WO2015149992A1

WO2015149992A1 - Papermaking fabric

Info

Publication number: WO2015149992A1
Application number: PCT/EP2015/053693
Authority: WO
Inventors: Matthias Hoehsl; Scott D. Quigley
Original assignee: Voith Patent Gmbh
Priority date: 2014-04-02
Filing date: 2015-02-23
Publication date: 2015-10-08
Also published as: DE112015001650T5

Abstract

The invention relates to apapermakers fabric for a fibrous web forming and/or processing machine, the fabric comprises a first side and a second side opposing the first side, a machine direction and a cross-machine direction, a plurality of machine direction yarns interweaving with a plurality of cross-machine direction yarns to form a weave pattern on the first side, repeated in a pattern repeat, per pattern repeat each of the machine direction yarnsforming several MD-floats on the first side which are consecutive in machine direction, each MD-float being formed by passing of a machine direction yarn on the first side over a plurality of adjacent cross-machine direction yarns, the weave pattern comprises a plurality of compression regions separated by valleys recessed relative to the compression regions, each of the compression regions being formed by a plurality of MD-floats adjacently arranged in cross-machine direction, the MD-floats forming a compression region at least partially overlap each other in machine direction, at least a majority of them being offset relative to each other in the machine direction. The fabric of the invention is characterized in that at least one compression region has at least one first group of MD-floats and at least one second group of MD-floats, the at least one first group being formed by a first number of adjacent MD-floats and the at least one second group being formed by a second number of adjacent MD-floats, and the average offset of the MD-floats in the at least one first group is smaller than the average offset of the MD-floats in the at least one second group.

Description

Papermaking fabric

Technical Field The present invention relates to a papermakers fabric for use in the manufacturing of a fibrous web, like paper, board, tissue or non-woven webs. The present invention especially relates to a papermakers fabric used to produce structured tissue paper or non-woven webs for hygiene or wiping products. A tissue paper is defined as a soft absorbent paper (softer than graphical or cardboard paper and having a higher tensile energy absorption index than graphical or cardboard paper; see DIN EN 12625-4 and DIN EN 12625-5) with a basis weight of between 8 to 40 g/m², preferably 10 to 25 g/m² per ply. A tissue paper can be mainly formed from natural fibers, such as cellulosic fibers.

The term non-woven web (ISO 9092, DIN EN 29092) applies to a wide range of products which, in terms of their properties, are located between those of paper (cf. DIN 6730, May 1996) and cardboard (DIN 6730) on the one hand and textiles on the other hand. A non-woven web can be mainly formed from natural fibers or synthetic fibers or a mixture thereof.

Especially tissue paper or non-woven webs for hygiene or wiping products need to have a structure providing bulky regions of lower density with good absorbency for liquids and less bulky regions of higher density with good tensile strength .

To manufacture such structured fibrous webs papermakers fabrics having a paper contacting side with elevated compression regions and valleys which separate the compression regions and which are recessed relative to the compression regions are used (also called structured fabrics) to impart to the tissue paper or non-woven web a structure having bulky regions with high absorbency and compressed regions with high tensile strength.

For manufacture such structured fibrous webs it is possible to form the web from a fibrous slurry on the such a structured fabric or to impart the bulky and high tensile strength regions by moulding or converting a already formed fibrous web on such a structured fabric.

Background Art

US 6,039,838 shows a structured fabric with a plurality of continuous compression regions extending in machine direction and separated by valleys. According to EP^'332 the compression regions are formed by floats of machine direction yarns (hereinafter called MD-floats) grouped together and constantly offset relative to each other. The web or paper processed on these fabrics has bulky areas and compressed areas with in essence constant width. This leads to a tissue paper or non- woven web with a high tensile strength in machine direction but a weak tensile in cross-machine direction.

In addition to this the optical appearance, which is an important feature for recognition of hygiene or wiping products at the end customer side, for fibrous webs produced on a fabric as shown in US6,039,838 is very similar to a high number of already existing tissue papers or non-woven webs. It is therefore difficult to successfully establish a market position for a new hygiene or wiping product produced on a fabric according to US ^'838. US 7,585,393 discloses a structured fabric with a weave pattern having squared compression regions, adjacently arranged in offset position in machine and cross-machine direction. Due to the relatively short compression regions in machine direction tissue paper or non-woven webs produced on such a fabric show relatively low tensile strength and low bulk . What is needed is an improved papermakers fabric with a good tensile strength in machine direction combined which are better interlinked with each other in cross-machine direction.

Description of the Invention

Taking the aforesaid into account it is an object of the present invention to provide a papermakers fabric to manufacture tissue paper or non-woven webs with improved tensile strength in machine and in cross-machine direction.

This object is solved by a papermakers fabric as defined in claim 1, claim 37 and claim 45. According to a first aspect of the present invention a papermakers fabric is provided having a first side and a second side opposing the first side and a machine direction and a cross-machine direction. For explanation the expression "machine direction" stands for the direction in which the fabric moves during the papermaking process. The expression "cross-machine direction" describes the direction perpendicular to the machine direction. It is further to be noted that the terms "fabric" and "papermakers fabric" are used as synonyms. The fabric further has a plurality of machine direction yarns interweaving with a plurality of cross-machine direction yarns to form a weave pattern which is repeated in pattern repeats at the first side. The length extension of the "machine direction yarns" is mainly in machine direction, what means that their length extension can deviate maximum by -/+ 30° from the machine direction of the fabric. The length extension of the "cross-machine direction yarns" is mainly in corss-machine direction, what means that their length extension can deviate maximum by -/+ 30° from the cross-machine direction of the fabric. A "pattern repeat" is the smallest unit of the weave pattern in machine and cross- machine direction. The weave pattern is formed by repeating or dublicating the pattern repeat. In the pattern repeat each of the machine direction yarns forms several machine direction floats on the first side (hereinafter called MD-floats) , which are consecutive in machine direction. Each MD-float of a machine direction yarn is formed by passing of the respective machine direction yarn on the first side over a plurality of adjacent cross-machine direction yarns. If yarns of one type - machine direction yarns or cross-machine direction yarns- are adjacent yarns, no other yarn of the same type is located between. Between two consecutive MD-floats of a machine direction yarn the machine direction yarn forms at least a knuckle and/or a float on the second side.

