US20060278361A1

US20060278361A1 - Papermachine fabric

Info

Publication number: US20060278361A1
Application number: US11/437,353
Authority: US
Inventors: Arved Westerkamp
Original assignee: Voith Paper Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2005-05-20
Filing date: 2006-05-19
Publication date: 2006-12-14
Also published as: DE102005023390A1; EP1724393A1

Abstract

The invention relates to a papermachine fabric having a batt structure extending over the entire width of the fabric, the batt structure comprising at least one ultrathin elongated fiber batt which extends over a part width of the fabric and has a thickness of 0.3 mm or less.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 of German Patent Application No. 10 2005 023 390.2 filed on 20 May 2005, the disclosures of which is expressly incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a papermachine fabric for use in a paper, board or tissue machine.
2. Description of Background
In order to reduce the production costs for papermachine fabrics, the aim of current developments is often to provide modularly constructed papermachine fabrics.
One possibility for the modular construction of papermachine fabrics consists in providing carrier or reinforcing structures which are built up from basic elements that are prefabricated and joined to one another, such as threads and/or flat structures such as films or the like.
In the production of papermachine fabrics, use is currently made of batt structures having fiber batts with thicknesses in the region of 1.0 mm or more (measured in accordance with EN ISO 5084), batt structures being employed both in the production of press felts and in other papermachine fabrics such as forming fabrics or transfer belts.
As a result of using the relatively thick fiber batts, limits are placed on the variability in the production of the batt structures. For example, for a customer-specific adaptation of the fabrics to conditions in the paper machine of the customer and/or to the paper grade produced by the customer and so on, batt structures are provided individually, with thickness graduations of the batt structures which are often fine. In the case of the known fiber batts, this often requires individual production of the fiber batts specifically for the respective customer requirements, which often makes the costs for the production of such fabrics expensive.

