EP2314762B1

EP2314762B1 - Woven paper maker fabric

Info

Publication number: EP2314762B1
Application number: EP09013403A
Authority: EP
Inventors: Rex Barrett
Original assignee: Heimbach GmbH and Co KG
Current assignee: Heimbach GmbH and Co KG
Priority date: 2009-10-23
Filing date: 2009-10-23
Publication date: 2012-09-26
Anticipated expiration: 2029-10-23
Also published as: BRPI1004135A2; EP2314762A1; KR20110044704A; ES2392127T3; KR101265663B1; JP2011089247A; CN102041707A; PT2314762E; CN102041707B; JP5192021B2

Description

The invention relates to a woven paper maker fabric, in particular a forming fabric, having a first woven fabric layer provided for the paper side, made of first threads interwoven with one another which form recurring first woven fabric repeats, and a second woven fabric layer provided for the machine side made of second threads interwoven with one another which form recurring second woven fabric repeats, the woven fabric layers being connected to one another by first binder threads formed by first threads, the first threads extending in one direction being divided into first basic threads forming a plain weave with the first threads extending transversely thereto, and into the first binder threads forming a plain weave with the first threads extending transversely to the first binder threads section wise, the first binder threads bind just a single second thread extending transversely to the first binder threads at the binding points on the outside and in so doing change from the first woven fabric layer to the second woven fabric layer and back again, wherein three first threads extending transversely to the first binder threads are not bound by the latter at the binding points respectively.
Woven paper maker fabrics are intended to be used in the sections of a paper making machine as a support for the paper web. These are endless woven fabrics or fabrics made endless by means of a seam, which circulate in the paper making machine. In the first section of a paper making machine forming fabrics are used on the top layer of which a paper pulp is disposed at the start, and the latter is dewatered through the forming fabric such as to form a paper web.
Known as forming fabrics are woven paper maker fabrics which have two separate woven fabric layers disposed over one another, the first woven fabric layer, or the one on the paper side, being formed by first longitudinal and first transverse threads, and the second woven fabric layer, or the one on the machine side, being formed by second longitudinal and second transverse threads. In both woven fabric layers the first and second threads form recurring first and second woven fabric repeats. Examples of these type of woven paper maker fabrics suitable in particular for use in the web formation part of the paper making machine can be taken from WO 2005/014926 A1 , WO 2005/017254 A1 , WO 2006/083604 A1 , EP 0 794 283 A1 , EP 1 693 506 B1 , EP 1 586 696 B1 , EP 0 998 607 B1 , US 5,826,627 A , EP 1936024 A1 and EP 1 506 339 B1 .
The connection between the two woven fabric layers is realized with the aid of binding transverse threads which form part of the respective first thread repeat, i.e. unlike separate binder threads as disclosed in DE 3 305 713 C1 , form structural or intrinsic threads. The binding of the latter in accordance with the repeat of the first longitudinal threads is only interrupted at the binding points. Here, a binding transverse thread binds between two first longitudinal threads, which it binds on the outside (paper side), and between which it does not bind with further first longitudinal threads, a second longitudinal thread on the outside. For this purpose it changes from the first woven thread layer into the second woven thread layer, binds the second longitudinal thread and returns to the first woven thread layer again.
With the paper maker woven fabrics of the aforementioned type binding transverse threads are respectively woven in pairs, i.e. respectively always two binding transverse threads are arranged between two first basic threads which are not binder threads and which are bound with the first longitudinal threads in a plain weave regularly.
In the embodiment disclosed in EP 1 506 339 B1 the first binder threads are bound with the first longitudinal threads also in a plain weave, however interrupted at the binder points. Between a pair of adjacent binder threads an additional substitute weft thread is provided in order to complete the two yarn paths formed by the two adjacent binding transverse threads.
The known paper maker woven fabrics form regular drainage openings of rectangular or square shape. Nevertheless, the weave structure produces a disrupted plain weave surface. This impairs the sheet quality and creates markings in the paper web.
The object which forms the basis of the invention is to design a woven paper maker fabric, in particular for use in the web formation section of the paper making machine such that the drainage properties are improved and so the risk of development of marks in the paper web is reduced.
This object is achieved by the features of claim 1.
