absorbent material

Abstract

The present invention provides an absorbent article which does not readily twist even when wet, and which exhibits excellent comfort when worn. This absorbent article includes a liquid-absorbing absorption layer, and has a longitudinal direction, a width direction, and a thickness direction which are orthogonal to each other. The absorption layer is provided with an uneven structure (20) having, alternately arranged therein along the longitudinal direction, protrusions (21) which protrude towards the skin-facing surface side of the absorbent article in the thickness direction, and which continuously extend in a direction intersecting the longitudinal direction, and recesses (22) which sink towards the non-skin-facing surface side of the absorbent article in the thickness direction, and which continuously extend in parallel with the protrusions (21). The protrusions (21) are provided with cavities (23) which face the surface of the absorption layer at the non-skin-facing surface side.

Description

Absorbent articles This invention relates to absorbent articles such as panty liners, light incontinence pads, and sanitary napkins. Traditionally, absorbent products such as panty liners, light incontinence pads, and sanitary napkins have been required to rapidly absorb liquid excretions such as urine and menstrual blood and retain them to prevent leakage. In recent years, however, in addition to these capabilities, there has been a growing demand for products that are flexible and fit well to the wearer's body. For example, Patent Document 1 discloses an absorbent article having a groove of a specific structure in which the surface sheet and absorbent material are integrally recessed. According to the absorbent article disclosed in Patent Document 1, it is possible to quickly absorb and diffuse excretory fluids, eliminate discomfort caused by wetting the wearer, and despite having a leak-proof groove, it has appropriate flexibility and provides an excellent fit. Patent Document 2 also discloses an absorbent article in which a plurality of recessed embossings are applied to specific positions on the absorbent material. According to the absorbent article disclosed in Patent Document 2, it is possible to fit the curves of the body without discomfort and reduce leakage of bodily fluids. Japanese Patent Publication No. 2012-245130 Japanese Patent Publication No. 2008-73449 Although the absorbent article disclosed in Patent Document 1 is said to have excellent flexibility, etc., the absorption material has grooves of the above-mentioned specific structure formed on it, which reduces the strength of the absorbent material when wet (wet strength). Therefore, when the absorbent material absorbs liquid excretions such as urine or menstrual blood, the force (crotch constriction force) F exerted from both legs of the wearer in the width direction of the absorbent article becomes excessive. Ｗ This made the material prone to being crushed in the width direction, and as a result, there was a risk that the absorbent material would be crushed in the width direction, causing the warping shown in Figure 3. On the other hand, the absorbent article disclosed in Patent Document 2 has multiple concave embossed surfaces on the absorbent material, resulting in high wet strength of the absorbent material and making it less prone to the aforementioned creasing even when absorbing liquid excrement. However, because the concave embossing itself is hard, there was a risk of deterioration in wearing comfort, such as a decrease in the feel of the surface where the concave embossing is exposed or the wearer feeling discomfort. Thus, with conventional absorbent materials, it has been difficult to achieve both resistance to creasing (especially when wet) and a good wearing comfort. Therefore, the present invention aims to provide an absorbent article that is less prone to creasing even when wet and offers excellent wearability. One aspect of the present invention (Aspect 1) is an absorbent article comprising an absorbent layer having liquid-absorbing properties, having longitudinal, width, and thickness directions that are mutually orthogonal, wherein the absorbent layer has an uneven structure in which protrusions that project toward the skin-facing side of the absorbent article in the thickness direction and extend continuously in a direction intersecting the longitudinal direction, and recesses that recess toward the non-skin-facing side of the absorbent article in the thickness direction and extend continuously parallel to the protrusions, are alternately arranged along the longitudinal direction, and the protrusions have cavities that the non-skin-facing surface of the absorbent layer faces. The absorbent article of this embodiment 1 has an absorbent layer that has the above-mentioned specific uneven structure (i.e., an uneven structure in which the cross-sectional shape along the longitudinal direction of the absorbent article is corrugated) that extends in a direction intersecting the longitudinal direction of the absorbent article. As a result, the compressive strength in the direction in which the uneven structure extends (i.e., the direction intersecting the longitudinal direction of the absorbent article) is high, and the force applied from both legs of the wearer can be distributed in the thickness direction by the convex and concave parts of the above-mentioned uneven structure. Therefore, the absorbent article of this embodiment can maintain a certain strength (especially the compressive strength in the direction intersecting the longitudinal direction of the absorbent article) even when wet, and is less prone to warping. Furthermore, the aforementioned uneven structure can provide the absorbent layer with appropriate flexibility (specifically, ease of bending in the longitudinal direction, cushioning in the thickness direction, etc.) and a good feel against the