Embossed absorbent paper sheet

The present invention relates to the field of absorbent papers for sanitation or household-related use, and is directed to a sheet material, formed from at least one embossed ply, substantially determined for the production of toilet paper, but also of handkerchiefs, table napkins or possibly household towels.

in the industry of papers for sanitary or household-related Use is used for manufacturing this type of product a generally creped absorbent paper of low basis weight, composed of cellulose wadding or quilted fabric. One uses the extensibility of the structure, caused for example by creping, to the Sheet material to shape. This process is not the latter between a deformable, provided with reliefs roll and a counter roll, for Example with yielding shell to deform more permanent way. You get in this way elevations on one side, which depressions in accordance with the other side.

in Indeed, it was the trend of recent years, which the hygiene products concerns of cellulose wadding, this soft and gentle feeling, to make by their characteristics with respect the thickness and resistivities in particular by means of stamping were processed. This latter also allows the visual appeal to improve the product. The process of imprinting is either on paper high moisture content, that is, in the wet part of the paper machine, or on paper with low moisture content, that is in the Conversion, made. So you worked a dry leaf material, unwound from a parent roll, coming from the paper machine. The present invention relates to paper, which in the dry part is reshaped.

The widespread embossing pattern consist of a repetition of elementary protrusions low Cross-section and of simple geometrical shape on a geometrical Basis together. An example in the patent US-A-3,414,459 described which is formed on a layered sheet material from a mentioned plurality of glued-together elementary sheets, the plies are lifted. The layers were washed with a distribution frequency and a height influenced the projections, the absorbent in the production of water products, such as For example, household wipes, is adapted. The number of elements is between 5 to 30 per cm², The patent US-A-5,620,776 describes a embossed Sheet material comprising a first pattern composed of Elevations with a surface at the highest Instead of more than 1 mm²Arranged along simple lines, which cells Narrow polygonal shape. At least one Part of the cells comprises a second pattern of second protrusions is formed. In turn, the applicant, in particular for toilet paper, Pattern developed whose number of elements is larger, from 30 to 80 per cm² extending. These elements necessarily a very small elementary surface of less than 1 mm² at the highest point. You get for this latter versions an appearance that mimics that of a woven product. On Example of this was described in the patent EP-A-426 548th This fine, dense type of embossing pattern is very well suited to the sheet material an impression of thickness lend.

it nevertheless has a limited visual appeal. It should also the softness of the product obtained is not optimal, if by Gluing two such embossed Layers are joined.

The in the application FR-A-94 15196 solution shown allows the softness a two-ply sheet material with this type embossing to improve by a combined pattern is produced comprising a graphical Pattern and a base pattern. The former is linear from surveys Shape composed of a width between 0.1 and 2 mm, and the second includes small, generally truncated surveys, distributed in an amount of at least 30 per cm², It connects the layers on the pattern of linear shape and limited as the extension of the mutually bonded surfaces and the concomitant Stiffening.

The Surveys of the basic pattern must leave the main patterns stand out because they are not easy the naked Eye individually visible because of their small size necessary. however while the preparation of the graphic pattern in relief on the roll present, just as against the embossing rubber depressed as the stamping of the suppository Basic pattern. Thus, there is a competition between the two Stamping types. Since the suppositories the basic pattern formative because of their small size than those of the graphic Pattern are followed by a weaker Umrißschärfe of imprint on these latter.

If conversely attempted a better extent the reprinting of sharpness graphic pattern <?page 3?>achieve the necessary lead embossing conditions to a deterioration of the properties of the sheet material, in particular its strength, both at the edges of the pattern itself as Also on the background grid. They also lead to a deterioration the yield conditions, for example to wear of the rubber sheathing.

