Paper machine clothing, method for producing same, and nonwoven fabric

Abstract

A clothing for a machine for producing a fibrous web, especially a paper, cardboard, tissue or cellulose pulp web. The clothing has a basic structure with a top side and a running side as well as a nonwoven support at least on one side. The nonwoven support has a functional zone, which extends over more than 50 μm in the thickness direction of the clothing and which includes a first portion and a second portion of nonwoven fibers. The nonwoven fibers of the first portion are formed of, or include, a polyurethane, especially a thermoplastic polyurethane, while the nonwoven fibers of the second portion are a polymer material not including a polyurethane. The first portion makes up between 10 wt. % and 60 wt. %, of the functional zone. There is also described a method for production and a suitable nonwoven fabric.

Claims

1. A clothing for a machine for producing a fibrous web, the clothing comprising: a basic structure having a top side, a running side, and a nonwoven support at least on one side; said nonwoven support having a layer being a functional zone that extends over more than 50 μm in a thickness direction of the clothing and includes a first portion and a second portion of nonwoven fibers; said nonwoven fibers of said first portion containing a polyurethane, and said nonwoven fibers of said second portion consisting of a polymer material not including a polyurethane; said first portion making up between 10 wt. % and 60 wt. % of said functional zone; and the polyurethane material of said nonwoven fibers of said first portion having a hardness between 35 Shore D and 85 Shore D.

2. The clothing according to claim 1, wherein said nonwoven fibers of said first portion consist of a thermoplastic polyurethane.

3. The clothing according to claim 1, wherein said first portion makes up between 20 wt. % and 45 wt. % of said functional zone.

4. The clothing according to claim 1, wherein said polyurethane material of said nonwoven fibers of said first portion has a hardness between 50 Shore D and 85 Shore D.

5. The clothing according to claim 1, wherein said functional zone extends in the thickness direction for less than 5 mm.

6. The clothing according to claim 1, wherein said nonwoven fibers of said first portion have a fiber fineness between 30 dtex and 80 dtex.

7. The clothing according to claim 6, wherein said nonwoven fibers of said first portion have a fiber fineness between 50 dtex and 70 dtex and said nonwoven fibers of said second portion have a fiber fineness between 20 dtex and 70 dtex.

8. The clothing according to claim 1, wherein said nonwoven fibers of said second portion have a fiber fineness between 10 dtex and 80 dtex.

9. The clothing according to claim 1, wherein said first portion and/or said second portion comprise nonwoven fibers with different fiber fineness.

10. The clothing according to claim 1, wherein between 15 g/m.sup.2 and 250 g/m.sup.2 of nonwoven fibers of said first portion are provided in said nonwoven support.

11. The clothing according to claim 1, wherein between 100 g/m.sup.2 and 1500 g/m.sup.2 of nonwoven fibers of said second portion are provided in said nonwoven support.

12. The clothing according to claim 1, which comprises at least one further functional zone in which said first portion amounts to less than 10 wt. %, and which is disposed between said basic structure and said functional zone and/or between said functional zone and a surface of the clothing.

13. The clothing according to claim 1, wherein said functional zone forms a surface of the clothing.

14. The clothing according to claim 1, wherein said nonwoven support is provided on a side of said basic structure disposed for touching the fibrous web.

15. The clothing according to claim 1, wherein said basic structure consists of a flat weave.

16. The clothing according to claim 1, wherein said basic structure is a flat weave with end-side edges and having a length substantially twice a length of the clothing in a finished condition, said flat weave being folded at folds and defining folded portions that are deposited back onto the flat weave to form a two-layer structure, and wherein seam loops are formed at said folds, enabling the basic structure to be merged with a pintle to form an endless structure.

17. The clothing according to claim 1, wherein said basic structure comprises a flat weave that is narrower than said basic structure in a width direction and said basic structure is formed by spiraling said flat weave.

18. The clothing according to claim 1, wherein said nonwoven fibers of said first portion consist of polyurethane.

19. A method for producing a clothing for a machine for producing a fibrous web, the method comprising: i) providing a basic structure; ii) providing a functional nonwoven layer, the functional nonwoven layer to extend over more than 50 μm in a thickness direction of the clothing and including a first portion and a second portion of nonwoven fibers, the nonwoven fibers of the first portion containing a polyurethane, the nonwoven fibers of the second portion consisting of a polymer material not including a polyurethane, and the first portion making up between 10 wt. % and 60 wt. % of the functional nonwoven layer; and the polyurethane material of the nonwoven fibers of the first portion having a hardness between 35 Shore D and 85 Shore D; and iii) securing the functional nonwoven layer, and optionally securing further nonwoven layers, to the basic structure by needling.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) In the following, the invention shall be explained more closely with the aid of schematic figures, not drawn to scale.

(2) FIG. 1 to FIG. 4 respectively show a paper machine clothing according to one aspect of the invention.

(3) FIGS. 5a to 5c show a class of basic structures which can be used advantageously for the present invention.

(4) FIG. 5d shows a paper machine clothing according to another aspect of the invention making use of a basic structure from FIGS. 5a to 5c

(5) FIG. 6 shows another possible basic structure for a paper machine clothing according to another aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows schematically a first section through a paper machine clothing according to one aspect of the invention. It comprises a basic structure 1, being in this embodiment a woven basic structure 1. The weave may be a single or a multiple ply. In general, a woven basic structure 1 may consist of a single weave or also multiple weaves, or comprise such. On the bottom side of the basic structure 1 there is provided a nonwoven support 2b. This may be a traditional nonwoven support with nonwoven fibers made from a polyamide. This nonwoven support 2b also provides the running side 11 of the paper machine clothing.