skin. Therefore, the absorbent article of this embodiment can provide the wearer with an excellent wearing experience due to such appropriate flexibility and a good feel against the skin. Therefore, the absorbent article of this embodiment can achieve both resistance to creasing (especially resistance to creasing when wet) and a good wearing comfort, which was difficult with conventional absorbent articles. Furthermore, in another aspect of the present invention (Aspect 2), in the absorbent article of Aspect 1, the direction intersecting the longitudinal direction is the width direction of the absorbent article. In this embodiment 2, the absorbent article has the aforementioned uneven structure extending in the width direction of the absorbent article, where the force transmitted from the wearer's legs is strongest, among the directions intersecting the longitudinal direction as described above. Therefore, the absorbent article in this embodiment is even less prone to the aforementioned twisting. Furthermore, in another aspect of the present invention (Aspect 3), in the absorbent article of Aspect 1 or 2, in the thickness direction of the absorbent article, at least one of the skin-facing side and the non-skin-facing side of the absorbent layer is provided with a low-absorbent layer that has lower liquid absorption than the absorbent layer, and the absorbent layer and the low-absorbent layer are joined together. Generally, absorbent layers tend to lose strength (i.e., have low wet strength) when they absorb liquid excretions such as urine from the wearer due to their absorbency. However, in the absorbent article of this embodiment, a low-absorbent layer with lower absorbency (i.e., relatively higher wet strength) than the absorbent layer is bonded to at least one of the skin-facing side and the non-skin-facing side of the absorbent layer, which tends to lose strength when wet, in the thickness direction. As a result, the strength (especially wet strength) of the absorbent layer is reinforced, making it easier to maintain a certain level of strength even when wet, and further reducing the likelihood of the aforementioned creasing. Furthermore, in another aspect of the present invention (Aspect 4), in the absorbent article of Aspect 3, the low-absorption layer is a layer with a greater thickness than the absorption layer. In this embodiment 4, the absorbent article has a lower absorbency layer that is thicker than the absorbency layer, and the force applied from the wearer's legs can be distributed in the thickness direction even in the lower absorbency layer. Therefore, the absorbent article in this embodiment is even less prone to twisting in the direction intersecting the longitudinal direction. Furthermore, as mentioned above, the low-absorption layer is a layer with relatively high strength when wet, making it less prone to the aforementioned creasing, especially when absorbent materials are wet. Furthermore, in another aspect of the present invention (Aspect 5), in the absorbent article of Aspect 3 or 4, the low-absorption layer contains heat-fusible fibers and has a plurality of fused portions formed by the fusion of the heat-fusible fibers with each other, and the absorbent layer does not contain heat-fusible fibers or contains fewer heat-fusible fibers than the low-absorption layer. In this embodiment 5, the absorbent article has high rigidity and high compressive strength in the direction intersecting the longitudinal direction (especially when wet) because the low-absorbent layer contains heat-fusible fibers and has multiple fused portions where the heat-fusible fibers are fused to each other. In contrast, the absorbent layer does not contain heat-fusible fibers, or if it does, it contains them in a smaller amount (mass ratio) than the low-absorbent layer. As a result, the fused portions between the heat-fusible fibers are absent in the absorbent layer or fewer in number than in the low-absorbent layer. Therefore, the absorbent article in this embodiment is even less prone to twisting (especially when wet) due to the low-absorbent layer, and the absorbent layer makes it easier to ensure appropriate flexibility and a good feel against the skin. Therefore, the absorbent article of this embodiment can more reliably achieve both the aforementioned resistance to creasing (especially resistance to creasing when wet) and a good wearing comfort. Furthermore, in another aspect of the present invention (Aspect 6), in the absorbent article of any of aspects 3 to 5, the low-absorbent layer is made of an air-through nonwoven fabric, and the air-through nonwoven fabric is arranged on the non-skin-facing side of the absorbent layer in the thickness direction of the absorbent article. In this embodiment 6, the absorbent article is configured such that the low-absorbent layer is made of an air-through nonwoven fabric that is particularly good at maintaining wet strength, and furthermore, the air-through nonwoven fabric is positioned on the non-skin-facing side of the absorbent layer in the thickness direction of the absorbent article. As a result, liquid excretions such as urine can be quickly absorbed into the absorbent layer, and the absorbent layer is reinforced by the air-through nonwoven fabric, which can more reliably maintain the wet strength of the absorbent article, and consequently more reliably prevent the aforementioned twisting (especially when wet). Furthermore, in another aspect of the present invention (Aspect 7), in the absorbent article of Aspect 1 or 2, the absorbent article does not include a liquid-absorbing layer other than the absorbent layer described above. In this embodiment 7, the absorbent article does not include, in addition to the absorbent layer described above, a liquid-absorbing layer that tends to lose strength when wet, making it easier to maintain wet strength as an absorbent article. Therefore, the absorbent article of this embodiment