EP0776758B1 - Method end apparatus for producing a laminated product made of cellulose wad - Google Patents

Abstract

The cellulose fibre tissue product (1), for use as handkerchief or napkin, is made by at least two ply cellulose pads (1a,1b). These are cut to required form and joined together along a peripheral border (3), by adhesive. The join presents a minimal resistance to delamination of 1 g/cm., the border area being less than 50% of total tissue surface area. The adhesive may be on the border of each ply, distributed as discontinuous spots (5). Alternatively, the borders may also be embossed, like waffles. The several ply may have differing composition.

Description

The invention relates to the field of sanitary and domestic paper; she aims at the production of laminated products composed of at least two folds or sheets cellulose wadding, especially for use as a handkerchief, napkin or the like similar applications. A method according to the preamble of claim 1 is known for example from document GB-A 363 699.

The handkerchiefs, generally packaged in cases, which are currently found on the market consist of several sheets of crepe absorbent paper, also called cellulose wadding, superimposed, and held together by a mechanical connection at the periphery. This connection is obtained by an embossing operation, of the steel / steel or steel / paper type, according to which the sheets are passed between two cylinders meshing one on the other. One of the cylinders has reliefs on the surface and the other has corresponding cavities. The sheets are thus locally deformed into zones which constitute attachment points. A known embossing pattern consists of a multitude of spikes of small diameter and of small height tightened against each other linearly, or in both directions in the running direction and in the transverse direction. Another known pattern consists of fine edge bars arranged in tight parallels. This bonding method is satisfactory when the grammage of the plies is not too high, of the order of 10 to 20 g / m ² , and when cellulose wadding is used without additives.

• le choix des motifs de gaufrage est limité ; il est guidé par la nécessité d'obtenir un accrochage entre les plis ;
• il devient inopérant lorsque l'on souhaite utiliser des papiers présentant des caractéristiques différentes entre les plis, un allongement différentiel entre les plis par exemple ou bien une différence de composition fibreuse ou chimique. Ainsi l'addition d'un produit à effet déliant destiné à conférer de la douceur au papier n'est pas possible. On constate dans ce cas qu'il ne se produit aucun accrochage entre les plis.
• Le gaufrage donne un aspect rugueux qui se révèle désagréable pour une application en tant que mouchoir ;

However, it has a number of drawbacks:

• the choice of embossing patterns is limited; he is guided by the need to obtain a hook between the folds;
• it becomes ineffective when it is desired to use papers having different characteristics between the folds, a differential elongation between the folds for example or else a difference in fibrous or chemical composition. Thus, the addition of a debonding product intended to impart softness to the paper is not possible. It is noted in this case that there is no snagging between the folds.
• The embossing gives a rough appearance which is unpleasant for application as a handkerchief;

The invention remedies these drawbacks by providing a method according to the claim 1 and a device according to claims 9 and 11.

Bonding is carried out using any generally used adhesive product in the field of sanitary and household papers to associate folds together such as, for example, a polyvinyl alcohol in solution in an aqueous medium.

Preferably, the bonding is carried out along the four edges of the folds. We assume, to simplify, whether it is a rectangular or square format. The invention also includes the case where only two opposite edges are linked.

Bonding is carried out along a peripheral zone covering a strip the width of which can vary between a lower limit corresponding to a resistance sufficient for delamination and an upper limit where the product would become too rigid. The linked area must represent less than 50% of the product: handkerchief or towel of table. According to a particularly preferred embodiment, said zone represents between 30 and 40% of the total area.

Along this area, bonding can be done by continuous coating of adhesive but also by applying it on a plurality of small surfaces extent arranged in a linear pattern or in uniformly distributed dots. A preferred method of binding is then in the latter case, that described in the application for French patent FR-A-2653793 which ensures uniform adhesive deposition in the area bond without stiffening the sheet.

