FR2841574A1 - METHOD FOR PRODUCING A SHEET CARRYING A RELIEF PATTERN COVERED WITH A LAYER PROVIDING A DEEP EFFECT - Google Patents

Abstract

The invention relates to a method of manufacturing on a paper machine a sheet carrying a relief pattern covered with a layer giving it a depth effect, in particular an imitation leather appearance or similar to a “jean” type fabric, characterized in that it comprises at least: - a first step consisting in forming and then marking a support sheet by means of a relief marking device; - a second step consisting in coating at least one of the faces of the sheet marked with a layer using a coating device, choosing the viscosity of the applied layer and the pressure in the coating device so that the layer is preferably deposited either in the recesses or on the reliefs of the marked leaf.

Description

The present invention relates to a method for manufacturing sheets

  comprising a relief pattern and prepared by depositing a layer on at least one

  sides marked with a sheet of paper or the like.

  The present invention also relates, more generally, to a sheet carrying a relief pattern covered with a layer on at least one of its faces. In the present invention, the terms "marked sheet" and "marked paper" mean respectively a sheet or a paper, having marks or patterns in relief produced using embossing or watermarking rollers, marker felts or grain presses , possibly hot. It is for example a laid paper, the rods being made using a watermark roll; of a grained paper, the grain being produced by means of an embossing roller, a marker pen or a grain press. It can also be for example a film of

embossed synthetic material.

  In the prior art, marked and coated papers are already known.

  However, these papers have a number of drawbacks.

  When said papers are marked after being coated, their main drawback is that the marking operation makes the layer shiny at the places where pressure is exerted via the reliefs produced on the embossing or watermarking rollers or the reliefs of the felts. markers. Thus, these papers have bright and unsightly dots or streaks. In addition, since the layer is applied uniformly over the entire surface of the paper, the feeling of relief for the final paper may be reduced, in particular in the case of a colored layer. When said papers are coated after being marked, it has been observed, in particular from the teaching of patent FR 2670811 of the Applicant, that the layer was deposited homogeneously on the recesses and bumps of the paper. The resulting sensation of relief could therefore also be affected, in particular in the case of a colored layer. The sheets of the present invention will, on the contrary, have a feeling of relief enhanced to the eye by the difference in hues or glosses between the layer.

applied and the support coated.

  The effect produced will in particular be comparable to that of a faux leather or

"jean" type fabric.

  In a certain number of natural or artificial materials having a rough structure, differences in color between hollows and bumps in this structure reinforce the sensation of relief to the eye. This is the case, for example, for leathers, the pores of which are darker. that the

  surface, or "jeans" fabrics whose wear makes the protruding parts white.

  In the prior art, methods have already been envisaged for imitating this natural appearance on artificial supports so as to obtain decorative sheets,

  especially for creation, packaging or drawing.

  There are in particular methods of coloring imitation leather, in which an impression is made of the tops of the bumps of the similis, the hollows being of a

different color.

  This difference in color gives them both a more natural appearance,

  but also produces an aspect of relief with texture.

  The same effect is also known with differences in gloss between

  the hollows and bumps in the case of leather imitations.

  It is also known methods of marking and coloring paper performed offline by means of a gravure printing type, in which only the bumps of the paper are covered by ink. However, most of the existing methods have in common the implementation of a

  coloring process carried out outside the machine.

  One of the aims of the invention is therefore to propose a colored paper with an effect of

  1 0 reinforced relief produced on paper machine.

  In accordance with the invention, the paper is obtained using a method of manufacturing on a paper machine a sheet bearing a relief pattern covered with a colored layer giving it an effect of depth, in particular a similar appearance. leather or similar to a "jean" type fabric, characterized in that it comprises at least 1 5: - a first step consisting in forming and then marking a backing paper; - a second step consisting in coating at least one of the faces of the marked paper with a colored layer using a coating device, by choosing the viscosity of the applied layer and the pressure in the coating device so that the colored layer be deposited so

  preferential either in the hollows or on the reliefs of the marked paper.

  The method of manufacturing such a sheet according to the present invention will

  beyond the current knowledge of those skilled in the art.

  Indeed, the skilled person knew, as we have before, that if a pigmented layer was deposited on a previously marked paper, the layer would

  distributes evenly and follows the reliefs of the marked paper.

