Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
  • B31F—MECHANICAL WORKING OR DEFORMATION OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
  • B31F1/00—Mechanical deformation without removing material, e.g. in combination with laminating
  • B31F1/07—Embossing, i.e. producing impressions formed by locally deep-drawing, e.g. using rolls provided with complementary profiles
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F1/00—Wet end of machines for making continuous webs of paper
  • D21F1/48—Suction apparatus
  • D21F1/52—Suction boxes without rolls
  • D21F1/523—Covers thereof
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F7/00—Other details of machines for making continuous webs of paper
  • D21F7/006—Cutting the edges of the paper-web
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/30—Multi-ply
  • D21H27/40—Multi-ply at least one of the sheets being non-planar, e.g. crêped
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
  • B31F—MECHANICAL WORKING OR DEFORMATION OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
  • B31F2201/00—Mechanical deformation of paper or cardboard without removing material
  • B31F2201/07—Embossing
  • B31F2201/0707—Embossing by tools working continuously
  • B31F2201/0715—The tools being rollers
  • B31F2201/0723—Characteristics of the rollers
  • B31F2201/0733—Pattern
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
  • B31F—MECHANICAL WORKING OR DEFORMATION OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
  • B31F2201/00—Mechanical deformation of paper or cardboard without removing material
  • B31F2201/07—Embossing
  • B31F2201/0707—Embossing by tools working continuously
  • B31F2201/0715—The tools being rollers
  • B31F2201/0723—Characteristics of the rollers
  • B31F2201/0738—Cross sectional profile of the embossments
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
  • B31F—MECHANICAL WORKING OR DEFORMATION OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
  • B31F2201/00—Mechanical deformation of paper or cardboard without removing material
  • B31F2201/07—Embossing
  • B31F2201/0756—Characteristics of the incoming material, e.g. creped, embossed, corrugated
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
  • B31F—MECHANICAL WORKING OR DEFORMATION OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
  • B31F2201/00—Mechanical deformation of paper or cardboard without removing material
  • B31F2201/07—Embossing
  • B31F2201/0758—Characteristics of the embossed product
  • B31F2201/0761—Multi-layered
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
  • B31F—MECHANICAL WORKING OR DEFORMATION OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
  • B31F2201/00—Mechanical deformation of paper or cardboard without removing material
  • B31F2201/07—Embossing
  • B31F2201/0784—Auxiliary operations
  • B31F2201/0787—Applying adhesive

