EP1359251B1 - Dryer fabric and method for its production - Google Patents

Abstract

During a paper making process, a paper web is de-watered by a porous de-watering web consisting of longitudinal (2, 3) and transverse (5, 6, 7, 8) strips. Longitudinal and transverse strips are each made of a different type of fibre, and are joined at their crossover points (8, 16, 17) esp. by local application (9) of a hotmelt bonding agent. Also claimed is a process for making the de-watering web in which the crossover joins are further strengthened by a form-fit union in which each strip incorporates a shallow groove with a thread which is transverse to the adjacent thread. The union is effected by insertion of a single pin through the two strips.

Description

The invention relates to a dryer fabric for the dryer section a paper machine, with a scrim from at least one layer of longitudinal threads and at least one layer the longitudinal threads crossing transverse threads, wherein the longitudinal and transverse threads at crossing points due to heating Melting temperature are fused together.

Such a dryer fabric with a scrim is as a Variant disclosed in WO 98/12370. So that the Trokkensieb has stability at all, are the longitudinal and Cross threads at the crossing points by heating each other merged. So that the threads in the merger process do not completely melt, are bicomponent threads with a thread core and a thread core surrounding thread coat used, the thread core a higher melting temperature than the thread sheath. The Fusion then takes place by heating to a temperature above the melting point of the suture sheath and below the melting point of the thread core.

Since bicomponent yarns are expensive, the cost is one Such Trockensiebes very high. In addition, you can Such bicomponent threads in terms of their material properties not always optimal on the conditions in adjust the dryer section.

In addition, paper machine clothing is known, e.g. from EP-A-0 947 623, which is known as Basis have a textile web and their special feature consist in that the textile web of several together lying, extending in the running direction partial webs is composed, which at their web edges welded together. The textile web or their Partial webs in the exemplary embodiment consist of yarn layers, consisting of longitudinal and transverse threads and on their crossing points, for example by welding, Bonding or the like are connected. To the individual Partial paths to connect with each other, is about the Thread sections that survive at the edges of the partial webs and overlap with each other, a connecting thread placed and welded to the thread sections. this happens by means of an ultrasonic welding device, the the connecting thread heated so much that he plasticized and adheres or adheres to the thread sections. Subsequently, the partial webs with a fiber fleece occupied and this needled with the thread scratches.

The invention is based on the object, a drying wire of the aforementioned type so that there is a has high dimensional stability and yet inexpensive is to produce. A second task is to provide a method for its production.

This object is achieved in that the longitudinal and transverse threads are Einkomponentenfäden and as Flat threads are formed and that the longitudinal and transverse threads with each other and / or with these connecting parts due to heating limited to the crossing points are merged. The basic idea of the invention is thus the longitudinal and transverse threads only at the crossing points, where they are to be connected together, to melting temperature to heat and so make the fuse. The temperature of the remaining areas of the threads stays below the melting point of the thread material. So it does not undergo structural and shape changes, so that Overall, the given by the juxtaposition of the layers Thread structure is preserved. This makes it possible the bicomponent threads used in the generic dryer fabric to replace by monocomponent threads, whereby the dryer fabric produced much cheaper can be without any disadvantages in terms of Dimensional stability must be taken into account.

Single-component threads are to be understood as meaning such threads which consist homogeneously of a single material, wherein the material may also be a copolymer, provided only homogeneity is given. Here are under Einkomponentenfäden in the context of the present invention also such To understand threads of the aforementioned type, with a Arming, in particular fiber reinforcement, provided are.

Compared with fabrics and knitted fabrics has the invention Drying screen the advantage of high flexibility in terms of Number of layers, thread density and choice of material. In addition, for the production of no consuming Textile machines, such as weaving and knitting machines, required, in addition, the width of the produce on them Drying screen limited. Such a limitation exists if there are threads, i. They can be practical be made of any width. In addition, can if there are threads on the necessary heat setting on fabrics be waived if the threads previously sufficient have been thermally treated.

