Nonwoven fabric for absorbent article and method for manufacturing the same

Abstract

Provided is a nonwoven fabric that is excellent in visual recognition in the thickness direction. A nonwoven fabric (10) for an absorbent article has a first direction, a second direction, and a thickness direction that are orthogonal to each other, and is composed of continuous fibers, wherein the nonwoven fabric has: a plurality of ridge portions (12) that extend along the first direction; and a plurality of groove portions (14) that extend along the first direction and have a lower basis weight than the plurality of ridge portions (12), each of the plurality of ridge portions (12) and each of the plurality of groove portions (14) being alternately arranged in the second direction, each of the plurality of ridge portions (12) and each of the plurality of groove portions (14) having a plurality of junction portions in which the continuous fibers are thermally joined to each other at intersections.

Description

Technical Field

[0001] This invention relates to nonwoven fabrics for absorbent articles and methods for manufacturing the same. Background Technology

[0002] Nonwoven fabrics with multiple irregularities on their surface are known. Examples of such nonwoven fabrics include the surface sheet of disposable diapers.

[0003] Patent Document 1 discloses a nonwoven fabric formed by spraying a fluid, mainly composed of gas, onto a fiber assembly. The nonwoven fabric has a longitudinal direction and a transverse direction. The nonwoven fabric has: a plurality of low unit area weight portions formed along the longitudinal direction; and a plurality of high unit area weight portions formed adjacent to each of the plurality of low unit area weight portions, wherein the unit area weight of each of the plurality of low unit area weight portions is lower than the unit area weight of each of the plurality of high unit area weight portions.

[0004] According to Patent Document 1, a nonwoven fabric can be provided in which the fibers constituting the fiber web are moved by spraying gas from the upper surface side of the fiber web, the fiber web being supported from the lower surface side by a predetermined air-permeable support member, thereby at least adjusting the weight per unit area and facilitating liquid permeation.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2008-25079 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] Regarding the nonwoven fabric described in Patent Document 1, for example, when applied to the surface sheet of a disposable diaper, excreted bodily fluids easily pass through the low-weight-per-unit area portions, and the bodily fluids absorbed by the absorbent body through these low-weight-per-unit area portions can be visually identified. However, since this nonwoven fabric is composed of short fibers, it is prone to deformation in the thickness direction. Nonwoven fabrics that are prone to deformation in the thickness direction tend to thin when subjected to a load in the thickness direction during wear. When this thinning nonwoven fabric is applied to the surface sheet of a disposable diaper, the thickness of multiple high-weight-per-unit area portions thins and expands along the surface direction due to the load in the thickness direction. If multiple high-weight-per-unit area portions expand along the surface direction, the range of low-weight-per-unit area portions with lower basis weight correspondingly narrows, thus resulting in a decrease in visual recognizability.

[0010] The present invention aims to provide a nonwoven fabric with excellent visual recognizability in the thickness direction.

[0011] Solution for solving the problem

[0012] The present invention relates to a nonwoven fabric for absorbent articles, having mutually orthogonal first, second, and thickness directions and being composed of continuous fibers. The nonwoven fabric comprises: a plurality of ridges extending along the first direction; and a plurality of grooves extending along the first direction, wherein the basis weight of the plurality of grooves is lower than that of the plurality of ridges. The ridges and grooves are alternately arranged in the second direction, and each ridge and groove has a plurality of joints formed by thermally bonding the intersections of the continuous fibers.

[0013] The effects of the invention

[0014] The nonwoven fabric according to the present invention has excellent visual recognizability in the thickness direction. Attached Figure Description

[0015] Figure 1 This is a perspective view of a nonwoven fabric schematically representing an embodiment.

[0016] Figure 2 This is a cross-sectional view of the nonwoven fabric of the embodiment, orthogonal to the first direction.

[0017] Figure 3 This is a perspective view of the wire mesh used in the nonwoven fabric manufacturing method of the embodiment.

[0018] Figure 4 It is a cross-sectional view of the screen orthogonal to the MD direction.

[0019] Figure 5 This is a top view schematically illustrating an absorbent article according to an embodiment.

[0020] Figure 6A This is a microscope image (20x) of nonwoven fabric.

[0021] Figure 6B yes Figure 6A Microscopic photograph of a section of nonwoven fabric (100x magnification).

[0022] Figure 6C yes Figure 6B Microscopic photograph of a section of nonwoven fabric (300x magnification).

[0023] Figure 6D It is a microscope image (50x) of a cross-section of a nonwoven fabric orthogonal to the first direction. Detailed Implementation

[0024] The embodiments of the present invention relate to the following methods.

[0025] [Method 1]

[0026] A nonwoven fabric, used for absorbent articles, has mutually orthogonal first, second, and thickness directions and is composed of continuous fibers, wherein...

[0027] This nonwoven fabric has the following characteristics:

[0028] Multiple ridges extending along the first direction; and

[0029] Multiple grooves extending along the first direction, wherein the basis weight of the multiple grooves is lower than the basis weight of the multiple ridges.

[0030] The ridges and grooves of the plurality of ridges are alternately arranged in the second direction.

[0031] Each of the plurality of ridges and each of the plurality of grooves has a plurality of joints formed by thermally joining the intersections of the continuous fibers to each other.

[0032] The aforementioned nonwoven fabric is composed of continuous fibers, and each of the multiple ridges and the multiple grooves has multiple joints formed by thermally joining the intersections of the continuous fibers to each other. Therefore, it is easy to maintain its shape, and the thickness variation under a load applied in the thickness direction is smaller than that of nonwoven fabrics composed of short fibers.

[0033] Because the aforementioned nonwoven fabric has multiple joints formed by thermally bonding the intersections of continuous fibers, it easily maintains its shape, and therefore the thickness of the rib section is less prone to change when a load is applied in the thickness direction. Consequently, the length of the rib section in the second direction is also less prone to change, and therefore the length of the groove section in the second direction is also less prone to change. In other words, in the aforementioned nonwoven fabric, the structure of the rib and groove sections is less prone to change, and the length of the groove section in the second direction is less prone to change, thus the range of visual recognizability is less prone to change. Therefore, for the groove section, visual recognizability in the thickness direction through the groove section is excellent. For example, when the nonwoven fabric is used as the outermost layer of a disposable diaper, even when subjected to load over time after wear, the visual recognizability in the thickness direction through the groove section remains excellent.

[0034] In nonwoven fabrics, the ribs and grooves are alternately arranged in the second direction, thereby providing excellent visual recognition through the grooves over a large range in both the first and second directions.

[0035] Furthermore, in nonwoven fabrics composed of short fibers, the ribbed portion tends to thin under loads applied in the thickness direction. When the ribbed portion thins due to a load in the thickness direction, its length in the second direction widens, and correspondingly, the length of the grooved portion in the second direction narrows. When the width of the grooved portion narrows, the range of visual recognizability becomes narrower. Therefore, the visual recognizability of the grooved portion in nonwoven fabrics formed from short fibers and having both ribbed and grooved portions tends to deteriorate.

[0036] [Method 2]

[0037] For the nonwoven fabric described in method 1, among which,

[0038] The nonwoven fabric is used as a liquid-permeable sheet for the absorbent article.

[0039] The aforementioned nonwoven fabric is used as a liquid-permeable sheet for absorbent articles. An absorbent article can be exemplified by comprising a liquid-permeable sheet, an absorbent core, and a liquid-impermeable sheet in sequence. For example, the aforementioned nonwoven fabric, used as a liquid-permeable sheet in disposable diapers, exhibits minimal thickness variation during wear, thus easily maintaining a gap between the absorbent core and the user's skin. As a result, this nonwoven fabric exhibits excellent suppression of moisture.

[0040] In nonwoven fabrics, the ribbed and grooved portions are alternately arranged in the second direction, thereby maintaining a gap between the absorbent and the user's skin over a large area in both the first and second directions, resulting in excellent suppression of moisture.

[0041] Furthermore, nonwoven fabrics made from short fibers are prone to shape changes, and their thickness varies considerably under load in the thickness direction, making them easily thinner. Therefore, nonwoven fabrics made from short fibers struggle to maintain a proper gap between the absorbent and the user's skin, resulting in a feeling of dampness.

[0042] [Method 3]

[0043] For the nonwoven fabric described in method 1, among which,

[0044] The nonwoven fabric is used as the outer covering sheet for the absorbent article.

