EP1336685A1 - Papermachine fabric in particular press felt, and method of making the papermachine fabric - Google Patents

Abstract

Press felt for a papermaking machine has support made up of layers (3, 4, 5) of parallel fibers (6, 7, 8). These have spacer fibers between them which are soluble in a solvent which does not dissolve the parallel fibers. An Independent claim is also included for a method for making the felt in which spacer fibers as described above are embedded between the parallel fibers and are dissolved from between them.

Description

The invention relates to a paper machine clothing, in particular a press felt, with a carrier that at least a layer of a scrim with parallel to each other has running scrim threads. The invention relates to the further a method for producing a paper machine clothing.

Paper machine clothing is circulating in paper machines Tapes of great length and width, that of training and Guide the paper web through the paper machine. you Construction depends heavily on what part of the paper machine they are used. For the press section, in which mechanically drains the previously formed paper web is, press felts are common in which a carrier is embedded in a fiber matrix. The carrier serves the inclusion, in particular, of those acting on the press felt Tensile forces and is primarily formed as a fabric, wherein the carrier also does not consist of several, among themselves connected carrier webs can be constructed. On this The carrier is then needled on one or both sides of a nonwoven fabric, that protects the wearer from abrasion and ensures flat surfaces.

Instead of a fabric, laid scrim can also be used for the wearer be provided in single and multi-layer training. Such generic press felts are, for example EP-B-0 394 293 and EP-A-0 038 276. The Threads are characterized by the fact that they consist of a There are a large number of parallel laying threads, the scrim threads in both longitudinal and can also extend in the transverse direction. Such laid scrims can also with other thread structures, such as Woven fabrics can be combined (cf. DE-C-40 40 861).

So that the press felt is sufficiently permeable to liquids effective dewatering of the paper web is guaranteed, the scrim must be spaced apart exhibit. These distances should be as equal as possible and be constant over the extension of the scrim threads, thus the drainage properties of the press felt whose area is even. When making such Press felts, however, cause problems for such to ensure equal and constant distances, in particular in the needling process for connection and Consolidation of the nonwoven layers.

The invention has for its object a paper machine clothing of the type mentioned at the beginning that drainage properties as uniform as possible over their area can be achieved. Another job is a method of making one to provide such paper machine clothing.

The first-mentioned object is achieved according to the invention by that there are spacer threads between two Laying threads run and are soluble in a solvent in which the remaining part of the paper machine clothing is not soluble. Basic idea of the invention So it is between the scrim threads - and preferably between all scrim threads - to provide spacing threads, which the laid threads on a predetermined and over keep their distance at a constant distance. she thereby stabilize the position of the scrim and provide for their even distribution over the surface. There they are introduced during the manufacture of the carrier, it occurs in subsequent manufacturing steps, in particular when the carrier is embedded in a fiber matrix for example by needling nonwovens, not to shift the scrim threads, i.e. their distribution remains until the paper machine clothing is completed receive. Only then are the spacer threads detached to the desired water permeability to obtain.

It can be removed before it is drawn into the paper machine through an appropriate washing step or only after pulling in, taking out through the liquid squeezed out of the paper web takes place during a running-in phase. In both cases it is expedient that the spacer threads are water-soluble, in particular threads made of polyvinyl alcohol to offer. The result is paper machine clothing with at least one scrim having carrier that extends through the surface very uniform drainage properties.

Although it has long been known in the art, fibers soluble in paper machine clothing or incorporate threads and thread them in before the paper machine or in a run-in phase. However, this happened to the paper machine clothing to make water permeable at all or its interior To increase cavity volume to such an extent like this through the normal manufacturing processes would have been achievable, and thereby the drainage capacity to enlarge (see US-A-4,482,601, EP-B-0 466 990, EP-A-0 567 206, EP-B-0 413 869; WO 98/07925; EP-A-0 123 431; DE-A-24 37 303; DE-U-70 31 398). there were also used fibers that are used in are not soluble in the paper machine and only through Application of a special wash liquor were removable. The purpose of this measure, the original one, was through pollution restore reduced water permeability. In both cases, the goal is not with of those on which the present invention is based, comparable.

In a first embodiment of the basic idea of the invention the spacer threads run parallel to the scrim threads, i.e. the lay-up threads and the spacer threads lie Side by side with each other, it being understood that the spacer threads are constant over their extension Cross section. A spacer thread is usually sufficient between two scrim threads, so that always alternate a scrim with a spacer thread. Alternatively, it can be provided that the spacer threads each wound around a scrim or are twisted with this so that they are outside protrude. In this way there is a point by point The threads lie against each other, either the spacer threads, when all scrim threads are wrapped with spacer threads or are twisted with them, or from each a spacer thread and a scrim thread, if only everyone second laid thread wrapped by a spacer thread or is twisted with this. The point touch can go into line contact when the scrim threads are completely wrapped by the spacer threads and for example are formed as flat threads or tapes.

