Embossed paper multi-ply material and machine for the production thereof

Technical field The present invention relates to improvements to multi-layer materials made of paper, in particular so-called tissue paper, for example for the production of absorbent articles, toilet paper, kitchen towels and the like.

Background Art [0002] In the field of tissue paper making and processing, it is well known to make multi-layered articles in which two or more extruded layers of tissue paper are joined together by laminating and gluing according to various techniques.

[0003] For example, US-A-3961119 describes a two-layer material in which two layers are extruded separately into screw patterns with different slopes and are joined at the intersection of the screw patterns.

[0004] Document US-A-6470945 describes a device for extruding layers that, when joined together, form a web material with layers connected to the tip to the tip or, respectively, nested. The tip-to-tip connection is intended to create a connection in which the protuberances of one layer at least partially correspond to the protrusions of the other layer. Conversely, a nested joint is intended to create a joint in which the protuberances of one layer are nested between the protrusions of the other layer.

[0005] Other extruded multilayered products and devices for their production are described and illustrated, for example, in documents US-A-6261666, US-A-6109326, US-A-2003/0102096, US-A-6136413, WO-A00 / 78533, US-A-6681826, US-A-3414459, US-A-5173351, US-A-6032712, US-A-6245414, WO 99/44814. [0006] Document US-A-4 320 162 describes a multilayered article with two extruded layers with equal embossing on both surfaces, i.e. two layers. The embossing is arranged tip-to-tip and is formed by large protrusions with a large front surface, between which are protuberances of smaller height and smaller size.

[0007] Extruded multilayer paper materials must meet a number of requirements that often contrast with each other, such as in particular: softness, absorption capacity, thickness, mechanical strength, also when they are soaked in liquid, the ability to remove materials from surfaces cleaned using extruded paper, and other requirements.

[0008] Research is constantly being carried out to identify extrusion, laminating and layer bonding techniques that allow optimizing the performance of these materials from many points of view, including those that contrast with each other.

Summary of the invention

ΕΡ 2 095 935 Β1 [0009] According to one aspect, one of the purposes of the present invention is to provide a multilayer roll paper material, in particular one that forms a plurality of layers of material made of extruded tissue paper that has improved properties over traditional products, at least in one or some respects.

[0010] According to one embodiment, the multilayer material made of embossed tissue paper in accordance with the present invention comprises at least one first outer layer and at least one second outer layer, which layers are joined together according to the first protrusions obtained on one and the other the other of these layers and directed inwards. The connection is tip-to-tip, i.e. a connection in which the protrusions obtained on the first layer correspond to the protrusions obtained on the second layer. Preferably, two inner layers are included between the two outer layers, one or both of which are preferably extruded. In contrast to traditional tip-to-tip products, according to the present invention (apart from the first series of tip-to-tip tips, obtained on both the first and second outer layers, and extending linearly to form extensive surface-decorative patterns), for both outer layers a second series of protrusions are also provided, directed also inside and forming a background pattern, which preferably consists of numerous protrusions of simple geometrical shape, for example and in particular of the shape of a truncated pyramid or a truncated cone.

[0011] The layers are joined together by gluing and laminating according to at least the protuberances of the first and second layers that run linearly.

[0012] According to a preferred embodiment, the protuberances having the shape of a truncated pyramid, a truncated cone or any simple geometrical shape forming a background embossing pattern have a front surface area of ​​the protuberances equal to or less than 4 mm².

[0013] Preferably, the background protuberances have a density comprised between 2 and 25, and more preferably between 3 and 8 protuberances / cm².

[0014] According to some preferred embodiments, the first extruded protuberances, or at least some of them, both on the first and second outer layers, preferably form closed lines within which areas or parts of the respective layers are limited, with or without substantially extrusion. , i.e. smooth areas. Preferably, these areas form bulges directed outwards of the multilayer material.

Preferably, according to some embodiments, at least the third layer, and preferably both the third and fourth inner layers of the multilayer material are extruded.

[0016] The embossing obtained on the third and / or fourth inner layer are formed by protrusions directed outwards, i.e. directed towards the first and second outer layers of the multilayer material, respectively.

[0017] In order to obtain a product with a larger thickness that is not prone to creasing or collapsing during packaging, for example when being rolled into rolls, the geometric protrusions of the third and fourth layers disposed within the first and second outer layers are preferably arranged in at least some zones or areas without extrusion, limited by linear

EP 2 095 935 -1 embossed protrusions of the first and second layers so as to support these non-extruded areas and keep them bulging and projecting out of the multilayer material.

[0018] In this way, a certain soft material is obtained with a considerable apparent thickness and a highly aesthetic appearance due to the wide embossing pattern, limited by the linear protuberances of the two outer layers. The thickness of the material is also maintained after it has been rolled up, for example for dfa shaping or kitchen towels, due to the presence of the geometric protuberances of the two inner layers, which are placed inside the non-extruded areas bounded by the linear protuberances of the two outer layers, i.e. they nest between said linear protuberances.