(7) On the top side of the basic structure 1 there is provided a further nonwoven support 2a. This nonwoven support 2a comprises a functional zone 3. The thickness of the functional zone 3 is at least 100 μm, preferably more than 200 μm or more than 300 μm. This functional zone 3 comprises a first portion of PU fibers as well as a second portion of non-PU fibers. The first portion makes up between 10 wt. % and 60 wt. %, preferably between 10 wt. % and 50 wt. %, especially preferably between 20 wt. % and 45 wt. % of the functional zone.

(8) The top nonwoven support 2a may comprise basically all kinds of nonwoven fibers outside of the functional zone. Advantageously, for example, it may consist primarily of non-PU fibers. The portion of the PU fibers outside the functional zone can make up 10 wt. % or less, for example.

(9) The top nonwoven support 2a also provides the surface 10 touching the fibrous web.

(10) The functional zone 3 in the embodiment of FIG. 1 is arranged such that it neither provides the surface 10 touching the fibrous web nor borders directly on the basic structure. Yet this need not be the case. It is entirely possible for the functional zone 3 to provide the surface 10 touching the fibrous web and/or to be arranged in direct contact with the basic structure.

(11) The paper machine clothing represented in FIG. 2 differs from that represented in FIG. 1 basically in that the top nonwoven support 2a has two functional zones 3, 3a, having respectively PU fibers and non-PU fibers. In both functional zones, the portion of the PU fibers is between 10 wt. % and 60 wt. %, preferably between 10 wt. % and 50 wt. %, −%, especially preferably between 20 wt. % and 45 wt. %. It may be provided that the portion of PU fibers in the different functional zones 3, 3a is the same or different. Furthermore, it may be provided that the material of the nonwoven fibers and/or the fiber fineness in the different functional zones 3, 3a is the same or different.

(12) Between the two functional zones 3, 3a there is provided a region in which the portion of the PU fibers is less than 10 wt. %.

(13) One functional zone 3a of the paper machine clothing shown in FIG. 2 borders directly on the basic structure 1. In other embodiments, however, multiple functional zones 3, 3a may also be provided, none of which borders directly on the basic structure 1.

(14) The paper machine clothing shown in FIG. 3 has, in contrast with FIG. 1 and FIG. 2, a nonwoven support 2a on the top side consisting entirely of a functional zone. The portion of the PU fibers here is between 10 wt. % and 60 wt. %, preferably between 10 wt. % and 50 wt. %, especially preferably between 20 wt. % and 45 wt. % of the top nonwoven support 2a. Yet it may also be provided that the nature of the nonwoven fibers, in particular the PU fibers, may vary across the thickness of the nonwoven support 2a.

(15) FIG. 4 shows a paper machine clothing which differs from that shown in FIG. 1 in that a further functional zone 3b is provided in the bottom nonwoven support 2b. Such a functional zone 3b in the bottom nonwoven support 2b may be provided regardless of the configuration of the top nonwoven support, i.e., also for paper machine clothings of the kind shown in FIG. 2 or 3, for example. Once again, the functional zone 3b may be positioned howsoever desired within the bottom nonwoven support, i.e., also in direct contact with the basic structure 1, or such that it provides the running side 11 of the paper machine clothing.

(16) FIGS. 5a to 5c show a basic structure 1 which is especially advantageous for a paper machine clothing according to the present invention.

(17) A weave 100, in particular a flat woven weave 100, is used for the basic structure 1, having substantially twice the length of the finished paper machine clothing. This weave 100 has end-side edges 102, 103. In order to produce the basic structure 1, the weave 100 is folded at folding points 106, 107, and the folded parts are placed in turn on the weave 100. This produces a shape having two layers as compared to the original weave 100. The end-side edges 102, 103 may overlap, touch, or as shown in FIG. 5c have a slight spacing from each other. For better handling, the end-side edges 102, 103 may also be joined together in suitable manner. Furthermore, it may also be provided that the two layers are joined together. This may be done, for example, by seam joints 110. Seam loops 106a, 107a can be formed from the folding points 106, 107, which is preferably done by removing weave threads in the machine cross direction (CD). These seam loops 106a, 107a can be joined together and merged into an endless structure in a way familiar to the skilled person by means of a pintle. Now, nonwoven supports 2a, 2b can be placed on such a basic structure 1 and be secured by needling.

(18) FIG. 5d shows as an example a basic structure 1, as shown in FIGS. 5a to 5c, which uses as the basic structure 1 a paper machine clothing as shown in FIG. 1.

(19) FIG. 6 shows another possible basic structure 1. The basic structure 1 here is formed from a flat weave 100, which is narrower than the later basic structure 1 or the paper machine clothing. The required width of the basic structure 1 was realized by coiling the flat weave 100. In frequent embodiments, the flat weave 100 has a width between 50 cm and 2 m, in particular 100 cm. The length L of the resulting loop is generally over 10 m, also often over 20 m or 30 m. At the abutment joints W, the edges of the weave 100 of adjacent coils can be joined together, in particular they can also be welded together.

(20) A loop as is shown in FIG. 6 can be used directly as the basic structure 1 for an endless paper machine clothing. The top side t and/or the bottom side b may be further provided with nonwoven supports.

(21) Alternatively, however, this basic structure may also serve as a basic structure 1 for a seamed felt. In this case, the loop 1 is produced similarly to FIGS. 5c and 5d basically in twice the length of the paper machine clothing, and laid on top of one another to form a flat, double-layered shape. This once again produces folds, which serve as the basis of the seam loops of the seam joint as described above. Now, once again nonwoven supports 2a, 2b can be placed on such a basic structure 1 and be secured by needling, for example.

(22) The examples shown constitute advantageous embodiments of the invention. However, the invention is not limited to these embodiments.