TISU ENGRAVED PAPER THAT HAS SINGLE SURFACE FIBERS AND METHOD FOR ITS MANUFACTUREFIELD OF THE INVENTIONThe present invention relates to tissue paper and tissue products and specifically tissues, paper towels for kitchen, toilet paper and disposable handkerchiefs. More specifically, the invention relates to a tissue paper product with a smooth and uniform surface of high strength and volume that provides the user with greater functionality and comfort during use. The present invention also relates to the process used to manufacture tissue paper and tissue products, and in particular handkerchiefs, paper towels for kitchen, toilet paper and disposable tissues with the aforementioned characteristics and including in the process the steps of etching and brushing the surface of the tissue paper.
BACKGROUND OF THE INVENTIONTissue papers sometimes referred to as wefts or canvases of paper, tissue, tissue paper layers, paper sheets or tissue paper webs and products made with them such as disposable tissues, paper towels for kitchen or toilet paper are widely used by the current society and well known in the art. In general, the process of making tissue paper comprises the layering of the cellulose fibers moistened on a filter, the addition of various additives or other ingredients and their subsequent drying. To incorporate the desired properties into the tissue paper, other steps of the process are carried out before or after the aforementioned processing steps. The objective of the transformation steps is to obtain a finished product from the tissue paper. Tissue paper products can be made using multiple layers of tissue paper, also called sheets or a single layer of tissue paper (single-sheet products). These sheets can be combined and held together in different ways to form the finished product, for example, by engraving and / or gluing the multi-leaf structure. In the present, the finished products are mentioned as tissue paper products. Also, for a long time it has been recognized that the important physical attributes of these tissue papers are their strength and thickness / bulk, their smoothness and uniformity and their absorbency. The research and development activities have been directed to the improvement of these attributes without affecting too much the other attributes and also to the simultaneous improvement of two or three attributes. The softness and uniformity refer to the tactile sensation perceived by the consumer when he takes a particular product, rubs it against the skin or wrinkles it with his hands. The tactile sensation is a combination of several physical properties. It can be determined suitably by the target parameter of physiological surface smoothness (PSS) as described for example in U.S. Pat. no. 5,855,738. For the tactile sensation perceived by the consumer, the thickness / caliber of a paper product known as bulking is also important. Resistance is the ability of the product to maintain physical integrity and resist tearing, breaking and fraying during conventional use.
Absorbency is the measure of the ability of a tissue paper or product to absorb quantities of liquid, especially aqueous solutions or dispersions. The general absorbency perceived by the consumer is usually considered as a combination of the total amount of a liquid that the mass of a tissue paper or tissue product will absorb until it is saturated and also the speed of such absorption. Thick but soft disposable paper products are known, for example, in the form of disposable tissues. For example, Tempo ™, marketed by The Procter & Gamble Company, is a multi-sheet paper product, thick and soft and with an approximate size of 0.3 mm. A high caliber transmits to the consumer the sensation of great resistance, in a wet and dry state. In particular, high wet strength, also known as wet break resistance, prevents tearing or breaking which in the case of a disposable handkerchief involves contamination of the user's hand with mucus or other organic fluids. A common method for improving the uniformity of the tissue paper surface is to calender the material. For example, U.S. Pat. no. 5'855'738 filed by Weisman et al. describes a calendering step that facilitates the manufacture of a uniform and high density tissue paper. This step of the manufacturing process flattens the surface of the tissue paper, orienting and reattaching the fibers of the paper to the surface of the weft. However, the calendering considerably reduces the size of the paper web, making it difficult to obtain the desired volume in the final product. Methods for producing high bulk tissue papers are described, for example, in U.S. Pat. no. 5'702'571 and in European patent no. 0 696 334 B1, both patents filed by Kamps et al. They state that the bulkiness of the tissue paper increases when the tissue paper is stamped between a grip line formed by a male engraved roller and a female engraved roller. Another example included in the patent application EP01103798.3 presented by K. Hilbig, M. Liplijn and H. Reinheimer on February 16, 2001 consists of the production of a three-dimensional structure on the surface of the paper (by means of microgravure, also called stretch deformation, before the calendering step). This is the method to produce a relatively uniform and bulky end product. However, the aforementioned