Nonwoven fabric, its manufacturing method, and wiper

Abstract

To provide a nonwoven fabric having stronger tensile strength in a direction orthogonal to a direction in which columns configuring a stripe are extended.SOLUTION: A nonwoven fabric includes a first entanglement section and a second entanglement section. The first entanglement section and the second entanglement section exist in a striped state. The second entanglement section and the first entanglement section have different patterns from each other or any one of the second entanglement section and the first entanglement section has no pattern and the other has a pattern. Tensile strength S1 of the nonwoven fabric in a direction in which the first entanglement section is extended and tensile strength S2 of the nonwoven fabric in a direction orthogonal to a direction in which the first entanglement section is extended satisfy S1<S2.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a nonwoven fabric having a striped pattern as a whole and having greater tensile strength in the direction in which the striped pattern is repeated, and a wiper using the same. [Background technology]

[0002] One of the applications of nonwoven fabrics is wipers for wiping off dirt from the human body or objects. A wide variety of wiper configurations have been proposed depending on the purpose of the wiper (the object to be wiped off (whether it is a person or an object) and the type of dirt to be wiped off).

[0003] As one method for improving the wiping performance of a wiper, it has been proposed to make the nonwoven fabric have a three-dimensional pattern and scrape off more dirt by utilizing the unevenness formed by the pattern. For example, Patent Document 1 proposes a nonwoven fabric in which rows of holes, in which openings are continuously connected through, and rows of non-holes are alternately present. In addition, Patent Document 2, in consideration of the insufficient strength characteristics of the nonwoven fabric disclosed in Patent Document 1, proposes a nonwoven fabric having a striped pattern by having a plurality of stripes each having a regular pattern and spaced apart from each other, and the stripe width is 4 mm to 50 mm. In the nonwoven fabrics disclosed in these patent documents, each row constituting the striped pattern extends in the MD direction (machine direction, also called the longitudinal direction) of the nonwoven fabric. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-45161 A [Patent Document 2] JP 2009-287158 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a nonwoven fabric having a stronger tensile strength in a direction orthogonal to the direction in which each column constituting the stripes extends. **Means for Solving the Problems**

[0006] In a first aspect, the present disclosure provides a nonwoven fabric including a first entanglement portion and a second entanglement portion, wherein the first entanglement portion and the second entanglement portion are present in a striped pattern, the second entanglement portion and the first entanglement portion each have a different pattern from each other, or one of the second entanglement portion and the first entanglement portion is patternless and the other has a pattern, and a tensile strength S1 of the nonwoven fabric in the direction in which the first entanglement portion extends and a tensile strength S2 of the nonwoven fabric in a direction orthogonal to the direction in which the first entanglement portion extends satisfy S1 < S2. A nonwoven fabric is provided.

[0007] In a second aspect, the present disclosure includes producing a fiber web, placing the fiber web on a support and subjecting the fiber web to an entanglement treatment with a high-pressure fluid flow, and in the entanglement treatment, assuming that a first section and a second section extending along the CD direction are present in a striped pattern in the fiber web, and performing the entanglement treatment such that treatment conditions when the first section of the fiber web is subjected to the entanglement treatment are different from treatment conditions when the second section of the fiber web is subjected to the entanglement treatment, so that the first entanglement portion, which is the first section after the entanglement treatment, and the second entanglement portion, which is the second section after the entanglement treatment, have different patterns from each other, or one of the first entanglement portion, which is the first section after the entanglement treatment, and the second entanglement portion, which is the second section after the entanglement, is patternless and the other has a pattern. A method for manufacturing a nonwoven fabric is provided. **Advantages of the Invention**

[0008] In the nonwoven fabric of the present disclosure, the tensile strength S1 in the direction in which the first entanglement part and the second entanglement part constituting the stripe pattern extend, and the tensile strength S2 in the direction orthogonal to the said direction, satisfy the relation S1 < S2. Therefore, deformation of the nonwoven fabric hardly occurs in the direction orthogonal to the direction in which the first entanglement part and the second entanglement part extend. When this is used, for example, as a wiper, dirt can be wiped off well due to the stripe pattern.

Brief Description of the Drawings

[0009] [Figure 1] It is a plan view showing an acute angle a formed by the slant line of the slant line pattern and the direction in which the first entanglement part extends when the first entanglement part is a slant line pattern. [Diagram 2] It is a plan view showing the shortest distance D between the centers of adjacent apertures when the second entanglement part is a pattern in which the apertures are arranged in a staggered pattern.

Embodiments for Carrying Out the Invention

[0010] (Circumstances Leading to the Present Embodiment) In both of the nonwoven fabrics disclosed in Patent Documents 1 and 2 above, the stripe pattern, that is, the rows or pattern parts constituting the stripe pattern, mainly extend in the MD direction of the nonwoven fabric, and the pattern (that is, the uneven pattern) changes along the CD direction. In these nonwoven fabrics, since the fibers are oriented in the MD direction, the strength in the MD direction is large, and it is easy to break and deform in the CD direction (also referred to as the lateral direction). That is, when these nonwoven fabrics are used, for example, for wiping, if the nonwoven fabric is placed on a dirty object and the nonwoven fabric is moved in a direction parallel to the CD direction to rub the object, there is a tendency for the nonwoven fabric to break without wiping off the dirt on the object. Therefore, even when these nonwoven fabrics are moved in the CD direction and an attempt is made to wipe off dirt by utilizing the change in the pattern in the CD direction, the nonwoven fabric may sag and the wiping performance by the stripe may not be exhibited.

[0011] Therefore, the inventors considered that the above problems could be solved by configuring each column constituting the striped pattern to extend in a direction (e.g., the CD direction) orthogonal to the direction (e.g., the MD direction) in which the nonwoven fabric has a greater mechanical strength, and studied to realize this configuration. Then, regarding the nonwoven fabric having such a configuration, it was assumed that a first section and a second section extending along the CD direction exist in a striped pattern in the fiber web, and it was found that the nonwoven fabric could be obtained by performing the entanglement treatment with different treatment conditions when the first section of the fiber web is subjected to the entanglement treatment and when the second section of the fiber web is subjected to the entanglement treatment, and thus the present embodiment was reached.

[0012] (Embodiment 1: Nonwoven Fabric) The nonwoven fabric described as Embodiment 1 is a nonwoven fabric including a first entanglement portion and a second entanglement portion, the first entanglement portion and the second entanglement portion exist in a striped pattern, the second entanglement portion and the first entanglement portion each have different patterns from each other, or either one of the second entanglement portion and the first entanglement portion is patternless and the other has a pattern, the tensile strength S1 of the nonwoven fabric in the direction in which the first entanglement portion extends and the tensile strength S2 of the nonwoven fabric in the direction orthogonal to the direction in which the first entanglement portion extends satisfy S1 < S2, is a nonwoven fabric.

[0013] [First Entanglement Portion and Second Entanglement Portion] The first entanglement portion and the second entanglement portion included in the nonwoven fabric of the present embodiment exist in a striped pattern and have different patterns from each other, or either one of the second entanglement portion and the first entanglement portion is patternless and the other has a pattern. Here, "no pattern" means something that gives no sense of design, and although it may have, for example, uneven texture that inevitably occurs during web formation or nozzle streaks that inevitably occur during hydroentanglement treatment, no intentional pattern is imparted. More specifically, if there are protrusions, recesses, or openings, etc., whose longest dimension (excluding the dimension in that direction when they extend continuously in one direction like nozzle streaks) is 0.1 mm or less, such protrusions, recesses, or openings are not considered to form a pattern.

[0014] The term "existing in stripes" means that these entangled parts are repeatedly present with a certain regularity as linear parts extending in a certain direction. For example, when the nonwoven fabric of the present embodiment has only the first entangled parts and the second entangled parts, the first entangled parts and the second entangled parts are alternately and repeatedly present. When the nonwoven fabric of the present embodiment has a third entangled part in addition to the first entangled parts and the second entangled parts, these entangled parts may be present with a regularity such as 1-2-1-3, 1-2-3, or 2-1-3.

[0015] The patterns of the first and second intertwined parts are not particularly limited, as long as they are different from each other, or one of the first and second intertwined parts has no pattern and the other has a pattern. The pattern may be formed by regularly arranging a region with a lower fiber density ("low density region") and a region with a higher fiber density ("high density region"). In this case, the low density region may be at least one pattern selected from the group consisting of a regular pattern, such as a dot pattern, a herringbone pattern, a checkered pattern, a lattice pattern, a houndstooth pattern, a diagonal line pattern, a wave pattern, and a zigzag pattern.

[0016] The low-density region may have a smaller thickness than the high-density region and may be a concave portion that is recessed from the high-density region, or may be a pore where no fibers are present. In one entanglement portion, a concave portion and pores may be mixed as the low-density region. In particular, when forming pores, depending on the manufacturing conditions, it may not be possible to make all the low-density regions into pores, and some low-density regions may exist as concave portions. Such a form is also acceptable in the present embodiment.

[0017] In the present embodiment, it is preferable that the pattern of the first entanglement portion is a diagonal stripe pattern. The diagonal stripe pattern is a pattern in which low-density regions and high-density regions extending in an oblique direction are alternately arranged, and the "oblique direction" in the present embodiment refers to a direction that is not parallel to the MD direction and the CD direction of the nonwoven fabric. The entanglement portion having the diagonal stripe pattern tends to improve the wiping property when the nonwoven fabric is used as a wiper.

