EP2914776B1 - Decorative paper for layered products - Google Patents

Description

The present invention relates to the field of decorative papers.

In particular, the invention relates to a decorative paper, also called decor paper or decorative sheet, suitable for inkjet printing, a method of manufacturing such a paper, and a laminate comprising such a paper.

For many years, laminated decorative panels or profiles have been used as materials in homes, commercial and industrial premises. Typical applications of such laminates are floor coverings, particularly those imitating parquet, furniture coverings, tabletops or chairs, among others.

There are two main types of decorative "laminates": high-pressure laminates (HPL) and low-pressure laminates (LPL).

The high pressure decorative laminates are produced from a body of resin impregnated sheets. These sheets are generally made of kraft paper and have been impregnated with a thermosetting resin, most often a phenolic resin.

After impregnating the resin sheets, they are dried, cut, and stacked on top of one another. The number of sheets in the stack depends on the applications and typically ranges from 3 to 9, but may be higher. On the pile of sheets constituting the body, a decorative paper is then placed, which is generally a sheet of paper bearing a printed or colored pattern or comprising decorative particles, impregnated with a thermosetting resin, chosen from among the resins of melamine-formaldehyde, urea-formaldehyde, benzoguanamine-formaldehyde or unsaturated polyester paper.

In general, there is placed over the decorative paper, a protective sheet, called "overlay", devoid of patterns and transparent appearance in the final laminate, to improve the abrasion resistance of the laminate. The stack of impregnated sheets is then placed in a laminating press whose trays are provided with a sheet that confers the desired surface finish on the laminate. Then, the cell is densified by heating, at a temperature of the order of 110 ° C. to 170 ° C., and by pressing, at a pressure of the order of 5.5 MPa to 11 MPa, for approximately 25 to 60 minutes. minutes, to obtain a unitary structure.

This is then fixed on a base support; for example, it is glued on a panel of agglomerated particles, especially agglomerated wood particles.

It is possible to obtain high pressure laminates according to a so-called non-impregnation process , which consists in using a non-resin impregnated decorative paper. thermosetting, usually sandwiched between a resin impregnated barrier paper positioned underneath, and an overlay protective sheet also impregnated with resin and positioned above. There are variations where the overlay sheet is not placed above but below. The impregnation of the decorative paper with the resin occurs when pressure is exerted on the stack of the different sheets, by diffusion of the resin out of the sheets of the barrier paper and overlay with which the decorative paper is in contact or close.

In addition to the high-pressure and low-pressure processes, there is a continuous laminating process called CPL ( continuous pressed laminates ), which is similar to the high-pressure process but where impregnated papers rolled from coils are used instead. precut sheets.

The so-called low-pressure decorative laminates are produced using only a decorative sheet impregnated with thermosetting resin, and possibly an overlay sheet, which is laminated directly on the base support during a short cycle, the temperature being of the order of 160 to 175 ° C and the pressure of 1.25 MPa to 3 MPa.

The decorative paper used for the manufacture of laminates is generally a sheet of paper made on a paper machine. A decorative paper is generally used to impart a particular aesthetic appearance to the laminated support on which it is affixed, this aspect being able to result from the printing on paper of a decorative motif.

However, this decorative motif, which traditionally consisted of imitating the appearance of a natural material, such as wood or marble, took more diversified forms depending on the demand, so as to adapt to the needs and wishes client. This increase in the variety of reasons was accompanied by a contrario of a reduction of the quantities to be produced.

This phenomenon of customization of sets and production in small series has not been without consequences on the difficulties encountered by manufacturers of decorative papers. Indeed, for mass production of simple patterns, printing techniques such as gravure printing had the advantage of printing on large width at high rates. However, these printing techniques do not prove to be profitable for small series; in addition, the print result obtained is not sufficient for complex reasons that require a high resolution.

Among printing techniques that are flexible enough to produce small quantities on demand, inkjet printing has proven to be the most suitable technique for decorating papers. In addition to the simplicity of its implementation and the cost associated relatively low, the inkjet printing also allows to obtain better quality prints, including a very good image definition and a high color density with low ink consumption.

However, the use of the inkjet printing technique in the production of decorative papers still faces a major difficulty related to the process of obtaining the laminates themselves.

In the conventional process of making laminates, the decorative paper is first printed, then impregnated with resin and finally hot pressed with its support at high or low pressure. The impregnation step requires the provision of a decorative paper having a high resistance in the wet state, so as to maintain a sufficient resistance after its total immersion in the resin, which resin is preferably aqueous, as well as a resin absorption capacity as large as possible in the shortest possible time. These characteristics are generally obtained by using decorative papers having a very high porosity.

The inkjet printing technique is based today on the principle of fixing ink on the surface of the substrate to be printed; the latter must therefore, to obtain a clean and high quality print, have a controlled ink absorption. Thus papers usually used for inkjet printing outside the field of laminate manufacture for producing color prints, graphics or photographic quality prints have a closed surface produced by a synthetic resin coating or a coating. layer. Such papers can not therefore be suitable for the preparation of laminates since they can not be satisfactorily impregnated with a thermosetting resin. Also, these papers not falling under the category of decorative papers can not be suitable for the process of stratification without impregnation ("dry process"), because of the delamination of the various layers which occurs during the tests of resistance to the vapor of water and immersion in water.

It also appears that the decorative papers used in the past can not agree in the state for inkjet printing because of their high porosity, necessary for fast and uniform impregnation by the resin.

Decorative papers improved by a coating with a layer comprising ink-fixing particles have already been described, especially in patents EP 1 749 134 and EP 1 044 822 .

The patent EP 1 044 822 discloses the use of conventional coating techniques which can substantially reduce the impregnating properties of the paper by a resin due to the penetration of the layer into the paper.

The patent EP 1 749 134 claims a coating process for obtaining a printable decor paper inkjet without significant reduction of its impregnation properties. However, such a paper is not entirely satisfactory for the production of a high-pressure laminate by the non-impregnated lamination process because of the delamination that occurs during the water vapor and water resistance tests. immersion in water carried out on high-pressure laminates.

International demand WO 02/081228 discloses a decorative paper sheet for high or low pressure laminate, comprising in its thickness silica particles in order to improve the abrasion resistance of the paper. In this regard, the silica particles used have a relatively large diameter, which is too coarse to improve the printability properties of the paper.