A provisional fixation can be achieved, if the longitudinal and transverse threads at crossing points in addition be positively connected with each other. The connection can each consist of a recess in the one thread and a protrusion bordering on it consist of crossing thread. But it can also be formed by it be that the threads at the crossing points with each other have aligned recesses, by a Pen, e.g. a round bolt or a rivet made of plastic or metal, interspersed. Such a positive Connection also supports the fusion bond between the threads or the recesses and projections or pins and makes for even better ones Bracing at the crossing points.

It is particularly preferred, the longitudinal and transverse threads as Form flat threads with rectangular cross section. On This way, a surface contact is created at the crossing points and the area over which the threads are connected fused, is considerably enlarged and thus firmer. As appropriate width for the longitudinal and transverse threads has a range of 2 to 20 mm, preferably 8 to 12 mm, proved. The thickness should be between 0.3 to 2 mm, preferably 0.6 to 1.2 mm, wherein the transverse threads should have at most the same thickness as the longitudinal threads.

In particular for very wide flat threads sufficient Permeability to ensure water or steam Through holes in the longitudinal and / or transverse threads are provided. By their size and number, the permeability can be controlled arbitrarily, where there is also the possibility of permeability over the width of the dryer to different shape, e.g. higher in the middle than in the border areas or the other way around. The through holes can as be formed round holes or elongated slots.

The dryer fabric according to the invention can be any number of layers, each having one layer alternate with longitudinal threads and a layer with transverse threads, So each adjacent to each other. A functional one Number are two or three layers, in the former case preferably a lower longitudinal thread lay with an upper Querfadengelege is combined and in the latter case a Position with transverse threads on both sides of one layer of longitudinal threads is included. In this way is at upper and Bottom formed a longitudinal structure. Of course there is the possibility to proceed in reverse, so that at the top and bottom by the existing there Transverse threads is a transverse structure.

The permeability or permeability of the dryer fabric can also be, for example, by the width dimensions the longitudinal and / or transverse threads and / or their thread density set in wide limits. It also exists the possibility of longitudinal threads in at least one layer to arrange them in the middle area another Have thread density than in the peripheral areas, in particular in the middle area a lower than in the border areas.

With the thread scrim according to the invention can also be In a simple way eyelets on the front sides of the dryer by turning over longitudinal threads to form Make loops with them to a wire seam form. This can be done in such a way that tails of longitudinal threads of a first layer on the end faces of Dry sieve forming loops on this Layer turned away side of the situation with transverse threads and at several of these transverse threads, preferably at least five transverse threads, to be fastened. The attachment However, it can also be done on the longitudinal threads themselves become. The fixation can in both cases positive fit, e.g. using bolts or rivets made of plastic or Metal, done.

The loop formation should expediently only with one Part of the longitudinal threads are carried out so that the both end edges with their loops comb-like into each other grab and so a passageway for a pintle can form. Preferably, at least alternately an end piece turned over to form a loop his and at least a tail without education a loop at the last cross thread edge end. In order to the permeability in this area does not deteriorate is, should be at the ends of the end pieces longitudinal threads from in the situation with transverse threads adjacent second layer connect with longitudinal threads, i. these longitudinal threads abut dull on the end pieces, so do not overlap with them, so that there is no compression in this area comes from longitudinal threads.

As far as the material of the threads is concerned, basically no restrictions if the material is meltable and shows thermoplastic behavior. In question For example, PET, PA come in all modifications, PPS, PEK, PEKK, elastic polyester, PBT or PTT or Combinations thereof. The threads can also be reinforced, e.g. with fibers such as glass fibers, carbon fibers, ceramic fibers, the fibers also being short cut fibers may be present.

As dryer fabric are mainly training in question, where the dryer fabric consists of the scrim, which does not exclude that the scrim with others Components is combined, for example, a nonwoven fabric.

For the preparation of the above drying fabrics is According to the invention, a method proposed in which the Longitudinal and transverse threads by limited to the crossing points Heating to melting temperature with each other or fused with fasteners, wherein the heating by means of laser, high frequency and / or induction energy he follows. There are two alternatives Procedures are used with which the heating up the crossing points can be concentrated. On the one hand the energy can be selectively, i. limited in space the crossing points are applied, including in particular Lasers are suitable because of their focused laser beam. Alternatively, however, the energy can also be flat Applied over several to be merged crossing points be, for example, across the entire width and a certain length of the dryer fabric when the crossing points previously with a the absorption of energy promotional additives are provided. Because of this Additive concentrates the energy intake despite flat application to the crossing points, so that only heat them to melting temperature and therefore together merge. The planar application of energy is easier to implement in terms of device, since the Focus on the multitude of crossing points to be connected eliminated.

