ITPI20090010A1 - PAPER PRODUCT IN VEIL WITH HIGH ABSORPTION CAPACITY AND RELATIVE REALIZATION METHOD. - Google Patents

Description

Description attached to the patent application for industrial invention entitled: PAPER PRODUCT IN VEIL WITH A HIGH ABSORPTION CAPACITY AND RELATIVE MANUFACTURING METHOD.

TECHNICAL FIELD

The present invention relates to a paper product in web with a high capacity for absorbing liquids.

In particular, the invention refers to a paper product composed of one or more layers comprising cellulose pulp, such as for example tissue-type paper, for the production of rolls for domestic and / or industrial use, napkins or handkerchiefs of paper with hygienic-sanitary use in which, in particular for kitchen rolls and / or for industrial use, the characteristics related to the water absorption capacity are very important.

STATE OF THE ART

Paper for domestic and / or industrial use is usually composed of at least two coupled layers, smooth or with raised motifs obtained by embossing, and joined together at the tips by gluing, by pressure or by other methods.

The absorption capacity and the time in which a certain amount of liquid is absorbed, i.e. the absorption speed, are fundamental parameters of papers for domestic and / or industrial use and are mainly influenced by the chemical-physical characteristics of the paper product, and in in particular from the quantity, type and distribution of the fibers.

With the same chemical-physical characteristics, even the presence of embossing on the surface of the paper product is able to improve the absorption capacity parameter.

In fact, water absorption tests show that, compared to smooth paper, as the depth of the embossing impressed on the layer increases, there is an increase in the water absorption capacity, even if this occurs with a proportional increase in the time taken to complete said absorption, i.e. with a reduction of the absorption rate.

Further absorption tests have also shown how the absorption capacity increases if the embossing is designed in such a way as to cause tears or punctures in the paper structure.

In the GB 816,284 patent an absorbent paper is described and claimed, the absorption capacity of which is improved by carrying out processes on it suitable to create ridges and depressions on the surface in which, during these processes, in specific areas the paper is subjected to a shearing action. , due to the particular timing of the two embossing rollers, such as to cause an elongation in the paper that exceeds its elastic limit and possibly up to the formation of cracks or openings on the surface. The overcoming of the elastic limit of the paper is obtained in the sloping sections of connection between a ridge and the subsequent depression by virtue of the approach of two engraved surfaces in which the protuberances of one correspond to the depressions of the facing surface so that the distance between the surfaces is less than the thickness of the paper only in the sloping sections of connection between a ridge and the next depression. The presence of cracks in the surface of the paper interrupts and reveals a part of the fibers of which it is composed, thus increasing the water absorption capacity of the paper itself. However, the presence of cracks inevitably causes a worsening of the mechanical characteristics of the paper, in particular the tensile strength in both dry and wet conditions.

A different location, shape and size of the fractures could lead to even greater increases in the absorption capacity, compromising less significantly the aforementioned mechanical characteristics.

Patent GB 1,395,447 describes and claims a paper product for hygienic-sanitary use of great softness, and relative manufacturing method, which at the same time has a high capacity of elastic elongation in all directions of the surface without important compromise of the mechanical resistance. These characteristics are obtained by means of fractures or openings formed on the surface of the paper and elongated in specific directions, in particular in the direction of feeding the paper web. However, the aforesaid invention does not solve the problem of increasing the absorption capacity of the product.

GB 1,443,624 describes a paper product in which two layers are coupled in specific coupling areas and these areas can be perforated to allow the coupling of the two layers without having to resort to adhesives. Even in this last document, the presence of cracks or openings on the paper is not aimed at solving the problem of increasing the absorption capacity.

Certainly, many other paper products and related manufacturing methods have been studied and patented to increase the water absorption capacity of a paper product, however, with the exception of those mentioned above, no document of the known art describes found able to improve the aforementioned characteristic through the presence of cracks and / or openings suitably positioned and sized on the surface of the paper.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a paper product composed of one or more layers with innovative characteristics, in particular in relation to the water absorption capacity and the absorption speed.

A further object of the present invention is to propose an absorbent paper product composed of one or more layers capable of overcoming the limits highlighted above of the known art.

Another object of the present invention is to propose a paper product composed of one or more layers in which excellent water absorption characteristics are obtained without generating increases in the costs of the raw materials used since the addition of any special material is not required, such as for example superabsorbent powders SAP or other.

Another object of the present invention is to propose a method for the production of a paper product composed of one or more layers with high water absorption capacity with very low production costs, which can be achieved with machines present in the current technique by simply replacing some components. .