[0045] The aforementioned nonwoven fabric is used as the outer covering sheet for absorbent articles. An absorbent article can be exemplified by sequentially comprising a liquid-permeable sheet, an absorbent body, a liquid-impermeable sheet, and an outer covering sheet. The absorbent article may be provided with an indicator portion (preferably between the absorbent body and the liquid-impermeable sheet) and a pattern (preferably on the inner or outer surface of the liquid-impermeable sheet). The aforementioned nonwoven fabric can, for example, be applied to the outer covering sheet of disposable diapers. In the aforementioned nonwoven fabric, even under load in the thickness direction, the multiple ridges are not easily deformed, and the length of the multiple grooves in the second direction can be maintained with a low basis weight, thus maintaining excellent breathability and visual visibility of the multiple grooves. Therefore, absorbent articles in which the nonwoven fabric is applied to the outer covering sheet and the side with the multiple ridges and multiple grooves is positioned on the non-skin side can achieve excellent breathability and visual visibility after wearing. In addition, in absorbent articles in which non-woven fabric is applied to the outer cover and the side with multiple ridges and multiple grooves is placed on the skin side, the space formed between the non-woven fabric and the liquid-impermeable sheet makes it difficult for moisture to be transferred to clothing, sheets, etc.

[0046] [Method 4]

[0047] For the nonwoven fabric described in any of methods 1 to 3, among which,

[0048] Each of the plurality of ridges has a plurality of recesses that are recessed along the thickness direction, and each of the plurality of recesses has a base made of the continuous fibers at its bottom.

[0049] The aforementioned nonwoven fabric has grooves and multiple recesses along its thickness in the rib section, thus reducing the contact area between the user's skin and the nonwoven fabric compared to nonwoven fabrics without recesses. In the case of the aforementioned nonwoven fabric, for example, in the case of a liquid-permeable sheet used in disposable diapers, the base absorbs excreted bodily fluids and more reliably prevents the return of absorbed bodily fluids into the recesses. Therefore, the nonwoven fabric exhibits excellent suppression of moisture. Furthermore, in the case of the aforementioned nonwoven fabric, for example, in the case of an outer sheet used in disposable diapers, the side with multiple ribs and grooves can be positioned on the non-skin side. In this case, the contact area of ​​the nonwoven fabric surface is further reduced accordingly, thus providing a refreshing feel and exhibiting a complex fabric-like surface shape. Additionally, in the aforementioned nonwoven fabric, when the side with multiple ribs and grooves is positioned on the skin side, the space formed between the nonwoven fabric and the liquid-impermeable sheet is further increased accordingly, thus making it less likely for moisture to be transferred to clothing, sheets, etc.

[0050] [Method 5]

[0051] For the nonwoven fabric described in method 4, among which,

[0052] Each of the plurality of ridges has a bundle-like portion on at least a portion of the plurality of recesses in the second direction, the bundle-like portion being joined by the plurality of joints through the continuous fibers in a state oriented along the first direction.

[0053] In the aforementioned nonwoven fabric, each of the plurality of ridges has a bundle-like portion formed by multiple joints joining continuous fibers in a state oriented along a first direction on at least a partial second direction side of the plurality of recesses. In the bundle-like portion, the spacing between the continuous fibers is small, making it less prone to deformation under load. Therefore, the aforementioned nonwoven fabric with the bundle-like portion easily maintains the shape of the recesses with minimal thickness variation when worn.

[0054] [Method 6]

[0055] For the nonwoven fabrics described in method 4 or 5, wherein,

[0056] The thickness of each of the plurality of grooves is thinner than the thickness of the base.

[0057] In the aforementioned nonwoven fabric, since the thickness of each of the multiple grooves is thinner than the thickness of the base, for example, in applications such as liquid-permeable sheets or outer coverings for disposable diapers, the visual recognizability of the grooves in the thickness direction is excellent, thus the difference from the ribbed sections, which have almost no visual recognizability in the thickness direction, is more prominent. Therefore, the aforementioned nonwoven fabric has excellent visual recognizability.

[0058] [Method 7]

[0059] For any of the nonwoven fabrics described in methods 1 to 6, among which,

[0060] The continuous fiber is a composite fiber containing olefin resin.

[0061] Because continuous fibers are composite fibers containing olefin resins, they can form joints even at lower heat treatment temperatures, thus enabling more efficient formation of joints throughout the nonwoven fabric. Since the nonwoven fabric has joints formed throughout, it easily maintains its shape when subjected to loads in the thickness direction after wear, making the structure of the ribs and grooves less prone to change.

[0062] [Method 8]

[0063] For any of the nonwoven fabrics described in methods 1 to 7, among which,

[0064] The average fiber diameter of the continuous fibers is greater than 15 μm and less than 30 μm, and the average basis weight of the nonwoven fabric is 10 g / m³. 2 Above and 40g / m 2 the following.

[0065] The average fiber diameter of the continuous fibers in the aforementioned nonwoven fabric is 15 μm or more and 30 μm or less, and the average basis weight of the nonwoven fabric is 10 g / m³. 2 Above and 40g / m 2 Therefore, when a load is applied in the thickness direction after wearing, the structure of the ridge and groove that easily maintains its shape can be obtained more reliably.

[0066] [Method 9]

[0067] For any of the nonwoven fabrics described in methods 1 to 8, among which,

[0068] The first direction is configured along the length of the absorbent article.

[0069] In the aforementioned nonwoven fabric, the grooves and ridges are arranged along the length of the absorbent article, thus providing excellent visual visibility along the length. Furthermore, in the case of a liquid-permeable sheet used in disposable diapers, bodily fluids tend to diffuse along the length of the absorbent article. Therefore, in the aforementioned nonwoven fabric, by allowing bodily fluids to diffuse along the length, the retention of bodily fluids in one place is suppressed, resulting in excellent suppression of wetness.

[0070] [Method 10]

[0071] For any of the nonwoven fabrics described in methods 1 to 8, among which,

[0072] The first direction is configured in the width direction of the absorbent article.

[0073] In the aforementioned nonwoven fabric, the grooves and ridges are arranged along the width direction of the absorbent material, thus providing excellent visual visibility in the width direction. Furthermore, in the case of a liquid-permeable sheet used in disposable diapers, bodily fluids tend to diffuse in the width direction of the absorbent material. Therefore, in the aforementioned nonwoven fabric, by allowing bodily fluids to diffuse in the width direction, the retention of bodily fluids in one place is suppressed, resulting in excellent suppression of wetness.

[0074] [Method 11]

[0075] For any of the nonwoven fabrics described in methods 1 to 10, among which,

[0076] Each of the plurality of ridges has a plurality of protrusions that project toward each of the plurality of adjacent slots and are spaced apart along the first direction.

[0077] In the aforementioned nonwoven fabric, each of the multiple ridges has multiple protrusions that protrude toward each of the adjacent multiple grooves and are spaced apart along a first direction. Therefore, when a load is applied in the thickness direction, the ridges are less likely to tip over. Consequently, in this nonwoven fabric, for example in the case of a liquid-permeable sheet or outer sheet used in disposable diapers, the ridges are easily kept in shape, and thus the ridges do not close the grooves, resulting in excellent visual recognizability.

[0078] [Method 12]

[0079] For any of the nonwoven fabrics described in methods 1 to 11, among which,

[0080] The fiber orientation of each of the plurality of ridges along the first direction is higher than that of each of the plurality of grooves along the first direction.

[0081] In the aforementioned nonwoven fabric, the fiber orientation along the first direction of the multiple ridges is higher than that of the multiple grooves, resulting in shorter distances between the intersections of continuous fibers and shorter distances between the multiple joints. Therefore, in the aforementioned nonwoven fabric, it is easier to maintain the shape of the multiple ridges.

[0082] [Method 13]

[0083] For any of the nonwoven fabrics described in methods 1 to 12, among which,

[0084] The nonwoven fabric is a spunbond nonwoven fabric.

[0085] Since the aforementioned nonwoven fabric is a spunbond nonwoven fabric, during manufacturing, when the continuous fibers move through the airflow, their relatively long length causes them to move across a certain length, leading to the movement of adjacent continuous fibers. Therefore, it is easily affected by the airflow during the stacking process. Consequently, by moving the continuous fibers individually, it is easy to form sections with smaller fiber spacing. The distance between the intersections of the continuous fibers is short, and the distance between multiple joints is also short. Therefore, in the aforementioned nonwoven fabric, it is easy to maintain the shape of multiple ribs.

