BASE FABRIC FOR SEAMED FELT, PAPERMAKING FELT, AND METHOD FOR PRODUCING PAPERMAKING FELT

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2024-211813 filed on Dec. 4, 2024, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a base fabric for seamed felt, a papermaking felt, and a method for producing a papermaking felt.

BACKGROUND ART

A papermaking machine for compressing water from a wet paper web generally includes a wire part, a press part, and a dryer part. The wire part, the press part, and the dryer part are disposed in this order along a transfer direction of wet paper web. The wet paper web has a certain width in a felt cross direction, which is a cross machine direction (CD direction) in the papermaking machine. The wet paper web in a strip shape moves in a felt running direction, which is a machine direction (MD direction) perpendicular to the CD direction within the papermaking machine. The wet paper web is compressed while being transferred by passing from one papermaking equipment to the next provided in the wire part, the press part, and the dryer part, and is finally dried in the dryer part.

The press part is equipped with a plurality of press devices arranged in series along the transfer direction of the wet paper web. Each press device includes a papermaking felt (hereinafter, may be simply referred to as a “felt”), and either a pair of rolls (that is, roll presses) disposed vertically facing each other to sandwich a part of the felt therebetween, or a cylindrical belt (that is, a shoe press) including a roll and a shoe. Then, the wet paper web transferred by the felt running in the same direction at substantially the same speed is pressed under pressure by the rolls or the cylindrical belt including a roll and a shoe, together with the felt, thereby continuously compressing water from the wet paper web.

When a large amount of water is removed from the wet paper web such as paperboard or pulp paper, a felt having a large void volume is required. Specifically, to increase the void volume of the felt, a laminate structure in which a plurality of base fabrics are laminated is used.

Such a papermaking felt can be obtained by using an endless felt directly or joining open-ended base fabrics for a felt. Since the endless felt does not have a joint, the endless felt is excellent in smoothness when being used as the papermaking felt, but the endless felt needs to be custom-made to fit dimensions of the papermaking machine, which reduces productivity.

In view of such circumstances, in recent years, open-ended base fabrics for a felt are joined to form an endless configuration. For example, Patent Literature 1 discloses a papermaking felt in which open-ended base fabrics for a felt are joined by welding or the like to form an endless configuration, and the obtained endless felts are laminated in plurality.

In recent years, there has been a demand for a seamed felt that ensures easy threading and high safety, and that can be made endless by connecting seam loop portions on a papermaking machine. Some seamed felts are woven on a loom while forming seam loops, but as described above, such seamed felts are inferior in productivity. Therefore, a seamed felt is becoming mainstream, in which open-ended plain-woven base fabrics are joined by welding or the like to form an endless configuration, seam loops are formed at a folded portion, and the seam loop portions are then connected on a papermaking machine to achieve endless configuration. The joining of the base fabrics is mainly performed by welding from a standpoint of simplicity of operation and the like. Patent Literature 2 discloses an endless papermaking felt via a seam portion provided in an open-ended felt.

CITATION LIST

Patent Literature

• Patent Literature 1: JP2022-38303A
• Patent Literature 2: JP2022-134415A

SUMMARY OF INVENTION

However, when producing a papermaking felt by using an open-ended felt base fabric, wrinkles may be generated in a welded portion due to heat setting of the base fabric. When producing paper, vibration occurs when the welded portion of the base fabric passes over the rolls of the papermaking machine, and wrinkles on the welded portion of the base fabric reduce the smoothness of the felt, causing marks to appear on the paper passing through the papermaking machine.

The welded portion may be opened when producing or using the papermaking felt, and particularly, when using the papermaking felt, the felt may be broken starting from an opened welded portion. The term “opened” as used herein means a state in which a force is applied when producing the papermaking felt or when using the papermaking felt, a part of the welded portion is cut, and the base fabric is not connected in the MD direction. The term “broken” means that the papermaking felt is torn over the entire width in the CD direction.

Aspect of non-limiting embodiments of the present disclosure relates to providing a base fabric for the seamed felt that enables various laminate structures, and that can produce a papermaking felt with high productivity, improved smoothness, and no risk of opening.

Aspects of certain non-limiting embodiments of the present disclosure address the features discussed above and/or other features not described above. However, aspects of the non-limiting embodiments are not required to address the above features, and aspects of the non-limiting embodiments of the present disclosure may not address features described above.

As a result of intensive studies, the present inventors have found that the above object can be achieved by specifying a structure of the base fabric for the seamed felt, and have completed the present invention.

According to an aspect of the present disclosure, the followings are provided.