The term "float" is used therein if a yarn of one type (machine direction or cross- machine direction yarn) passes on one side of the fabric over at least two adjacent yarns of the other type of yarns (cross-machine direction yarn or machine direction yarn), e.g. if a machine direction yarn passes on the first side over two adjacent cross-machine direction yarns it forms on the first side a MD-float over two cross-machine direction yarns. In contrary to the term "float" the term "knuckle" is used if a yarn of one type passes on one side of the fabric over only one yarn of the other type. Each MD-float starts with a first of the adjacent cross-machine direction yarns, the machine direction yarn passes over on the first side, after coming from the second side, and ends with a last of the adjacent cross-machine yarns, the machine direction yarn passes over on the first side, before disappearing to the second side.

The pattern repeat further comprises a plurality of compression regions. Each compression region is formed by a plurality of MD-floats which are adjacently arranged in cross- machine direction. The adjacent MD-floats which form the respective compression region at least partially overlap each other in machine direction and at least a majority of them is offset relative to each other in machine direction in such a way, that the compression region extends in its length extension diagonally (angled) relative to the machine and cross-machine direction. If two MD-floats -they are formed on the first side of the fabric- are adjacently arranged in cross-machine direction, they are formed by two adjacent machine direction yarns.

The term "majority" means that more than 50%, preferably at least 75%, more preferably at least 85% of the adjacent MD- floats forming the respective compression region are offset relative to each other.

Two adjacent MD-floats are "offset" relative to each other if the "centers" of the two adjacent MD-floats are shifted relative to each other in machine direction. The "center" of a MD-float is half the length of the respective MD-float. The "length" of a MD-float or "float length" is determined by the number of adjacent cross-machine direction yarns the machine direction yarn passes over on the first side when forming the MD-float .

The compression regions are separated by valleys which are recessed relative to the compression regions on the first side. It has to be noted that in regard to the finished paper web or non-woven web, which has been produced on the papermaker^'s fabric, the areas of the web which have been in contact with the compression regions are compressed and/or contain lower basis weight compared to the areas of the web which have been in contact with the valleys.

The first aspect of the invention is characterized in that at least one compression region has at least one first group of MD-floats and at least one second group of MD-floats, wherein the at least one first group is formed by a first number of adjacent MD-floats and the at least one second group is formed by a second number of adjacent MD-floats, and wherein the average offset of the MD-floats in the at least one first group is less than the average offset of the MD-floats in the at least one second group.

The "average offset" of a group is calculated by summing up all offsets between adjacent MD-floats forming the respective group divided by the number of offsets in the group.

If, for example, a group is formed by seven (7) MD-floats the group has six (6) offsets (offset from 1^st to 2^nd MD-float, offset from 2^nd to 3^rd MD-float, offset from 3^rd to 4^th MD-float, offset from 4^th to 5^th MD-float, offset from 5^th to 6^th MD-float and offset from 6^th to 7^th MD-float) . If the offset in this example is 1 for all adjacent MD-floats (offset from 1^st to 2^nd MD-float is 1, offset from 2^nd to 3^rd MD-float is one, ..., offset from 6^th to 7^th MD-float is 1), than the average offset is one (1) . If in the above example the offset between the 2^nd and 3^rd MD-float is three (3) and all the other offsets are the same as described above, then the average offset would be one point three three (1,33) .

By providing at least one compression region with a first and a second group of MD-floats, wherein the MD-floats forming the first group have a smaller average offset than the MD-floats forming the second group, the compression region can get wavy outer contour with a varying width. This leads, in contrast to compression regions along straight lines, to a more inhomogenious arrangement of the high bulk and high tensile strength regions for the tissue paper or non-woven web produced on such a fabric. Therefore a fibrous web with better tensile strength in machine and in cross-machine direction is provided. Due to the fact that the compressed regions of the fibrous web, which have been produced on a fabric according to the invention, extend in a bended like row, the transition area between an uncompressed high bulk region and an compressed high tensile strength region is much longer, compared to a straight lined transition area. Therefore a tensile force acting on the fibrous web is distributed along a longer way. This leads to the benefit that such transition areas are less weak compared to paper produced on fabrics known from prior art. Preferably the majority of the compression regions, most preferably each compression region comprises at least one first and second group of MD-floats.

The average offset of the MD-floats in the at least one first group may be between 0 and 2,5, preferably between 0,5 and 2. Further on, the average offset of the MD-floats in the at least one second group may be between 1,2 and 4.

The offset of the adjacent MD-floats in the at least one first group may be such that the adjacent MD-floats overlap each other in machine direction by at least half of their float length. Preferably at least 50%, more preferably at least 75%, of all adjacent MD-floats forming a compression region have an overlap of at least three consecutive cross-machine yarns.

According to a preferred embodiment of the first aspect the second number may be smaller than the first number, what means, that the second group with the bigger average offset is formed by less MD-floats than the first. It is possible a majority of the compression regions is formed by at least 10 adjacent MD-floats. It is further possible, that all MD-floats which form a compression region are offset relative to each other in machine direction.

More concrete it may be possible, that each of the first groups is formed by at least four adjacent MD-floats, preferably at least six adjacent MD-floats and/or that each of the second groups is formed by maximum eight adjacent MD- floats, preferably by maximum six adjacent MD-floats.

