阅读说明：本技术 干燥织物 (Drying fabric ) 是由 R·恩奎斯特 于 2020-09-28 设计创作，主要内容包括：本发明涉及一种干燥织物,其具有纵向、横向、第一表面和第二表面。干燥织物包括：纬纱,包括机器横向纱线；双经纱,包括第一经纱和第二经纱,第一经纱包括第一机器方向纱线,第二经纱包括第二机器方向纱线,第一经纱的纱线在第一表面侧上沿干燥织物的厚度方向布置在第二经纱的纱线上方,第一经纱包括主纱线,其断裂载荷在RH＝100％、T＝125℃和p＝2.3bar的条件下在15天内保持基本上稳定；以及位于第一端处的第一接缝形成配对部和位于第二端处的第二接缝形成配对部。第一经纱包括副纱线,使得第一经纱的至少每隔一根纱线是副纱线。副纱线的断裂载荷最初高于主纱线的断裂载荷,但是在RH＝100％、T＝125℃和p＝2.3bar的条件下副纱线的断裂载荷在15天内降低。(The present invention relates to a dryer fabric having a machine direction, a cross-machine direction, a first surface and a second surface. The dryer fabric comprises: weft yarns, including cross-machine direction yarns; a double warp yarn comprising a first machine direction yarn and a second warp yarn comprising a second machine direction yarn, the yarn of the first warp yarn being arranged over the yarn of the second warp yarn on the first surface side in the thickness direction of the drying fabric, the first warp yarn comprising a main yarn, the breaking load of which remains substantially stable for 15 days under conditions of RH-100%, T-125 ℃ and p-2.3 bar; and a first seam forming counterpart at the first end and a second seam forming counterpart at the second end. The first warp yarns include secondary yarns such that at least every other yarn of the first warp yarns is a secondary yarn. The breaking load of the secondary yarn was initially higher than that of the primary yarn, but the breaking load of the secondary yarn decreased within 15 days under conditions of RH 100%, T125 ℃ and p 2.3 bar.)

1. A dryer fabric (1) having a Machine Direction (MD), a cross-machine direction (CMD), a First Surface (FS) and a Second Surface (SS), said dryer fabric extending in the machine direction from a First End (FE) to a Second End (SE) and in the cross-machine direction from a first edge (7) to a second edge (8), said dryer fabric comprising:

-a weft yarn comprising cross-machine direction yarns (6),

-a twin warp yarn comprising a first machine direction yarn (5) and a second warp yarn comprising a second machine direction yarn (9), the yarns of the first warp yarn being arranged above the yarns of the second warp yarn in the thickness direction of the dryer fabric (1) on the First Surface (FS) side, the first warp yarn comprising a main yarn (51) whose breaking load remains substantially stable for 15 days under the conditions of RH 100%, T125 ℃ and p 2.3bar,

-a first seam forming counterpart (3) at the First End (FE) and a second seam forming counterpart (4) at the Second End (SE),

characterized in that the first warp yarn comprises secondary yarns (52) such that at least every second yarn of the first warp yarn is a secondary yarn (52), the breaking load of the secondary yarn (52) initially being higher than the breaking load of the primary yarn (51), but the breaking load of the secondary yarn (52) decreases within 15 days under conditions of RH-100%, T-125 ℃ and p-2.3 bar.

2. Dryer fabric according to claim 1, characterized in that the main yarn (51) comprises a polyphenylene sulfide (PPS) yarn.

3. Dryer fabric according to claim 1, characterized in that the main yarn (51) consists of polyphenylene sulfide (PPS) yarn.

4. Dryer fabric according to claim 1, characterized in that said main yarns (51) comprise: polyketone (PK) yarns, or yarns comprising Polyketone (PK).

5. Drying fabric according to claim 1, characterized in that the main yarns (51) consist of or comprise Polyketone (PK) yarns.

6. Dryer fabric according to any one of the preceding claims, characterized in that the secondary yarn (52) comprises a Polyester (PET) yarn.

7. Dryer fabric according to any one of the preceding claims 1 to 5, characterized in that the secondary yarn (52) consists of a Polyester (PET) yarn.