tissue paper is subjected to a calendering step and exhibits a markedly reduced thickness compared to microgravure tissue paper. Another method known in the art for producing uniform-surface tissue paper involves applying a brushing step to said paper. The brushing of tissue paper is known in the art and has been specifically described in U.S. Pat. no. 3'592732 filed by Wand et al. in which brushing is described with a rotating brush and an engraved or serrated roller as the opposite surface. U.S. Pat. no. 5'180'471 of Sauer et al. describes a multi-sheet tissue paper (and the related method) with its interior surfaces brushed. It is believed that the brushing of the paper surface acts on the paper fibers (cellulose fibers) mentioned herein, as extension fibers, by stripping one end of them close to the surface of the paper so that they rise above the surface of the paper. the surface of the paper web and the resulting surface is uniform to the touch. However, one of the disadvantages is that brushing could damage the strength of the paper web as it modifies the structure of the network of fibers that form it (as mentioned in U.S. Patent No. 3). '592'732 cited above) and reduces the bond between the fibers that make up the surface of the tissue paper. The prior art explains that all the above methods have disadvantages that affect one or more of the main characteristics of the tissue paper when trying to improve some other. In view of the prior art and the previously established, the need to have tissue papers that combine apparently incompatible characteristics persists: • High surface uniformity, • high resistance, • thickness / high bulk. The same requirements are valid for finished products, often made from a combination of multiple sheets of tissue paper. The present invention responds to this need.
BRIEF DESCRIPTION OF THE INVENTIONThe present invention relates to tissue papers comprising cellulose fibers. The tissue papers have a first and a second surface and an etching pattern that forms high regions surrounded by depressed regions on the first surface. These regions coincide with the respective opposite regions of the second surface of the tissue paper. The first surface contains extension fibers that include a first end not attached to | tissue paper and a second end attached to the paper. The unbonded ends result from the brushing of the first surface so that there are more fibers of extension in the elevated regions than in the depressed regions. The present invention also relates to paper products such as handkerchiefs, paper towels, disposable handkerchiefs and hygienic papers made with one or more of the aforementioned tissue papers. The present invention also relates to the process for making a tissue paper in accordance with the foregoing. The process comprises the steps of: - Recording the tissue paper passing it between two rollers that form a grip line; and - brushing at least one of the surfaces of the tissue paper. The process is preferably characterized in that the brushing step is carried out after the engraving step. The relevant parts of all the cited documents are incorporated herein by their mere mention; the mention of any document should not be construed as an admission that the patentability of this invention is excluded.
BRIEF DESCRIPTION OF THE FIGURESFigure 1 represents a disposable tissue composed of 3 tissue papers (also called sheets or layers) whose surface is practically non-flat / non-uniform. , Figure 2 is an enlarged portion of Figure 1, in which the 3 tissue papers are observed. Figure 3 shows the process for making a tissue paper like that of theFigure 1. Figure 4 shows an enlarged portion of the tissue paper at location I of Figure 3. Figure 5 shows an enlarged portion of the tissue paper at location II of Figure 3.
DETAILED DESCRIPTION OF THE INVENTIONThe present invention provides a tissue paper of a high degree of uniformity and surface smoothness, high strength and great bulk. These characteristics that apparently compete with each other were combined according to the concept of the present invention. Without being limited by theory, the underlying concept of the present invention can specifically be described as the production of a non-uniform tissue paper surface with the desired characteristics in individual regions: • Uniformity / softness in the most prominent regions (elevated regions) ) due to the presence of loose ends of the paper fiber which helps to provide the benefits of the tissue paper perceived to the touch. • · Resistance in the interior regions (depressed regions) by means of the supply of a fiber network practically unmodified. • Voluminosity produced by the presence of elevated and depressed regions and maintained during the next process that consists of transforming the tissue paper according to the nature of these steps of the process and preferably of its specific sequence. This can be done when the selected process steps are applied to the tissue paper. These steps are optimized to achieve the desired final result and provide a synergistic effect. Preferably, they are applied in a specific order. In particular, the present invention relates to steps known in the art as "transformation steps" in which a tissue paper produced by means of a suitable "papermaking process" is provided.
