EP1359252A1 - Paper machine clothing 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) strips. Longitudinal and transverse strips are each made of a different type of fibre, and are joined at their crossover points (8) esp. by a form-fit. The join consists of a detent in which the fibres of one strip cross those of the transverse strip in a matching detent. The crossover points two strips have concentric holes with a stud fixture (11) and are further bonded by a hotmelt adhesive. Also claimed is a process to make the de-watering web.

Description

The invention relates to a porous paper machine clothing for dewatering a paper web in a paper machine, especially as a paper machine felt or dry fabric, with a scrim from at least one layer Longitudinal threads and at least one layer crossing the longitudinal threads Cross threads.

Porous paper machine clothing is long and wide Ribbons in different lots of a paper machine circulate and on which the paper web through the paper machine is transported. In the first so-called Sheet forming section becomes a fiber pulp on the paper machine clothing applied, with a fibrous web forms. This is due to the paper machine clothing drained through. The paper machine clothing consists of a textile thread structure that is so porous is that the liquid coming out of the fibrous web due to gravity and negative pressure the paper machine clothing is discharged through. In The following press section will be paper web and paper machine clothing passed through roller presses, so that the one still in the paper web Liquid through the paper machine clothing is squeezed out. As a rule, the paper machine clothing as a felt with a carrier made of a textile thread structure educated. In the following dryer section paper web and paper machine clothing are over heated rollers, resulting in further drainage - in this case it is better to speak of drying - he follows. In the drying section are mainly turn paper machine clothing consisting of thread structures, i.e. Dryer fabrics, which are also porous, to remove the steam through the pores.

The textile thread structures are primarily woven educated. There are also so-called scrims known in which the threads are not bound together, therefore not interwoven or meshed are. Such a paper machine clothing is in US-A-3,097,413 disclosed. It has a scrim from one Position longitudinal threads that are parallel and spaced apart run and are not connected. On the layer is applied to a non-woven fabric that runs the longitudinal threads includes and is needled with them.

However, such a paper machine clothing has only one low transverse strength. That’s why we started to combine the longitudinal thread layer with a transverse thread layer (DE-A-1 802 560; EP-B-0 394 293). Doing so first Modules consisting of a thread layer and a needled nonwoven, formed and these modules merged and needled again. This way of making is not suitable for paper machine clothing, which consist only of a thread structure. In this case proposes US-A-4,555,440, the individual thread layers to connect with each other by twine.

With the aforementioned generic paper machine clothing is in particular the resistance to displacement between the individual layers and thus the dimensional stability unsatisfactory. As far as binding threads are used, represent these foreign bodies and complicate the Manufacturing process significantly. To eliminate this The US-A-5,888,915 proposes disadvantages, the layers Lay longitudinal and cross threads directly on top of each other and on to fuse the intersection points by heating. The prerequisite for this, however, is that bicomponent threads be used where the thread core a higher melting temperature than the thread jacket Has. The fusion takes place by heating to a Temperature above the melting point of the thread jacket and below the melting point of the thread core.

Because of the direct connection of the threads of the individual Layers the dimensional stability of the paper machine clothing improved. The disadvantage, however, is that special Threads, namely bicomponent threads, are used that are expensive and their material properties not always optimally to the conditions in the Have the respective batch of the paper machine set.

The invention has for its object a paper machine clothing with a laid scrim so that with it a high regardless of the type of threads Dimensional stability is achievable and that it is for everyone Batches of a paper machine is suitable. A second The task is to create a process for its manufacture provide.

According to the invention, the first object is achieved by that the longitudinal and transverse threads are positive at intersection points are interconnected, the connection each from a recess in one thread and a protruding frame at the crossing Thread or out at the intersection with each other aligned recesses and these interspersed pins, e.g. Bolts or rivets made of plastic or metal can. So with the invention, the possibility opened, a direct connection between the longitudinal and Cross threads at the crossing points regardless of the material of the threads. So you are no longer on bicomponent threads instructed, although the basic idea of the invention also includes such threads, but can be single-component threads connect directly to each other.