[0086] Furthermore, for nonwoven fabrics composed of short fibers, such as those in air-laid nonwoven fabrics, the short fibers move independently during manufacturing due to their shorter length, having less impact on other fibers and thus being less susceptible to airflow during the stacking process. Consequently, fewer fibers move in short fibers, making it easier to maintain a random stacking state, resulting in a larger fiber spacing compared to continuous fibers. Because of the larger fiber spacing, short-fiber nonwoven fabrics are prone to deformation under load, leading to greater thickness variations during wear. Therefore, it is difficult to maintain a proper gap between the absorbent and the wearer's skin, resulting in a feeling of dampness. Additionally, the significant thickness variation in short-fiber nonwoven fabrics before and after wear causes changes in the structure of the weft and groove sections during thickness loads and thickness recovery. Consequently, the upper and lower sides of the nonwoven fabric in the thickness direction tend to shift towards the planar direction, causing variations in the basis weight of the grooves and resulting in poorer visual visibility.

[0087] [Method 14]

[0088] A method for manufacturing a nonwoven fabric, wherein the method for manufacturing a nonwoven fabric is described in any one of methods 1 to 13, wherein...

[0089] The method for manufacturing the nonwoven fabric includes the following steps:

[0090] While drawing continuous fibers from the underside of a wire mesh having mutually orthogonal conveying, transverse, and height directions, the continuous fibers are stacked on the wire mesh; and

[0091] The continuous fibers stacked on the wire mesh are thermally bonded together.

[0092] The wire mesh has the following characteristics:

[0093] The main body of the network; and

[0094] Multiple protrusions extend along the conveying direction, are arranged at predetermined intervals on the net body in the transverse direction, and protrude in the height direction.

[0095] In the above-described method for manufacturing nonwoven fabric, continuous fibers are deposited onto the web by being attracted from below. Some of the continuous fibers preferentially aggregate between the non-ribbed sections of the web body. This preferential aggregation of continuous fibers between the ribbed sections results in a denser continuous fiber layer, forming a ridge section with a higher basis weight. Conversely, the continuous fibers become sparser on the ribbed sections, forming a groove section with a lower basis weight. Furthermore, the continuous fibers are thermally bonded while deposited on the web, thereby maintaining the shape of the ridge and groove sections. Therefore, the above-described method for manufacturing nonwoven fabric can produce a nonwoven fabric composed of continuous fibers, having multiple ridges and multiple grooves, and having multiple joints formed by thermally bonding the intersections of the continuous fibers.

[0096] [Method 15]

[0097] Regarding the method for manufacturing nonwoven fabric described in Method 14, wherein,

[0098] The height of the protrusion is 1.0 mm or more.

[0099] In the above-described method for manufacturing nonwoven fabric, since the height of the ribs is 1.0 mm or more, continuous fibers are less likely to remain on the ribs, and continuous fibers accumulate between the ribs, thus forming a ridge with a predetermined thickness. Therefore, the above-described method for manufacturing nonwoven fabric can more reliably produce nonwoven fabrics with multiple ridges and multiple grooves.

[0100] [Method 16]

[0101] For the nonwoven fabric manufacturing method described in method 14 or 15, wherein,

[0102] The total length of each of the plurality of protruding strips in the transverse direction is less than 50% of the length of the main body of the net in the transverse direction.

[0103] In the above-described method for manufacturing nonwoven fabric, since the total length of each of the multiple protrusions in the transverse direction is less than 50% of the length of the web body in the transverse direction, sufficient air permeability is achieved through the web body excluding the protrusions. Therefore, this method enables the stable stacking of continuous fibers on the web, thus allowing for more reliable manufacturing of nonwoven fabrics with multiple ridges and multiple grooves.

[0104] [Method 17]

[0105] For any of the nonwoven fabric manufacturing methods described in methods 14 to 16, wherein,

[0106] Each of the plurality of protrusions has a plurality of bulges that bulge out in the transverse direction.

[0107] The nonwoven fabric is manufactured by having multiple protrusions extending in the transverse direction, such that the continuous fibers in the protrusions become sparse, and the protrusions become protrusions from the ridge to the groove. Therefore, the above-described method for manufacturing nonwoven fabric can produce nonwoven fabric with protrusions in the ridge.

[0108] [Method 18]

[0109] For any of the nonwoven fabric manufacturing methods described in methods 12 to 15, wherein,

[0110] The outer diameter of the filaments forming the mesh is smaller than the height of the protrusions.

[0111] Because the outer diameter of the filaments forming the mesh is smaller than the height of the ribs, even in the areas where the filaments overlap, the ribs are higher than the filaments, thus forming grooves. Therefore, the above-described method for manufacturing nonwoven fabric can more reliably produce nonwoven fabrics with both grooves and ribs. Furthermore, because the overlapping portion of the filaments is smaller than the ribs, continuous fibers easily accumulate on the mesh, thus forming grooves with concave portions.

[0112] [Method 19]

[0113] For any of the nonwoven fabric manufacturing methods described in methods 14 to 18, wherein,

[0114] The continuous fibers are deposited on the wire mesh at a fiber speed of 1000 m / min or more and 4500 m / min or less.

[0115] By setting the fiber speed of the continuous fibers to 1000 m / min or higher, the continuous fibers are easily stacked on the web, facilitating the formation of ridges. Furthermore, by setting the fiber speed of the continuous fibers to 4500 m / min or lower, orientation disorder of the continuous fibers on the web can be suppressed, thus also facilitating the formation of ridges. Therefore, by keeping the continuous fibers within the above range, nonwoven fabrics with multiple ridges and multiple grooves can be manufactured efficiently.

[0116] The following describes the nonwoven fabric used for absorbent articles according to the embodiments. In this specification, "along a predetermined direction" refers to the following: the object extends with an angle of less than ±90° to the predetermined direction (e.g., the first direction, the second direction, etc.). Furthermore, when the object extends along the predetermined direction, it is preferable that the object has an angle of less than 60° with the predetermined direction, more preferably less than 45°, even more preferably less than 30°, even more preferably less than 20°, and even more preferably less than 5°.

[0117] Appropriately set the orthogonal coordinates shown in the figure as x: first direction, y: second direction, z: thickness direction, and also set as MD: conveying direction, CD: transverse direction, H: height direction, L: length direction, W: width direction.

[0118] (Structure of nonwoven fabric)

[0119] Figure 1 The nonwoven fabric 10 for absorbent articles shown has mutually orthogonal first direction x, second direction y, and thickness direction z, and is composed of continuous fibers. There are no particular limitations as long as the nonwoven fabric 10 is formed of continuous fibers; for example, spunbond nonwoven fabric can be cited. There are no particular limitations as long as the continuous fibers are fibers that can be melted and thermally bonded by heating. Examples of such thermally bondable fibers include single fibers of polyolefins such as polyethylene, polypropylene, and polyvinyl alcohol, and core-sheath type composite fibers containing olefin resins such as polyethylene terephthalate (core) / polyethylene (sheath), polyethylene terephthalate (core) / polypropylene (sheath), and polypropylene (core) / polyethylene (sheath). The composite fibers can be either hydrophobic fibers or fibers that have undergone hydrophilic treatment using hydrophilic oils or the like. Hydrophilic treatment can be performed, for example, by mixing a hydrophilic agent into the resin constituting the fiber or by coating the surface of the fiber with a hydrophilic agent. Alternatively, the composite fiber can also be a parallel-type fiber containing the aforementioned olefin resins. These fibers can be used alone or in combination with two or more fibers. Preferably, the continuous fibers contain thermoplastic resin fibers with a lower melting point. The average fiber diameter of the continuous fibers can be 15 μm or more and 30 μm or less. Since the nonwoven fabric 10 is composed of continuous fibers, it is preferable that the surface of the nonwoven fabric 10 does not contain ends with continuous fibers. Figure 1 and Figure 2 The fine lines in the diagram schematically represent the fibers of the nonwoven fabric 10. The direction, length, and diameter of the fibers do not imply the direction, length, and diameter of the continuous fibers of the nonwoven fabric 10.

[0120] The average fiber diameter of continuous fibers can be measured as follows. First, a 10mm × 10mm sample of nonwoven fabric is cut and placed on a glass slide. Next, a suitable amount of glycerin is dropped onto the sample to impregnate the entire sample with glycerin, and a coverslip is placed on it. Next, the sample is observed at 1000x magnification using a known optical microscope (e.g., Keyence VHC-100 digital microscope VH-Z450), and the fiber diameter of 50 exposed fibers on the surface of the sample is measured. The average value is taken as the average fiber diameter.