BRIEF SUMMARY OF THE INVENTION

The object of the present invention is to propose a papermachine fabric having a batt structure whose properties can be adapted simply to the respective customer-specific requirements and which, moreover, can be produced more cost-effectively than the papermachine fabrics with a batt structure known from the prior art.
According to the invention, a papermachine fabric having a batt structure extending over the entire width of the fabric is proposed, in which the batt structure comprises at least one ultrathin batt section which, in its entire width, extends over part of the width of the fabric and has a thickness of 0.3 mm or less, measured in accordance with EN ISO 5084.
As a result of providing at least one ultrathin batt section which extends over part of the width of the batt structure and has a thickness of 0.3 mm or less, it is possible to build up the batt structure from one or more of the ultrathin and cost-effectively prefabricated batt sections in accordance with the specific requirements on the fabric, irrespective of its overall thickness and overall width.
Furthermore, it is conceivable, for example, for the ultrathin batt layer to be incorporated into a conventional batt layer, extending over only part of the width of the batt structure, in order to provide a dewatering performance over the aforesaid part width that is different from the remainder of the papermachine fabric. It is thus possible, with the at least one ultrathin batt layer, to influence one or more properties of a batt structure, for example a conventional structure, locally over a part width of the papermachine fabric without the planarity and thus the marking behavior of the batt structure being influenced notably as a result on account of the ultrathin thickness of the batt section.
On account of the very low thickness of the ultrathin batt section, this can, for example, simply be integrated locally into an existing batt structure without affecting the thickness of the latter substantially.
The ultrathin batt section is preferably formed in such a way that the latter is different from the remaining batt structure in at least one property. The property can be, for example, the permeability, the liquid storage volume or compressibility. Possible ways of influencing the at least one property of the ultrathin batt section consist, for example, in the fact that this is to be compacted more highly, so that this comprises other fibers or that this is coated.
The ultrathin batt section has, for example, a width of 1.5 m or less.
Furthermore, it is possible to form at least one or more ultrathin fiber batts with a batt structure from the ultrathin batt sections. A preferred embodiment of the invention therefore provides for at least one ultrathin fiber batt extending over the entire width of the fabric to be formed by a plurality of ultrathin batt sections adjoining one another in their width extent. It is thus possible to build up an ultrathin fiber batt of any desired width modularly by placing prefabricated batt sections laterally beside one another.
Because the ultrathin batt sections are so thin, moreover, no requirements are placed on the accuracy when the batt sections are placed laterally beside one another, for example during winding. Thus, because of the ultrathin formation of the batt sections, it is no problem for many applications if the batt sections overlap partly when they are placed laterally beside one another.
A plurality of such ultrathin fiber batts can then be joined flatly to one another in order to form at least one part of the batt structure. In this way, the batt structure can be built up simply and cost-effectively from the prefabricated ultrathin batt sections virtually in any desired thickness graduation and with virtually any desired properties in accordance with the customer requirements.
By using still thinner ultrathin batt sections, still finer thickness graduations of the batt structure can be achieved. Moreover, by means of such still thinner ultrathin batt sections, the property of the batt structure can be influenced locally without influencing the thickness of the remaining batt structure noticeably, for example with regard to the tendency to marking. It has proven to be advantageous if, in this connection, the ultrathin batt section has a thickness of 0.25 mm or less, preferably a thickness of 0.15 mm or less or a thickness of 0.1 mm or less, measured in accordance with EN ISO 5084.
If a 3 mm thick batt structure is built up from ultrathin fiber batts with a layer thickness of 0.15 mm, then this is formed of 20 ultrathin fiber batts arranged above one another. From this, the potential of the flexible possible configuration for the adaptation of the papermachine fabric to the customer-specific requirements by the use of the ultrathin fiber batts emerges directly if these are compared with fiber batts according to the prior art, which have thicknesses of 1 mm or more.
The fibers which are suitable for an ultrathin batt section have a titer in the range from 1 to 150 dtex which, for example in the case of polyamide 6 (PA6), corresponds to a filament diameter in the range between 0.0106 mm and 0.1296 mm.
The fibers of the ultrathin batt section comprise, for example, mineral and/or leonic fibers, such as rock fibers, glass fibers, metal fibers, and/or fibers made of polymer materials, such as polyamide, polypropylene, polyester, ethyl vinyl acetate, polyethylene, polyurethane and their modifications, and/or cellulosic fibers, such as viscose, acetate or mixtures of the same.
For the purpose of further individual influencing of the property profile along the width extent of the papermachine fabric according to the invention, it is also possible for the batt structure to comprise a plurality of ultrathin batt sections which do not adjoin one another in their width extent arranged beside one another in one plane. This means that the batt structure can have a plurality of ultrathin batt sections which do not adjoin one another in a specific plane over its width. This is the case, for example, when an ultrathin fiber batt is in each case arranged only in the two edge regions of the batt structure.
Of course, the ultrathin fiber batt can also be built up from ultrathin batt sections which differ in their properties in order to create a property profile that is locally different in the width of the fabric. A preferred refinement of the invention accordingly provides for the ultrathin fiber batt to have at least one ultrathin batt section which differs in at least one property from the remaining ultrathin batt sections of the ultrathin fiber batt. For example, the following properties are suitable: permeability, liquid storage volume, compressibility, density.