In the practice of the present invention the following steps of the process are applied: A tissue paper is supplied. The tissue paper is treated with one or several processes to modify one or more surfaces and / or the inner surface in order to incorporate the desired characteristics into said paper; and / or is combined with one or more tissue papers to form a product or an article capable of being transformed into a product; and / or other processes are applied in the article or product in order to modify its interior surface or structure. The tissue paper according to the present invention will now be explained with reference to the drawings and steps for its preparation.
Engraving (engraving or microengraving by stretching or deformation by stretching) Although any type of engraving known in the art may be used in the present invention, a preferred engraving step is the so-called micro-engraving step or stretch engraving, also called stretch-forming as described in the European patent application EP01103798.3 filed by K. Hilbig, M. Liplijn and H. Reinheimer on February 16, 2001, in which a very fine pattern is recorded by means of low pressure. The engraving can be done on a tissue paper as indicated with the reference numeral (13) in Figures 3, 4 or 5 or with the reference numerals (2), (3) and (4) in Figures 1 and 2 Alternatively, it may be performed on a multi-sheet article as indicated by the reference numeral (1) in Figure 1. In order to simplify, the reference numeral (13) of Figure 3 is described below as a tissue paper (ie, a single-sheet entity), but the person skilled in the art will understand that it can be replaced with a multi-sheet article as indicated by the reference numeral (1) in Figure 1 without deviating of the present invention. As shown in Figure 3, the engraving of a tissue paper as indicated with the reference numerals (2), (3) and (4) in Figures 1 and 2 or the engraving of a multi-sheet article as the indicated with the reference numeral (1) in Figure 1, it is usually obtained by passing the tissue paper or the multi-sheet article (reference numeral (13) of Figure 3) through the nip ( 8) formed between two stamping rollers (9) and (10); at least one stamping roll (9) comprises stamping elements (12). A stamping roll usually comprises a uniform surface. The embossing elements (12) are projections projecting from their surface and having a specific height measured in a radial direction from the axis of the embossing roller above the smooth roller surface to the highest point of the projection. The embossing elements also have a width in a direction parallel to the axis of the roller and a length in a radial direction. As used herein, the terms "width" and "length" may refer to the diameter of a round stamping element. It is not essential that this diameter be constant from the lower part of the embossing element to its upper part. Preferably, the largest width of a stamping element is located on that uniform surface. The embossing elements (12) may be of any shape, for example, pyramidal or half-sphere, and their cross-section may be circular, oval or square. They can form a continuous pattern, but are preferably different from each other since the uniform surface of the roller forms a continuous plane. In one embodiment of the present invention, the embossing elements (12) are arranged on at least one embossing roller with a very fine pattern comprising at least 30 embossing elements, preferably at least 50, more preferably at least 60 , more preferably at least 70 and most preferably at least 80 embossing elements per square centimeter of roll surface area. The stamping elements are not high; its height is preferably up to 1 mm, more preferably up to 0.8 mm, with a preference up to 0.6 mm, even more preferably up to 0.5 mm or 0.4 mm and most preferably up to 0.3 mm. When the stretch engraving is performed, the radius of the engraved areas to the non-engraved areas is preferably 5% to 95%, more preferably between 20% and 80% and most preferably between 40% and 60%, is say, preferably between 40% and 60% of the total surface area of the tissue paper is etched. Any type and mode of operation of the known embossing roller is within the scope of the present invention. Specifically, two stamping rolls of hard metal, for example steel, can be used, wherein a first roller comprises projected stamping elements mentioned as the male roller and a second roller comprising matching cavities mentioned as the female roller. The cavities can be mirror images of the projected embossing elements or they can be of a size barely smaller than that of the exact mirror images, for example, due to a small difference in size or shape (e.g., slope) of these cavities in the female roller. The "stamping with a double male roller" can also be used in which two rollers with matching projections are used. Alternatively, a first embossing roll comprising a contact surface with the weft may be used.; the surface is a hard metal and comprises projected embossing elements and a second roller comprising a contact surface with the weft; the surface comprises