  However, the Applicant has been able to observe in the context of its research that this teaching remains true during a coating carried out according to conventional methods but is no longer verified for very specific conditions linked to the choice of the coating device, to the physical characteristics of the sauce of

  and the settings of the sleeping device itself.

  The Applicant therefore had the idea of varying the rheology of the sauce

  coating and the pressure applied to it as a function of the result to be obtained, that is to say a preferential deposition of the layer in the recesses or on the reliefs of the paper.

  The coating device will preferably be chosen from the presses

  film transfer, especially of the Twin HSM type, or conventional size presses.

  In order to obtain the relief effects, the rheology of the applied layer and the pressure applied during coating are varied according to the type of paper and the type of layer used to obtain the desired effect, effect resulting from the deposition.

  selective layer either in the hollows or on the reliefs of the paper.

  In this case, for coating in the hollows of the marked paper, the coating sauce should have a low shear threshold and the pressure between

  the rollers of transfer presses or gluing machines will be raised.

  Conversely, for a coating on the tops of the paper grains, the coating sauce must have a relatively high shear threshold and the pressure applied will be low, but sufficient for the sheet to be in contact with

the presses.

  According to a first embodiment of the invention, in order to achieve a preferential coating in the recesses, or respectively on the reliefs of the marked sheet, the pressure applied to the marked sheet during the coating will be chosen so that the width of the contact area of the coating rollers is

  greater than 19 mm, or respectively less than 17 mm.

  According to another embodiment, the viscosity of the coating sauce will be less than 0.3 Pa.s measured with a Brookfield type device at 100 rpm with the module 3 for coating in the hollows of the marked paper and will be greater than 0.5 Pa.s measured with a Brookfield type device at 100 rpm with the

  module 3 for coating on the reliefs of marked paper.

  The marking can be done on machine or off machine.

  Additional coating may be carried out following the first coating using a coating device formed by two film transfer presses

  or a size press and a film transfer press.

  The first and second layers may, as such, be identical or

  different from each other in terms of their coloring and shine.

  More generally, the layer or layers applied will contain at least one component chosen from dyes, white pigments and / or pigments with a high gloss value, iridescent, luminescent or fluorescent substances,

thermochromic agents.

  In particular, the percentage of reliefs relative to the depressions for the total surface of the relief marking device will be between 40% and 80%,

  and will preferably be close to 60%.

  Another object of the invention is to provide a sheet carrying a relief pattern covered on one of its faces with one or more layers, characterized in that the layer or layers are mainly located either in the recesses or on the landforms

of the sheet.

  Specifically, the proportion of layers deposited mainly 1 5 either in the hollows or on the reliefs of the sheet may be greater than 80%, and

preferably greater than 90%.

  For this reason, we will consider as a relief for the sheet all the parts of the surface of the sheet situated above the average amplitude of the relief patterns of the sheet, and as a hollow for the sheet all the parts of the surface of the

  sheet located below the average amplitude of the relief patterns of the sheet.

  This sheet may have layer and support colorations

  different shades, in particular one being colored and the other white.

  Likewise, it may have different coat and support glosses, one being matt and the other being shiny, or one being iridescent

and the other being dull.

  In general, the layer or layers applied may contain at least one component chosen from dyes, white pigments and / or pigments with a high gloss value, iridescent, luminescent or fluorescent substances,

thermochromic agents.

  In particular, the marked sheet will have a percentage of reliefs relative to the hollows for its total area of between 40% and 80%, and

preferably close to 60%.

  One of the embodiments of the invention will be described below in detail.

referring to the drawings.

  Figure 1 shows a coating device of the TWIN HSM press type.

  Figure 2 shows an example of a graining pattern.

  Figure 3 shows the surface photograph of a grain press

  seen in grazing light, relative to another example of graining pattern.

  Figure 4 is the perspective graphic representation of the relief of

  surface of the grain press in Figure 3.

  Figure 5 is a diagram representing the distribution of amplitudes

  reliefs of the grain press in Figure 3.

  Figure 6 is the graphical representation of the approximation function

  of the surface of the grain press in Figure 3.