In this case, it is both possible for the ultrathin batt sections of an ultrathin fiber batt to have the same thickness or for at least one of the ultrathin batt sections of the ultrathin fiber batt to have a different thickness than the remaining ultrathin batt sections of the ultrathin fiber batt. In the last-named case, it is also conceivable for a plurality of ultrathin batt sections to be arranged above one another and jointly to have a height which corresponds to the height of the adjacent ultrathin batt sections of the same ultrathin fiber batt adjacent to the former. In this way, it is possible to form an ultrathin fiber batt having a uniform height.
In order to set different properties over its width in the ultrathin fiber batt, it is also conceivable for at least one of the ultrathin batt sections of the ultrathin fiber batt to comprise fibers with a different titer than the remaining ultrathin batt sections of the ultrathin fiber batt.
If the batt structure has a plurality of ultrathin fiber batts, the property profile over the width of the papermachine fabric can further be set individually by at least one ultrathin batt section of an ultrathin fiber batt differing in at least one of the following properties from an ultrathin batt section of another ultrathin fiber batt. For example, the following properties are suitable: permeability, liquid storage volume, compressibility, density.
The ultrathin fiber batts are preferably joined to one another with one of the following methods, on their own or in combination: mechanical joining methods such as needling, chemical joining methods such as adhesive bonding, fusing, chemical cross-linking. In this connection, it is for example conceivable for what are known as hot-melt fibers which have a lower melting point than the remaining fibers of the fiber batt to be incorporated in ultrathin fiber batts to be joined to one another. In order to join the fiber batts, the fiber batts are subjected to the action of heat in order to melt the hot-melt fibers or, in the case of the lower melting-point sheaths, their sheaths, and thus to fuse the ultrathin fiber batts at least partly to one another.
In order to provide adequate dimensional stability of the papermachine fabric according to the invention, it is necessary for the latter to comprise a carrier structure which is joined directly or indirectly to at least one of the ultrathin fiber batts.
In this case, the carrier structure can be arranged on one side with the batt strontium or within the batt structure. According to a further refinement of the invention, provision is made for at least part of the carrier structure to be arranged between two of the ultrathin fiber batts. The carrier structure preferably comprises an ultrathin carrier layer with a thickness of 0.3 mm or less, the ultrathin carrier layer being able to comprise, on their own or in combination: a permeable or semipermeable or impermeable film, a two-dimensional textile structure such as a woven fabric or a fine woven fabric, a film structure, a warp knit.
In practical terms, therefore, a semipermeable film which is joined two-dimensionally to the ultrathin fiber batts can therefore be arranged, for example, at least partly between two ultrathin fiber batts.
Suitable films are, for example, a film marketed by DuPont under the trademark Mylar.
The fine woven fabric is preferably one having 50 or more warp and/or weft threads per cm. The woven fabric is a woven structure known from the papermachine fabric sector.
If the batt structure has a plurality of ultrathin fiber batts, then it is both possible for the batt sections of different layers to extend parallel to one another or for the batt sections of different layers to extend crossed in relation to one another. In the first-named case, the ultrathin fiber batts can be produced by spiral winding of one or more ultrathin batt strips which, in the wound state, form the various batt sections extending over a part width of the fabric and adjoining one another in their width extent. In the second-named case, the ultrathin batt strip layers can be wound layer by layer crossing one another.
Depending on the configuration of the batt structure, the papermachine fabric according to the invention can be a forming fabric or press felt or a dryer fabric or a transfer belt.
These and other features and advantages of this invention are described in or are apparent from the following detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the present inventions is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:
FIG. 1 shows a cross section of the first embodiment of a fabric according to the invention,
FIG. 2 shows a cross section of the second embodiment of a fabric according to the invention,
FIG. 3 shows a cross section of the third embodiment of a fabric according to the invention, and
FIG. 4 shows in plan view two ultrathin fiber batts arranged one above the other, which form part of the batt structure of a fabric according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.
FIG. 1 shows in cross-section over its entire width a first embodiment of a papermachine fabric according to the invention, formed as a dryer fabric 1.
The dryer fabric 1 has a carrier structure 2 which is formed by a perforated film 2 having openings 3. In the FIG. 1, above the perforated film, there is arranged a first ultrathin fiber batt 4, which is formed by ultrathin batt sections 5 a, 5 b, 6 a, 6 b and 7 a, 7 b.
The batt sections 6 a and 7 a and the batt sections 6 b and 7 b are in each case arranged flatly on one another and form a first laminate 8 a and a second laminate 8 b. The two laminates 8 a and 8 b are in each case arranged in the edge region 11 a and 11 b of the dryer fabric 1, the ultrathin batt sections 5 a and 5 b being arranged in the central region of the dryer fabric 1.
In order to form the ultrathin fiber batt 4 extending over the entire width of the fabric 1, the fiber batts 5 a and 5 b and the first and the second laminate 8 a, 8 b are arranged adjoining one another in their width extent. In FIG. 1, above the first ultrathin fiber batt 4, there is arranged a second ultrathin fiber batt 9, which is joined flatly to the first ultrathin fiber batt 4.
The second ultrathin fiber batt 9 extends over the entire width of the dryer fabric 1 and is formed by a plurality of ultrathin batt sections 10 a to 10 e adjoining one another in their width extent.
The first ultrathin fiber batt 4 has a thickness of 0.2 mm, the batt sections 6 a, 6 b, 7 a, 7 b in each case having a thickness of 0.1 mm and the batt sections 5 a, 5 b having a thickness of 0.2 mm. Accordingly, the ultrathin batt sections 6 a, 6 b, 7 a, 7 b of the ultrathin fiber batt 4 have a different thickness than the ultrathin batt sections 5 a, 5 b.
The second ultrathin fiber batt 9 has a thickness of 0.1 mm.