[0121] The nonwoven fabric 10 can have any shape, size, and average basis weight corresponding to the various constituent components of the absorbent article to which it is applied. For example, the average basis weight of the nonwoven fabric 10 can be 10 g / m³. 2 Above and 40g / m 2 the following.

[0122] The average basis weight is measured using the following method. First, five samples of a predetermined size (e.g., 100mm × 100mm) are cut from the nonwoven fabric. Next, the mass of the five cut samples is measured using a direct-reading balance (e.g., an electronic balance HF-300 manufactured by Kensei Kogyo Co., Ltd.). Then, the mass per unit area of ​​the nonwoven fabric (g / m²) is calculated based on the average mass of the five samples. 2 () is used as the average basis weight of the nonwoven fabric.

[0123] The average thickness of the nonwoven fabric 10 is, for example, 0.1 mm to 3 mm. The average thickness of the nonwoven fabric 10 refers to the thickness measured using the FS-60DS [measuring surface 50.5 mm (diameter), measuring pressure 3 gf / cm] manufactured by Daiei Scientific Precision Instruments Co., Ltd. 2 [0.3kPa] The average of five measurements was obtained by applying pressure to five different parts of the nonwoven fabric under standard conditions (temperature 23±2℃, relative humidity 50±5%) and measuring the thickness of each part after 10 seconds of pressure application.

[0124] The tensile strength per average basis weight of the nonwoven fabric 10 is not particularly limited as long as it does not hinder the effect of the present invention, and any tensile strength corresponding to the desired softness, strength, etc., can be adopted. For example, the tensile strength per average basis weight of the nonwoven fabric 10 in the first direction x can be set to 0.3 [(N / 50mm) / (g / m³)]. 2 )] above and 3.0[(N / 50mm) / (g / m 2 The tensile strength per average basis weight of the nonwoven fabric 10 in the second direction y can be set, for example, to 0.2 [(N / 50mm) / (g / m²)]. 2 ))] above and 1.2[(N / 50mm) / (g / m 2 )]the following.

[0125] The average breaking strength per average basis weight is defined as the value obtained by dividing the measured average breaking strength by the average basis weight. The average breaking strength was measured using an AG-1 universal testing machine manufactured by Shimadzu Corporation. First, five specimens with a length of 150 mm in the first x-direction and 50 mm in the second y-direction were prepared, along with five specimens with a length of 50 mm in the first x-direction and 150 mm in the second y-direction. Next, the breaking strength of the composite sheet in the first x-direction and the second y-direction was measured at a chuck spacing of 100 mm and a tensile speed of 100 mm / min. Then, the average of the breaking strengths of each set of five specimens was defined as the average breaking strength for that specific section. "N / 50 mm" indicates the breaking strength (N) per 50 mm width. Furthermore, the breaking strength represents the strength under maximum load.

[0126] The nonwoven fabric 10 has multiple ribs 12 and multiple grooves 14. The multiple ribs 12 and multiple grooves 14 are located on one side of the nonwoven fabric 10 in the thickness direction z. Figure 1 In the case of a nonwoven fabric 10, the ribs 12 are located on the upper side. Multiple ribs 12 protrude from one side of the nonwoven fabric 10 in the thickness direction z and extend along the first direction x. Multiple grooves 14 extend along the first direction x, and the basis weight of the multiple grooves 14 is lower than that of the multiple ribs 12. The ribs 12 and grooves 14 are alternately arranged in the second direction y. The multiple ribs 12 are arranged at predetermined intervals in the second direction y.

[0127] For each of the plurality of ridges 12, the amount of continuous fibers is greater than the amount of continuous fibers in the plurality of grooves 14, but the ridges are thicker than the grooves 14. That is, the thickness of the grooves 14 is thinner than the thickness of the ridges 12. The thickness of the ridges 12 is equivalent to the thickness of the nonwoven fabric 10 described above. The ridges 12 and the grooves 14 are connected by relatively gentle surfaces. Figure 2 As shown, for the multiple ridges 12 and multiple grooves 14, the thickness T is 50% of the thickness Tn of the nonwoven fabric 10 in the unloaded state. 50 As a boundary, regions with a thickness of 50% or more of the thickness Tn are designated as ridges 12, and regions with a thickness of less than 50% of the thickness Tn are designated as multiple grooves 14.

[0128] Each of the plurality of ridges 12 and each of the plurality of grooves 14 has a plurality of joints (not shown) formed by thermally bonding the intersections of continuous fibers together. Since these joints are not pressed together, they are not membrane-like. Regarding the nonwoven fabric 10, because the continuous fibers are spaced apart from each other, it is relatively fluffy, and because the intersections are thermally bonded, it easily maintains its shape. Therefore, the nonwoven fabric 10 easily maintains the shape having the plurality of ridges 12 and the plurality of grooves 14.

[0129] Preferably, the fiber orientation of the plurality of ridges 12 along the first direction x is higher than that of the plurality of grooves 14 along the first direction x. By making the fiber orientation of the plurality of ridges 12 along the first direction x higher, the distance between the intersection points of the continuous fibers is shorter, and the distance between the plurality of joints is shorter, thus making it easier to maintain the shape. Fiber orientation is a concept composed of the fiber orientation angle and orientation intensity, and can be measured, for example, by the following method: The nonwoven fabric 10 is placed with the surface having the plurality of ridges 12 and the plurality of grooves 14 on the upper side. Using a microscope (e.g., a scanning electron microscope such as JCM-5100 manufactured by Nippon Electron Ltd.), a magnified image of the measurement surface of the nonwoven fabric 10 is taken from a vertical direction and printed, and the fibers are drawn on a transparent PET sheet. The magnified image is an image magnified to a magnification that allows the measurement of more than 10 fibers, for example, a magnification of 50x to 300x. The image was imported into a personal computer and binarized using Nexus New Qube (single-user version) image processing software manufactured by NEXUS Corporation. The orientation angle and orientation intensity were obtained from the binarized image using Fiber Orientation Analysis 8.13 Single, a fiber orientation analysis program. The orientation angle is the angle at which the fiber's orientation is greatest, and the orientation intensity is the strength at that orientation angle. Measurements were repeated several times (e.g., 3 to 5 times), and the average value was calculated.

[0130] Each of the plurality of ridges 12 may have a plurality of recesses 16. Each recess 16 is an elongated shape with a length in the first direction x longer than its length in the second direction y, and is arranged at intervals along the first direction x. Each of the plurality of recesses 16 is recessed along the thickness direction z, and each recess 16 has a base 18 at its bottom. The base 18 is composed of continuous fibers. The amount of continuous fibers in the base 18 is less than the amount of continuous fibers in the portions of the plurality of ridges 12 excluding the base 18, and the base 18 has a plurality of joints (not shown) formed by thermally joining the intersections of the continuous fibers. The thickness Tb of the base 18 is thicker than the respective thickness Tc of the plurality of grooves 14. That is, the respective thickness Tc of the plurality of grooves 14 is thinner than the thickness Tb of the base 18.

[0131] Multiple ridges 12 may also have bundles 20 on at least a partial side of the recess 16 in the second direction y. The bundle 20 has multiple continuous fibers joined by multiple joints in a state oriented along the first direction x. "Oriented along the first direction x" is not limited to the case where the continuous fibers are parallel to the first direction x, but also includes the case where the orientation is within a range where the angular difference relative to the first direction x is 30 degrees or less. The intersection points of the continuous fibers of the bundle 20 are thermally bonded to each other through multiple joints. The fiber spacing between the continuous fibers of the bundle 20 is smaller than when the continuous fibers are not oriented along a specific direction. That is, in the bundle 20, since the continuous fibers between the joints are oriented along the first direction x, the fiber spacing between the continuous fibers between the joints is smaller. Furthermore, when a load in the thickness direction z is applied to the bundle 20, the probability of the continuous fibers of the bundle 20 making line contact with each other is higher, and therefore it is less prone to deformation in the thickness direction z. The bundle 20 may also be formed on both sides of the recess 16 in the second direction y.

[0132] On the other hand, in the case of continuous fibers that are not oriented in a specific direction, the continuous fibers between the joints are oriented in an unspecified direction. Therefore, when a load is applied in the thickness direction z, the fibers are more likely to make point contact with each other, and the fibers in the non-contact range deform.