It is the basic idea of the invention to reduce the number of binder threads between two adjacent basic threads to one single binder thread. This generates a design with irregularly shaped drainage openings at the paper side, although they are uniformly distributed. Drainage openings formed between two adjacent first threads, i.e. between a first basic thread and a first binder thread, are in the shape of lenses with one flat and one concave surface. The elongate orientation of the drainage opening provides good fiber support, particularly if the first binder threads and basic threads are extending in cross machine direction, i.e. transversely. This special drainage surface pattern imparts a significantly different drainage structure to the paper sheet from that produced with a regular square drainage surface pattern.
In the embodiment of the invention provision is made such that the first binder threads extend as first binder transverse threads transversely to the provided running direction of the woven paper maker fabric and at the binding points bind just a single second longitudinal thread. This embodiment imparts a good fiber support which is important particularly if the paper maker fabric is designed as a forming fabric. Nevertheless, provision can be alternatively made such that the first binder threads extend as first binding longitudinal threads in the provided running direction of the woven paper maker fabric and bind just a single second transverse thread at the binding points.
In a further embodiment at the binding points the second threads being bound by the first binder threads and the first threads being parallel to the said second threads form respectively a pair of threads lying over one another and the first threads of such pairs are bound by the first basic threads adjacent to the first binder threads in the same way as the second threads by the adjacent first binder thread. Moreover, it is advantageous if the first binder threads are separated from the respective adjacent first binder thread by only one first basic thread extending parallel to the latter, because then two adjacent basic threads are distinctly approaching one to another at the binder points of the first binder thread extending between the two basic threads thus forming drainage openings with the shape of lenses. However, the number of first basic threads between two adjacent first binder threads can be more than one, for example two, three or four at most.
In another embodiment of the invention respectively at least one pair of first and second threads lying over one another extends at the binding points adjacent to the second thread being bound by the respective first binder threads and that the specific first binder threads pass between these two first and second threads upon changing the woven fabric layers.
In order to reduce the number of binder points, it can be provided that the first binder threads flow under the undersides of the first threads extending transversely to the first binder threads between in their extension two adjacent binder points and respectively symmetrically thereto, the number of these first threads corresponds to the number of the first threads extending parallel at the binder points, which are not bound by the respective first binder thread.
The basic idea behind the present invention is suitable for woven paper maker fabrics with which the first threads extending transversely to the first binder threads are present in a number of threads which is at least as great as the number of the second threads extending parallel to the latter, i.e. the ratio of the thread numbers of these first and seconds threads is 1:1. However, ratios of 2:1, 3:2, 1:2 or 2:3 can also be considered without any restriction being associated with this. Moreover, the ratio of the number of the first binder threads and of the first basic threads extending parallel to the first binder threads to the number of the second threads extending parallel to the first basic threads should amount to 1:1, 2:1 or 3:2.
The present invention does not exclude second binder threads formed by second threads from also being present in addition of the first binder threads. These advantageously extend transversely to the first binder threads and at the binder points bind with at least one first thread which extends transversely to the second binder threads.
Woven paper maker fabrics of the present type, i.e. fabrics with connection of the woven fabric layers by means of structural or intrinsic binder threads, are particularly suitable for woven fabrics, in which the second woven layer is woven to at least four-shaft or harnesses and at most 24-shaft, particularly six- or eight-shaft.
Suitable as materials for the threads are all of the synthetics which are generally used with woven paper maker fabrics, and in particular forming fabrics. It is advantageous that the threads extending in the provided running direction of the woven paper making fabric are made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN) or mixtures or copolymers of these materials. The threads extending transversely to the provided running direction should be made of PET, polyamide (PA) or mixtures or copolymers of these materials or blends of these materials with polyurethane (PU).
As regards to the cross-sectional shape of the threads, all known cross-sectional shapes are possible, in particular round, oval, rectangular cross-sections or those with other profiles. Moreover, threads can be provided which are twisted or braided from at least two monofilaments or multifilaments. Finally, threads can be used which are provided with a coating, in particular made of the urethane or acrylic, or using nanoparticles.
In the drawings the invention is illustrated by means of exemplary embodiments. These show as follows:

Figure 1: a cross-section through a first woven paper maker fabric;
Figure 2: a top view onto the paper side of the paper maker fabric shown in figure 1;
Figure 3: a cross-section through a second woven pa- per maker fabric;
Figure 4: a cross-section through a third woven paper maker fabric; and
Figure 5: a cross-section through a fourth woven pa- per maker fabric.

The woven paper maker fabric 1 shown in Figure 1 has a paper side, and so first woven fabric layer 2 and a machine side, and so second woven fabric layer 3. The two woven fabric layers 2, 3 are laid over one another.
The first woven fabric layer 2 is made up of first longitudinal threads extending in the running direction of the paper maker machine woven fabric 1 - identified for example by 4 - and of first transverse threads extending transversely to the latter, which both have a circular cross-section. The first transverse threads are composed of first transverse basic threads 5 and first transverse binder threads 6. These two kinds of threads 5, 6 alternate one to another in the direction of the first longitudinal threads 4. The first transverse basic threads 5 are interwoven with the first longitudinal threads 4 in a plain weave, while the first binding transverse threads bind with the first longitudinal threads 4 only section-wise between two adjacent binder points 7, 8 in a plain weave, i.e. over one first longitudinal thread 4, under the adjacent first longitudinal thread 4 and over the next first longitudinal thread 4.
The second woven fabric layer 3 is formed by second longitudinal threads extending in the running direction - identified for example by 9 - and by second transverse threads 10, of which just a single second transverse thread 10 is shown here. The second transverse threads 10 flows respectively on the outside, i.e. the machine side, under five second longitudinal threads 9 and then respectively bind one second longitudinal thread 9 in a knuckle 11. Due to the long floating segments of the second transverse threads 10 one talks of a weft runner. The second longitudinal threads 9 also have a circular cross-section as well as the second transverse threads 10.
The ratio of the numbers of threads between the first and second longitudinal threads 4, 9 is 1:1, i.e. only a single first longitudinal thread 4 extends above each single second longitudinal thread 9 forming pairs of first and second longitudinal threads 4, 9 lying one over the other.
The first transverse binder threads 6 bind second longitudinal threads 9 at the binder points 7, 8 in specific regular intervals in knuckles 12, 13 on the outside, i.e. on the machine side, thereby connecting the two woven fabric layers 2, 3. At every binder point 7, 8 the respective first transverse binder thread 6 passes between a pair 14 of a first and a second longitudinal thread 4, 9 lying over one another and then binds the next second longitudinal thread 9 on the outside, i. e. the machine side. Then the first transverse binder thread 6 passes again between a pair 15 of a first and a second longitudinal thread 4, 9 lying over one another and then binds the next first longitudinal thread 4 on the outside, i.e. the paper side and proceeds in a plain weave. At the following binder point 8 the first transverse binder thread 6 extends in the same manner. So at every binder point 7, 8 three adjacent first longitudinal threads 4 are not bound by the first transverse binder thread 6, but only by the two adjacent first transverse basic threads 5. Due to this pattern the first longitudinal thread 4 lying above the second longitudinal thread 9 being bound by the first transverse binder thread 6 is bound by the two first transverse basic threads 5 extending adjacent to the first transverse binder thread 6 under the underside of this first longitudinal thread 4.