As an example the first groups may consist of between 4 and 20 adjacent MD-floats, preferably between 6 and 15 adjacent MD- floats. It also may be possible, that the second groups consist of between 2 and 10 adjacent MD-floats, preferably between 3 and 6 adjacent MD-floats.

The first and second groups can be arranged alternatingly . The term "alternatingly" means in this context, that between two adjacent first groups a second group is arranged and vice versa. The first and the second groups also can be consecutive. The term "consecutive" means in the context, that between a first and a second group a MD-float can be located, not belonging to one of these groups.

Preferably the compression regions are adjacently arranged in machine direction and/or cross-machine direction, wherein between two adjacent compression regions a valley is located separating them. The compression regions can provide at least one continuous compression region and/or at least one discontinuous compression region.

The width of each of the continuous compression regions preferably is less than the half, more preferably less than one third (1/3), most preferably less than one fifth (1/5), than the width of the pattern repeat.

A continuous compression region may have a length which spans over at least the length of a pattern repeat, without being interrupted by a valley. The "length of a compression region" may be the biggest extension the compression region has along a straight line selected from all possible straight lines in the plane of the machine and cross-machine direction. The "width of a compression region" may be the biggest extension the compression region has between the two valleys bordering it, along a straight line in the plane of the machine and cross-machine direction which is perpendicular to the straight line of the length. The "length of the pattern repeat" is the extension of the pattern repeat in machine direction. The "width of the pattern repeat" is the extension of the pattern repeat in cross-machine direction. Two continuous compression regions, which are adjacently arranged in cross-machine direction, may be separated by valleys. Preferably the continuous compression regions extend in such a way, that, if several adjacently arranged pattern repeats are regarded, the continuous compression region extends over the length or the width of the fabric. By doing so, the papermakers fabric has a network of compression regions and valleys continuously spanning in a bended or undulating manner over the whole fabric. This gives the fibrous web, which has been produced with such a fabric, a balanced distribution of bulky regions with high absorbency and compressed regions with high tensile strength in machine direction as well as in cross-machine direction. The continuous compression regions spanning over the length of the fabric further have the advantage that during a creping step the fibrous web is constantly supported. This leads to much better creping in regard to bulkiness.

A discontinuous compression region may be surrounded by a valley, separating the discontinuous compression region on all sides from adjacent compression regions.

Preferably the first and second groups of MD-floats contribute in forming at least one of the continuous compression regions. In other words, at least one compression region has at least one first group of MD-floats and at least one second group of MD-floats. More preferably more than 50%, preferably more than 70%, of the MD-floats forming the at least one continuous compression region are arranged in one of the first and second groups. The continuous compression regions can be formed by at least 10 adjacent MD-floats.

The at least one discontinuous compression region can be formed by a number of MD-floats, adjacently arranged in cross- machine direction and off-set relative to each other in machine direction. Preferably the number of MD-floats forming the at least one continuous compression region may be greater than the number of MD-floats forming the at least one discontinuous compression region. It may be possible that the number of MD-floats forming the at least one discontinuous compression region is less than half, preferably less than one third, the number of MD-floats forming the at least one continuous compression region. In concrete the at least one discontinuous compression region may be formed by no more than six MD-floats, preferably no more than four MD-floats. The average length of the MD-floats and/or the maximum length of the MD-floats and/or the length of each MD-float forming the at least one discontinuous compression region may be less than the first and/or second float length. The term "average float length" is calculated by summing up the float lengths of all MD-floats forming the respective discontinuous compression region divided by the number of MD-floats forming the discontinuous compression region. The outer contour of the continuous compression regions may be wavy. The fabric further may have, has regarded in cross- machine direction, between 1 and 10, preferably between 3 and 8 continuous compression regions per pattern repeat.

The MD-floats which form a first group may have a first average float length and the MD-floats which form the second group may have a second average float length, wherein the individual length of the MD-floats forming the first group deviate from first average float length by not more than 25% and/or the individual length of the MD-floats forming the second group deviate from the second average float length by not more than 25%.

According to a further preferred embodiment of the first aspect of the present invention the first groups may be formed by first MD-floats and the second groups are formed by second MD-floats, wherein the first MD-floats have a first float length and the second MD floats have a second float length. It may be possible that the first float length is different to the second float length. Depending on the specific requirement on the papermakers fabric it can be advantageous if the first float length is bigger than the second float length.

According to a concrete example, a first group can consist of six (6) MD-floats with a float length of seven (7) and a second group may consist of four (4) MD-floats with a float length of five (5) .

Alternatively the first float length may be less than the second float length. According to a concrete example of this embodiment a first group may consist of five (5) MD-floats with a float length of five (5) and a second group may consist of three (3) MD-floats with a float length of seven (7) .

According to a further preferred embodiment the pattern repeat may comprise at least one machine direction yarn forming a plurality of first MD-floats consecutive in machine direction and at least another machine direction yarn forming a plurality of second MD-floats consecutive in machine direction. Two first MD-floats which are consecutive in machine direction can be separated by another MD-float not being a first MD-float. Two second MD-floats which are consecutive in machine direction can be separated by another MD-float not being a second MD-float. More concrete the pattern repeat may comprise a plurality of first machine direction yarns, each of the first machine direction yarns may form a plurality of first MD-floats adjacent in machine direction and/or the pattern repeat may comprises a plurality of second machine direction yarns, each of the second machine direction yarns form a plurality of second MD-floats adjacent in machine direction. Two first MD- floats are adjacent in machine direction if no other MD-float is located between them, preferably if neither another MD- float nor a float on the second side is located between them. Two second MD-floats are adjacent in machine direction if no other MD-float is located between them, preferably if neither another MD-float nor a float on the second side is located between them. Further on or alternatively the pattern repeat may comprise a plurality of third machine direction yarns, each of the third machine direction yarns form at least one first and at least one second MD-float consecutive in machine direction.