It should also the proportion of embossed with the pattern surface far outnumbered: he is virtually 80% of the surface. It secures the essentials associated with the embossing functional characteristics, this means the thickness and absorbency. In the production we therefore distributes the increased load that between the gravure roll and its counterpart from rubber occurs, on a large Number of elements. This also reduces the local stresses and the dangers to tear the sheet material. It also distributes the Load to almost isotropic manner to the sheet material, which the risks of producing breaking lines limits.

one white, moreover, that if reducing the density is concentrated tensions and so more the sheet material weakens.

The Invention has a sheet material made of embossed paper towel to goal a working out teres patterns than a simple grid pattern without the use of linearly arranged elevations.

The The invention is also the goal of a uniform footprint and a good Umrißschärfe the pattern ensure.

The The invention is also a sheet material made of embossed paper towel having two or several layers to target whose embossing pattern allows the flexibility better to maintain the documents after the connection.

The Invention has about addition, a sheet material made of embossed paper towel for destination that features the thickness and strength of the same order of magnitude as those a sheet material, the embossing evenly distributed is uniformly and more than 30 protrusions per cm² having.

In accordance with the invention is a sheet material made of absorbent paper, creped cellulose wadding particular, with a surface weight between including 10 and 40 g / cm²Comprising on one side first elevations with a surface at the highest point of less than 1 mm²Corresponding recesses characterized on the other side, characterized in that the first Surveys in a number of more than 30 per cm² so distributed along mutually parallel lines that they together Refinement cells, the entire surface of at least 30%, preferably at least 50%, the surface of the Sheet material occupies the cells themselves have little or no embossed are.

A Cell is a part of the surface of the sheet material, surrounded by parallel lines of the first projections, of itself 30% of the non-screened areas forms. The shape of these Cells is arbitrary, but preferably it is geometric. The Lines that define them, may intersect to form a grid, but the cells can accurately be as good unconnected.

it was surprisingly found that a Sheet material whose embossing was defined in such a way from the same characteristics of thickness and Strength benefited as a sheet of material having a same from the Elements composite imprinting which the evenly over the whole surface with a higher uniform density distributed. This is particularly interesting when a sheet material several such embossed produce documents wishes because the non-uniform distribution allows partial connection of the layers to one another. The result is from a higher Flexibility.

Also obtained cumulative Perceptual effects connected with the distribution frequency of the pattern are. The softness is due to the non- or slightly embossed surface of Cell improves whose extent still sufficient to their calendering at the time of stamping permit.

The Calendering results from the action of the rubber of the Counter roll to the sheet material when the pressure on the surface Roll between the embossing suppository exerts. The Calendering makes the sheet material smoother by its unevenness suppressed. It improves with this fact the impression of softness. This is further improved if the glazed area is large enough to touch. For this reason, it takes advantage of the solution of the invention, if the calendered surface parts at least 1 cm² account. This matches with the contact surface of the fingers with <?page 4?>the sheet material.

According to a other features are the first elevations along at least 3 lines distributed when cells are adjacent. In fact tends a smaller number to form preferential breaking lines.

According to a another feature of the lines are wavy. In this way reduces still see the risk of formation of lines lowest strength continue.

According to a another feature, the second sheet material elevations inside of the cells. It is in this case are isolated elevations. In other words, the elevations are arranged in such a way that they subcells avoiding of sufficient size, so that during the embossing the rubber, the base touch the engraved roll and so ensure the calendering of the sheet material at this point can. This second elevations are parallel advantageously in the form individual lines at the edges the cells attached. These surveys take in no event more than 15% of the surface of the Cell.

According to a another feature define the first surveys at least 5 cells per demolition, preferably 15 to 20 Also preferred define the second Surveys between themselves or between them and the first Surveys more than 100 sub-cells. An outline is the part of the sheet material, the one along a pre-punched in the transverse direction of line a role, for example, toilet paper, tear off.

According to a another feature are not adjacent to the cells. Specifically, occupied the space between the cells of a rasterized zone will. Said rasterized zone if this is preferred, of an embossing density different from that of the first protuberances.