As the state of the art reveals, the manufacture of a decorative paper allowing a good quality inkjet printing while having a high resin absorption capacity to manufacture high or low pressure laminates requires to achieve to meet contradictory requirements.

Also, the manufacture of a decorative paper allowing a good quality ink jet printing while being suitable for the preparation of laminates by laminating method without impregnation ("dry process") raises important difficulties.

The object of the invention is to remedy the problems encountered in the prior art by decorative laminate papers by proposing a decorative paper having both good printability in inkjet printing and suitable for the industrial production of all types of laminates. laminates, with or without prior impregnation of the decorative paper, in particular by the implementation of high-pressure, low-pressure or non-impregnation processes.

Thus, the invention relates to a decorative paper for decorative laminate high-pressure (HPL), low-pressure (LPL), or continuous laminate (CPL), comprising, distributed in the thickness of said paper, particles of a filler having a relatively high oil absorption, preferably greater than or equal to 80%. These filler particles can still be called "pigment" particles, even if they do not necessarily bring color to the paper.

Unexpectedly, the applicant has observed that it is possible to obtain decorative papers having good printability by inkjet printing, and which may be impregnated with a thermosetting resin for the production of conventional high or low pressure laminates, or continuously laminated, or which may be used in a non-impregnated process, by incorporating into the decorative paper a particulate filler chosen for its properties of oil absorption.

As evidenced by the results of tests carried out with the examples of paper decorations detailed below, the decorative papers according to the invention have good printability by inkjet printing whatever the nature of the ink, aqueous, crosslinkable under UV, or in solution in an organic solvent or an eco solvent. Moreover, this good printability is achieved without the need to first deposit on paper an ink-fixing layer, which simplifies the manufacture of decorative paper. In addition, the decorative paper according to the invention becomes compatible with printing on one and / or the other of its faces, which is not the case of a decorative paper according to the prior art, lying on a face. Finally, such a paper can quite suit the preparation of laminate without impregnation.

The invention also relates to a decorative paper comprising, before its impregnation with a thermosetting resin, at least one pattern printed on at least one of its faces. Such a pattern may be printed by inkjet printing, preferably with an aqueous ink, a UV curable ink, a solvent or eco solvent ink.

• préparer une composition fibreuse de cellulose humide, et
• introduire dans la composition fibreuse, en partie humide d'une machine à papier, des particules d'une charge selon l'invention.

According to yet another of its objects, the invention relates to a process for preparing a decorative paper, comprising the steps of:

• prepare a fibrous composition of wet cellulose, and
• introducing into the fibrous composition, in the wet part of a paper machine, particles of a filler according to the invention.

According to yet another of its objects, the invention relates to a high laminate, low pressure or continuous laminate, comprising at least one decorative paper according to the invention.

According to yet another of its objects, the invention relates to a use of particles of a filler according to the invention in a decorative paper for decorative laminate high-pressure, low-pressure or continuous laminate, to improve printability by printing inkjet of said decorative paper.

Charge

For the purposes of the invention, the term "charge particles" or "charge" means particles of a single type of particulate material or a mixture of particles of different types of particulate materials. Preferably, the filler consists of a single particulate material.

The particles of a filler suitable for the invention have an oil absorption greater than or equal to 80%, better still greater than or equal to 100%, preferably greater than or equal to 150%, preferably greater than or equal to 200%, and more preferably greater than or equal to 300%.

The particles of the filler of the invention can have an absorption of oil at most equal to 400%, or even at most equal to 360%.

The oil absorption property of the load according to the invention is measured according to DIN ISO 787 part 5.

The particles of the filler suitable for the invention preferably have a specific surface greater than or equal to 10 m ² / g, preferably greater than or equal to 20 m ² / g, preferably greater than or equal to 50 m ² / g, preferably greater than or equal to 80 m ² / g, preferably greater than or equal to 100 m ² / g, more preferably greater than or equal to 200 m ² / g, and more preferably still greater than or equal to 300 m ² / g.

The particles of the filler according to the invention may have a specific surface at most equal to 1000 m ² / g, preferably at most equal to 800 m ² / g.

The specific surface area of the particles of a filler suitable for the invention is measured by the BET method according to DIN 66132.

The particles of a filler suitable for the invention may have a diameter ranging from 0.5 to 10 μm, preferably ranging from 2 to 8 μm, and more preferably ranging from 3 to 5 μm. By "diameter" is meant the diameter of the circumscribed circle.

The particles of a filler suitable for the invention preferably have a median diameter D 50 ranging from 0.5 to 10 μm, preferably from 2 to 8 μm, and more preferably varying from 3 to 5 μm.

Also, charge particles that are suitable for the invention may have a median diameter D50 ranging from 1 to 3 μm.

The particles of a filler suitable for the invention may have a form chosen from a lamellar form, a globular form, a spherical form, or any intermediate form between the previously defined forms. Preferably, the shape of the particles is substantially spherical.

Preferably, the particles of a filler suitable for the invention have a refractive index n of less than 1.9, and preferably ranging from 1.2 to 1.8, and more preferably varying from 1.4 to 1. , 7, and more preferably still ranging from 1.5 to 1.6. Of more preferably, the particles of a filler suitable for the invention have a refractive index n of about 1.55.

The refractive index is measured using a refractometer, the best known of which is that of Abbe.

Advantageously, the particles of a filler of the invention will be chosen so as to have a refractive index equal to, or substantially close to, the refractive index of the thermosetting resin intended to impregnate the decorative paper of the invention.

Thus, between a charge of the invention and a thermosetting resin, the difference Δ _n between the refractive indices may advantageously be less than or equal to 0.5, better still less than or equal to 0.3, more preferably less than or equal to 0 , 2, or even less than or equal to 0.1.

The identity, or the proximity, of the values of the refractive index of the charge and of the refractive index of the thermosetting resin may make it possible to confer an increased transparency on the decorative paper after it has been impregnated with the resin.

The particles of a filler according to the invention may be chosen from inorganic particles, organic particles, and mixtures thereof. Preferably, the particles of the filler are selected from mineral particles, or mixtures thereof.

Most preferably, the mineral particles of a filler according to the invention have a specific surface area greater than or equal to 50 m ² / g and an oil absorption greater than or equal to 80%, preferably a higher specific surface area or equal to 100 m ² / g and an oil absorption greater than or equal to 80%, more preferably a specific surface area greater than or equal to 200 m ² / g and an oil absorption greater than or equal to 80%, preferably a specific surface greater than or equal to 200 m ² / g and an oil absorption greater than or equal to 150%, and even more preferably a specific surface greater than or equal to 300 m ² / g and an oil absorption greater than or equal to at 200%.