The consecutive or adjacent MD-floats of each of the machine direction yarns may be separated by a separation area, each of which may be formed by at least one knuckle and/or float of the machine direction yarn on the second side.

More concrete at least some of the separation areas may be formed by one of i) a plain weave sequence of a machine direction yarn with at least three adjacent cross-machine direction yarns and ii) a float of a machine direction yarn on the second side over at least two adjacent cross-machine direction yarns and iii) a knuckle of a machine direction yarn on the second side over one cross-machine direction yarns and iv) two consecutive knuckles of a machine direction yarn on the second side each over one cross-machine direction yarn, being separated from each other by a float of the machine direction yarn over maximum four adjacent cross-machine direction yarns on the first side.

Preferably the length of the MD-float under iv) of a separation area is equal or less than the minimum float length of the MD-floats forming the neighboring compression region (s) .

The separation areas of all machine direction yarns together may contribute to form or form the recessed valleys. The separation areas of adjacent machine direction yarns either overlap each other in machine direction or are adjacently arranged in machine direction.

According to a further preferred embodiment of the first aspect of the present invention a center connection line connecting the centers of all adjacently arranged MD-floats forming the respective compression region mainly runs angled relative to the machine and cross-machine direction. To provide continuous regions mainly running in machine direction the center connection line mainly runs in the machine direction . The center connection line may be non-straight, preferably has at least two turning points. Further on the center connection lines of all continuous compression regions may run in parallel relative to each other.

According to a second aspect of the present invention a papermakers fabric which is in addition to the features of the preamble of claim 1 characterized in that, for at least one of the compression regions each of the MD-floats have a center of the float, wherein a first center line connecting the centers of first two adjacent MD-floats is angled to the machine direction at a first angle and a second center line connecting the centers of second two adjacent MD-floats is angled to the machine direction at a second angle, the second angle being different to the first angle.

It has to be noted, that the aforementioned center connection lie of a respective compression area is formed by all center lines of the MD-floats forming the compression area.

Preferably a line, which connects the centers of more than five adjacent MD-floats is not straight and preferably has at least two turning points.

According to a third aspect of the present invention a papermakers fabric for a fibrous web forming and/or processing machine is provided, having a first side and a second side opposing the first side, a machine direction and a cross- machine direction and a plurality of machine direction yarns interweaving with a plurality of cross-machine direction yarns to form a pattern repeat at the first side. Per pattern repeat each of the machine direction yarns form several MD-floats consecutive in machine direction and separated from each other by separation areas, wherein each MD-float is formed by passing of a machine direction yarn on the first side over a plurality of adjacent cross-machine direction yarns, each separation area being formed by at least one float of the machine direction yarn on the second side over at least one cross-machine direction yarn. The fabric according to the third aspect is characterized in that the pattern repeat comprises a plurality of first machine direction yarns and a plurality of second machine direction yarns, the first machine directions yarns forming first MD-floats separated by first separation areas and the second machine direction yarns forming second MD-floats separated by second separation areas. The first MD-floats have a first float length which is longer in machine direction than the float length of the second MD- floats. The first separation areas are shorter in machine direction than the second separation areas. According to a preferred embodiment of the third aspect per pattern repeat the first machine direction yarns form at least one, preferably a plurality of, group (s) of adjacently arranged first machine direction yarns and/or the second machine direction yarns form at least one, preferably a plurality of, group (s) of adjacently arranged second machine direction yarns.

Preferably the first group (s) and the second groups are alternatingly arranged in machine direction and/or cross- machine direction. Further on adjacent first machine direction yarns in the first group (s) may be offset relative to each other in machine direction and/or adjacent second machine direction yarns in the second group (s) may be offset relative to each other in machine direction. Preferably at least some, most preferably all of the separation areas may be formed by a plain weave sequence of the machine direction yarn with at least three consecutive cross-machine direction yarns. More concrete the first machine direction yarns may form first separation areas, each of which being formed by a plain weave sequence with at least three consecutive cross machine direction yarns and/or the second machine direction yarns may form second separation areas, each of which being formed by a plain weave sequence with maximum 15 consecutive cross machine direction yarns. According to a forth aspect of the present invention a papermakers fabric for a fibrous web forming and/or processing machine is provided. The fabric comprises a first side and a second side opposing the first side, a machine direction and a cross-machine direction and a plurality of machine direction yarns interweaving with a plurality of cross-machine direction yarns to form a pattern repeat at the first side. Per pattern repeat each of the machine direction yarns forming several MD- floats consecutive in machine direction and separated from each other by separation areas, each MD-float being formed by passing of a machine direction yarn on the first side over a plurality of consecutive cross-machine direction yarns, each separation area being formed by at least one float of the machine direction yarn on the second side over at least one cross-machine direction yarn. The fabric according to the forth aspect of the present invention is characterized in that the pattern repeat comprises a plurality of third machine direction yarns. Each of the third machine direction yarns form at least one first MD-float with a first float length and at least one consecutive second MD-float with a second float length. The first length is smaller than the second length and the first and second MD-floats are separated by a third separation area, which is formed by one of a plain weave sequence of the third machine direction yarn with at least three consecutive cross-machine direction yarns and a float of the third machine direction yarn on the second side over one cross-machine direction yarn.

According to a preferred embodiment of the forth aspect, the pattern repeat may comprise a plurality of first machine direction yarns, each of which form a plurality of first MD- floats consecutive in machine direction.