can more reliably achieve both resistance to creasing, especially when wet, and a good wearing comfort. Furthermore, in another aspect of the present invention (Aspect 8), in the absorbent article of any of the above aspects 1 to 7, the absorbent layer is a surface sheet. In this embodiment 8, since the absorbent article has an absorbent layer as a surface sheet, liquid excretions such as urine excreted from the wearer can be quickly absorbed and retained by the absorbent surface sheet. Furthermore, there is no need to provide a separate absorbent body (or if a separate absorbent body is provided, a thin absorbent body is sufficient), so the absorbent article can be made thinner overall, resulting in even greater flexibility and wearing comfort. According to the present invention, it is possible to achieve both resistance to creasing (especially when wet) and a good wearing comfort, which has been difficult with conventional absorbent articles. Figure 1 is a partially broken perspective view of a panty liner 1 according to one embodiment of the present invention. Figure 2 is a partially cross-sectional view of a panty liner 1 according to one embodiment of the present invention along the line II-II in Figure 1. Figure 3 shows the crotch tightening force F of a conventional panty liner 1'. Ｗ This is a schematic plan view showing the state in which the material is compressed and warped in the width direction. Hereinafter, preferred embodiments of the absorbent article of the present invention will be described in detail with reference to the drawings. In this specification, unless otherwise specified, "viewing an object (e.g., an absorbent article, absorbent material, etc.) placed on a horizontal surface in an unfolded state from the vertically upward side (the surface sheet side in the case of an absorbent article) in the direction of the thickness of the object" is simply referred to as "planar view." Furthermore, unless otherwise specified, the various directions and other terms used in this specification are as follows: In this specification, "width direction" refers to "the shorter direction of the length of a vertically elongated object in a plan view (short side direction)," "long side direction" refers to "the longer direction of the length of a vertically elongated object in a plan view," and "thickness direction" refers to "the direction perpendicular to the object when it is placed on a horizontal surface in an unfolded state." These width direction, long side direction, and thickness direction are all orthogonal to each other. Furthermore, in this specification, unless otherwise specified, in the thickness direction of an absorbent article, the side that is "proximal to the wearer's skin when the absorbent article is worn" is referred to as the "skin-facing side," and the side that is "distal to the wearer's skin when the absorbent article is worn" is referred to as the "non-skin-facing side." Figure 1 is a partially broken perspective view of a panty liner 1 (absorbent article) according to one embodiment of the present invention, and Figure 2 is a partially cross-sectional view of the panty liner 1 along the line II-II in Figure 1. Figure 3 shows the crotch tightening force F of a conventional panty liner 1'. Ｗ This is a schematic plan view showing the state in which the material is compressed and warped in the width direction. A panty liner 1 according to one embodiment of the present invention has, in plan view, an external shape that is elongated in the longitudinal direction L, and furthermore, has a roughly oval shape with the outer edge of the approximately central part in the longitudinal direction L slightly narrowed in the width direction W. In this invention, the external shape of the absorbent article is not particularly limited, and any shape (for example, rectangular, elliptical, gourd-shaped, etc.) can be adopted depending on the various applications, as long as the length dimension in the longitudinal direction L is longer than the width dimension in the width direction W. As shown in Figures 1 and 2, the panty liner 1 according to this embodiment comprises, in the thickness direction T, a surface sheet 2 made of an absorbent sheet located on the side facing the wearer's skin and having a specific uneven structure 20, a back sheet 3 made of a liquid-impermeable sheet located on the side not facing the wearer's skin, and a low-absorbency sheet 4 located between these sheets and having relatively low liquid absorption, wherein the surface 2a of the surface sheet 2 on the side facing the skin forms the surface a of the panty liner 1 on the side facing the skin, and the surface of the back sheet 3 on the side not facing the skin forms the surface b of the panty liner 1 on the side not facing the skin. In this embodiment, as shown in Figure 2, a first adhesive layer A is formed between the surface sheet 2 and the low-absorbency sheet 4, and between the low-absorbency sheet 4 and the back sheet 3, using a hot-melt adhesive, which will be described later. １ and second adhesive layer A ２ They are joined via a connection. Furthermore, as shown in Figure 2, the non-skin-facing surface of the back sheet 3 is provided with a clothing-fixing adhesive portion in which multiple adhesive layers 6 extending continuously in the width direction W are arranged in a row along the longitudinal direction L (so-called stripe pattern). In addition, a release sheet 5 is provided on the non-skin-facing surface of the clothing-fixing adhesive portion to protect the clothing-fixing adhesive portion before use. The adhesive forming the adhesive layer is not particularly limited as long as it can fix the absorbent article to the wearer's clothing (e.g., underwear), and any adhesive containing, for example, a styrene polymer can be used. Furthermore, the arrangement pattern of the adhesive layer in the clothing-fixing adhesive portion is not particularly limited, and the