Admittedly, the Applicant is aware that it is already known to produce towels in cellulose wadding where the folds are glued together. So, for example, the US patent 3673060 describes a napkin produced in this way: two folds of cellulose wadding are placed on top of each other so that their creping lines are parallel to each other, and are glued together by points. It should be noted that this bonding is evenly distributed over the entire surface of the towel according to points close together; bonding limited to the edges of the sheet is not envisaged.

This type of product is not satisfactory since the central area, functional, presents a surface state and a flexibility more or less altered by the bonding.

The proposed solution makes it possible to produce handkerchief type laminate products, towels or the like, that is, coming under the form of individual sheets, having excellent resistance to delamination without being made rigid in the center, that is to say in the functional area of use, nor be likely to irritate the skin by bonding. Tests show that we can very easily obtain products whose resistance to delamination is far superior to that of a mechanical connection of the prior art.

• Le nombre de possibilités offertes au fabricant pour décorer son produit et le rendre plus attractif est considérablement accru.
  Par exemple, il peut ne pas être gaufré à la périphérie ; il reste alors parfaitement plat et son conditionnement est plus facile ;
• On peut teinter la colle de manière à créer un effet de liséré plaisant à l'oeil. L'adhésif étant appliqué entre les plis, les pigments ne sont pas susceptibles de venir au contact de la peau ;
• On peut choisir un motif de gaufrage quelconque sans aucune contrainte sur la forme des reliefs, le motif du gaufrage et le type d'association : pointe/pointe ou emboíté ; on n'est pas lié par la nécessité d'assurer une liaison mécanique entre les feuilles par ce moyen.

Thus the proposed solution offers many advantages:

• The number of possibilities offered to the manufacturer to decorate his product and make it more attractive is considerably increased.
  For example, it may not be embossed at the periphery; it then remains perfectly flat and its packaging is easier;
• You can tint the glue to create an edging effect pleasing to the eye. The adhesive being applied between the folds, the pigments are not likely to come into contact with the skin;
• You can choose any embossing pattern without any constraint on the shape of the reliefs, the embossing pattern and the type of association: tip / tip or nested; one is not bound by the need to ensure a mechanical connection between the sheets by this means.

In accordance with another characteristic of the invention, by bonding peripheral leaf with fibrous and / or chemical compositions different.

In accordance with a particular embodiment, a sheet incorporating is associated an additive to increase the wet strength of the paper to at least a sheet without additives or incorporating an additive to improve smoothness. We in this way obtains a layered complex combining properties that cannot be find together on a single layer product.

According to another embodiment, we associate folds made with different pasta. For example, for a three-ply handkerchief, you can choose to make the central fold with lower cost dough than the cover folds, such as than CTMP or bisulfite.

It is also certain that chemical additives may or may not be incorporated therein. known to those skilled in the art.

Other characteristics and advantages will appear on reading the description nonlimiting which follows with reference to the accompanying drawings on which

Figure 1 represents a product, handkerchief for example, with a zone of peripheral connection of the different folds. A corner has been delaminated to show the folds.

Figure 2 represents an installation likely to allow the realization of a product according to the invention.

Figure 3 shows a detail of the installation in Figure 2.

In Figure 1 there is shown schematically, and seen from above, a handkerchief or a square napkin (1) consisting of 3 sheets (la, 1b, 1c) of cellulose wadding bonded together, by bonding at the periphery, along an area (3) of determined width. According to the embodiment shown, the bonding was carried out by points (5) so as not to stiffen the complex; according to the invention, the central area is not glued; it may, where appropriate, include a embossing to improve its appearance.

The peripheral zone (3) covers less than 50% of the total surface of the handkerchief or towel, preferably this area represents 30% to 40%.

For example a napkin of dimension 40 cm x 40 cm will be bordered by a connecting strip formed by gluing the sheets from the edge line on a width of 4 cm. The linked area thus covers 36% of the total surface of the towel

According to a particularly preferred form of the invention, the connection actually departs from the edge of the folds so as to avoid any yawning of the folds or formation creases on the periphery which affect the appearance of the product.