All fabrics according to the aforementioned different aspects of the present invention may be a single layer fabric. The first side of these fabrics may provide a paper contacting surface and the second side may provide a machine contacting surface. All of these fabrics might be used in a forming or drying position of a papermaking or non-woven web making machine. If the fabric is used in a drying position, it can be a so called "Trough Air Dryer" (TAD) fabric. Further at least some, preferably all, machine direction yarns which form the MD-floats, may have a flattened cross section.

Description of the Drawings: The invention will be further described by way of non-limiting drawings, showing two preferred embodiments of fabrics according to the present invention. As follows

Fig. 1 shows a schematic view of a pattern repeat on the first side of a fabric according to a first embodiment of the present invention,

Fig. 2 shows a photograph onto the first side of the fabric from Fig. 1,

Fig. 3 shows a schematic view of a pattern repeat on the first side of a fabric according to a second embodiment of the present invention and

Fig. 4 shows a photograph onto the first side of the fabric from Fig. 3.

The fabric 100 as shown in figures 1 and 2 is a single layer fabric consisting of a system of cross-machine direction yarns (hereinafter called CD-yarns) A to T interwoven in a pattern repeat with a system of machine direction yarns (hereinafter called MD-yarns) 1 to 20. The pattern repeat consists of 20 MD-yarns x 20 CD-yarns. The fabric 100 has a first side 101 and a second side opposing the first side and a machine direction MD and a cross-machine direction CD.

Figure 1 shows a schematic view of a pattern repeat onto the first side 101 of the fabric 100. Each dark box in figure 1 indicates, when a MD-yarn passes on the first side 101 over a CD-yarn. Each bright box in figure 1 indicates, when a MD-yarn passes on the second side over a CD-yarn or in other words when a CD-yarn passes on the first side 101 over a MD-yarn.

Fig. 2 shows a photograph onto the first side 101 of the fabric 100 from Fig. 1, wherein more than one pattern repeat is shown. A part of the features described in the following are highlighted in figure 2. In the pattern repeat each of the MD-yarns 1 to 20 form several MD-floats Fl or F2, which are consecutive in machine direction MD. The consecutive MD-floats Fl, F2 of the MD-yarns

I to 20 are separated by separation areas SI, S2, each of which being formed by passing of the respective MD-yarn on the second side over at least one CD-yarn A to T.

For example MD-yarn 11 forms per pattern repeat two first MD- floats Fl with a float length of seven CD-yarns T + A to F + J to P. The first MD-floats Fl of the respective MD-yarn 11 are separated by separation areas SI. The separation areas SI are formed by a plain weave sequence of a machine direction yarn

II with three adjacent cross-machine direction yarns G, H, I and Q, R, S. The same applies for MD-yarns 1 to 3, 8 to 13 and 18 to 20, which all form first floats Fl which are separated by first separation areas SI. MD-yarns 1 to 3, 8 to 13 and 18 to 20 are called first MD-yarns. In the case of first MD-yarns the first MD-floats Fl are adjacently arranged in machine direction MD, because between the first MD-floats Fl of the same first MD-yarn no other MD-floats are located. Further each of the MD-yarns 5 to 7 and 14 to 17 forms per pattern repeat two second MD-floats F2 with a float length of five CD-yarns (e.g. MD-yarn 7 forms a second MD-float F2 over the adjacent CD-yarns D to H and another second MD-float F2 over the adjacent CD-yarns N to R) . The second MD-floats F2 of the respective MD-yarn are separated by second separation areas S2. The second separation areas S2 are formed by a plain weave sequence of the respective machine direction yarn with five adjacent cross-machine direction yarns (e.g. MD-yarn 7 forms a second separation area with CD-yarns A to C + S to T and another second separation area with CD-yarns I to M) . MD- yarns 5 to 7 and 14 to 17 are called second MD-yarns. In the case of second MD-yarns the second MD-floats of the same second MD-yarn are adjacently arranged in machine direction MD, because between the second MD-floats F2 there are no other MD-floats .

The weave pattern comprises a plurality of continuous compression regions, a part of a continuous compression region is visible and indicated by a dashed line supplied with the reference sign CR. The MD-floats forming a continuous compression region are adjacently arranged in cross-machine direction CD and offset relative to each other in machine direction MD. The continuous compression regions CR are formed by the first and the second MD-floats Fl, F2. The first and second separation areas SI, S2 together form valley V separating the adjacent compression regions CR. The continuous compression regions CR extend with its length at least over the length of the pattern repeat without being interrupted by a valley V. The continuous compression regions CR extend diagonally relative to the machine and cross-machine direction. The outer contour of the continuous compression regions CR is wavy.

As shown in figure 1, the first MD-yarns 8 to 13 form a first group of first MD-floats Fl which all have a first float length of seven CD-yarns. Adjacently to the first group of first MD-floats a second group of second MD-floats F2 is located, which is formed by the MD-yarns 4 to 7. All second MD-floats have a second float length of five CD-yarns, which is less than the first float length. As can be seen the continuous compression region CR has at least one first group of MD-floats 8 to 13 and at least one second group of MD- floats 4 to 7. The at least one first group is formed by a first number of first MD-floats Fl, adjacently arranged in cross-machine direction CD. The first number is in the current case six (6) . The at least one second group of second MD- floats F2 is formed by a second number of second MD-floats F2, adjacently arranged in cross-machine direction CD. The second number is which is in the current case four (4) . The first and second groups are arranged alternatingly . The average offset of the first MD-floats Fl in the first group is 1,4 (=[ 1+1+3+1+1 ] /5 ) and the average offset of the second MD- floats F2 in the second group is 3 (= [3+3+3] /3) . Therefore the average offset in the first group is less than the average offset in the second group.

In addition the first MD-floats Fl, which form the first group have a first average float length, which is in this case seven (7) CD-yarns, and the second MD-floats F2, which form the second group have a second average float length, which is in this case five (5) CD-yarns. As it is clearly visible the individual length of the MD-floats forming the first group do not deviate from first average float length and the individual length of the MD-floats forming the second group do not deviate from second average float length.