[0018] When the first entanglement portion has a diagonal stripe pattern, the acute angle a (see FIG. 1) formed by the diagonal line of the diagonal stripe pattern and the direction in which the first entanglement portion extends may be 10 degrees or more and 80 degrees or less, particularly 15 degrees or more and 75 degrees or less, and more particularly 20 degrees or more and 70 degrees or less. When the acute angle a is too small, the direction of the diagonal line approaches the direction in which the first entanglement portion extends, and when the acute angle a is too large, the direction of the diagonal line approaches the direction orthogonal to the direction in which the first entanglement portion extends. In either case, it becomes difficult to obtain the improvement effect such as wiping property. Here, the direction in which the first entanglement portion extends is a direction that satisfies S1 < S2 when the tensile strength of the nonwoven fabric in that direction is S1 and the tensile strength of the nonwoven fabric in the direction orthogonal to that direction is S2, and generally is the CD direction of the nonwoven fabric. Also, the direction in which the first entanglement portion extends is also the direction in which the second entanglement portion extends.

[0019] The second intertwined portion may be a pattern in which the apertures are regularly arranged. The pattern in which the apertures are regularly arranged may be, for example, a pattern in which the apertures are arranged in a staggered pattern, a pattern in which the apertures are arranged in a square pattern, etc. In the pattern in which the apertures are regularly arranged, the shortest distance between the centers of adjacent apertures may be, for example, 1.0 mm or more and 4.0 mm or less, particularly 1.3 mm or more and 3.0 mm or less, more particularly 1.6 mm or more and 2.5 mm or less. Here, the shortest distance between the centers of adjacent apertures refers to the shortest line segment connecting the centers of adjacent apertures in all combinations. For example, when the apertures are formed in a staggered pattern as shown in FIG. 2, the shortest distance between the centers of adjacent apertures is the distance indicated by the symbol D.

[0020] When the second intertwined portion has a pattern formed by regularly arranging apertures, the area of ​​one aperture is, for example, 0.50 mm 2 It may be equal to or less than 0.45 mm, in particular 2 Below, more specifically 0.40 mm 2 The lower limit of the area of ​​the opening may be, for example, 0.01 mm 2 In particular, 0.02 mm 2 , more particularly 0.03 mm 2 If the area of ​​the openings is too large, the strength of the nonwoven fabric may decrease, and when used as a wiper, the wiped dirt may adhere to the hand or tool through the openings, or the wiped dirt may be easily detached from the openings. If the area of ​​the openings is too small, it is difficult to say that a pattern is formed, and the pattern may not provide an effect of improving wiping properties.

[0021] In addition, when the second intertwined portion is a pattern formed by a regular arrangement of openings, the ratio of the openings to the second intertwined portion may be, for example, 1% to 30%, particularly 3% to 20%, and more particularly 5% to 10%. If the ratio of the openings to one intertwined portion is too small, the effect of improving wiping properties due to the formation of openings may not be obtained. If the ratio of the openings to one intertwined portion is too large, the strength of the nonwoven fabric may decrease, and when used as a wiper, the wiped dirt may adhere to hands or tools through the openings, or the wiped dirt may be easily detached from the openings.

[0022] When either the first intertwined portion or the second intertwined portion has no pattern, the other intertwined portion may have a diagonal line pattern or a pattern formed by a regular arrangement of apertures. In particular, when the other intertwined portion has a diagonal line pattern, the difference in thickness between the first intertwined portion and the non-patterned portion becomes large, and when used as a wiper, the scraping ability tends to improve.

[0023] As described above, in the nonwoven fabric of this embodiment, the first and second entangled parts are present in stripes and are present in a pattern repeated in a certain direction to form a pattern. When the nonwoven fabric has only the first and second entangled parts, a striped pattern is formed in which the first and second entangled parts alternate in a direction perpendicular to the direction in which the first and second entangled parts extend. When the first and second entangled parts extend parallel to, for example, the CD direction of the nonwoven fabric, the striped pattern appears in the MD direction, and when the CD direction is defined as "horizontal" and the MD direction is defined as "vertical", a horizontal striped pattern is formed in which two types of linear parts extending in the horizontal direction are alternately arranged in the vertical direction.

[0024] The first intertwined portion may have a dimension of, for example, 2 mm to 200 mm in a direction perpendicular to the direction in which the first intertwined portion extends, particularly 3 mm to 100 mm, more particularly 5 mm to 50 mm, even more particularly 7 mm to 30 mm, and even more particularly 10 mm to 25 mm. The second intertwined portion may also have a dimension of, for example, 2 mm to 200 mm in a direction perpendicular to the direction in which the first intertwined portion extends, particularly 3 mm to 100 mm, more particularly 5 mm to 50 mm, even more particularly 7 mm to 30 mm, and even more particularly 10 mm to 25 mm. The dimension of the first intertwined portion in a direction perpendicular to the direction in which the first intertwined portion extends (hereinafter referred to as "width" for convenience) and the width of the second intertwined portion may be the same or different. Furthermore, in one nonwoven fabric, there may be a plurality of first entangled portions having different widths, and / or there may be a plurality of second entangled portions having different widths.

[0025] If the width of the first entangled parts is too small, the design effect of the striped pattern may not be fully achieved, and when the nonwoven fabric is used as a wiper, the wiping performance may be insufficient. The same applies when the width of the second entangled parts is too small. If the width of the first entangled parts is too large, the design effect may not be fully achieved, and the wiping performance may be insufficient. The same applies when the width of the second entangled parts is too large.

[0026] As described above, for the nonwoven fabric of the present embodiment, the tensile strength S1 of the nonwoven fabric in the direction in which the first entanglement portion extends and the tensile strength S2 of the nonwoven fabric in the direction orthogonal to the direction in which the first entanglement portion extends satisfy S1 < S2. Generally, a nonwoven fabric has a greater tensile strength in the MD direction (the direction in which the distance of the produced nonwoven fabric extends during the production of the nonwoven fabric) and a smaller tensile strength in the CD direction (the direction orthogonal to the MD direction and given a given dimension during nonwoven fabric production). Therefore, in the present embodiment, the direction in which the first entanglement portion and the second entanglement portion extend is generally the CD direction of the nonwoven fabric. The tensile strength S1 (N / 5 cm) and the tensile strength S2 (N / 5 cm) may particularly satisfy S1 + 10 < S2, more particularly S1 + 20 < S2, and even more particularly S1 + 30 < S2. Alternatively, the relationship between the tensile strength S1 (N / 5 cm) and the tensile strength S2 (N / 5 cm) may be represented by the ratio of S2 to S1 (S2 / S1). In this case, the value of S2 / S1 may particularly be 2.0 or more and 20 or less, more particularly 3.0 or more and 15 or less, and even more particularly 4.0 or more and 8.0 or less.

[0027] [Fibers constituting the nonwoven fabric] The fibers constituting the nonwoven fabric of the present embodiment are not particularly limited, and those used in nonwoven fabric production may be arbitrarily adopted. The nonwoven fabric of the present embodiment is, for example, Synthetic fibers made of one or more thermoplastic resins selected from polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and their copolymers, polyamide resins such as nylon 6, nylon 66, and their copolymers, polyolefin resins such as polymethylpentene, polypropylene, and polyethylene (including high-density polyethylene, low-density polyethylene, and linear low-density polyethylene), acrylic resins, engineering plastics such as polycarbonate, polyacetal, polystyrene, and cyclic polyolefin, and their elastomers, natural fibers such as cotton, silk, wool, hemp, and pulp, and Regenerated fibers such as rayon and polynosic obtained by the viscose process, cupra obtained by the cuprammonium process, and cellulosic fibers (such as Lyocell and Tencel (registered trademark)) obtained by the solvent spinning process (including those whose surfaces have been treated with a hydrophobizing agent); Cellulosic fibers obtained by melt spinning, as well as Acetate and other semi-synthetic fibers The fiber may be formed of one or more fibers selected from:

[0028] The synthetic fibers may be either monofilaments or bicomponent fibers. The bicomponent fibers may be, for example, concentric or eccentric sheath-core bicomponent fibers, islands-in-the-sea bicomponent fibers, side-by-side bicomponent fibers, or splittable bicomponent fibers.

[0029] The synthetic fibers may also be ones that melt or soften by heating or the like to exhibit adhesive properties. For example, the synthetic fibers may be single fibers or composite fibers that contain a resin with a relatively low melting point, such as polyethylene, as one component, with the low melting point resin component occupying at least a part of the fiber surface. Such fibers are, for example, sheath-core composite fibers made of a combination of polyethylene / polypropylene or polyethylene / polyethylene terephthalate, with polyethylene as the sheath component, or splittable composite fibers made of a combination of these thermoplastic resins.

[0030] In the case of core-sheath type composite fibers, the volume ratio of the core component to the sheath component (core component:sheath component) is preferably 80:20 to 20:80, more preferably 70:30 to 30:70, and even more preferably 60:40 to 40:60.

[0031] In the case of splittable conjugate fibers, the ratio of the two components (first:second) is preferably 80:20 to 20:80 by volume, more preferably 70:30 to 30:70, and even more preferably 60:40 to 40:60. In the case of splittable conjugate fibers, the number of divisions (i.e., the number of sections in the conjugate fiber) may be, for example, 4 or more and 32 or less, particularly 4 or more and 20 or less, and more particularly 6 or more and 10 or less.

[0032] When synthetic fibers capable of bonding fibers together are used, the synthetic fibers may be contained in an amount of, for example, 5% by mass or more, particularly 10% by mass or more, more particularly 15% by mass or more, when the mass of the entire nonwoven fabric is taken as 100% by mass. The upper limit of the proportion of adhesive synthetic fibers is, for example, 35% by mass, particularly 30% by mass, more particularly 25% by mass. If the proportion of adhesive synthetic fibers is too low, the effects of bonding fibers together (for example, improving the mechanical strength of the nonwoven fabric, suppressing fluffing, and maintaining the applied pattern) may not be fully obtained. If the proportion of adhesive synthetic fibers is too high, the texture of the nonwoven fabric becomes hard and the drapeability decreases, which may affect wiping properties when used as a wiper.