<1> A base fabric for a seamed felt, comprising:

• • a single open-ended base fabric wound and laminated in a single direction by being wound around two winding portions,
  • wherein the single open-ended base fabric has a first end portion and a second end portion in the single direction, and
  • when the single open-ended base fabric is divided into a first laminated portion and a second laminated portion by a plane passing through top portions of the two winding portions, two or more layers of the single open-ended base fabric are present in at least one of the first laminated portion and the second laminated portion.
    <2> The base fabric for a seamed felt according to <1>, wherein
  • both the first end portion and the second end portion are located in either the first laminated portion or the second laminated portion.
    <3> The base fabric for a seamed felt according to <1>, wherein
  • the first end portion is located in either the first laminated portion or the second laminated portion, and the second end portion is located in the other of the first laminated portion or the second laminated portion.
    <4> The base fabric for a seamed felt according to any one of <1> to <3>, wherein
  • the first end portion and the second end portion are present on a vertical line perpendicular to the plane passing through the top portions of the two winding portions.
    <5> The base fabric for a seamed felt according to any one of <1> to <4>, wherein
  • two or more layers of the single open-ended base fabric are present at the respective top portions of the two winding portions.
    <6> The base fabric for a seamed felt according to any one of <1> to <5>, wherein
  • a distance between at least one selected from the first end portion and the second end portion and at least one of the top portions of the two winding portions is less than 5 cm.
    <7> The base fabric for a seamed felt according to any one of <1> to <6>, wherein
  • the first end portion and the second end portion are joined to the single open-ended base fabric.
    <8> The base fabric for a seamed felt according to <7>, wherein
  • the first end portion and the second end portion are joined to the single open-ended base fabric by at least one selected from linear sewing and zigzag sewing.
    <9> The base fabric for a seamed felt according to any one of <1> to <8>, further comprising:
  • a base fabric in an outermost layer.
    <10> A papermaking felt, which is formed by connecting the base fabrics for a seamed felt according to any one of <1> to <9> via seam portions formed in the two winding portions.
    <11> A method for producing a papermaking felt, the method comprising in the following order:
  • winding the base fabric for a seamed felt according to any one of <1> to <9> around the two winding portions; and
  • removing CD yarns of outermost layers at the two winding portions to form a seam loop.

According to the present invention, it is possible to provide a base fabric for a seamed felt that enables various laminate structures, and that can produce a papermaking felt with high productivity, improved smoothness, and no risk of opening.

BRIEF DESCRIPTION OF DRAWINGS

Exemplary embodiment(s) of the present invention will be described in detail based on the following figures, wherein:

FIG. 1A is a diagram illustrating a base fabric according to an exemplary embodiment of the present invention:

FIG. 1B is a diagram illustrating a first laminated portion and a second laminated portion according to the exemplary embodiment illustrated in FIG. 1A;

FIG. 2 is a diagram illustrating a base fabric according to an exemplary embodiment of the present invention;

FIG. 3 is a diagram illustrating a base fabric according to an exemplary embodiment of the present invention;

FIG. 4 is a diagram illustrating a base fabric according to an exemplary embodiment of the present invention;

FIG. 5 is a diagram illustrating a base fabric according to an exemplary embodiment of the present invention;

FIG. 6 is a diagram illustrating a base fabric according to an exemplary embodiment of the present invention;

FIG. 7 is a diagram illustrating a base fabric according to a comparative example;

FIG. 8 is a diagram illustrating a base fabric according to a comparative example;

FIG. 9 is a diagram illustrating a base fabric according to a comparative example; and

FIG. 10 is a diagram illustrating a base fabric according to a comparative example.

DESCRIPTION OF EMBODIMENTS

Hereinafter, aspects of a base fabric for a seamed felt, a papermaking felt, and a method for producing a papermaking felt according to the present invention will be described. However, the present invention is not limited thereto.

In the present description, “A to B” indicating a numerical range means a range including A and B and indicates “A or more and B or less”.

Base Fabric for Seamed Felt

Hereinafter, a base fabric for a seamed felt according to an embodiment of the present invention will be described in detail with reference to FIG. 1A and FIG. 1B and FIG. 2 to FIG. 6 as necessary. An aspect illustrated in FIG. 1A and FIG. 1B and FIG. 2 to FIG. 6 is an aspect of the base fabric for a seamed felt according to the embodiment of the present invention, and the present invention is not limited thereto.

A base fabric A for a seamed felt (hereinafter, may be simply referred to as a “base fabric”) according to the embodiment of the present invention is formed by winding and laminating a single open-ended base fabric B in a single direction by being wound around two winding portions 1. The single open-ended base fabric B includes a first end portion 2 and a second end portion 2 in the single direction. When the single open-ended base fabric B is divided into a first laminated portion 3 and a second laminated portion 3 by a plane passing through top portions 1a of the two winding portions, two or more layers of the single open-ended base fabric B are present in at least one of the first laminated portion 3 and the second laminated portion 3.

