EP1084300A1

EP1084300A1 - Absorbent paper product comprising three pleats and method for making same

Info

Publication number: EP1084300A1
Application number: EP99937958A
Authority: EP
Inventors: Gilles Roussel; Benoít Hoeft
Original assignee: Fort James France
Current assignee: Essity Operations France SAS
Priority date: 1998-03-06
Filing date: 1999-03-05
Publication date: 2001-03-21
Anticipated expiration: 2019-03-05
Also published as: FR2775698A1; TR200002581T2; DE69931631D1; FR2775698B1; DK1084300T3; US6599614B1; EP1084300B1; WO1999045205A1; PT1084300E; ES2264583T3; US6805766B1; DE69931631T2

Abstract

The invention concerns an absorbent paper product with basic weight of about 36 to about 105 g/m<2> comprising at least three pleats, a first and second outer embossed pleats each comprising raised patterns consisting at least partially of discrete protuberances oriented towards the inside of the structure and a non-embossed central pleat, the pleats being associated by linking the distal surfaces of at least part of the protuberances of each of the outer pleats to the central pleat. The invention is characterised in that each of the embossed outer pleats is linked by means of an adhesive to said central pleat, and at least one of the pleats has a pattern density more than 30 protuberances per cm<2>.

Description

ABSORBENT PAPER PRODUCT COMPRISING THREE-PLEASE AND SOUND

MANUFACTURING PROCESS

The invention relates to absorbent paper products and more particularly cellulose wadding, for sanitary or domestic use. It mainly relates to toilet paper, but may possibly concern household papers such as paper towels, hand towels, napkins, or handkerchiefs.

Most of these products consist of one or more folds or sheets superimposed in cellulose wadding. The folds can be combined by bonding them. In the case of toilet paper, conventional products include two, three or even four associated plies.

The invention relates more precisely to a product consisting of at least three plies and to its manufacturing process.

US Patent No. 3,414,459 generally describes a paper towel structure comprising at least two embossed plies. It mentions a product comprising three associated plies, a third ply being interposed between two embossed external plies. This structure is prepared from plies with a grammage of approximately 17 g / m ² each. According to the manufacturing process described in this patent, the two outer plies are embossed separately with a relief pattern consisting of discrete protuberances. Each of the folds is passed between a metal cylinder engraved in relief according to the desired pattern and a smooth rubber cylinder. Each embossed fold thus obtained generally has a repeated pattern of 3 to 30 protrusions or spikes in relief per unit area, here per cm ² . In the following text, the number of protuberances per unit area will be defined by "density of patterns". For the structures composed of three plies illustrated in this patent, the density of patterns is approximately 1 1 protuberances / cm ² . The third non-embossed ply is interposed between the two embossed plies and is more precisely arranged between the distal surfaces or tops of the protrusions of each of the plies. In other words, the protrusions are oriented towards the inside of the structure. The three plies are combined by passing the latter through the tightening space provided between the two engraved metal cylinders of each of the embossing devices provided for the outer plies. The raised elements or bosses of each of the engraved cylinders are placed face to face. This association technique is more generally called “tip-tip association” (tip against tip). The connection of the three plies is ensured in the case of this patent by the application of a sufficiently high pressure to create interfiber connections; no adhesive is applied to the distal surfaces of the protuberances of the outer pleats.

The manufacturing method described in this prior patent leads to rapid wear of the embossing cylinders due to the high clamping pressure which it is necessary to exercise for the association of the three folds. To the knowledge of the applicant, this process has not had industrial application Finally, this structure is illustrated by products having a low density of patterns (of the order of 10 to 15 protuberances / cm ² ) The products a three plies with this structure are mainly intended to be used as a wiping cloth or household paper towel where resistance and above all absorption are the first qualities sought. For this reason, the embossing patterns are relatively deep, and therefore of low density.

Other absorbent paper products consist of three plies but obtained according to a different association technique. One embosses on the one hand a set of two superposed plies and on the other hand a third fold by means of two distinct embossing devices. The first two superimposed folds as well as the third fold are embossed according to relief patterns made up of protuberances. The density of patterns necessarily remains low: less than 20 protuberances / cm ² for this type of product. Indeed, the two superimposed folds and the third fold are associated by means of a master cylinder so that the distal surfaces of the protuberances of the two superposed folds are arranged opposite the surfaces located between two protuberances in the plane of the third fold. This technique is also called the “nested” process.

