DE102004048432A1 - Multi-ply fabric with binodal MD yarn - Google Patents

Abstract

The present invention relates to a monofilament yarn for use in an industrial textile, the yarn having a binodal cross-section. The present invention further relates to an industrial fabric, preferably a papermaking fabric, comprising at least one monofilament yarn having a binodal cross-section. Moreover, the present invention relates to a process for producing an industrial fabric comprising a monofilament yarn having a binodal cross section.

Description

AREA OF INVENTION

The The present invention relates to industrial fabrics and more particularly but not exclusively Industrial materials such as papermaking materials.

The Structure of molded materials for use in papermaking devices influences web formation from the wet pulp and therefore has one Impact on quality of the produced paper. traditionally, Molded fabrics are made of fabrics made by weaving cylindrical monofilament strands made of polymer material or metal wires. The Knots formed at the intersections of such woven fabrics be left on the paper surface, however, impressions, which the softness is reduced. It has also been shown that such Substances a bad detachment of the leaf show.

Around mitigate the disadvantages described above, substances are developed in which at least some of the individual yarns within the Structure of the fabric composed of a plurality of individual, connected monofilament polymer strands are.

In US 4,636,426 (Huyck Corporation) two adjacent monofilament strands are adhered together using a heat activated polymer adhesive. The linked strands are used either in the machine direction (MD), in the cross direction (CD) or both in MD and in CD of the fabric. The adhesive is also used to glue the MD and CD yarns at their crossing points. This reduces the overall height of the nodes.

In US 5,591,525 (Shakespeare) and eliminated from it US 5,597,646 (Shakespeare), the fabric is formed by using yarns formed by extruding at least two individual filaments of polymer through a nozzle about an axis, with the swelling of the material at the die melting the filaments together. The one axis forms a central axis, which can be either a filament or a cavity.

substances which have been formed by using bonded yarns, However, they have the disadvantage that they are not very stable and vulnerable for one Separation of the so-called connected (glued or merged) Yarns are.

In US 5,944,062 (Christini Forming Fabrics GmbH) is the weave of the fabric so that adjacent MD or CD yarns are woven in side-by-side pairs so that they touch each other. This has the disadvantage that the problem of separation of the yarns remains, together with the fact that two inserts of the weaving machine are required during the formation of the fabric to insert such pairs.

In US 5,366,798 (Wangner Systems Corporation) woven a simple system of warp yarns with stacked triple wefts. The central yarn of the triple-weft has a cross-section which has an H-shaped, star-shaped or X "-shaped configuration; this shaped cross-section forms an upper and a lower channel, in which the respective upper and lower shot of the stack is received and held. This helps to prevent the lateral shifting of the yarns within the stacked structure, which would result in a change in the knot pattern presented on the support surface of the fabric, and a change in the drainage properties;
US 4,705,601 (Chiu-Kai) describes a three-ply molding material in which warp yarns having an oval cross-section are incorporated in the lowermost, ie machine-side, layer. Oval warp yarns have a greater tensile strength than the cylindrical yarns used in the topmost, ie, pulp side layer, thereby allowing a comparatively smaller number of such oval yarns to be used than to cylindrical yarns. This allows a lower density in the bottom layer, allowing greater water extraction, since it is possible to apply a larger suction pressure to the bottom layer. However, the oval yarns have the same vertical height as the cylindrical yarns, so that the general thickness of the fabric is not changed by the use of such yarns and thus the surface of the uppermost layer is not changed.

SUMMARY THE INVENTION

It is an object of the present invention to provide a substance where the impact that the node carried on it Product has been reduced, and that overcomes the disadvantages described above or relieved.

According to one Aspect of the present invention is a Monofilamentgarn with a provided binodal cross-section.

The binodal monofilament yarn can be two Include nodes that are immediately adjacent, or the nodes may be separated by a one-piece link bridge.

The binodal yarns preferably have an aspect ratio between maximum width and maximum height in the range of 1.1 to 1.7, preferably 1.3 to 1.6 and on most preferably from about 1.4 to.

The binodal yarns can be symmetrical or asymmetrical with respect to your longitudinal axis.

According to one another embodiment of the invention the knots on one side of the yarn be flat.

The Binodal yarns are preferably made of a polymeric material. The polymer material preferably comprises PA, PE, PET alone or in Combination.

According to one second aspect of the invention, an industrial fabric is provided comprising at least some monofilament yarns with binodal cross section.

By Provide a yarn that is made from a simple filament is, the yarn has more structural unit and is therefore more stable and less vulnerable for separation compared to a fused yarn, to yarns that during the die swell or yarns that are simply placed side by side. The raised stability allows furthermore, the use of thinner (vertically) Yarns, whereby the fabric thickness is further reduced while the Cavity volume is maintained or decreases. For example, one could binodal yarn is a yarn of thicker diameter but with the same Replace mass to reduce fabric thickness.