The base fabric for a seamed felt according to the embodiment of the present invention includes two winding portions around which an open-ended base fabric, to be described later, is wound.

In the present description, the winding portion refers to a portion where the open-ended base fabric that advances in a single direction draws an arc. For example, in FIG. 1A and FIG. 2 to FIG. 6, a portion in a range indicated by arrows corresponds to the winding portion 1.

In the present description, a top portion of the winding portion refers to an intermediate point between a start point and end point of the arc or an intermediate line formed by gathering the intermediate points.

In the present description, the laminated portions respectively included in two regions seen when the open-ended base fabric is divided by a plane passing through the top portions of the two winding portions are referred to as a first laminated portion and a second laminated portion. For example, in FIG. 1B, laminated portions included respectively in two regions seen when the open-ended base fabric is divided by a plane (indicated by a dotted line in the drawing) passing through the top portions 1a of the two winding portions correspond to the first laminated portion 3 and the second laminated portion 3.

In the base fabric for a seamed felt according to the embodiment of the present invention, a single open-ended base fabric is wound and laminated in a single direction by being wound around two winding portions. By using a single open-ended base fabric to be wound, the number of portions to be joined is reduced, and wrinkles caused by a step derived from a joined portion are less likely to occur. In addition, by using a single open-ended base fabric to be wound, it eliminates the need to butt end portions in the MD direction together and weld them, and it is possible to suppress the occurrence of wrinkles during heat setting.

Here, in the present description, the term “joined” means that parts of the open-ended base fabrics are integrated in a producing step of the base fabric for a seamed felt. In the present description, the term “connect” means that the base fabrics for a seamed felt are coupled together via a seam loop.

In the base fabric for a seamed felt according to the embodiment of the present invention, when the open-ended base fabric is divided into the first laminated portion and the second laminated portion by a plane passing though the top portions of the two winding portions, two or more layers of the open-ended base fabric are present in at least one of the first laminated portion and the second laminated portion.

When only one layer of the open-ended base fabric is present in both the first laminated portion and the second laminated portion, a void volume of the felt is insufficient, making it impossible to produce paper in which a large amount of water is removed, such as paperboard or pulp. In contrast, when two layers of the open-ended base fabric are present in one of the first laminated portion and the second laminated portion and one layer of the open-ended base fabric is present in the other of the first laminated portion and the second laminated portion, the void volume of the felt increases, making it possible to produce paper in which a large amount of water is removed, such as paperboard or pulp.

From a standpoint of water compressing performance, it is preferable that two or more layers of the open-ended base fabric are present in both the first laminated portion and the second laminated portion.

In one aspect of the base fabric for a seamed felt according to the embodiment of the present invention, both the first end portion and the second end portion can be located in either the first laminated portion or the second laminated portion. In such an aspect, the same number of layers of the open-ended base fabric is present on both top portions of the two winding portions. This is preferable because, for example, when the base fabric for a seamed felt according to the embodiment of the present invention is used as a papermaking felt in a papermaking machine, the occurrence of seam marks is suppressed.

In one aspect of the base fabric for seamed felt according to the embodiment of the present invention, the first end portion is located in either the first laminated portion or the second laminated portion, and the second end portion is located in the other of the first laminated portion or the second laminated portion. In such an aspect, the first end portion and the second end portion are located in one of the two winding portions. This is preferable because, for example, when the base fabric for a seamed felt according to the embodiment of the present invention is used as a papermaking felt in a papermaking machine, vibration during use of the felt is suppressed.

In the base fabric for a seamed felt according to the embodiment of the present invention, the first end portion and the second end portion are preferably present on a vertical line perpendicular to the plane passing through the top portions of the two winding portions. This is preferable because in such an aspect, for example, when the base fabric for a seamed felt according to the embodiment of the present invention is used as a papermaking felt in a papermaking machine, vibration is suppressed. Examples of such an aspect include the following combinations. Among the following aspects, aspect b is more preferable because vibration is easily suppressed.

• • Aspect a: The first end portion and the second end portion are present on the vertical line perpendicular to the plane passing through the top portions of the two winding portions, and both the first end portion and the second end portion are located in either the first laminated portion or the second laminated portion.
  • Aspect b: The first end portion and the second end portion are present on the vertical line perpendicular to the plane passing through the top portions of the two winding portions, and the first end portion is located in either the first laminated portion or the second laminated portion, and the second end portion is located in the other of the first laminated portion or the second laminated portion.