The usable additive should be adapted to the type of Be adapted to energy. As far as a laser, For example, a diode laser is used should the additive is a light-absorbing dye, e.g. black color, or a photoactive substance, wherein the overhead thread for the laser transparent is. For the application of high frequency or induction energy are especially metal and here before all iron powder, in the form of a paste, a dispersion or a powder may be present. The additive Can be applied between the threads or on the threads In the latter case, the application only on the threads of a layer of two adjacent layers sufficient. Instead of a subsequent application can the additive also added selectively to the thread material be, e.g. during the extrusion process.

According to a further feature of the invention is provided that the longitudinal and transverse threads at crossing points first using an adhesive and / or under positive engagement be joined together before they get together be merged. This will be the connection reinforced at the crossing points. Besides, the location can be the longitudinal and transverse threads by gluing and / or positive connection before the fusion process be fixed, which is advantageous if the thus formed Thread scrim moved through a device is used, with the help of the heat energy is applied.

In detail, the production of the yarn layer in the Made way that initially longitudinal threads parallel to each other be spanned, for example, between two parallel Thread trees, and then on these longitudinal threads one after the other individually or in groups laid cross threads and are provisionally fixed to the longitudinal threads and that the scrim in the longitudinal direction continuously through a Melting device transported and then rolled up becomes. At the same time or later can also be on the other Side of the longitudinal threads transverse threads are attached. It It is understood that on the free side of the transverse threads again a layer with longitudinal threads in corresponding Way can be attached. The provisional fixation can by additional application of weight, for example, with the help of one for each to be applied Energy permeable plate on the transverse threads is applied, or by gluing done.

According to the invention it is further provided that the layers after merging at the intersections temporarily pressed together until the compound hardens and cooled.

It is understood that the transverse threads are not perpendicular to must pass the longitudinal threads, but that with the inventive Method also produce scrim are where the transverse threads are oblique to the longitudinal threads run. It can also be two layers of transverse threads be provided, in which the transverse threads of a layer the longitudinal threads cross at a different angle than the the other location.

Figur 1

eine Draufsicht auf ein schematisch dargestelltes Trockensieb mit Schmelzvorrichtung;

Figur 2

eine Seitenansicht des Trockensiebs gemäß Figur 1;

Figur 3

einen Querschnitt durch das Trockensieb gemäß den Figuren 1 und 2;

Figur 4

eine Draufsicht auf einen Teil eines Trockensiebs mit formschlüssiger Verbindung der Fäden;

Figur 5

einen teilweisen Querschnitt durch das Trockensieb gemäß Figur 4;

Figur 6

eine Seitenansicht eines weiteren Trockensiebs.

In the drawing, the invention is illustrated by means of exemplary embodiments. Show it:

FIG. 1

a plan view of a schematically illustrated dryer fabric with melting device;

FIG. 2

a side view of the dryer according to Figure 1;

FIG. 3

a cross section through the dryer according to the figures 1 and 2;

FIG. 4

a plan view of a portion of a dryer fabric with positive connection of the threads;

FIG. 5

a partial cross section through the dryer according to Figure 4;

FIG. 6

a side view of another dryer.

The dryer 1 shown in Figures 1 to 3 consists from a scrim, the lower layer 2 of Longitudinal threads - exemplified with 3 - formed becomes. The longitudinal threads 3 have - as in particular from FIG 3 can be seen - rectangular cross-section and same Distance from each other. For the manufacturing process they are - what is not visible here - with their left-sided ends wound up on a thread tree. Right side is - also not visible here - a second tree provided, on the finished drying wire 1 is wound. In this direction (arrow A), the drying wire moves 1.