Definitions

• the present invention relates to absorbent paper products, more particularly cellulose wadding, sanitary or domestic use and aims a sheet consisting of at least two plies, one of which is embossed, intended for the realization of toilet paper essentially, but also handkerchiefs or towels.
• the present invention relates to paper transformed from a dried paper sheet which has been pre-made in a wet phase on the paper machine.
• the most widespread embossing patterns consist of a repetition on a geometric frame of elementary protuberances of small cross section and simple geometric shape.
• An example is described in US Patent 3,414,459 which relates to a sheet with two or three plies, that is to say consisting of a plurality of elementary sheets, called folds, bound or glued together.
• the plies are embossed with a frequency of distribution of the protuberances and a height of the protuberances adapted to the production of water-absorbing products such as paper towels, the number of elements ranging from 3 to 30 protuberances cm 2 .
• the embossed folds are associated according to a so-called "tip-tip” process, in which the vertices of the protuberances of one fold face the tops of the protuberances of the other fold.
• the Applicant has developed, for toilet paper in particular, patterns whose number of elements is greater, ranging from 30 to 100 protuberances per cm 2 . In this case, because of their number, these elements form protuberances of lower height and necessarily have an elementary surface at the top also very low, less than 1 mm 2 . For these last embodiments, an aspect is obtained which mimics that of a woven product.
• An example has been described in EP 0 426 548 B1. This type of embossing mainly affects the mechanical characteristics of the sheet such as its rigidity and strength.
• absorbent paper products consist of two plies but obtained according to a different association technique.
• a fold or a set of two superposed folds is waffled and, on the other hand, a second fold by means of two distinct embossing devices.
• the first fold and the second fold are embossed in relief patterns consisting of protuberances.
• the density of patterns necessarily remains low: less than 20 protuberances per cm 2 for this type of product.
• the two plies are associated by means of a marrying cylinder so that the distal surfaces of the protuberances of the two superimposed folds are disposed opposite the surfaces located between two protuberances in the plane of the second fold. This technique is still called “nested" process.
• the Applicant has also developed a product consisting of two plies, one embossed, the other unembossed. Each fold has a basis weight of the order of 10 to 40 g / m 2 .
• One is embossed with relief patterns consisting at least in part of discrete protuberances facing the inside of the sheet and the other is unembossed.
• the embossed fold has on at least a portion of its surface at least 30 protuberances per cm 2 , the top surface of which is less than 1 mm 2 , preferably less than 0.7 mm 2 .
• the fibrous and / or chemical composition of the plies may be the same or different.
• the unembossed ply may have a fibrous composition essentially based on long fibers such as softwood fibers, and the embossed ply a fibrous composition essentially based on short fibers.
• the non-embossed ply may include a wet-resistant additive, and the embossed ply may include a softening or debonding additive.
• the sheet thus composed has a very good wet strength and therefore good strength, in particular due to the composition of the non-embossed ply. It also offers a softness of surface by the choice of the fibrous and chemical composition of the embossed fold.
• the sheet also has remarkably, substantially the same thickness as a double sheet made with two embossed plies in the same way as the embossed ply and assembled in point-to-tip position.
• a first embossing roll 10 with a rigid coating, has on the surface spikes of a shape adapted to the production of desired protuberances. These pins are generally obtained by etching the cylinder.
• the process for producing the sheet consists in embossing a first ply of cellulose wadding 20, unwound from a spool, between the embossing roll and a roll 12 made of rubber or other equivalent material, and then assembling it by means of a marrying roll 14 to a ply of non-embossed cellulose wadding 40, also unwound from a mother reel.
• the marrying roll applies the fold 40 to the first fold 20 while the latter is still in contact with the embossing roll 10.
• a water-based adhesive substance was applied, where appropriate, to the tops of the highest embossed protuberances.
• first ply 20 by means of a gluing roll 16.
• the sheet from the machine is rolled into logs of small diameter corresponding to that of the rolls that will be marketed; then the logs are cut into the said rolls.
• the embossed fold is the so-called outer fold of the sheet when it is rolled up and the non-embossed fold the so-called inner fold. It is sought thereby to make the embossing visible, preferably.
• a marrying cylinder whose coating is hard but rubber anyway.
• This deformation of the surface of the marrying roll leads to a deformation of the sheet at the point where the contact pressure is high, ie the zone of the connecting pins.
• These protuberances are of low height but it is sufficient for them to be perceived to the touch, providing an unpleasant sensation affecting the softness of the product. This is an undesired side effect.
• the engraving pattern of the embossing cylinder of FIG. 3 is composed of frustoconical or truncated pyramidal pins, the first ones being aligned and the second ones being surface-filled.
• the first can be raised by 0.2 mm for example compared to the second.
• the protuberances formed from these first spikes receive the bonding adhesive of the embossed ply with the non-embossed ply. Due to the pressure of the marrying cylinder exerted on the sheet, the inner ply is deformed by these first protuberances while one would wish smooth.
• the plies consist of cellulose wadding with different fibrous or chemical compositions
• CWP Conventional Wet Press
• This technique consists in forming a sheet by depositing a paste consisting of fibers suspended in water on a forming fabric, draining it, and wringing it by transferring it with pressing to a second fabric. felt, then to apply it to a large diameter drying cylinder from which it is detached after drying by means of a doctor blade.
• the scraping is performed so as to form a crimp of fine close and regular undulations, imparting volume and elongation to the dried sheet.