[0033] The nonwoven fabric of this embodiment may contain, for example, 30% by mass or more, particularly 50% by mass or more, and more particularly 80% by mass or more of cellulosic fibers. Here, examples of cellulosic fibers include natural fibers derived from plants such as cotton, linen, ramie, jute, hemp, and pulp; regenerated fibers such as rayon and polynosic obtained by the viscose method, cupra obtained by the cuprammonium method, and cellulosic fibers obtained by the solvent spinning method (such as Lenzing Lyocell (registered trademark) and Tencel (registered trademark)), cellulosic fibers obtained by the melt spinning method, and semi-synthetic fibers such as acetate fibers. Cellulosic fibers, particularly when producing a nonwoven fabric by entanglement treatment using a high-pressure fluid flow, tend to be entangled with each other, and provide a nonwoven fabric in which the entangled state is well maintained even after the entanglement treatment, making it easy to form a clear pattern on the nonwoven fabric. In addition, the good entanglement of the fibers suppresses fluffing of the nonwoven fabric.

[0034] The fiber fineness is not limited as long as a pattern is formed in both or either of the first and second entangled parts, and is selected according to the use of the nonwoven fabric. The fiber fineness may be, for example, 0.3 dtex to 10 dtex, particularly 0.5 dtex to 5.0 dtex, more particularly 0.7 dtex to 4.0 dtex, even more particularly 1.0 dtex to 3.0 dtex, and even more particularly 1.3 dtex to 2.5 dtex. When the fibers constituting the nonwoven fabric are natural fibers such as cotton, it may be difficult to use fibers in a specific fineness range, and in that case, fibers of various finenesses may be included. If the fiber fineness is too small, when the nonwoven fabric is produced by entanglement treatment using a high-pressure fluid flow, the fibers may be entangled with the support, or the support may be clogged with the fibers. If the fiber fineness is too large, the pattern may become unclear.

[0035] The fiber length of the fibers is not limited as long as a pattern is formed in both or either of the first and second intertwined parts, and is selected according to the manufacturing conditions of the nonwoven fabric. The fiber length of the fibers is, for example, 10 mm or more and 100 mm or less. If the fiber length is outside this range, it may be difficult to produce a fiber web using, for example, a carding machine. In addition, in a nonwoven fabric with a low basis weight, if the fiber length exceeds 100 mm, the number of fibers constituting the nonwoven fabric is reduced, so that the texture of the nonwoven fabric may not be stable, or the required strength of the nonwoven fabric may not be obtained. In addition, if the fiber length is too small, the strength of the nonwoven fabric may decrease, and if the fiber length is too large, the pattern may not be clear. The fiber length is more preferably 25 mm or more and 90 mm or less, even more preferably 32 mm or more and 70 mm or less, and particularly preferably 38 mm or more and 65 mm or less. Alternatively, where the nonwoven fabric is produced by a process that includes producing a fibrous web by air-laying or wet-laid processes, the fiber length may be, for example, from 2 mm to 20 mm.

[0036] [Nonwoven fabric form] The nonwoven fabric may have a single layer structure or a laminate structure. The nonwoven fabric may be formed from a web selected from a card web such as a parallel web, a cross web, a semi-random web, and a random web, an air-laid web, a wet-laid paper web, a melt-blown web, and a spunbond web. When the cellulosic fibers are used as all or part of the constituent fibers, a web selected from a card web, an air-laid web, and a wet-laid paper web may be produced. When a nonwoven fabric is produced using these fiber webs containing cellulosic fibers, particularly by an entanglement treatment using a high-pressure fluid flow, the fibers are easily entangled with each other, and the entangled state is well maintained even after the entanglement treatment, resulting in a nonwoven fabric. This makes it easy to form a clear pattern on the nonwoven fabric, and the fibers are well entangled with each other, thereby suppressing fluffing of the nonwoven fabric.

[0037] Furthermore, by forming the nonwoven fabric into a laminated structure including an air-laid web, a wet-laid paper web, a melt-blown web, or a spunbond web, the mechanical strength of the nonwoven fabric can be improved.

[0038] [Physical properties of nonwoven fabric] The physical properties of the nonwoven fabric of this embodiment will be described below by way of example. It should be noted that the nonwoven fabric of this embodiment is not limited to those having the following physical properties because the physical properties of the nonwoven fabric vary depending on the fibers constituting the nonwoven fabric, the basis weight of the nonwoven fabric, and the manufacturing conditions of the nonwoven fabric.

[0039] The thickness of the nonwoven fabric of this embodiment (under a load of 294 Pa) may be, for example, 0.50 mm or more and 1.0 mm or less, particularly 0.55 mm or more and 0.90 mm or less, and more particularly 0.60 mm or more and 0.80 mm or less.

[0040] The nonwoven fabric of this embodiment has a striped pattern formed by first and second entangled parts, one of which has a different pattern, or one of which has no pattern and the other has a pattern. When the thickness change of this nonwoven fabric is observed by aligning the line of sight perpendicular to the MD and CD directions, the thickness change in one direction is significantly larger than that in the other direction. The thickness change can be determined by measuring the thickness using a microscope under a load of 40 Pa. Specifically, the thickness measurement using a microscope is performed as follows.

[0041] <How to measure thickness using a microscope> The nonwoven fabric is cut with a sharp blade so as to obtain a rectangular sample with each side parallel to the MD and CD directions. The cut nonwoven fabric is placed on a smooth table, a load of 40 Pa is applied, and a microscope is placed directly beside the cut surface obtained by cutting in a direction perpendicular to the MD direction, and the distance in the thickness direction (thickness) is measured in the part where the fibers exist. Measurements are performed at six points, and the average value is taken as the average thickness in the MD direction. Similarly, a microscope is placed directly beside the cut surface obtained by cutting in a direction perpendicular to the CD direction, and the distance in the thickness direction (thickness) is measured in the part where the fibers exist. Measurements are performed at six points, and the average value is taken as the average thickness in the CD direction.

[0042] In the case where two entangled portions are arranged in a striped pattern as in the nonwoven fabric of this embodiment, the cut surface may be a cut surface of only the first entangled portion or only the second entangled portion (a cut surface consisting of either one of the entangled portions) depending on the cutting direction. In that case, the thickness is measured on the cut surface of only one of the entangled portions.

[0043] When the thickness of the nonwoven fabric of this embodiment is determined by the above method, the average thickness in the MD direction may be, for example, 0.50 mm to 1.5 mm, particularly 0.60 mm to 1.0 mm, more particularly 0.65 mm to 0.90 mm. The average thickness in the CD direction may be, for example, 0.50 mm to 1.5 mm, particularly 0.60 mm to 1.0 mm, more particularly 0.65 mm to 0.90 mm.

[0044] In the nonwoven fabric of this embodiment, the coefficient of variation of the thickness in the CD direction of the nonwoven fabric may be 0.09 or more, particularly 0.12 or more, more particularly 0.15 or more. The upper limit of the coefficient of variation of the thickness of the nonwoven fabric in the CD direction may be, for example, 0.30. When only one intertwined part is observed on the cut surface (when the cut surface consists of one intertwined part), the standard deviation σ is calculated from the data obtained by measuring the thickness at six points, and the coefficient of variation is calculated from the following formula. When multiple types of intertwined parts are observed on the cut surface (when the cut surface consists of multiple intertwined parts), the thickness is measured at six points in each intertwined part, the standard deviation is calculated from the measurement data of (6 x types of intertwined parts), and the coefficient of variation is calculated from the following formula. Coefficient of variation of thickness = standard deviation σ / average thickness

[0045] The coefficient of variation of the thickness of the nonwoven fabric indicates the variation in the thickness of the nonwoven fabric in a given direction, and the larger the coefficient of variation, the more firmly the unevenness is formed along that direction. If the coefficient of variation of the thickness of the nonwoven fabric is too small, the unevenness is small, and when used as a wiper, the wiping performance may be poor, whereas if the coefficient of variation is too large, when used as a wiper, the nonwoven fabric may get caught on the unevenness of the object to be wiped, resulting in a poor usability.

[0046] The basis weight of the nonwoven fabric of this embodiment is not particularly limited and may be appropriately selected depending on the application, etc. For example, when the nonwoven fabric of this embodiment is used as a wiper, the basis weight is 30 g / m 2 More than 80g / m 2 or less, in particular 35 g / m 2 ~75g / m 2 and more particularly 40 g / m2 ~70g / m 2 Alternatively, when the nonwoven fabric of the present embodiment is used as a sanitary product, the basis weight may be 20 g / m 2 ~70g / m 2 and in particular 25 g / m 2 ~65g / m 2 and more particularly 30 g / m 2 ~60g / m 2 If the basis weight is too large, the pattern may be formed on only one side, and the effect of the pattern may be manifested on only one side. If the basis weight is too small, the pattern may not be clearly formed, and the effect of the pattern may not be manifested.

[0047] The nonwoven fabric of this embodiment may have a tensile strength of 25N / 5cm to 140N / 5cm, particularly 30N / 5cm to 100N / 5cm, more particularly 35N / 5cm to 80N / 5cm in a direction perpendicular to the direction in which the first intertwined parts extend. The nonwoven fabric may have a tensile strength of 3.0N / 5cm to 25N / 5cm, particularly 3.5N / 5cm to 23N / 5cm, more particularly 4.0N / 5cm to 20N / 5cm, and even more particularly 5.0N / 5cm to 15N / 5cm in a direction parallel to the direction in which the first intertwined parts extend. If the tensile strength in the direction perpendicular to the direction in which the first intertwined parts extend and / or the tensile strength in the direction parallel to the direction in which the first intertwined parts extend is too high, the texture may deteriorate, and if it is too low, the shape stability of the nonwoven fabric may be insufficient.

