WO2015185278A1

WO2015185278A1 - Method for producing a paper machine cloth

Info

Publication number: WO2015185278A1
Application number: PCT/EP2015/059016
Authority: WO
Inventors: Michael Straub
Original assignee: Voith Patent Gmbh
Priority date: 2014-06-02
Filing date: 2015-04-27
Publication date: 2015-12-10

Abstract

The invention relates to a method for producing a cloth comprising a paper side and a diametrically opposed machine side, wherein the cloth is suitable for use in a machine processing and/or producing a fiber material web and comprises at least one polymer film and wherein the method comprises the following steps: a. provision of at least one polymer film comprising a length and width spanning a surface and a thickness extending perpendicularly thereto, b. punching multiple holes out of a section of the surface of at least one of the at least one polymer films in such a way that each of the holes penetrates the thickness of the polymer film and the holes in the surface of the polymer film are arranged adjacent to one another, and c. processing the at least one polymer film, if necessary using additional polymer films, in such a way that the polymer film is arranged in the clothing in such a way that the surface spanned by the length and width of the polymer film extends parallel to the paper- and machine sides of the cloth.

Description

Method for producing a paper machine clothing Technical field and state of the art

The invention relates to a method for producing a covering comprising at least one polymer film.

Currently and in the past, attempts have been and are made repeatedly to produce suitable coverings without textile processes for use in a machine producing and / or processing a fibrous web. The use of perforated or perforated polymer films is described again and again in this connection in order to produce a structure which is similarly open to a fabric. Such a structure must contain more than 10 million holes per square meter.

In order to produce the holes in the films, the use of laser radiation is proposed, for example, in EP 2391754 and in US4541895, by means of which the holes are drilled. The use of laser radiation has disadvantages in some respects, which have in the past contributed to the fact that this technology is used for the production of perforated films for the o.g. Application has not been enforced so far. To name in this context, for example, the high investment costs for a laser drilling device, the increased health risks for the operator by the laser radiation source and in particular the low productivity in generating the high number of holes.

Based on the aforementioned disadvantages, the object is therefore to propose a method for producing a covering, which is more cost-effective, more productive and safer than a method using laser drilling.

Presentation of the invention

The object is achieved by a method for producing a covering with a paper side and a machine side opposite thereto, wherein the covering is suitable for use in a machine producing and / or processing a fibrous web and has at least one polymer film and wherein the method comprises the following steps includes: a. Providing at least one polymer film having a surface spanning length and width and a thickness extending perpendicular thereto, b. Punching a plurality of holes from a portion of the surface of at least one of the at least one polymer film such that each of the holes penetrates the polymer film in thickness and the holes in the surface of the polymer film are juxtaposed, and

c. Processing the at least one polymer film optionally using further polymer films such that the polymer film is arranged in the fabric in such a way that the area of the polymer film spanned by the length and width runs parallel to the paper and machine side of the fabric.

The tools for punching are very simple and therefore inexpensive. In a punching method, for example, in a punching stroke a plurality of holes can be generated simultaneously or quasi-simultaneously. Therefore, such a punching process is much more productive than laser drilling. Furthermore, a punching process is purely mechanical and dispenses with a more dangerous in terms of occupational safety radiation source.

In particular, holes can be reproducibly formed by the punching process with a defined cross-sectional shape, since it is in punching in particular a shear cutting process. In this case, as the waste material for each hole, a so-called "punched slug" can be formed, whose area corresponds to the cross-sectional area of the punched hole.Preferably, the punching method is to be distinguished from a method in which the polymer foil is used to produce a hole with a pointed object, eg In such a process, no waste material is generated, but when the holes are punched, the material of the film is displaced, producing high craters on the film.

In the context of the present invention, a polymer film is to be understood as meaning a film which consists of 80% by weight or more of a polymer material and is impermeable to water in liquid form before punching. A film has a large extension in length and width compared to its height (length and width are at least 300 times greater than the height). The polymer film can be made by extrusion, casting or blow molding, with production by extrusion being the most used. The extruded polymer films are then often drawn in a subsequent process step. The polymer film can contain as further constituent, for example, filler in the form of fibers and / or particles.

Preferably, the covering comprises a load-absorbing basic structure whose upper side faces the paper side and the underside faces the machine side of the clothing, wherein preferably at step c) the at least one polymer film is optionally further processed to the basic structure using the further polymer films, that the basic structure has the length and width or substantially the length and width of the fabric and is either closed to an endless belt or endlessly closable to an endless belt and the polymer film is arranged in the basic structure such that the surface spanned by the length and width of the Polymer film runs parallel to the top and bottom of the basic structure.