• creping in the case of a sheet with an embossed fold and a non-embossed fold bonded together, the back-side effect can not be avoided.
• the solution which consists in using a steel marrying cylinder substantially of the same hardness as the embossing cylinder, would be industrially difficult to implement because of differences in geometry between the cylinders that can not be compensated or compensated because of the very hardness of the cylinders. materials. The process would be economically unattractive.
• the Applicant has set itself the objective of producing such a product that is to say comprising a first and a second ply of cellulose wadding, the first of which is embossed with relief patterns, consisting at least in part first protuberances oriented towards the inside of the sheet, and the second is unembossed, the two plies being bonded by bonding of the first protuberances, which does not have the disadvantage of the prior art.
• the invention therefore relates to products whose nature of the protuberances of the embossed fold is likely to generate a backside effect.
• These are protuberances whose cross section in the plane of the fold is truncated cone or pyramid trunk.
• These protuberances are insulated or arranged side by side along the same line or portion of line, curved or rectilinear, that is to say arranged in a single row.
• the pattern of Figure 3 is an example.
• protuberances whose cross section in the plane of the fold is elongated. These protuberances are linear and form lines or portions of continuous line.
• protuberances are designated by protuberances arranged in a single line.
• the product according to the invention is characterized in that the first protuberances are arranged in a single line and in that the second non-embossed fold is a fold of the throughdried drying type. having a thickness of between 0.2 and 0.5 mm for a basis weight of between 15 and 45 g / m 2 .
• the thickness is an average measurement made on a stack of
• a surface probe 10 cm 2 is placed on the folds with a lowering speed of 2 mm / s, and then applies a pressure of 20 g / cm z; after a duration of 5 seconds, the value of the thickness is measured (according to EN 12625-3).
• a paper of the air-blown dry type which will be referred to as TAD, is in itself known. It differs from CWP type paper by first drying the sheet downstream of its formation and before any compression. This drying is carried out while the still wet sheet rests on a canvas, by hot air directed through it.
• the TAD fold surprisingly avoids or at least reduces this phenomenon.
• the thickness of the second fold is between 0.2 and 0.3 mm.
• said first protuberances cover between 2 and 15% and more particularly between 2 and 10% of the surface of the sheet.
• the invention is preferably applied to a sheet whose first ply further comprises second protuberances of density between
• the first protuberances being at a higher level than the second protuberances with respect to the plane of the first ply.
• the first fold is a fold of the CWP type.
• the sheet consists of the first and second plies mentioned above.
• the hybrid sheet will be referred to as a sheet comprising an embossed ply and a non-embossed type TAD ply.
• FIG. 1 schematically represents a cellulose wadding processing plant enabling the production of a continuous sheet comprising an embossed fold assembled with an unembossed fold, with an enlarged detail of the surface of the engraved cylinder;
• Figure 2 shows in section the structure of a two-ply sheet of cellulose wadding produced by the installation of Figure 1;
• Figure 3 shows an embossing pattern of the embossed fold of the sheet, the pattern comprising only discrete protruding elements in a single line;
• FIG. 4 represents the internal face of a sheet of the prior art in which the two plies are made of cellulose wadding CWP;
• FIG. 5 represents the internal face of a hybrid sheet according to the invention
• Figure 6 shows another embossing pattern of the embossed fold of the sheet, the pattern comprising continuous linear elements along a single line;
• FIG. 7 is a diagram showing the evolution of the ratio of the area above the threshold, on the ordinate, for each threshold value on the abscissa.
• the product from the machine illustrated in Figure 1 comprises a first ply of cellulose wadding 20, which has been embossed on the embossing cylinder 10 associated with a second ply of cotton wool.
• cellulose 40 which has not been embossed.
• the fold 20 comprises first protuberances 20i and second protuberances 20 2 .
• the fold 40 is connected to the fold 20 by the protuberances 20-t which correspond to the first pins 10i of the cylinder which are prominent with respect to the second pins IO2. Due to the pressure exerted by the marrying cylinder, given the speed of manufacture imposed by industrial constraints, it can not be avoided that the sheet 40 is deformed to a certain extent.
• the adjustment of the pressure applied by the marrying cylinder results from a balance.
• the adhesive applied to the tops of the protrusions 2Oi forms a connection between the two folds 20 and 40 only if a minimum pressure is exerted by the marrying cylinder. Too low a pressure would lead to a leaf with unassociated areas. Too much pressure leads to a leaf having a very pronounced backside effect.
• the difference between the levels of the vertices of the first and second pins is generally at least 0.2 mm. If a product is produced with an engraved cylinder whose pins are all the same height, this is at least 0.4 mm.
• This back-up effect springs up when the sheet is rolled up while it is being rolled.
• a mandrel or a spindle is used which is rotated about its axis. This rotation involves a pull on the sheet and a tightening of the latter on the roll. This results in a pressure of a turn on the underlying turn and the protuberances of the outer fold of the coil support on the inner fold.
• the underlying coil is flexible, it does not constitute sufficient support for the force of the protuberance on the inner fold, it is deformed producing a relief on the opposite smooth face.
• the backside effect is springing.
• the solution of the invention to avoid precisely the deformation during the winding has been to replace the smooth fold CWP type so far, by a fold of the air-drying drying type, TAD.
• the manufacture of this type of TAD of cellulose wadding is described below.
• the pulp consisting of fibers suspended in water is deposited in one or more jets on a moving web known as forming the sheet.
• the sheet is transferred to a fabric having a large porosity and a determined relief.