[0133] The thickness of the nonwoven fabric 10 under no-load conditions, the thickness of the multiple grooves 14, and the thickness of the base 18 are measured using a two-dimensional laser displacement meter. For example, the high-precision two-dimensional laser displacement meter LJ-G series (model: LJ-G030) manufactured by Keyence Corporation can be cited as an example. The nonwoven fabric is placed on a horizontal measuring stage, and the displacement of each target part of the nonwoven fabric from the measuring stage is measured at five different points using the laser displacement meter. The average of the five measurements is taken as the thickness (mm) of each target part of the nonwoven fabric.

[0134] Each of the multiple ridges 12 may also have multiple protrusions 22 protruding toward each of the adjacent multiple grooves 14. The multiple protrusions 22 protrude along a second direction y and are arranged at intervals along a first direction x. The protrusions 22 of each of the multiple ridges 12 are recessed along the second direction y. The multiple protrusions 22 are respectively provided on both sides of the multiple ridges 12, and the protrusions 22 may also be provided in a position where they overlap in the second direction y. When the protrusions 22 are provided in a position where they overlap in the second direction y, the multiple ridges 12 and the multiple grooves 14 respectively form a wider portion and a narrower portion. Alternatively, the protrusions 22 may also be provided in a position where they do not overlap in the second direction y. When the protrusions 22 are provided in a position where they do not overlap in the second direction y, the multiple ridges 12 and the multiple grooves 14 each have a substantially constant width.

[0135] Because the amount of continuous fibers in the multiple grooves 14 is relatively small, their respective thicknesses Tc are thinner than the thickness Tb of the base 18, resulting in less overlap of the continuous fibers in the thickness direction z. That is, the spacing between the continuous fibers in the multiple grooves 14 is larger. Therefore, in the nonwoven fabric 10, it is possible to observe one side from the other in the thickness direction z through the spacing between the continuous fibers in the multiple grooves 14; that is, the nonwoven fabric 10 has excellent visual recognizability.

[0136] Visual recognition can be evaluated using the average transmittance obtained as shown below. First, prepare five 100mm × 100mm samples. Arrange the samples with the textured side facing up on black paper. Using a 12-megapixel digital camera, photograph the entire sample from a height of approximately 15cm to capture the entire sample. Import the obtained image into a Keyence VHX-7000 for automatic area measurement. Set the extraction method to brightness (standard), perform image processing with the settings below, and calculate the transmittance. Then, take the average transmittance of the five samples as the average transmittance of the nonwoven fabric.

[0137] Measuring area 50mm × 50mm

[0138] Filter settings: Texture removal 10

[0139] Uneven brightness removal 1

[0140] Extract brightness settings 0-148

[0141] Filling holes OFF

[0142] Small particle removal OFF

[0143] Automatic shaping and filling settings

[0144] (Manufacturing method of nonwoven fabric)

[0145] The nonwoven fabric 10 described above can be formed by spunbonding. For example, a resin composition is spun from a spinning nozzle, the spun long fiber filaments are cooled using a cooling fluid or the like, and tension is applied to the long fiber filaments using stretching air to produce continuous fibers with a predetermined fineness. The obtained continuous fibers are drawn onto the web while being drawn from below the web moving in the conveying direction MD, thereby forming a web. The intersections of the continuous fibers are thermally bonded using a hot air method that delivers hot air from one side of the web. As described above, nonwoven fabric 10 can be manufactured.

[0146] like Figure 3As shown, the wire mesh 24 has mutually orthogonal conveying directions MD, transverse directions CD, and height directions H, and includes a mesh body 28 composed of a plurality of wires 26 arranged in a mesh pattern. Each of the plurality of wires 26 has a predetermined outer diameter. The mesh body 28 is formed by arranging the plurality of wires 26 into longitudinal and transverse lines and intersecting them one by one at regular intervals.

[0147] The wire mesh 24 has a plurality of protrusions 30 that protrude from one side of the mesh body 28 in the height direction H and extend along the conveying direction MD. The protrusions 30 are arranged at predetermined intervals in the transverse direction CD. The protrusions 30 partially close the gaps between the wires 26 in the mesh body 28 arranged along the first direction x.

[0148] like Figure 4 As shown, the height H of the protrusion 30 L It can be 1.0 mm or more. Preferably, the height H of the protrusion 30 is... L The outer diameter of wire 26 is larger than that of filament 26, that is, the outer diameter of filament 26 is larger than the height H of the protrusion 30. L Small. The width W of each of the plurality of protrusions 30. L That is, the total length of the transverse direction CD can be less than 50% of the transverse direction CD length of the main body 28. The width W of each protrusion 30... L This is not limited to constant cases, but also includes some different cases. The width W of each protrusion 30... L It can be set as the average value obtained by measuring at multiple locations (e.g., 5 locations) at predetermined intervals (e.g., 100 mm) along the conveying direction MD. The width W of the protrusion 30... L Let CD be the length of the part that contacts the main body of the net in the transverse direction.

[0149] Each of the plurality of protrusions 30 may have a plurality of bulges 32 extending in the transverse direction CD. The bulges 32 are arranged at predetermined intervals along the conveying direction MD. The bulges 32 of the plurality of protrusions 30 are recessed between each other in the transverse direction CD. The plurality of bulges 32 are respectively provided on both sides of the protrusion 30, and each bulge 32 may also be provided in a position where they overlap in the transverse direction CD. When the bulges 32 are provided in a position where they overlap in the transverse direction CD, a wider portion and a narrower portion are formed between the protrusions 30 and each other. Alternatively, each bulge 32 may also be provided in a position where they do not overlap in the transverse direction CD. When the bulges 32 are provided in a position where they do not overlap in the transverse direction CD, the protrusions 30 and each other are formed with a constant width.

[0150] When the aforementioned wire mesh 24 is used, continuous fibers are attracted from the underside of the wire mesh 24 and thus accumulate on the wire mesh 24. Some of the continuous fibers preferentially aggregate between the protrusions 30 of the web body 28 that do not form protrusions 30. By preferentially aggregating some of the continuous fibers between the protrusions 30, the continuous fibers become dense, thereby forming multiple ridges 12 with a higher basis weight. In addition, on the protrusions 30, the continuous fibers become sparse, thereby forming multiple grooves 14 with a lower basis weight. Furthermore, the continuous fibers are thermally bonded while they are piled on the wire mesh 24, thereby maintaining the shape of the multiple ridges 12 and the multiple grooves 14. The nonwoven fabric is removed from the wire mesh 24, and the thickness direction z is reversed vertically, thereby obtaining... Figure 1 The nonwoven fabric 10 shown above. Therefore, the above-described method for manufacturing nonwoven fabric 10 can produce nonwoven fabric 10 that is composed of continuous fibers, has a plurality of ribs 12 and a plurality of grooves 14, and has a plurality of joints formed by thermally bonding the intersections of the continuous fibers together.

[0151] Since the height of the ribs 30 is 1.0 mm or more, continuous fibers are less likely to remain on the ribs 30. Because continuous fibers are gathered between the ribs 30, multiple ridges 12 with a predetermined thickness can be formed. Therefore, the above-described method for manufacturing the nonwoven fabric 10 can more reliably manufacture a nonwoven fabric 10 having ridges 12 and grooves 14. Since the continuous fibers are gathered between the ribs 30 in a manner that avoids the ribs 30, the fiber orientation of the multiple ridges 12 along the first direction x is higher than that of the multiple grooves 14 along the first direction x.

[0152] The total length of the cross-sectional direction CD of each of the multiple protrusions 30 is less than 50% of the length of the cross-sectional direction CD of the web body 28, thus allowing sufficient air permeability for the web body 28 excluding the protrusions 30. Therefore, the above-described method for manufacturing the nonwoven fabric 10 enables the continuous fibers to be stably stacked on the web 24, thereby enabling the more reliable manufacture of the nonwoven fabric 10 having multiple ridges 12 and multiple grooves 14.

[0153] The multiple ribs 30 each have multiple bulges 32 extending in the transverse direction CD, causing the continuous fibers in the bulges 32 to become sparse. Between the bulges 32 in the first direction x, the continuous fibers become denser, forming protrusions 22 protruding from the multiple ridges 12 to the multiple grooves 14. Therefore, the above manufacturing method can produce a nonwoven fabric 10 with protrusions 22 in the multiple ridges 12.