[0048] The nonwoven fabric of this embodiment may have an extensibility of 20% to 50%, particularly 23% to 47%, more particularly 26% to 43%, in the direction perpendicular to the direction in which the first entangled parts extend, and may have an extensibility of 70% to 140%, particularly 75% to 125%, more particularly 80% to 110%, in the direction parallel to the direction in which the first entangled parts extend. If the extensibility in the direction perpendicular to the direction in which the first entangled parts extend and / or the extensibility in the direction parallel to the direction in which the first entangled parts extend is too high, the nonwoven fabric may be prone to elongation and may have insufficient shape stability, whereas if the extensibility is too low, the nonwoven fabric may not elongate when an external force is applied to it and may immediately break, resulting in insufficient shape stability.

[0049] The nonwoven fabric of the present embodiment may have a stress at 10% elongation of 4.5N / 5cm to 110N / 5cm, particularly 5.5N / 5cm to 100N / 5cm, more particularly 8.0N / 5cm to 50N / 5cm, and even more particularly 12N / 5cm to 25N / 5cm, in a direction perpendicular to the direction in which the first entangled parts extend. The nonwoven fabric may have a stress at 10% elongation of 0.6N / 5cm to 3.0N / 5cm, particularly 0.7N / 5cm to 2.5N / 5cm, and more particularly 0.8N / 5cm to 2.0N / 5cm, in a direction parallel to the direction in which the first entangled parts extend. If the stress at 10% elongation in the direction perpendicular to the extension direction of the first intertwined portions and / or the stress at 10% elongation in the direction parallel to the extension direction of the first intertwined portions is too high, the fiber freedom of the nonwoven fabric will be small, making it difficult for the nonwoven fabric to conform to the shape of an object when it comes into contact with the object, which may result in a small contact area between the object and the nonwoven fabric; if it is too low, the shape stability of the nonwoven fabric will be insufficient.

[0050] The nonwoven fabric of this embodiment may have a stress at 20% elongation of 15N / 5cm to 140N / 5cm, particularly 17N / 5cm to 100N / 5cm, more particularly 20N / 5cm to 80N / 5cm in a direction perpendicular to the direction in which the first entangled parts extend. The nonwoven fabric may have a stress at 20% elongation of 1.0N / 5cm to 3.5N / 5cm, particularly 1.2N / 5cm to 3.0N / 5cm, more particularly 1.4N / 5cm to 2.5N / 5cm in a direction parallel to the direction in which the first entangled parts extend. If the stress at 20% elongation in the direction perpendicular to the direction in which the first intertwined portions extend and / or the stress at 20% elongation in the direction parallel to the direction in which the first intertwined portions extend is too high, the fiber freedom of the nonwoven fabric will be small, making it difficult for the nonwoven fabric to conform to the shape of an object when it comes into contact with the object, which may result in a small contact area between the object and the nonwoven fabric; if it is too low, the shape stability of the nonwoven fabric may be insufficient.

[0051] The nonwoven fabric of this embodiment has a lower water absorbency and tends to be less susceptible to liquid diffusion than a nonwoven fabric having the same pattern formed over the entire surface. Specifically, when the water absorbency of the nonwoven fabric of this embodiment is measured by the Byreck method in accordance with JIS L 1907 7.1.2, the nonwoven fabric of this embodiment may exhibit a water absorbency of, for example, 1 mm to 90 mm in the CD direction and 1 mm to 70 mm in the MD direction. In addition, in the nonwoven fabric of this embodiment, when the water absorbency in the MD direction is A (mm) and the water absorbency in the CD direction is B (mm), the area of ​​the pseudo-diffusion ellipse measured by A×B×π is, for example, 146 cm 2 The following, especially 144cm 2 Below, more specifically 142cm 2 The lower limit of the area of ​​the pseudo-diffusion ellipse is, for example, 0.03 cm 2 , especially 0.3 cm 2 , more specifically 0.8 cm 2 The reason why the nonwoven fabric of the present embodiment exhibits the above-mentioned water absorption properties is believed to be that the progress of water is hindered by the recesses and pores formed in the first entangled parts and the second entangled parts when the nonwoven fabric absorbs water.

[0052] (Embodiment 2: Method for producing the nonwoven fabric of embodiment 1) As embodiment 2, a method for producing the nonwoven fabric of embodiment 1 will be described. The nonwoven fabric of embodiment 1 can be produced, for example, by Producing a fibrous web; placing the fibrous web on a support and subjecting the fibrous web to an entanglement treatment using a high-pressure fluid flow; Including, In the entanglement treatment, it is assumed that the fiber web has a first section and a second section extending in the CD direction in a striped pattern, The entanglement treatment is performed under different treatment conditions when the first section of the fiber web is subjected to the entanglement treatment and when the second section of the fiber web is subjected to the entanglement treatment, so that the first entangled portion, which is the first section after the entanglement treatment, and the second entangled portion, which is the second section after the entanglement treatment, have different patterns, or one of the first entangled portion, which is the first section after the entanglement treatment, and the second entangled portion, which is the second section after the entanglement treatment, has no pattern and the other has a pattern. It can be produced by a production method.

[0053] This manufacturing method corresponds to a method in which a high-pressure fluid flow is sprayed onto a fiber web to entangle the fibers and integrate them. The high-pressure fluid is, for example, a high-pressure gas such as compressed air, or a high-pressure liquid such as high-pressure water. In the manufacture of nonwoven fabrics, a hydroentanglement process using high-pressure water as the high-pressure fluid is often used, and in this embodiment, the hydroentanglement process is preferably used from the viewpoint of ease of implementation. Below, a manufacturing method in which a high-pressure water flow (hereinafter also simply referred to as "water flow") is used as the high-pressure fluid flow will be described.

[0054] In this manufacturing method, when the surface of the fiber web to be subjected to the hydroentanglement treatment is viewed, it is assumed that the first section and the second section extending along the CD direction of the fiber web are present in a striped pattern, and the two sections are subjected to the hydroentanglement treatment under different treatment conditions. The conditions of the hydroentanglement treatment include, for example, the hole size of the orifice, the distance between the orifices, the number of water jets in the MD direction, the water pressure, the water volume, the conveying speed of the fiber web, and the structure of the surface of the support that conveys the fiber web during the hydroentanglement treatment and that comes into contact with the fiber web. The hydroentanglement treatment in the two sections is performed under different treatment conditions by making at least one of these different.

[0055] The conditions for the hydroentanglement treatment of the two sections are selected so that the first entangled portion formed by entangling the first section and the second entangled portion formed by entangling the second section have different patterns, or one of the first entangled portion formed by entangling the first section and the second entangled portion formed by entangling the second section has no pattern and the other has a pattern. The conditions for making the first entangled portion and the second entangled portion have different patterns may be, for example, the structure of the support surface in order to obtain two such entangled portions after the entanglement treatment.

[0056] For example, a single support (hereinafter, for convenience, referred to as a "striped pattern-forming support") on which two types of weaves are regularly and repeatedly formed along the MD direction may be used as the support. By simultaneously spraying water streams on the first and second sections of the fiber web on this support (i.e., by not changing the conditions for spraying the water streams between the two sections), the first and second entangled parts of the nonwoven fabric described as the first embodiment can be formed. The first entangled part is formed by rearranging the fibers so as to have a pattern determined by one of the two types of weaves constituting the striped pattern-forming support (for convenience, referred to as "weave A"), and becomes a linear part extending in the CD direction. Similarly, the second entangled part is formed by rearranging the fibers so as to have a pattern determined by the other of the two types of weaves constituting the striped pattern-forming support (for convenience, referred to as "weave B").

[0057] In the striped pattern forming support, for example, the weave structure A and the weave structure B are arranged in the order ABAB... along the MD direction. Therefore, the first entangled parts and the second entangled parts formed by the weave structures A and B of this support are also formed in the order 1-2-1-2... along the MD direction. Therefore, the nonwoven fabric produced by this method has a striped pattern in which the first entangled parts and the second entangled parts extend along the CD direction.

[0058] The striped pattern forming support may be, for example, woven from filaments having a diameter of 0.5 mm to 1.0 mm, with twill weave portions as weave structure A and plain weave portions as weave structure B alternately formed along the MD direction. With such a support, a first entangled portion having a diagonal line pattern is formed in the twill weave portion, and a second entangled portion having staggered openings is formed in the plain weave portion. In the support, the weave structure A and the weave structure B may be woven using filaments of different thicknesses as weft yarns.

[0059] In the striped pattern forming support, the dimensions of the weaves A and B in the MD direction determine the dimensions of the first and second intertwined parts in the obtained nonwoven fabric (i.e., the dimensions of the first and second intertwined parts in the direction perpendicular to the direction in which the first and second intertwined parts extend). In this embodiment, the dimension of the weave A in the MD direction may be 2 mm or more and 200 mm or less, particularly 3 mm or more and 100 mm or less, more particularly 5 mm or more and 50 mm or less, even more particularly 7 mm or more and 30 mm or less, even more particularly 10 mm or more and 25 mm or less. Similarly, the dimension of the weave B in the MD direction may be 2 mm or more and 200 mm or less, particularly 3 mm or more and 100 mm or less, more particularly 5 mm or more and 50 mm or less, even more particularly 7 mm or more and 30 mm or less, even more particularly 10 mm or more and 25 mm or less. The dimension of the weave A in the MD direction may be the same as or different from the dimension of the weave B in the MD direction. Furthermore, in one support, there may be a plurality of weave structures A having different dimensions in the MD direction, and / or there may be a plurality of weave structures B having different dimensions in the MD direction.

[0060] When the weave structure A is a twill weave, the shape of the diagonal pattern in the first intertwined portion changes depending on the fiber diameter of the monofilament, the warp density, and the weft density, as well as the number of warps floating above the wefts and / or the number of warps sinking below the wefts in the twill weave. A twill weave is constructed such that the warps floating above the wefts are either adjacent or not adjacent, and when the floating warp portions are connected with straight lines, if a straight line extending diagonally including all the floating portions can be drawn, a first intertwined portion with a diagonal pattern is obtained. If such a straight line cannot be drawn, a first intertwined portion with a mottled pattern is obtained.