adhesive layer may extend intermittently in the width direction W, or it may extend in the longitudinal direction L. When wearing the panty liner 1, the release sheet 5 is peeled off, and the panty liner 1 is fixed to the inner surface of the wearer's clothing 7 (for example, underwear) by the adhesive portion for clothing fixation located on the non-skin-facing surface of the back sheet 3, and the panty liner 1 is worn so that the front sheet 2 faces the wearer's skin. When liquid excrement such as urine is discharged from the wearer, the liquid excrement is supplied to the skin-facing surface of the front sheet 2 of the panty liner 1 and is absorbed and retained by the front sheet 2. However, if the amount of liquid excrement is large, some of the liquid excrement will permeate the front sheet 2 and be retained between the front sheet 2 and the low-absorbent sheet 4 made of hydrophobic nonwoven fabric or the like. Furthermore, in the panty liner 1 according to this embodiment, as shown in Figures 1 and 2, the surface sheet 2 made of the absorbent sheet described above has a specific uneven structure 20 in which protrusions 21 that protrude in the direction Da toward the skin-facing side of the panty liner 1 in the thickness direction T and extend continuously in the width direction W of the panty liner 1 (an example of the "direction intersecting the longitudinal direction" in this invention) and recesses 22 that are recessed in the direction Db toward the non-skin-facing side of the panty liner 1 in the thickness direction T and extend continuously parallel to the protrusions 21, are alternately arranged along the longitudinal direction L. The panty liner 1 according to this embodiment has a surface sheet 2 made of an absorbent sheet that has a specific uneven structure 20 extending in the width direction W of the panty liner 1 (i.e., an uneven structure 20 with a corrugated cross-sectional shape along the longitudinal direction L of the panty liner 1, as shown in Figure 2). As a result, the compressive strength in the direction in which the uneven structure 20 extends (i.e., the width direction W of the panty liner 1) is high, and the force applied from both legs of the wearer can be distributed in the thickness direction T by the convex portions 21 and concave portions 22 of the uneven structure 20. Therefore, the panty liner 1 according to this embodiment can maintain a certain strength (especially the compressive strength in the width direction W of the panty liner 1) not only when dry (i.e., before liquid excrement is supplied) but also when wet, and is less prone to the wrinkles described above. Furthermore, the aforementioned specific uneven structure 20 can provide the surface sheet 2 with appropriate flexibility (specifically, ease of bending in the longitudinal direction L, cushioning in the thickness direction T, etc.) and a good feel against the skin. Therefore, the panty liner 1 according to this embodiment can provide the wearer with a good wearing experience due to such appropriate flexibility and a good feel against the skin. The various components constituting the absorbent article of the present invention will be described in more detail below. [Surface sheet] In the panty liner 1 according to this embodiment, as shown in Figures 1 and 2, the surface sheet 2 is positioned on the skin-facing side in the thickness direction T of the panty liner 1, so as to be in direct contact with the wearer's skin, and has a surface 2a that forms the skin-facing side surface a of the panty liner 1, and a surface 2b that is the opposite side of the surface 2a, which is the non-skin-facing side, and is composed of an absorbent sheet having a certain level of absorbency and liquid retention. Such a surface sheet 2 is an example of an "absorbent layer having liquid absorption properties" in the absorbent article of the present invention. In this specification, "liquid absorption" refers to a property that combines the ability to absorb liquids such as liquid excrement with the ability to retain the absorbed liquid. This property is different from, for example, the property of a surface sheet in a conventional absorbent article, which allows the supplied liquid to pass through with almost no retention (specifically, the amount of liquid that passes through is greater than the amount of liquid that is retained) (so-called liquid permeability). In this embodiment, the surface sheet 2 has a long, vertical shape in plan view, aligned with the longitudinal direction L of the panty liner 1. However, the absorbent article of the present invention is not limited to this shape, and the surface sheet (absorbent layer) can be any shape and size in plan view. The absorbent sheet constituting the surface sheet 2 is not particularly limited as long as it is an absorbent sheet, and any absorbent sheet can be used, such as a fiber sheet such as a nonwoven fabric, woven fabric, or knitted fabric made of absorbent fibers; or a resin sheet made of absorbent resin. Among these, a nonwoven fabric made of absorbent fibers is preferred in terms of liquid absorption, flexibility, and feel against the skin. The type of nonwoven fabric used for the surface sheet is not particularly limited, and any nonwoven fabric can be used, such as spunlace nonwoven fabric, air-through nonwoven fabric, spunbond nonwoven fabric, point-bond nonwoven fabric, meltblown nonwoven fabric, and combinations thereof (e.g., SMS nonwoven fabric). Among these, spunlace nonwoven fabric is preferred because of its excellent flexibility and other properties. Furthermore, for absorbent fibers, hydrophilic fibers are preferable in terms of liquid absorption and liquid retention. Examples of such hydrophilic fibers include cellulose fibers such as cotton and crushed pulp; regenerated cellulose fibers such as rayon and fibril rayon; semi-synthetic cellulose fibers such as acetate and triacetate; and thermoplastic resin fibers