JP2001512192A - Multilayer screen for wet section of paper machine and product produced using it - Google Patents

Abstract

(57) Abstract: The present invention relates to a multilayer screen (10, 11) for a wet section of a paper machine and a thin paper produced using the same. SOLUTION: The screen of the present invention comprises fine wires, preferably knitted fine wires forming at least two layers. The layers are connected to one another by additional fine wires (14) interwoven into the layers. The additional thin lines (14) together with the thin lines making up the layer form narrowing points (16), said narrowing points being distributed throughout the screen. A very small amount of water can pass through these stenosis points than through adjacent areas. To produce tissue paper with alternating high and low areas of GSM material, the extra fine lines are arranged in a special continuous pattern, providing a means to affect the water squeezing through the screen at the point of constriction. . The present invention therefore provides a simple means of producing a tissue paper having a flexible, thin, heterogeneous, mesh-like structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates in particular to a multilayer screen for use in the wet machine (den Nassbereich) of tissue making paper machines, comprising at least two layers of fine wires, preferably knitted wires, which layers are provided by additional fine wires interwoven into the layers. Combined with each other. The present invention
It also relates to products made using this screen.

[0002]

[Prior art]

Such a multilayer screen is known from US Pat. No. 5,219,004. In the production of paper (Papier) and especially tissue-paper (Tissue-Papier), intentional and selective water removal through a screen covered with a specific area results in the fibers being deposited alternately in the wet area as a result of differential deposition. It is well known to provide high and low basis weight (Flaechengewicht). The screen is squeezed (das abfliessende Wasse
The higher the permeability to r), i.e. the so-called open areas accumulate more fiber than the so-called closed areas. The closed and open areas are usually formed by arranging the weft and / or warp yarns of the fabric forming the screen at different distances from each other, so that the difference between the machine direction and the transverse direction perpendicular thereto is obtained. Occurs.

[0003] As a result, there is a difference in the basis weight in a macroscopic region during paper production,
A paper that has a mesh-like structure, which will convert the normally flat, homogeneous, normally inflexible structure of dried tissue to a flat, non-homogeneous, mesh-like structure from external forces. For example, it becomes possible to produce tissue paper; such a structure provides a flexible response under loads due to external forces. Paper, such as conventional tissue paper, has a planar structure in which individual fibers are firmly fixed within the structure. In the case of a macroscopically uniform basis weight, the coalescence of the fibers into the structure results in an inflexible rigid structure. In the unwrinkled state, the tissue has a very low expansion value in the range of <= 6%. The wrinkling process commonly performed in the production of tissue makes the tissue particularly flexible in the machine direction, with respect to the load as a result of external forces. The high flexibility in the machine direction, which can be achieved by wrinkling in the case of a homogeneous paper structure, has been demonstrated by a high practicality and is accompanied by a large stretch in the machine direction.

[0004] The flexibility of paper, and thus the tissue, can also be improved by converting a planar homogeneous structure to a mesh planar heterogeneous structure, where the improvement is limited to the machine direction only. But also in the lateral direction.

[0005] As already mentioned, the network structure is achieved by varying the basis weight, where high and low basis areas alternate in the macroscopic region. The change in basis weight is achieved by changing the water removal of the screen. The location where a large amount of fiber has been deposited according to the above comments is known as a high basis weight area. Places where little fiber accumulates are called low basis weight areas.

[0006] There is a local flow parallel to the screen surface due to the different water-drawing capabilities of the screen, thereby providing a more or less substantial alignment of the fibers, similar to the production of a real watermark.

[0007] Areas with different water squeezing capacities can be achieved by constriction of the screen by sealing that area within the screen with a synthetic adhesive or dye, for example (see WO 93/00).
474).

[0008] Changes in the degree of opening of the screen can also be brought about by combining different knitting patterns. The basic fabric forming the structure of the screen may be one or more layers, but preferably two layers. As already mentioned in connection with U.S. Pat. No. 5,219,004, the layers should be joined together using additional wires.

[0009]

[Problems to be solved by the invention]

It is an object of the invention to provide a multilayer screen of the type mentioned at the outset. Such a screen is one in which the aforementioned modified water removal properties can be easily adjusted to produce an improved product.

[0010]

[Means for Solving the Problems]

According to the invention, this object is solved in that the additional fine lines together with the fine lines making up the layer form stenosis points distributed throughout the screen. Only a small amount of water can be squeezed through these stenosis points compared to penetrating the area adjacent thereto.

A feature of this solution is that the extra fine lines used to join the layers of the screen are used to form a closed or essentially closed area of the screen, the extra fine lines being used to form the screen. Essentially open areas are formed in areas that do not seal the mesh of the basic fabric. The extra wires are therefore used to perform two functions. Well improved paper products, especially tissue paper, can be produced using such screens.