A method of associating three plies of this type is described in European patent application No. 0 570 578. It consists in embossing a first and a second sheet separately, itself consisting of the superposition of two sheets, by means of of a first and second embossing device comprising an embossing pattern with a density of less than 20 protuberances per cm ² , at least partially applying an adhesive to the tops of the protrusions formed on the first or second sheet and joining the two sheets to the by means of a non-resilient master cylinder disposed parallel to one of the engraved cylinders of an embossing device so that their protuberances are fitted. In this process, the master cylinder is held in abutment at a predetermined minimum distance from the engraved cylinder.

With a structure of this type, we seek to obtain thick products having a good hand. However, especially for application to toilet paper, the softness is not optimal due to the relatively coarse embossing. In addition, it is necessary to emboss strongly to obtain the desired large thickness.

Finally, other complex products made up of three folds have been found. For example, European patent application No. 0 564 319 decπt a product comprising three folds embossed separately and associated successively. More precisely, small and large protuberances are created by embossing on a first ply, protrusions are created by embossing separately on a second ply. These are separated from each other by the same distance as the small protrusions of the first fold and have a height such that the sum of their height and that of a small protuberance of the first fold is at least equal to the height of a large protuberance of the first fold. The ends of the protrusions of the second ply are glued, a mattress is then produced between the first and second plies by superimposing the ends of the small protrusions of the first ply with the ends of the protrusions of the second ply in the point-to-point position, the large protrusions of the first fold coming to fit between protuberances of the second fold. The separate embossing of a third ply is also carried out, this embossing having a pitch identical to that of the large protuberances of the first ply. The ends of the protrusions of the third ply are glued and the third ply and the mattress formed between the first two plies are assembled so that the ends of the protrusions of the third ply stick in the point-to-point position on the second ply at the large protrusions of the first fold.

The product thus obtained has an improved thickness and rigidity but has a relatively complex structure requiring several levels of gluing. The process is also quite complicated to implement and involves a relatively complex industrial installation.

This process only makes it possible to manufacture embossed products with a pattern density of less than 20 protuberances / cm ² . In addition, the thickness of the products thus obtained, consisting of three sheets, is not optimized.

The object of the invention is to overcome all of the aforementioned drawbacks, concerning both the products and their manufacturing process.

It also aims to provide a new product consisting of at least three plies both thick and soft, having a good hand, and resistant to crushing when rolled, thus offering a combination of properties that the we do not find in existing products.

The object of the invention is also to provide a new product consisting of at least three plies, of the “tip-tip” type, used as toilet paper.

The subject of the invention is a paper absorbent product with a grammage of about 36 to about 105 g / m ² comprising at least three plies, a first and a second embossed external plies each comprising relief patterns consisting at least of part in discrete protuberances oriented towards the inside of the structure and a non-embossed central fold, the folds being associated by connection of the distal surfaces of at least part of the protuberances of each of the external folds with the central fold.

According to an essential characteristic of the invention, each of the embossed outer plies is bonded by means of an adhesive to the central ply, and at least one has a pattern density greater than 30 protuberances / cm ² .

Such a structure surprisingly combines both softness and thickness. In fact, fine embossing, on the one hand, gives the external surface of the finished sheet a great softness to the touch, and, on the other hand, offers very good resistance to the crash. This last property is reinforced by the central fold which prevents any overlapping of the two external folds between them, a phenomenon which would occur if this fold did not exist, due to the small bearing surface offered by such fine protuberances.

According to an advantageous characteristic of the invention, each of the embossed outer plies has a pattern density of less than 90 protuberances / cm ² .

According to another characteristic of the invention, the density of patterns of the outer folds is different. According to another advantageous characteristic, the two patterns are different and allow a partial association, that is to say that the number of connection points is less than the number of protrusions in contact with the central fold. This partial connection mode makes the sheet less rigid. In particular, one of the folds comprises combined patterns, that is to say two different patterns, one of which is a background pattern, and in particular the two combined patterns can be at two different heights relative to the reference plane which is that of the fold.

According to yet another characteristic of the invention, the fibrous and / or chemical composition of the central ply is different from that of each of the embossed outer plies.

