Press felt

Abstract

To provide an improved press felt having a marking effect and capable of better evaporation of moisture from pulp.SOLUTION: According to an example aspect of the present invention, there is provided a press felt (100) having a seam and a web-side and a machine-side. The press felt (100) comprises: a first fiber layer (131) on the web-side; a second fiber layer (132) on the machine-side; and at least one woven base fabric (110) and at least one spiral fabric (120) between the first fiber layer and the second fiber layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to press felts used in fibre web machines.

Background Art

[0002] Press felts play an important role in removing water from the fibre web in the press section of fibre web machines. The press felt transports the web across the press section and receives the water removed from the web during the pressing process. At the same time, the press felt gives smoothness to the web and transports it to the dryer section. Modern press felts include at least one base fabric and a fibre layer provided on at least one side of the base fabric. The base fabric can be a woven or non-woven fabric consisting of 1 to 4 layers.

[0003] Conventionally used press felts have a small surface area, which enables the production of webs with a smooth surface. That is, conventionally used press felts do not have a marking effect. The marking effect means that the press felt creates a concave-convex structured surface on the web. Therefore, there is a need for a new press felt having a marking effect. Also, conventionally used press felts may have insufficient water removal characteristics due to their small surface area. Therefore, there is also a need for a new press felt with a larger surface area so that moisture evaporates better from the pulp.

Summary of the Invention

[0004] At least some of the objectives of the present embodiment are to provide a press felt with an increased surface area for a marking effect and better evaporation of moisture from the pulp.

[0005] According to a first aspect of the present invention, there is provided a press felt having a seam, a web side, and a machine side, the press felt comprising: - a first fibre layer on the web side; - a second fibre layer on the machine side; - at least one woven base fabric and at least one spiral fabric between the first fiber layer and the second fiber layer; comprising.

[0006] According to a second aspect of the present invention, there is provided the use of the press felt of the present invention in a fiber web machine such as a paper making machine, a cardboard manufacturing machine, a tissue manufacturing machine or a pulp machine.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0008] In this context, the term "spiral fabric" means a fabric comprising a plurality of spiral loop yarns and a plurality of pintle wires connecting the spiral yarns to each other. The spiral loop yarns are woven together with adjacent spiral loop yarns like a zipper. Adjacent spiral loop yarns form channels between adjacent spiral loop yarns. Adjacent spiral loop yarns are connected to pintle wires extending through the channels. There is free space within the loops of the spiral loop yarns, and the free space can be filled with filler yarns.

[0009] In this context, the term "loop size" means the length (L) of the loop of the spiral loop yarn. The length is substantially perpendicular or inclined to the length direction of the pintle wire in the plane of the spiral fabric.

[0010] In this context, the term "web side" means the side of the press felt facing the fibrous web such as paper, cardboard, pulp or tissue produced when the press felt is used in a fibrous web machine, for example, a paper machine, a cardboard manufacturing machine or a tissue manufacturing machine.

[0011] In this context, the term "machine side" means the side of the press felt that contacts the equipment of the fibrous web machine when the press felt is used in the fibrous web machine.

[0012] In this context, the term "machine direction" means the direction parallel to the direction in which the press felt moves in the fibrous web machine when the press felt is used in the fibrous web machine.

[0013] In this context, the term "cross machine direction" means the direction perpendicular to the direction in which the press felt moves in the fibrous web machine when the press felt is used in the fibrous web machine.

[0014] The press felt plays an important role in removing water from the fibrous web in the press section of a fibrous web machine such as a paper machine, a cardboard manufacturing machine or especially a pulp machine and forming the surface. At least a part of the present embodiment provides a press felt having a marking effect that can impart a large surface area to the fibrous web in order to more favorably evaporate the moisture from the fibrous web in the drying section.

[0015] According to one embodiment, a press felt 100 having a joint, a web side and a machine side includes: - a first fiber layer 131 on the web side; - a second fiber layer 132 on the machine side; - at least one fabric base fabric 110 and at least one spiral fabric 120 between the fiber layers 131, 132; and.