[0019] Further advantageous properties and embodiments of the multilayer material of the present invention are defined in the appended claims and will be described in more detail below with reference to some non-limiting embodiments of the invention.

[0020] According to a further aspect, the invention also relates to an extrusion device or unit for producing the coil material as defined above.

[0021] Basically, in one embodiment of the invention, the device comprises first and second embossing rollers which cooperate with the first and second pressure rollers respectively, and both are provided with first linearly extending protrusions, the first protrusions of the first and second rollers being arranged in tip-to-tip arrangement. Both embossing rollers, first and second, contain second protrusions forming a background pattern.

Brief Description of the Drawings [0022] The invention will be better understood upon reading the description and the attached drawings, which show non-limiting practical embodiments of the invention. More specifically, with reference to the attached drawings:

figure 1 is a top view of part of the web material of the present invention; figure 2 is a substantially enlarged schematic section according to line II-II in figure 1; figure 3 is a diagram of the device or extrusion unit for producing the web material of the type illustrated in figures 1 and 2,

Detailed Description of Embodiments of the Invention [0023] Figure 1 is a top view of the portion of the multilayer material of the present invention, designated as a whole by number 1. Figure 2 shows a significantly enlarged and schematic cross section, according to line II-FL in figure 1, of material 1, from which it can be seen that the material is formed of four layers, more precisely: of the first outer layer V1, the second outer layer V2, the third inner layer V3 sandwiched between layers V1 and V2, and a fourth inner layer V4, also sandwiched between layers V1 and V2. More specifically, layer V3 is sandwiched between layers V1 and V4, and layer V4 is sandwiched between layer V3 and layer V2.

ΕΡ 2 095 935 Β1 [0024] According to a preferred embodiment, the outer layers V1 and V2 are extruded in the tip-to-tip pattern, i.e. in such a way that the protrusions of the V1 layer have the same shape or substantially the same shape as the protrusions of the V2 layer and correspond in a system in which the front surfaces of the protuberances of one layer correspond to the front surfaces of the protrusions of the same shape of the other layer.

According to a preferred embodiment, both the layer V1 and the layer V2 have the first protuberances, designated by numbers 5 and 7, respectively, for layers V1 and V2, which are linear, i.e. they are larger in longitudinal than transverse dimensions . In some embodiments, both protrusions 5, 7 have a length of at least 10, preferably 20 times, and more preferably 50 times the transverse dimension of the width of the protuberance itself.

[0026] According to some preferred embodiments, the protrusions 5 and the corresponding protuberances 7, or at least some of them, have a closed shape, i.e. such a shape that defines the areas designated by the letter A in figure 1, which are completely or almost completely surrounded by the respective linear protuberances 5, 7. In some embodiments, the so restricted areas A are non-embossed, i.e., they are substantially smooth, i.e., not convex. They are preferably bulging, i.e., they protrude outside the multilayer material 1, forming some kind of protrusions, bubbles or bulges, while the protuberances 5 and 7 are directed inside the multilayer material 1.

[0027] In addition to the projections or linear protrusions 5, 7, both layers V1, V2 have further protrusions 9, 11, which are also arranged preferably in a tip-to-tip arrangement and, as can be seen in Figure 1, and have a simple geometric shape. In some embodiments, the protrusions 9, 11, also inwardly facing the multilayer material 1, have the shape of a truncated pyramid or a truncated cone, with a frontal area preferably less than 4 mm².

[0028] In some embodiments, as shown in Figures 1 and 2, the inner layers V3 and V4 are provided with protrusions 13, 15 facing outwards, respectively, i.e. protuberances 13 located on layer V3 facing the outer layer V1 and protuberances 15 located on layer V4 facing the outer layer V2. In some embodiments, the protrusions of the layers V3 and V4 have varying heights, as shown, for example, in the embodiment of Figure 2. In this case, the V3 layer has protrusions or protrusions 13 and protrusions 13 wysokości with heights H and h, respectively, and on layer V4 there are protrusions 15Χ and 15 with heights H and h.

[0029] In some embodiments, a plurality of protrusions 13 of the V3 layer and protrusions 15 of the V4 layer are arranged, respectively, to areas A of layers V1 and V2 delimited by linear protrusions 5, 7. In this way, the bulges formed in the zones or areas A bounded by the linear protuberances 5, 7 are supported by the protrusions 13, 15 formed on the inner layers V3, V4 and directed outwards, being in the nested arrangement within the linear protuberances 5, 7. This makes it easier to maintain the overall thickness, indicated by the letter S, of the multilayer material 1 also when it is rolled up to form, for example, a roll of kitchen towels, toilet paper and the like.