In the base fabric for a seamed felt according to the embodiment of the present invention, it is preferable that two or more layers of the open-ended base fabric be present at the respective top portions of the two winding portions. This is preferable because in such an aspect, when the base fabric for a seamed felt according to the embodiment of the present invention is used as a papermaking felt in a papermaking machine, the occurrence of seam marks is suppressed.

In the base fabric for a seamed felt according to the embodiment of the present invention, the distance between at least one selected from the first end portion and the second end portion and at least one of the top portions of the two winding portions is preferably less than 5 cm, more preferably less than 3 cm, and still more preferably less than 1 cm. It is preferable that the distance between at least one selected from the first end portion and the second end portion and the top portion of the winding portion be less than 5 cm, because such an arrangement is effective in suppressing vibration.

The lower limit of the distance between at least one selected from the first end portion and the second end portion and the top portion of the winding portion is not particularly limited, and the distance can be, for example, 1 mm or more, 3 mm or more, or 5 mm or more.

In the present description, the distance between at least one selected from the first end portion and the second end portion and the top portion of the winding portion is not the distance measured along a straight line connecting at least one selected from the first end portion and the second end portion and the top portion of the winding portion, but rather the distance measured along the open-ended base fabric wound and laminated in a single direction. The distance between at least one selected from the first end portion and the second end portion and the top portion of the winding portion refers to the longer of the distance between the first end portion and the top portion of the closer one of the two winding portions, and the distance between the second end portion and the top portion of the closer one of the two winding portions.

In one aspect of the base fabric for a seamed felt according to the embodiment of the present invention, the first end portion and the second end portion of the open-ended base fabric can be joined to the open-ended base fabric. It is preferable that the first end portion and the second end portion of the open-ended base fabric be joined to the open-ended base fabric, because CD yarns near the end portions are less likely to loosen.

There is no particular limitation on the method for joining the first end portion and the second end portion of the open-ended base fabric to the open-ended base fabric. Examples of the joining methods include machine sewing, stitching, adhesives, needling, melting, and the like.

For vibration suppression, more particularly, the first end portion and the second end portion are preferably joined to the open-ended base fabric by machine sewing, and are more preferably joined to the open-ended base fabric by at least one selected from linear sewing and zigzag sewing.

The base fabric for a seamed felt according to the embodiment of the present invention can include a further base fabric in an outermost layer. As used herein, the term “outermost layer” refers to the other of the two surfaces of the base fabric for a seamed felt, which is different from the surfaces that face each other.

Examples of the further base fabric include a tubular-woven base fabric that is woven endless fabric on a loom, a base fabric in which a narrow open-ended base fabric is spirally wound and the end portions in the CD direction are joined to each other, and a base fabric in which the end portions in the MD direction of a wide open-ended base fabric are joined by welding or the like. Among these examples, from the standpoint of productivity, a base fabric obtained by joining the end portions of an open-ended base fabric is preferable, and a base fabric in which the end portions in the MD direction of a wide open-ended base fabric are joined by welding or the like is more preferable.

When the base fabric for a seamed felt includes a further base fabric in the outermost layer, the open-ended base fabric and the further base fabric may be joined to each other or left unjoined. From the standpoint of dimensional stability, it is preferable that the open-ended base fabric and the further base fabric be joined.

When the open-ended base fabric and the further base fabric are joined to each other, the joining method is not particularly limited. Examples thereof include machine sewing, stitching, adhesives, needling, melting, and the like. Among these methods, machine sewing and needling are preferable, and needling is more preferable, from the standpoint of dimensional stability.

One of the further advantageous effects achieved by the base fabric for a seamed felt according to the embodiment of the present invention is low production cost. When open-ended plain-woven base fabrics are joined by welding to form an endless configuration, and a plurality of such endless base fabrics are subsequently laminated, it is necessary to perform cutting, welding, and heat setting for each base fabric. However, in the base fabric according to the embodiment of the present invention, even when the number of layers when being formed as a felt is increased to an infinite number, cutting and heat setting are required only once, and welding is not performed.

The base fabric for a seamed felt according to the embodiment of the present invention enables various laminate structures.

In a seamed felt in the related art in which open-ended plain-woven base fabrics are joined by welding to form an endless configuration, and then seam loops are formed at a folded portion, to adjust the void volume of the felt, it is necessary to add one plain-woven base fabric to the outside to make the number of layers of the base fabric odd. Meanwhile, since an end portion in the MD direction of the added base fabric is not joined, the CD yarn at the end portion is loosened.

In contrast, in the base fabric for a seamed felt according to the embodiment of the present invention, even when the number of layers when being formed as a felt is an odd number, the CD yarn on the end portion is not loosened because the end portions in the MD direction are joined.

Open-Ended Base Fabric

The open-ended base fabric used in the present embodiment is a base fabric having an end portion.