[0016] Since the spiral fabric has a stronger and coarser structure, the spiral fabric provides a better mechanical marking effect compared to the fabric base. This marking effect increases the surface area of the fiber web, so that later, the drying of the fiber web becomes more energy-efficient.

[0017] The press felt 100 may include 1 to 4, preferably 1 to 2 fabric bases 110. With two or more fabric bases, a higher void volume, stability and strength can be obtained. The fabric base may have at least one yarn layer, preferably 1 to 4 yarn layers.

[0018] The press felt 100 may include 1 to 2, preferably 1 spiral fabric 120. With two or more spiral fabrics, a higher void volume can be obtained.

[0019] According to one embodiment, at least one spiral fabric 120 is on the web side or the machine side of at least one fabric base 110. When at least one spiral fabric is on the web side, since the surface structure of the spiral fabric affects through the fiber layer, the surface on the web side of the press felt becomes rough and granular. Therefore, the marking effect of at least one spiral fabric on the web is stronger. Alternatively, when at least one spiral fabric is on the machine side, the surface on the web side of the press felt is at least relatively smooth and uniform because the surface structure of the spiral fabric does not affect or does not significantly affect across the fiber layer. Or it does not significantly affect through the fiber layer. Therefore, at least one spiral fabric has no marking effect or a weak marking effect on the fiber web.

[0020] When the press felt 100 includes two or more fabric base cloths 110, the fabric base cloths 110 can be overlapped with each other to form a laminate of the fabric base cloths. When the press felt 100 includes two or more spiral fabrics 120, the spiral fabrics can be overlapped with each other to form a laminate of the spiral fabrics. The laminate of the spiral fabrics or preferably one spiral fabric 120 can be disposed on the machine side or the web side of the laminate of the fabric base cloths 110. Alternatively, the fabric base cloth 110 can alternate with the spiral fabric 120.

[0021] The fiber layers 131, 132 can include individual fibers that are needled to at least one fabric base cloth 110 and at least one spiral fabric 120 to form the fiber layers 131, 132 on the web side and the machine side of the press felt 100.

[0022] According to one embodiment, the first fiber layer 131 and the second fiber layer 132 are configured to penetrate through at least one fabric base cloth 110 and at least one spiral fabric 120 and attach the at least one fabric base cloth 110 and the at least one spiral fabric 120 to each other. Thus, no additional step for attaching the fabrics to each other is required, but the fibers of the fiber layers can be needled to the fabrics. In fact, the fiber layers penetrating through the base cloth and the spiral fabric can be obtained by passing the fibers of either the first fiber layer, the second fiber layer, or both through the fabric base cloth and the spiral fabric disposed between the fiber layers such that the fibers of at least one of the fiber layers extend to the other fiber layer, thereby attaching all the layers and fabrics of the press felt together.

[0023] According to one embodiment, at least one fabric base 110 includes machine direction (MD) yarns 111 and cross machine direction (CMD) yarns 112, and at least one spiral fabric 120 includes spiral loop yarns 121 and pintle wires 122. The machine direction yarns 111 and the cross machine direction yarns 112 intersect with each other and thereby engage with each other. When the spiral loop yarns are arranged adjacent to each other, i.e., a channel is formed in a first direction between adjacent spiral loop yarns. The adjacent spiral loop yarns are connected to a pintle wire extending through the channel. Usually, in a second direction perpendicular to the first direction in the plane of the spiral fabric, two loops overlap so that the pintle wire extends to adjacent channels as shown in FIG. 1.

[0024] According to one embodiment, the pintle wire 122 is arranged in the cross machine direction (CMD) as shown in FIG. 1 or is inclined with respect to the cross machine direction in the plane of the spiral fabric 120. The pintle wire 122 is slightly inclined (e.g., 0.1 to 10°) with respect to the cross machine direction in the plane of the spiral fabric 120. That is, the direction of the pintle wire 122 can be at least substantially the same as the direction of the cross machine direction yarns 112 of at least one fabric base 110. Therefore, the channels between adjacent spiral loop yarns are formed at least substantially in the cross machine direction of the press felt. Thereby, seams can be formed in the cross machine direction for all the base fabrics, i.e., the base fabric and the spiral fabric, facilitating the sewing of the press felt. In addition, since the seam of the spiral fabric is the same as the spiral fabric body, it cannot be distinguished from the body.

