Industrial Fabric

The present invention relates to industrial fabrics used for producing nonwoven fabrics.

In the related art, industrial fabrics woven using warps and wefts have been widely used as industrial fabrics used for nonwoven fabric manufacturing devices. The characteristics required for industrial fabrics vary. For example, Patent Literature 1 discloses a multilayer weave for a nonwoven fabric having a first warp, a second warp, an upper surface side weft, and a lower surface side weft. This multilayer weave for a nonwoven fabric is formed by weaving the first warp with all the wefts from the upper surface side weft to the lower surface side weft and weaving the second warp with only the upper surface side weft.

An industrial fabric is attached to a nonwoven fabric manufacturing device in the form of an endless belt. A plurality of loops are formed by warps at both ends of the industrial fabric, and wefts are inserted into the loops to join the two ends of the industrial fabric, making the industrial fabric endless. In the multilayer weave for a nonwoven fabric described in Patent Literature 1, since a second warp is woven only into an upper surface side weft having a small wire diameter, the loop formed by folding back the second warp may protrude to the upper surface side in alignment with the position of the upper surface side weft, possibly forming a height difference in the belt. If by any chance a height difference is formed in the belt, the uniformity of the nonwoven fabric produced using the belt is impaired only in the part of the height difference, causing poor formation of the nonwoven fabric.

A purpose of the present invention is to provide industrial fabrics having loops which become smooth and have a stable shape when made into an endless belt.

In order to solve the above problem, one embodiment of the present invention relates to an industrial fabric including: first warps; second warps; first wefts; and second wefts, wherein the first warps and the second warps are provided while being shifted in a weft direction, wherein the first wefts and the second wefts are provided while being shifted in a warp direction, wherein the second wefts are located on the upper surface side of the industrial fabric, wherein the first warps are woven only into the first wefts, and wherein the second warps are woven into the first wefts and the second wefts.

The invention will now be described by reference to the preferred embodiments. This does not intend to limit the scope of the present invention, but to exemplify the invention. In the following explanation, “warps” are threads extending along the direction of conveyance of paper materials, and “wefts” are threads extending in a direction that intersects the warps, when a multilayer weave for papermaking constitutes an endless belt. Further, an “upper surface side” means to be located on the side where the materials are conveyed out of the two sides of a belt for nonwoven fabrics, and a “lower surface side” means to be located mainly on the side where a drive roller is in contact out of the two sides of the belt for nonwoven fabrics. An “obverse surface” is a surface exposed on the upper surface side or the lower surface side.

Further, the term “design diagram” represents the minimum repeating unit of a weave texture and corresponds to a weave repeat of the weave. In other words, a “weave repeat” is repeated from front to back and left to right to form a “weave.” Further, “knuckles” refers to parts where a warp is exposed on the obverse surface after passing above or below a single or multiple wefts.

is a design diagram showing a weave repeat of an industrial fabricaccording to an exemplary embodiment.is a cross-sectional view in the warp direction along warps of the industrial fabricshown in.shows a cross-section of a first warp pair composed of a first warpand a first warp, andshows a cross-section of a second warp pair composed of a second warpand a second warp

In the design diagram, warps are indicated by Arabic numerals, e.g.,,,, and so on. Wefts are indicated by Arabic numerals with dashes, e.g.,′,′,′, and so on. The first warps and the first wefts are indicated by numbers with f, and the second warps and the second wefts are indicated by numbers with s.

In the design diagram, x marks indicate that the first and second warps are arranged above the first and second wefts, and unmarked squares indicate that the first and second warps are arranged below the first and second wefts.

An industrial fabricshown inincludes first warps (,,, and), second warps (,,, and), first wefts (′,′,′, and′), and second wefts (′,′,′, and′). In a weave repeat that forms a repeating pattern of the industrial fabric, there are eight warps: the first warps (,,, and); and the second warps (,,, and), and there are eight wefts: the first wefts (′,′,′, and′); and the second wefts (′,′,′, and′).

The first wefts (′,′,′, and′) may have a larger wire diameter than the second wefts (′,′,′, and′) and be set to, for example, a size that is 1.5 to 3 times the wire diameter of the second wefts (′,′,′, and′). In the weave repeat, there are four first warps (,,, and), there are four second warps (,,, and), there are four first wefts (′,′,′, and′), and there are four second wefts (′,′,′, and′). The relationship between the first and second wefts will be explained now with reference to.

is a cross-sectional view along a first warpof the industrial fabricshown in. The first wefts (′,′,′, and′) and the second wefts (′,′,′, and′) are arranged alternately. This allows the second wefts to be arranged between the first wefts, which have a large wire diameter, so as to function as floating yarns.