To make this type of product, any known installation can be used, for example example that shown in Figure 2. The folds (11) and (12), one possibly being double, of cellulose wadding coming from their respective reel, not shown, are guided to pass around the rubber cylinders (13) and (14) then between these and embossing cylinders (15) and (16) made of steel provided with suitable reliefs. These reliefs can be distributed according to the pattern in Figure 1, for example. One of the folds (12) is glued by means of a rubber applicator cylinder (18) shown in FIG. 3. This cylinder comprises, in accordance with one embodiment of the invention, a part (181) in relief whose design corresponds to that of the area device for gluing the sheets, so that the adhesive entrained by the cylinder applicator is distributed according to this pattern. According to this embodiment, one can emboss one or both leaves over their entire surface. Gluing is only carried out on the periphery corresponding to the part (181) of the gluing cylinder. According to another embodiment, one or both cylinders (15, 16) are provided with reliefs, along of a peripheral zone of the desired product format. We can then use a cylinder smooth gluing.

After gluing, the folds (11) and (12) are assembled in the nip formed between the embossing cylinders (15) and (16) which rotate at speeds equal and opposite. The multiply sheet from the device is led to an installation processing where it is cut and folded according to the application considered: handkerchiefs, towels or other.

According to a variant of the method, the folds (11) and (12) can come from a same 2-ply coil, and have been subjected to a common calendering so as to operate smoothing the outer face and imparting greater softness. Then only the two layers are separated to be embossed separately and individually.

According to another variant of the process, not shown, a simple fold is embossed or double, between a rubber cylinder and a steel cylinder suitably engraved, that is to say with reliefs along the periphery of the desired product format. We deposits the adhesive on the tops of the reliefs. Finally we come to apply on the fold a second respectively third fold, by means of a third rubber cylinder of matchmaker type. This third cylinder ensures both the embossing of the second respectively third fold and its marriage with the first. For the third cylinder a steel or paper cylinder can also be used.

A test was carried out to test the behavior of the product on delamination compared to a control handkerchief.

We made a handkerchief with a binder, using an adhesive in solution in water, PVA, 3 ply format 21.5 x 21.5 cm, on the periphery on a 2 cm strip of large.

15 mm wide test pieces were cut from the bonded area of the tissues and the 180 ° delamination test was carried out. This test consists in measuring the average delamination force of a test piece at a determined constant speed of 100 mm / min. For this, the ends of two folds are clamped between two pairs of jaws, the delamination force of which is to be measured, the two pairs of jaws are separated from one another, at constant speed, and the force exerted is measured. Its value is reduced to the unit of width. 180 ° delamination witness linked by simple embossing of the prior art sample with bonding Average force (g / cm) / maximum force noted SM 0.55 / 1 2.4 / 6.4 ST 0.65 / 1 6.2 / 20

It can therefore be seen that bonding makes it possible to produce a product offering resistance strongly increased delamination, both direction of travel (SM) and direction across (ST).

Measurements, moreover, on a large number of samples of existing commercial products have shown that, whatever the reason embossing made either from points or from edge bars, can obtain a constant mechanical bond including resistance to delamination reaches 1 g / cm walking direction or cross direction.

Examples: Product I

We made a handkerchief from 3 plies of cellulose wadding, consisting of 60% softwood fibers and 40% hardwood fibers, each having a basis weight of 18 g / m ² and incorporating an additive, as right 1.5 kg per ton having a deliant effect on the fibers to improve the softness (product marketed by the company ENKA NOBEL under the brand BEROCELL 595). The connection was made by peripheral bonding. Such a product would not be feasible with the prior art of peripheral embossing due to the presence of the additive.