8. Dryer fabric according to any one of the preceding claims, characterized in that the first warp yarns comprise alternately primary (51) and secondary (52) yarns.

9. Dryer fabric according to any one of the preceding claims, characterized in that the first seam forming counterpart (3) and the second seam forming counterpart (4) comprise locking spirals comprising separate loops (31), the mutually engaging locking spirals and pins being able to form a seam.

10. Drying fabric according to claim 9, characterized in that the individual loops (31) of the locking spiral are arranged to join adjacent primary (51) and secondary (52) yarns, such that the primary yarn (51) is located on top of the secondary yarn (52) on the First Side (FS) of the drying fabric (1).

11. Dryer fabric according to claim 9 or 10, characterized in that the locking spiral is made of Polyetheretherketone (PEEK).

12. The dryer fabric of claim 7, wherein the Polyester (PET) yarn includes an anti-hydrolysis agent that is a carbodiimide compound, such as a cyclic carbodiimide compound, an aromatic polycarbodiimide, or a monomeric carbodiimide.

13. The dryer fabric of any one of the preceding claims, wherein the yarns of the first warp yarns and the yarns of the second warp yarns are monofilaments.

14. Drying fabric according to any of the preceding claims, wherein at the first edge (7) there is a first edge zone (FZ) and at the second edge (8) there is a second edge zone (SZ), the first warp yarns comprise secondary yarns (52), such that at least every other one of the first warp yarns in at least one edge zone (FZ, SZ) is a secondary yarn (52) and the remaining part of the machine direction yarns (5) of the first warp yarns is a secondary yarn (52).

Technical Field

The present invention relates to a dryer fabric (dryer fabric). The dryer fabric has a machine direction, a cross-machine direction, and first and second surfaces. When the dryer fabric is in use, the first surface is in contact with a web of material to be treated, such as a paper or pulp web. The second surface of the dryer fabric faces a machine component, such as a roll of a papermaking machine. The dryer fabric forms a continuous rotating loop (endless) during use. Dryer fabrics are used primarily in the dryer section of a paper or pulp making machine.

The dryer fabric extends in a machine direction from a first end to a second end and in a cross direction from a first edge to a second edge. The dryer fabric comprises: weft yarns (weft) comprising cross-machine direction yarns (yarns); a double warp (warp) and a first seam-forming counterpart (seam-forming counterpart) at a first end and a second seam-forming counterpart at a second end. The double warp yarns include a first warp yarn and a second warp yarn. The first warp yarns comprise first machine direction yarns and the second warp yarns comprise second machine direction yarns. The yarn of the first warp is arranged above the yarn of the second warp on the first surface side in the thickness direction of the drying fabric. The first warp yarn comprises a main yarn, the breaking load of which is substantially stable for 15 days under conditions of RH (Relative Humidity) 100%, T125 ℃ and p 2.3 bar.

Further, the dryer fabric includes a first seam forming counterpart at a first end and a second seam forming counterpart at a second end.

Background

Monofilaments (monofilents) which retain their breaking load substantially stable under hydrolytic conditions are generally very expensive. The monofilaments may be made of, for example, polyphenylene sulfide (polyphenylene sulfide). The raw materials impart excellent properties to the dryer fabric, but are costly. It is also substantially inelastic.

Disclosure of Invention

It is an object of the present invention to provide a dryer fabric which overcomes the above problems. The object of the present invention is achieved by a dryer fabric as in the examples herein. Preferred embodiments of the present invention are disclosed herein.

The advantage of the dryer fabric is that the excellent properties of the dryer fabric are mainly maintained, while the fabric is much cheaper. Another advantage is that the fabric has a greater elasticity, which enhances the performance of the drying fabric, for example, during web breaks or during high pressure washing.

The double warp yarns include a first warp yarn and a second warp yarn. The first warp yarns comprise first machine direction yarns and the second warp yarns comprise second machine direction yarns. The yarns of the first warp yarns are arranged above the yarns of the second warp yarns in the thickness direction of the dryer fabric on the first surface side. The first warp yarn may be directly over the second warp yarn, but alternatively the first warp yarn may be displaced in the cross direction of the fabric relative to the second warp yarn.