The first wefts (′,′,′, and′) and the second wefts (′,′,′, and′) are provided while being shifted from each other in the warp direction. The first weft′and the second weft′are spaced apart from each other in the warp direction by a gap C, and the other first and second wefts also have the same gap C. The gap C between the first and second wefts serves as a space for weaving the first warp and the second warp around the first weft that serves as the axis.

The second wefts (′,′,′, and′) are located on the upper side of the industrial fabric. A line Lpassing through the center of the plurality of second wefts (′,′,′, and′) is located on the upper side of a line Lpassing through the center of the plurality of first wefts (′,′,′, and′). This allows the second wefts (′,′,′, and′) to function as floating yarns.

The description now returns toand. The first warps (,,, and) are woven only into the first wefts (′,′,′, and′). The first warps are not woven into the second wefts and prevent the second wefts from being pulled to the lower surface side. The second warps (,,, and) are woven into the first wefts (′,′,′, and′) and the second wefts (′,′,′, and′). The second warps are also woven into the second wefts, tying the second wefts to the first wefts.

The first warps (,,, and) have a weaving pattern of passing below all the second wefts (′,′,′, and′) and alternately going above and below the first wefts (′,′,′, and′). This allows the first warps to be finely woven only into the first wefts.

A pair of first warps (and) are adjacent to each other in the weft direction to form a first warp pair. The other pair of first warps (and) are adjacent to each other in the weft direction to form a first warp pair in the same manner. The adjacent first warps (and, andand) forming the first warp pairs are woven into the first wefts (′,′,′, and′) while being shifted from each other by one first weft with respect to the first wefts in the warp direction. The first warps (,,, and) form a weaving pattern of being woven into the first wefts (′,′,′, and′) while alternately going above and below the first wefts. As shown in, this allows a pair of first warps to be woven into the first wefts so as to sandwich the first wefts from above and below, and the second wefts are arranged to float on the upper surface side by the pair of first warps. The arrangement of the second wefts as floating yarns between the first wefts with a thick wire diameter makes the mesh of the industrial fabricfiner and suppresses the sticking-in of nonwoven fabric fibers.

In a weave repeat that forms a repeating pattern of the industrial fabric, the weaving pattern of one first warp pair (and) and the weaving pattern of the other first warp pair (and) are identical. More specifically, the weaving pattern of the first warpand the weaving pattern of the first warpare identical, and the weaving pattern of the first warpand the weaving pattern of the first warpare identical. Having the identical weaving patterns means that the first wefts into which the first warps are woven are the same.

A pair of second warps (and) are adjacent to each other in the weft direction to form a second warp pair. The other pair of second warps (and) are adjacent to each other in the weft direction to form a second warp pair in the same manner. The pairs of second warps (and, andand) forming the second warp pairs are woven into the second wefts (′,′,′, and′) in the warp direction while being shifted from each other by two second wefts with respect to the second wefts in the warp direction. In other words, the second warpis woven so as to pass over the second weft′, and the second warpis woven so as to pass over the second weft′. Thus, the weaving pattern of the second warpand the weaving pattern of second warpare shifted by two second wefts with respect to the second wefts.

The second warpforms a weaving pattern of passing above one first weft′, one second weft′, and one first weft′in order and then passing below one second weft′, one first weft′, one second weft′, one first weft′, and one second weft′in order. Each of the other second warps (,, and) forms a weaving pattern of passing above one first weft, one second weft, and one first weft in order and then passing below one second weft, one first weft, one second weft, one first weft, and one second weft in order. In other words, each of the second warps (,,, and) forms a common weaving pattern.

In a weave repeat that forms a repeating pattern of the industrial fabric, two second warp pairs (and, andand) have a common weaving pattern. One second warp pair (and) and the other second warp pair (and) form a weaving pattern of being shifted from each other by one weft in the warp direction with respect to the first or second wefts. The second warpand the second warpare provided while being shifted from each other by one first weft with respect to the first wefts, and the second warpand second warpare provided while being shifted from each other by one first weft with respect to the first wefts. Thus, the two second warp pairs (and, andand) share the same weaving pattern but are provided while being shifted from each other in the warp direction. This allows the first wefts and the second wefts to be woven evenly.

The first wefts (,,, and) and the second wefts (,,, and) are provided while being shifted from each other in the weft direction. For example, although the first warpmay come into contact with the second warpin the weft direction, the warps are arranged so as not to overlap in the weft direction since the warps are both woven into the first weft′. The first warps (,,, and) are also provided while being shifted from each other in the weft direction, and the second warps (,,, and) are also provided while being shifted from each other in the weft direction. As a result, the eight warps are arranged side by side in the weft direction.

The first warp pairs (and, andand) and the second warp pairs (and, andand) are arranged alternately in the weft direction. By arranging the first warp pairs alternately one set at a time, spaces created between the warps and the wefts can be made uniform.