This is the first time that paper machine clothing has been used a scrim provided by high dimensional stability and when using single-component threads low manufacturing costs. Under single component threads are such threads to be understood which consist homogeneously of a material, the material can also be a copolymer, provided only homogeneity given is.

Compared to fabrics and knitted fabrics, the invention has Paper machine clothing the advantage of high flexibility regarding the number of layers, the thread density and the Choice of material. They are also for manufacturing no expensive textile machines, such as weaving and knitting machines, required, which is also the width of the on them limited to manufacture paper machine clothing. A there is no such limitation for thread beds, i.e. they can be made in practically any width become. In addition, with thread recliners to that with fabrics necessary thermosetting can be dispensed with if the threads be sufficiently thermally treated beforehand.

In an embodiment of the invention it is provided that to connecting intersection additionally an adhesive is available. Such an adhesive supports the fixation of the longitudinal and transverse threads at the crossing points. In addition, the adhesive can interlock Parts such as recesses and protrusions or pins, glue. Hot melt adhesives come as adhesives, whose melting temperature is below that of the threads contact adhesive, diffusion adhesive and / or reaction adhesive in question.

This can improve the fixation at the crossing points be that the longitudinal and transverse threads and / or the these connecting parts, e.g. the pins and recesses at crossing points additionally as a result of this Limited heating intersection fused together are. The temperature of the remaining areas of the Threads remain below the melting point of the thread material. So there is no change in structure and shape, so that the total by stacking the layers given thread structure is retained.

It is particularly preferred to use the longitudinal and transverse threads Form flat threads with a rectangular cross-section. On this creates a surface contact at the crossing points, and the area over which the threads join together can be fused, is significantly enlarged and so firmer. The thread shape also favors training the positive connection. As appropriate There is a width for the longitudinal and transverse threads from 2 to 20 mm, preferably 8 to 12 mm. The Thickness should be between 0.3 to 2 mm, preferably 0.6 to 1.2 mm, with the transverse threads maximally the same Thickness should be like the longitudinal threads.

To be sufficient, especially with very wide flat threads To ensure permeability to water or steam, can have through openings in the longitudinal and / or Cross threads are provided. By their size and number, the permeability can be controlled arbitrarily, with the possibility of permeability different across the width of the paper machine clothing to design, e.g. in the middle higher than in the border areas or vice versa. The through openings can be designed as round holes or elongated slots his.

The paper machine clothing according to the invention can have any number of layers, each being alternate one layer with longitudinal threads and one layer with cross threads, are adjacent to each other. A Appropriate number are two or three layers, whereby in in the former case, a lower longitudinal thread scrim is preferred combined an upper cross thread and in the latter Fall a layer with cross threads on both sides of one layer Longitudinal threads are included. In this way, is on A longitudinal structure is formed on the top and bottom. Of course it is possible to do the opposite, so that on the top and bottom by the there existing cross threads a cross structure arises.

The permeability or permeability of the paper machine clothing can also, for example, by the Width dimensions of the longitudinal and / or transverse threads and / or adjust their thread density within wide limits. There is also the possibility in at least one location Arrange longitudinal threads so that they are in the central area have a different thread density than in the edge areas, in particular in the middle area less than in the edge areas.

With the scrim according to the invention can also in simple ways eyelets on the front of the paper machine clothing by turning longitudinal threads under Form loops to make one with them To form plug wire seam. This can happen in the way that end pieces of longitudinal threads of a first layer the end faces of the paper machine clothing with formation of loops on the side facing away from this position the situation with cross threads and on several of these Cross threads, preferably on at least five cross threads, be attached. The attachment can also be made to the Longitudinal threads themselves are made. The fixation can in both cases, e.g. by means of bolts or Rivets made of plastic or metal.