There is a first end region (region) at the first end of the dryer fabric and a second end region at the second end. To form the loops to the end of the fabric, the first machine direction yarn may be woven back into the end region. An end section of the second machine direction yarn may be removed such that a free space is formed where the yarn has been removed. The end segments of the first machine direction yarns may be looped back onto themselves and woven back into free space.

At the first edge of the dryer fabric there is a first edge zone (zone) extending in the machine direction and at the second edge there is a second edge zone extending in the machine direction. The edge zone has a width (certain width) in the cross-machine direction.

According to one alternative, the first machine direction yarns forming the first surface side of the fabric comprise primary yarns and secondary yarns. The primary and secondary yarns are preferably monofilaments. The breaking load of the main yarn was substantially stable within 15 days under conditions of RH 100%, T125 ℃ and p 2.3 bar. In this context, substantially stable means that the breaking load is reduced by at most five percent compared to the initial breaking load of the primary yarn. The breaking load of the secondary yarn was initially higher than that of the primary yarn, but the breaking load of the secondary yarn decreased within 15 days under conditions of RH 100%, T125 ℃ and p 2.3 bar. The breaking load of the secondary yarn is reduced by more than five percent compared to the initial breaking load of the secondary yarn.

The breaking load of the yarn was tested by using a speed of 100mm/min at T23 ℃ and RH 65%. The test was carried out after 24 hours of conditioning under the same conditions.

A suitable apparatus for simulating hydrolysis conditions is an autoclave (autoclave). The aging in the autoclave should be carried out in the same batch to obtain comparable results. The control sample should also be in the same batch as the sample to be tested. A suitable device for testing the breaking load is, for example, an Instron tensile strength tester (Instron tensile strength tester). The same definitions, test methods and conditions described above are also used in combination with other alternatives described herein.

The primary and secondary yarns are preferably flat monofilaments. In this context, flattened monofilaments refer to monofilaments having a width greater than their thickness, as well as monofilaments having substantially flat upper and lower surfaces.

When viewing the cross-section of the dryer fabric, the secondary yarns may have a lower profile on the first surface side in the thickness direction of the dryer fabric than the primary yarns. In other words, when the drying fabric is in use, the primary yarns are in direct contact with the web to be treated (such as a paper web or a pulp web), there being air gaps between the web and the secondary yarns. In this way, the less resistant secondary yarn is protected against e.g. heat and abrasion.

The primary yarn may be a polyphenylene sulfide (PPS) yarn, preferably a monofilament. PPS yarns have excellent heat and chemical resistance, high dimensional stability, low moisture absorption, and high hydrolysis resistance. The secondary yarn is preferably a monofilament, which may be a Polyester (PET) yarn. PET yarns have limited performance in many respects compared to PPS yarns, but they impart additional elasticity to the dryer fabric. The PET yarn comprises polyethylene terephthalate. The PET yarn preferably includes a chemical hydrolysis stabilizer to prevent degradation. The chemical hydrolysis stabilizer may be a carbodiimide compound, such as a cyclic carbodiimide compound, an aromatic polycarbodiimide, or a monomeric carbodiimide.

The cross-machine direction yarns may be made of the same material as the machine direction yarns.

According to another alternative, the main yarn may be a Polyketone (PK) yarn or a yarn comprising polyketone. They are preferably monofilaments. Yarns comprising polyketones may comprise another polymer as a blend (blend) or a core/sheath structure may be present. A polyketone sheath and a core of another polymer may be present. The secondary yarn may be a Polyester (PET) yarn, preferably a monofilament. PET yarns have limited performance in many respects compared to PK yarns, but they impart additional elasticity to the dryer fabric. The PET yarn comprises polyethylene terephthalate. The PET yarn preferably includes a chemical hydrolysis stabilizer to prevent degradation. The chemical hydrolysis stabilizer may be a carbodiimide compound, such as a cyclic carbodiimide compound, an aromatic polycarbodiimide, or a monomeric carbodiimide.