[0061] When the weave structure B is a plain weave portion, the size of the openings formed in the second intertwined portion changes depending on the fiber diameter of the monofilaments that make up the structure, and the area of ​​the openings tends to increase as the fiber diameter of the monofilaments increases. Also, the spacing between the openings changes depending on the weft density and warp density of the plain weave portion, and the spacing between the openings tends to decrease as the weft density and / or warp density increases.

[0062] In the striped pattern forming support, both weaves A and B may be plain weaves. In this case, the two weaves can be different from each other by changing the thickness of the weft yarn and / or the density of the weft yarn. Also, both weaves A and B may be twill weaves. In this case, the two weaves can be different from each other by using one of the methods selected from changing the number of warp yarns that float above the weft yarn, changing the number of warp yarns that sink below the weft yarn, changing the thickness of the weft yarn, etc.

[0063] When the weave structure B is a plain weave part with a fine mesh (for example, 80 mesh or more and 100 mesh or less), a second intertwined part without a pattern is formed corresponding to the weave structure. In this case, the weave structure A may be a structure capable of forming a pattern, for example, a twill weave part, or a plain weave part made of thick filaments.

[0064] Alternatively, the conditions of the hydroentanglement treatment can be made different between the two sections by disposing a plate (hereinafter, "intervening plate") between the fiber web and the nozzle, which is processed into a shape such that the water flow does not hit the fiber web in a portion corresponding to one of the sections, and moving the plate in accordance with the traveling speed of the fiber web. Such an intervening plate may be a ladder-shaped plate with rectangular openings provided at regular intervals in the MD direction (traveling direction of the fiber web). In the portion where the water flow is prevented from being sprayed by the intervening plate, entanglement does not progress in the fiber web, resulting in a patternless state, while in the portion located at the opening of the intervening plate where the water flow is sprayed, entanglement progresses in the fiber web and a pattern corresponding to the weave structure of the support is formed. Therefore, by using such an intervening plate, a nonwoven fabric can be obtained in which one entangled portion is patternless and the other has a pattern.

[0065] Alternatively, the conditions of the hydroentanglement treatment can be made different between the two sections by using two types of supports and the above-mentioned intervening plate. Specifically, first, a fiber web is placed on one support, and the above-mentioned ladder-shaped intervening plate is placed between the web and the nozzle, and a water stream is sprayed onto the fiber web to form a pattern, for example, only in the first section. Then, the fiber web with the pattern formed in the first section is placed on another support, and the intervening plate is placed so that the opening of the intervening plate is located in the second section, and a water stream is sprayed onto the fiber web to form a pattern corresponding to the weave of the other support in the second section. This method can also form a first intervening portion and a second intervening portion having different patterns.

[0066] In this embodiment, the fiber web may be subjected to a treatment for entangling the constituent fibers overall (overall entangling treatment), and then to a hydroentangling treatment in which the hydroentangling treatment conditions are different between the two sections. The overall entangling treatment may be performed under the same treatment conditions over the entire fiber web. The overall entangling treatment may also be performed so that the fiber web after the entangling treatment has no pattern, i.e., is patternless. By entangling the fibers to a certain degree in advance by the overall entangling treatment, it becomes easier to create a pattern in the subsequent entangling treatment.

[0067] The total entanglement treatment is carried out by placing the fiber web on a support and spraying a columnar water stream onto the support. For example, the support is preferably a plain weave support of 80 mesh or more and 100 mesh or less. With such a support, it is possible to entangle the fibers of the fiber web without forming a pattern on the fiber web and with good texture.

[0068] The fiber web can be produced by a known method. The form of the fiber web may be any one selected from, for example, a parallel web, a cross web, a card web such as a semi-random web or a random web, an air-laid web, and a wet-laid paper web. In this embodiment, a card web is preferably used because it is easy to obtain a thickness and to form unevenness.

[0069] The total entanglement treatment may be carried out by spraying water at a pressure of 1 MPa to 15 MPa from nozzles having orifices with a hole diameter of 0.05 mm to 0.5 mm spaced at intervals of 0.3 mm to 1.5 mm onto the front and back surfaces of the fiber web 1 to 5 times. The water pressure is preferably 1 MPa to 10 MPa, more preferably 1 MPa to 7 MPa.

[0070] The entanglement treatment for the first and second sections (hereinafter, "section entanglement treatment") may be performed by spraying a water stream with a water pressure of 1 MPa or more and 15 MPa or less from a nozzle having orifices with a hole diameter of 0.05 mm or more and 0.5 mm or less arranged at intervals of 0.3 mm or more and 1.5 mm or less onto the front and back surfaces of the fiber web 1 to 5 times. The water pressure is preferably 1 MPa or more and 10 MPa or less, and more preferably 1 MPa or more and 7 MPa or less. In this embodiment, when the entire entanglement treatment is not performed and only the section entanglement treatment is performed, the water pressure may be set higher than when the entire entanglement treatment is performed so that the desired entangled state is achieved. In this embodiment, when the section entanglement treatment is performed twice using two types of supports, the water pressure of the water stream sprayed onto each section may be within the above range.

[0071] The first and second entangled portions are formed by subjecting the first and second sections to a hydroentanglement treatment, and then the fiber web is subjected to a drying treatment, thereby obtaining the nonwoven fabric of the first embodiment.

[0072] When the fiber web contains adhesive fibers, a bonding treatment may be performed simultaneously with or after the drying treatment so that the fibers are bonded together in the resulting nonwoven fabric. The bonding treatment may be a thermal bonding treatment, or bonding by electron beam irradiation or ultrasonic welding. By the heat treatment, the adhesive fibers (e.g., the low melting point component of the composite fiber) melt or soften by heating during the heat treatment, and the fibers constituting the fiber web can be bonded together. By the heat treatment, the drying treatment can be performed simultaneously.

[0073] The heat treatment may be, for example, a hot air processing treatment in which hot air is blown, a heat roll processing (heat embossing roll processing), or a heat treatment using infrared rays. The hot air processing treatment may be carried out using a device that blows hot air at a predetermined temperature onto the fiber web, for example, a hot air penetration type heat treatment machine or a hot air blowing type heat treatment machine.

[0074] The heat treatment temperature (for example, the temperature of the hot air) may be a temperature at which a component constituting the adhesive fiber and functioning as an adhesive component softens or melts. For example, the heat treatment temperature may be a temperature equal to or higher than the melting point of the component. For example, when the adhesive fiber contains polyethylene as a component and polyethylene is used as an adhesive component, the heat treatment temperature may be 130°C to 150°C.

[0075] In the above, a striped pattern forming support in which two different weaves are regularly and repeatedly formed in the MD direction is exemplified. In a modified example of this embodiment, a support in which three or more different weaves (e.g., weaves A, B, and C) are repeatedly formed in the MD direction, for example, in the order of ABC- or ABAC-, may be used. When this support is used, a nonwoven fabric in which a third entangled portion is formed corresponding to the weave C is obtained. In addition, in order to form three types of entangled portions, for example, three types of supports may be used, and the intermediate plate may be shaped so that the water flow is sprayed only on the portion corresponding to one of the three sections, and the hydroentanglement treatment may be performed by the method described above.

[0076] (Embodiment 3: Uses of the nonwoven fabric of embodiment 1) As the third embodiment, a product using the nonwoven fabric of the first embodiment will be described. The nonwoven fabric of the first embodiment may be used as a wiper alone or together with other nonwoven fabrics or sheets. The nonwoven fabric of the first embodiment has a tensile strength S1 in the direction in which each linear portion constituting the striped pattern extends, which is smaller than the tensile strength S2 in the direction perpendicular to the direction in which each linear portion constituting the striped pattern extends. Therefore, even if this nonwoven fabric is placed on an object having dirt and is rubbed by reciprocating in the direction perpendicular to the direction in which the first and second intertwined portions corresponding to each linear portion extend, the nonwoven fabric is unlikely to twist, and the dirt on the object can be effectively wiped off by the striped pattern.

[0077] When the rate of gradation change upon wiping of the nonwoven fabric of embodiment 1 is measured by the following method, the rate of gradation change upon wiping in the direction in which the first intertwined portions extend (T1) and the rate of gradation change upon wiping in the direction perpendicular to the direction in which the first intertwined portions extend (T2) may satisfy T2 / T1>1.0. (Method for measuring the rate of change in gradation when wiping) A transparent acrylic plate (thickness 3 mm, product number: KAC9143-1S, manufactured by Hikari Corporation) with a mark (a square frame with sides of 1.5 cm drawn with a pen) is placed on the opposite side of the mark with three drops (0.05 ml per drop) of a pseudo-soil (a mixture of blue acrylic paint (product name: acrylic paint (blue), manufactured by Daiso Industries Co., Ltd.), ethanol (product name: Wako First-class Ethanol (99.5), manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) and distilled water (blue acrylic paint: ethanol: distilled water = 10:50:40 (mass ratio))) and spread evenly over an area larger than the area of ​​the mark, and air-dried for 60 minutes. The grayscale gradation A within the mark (excluding the area of ​​the square frame drawn with a pen) after air-drying is measured. An image analysis processing software (software name: Image J) is used for gradation measurement. Another acrylic plate is placed on the side with the artificial stain to protect the stain, and image data is captured with a scanner (product name: Docu Centre VIIC4473, manufactured by Fuji Xerox Co., Ltd.). The captured image data is split into RGB channels (Split Channels), and the average value of the gradation within the mark for only the red component is confirmed with a histogram (Histogram). This is defined as grayscale gradation A.