On the pad 2 is a top layer 4 with each other parallel transverse threads - exemplified with 5, 6, 7 - hung up. The transverse threads 5 have a wide Distance - it essentially corresponds to the distance the longitudinal threads 3 -, the transverse threads 6 a close distance to reduce the permeability of the dryer fabric 1 and the transverse threads 7 also a close distance, however a substantially smaller width than the transverse threads 5, 6. It is understood that these differences in an actual Dry fabrics are absent, i. it will come the same transverse threads equidistant from each other for use. By the representation is only symbolized be that the inventive method various types of longitudinal and transverse threads 3, 5, 6, 7 and thread densities possible. The same applies to the longitudinal threads 3, with the additional possibility here given to vary their distances across the width, e.g. in the middle area a lower thread density than in the two peripheral areas or vice versa.

For the production of the dryer fabric 1, the longitudinal threads 3 stretched between the two trees and then the transverse threads 5, 6, 7 placed over the longitudinal threads 3. This can machine, for example, with a crossbar device done, as in principle from US-A-3,097,413 is known. So that the transverse threads 5, 6, 7 to each other and with respect to the longitudinal threads 3 their position also during the movement of the dryer fabric 1 in the direction of the Keep arrow A, they will be at the crossing points - designated by way of example 8 - between longitudinal threads. 3 and transverse threads 5, 6, 7 temporarily bonded together. The adhesive application can on the longitudinal and / or transverse threads 3, 5, 6, 7 pointwise or surface wise done. Instead of a fixation by gluing can on the upper Layer 4 also a plate are placed, e.g. a Glass plate, the transverse threads 5, 6, 7 on the longitudinal threads 3 presses and prevents a shift between the two.

About the drying wire 1 spans like a bridge Melting device 9. It is intended to be the material the longitudinal and transverse threads 3, 5, 6, 7 at the crossing points 8 to melt, so they are there together merge. The melting device is laser, High frequency and / or induction devices in question. So that the melting of the material of the longitudinal threads 3 and Transverse threads 5, 6 limited to the crossing points 8 remains, is at the crossing points 8 an additive which has been applied to the absorption of the in the melting device Promotes 9 generated energy. The energization is then set so that the longitudinal and Cross threads 3, 5, 6, 7 only at the crossing points 8 because of the additive present there melt and consequently merge together, while the remaining parts of the Longitudinal and transverse threads 3, 5, 6, 7 either not at all or only slightly, in any case not up to the melting temperature, to be heated. After leaving the melter 9, the crossing points 8 cool again, so that harden the melted areas and make a firm bond between the longitudinal and transverse threads 3, 5, 6, 7 arises. This can be further promoted by the fact that the two layers 2, 4 are pressed together, for example with the help of rollers or plates during movement the drying wire 1 are carried.

Figures 4 and 5 show sections of another Drying wire 11 with a lower layer 12 of longitudinal threads - exemplified by 13 - and an upper layer 14 of transverse threads - designated 15 by way of example. It is understood that a plurality of longitudinal threads 13 are present are and that the transverse threads 15 over the entire Width of the dryer wire 11 extends, not here is shown.

Longitudinal and transverse threads 13, 15 have here also rechtkkigen Cross-section, wherein the transverse threads 15 are flatter as the longitudinal threads 13. At the crossing points - by way of example denoted by 16 - are the longitudinal and transverse threads 13, 15 positively connected with each other, namely via connecting bolts - designated 17 by way of example -, each with aligned holes - by way of example denoted by 18, 19 - in the longitudinal and transverse threads 13, 15 prevail. Instead, however, the connecting bolts 17 also on the longitudinal threads 13 or the Cross threads 15 be formed so that only the other Threads have holes in which then the connecting bolts 17 are pushed into it. The so produced interlocking connection has provisional character, to the thread scrim by a melting device 9 of in Figure 1 shown type pass and in this way also a merger of the longitudinal and transverse threads 13, 15 and also to cause the connecting pin 17.