The first warp yarn comprising the first machine direction yarn, preferably a monofilament, may alternately comprise a primary yarn and a secondary yarn, but the primary yarn may also be, for example, every third (every fourth) yarn.

For example, first warp yarns comprising first machine direction yarns (preferably monofilaments) may alternately comprise polyphenylene sulfide yarns or polyketone yarns or yarns comprising polyketone, i.e. every other first machine direction yarn is a polyphenylene sulfide yarn or a polyketone yarn or a yarn comprising polyketone, and every other first machine direction yarn is a polyester yarn. However, other ratios of polyphenylene sulfide yarns or polyketone yarns or yarns comprising polyketone and polyester yarns are also possible. For example, the polyphenylene sulfide yarns or polyketone yarns or yarns comprising polyketone may be, for example, every third yarn.

The cross-machine direction yarns may be made of the same material as the machine direction yarns.

The dryer fabric should be a continuous loop when in use. To form the seam, the first and second ends of the dryer fabric may be attached to each other by loops that have been formed by looping back the first machine direction yarns, or the loops may be used to secure separate locking spirals in both ends of the fabric. In both cases, the seam-forming counterpart, i.e. the loop or the locking helix, is fastened to one another in the following manner: the individual loops of the first seam forming counterpart intermesh with the individual loops of the second seam forming counterpart.

If the seam is made of loops of machine direction yarns, a pin is inserted into the channel that has been formed by the intermeshed loops. If the seam is made of a locking spiral, the pin is inserted into the channel that has been formed by the intermeshing turns (turn) of the locking spiral. The locking helix may be made of Polyetheretherketone (PEEK). The form of the locking helix may be flat, i.e. the helix has a shorter dimension in the thickness direction of the dryer fabric and the upper and lower surfaces of the turns of the helix are substantially flat.

When the primary and secondary yarns alternate and the primary yarn is located on top of the secondary yarn on the first side of the dryer fabric, the turns of the locking spiral bind (bind) themselves to the loops of the dryer fabric in such a way that they bind to both the primary and secondary yarns. The uppermost yarn is highly resistant to hydrolysis, and the monofilament under the uppermost yarn supports the durability of the joint (joint) between the woven part (weave) and the locking helix.

When polyphenylene sulfide yarns or polyketone yarns or yarns comprising polyketone and polyester yarns alternate and PPS or PK yarns are on top of PET yarns on the first surface side of the dryer fabric, the loops of the locking spiral bind themselves to the loops of the dryer fabric in a manner that binds themselves to the PPS yarns or both the PK and PET yarns. The uppermost PPS or PK yarn is highly resistant to hydrolysis, and the PET yarn below the highly resistant yarn supports the durability of the joint between the braided part and the locking helix.

Another alternative to making the dryer fabric is to use two different high performance yarns, namely, in a manner that the primary yarn is different from the secondary yarn, such that the first primary yarn of the dryer fabric comprises a primary yarn whose breaking load and elongation at break are substantially stable over 15 days under conditions of RH 100%, T125 ℃ and p 2.3bar, and the first primary yarn of the dryer fabric comprises a secondary yarn whose breaking load and elongation at break are substantially stable over 15 days under conditions of RH 100%, T125 ℃ and p 2.3 bar. The above conditions may be arranged in an autoclave. After treatment in an autoclave, the monofilaments were tested.

The primary yarn may be, for example, polyphenylene sulfide (PPS) yarn, and the secondary yarn may be, for example, Polyketone (PK) yarn. The primary and secondary yarns are preferably monofilaments. The first warp yarns, including the first machine direction yarns, may alternately include PPS yarns and PK yarns, i.e., every other first machine direction yarn is a PPS yarn and every other first machine direction yarn is a PK yarn. However, other ratios of PPS and PK yarns are possible. For example, the PPS yarns may be, for example, every third yarn. The second warp yarns may comprise Polyester (PET) yarns. They preferably include chemical hydrolysis stabilizers to prevent degradation. The chemical hydrolysis stabilizer may be a carbodiimide compound, such as a cyclic carbodiimide compound, an aromatic polycarbodiimide, or a monomeric carbodiimide. One possible construction of the dryer fabric is described below.