Figure 2 shows the extension of the first longitudinal threads 4 (black colored), the first transverse basic threads 5 (dark grey colored) and the first transverse binder threads 6(bright grey colored). It is recognizable that the first transverse binder threads 6 are extending substantially straight, while the first transverse basic threads 5 have a wave-like extension. At binder points 7, 8, for example the binder point 7, the first transverse binder thread 6 changes to the second woven fabric layer 3 (in this figure not shown) so that the adjacent two first transverse basic threads 5 are forced by the first longitudinal threads 4 extending over the latter to approach to each other and hence, overlying the first binder thread 6 partly. The displacement of the first transverse basic threads 5 results in drainage openings - identified for example by 16 and 17 - having a shape of lenses with one flat surface formed by the next first transverse binder thread 6 and concave surface formed by the adjacent first transverse basic thread 5. These drainage openings 16, 17 are regularly distributed about the paper side of the first woven fabric layer 2 providing good fiber support due to their elongate orientation transverse to the running direction.
The woven paper maker fabric 21 illustrated in Figure 3 only differs a little from the paper maker fabric 1 according to Figure 1, and this is why the same reference numbers are used for the same parts. The only difference is that the binder point 8 of the woven paper maker fabric 1 is omitted so that the distance between two binder points 7 is doubled. Instead of the binder point 8, the first transverse binder thread 6 flows under three consecutive first longitudinal threads 4. A modification of the embodiment illustrated in Figure 3 would be, if the foregoing described floating is replaced by continuation of the plain weave so that the binding in plain weave extends between two binder points 7 uninterrupted.
The woven paper maker fabric 31 illustrated in Figure 4 also only differs slightly from the woven paper maker fabric 1 according to Figure 1, and so here too the reference numbers to be seen in Figure 1 are used for the same parts, and with regard to these parts, reference is made to the description of the woven paper maker fabric 1 according to Figure 1. The only difference is the ratio of the numbers of threads between the first and the second longitudinal threads 4, 9. The ratio is 1:2 here, the arrangement of the first and second longitudinal threads 4, 9 being such that only over every other second longitudinal thread 9 pairs 14, 15 of first and second longitudinal threads 4, 9 lying over one another are formed. Due to this design, the paper side of the first woven fabric layer 2 is more open and the drainage openings are more elongated compared with the drainage openings 16, 17 illustrated in Figure 2. As in the embodiment illustrated in Figures 1 to 3, the binder points 7, 8 can be displaced with respect to the knuckles 12, 13 of the second transverse threads 10.
The woven paper maker fabric illustrated in Figure 5 differs from the woven paper maker fabric 1 according to Figure 1 only with respect to the ratio of the numbers of the first longitudinal threads 4 and the second longitudinal threads 9. This is why here too the same reference numbers are used for the same parts. The ratio is here 3:2, i.e. every third second longitudinal thread 9 is omitted and the floats of the second transverse threads 10 extends under five second longitudinal threads 9 the distance of which are greater so that two binder points 7, 8 are created within a floating segment of the second transverse thread 10, i.e. between two adjacent knuckles 11.

