EP2146610B1 - Roll of absorbing product sheets of the toilet paper type - Google Patents

Description

The present invention relates to a roll for toilet paper use according to the preamble of claim 1.

It relates to a roll composed of articles based on (or essentially made from a) fibrous cellulosic product. More particularly, it relates to a roll of which each sheet which composes it has particular characteristics related to its thickness and to its tensile strength.

Products of the aforementioned type packaged in the form of rolls are already known in general. In these rolls, the sheets of product to be dispensed are usually wound on a central mandrel of cylindrical section made of cardboard or the like. In the field concerned, said wound sheets of interest to the user are conventionally produced from fibrous cellulosic products in (or mainly in) cellulose wadding and assembled in the form of one or more superimposed linked plies, said sheets being able to be separated. between them, in the direction perpendicular to the direction of unwinding of the sheets, by so-called pre-cut perforated lines making it possible to tear or detach one or more sheets from the roll.

The document FROM 2,238,005 discloses cellulose wadding or paper products, in particular multiply paper products.

The document EP 1,400,199 discloses a roll of toilet paper and its production method.

The document US 4,601,938 discloses an article suitable for cleaning surfaces, said article being in the form of an impregnated wet substrate.

In the case of rolls of plywood sheets, the different superimposed plies are, depending on the intended use of the sheet and / or the requirements imposed by consumers and / or production constraints, more or less strongly linked together using different techniques for assembling said plies.

Most often, the combination of plies in a multiply product essentially of cellulose wadding is carried out by applying an adhesive between said plies. Said bonding is carried out by means of any adhesive product generally used in the field of sanitary and domestic papers to combine folds with one another such as, for example, a polyvinyl alcohol in solution in an aqueous medium. This association by gluing can be combined with another type, just as classic, of association of plies which is purely mechanical and which consists in locally deforming, by crushing, the plies so that the latter, nested in each other under the pressure of a cylinder, be held together after the pairing operation is complete.

From a certain number of folds to be associated, in particular when more than three folds or group of folds are associated, problems of various kinds may appear.

First of all purely technical problems of association of folds. We know different ways to overcome them. But in most cases, the thick sheets are not flexible. "Thick" here means "greater than 0.75 mm".

Furthermore, it is known that the thickness can adversely affect the bond between the successive sheets, at the level of the pre-cut lines which usually constitute the bond between the sheets forming the roll. Problems of breakage have already been observed at this level: for example the sheets are detached from each other on the roll itself.

Surprisingly and unexpectedly, the rollers according to the invention do not exhibit such drawbacks.

In addition, sheets that are too stiff are not suitable for use as toilet paper.

In addition, when it comes to making rolls, the sheets which constitute it must be able to wind up easily even in the center of the roll where the radius of curvature is smallest.

Another very important parameter for toilet paper applications relates to the thickness and the dry resistance of the sheets constituting the roll.

As it appears in the table below, and contrary to popular belief, when the existing products are thick, they are not particularly resistant however, in particular in the transverse direction that is to say perpendicular to the direction of unwinding of the roller.

However, it is very important for uses as toilet paper, that the product is both thick and resistant.

Thus, the invention relates to a roll for toilet paper use, formed of a wound strip of a fibrous cellulosic product, said strip comprising at least three superimposed and associated plies, said strip having a tensile strength R _ST according to its width.

In accordance with the invention, the product P of the total thickness E of the strip by its resistance R _ST is greater than 190 mm.N / m, E being expressed in mm and R _ST in N / m: P = E x R _ST and P> 190 mm.N / m.

This feature ensures in particular a completely remarkable, new and unexpected comfort and reliability of use.

The invention therefore relates to a multi-ply product according to which “ply” can be understood as a group of plies in the sense that a group of plies is a set of several folds superimposed and associated with one another in the wet phase.

According to the invention, at least one of the plies forming said strip is manufactured in the wet phase according to a TAD type technique and / or at least one of the plies forming said strip is manufactured according to a CWP type technique.

The TAD type ply can preferably be placed so as to be visible on the outside of the roll.

Furthermore, the basis weight of said strip is between 30 and 150 g / m ² , preferably between 85 and 115 g / m ² .

• la figure 1 est un exemple de rouleau selon l'invention ; et
• la figure 2 est une coupe transversale d'une feuille selon un mode de réalisation de l'invention.

Other characteristics, details and advantages of the present invention will emerge better on reading the description which follows, given by way of illustration and in no way limiting with reference to the appended drawings in which:

• the figure 1 is an example of a roller according to the invention; and
• the figure 2 is a cross section of a sheet according to one embodiment of the invention.

Thus, the roll according to the invention is intended for use as toilet paper. Such a roll corresponds to the following definition: an external diameter greater than 60 mm, usually of the order of a hundred mm and possibly reaching 200 or even 300 mm in the case of use in communities.

The cellulose wadding strip forming the rolls targeted by the invention may have a width of between 80 and 120 mm, and it may or may not have pre-cuts (30) transverse to its length, preferably arranged at regular intervals.

When pre-cuts (30) are present, a succession of sheets (10, 20) is therefore formed and it is considered, within the meaning of the invention, that a sheet for use as toilet paper has a length of between 90 mm and 250 mm, and a width between 80 mm and 120 mm.

Moreover, the sheets are interconnected by perforations and tenons, the percentage of which can vary from 10 to 70%; the perforations (or incisions) may or may not be evenly distributed over the width of the strip.

Currently, the basis weight of such strips is between approximately 70 g / m ² and 150 g / m ² .

In addition, each ply constituting the wound strip can be manufactured beforehand in a wet process according to a technique called CWP, well known to those skilled in the art and which therefore will not be explained further.