a softer material, for example rubber, preferably a material of Shore A hardness 40-70 with cavities formed when contact with the projected embossing elements occurs. The advantages provided by an engraving grip line formed by combining a hard metal roller with a rubber roller are several; for example, the production and operation are easier and cheaper, since the adjustment of the rollers is much less critical than when using two rollers, female and male, of hard metal. The size of the grip line formed between the two stamping rollers will be adapted, for example, depending on the tissue paper to be processed and the engraving pattern used. Also depending on these considerations, some pressure can be used to join the two stamping rollers or the connection can be made without pressure. If two hard metal rollers, a male roller and a female roller are used in the process, they should work so that there is a space of 60% to 140%, preferably between 80% and 120% of the size of the tissue paper. engraving between the projected patterning elements of the male roller and the lower part of the cavities of the female roller. When using a hard metal roller and a rubber roller, the pressure exerted for the rollers to be joined should be from 10 N / square centimeter to 1000 N / square centimeter, preferably between 20 N / square centimeter and 200 N / square centimeter and most preferably between 50 N / square centimeter and 100 N / square centimeter. Known modes of operation are suitable for the present invention; Preferably, the embossing rollers do not heat and do not operate at the same speed, but in alternative operating modes, at least one roller can be heated and the rollers can operate at different speeds. The engraving with a fine pattern described above is useful for increasing the caliber, in other words, the volume of the tissue paper. Therefore, in a preferred embodiment of the present invention, a single tissue paper is passed through the etching line (Figure 3, (8)). In other operating modes multiple sheets of tissue paper may be passed simultaneously through said line (Figure 3, (8)). These engravings will initially be concordant or will be nested between the tissue papers.
Brushing step: In accordance with one aspect of the present invention, the brushing of the tissue papers (Figure 3, reference (13)) is preferably carried out after the etching step, but can also be considered as an independent step as long as it produces the desired result described. In the present document, the terms brush and brush are used as an example, without limiting the scope of this invention. In accordance with the present invention, the brush is any implement, equipment or means capable of suitably modifying the surface and structure of the tissue paper (i.e., raising the ends of the fiber without completely separating). Conventionally, these means include any type of abrasive surface such as those provided by the fibers of a brush or by sandpaper. Useful structures suitable as abrasives can be made from natural or artificial materials such as foam, metal or polymers. To generate the desired abrasion preferably a relative movement between the surface of the tissue paper and the abrasion means is required. In the present invention, the chemical, optical or physical processes that produce the described modification of the surface and / or structure of the tissue paper are considered as an alternative. Preferably, the surface and structure of the tissue paper are modified with a rotary implement in abrasive contact with the surface of the tissue paper and most preferably a brushing cylinder comprising brushing fibers throughout its circumference. The fibers can be polymeric, but preferably they are natural like the hair or the skin of animals to achieve a greater electrostatic performance. The brushing step can be carried out on one side of the tissue paper or both, depending on the desired benefits, by means of a combination of one, two or more brushes. One or more brushes (or brushing cylinders) can be applied to each side of the tissue paper. However, for the purpose of simplification, in the embodiment of the invention described below a brushing cylinder (identified in Figure 3 with the reference numeral 11) is used on one side of the tissue paper. In practice other alternative configurations may be used. For example, the use of 2 or more brushes on the same face of the tissue paper that brush the first and second surface simultaneously or consecutively is considered. In a preferred embodiment of the present invention, 5 pairs of brushes are used that provide 5 brushing operations on each side of the paper web. The main result of the brushing step consists of the modification of the fibers lying on the outermost part of the surface of the tissue paper. The tissue paper fibers are generally joined together by hydrogen bonds during the processes of making, drying or calendering the tissue paper at multiple points at which the fibers intersect. The inventor considers that the supply energy of the paper fibers in the brushing step is sufficient to break some of