The invention also relates to a process for manufacturing a paper towel product comprising at least three linked plies, each of the plies having a basis weight of from about 12 to about 35 g / m ² .

According to another characteristic of the invention, the resistance to delamination of one of the external plies with the central ply is substantially different from the resistance to delamination of the other of the external plies with the central ply.

According to a characteristic of the invention, the method making it possible in particular to obtain a product having a difference in resistance to delamination consists in:

- embossing a first and a second fold with relief patterns consisting of discrete protuberances,

- superimpose a third non-embossed fold on the protuberances of the first of the embossed folds,

- apply an adhesive in particular on the third ply, and

- associate the first embossed fold and third non-embossed fold superimposed, with the second embossed fold, so that the distal surfaces of the protuberances of each of the first and second embossed folds are at least partly face to face and exert sufficient pressure to ensure the bonding of the three plies by the adhesive.

According to an advantageous characteristic of the invention, an aqueous adhesive is applied to the external surface of the third ply opposite the distal surfaces of the protrusions of the first ply. According to another characteristic, an aqueous adhesive is applied to the third ply by spraying with sufficient energy for a part to pass through it and to ensure the connection of the three plies together.

Other characteristics and advantages of the invention will appear on reading the detailed description which follows with reference to the appended drawings in which

FIG. 1 represents in section the structure of a product according to the invention,

FIG. 2 schematically represents the principle of the method according to the invention,

FIG. 3 is a graphic representation of the loss of thickness as a function of the pressure for products according to the invention compared to products of the prior art,

- Figure 4 is a graphic representation of the variation of the thickness of the product according to the invention, for different embossing pressures, compared to that of the prior art products

Referring to Figure 1, the product 1 according to the invention comprises three plies, a first embossed outer ply 2, a second embossed outer ply 3 and a central ply or third ply 4 not embossed or smooth. The three folds are linked. The first embossed external ply comprises protuberances 11 distributed according to a determined constant pitch The second embossed external ply also includes protrusions 33, distributed according to a determined constant pitch different here from the pitch of protuberances 11 of the first ply In the structure of the product according to invention, the protuberances of each of the embossed outer plies are oriented towards the interior. The three pleats are linked at the level of the distal surfaces of the protrusions of each of the outer plies arranged opposite or even in point-to-point position. In the product illustrated in FIG. 1, as the steps are different from one external ply to the other, the connection only exists at the level of the protuberances in at least partial tip-tip position, illustrated by positions A1 and A2, at image of the products made up of two folds decπts in European patent application N ° 0 426 548. This connection is ensured by the presence of adhesive and on the other side of the central fold 4, between this central fold and each of the embossed external phs 2 and 3, at the positions Al and A2.

The product according to the invention has a grammage of about 36 to 105 g / m ² Each of the phs has a grammage of about 12 to about 35 g / m ² and preferably from 12 to 25 g / m ²

At least one of the external plies has a pattern density greater than 30 protuberances / cm ² and mféπ greater than 300 the two external phs preferably have a density less than 90 protuberances / cm ² The pattern density of the external plies can be the same or different. Each of the external folds may also have one or more types of different patterns of different densities. The protrusions can therefore be of different height, the fold then has patterns of different levels. European patent applications No. 0 426 548 and No. 0 797 705 illustrate products embossed according to these principles but comprising two folds.

In the product according to the invention, the central fold is not embossed.

The fibrous and / or chemical composition of the pleats can be the same or different. For example, the central ply may have a fibrous composition essentially based on long fibers such as coniferous fibers, and the outer plies arranged on either side of the central ply and forming the surface of the sheet, an essentially fibrous composition made from short fibers. This combination makes it possible to obtain a more resistant product without sacrificing the softness brought by the short fibers. The central ply may comprise a temporary or possibly permanent wet resistant additive. If this additive is already present in a certain quantity in each of the external folds, the central fold will contain a larger quantity. An example of a wet resistant additive is a compound of the polyamine epichlorohydrin type, marketed under the name KYMENE SLX by the company HERCULES. The outer folds may in turn include a softener or unbinding. The sheet thus formed has very good wet strength and therefore good solidity, in particular due to the composition of the central fold. It also offers a soft surface by the choice of the fibrous and chemical composition of the two outer plies.