Figure 6 also shows a section through another Drying screen 21 with a lower layer 22 of longitudinal threads 23 and an upper layer 24 of transverse threads - by way of example denoted by 25 -. The longitudinal and transverse threads 23, 25 have rectangular cross-section, so that they face each other flat lie. They are about adhesive layers - exemplary denoted by 26 - at the crossing points 27 interconnected so that they are mutually fixed in position are. The connection is made only provisionally be to the longitudinal and transverse threads 23, 25 for the Transport by a melting device 9 in FIG. 1 to fix the type shown. In the smelting device 9 then becomes a merger of the longitudinal and transverse threads 23, 25 at the crossing points - designated 27 by way of example - causes.

Claims (34)

1. Drying screen (1, 11, 21) for the drying section of a paper machine, comprising a filament lay-up made of at least one layer (2, 12, 22) of longitudinal filaments (3, 13, 23) and at least one layer (4, 14, 24) of transverse filaments (5, 6, 7; 15; 25) which cross the longitudinal filaments (3, 13, 23), wherein the longitudinal and transverse filaments (3, 13, 23; 5, 6, 7; 15; 25) are fused to each other at crossing points (8, 16, 27) as a result of heating to the melting temperature, characterized in that the longitudinal and transverse filaments (3, 13, 23; 5, 6, 7; 15; 25) are single-component filaments are designed as flat filaments and that the longitudinal and transverse filaments (3, 13, 23; 5, 6, 7; 15; 25) are fused to each other and/or to these connecting parts (17, 18, 19) as a result of heating, which is restricted to said crossing points.
2. Drying screen according to claim 1, characterised in that the longitudinal and transverse filaments (13, 15) are additionally positively attached to each other at crossing points (16).
3. Drying screen according to claim 2, characterised in that each joint consists of an aperture in one filament and of a projection, which fits suitably therein, on the crossing filament.
4. Drying screen according to claim 2, characterised in that each joint consists of mutually aligned apertures (18, 19) in the filaments (13, 15) and of a pin (17) which passes through the latter.
5. Drying screen according to any one of claims 1 to 4, characterised in that the longitudinal and transverse filaments (3, 13, 23; 5, 6, 7; 15; 25) are formed as flat filaments with a rectangular cross-section.
6. Drying screen according to claim 5, characterised in that the longitudinal and transverse filaments (3, 13, 23; 5, 6, 7; 15, 25) have a width of 2 to 20 mm, preferably 8 to 12 mm.
7. Drying screen according to any one of claims 1 to 6, characterised in that the longitudinal filaments (3, 13, 23) have a width in their middle region which differs from that in their edge regions.
8. Drying screen according to any one of claims 5 to 7, characterised in that the longitudinal and transverse filaments (3, 13, 23; 5, 6, 7; 15, 25) have a height of 0.3 to 2 mm, preferably 0.6 to 1.2 mm.
9. Drying screen according to any one of claims 5 to 8, characterised in that the transverse filaments (5, 6, 7; 15; 25) have a thickness which as a maximum is the same as that of the longitudinal filaments (3, 13, 23).
10. Drying screen according to any one of claims 1 to 9, characterised in that the longitudinal and/or transverse filaments comprises passageway openings.
11. Drying screen according to any one of claims 1 to 10, characterised in that at least three layers are present, wherein a layer comprising longitudinal filaments and a layer comprising transverse filaments are adjacent in each case.
12. Drying screen according to claim 11, characterised in that each layer comprising transverse filaments is surrounded on both sides by a layer of longitudinal filaments.
13. Drying screen according to any one of claims 1 to 12, characterised in that at least one layer comprising longitudinal filaments has a filament density in its middle region which differs from that in its edge regions.
14. Drying screen according to any one of claims 1 to 14, characterised in that end pieces of longitudinal filaments (3, 13, 23) are wrapped round and fixed to the end faces of the paper machine clothing (1, 12, 21) with the formation of loops.
15. Drying screen according to claim 14, characterised in that the end pieces are wrapped round on the side, which is remote from the layer (2, 12, 22) comprising the longitudinal filaments (3, 13, 23), of the layer (4, 14, 24) comprising transverse filaments (5, 6, 7; 15; 25) and are fixed to the transverse filaments (5, 6, 7; 15; 25).