and composite fibers that have undergone hydrophilization treatment. Among these, cellulose-based fibers such as cellulose fibers, regenerated cellulose fibers, and semi-synthetic cellulose fibers are preferable in terms of excellent liquid absorption, liquid retention, flexibility, and feel against the skin. In particular, cotton, rayon, or mixed fibers combining these are preferable. Furthermore, in cases where the absorbent article is equipped with a separate absorbent material capable of absorbing and retaining liquid excretions such as urine, or where the amount of liquid excretions to be absorbed is expected to be small, the nonwoven fabric used for the surface sheet may contain, in addition to the hydrophilic fibers mentioned above, polyolefin fibers such as polyethylene (PE) and polypropylene (PP); polyester fibers such as polyethylene terephthalate (PET); and hydrophobic thermoplastic resin fibers such as heat-fusible fibers. However, in order to ensure a certain level of absorption performance, it is preferable that the hydrophilic fibers are included in a mass ratio of 50% by mass or more. As described above, the non-woven fabric used for the surface sheet may contain heat-fusible fibers in addition to hydrophilic fibers in order to improve sheet strength and the like. In particular, when the low-absorbency sheet (low-absorbency layer) described later contains heat-fusible fibers, the non-woven fabric used for the surface sheet preferably does not contain heat-fusible fibers or contains them at a content (mass ratio) less than the content (mass ratio) of the heat-fusible fibers in the low-absorbency sheet. When the non-woven fabric used for the surface sheet does not contain heat-fusible fibers or contains them at a content less than the content of the heat-fusible fibers in the low-absorbency sheet, the joints (fusion parts) formed by the fusion of the heat-fusible fibers do not exist in the non-woven fabric constituting the surface sheet or, if they do exist, the number of joints (fusion parts) in the low-absorbency sheet with low liquid absorbency constituting the low-absorbency sheet is less. Therefore, the rigidity of the surface sheet becomes lower than that of the low-absorbency sheet, and it becomes easier for the surface sheet to ensure appropriate flexibility and good touch. Therefore, an absorbent article provided with such a surface sheet and a low-absorbency sheet can ensure the difficulty of sagging (especially the difficulty of sagging when wet) by the low-absorbency sheet (low-absorbency layer) with low liquid absorbency described above, and can easily ensure appropriate flexibility and good touch by the absorbent layer described above. The basis weight of the surface sheet (absorbent layer) is not particularly limited as long as the effects of the present invention are not impaired, and any basis weight can be adopted in consideration of absorbency, liquid retention, difficulty of sagging, flexibility, etc. Such basis weights include, for example, basis weights within the range of 10 g / m 2 to 100 g / m 2 , and preferably within the range of 20 g / m 2 to 50 g / m 2 . The basis weight can be measured in accordance with 5.2 of JIS L 1906. Regarding the thickness of the surface sheet (absorbent layer), it is not particularly limited as long as the effects of the present invention are not impaired. For example, a thickness within the range of 0.001 mm to 5.0 mm can be adopted. From the viewpoints of absorbency, liquid retention, difficulty of sagging, flexibility, touch, etc., it is preferably within the range of 0.01 mm to 3.0 mm, and more preferably within the range of 0.1 mm to 1.0 mm. Here, the thickness of the surface sheet and the low-absorbency sheet described later can be measured according to the following <Method for Measuring the Thickness of Various Sheets>. The thickness of other sheets (e.g., backing sheet, etc.) can also be measured in the same manner. <Methods for measuring the thickness of various sheets> (1) Cut out a sample sheet of a predetermined size (for example, 100 mm x 100 mm) from the sheet to be measured. (2) The cut sample sheet is placed in the KES FB-3A automated compression testing machine of Kato Tech Co., Ltd., and the thickness (mm) is measured when the pressure on the sample sheet by the measuring terminal of the machine is 49 Pa. This measured thickness (mm) is taken as the thickness of the sample sheet. In this embodiment, as shown in Figures 1 and 2, the surface sheet 2 has a specific uneven structure 20 in which protrusions 21 that project in the direction Da toward the skin-facing side of the panty liner 1 in the thickness direction T and extend continuously in the width direction W of the panty liner 1, and recesses 22 that are recessed in the direction Db toward the non-skin-facing side of the panty liner 1 in the thickness direction T and extend continuously parallel to the protrusions 21, are alternately arranged along the longitudinal direction L of the panty liner 1. Furthermore, the protrusions 21 have cavities 23 that face the non-skin-facing surface 2b of the surface sheet 2. As shown in Figure 3, in conventional panty liners 1' (absorbent articles), the wet strength of the absorbent material is low. Therefore, when the absorbent material absorbs liquid excretions such as urine, a force (crotch constriction force) F is exerted from both legs of the wearer in the width direction W of the panty liner 1'. ＷAs a result, the absorber was likely to be crushed in the width direction W, and consequently, the panty liner 1' might be crushed and wrinkled in the width direction W. On the other hand, in the panty liner 1 according to the present embodiment, the surface sheet 2 as the absorption layer has the specific concavo-convex structure 20 extending in the width direction W of the panty liner 1. Due to this, the compressive strength in the direction in which the concavo-convex structure 20 extends (i.e., the width direction W) is high. Further, the forces applied from both legs of the wearer can be dispersed in the thickness direction T by the convex portions 21 and concave portions 22 in the above-mentioned concavo-convex structure 20. Therefore, not only during drying but also during wetting, a certain strength (particularly, the compressive strength in the width direction W) can be maintained, and wrinkling is less likely to occur. Furthermore, the above-mentioned specific concavo-convex structure 20 can impart appropriate flexibility (specifically, ease of bending in the longitudinal direction L, cushioning property in the thickness direction T, etc.) and good touch to the surface sheet 2. Thus, the panty liner 1 according to the present embodiment can provide a more excellent wearing feeling to the wearer due to such appropriate flexibility and good touch. Also, in the present embodiment, although the convex portions 21 and concave portions 22 of the above-mentioned concavo-convex structure 20 extend in the width direction W of the panty liner 1, in the present invention, the direction in which the convex and concave portions of the concavo-convex structure extend is not limited to the "width direction" in the above-mentioned embodiment as long as it is a direction "intersecting the longitudinal direction" of the absorbent article. In this specification, the "direction intersecting the longitudinal direction" of the absorbent article means a direction in which the angle formed with the longitudinal direction of the absorbent article is within the range of 45° or more and 90° or less. The absorbent article of the present invention has a specific concavo-convex structure in which the absorption layer extends in a direction intersecting the longitudinal direction of the absorbent article. Due to this, the compressive strength in the direction in which the concavo-convex structure extends is high. Further, the forces applied from both legs of the wearer can be dispersed in the thickness direction by the convex and concave portions in the above-mentioned concavo-convex structure. Therefore, even during wetting, a certain strength (particularly, the compressive strength in the direction intersecting the longitudinal direction of the absorbent article) can be maintained, and wrinkling is less likely to occur. Particularly, in the above-described embodiment, among the "directions intersecting the longitudinal direction" of the panty liner 1 (absorbent article), since the uneven structure 20 extends in the "width direction" where the force transmitted from both legs of the wearer is most strongly applied, the panty liner 1 according to the present embodiment is less likely to develop the above-described sagging. In the present invention, the pitch of the convex portions in the uneven structure (that is, the distance (mm) between the centers of the tops of two adjacent convex portions) is not particularly limited. For example, a pitch within the range of 0.5 mm to 5.0 mm can be adopted. However, from the viewpoints of cushioning properties and touch, etc., it is preferably within the range of 1.0 mm to 4.0 mm. The pitch of the convex portions can be measured as the distance (mm) between the centers of the tops of two adjacent convex portions based on a plan view photograph or a planar image of the surface sheet in the unpressurized state. In the present embodiment, as shown in FIG. 2, the surface sheet 2 is joined to the low-absorbency sheet 4 on the non-skin-facing surface 2b of the recess 22 of the uneven structure 20. Since the low-absorbency sheet 4 is not an essential component in the absorbent article of the present invention as described later, when the absorbent article does not have such a low-absorbency sheet, the surface sheet may be joined to the absorber or (when there is no absorber either) the back sheet on the non-skin-facing surface of the recess of the uneven structure. The means for joining the surface sheet to these constituent members (that is, the low-absorbency sheet, the absorber, or the back sheet) is not particularly limited, and for example, any joining means such as a heat fusion method such as a hot melt adhesive or heat seal can be adopted. The method for forming the above-described specific uneven structure on the surface sheet is not particularly limited, and for example, any shaping method such as a method using gear stretching or a method using vacuum forming or press forming can be adopted. Furthermore, in this embodiment, as described above, the surface sheet 2 is configured as an absorbent layer having liquid-absorbing properties. When the surface sheet is configured as an absorbent layer having liquid-absorbing properties in this way, liquid excretions such as urine excreted from the wearer can be quickly absorbed and retained by the absorbent surface sheet, and there is no need to provide a separate absorbent body in the absorbent article (or if a separate absorbent body is provided, a thin absorbent body is sufficient), so the absorbent article can be made thinner overall, and even better flexibility and wearing comfort can be obtained. Furthermore, layers with excellent liquid absorption properties, such as absorbents, generally tend to lose strength when wet, causing the absorbent article to become prone to warping. Therefore, by constructing the absorbent article so that it does not include any layers with excellent liquid absorption properties other than the absorbent layer with the specific uneven structure described above (a surface sheet with liquid absorption properties), the wet strength of the absorbent article becomes less likely to decrease (i.e., the absorbent article becomes less prone to warping when wet). Therefore, if an absorbent article has a surface sheet with the above-mentioned specific uneven structure as an absorbent layer with liquid-absorbing properties, and does not contain any other liquid-absorbing