Each ply can also consist of one or more layers forming a laminate. The layers in this case may also have a different fibrous and / or chemical composition.

The products according to the invention have very advantageous characteristics compared to products made up of three plies, or even two plies existing on the market.

The thickness of a sheet according to the invention is greater than the thickness of a sheet of a product obtained by a technique called "nested" from folds identical to those of the products according to the invention (same nature, same fibrous and chemical composition, same manufacturing) and embossed so as to have the same final resistances.

This is illustrated by the following example where a standard product sold under the brand Moltonel having a density of 9 spikes per cm ² , and a product according to the same cellulose wadding (tissue) was produced. the invention, that is to say with external folds having patterns different from the standard product (80 spikes per cm ² and different direction and cross direction steps). Standard Invention

Number of phs 3 3 Weight in g / m ² per ply 16, 18, 16 16, 18, 16

Resistance in N / m of the starting tissue:

CD 186 186

MD 334 334

Tissue strength of the embossed end product, N / m

CD 124 129

MD 297 289

Thickness in mm 0.63 0.69

It is therefore found that the thickness of the final product is increased when the latter is manufactured in accordance with the invention, all conditions being the same elsewhere, and in particular by ensuring that it has the same resistance characteristics. This is all the more remarkable since it is generally observed, for an embossing pressure giving the same thickness to the product, that a pattern with 80 pins per cm ² induces a loss of resistance, compared to the base leaf, greater than that induced by a pattern with 9 spikes per cm ² .

It has also been observed that the average thickness of a sheet according to the invention, in a roll where a strip of paper is wound, is greater than the average thickness of a sheet of the known product mentioned above, also wound in roll form. It is therefore possible from the same number of coupons precut in the sheet according to the invention, to increase the volume of the rolls thus obtained. A surprising advantage of the product according to the invention is its resistance to crushing once wound, compared to existing products on the market. Indeed, some known products tend to sag once rolled up, being particularly too soft.

The average thickness of a sheet according to the invention and of a sheet of known products was thus measured by varying the mass of the charges applied to the sheet or sheets. A LHOMARGY MI20 micrometer was used, the probe surface of which was 25 cm ² and set at a descent speed of 2.7 mm s. Pressure (g / cm ² ) 20 80 120 180 200

Thickness (mm)

Product Moltonnel Average of 10 me65 0.48 0.4 0.33 0.31

3 folds nested sure

9 pins / cm ² Loss of thickness 0 -0.17 -0.25 -0.32 -0.34

0% 26.1% 38.4% 49.2% 52.3%

Standard product 2 Average of 10 m 0.64 0.41 0.32 0.25 0.23 tip folds / tip surges Thickness loss 0 -0.23 -0.32 -0.39 -0.41 at 16 pins / cm ² 0% 35.9% 50% 60% 64%

Standard product 2 Average of 10 m 0.63 0.43 0.35 0.27 0.25 tip folds / tip surges Thickness loss 0 -0.21 -0.28 -0.36 -0.39 at 30 pins / cm ² 33.3% 44.0% 57.1% 60.3%

Invention at an average of 10 ME 0.62 0.44 0.37 0.31 0.29

30 pins / cm ² sures

Thickness loss 0 -0.18 -0.25 -0.31 -0.33

29% 40% 50% 53%

Invention at an average of 10 me0.59 0.51 0.45 0.36 0.33

80 pins / cm ² sures

Thickness loss 0 -0.08 -0.14 -0.14 -0.26 13% 24% 24% 44%

Figure 3 gives a graphic representation of the results shown in this table.

It is thus found that the sheet according to the invention resists crushing very well compared to a standard sheet of the point / point type. This resistance is even improved for a higher density of pins.

This behavior of the sheet according to the invention, once wound up, partly explains the possible increase in the volume of the roll, for the same number of precut formats.

Another series of tests was carried out by varying the embossing pressure for products having a first pattern at 16 pins / cm ² and products having 30 pins / cm ² . In both cases, 3 “nested” folds were assembled, that is to say a double fold fitted between the pins of a single fold. The folds according to the invention have also been assembled. The thickness of the assembled sheet was measured for 3 embossing pressures and the values obtained are reported in the table below. The embossing pressure is defined by the length of the deformation or imprint of the rubber cylinder on the engraved cylinder.