The mineral particles of a pigmented filler of the invention may be selected from amorphous silica particles, precipitated silica particles, diatomaceous earth particles, silico-aluminate particles, and mixtures thereof. . Preferably, such particles are selected from amorphous silica particles, precipitated silica particles, silico-aluminate particles, and mixtures thereof. More preferably, such particles are selected from amorphous silica particles, precipitated silica particles, and mixtures thereof, and more more preferably, they are selected from amorphous silica particles, and mixtures thereof.

Of inorganic filler particles suitable for the invention may be selected from particles of amorphous silica or precipitated types of Syloid ^® sold by the company GRACE, soil particles Celite ^® diatomaceous type marketed by World Minerals, or particles Zeolex ^® type silico-aluminates marketed by Huber Engineered Materials.

Advantageously, the particles of a filler according to the invention are present in an amount ranging from 3 to 40% by weight relative to the total dry weight of the paper, preferably ranging from 5 to 35%, more preferably from 8 to 30% by weight. %, preferably ranging from 10 to 30%, more preferably varying from 10 to 25%, more preferably still varying from 15 to 25%, and more preferably ranging from 15 to 20% by weight relative to the total dry weight of the paper .

The charge weight, for a mineral filler, of a paper of the invention is determined by measuring the ash content of the paper according to ISO 2144: 1997, corrected by the loss on ignition of the load used which must be known. .

A decorative paper according to the invention may comprise a single type of particles of a filler suitable for the invention, or a mixture of different types of filler particles, for example at least two or even at least three, or at least four types of charge particles. The term "different types of charge particles" means particles of charges which differ from each other by their characteristic of oil absorption and / or specific surface area.

It is understood that when a decorative paper according to the invention comprises more than one type of particles of a filler according to the invention, in particular at least two or even at least three, or at least four distinct types of particles. according to the invention, that is to say, in terms of oil absorption, the quantities indicated above must be understood as being directed to the mixture of these particles, and not to each type of particles taken individually .

According to a preferred embodiment, for an ink jet printing with an aqueous ink, a decorative paper of the invention advantageously comprises mineral filler particles selected from amorphous silica particles, particles of precipitated silicas , silico-aluminate particles, and mixtures thereof. Preferably, amorphous silica particles, precipitated silica particles or mixtures thereof are used in such an embodiment.

Advantageously, these particles are used in a content ranging from 15 to 25%, and more preferably in a content of about 20% by weight relative to the total dry weight of the paper.

According to another preferred embodiment, for an ink jet printing with a crosslinkable UV ink, a decorative paper of the invention advantageously comprises mineral filler particles selected from amorphous silica particles, particles of precipitated silicas, and mixtures thereof.

Advantageously, these particles are used in a content ranging from 15 to 25% by weight relative to the total dry weight of the paper

The above filler particle contents are given for dry paper, before printing and before impregnation thereof with a thermosetting resin.

The fillers, in particular the mineral fillers, used in the invention preferably have a neutrality in terms of acidity or alkalinity vis-à-vis the thermosetting resins. By "neutrality in terms of acidity or alkalinity" of the fillers according to the invention with respect to thermosetting resins is meant that the fillers behave neither as acids nor as bases vis-à-vis -vis thermosetting resins.

Decorative paper

A decorative paper according to the invention may have a basis weight ranging from 20 to 100 g / m ² and preferably from 40 to 80 g / m ² .

The basis weight of the sheets is determined according to ISO 536 after conditioning according to ISO 187. This is the grammage of the sheet before impregnation with a thermosetting resin.

A decorative paper according to the invention comprises, distributed in the thickness of the paper, particles of a filler, as defined above.

Unlike a coated decorative paper according to the prior art, a paper according to the invention comprises filler particles according to the invention in its core. On the other hand, a decorative paper coated according to the prior art only has charge particles in the layer deposited on the surface.

The profile of the particle distribution in the paper thickness may depend on how the particles are introduced into the paper.

The distribution profile of the filler particles in a paper of the invention shows that they are present in the paperboard substrate.

The distribution profile of the load in the decorative papers of the invention can pass through a maximum substantially between 1/4 and 3/4 of the total thickness e of the paper.

The distribution of the filler particles in the paper thickness may have a pattern of increasing distribution between one side of the paper to half the thickness of said paper.

The distribution profile of the filler particles may have a maximum between one side and half the thickness of the paper.

The distribution of the filler particles can be anisotropic within the paper.

The distribution profile is unsymmetrical with respect to a median plane cutting the paper at mid-thickness.

The distribution pattern of the filler particles in the paper thickness of the invention has a minimum on the face side of the paper in contact with the web or forming surface, and a maximum on the side of the opposite side.

The determination of a mean distribution profile of the charge particles in a paper can be carried out by analysis of electron microscopy images taken in backscattered electron detection mode or elementary mappings acquired in microanalysis X in a SEM (scanning microscope electronic). Paper cups are prepared in such a way that several centimeters of sample can be observed. Several dozens of images are acquired along these sections, about thirty are in general sufficient, and are then processed by image analysis. The edges of the paper are first identified to extract the paper area. The latter is then automatically divided into twenty layers of equal thickness in any abscissa along the paper area extracted: thus obtaining slices each corresponding to a given depth within the paper. Mineral fillers present in the paper area are then extracted in turn and assigned to the depth range in which they are located. It is then sufficient to count the proportion of charges in each slice to obtain a relative distribution of the mineral charges from one side to the other of the paper. The relative distributions obtained for each image are averaged and finally produce the average relative distribution curve of the mineral charges for the paper analyzed.

For example, there is shown in the figure 1 the profile of the average relative distribution of the silica particles of example 4 of the patent EP 1749 134 in the thickness of the paper. It can be seen that the silica particles remain confined to the surface in the coating coating R and are absent from the papermaking substrate P.

The Figures 2A and 2B represent, respectively, two examples of average relative distribution profiles of the filler particles in the thickness of decorative papers according to the invention obtained by mass introduction ( Figure 2A ), i.e. mixing the filler particles with the fibrous cellulose composition prior to deposition on the forming surface, or spraying a solution containing the filler onto the fibrous cellulose composition on a forming table. wet phase of a paper machine ( Figure 2B ).