The term "load-bearing basic structure" designates the functional unit of the clothing which is suitable for absorbing the substantial part, ie more than 50%, in particular more than 70%, of the tensile forces acting on the clothing in the machine direction and / or machine cross-straightening, ie the basic structure represents the dimensional stability The basic structure can, for example, in addition to the at least one polymer film, also comprise threads running in the machine direction and / or threads running in the machine direction, Furthermore, the basic structure can comprise a seam connection means, by means of which it can be made endless The basic structure thus takes over the task which is taken over in conventional sieves and felts, for example by a fabric.

The length of the base structure also extends in the direction of travel of the fabric in the machine, i. in the machine direction, as the width of the base structure transverse to the direction of travel of the fabric in the machine, i. extends into machine cross-fencing.

By the term "that the basic structure has substantially the length and width of the fabric" is to be understood that the basic structure has at least 90% of the length and at least 90% of the width of the fabric to be produced.

According to one embodiment of the method according to the invention, it is provided that step b) takes place before step c). In this case, the at least one polymer film or several polymer films are or are first provided with holes before they are further processed, for example, to the basic structure with final width, length and thickness. Alternatively, it is conceivable that step c) takes place before step b). In this case, for example, the basic structure with final width, length and thickness is processed before the holes are punched into the at least one film.

A preferred development of the method according to the invention provides that in step b) several holes are punched out simultaneously or quasi-simultaneously. The term "quasi-simultaneous" should be understood in the present case that several holes, in particular more than 10 holes, are generated within less than 1/10 second.

Preferably, in step b) at least 50 holes, preferably at least 150 holes, more preferably at least 250 holes simultaneously or quasi-simultaneously from the punched out at least one polymer film. This makes it possible, in particular, that more than 500 holes are punched out per second, in particular more than 2000 holes, as a result of which high productivity can be achieved.

Specifically, the punching of the holes can be done by means of a stamping device comprising a plurality of punches. The punching device in this case moves the plurality of punches in a plurality of punching strokes that follow one another at intervals, with the multiple punches simultaneously being moved during each punching stroke and driven into the at least one polymer foil by the thickness of the polymer foil.

The punching device may preferably comprise at least 50 punches, preferably at least 150 punches, more preferably 250 punches. Conceivable but also punching devices with 300 punches or more are moved simultaneously in a punching stroke.

Furthermore, it is conceivable that the punching out of the holes from the at least one polymer film in step b) is carried out successively at a plurality of juxtaposed sections of the surface of the at least one polymer film. If the punching with the stamping device comprising the plurality of punches, it is particularly conceivable in this context that when repeated step b), the plurality of adjacent surface sections are approached by the polymer film and the punching device are moved parallel to the surface relative to each other.

Specifically, it is conceivable that the juxtaposed surface portions of the film are provided with holes by the successive punching strokes are performed on the adjacent surface portions. This means that each of the adjacent surface sections is machined to produce holes with a single punch stroke. Here, first a first surface section is processed by a first punching stroke. Subsequently, the polymer film and the stamp are moved relative to each other in the plane spanned by the width and length of the film, that a second surface portion adjacent to the first surface portion can be processed with the punches by a second punching stroke.

Preferably, in addition to the punches, the punching device has a die comprising a plurality of recesses, wherein the number of recesses corresponds at least to the number of punches, and wherein during each punching stroke the punches are at least partially immersed in the recesses.

For use as a covering, it is particularly useful if the holes have a smallest cross-sectional area in the range of 0.0019 mm ² to 0.072 mm ² , in particular in the range of 0.005 mm ² to 0.0314 mm ² . The term "smallest cross-sectional area" is to be understood as meaning the open projection of the holes in the plane spanned by the length and width of the film.Furthermore, the holes can be punched out so that the smallest spacing of adjacent holes is 300 μm or less, preferably 200 μm or less, more preferably δθμηη or less.

Preferably, the holes are punched out such that the at least one polymer film has an open area caused by the holes of at least 25%, preferably at least 30% and optionally at most 80%, preferably at most 70%. This makes it possible, for example, to provide a basic structure which on the one hand provides sufficient drainage behavior and on the other hand provides sufficient stability. The "open area" here is the quotient of the area of all open projections of the holes that completely penetrate the basic structure in their thickness to the total area of the basic structure.