[0078] The pseudo-soil applied to the acrylic plate is attached to a nonwoven fabric sample of 10 cm in the MD direction and 6 cm in the CD direction (100 parts by mass of nonwoven fabric is impregnated with 300 parts by mass of distilled water) and is attached to a plate-shaped jig (wiping area 6 cm x 6 cm). While applying a pressure of 510 Pa, the fabric is moved back and forth twice in a specified direction at a speed of 10 mm / sec and a moving distance of 100 mm. The grayscale gradation B of the pseudo-soil remaining on the acrylic plate after wiping is obtained in the same manner as gradation A, and the gradation change rate T (%) is calculated according to the following formula.

number

[0079] T1 and T2 may particularly satisfy T2 / T1≧1.05, more particularly T2 / T1≧1.10. The upper limit of T2 / T1 may be, for example, 3.0, particularly 2.5, and more particularly 2.0.

[0080] Satisfying T2 / T1>1.0 means that the wiping ability is higher when the wiping direction is perpendicular to the extension direction of the first entangled parts than when the wiping direction is the extension direction of the first entangled parts. Therefore, when the extension direction of the first entangled parts is the CD direction of the nonwoven fabric, the wiping ability is higher when the wiping direction is the MD direction than when the wiping direction is the CD direction. Such wiping ability has not been obtained with conventional striped nonwoven fabrics in which each linear part extends in the MD direction.

[0081] When the nonwoven fabric of embodiment 1 satisfies T2 / T1>1.0 and is used as a wiper, the user can easily recognize the wiping direction that provides a higher wiping effect. That is, if the relationship between the striped pattern and the preferred moving direction of the wiper is indicated on the package or the like, coupled with the fact that the wiper itself has a clear striped pattern, the user can wipe in the correct direction without making a mistake in the moving direction of the wiper.

[0082] Alternatively, the nonwoven fabric of this embodiment may be used in sanitary products such as sanitary napkins, baby diapers, and adult diapers. As described above, the nonwoven fabric of this embodiment has unique water absorption properties, and absorbed liquid is less likely to spread in the nonwoven fabric of this embodiment. Therefore, the nonwoven fabric of this embodiment may be used as a member, particularly a surface material, in sanitary products where suppression of the spread of blood or excrement is required. Alternatively, the nonwoven fabric of this embodiment may be used in hand towels, face masks, sanitary masks, filters, poultices, and the like. EXAMPLES

[0083] The present embodiment will now be described with reference to examples. The following fibers were prepared for use in the examples and comparative examples. Rayon (cellulosic fiber): Viscose rayon fiber with a fineness of 1.7 dtex and fiber length of 40 mm (Corona CD (product name) manufactured by Daiwabo Rayon Co., Ltd.). PET: A single fiber made of polyethylene terephthalate with a fineness of 1.45 dtex and a fiber length of 38 mm (product name: Tetoron T403, manufactured by Toray Industries, Inc.). PP / PE: A concentric core-sheath composite fiber (NBF(H) (product name) manufactured by Daiwa Boseki Co., Ltd.) with a core of polypropylene and a sheath of high-density polyethylene (melting point: approximately 133°C) and a composite ratio (core:sheath) of 37:63 (volume ratio), a fineness of 1.7 dtex, and a fiber length of 51 mm.

[0084] In producing the nonwoven fabrics of the Examples and Comparative Examples, the supports used in the second hydroentanglement treatment are shown below. Support 1: Warp thread diameter 0.81 mm and 0.41 mm (two types of filaments arranged alternately), weft thread diameter 0.72 mm, warp thread density 25 threads / inch, weft thread density 17 threads / inch, plain weave fabric Support 2: Warp thread diameter 0.7 mm, weft thread diameter 0.9 mm, warp thread density 41 threads / inch, weft density 16 threads / inch, 3 / 1 herringbone weave Support 3: A fabric having warp thread diameters of 0.88 mm and 0.57 mm (two types of filaments arranged alternately), weft thread diameters of 0.45 mm (plain weave portion) and 0.9 mm (twill weave portion), warp thread density of 30 threads / inch, weft thread density of 17 threads / inch, plain weave and 2 / 2 twill weave alternately in the MD direction, the dimension of one plain weave portion in the MD direction being 24 mm, and the dimension of one 2 / 2 twill portion in the MD direction being 11 mm. Support 4: A fabric having warp thread diameters of 0.88 mm and 0.57 mm (two types of filaments arranged alternately), weft thread diameters of 0.45 mm (plain weave portion) and 0.8 mm (twill weave portion), warp thread density of 30 threads / inch, weft thread density of 25 threads / inch, plain weave and 1 / 7 twill weave alternately in the MD direction, the dimension of one plain weave portion in the MD direction being 24 mm, and the dimension of one 1 / 7 twill portion in the MD direction being 11 mm.

[0085] (Test 1) <Production of Nonwoven Fabric 1-A: Comparative Example> A fiber web was produced by mixing 80% by mass of rayon and 20% by mass of PP / PE using a parallel carding machine. The basis weight of this fiber web was about 40 g / m 2 It was. [First water flow entanglement treatment (total entanglement treatment)] The above-mentioned fiber web was placed on a plain weave net with a warp thread diameter of 0.132 mm, a weft thread diameter of 0.132 mm, and a mesh count of 90 meshes. While the fiber web was moving at a speed of 4 m / min, a columnar water stream with a water pressure of 1.0 MPa was sprayed onto the front surface of the fiber web, and then a columnar water stream with a water pressure of 1.5 MPa was sprayed onto the back surface of the fiber web. A nozzle with orifices with a hole diameter of 0.12 mm spaced 0.6 mm apart was used to spray the water stream. The distance between the surface of the fiber web and the orifice was 15 mm.

[0086] [Second water flow entanglement treatment] The fiber web after the first hydroentanglement treatment was placed on a support 1, and while the fiber web was moving at a speed of 4 m / min, a columnar water stream was sprayed onto the back surface of the fiber web at a water pressure of 1.5 MPa. The same nozzle as that used in the first hydroentanglement treatment was used to spray the water stream. The second hydroentanglement treatment formed a pattern in which the openings were regularly arranged in a staggered pattern over the entire nonwoven fabric. The area per opening was 0.4 mm. 2 The shortest distance between the centers of adjacent apertures was 1.8 mm, and the proportion of the apertures on the surface of the nonwoven fabric was 13%.

[0087] [Heat treatment] The nonwoven fabric after the second hydroentanglement treatment was heated at 135°C for approximately 5 seconds using a hot air penetration type heat treatment machine to carry out a drying treatment, and at the same time, the fibers were thermally bonded together by the PP / PE sheath component to obtain nonwoven fabric 1-A.

[0088] <Production of Nonwoven Fabric 1-B: Comparative Example> Nonwoven fabric 1-B was obtained in the same manner as in the production of nonwoven fabric 1-A, except that support 2 was used in the second hydroentanglement treatment. Nonwoven fabric 1-B had a herringbone pattern formed over the entire surface.

[0089] <Production of Nonwoven Fabric 1-C: Example> Nonwoven fabric 1-C was obtained using the same procedure as that employed in the production of nonwoven fabric 1-A, except that support 3 was used in the second hydroentanglement treatment and the second hydroentanglement treatment was carried out as a section entanglement treatment. In nonwoven fabric 1-C, a diagonal line pattern portion as a first intertwined portion extending along the CD direction of the nonwoven fabric and a pattern portion in which openings were arranged in a staggered pattern as a second intertwined portion were alternately repeated in the MD direction to form a striped pattern. The dimension in the MD direction of the first intertwined portion (diagonal line pattern portion) was 24 mm, and the dimension in the MD direction of the second intertwined portion (open hole pattern portion) was 11 mm. The acute angle formed by the diagonal line of the first intertwined portion and the CD direction was 57 degrees. In the second intertwined portion, the area per opening was 0.04 mm 2 The shortest distance between the centers of adjacent openings was 1.5 mm, and the proportion of the openings in the second intertwined portion was 1.6%.

[0090] <Production of Nonwoven Fabric 1-D: Comparative Example> Nonwoven fabric 1-D was obtained in the same manner as in the production of nonwoven fabric 1-A, except that the second hydroentanglement treatment was carried out in the following manner. [Hydroentangling process 2] The fiber web after the first hydroentanglement treatment was placed on a support 1, and while the fiber web was moving at a speed of 4 m / min, a columnar water flow with a water pressure of 1.5 MPa was sprayed onto the back surface of the fiber web. The same nozzle as that used in the first hydroentanglement treatment was used to spray the water flow, but a nozzle in which some of the orifices were blocked so that the water flow was not sprayed from the orifices was used. Specifically, a part of the orifice was blocked so that the part P1 with the blocked orifice and the part P2 with the unblocked orifice were 10 mm (P1) and 20 mm (P2) long in the CD direction, respectively, and P1 and P2 were alternately arranged in the CD direction. By using this nozzle, a pattern part in which openings extending along the MD direction were regularly arranged and a plain part extending along the MD direction were alternately formed in the CD direction in the fiber web.

[0091] Next, the fiber web was placed on a support 2, and while the fiber web was moving at a speed of 4 m / min, a columnar water flow with a water pressure of 1.5 MPa was sprayed onto the back surface of the fiber web to obtain a nonwoven fabric. The same nozzle as that used in the first water flow entanglement treatment was used to spray the water flow, but a nozzle in which some of the orifices were blocked so that the water flow was not sprayed from the orifices was used. Specifically, some of the orifices were blocked so that the part Q1 with the blocked orifice and the part Q2 with the unblocked orifice were 20 mm (Q1) and 10 mm (Q2) long in the CD direction, respectively, and Q1 and Q2 were alternately arranged in the CD direction. This nozzle was used to make the water flow hit the previously formed plain part.

[0092] By carrying out the second hydroentanglement treatment according to the above procedure, in nonwoven fabric 1-D, a diagonal line pattern portion extending along the MD direction of the nonwoven fabric and a pattern portion in which the apertures are regularly arranged in a staggered pattern (aperture pattern portion) were alternately formed along the CD direction. The dimension of the diagonal line pattern portion in the CD direction was 10 mm, and the dimension of the aperture pattern portion in the CD direction was 20 mm. In the aperture pattern portion, the area per aperture was 0.4 mm 2 The shortest distance between the centers of adjacent apertures was 1.8 mm, and the proportion of the apertures in the aperture pattern was 13%.