• This fabric is driven on drying means by hot air passing through, for example in the form of a cylinder around which the fabric with its sheet is guided. During its passage on the cylinder the sheet is crossed by a mass of hot air which greatly increases its dryness freezing the fibrous structure of the sheet. This structure depends on the imprint left on the sheet by the canvas.
• a marker fabric is preferably used which comprises a weaving structure with zones of high porosity and areas of low porosity disposed according to a geometric definition determined such that it induces in the sheet a heterogeneous structure having different areas of compacting by the very effect of the air through.
• Drying can be carried out on a single means of drying by passing air or by step on two means, one after the other.
• the sheet may retain a certain degree of residual moisture and be applied to a drying cylinder, Yankee type known per se, to complete its drying so as to allow its creping by delamination by means of a scraper blade.
• Other means than conventional creping are known to impart elongation to the sheet.
• the invention is not limited to the use of a fold of cellulose wadding dried according to a particular technique of passing air blowing. Any other technique equivalent to the scope of those skilled in the art can be implemented. This manufacturing technique allows the production of sheets whose mass volume is higher than for CWP sheets. At equal weight the sheet is therefore thicker.
• the fiber composition is a mixture of long fibers of wood pulp, such as softwood and short wood pulp fibers, such as hardwoods.
• the first embossed fold is a fold CWP.
• the thickness of such a fold is between 0.1 mm and 0.15 mm.
• FIG. 3 This is a pattern consisting of first protuberances , relatively large and drawing an aesthetic pattern, and second protuberances finer, density of 80 protrusions per cm 2 , forming a filling within the design of the first protuberances.
• Thickness 1.84 mm for 12 folds.
• a creped TAD cellulose wadding band with a creping rate of 8 to 10% fibrous composition 50% SWK prime / 50% Eucalyptus,
• a hybrid sheet according to the invention was made in which the CWP ply was embossed from the CWP strip according to the pattern of FIG. 3 and the non-embossed ply was a TAD fold consisting of the TAD band and a control sheet of which the Embossed ply was identical to that of the sheet according to the invention (ply CWP) and the non-embossed ply consisted of the CWP strip.
• the operating conditions on the machine of FIG. 1 were the same in both cases. The sheet in both cases was put in rolls of diameters
• the backside samples are placed facing the 3D analyzer's illumination to study the inner fold of the sheet. Each sample is flattened as best as possible to avoid measuring differences in parasitic heights.
• the analyzed surface is a rectangle of 20X16 mm. The surface is illuminated by a projection of bright fringes. The fringes are obtained by a light passing through various calibrated grids. The image is acquired by triangulation between the fringe projector, the sheet and the camera. The camera allows you to save images to a computer's memory via the Optocat program.
• the images are then processed by the Toposurf software.
• the image is first flattened to compensate for optical distortions due to the lens of the camera and then clipped to remove extreme values (99.9% of the data is retained).
• a reference image is then obtained. Each pixel of the image is referenced in space and has ribs along the three axes.
• Reference images are then processed by the 'Morphology / z cuts' function.
• This function makes it possible to make cross sections perpendicular to the z axis and to calculate with respect to a horizontal plane of altitude z, the surface of the points situated above or below the plane.
• FIG. 4 shows, for the CWP fold (corresponding to the control sheet), a structure of fine ridges of the crepe. In this area of the image, we can see the traces of the protuberances forming the backside effect. The light pavers are surrounded by darker areas showing the difference in level.
• TAD corresponding to the hybrid sheet according to the invention
• the general relief is more marked; it is that of the marker cloth.
• the images were analyzed using the software mentioned above. Images were cut along the z-axis keeping only the pixels present above a given threshold.
• the threshold was increased progressively until most of the pixels corresponding to the crepe disappeared. The remaining pixels thus correspond to the upside effect at the first protuberances.
• a curve has also been plotted for each threshold on the abscissa of the ratio of the area above the threshold to the total area. This curve, referenced A is reported in Figure 7. Knowing that the surface of the first protuberances covers in this example 5 to 8% of the total area, the measured threshold is then 0.05 mm. It remains then a height of 0.05 mm for the protuberances which are at the origin of the effect of back.
• Curves A and B make it possible to deduce that the hybrid sheet produced according to the invention with an embossed CWP ply and an unembossed TAD ply has a threshold of 0.07 mm, which corresponds to a height of only 0.03 mm for protuberances likely to generate a backside effect. This reduction of 40% of the height of the protuberances is enough to remove the perceived upside effect.
• Figure 6 there is shown another type of pattern, the first protuberances are not punctual shape but they consist of linear elements.
• the graph of FIG. 7 shows that the behavior is the same as for the present invention relating to discrete protuberances.
• the unpleasant perception of the upside-down effect is no longer present on the hybrid sheet according to the invention, in particular after winding the sheet. As a result, the perceived overall sweetness of the product by the consumer is improved.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Paper (AREA)
• Machines For Manufacturing Corrugated Board In Mechanical Paper-Making Processes (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Sanitary Thin Papers (AREA)
• Laminated Bodies (AREA)

Priority Applications (3)

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Citations (5)

• 2006
  • 2006-01-12 FR FR0650106A patent/FR2895934B1/fr active Active
• 2007
  • 2007-01-11 AT AT07717775T patent/ATE534769T1/de active
  • 2007-01-11 EP EP07717775A patent/EP1979540B1/fr active Active
  • 2007-01-11 ES ES07717775T patent/ES2376262T3/es active Active
  • 2007-01-11 WO PCT/FR2007/000048 patent/WO2007080322A2/fr active Application Filing

Patent Citations (5)

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