In a paper of the invention obtained by mixing the filler with a fibrous cellulose composition before depositing on a formation surface ( Figure 2A ), the maximum of the distribution profile of the charges is at substantially mid-thickness of the paper.

In a paper of the invention obtained by spraying the filler on a fibrous cellulose composition before depositing on a forming surface ( Figure 2B ), the maximum of the distribution profile of the charge is substantially in the quarter of the thickness from the face having received the particles of charge.

A decorative paper according to the invention has, in particular, the characteristic of being printable, in particular by inkjet printing, while maintaining thermosetting resin absorption properties identical or similar to those of known decorative papers.

Because of the distribution of the load in its thickness, a paper of the invention has the advantage of being able to be printed indifferently on one or the other of its faces, even on its two faces, which can make it possible to create optical depth effects due to the transparency of the paper on the laminate.

The impregnation of a decorative paper according to the invention with a thermosetting resin is advantageously after an inkjet printing step of this paper.

A decorative paper according to the invention may have a speed of impregnation with a thermosetting resin, as defined below, less than or equal to 20 seconds, preferably less than or equal to 10 seconds, preferably ranging from 2 to 20 seconds. , more preferably varying from 3 to 10 seconds, and more preferably varying from 3 to 6 seconds, in particular on each of its faces.

• on prépare une solution de résine à 56 % en poids en dissolvant de la résine mélamine-formaldéhyde KAURAMIN 773 en poudre dans de l'eau distillée chauffée vers 45°C. On ajuste sa viscosité telle qu'elle soit de l'ordre de 100 mPas (cps) vers 20°C sur viscosimètre Brookfield mesurée à 100 tours/min - Arbre N° 2,
• on détermine comme suit le temps d'imprégnation d'une feuille de papier:
• on découpe deux échantillons en carré (10 x 10 cm) par essai ; pour tester chaque face, on repère la face,
• on remplit un verre de montre de résine,
• on dépose le carré de papier sur la surface de la résine, la face à tester en contact avec celle-ci, et on déclenche le chronomètre en même temps,
• on note le temps du transpercement total qui donne le temps de pénétration de la résine.

The rate of impregnation is characterized by determining the penetration time of the thermosetting resin through the sheet; this time is determined as follows:

• a 56% by weight resin solution is prepared by dissolving KAURAMIN 773 melamine-formaldehyde resin powder in distilled water heated to 45 ° C. Its viscosity is adjusted such that it is of the order of 100 mPas (cps) at 20 ° C. on a Brookfield viscometer measured at 100 revolutions / min.
• the impregnation time of a sheet of paper is determined as follows:
• two square samples (10 x 10 cm) are cut per test; to test each face, we find the face,
• we fill a glass of resin watch,
• depositing the square of paper on the surface of the resin, the face to be tested in contact therewith, and the stopwatch is started at the same time,
• we note the time of the total piercing which gives the penetration time of the resin.

A decorative paper according to the invention can have a Gurley porosity of 5 to 50 seconds, ideally 10 to 20 seconds. The air permeability, or Gurley porosity method, is determined according to ISO 5636-5R (1990).

A decorative paper of the invention can be smoothed or non-smoothed. A decorative paper according to the invention can be smoothed by any method known to those skilled in the art.

According to one embodiment, a decorative paper of the invention has, on at least one of its faces, a Bekk smoothness of 20 to 140 seconds.

A decorative paper according to the invention may be devoid of filler particles other than those defined above. In other words, the decorative paper of the invention can comprise only as particulate filler filler particles according to the invention, that is to say a decorative paper according to the invention can be free of mineral fillers or organic other than those with an oil absorption greater than or equal to 80%. In particular, a paper according to the invention may be devoid of TiO ₂ particles.

Alternatively, a decorative paper of the invention may comprise in its matrix a filler other than according to the invention, such as kaolin particles. Such an embodiment makes it possible to reduce the amount of cellulose in the paper and can result in a reduction in paper production costs. The amount of such a substitute filler can range from 0 to 35% by weight, based on the dry weight of the paper.

The decorative paper according to the invention does not require the removal of an ink-fixing layer by coating, as in the prior art, fixing layer which comprises a binder.

Thus, a decorative paper of the invention is advantageously devoid of ink-fixing surface layer, and associated compounds, typically an acrylic binder, polyvinyl alcohol, polyvinyl acetate, and titanium dioxide. .

The opacity of a decorative paper according to the invention is preferably relatively low.

A decorative paper of the invention may advantageously be, before or after impregnation with a thermosetting resin, and preferably after impregnation, transparent.

The opacity of the papers is measured according to ISO 2471. The luminance of the paper sample (L ₀ ) is measured under a black background, the luminance at infinity (L _∞ ) is measured on a stack of the same paper. The opacity is calculated according to the formula: L ₀ / L _∞ * 100.

The lower the value obtained, the less opaque the paper, and therefore the more transparent it is.

A decorative paper according to the invention may have, prior to impregnation with the thermosetting resin and before inkjet printing, opacity L ₀ / L _∞ * 100 greater than 60%, in particular ranging from 60 to 90%, or even 70 to 90%.

A high pressure or low pressure laminate obtained with a decorative paper according to the invention may comprise one or more layers having a certain transparency.

Opacity measurement on high-pressure (HP) or low-pressure laminates (BP) is performed in a manner similar to that performed on decor paper. The measurement of the luminance L ₀ of the laminate is made kraft side, the measurement of the luminance of the laminate to infinity (L _∞ ) is made on a white background. The opacity is calculated according to the formula: L ₀ / L _∞ * 100. The lower the value obtained, the less opaque the paper, or the more transparent it is.

A high pressure or low pressure laminate obtained with a decorative paper according to the invention may have an opacity L ₀ / L _∞ * 100 less than 20%, in particular ranging from 7 to 15%.

A paper according to the invention may have the advantage of not providing little or no opacity, and may be used with a white or colored background sheet to which it is superimposed. This offers additional decorative possibilities, namely to allow to use the same decorative paper printed and laminated on different colored backgrounds.

According to an alternative embodiment, a decorative paper of the invention is used in combination with a colored decorative paper. Such a decorative colored paper is for example disposed between the decorative paper of the invention (placed above) and the body of the laminate considered (placed below).

By "colored paper" is meant any decorative paper having a non-white shade other than a white shade. For example, a colored decorative paper is a paper of red, blue, green or even black tint.