The cross-machine direction yarns may be made of the same material as the machine direction yarns.

If the seam is made of loops of machine direction yarns, a pin is inserted into the channel that has been formed by the intermeshed loops. If the seam is made of a locking spiral, a pin is inserted into the channel that has been formed by the intermeshed turns of the locking spiral. The locking helix may be made of Polyetheretherketone (PEEK). The form of the locking helix may be flat, i.e. the helix has a shorter dimension in the thickness direction of the dryer fabric and the upper and lower surfaces of the turns of the helix are substantially flat.

A further alternative is to form the first warp yarns of the drying fabric from Polyketone (PK) yarns, i.e. yarns made of polyketone, the breaking load of which is substantially stable for 15 days at RH 100%, T125 ℃ and p 2.3 bar. The second warp yarns may comprise Polyester (PET) yarns. The yarns of the first and second warp yarns are preferably monofilaments. They preferably include chemical hydrolysis stabilizers to prevent degradation. The chemical hydrolysis stabilizer may be a carbodiimide compound, such as a cyclic carbodiimide compound, an aromatic polycarbodiimide, or a monomeric carbodiimide.

The cross-machine direction yarns may be made of the same material as the machine direction yarns.

If the seam is made of loops of machine direction yarns, a pin is inserted into the channel that has been formed by the intermeshed loops. If the seam is made of a locking spiral, a pin is inserted into the channel that has been formed by the intermeshed turns of the locking spiral. The locking helix may be made of Polyetheretherketone (PEEK). The form of the locking helix may be flat, i.e. the helix has a shorter dimension in the thickness direction of the dryer fabric and the upper and lower surfaces of the turns of the helix are substantially flat.

The above alternatives may be implemented only in either edge region and the remainder of the machine direction yarns of the first warp yarns may be secondary yarns. The above alternatives can also be implemented in both edge areas and the machine direction yarns between the edge areas can be secondary yarns. The width of the first edge zone and the width of the second edge zone may be at most 500mm, preferably at most 300mm, more preferably at most 150mm from the respective edge of the drying fabric. For example, every other machine direction yarn in one or more (two) edge regions may be a primary yarn and every other machine direction yarn may be a secondary yarn. The main yarn may be a polyphenylene sulfide (PPS) yarn or a Polyketone (PK) yarn. The secondary yarns may be Polyester (PET) yarns or Polyketone (PK) yarns. The machine direction yarns of the second warp yarns and the machine direction yarns of the first warp yarns outside of the one or more (two) edge regions may be Polyester (PET) yarns. The cross-machine direction yarns may be made of the same material as the machine direction yarns.

In various alternatives, all of the yarns or monofilaments described above may include additional components other than polymers, such as fillers and the like. The same applies to the locking helix.

Dryer fabrics may have many alternative configurations. For example, the dryer fabric may have the following structure. This structure can be applied to each of the alternatives described above.

The dryer fabric comprises double warp yarns, i.e. there are two warp yarns, one above the other. The first warp yarns comprise first machine direction yarns and the second warp yarns comprise second machine direction yarns. The yarns of the first warp yarn are arranged above the yarns of the second warp yarn. The first machine direction yarn of the first warp yarn and the second machine direction yarn of the second warp yarn may be flat yarns.

The yarns of the first warp yarns may be at least partially offset with respect to the yarns of the second warp yarns, which means that at least a portion of the yarns of the first warp yarns are laterally (laterally) displaced with respect to the yarns of the second warp yarns. However, all of the yarns of the first warp yarn may be offset relative to the yarns of the second warp yarn. The warp coverage of each warp is preferably 75% to 95%.

The dryer fabric includes weft yarns that include cross-machine direction yarns. The cross-machine direction yarns of the weft yarns may be round yarns, i.e. their cross-section is circular, or they may be oval yarns, i.e. their cross-section is oval. The cross-machine direction yarns are typically monofilaments.

The yarns of the first warp and the weft are coupled to each other according to a first predetermined pattern, and the yarns of the second warp and the weft are coupled to each other according to a second predetermined pattern.