  Figure 7 is a diagram representing the value displayed by the Twin HSM press in BTG unit as a function of the width of the "nip" or contact area measured between the coating rollers of the press expressed in mm. In Figure 1, we can see a particular configuration of the film transfer press, as designed by the Swedish manufacturer BTG Kalle Inventing AB under the name Twin-HSM and which is protected by patent EP 362174, content should be considered as part of technical knowledge

common in the art.

  In this particular configuration, the Twin-HSM press deposits a

  coating sauce on both sides of the paper strip (1).

  The strip is running vertically in the direction of the arrow (c).

  The press comprises two pressure rollers (9) rotating in the

  direction (a) and between which the paper strip is pressed.

  Each pressure roller has an associated coating device (2)

  which is provided with a coating roller (3) rotating in the direction of the arrow (b).

  The coating roller (3) bathes in its lower part over its entire length in a bath (21) of coating composition or liquid supplied by a feed chute and in this way transfers a coating composition onto the external surface of the roller pressure and, subsequently, on one side of the strip

  of paper facing the pressure roller.

  The excess coating composition is evacuated from the pinch area and

  collected in a collecting tank (23) for recirculation in the process itself.

  The film transfer press can either be integrated into the paper manufacturing process itself, and therefore mounted on a paper machine, or installed outside the machine.

  so as to apply the coating sauce on already formed paper.

  It is understood that the use of this film transfer press is an advantageous solution for the problem to be solved, but does not in any way constitute a strict limitation of the coating means capable of being used in order to

to achieve the desired result.

  It is also understood that the relief of the paper can be obtained either by any other finishing process than simple graining, in particular by

  creping or embossing, or that it results from the original surface condition of the paper itself, in particular due to a high degree of roughness.

  In the following examples, the relief applied to the paper results from a

  graining carried out just before the drying of the paper machine.

  As the relief applied is not the essential parameter of the invention, the

  different examples are based on the same graining relief.

  This has been shown diagrammatically in FIG. 2.

  It can be likened to a network of ellipsodal points in relief arranged in a checkerboard covering an area, representing approximately 60% of that of the hollows of the grain press. Another graining pattern used by the Applicant, and for which the observations in the following examples have been confirmed, has been represented on the

figure 3.

  This figure 3 corresponds in fact to the photograph of the surface of a grainy press seen in grazing light. The white parts of the photograph correspond to the reliefs of the

  press and the dark parts in the hollow of the press.

  The Applicant has analyzed the topography of this grainy press, by making an impression of its surface using silicone and by using

  optical sensors for measuring the depth of the valleys.

  These measurements resulted in the perspective graphic representation of the

figure 4.

  In this figure, one can see in relief a part of the surface of the grain press, a square of 5 mm by 5 mm, the upper parts being white and the parts

bass being dark.

  It can be seen that the highest peaks are around 500 gm.

  These measurements were then the subject of statistical calculations and a mathematical approximation intended to give a simple graphical representation and

  smoothed from the surface of the grain press.

  We can thus see in Figure 5 a diagram representing the distribution

  amplitudes of the reliefs of the grainy press.

  il The bar chart refers to the lower abscissa and gives the percentage, in relation to the total area, of the reliefs having the amplitude indicated on

the ordinate axis.

  As for the linear curve, it refers to the upper abscissa and represents the cumulative percentage, relative to the total surface, of the reliefs having

  an amplitude less than or equal to that indicated on the ordinate axis.

  The percentage at 50% on the upper abscissa therefore allows us to find an average amplitude of reliefs for the total surface being worth approximately 320 μm. The software means implemented by the Applicant then made it possible to find, from the measurements made, a simple mathematical approximation of the

surface studied.

  This approximation is shown in Figure 6.

  It makes it possible to assimilate the surface of the grain press to a series of identical parallel grooves, the grooves themselves being comparable to cylinders with

trapezoidal base.

  This trapezoidal base is defined by a large base worth about 10

  mm, a small base worth about 3 mm, and a height worth about 6 mm.

  By considering the part of the furrows having an amplitude greater than or equal to the half-height of the trapezium as the reliefs of the grainy press, and the other part of the furrows as the hollows of the grainy press, we arrive by calculation at a rate reliefs compared to the troughs for the total surface area close to 60%, that is to say

  close to that of the first pattern used.