the hydrogen bonds that bind the fibers and ensure the cohesion of the paper structure. This energy is supplied by means of the tearing or frictional force of the individual fibers when they collide with the fibers. Without being limited by theory, the inventors believe that the energy must be sufficient to break some joints between the fibers, but low enough so as not to break all the joints since this would produce a complete displacement of the fibers from the surface of the paper. tissue (also known as blanching) and not to break the structure of the fiber itself. When applying the brushing step of the present invention, the extension fibers (7) are generated as shown in Figures 2 and 5, that is, fibers in which one end is still attached to other fibers and the other end is free.; these fibers can extend above the surface of the tissue paper. The extension fibers (7) are essential to provide the tissue paper with the characteristics of uniformity and softness to the touch. The object of the process according to the present invention preferably consists of loosening or releasing only one end of the fibers by breaking their bonds with the other fibers at one end. However, it is observed that the brushing step also inevitably produces the total detachment of some complete fibers or the fraying of fibers. These fibers or parts of fibers should be removed from the tissue paper thereby facilitating the reduction of repellency. One of the possibilities is to recycle them. The process according to the present invention can be seen schematically in Figure 3: first a tissue paper web (13) is provided, usually unwound from a tissue paper web roll. The tissue paper web (13) is guided to an engraving station where it passes through a grip line (8) between two stamping rollers (9), (10). After the engraving, the tissue paper (13) is moved to a brushing station where at least one face is exposed to a planing cylinder (11). The brush cylinder can rotate so that its surface moves in the same direction or in a direction different from the displacement of the tissue paper or can simply remain static. The configuration parameters of the equipment, especially the brushing cylinder, such as the speed of rotation, the distance of the brush to the tissue paper web, the measurement of the wrapping of the tissue paper web around the brush and the design of the brush as the origin of the fibers, their length, the moment of flexion of the fibers, the density and diameter of the fibers and the treatment or coating of the fibers, are optimized to produce the best results in the quality of the tissue paper after brushing (analyzed according to the resistance, uniformity, softness and volume of the tissue paper), the stability of the process and the useful life of the equipment. The brushing step can be performed only with the inherent force of the moving tissue web acting on the brush, ie, without using a roller or opposing surface to apply pressure and / or guide the tissue paper over the brush. As shown in Figure 3, only the tension of the tissue paper web and in a much smaller proportion, the tissue paper itself exerts pressure on the rotary brush (11). Alternatively, an opposing surface (more preferably in the form of an opposite roller rotating at a surface velocity close to the surface velocity of the weft) positioned so that a portion of the weft is simultaneously in contact with the brush is used. and with the opposite surface. Even more preferably, the opposite roller and the plotting of the screen are positioned so that a convex surface of the screen is exposed to the action of the brush. Without being limited by theory, it is believed that this configuration "opens" the microstructure of the weft and consequently improves the action of the brush on the fibers of the weave of the tissue paper. This configuration is obtained for example by the partial wrapping of the weft around the opposite roller (therefore, the surface of the weft that is not in contact with the opposite roller has a convex surface in contact with the brush). When more than one planing cylinder is used in the process, some of the brushes may be positioned so that they brush both sides of the paper web simultaneously or consecutively. In a preferred practice of the invention, the brush rotates in the direction of movement of the weft in the transformation line. However, the opposite direction is also considered. Together with the design of the brush, its speed of rotation is a crucial parameter for the efficiency of the brushing step that influences the wear of the equipment and the final results of the process step. Preferably, the speed of the brushing cylinder relative to the surface of the tissue paper web is greater than 1000 m / min (linear velocity of the point of contact with the paper web), more preferably greater than 1500 m / min, with a even greater preference more than 2000 m / min and most preferably more than 3000 m / min. The relative surface velocity of the brush can also be calculated in relation to the surface velocity of the weft: it has been observed that the present invention