Further is can be seen that each of the MD-floats Fl, F2 have a center "X" of the float. If the centers "X" of first two adjacent MD-floats are connected by a straight line (e.g. the center of the second MD-float F2 formed by third MD-yarn 9 and the center "X" of the second MD-float F2 formed by third MD- yarn 10) a first center line (dotted line) is created, being at a first angle relative to the machine direction MD . If the centers "X" of second two adjacent MD-floats are connected by a straight line (e.g. the center of the second MD-float F2 formed by third MD-yarn 10 and the center "X" of the first MD- float Fl formed by first MD-yarn 11) a second center line (dotted line) is created, being at a second angle relative to the machine direction MD, which is different to the first angle . By connecting all the center lines of the MD-floats forming the respective continuous compression region CR a center connection line CLC is created, which mainly runs angled relative to the machine and cross-machine direction MD, CD. The center connection line CLC is non-straight and has at least two turning points. In addition the outer contour of the continuous compression regions is wavy.

The fabric 100 as shown in figures 3 and 4 is a single layer fabric consisting of a system of CD-yarns A to R interwoven in a pattern repeat with a system of MD-yarns 1 to 20. The pattern repeat consists of 20 MD-yarns x 18 CD-yarns. The fabric 100 has a first side 101 and a second side opposing the first side and a machine direction MD and a cross-machine direction CD.

Figure 3 shows a schematic view of a pattern repeat onto the first side 101 of the fabric 100. Each dark box in figure 3 indicates, when a MD-yarn passes on the first side 101 over a CD-yarn. Each bright box in figure 3 indicates, when a MD-yarn passes on the second side 101 over a CD-yarn or in other words when a CD-yarn passes on the first side 101 over a MD-yarn.

Fig. 4 shows a photograph onto the first side 101 of the fabric from Fig. 3, wherein more than one pattern repeat is shown . The pattern repeat comprises a plurality of first MD-yarns, each of the first MD-yarns, e.g. 10 to 12, forming a plurality of consecutive first MD-floats Fl . The pattern repeat further comprises a plurality of third MD-yarns, e.g. 8, 9 13, 14, each of the third MD-yarns forming at least one first MD-float Fl and at least one consecutive second MD-float F2.

The consecutive MD-floats Fl, F2 of each of the MD-yarns 1 to 20 are separated by first separation areas SI or by second separation areas S2 or by third separation areas S3 or by forth separation areas S4 or by fifth separation areas S5. The first and second separation areas SI, S2 are the same as in the previous embodiment shown in fig.^'s 1 and 2. The third separation areas S3 are formed by two consecutive knuckles of a MD-yarn on the second side each over one cross-machine direction yarn, which are separated from each other by a float of the MD-yarn over three adjacent CD-yarns on the first side. The forth separation areas S4 are formed by a knuckle of a MD- yarn on the second side over one CD-yarn. The fifth separation areas S5 are formed by a float of a MD-yarn on the second side over two adjacent CD-yarns.

The weave pattern comprises a plurality of continuous compression regions, a part of a continuous compression region is visible and indicated by a dashed line supplied with the reference sign CR. The MD-floats forming a continuous compression region CR are adjacently arranged in cross-machine direction CD and offset relative to each other in machine direction MD. The continuous compression regions CR are mainly formed by the first and the second MD-floats Fl, F2. The first to fifth separation areas SI to S5 together form valleys V separating the adjacent continuous compression regions CR. The weave pattern further comprises discontinuous compression regions dCR each of it being surrounded by recessed valleys V. Each discontinuous compression region dCR is formed by a number of MD-floats which are adjacent in cross-machine direction CD, which are off-set in machine direction MD and which overlap each other in machine direction MD. The number of MD-floats forming a discontinuous compression region dCR is less than the number of MD-floats which form a continuous compression region CR.

The continuous compression regions CR extends with its length at least over the length of the pattern repeat without being interrupted by a valley V. The continuous compression regions CR extend diagonally relative to the machine and cross-machine direction .

As shown in figure 3, the first MD-yarns 11 to 14 in the continuous compression region CR form a first group of first MD-floats Fl which all have a first float length of five (5) CD-yarns. Adjacently to the first group of first MD-floats Fl in the continuous compression region CR comprises a second group of second MD-floats F2, which is formed by the MD-yarns 7 to 10. All second MD-floats F2 have a second float length of seven (7) CD-yarns, which is more than the first float length. As can be seen the continuous compression region CR has at least one first group of MD-floats and at least one second group of MD-floats. The at least one first group is formed by a first number of first MD-floats Fl, which are adjacent in cross-machine direction CD. The first number is in the current case four (4) . The at least one second group of MD-floats F2 is formed by a second number of second MD-floats F2, which are adjacent in cross-machine direction CD. The second number is three (3) in the current case. The first and second groups are arranged consecutive. The average offset of the first MD- floats Fl in the first group is 1 (=[ 1 + 1 + 1 + 1 ] /4 ) and the average offset of the second MD-floats F2 in the second group is 3 (= [3+3+3J/3) . Therefore the average offset in the first group is less than the average offset in the second group.

In addition the first MD-floats Fl which form the first group have a first average float length, which is in the current case five CD-yarns, and the second MD-floats F2 which form the second group have a second average float length, which is in this case seven CD-yarns. As it is clearly visible, the individual length of the MD-floats forming the first group do not deviate from the first average float length and the individual length of the MD-floats forming the second group do not deviate from the second average float length. Further is can be seen that each of the MD-floats Fl, F2 have a center "X" of the float. If the centers "X" of first two adjacent MD-floats are connected by a straight line (e.g. the center of the second MD-float F2 formed by third MD-yarn 9 and the center "X" of the second MD-float F2 formed by third MD- yarn 10) a first center line (dotted line) is created, being at a first angle relative to the machine direction MD. If the centers "X" of second two adjacent MD-floats are connected by a straight line (e.g. the center of the second MD-float F2 formed by third MD-yarn 10 and the center "X" of the first MD- float Fl formed by first MD-yarn 11) a second center line (dotted line) is created, being at a second angle relative to the machine direction MD, which is different to the first angle .