A constituent material of fibers constituting a yarn used for the base fabric is preferably a thermoplastic resin having a heat-resistant temperature of 60° C. to 200° C. and a melting point of 80° C. to 300° C. For example, a polyethylene resin, a polypropylene resin, a polystyrene resin, an acrylic resin, a polyethylene terephthalate resin, a polyamide resin, an acetal resin, a polycarbonate resin, and the like can be used as the MD yarn and the CD yarn, and among these resins, a polyamide resin is preferable.

A form of the fibers constituting the yarn used for the base fabric may be a monofilament, a multifilament, a spun yarn, a processed yarn such as a textured yarn, a bulky yarn, or a stretch yarn that is subjected to crimping processing or bulking processing, or a twist yarn formed by twisting these yarns. A cross-sectional shape of the fiber may be circular, substantially elliptical, polygonal, substantially star-shaped, substantially rectangular, or the like.

A fineness of the fibers constituting the yarn used for the base fabric is not particularly limited. When the yarn used for the base fabric is a monofilament, the fineness can be preferably 89 dtex to 2240 dtex (0.10 mm to 0.50 mm), and more preferably 200 dtex to 1440 dtex (0.15 mm to 0.40 mm). In contrast, when the yarn used for the base fabric is a multifilament, the fineness of a monofilament constituting the multifilament is usually 20 dtex to 90 dtex, and preferably 40 dtex to 60 dtex. The number of fibers constituting the multifilament is usually 5 to 20, preferably 7 to 15. When these yarns are twisted to form a twist yarn, the number of yarns is usually 2 to 15, preferably 3 to 10.

The yarns constituting the base fabric may be of one kind only or of two or more kinds.

The base fabric may have either a single weave structure or a multiple weave structure. The kind of weave structure is not particularly limited, and examples thereof may include any weave structure, such as plain weave, twill weave, satin weave, modified weave or other kinds of weave structures, and a combination thereof.

A basis weight of the base fabric is not particularly limited and can be usually 100 g/m² to 1000 g/m², preferably 200 g/m² to 800 g/m². A thickness of the base fabric is not particularly limited, and can be usually 0.4 mm to 2.0 mm, preferably 0.6 mm to 1.1 mm. A density of the base fabric is not particularly limited and can be usually 0.25 g/cm³ to 0.75 g/cm³, preferably 0.35 g/cm³ to 0.65 g/cm³.

The dimensions of the base fabric are not particularly limited as long as the dimensions satisfy the requirements of a final product (a papermaking felt) when the base fabric is wound. The number of layers is preferably determined depending on the required void volume. In this case, a length of the base fabric is equal to a length obtained by multiplying the length of the final product by the number of layers, when the seam loop portions are connected to form an endless configuration on the papermaking machine.

A winding angle of the base fabric with respect to an extension direction of the MD yarn and/or the CD yarn is not particularly limited as long as the base fabric is wound in a single direction. Examples of the winding angle include 0° with respect to the extension direction of the MD yarn and/or the CD yarn, and an angle inclined with respect to the extension direction of the MD yarn and/or the CD yarn. From the standpoint of the yield and the dimensional stability of the base fabric during production, the angle is preferably 0° with respect to the extension direction of the MD yarn and/or the CD yarn.

In a case where the base fabric is wound at an angle inclined with respect to the extension direction of the MD yarn and/or the CD yarn, the following method can be adopted: an open-ended base fabric having a width that is wider than the final product (the papermaking felt) is cut from a raw fabric, then wound or machine-sewn to obtain a base fabric for a seamed felt, and finally the width is trimmed to match the dimensions of the final product (the papermaking felt).

Papermaking Felt

The papermaking felt according to the embodiment of the present invention is formed by connecting the base fabrics for a seamed felt described above via seam portions formed at the two winding portions. Specifically, a seam loop of the base fabric for a seamed felt may be fitted to another seam loop to engage these seam loops, and a pintle wire may be inserted into a tunnel-shaped space formed by the engaged seam loops to connect the base fabrics for a seamed felt. By repeating this operation one or more times, an endless papermaking felt can be formed on the papermaking machine.

In the papermaking felt according to the embodiment of the present invention, a nonwoven fabric is preferably entangled on both a wet paper web side surface and roll side surface of the base fabric for a seamed felt. According to this aspect, the roll side surface of the base fabric for a seamed felt constituting the papermaking felt can be prevented from being damaged.

A basis weight of the papermaking felt according to the present invention is not particularly limited, and is preferably 1000 g/m² or more, more preferably 1200 g/m² or more, still more preferably 1400 g/m² or more, and particularly preferably 1600 g/m² or more.

The basis weight of the papermaking felt being 1000 g/m² or more is preferable, because it makes it possible to handle a large amount of water to be removed from wet paper web.