In the ultrathin fiber batt 4, the ultrathin batt sections 6 a and 6 b have a permeability that is reduced as compared with the batt sections 7 a, 7 b, 5 a, 5 b, in order to prevent fluttering of the edges in the edge regions 11 a and 11 b of a paper web carried on the dryer fabric 1. Furthermore, the ultrathin batt sections 7 a, 7 b have a thermal conductivity that is increased as compared with the ultrathin batt sections 5 a, 5 b, 6 a, 6 b, in order to prevent excessive heating and damage resulting therefrom of the non-web-carrying edge regions 11 a and 11 b of the dryer fabric 1.
The batt sections 6 a and 6 b are coated with a polymer coating in order to achieve the lower permeability, the batt sections 7 a and 7 b comprising metal fibers.
FIG. 2 shows in a cross section over its entire width a second embodiment of a paper machine fabric according to the invention, formed as a press felt 13.
The press felt 13 has a carrier structure 14 which is formed by a woven fabric 14 known in the papermachine fabric sector. Furthermore, the press felt 13 has a batt structure 21.
The batt structure 21 has conventional fiber batts 15 and 16 which, in FIG. 2, are arranged above and below the woven fabric 14 and are joined flatly to the latter.
Furthermore, the batt structure 21 has conventional fiber batts 19 and 20 and ultrathin batt sections 18 a and 18 b according to the invention. The ultrathin batt sections 18 a, 18 b are in each case arranged in one of the edge regions 17 a and 17 b of the press felt 13, between the fiber batts 16 and 19.
The two ultrathin batt sections 18 a, 18 b each have a thickness of 0.1 mm, whereas the conventional fiber batts 16 and 19 have thicknesses in the range from 1.2 mm to 1.8 mm with thickness fluctuations of +/−0.1 mm, so that, as a result, the two batt sections 18 a, 18 b have no detrimental effect on the planarity of the paper-side surface 22 of the press felt 13.
The two ultrathin batt sections 18 a, 18 b have a reduced permeability, so that, as a result, the permeability and thus the dewatering performance of the press felt 13 is reduced in its two edge regions 17 a and 17 b as compared with the region in which the batt sections 18 a, 18 b do not extend. In this way, an increased dewatering pressure prevailing in the edge regions 17 a, 17 b in the press nip can be compensated for in order to effect more uniform dewatering over the width of the press felt 13.
FIG. 3 shows in a cross section over its entire width a third embodiment of a paper machine fabric according to the invention, formed as a press felt 24.
The press felt 24 has a carrier structure 25 which is formed by a laid scrim having filaments 27 extending in the machine direction. In FIG. 3, above the carrier structure 25, there is arranged a batt structure 26 which is joined flatly to the carrier structure 25.
The batt structure 26 has ultrathin fiber batts 28, 29, 30, 31 and 32 which are ranged above one another flatly from bottom to top in FIG. 3.
In the two edge regions 33 a and 33 b of the press felt 24, ultrathin batt sections 35 a and 35 b are, moreover, arranged between the two ultra thin fiber batts 30 and 31. Furthermore, two ultrathin batt sections 36 a and 36 b adjoining one another in their width extent are arranged in the central region 34 between the two fiber batts 31 and 32.
Each of the ultrathin fiber batts 28, 29, 30, 31 and 32 is formed by a plurality of ultrathin batt sections adjoining one another in their width extent, which are not designated individually in the following text for reasons of clarity.
The fiber batts 28 to 30 are constructed identically and comprise fibers having a titer in the range of more than 60 dtex. The fiber batts 28 to 30 together constitute the equivalent of a conventional fiber batt having a thickness of about 1 mm thickness, only with the difference that, according to the invention, the fiber batts 28 to 30 are formed from prefabricated batt sections having a thickness of 0.3 mm in each case. Of course, far more fiber batts can be joined flatly to one another, in accordance with the customer-specific or application-based requirements.
The upper side of the ultrathin fiber batt 32 forms the paper side 37 of the press felt 24 in the embodiment shown in FIG. 3. The ultrathin fiber batt 32 is formed by fibers with a titer of 6 dtex or less and has a thickness of 0.1 mm.
In order to influence the dewatering performance, the ultrathin batt sections 35 a and 35 b are arranged in the edge regions 33 a and 33 b of the press felt 24, in between the ultrathin fiber batts 30 and 31, in each case in the area of the edge regions 33 a and 33 b. Accordingly, the batt structure comprises a plurality of ultrathin batt sections 35 a, 35 b which do not adjoin one another in their width extent arranged beside one another in one plane.
Furthermore, in order to reduce the rewetting in the central region 34 of the press felt 24 between the ultrathin fiber batts 31 and 32, the two ultrathin batt sections 36 a and 36 b are arranged beside each other, these extending just over the width of the press felt 24 in which the two ultrathin batt sections 35 a, 35 b do not extend.
The batt sections 36 a, 36 b, 35 a, 35 b have a thickness of 0.1 mm.
FIG. 4 shows in plan view two ultrathin fiber batts 39 and 40 which are arranged one above the other and which form part of a batt structure 38 according to the invention.
The two fiber batts 39 and 40 are produced by winding a batt strip over two rollers 41 and 42 spaced apart from each other, the first fiber batt 39 being formed by a plurality of ultrathin batt sections 43 a to 43 c adjoining one another in their width extent and running parallel to one another which, in the illustration of FIG. 4, extend from the roller 41 to the roller 42, running from below.
Moreover, the second fiber batt 40 is formed by a plurality of ultrathin batt sections 44 a to 44 c adjoining one another in their width extent and running parallel to one another which, in the illustration of FIG. 4, extend from the roller 41 to the roller 42 running from above, so that the batt sections 43 a to 43 c, 44 a to 44 c of the different ultrathin fiber batts 39 and 40 run crossed in relation to one another.
At a later time in the production, the finished batt structure 38 is cut out of the wound ultrathin fiber batts 39, 40 along the section lines A-A and B-B. According to the invention, the batt structure 38 comprises a plurality of ultrathin elongated batt sections 43 a to 43 c and 44 a to 44 c, which in each case extend only over a part width of the batt structure 38 and have a thickness of 0.3 mm or less.
While the present invention has been particularly shown and described with reference to the foregoing preferred embodiments, those skilled in the art will understand that many variations may be made therein without departing from the spirit and scope of the invention as defined in the following claims. This description of the invention should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements. The foregoing embodiments are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application. Where the claims recite “a” or “a first” element or the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.