The aforementioned purposes are achieved by means of a paper product with a high liquid absorption capacity composed of one or more layers, comprising at least one paper layer with a weight of between 10 and 100 gr / m <2> provided on at least one side with embossed motifs. consisting at least in part in a first series of discrete protuberances distributed in said pattern in which at least a part of them has cracks located at the top. Advantageously, the protuberances of said first series have a density greater than 5 protuberances per cm <2> and at least 40% of them have cracks at the top.

Advantageously, the protuberances with cracks at the top have a greater base area than the area of the top and the cracks consist at least in part of openings with an area lower than the area of the base of the protuberances.

The protuberances with breaks or openings at the top can also be located on a single face of said paper layer depending on the type of product to be made.

Advantageously, the layer comprises a second series of discrete protuberances having a height and base area greater than the height and base area of the perforated protuberances of said first series of protuberances, the protuberances of said first series being located in the areas of separation between the protuberances of said second series and / or on the surface of said protuberances of said second series and having a concordant orientation with these.

Still advantageously, the protuberances of said first series protrude in the opposite direction with respect to the protuberances of said second series.

The aforementioned purposes are also achieved by means of a method for processing a paper product in web suitable for the production of a paper product with a high capacity to absorb liquids as outlined above in which at least one deformation step of said paper product is provided. during which at least one paper layer of said paper product is engraved by means of sharp protuberances suitable for forming in said layer protuberances provided with breaks and / or openings at the top.

Advantageously, the aforesaid step of engraving the paper product takes place by feeding at least one paper layer of which said product is made between two cylinders, at least one of which is provided with sharp protuberances.

In particular, both cylinders can be provided with sharp protuberances in case it is desired to obtain a layer having protuberances with top opening on both its faces.

Tests carried out have shown that a paper product as outlined above has obvious advantages in relation to the absorption characteristics of liquids. In particular, the speed of water absorption is much higher than that of traditional paper products for the same type of base paper used. Furthermore, there is a simultaneous increase in the amount of water absorbed compared to that of traditional paper products for the same type of base paper used.

Another advantage of the paper product of the invention is related to the reduction of the very limited mechanical strength compared to what occurs in paper products of the known art with fractures on the surface.

Another advantage of the invention consists in the possibility of making the paper product itself using machines of the known technique, with the simple replacement of a few components of the same and the addition of at least one simple but peculiar processing step.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other advantages associated with the paper product with a high water absorption capacity composed of one or more layers according to the present invention, and with the related manufacturing method, will however be more easily understood by illustrating non-limiting embodiments, such as described below with the aid of the attached drawing tables, in which:

- Figure 1 represents a top view of a paper product according to the invention;

- figure 2 represents a sectional view taken along the plane marked II-II of fig.1;

- figure 3 represents a top view, similar to the view of fig.1, of a different embodiment of the paper product of the invention;

- figure 4 represents a sectional view, similar to the view of fig.2, of a further variant of the invention;

- figure 5 represents a sectional view, similar to the view of fig.2, of another variant of the invention;

- figure 6 represents a top view, similar to the view of fig.1, of another embodiment of the paper product of the invention;

- figure 7 represents a sectional view taken along the plane of line VII-VII of fig.6;

- Figures 8 to 12 represent sectional views, similar to the view of Fig. 2, of some further embodiments of a multi-layer paper product according to the invention;

- Figure 13 represents a schematic sectional view of a device for carrying out processes suitable for the realization of a paper product of the invention according to the method of the invention;

- Figure 14 represents a detailed view of the work area of two cylinders suitable for making a paper product of the invention according to a variant embodiment of the method of the invention;

- figure 15 represents a schematic view, similar to the view of fig. 13 suitable for making a paper product of the invention according to a further variant of the method of the invention.

DESCRIPTION OF THE PREFERRED MANUFACTURING FORMS

With reference to figures 1 and 2, a portion of a layer 10 is represented, which can alone constitute a paper product according to the invention, or be part of it as one of the layers that compose it.

The layer 10, originally smooth, or substantially smooth except for the roughness or creping typical of the type of paper from which it is obtained, is worked by embossing to obtain conical protuberances, 11, on the upper face, 12, and further protuberances, 13 still conical in shape on the lower face 14, the protuberances 11 and 13 being arranged to form relief and depression motifs on the faces of the layer 10.

At the top of the protuberances 11 and 13 there are respective openings, 15 and 16, of circular shape in this embodiment.

A simple method of manufacturing a layer 10 provides, as shown in Fig. 13, for the passage of the tape, N, of a paper layer through a pair of cylinders, 40, for example made of steel, provided on the cylindrical surface with sharp protuberances, 41, of conical shape and suitably phased together so that the sharp protuberances of one cylinder fall into the empty spaces between the sharp protuberances of the other cylinder.