produces the best results when the brush surface velocity is between 1.5 and 20 times greater than the surface velocity of the weft , more preferably between 2 and 5 times and most preferably between 5 and 10 times. The origin and design of the brush (Figure 3, reference (11)) used in the present invention can be varied, including synthetic, metallic or natural bristles of different dimension and density. In a preferred practice of the invention, brushes made with horse hair have been used, such as those distributed by Mink GmbH (Goeppingen, Germany) under the reference ZZB12528-K2509. These brushes are conventionally used for the treatment of fabrics. Preferably, the brush is practically circular and works by rotation about an axis. However, the inventors consider as part of the present invention, the use of other types of brushes (for example, fixed brushes or brushes operating by translation of the surface of the brush or the abrasive surface on the surface of the tissue paper) always and when the action of the brush leads to the modification described for the surface and structure of the tissue paper. In a preferred practical embodiment of the invention, the engraved weft of the tissue paper is wrapped around two brushing rollers without being fixed on a guide roller. Each roller brushes a surface of the tissue paper. The displacement distance of the tissue paper on the surface of the brush (i.e., the tissue wrap around the brush, or in other words, the length of contact between the brush and the tissue paper) can vary widely. It has been found that the useful length is up to 20 cm, preferably up to 5 cm and most preferably up to 1 cm, although a longer length interval is considered. In the case of tissue paper made in the papermaking process as an inhomogeneous mixture of short and long fibers wherein one side of the paper includes fibers shorter than those on the other side, the present invention considers a preferred orientation of the paper. the paper web in the brush. Preferably, the tissue paper or the brush is oriented so that the short fibers of the tissue paper come into contact with the brush. Without being limited by the theory, it is easy to imagine that the union of the short fibers with each other is smaller. Accordingly, it is easier to release a greater number of fiber ends on the short fiber face than on the long fiber face of a tissue paper. It has been observed that the step of brushing a tissue paper tends to increase its caliber and increases have been measured from 1 to 25%, on average up to about 5%. Fundamentally, the high bulk resulting from this increase in caliper is in addition to the increase in caliper produced by the engraving step, preferably the step of deformation by stretching. In general, this deformation produces an approximate increase of 50% to 200% of the size of the tissue paper, in accordance with the aforementioned European patent application EP01 03798.3. One of the advantages of the process of the present invention, compared with the process described in the European patent application EP01103798.3 mentioned above, is that the conventional calendering step subsequent to the stretch deformation step can be eliminated. This conventional calendering usually results in a reduction in the size of the tissue paper which, when deformed by stretching, produced an increase in the total size (after the two steps: stretch deformation and uniform calendering) from 10% to 100%. If the calendering is removed after the engraving, but a brush is used, an exceptionally high final size can be obtained in the treated tissue paper web, between 51% and 225% in the examples provided above. In a preferred embodiment of the invention shown in Figure 3, previously an engraving step was applied to the tissue paper (13) of Figures 3, 4 and 5, most preferably micro-engraving (or step of engraving or deformation by stretching). described under the heading "Engraving" of this document. In that case, the tissue paper (13) enters the brushing step as an essentially non-planar surface, that is, it has elevated regions (6) and depressed regions (5) related to each other, as a result of the engraving step. The brushing effect on this previously deformed tissue paper has been unexpected and constitutes one of the main discoveries of the present invention. It has been identified that the brushing step preferably acts in the elevated regions (6) while the depressed regions (5) remain practically unaltered. Accordingly, more extension fibers (7) are generated in the high regions (6) than in the depressed regions (5). In this way a network of depressed regions is produced practically without alteration. This network practically maintains the strength and traction characteristics of untreated tissue paper. This generates the expected results: produce a tissue paper with a high level of softness and uniformity (especially provided by the extension fibers of the elevated regions), a high resistance (specifically supplied by the network of depressed regions not altered) and bulkiness ( supplied by the presence of high and depressed regions).