The loop formation should expediently only with one Part of the longitudinal threads happen to the two Forehead edges with their loops like a comb grab and so a through channel for a plug wire can form. Preferably at least alternately turned over an end piece to form a loop and at least one end piece without forming a loop end at the outer cross thread edge. So the permeability should not deteriorate in this area at the ends of the end pieces Layer with cross threads adjacent second layer with longitudinal threads connect, i.e. these longitudinal threads butt against the end pieces, so do not overlap with them, so that it does not condense in this area Longitudinal threads come.

As far as the material of the threads is concerned, there are basically no restrictions; it should have high tensile strength, low Have stretch and a high initial modulus. In question come for example PET, PA in all modifications, PPS, PEK, PEKK, elastic polyester, PBT or PTT or Combinations of these. The threads can be armored, e.g. with fibers such as glass fibers, carbon fibers, and / or Ceramic fibers, the fibers also called short cut fibers can be present.

The paper machine clothing according to the invention can be use in all lots of a paper machine and due to their flexibility to meet the respective requirements optimally adapt these games. For use in the Sheet formation and dryer section mainly come training in question where the paper machine clothing consists only of the scrim, which does not rule out that the scrim with other components is combined, for example a nonwoven fabric. For the Press section is recommended, the scrim according to the invention to use as a carrier and with a fiber layer to be provided on one or both sides, for example by one or both sides needling or laminating Nonwoven or spunbonded.

For the production of the paper machine clothing described above if a method is proposed according to the invention, where the longitudinal and transverse threads at crossing points be positively connected to each other, for example by interlocking one projection at a time on one thread and a complementary recess on the crossing thread or by inserting a pin, such as a bolt or rivet, in one another aligned recesses in the threads.

The connection between the threads can still be improved be that the longitudinal and transverse threads at crossing points with each other and / or with connecting elements by heating limited to the crossing points are melted together at the melting temperature, the heating by means of laser, radio frequency and / or Induction energy takes place. There are two alternatives Processes are used with which the heating can be focused on the crossing points. On the one hand, the energy can be limited space on the crossing points, what for especially lasers because of their focused laser beam suitable. Alternatively, the energy also across several intersection points to be merged be applied, for example over the entire Width and a certain length of the paper machine clothing, if the crossing points previously with one Provide absorption of energy-promoting additives become. Because of this additive it concentrates the energy consumption in spite of extensive application to the Crossing points, so that only this at melting temperature heat and consequently fuse together. The flat Application of the energy is simpler in terms of the device to realize since focusing on the The number of crossing points to be connected is eliminated.

The additive that can be used should depend on the type of Be energized adapted. As far as a laser, for example a diode laser should be used the additive is a light absorbing dye, e.g. black color, or be a light-active substance, whereby the thread above is transparent. For the application of high-frequency or induction energy especially metal and especially iron powder, that in the form of a paste, a dispersion or a powder can be present. The additive can be between the Threads or are applied to the threads, wherein in the latter case, the application only on the threads of one Location of two neighboring layers is sufficient. Instead of the additive can be applied subsequently also be added to the thread material selectively, e.g. during the extrusion process.

According to a further feature of the invention, that the longitudinal and transverse threads at crossing points additionally bonded together using an adhesive become. This will make the connection at the crossing points further strengthened.

In particular, the production of the scrim in the Way that first longitudinal threads parallel to each other be spanned, for example between two parallel ones Thread trees, and then on these longitudinal threads one after the other individually or in groups, cross threads and form-fitting longitudinal and transverse threads at the crossing points be connected to each other, for example by connecting bolts in alignment at the crossing points Holes will be knocked in or a head start one thread in a complementary recess in the other thread is pressed.

For an even better connection of the threads at the crossing points to achieve the scrim in the longitudinal direction continuously through a melter transported and then rolled up. Gleichzeiitg or later on the other side of the longitudinal threads Cross threads are attached. It is understood that a layer on the free side of the cross threads be attached with longitudinal threads in a corresponding manner can.