According to a further feature of the invention, that scrim threads are wound with a spun yarn or are twisted, as is already the case with paper machine clothing according to EP-B-0 394 293 is.

According to the invention it is also proposed that scrim threads are provided with fibers that protrude outwards, the fibers preferably predominantly perpendicular to Surface of the scrim threads - but also at an angle should protrude up to 60 ° from the vertical. Such Laying threads can be wrapped with spun yarns Scrim threads as known from EP-B-0 394 293 replace at least partially, but preferably completely, whereby not all scrim threads are formed in this way have to be, but they are expedient. The The advantage of such scrim is that such Plaid threads much easier and therefore cheaper can be produced, for example by gluing the Fibers and in particular flocking or through training as chenille threads. This opens up to now the threads wrapped with spun yarn are not given Possibility of monofilament of different diameters, preferably in the range between 0.3 and 0.6 mm and give them the same quality that by wrapping the laid threads with spun yarn was effected. The protruding fibers cannot only by flocking, but also by roughening, especially Scraping of the material of the monofilaments are produced.

The use of monofilaments allows seam felts to appear Scrim can be made because of the monofilament to form loops on the end edges of the paper machine clothing own and about these ends by means of a plug-in wire pushed through the loops can be connected. Such seam felts are special a paper machine is essential in the press section easier to pull in than endless press felts.

Of course, there is also the possibility of the scrim threads with fibers protruding outwards as threads from individual threads, preferably from two to twelve monofilaments Individual threads with a diameter of 0.1 to 0.4 mm, or to be designed as multifilaments. This too Threads can be flocked. Instead there is Possibility to place the fibers that stand out between the Pinch individual threads.

To further improve the drainage properties, is provided according to the invention that a part or all laid threads as helically profiled Monofilaments are formed. So you don't have one round cross-section, with the profile in the longitudinal direction the monofilament seen helical or helical runs, the respective monofilament with regard to its outer design twisted in itself around its longitudinal axis is.

By using the helically profiled according to the invention The open volume is laid inside the paper machine clothing increases, and there are better drainage properties. This effect can by the number, design and arrangement of these scrim threads varies to a considerable extent and thus to the respective Requirements are adjusted. It happens does not depend on whether the scrim threads within the paper machine clothing are under torsional stress, they thus only twisted after their production and in this Condition brought into the paper machine clothing are or whether the helical profile already in production, for example in extrusion by appropriate nozzle shapes or in the subsequent Stretch, has been stamped and therefore the monofilament present without tension in the paper machine clothing.

Although it is known for certain purposes in cross section rectangular, flat threads or other cross-sectional shapes of threads for the supports of paper machine clothing to use, which are partly strongly profiled (see DE-A-40 31 608; US-A-5,361,808; DE-A-195 45 386; US-A-5,591,525; EP-A-1 067 239, DE-A-199 00 989). These threads are profiled for various reasons. However, all threads are common that the profile is elongated itself thus extends in the axis of the respective thread and is therefore not twisted.

With regard to the formation of the cross sections of the helical profiled monofilament there is great freedom. So you can create an oval, trilobal, polygonal, square, rectangular, shamrock-shaped and / or have triangular cross section, the cross sections don't even have to be regular or symmetrical. Monofilaments of different cross-sections can also be used be in place to meet the requirements Influence on the pore volume and thus on the drainage properties to take. A particularly high one Pore volume results when helically profiled Monofilaments are present, the cross section of which Have several vaults distributed around the circumference. Vice versa can also bulges distributed over the circumference provided or both combined in such a way be that bulges and bulges over the scope spread alternately. It can also be helical provided sharp or rounded edges his.

It has proven beneficial if the profile of the helically profiled monofilament to 10 cm two to has forty courses, so the cross section of the monofilament rotates two to forty times on this length. Also about that Number of courses can be the pore volume and thus influence the drainage properties. You can also monofilaments with different numbers of courses be provided.

About the number of helically profiled monofilaments can also influence the pore volume and thus the Drainage capacity can be taken. Conveniently, should be at least 30% of the lengthways and / or in Crosswise extending scrim threads helically be profiled monofilaments, all longitudinal and / or Cross-laid threads can be such monofilaments.