  Anyway, it is understood that other surface patterns are possible, obtaining the enhanced relief effect targeted by the invention is normally independent of the shape of the hollows or bumps of the grain press

  and their distributions on its surface.

  The examples provided are intended to highlight the major role of the rheology of the coating sauce and, incidentally, of the pressure applied during

  coating in the film transfer press, in obtaining the desired result.

  Therefore, in a first step, the viscosity of the coating sauce was modified, either by modifying the pigments added, or by including agents

viscosity modifiers.

  These viscosity modifiers may in particular be

  rheofluidifiers or rheo-thickeners.

  For the viscosity measurement, the device used was the rheometer

  RHEOVISCO ERV8 model (Brookfield type).

  This device has been shown diagrammatically in FIG. 7.

  It operates according to the well-known principle of a cylinder rotating in the

  product whose viscosity is to be known.

  We measure the torque necessary to overcome the resistance opposed by the

produced on cylinder rotation.

  The rotating cylinder, the height of which can be reduced, depending on the case, to that

  of a disc is connected by a spring to an axis driven at a known speed.

  The angle of deformation of the axis under the effect of the torque is measured electronically. Several types of cylinders can be used with different speeds of

  rotation allowed, which offer a wide range of measurement.

  In the examples provided, the cylinder used, according to the documentation supplied with the apparatus, cylinder n03, the measurements having been made at a speed of 100 rpm. In a second step, we modified the pressure applied on the sheet

  during coating, by changing the settings of the film transfer press.

  The Twin HSM press used displays the value of the pressure applied in

  a BTG unit specific to its manufacturer.

  The diagram of figure 7 given by the manufacturer gives, according to the pressure displayed by the machine, in BTG unit, the value in mm of the width of

  the contact area of the coating rollers.

  This contact zone corresponds in fact to the pinch zone, more commonly called "nip", in which the sheet is forced to pass and into

  which it undergoes a more or less significant compression.

  This diagram can be easily found using a sheet of carbonless paper which is passed through the coating device by varying the pressure applied and by measuring the width of the blackened area of the output sheet.

of the coating device.

EXAMPLE 1:

  In the example considered, the paper base support is a white paper grained according to the

  pattern defined above with a grammage of 250 g / m2.

  Fillers, in particular about 12% of a

ground calcium carbonate.

  The base support obtained then has an ISO whiteness degree of 108%.

  This paper was, during its formation, grained online to obtain the desired pattern.

  The amplitude of the bumps is then around 300 ptm.

  The paper is marketed by ARJO WIGGINS under the name "Tradition".

  The base support is then coated in a film transfer press of the Twin type.

HSM.

  The sauce composition used is as follows: Kaolin pigment SPS 66% (ECC): 100 parts Acrylic styrene binder ACRONAL S305D (BASF): 20 parts Blue dye LEVANOX ULTRA MARIN 3113 LF 1, part The viscosity of this coating is 0 , 2 Pa.s measured with a Brookfield viscometer at 100

rpm at 20 'C.

  This coating is deposited in a proportion of 10 g / m2 per side.

  The setting of the film transfer press is such that the pressure between the transfer rollers is 1030 (BTG unit), which corresponds, according to the diagram in the

  Figure 7, at a width of "nip" of about 27 mm.

  Under these conditions, the layer is preferably deposited in the recesses of the paper.

  It is therefore white on the tops of the grains and blue in the hollows.

EXAMPLE 2:

  In this example, the same paper support is used as in the previous example. The sauce composition used is as follows: ULTRAGLOSS kaolin pigment 90 to 66% (ENGELHARD) 100 parts Acrylic styrene binder ACRONAL S305D (BASF): 20 parts SATIAXANE thickener at 1% (SKW Biosystem): 0.32 part Blue dye LEVANOX ULTRAMARIN 3113 LF: 1.00 part The Brookfield viscosity at 100 rpm at 25 ° C measured with an n03 cylinder is in this

0.6 Pa.s.

  This coating is applied at a rate of 8.8 g / m2 / side.

  The pressure applied to the transfer rollers of the film transfer press is

  of 1010 (BTG unit), which corresponds to a width of "nip" of about 6 mm.

  In this case, the coating sauce is preferentially deposited on the reliefs of the paper. Comparative EXAMPLE 3:

  The paper support is that of the two previous examples.