According to the invention it is further provided that the layers temporarily after the merge at the crossing points be pressed together until the connection has hardened and cooled down.

If a felt is to be formed, for example for use in the press section of a paper machine, should have a layer of fibers on one or both sides of the laid scrim applied and attached to this. The attachment can be done by needling, gluing or melting happen.

It is understood that the transverse threads are not perpendicular to the longitudinal threads must run, but that with the invention The process can also be used to produce scrims are in which the transverse threads are oblique to the longitudinal threads run. Two layers of cross threads can also be used be provided in which the transverse threads of one layer cross the longitudinal threads at a different angle than that the other location.

Figur 1

eine Draufsicht auf eine schematisch dargestellte Papiermaschinenbespannung mit Schmelzvorrichtung;

Figur 2

eine vergrößerte Draufsicht auf einen Teil der Papiermaschinenbespannung gemäß Figur 1;

Figur 3

einen teilweisen Querschnitt durch die Papiermaschinenbespannung gemäß den Figur 1 und 2;

In the drawing, the invention is illustrated in more detail using exemplary embodiments. Show it:

Figure 1

a plan view of a schematically illustrated paper machine clothing with melting device;

Figure 2

an enlarged plan view of a portion of the paper machine clothing according to Figure 1;

Figure 3

a partial cross section through the paper machine clothing according to Figures 1 and 2;

The paper machine clothing 1 shown in FIG. 1 consists of a scrim, the lower layer 2 of Longitudinal threads - designated 3 by way of example - formed becomes. The longitudinal threads 3 have a rectangular cross section and equal distance from each other. For the manufacturing process they are - which is not visible here - with theirs left ends wound on a thread tree. On the right is a - not visible here either second tree provided on which the finished paper machine clothing 1 is wound up. In this direction (Arrow A) the paper machine clothing 1 moves.

On the base 2 is a top layer 4 with each other parallel cross threads - exemplified with 5, 6, 7 - hung up. The transverse threads 5 have a wide one Distance - it essentially corresponds to the distance of the longitudinal threads 3 -, the transverse threads 6 a narrow distance to reduce the permeability of the paper machine clothing 1 and the transverse threads 7 also a tight Distance, but a much smaller width than that Cross threads 5, 6. It is understood that these differences not with an actual paper machine clothing are present, i.e. the same cross threads come along same distance from each other for use. By representation is only to be symbolized that the invention Process different types of longitudinal and Cross threads 3, 5, 6, 7 and thread densities allows. The same applies to the longitudinal threads 3, with additional here there is still the possibility of their distances to vary across the width, e.g. in the middle area to provide a lower thread density than in the two Marginal areas or vice versa.

Figures 2 and 3 show sections of the paper machine clothing 1 according to FIG. 1. At the crossing points - designated by way of example with 8 - are the longitudinal and transverse threads 3, 5 positively connected to each other via connecting bolts - designated 10 by way of example -, each aligned holes - exemplary designated 11, 12 - in the longitudinal and transverse threads 3, 5 enforce. However, the connecting bolts can be used instead 10 also on the longitudinal threads 3 or the transverse threads 5 be molded so that only the other threads Have holes in which the connecting bolts be pushed in.

For the manufacture of paper machine clothing 1 the longitudinal threads 3 stretched between the two trees and then the transverse threads 5, 6, 7 over the longitudinal threads 3 laid. This can be done mechanically, for example with a Cross panel device happen as they are made in principle US-A-3,097,413 is known. Then the longitudinal and Cross threads 3, 5, 6, 7 by inserting connecting bolts 12 into those aligned at the crossing points 8 Holes 11, 12 are positively connected. For further fixation are longitudinal and transverse threads 3, 5, 6, 7 to the Crossing points 8 glued together. The adhesive application can on the longitudinal and / or transverse threads 3, 5, 6, 7 are carried out point by point or area by area.