By connecting all the center lines of the MD-floats forming the respective continuous compression region CR, a center connection line CCL is created which mainly runs angled relative to the machine and cross-machine direction. The center connection line CCL is non-straight and has at least two turning points. In addition the outer contour of the continuous compression regions is wavy.

Claims

OPAL 100 / OPAL 101

Claims

A papermakers fabric for a fibrous web forming and/or processing machine, the fabric comprises a first side and a second side opposing the first side, a machine direction and a cross-machine direction, a plurality of machine direction yarns interweaving with a plurality of cross-machine direction yarns to form a weave pattern on the first side, repeated in a pattern repeat, per pattern repeat each of the machine direction yarns forming several MD-floats on the first side which are consecutive in machine direction, each MD-float being formed by passing of a machine direction yarn on the first side over a plurality of adjacent cross-machine direction yarns, the weave pattern comprises a plurality of compression regions separated by valleys recessed relative to the compression regions, each of the compression regions being formed by a plurality of MD- floats adjacently arranged in cross-machine direction, the MD-floats forming a compression region at least partially overlap each other in machine direction, at least a majority of them being offset relative to each other in the machine direction, characterized in that at least one compression region has at least one first group of MD-floats and at least one second group of MD-floats, the at least one first group being formed by a first number of adjacent MD-floats and the at least one second group being formed by a second number of adjacent MD- floats, and the average offset of the MD-floats in the at least one first group is smaller than the average offset of the MD-floats in the at least one second group.

2. Papermakers fabric according to claim 1, characterized in that the second number being less than the first number.

3. Papermakers fabric according to claim 1 or 2, characterized in that all MD-floats which form a compression region are offset relative to each other in machine direction.

4. Papermakers fabric according to one of the preceding claims, characterized in that each compression region comprises at least one first and second group.

5. Papermakers fabric according to one of the preceding claims, characterized in that the first and second groups are arranged alternatingly .

6. Papermakers fabric according to one of the preceding claims, characterized in that the compression regions are adjacently arranged in machine direction and/or cross- machine direction.

7. Papermakers fabric according to one of the preceding claims, characterized in that each of the first groups is formed by at least four adjacent MD-floats, preferably at least six adjacent MD-floats.

8. Papermakers fabric according to one of the preceding claims, characterized in that each of the second groups is formed by maximum eight adjacent MD-floats, preferably by maximum six adjacent MD-floats.

9. Papermakers fabric according to one of the preceding claims, characterized in that the first groups are formed by first MD-floats and the second groups are formed by second MD-floats, wherein the first MD-floats have a first length and the second MD floats have a second length.

10. Papermakers fabric according to claim 9, characterized in that the first length is different to the second length.

11. Papermakers fabric according to claim 10, characterized in that the first length is bigger than the second length or that the first length is less than the second length.

12. Papermakers fabric according to one of the preceding claims, characterized in that the average offset of the MD-floats in the first group is between 0 and 2,5, preferably 0,5 and 2.

13. Papermakers fabric according to one of the preceding claims, characterized in that the average offset of the MD-floats in the second group is between 1,2 and 4.

14. Papermakers fabric according to one of the preceding claims, characterized in that the offset of the adjacent MD-floats in the first groups is such that the adjacent

MD-floats overlap each other in machine direction by at least half of their float length.

15. Papermakers fabric according to one of the preceding claims, characterized in that at least 50%, preferably at least 75%, of all adjacent MD-floats forming a compression region have an overlap of at least three consecutive cross-machine yarns.

16. Papermakers fabric according to one of the preceding claims, characterized in that the contact area formed by the first groups differs from the contact area formed by the second groups by maximum 20% in regard to the total contact area of the fabric on the first side.

17. Papermakers fabric according to one of the preceding claims, characterized in that the pattern repeat comprises at least one machine direction yarn forming a plurality of consecutive first MD-floats and at least another machine direction yarn forming a plurality of consecutive second MD-floats.

18. Papermakers fabric according to claim 17, characterized in that the pattern repeat comprises a plurality of first machine direction yarns, each of the first machine direction yarns forming a plurality of adjacent first MD- floats .

19. Papermakers fabric according to claim 17 or 18, characterized in that the pattern repeat comprises a plurality of second machine direction yarns, each of the second machine direction yarns forming a plurality of adjacent second MD-floats.

20. Papermakers fabric according to claim 17, 18 or 19, characterized in that the pattern repeat comprises a plurality of third machine direction yarns, each of the third machine direction yarns forming at least one first and at least one consecutive second MD-float.

21. Papermakers fabric according to one of the preceding claims, characterized in that consecutive MD-floats of each of the machine direction yarns are separated by a separation area, the separation area being formed by at least one of a knuckle and float of the machine direction yarn on the second side over at least one cross-machine direction yarn.

22. Papermakers fabric according to one of the preceding claims, characterized in that the pattern repeat comprises a plurality of separation areas, at least some of them being formed by one of i) a plain weave sequence of a machine direction yarn with at least three adjacent cross-machine direction yarns and ii) a float of a machine direction yarn on the second side over at least two adjacent cross-machine direction yarns and iii) a float of a machine direction yarn on the second side over one cross-machine direction yarns and iv) two consecutive floats of a machine direction yarn on the second side each over one cross-machine direction yarn, being separated from each other by a float of the machine direction yarn over maximum four adjacent cross-machine direction yarns on the first side.