Basically there is also the option of being helical to process profiled monofilaments into twists, for example in the way that several helical profiled monofilaments are twisted together. It but there is also the possibility of one or more helically profiled monofilaments with different shapes Monofilaments, for example stretched profiled monofilaments or round monofilaments and / or with multifilaments twisting.

There are no restrictions regarding the position of the carrier, i.e. the carrier can be single-layer or multi-layer be formed or from several, one below the other there are carrier webs not connected by threads, which are either the same or different are. The carrier can also be a woven, knitted fabric and / or have a network, as long as a layer from scrim is present.

For use in a press felt, it is advantageous if the support is embedded in a fiber matrix, in for example between at least two fiber layers is included, which are needled together. What As far as the material of the scrim threads is concerned, they can be used for paper machine clothing usual materials used become. These are in particular thermoplastic polymers, for example polypropylene, polyamide 4.6, polyamide 6, polyamide 6.6, polyamide 6.10, polyamide 6.12, polyamide 11, polyamide 12, PET, PTT, PBT, PPS, PEK or PEEK. Also elastomeric polyesters can be used.

Figur 1

einen Querschnitt durch einen Preßfilz mit Fadengelegen als Träger;

Figur 2

einen Teilausschnitt des Preßfilzes gemäß Figur 1 in der Schrägansicht, wobei die jeweils obere Lage gegenüber der jeweils unteren Lage verkürzt ist;

Figur 3

einen beflockten Gelegefaden;

Figur 4

einen Querschnitt durch ein Fadengelege mit beflockten Gelegefäden;

Figur 5

eine Ansicht eines als Zwirn mit eingeklemmten Fasern ausgebildeten Gelegefadens;

Figur 6

einen als Chenillefaden ausgebildeten Gelegefaden;

Figur 7

ein Teilstück eines Gelegefadens, ausgebildet als schraubenförmig profiliertes Monofil;

Figur 8

einen Querschnitt durch den Gelegefaden gemäß Figur 7;

Figuren 9 bis 17

verschiedene Querschnitte von Gelegefäden, die als schraubenförmig profilierte Monofile ausgebildet sind.

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

Figure 1

a cross section through a press felt with thread as a carrier;

Figure 2

a partial section of the press felt according to Figure 1 in an oblique view, the upper layer is shortened compared to the lower layer;

Figure 3

a flocked scrim;

Figure 4

a cross section through a scrim with flocked scrim;

Figure 5

a view of a laid as a thread with pinched fibers;

Figure 6

a scrim formed as chenille thread;

Figure 7

a portion of a scrim, formed as a helically profiled monofilament;

Figure 8

a cross section through the scrim according to Figure 7;

Figures 9 to 17

different cross-sections of scrim threads, which are designed as helically profiled monofilaments.

The press felt 1 shown in FIGS. 1 and 2 has one Carrier 2, which consists of three layers one on top of the other exists, each formed as a scrim 3, 4, 5 are. All three scrims 3, 4, 5 each consist of Laying threads running parallel in the plane of the press felt 1 - exemplified with 6, 7, 8 -, each have the same distance from each other. The scrim threads 6, 8 of the upper and lower scrims 3, 5 run thereby in the longitudinal direction of the press felt 1, which at the same time whose direction is, while the scrim 7 of middle scrim 4 extend transversely to it. The Carrier 2 is embedded in the middle in a fiber matrix 9, which is only shown in layers in FIG. 2 and was created by needling nonwovens.

The press felt 1 can already be seen in its final state, as it is used in the paper machine. characteristic are the distances between the scrim threads 6, 7, 8. These distances were caused by the fact that between the Laying threads 6, 7, 8 already during the manufacture of the carrier 2 spacer threads have been incorporated, their extension in the plane of the respective scrim 3, 4, 5 the in FIGS. 1 and 2, now clear distance which corresponded to scrim 6, 7, 8. The Spacer threads square or rectangular cross-section have had to slide spacer threads on top of each other and to avoid scrim 6, 7, 8.

The carrier 2 is then covered with non-woven fabrics and by ran a needle machine in which the nonwovens under Formation of the fiber matrix 9 matted and solidified together were. The spacer threads have ensured that there is no shifting of the scrim threads 6, 7, 8 has come. Then there are the spacer threads by the action of a solvent - with spacer threads from polyvinyl alcohol, water can be used as a solvent are - been detached, whereby the free ones Distances between the scrim threads 6, 7, 8 resulted.

FIG. 3 shows a laid thread 10 in the side view, which has a monofilament 11, which with essentially Fibers protruding perpendicularly from its surface - exemplary designated with 12 - is flocked.