Weight Thickness Resistance Elongation g / m ² (mm) MD CD MD%

N / m / 3 Phs

Cellulose wadding 47.2 0.26 381 195 18

Embossing density of 16 pts / cm ²

Invention E = 22 mm 46.1 1.08 345 146 19

Invention, 18 mm 46.4 0.87 382 170 19

Invention, 13 mm 48.1 0.40 432 229 20

Prior art, E = 22 mm 43.5 0.67 279 105 15

Prior art, E = 18 mm 44.9 0.56 349 153 17

Prior art, E = 13 mm 45.7 0.42 397 200 19

Embossing density of 30 pts / cm ²

Invention, E = 22 mm 47.0 0.81 404 183 21

Invention, E = 18 mm 46.3 0.61 433 198 21

Invention, E = 13 mm 47.1 0.49 472 240 23

Prior art, E = 22 mm 44.0 0.48 354 144 16

Prior art, E = 18 mm 44.9 0.42 408 181 18 Front art, E = 13 mm 45..7 0.34 430 217 20

E = fingerprint

It can be seen that, for the same embossing pressure, the product of the invention ultimately has a higher thickness.

This is particularly apparent from the graphical representation in Figure 4.

It is also found that despite the greater thickness the resistances are higher.

These results illustrate the fact that with equal product thickness and according to the prior art, the increase in density induces lower resistances.

It is also observed that for a pattern of 30 pins, a higher resistance of the product of the invention is obtained compared to a product of the prior art in “nested” assembly.

When it is desired to appreciably improve the tactile perception of the product, in particular the softness, it is considered that 30 dots / cm ² is the lower limit of density; however it is not possible to achieve the desired thickness with such a pattern used with a technique of the “nested” type, thus the product according to the invention makes it possible to advantageously combine thickness and softness.

The softness of the products according to the invention was measured by panel. The results show that the products according to the invention are softer than known products consisting of three plies and obtained by a technique called "nested" from plies identical to those of the products according to the invention (same nature, same composition fibrous and chemical, same manufacture).

The product illustrated in FIG. 1 is manufactured according to a process, the principle of which is illustrated in FIG. 2. With reference to FIG. 2, the first fold 2 is embossed in a first embossing device consisting of an engraved cylinder 51 and d a rubber counter-cylinder 52 rotating in opposite directions. The non-embossed central ply 4 is brought to the external ply 2 itself applied against the surface of the engraved cylinder 51. The central ply 4 is superimposed so that the protrusions 1 1 of the first embossed external ply 2 are oriented inward of the structure. An adhesive is applied by means of a gluing device 53 to the surface of the central ply 4, opposite to the embossed outer ply 2. The gluing device comprises an applicator cylinder 54 bearing on the engraved cylinder 51 by means of the central plies 4 and embossed outer 2, superimposed, a transfer cylinder 55 transferring the adhesive from a plunger cylinder 56 to the applicator cylinder 54. The applicator cylinder takes the adhesive from a container. The applicator cylinder exerts a certain pressure on the engraved cylinder at the level of the distal surface of the protuberances of the outer fold 2.

In parallel with the embossing of the first ply 2, the second external ply is embossed separately by means of a second embossing device 60. The latter comprises an engraved cylinder 61 and a rubber counter-cylinder 62, rotating in opposite directions.

Once the adhesive has been applied to the free surface of the central ply, the embossed outer ply 2 and the central ply 4 superimposed are associated with the second embossed outer ply 3 by means of an association device or tightening interval 63 consisting of the engraved cylinder 51 of the first embossing device and the engraved cylinder 61 of the second engraved cylinder, by the so-called tip-tip technique.

The adhesive used can be a standard PVA or hot melt glue. By way of example, an adhesive sold by the company SWIFT was used. This adhesive has been diluted with water in optimal proportions to obtain the appropriate transfer on the folds. It has been observed that the adhesive after its application on the non-embossed central ply and before the association of the three plies at the level of the tightening interval, permeated the central ply without "reaching" the embossed external ply on which the central ply was superimposed. At this stage, no glue could be detected on the surface of the embossed outer ply in contact with the central ply. It is only at the stage of the association of the three plies that the connection of the three phs takes place It is probable that the glue ends up crossing the central ply to reach the embossed external ply when the three phs pass in the tightening interval under the exercise pressure

It appears that the process for producing a 3-ply paper makes it possible to use an installation provided for the manufacture of a traditional two-point / point-type paper without having to substantially modify the elements and the settings.