One useful extension of this solution is that an additional thin line forming a stenosis point extends, for example, in the machine direction, and appears at predetermined points on the top surface of the screen or of a layer disposed thereon, These narrow lines form a stenosis region by stenosis points gathered or arranged in different directions, and such a stenosis region appears as a pattern covering the screen surface. These locations form a low basis weight macroscopic area of paper or tissue, i.e., a structure with less fiber deposition than adjacent areas, which has a positive effect on the expansion behavior in the longitudinal or intersecting direction, especially in the intersecting direction. . This is due to the fact that, depending on the alignment, the low basis weight parts of the surface area are weaker than the homogeneous structure, which makes the previously described heterogeneous structure more flexible than the homogeneous structure. Things. The difference in basis weight achievable in this way can be adjusted by the predefined structure of the fiber network of the paper, in particular the tissue paper, but leads to an increase in the practical water absorption in the longitudinal and transverse directions, this increase being particularly pronounced. This is desirable for tissue paper.

When the stenosis points are arranged side by side, for example, at an angle to the machine direction of the screen to form an elongated piece (die Laengenabschnitte), wrinkling is achieved by supplementing the flexibility in the machine direction. The resulting flexibility can be further improved to achieve high flexibility in the direction transverse to the machine direction.

[0014] To form elongated fragments, to the same effect, the constriction points are arranged to some extent perpendicular to the machine direction and to some extent in the machine direction.

[0015] With respect to other possible embodiments, the elongated pieces may be alternately aligned in opposite directions. Elongated fragments may be arranged in blocks, parallel to similarly arranged lines.

According to a further embodiment, the stenosis points are arranged side by side, forming a zigzag or wavy continuous pattern.

The stenosis points are arranged to form a closed or at least partially open continuation pattern, similar to a continuous continuation pattern. The arrangement of the stenosis points is whether the discontinuous continuous pattern exists alone or together with the continuous continuous pattern.

[0018] Paper products made with such screens, especially tissue papers, are endowed with a number of improved properties, especially so-called tactile quality and softness. Positive effects on the wrinkling process, drying, wrestling, and water squeezing, as well as positively affecting dry and wet strength.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

The invention will now be described in more detail with reference to exemplary embodiments that are shown purely schematically in the drawings. The two-layer screen is designed as a fabric having a top fabric 10 and a bottom fabric 11. The machine direction of the screen is marked by arrow A. Depending on the weave chosen, the fine wire 12a of the face fabric (surface in contact with paper) is designed as a warp or weft, preferably a warp. Conversely, the same applies correspondingly to the fine wires 12b of the surface fabric. Similarly, this applies correspondingly to the fine lines 13a and 13b of the bottom fabric.

In this exemplary embodiment, the additional thin wire 14 as the connecting thin wire 14 is
As shown in FIG. 1b, the additional thin line 14 extends in the same direction and parallel to the thin line 12a, and the additional thin line 14 extends between the thin line 13b and the thin line 13c of the bottom fabric 11, so that the top surface of the surface fabric 10 can be clearly seen from FIG. , Closing the mesh 15 and the additional thin line 14 extends in the machine direction above the fine line 12 c of the surface fabric forming the constriction point 16. Arranged side by side at an angle with the machine direction A, the plurality of stenosis points 16 result in stenosis regions 17 formed as elongated fragments. The parallel constrictions 17 and 18 extend in one direction, but are provided purely by way of example. Such constricted regions extend perpendicular to each other throughout the screen surface and are alternately supplied in a direction that forms a pattern of constricted regions. These constricted areas form the aforementioned low basis weight areas in the tissue made on this screen, and are highly flexible, planar and inhomogeneous mesh-like in the paper, which is desirable under load. Give structure. Many designs of such a structure can be inferred from FIGS. FIG. 2 shows a product made using the screen structure according to FIG. The darkly marked portions of the surface area form the network. This creates a continuous high basis weight area. The same applies to the product according to FIGS. FIG.
For the products according to 3, 4 and 5, the dark area-marked high basis weight portion of the surface area is the low basis weight area, and the light-weighted low weight basis area of the surface area is marked. May have a correspondingly high basis weight (see the examples of FIGS. 2a and 3a). The brightly marked portions of the surface area then form the network.

Further modifications of the screen structure can be more diagrammatically inferred from FIGS. In a product made using the screen structure according to FIG. 7 or 8, the low basis weight parts of the surface area form the network structure described above.