[0025] According to this embodiment, the seam includes a first seam 141 in at least one fabric base cloth 110 and a second seam 142 in at least one spiral fabric 120, and is a double-seam structure. The at least one fabric base cloth 110 and the at least one spiral fabric 120 may have a cross-machine direction (CMD) width and a machine direction (MD) length with both ends in the machine direction (MD) where they are joined together to form a continuous press felt, i.e., a first end and a second end. Therefore, when the press felt is used in a fiber web machine, the press felt forms a loop. The double seam provides for safe and easy attachment of the press felt.

[0026] According to one embodiment, the first seam is formed of a fabric loop and the second seam is formed of a spiral loop. The fabric loop can be formed at the end of the fabric base cloth 110 to be joined. The fabric loop can be formed of the machine direction yarns 111 of the fabric base cloth 110. The spiral loop can be formed at the end of the spiral fabric 120 to be joined. The spiral loop can be formed of loops of the spiral loop yarns 121 of the spiral fabric 120.

[0027] The fabric loops at the first end of the fabric base cloth 110 can interlock with the fabric loops at the second end of the fabric base cloth 110 when the ends are aligned with each other to form an endless press felt. The spiral loops at the first end of the spiral fabric 120 can interlock with the spiral loops at the second end of the spiral fabric 120 when the ends are aligned with each other to form an endless press felt. This interlocking arrangement of the loops forms a substantially tubular passage into which a pintle can be inserted. When the pintle is inserted into the passage, it attaches the ends to each other and provides an endless press felt.

[0028] When the press felt 100 includes two or more fabric base cloths 110 and / or spiral fabrics 120, both ends in the machine direction of all the individual fabric base cloths 110 and spiral fabrics 120 that together form the press felt can be joined separately or simultaneously.

[0029] Both ends in the machine direction can be joined together when the press felt is installed in the press section of the fiber web machine. Joining the seam loop with a pintle can start from the end of the fabric. The seam process continues until the pintle passes through all the loops and spiral loops of the fabric.

[0030] According to one embodiment, the spiral yarn 121 comprises a polymer, preferably a polyamide (PA). A press felt made of polyamide yarn has excellent strength and wear resistance.

[0031] According to one embodiment, the polyamide is selected from polyamide 4.6, polyamide 4.10, polyamide 5.6, polyamide 5.10, polyamide 6, polyamide 6.6, polyamide 6.10, polyamide 6.12, polyamide 10, polyamide 11 and polyamide 12 or mixtures thereof. By mixture (and for other examples below), it means that the product can contain two or more types of polyamides in the same yarn or fiber or that the product can contain different types of polyamides in different yarns or fibers. The above polyamides are excellent choices when mechanical strength and wear resistance are required. Polyamide 6 fibers are tough and have high tensile strength and elasticity. They have high resistance to wear and chemical substances such as acids and alkalis. Polyamide 6 has high water absorbency. Polyamide 6.6 has high mechanical strength, rigidity and good thermal and chemical stability. Polyamide 6.10 has high impact resistance, chemical resistance and dimensional stability. The values of the density, flexural modulus and Young's modulus, water absorbency, and melting and glass transition temperatures of polyamide 11 are lower than those of polyamide 6. However, polyamide 11 has higher dimensional stability in the presence of moisture than polyamide 6.

[0032] According to one embodiment, the cross-section of the spiral loop yarn 121 is circular, elliptical, rhombic, square, or square with rounded edges. These cross-sections provide a rough and granular surface and a high surface area for the spiral fabric. Therefore, the press felt has a marking effect when at least one spiral fabric is on the web side. In addition, the water removal property of the press felt is improved.

[0033] According to one embodiment, the diameter of the spiral loop yarn 121 is 0.1 to 3 mm, preferably 0.1 to 0.6 mm. Spiral loop yarns with a small diameter, such as about 0.1 to 1 mm, provide a smaller surface area and thus a smoother surface for the press felt. On the other hand, spiral loop yarns with a large diameter, such as about 2 to 3 mm, provide a higher surface area and thus a rougher and more granular surface for the press felt. In addition, a larger diameter provides good tensile strength and air permeability.