The multiply wound strip according to the invention can only comprise folds thus formed.

Without departing from the scope of the invention, the plies can be manufactured in the wet phase according to a technique known as TAD (through air drying) known in itself and which consists, overall, in projecting a set of paper fibers on a fabric in order to forming a mattress, in transferring this mattress against the surface of a porous drying cylinder, in making the mattress pass through jets of air coming from said cylinder, then in transferring the fold thus formed onto a so-called creping cylinder. One or more folds are thus formed.

Wet-formed folds are known from the application EP 1,353,010 .

The combination of folds can be achieved with an installation which may or may not include a gluing unit.

The invention further relates to multi-ply sheets comprising both plies obtained according to a conventional technique (called CWP) and plies produced according to the TAD technique.

The TAD type folds can constitute the two outer faces of such sheets. A very soft feel is then obtained. The interior plies can be made using a CWP or other technique.

Without departing from the scope of the invention, the outer plies can be produced in a wet process according to a conventional technique (CWP) and form the two outer faces of the sheet. In this configuration, the interior plies can be made using a TAD type technique.

Of course, a combination of plies aiming to obtain a sheet having a face formed of a conventional ply and a face formed according to a TAD type technique, can also be produced without departing from the scope of the invention.

One or the other of the combinations will be chosen according to the specific case, that is to say according to the touch, the absorption, the flexibility which is primarily desired, and again according to constraints of an economic nature.

The figure 2 gives an example of a sheet comprising three folds 1, 2, 3 superimposed and associated with each other at certain points 4.

Furthermore, it is perfectly conceivable to produce a wound strip according to the invention without using glue to combine the folds, whatever the nature. of each of the plies (or group of plies) which constitutes said wound strip.

In a new and unexpected way, it has been observed that a roll for toilet paper use formed from a wound strip whose thickness and resistance in the transverse direction are such that P = E x R _ST > 190 mm.N / m, presents notable advantages over the prior art. The comparative table below gives the following values: Product Thickness ST resistance Product mm N / m E x Rst 9 folds 1.11 392 435.1 INV TAD 5 ply (1tad + 3cwp) 0.77 365 281.1 6 folds 0.9 260 234.0 INV TAD 5 ply (2tad + 1cwp) 0.93 242 225.1 7 ply 0.94 234 220.0 Moltonel 0.62 180 111.6 Lotus Comfort 0.32 97 31.0 Lotus Small Flower 0.33 87 28.7

In this table R _ST is the tensile strength of the strip wound in a direction perpendicular to the direction of unwinding of the roll.

The “tensile strength” or more precisely “tensile strength” defined in standard NF EN 12625-4, part 4, is the maximum tensile force, supported per unit width of a tissue paper test piece. or tissue product until breakage, in a tensile test. The principle of this test is to stretch to rupture, at a constant elongation speed of 50 mm / min, a test specimen 50 mm wide and at least 250 mm long.

To do this, the samples to be measured are successively placed between two jaws of a testing apparatus (as precisely defined in standard EN 12625-4): at least 20 samples are subjected to the test.

The jaws of the apparatus move away from each other at a constant speed of about 50 mm / min, all significant values of the forces during the breaking of the samples are recorded.

Avec wi : largeur initiale de l'éprouvette (normalement 50 mm).Then the average of said breaking forces is calculated: F (expressed in N), in order to determine the average tensile strength Fm expressed in N / m such that: $$\mathrm{Fm}=\frac{\mathrm{F}\times {10}^3}{\mathrm{Wi}}$$

With wi: initial width of the specimen (normally 50 mm).

For the preferred applications of the invention, R _ST is between 200 and 500 N / m and preferably greater than 250 N / m, provided that the product P is greater than 190 mm.N / m.

E is the measured thickness of the sheet (or of the strip) obtained according to European standard EN 12625-3, while Ep is the average thickness of a fold of said sheet. More precisely Ep is the total thickness of the sheet divided by the number of folds forming said sheet (in strip).

For the purposes of the invention, the thickness E is between 0.75 and 1.5 mm, preferably around 0.90 mm.

The above comparative table clearly shows that the products according to the prior art, namely those corresponding to the last three lines of the table named “MOLTONEL”, “LOTUS CONFORT” and “LOTUS PETITE FLEUR” have a product P less than 190 mm .N / m.

The “MOLTONEL”, “LOTUS CONFORT” and “LOTUS PETITE FLEUR” products correspond to rolls of toilet paper manufactured and marketed by the applicant under these three registered trade names; and whose sheets consist of two or three folds, of the CWP type.

Claims (5)

1. Roll for use as toilet paper, formed of a rolled strip of a cellulose-fibre product, said strip comprising at least three superposed and associated plies (1, 2, 3), said strip having a tensile strength R_ST across its width (1), characterised in that:

   said strip has a total thickness E between 0.75 and 1.5 mm inclusive measured according to the ISO standard 12625-3,

   the product P of the total thickness E of the strip times its strength R_ST is greater than 190 mm*N/m, and

   at least one of the plies of which said strip is formed is wet laid using a technique of the TAD type and/or at least one of the plies of which said strip is formed is wet laid using a technique of the CWP type.
2. Roll according to claim 1, characterised in that it consists of a succession of sheets (10, 20) that can be separated from one another along precut lines (30).
3. Roll according to claim 2, characterised in that each sheet (10, 20) has a length between 90 mm and 250 mm inclusive and a width between 80 mm and 120 mm inclusive.
4. Roll according to any one of the preceding claims, characterised in that each ply of which said strip is formed comprises a group of plies.
5. Roll according to any one of the preceding claims, characterised in that a basis weight of said strip is between 30 and 150 g/m² inclusive, preferably between 85 and 115 g/m² inclusive.

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