A decorative paper according to the invention may comprise a pattern printed on at least one of its faces. The printing of this pattern is advantageously carried out by means of inkjet printing. The pattern is printed after the drying step and prior to its impregnation with the thermosetting resin.

A decorative paper of the invention may furthermore comprise the usual components used in the formulation of decorative papers.

Other components

A decorative paper of the invention naturally comprises cellulosic fibers.

The cellulosic fibers can be a mixture of short celluloses and long celluloses

Advantageously, a decorative paper of the invention comprises a mixture of cellulosic fibers comprising from 40 to 100%, preferably 70 to 90%, or even about 80% of short cellulose fibers, and from 0 to 60%, preferably from 10 to 30%, even about 20% of long celluloses in dry weight

According to one embodiment, the short celluloses fibers are eucalyptus fibers.

According to one embodiment, a decorative paper of the invention is devoid of synthetic fibers.

A decorative paper of the invention may comprise at least one additional agent selected from the group consisting of a wet strength agent, a retention agent, decorative particles, fillers, a cationic polymer, an absorbent organic polymer.

A decorative paper of the invention may comprise at least one wet strength agent.

By "wet strength agent" is meant any agent capable of giving the paper in the wet state a tensile strength. Such agents are known to those skilled in the art. Preferably, such an agent may be a polyamine epichlorohydrin resin, a resin polyamide / polyamine-epichlorohydrin, a cationic polyacrylate, a modified melamine-formaldehyde resin or a cationic starch.

A wet strength agent may be present in a proportion of 0.2 to 2.5% by weight relative to the dry weight of the sheet, and more preferably from 0.4 to 0.8%.

A decorative paper of the invention may comprise in its composition at least one retention agent.

By "retention agent" is meant any agent capable of allowing the fixing of mineral fillers on the fibers. Such agents are known to those skilled in the art. Preferably, such an agent may be selected from the group consisting of a system of inorganic microparticles, for example anionic silicas, and a polyacrylamide of low ionicity.

By "low ionicity" with respect to a polyacrylamide that is suitable for the invention, is meant a polyacrylamide containing few quaternary ammonium type cationic comonomers and / or few anionic acrylate groups.

In addition, a decorative paper may comprise the optional agents used to put the fillers of the invention in aqueous dispersion, as described below.

A decorative paper of the invention, after drying and before printing, in particular by inkjet, may be subject to a surface treatment, for example to improve its smoothness or deposit an agent to improve the fixing of inks. By "surface treatment" is meant to subject a paper of the invention to a process that affects the one in the superficial part of its thickness. Thus, a surface treatment of a paper according to the invention with a chemical agent leads to the penetration of the latter into the thickness of the paper. We can speak of penetrating coating. Such a method is distinct from the surface coating which leads to depositing a layer on the surface of the paper, without it being intended to penetrate into the thickness of the latter.

According to one embodiment, a paper of the invention may be surface-treated with at least one agent intended to improve or promote the fixing of the inks. However, as previously stated, a decorative paper of the invention may be devoid of ink-fixing layer. The agents that can be used in a surface treatment of a paper of the invention are not intended to fix the inks, but are only intended to promote their fixation. The primary fixing effect of the inks is obtained by means of the load according to the invention distributed in the matrix thereof. An agent to be put in a surface treatment of a paper of the invention may be devoid of particles in accordance with the invention, and / or other inorganic or organic particulate fillers

A decorative paper of the invention may be surface-treated (penetrating coating) with at least one cationic polymer.

Such polymers are known to those skilled in the art, and may advantageously be used to prevent water inks, and in particular aqueous inks, from being disgorged in water. Preferably, such a polymer may be selected from the group consisting of a polyamine, a copolymer of epichlorohydrin and dimethylamine, and a polydiallyldimethylammonium clhorure. More preferably, such a polymer may be a polydiallyldimethylammonium chloride.

A decorative paper of the invention can be surface treated (penetrating coating) with at least one absorbent organic polymer.

Such polymers are known to those skilled in the art, and may be advantageously used to fix the inks on the surface. Preferably, such a polymer may be selected from the group consisting of polyvinylpyrrolidone, polyvinyl alcohol, carboxymethylcellulose, and microcrystalline cellulose. More preferably, such a polymer may be a microcrystalline cellulose.

As previously described, during the manufacture of high pressure, low pressure or continuous laminate laminates, the decorative paper is generally first printed, then impregnated with a thermally stable thermosetting resin, and finally heat pressed with its support at high or low pressure. Alternatively, as previously described, in the case of the process without impregnation (dry process), the printed decorative paper is stacked, non-impregnated, between two papers impregnated with thermosetting resin, and the impregnation of the decorative paper is performed during the pressure exerted on the whole pile.

Accordingly, a decorative paper of the invention can be used with or without thermosetting resin.

In particular, this thermosetting resin may be chosen from melamine-formaldehyde resins, urea-formaldehyde resins, benzoguanamine-formaldehyde resins, unsaturated polyester resins, dicyandiamide-formaldehyde resins, epoxy resins, polyurethane resins, resins acrylics, and mixtures thereof.

Once impregnated with resin, the decorative paper is heated, the resin is partially crosslinked (thermoset) so that it is no longer in a sticky state and that the sheet is manipulable. A decorative paper impregnated with partially crosslinked resin is called, in terms of trade, "decorative film" or "decorative film or" melamine film "This melamine film contains a resin content preferably ranging from 50 to 55% but may range from 45 to 65%.

This step is generally carried out by carrying the decorative paper at temperatures of about 110 to 140 ° C and is controlled, so that the resin, during the final lamination of the decorative film, flows correctly into the sheet, by the measurement of the remaining volatiles in the film décor. Indeed, this decor film then comprises a certain percentage, of the order of 5 to 8%, of volatile products (solvent water of the resin, water resulting from the chemical condensation of the resin, residual formaldehyde, the other residual products, ...). These volatiles represent the compounds that will be removed during the total crosslinking of the resin, during the lamination of the decor film.

The resin, once fully cross-linked, after lamination, will provide surface resistance to the final laminate (abrasion resistance, soil resistance, water vapor and chemical agents such as solvents, acids and alkalis). bases, ...).

According to one particular case, a decorative paper of the invention is impregnated with a thermosetting resin, and then the resin is partially crosslinked in an acid medium, the content of volatile compounds being between 5 and 8% by weight of the sheet.