[0154] Since the outer diameter of the filaments 26 forming the mesh 24 is smaller than the height of the ribs 30, even in the overlapping portions of the filaments 26 of the mesh 24, the ribs 30 are higher than the filaments 26, thus forming multiple grooves 14. Therefore, the above-described method for manufacturing the nonwoven fabric 10 can more reliably produce a nonwoven fabric 10 having multiple ribs 12 and multiple grooves 14. In addition, since the overlapping portions of the filaments 26 of the mesh 24 are smaller than the ribs 30, continuous fibers are less likely to accumulate in the overlapping portions of the filaments 26 of the mesh 24, but instead gather in the mesh, thereby forming multiple ribs 12 with recesses 16.

[0155] Furthermore, when the continuous fibers are gathered on the mesh 24 between the protrusions 30, they avoid the portions of the filaments 26 that overlap each other and protrude upwards in the height direction, thus forming a state in which multiple continuous fibers are oriented in the first direction x. By forming a joint in this state, a bundle of multiple continuous fibers oriented in the transport direction MD, i.e., the first direction x, is formed.

[0156] Preferably, the continuous fibers are deposited on the wire mesh 24 at a fiber speed of 1000 m / min or more and 4500 m / min or less. By setting the fiber speed of the continuous fibers to 1000 m / min or more, the continuous fibers are easily deposited on the wire mesh 24, making it easier to form multiple ridges 12. Furthermore, by setting the fiber speed of the continuous fibers to 4500 m / min or less, it is possible to suppress the orientation disorder of the continuous fibers on the wire mesh 24, thus making it easier to form multiple ridges 12. Therefore, by keeping the continuous fibers within the above range, it is possible to efficiently manufacture a nonwoven fabric 10 having multiple ridges 12 and multiple grooves 14.

[0157] (Examples of absorbent items)

[0158] Figure 5The absorbent article 1 shown is an example of a disposable diaper, comprising multiple layers. The absorbent article 1 includes: a liquid-permeable sheet 3 serving as a skin-contact sheet that comes into contact with the wearer's skin; a liquid-impermeable sheet 5; and an absorbent body 7 disposed between the liquid-permeable sheet 3 and the liquid-impermeable sheet 5. The absorbent article 1 may also have an outer sheet (not shown) on the non-skin side of the liquid-impermeable sheet 5. Additionally, the absorbent article may have an indicator (not shown) and a pattern (not shown). The indicator is preferably disposed between the absorbent body 7 and the liquid-impermeable sheet 5. The pattern is preferably disposed on the inner or outer surface of the liquid-impermeable sheet 5. The absorbent article 1 is divided along its length L into three regions: a front waist region FW, a back waist region RW, and a crotch region C between the front waist region FW and the back waist region RW. The absorbent article 1 also includes: a pair of leak-proof walls 101, each including an elastic member 103; a fixing part 105 that fixes the leak-proof wall 101 to the liquid-permeable sheet 3; an elastic member 107 around the legs; and hook and loop fasteners 109, etc. Furthermore, these components are well known in the art and therefore description is omitted.

[0159] The liquid-permeable sheet 3 can be the aforementioned nonwoven fabric 10. The nonwoven fabric 10 used in the liquid-permeable sheet 3 is liquid-permeable. In the liquid-permeable sheet 3, the side of the nonwoven fabric 10 with multiple ridges 12 and multiple grooves 14 is positioned on the skin side. In the liquid-permeable sheet 3, the first direction x of the nonwoven fabric 10 can also be arranged along the length direction L of the absorbent article 1. In the liquid-permeable sheet 3, since the multiple grooves 14 and multiple ridges 12 are arranged along the length direction L of the absorbent article 1, body fluids easily diffuse into the length direction L of the absorbent article 1.

[0160] Furthermore, in the liquid-permeable sheet 3, the first direction x of the nonwoven fabric 10 can be arranged along the width direction W of the absorbent article 1. In the liquid-permeable sheet 3, since the plurality of grooves 14 and the plurality of ridges 12 are arranged along the width direction W of the absorbent article 1, body fluids can easily diffuse into the width direction W of the absorbent article 1.

[0161] The outer covering sheet can also be the aforementioned nonwoven fabric 10. The outer covering sheet can be the side of the nonwoven fabric 10 with multiple ridges 12 and multiple grooves 14 on the non-skin side, or it can be the side of the nonwoven fabric 10 with multiple ridges 12 and multiple grooves 14 on the skin side. The outer covering sheet can be configured either along the length direction L of the absorbent article 1 in its first direction x, or along the width direction W of the absorbent article 1 in its first direction x.

[0162] In the nonwoven fabric 10, due to the small change in thickness, it is easy to maintain the shape of the multiple ribs 12 and the multiple grooves 14. In the nonwoven fabric 10, when a load in the thickness direction z is applied after wearing, the multiple ribs 12 are not easily thinned, and the length of the multiple grooves 14 in the second direction y can be maintained with a small basis weight.

[0163] Absorbent materials are not limited to disposable diapers. For example, they can be used in urination pads, animal urination pads, etc., and absorbent materials that mainly absorb menstrual blood, such as sanitary napkins and panty liners.

[0164] (Functions and Effects)

[0165] The nonwoven fabric 10 is composed of continuous fibers, and each of the plurality of ridges 12 and each of the plurality of grooves 14 has a plurality of joints formed by thermally bonding the intersections of the continuous fibers together. This nonwoven fabric 10 easily maintains its shape, and its thickness variation under a load applied in the thickness direction z is smaller than that of a nonwoven fabric 10 composed of short fibers. For example, under a load of 0.05 kPa (0.5 gf / cm²), it is more resistant to stress. 2 The thickness is set to T0 under pressure of 4.9 kPa (50 gf / cm). 2 When the thickness under pressure is set to Tm, the compression characteristic (Tm / T0) of the nonwoven fabric 10 is greater than 0.3 or 0.4 or higher. Therefore, the nonwoven fabric 10 is less prone to thinning; for example, in the case of the liquid-permeable sheet 3 used in disposable diapers, the change in thickness during wear is small, thus easily maintaining a gap between the absorbent material 7 and the user's skin. As a result, the nonwoven fabric 10 exhibits excellent suppression of wetness.

[0166] Thickness T0 and thickness Tm were measured using an automated compression tester KES-FB3-A manufactured by Kado Technology Co., Ltd. The measurement conditions are shown below.

[0167] SENS: 2

[0168] Speed: 0.02 mm / s

[0169] Stroke: 5mm / 10V

[0170] Pressurized area: 2cm 2

[0171] Import interval: 0.1 seconds

[0172] Upper limit load: 50g / cm 2

[0173] Number of repetitions: 1

[0174] The basis weight of the multiple grooves 14 is lower than that of the multiple ribs 12. Furthermore, they have multiple joints formed by thermally bonding the intersections of continuous fibers, thus easily maintaining their shape. Therefore, the thickness of the ribs 12 is less prone to change when a load is applied in the thickness direction z. Consequently, the length of the ribs 12 in the second direction y is also less prone to change, and therefore the length of the grooves 14 in the second direction y is less prone to change. In other words, in the nonwoven fabric 10 described above, the structure of the ribs 12 and the grooves 14 is less prone to change, and the length of the grooves 14 in the second direction y is less prone to change, thus the range of visual recognizability is less prone to change. Therefore, for the multiple grooves 14, the visual recognizability in the thickness direction z of the multiple grooves 14 is excellent. Because this nonwoven fabric 10 has multiple grooves 14, for example, in the case of a liquid-permeable sheet 3 applied to a disposable diaper, the visual recognizability of the body fluid absorbed by the absorbent 7 is excellent.

[0175] In the nonwoven fabric 10, multiple ridges 12 and multiple grooves 14 are alternately arranged in the second direction y, thereby maintaining a gap between the absorbent body 7 and the user's skin over a large range in the first direction x and the second direction y, resulting in excellent suppression of the feeling of moisture, and excellent visual recognition of the body fluid absorbed by the absorbent body 7 through the multiple grooves 14.

[0176] For the nonwoven fabric 10, when a load is applied in the thickness direction z after wearing, the multiple ridges 12 are not easily deformed, and the length of the multiple grooves 14 in the second direction y can be maintained with a low basis weight. For this nonwoven fabric 10, for example, when it is applied to the outer cover of a disposable diaper and the side with the multiple ridges 12 and multiple grooves 14 is positioned on the non-skin side, even when subjected to load over time after wearing, the multiple grooves 14 can maintain excellent breathability and visual visibility. Therefore, the absorbent article 1 can obtain excellent breathability after wearing, and the above-mentioned indicator and the pattern provided on the liquid-impermeable sheet 5 can be clearly seen from the outer cover side. In addition, when the nonwoven fabric 10 is applied to the outer cover and the side with the multiple ridges 12 and multiple grooves 14 is positioned on the skin side, a space is formed between the nonwoven fabric 10 and the liquid-impermeable sheet 5, thus preventing moisture from easily passing to clothing, sheets, etc.