While the Mass remains the same, decreases the void volume. A decrease of the void volume leads to a lower water capacity and thereby reduces the likelihood of rewet. The is particularly advantageous for Molded materials. In connection with the production leads the to a drier sheet, resulting in energy savings or a possibility means to speed up the paper machine.

The resulting decrease in knot height leads to improved smoothness of the paper and easier sheet separation. The channel between the Knot leads for improved drainage. The nodes also make point contacts with the product that is on the Fabric is moved, ready, resulting in much finer wire marks leads. There is also a reduction in the time required to weave the fabric because the binodal yarn takes the place of two separate yarns occurs.

One Fabric constructed with binodal yarns also has one improved stiffness, resulting in high speed gap formers advantageous with their closed mold zones. Stiffness corresponds good macro-sheet formation by reducing streaks (Density variations) caused by a substance with low stiffness is unable to control the hydraulic pressure unbearable.

According to one preferred embodiment of Invention are the binodal yarns warp yarns and / or weft yarns of the substance.

According to one another embodiment According to the invention, the fabric is a multi-ply fabric, the binodal fabric Yarns on the paper side layer and / or the wear side Layer and / or on the middle layer of the substance comprises.

binodal Yarns that are used on the paper side of the fabric lead to a decrease in node height, which leads to a smoother surface in contact with the paper a lower tendency to wire marking. Binodal yarns that on the wear side the fabric preferably but not exclusively used as CD yarns be, have the advantage of doing the scraping of the fibers of elements and to improve the friction / drive load by trapped Reduce water, resulting in an extension of the life of the Stoffes leads. Binodal yarns can, when added to the middle or upper layer of, for example, a triple weft fabric, provide good stiffness, providing additional fiber support in the top layer brings.

advantageously, are all warp yarns of paper side layer with binodal cross section Mistake.

Of Further, it is advantageous if all wear side warp yarns with binodal Cross section are provided.

Around to increase the flatness of the paper side layer have at least some the binodal yarns provided on the paper side layer are directed a flat side to the paper side.

In order to increase the wear resistance of the wear-side layer, at least some of the binodal yarns provided on the wear-side layer have a fla che side facing the wear side.

According to one Another aspect of the invention, the binodal yarns, the on the paper-side layer are provided, the same aspect ratio like the binodal yarns provided on the wear side layer are.

Around a fine and smooth paper side and a wear-resistant wear side too preferably have at least some binodal yarns, which are provided on the paper side layer, a smaller one Total cross-sectional area as the binodal yarns provided on the wear side layer are.

According to one Third aspect of the present invention is a method for Preparation of an industrial fabric provided, comprising Step of extruding a single filament yarn through a nozzle to a to produce binodal monofilament yarn.

When Examples will now be specific embodiments of the invention with reference to the accompanying drawings:

1 Figure 4 is a graphic representation of four different binodal yarns, each constructed in accordance with the present invention;

2a and 2 B are sectional side views of a single-ply fabric woven with asymmetrical binodal yarns;

3a Figure 3 is a sectional side view of a prior art monofilament using monofilament MD yarns;

3b is a view similar to 3a but compares the same fabric constructed of binodal yarns in place of known monofilament MD yarns and represents the overall reduction in thickness for a fabric constructed in accordance with the present invention;

4 Figure 3 is a sectional side view of a double-layered fabric using binodal MD yarns;

5 Figure 3 is a sectional side view of a double-layered fabric comprising paper-side and wear-side binodal CD yarns;

6 Fig. 3 is a sectional side view illustrating a three-shot structure using binodal MD yarns;

7 Fig. 4 is a sectional side view illustrating a three-shot structure using binodal CD yarns;

8th Fig. 3 is a sectional side view illustrating a three-shot cloth using binodal MD yarns; and

9 Figure 5 is a sectional side view illustrating a three-shot fabric using binodal CD yarns.

The binodal yarns of the present invention are made by extruding a simple filament to form a binodal yarn. Examples of the shapes of such binodal yarns are in 1 where yarns (a) and (b) are symmetrical about their X-axis and yarns (c) and (d) are not symmetrical about their X-axis. In the yarn of 1 (a) and 1 (d) are the two nodes 10 . 12 formed integrally and are immediately adjacent to each other, while in the yarn of 1 (b) and 1 (c) the two nodes 10 . 12 by an integrally formed connecting bridge 14 spaced apart from each other.

2a and 2 B represent the use of asymmetric binodal yarns (c) and (d) in a single-ply fabric 34 and 36 It goes without saying that the yarns can be either MD or CD direction or both MD and CD direction. The yarns can also be in any position with their flatter side to (as in 2a ) or away (as in 2 B ) are woven by the yarns woven in the opposite direction. The orientation of the yarns is selected depending on the required machine conditions.