The invention also relates to a laminated decorative panel or profile comprising at least one decorative paper of the invention.

A laminate according to the invention may comprise a superposition, by contact, of at least two, preferably at least three, and more preferably at least four, decorative papers according to the invention.

The presence of a decorative paper comprising at least one pattern printed on two sides, or the superposition of a plurality of decorative papers of the invention each comprising at least one pattern printed on at least one face may advantageously make it possible to create an optical effect of relief.

In such an embodiment, the sheets of decorative paper of the invention are printed, with at least one pattern, on one or both sides, impregnated with thermosetting resin, then stacked on one another, and placed on a support, according to the case of sheets of kraft paper impregnated with thermosetting resin or a panel of agglomerated particles, and possibly covered with an overlay also impregnated with resin, before being pressed.

Between the support and the stack of decorative paper sheets, it is advantageous to have a colored sheet of decorative paper, also impregnated with the resin.

Manufacturing process

The fibrous base of a decorative paper of the invention, comprising cellulose fibers, may be prepared by any method known to those skilled in the art.

Thus, in the first place is prepared a fibrous composition of cellulose, or pulp, wet.

The filler particles of the invention can be introduced into the fibrous wet cellulose composition, if necessary supplemented with the agents indicated above, during the continuous manufacture of the pulp, in the wet part of the machine. paper.

Within the meaning of the invention, the term "wet part" with respect to a paper machine, any part of the paper machine in the papermaking process positioned before the dryer, and in particular before the section of presses.

The filler particles may be introduced in the form of a powder or in the form of a dispersion, preferably aqueous.

Preferably, the particles are introduced in the form of a dispersion, in particular an aqueous dispersion, which may comprise any agent capable of promoting the stability of this dispersion. For example, the aqueous dispersion comprises, in addition to the filler particles of the invention, an agent for preventing settling or flocculation of the particles or a surfactant, or a viscosity agent. For example, it is possible to use carboxymethylcellulose, microcrystalline cellulose, sodium alginate, hydroxypropyl cellulose, polyvinyl alcohol, starch or mixtures thereof. Polycarboxylates may also be mentioned; cellulosic thickeners, such as methyl, ethyl, hydroxyethyl and hydroxypropyl cellulose, natural gums, in particular guar gum, gum arabic, agar gum, pectins; proteins, including casein, soy protein, gelatin.

According to a preferred variant embodiment, the aqueous dispersion of filler particles consists, substantially, of a mixture of water and of said filler particles. "Substantially" is intended to indicate that the dispersion is obtained by mixing only water and filler particles, but it is not possible to rule out the presence of contaminants or impurities naturally present in the water and / or the charge particles, but which do not affect the properties of the aqueous dispersion or decorative paper of the invention.

When the fillers are introduced as a dispersion in the fibrous composition, the dispersion can contain from 5 to 40% by weight of filler particles.

According to one embodiment, the filler particles are mixed with the fibrous cellulose composition before it is deposited on the forming surface.

This mixing can be achieved, for example, at the level of the pulp chamber, the headbox, a storage tank, at the level of the refiners, or the mixing pump.

The introduction of the filler particles into the fibrous cellulose composition may be carried out by mixing, especially continuously, with the fibrous composition, before the headbox.

According to one embodiment, such a mixture can be carried out in a pulp box.

According to another embodiment, the filler particles according to the invention are introduced into the fibrous composition after deposition of said composition on a forming surface. A training surface suitable for the invention may be a Fourdrinier table.

The pigment particles may be introduced into the fibrous cellulose composition by means of application devices such as a second headbox, a slit device, or a spraying device.

These applicators are placed at any position before the wet press section, i.e. in the wet part of the paper machine.

According to one embodiment, the filler particles may be introduced into a fibrous cellulose composition, arranged in the form of a mattress on the forming surface, by means of a secondary headbox or by means of a slit coater, and more particularly by means of a curtain coating head.

For the purposes of the invention, the term "slit coater or slit orifice" refers to coating heads in which the dispersion to be deposited passes through an orifice and forms a curtain which falls on the fibrous cellulose composition. , or paper pulp, before the section of wet presses.

In another embodiment, the filler particles may be sprayed into a fibrous wet cellulose composition at any location prior to the wet press section.

The filler particles are preferably sprayed at a pressure and / or velocity sufficient to allow them to penetrate the paper pulp.

According to an alternative embodiment, the filler particles of the invention are introduced into the paper pulp by means of a combination of the various application devices above, before the section of wet presses.

A process for preparing a decorative paper of the invention may comprise a step of adding a wet strength agent and / or a retention agent as defined above.

Preferably, the wet strength agent is a polyamine epichlorohydrin resin, and the retention agent may be a system of inorganic microparticles, for example anionic silicas, or a polyacrylamide of low ionicity.

The fibrous cellulose composition, or pulp, incorporating the filler particles of the invention, and any additional agents, can then be subjected to any drying step usually carried out in the paper industry to obtain a sheet of paper. decorative.

A process for preparing a paper according to the invention comprises a drying step which can be carried out by any method known to those skilled in the art, and usually carried out in the field. Such methods therefore do not need to be described further here.

A process for preparing a decorative paper of the invention may further comprise an additional step of surface treatment of the paper.

Such a treatment may be a physical treatment, for example to improve the smoothness of the paper, or be a chemical treatment, for example a penetrating coating. A penetrating coating may for example consist in treating the surface of a paper with an agent for promoting the retention of the ink as described above. This step can in particular be carried out by "size-press" or "film press".

According to a particular embodiment, a method according to the invention may comprise a surface treatment step, in particular by penetrating coating.

A surface treatment may consist in carrying out a penetrating coating of any agent normally used in the field. In particular, the deposited layer may comprise at least one agent selected from the group consisting of a cationic polymer and an absorbent organic polymer. The cationic and organic polymers may, in particular, be as defined above.

According to one embodiment, a surface treatment step, in particular by penetrating coating, can advantageously be carried out with at least one cationic polymer or at least one absorbent organic polymer, as described above, and preferably with polydiallyldimethylammonium, or a cellulose microcrystalline.

A paper of the invention may advantageously be used to prepare a high or low pressure laminate, or a continuous laminate.

In the case of a high-pressure laminate, the basic components of the laminate are kraft sheets impregnated with thermosetting resin and the decorative paper of the invention whether or not impregnated with a thermosetting resin.