FIG. 4 shows a laid scrim 13 with the laid thread 10 according to Figure 3, wherein the scrim 13 of a variety of side by side, parallel to each other extending scrim threads 10, the same distances to each other.

Figure 5 shows a scrim 14, which consists of a thread 15 with pinched between the individual threads of the thread 15, vertically protruding tufts of fibers - exemplary designated 16 - exists. It is understood that this Tufts of fibers 16 - similar to the laid scrim 13 see - are distributed over the circumference.

Figure 6 shows a scrim 17, the Chenille thread with a core thread 18 and essentially vertical thereof protruding fibers - designated by way of example at 19 - is trained.

A fabric thread 21 is shown in FIGS. which is designed as a monofilament and a rotationally symmetrical Cross section with a core 22 and overall six webs projecting radially outwards - exemplary designated 23 - is formed on their Ends are crowned widened. The webs 23 close deep indentations between them - exemplary at 24 designated - a, which in the laid thread 21 on the Form length grooves.

As can be seen from Figure 7, the profile of the scrim is 21 helically shaped, so from its outer Design twisted in itself, so that the webs 23rd and also the grooves formed by the concavities 24 extend helically around the core 22 of the laid thread 21. Are such laid threads 21 in the carrier of a This incorporates paper machine clothing Pore volume, with those formed by the concavities 24 Form grooves for drainage channels.

FIGS. 9 to 12 show other embodiments of Laying threads 25, 26, 27, 28 are shown. You are also rotationally symmetrical and have a different Number of radial webs - exemplary designated 29, 30, 31, 32.

In Figure 13, a scrim 33 is disclosed, the only is mirror symmetric. It has two opposite Arches 34, 35, on both sides in thickenings 36, 37 run out of different shapes.

In Figure 14 is a helically profiled scrim 38 shown, the rotationally symmetrical is and four bulges distributed over the circumference 39, 40, 41, 42, the bulges 39, 40, 41, 42 are connected via convex areas. Also at this profile results in groove-shaped depressions.

In Figures 15 to 17 more are helical profiled scrim threads 43, 44, 45 shown in cross section, with a regular pentagon (fig 15), a square (Figure 16) and a triangle (Figure 17). Even if the connection of the corners or edges of this Laying threads 43, 44, 45 form trenches due to the helical profile pore volumes and drainage channels.

Claims (37)