[0177] In the aforementioned nonwoven fabric 10, multiple grooves 14 are provided, and multiple recesses 16 recessed along the thickness direction z are provided in the multiple ridges 12. Therefore, the area of ​​contact between the user's skin and the moist nonwoven fabric 10 is smaller than that of a nonwoven fabric 10 without recesses 16. In the aforementioned nonwoven fabric 10, for example, in the case of a liquid-permeable sheet 3 applied to a disposable diaper, the base 18 absorbs excreted bodily fluids and more reliably prevents the bodily fluids absorbed by the absorbent 7 from returning to the recesses 16. Therefore, the nonwoven fabric 10 has excellent suppression of wetness. In addition, in the aforementioned nonwoven fabric 10, for example, in the case of an outer sheet applied to a disposable diaper, the side with multiple ridges 12 and multiple grooves 14 can be positioned on the non-skin side. In this case, the contact area of ​​the surface of the nonwoven fabric 10 is correspondingly reduced compared to the case with recesses 16, thus providing a refreshing touch and having a complex fabric-like surface shape. In addition, in the nonwoven fabric 10 described above, the side with multiple ridges 12 and multiple grooves 14 can be positioned on the skin side. In this case, the space formed between the nonwoven fabric 10 and the liquid-impermeable sheet 5 and the recessed portion are further increased accordingly, making it more difficult for moisture to be transmitted to clothing, sheets, etc.

[0178] In the aforementioned nonwoven fabric 10, each of the plurality of ridges 12 has a bundle-like portion 20 formed by multiple joints joining continuous fibers in a state oriented along the first direction x on at least a partial side of the plurality of recesses 16 in the second direction y. In the bundle-like portion 20, the spacing between the continuous fibers is small, making it less prone to deformation under load. Therefore, in the aforementioned nonwoven fabric 10 with the bundle-like portion 20, the thickness variation during wear is small, and the shape of the recesses is easily maintained. In the aforementioned nonwoven fabric 10, for example, in the case of a liquid-permeable sheet 3 applied to disposable diapers, it is easy to maintain a gap between the absorbent body 7 and the user's skin, and it is also easy to maintain the shape of the recesses 16, thus easily maintaining a small contact area of ​​the nonwoven fabric 10.

[0179] In the aforementioned nonwoven fabric 10, the thickness of each of the plurality of grooves 14 is thinner than the thickness of the base 18. Therefore, for example, in the case of application to the liquid-permeable sheet 3 or outer sheet of disposable diapers, the visual distinguishability of the plurality of grooves 14 in the thickness direction z is excellent, thus the difference from the plurality of ridges 12, which have almost no visual distinguishability in the thickness direction z, is more prominent. Therefore, the aforementioned nonwoven fabric 10 has excellent visual distinguishability. In addition, since the aforementioned nonwoven fabric 10 is composed of continuous fibers and has a predetermined average breaking strength per average basis weight, it can be used as a liquid-permeable sheet 3 and outer sheet with excellent visual distinguishability in absorbent articles 1.

[0180] Since continuous fibers are composite fibers containing olefin resins, they can form joints even at lower heat treatment temperatures, thus enabling more efficient formation of joints throughout the nonwoven fabric 10. Because the nonwoven fabric 10 has joints integrally formed, it easily maintains its shape when subjected to load in the thickness direction z after wear, thus minimizing changes in the structure of the ribs 12 and grooves 14. The nonwoven fabric 10 with integrally formed joints maintains the shape of the grooves 14, resulting in excellent visual recognizability and suppressing deformation of multiple grooves 14 and multiple ribs 12 due to excrement, thus exhibiting excellent suppression of wettability.

[0181] In the aforementioned nonwoven fabric 10, the average fiber diameter of the continuous fibers is 15 μm or more and 30 μm or less, and the average basis weight of the nonwoven fabric 10 is 10 g / m³. 2 Above and 40g / m 2 Therefore, the structure of the ridge portion 12 and the groove portion 14, which easily maintain their shape when a load is applied in the thickness direction z after wearing, can be obtained more reliably. Furthermore, after absorbing excreted bodily fluids, the continuous fibers can maintain a gap between each other. Therefore, in the case of the nonwoven fabric 10, for example, when applied to the liquid-permeable sheet 3 of a disposable diaper, the gap between the absorbent body 7 and the user's skin is maintained, resulting in excellent suppression of wetness, and the visual visibility of the bodily fluids absorbed by the absorbent body 7 is excellent.

[0182] In the aforementioned nonwoven fabric 10, multiple grooves 14 and multiple ridges 12 are arranged along the length direction L of the absorbent article 1, thus providing excellent visual visibility along the length direction L. Furthermore, in the aforementioned nonwoven fabric 10, bodily fluids readily diffuse along the length direction L of the absorbent article 1. Therefore, when the aforementioned nonwoven fabric 10 is applied to the liquid-permeable sheet 3, by causing bodily fluids to diffuse along the length direction L, the retention of bodily fluids in one place is suppressed, resulting in excellent suppression of wetting sensation.

[0183] In the aforementioned nonwoven fabric 10, multiple grooves 14 and multiple ridges 12 are arranged along the width direction W of the absorbent article 1, thus providing excellent visual visibility in the width direction W. Furthermore, in the aforementioned nonwoven fabric 10, bodily fluids readily diffuse into the width direction W of the absorbent article 1. Therefore, when the aforementioned nonwoven fabric 10 is applied to the liquid-permeable sheet 3, by causing bodily fluids to diffuse into the width direction W, the retention of bodily fluids in one place is suppressed, resulting in excellent suppression of wetting sensation.

[0184] In the aforementioned nonwoven fabric 10, each of the plurality of ridges 12 has a plurality of protrusions 22 that protrude toward each of the plurality of adjacent grooves 14 and are spaced apart along the first direction x. Therefore, when a load is applied in the thickness direction z, the plurality of ridges 12 are not prone to tipping over. Thus, when this nonwoven fabric 10 is used, for example, in the case of a liquid-permeable sheet 3 or an outer sheet for disposable diapers, it is easy to maintain the shape of the plurality of ridges 12, so that the plurality of ridges 12 will not close the grooves 14, resulting in excellent visual recognizability.

[0185] In the aforementioned nonwoven fabric 10, the fiber orientation of the plurality of ridges 12 along the first direction x is higher than that of the plurality of grooves 14 along the first direction x. Therefore, the distance between the intersection points of continuous fibers and the distance between the plurality of joints are shorter. Consequently, the shape of the plurality of ridges 12 is easily maintained in the aforementioned nonwoven fabric 10. Furthermore, bodily fluids can diffuse along the plurality of ridges 12 in the first direction x. Therefore, in the aforementioned nonwoven fabric 10, by allowing bodily fluids to diffuse in the first direction Lx, the retention of bodily fluids in one place is suppressed, resulting in excellent suppression of wetting sensation. Additionally, in the aforementioned nonwoven fabric 10, the higher fiber orientation of the plurality of ridges 12 along the first direction x leads to shorter distances between the intersection points of continuous fibers and shorter distances between the plurality of joints, thus making it easier to maintain the shape. Therefore, the aforementioned nonwoven fabric 10 is less prone to deformation in the thickness direction z.

[0186] The aforementioned nonwoven fabric 10 is a spunbond nonwoven fabric. Therefore, when the continuous fibers move through the airflow, due to their relatively long length, they move over a certain length, causing adjacent continuous fibers to move as well. Consequently, they are easily affected by the airflow during the stacking process. Thus, by moving the continuous fibers individually, it is easy to form portions with smaller fiber spacing. The distance between the intersections of the continuous fibers is short, and the distance between multiple joints is also short. Therefore, in the aforementioned nonwoven fabric 10, it is easy to maintain the shape of the multiple ribs 12.

[0187] The nonwoven fabric 10 is not easily deformed when subjected to load, and its thickness changes little even after the load is removed. The change in thickness before and after the load is applied is measured as described below.