layer besides the surface sheet, it is possible to more reliably achieve both resistance to creasing when wet and excellent wearability. [Low absorbency sheet] In the panty liner 1 according to this embodiment, the low-absorbency sheet 4, which has low liquid absorption, is positioned between the surface sheet 2 and the back sheet 3 in the thickness direction T of the panty liner 1, as shown in Figure 2, and is bonded to the surface sheet 2, functioning to reinforce the strength (especially the wet strength) of the surface sheet (absorbent layer). Since the low-absorbency sheet 4 has lower liquid absorption (i.e., relatively higher strength when wet) than the surface sheet 2 (absorbent layer) described above, the bond of such a low-absorbency sheet 4 to the surface sheet 2 reinforces the strength (especially the wet strength) of the surface sheet 2, making it easier for the panty liner 1 to maintain a certain level of strength even when wet, and further reducing the likelihood of wrinkles. The sheet material constituting the low-absorption sheet is not particularly limited as long as it has lower liquid absorption than the absorption layer, but it is preferable to use a hydrophobic nonwoven fabric in terms of wet strength, resistance to twisting, and flexibility. When using a hydrophobic nonwoven fabric as the low-absorption sheet, it is sufficient if the hydrophobicity is such that when water is dropped onto the surface of the hydrophobic nonwoven fabric, it does not absorb the water, but it is even more preferable that the hydrophobicity is such that when water is dropped onto the surface of the hydrophobic nonwoven fabric, the water is repelled and forms droplets (so-called water repellency) in terms of wet strength and resistance to twisting. The type of hydrophobic nonwoven fabric used for the low-absorbency sheet (low-absorbency layer) is not particularly limited as long as it has lower liquid absorption than the absorbency layer; for example, the same type of nonwoven fabric as the surface sheet described above can be used. In particular, it is preferable to use an air-through nonwoven fabric because it is easy to maintain wet strength. When the low-absorbency layer is made of an air-through nonwoven fabric that is particularly easy to maintain wet strength and is bonded to the surface of the absorbency layer on the non-skin-facing side, liquid excretions such as urine can be quickly absorbed into the absorbency layer, and the absorbency layer is reinforced by the low-absorbency layer, which can more reliably maintain the wet strength of the absorbent article, and as a result can more reliably prevent the aforementioned twisting (especially when wet). Furthermore, the low-absorbency sheet described above may be composed of a single-layer hydrophobic nonwoven fabric using a hydrophobic nonwoven fabric alone, or it may be composed of a laminated hydrophobic nonwoven fabric using two or more hydrophobic nonwoven fabrics. When the low-absorbency sheet is composed of a hydrophobic laminated nonwoven fabric, the wet strength and flexibility of the absorbent article can be easily adjusted by adjusting the number of layers of the hydrophobic laminated nonwoven fabric. The fibers constituting the hydrophobic nonwoven fabric used in the low-absorption sheet (low-absorption layer) are not particularly limited as long as they are hydrophobic. For example, hydrophobic thermoplastic resin fibers such as polyolefin fibers like PE and PP; polyester fibers like PET; and various composite fibers such as core-sheath type composite fibers can be used. Furthermore, the hydrophobic nonwoven fabric used in the low-absorption layer may contain heat-fusible fibers to improve rigidity. In particular, if the absorption layer contains heat-fusible fibers, it is preferable to contain heat-fusible fibers in a larger quantity (by mass percentage) than the heat-fusible fiber content (by mass percentage) of the absorption layer. If the hydrophobic nonwoven fabric used in the low-absorption layer contains more heat-fusible fibers than the heat-fusible fibers in the absorption layer, the number of joints (fused parts) formed by the fusion of heat-fusible fibers within the hydrophobic nonwoven fabric will be greater than the number of joints (fused parts) within the nonwoven fabric constituting the absorption layer. As a result, the rigidity of the low-absorption layer will be higher than that of the absorption layer, making it easier to ensure resistance to twisting (especially when wet) in the low-absorption layer while ensuring appropriate flexibility and a good feel in the absorption layer. The basis weight of the low-absorption sheet (low-absorption layer) is not particularly limited as long as it does not hinder the effects of the present invention, and any basis weight can be adopted considering wet strength, flexibility, etc. For example, a basis weight of 20 g / m² is one such example. 2 ~200g / m 2 A basis weight within the range of 30 g / m² is possible, preferably 30 g / m². 2 ~100g / m 2 It is within the specified range. Furthermore, if the low-absorbency sheet consists of the aforementioned hydrophobic laminated nonwoven fabric, the sum of the basis weights of each layer constituting the hydrophobic laminated nonwoven fabric must be within the specified range. Furthermore, the thickness of the low-absorbency sheet (low-absorbency layer) is not particularly limited as long as it does not hinder the effects of the present invention. For example, a thickness in the range of 0.01 mm to 8.0 mm can be used, but from the viewpoint of wet strength and flexibility, it is preferably in the range of 0.05 mm to 5.0 mm, and more preferably in the range of 0.1 mm to 3.0 mm. If the low-absorbency sheet is made of the hydrophobic laminated nonwoven fabric described above, the total thickness of the layers constituting the hydrophobic laminated nonwoven fabric should be within the above