Other steps of the process The method for preparing a paper product in accordance with the present invention may comprise several additional optional steps. The following are some examples that do not limit the scope, function or nature of the invention: By using a suitable method that includes but is not limited to printing or spray printing, a lotion is applied to one or more surfaces of the tissue paper or paper product or on a portion of these surfaces. The superimposed sheets of the tissue paper may be joined to provide a multi-sheet paper product, preferably by etching. As used herein, "fixing etch" refers to the engraving in which all sheets of a multi-sheet product in accordance with the present invention are recorded in one step of the process. "Fixation etching" has been described by H. Reinheimer, K. Hilbig and W. Schmitt in WO-95/27429. Preferably, it does not influence the uniformity of a calendered tissue paper or it has very little influence. Therefore, the paper product preferably has a non-engraved surface that occupies a large part of the surface area of the tissue paper, preferably on the first and second surfaces. As used herein, this means that the tissue paper has one or more regions not etched by fixation and, optionally, one or more regions recorded in this way; the non-engraved region is at least 50%, preferably at least 80%, and in some preferred embodiments, 99% of the surface area of the tissue paper. Generally, the regions recorded by fixation are close to the edge of the tissue paper (for example, along two or four edges). This type of engraving can also be used as an ornament (for example, to create a pattern or place the letters of a logo or trade name). Preferably, it is made by engraving with two male steel rollers having 10 to 40 stamping elements per square centimeter with a height of 0.01 mm to 1 mm, preferably between 0.05 mm and 0.2 mm. The percentage of areas recorded by fixation relative to areas not recorded or recorded with a fine pattern in the total surface area of a tissue paper product preferably ranges between 0.01% and 5%. This type of engraving requires the substantial densification of the tissue paper products necessary to obtain the fixation. Therefore, the grip line or the space between a stamping element and its counterpart, for example, two pins when using two male rollers, is smaller than the caliper of the tissue paper to be stamped, usually between 5% and 50%, preferably between 10% and 20% of the size that requires an engraving pressure of 10,000 to 50,000 N / square centimeter. The method of the present invention can also include a step that consists in sizing the tissue paper web or the paper product until adequate measures are obtained. In the paper products according to the present invention, distinctive aesthetic or functional marks may be incorporated. Distinctive marks can be applied on one or both surfaces of paper products. They can be applied to the entire paper product or to a part of it with a continuous or discontinuous pattern. Distinctive markings can be applied to tissue paper products by any method well known in the art, such as spray printing, extrusion and, preferably, printing.
Examples:Tissue paper: A portion of a tissue paper web is cut according to the present invention; this part has a non-uniform surface which can be obtained for example by a micro-engraving step. It usually has between 30 and 100 depressed regions per cm2 typically with a depth of up to 260 μ? T? and a diameter of more than 20 μ ??. The thickness of tissue paper depends largely on the manufacturing process and is usually 100 μ? per original sheet of tissue paper and 150 μp? at 200 μp? when it is engraved or deformed by stretching. This produces an approximate thickness of 400 μG? at 500 μ ?? when 3 sheets are combined (after engraving) to form a finished product. The dimensions of the tissue paper are not important, since this practically depends only on the configuration parameters of the cutting equipment of a manufacturing machine. As shown in Figure 5, the raised regions (6) of the tissue paper (13) have extension fibers (7) visible with a microscope or magnifying lens. The ends of the fibers are not bonded to the other fibers and can therefore adhere away from the surface of the tissue paper. Apparently, the extension fibers provide the specific characteristics according to the present invention that generate the advantages described above, specifically softness, uniformity and bulkiness of the tissue paper. The strength characteristics of the tissue paper are practically unchanged since the depressed regions contain less extension fibers than the elevated regions. In general, the present invention encompasses any tissue paper (13) having more extension fibers (7) in the raised regions (6) than in the depressed regions (5). However, in a preferred embodiment of the present invention the high region contains at least 20% more extension fibers than the depressed region, more preferably at least 50% and most preferably at least 80%. The counting of the extension fibers can be done with an augmentation device (for example, a 10-fold magnification lens) by calculating the density or quantity of extension fibers or counting the fibers of the high regions and the regions in numerical form. depressedDisposable tissues: Specifically, Tempo disposable tissues (registered trademark) are usually made up of 3 to 4 sheets of tissue paper. The approximate base weight of the handkerchief is 50 to 80 g / m2 (that is, approximately 18 g / m2 per sheet) and its size is 400μ? to T ?? μ ?? (approximately 140μ per sheet). The sheets are joined by a particular engraving in accordance with W095 / 27429 and possibly with glue, which keeps the sheets together and allows to design a specific pattern on the surface of the disposable tissue. In a particular example, only the 2 outer surfaces of the tissues (after combining the sheets) have unbonded fiber ends in the raised regions of the tissue paper in accordance with the present invention. The other surfaces of the tissue paper (outer tissue surfaces facing inward and surfaces of the inner tissue paper) have elevated regions and depressed regions that provide bulk and caliber, but have an equivalent amount of unbound fibers in the high and depressed regions . While particular embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. It has been intended, therefore, to cover all the changes and modifications within the scope of the invention in the appended claims.