The paper machine clothing 1 stretches like a bridge a melting device 9. It is intended the material of the longitudinal and transverse threads 3, 5, 6, 7 and also the connecting bolt 10 at the crossing points 8 to Bring them melt so that they melt together there. Laser, high-frequency and / or induction devices in question. In order to the melting of the material of the longitudinal threads 3 and transverse threads 5, 6, 7 remains limited to the crossing points 8, an additive is applied at the crossing points 8 been the absorption of the in the melter 9 promotes generated energy. The energy load is then set so that the longitudinal and transverse threads 3, 5, 6, 7 only at the crossing points 8 because of the existing there Melt the admixture and consequently together and / or fuse with the connecting bolts 10 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 heated up to the melting temperature. To Leaving the melting device 9 cool down the crossing points 8 again, so that the melted areas harden and a firm connection between the longitudinal and Cross threads 3, 5, 6, 7 arises. This can still be done are encouraged that the two layers 2, 4 pressed together be, for example with the help of rollers or Plates in the movement of the paper machine clothing 1 be carried.

If the connecting bolts 12 are very tight in the holes 11, 12 sit, the positive connection can also be sufficient, and then a subsequent one is not required Fusion process.

Claims (36)

Porous paper machine clothing (1) for dewatering a paper web in a paper machine with a scrim of at least one layer (2) of longitudinal threads (3) and at least one layer (4) of transverse threads (5, 6, 7) crossing the longitudinal threads (3), characterized that the longitudinal and transverse threads (3, 5, 6, 7) are positively connected to one another at crossing points (8). Paper machine clothing according to claim 1, characterized in that the connection consists in each case of a recess in the one thread and a projection on the crossing thread which fits therein. Paper machine clothing according to claim 1, characterized in that the connection consists of mutually aligned recesses (11, 12) in the threads (3, 5, 6, 7) and a pin (10) engaging them. Paper machine clothing according to one of claims 1 to 3, characterized in that an adhesive is additionally present at the crossing points (8) to be connected. Paper machine clothing according to claim 4, characterized in that the adhesive is a hot melt adhesive, contact adhesive, diffusion adhesive and / or reaction adhesive. Paper machine clothing according to one of claims 1 to 5, characterized in that the longitudinal and transverse threads (3; 5, 6, 7) and / or the parts connecting them (10, 11, 12) at crossing points (8) additionally as a result of this Crossing points (8) limited heating to the melting temperature are fused together. Paper machine clothing according to one of claims 1 to 6, characterized in that the longitudinal and transverse threads (3; 5, 6, 7) are designed as flat threads with a rectangular cross-section. Paper machine clothing according to claim 7, characterized in that the longitudinal and transverse threads (3; 5, 6, 7) have a width of 2 to 20 mm, preferably 8 to 12 mm. Paper machine clothing according to one of claims 1 to 8, characterized in that the longitudinal threads (3) have a different width in the central region than in the edge regions. Paper machine clothing according to one of claims 7 to 9, characterized in that the longitudinal and transverse threads (3; 5, 6, 7) have a height of 0.3 to 2 mm, preferably 0.6 to 1.2 mm. Paper machine clothing according to one of claims 7 to 10, characterized in that the transverse threads (5, 6, 7) have at most the same thickness as the longitudinal threads (3). Paper machine clothing according to one of claims 1 to 11, characterized in that the longitudinal and / or transverse threads have through openings. Paper machine clothing according to one of claims 1 to 12, characterized in that at least three layers are present, one layer with longitudinal threads and one layer with transverse threads being adjacent. Paper machine clothing according to claim 13, characterized in that a layer with transverse threads is enclosed on both sides with a layer of longitudinal threads. Paper machine clothing according to one of claims 1 to 14, characterized in that at least one layer with longitudinal threads in the central region has a different thread density than in the edge regions. Paper machine clothing according to one of claims 1 to 