[0034] According to one embodiment, the loop size L of the spiral loop yarn 121 is 0.2 to 15 mm, preferably 0.2 to 10, more preferably 2 to 6 mm. When the loop size is larger, a pintle wire with a larger diameter can be used, which affects the marking effect. When the loop size is smaller, a pintle wire with a smaller diameter can be used. This allows for a more flexible selection of yarn and loop size according to the working conditions. A large loop size, such as about 10 to 15 mm, provides a smaller surface area for the press felt than a small loop size, such as about 0.2 to 1 mm. On the other hand, a small loop size results in a rougher and more granular surface than a large loop size because the distance between the pintle wires 122 is shorter.

[0035] The spiral fabric 120 may be a wind fabric. In a wind fabric, the filaments of the spiral loop yarn 121 are wound into spiral loops, and the spiral loops are connected to each other by pintle wires 122.

[0036] The pintle wire 122 may contain a polymer, preferably a polyamide (PA). The polyamide can be selected from polyamide 4.6, polyamide 4.10, polyamide 5.6, polyamide 5.10, polyamide 6, polyamide 6.6, polyamide 6.10, polyamide 6.12, polyamide 10, polyamide 11, and polyamide 12, and mixtures thereof. The pintle wire made of polyamide has excellent strength and wear resistance.

[0037] The diameter of the pintle wire 122 can be 0.1 to 14 mm, preferably 0.3 to 0.9 mm. Preferably, all of the pintle wires have essentially the same diameter.

[0038] According to one embodiment, the spiral fabric 120 further includes a filler yarn 123 within the loops of the spiral loop yarn 121. The filler yarn can be used to reduce breathability if necessary and to enhance the entanglement of the fibers of the fiber layers 131, 132.

[0039] According to one embodiment, the filler yarn 123 is a monofilament, multifilament, or twisted yarn. The filler yarn is preferably a twisted yarn, in which case the entanglement with the fibers of the fiber layers 131, 132 is enhanced. Therefore, it becomes easier to attach the fibers of the fiber layers 131, 132 to the spiral fabric 120. In addition, this strengthens the attachment of the fiber layers to each other.

[0040] The fibers of the fiber layers 131, 132 can be attached to at least one fabric base 110 and at least one spiral fabric 120 by needles.

[0041] The amount of the fibers of the fiber layers 131, 132 can be, for example, 50 to 2000 g / m 2 and can be.

[0042] The diameters of the machine direction yarn 111 and the cross-machine direction yarn 112 of at least one fabric base 110 can be 150 to 500 μm. Preferably, all of the yarns of the base fabric preferably have essentially the same diameter.

[0043] The machine direction yarns 111 and cross-machine direction yarns 112 of at least one fabric base cloth 110 may include polyamide (PA). The polyamide can be selected from polyamide 4.6, polyamide 4.10, polyamide 5.6, polyamide 5.10, polyamide 6, polyamide 6.6, polyamide 6.10, polyamide 6.12, polyamide 10, polyamide 11, and polyamide 12 and mixtures thereof. Alternatively, the polyamide fibers may include copolyamides obtained from two or more of the above polyamides or the polyamide fibers may be bicomponent fibers containing two of the above polyamides. The polyamide fibers preferably contain polyamide 11. Polyamide 11 has good dimensional stability in the presence of moisture.

[0044] The above-described press felt 100 can be used in a paper machine, a cardboard machine, a tissue machine, or a pulp machine.

[0045] FIG. 1 shows a press felt 100 according to at least some embodiments of the present invention. The press felt 100 includes a first fiber layer 131 on the web side and a second fiber layer 132 on the machine side. Further, the press felt 100 includes a fabric base cloth 110 and a spiral fabric 120 between the fiber layers 131, 132. The fabric base cloth 110 includes three layers. The spiral fabric 120 is on the web side of the fabric base cloth 110. The fabric base cloth 110 includes machine direction (MD) yarns 111 and cross-machine direction (CMD) yarns 112, and the spiral fabric 120 includes spiral loop yarns 121 and pintle wires 122. The pintle wires 122 are arranged in the cross-machine direction in the plane of the spiral fabric 120. The seam of the press felt is a double seam structure including a first seam 141 in the fabric base cloth 110 and a second seam 142 in the spiral fabric 120. The first seam 141 is formed of fabric loops. The second seam 142 is formed from spiral loops. Therefore, the second seam 142 is the same as the spiral fabric body itself and is thus invisible.