The cross-sectional area of the holes may, for example, be circular or oval or polygonal. To increase the tensile strength of the basic structure in the machine direction, it may be useful if the longer axis of the oval holes is oriented in the longitudinal direction of the fabric to be produced. To provide an improved formation when using the fabric as a forming fabric, it may be useful if the longer axis of the oval holes is oriented in the transverse direction of the fabric to be produced.

There are different possibilities conceivable how the basic structure can be built up.

For the production of the covering or basic structure in its width, the following is conceivable.

The width of the at least one polymer film may be less than the width of the fabric or basic structure to be produced. In this case, the at least one polymer film can be provided, for example, as an already perforated polymer film in the form of a roll, which is then further processed in step c).

In this case, several possibilities are conceivable.

Thus, a plurality of polymer films with a width smaller than the width of the fabric or basic structure to be produced can be provided, of which at least some in the direction of the width of the fabric or basic structure to be produced are arranged next to one another in step c). It is conceivable, in particular, for each of the plurality of polymer films to be arranged next to one another to be closed into an endless belt, before the adjacent polymer films are joined together in the region of their longitudinal edges. Alternatively, it is conceivable that the adjacent polymer films are first in the range their longitudinal edges are joined together before this film assembly of several juxtaposed polymer films is then closed an endless belt.

Alternatively, a polymer film with a width smaller than the width of the fabric or basic structure to be produced can be provided, which is helically wound progressively in step (c) in the direction of the width of the fabric to be produced.

The polymer films or sections of the polymer film arranged side by side in step c) in the region of the longitudinal edges can hereby be arranged butt-jointed or overlapping one another in sections and connected to one another.

Alternatively, it is conceivable that a polymer film is provided whose length corresponds to the length or substantially the length of the substrate and whose width corresponds to the width or substantially the width of the substrate.

The following is conceivable for producing the covering or basic structure in its thickness.

It is possible to provide a plurality of polymer films which, in step c), are connected to one another in an overlapping manner at least in sections, overlapping one another. In this way, the covering or basic structure can comprise or provide a layer structure which comprises a plurality of polymer films arranged one above the other which are connected to one another in a planar manner.

Preferably, at least one, in particular all, of the at least one polymer film contains PET, PA, PPS, PEN, PEEK. Furthermore, the at least one polymer film preferably has a thickness in the range of 150μηΊ to 1600μη "ΐ, preferably 300μηΊ to 1200μη" ΐ, more preferably δθθμηη to δθθμηη. The at least one polymer film can be unidirectionally or bidirectionally stretched to increase the tensile strength.

Preferably, a tension is provided by the method according to the invention, which is formed by the load-bearing basic structure. This means that the fabric has, for example, no fiber fleece structure and / or foam structure which is arranged on the top and / or bottom of the basic structure. Such a covering may, for example, be a forming fabric or a drying fabric for a paper, board or tissue machine.

The invention will be further explained with reference to schematic, not to scale drawings. Show it 1 shows a schematic representation of a preferred embodiment of the punching method according to the invention,

Figure 2 shows a first embodiment of the method according to the invention and

FIG. 3 shows a second embodiment of the method according to the invention

Figures 1 a) and 1 b) show two basic representations of preferred embodiments of the punching step of the method according to the invention. FIG. 1 c) shows a section of the surface F of the polymer film 1 spanned by the length and width of the polymer film 1 in plan view.

From the provided polymer film 1, a plurality of holes 2 are punched out of a section of the area F spanned by the length and width of the polymer film such that each of the holes 2 penetrates the polymer film 1 in its thickness D and the holes 2 in the surface F of the polymer film 1 are arranged side by side, as can be seen from the figure 1 c).

In the two embodiments shown in FIGS. 1 a) and 1 b), a plurality of holes is punched out using a punching device 3 comprising a plurality of punches 4 and a die 5, wherein the die 5 has a plurality of recesses 6, the number of which is at least equal to the number of punches 4 equivalent. The punching of the holes 2 takes place in several punching strokes (in FIGS. 1 a) and 1 b) indicated by the double arrow, wherein the punch 4 moves simultaneously with each stamping stroke and into the at least one polymer film 1 in the direction of the thickness D of the polymer film are driven. The waste material produced during the punching of the holes 2, the so-called punched slugs 7, can be conveyed downwards out of the die 5.

The punching step (step b)) is carried out successively at a plurality of sections lying adjacent to one another in the surface F of the at least one polymer film 1. For this purpose, the plurality of adjacent surface sections are approached by the polymer film and the punching device in the surface F are moved relative to each other.