The density of the first wefts (,,, and) and the density of the second wefts (,,, and) are in the range of 90 percent to 140 percent. Since the density DW of the warps is large, the mesh (gaps) of the industrial fabricare small, and the sticking-in of the fibers of the nonwoven fabric are less likely to occur, thus resulting in good releasability. This density DW of the warps is calculated by the following Expression 1.

DW represents the warp density, D represents the diameter (in millimeters) of the warps, and M indicates a mesh count, which refers to the number of warps per inch. The diameter of the first warps and the diameter of the second warps may be the same.

Resin may be applied to the upper surface of the industrial fabricto improve gripping force. For example, if the gripping force of the industrial fabricis small, a nonwoven sheet to be formed may be folded due to the movement of the nonwoven sheet on the industrial fabricat the time of the conveyance of the nonwoven sheet on the industrial fabric, which may lead to a decrease in the quality rate of nonwoven fabrics. Applying resin to the industrial fabricimproves the gripping force of the industrial fabric. Since the peak of a knuckle of a first warp is located on the inner side of the industrial fabricthan the peak of a second warp, when resin is applied to the industrial fabric, the resin attached to the peak of the knuckle of the first warp is less likely to come into contact with the press rolls or the like of a nonwoven manufacturing device, and even if the resin attached to the peak of the knuckle of the second warp peels off, it is possible to prevent peeling of all the resin throughout the entire industrial fabric.

At least some of the second warps (,,, and) are conductive carbon yarns. All of the second warps (,,, and) may be conductive carbon yarns. By weaving conductive carbon yarns into the industrial fabric, the industrial fabriccan be provided with a static electricity removing property. If static electricity is charged on the industrial fabric, the industrial fabricand the nonwoven web may repel each other, making it impossible to form a good nonwoven fabric.

is a diagram for explaining loops formed by a second warp in the industrial fabric.shows a first loop,shows a second loop, andshows a third loop. When the first loop, the second loop, and the third loopare not to be distinguished, the loops are simply referred to as loops.

A loopis formed by folding back a warp and forms a space for passing a first weft having a large wire diameter. When attaching the industrial fabricto the nonwoven fabric manufacturing device, the operator wraps the industrial fabricaround a plurality of rolls and connects the two ends of the industrial fabricso as to form an endless belt. When connecting the ends of the industrial fabric, the operator inserts a weft for looping into the loop. The weft for looping may have the same wire diameter as that of the first weft or may have a smaller wire than that of the first weft.

In, wefts for looping that are inserted into loopsare shown in black. If the shape of a loopvaries, it becomes difficult to insert a weft for looping, and the weft for looping is likely to get caught on the loopwhen being inserted. The width of the industrial fabriccan be several meters or more, and when inserting a weft for looping having that length, it is desirable for the loopto be well-shaped. Furthermore, when the weft for looping is inserted into the loop, the weft may get caught in the loop, causing the loopto shift or tilt, resulting in differences in the breathability of the fabric in some parts.

The first loopshown informs a large loop that allows two wefts for looping (′and′) to pass through using the second warp. Further, the second loopshown informs a large loop that allows the two wefts for looping (′and′) to pass through using the second warp. The weft′located on the right side of the first loopshown inis a weft for looping and is woven by folding a warp that is not shown. The weft′located on the left side of the second loopshown inis a weft for looping and is woven by folding a warp that is not shown.

The third loopshown informs a small loop that allows one weft for looping to pass through using the second warpand the second warp. The weft′for looping is inserted into the third loopformed by the second warp, and the weft′for looping is inserted into the third loopformed by the second warp. The loopsshown inare arranged in order along the weft direction. This connects both ends of the industrial fabric.

is a diagram for explaining a small loopformed by a first warp. The first warpis folded back to form the small loop. One weft′for looping is inserted into the small loop. The first warpis folded back and woven as the first warp

If the loop is formed by a warp into which only a second weft is woven, the position of the loop will be at a height that matches the second weft located on the upper surface side, and the loop will be formed protruding above the height of the first weft on the upper surface side. In the industrial fabric, since all the warps are woven into the first wefts with a large wire diameter, the loopsand the small loopare all arranged to match the height of the first wefts, thus allowing the industrial fabricto be formed well with less variation in position and shape of the loops. The stabilization of the shape of the loopsmakes it easier to insert the wefts for looping and facilitates the process of joining the two ends of the industrial fabric. Further, the wefts for looping are less likely to get caught on the loopswhen being inserted, which makes it possible to suppress the shifting or tilting of the loops, and the formation of marks resulting from the loopson a nonwoven fabric placed on the loopportion can thus be suppressed. The stabilization of the shape of the loopsmakes it possible to form large loops.