As shown in FIG. 13 a for a tissue paper according to the conventional method, virtually no change in the length of the tissue paper can be measured when a pulling force is applied, whereas in the case of the tissue paper according to FIG. Changes as shown in the figure.

[0023]

【The invention's effect】

The present invention therefore has the advantage that it makes it possible to provide a simple means for producing flexible, thin, inhomogeneous and tissue-like tissue.

[Brief description of the drawings]

FIG. 1 shows a top view of a multilayer screen according to the present invention. FIG. 1a shows a sectional view through the screen according to FIG. 1 along the intersection line aa. FIG. 1b shows a sectional view through the screen according to FIG. 1 along the intersection line bb.

FIG. 2 shows a top view of various structural designs of tissue paper made using a multilayer screen similar to FIG.

FIG. 2a shows top views of various structural designs of tissue paper made using a multilayer screen similar to FIG.

FIG. 3 shows top views of various structural designs of tissue paper manufactured using a multilayer screen similar to FIG.

FIG. 3a shows top views of various structural designs of tissue paper made using a multilayer screen similar to FIG.

FIG. 4 shows a top view of various structural designs of tissue paper made using a multilayer screen similar to FIG.

FIG. 5 shows top views of various structural designs of tissue paper made using a multilayer screen similar to FIG.

FIG. 6 shows a schematic representation of another multilayer screen with various designs for the layer arrangement of additional wires as connecting wires.

FIG. 7 shows a schematic representation of another multilayer screen with various designs for the layer arrangement of additional thin lines as connecting thin lines.

FIG. 8 shows a schematic representation of another multilayer screen with various designs for the layer arrangement of the additional wires as connecting wires.

FIG. 9 shows a schematic representation of another multilayer screen with various designs for the layer arrangement of additional thin lines as connecting thin lines.

FIG. 10 shows a schematic representation of another multi-layer screen with various designs for the layer arrangement of additional thin lines as connecting thin lines.

FIG. 11 shows a schematic representation of another multi-layer screen with various designs for the layer arrangement of additional wires as connecting wires.

FIG. 12 shows a schematic representation of another multilayer screen with various designs for the layer arrangement of additional thin lines as connecting thin lines.

FIG. 13a shows a planar, homogeneous tissue according to the prior art before and after applying a pulling force (arrow). FIG. 13b likewise shows the planar, heterogeneous, mesh-like tissue according to the invention before and after the application of a pulling force (arrow).

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Claims (14)

[Claims] 1. A thin wire, preferably a braided wire having at least two layers (10,11), said layers (10,11) being joined by interweaving the added thin wires (14). A screen, wherein the added fine lines (14) are distributed with fine lines (12a, 12b, 12c, 13a, 13b, 13c) constituting the layers (10, 11) throughout the screen. (16), wherein water can only penetrate the stenosis point so that water can be squeezed little more than penetrating the area adjacent to the stenosis point;
Multilayer screen for wet section of paper machine. 2. The stenosis point (2), wherein the additional thin line (14) extends in the machine direction (A).
16) and appear at a predetermined location on the surface of said screen (10) or in a layer located at that location, wherein the stenosis points are grouped together or arranged in different directions. The multilayer screen according to claim 1, characterized in that the fine lines are arranged to form a narrowed area (17, 18), and the narrowed area appears as a pattern on the surface of the screen. 3. The stenosis point (16) is arranged side by side and forms an elongated piece (17, 18) at an angle to the machine direction (A). 3. The multilayer screen according to 2. 4. The stenosis points (16) are arranged side by side and form elongated fragments (17, 18) somewhat perpendicular to the machine direction (A) and along the machine direction to some extent. The multilayer screen according to claim 1. 5. The multilayer screen according to claim 3, wherein the elongated pieces are alternately arranged in opposite directions. 6. The multilayer screen according to claim 3, wherein the elongated pieces (17, 18) are arranged in groups in parallel and parallel. 7. The multilayer screen according to claim 1, wherein the stenosis points are arranged side by side to form a zigzag or wavy pattern. 8. The multilayer screen according to claim 1, wherein the stenosis points are arranged so as to form a closed continuous pattern. 9. The multilayer screen according to claim 1, wherein the stenosis points are arranged to form a partially open continuous pattern. 10. The multilayer screen according to claim 1, wherein the narrowed points are arranged so as to form a continuous pattern. 11. The multilayer screen according to claim 1, wherein the narrowed points are arranged so as to form a discontinuous continuous pattern. 12. The multilayer screen according to claim 1, wherein the stenosis points are arranged so as to form a continuous and discontinuous continuous pattern. 13. A product manufactured by a paper machine using the multilayer screen according to any one of claims 1 to 12. 14. The product according to claim 13, wherein the product is tissue paper.
Product described in.