  The layer composition used is as follows: Calcium carbonate pigment HYDROCARB 90 to 75% (OMYA): 56 parts SPS kaolin pigment 66% (ECC): 44 parts Thickener CMC finnfix 2000 at 1% (METSA SERLA) 0, 35 part LEVANOX ULTRAMARIN 3113LF blue dye. 1.2 parts The Brookfield viscosity at 100 rpm at 21 ° C. with the cylinder n03 is 0.4 Pa.s.

  This coating is deposited at a rate of 9.1 g / m2 / face.

  The pressure applied between the rollers of the film transfer press is 1030 (

  BTG unit), which corresponds to a width of "nip" of approximately 27 mm.

  In this case, it can be seen that the sauce is not preferentially deposited on the recesses or bumps in the paper, but rather in a homogeneous manner over the entire surface of the paper. This example makes it possible to observe that, for a viscosity of the coating sauce of between 0.3 and 0.5 Pa.s, it results rather in a uniform and regular deposition of the layer over the entire surface of the sheet and, this , despite a fairly coating pressure

  strong which would tend to bring it into the hollows of the leaf.

Claims (11)

  1) A method of manufacturing on a paper machine a sheet bearing a relief pattern covered with a layer giving it a depth effect, in particular an imitation leather appearance or similar to a "jean" type fabric, characterized in that '' it comprises at least: - a first step consisting in forming and then marking a support sheet by means of a relief marking device, - a second step consisting in coating at least one of the faces of the marked sheet with a layer of using a coating device, choosing the viscosity of the applied layer and the pressure in the coating device so that the layer is preferably deposited either   in the hollows, or on the reliefs of the marked leaf.   1 5 2) A method according to claim 1, characterized in that the relief marking device is chosen from embossing rollers, the rollers   watermarks, marker pens and grain presses.   3) Method according to one of the preceding claims, characterized in that   that the coating device is a film transfer press, in particular of the type   Twin HSM, or a classic size press.   4) Method according to claim 3, characterized in that, to achieve a preferential coating in the hollows of the marked sheet, the pressure applied during the coating on the marked sheet is chosen so that   the width of the contact area of the coating rollers is greater than 19 mm.   ) Method according to claim 3, characterized in that, in order to obtain a preferential coating on the reliefs of the marked sheet, the pressure applied during coating on the marked sheet is chosen so that   the width of the contact area of the coating rollers is less than 17 mm.   6) Method according to one of claims 1 to 4, characterized in that the   viscosity of the coating sauce is less than 0.3 Pa.s measured with a Brookfield type device at 100 rpm with module 3 for coating in the hollow of the marked leaf.   7) Method according to one of claims 1,2,3 or 5, characterized in that   the viscosity of the coating sauce is greater than 0.5 Pa.s measured with a Brookfield type device at 100 rpm with module 3 for coating on the reliefs of the marked leaf.   8) Method according to any one of the preceding claims,   characterized in that an additional coating is carried out following the   first coating, the layers being able to be identical or different between them.   9) Method according to the preceding claim, characterized in that the coating device is formed by two film transfer presses, or a press   gluing machine and a film transfer press.   ) Method according to any one of the preceding claims,   characterized in that the applied layer contains at least one component chosen from dyes, white pigments and / or pigments with a high gloss value,   iridescent, luminescent or fluorescent substances, thermochromic agents.   11) Method according to any one of the preceding claims,   characterized in that the total surface of the relief marking device has a percentage of reliefs with respect to the depressions of between 40% and 80%, and of preferably close to 60%.   12) Sheet carrying a relief pattern covered on at least one of its faces with one or more layers, characterized in that the layer or layers are   mainly located either in the hollows or on the reliefs of the leaf.   13) Sheet according to the preceding claim, characterized in that the proportion of layers deposited mainly either in the hollows, or on the   leaf reliefs is greater than 80%, and preferably greater than 90%.   14) Sheet according to claim 12 or 13, characterized in that the layer or layers contain at least one component chosen from dyes, white pigments and / or pigments with a high gloss value, iridescent substances,   luminescent or fluorescent, thermochromic agents.   ) Sheet according to one of claims 12 to 14, characterized in that   that the percentage of reliefs compared to the hollows for the total surface of the   sheet is between 40% and 80%, and is preferably close to 60%.