Patent Grant
7670461
1. Field of the Invention
The invention relates to a papermachine fabric for dewatering and drying a fibrous web in a machine producing a fibrous web.
2. Description of the Related Art
Known papermachine fabrics, in particular papermachine felts, are traditionally produced from a combination of carrier structures and fiber batts. This type of production of papermachine fabrics generally requires a considerable amount of time and, accordingly, gives rise to high production costs.
In previous years, there were again and again approaches to replacing the carrier structures in the form of woven base fabrics with alternative carrier structures that can be produced more quickly, such as knitted fabrics, laid scrims or the like. However, most of these approaches were unsuccessful. Moreover, these modified papermachine fabrics were distinguished by a reduced stiffness and a reduced creep resistance as compared with conventional fabrics of the same type.
What is needed in the art a papermachine fabric of the type mentioned above in such a way that it exhibits low stretch, associated with linear elastic deformation.
According to the invention, the fiber batt is provided with a coating, at least on one side. This provision of a coating on at least one side of the fiber batt provides the advantage of lower stretch, associated with linear elastic deformation. In addition, the production costs are reduced considerably by means of a reduction in the production time. The coating according to the invention, which preferably adheres firmly, can be applied to the fiber batt over the entire area or partly.
According to a first embodiment, provision is made for the coating to be a force-absorbing coating. The force-absorbing coating can in this case also include fiber matrix structures. As a result, the possibility is created of designing the carrier structure more simply, that is to say with reduced properties, in particular of a mechanical nature.
The force-absorbing coating can alternatively or additionally be reinforced by using textile reinforcing structures, the intention being for “textile reinforcing structures” to be understood to mean products which, amongst other things, are formed by textile production methods such as weaving, non-woven production, intermeshing methods, laying methods or combinations of the same. Isotropic/anisotropic fiber reinforcing structures can also be provided, which are embedded in the coated layers and/or connected to them.
In a further embodiment, it is proposed to provide the coating with a woven layer on its side facing away from the fiber batt. This woven layer can preferably again have a force-absorbing structure.
In a third embodiment, provision is made for the fiber batt to be provided with a force-absorbing structure on its side facing away from the coating. As a result, the possibility is again created of designing the carrier structure more simply once more, that is to say with reduced properties, in particular of a mechanical nature.
Furthermore, the force-absorbing structure can be provided with a coating on its side facing away from the fiber batt, and the coating can in turn be provided with a fiber batt on its side facing away from the force-absorbing structure.
In a fourth embodiment, it is proposed that the fiber batt be provided on the side facing away from the coating with a coating which, moreover, is preferably a force-absorbing coating. Thus the carrier structure, as already explained, can once more be designed more simply.
The coating according to the invention is preferably firmly connected to its adjacent layer, at least on one side, so that the highest extent of layer adhesion and stability is achieved. In this case, the coating does not necessarily have to be connected to the adjacent layer over the entire area; partial-area connection is certainly adequate, depending on the application. At least in theory, it is conceivable for the coating, particularly on a nonwoven base, to enter into a true connection only with some of the nonwoven fibers.
Furthermore, the coating can be permeable, that is to say permeable from all sides, semi-permeable, that is to say permeable from only one side, or non-permeable, that is to say impermeable on all sides. Thus, the highest degree of utility is created for the coating.
The permeable coating preferably consists of at least one thermoplastic, elastomer, thermosetting or polymer material, in particular polyurethane. On the other hand, the semi-permeable coating preferably has a cast membrane structure.
In addition, the coating can be arranged in such a way that it touches the fibrous web during the use of the papermachine fabric. This reduces and even eliminates the marking tendency of the carrier structure.
Generally, the papermachine fabric according to the invention preferably has a thickness variation which is ≦40%, preferably ≦25%, in particular ≦10%, of the average layer thickness, secondly it preferably has a hardness variation ≦70 Shore A, preferably ≦35 Shore A, in particular ≦15 Shore A, of the average layer hardness.
In one embodiment, the papermachine fabric is a press felt for dewatering and drying a fibrous web in a machine producing a fibrous web, consisting of a plurality of layers and including at least one carrier structure and a fiber batt consisting of at least one fiber non-woven, the press felt having at least two coatings according to the invention and preferably absorbing force and having a top coating.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate one preferred embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
A papermachine fabric 1 of this type is used, as is known, for dewatering and drying a fibrous web in a machine producing a fibrous web. It generally consists of a plurality of layers, these being formed by at least one carrier structure and by at least one fiber batt 2 consisting of a fiber non-woven 3. The carrier structure is not illustrated explicitly in the figures.
In a first embodiment according to
In a further embodiment according to
In a third embodiment according to
Furthermore, in a fourth embodiment according to
Coatings 4, 11, 15 illustrated in
Furthermore, respective coating 4, 15 of
Fiber batt 18 is provided with a preferably force-absorbing coating 20 oriented toward the outside, which for its part is in turn provided with a fiber batt 21 consisting of a fiber non-woven 22. The preferably force-absorbing coating 20 is preferably formed both in the machine running direction and in the cross-machine direction.
Fiber batt 21 is once more provided with a preferably force-absorbing coating 23 which for its part is in turn provided with a fiber batt 24 consisting of a fiber non-woven 25. Force-absorbing coating 23 is also preferably formed both in the machine running direction and in the cross-machine direction. The two coatings 20 and 23 can include different materials and accordingly also have different properties.
Furthermore, fiber batt 24 is provided with a final top coating 26, which touches the fibrous web during the use of the papermachine fabric.
That which was stated for the coatings and structures 4, 11, 15 illustrated in
The force-absorbing coatings and structures 4, 11, 15 of
In summary, it is to be recorded that, by way of the invention, a papermachine fabric of the type mentioned at the beginning is developed in such a way that it exhibits low stretch, associated with linear elastic deformation.
While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 030 774 | Jul 2005 | DE | national |
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| 5783501 | Schuetze et al. | Jul 1998 | A |
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| Number | Date | Country |
|---|---|---|
| 1674612 | Jun 2006 | EP |
| WO9941447 | Aug 1999 | WO |
| WO 9941447 | Aug 1999 | WO |
| WO 03091498 | Nov 2003 | WO |
| WO2004038093 | May 2004 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20070000632 A1 | Jan 2007 | US |