In the case of a low pressure laminate, the basic components of the laminate are the support panel, such as a chipboard, and a decorative paper of the invention whether or not impregnated with a thermosetting resin.

The figure 3A represents in section the constituents of a low-pressure laminate, placed between the plates W of a press, comprising a decorative paper 22 according to the invention, impregnated with a thermosetting resin, and possibly printed with a jet pattern ink on at least one of its faces, and a particle board 23.

The figure 3B represents in section the constituents of a high pressure laminate. The laminate comprises an overlay 26, a stack of decorative papers 22 according to the invention, optionally comprising at least one inkjet printed pattern on at least one of their faces. A stack of several decorative papers 22 each carrying at least one printed pattern on at least one of their faces is advantageous in that it can be used to create a 3D optical effect. The stack of decorative papers 22 is deposited on a stack 28 of sheets of craft paper, itself deposited on a so-called "counterbalancing" sheet. The different leaves are each impregnated with a thermosetting resin. According to a non-illustrated embodiment the overlay 26 and / or the sheet 29 are absent.

The figure 3C illustrates the sizing of a laminate 31 of the invention, for example as described in figure 3B on a support 23 by means of an adhesive 32.

The examples presented below are given by way of illustration of the invention and should not be interpreted in a limiting manner.

EXAMPLES Example 1 a- Preparation of decorative papers

A mixture of cellulose fibers comprising 20% by weight of long staple fibers of bleached softwood kraft pulp type Spruce, and 80% by weight of short staple fibers of bleached kraft pulp of Eucalyptus is suspended in an aqueous phase.

The suspension is subjected to a refining step to obtain a Gurley porosity of 15 sec.

To this suspension are added separately the various fillers according to the nature and the contents indicated (expressed in% of ash at 800 ° C) below. The fillers are introduced in the form of an aqueous dispersion at 15% by weight. Then added a polyamide epichlorohydrin wet strength agent at the rate of 0.6% dry. To finish at the top of the machine is introduced a retention agent of silica microparticle type at a rate of 0.5% dry.

The paper (C) is obtained according to the process described in the patent EP 1 749 134 and corresponds to Example 4 of this patent.

By a common papermaking process, a plain smooth white decorative paper having a grammage of 80 g / m, a Gurley porosity of 20 s, a Bekk satin of 20 s, and containing 38% ash, is manufactured on a machine Fourdrinier type paper. This support thus constituted is a standard paper (A).

This paper is then coated by the coating process on one of its faces with 10 g / m ² dry weight of an inkjet printing layer composed of 28.6 parts of the binder made of a mixing a hydrophilic aqueous solution of polyvinyl alcohol (PVA) and a polyvinyl acetate in stabilized aqueous dispersion (said latex), respectively in proportions 85/15 by dry weight and 100 parts of a silica coating (amorphous) having an average particle size of 5.3-6.3 μm and a specific surface area (BET) of 160 m ² / g. This coated paper is paper (C). <i><u> Table 1 </ u></i> Paper Load type (BET surface area & oil absorption) Content% by weight of dry paper Standard (A) (except invention) TiO ₂ RCL 722 20 100% cellulose (B) (except invention) Without charge 0 1 Syloid ^® (BET 400 m ² / g and 320% oil absorption) 10 2 15 3 20 4 25 6 Syloid ^® (BET 400 m ² / g and 180% oil absorption) 20 7 Syloid ^® (BET 700 m ² / g and oil absorption 80%) 20 8 Celite ^® (BET 10 m ² / g and oil absorption 130%) 20 9 Silico-aluminate (BET 100 m ² / g and oil absorption 80%) 20 10 (except invention) Silico-aluminate (BET 4 m ² / g and oil absorption 62%) 20 M-Jet (Patent EP 1 749 134 - Example 4) (C) (except invention) Coated paper

b- Printing

The papers prepared above were printed by inkjet printing with aqueous inks on a Hewlett Packard (HP) Deskjet 6540 printer and with UV curable inks using a Jupiter plotter Digital printing of the company HYMMEN.

c- Color density measurement and visual analysis

The color density of the printed papers was measured using an X rite 500 densitometer in yellow, black, magenta and cyan.

The visual analysis of the printed papers was carried out using an observer panel that performed a good or bad ranking according to the fineness of the ink dots.

The results obtained are detailed in Tables 2 and 3 below. <i><u> Table 2: </ u></i> printing with an aqueous ink Paper Density of color Visual analysis Magenta Yellow cyan Black definition Standard (A) (except invention) 0.74 0.67 1.02 1.16 Bad 100% cellulose (B) (except invention) 1.42 0.99 1.24 1.9 Way 1 1.37 0.89 1.28 1.87 Well 2 1.37 0.88 1.29 1.83 Very good 3 1.4 0.86 1.29 1.87 Very good 4 1.4 0.86 1.3 1.89 Very good 6 1.24 0.84 1.17 1.74 Very good 7 1.48 0.98 1.29 1.8 Well 8 1.46 0.97 1.34 1.77 Well 9 1.49 0.94 1.39 1.74 Very good 10 (except invention) 1.42 0.92 1.26 1.57 Way M-Jet (Patent EP 1 749 134 - Example 4) (C) (except invention) 1.38 0.88 1.27 1.88 Excellent

The results obtained show that the fillers specifically selected for the invention allow the preparation of a decorative paper, suitable for inkjet printing with an aqueous ink without the need to implement a printing fixing layer as in the prior art. <i><u> Table 3 </ u></i>: printing with a UV curable ink Paper Density of color Visual analysis cyan magenta yellow black Definition Standard (A) (except invention) 0.71 0.55 0.44 0.58 Bad 100% cellulose (B) (except invention) 1.44 1.12 0.73 1.12 Very bad 1 1.27 1.04 0.68 0.96 Well 2 1.18 0.96 0.62 0.88 Very good 3 1.11 0.94 0.6 0.82 Very good 4 1.09 0.9 0.57 0.8 Very good 6 1.09 0.86 0.58 0.88 Well 7 1.41 1.01 0.67 1.15 Way 8 1.43 1.08 0.69 1.18 Way 9 1.29 0.96 0.6 1.04 Way 10 (except invention) 1.33 1.01 0.65 1.1 Bad M-Jet (Patent EP 1 749 134 - Example 4) (C) (except invention) 0.95 0.87 0.57 0.76 Very good

The results obtained show that the fillers specifically selected for the invention allow the preparation of a decorative paper, suitable for inkjet printing with a UV curable ink, without the need to implement a layer. ink fixer. Charges that do not have these properties give a good print intensity but a poor definition.