According to a another feature is the sheet material comprises at least one layer of a multi-layer sheet material. In fact, one provided by the arrangement the surveys in cells form a kind of partial connection and obtaining a softer multilayer product.

it will hereinafter be a non-limiting embodiment of the invention described, with reference to the accompanying drawings, in which

<figref idrefs="S14">1</figref> a embossed view of a Sheet material according to the invention shows.

<figref idrefs="S15">2</figref> is a graph and the relation between the strength of the thickness of a product according to the prior art and a product according to the invention shows.

The reproduced sheet material is a sheet material made of crimped Cellulose wadding with a surface weight between including 10 and 40 g / m², The points mean elevations on one side and recesses on the opposite side. These surveys were obtained by the sheet material between an element, such as a roller, and with a rigid surface a counterpart, such as a roller with casing yielding, for example of rubber, was deformed. The rigid surface has according to the pattern desired to be obtained from cellulose wadding on the sheet material, Inappropriate Reliefs on. The shape of the embossing suppository above dulled and they have a circular, oval or polygonal Cross-section.

in <figref idrefs="S14">1</figref> is the reproduced pattern of rows of cells composed, of multiple rows of grid-like arranged first protuberances be limited. For example, the cell C is in the form of a rhombus B1, B2 and B3 defined by the triple rows of crests. Note that this Rows have a wave-like shape.

According to the invention are the first bumps mounted in such a way that the local Density of the elevations greater than 30 per cm² is. Preferably, it is greater than 6 per cm², They have a surface the highest Point of less than 1 mm², To the result to obtain the present invention, that is, a behavior with respect to strength and thickness equivalent to the one with in a uniform manner over the entire surface a density of the same order imprinted Sheet material is, the number of rows or lines at least 3 when neighboring Cells limit.

The Interior of the cell C is not marked or not containing embossed Zones of the second Erhebun&lt;?page 5?&gt;limited conditions (I) of the insulated type will. thus is referred surveys or between them between itself and the edges the cell zones, avoiding, called sub-cells where the Sheet material is calendered. This calendering is only possible if there is a free space sufficient, the compliant material the backing roll pressure onto the ground surface between die suppositories exert allow. According to the reproduced embodiment these isolated form elevations lines parallel to the edges of the Cells and divide them into 9 sub-cells.

it Experiments were carried out, to the behavior of a sheet material according to the invention compared show with a sheet material according to the prior art. The elements and the results are in the following table reproduced.

The Pattern according to the prior art consists together evenly along for example, substantially oriented in the machine direction Rows distributed elevations, which are arranged as desired, in a Amount of 80 surveys per cm², The surface at the highest Place of stamping suppository is 4.4 mm², The pattern occupies 100% of the surface.

The tested Pattern of the invention is the one which in the <figref idrefs="S14">1</figref> reproduced is. The average number of surveys is 25 per cm², However increases in the areas B1, B2 and B3 which form the boundaries, the density at 60 surveys per cm² at. The surveys take 20% of the surface of the sheet material a; in other words, taking the whole of the sub-cells 80% of the surface on.

<img img-content="tb" img-format="tif" he="64" wi="151" file="00100001.tif" />

it were for the two patterns embossed suppository the same geometry and the same size used. The impression is the size of the imprint the rigid roll on the roll of rubber. For a same rubber quality is this Value is a function of the applied Pressure. Thus, the greater The impression is, the higher is the pressure. The value 0 of impression are the characteristics of the sheet material before to embossing. By plotting the values ​​on a graph of the <figref idrefs="S15">2</figref>. the tear strength, the sheet goods reproduces as a function of thickness, and by pulling a regression line between the plotted values ​​is one finds that the Pattern of the invention features equivalent to those of a pattern by having the prior art.

one receives so without the by embossing induced high density sacrificing and demanded features something, a product which is softer is. One understands that one one according to the claimed pattern embossed Location with an identical position or another position after can combine prior art, and receive a sheet material can, the relatively soft is due to the low number of connection points.