15, characterized in that end pieces of longitudinal threads (3) are turned over and fixed on the end faces of the paper machine clothing (1) to form loops. Paper machine clothing according to claim 16, characterized in that the end pieces are folded over on the side of the layer (4) facing away from the layer (2) with the longitudinal threads (3) with transverse threads (5, 6, 7) and on transverse threads (5, 6, 7 ) are fixed. Paper machine clothing according to claim 17, characterized in that end pieces of longitudinal threads (3) of a layer (2) on the end faces of the paper machine clothing (1) are turned over to form loops and are fixed to themselves. Paper machine clothing according to one of claims 16 to 18, characterized in that non-loop-forming end pieces of longitudinal threads (3) are each fixed to the last transverse thread (5, 6, 7) on the end face of the paper machine clothing (1). Paper machine clothing according to one of claims 16 to 19, characterized in that at least one end piece is alternately folded over to form a loop and at least one end piece ends at the outer edge of the last transverse thread (5, 6, 7) on the end face of the paper machine clothing (1) , Paper machine clothing according to one of claims 16 to 20, characterized in that the ends of the end pieces are joined by longitudinal threads of a second layer of longitudinal threads lying against the layer with transverse threads. Paper machine clothing according to one of claims 1 to 21, characterized in that the longitudinal and / or transverse threads (3, 5, 6, 7) made of PET, PA in all modifications, PPS, PEK, PEEK, elastic polyester, PBT or PTT or combinations thereof consist. Paper machine clothing according to one of claims 1 to 22, characterized in that the longitudinal and / or transverse threads (3, 5, 6, 7) are fiber-reinforced. Paper machine clothing according to one of claims 1 to 23, characterized in that a fiber layer is provided on at least one side. Method for producing a porous paper machine clothing (1), in which a laid scrim is produced in that at least one layer (2) of longitudinal threads (3) and at least one layer (4) cross threads (5, 6, 7) crossing the longitudinal threads (3) can be arranged one above the other, characterized in that the longitudinal and transverse threads (3; 5, 6, 7) are positively connected to one another at crossing points (8). A method according to claim 25, characterized in that the longitudinal and transverse threads (3; 5, 6, 7) at crossing points (8) additionally by heating to melting point with one another and / or with parts (10) connecting them to the crossing points (8) ) are fused. A method according to claim 26, characterized in that the heating takes place by means of laser, high-frequency and / or induction energy. A method according to claim 26 or 27, characterized in that the energy is applied selectively. Method according to Claim 26 or 27, characterized in that the energy is applied over a large area via a plurality of intersection points (8) to be melted and these intersection points (8) have previously been provided with an additive which promotes absorption of the energy. A method according to claim 29, characterized in that the additive is a dye, a light-active substance or a metal powder. A method according to claim 29 or 30, characterized in that the additive is applied only to the threads and / or between the threads. Method according to one of claims 25 to 31, characterized in that the longitudinal and transverse threads (3; 5, 6, 7) at points of intersection (8) additionally glued to one another and / or to the parts (10) connecting them using adhesive become. Method according to one of claims 25 to 32, characterized in that first longitudinal threads (3) are stretched parallel to one another and then successively individually or in groups transverse threads (5, 6, 7) are placed on these longitudinal threads (3) and fixed to the longitudinal threads (3) be, and that the scrim is transported in the longitudinal direction and then rolled up. Method according to claim 33, characterized in that transverse threads (5, 6, 7) are fastened simultaneously or later on the other side of the longitudinal threads (3). Method according to one of claims 25 to 34, characterized in that the layers (2, 4) at the crossing points (8) are temporarily pressed against one another for fixing. Method according to one of claims 25 to 35, characterized in that a fiber layer is applied to the laid scrim on one or both sides and fastened to it.

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