Example 2

In this example are measured on the papers prepared in Example 1, the opacity before impregnation with a thermosetting resin, and the time of impregnation of these papers with a thermosetting resin.

By means of these papers high-pressure laminates are prepared by a usual method. The high-pressure laminates prepared include 10 sheets of craft paper and 10 sheets of decorative papers.

The results of the various measurements made are summarized in Table 4 below. <i><u> Table 4 </ u></i> Paper Penetration time (sec) according to measurement method defined above Opacity% Decor Side Back Side Paper Laminate Standard (A) (except invention) 2 3 97.6 93.5 100% cellulose (B) (except invention) 1 1 64.2 10.5 2 4 4 81.7 11.7 M-Jet (Patent EP 1 749 134 - Example 4) (C) (except invention) 32 7 99.2 95.6

Claims (15)

1. A decorative paper for a high-pressure, low-pressure or continuous-pressed decorative laminate, comprising, distributed through the thickness of said paper, particles of a filler having an oil absorption of greater than or equal to 80% measured according to standard DIN ISO 787 part 5, and having a median diameter D50 ranging from 0.5 to 10 µm.
2. The decorative paper as claimed in the preceding claim, the particles of filler having an oil absorption greater than or equal to 100%, preferably greater than or equal to 150%, preferably greater than or equal to 200%, and more preferentially greater than or equal to 300%, the particles of filler having, preferably, a specific surface area greater than or equal to 20 m²/g, preferably greater than or equal to 50 m²/g, preferably greater than or equal to 80 m²/g, preferably greater than or equal to 100 m²/g, preferably greater than or equal to 200 m²/g, and even more preferentially greater than or equal to 300 m²/g.
3. The decorative paper as claimed in any one of the preceding claims, the particles of filler having a median diameter D50 ranging from 2 to 8 µm, and more preferably ranging from 3 to 5 µm, the particles of filler having, preferably, a shape chosen from a lamellar shape, a globular shape and a spherical shape, and preferably have a spherical shape.
4. The decorative paper as claimed in any one of the preceding claims, the particles of filler having a refractive index n of less than 1.9, and preferably ranging from 1.2 to 1.8, and more preferably ranging from 1.4 to 1,7, and even more preferentially ranging from 1.5 to 1.6.
5. The decorative paper as claimed in any one of the preceding claims, the particles of filler being chosen from inorganic particles, organic particles, and mixtures thereof, the particles of filler being, preferably, inorganic and having a specific surface area greater than or equal to 50 m²/g and an oil absorption greater than or equal to 80%, preferably a specific surface area greater than or equal to 100 m²/g and an oil absorption greater than or equal to 80%, preferably a specific surface area greater than or equal to 200 m²/g and an oil absorption greater than or equal to 80%, preferably a specific surface area greater than or equal to 200 m²/g and an oil absorption greater than or equal to 150%, and even more preferably a specific surface area greater than or equal to 300 m²/g and an oil absorption greater than or equal to 200%, the particles being, preferably, inorganic and chosen from particles of amorphous silicas, particles of precipitated silicas, particles of diatomaceous earths, particles of aluminosilicates, and mixtures thereof, and preferably are chosen from particles of amorphous silicas, particles of precipitated silicas, and mixtures thereof, and even more preferentially are chosen from particles of amorphous silicas, and mixtures thereof.
6. The decorative paper as claimed in any one of the preceding claims, the particles of filler being present in an amount ranging from 3% to 40% by weight relative to the total dry weight of the paper, preferably ranging from 5% to 35%, more preferably ranging from 8% to 30%, preferably ranging from 10% to 30%, more preferably ranging from 10% to 25%, even more preferentially ranging from 15% to 25%, and more preferentially ranging from 15% to 20% by weight relative to the total dry weight of the paper.
7. The decorative paper as claimed in any one of the preceding claims, said paper exhibiting a speed of impregnation with a thermosetting resin of less than or equal to 20 seconds, preferably less than or equal to 10 seconds, said paper exhibiting, preferably, on at least one of its faces, a Bekk smoothness of 20 to 140 seconds.
8. The paper as claimed in any one of the preceding claims, said paper being devoid of particles other than those defined in one of claims 1 to 7, said paper being devoid, preferably, of an ink-fixing surface layer.
9. The decorative paper as claimed in any one of the preceding claims, said paper being transparent after impregnation with a thermosetting resin and also comprising, preferably, at least one pattern printed on at least one of its faces.
10. A process for preparing a decorative paper as defined in any one of the preceding claims, comprising the steps consisting in:

    - preparing a wet fibrous cellulose composition, and

    - introducing into said fibrous composition, in the wet part of a paper machine, particles of a filler as defined in one of claims 1 to 9, said particles being introduced into said fibrous composition by mixing with said composition before the headbox or said particles being introduced into said fibrous composition by mixing in a paper pulp vat or said particles being introduced into said fibrous composition after said composition has been deposited on a forming surface, said particles being, preferably, introduced into said fibrous composition by means of a second headbox, by means of a slot device, or by means of a spraying device.
11. The process as claimed in claim 10, said particles being introduced into said fibrous composition in the form of a dispersion, preferably an aqueous dispersion, or in the form of a powder, and preferably, the aqueous dispersion of particles consisting substantially of a mixture of water and said particles.
12. The process as claimed in one of claims 10 to 11, comprising a step consisting in adding to said fibrous composition a wet strength agent and/or a retaining agent and, comprising, preferably, a step of surface treatment, in particular by penetrating coating, advantageously with polydiallyldimethylammonium or a microcrystalline cellulose.
13. A high-pressure, low-pressure or continuous-pressed laminate, comprising at least one decorative paper as defined in one of claims 1 to 9, or capable of being obtained according to a process as defined in one of claims 10 to 12.
14. The laminate (31) as claimed in the preceding claim, comprising a superposition of at least two, preferably of at least three, and more preferentially of at least four, decorative papers (22) as defined in one of claims 1 to 9, or capable of being obtained according to the process as defined in one of claims 10 to 12.
15. The use of particles of a filler as defined in one of claims 1 to 9, in a decorative paper for a high-pressure, low-pressure or continuous-pressed laminate, for improving the printability by inkjet printing of said decorative paper.

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