[0093] <Production of Nonwoven Fabric 1-E: Example> Nonwoven fabric 1-E was obtained in the same manner as in the production of nonwoven fabric 1-A, except that support 4 was used in the second hydroentanglement treatment and the second hydroentanglement treatment was carried out as a section entanglement treatment. In nonwoven fabric 1-E, a first intertwined portion extending along the CD direction of the nonwoven fabric, which was a diagonal line pattern portion, and a second intertwined portion, which was a pattern portion in which openings were arranged in a staggered pattern, were alternately repeated in the MD direction to form a striped pattern. The dimension in the MD direction of the first intertwined portion (diagonal line pattern portion) was 14 mm, and the dimension in the MD direction of the second intertwined portion (open hole pattern portion) was 9 mm. The acute angle formed by the diagonal line of the first intertwined portion and the CD direction was 17 degrees. In the second intertwined portion, the area per opening was 0.04 mm 2 The shortest distance between the centers of adjacent openings was 1.5 mm, and the proportion of the openings in the second intertwined portion was 1.1%.

[0094] (Test 2) Nonwoven fabrics 2-A to 2-D were obtained using the same procedures as those used to produce nonwoven fabrics 1-A to 1-D in Test 1, except that 40% by weight of rayon, 40% by weight of PET, and 20% by weight of PP / PE were mixed and a fiber web was produced using a parallel carding machine.

[0095] (Test 3) Nonwoven fabrics 3-A to 3-D were obtained using the same procedures as those used to produce nonwoven fabrics 1-A to 1-D in Test 1, except that 80% by mass of PET and 20% by mass of PP / PE were mixed and a fiber web was produced using a parallel carding machine.

[0096] The nonwoven fabrics produced in Tests 1 to 3 were subjected to a wiping test (gradation change rate when wiping), and were evaluated for thickness, thickness variation coefficient, water absorption properties, and runoff according to the following procedures. Among the nonwoven fabrics produced in Tests 1 to 3, Nonwoven Fabrics 1-A to 1-D, Nonwoven Fabrics 2-A to 2-D, and Nonwoven Fabrics 3-A to 3-D were evaluated for tensile strength, elongation, and stress at 10% and 20% elongation according to the following procedures. The evaluation results are shown in Tables 1 and 2.

[0097] [Table 1]

[0098] [Table 2]

[0099] <Rate of change in gradation when wiping> A transparent acrylic plate (thickness 3 mm, product number: KAC9143-1S, manufactured by Hikari Corporation) with a mark (a square frame with sides of 1.5 cm drawn with a pen) is placed on the opposite side of the mark with three drops (0.05 ml per drop) of a pseudo-soil (a mixture of blue acrylic paint (product name: acrylic paint (blue), manufactured by Daiso Industries Co., Ltd.), ethanol (product name: Wako First-class Ethanol (99.5), manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) and distilled water (blue acrylic paint: ethanol: distilled water = 10:50:40 (mass ratio))) and spread evenly over an area larger than the area of ​​the mark, and air-dried for 60 minutes. The grayscale gradation A within the mark (excluding the area of ​​the square frame drawn with a pen) after air-drying is measured. An image analysis processing software (software name: Image J) is used for gradation measurement. Another acrylic plate is placed on the side with the artificial stain to protect the stain, and image data is captured with a scanner (product name: Docu Centre VIIC4473, manufactured by Fuji Xerox Co., Ltd.). The captured image data is split into RGB channels (Split Channels), and the average value of the gradation within the mark for only the red component is confirmed with a histogram (Histogram). This is defined as grayscale gradation A.

[0100] The pseudo-soil applied to the acrylic plate is attached to a nonwoven fabric sample of 10 cm in the MD direction and 6 cm in the CD direction (100 parts by mass of nonwoven fabric is impregnated with 300 parts by mass of distilled water) and is attached to a plate-shaped jig (wiping area 6 cm x 6 cm). While applying a pressure of 510 Pa, the fabric is moved back and forth twice in a specified direction at a speed of 10 mm / sec and a moving distance of 100 mm. The grayscale gradation B of the pseudo-soil remaining on the acrylic plate after wiping is obtained in the same manner as gradation A, and the gradation change rate T (%) is calculated according to the following formula.

number

[0101] <Thickness, thickness variation coefficient> <How to measure thickness using a microscope> The nonwoven fabric is cut with a sharp blade so as to obtain a rectangular sample with each side parallel to the MD or CD direction. The cut nonwoven fabric is placed on a smooth table, a load of 40 Pa is applied, and a microscope is placed directly beside the cut surface obtained by cutting in a direction perpendicular to the MD direction, and the distance in the thickness direction (thickness) is measured in the part where the fibers exist. Measurements are performed at six points, and the average value is the average thickness in the MD direction. Similarly, a microscope is placed directly beside the cut surface obtained by cutting in a direction perpendicular to the CD direction, and the distance in the thickness direction (thickness) is measured in the part where the fibers exist. Measurements are performed at six points, and the average value is the average thickness in the CD direction. For nonwoven fabrics in which multiple intertwined parts are arranged in a striped pattern, cutting in a direction parallel to the extension direction of the linear parts is performed at only one of the intertwined parts, and the thickness is measured at the cut surface of the intertwined part.

[0102] When only one intertwined portion is observed on the cut surface (when the cut surface consists of one intertwined portion), the standard deviation σ is calculated from the data obtained by measuring the thickness at six points, and the coefficient of variation is calculated from the following formula. When multiple types of intertwined portions are observed on the cut surface (when the cut surface consists of multiple intertwined portions), the thickness is measured at six points on each intertwined portion, the standard deviation is calculated from the measurement data at (6 x types of intertwined portion), and the coefficient of variation is calculated from the following formula. Coefficient of variation of thickness = standard deviation σ / average value of thickness

[0103] <Water absorbency (Bylek method)> In accordance with JIS L 1907 7.1.2, the water absorbency was measured by the Bylek method, and the numerical values in the MD direction and the CD direction were measured. For each direction, four nonwoven fabric specimens were used, and the immersion time in water was 5 minutes. Also, when the water absorbency in the MD direction is A (mm) and the water absorbency in the CD direction is B (mm), the area (mm 2 ) of the pseudo-diffusion ellipse measured by A × B × π was calculated.

[0104] <Tensile strength, elongation rate, stress at 10% elongation, stress at 20% elongation> In accordance with JIS L 1913:2010 6.3, using a constant-speed tension type tensile testing machine, the specimen pieces were subjected to a tensile test under the conditions of a specimen width of 50 mm, a grip interval of 10 cm, and a tensile speed of 30 ± 2 cm / min, and the load value at break (tensile strength), elongation rate, stress at 10% and 20% elongation were measured. The tensile test was carried out with the longitudinal direction (MD direction) and the transverse direction (CD direction) of the nonwoven fabric as the tensile directions. All the evaluation results are shown as the average of the measured values for three specimens.

[0105] Nonwoven fabrics 1-C, 2-C, and 3-C all have a striped pattern in which the first entanglement part and the second entanglement part extend in the CD direction, and the first entanglement part and the second entanglement part are alternately arranged in the MD direction. In these nonwoven fabrics, as shown in Table 2, the relationship between the tensile strength in the CD direction < the strength in the MD direction is satisfied. All of these nonwoven fabrics had a larger coefficient of variation of thickness in the CD direction than other nonwoven fabrics manufactured in the same test. Also, in these nonwoven fabrics, a relatively high tone change rate (wiping property) was shown in the MD direction, and the tone change rate T2 in the MD direction / the tone change rate T1 in the CD direction was 1.0 or more. The tone change rate of nonwoven fabric 1-E was the same. This indicates that a nonwoven fabric having a first entanglement part and a second entanglement part extending in the CD direction exhibits high wiping property when moved in a direction orthogonal to the CD direction.

[0106] Further, the nonwoven fabrics 1-C and 1-E had lower water absorbency in the MD and CD directions and smaller pseudo-diffusion ellipse areas compared to the nonwoven fabrics 1-A and 1-B.

[0107] None of the other nonwoven fabrics (comparative examples) produced in Tests 1 and 3 had a striped pattern in which the linear portions extending in the CD direction were repeatedly arranged along the MD direction. Therefore, although the wiping property of the other nonwoven fabrics in the MD direction was small compared to that of the nonwoven fabric of the example or had no significant difference compared to the example, the wiping property in the CD direction was very low. In particular, in the nonwoven fabrics 1-D, 2-D, and 3-D having a striped pattern in which the linear portions were repeatedly arranged in the CD direction, the wiping property in the CD direction was higher than that in the MD direction, and the gradation change rate T2 in the MD direction / the gradation change rate T1 in the CD direction was less than 1. Therefore, when wiping by pressing and moving in the CD direction with, for example, a human hand without fixing the nonwoven fabric of the comparative example to a tool, the nonwoven fabric tended to break and it was difficult to wipe off the dirt.