Method for Producing Papermaking Felt

A method for producing a papermaking felt according to the embodiment of the present invention can include winding the base fabric for a seamed felt described above around the two winding portions (hereinafter, also referred to as “step 1”) and removing CD yarns of outermost layers at the two winding portions to form a seam loop (hereinafter, also referred to as “step 2”) in this order.

The method for producing a papermaking felt according to the embodiment of the present invention can include steps other than the step 1 and step 2. Examples of the other steps include entangling the nonwoven fabric on both the wet paper web side surface and roll side surface of the base fabric for a seamed felt.

EXAMPLES

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples.

Production of Base Fabric for Seamed Felt

Base Fabric for Seamed Felt in Example 1

Using MD yarns and CD yarns, a 1/1 plain-woven base fabric was woven by a loom to obtain a raw fabric of a base fabric for a seamed felt (hereinafter may be simply referred to as a “raw fabric”).

A single open-ended base fabric having the same width and six times the length of the final product was cut out from the raw fabric and wound three times in a single direction around the two winding portions. Thereafter, the first end portion and the second end portion were joined to the open-ended base fabric by machine sewing by zigzag sewing. Furthermore, the machine sewing by zigzag sewing was performed on the two winding portions starting from the vicinity of the winding start point of each winding portion to pass through the first laminated portion and the second laminated portion. Then, the CD yarns of the outermost layers of the two winding portions were removed, and seam loops were formed therein to obtain a base fabric for a seamed felt in Example 1.

The base fabric for a seamed felt in Example 1 has a structure schematically illustrated in FIG. 1A. That is, the first end portion 2 and the second end portion 2 were located in either the first laminated portion or the second laminated portion, were present on a vertical line perpendicular to a plane passing through the top portions of the two winding portions 1, were not present in any of the two winding portions 1, and were present in a central portion of start positions of the two winding portions 1.

In FIG. 1A, a location where machine sewing was performed, that is, a coupling portion is indicated by a broken line. The same applies to FIG. 2 to FIG. 10. The number of the joined portions in FIG. 1A is four in total, that is, portions where the open-ended base fabrics were integrated together in the process of producing the base fabric for a seamed felt, i.e., two locations where the first end portion 2 and the second end portion 2 were joined to the open-ended base fabric by machine sewing, and two locations where machine sewing was performed on the two winding portions 1 so as to penetrate through the first laminated portion and the second laminated portion.

Base Fabric for Seamed Felt in Example 2

A single open-ended base fabric having the same width and eight times the length of the final product was cut out from the raw fabric and wound four times in a single direction around the two winding portions. A base fabric for a seamed felt in Example 2 was obtained in the same manner as in Example 1 from machine sewing for the first end portion and the second end portion to seam loop formation. A positional relationship between the first end portion and the second end portion regarding the first laminated portion, the second laminated portion, the vertical line perpendicular to the plane passing through the top portions of the two winding portions 1, and the two winding portions 1 was the same as that in Example 1. The base fabric for a seamed felt in Example 2 has a structure schematically illustrated in FIG. 2.

Base Fabric for Seamed Felt in Example 3

A single open-ended base fabric having the same width and five times the length of the final product was cut out from the raw fabric and wound 2.5 times in a single direction around the two winding portions. A base fabric for a seamed felt in Example 3 was obtained in the same manner as in Example 1 from machine sewing for the first end portion and the second end portion to seam loop formation.

The base fabric for a seamed felt in Example 3 has a structure schematically illustrated in FIG. 3. That is, the first end portion 2 and the second end portion 2 were located in either the first laminated portion or the second laminated portion, were not present on the vertical line perpendicular to a plane passing through the top portions of the two winding portions 1, and were present in each of the two winding portions 1.

Base Fabric for Seamed Felt in Example 4

A single open-ended base fabric having the same width and six times the length of the final product was cut out from the raw fabric and wound three times in a single direction around the two winding portions. A base fabric for a seamed felt in Example 4 was obtained in the same manner as in Example 1 from machine sewing for the first end portion and the second end portion to seam loop formation.

The base fabric for a seamed felt in Example 4 has a structure schematically illustrated in FIG. 4. That is, the first end portion 2 is located in either the first laminated portion or the second laminated portion, and the second end portion 2 is located in the other of the first laminated portion or the second laminated portion, were present on a vertical line perpendicular to a plane passing though the top portions of the two winding portions 1, and were present in one of the two winding portions 1.