[0046] Figure 2 shows a spiral fabric 120 according to at least some embodiments of the present invention. The spiral fabric 120 includes spiral loop yarns 121 and pintle wires 122. The spiral fabric 120 further includes filler yarns 123 within the loops of the spiral loop yarns 121. The spiral loop yarns 121 have a loop size L which is the length of the loops of the spiral loop yarns in the machine direction (MD) of the press felt.

[0047] It should be understood that the disclosed embodiments of the present invention are not limited to the specific structures, processes or materials disclosed herein, but extend to their equivalents as would be recognized by those skilled in the art. It should be understood that the terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting.

[0048] Furthermore, the described features, structures or characteristics may be combined in any suitable manner in one or more embodiments. In this specification, numerous specific details such as examples of length, width, shape, etc. are provided to provide a complete understanding of the embodiments of the present invention.

[0049] The verb "comprising" is used herein as an open limitation that does not exclude or require the presence of features not recited. The features recited in the dependent claims may be freely combined with each other unless otherwise specified. Furthermore, it should be understood that the use of "a" or "an", i.e., the singular form, throughout this application does not exclude a plurality.

Explanation of Reference Numerals

[0050] 100 Press felt 110 Base fabric 111 Machine direction yarn 112 Cross machine direction yarn 120 Spiral fabric 121 Spiral loop yarn 122 Pintle wire 123 Filler yarn 131 First fiber layer 132 Second fiber layer 141 First seam 142 Second seam

Claims

1. A press felt having a seam, a web side, and a machine side, wherein the press felt comprises: a first fiber layer on the web side; a second fiber layer on the machine side; at least one fabric base fabric and at least one spiral fabric between the first fiber layer and the second fiber layer; and the at least one spiral fabric is on the web side of the at least one fabric base fabric, and the first fiber layer is directly attached to the at least one spiral fabric; the seam is a double seam structure including a first seam in the at least one fabric base fabric and a second seam in the at least one spiral fabric.

2. The press felt according to claim 1, wherein the first fiber layer and the second fiber layer penetrate through the at least one fabric base fabric and the at least one spiral fabric and are configured to attach the at least one fabric base fabric and the at least one spiral fabric to each other.

3. The at least one fabric base fabric includes machine direction yarns and cross-machine direction yarns, and the at least one spiral fabric includes spiral loop yarns and pintle wires.

4. The press felt according to claim 3, wherein the pintle wires are arranged in the cross-machine direction within the plane of the spiral fabric or are inclined with respect to the cross-machine direction.

5. The press felt according to claim 1, wherein the first seam is formed by fabric loops and the second seam is formed by spiral loops.

6. The press felt according to claim 3, wherein the spiral loop yarns contain a polymer, and the polymer contains a polyamide.

7. The polyamide according to claim 6 is selected from polyamide 4.6, polyamide 4.10, polyamide 5.6, polyamide 5.10, polyamide 6, polyamide 6.6, polyamide 6.10, polyamide 6.12, polyamide 10, polyamide 11, and polyamide 12, or a mixture thereof.

8. The cross-section of the spiral loop yarns is circular, elliptical, rhomboidal, square, or square with rounded edges. The press felt according to claim 3.

9. The press felt according to claim 3, wherein the diameter of the spiral loop yarns is 0.1 to 3 mm.

10. The loop size of the spiral loop yarn is 0.2 to 15 mm, the press felt according to claim 3.

11. The spiral fabric further includes a filler yarn in the loop of the spiral loop yarn, the press felt according to claim 3.

12. The filler yarn is a monofilament, multifilament or twisted yarn, the press felt according to claim 11.

13. Use of the press felt according to any one of claims 1 to 12 in a paper making machine, cardboard manufacturing machine, tissue manufacturing machine or pulp machine.

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