16. Drying screen according to any one of claims 1 to 13, characterised in that the end pieces are fixed to the longitudinal filaments (3, 13, 23) themselves.
17. Drying screen according to any one of claims 14 to 16, characterised in that non-loop-forming end pieces of longitudinal filaments (3, 13, 23) are each fixed to the last transverse filament (5, 6, 7; 15; 25) on the end face of the paper machine clothing (1).
18. Drying screen according to any one of claims 14 to 17, characterised in that, alternately, at least one end piece is wrapped round with the formation of a loop, and at least one end piece ends at the outer edge of the last transverse filament (5, 6, 7; 15; 25) on the end face of the paper machine clothing (1).
19. Drying screen according to any one of claims 14 to 18, characterised in that longitudinal filaments of a second layer comprising longitudinal filaments, which is seated against the layer comprising transverse filaments, adjoin the ends of the end pieces.
20. Drying screen according to any one of claims 1 to 19, characterised in that the longitudinal and/or transverse filaments (3, 13, 23; 5, 6, 7; 15; 25) consist of PET, PA in all modifications, PPS, PEK, PEEK, an elastic polyester, PBT or PTT or a combination thereof.
21. Drying screen according to any one of claims 1 to 19, characterised in that the longitudinal and/or transverse filaments (3, 13, 23; 5, 6, 7; 15; 25) are fibre-reinforced.
22. Drying screen according to any one of claims 1 to 21, characterised in that a fibrous layer is provided on at least one side.
23. A method of producing a dryer screen (1, 11, 21) for the drying section of a paper machine, wherein a filament lay-up is produced by arranging at least one layer (2, 12, 22) of longitudinal filaments (3, 13, 23) and at least one layer (4, 14, 24) of transverse filaments (5, 6, 7; 15; 25), which cross the longitudinal filaments (3, 13, 23) one above the other, and by fusing the longitudinal and transverse filaments (3, 13, 23; 5, 6, 7; 15, 25) at crossing points to each other by heating to melting temperature, characterised in that single-component filaments designed as flat filaments are used for the longitudinal and transverse filaments (3, 13, 23; 5, 6, 7; 15; 25) and that the longitudinal and transverse filaments (3, 13, 23; 5, 6, 7; 15; 25) are fused at crossing points (8, 16, 27) to each other and/or to parts (17, 18, 19) joining them by heating, which is restricted to said crossing points (8, 16, 27).
24. A method according to claim 23, characterised in that heating is effected by means of laser-, high-frequency- and/or induction energy.
25. A method according to claim 24, characterised in that energy is applied in the form of spots.
26. A method according to claim 24, characterised in that energy is applied two-dimensionally over a plurality of crossing points (8, 16, 27) to be fused together and said crossing points (8, 16, 27) have previously been provided with an additive which facilitates the absorption of energy.
27. A method according to claim 26, characterised in that the additive is a dye, an optically active substance or a metal powder.
28. A method according to claim 26 or 27, characterised in that the additive is only applied to one filament lay-up.
29. A method according to any one of claims 23 to 28, characterised in that the longitudinal and transverse filaments (13, 15) are firstly positively attached to each other at crossing points (16) before they are fused to each other.
30. A method according to any one of claims 23 to 29, characterised in that longitudinal filaments (3, 13, 23) are firstly clamped parallel to each other, and that transverse filaments (5, 6, 7; 15; 25) are then laid, individually or in groups, successively on said longitudinal filaments (3, 13, 23) and are temporarily fixed to the longitudinal filaments (3, 13, 23), and that the filament lay-up is conveyed in a longitudinal direction through a fusing apparatus (9) and is then rolled up.
31. A method according to claim 30, characterised in that transverse filaments (5, 15, 25) are also fixed, simultaneously or later, to the other side of the longitudinal filaments (3, 13, 23).
32. A method according to claim 30 or 31, characterised in that temporary fixing is effected by the additional application of weight or by means of adhesive bonding.
33. A method according to any one of claims 23 to 32, characterised in that the layers (2, 4, 12, 14, 22, 24) are temporarily pressed on to each other at the crossing points (8, 16, 27).
34. A method according to any one of claims 23 to 33, characterised in that a fibrous layer is applied to one or both sides of the filament lay-up and is fixed thereto.

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