[0188] First, a roll of nonwoven fabric 10 is made. Nonwoven fabric 10 is then cut from this roll. The cut fabric is then subjected to a load of 0.3 kPa (3 gf / cm). 2 The thickness of the nonwoven fabric under load is set as T1. The cut nonwoven fabric 10 is left to stand for one day at a temperature of 23 degrees Celsius and a humidity of 60%, and then subjected to a load of 0.3 kPa (3 gf / cm). 2The thickness of the nonwoven fabric 10 under load is set to T2. The thickness recovery (T2 / T1) of the nonwoven fabric 10 is less than 1.1, with almost no change in thickness. Therefore, even after the load is removed, the change in thickness is minimal, and the upper and lower sides of the thickness direction z of the nonwoven fabric 10 are less likely to shift towards the planar direction, thus maintaining good visual recognizability.

[0189] Example

[0190] The nonwoven fabrics corresponding to the above-described embodiments were actually produced and evaluated. The following examples illustrate the present invention, but the invention is not limited to these examples.

[0191] (1) Sample

[0192] (Examples 1-3)

[0193] According to the above description of "Method for Manufacturing Nonwoven Fabrics," nonwoven fabrics of Examples 1 to 3, composed of continuous fibers, were produced using a spunbond method. All nonwoven fabrics of Examples 1 to 3 have multiple ridges, multiple grooves, multiple recesses, and multiple protrusions. A photograph of the nonwoven fabric of Example 1 is shown below. Figure 6A , Figure 6B , Figure 6C , Figure 6D .exist Figure 6A and Figure 6B An ellipse is shown, but the ellipse represents a specific area and does not constitute nonwoven fabric. For example... Figure 6A and Figure 6B As shown, multiple recesses are formed in multiple ridges, and bundle-like portions are formed adjacent to the recesses. For example... Figure 6C As shown, in the bundle portion, multiple continuous fibers are oriented along the first direction and joined by multiple junctions. Figure 6D As shown, the thickness of multiple grooves is thinner than the thickness of the base.

[0194] (Compare Examples 1 and 2)

[0195] Nonwoven fabrics of Comparative Examples 1 and 2, composed of short fibers, were produced using a carding method. In the nonwoven fabric of Comparative Example 1, high and low weight-per-unit area portions were formed according to the method described in Patent Document 1. In the nonwoven fabric of Comparative Example 2, multiple grooves were formed using a hot embossing process. The basis weight of the multiple grooves and the ridges between the multiple grooves in Comparative Example 2 is the same. The nonwoven fabrics of Comparative Examples 1 and 2 do not have recesses or protrusions.

[0196] (Evaluation Results)

[0197] The properties of the nonwoven fabrics of the embodiments and comparative examples are shown in Table 1.

[0198] For withstanding 0.3 kPa (3 gf / cm) 2The thickness T1 of the nonwoven fabrics under load in Examples 1-3 is greater than that in Comparative Examples 1 and 2, which have the same average basis weight. The thickness recovery (T2 / T1) of Examples 1-3 is 1.0, while that of Comparative Examples 1 and 2 is 1.1 or higher. It was confirmed that the thickness change of the nonwoven fabrics in the examples before and after applying load is small. In the nonwoven fabrics of the examples, since the thickness change before and after applying load is small, the upper and lower sides of the nonwoven fabric in the thickness direction are not easily shifted in the planar direction, and it can be said that good visual recognizability is easily maintained.

[0199] The compression characteristics (Tm / T0) of Examples 1-3 are 0.4 or higher, while those of Comparative Examples 1 and 2 are 0.3. In the nonwoven fabrics of the Examples, the thickness change under a load in the thickness direction is smaller than that of nonwoven fabrics composed of short fibers. Therefore, the nonwoven fabrics of the Examples are less prone to thinning, and when applied to the liquid-permeable sheet of disposable diapers, the thickness change during wear is small, thus easily maintaining a gap between the absorbent and the user's skin, resulting in excellent suppression of moisture.

[0200] The nonwoven fabric of the embodiment achieved a superior average transmittance compared to the comparative example. The nonwoven fabric of the embodiment has multiple joints formed by thermally bonding the intersections of continuous fibers, thus easily maintaining its shape and the length of the groove in the second direction. Therefore, it can be said that the nonwoven fabric has a higher average transmittance, which means it easily maintains excellent visual recognizability.

[0201] [Table 1]

[0202]

[0203] Explanation of reference numerals in the attached figures

[0204] 1. Absorbent material; 3. Liquid-permeable sheet; 7. Absorbent body; 10. Nonwoven fabric; 12. Rib; 16. Concave portion; 18. Base; 20. Bundle portion; 22. Protrusion; 24. Mesh; 26. Thread; 28. Mesh body; 30. Strip; 32. Bulging portion.

Claims

1. A nonwoven fabric, which is a nonwoven fabric for an absorbent article, has a first direction, a second direction, and a thickness direction that are orthogonal to each other, and is composed of continuous fibers, wherein the nonwoven fabric comprises: a plurality of ridge portions that extend along the first direction; and a plurality of groove portions that extend along the first direction and have a basis weight lower than that of the plurality of ridge portions, each of the ridge portions and each of the groove portions are alternately arranged in the second direction, each of the ridge portions and each of the groove portions have a plurality of junction portions in which the continuous fibers are thermally joined to each other at intersections thereof, each of the ridge portions has a plurality of recessed portions recessed in the thickness direction, and each of the plurality of recessed portions has a base portion composed of the continuous fibers at a bottom portion thereof.

2. The nonwoven fabric according to claim 1, wherein the nonwoven fabric is used as a liquid-permeable sheet for the absorbent article.

3. The nonwoven fabric according to claim 1, wherein the nonwoven fabric is used as an outer cover sheet for the absorbent article.

4. The nonwoven fabric according to any one of claims 1 to 3, wherein each of the ridge portions has a bundle-shaped portion on one side of the second direction of at least a part of the plurality of recessed portions, the bundle-shaped portion being joined by the continuous fibers in a state of being oriented along the first direction by the plurality of junction portions.

5. The nonwoven fabric according to any one of claims 1 to 3, wherein a thickness of each of the groove portions is thinner than a thickness of the base portion.

6. The nonwoven fabric according to any one of claims 1 to 3, wherein the continuous fibers are composite fibers containing an olefin-based resin.

7. The nonwoven fabric according to any one of claims 1 to 3, wherein 8. The nonwoven fabric according to any one of claims 1 to 3, wherein the first direction is arranged in a length direction of the absorbent article.

9. The nonwoven fabric according to any one of claims 1 to 3, wherein the first direction is arranged in a width direction of the absorbent article.

10. The nonwoven fabric according to any one of claims 1 to 3, wherein each of the ridge portions has a plurality of protruding portions protruding toward each of the adjacent groove portions and arranged at intervals along the first direction.

11. The nonwoven fabric according to any one of claims 1 to 3, wherein a fiber orientation along the first direction of each of the ridge portions is higher than a fiber orientation along the first direction of each of the groove portions.

12. The nonwoven fabric according to any one of claims 1 to 3, wherein the nonwoven fabric is a spunbond nonwoven fabric.

13. A method of manufacturing a nonwoven fabric, which is a method of manufacturing the nonwoven fabric according to any one of claims 1 to 12, wherein the method of manufacturing the nonwoven fabric comprises the following steps: suctioning continuous fibers from a lower side of a wire net having a conveying direction, a transverse direction, and a height direction that are orthogonal to each other, while stacking the continuous fibers on the wire net; and thermally joining the continuous fibers stacked on the wire net to each other, the wire net having: ​ ​ ​ ​ ​ The average fiber diameter of the continuous fibers is 15 μm or more and 30 μm or less, and the average basis weight of the nonwoven fabric is 10 g / m 2 40 g / m 2 or more and 40 g / m ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ A web body; And A plurality of protrusions extending in the conveyance direction, arranged at predetermined intervals on the web body in the cross direction, and protruding in the height direction.

14. The nonwoven fabric manufacturing method according to claim 13, wherein The height of the protrusions is 1.0 mm or more.

15. The nonwoven fabric manufacturing method according to claim 13 or 14, wherein The proportion of the total length of the respective cross direction lengths of the plurality of protrusions with respect to the length of the web body in the cross direction is 50% or less.

16. The nonwoven fabric manufacturing method according to claim 13 or 14, wherein The plurality of protrusions each have a plurality of bulges bulging in the cross direction.

17. The nonwoven fabric manufacturing method according to claim 13 or 14, wherein The wire diameter of the wire forming the wire mesh is smaller than the height of the protrusions.

18. The nonwoven fabric manufacturing method according to claim 13 or 14, wherein The continuous fibers are accumulated on the wire mesh at a fiber speed of 1000 m / min or more and 4500 m / min or less.

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