Base Fabric for Seamed Felt in Example 5

A single open-ended base fabric having the same width and four times the length of the final product was cut out from the raw fabric and wound two times in a single direction around the two winding portions. A base fabric for a seamed felt in Example 5 was obtained in the same manner as in Example 1 from machine sewing for the first end portion and the second end portion to seam loop formation. A positional relationship between the first end portion and the second end portion regarding the first laminated portion, the second laminated portion, the vertical line perpendicular to the plane passing through the top portions of the two winding portions 1, and the two winding portions 1 was the same as that in Example 4. The base fabric for a seamed felt in Example 5 has a structure schematically illustrated in FIG. 5.

Base Fabric for Seamed Felt in Example 6

A single open-ended base fabric having the same width and three times the length of the final product was cut out from the raw fabric and wound 1.5 times in a single direction around the two winding portions. A base fabric for a seamed felt in Example 6 was obtained in the same manner as in Example 1 from machine sewing for the first end portion and the second end portion to seam loop formation.

The base fabric for a seamed felt in Example 6 has a structure schematically illustrated in FIG. 6. That is, the first end portion 2 and the second end portion 2 were located in either the first laminated portion or the second laminated portion, were not present on a vertical line perpendicular to a plane passing through the top portions of the two winding portions 1, and were present in each of the two winding portions 1.

Base Fabric for Seamed Felt in Comparative Example 1

A single open-ended base fabric having the same width and twice the length of the final product was cut out from a raw fabric, and end portions in the MD direction were butted against each other and joined by ultrasonic welding to form an endless configuration. Thereafter, CD yarns in two folded portions were removed, and a seam loop was formed therein to obtain a base fabric for a seamed felt in Comparative Example 1. The base fabric for a seamed felt in Comparative Example 1 has a structure schematically illustrated in FIG. 7.

In FIG. 7, a portion in a range indicated by an arrow corresponds to a folded portion 11, and a portion indicated by a black circle corresponds to a portion (a welded portion 12) joined by ultrasonic welding. The same applies to FIG. 8 to FIG. 10.

Base Fabric for Seamed Felt in Comparative Example 2

Two pieces of endless base fabrics similar to that in Comparative Example 1 were produced, and one endless base fabric was disposed inside the other endless base fabric to form a laminate structure. Thereafter, CD yarns in two folded portions of the outer base fabric were removed, and a seam loop was formed therein to obtain a base fabric for a seamed felt in Comparative Example 2. The base fabric for a seamed felt in Comparative Example 2 has a structure schematically illustrated in FIG. 8.

Base Fabric for Seamed Felt in Comparative Example 3

A single open-ended base fabric having the same width and the same length as those of the final product cut out from a raw fabric was disposed on the outside of a base fabric for a seamed felt similar to that in Comparative Example 2 to form a laminate structure. The base fabric for a seamed felt in Comparative Example 3 has a structure schematically illustrated in FIG. 9.

Base Fabric for Seamed Felt in Comparative Example 4

After the similar base fabric for a seamed felt as in Comparative Example 2 was produced, a temporary pintle wire for needling was inserted into tunnel-shaped spaces formed by two seam loops and connected. Then, a single endless base fabric (a tubular-woven base fabric obtained by endlessly weaving on a loom) having the same width and the same length as those of the final product formed of the same yarn and structure as those of the raw fabric was disposed on the outside to obtain a base fabric for a seamed felt in Comparative Example 4. The base fabric for a seamed felt in Comparative Example 4 has a structure schematically illustrated in FIG. 10, that is, a structure in which seam loop portions are connected.

In FIG. 10, the endless base fabric is represented by a reference sign B′. In a state of the base fabric for a seamed felt, a broken line above a loop of the endless base fabric B′ in FIG. 10 is not cut and is connected.

Production of Papermaking Felt

Papermaking Felts in Examples 1 to 6 and Comparative Examples 1 to 3

After the base fabric for a seamed felt was produced, a temporary pintle wire for needling was inserted into tunnel-shaped spaces formed by two seam loops, the nonwoven fabric was laminated, entangled, and integrated, the temporary pintle wire was pulled out, and a fiber layer above the loop was cut and separated to obtain papermaking felts in Examples 1 to 6 and Comparative Examples 1 to 3.

Papermaking Felt in Comparative Example 4

After the nonwoven fabric was laminated, entangled, and integrated, the temporary pintle wire was pulled out, and the fiber layer above the loop and the tubular-woven base fabric were cut and separated to obtain a papermaking felt in Comparative Example 4.

In FIG. 10, a broken line above the loop corresponds to a portion where the endless base fabric B′ was cut and separated.

Evaluation of Base Fabric for Seamed Felt and Papermaking Felt

The papermaking felts in Examples 1 to 6 and Comparative Examples 1 to 4 were evaluated as follows. Results are shown in Table 1.