Absorbent article: In another example, the tissue paper according to the present invention is used for an absorbent article. "Absorbent article" refers to devices that absorb and contain liquids and more specifically refers to devices that are placed against or in proximity to the user's body to absorb and contain liquid exudates discharged from the body. Absorbent articles include but are not limited to diapers, incontinence briefs in adults, trainers, diaper liners and liners, sanitary napkins and the like. The absorbent articles typically comprise an absorbent core, an upper canvas and a lower canvas. The absorbent core is usually arranged between the upper canvas and the lower canvas. The absorbent core may comprise any absorbent material that is generally compressible, conformable, non-irritating to the wearer's skin and capable of absorbing and retaining liquids, such as, for example, urine and other certain body exudates. The absorbent core can comprise a wide range of liquid absorbent materials that are commonly used in disposable diapers and other absorbent articles, such as crushed wood pulp, which is generally referred to as air felt. Examples of other suitable absorbent materials include creped cellulose wadding; meltblown polymers including coform; chemically stiffened, modified or crosslinked cellulosic fibers; tissue paper, including tissue paper wraps and tissue paper laminates, absorbent foams, absorbent sponges, superabsorbent polymers, absorbent gelling materials or any other known material or combination of absorbent materials. The absorbent core 28 may also include minor amounts (generally up to 10%) of non-liquid absorbent materials such as adhesives, waxes, oils and the like. The absorbent core preferably includes a pick-up system comprising an upper pick-up layer facing the user's skin and a lower pick-up layer facing the wearer's garment. In a preferred embodiment, the upper picking layer comprises a nonwoven fabric while the lower picking layer comprises a mixture of chemically stiffened, twisted and crimped fibers, high surface area fibers and thermoplastic bonding fibers. In another preferred modality, the two acquisition layers are supplied from a nonwoven fabric material, preferably hydrophilic. Alternatively, one or all of the layers of the acquisition system may be supplied from a tissue paper in accordance with the present invention. The acquisition layer preferably is in direct contact with a storage layer, which is also comprised by the absorbent core. The storage layer may be wrapped by a core wrapping material. In a preferred embodiment, the core wrapping material comprises an upper layer and a lower layer. The core wrapping material, the upper layer or the lower layer can be supplied from a nonwoven fabric material. Non-woven fabrics are permanently hydrophilic and in particular, non-woven fabrics with durable hydrophilic coatings. A highly preferred alternative material for supplying the upper layer and / or the lower layer is a tissue paper in accordance with the present invention. The upper layer and the lower layer can be provided with two or more sheets of separated material or alternatively they can be provided with a sheet of unitary material. This sheet of unitary material can be wrapped around the storage layer, for example, in a "C" fold. It has been observed that the use of tissue paper in accordance with the present invention improves the dryness of the absorbent article on the face facing the user. Without being limited by theory, it is believed that this effect is the result of a greater drainage of the uptake system by means of a core comprising the tissue paper according to the present invention, as a core wrapping material.