It will be understood that other types of binodal yarns such as (a) and (b) could be used in such a single-ply fabric. For example, in 3b the yarn having the cross section shown in Fig. 1 (a) as MD yarn in a single-layered structure 38 shown. In 3a is a conventional fabric with the same pattern as that of 3b woven but with conventional cylindrical yarns and not with binodal yarns. The measurement of the thickness A of the conventional substance ( 3a ) compared to the thickness B of the fabric made from binodal yarns ( 3b ), shows that the total thickness of the binodal fabric B is smaller than the thickness A of the conventional fabric, whereby the overall height of the knots is reduced and, consequently, tends to be crushed when used as a papermaking material, for example ,

Moreover, by forming the binodal yarn from a simple yarn, it is possible to make a yarn with increased structural unit compared to a paired, bonded or fused yarn. The increased stability allows the use of thinner yarns to reduce fabric thickness while maintaining or reducing the void volume. For example, a binodal yarn could replace a thicker diameter cylindrical yarn but with the same mass to reduce fabric thickness. While the mass remains the same, the void volume decreases. A decrease in void volume results in lower water-carrying capacity and therefore reduces the likelihood of rewet. This is particularly advantageous with molding materials that result in the production of a drier sheet, which would mean energy savings or a chance to speed up the paper machine.

Besides that is a channel for the drainage between The two knots provided, resulting in a flat yarn, the not the ability for drainage is not the case. The nodes of the binodal yarn show even just a point contact, creating a much finer wire pattern is made compared to the wider contact made by a flat yarn is provided.

4 introduces the use of binodal yarns as machine direction yarn 16 in a double-layered fabric 22 while 5 the use of binodal yarns 16 . 18 both in the machine direction and in the transverse direction of a substance 24 represents. The reference number 18 refers to yarns with binodal cross section and the numeral 20 Twines.

6 represents a three-shot structure 26 wherein the binodal yarn is a machine direction yarn 16 is used while in the embodiment of 7 the binodal yarn as the cross direction yarn 18 in a three-shot structure 28 is used. In the embodiment of 8th is the binodal yarn as machine direction yarn 16 only on the machine side of a three-shot structure 30 used while 9 a similar structure 32 with the binodal yarn as the cross-direction yarn 18 represents.

Other Variations in the use of binodal monofilament yarns Professionals will easily encounter.

Claims (18)

Monofilament yarn for use in an industrial textile, wherein the yarn has a binodal cross-section. Monofilament yarn according to claim 1, characterized in that that the binodal yarn comprises two knots immediately adjacent are. Monofilament yarn according to claim 1, characterized in that that the binodal yarn comprises two nodes separated by a one-piece connecting bridge are. Monofilament yarn according to one of claims 1 to 3, characterized in that the binodal yarn has an aspect ratio of maximum width to maximum height greater than 1, preferably in the range of 1.1 to 1.7, more preferably from 1.3 to 1.6, and most preferably around 1.4. Monofilament yarn according to one of claims 1 to 4, characterized in that the binodal yarn is symmetrical or asymmetric with respect its longitudinal axis is. Monofilament yarn according to one of claims 1 to 5, characterized in that the nodes on one side of the yarn are flat. Monofilament yarn according to one of claims 1 to 6, characterized in that the binodal yarn of a polymeric material wherein the polymeric material is preferably PA, PE, PET alone or in combination. Industrial fabric, preferably a papermaking fabric, comprising at least one monofilament yarn according to one of claims 1 to 7th Industrial fabric according to claim 8, characterized in that that the binodal yarns are warp yarns and / or weft yarns of the fabric are. Industrial fabric according to one of claims 8 to 9, characterized in that the substance is a multilayer material is the binodal yarns on the paper side layer and / or the wear side layer and / or on a middle layer of the fabric. Industrial fabric according to one of claims 8 to 10, characterized in that all the warp yarns of the paper side layer provided with binodal cross-section. Industrial fabric according to one of claims 8 to 11, characterized in that all warp yarns on the wear side with binodal cross-section are provided. Industrial fabric according to one of claims 8 to 12, characterized in that at least some of the binodal Yarns provided on the paper side layer, a have flat side facing the paper side. Industrial fabric according to one of claims 8 to 13, characterized in that at least some of the binodal Yarns on the wear side Layer are provided, a flat side facing the wear side exhibit. Industrial fabric according to one of claims 8 to 14, characterized in that the binodal yarns on the paper side layer are provided, which have the same aspect ratio like the binodal yarns provided on the wear side layer are. Industrial fabric according to one of claims 8 to 15, characterized in that at least some of the binodal Yarns provided on the paper side layer, a smaller total cross-sectional area exhibit as the binodal yarns that are on the wear side Layer are provided. Industrial fabric according to one of claims 8 to 16, characterized in that the substance is a molding material or a Drying fabric or a base cloth of a press felt or a smoothing belt or a transfer belt is. Process for the production of an industrial fabric comprising the step of extruding a single filament yarn through a nozzle, to produce a monofilament yarn having a binodal cross section.