The punching device 3 shown in FIG. 1 a) has a plurality of punches 4 of equal length, whereby several holes 2 are punched out simultaneously during each punching stroke, since the punches 4 penetrate into the polymer film 1 at the same time. The punching device of FIG. 1 b) differs from the punching device of FIG. 1 a) in that the punches 4 have different lengths. As a result, the plurality of holes are punched quasi-simultaneously in a punching stroke, since the punch 4 are moved simultaneously in a punching stroke, but temporally offset in succession in the polymer film 1 penetrate. Through the punching device 3 shown in Figure 1 b) a "gentle" punching can be achieved. Although FIG. 1 does not explicitly show this, the punching device 3 can have more than 250 punches 4, which are moved simultaneously during a punching stroke and driven into the polymer film 1.

As a result, production speeds are possible in which more than 500 holes are punched out per second.

FIG. 2 shows a first embodiment of the method according to the invention. For this purpose, one or more rolls of non-perforated polymer film (s) 1 are provided which are perforated in a process step (FIG. 2a) by punching out holes 2 with a punching device 3. After the production of the holes 2, the film is made up to the necessary for the further production of a basic structure 8 length.

It should be noted that the transport direction of the polymer films in Figures 2a) and 2b) and 3a) and 3b) is from left to right as indicated by the arrow.

The basic structure 8 is now produced using a plurality of perforated polymer films 1 a, 1 b and 1 c, 1 a ^' , 1 b ^' and 1 c ^' , and 1 a ^" , 1 b ^" and 1 c ^" 1 a, 1 b and 1 c, 1 a ^' , 1 b ^' and 1 c ^' , and 1 a ^" , 1 b ^" and 1 c ^" is less than the width of the base structure to be produced 8th

In the further processing of the perforated polymer films 1 a, 1 b and 1 c, 1 a ^' , 1 b ^' and 1 c ^' , and 1 a ^" , 1 b ^" and 1 c ^" these are for each position to be produced of the basic structure in the direction of For example, a first layer is produced by juxtaposing the polymer films 1 a, 1 a ^' and 1 a ^" in the direction of the width of the basic structure to be produced. The next, ie the second, layer is produced in the same way, wherein the polymer films 1 b, 1 b ^' and 1 b ^"of the second layer in the width direction of the base structure to be produced offset from the polymer films 1 a, 1 a ^' and 1 a ^" The first layer are arranged so that the impact-to-joint longitudinal edges L1 of the polymer films 1 a, 1 a ^' and 1 a ^{" of} the first layer between the shock-to-joint longitudinal edges L2 of the polymer films 1 b, 1 b ^' and 1 b ^"of the second layer are arranged and vice versa. This structure continues analogously with the third layer and possibly further layers.

The connection of the layers of polymer films 1 a, 1 b and 1 c, 1 a ^' , 1 b ^' and 1 c ^' , and 1 a ^" , 1 b ^" and 1 c ^" takes place here by a lamination process in which the individual layers by means Radiation exposure by a radiation source 9, for example. By laser radiation, melted on and immediately thereafter by force in a by two rollers 10, 1 1 formed nip in still molten state to be compressed. For further completion of the basic structure, the laminated polymer film arrangement 12 obtained in this way is provided with a seam connection element 13, by means of which the basic structure 8, whose length and width now correspond to the length and width of the fabric, can be endlessly closed to form an endless belt.

In the present case, the fabric to be produced is formed by the basic structure and a forming fabric or dryer fabric for a paper, board or tissue machine. The basic structure 8 is presently formed by the laminated polymer film arrangement 12 and the seam connection element 13.

Figures 2c) and d) show the finished, guided around rollers 14, 15 and endless closed fabric in side view (Figure 2c) and in plan view (Figure 2d).

FIG. 3 shows a further embodiment of the method according to the invention. In the embodiment shown in FIG. 3, a plurality of polymer films 1 a, 1 b and 1 c which are in roll form and which have a smaller width than the fabric and base structure 12 to be produced are laminated onto one another. As in the example of FIG. 2, the lamination process (FIG. 3 a) takes place by the action of laser energy by means of a radiation source 9 and immediately following force in a nip formed by two rollers 10, 11, when the polymer films 1 a, 1 b, 1 c are still in a molten state. Alternatively, in the present embodiment and in the case of FIG. 2, gluing by means of an adhesive could also take place instead of a radiation source.

The laminated film assembly 12 obtained by the lamination process is perforated in the punching step shown in FIG. 3b by punching holes 2 with a punching device 3.