In fig. 3 a variant embodiment of the invention is shown in which a layer, 10a, is provided with protuberances 11a, 13a, arranged similarly to those of fig. 1 but of a pyramidal shape with a rectangular base. Also in this case the protuberances 11a and 13a are provided with respective end openings 15a and 16a.

The paper layers of figs. 1-3 can be obtained from any type of mixture for making paper for hygienic-sanitary use, the so-called tissue-type paper. In particular, they can be obtained from pure cellulose or from mixtures containing cellulose and waste paper pulp in any proportion.

In the non-limiting example shown in the drawings, it is envisaged, on a layer of tissue paper with a weight of about 20 g / m <2> and a thickness of 0.09 mm, to create an embossing from which a density of protuberances 11 is obtained and 13, or 11a and 13a, approximately equal to 110 protuberances per cm <2>. The conical protuberances 11 and 13 have a center distance of about 0.95 mm with a base diameter of 0.35 mm, a height of 0.3 mm and a diameter of the openings 15 and 16 of 0.08 mm.

A paper layer as described above, provided in particular with openings 15 and 16 located at the top of protuberances obtained on the layer itself by embossing, has a greater water absorption capacity and a lower absorption time than a similar embossed layer in which no there are openings or fractures at the top of the bumps. In fact, following the realization of the openings, at the edge of the openings themselves, the ends of stumps of cellulose fibers are found through which the water is absorbed by rising them by capillarity. The fact that the exposed fiber stumps are located at the top of the protuberances facilitates the absorption of water even more, mainly by capillarity.

In addition, any protuberance with openings or fractures at the ends constitutes a sort of funnel that favors the flow of water in one direction but hinders it in the opposite direction. In particular, in products composed of several layers in which there are opposite openings and oriented towards the inside, the flow of water can easily take place towards the inside of the layers but it is difficult towards the outside, causing a sort of entrapment of the water between said veils.

As can be easily understood, the inventive concept of the present invention lends itself to being applied with innumerable variations dictated by particular production and commercial needs, and according to the specific characteristics that the final paper product must possess.

The openings at the top of the protuberances can take on any shape and size, for example they could be elongated longitudinally or transversely, or they could be simple cracks in the surface of the paper layer, at the top of the protuberances.

The protuberances 11 and 13 themselves can have the most disparate shapes and sizes in addition to the conical or pyramidal ones represented in Figures 1 and 3. Furthermore, the top openings could be provided on not all the protuberances and the perforated protuberances could be alternated with protuberances not perforated, possibly having different shapes and sizes. For example, the density of the protuberances perforated at the top could also be much lower than that described by about 110 protuberances per cm <2> up to, for example, a limit of a few units per cm <2,> this depending, among other things, on the chemical composition of the mixture, the weight and the absorption capacity of liquids of the product to be obtained.

The layer 10 provided with perforated protuberances at the top could be coupled according to known techniques to other layers, provided or not provided with perforated protuberances, to form a multi-layered paper product.

In particular, figures from 4 to 12 show construction variants of multi-layer paper products according to the invention.

In fig. 4 a paper product is shown in which a paper layer, 10b, is provided with protuberances, 11b, at the top of which there are openings, 15b, in which all the protuberances are obtained on the same face, 12b, and is coupled to a paper layer, 20, smooth.

In figure 5 a layer 10, according to the first embodiment described, is coupled with two smooth layers 20, one on one face, the other on the opposite face.

Figures 6 and 7 offer a particularly advantageous embodiment variant consisting of a paper product in three layers. Centrally there is a layer 10 with protuberances perforated at the top on both faces, similarly to what occurs in the first embodiment described. The central layer 10 is between two further layers, 10c, according to the invention. Each layer 10c comprises a first series of protuberances, 11c, having a perforated top and protruding towards the central layer 10, and a second series of protuberances, 18, not perforated, of larger dimensions and also protruding towards the central layer 10.

The layers 10c are coupled to each other tip to tip and the layer 10 remains between them. With this type of coupling, there are gaps in the thickness of the paper product, 19 which can fill with water or other liquid which must be absorbed by the paper product. The funnel shape of the perforated protuberances 11c facilitates the entry of the liquid and hinders its escape, thus helping to further increase the liquid absorption capacity of the product.