It can be seen that, although the sizing machine comes into contact with a non-embossed central ply, the transfer of glue takes place only on the ply surfaces which are supported on the pins of the embossing cylinder.

According to another embodiment, not shown, an installation with two gluing units is used. However, it then requires more extensive adjustment operations, and its operation is generally less flexible.

According to yet another embodiment, not shown, a "hotmelt" glue is sprayed by appropriate means on the internal face of the external embossed plies, the third ply is inserted between them, and the whole is assembled. According to this embodiment, the glue can also be applied to the third ply or else between the outer plies and the third ply, or else evenly over the entire surface of the pleats but also on only parts thereof. According to yet another embodiment, not shown, an aqueous glue is sprayed by appropriate means on the central ply, before assembly. It is ensured that the energy imparted to the droplets by the spray is sufficient to obtain a piercing of the central ply. which ensures the association of the three folds. According to this embodiment also, the adhesive can be applied uniformly over the entire surface of the central pleat but also on only parts of it.

Claims

1) Absorbent paper product with a grammage of about 36 to about 105 g / m ² comprising at least three plies, a first and a second embossed external plies each comprising relief patterns consisting at least in part of discrete protuberances oriented towards the inside of the structure and an unembossed central fold, the folds being associated by connection of the distal surfaces of at least part of the protrusions of each of said folds external to said central fold, characterized in that each of said embossed external folds is bonded by means of an adhesive to said central ply, and at least one of the plies has a pattern density greater than 30 protuberances / cm ² .

2) Product according to claim 1, characterized in that each of the embossed outer plies has a pattern density of less than 90 protuberances / cm ² .

3) Product according to claim 1 or 2, characterized in that the density of patterns of the embossed outer plies is different.

4) Product according to one of claims 1 to 3, characterized in that the patterns of each of the outer plies are different, at least one of the plies comprising combined patterns.

5) Product according to claim 4 characterized in that the combined patterns are on two levels.

6) Product according to one of claims 1 to 5, characterized in that the grammage of the central ply is different from the grammage of at least one of the embossed outer plies.

7) Product according to one of claims 1 to 6, characterized in that the fibrous and / or chemical composition of the central ply is different from that of at least one of the external plies.

8) Product according to claim 7, characterized in that at least one of the external plies to a fibrous composition essentially based on short fibers and in that the central ply has a fibrous composition essentially based on long fibers. 9) Product according to claim 7 or 8, characterized in that at least one of the outer plies comprises a softener.

10) Product according to claim 7, 8 or 9, characterized in that the central ply comprises a temporary or permanent wet resistant agent.

11) Product according to one of claims 1 to 10, characterized in that the resistance to delamination of one of the outer plies with the central ply is substantially different from the resistance to delamination of the other of the outer plies with the central fold. 12) Method for manufacturing a paper towel product comprising three linked plies, each of said plies having a grammage of about 12 to about 35 g / m ² and preferably from 12 to 25 g / m ² , characterized in that 'it consists of :

- superimpose the third non-embossed ply on the protrusions of the first embossed ply,

- apply an adhesive to the surface of the third ply, and

- Associating the first embossed fold and third non-embossed fold superimposed, with the second embossed fold, so that, for at least part of the protuberances of each of the first and second embossed folds, at least part of the distal surfaces of the protuberances are facing face and

- exert sufficient pressure to ensure the connection of the three plies by said adhesive. 13) A method according to claim 12, characterized in that the adhesive is applied to the outer surface of the third ply opposite the distal surfaces of the protrusions of the first embossed ply.

14) Method according to claim 12 or 13, characterized in that the adhesive is applied by means of a sizing device comprising an applicator cylinder. 15) Method according to claim 12, characterized in that an aqueous adhesive is applied by spraying on the third ply

16) Use of the product according to one of claims 1 to 1 1 or obtained according to the method according to one of claims 12 to 14, as toilet paper.

17) Use of the product according to one of claims 1 to 1 1 or obtained according to the process according to one of claims 12 to 14, as a napkin or handkerchief.