(Wrinkles after Heat Setting)

The base fabric for a seamed felt was hung on a pair of rolls, and heat setting was performed under conditions of 100° C. and five rounds with a heat source from the inside and outside of the rolls while adjusting a roll gap to a predetermined dimension.

Regarding the base fabric after the heat setting, in Examples, the occurrence of wrinkles in joined portions by machine sewing in the vicinity of the first end portion and the second end portion and in the vicinity of the two winding portions were observed, and in Comparative Examples, an occurrence situation of wrinkles in the joined portions by welding and machine sewing in the vicinity of the two winding portions were observed.

(CD Yam Loosening at End Portion)

The papermaking felt was tested on a high-speed and high-pressure papermaking machine tester, and the occurrence of loosening of the CD yarn at the first end portion and the second end portion in Examples, and the occurrence of loosening of the CD yarn at the MD end portion of the base fabric disposed on the outside in Comparative Examples 3 and 4, was observed. Running conditions were a sheet making speed of 1000 m/min, a pressure of 100 kN/m, and HPS 30 kg/cm².

(Vibration)

An acceleration (an overall value (OA value) in a pressurizing direction in FFT analysis in a vibrometer was measured for the papermaking felt. Running conditions were a speed of 1000 m/min and a pressure of 100 kg/cm. In general, when this value is less than 0.3, the vibration is good.

	TABLE 1
	Configuration

Base fabric for papermaking felt

The number

of joined

Evaluation

Number of

End

portions

Papermaking felt

	layers of	portions		Position	Number of	Number of	and welded	Base fabric	CD yarn
	base	location	On vertical	of end	joined	welded	portions per	Wrinkles	loosening	Vibration
	fabric (*1)	(*2)	line (*3)	portion	portions	portions	base fabric	(*4)	(*5)	(OA value)

Example 1	6	Yes	Present	Central	4	0	0.7	None	None	0.2
				portion
Example 2	8	Yes	Present	Central	4	0	0.5	None	None	0.2
				portion
Example 3	5	Yes	Not present	Winding	2	0	0.4	None	None	0.1
				portion
Example 4	6	No	Present	Winding	2	0	0.3	None	None	0.1
				portion
Example 5	4	No	Present	Winding	2	0	0.5	None	None	0.1
				portion
Example 6	3	Yes	Not present	Winding	2	0	0.7	None	None	0.1
				portion
Comparative	2	—	—	—	2	1	1.5	Present	—	0.4
Example 1
Comparative	4	—	—	—	2	2	1.0	Present	—	0.5
Example 2
Comparative	5	—	—	—	2	2	0.8	Present	Present	0.4
Example 3
Comparative	5	—	—	—	2	2	0.8	Present	Present	0.4
Example 4
(*1) represents the number of base fabrics threaded onto a papermaking machine.
(*2): “Yes” means that the first end portion and the second end portion are located in either the first stacked portion of the second stacked portion. “No” means that the first end portion is located in either the first stacked portion or the second stacked portion, and the second end portion is located in the other of the first stacked portion or the second stacked portion.
(*3) represents whether the first end portion and the second end portion are present on a vertical line perpendicular to a plane passing through the top portions of the two winding portions.
(*4) represents the presence of absence of wrinkles in the first end portion and the second end portion in Examples, and in the joined portion caused by welding in Comparative Examples.
(*5) represents the presence or absence of occurrence of the CD yarn loosening at the first end portion and the second end portion in Examples and at the MD end portion of the base fabric disposed on the outside in Comparative Examples 3 and 4.

From the results illustrated in Table 1, it can be seen that in the base fabric for a seamed felt in Examples, compared to the base fabric for a seamed felt in Comparative Examples, wrinkles at the joined portion or loosening of the CD yarn at the end portion were not caused, and the occurrence of vibration is suppressed. Particularly, it can be observed that the occurrence of vibration is reduced in the base fabric for a seamed felt in Example, which has a small number of locations per base fabric that can contribute to vibration, namely, the total number of joined portions and welded portions.

The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.

INDUSTRIAL APPLICABILITY

Since the base fabric for a seamed felt according to the present invention can provide a papermaking felt having a laminate structure which is excellent in smoothness and has no yarn loosening or vibration, the base fabric for a seamed felt can be used for producing various kinds of paper, such as newspaper, high-quality paper, paperboard, pulp, and household paper, particularly paper such as paperboard and pulp having a large amount of water to be removed.

DESCRIPTION OF REFERENCE NUMERALS

• • A: Basic fabric for sealed felt
  • B: Open-ended base fabric
  • B′: Endless base fabric
  • 1: Winding portion
  • 1a: Top portion of winding portion
  • 2: First end portion and Second end portion
  • 3: First laminated portion and Second laminated portion
  • 11: Folded portion
  • 12: Welded portion