23. Papermakers fabric according to one of the preceding claims 21 to 22, characterized in that the separation areas of all machine direction yarns together contribute to form the recessed valleys.

24. Papermakers fabric according to one of the preceding claims 21 to 23, characterized in that the separation areas of adjacent machine direction yarns either overlap each other in machine direction or are adjacent in machine direction.

25. Papermakers fabric according to one of the preceding claims, characterized in that the weave pattern comprises at least one continuous compression region and at least one discontinuous compression region.

26. Papermakers fabric according to claim 25, characterized in that each continuous compression region is formed by at least 10 adjacent MD-floats.

27. Papermakers fabric according to claim 25 or 26, characterized in that the at least one discontinuous compression region is formed by no more than six MD- floats, preferably no more than four MD-floats.

28. Papermakers fabric according to one of the preceding claims, characterized in that a center connection line connecting the centers of all adjacently arranged MD- floats mainly runs angled relative to the machine and cross-machine direction.

29. Papermakers fabric according to claim 28, characterized in that the center connection line mainly runs in the machine direction.

30. Papermakers fabric according to claim 28 or 29, characterized in that center connection line is non- straight, preferably has at least two turning points.

31. Papermakers fabric according to claim 28, 29 or 30, characterized in that the center connection lines of all continuous compression regions run in parallel relative to each other.

32. Papermakers fabric according to one of the preceding claims, characterized in that the outer contour of the continuous compression regions is wavy.

33. Papermakers fabric according to one of the preceding claims, characterized in that each of the MD-floats has a center of the float, wherein a first center line connecting the centers of first two adjacent MD-floats is angled to the machine direction at a first angle and a second center line connecting the centers of second two adjacent MD-floats is angled to the machine direction at a second angle different to the first angle.

34. Papermakers fabric according to one of the preceding claims, characterized in that the fabric is a single layer fabric.

35. Papermakers fabric according to one of the preceding claims, characterized in that the first side provides a paper contacting surface and the second side provides a machine contacting surface.

36. Papermakers fabric according to one of the preceding claims, characterized in that at least some, preferably all machine direction yarns forming the floats have a flattened cross section.

37. A papermakers fabric for a fibrous web forming and/or processing machine, the fabric comprises a first side and a second side opposing the first side, a machine direction and a cross-machine direction, a plurality of machine direction yarns interweaving with a plurality of cross-machine direction yarns to form a pattern repeat at the first side, per pattern repeat each of the machine direction yarns forming several MD-floats consecutive in machine direction and separated from each other by separation areas, each MD-float being formed by passing of a machine direction yarn on the first side over a plurality of adjacent cross-machine direction yarns, each separation area being formed by at least one of a knuckle and float of the machine direction yarn on the second side over at least one cross-machine direction yarn, characterized in that the pattern repeat comprises a plurality of first machine direction yarns and a plurality of second machine direction yarns, the first machine directions yarns forming first MD-floats separated by first separation areas, the second machine direction yarns forming second MD-floats separated by second separation areas, the first MD-floats have a first float length being longer in machine direction than the float length of the second MD-floats, the first separation areas being shorter in machine direction than the second separation areas.

38. Papermakers fabric according to claim 37, characterized in that per pattern repeat the first machine direction yarns form a plurality of groups of adjacently arranged first machine direction yarns.

39. Papermakers fabric according to claim 37 or 38, characterized in that per pattern repeat the second machine direction yarns form a plurality of groups of adjacently arranged second machine direction yarns.

40. Papermakers fabric according to claim 37, 38 or 39, characterized in that the first groups and the second groups are alternatingly arranged in machine direction and/or cross-machine direction.

41. Papermakers fabric according to one of the preceding claims 37 to 40, characterized in that adjacent first machine direction yarns in the first groups are offset relative to each other in machine direction and/or that adjacent second machine direction yarns in the second groups are offset relative to each other in machine direction .

42. Papermakers fabric according to one of the preceding claims 37 to 41, characterized in that at least some, preferably all of the separation areas being formed by a plain weave sequence of the machine direction yarn with at least three consecutive cross-machine direction yarns.

43. Papermakers fabric according to claim 42, characterized in that the first machine direction yarns form first separation areas, each of which being formed by a plain weave sequence with at least three consecutive cross machine direction yarns.

44. Papermakers fabric according to claim 42 or 43, characterized in that the second machine direction yarns form second separation areas, each of which being formed by a plain weave sequence with maximum 15 consecutive cross machine direction yarns.

45. A papermakers fabric for a fibrous web forming and/or processing machine, the fabric comprises a first side and a second side opposing the first side, a machine direction and a cross-machine direction, a plurality of machine direction yarns interweaving with a plurality of cross-machine direction yarns to form a pattern repeat at the first side, per pattern repeat each of the machine direction yarns forming several MD-floats consecutive in machine direction and separated from each other by separation areas, each MD-float being formed by passing of a machine direction yarn on the first side over a plurality of adjacent cross-machine direction yarns, each separation area being formed by at least one float of the machine direction yarn on the second side over at least one cross-machine direction yarn, characterized in that the pattern repeat comprises a plurality of third machine direction yarns each of which forming at least one first MD-float with a first float length and at least one consecutive second MD-float with a second float length, the first length being smaller than the second length, the first and second MD-floats being separated by a third separation area, being formed by one of a plain weave sequence of the third machine direction yarn with at least three consecutive cross-machine direction yarns and a float of the third machine direction yarn on the second side over one cross-machine direction yarn.

46. Papermakers fabric according to claim 45, characterized in that the pattern repeat comprises a plurality of first machine direction yarns, each of which forming a plurality of first MD-floats consecutive in machine direction .