[0108] This embodiment includes the following aspects. (Aspect 1) A nonwoven fabric including a first entanglement portion and a second entanglement portion, wherein the first entanglement portion and the second entanglement portion exist in a striped shape, the second entanglement portion and the first entanglement portion each have different patterns from each other, or either one of the second entanglement portion and the first entanglement portion is patternless and the other has a pattern, the tensile strength S1 of the nonwoven fabric in the direction in which the first entanglement portion extends and the tensile strength S2 of the nonwoven fabric in the direction orthogonal to the direction in which the first entanglement portion extends satisfy S1 < S2, nonwoven fabric. (Aspect 2) The nonwoven fabric according to Aspect 1, wherein the dimension of the first entanglement portion in the direction orthogonal to the direction in which the first entanglement portion extends is 2 mm or more and 200 mm or less. (Aspect 3) 3. The nonwoven fabric of embodiment 1 or 2, wherein the dimension of the second entangled parts in a direction perpendicular to the direction in which the second entangled parts extend is 2 mm or more and 200 mm or less. (Aspect 4) The first intertwined portion has a pattern, and the pattern of the first intertwined portion is a diagonal line pattern, The acute angle between the oblique lines of the oblique line pattern and the extension direction of the first intertwined portions is 10 degrees or more and 80 degrees or less. The nonwoven fabric of any one of embodiments 1 to 3. (Aspect 5) The nonwoven fabric of any of Aspects 1 to 4, wherein the second entangled portions have a pattern, and the pattern of the second entangled portions is an open pattern in which open holes are regularly arranged. (Aspect 6) The area of ​​each opening in the opening pattern is 0.50 mm 2 The nonwoven fabric of embodiment 5, which is: (Aspect 7) The nonwoven fabric of any one of embodiments 1 to 6, wherein the coefficient of variation in thickness of a cut section perpendicular to the CD of the nonwoven fabric is 0.09 or more. (Aspect 8) The nonwoven fabric of any of embodiments 1 to 7, wherein, when the rate of gradation change upon wiping is measured by the following method, the rate of gradation change T1 upon wiping in the CD direction of the nonwoven fabric and the rate of gradation change T2 upon wiping in the MD direction of the nonwoven fabric satisfy T2 / T1>1.0. (Method for measuring the rate of change in gradation when wiping) A transparent acrylic plate (thickness 3 mm, product number: KAC9143-1S, manufactured by Hikari Corporation) with a mark (a square frame with sides of 1.5 cm drawn with a pen) is placed on the opposite side of the mark with three drops (0.05 ml per drop) of a pseudo-soil (a mixture of blue acrylic paint (product name: acrylic paint (blue), manufactured by Daiso Industries Co., Ltd.), ethanol (product name: Wako First-class Ethanol (99.5), manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) and distilled water (blue acrylic paint: ethanol: distilled water = 10:50:40 (mass ratio))) and spread evenly over an area larger than the area of ​​the mark, and air-dried for 60 minutes. The grayscale gradation A within the mark (excluding the area of ​​the square frame drawn with a pen) after air-drying is measured. An image analysis processing software (software name: Image J) is used for gradation measurement. Another acrylic plate is placed on the side with the artificial stain to protect the stain, and image data is captured with a scanner (product name: Docu Centre VIIC4473, manufactured by Fuji Xerox Co., Ltd.). The captured image data is split into RGB channels (Split Channels), and the average value of the gradation within the mark for only the red component is confirmed with a histogram (Histogram). This is defined as grayscale gradation A. The pseudo-soil applied to the acrylic plate is attached to a nonwoven fabric sample of 10 cm in the MD direction and 6 cm in the CD direction (100 parts by mass of nonwoven fabric is impregnated with 300 parts by mass of distilled water) and is attached to a plate-shaped jig (wiping area 6 cm x 6 cm). While applying a pressure of 510 Pa, the fabric is moved back and forth twice in a specified direction at a speed of 10 mm / sec and a moving distance of 100 mm. The grayscale gradation B of the pseudo-soil remaining on the acrylic plate after wiping is obtained in the same manner as gradation A, and the gradation change rate T (%) is calculated according to the following formula.

number

[0109] In the nonwoven fabric of the present disclosure, each linear portion constituting the striped pattern extends in a direction perpendicular to the direction in which the tensile strength is greater, and even if the nonwoven fabric is moved back and forth on the surface of an object in a direction perpendicular to the direction in which each linear portion of the striped pattern extends, it is unlikely to twist. In addition, the striped pattern includes at least a first intertwined portion and a second intertwined portion, each of which has a different pattern, or one of which has no pattern and the other has a pattern. Therefore, the nonwoven fabric of the present disclosure is suitable for use as hygiene products such as wipers, sanitary napkins, disposable diapers for infants and infants, disposable diapers for adults, hand towels, face masks, sanitary masks, filters, or poultices.

Claims

1. A nonwoven fabric including a first entangled portion and a second entangled portion, the first intertwined portions and the second intertwined portions are present in a striped pattern, The second intertwined portion and the first intertwined portion have different patterns, or one of the second intertwined portion and the first intertwined portion has no pattern and the other has a pattern; A tensile strength S1 of the nonwoven fabric in a direction in which the first entangled portions extend and a tensile strength S2 of the nonwoven fabric in a direction perpendicular to the direction in which the first entangled portions extend satisfy S1<S2, The direction in which the first intertwined portion extends is the CD direction of the nonwoven fabric. Nonwoven fabric.

2. 2. The nonwoven fabric according to claim 1, wherein the dimension of the first entangled portions in a direction perpendicular to the direction in which the first entangled portions extend is 2 mm or more and 200 mm or less.

3. 3. The nonwoven fabric according to claim 1, wherein the second entangled portions have a dimension of 2 mm or more and 200 mm or less in a direction perpendicular to a direction in which the second entangled portions extend.

4. The first intertwined portion has a pattern, and the pattern of the first intertwined portion is a diagonal line pattern, The acute angle between the oblique lines of the oblique line pattern and the extension direction of the first intertwined portions is 10 degrees or more and 80 degrees or less. The nonwoven fabric according to any one of claims 1 to 3.

5. The nonwoven fabric according to any one of claims 1 to 4, wherein the second entangled portions have a pattern, and the pattern of the second entangled portions is an open pattern in which open holes are regularly arranged.

6. The area of ​​each opening in the opening pattern is 0.50 mm 2 6. The nonwoven fabric of claim 5, wherein:

7. The nonwoven fabric according to any one of claims 1 to 6, wherein the coefficient of variation of thickness of a cut section perpendicular to the CD direction of the nonwoven fabric is 0.09 or more.

8. The nonwoven fabric according to any one of claims 1 to 7, wherein, when the rate of change in gradation upon wiping is measured by the following method, the rate of change in gradation upon wiping in the CD direction of the nonwoven fabric (T1) and the rate of change in gradation upon wiping in the MD direction of the nonwoven fabric (T2) satisfy T2 / T1>1.

0. (Method for measuring the rate of change in gradation when wiping) A transparent acrylic plate (thickness 3 mm, product number: KAC9143-1S, manufactured by Hikari Corporation) with a mark (a square frame with sides of 1.5 cm drawn with a pen) is placed on the opposite side of the mark with three drops (0.05 ml per drop) of artificial dirt (a mixture of blue acrylic paint (product name: acrylic paint (blue), manufactured by Daiso Industries Co., Ltd.), ethanol (product name: Wako First Grade Ethanol (99.5), manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) and distilled water (blue acrylic paint: ethanol: distilled water = 10: 50: 40 (mass ratio))) and spread evenly over an area larger than the area of ​​the mark, and air-dried for 60 minutes, and the grayscale gradation A within the mark (excluding the area of ​​the square frame drawn with the pen) after air-drying is measured. Image analysis processing software (software name: Image J) is used for gradation measurement. Another acrylic plate is placed on the side with the artificial stain to protect the stain, and image data is captured with a scanner (product name: Docu Centre VIIC4473, manufactured by Fuji Xerox Co., Ltd.). The captured image data is split into RGB channels (Split Channels), and the average value of the gradation within the mark for only the red component is confirmed using a histogram, and this is designated as grayscale gradation A. The artificial dirt applied to the acrylic plate is attached to a plate-shaped jig (wiping area 6 cm x 6 cm) of a sample nonwoven fabric (100 parts by weight of nonwoven fabric is impregnated with 300 parts by weight of distilled water) of 10 cm in the MD direction and 6 cm in the CD direction, and while applying a pressure of 510 Pa, it is moved back and forth twice in a specified direction at a speed of 10 mm / sec and a movement distance of 100 mm. After wiping, the grayscale gradation B of the artificial dirt remaining on the acrylic plate is obtained in the same manner as for gradation A, and the gradation change rate T (%) is calculated according to the following formula. [0010]

9. The nonwoven fabric according to any one of claims 1 to 8, wherein the nonwoven fabric contains 30% by mass or more of cellulosic fibers when the mass of the nonwoven fabric is taken as 100% by mass.

10. The nonwoven fabric has a basis weight of 30 g / m ２ 80g / m or more ２ The nonwoven fabric according to any one of claims 1 to 9, wherein:

11. A wiper comprising the nonwoven fabric according to any one of claims 1 to 10.

12. Producing a fibrous web; placing the fibrous web on a support and subjecting the fibrous web to an entanglement treatment using a high-pressure fluid flow; Including, In the entanglement treatment, it is assumed that the fiber web has a first section and a second section extending along the CD direction in a striped pattern, The entanglement treatment is performed under different treatment conditions when the first section of the fiber web is subjected to the entanglement treatment and when the second section of the fiber web is subjected to the entanglement treatment, so that the first entangled portion, which is the first section after the entanglement treatment, and the second entangled portion, which is the second section after the entanglement treatment, have different patterns, or one of the first entangled portion, which is the first section after the entanglement treatment, and the second entangled portion, which is the second section after the entanglement treatment, has no pattern and the other has a pattern. A method for manufacturing nonwoven fabric.

13. The method for producing a nonwoven fabric according to claim 12, wherein the entanglement treatment of the first section of the fibrous web and the entanglement treatment of the second section of the fibrous web are performed simultaneously by placing the fibrous web on a single support.

14. The method for producing a nonwoven fabric according to claim 13, wherein the support used in the entanglement treatment has two types of weave structure regularly repeated along the MD direction.

15. The method for producing a nonwoven fabric according to claim 14, wherein the support used in the entanglement treatment has plain weave portions and twill weave portions alternately and repeatedly formed along the MD direction.

16. The method for producing a nonwoven fabric according to any one of claims 12 to 15, further comprising a total entanglement treatment of performing an entanglement treatment using a high-pressure fluid flow under the same treatment conditions over the entire fiber web before performing the entanglement treatment.

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