The dryer fabric may have a granular texture (grain texture) on a first side of the dryer fabric. In other words, there are many points of contact on the first surface of the industrial textile, but the area of contact is small. The granular texture is obtained by means of short floats (floats). For example, the first predetermined pattern may be formed such that the yarns of the first warp and the weft are combined with each other such that the yarns of the first warp repeatedly pass over and under two of the weft. The yarns of the first warp yarns that are adjacent to each other are arranged such that when a simultaneously selected warp yarn is below a weft yarn, the warp yarn adjacent to the simultaneously selected warp yarn is above the weft yarn. This creates a grainy texture on the first surface, i.e. the surface of the textile appears to be covered by particles.

The second predetermined pattern may be formed such that the yarns of the second warp and the weft yarns are combined with each other such that the yarns of the second warp yarn repeatedly pass over one weft yarn and under three weft yarns. The yarns of the second warp yarns adjacent to each other are arranged such that when a simultaneously selected warp yarn is located above a weft yarn, the warp yarn adjacent to the simultaneously selected warp yarn is located above the second weft yarn as if starting from a weft yarn (above which the simultaneously selected warp yarn is located), i.e. the second weft yarn starting from the weft yarn above which the simultaneously selected warp yarn is located. The weft yarn over which the yarn of the second warp yarn passes is the second weft yarn over which the yarn of the first warp yarn passes.

The structure of the dryer fabric is not limited to the combination or cross-section of the yarns described above. The description of the structure is only one example of how to make the woven portion of the dryer fabric.

Drawings

In the following, the invention will be described in more detail by means of preferred embodiments with reference to the accompanying drawings, in which

Figures 1 to 4b show schematic views of a dryer fabric;

FIG. 5 shows a perspective view of a portion of a dryer fabric;

FIG. 6 illustrates another perspective view of a portion of a dryer fabric;

figure 7 shows a schematic representation of one possible arrangement of the first and second warp yarns of the drying fabric in cross section.

Detailed Description

Fig. 1 to 3 show a schematic view of a dryer fabric 1. The dryer fabric has a machine direction MD, a cross-machine direction CMD, a first surface FS and a second surface SS. The dryer fabric 1 comprises a woven portion 2 and seam forming counterparts 3, 4. The knitted part 2 comprises a first end FE, a second end SE, a first end region FR, a second end region SR, a first edge 7, a second edge 8, a first edge zone FZ and a second edge zone SZ.

In addition to the possible configurations shown in the other figures, one possible configuration is that every other machine direction yarn of the first warp yarns in the first edge zone FZ, or every other machine direction yarn of the first warp yarns in the second edge zone SZ may be a primary yarn, and every other machine direction yarn may be a secondary yarn. The two edge regions FZ, SZ may also have the above-described structure. The main yarn may be a polyphenylene sulfide (PPS) yarn or a Polyketone (PK) yarn. The secondary yarns may be Polyester (PET) yarns or Polyketone (PK) yarns. The machine direction yarns of the first warp yarns and the machine direction yarns of the second warp yarns outside the one or more (two) edge regions may be Polyester (PET) yarns. The cross-machine direction yarns may be made of the same material as the machine direction yarns.

In use, the dryer fabric 1 forms a continuous loop as shown in figure 3 and the seam forming counterparts 3, 4 are joined together by pins (not shown).

Fig. 4a and 4b are schematic views of a possible arrangement of the first and second warp yarns of the drying fabric 1 shown in cross-section. When the drying fabric is in use, the first surface FS is in contact with a web of material to be treated, such as a paper web or pulp web. The second surface SS of the dryer fabric faces a machine component, such as a roll of a papermaking machine.

The first warp yarn includes a primary yarn 51 and a secondary yarn 52. The second warp yarn comprises yarn 9. In fig. 4a, the first warp yarn comprises alternately a main yarn 51 and a secondary yarn 52. In fig. 4b, every third first machine direction yarn is a main yarn 51, and three sub-yarns 52 are present between two main yarns 51.