[0030] For the sake of simplicity of the drawing, in figure 2 the protrusions 13Χ are shown only at an angle at the very bottom, where the layer V1 is raised so as to show the embossed structure below. Conversely, on smooth areas A surrounded by protrusions 5, protrusions 13 of the layer

EP 2 095 935 poniżej1 below is shown in dashed lines to show how they are arranged to support parts of the layer in extrusion-free areas A.

[0031] The protrusions 13Χ, 15Χ may have a smaller height than the protrusions 13, 15, as can be seen in figure 1, since they do not have to perform a specific supporting function. However, it is possible for the projections or protrusions 13Χ, 15Χ to have a height equal to the height H of the protrusions 13, 15, [0032] Finally, with this type of configuration, material of considerable thickness and high softness can be obtained that is resistant to crushing or collapsing, has good detergent properties due to the presence of linear protrusions 5, 7, which form on the outer surface of the material 1 layer, linear cavities for collecting impurities, such as, for example, dust, liquid and other collected from the surface, which are purified by means of material 1.

[0033] Preferably, layers V1 and V2 are glued to each other by laminating to protrusions 5, 7 and 9, 11 respectively, in a tip-to-tip arrangement, all these protrusions having the same height, or at least protrusions 5, 9 have such the same height and correspondingly protrusions 7, 11 have the same height. In the modified embodiment, the height of the protuberances 9, 11 may vary, and in particular may be less than the height of the protuberances 5, 7.

[0034] The protrusions 13, 15 can be arranged with different densities, for example the protrusions 13, 15 can be packed more densely than the protrusions 13Χ, 15Χ, to provide a more effective support for bulging areas A.

[0035] In some embodiments, the density of the protrusions 13, 15 and / or the protrusions 13Χ, 15Χ may be between 5 and 10 protuberances / cm².

[0036] The dimensions of the protrusions 13, 15 and 13Χ, 15Χ may be such that they form, at the upper ends of the surface area (i.e. those that are directed outwards), protuberances equal to or less than 4 mm².

[0037] Multilayer material 1 of the type described above can be obtained, for example, by means of an embossing device or unit of the type schematically shown in Figure 3 and designated as a whole with the number 20. In some embodiments, the embossing unit includes a first embossing roller 21 and a second embossing roller 23 equipped with mirror engravings to extrude the tip to tip and laminate the first outer layer V1 with the second outer layer V2 of multilayer web 1.

[0038] The surface configuration of the rollers 21 and 23 essentially reflects the shape of the protuberances 5, 9 for one of the rollers and 7.11 for the other roller.

[0039] The embossing rollers 21 and 23 cooperate with the pressure rollers 25, 27, respectively, for example covered with rubber or other elastically deformable material so as to extrude separately from each other layers V1 and V2 carried out along respective paths around the pressure rollers 25, 27 and in the clamps between the rollers 25, 21 and 27, 23 respectively.

[0040] Between the embossing rollers 21 and 23 a laminating clamp 29 is defined, through which the extruded layers V1, V2 are passed and to which said layers are mutually laminated by sticking together thanks to the adhesive applied by one or the other of two glue dispensers 31.33 .

[0041] In addition to the extrusion and pressure roller pairs 21, 25 and 23, 27, the extrusion unit 20 comprises a further third extrusion roller 35 and a fourth extrusion roller 37 that cooperate with,

ΕΡ 2 095 935 Β1, respectively, a third 39 and fourth 41 pressure roller coated with elastically deformable material such as rubber or other material.

[0042] The third layer V3 and the fourth layer V4 are passed along the respective paths through the extrusion unit 20 and are separately extruded in the clamps defined between the pressure roller 39 and the extrusion roller 35 respectively, and between the pressure roller 41 and the extrusion roller 37. Extrusion rollers 35, 37 have engravings with projections corresponding to protrusions 13, 13Χ and 15, 15Χ produced by rollers on the inner layers V3 and \ Z4. As can be seen from the diagram of Figure 3, the arrangement of the rollers is such that the projections of the rollers 35 and 37 produce on the layers V3 and V4 the respective protrusions directed at the layers V1 and V2 in the clamp between the roller pairs 21, 35 and 23, 37. In this way, protuberances 13, 13Χ produced by the extrusion roller 35 and protrusions 15, 15Χ produced by the extrusion roller 37 are directed outside the multilayer material 1.

The arrangement of two glue dispensers 31, 33 enables the glue to be applied to the protrusions 5, 9 obtained on the layer V1 by means of the dispenser 31 and on the protrusions 7, 11 produced on the layer V2 by the extrusion roller 23 by means of the glue dispensing unit 33 so as to have enough glue to stick together by laminating four layers V1, V2, V3 and V4 in clamp 29.

[0044] It is understood that the drawings only illustrate an example provided within the framework of the practical arrangement of the present invention, which may vary in form and arrangement without departing from the scope of the concept underlying the invention.