Certainly further solutions of multi-layer paper products can be advantageously provided and realized by coupling according to known techniques paper layers according to the invention and smooth or embossed layers with known technique and with known technique coupling methods such as the so-called "nested" coupling in in which the tips of one layer are phased with the void defined by the tips of the other layer, or the “random” coupling in which the layers couple in a random way, both glued and bonded by pressure or other known techniques.

Figure 8 shows a paper product comprising two identical layers, similar to layer 10c, i.e. provided with protuberances perforated at the ends all in one direction and provided with further embossing with tip-to-tip coupling of the two layers, while in figure 9 the same two 10c layers are nested coupled.

In fig. 10 shows a paper product comprising two layers of the type 10c, coupled "nested" between which a layer of the type 10 is included, with perforated protuberances on both faces. Obviously the two layers 10c could also be coupled "randomly" and between them could be comprised several layers of the type 10, 10b or even smooth.

Fig. 11 shows a paper product comprising two pairs of layers of the type 10c coupled "nested" to each other and the two pairs coupled to each other tip to tip.

Finally, fig.12 shows a paper product comprising a pair consisting of a layer 10c and a layer 10 further coupled tip-toe with another identical pair.

Even the method of making paper products according to the invention can certainly undergo changes with respect to what is described.

For example, fig. 14 shows a detail of a processing step in which a paper layer N is passed between a cylinder 40 provided with sharp protuberances 41, and a cylinder 50 provided with partially flattened protuberances, 51, coupled and phased in in such a way that the sharp protuberances of the cylinder 40 fall into the voids between the blunt protuberances of the cylinder 50. At the output a paper layer 10d is obtained having on one face protuberances perforated at the top and on the other face unperforated protuberances.

Otherwise, figure 15 shows a pair of cylinders, 40, 60, for example made of steel, in which the cylinder 40 is provided on the cylindrical surface with sharp protuberances, 41, of conical shape, while the cylinder 60 is coated with a layer of resilient material, 61, such as rubber or the like. The output layer 10b will be provided with conical protuberances like the protuberances of the scoring cylinder and perforated at the top on one face only.

The cylinders 40 can have sharp protuberances of any shape and size according to the type of protuberances to be obtained in the paper layer.

Certainly, in addition to the foregoing, many other paper products can be made in application of the inventive concept of the present invention and many further variations can be made to the method of manufacturing them, remaining within the scope of implementation of the inventive idea described above and in the 'scope of protection defined by the following claims.

In fact, the above description of specific embodiments is useful to illustrate the basic concept of the invention, so that experts in the field can implement it by modifying and adapting the aforementioned embodiments to the various applications; such adaptations and modifications will therefore be considered as equivalent to the exemplified embodiments. It is understood that the expressions or numbering used have a purely descriptive purpose and to aid in the understanding of the inventive concept and therefore not limitative.

Claims (10)

CLAIMS 1. Paper product with a high liquid absorption capacity composed of one or more layers and comprising at least one paper layer with a grammage between 10 and 100 gr / m <2> provided on at least one face with relief motifs consisting at least in part in a first series of discrete protuberances distributed in said pattern, characterized in that at least a part of the protuberances of said first series of protuberances has cracks located at the top. 2. Paper product according to claim 1 characterized in that said first series of protuberances has a density greater than 5 protuberances per cm2 and at least 40% of said protuberances have cracks located at the top. 3. Paper product according to claim 1 or 2 characterized in that said protuberances have a larger base area than the top area. 4. Paper product according to one of the preceding claims characterized in that said breaks located at the top of said protuberances consist at least in part of openings with an area lower than the area of the base of said protuberances. 5. Paper product according to one of the preceding claims characterized in that said protuberances are located on only one face of said layer. 6. Paper product according to one of the preceding claims characterized in that said layer comprises at least a second series of discrete protuberances having a height and base area greater than the height and base area of the protuberances of said first series of protuberances, the protuberances of said first series of protuberances being located in the areas of separation between the protuberances of said second series of protuberances and / or on the surface of said protuberances of said second series of protuberances. 7. Paper product according to the preceding claim, characterized in that said protuberances of said first series extend in the opposite direction with respect to the protuberances of said second series. 8. Method for processing a paper product in a veil suitable for making a paper product with a high capacity for absorbing liquids according to one of the preceding claims, characterized by the fact of comprising at least one deformation step of said paper product in which at least one layer of paper of said paper product is engraved by means of sharp protuberances suitable to form in said layer said protuberances provided with breaks and / or openings at the top. 9. Method according to the preceding claim characterized in that the step of engraving said paper product takes place by feeding said at least one paper layer between two cylinders in which at least one of said cylinders is provided with sharp protuberances. 10. Method according to the preceding claim characterized in that both said cylinders are provided with sharp protuberances.