Claims

A woven paper maker fabric (1, 21, 31, 41), in particular a forming fabric, having a first woven fabric layer (2) provided for the paper side, made of first threads (4, 5, 6) interwoven with one another which form recurring first woven fabric repeats, and a second woven fabric layer (3) provided for the machine side made of second threads interwoven with one another which form recurring second woven fabric repeats, the woven fabric layers (2, 3) being connected to one another by first binder threads (6) formed by first threads (5, 6), the first threads (5, 6) extending in one direction being divided into first basic threads (5) forming a plain weave with the first threads (4) extending transversely thereto, and into the first binder threads (6) forming a plain weave with the first threads (4) extending transversely to the first binder threads (6) section-wise, wherein only one single binder thread (6) is provided between two adjacent first basic threads (5) respectively, characterized in that the first binder threads (6) bind just a single second thread (9) extending transversely to the first binder threads (6) at the binding points (7, 8) on the outside and so doing change from the first woven fabric layer (2) to the second woven fabric layer (3) and back again, wherein three first threads (4) extending transversely to the first binder threads (6) are not bound by the latter at the binding points (7, 8) respectively.
A woven paper maker fabric according to claim 1, characterized in that the first binder threads (6) are disposed directly adjacent to two adjacent first basic threads (5) respectively, one first basic thread (5) on each side.
A woven paper maker fabric according to claim 1 or 2, characterized in that the first binder threads extend as first binder transverse threads (6) transversely to the provided running direction of the woven paper maker fabric (1, 21, 31, 41) and at the binding points (7, 8) bind just a single second longitudinal thread (9) or that the first binder threads extend as first binding longitudinal threads in the provided running direction of the woven paper maker fabric and bind just a single second transverse thread at the binding points.
A woven paper maker fabric according to any of claims 1 to 3, characterized in that at the binding points (7, 8) the second threads (9) being bound by the first binder threads (6) and the first threads (4) being parallel to the said second threads (9) form respectively a pair of threads lying over one another and the first threads of such pairs are bound by the first basic thread (5) adjacent to the first binder thread (6) in the same way as the second thread (9) by the first binder thread (6).
A woven paper maker fabric according to any of claims 1 to 4, characterized in that the first binder threads (6) are separated from the respective adjacent first binder thread (6) by one single first basic thread (5) extending parallel thereto or a number of these first basic threads, in particular the number of first basic threads (5) extending in parallel between two adjacent first binder threads (6) being 4 at most.
A woven paper maker fabric according to any of claims 1 to 5, characterized in that respectively at least one pair (14, 15) of first and second threads (4, 9) lying over one another extends at the binding points (7, 8) adjacent to the second thread (9) being bound by the respective first binder thread (6) and that the specific first binder thread (6) passes between these two first and second threads (4, 9) upon changing the woven fabric layers (2, 3).
A woven paper maker fabric according to any of claims 1 to 6, characterized in that the first binder threads (6) flow under the undersides of the first threads (4) extending transversely to the first binder threads (6) between in their extension two adjacent binder points (7) and respectively symmetrically to the latter, the number of the first threads (4) corresponds to the number of the first threads extending parallel at the binder points (7), which are not bound by the respective first binder thread (6).
A woven paper maker fabric according to claim 1 to 7, characterized in that the ratio of the number of the first threads (1) extending transversely to the first binder threads (6) to the number of the second threads (9) extending parallel to the latter amounts to 1:1, 2:1, 3:2, 1:2 or 2:3.
A woven paper maker fabric according to any of claims 1 to 8, characterized in that the ratio of the number of the first binder threads (6) and the first basic threads (5) extending parallel to the first binder threads (6) to the number of the second threads (10) extending parallel to the first basic threads (5) amounts to 1:1, 2:1 or 3:2.
A woven paper maker fabric according to any of claims 1 to 9, characterized in that additionally to the first binder threads second binder threads formed by second threads are provided which extend transversely to the first binder threads and at the binding points bind with at least one first thread which extends transversely to the second binder threads.
A woven paper maker fabric according to claims 1 to 10, characterized in that the second woven layer (3) is woven to at least four-shaft and at the most 24-shaft, in particular six- or eight-shaft.
A woven paper maker fabric according to any of claims 1 to 11, characterized in that the threads (4, 9) extending in the provided running direction of the woven paper maker fabric are made of PET, PEN or of mixtures or copolymers of these materials and/or the threads (5, 6, 10) extending transversely to the provided running direction are made of PET, PA or mixtures or copolymers of these materials or blends of these materials with PU or other material suitable for use in a paper maker fabric.
A woven paper maker fabric according to any of claims 1 to 12, characterized in that the threads (4, 5, 6, 9, 11) have around, oval, rectangular cross-section or one with a different profile.
A woven paper maker fabric according to any of claims 1 to 13, characterized in that threads (4, 5, 6, 9, 11) are provided, which are twisted or braided from at least two monofilaments or multifilaments and/or which are provided with a coating, in particular made of urethane or acrylic or using nanoparticles.