Fig. 4a and 4b show that the yarns 51, 52 of the first warp yarn are directly above the yarns 9 of the second warp yarn. However, the yarns 51, 52 of the first warp yarn may be at least partially offset with respect to the yarns of the second warp yarn, which means that at least a portion of the yarns 51, 52 of the first warp yarn are laterally displaced with respect to the yarns 9 of the second warp yarn. All yarns 51, 52 of the first warp yarn may be offset with respect to yarn 9 of the second warp yarn.

Fig. 5 shows a perspective view of a part of the drying fabric 1. The dryer fabric 1 comprises a woven portion 2 and seam forming counterparts 3, 4 (only counterpart 3 is shown). The knitting portion 2 includes: first warp yarns comprising first machine direction yarns 5; a second warp yarn comprising a second machine direction yarn positioned below the first warp yarn; and the weft yarns, including cross-machine direction yarns 6.

The seam forming counterpart 3, 4 is a locking helix. As shown in fig. 5, the locking helix is flat, i.e. the helix has the shortest dimension in the thickness direction of the dryer fabric, and the upper and lower surfaces of the turns of the helix are substantially flat.

The first warp of the knitted part 2 comprises alternating main monofilaments 51 and secondary monofilaments 52. The primary monofilament 51 is located on top of the secondary monofilament 52 on the first surface side of the drying fabric 1. The single turn 31 of the locking helix binds itself to the loops of the drying fabric in such a way as to bind itself to both the primary monofilament 51 and the secondary monofilament 52.

The above-described dry fabric 1 was tested for hydrolysis resistance when the primary monofilament was a polyphenylene sulfide monofilament and the secondary monofilament was a polyester monofilament. Two comparative dryer fabrics were also tested. The first contrast fabric is a fabric composed of PPS yarns. The second comparative fabric was a fabric composed of PET yarns. The breaking load of the tested fabric at the beginning of the test was over 90N. After 15 days under hydrolysis conditions, the breaking load of the second comparative fabric fell to 10N, while the breaking load of the drying fabric 1 of the invention was at the same 90N level as that of the comparative fabric consisting of PPS yarns.

Alternatively, the first warp yarn of the knitted portion 2 comprises alternating PK yarns 51 and PET yarns 52. The PK yarns 51 are located on top of the PET yarns 52 on the first surface side of the drying fabric 1. The single turn 31 of the locking spiral binds itself to the loops of the dryer fabric in a manner that binds itself to both PK yarn 51 and PET yarn 52.

Fig. 6 shows a perspective view of a part of the drying fabric 1. The dryer fabric 1 comprises a woven portion 2 and seam forming counterparts 3, 4 (only counterpart 3 is shown). The knitting portion 2 includes: first warp yarns comprising first machine direction yarns 5; a second warp yarn comprising a second machine direction yarn positioned below the first warp yarn; and the weft yarns, including cross-machine direction yarns 6.

The seam forming counterparts 3, 4 are loops of the first machine direction yarns. The first warp yarn of the knitted part 2 comprises alternating PPS yarns 51 and PET yarns 52. PPS yarns 51 are on top of PET yarns 52 on the first surface side of the dryer fabric.

Alternatively, the first warp yarn of the knitted portion 2 comprises alternating PK yarns 51 and PET yarns 52. PK yarns 51 are on top of PET yarns 52 on the first surface side of the dryer fabric.

Fig. 7 shows a schematic representation of one possible arrangement of the first and second warp yarns of the drying fabric 1 in cross section. The first warp yarn includes a primary yarn 51 and a secondary yarn 52. The second warp yarn comprises yarn 9. The secondary yarns 52 may have a lower height in the thickness direction of the dryer fabric than the primary yarns 51. The secondary yarns 52 are at the same level on the second surface SS of the dryer fabric 1 as the primary yarns 51. In other words, when the drying fabric is in use, the primary yarns 51 are in direct contact with the web to be treated (such as a paper web or a pulp web), and on the side of the first surface FS, there is an air gap 10 between the web and the secondary yarns 52. Thus, the secondary yarns 52 are protected from, for example, heat and abrasion.

It is obvious to a person skilled in the art that as technology advances, the inventive concept can be implemented in different ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.