Paper machine clothing, in particular press felt (1), with a carrier (2) which has at least one layer of a laid scrim (3, 4, 5, 13) with parallel laying threads (6, 7, 8, 10, 14, 17, 21, 25, 26, 27, 28, 33, 38, 43, 44, 45), characterized in that spacing threads are present which are between two scrim threads (6, 7, 8, 10, 14, 17, 21, 25, 26 , 27, 28, 33, 38, 43, 44, 45) and are soluble in a solvent in which the remaining part of the paper machine clothing (1) is not soluble. Paper machine clothing according to claim 1, characterized in that the spacing threads run parallel to the laid threads (6, 7, 8, 10, 14, 17, 21, 25, 26, 27, 28, 33, 38, 43, 44, 45). Paper machine clothing according to claim 1 or 2, characterized in that the spacer threads are each wound around a laid thread or twisted with it in such a way that it protrudes on the outside. Paper machine clothing according to one of claims 1 to 3, characterized in that the spacer threads are water-soluble. Paper machine clothing according to one of claims 1 to 4, characterized in that laid threads are wound or twisted with spun yarn. Paper machine clothing according to one of claims 1 to 5, characterized in that laid threads (10, 14, 17) are provided with fibers (12, 16, 19) projecting outwards. Paper machine clothing according to claim 6, characterized in that the fibers (12, 16, 19) predominantly protrude at an angle to the surface of the laid threads (10, 14, 17) which deviates 0 ° to 60 ° from the normal to the surface. Paper machine clothing according to claim 6 or 7, characterized in that the fibers (12) are glued to the laid threads (10). Paper machine clothing according to claim 8, characterized in that the fibers (12) are flocked. Paper machine clothing according to one of claims 5 to 9, characterized in that the laid threads (14) are formed with chenille threads projecting outwards. Paper machine clothing according to one of claims 6 to 10, characterized in that the fibers (12, 16, 19) have a length of at least 0.5 mm, preferably 1 to 1.6 mm. Paper machine clothing according to one of claims 6 to 11, characterized in that the laid threads (10) are formed as monofilaments with the fibers projecting outwards. Paper machine clothing according to claim 12, characterized in that the monofilaments have a diameter of 0.3 to 0.6 mm. Paper machine clothing according to claim 12 or 13, characterized in that the monofilaments are roughened in such a way that fibers projecting outward from their material are formed. Paper machine clothing according to one of claims 6 to 14, characterized in that the laid threads (14) with fibers (16) projecting outwards are formed as twisted threads made of individual threads. Paper machine clothing according to claim 15, characterized in that the threads consist of two to twelve monofilament single threads, each with a diameter of 0.1 to 0.4 mm. Paper machine clothing according to claim 15 or 16, characterized in that the threads are designed as multifilaments. Paper machine clothing according to claim 15 or 16, characterized in that fibers (16) projecting outwards are clamped between the individual threads. Paper machine clothing according to one of claims 1 to 18, characterized in that laid threads (21, 25, 26, 27, 28, 33, 38, 43, 44, 45) are designed as helically profiled monofilaments. Paper machine clothing according to claim 19, characterized in that there are helically profiled monofilaments (21, 25, 26, 27, 28, 33, 38, 43, 44, 45) which are oval, trilobal, polygonal, square, rectangular, shamrock-shaped and / or triangular cross-section. Paper machine clothing according to claim 19 or 20, characterized in that helically profiled monofilaments (21, 33) are present, the cross section of which has a plurality of bulges (24, 34, 35) distributed over the circumference. Paper machine clothing according to one of claims 19 to 21, characterized in that there are helically profiled laid threads (38), the cross-section of which has a plurality of bulges (39, 40, 41, 42) distributed over the circumference. Paper machine clothing according to claim 21 and 22, characterized in that there are helically profiled scrim threads, the cross-section of which alternately has indentations and bulges distributed over the circumference. Paper machine clothing according to one of claims 19 to 23, characterized in that there are helically profiled scrim threads, the profile of which has helical sharp edges. Paper machine clothing according to one of claims 19 to 24, characterized in that there are helically profiled laid threads (21), the profile of which has helically rounded edges. Paper machine clothing according to one of claims 19 to 25, characterized in that the profile of the helically profiled laid threads (21, 25, 26, 27, 28, 33, 38, 43, 44, 45) has two to forty courses over a length of 10 cm. Paper machine clothing according to one of claims 1 to 26, characterized in that at least 30% of the laid threads extending in the longitudinal and / or transverse direction are helically profiled monofilaments (21, 25, 26, 27, 28, 33, 38, 43, 44, 45 ) are. Paper machine clothing according to one of claims 19 to 27, characterized in that there are threads in which a plurality of helically profiled monofilaments are twisted together or at least one helically profiled monofilament is twisted with other monofilaments and / or multifilaments. Paper machine clothing according to one of claims 1 to 28, characterized in that the carrier is constructed in one or more layers. Paper machine clothing according to one of claims 1 to 29, characterized in that the carrier consists of a plurality of carrier webs (3, 4, 5) which are not connected to one another by threads. Paper machine clothing according to one of claims 1 to 30, characterized in that the carrier has a woven fabric, a knitted fabric, and / or a network and additionally a scrim. Paper machine clothing according to one of claims 1 to 31, characterized in that the carrier (2) is embedded in a fiber matrix (9). Paper machine clothing according to claim 32, characterized in that the carrier (2) is enclosed between at least two fiber layers. Paper machine clothing according to one of claims 1 to 33, characterized in that the laid threads (6, 7, 8, 10, 14, 17, 21, 25, 26, 27, 28, 33, 38, 43, 44, 45) and optionally the spun yarns consist of a thermoplastic polymer such as polypropylene, polyamide 4.6, polyamide 6, polamide 6.6, polyamide 6.10, polyamide 6.12, polyamide 11, polyamide 12, PET, PTT, PBT, PPS, PEK, PEEK or an elastomeric polyester. Method for producing the paper machine clothing (1) according to one of claims 1 to 34, with a carrier (2) which has at least one laid scrim (3, 4, 5, 13) with parallel lay-up threads (6, 7, 8, 10, 14, 17, 21, 25, 26, 27, 28, 33, 38, 43, 44, 45), characterized in that in the manufacture of the scrim (3, 4, 5, 13) spacer threads are incorporated, which in are soluble in a solvent in which the remaining part of the paper machine clothing (1) is not soluble, and that the spacer threads are removed from the scrim (3, 4, 5, 13) using the solvent. A method according to claim 35, characterized in that the carrier (2) is first embedded in a fiber matrix (9) and only then are the spacer threads removed. A method according to claim 35 or 36, characterized in that water-soluble threads are used as spacer threads and that the spacer threads are removed by means of an aqueous liquid.

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