Claims

1. A papermachine fabric comprising:

a batt structure,

wherein the batt structure comprises at least one ultrathin elongated batt section that extends over part of a width of the fabric, the ultrathin batt structure having a thickness of greater than 0 mm and less than approximately 0.3 mm.

2. The papermachine fabric of claim 1, wherein the thickness of the ultrathin batt section is greater than 0 mm and less that at least one of 0.25 mm, 0.15 mm and 0.1 mm.

3. The papermachine fabric of claim 1, wherein the ultrathin batt section comprises fibers with a titer in the range from approximately 1 to approximately 150 dtex.

4. The papermachine fabric of claim 1, wherein a plurality of ultrathin batt sections are adjoined in a width extent.

5. The papermachine fabric of claim 1, wherein a plurality of ultrathin batt sections are not adjoined in their width extent when arranged beside one another in one plane.

6. The papermachine fabric of claim 1, further comprising a second ultrathin batt section, wherein the at least one ultrathin fiber batt section differs from the second ultrathin batt section by at least one of permeability, liquid storage volume, compressibility and density.

7. The papermachine fabric of claim 6, wherein the at least one ultrathin batt section has the same thickness as the second ultrathin batt section.

8. The papermachine fabric of claim 6, wherein the at least one ultrathin batt section has a different thickness than the second ultrathin batt section.

9. The papermachine fabric of claim 1, wherein a first ultrathin batt section comprises fibers with a different titer than a second ultrathin batt section.

10. The papermachine fabric of claim 1, wherein the batt structure comprises a plurality of ultrathin fiber batts which are arranged flatly on one another.

11. The papermachine fabric of claim 10, wherein the ultrathin fiber batts are joined flatly to one another.

12. The papermachine fabric of claim 10, wherein the ultrathin fiber batts are joined to one another by at least one of adhesive bonding, fusing and cross-linking.

13. The papermachine fabric of claim 1, wherein the fabric comprises a carrier structure which is joined to at least one of the ultrathin fiber batts.

14. The papermachine fabric of claim 13, wherein a first part of the carrier structure is arranged between a first ultrathin fiber batt and a second ultrathin fiber batt.

15. The papermachine fabric of claim 14, wherein the carrier structure is joined flatly on both sides to the first and second ultrathin fiber batts.

16. The papermachine fabric of claim 13, wherein the carrier structure comprises an ultrathin carrier layer with a thickness of 0.3 mm or less.

17. The papermachine fabric of claim 16, wherein the ultrathin carrier layer comprises at least one of a permeable film, a semipermeable film, an impermeable film, a two-dimensional textile structure such as a woven fabric or a fine woven fabric, a film structure, and a warp knit.

18. The papermachine fabric of claim 10, wherein the batt sections of different ultrathin fiber batts extend parallel to one another.

19. The papermachine fabric of claim 10, wherein the batt sections of different ultrathin fiber batts extend perpendicular in relation to one another.

20. The papermachine fabric of claim 1, wherein the papermachine fabric is one of a forming fabric, a press felt, a dryer fabric, and a transfer belt.