Product II

We made a handkerchief with a central fold made from a mixture of softwood pulps (75%), hardwoods (10%) and a chemical-thermal pulp (grammage: 21 g / m ² ) incorporating an improving additive its resistance characteristics when it is in the wet state (product marketed by the company HERCULES under the brand KYMENE 557 H), and two cover plies made with a mixture of softwood pulp (65%) and hardwood (35% ) (grammage: 14.5 g / m ² ) incorporating an additive (BEROCELL 595) for softness. The connection was made by peripheral bonding.

Product III

We made a control handkerchief from 3 plies (18 g / m ² ) without additives

- Connection by embossing.

The measurement of the resistances, dry and wet and of the bursting, was carried out on specimens of 15 mm wide cut out in the zone of connection of the folds and is expressed in length of rupture for each of the three products (cm) gathered in the table below: I II III Weight measured g / m ² 52.8 49.3 51.8 Thickness (mm) 0.20 0.21 0.18 Dry strength SM 505 630 580 ST 180 280 220 Elongation 10.5% 11% 12.5% Wet resistance SM 130 165 175 ST 52 95 65 Burst Dry 330 440 450 Wet 100 170 115

Compared to control sample III, it can be seen that the invention allows the production of products with a wide range of characteristics depending on the application considered.

Claims (11)

1. Method for production of a fibrous cellulose product such as a handkerchief or napkin, according to which two plies of a continuous strip of cellulose wadding are superimposed, they are bonded to one another along an area which constitutes the periphery of the said product, and represents less than 50% of its surface, and the assembly is cut to the format defined by the said peripheral area, characterised in that before the said individual plies are superimposed, an adhesive substance is applied to one of the said plies, along the said area, such that after the said plies have been assembled, they are bonded directly along the said area, and have a minimum resistance to delamination of 1 g/cm.
2. Method according to claim 1, characterised in that an adhesive substance is coated continuously along the said area.
3. Method according to claim 1, characterised in that an adhesive substance is applied along the said area, on a plurality of surfaces each with a small size.
4. Method according to claim 3, characterised in that the said surfaces with a small size are disposed according to a linear pattern.
5. Method according to claim 3, characterised in that the said surfaces with a small size are disposed according to points which are distributed regularly.
6. Method according to any one of the preceding claims, characterised in that at least one of the plies is embossed, such that the said area has a pattern in relief, and an adhesive substance is deposited on the said reliefs.
7. Method according to the preceding claim, characterised in that at least one of the plies is embossed by means of passage between an embossing roller, which is engraved according to a pattern in relief which constitutes the said area, and a rubber roller, an adhesive substance is deposited on the said reliefs, the second ply is applied to the ply which has received the adhesive substance, and the two plies are associated by means of a third roller.
8. Method according to claim 7, characterised in that the two plies are embossed by means of passage each separately between an embossing roller, which is engraved according to a pattern in relief which constitutes the said area, and a rubber roller, an adhesive substance is then deposited on the reliefs of one of the plies, and finally the two plies are brought together such as to make the said areas coincide, and they are associated by being pinched between the said two engraved rollers.
9. Device for implementation of the method according to any one of claims 6 to 8, of the type comprising an embossing roller (15 or 16), which co-operates with a rubber roller (13 or 14), a roller (18) for application of adhesive substance along an area which constitutes the periphery of the product, the applicator roller cooperating with the said embossing roller, and a roller (16 or 15), which co-operates with the embossing roller (15 or 16), characterised in that the embossing roller comprises a part in relief which corresponds to the said peripheral area.
10. Device according to the preceding claim, characterised in that it comprises a cylinder of the matching type, for association of the plies.
11. Device for implementation of the method according to any one of claims 6 to 8, comprising two embossing rollers (15, 16), two rubber rollers (13, 14) and a roller (18) for application of adhesive substance along an area which constitutes the periphery of the product, characterised in that the applicator roller (18) comprises a part (181) in relief, which corresponds to the said peripheral gluing area.

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