As shown in, the industrial fabrichas both a large loop into which two wefts for looping can be inserted and a small loop into which one weft for looping can be inserted but is not limited to this form. For example, the industrial fabricmay have only a large loop into which two wefts for looping can be inserted or only a small loop into which one weft for looping can be inserted.

In the industrial fabric, the first and second warps are arranged in a row of two warps each. Therefore, a loopcan be formed, for example, by folding back the second warpand weaving the second warpinto the adjacent second warp

Since the weaving patterns of the two first warp pairs are identical, i.e., the weaving pattern of the first warpand the weaving pattern of the first warpare identical and the weaving pattern of the first warpand the weaving pattern of the first warpare identical, the inclination direction of the loops can be aligned, making it easier to insert the wefts for looping.

An industrial fabric according to each of the above exemplary embodiments may be subjected to the following processing. For example, in order to improve the surface smoothness, the obverse surface side of the industrial fabric may be polished in the range of 0.02 to 0.05 mm. In particular, the obverse surface side may be polished by 0.02 mm or 0.03 mm.

Further, in order to suppress the fraying of yarns at a mesh (industrial fabric) edge, the mesh may be reinforced by coating with a polyurethane resin in the range of 5 mm to 30 mm, particularly in the range of 5 mm, 10 mm, or 20 mm, from the mesh edge. The coating of the mesh edge may be applied on one or both sides. The resin may be hot melt polyurethane and may be conductive.

In order to improve the wear resistance of a mesh edge, the mesh may be coated in the range of 20 mm to 500 mm (particularly 25, 50, 75, 100, 150, 250, 300, 350, or 400 mm) from the mesh edge with three to sixteen (particularly three, four, seven, eight, ten, twelve, fifteen, or sixteen) strips of resin of a width of about 7 mm over the entire length. The plurality of above-mentioned strips of polyurethane resin may be applied to both edges of the mesh or only to one side. The resin may be hot melt polyurethane.

The following is a list of preferred element ranges for an industrial fabric. The wire diameter of warps is preferably 0.10 mm to 1.0 mm, more preferably 0.2 mm to 0.6 mm, and particularly preferably 0.3 mm to 0.5 mm, where the warps include the first warps and the second warps. The diameter of the warps may be the same. The wire diameter of the wefts is preferably 0.10 mm to 1.2 mm, more preferably 0.2 mm to 1.0 mm, and particularly preferably 0.4 mm to 0.9 mm.

The second wefts may be composed of only PET wires or only polyamide wires, may be alternately interwoven PET and polyamide wires, or may be conductive carbon yarns. The first wefts may be composed of only PET wires, only polyamide wires, or alternately interwoven PET and polyamide wires, or may be conductive carbon yarns. Also, in order to reduce the driving load of the machine, low-friction yarns may be woven with the first wefts.

The air permeability is preferably 100 cm/cm/s to 600 cm/cm/s and more preferably 200 cm/cm/s to 400 cm/cm/s.

The mesh thickness is preferably 0.3 mm to 3.0 mm, more preferably 0.5 mm to 2.5 mm, and particularly preferably 1.0 mm to 2.5 mm. The usage applications mainly include usage as a nonwoven fabric belt and particularly as a spunbond nonwoven fabric conveying belt.

The cross-sectional shape of the warps and wefts according to each of the above-mentioned exemplary embodiments is not limited to a circular shape, and yarns having a quadrangular shape, a star shape, etc., and yarns having an elliptical shape, a hollow shape, a sheath-core structure shape, etc., can be used. In particular, by making the cross-sectional shape of the warps have a square shape, a rectangular shape, or an elliptical shape, the cross-sectional area of the yarns can be increased, and elongation resistance and rigidity can thus be improved. The cross-sectional shape of the second wefts being elliptical or rectangular reduces voids on the obverse surface of the industrial fabriccompared to a circular shape and thus allows for the suppression of the sticking of nonwoven fibers into the obverse surface of the industrial fabric.

Further, the yarn material can be freely selected as long as the yarn satisfies the desired characteristics, and polyethylene terephthalate, polyester, polyamide, polyphenylene sulfide, polyvinylidene fluoride, polypropylene, aramid, polyether ether ketone, polyethylene naphthalate, polytetrafluoroethylene, cotton, wool, metals, thermoplastic polyurethane, thermoplastic elastomers, etc., can be used. Needless to say, yarns prepared from a copolymer and yarns prepared by blending or adding various substances to such a material may be used according to the purpose. In general, polyester monofilaments having rigidity and excellent dimensional stability are preferably used as yarns constituting industrial fabrics.

The present invention relates to industrial fabrics used for producing non-woven fabrics.