In the subsequent process step shown in FIG. 3c, the laminated film arrangement 12, which has a width smaller than the width of the basic structure to be produced, is helically wound around two spaced-apart rolls 14, 15 in the direction of the width of the base structure 8 to be produced. As a result, a present as an endless belt basic structure 8 is generated. The base structure 8 is presently formed by the laminated and helically wound polymer film assembly 12.

In the exemplary embodiments shown, at least one, in particular all, of the polymer films may contain or be formed from the polymer material PET, PA, PPS, PEN, PEEK. Furthermore, the polymer films may have a thickness in the range of 150μηι to 1600μη-ι, preferably 300μηΊ to 1200μη-ι, more preferably δθθμηη to δθθμηη and be unidirectional or bidirectionally stretched. Furthermore, the holes can have a Cross-sectional area in the range of 0.0019 mm ² to 0.072 mm ² , in particular in the range of 0.005 mm ² to 0.0314 mm ² have.

Claims

claims

1 . A method of making a fabric having a paper side and a machine side thereof, the fabric being suitable for use in a machine producing and / or processing a fibrous web and comprising at least one polymer film, the method comprising the steps of:

a. Providing at least one polymer film having a surface spanning length and width and a thickness extending perpendicular thereto,

b. Punching a plurality of holes from a portion of the surface of at least one of the at least one polymer film such that each of the holes penetrates the polymer film in thickness and the holes in the surface of the polymer film are juxtaposed, and

c. Processing the at least one polymer film optionally using further polymer films such that the polymer film is arranged in the fabric in such a way that the area of the polymer film spanned by the length and width extends parallel to the paper and machine side of the fabric.

2. The method according to claim 1, characterized in that the covering comprises a load-absorbing basic structure, the upper side facing the paper side and the underside facing the machine side of the fabric, wherein at step c) the at least one polymer film optionally using at least the further polymer films in such Basic structure is further processed, that the basic structure has the length and width or substantially the length and width of the fabric and either closed to an endless belt or endlessly closable to an endless belt and the polymer film is arranged in the basic structure such that by the length and Width spanned surface of the polymer film runs parallel to the top and bottom of the basic structure.

3. The method according to claim 1 or 2, characterized in that step b) takes place before step c) or that step c) takes place before step b).

4. The method according to any one of the preceding claims, characterized in that at step b) several holes are punched simultaneously or quasi-simultaneously.

5. The method according to any one of the preceding claims, characterized in that at step b) at least 50 holes, preferably at least 150 holes, particularly preferred at least 250 holes are punched out of the at least one polymer film simultaneously or quasi-simultaneously.

6. The method according to any one of the preceding claims, characterized in that step b) successively carried out at a plurality of adjacent surface portions of the at least one polymer film.

7. The method according to any one of the preceding claims, characterized in that the punching of the holes in a plurality of successive punching strokes by means of several punches, wherein at each punching stroke, the plurality of punches simultaneously moved and are driven into the at least one polymer film.

8. The method according to claim 7, characterized in that the punching of the holes by means of a plurality of punches and optionally a die comprehensive stamping device is carried out, wherein the die comprises a plurality of recesses, the number of which corresponds at least to the number of punches, in each punching stroke Immerse the stamp at least in sections.

9. The method according to any one of the preceding claims 6 to 8, characterized in that when repeated step b), the plurality of adjacent surface portions are approached by the polymer film and the punching device are moved relative to each other.

10. The method according to any one of the preceding claims, characterized in that the holes have a cross-sectional area in the range of 0.0019 mm ² to 0.072 mm ² , in particular in the range of 0.005 mm ² to 0.0314 mm ² have.

1 1. Method according to one of the preceding claims, characterized in that the width of the at least one polymer film is less than the width of the fabric or base structure to be produced.

12. The method according to any one of the preceding claims, characterized in that a plurality of polymer films are provided with a width smaller than the width of the fabric or base structure to be produced, of which at least some in the direction of the width of the basic structure to be produced are arranged side by side in step c).

13. The method according to any one of the preceding claims, characterized in that a polymer film with a smaller width than the width of the fabric to be produced or basic structure is helically wound progressively in step c) in the direction of the width of the basic structure to be produced.

14. The method according to any one of the preceding claims, characterized in that a polymer film is provided whose length corresponds to the length or substantially the length of the fabric or base structure to be produced and whose width corresponds to the width or substantially the width of the fabric or base structure to be produced.

15. The method according to any one of the preceding claims, characterized in that a plurality of polymer films are provided which are interconnected at least in sections overlapping each other in step c) with each other.