range. Furthermore, in the present invention, it is preferable that the thickness of the low-absorbency sheet (low-absorbency layer) is greater than the thickness of the absorbency layer. When the thickness of the low-absorbency layer is greater than the thickness of the absorbency layer, the force applied from both legs of the wearer can be distributed in the thickness direction even within the low-absorbency layer, making the absorbent article even less prone to twisting. In addition, as described above, the low-absorbency layer is a layer with relatively high strength when wet, so it can further reduce the aforementioned twisting, especially when the absorbent article is wet. In this embodiment, the surface sheet 2 and the low-absorbency sheet 4 are bonded by a first adhesive layer A made of a hot-melt adhesive. １ Although they are joined to each other via a certain method, in the present invention, the joining method of the absorbent layer and the low-absorbent layer is not limited to this method as long as it does not hinder the effects of the present invention, and the absorbent layer and the low-absorbent layer may be joined by any joining means such as heat fusion. For example, if the absorbent layer and the low-absorbent layer are joined by heat fusion, the joint (fused part) is less susceptible to decomposition by liquid excretions such as urine, so the joining state can be maintained well even when the absorbent article is wet, and the function of reinforcing the absorbent layer with the low-absorbent layer described above can be performed more reliably. As a result, the absorbent article becomes even less prone to warping. In this embodiment, the low-absorbency sheet 4 (low-absorbency layer) is positioned on the non-skin-facing side of the surface sheet 2 (absorbency layer) in the thickness direction T of the panty liner 1 (absorbency article). However, in the present invention, the low-absorbency layer may also be positioned on the skin-facing side of the absorption layer. In that case, it is desirable that the low-absorbency layer has a predetermined liquid permeability. Even when the low-absorbency layer is positioned on the skin-facing side of the absorption layer, the same effects as in the above embodiment can be achieved in terms of reinforcing the strength (especially the wet strength) of the absorption layer. Furthermore, since a low-absorbency sheet (low-absorbency layer) is not an essential component in the absorbent article of the present invention, the absorbent article can be constructed without a low-absorbency sheet (low-absorbency layer), taking into consideration the flexibility of the absorbent article. [Backside sheet] In this embodiment, as shown in Figure 2, the back sheet 3 is positioned on the non-skin-facing side in the thickness direction T of the panty liner 1 and is made of a liquid-impermeable sheet that provides breathability while preventing the permeation of liquid excretions such as urine discharged from the wearer, and preventing such liquid excretions from leaking onto the wearer's clothing, etc. The liquid-impermeable sheet constituting the backing sheet 3 is not particularly limited, and any liquid-impermeable sheet can be used, for example, a hydrophobic nonwoven fabric, a breathable resin film such as polyethylene or polypropylene, a laminate in which a nonwoven fabric is bonded to the resin film, or a laminated nonwoven fabric such as SMS. Among these, a hydrophobic nonwoven fabric is preferred in terms of liquid impermeability, wet strength, and flexibility. When using a hydrophobic nonwoven fabric as the backing sheet, the degree of hydrophobicity is the same as that of the low-absorbency sheet described above. It is sufficient if the hydrophobic nonwoven fabric is so hydrophobic that it does not absorb water when water is dropped onto its surface. However, from the standpoint of wet strength, resistance to twisting, and resistance to leakage of liquid excrement, it is even more preferable that the hydrophobic nonwoven fabric is so hydrophobic that when water is dropped onto its surface, the water is repelled and forms droplets (so-called water-repellent). Furthermore, the type of hydrophobic nonwoven fabric used for the backing sheet is not particularly limited as long as it does not hinder the effects of the present invention, and any nonwoven fabric such as spunbond nonwoven fabric, point bond nonwoven fabric, meltblown nonwoven fabric, or SMS nonwoven fabric can be used. Among these nonwoven fabrics, it is preferable to use a nonwoven fabric that includes an ultrafine fiber layer composed of fibers having a fineness of 1 dtex or less. Since such an ultrafine fiber layer has excellent breathability and liquid impermeability as well as appropriate flexibility, using a nonwoven fabric containing such an ultrafine fiber layer as the backing sheet can further improve the wearing comfort of the absorbent article. The lower limit of the fineness of the fibers constituting the ultrafine fiber layer is not particularly limited, but for example, it is about 0.1 dtex. Furthermore, among the hydrophobic nonwoven fabrics mentioned above, it is particularly preferable to use SMS nonwoven fabric. SMS nonwoven fabric is a laminated nonwoven fabric consisting of a three-layer structure of spunbond / meltblown / spunbond. This SMS nonwoven fabric combines breathability and a certain strength (resistance to twisting) (especially due to the spunbond layer), and is a nonwoven fabric that can more effectively suppress the permeation of liquid excrement (especially due to the meltblown layer, which is an ultrafine fiber layer). Therefore, when such a nonwoven fabric is used as a backing sheet, it is possible to more effectively suppress the leakage of liquid excrement while ensuring excellent breathability and resistance to twisting (especially resistance to twisting when wet) in the backing sheet. Furthermore, the constituent fibers of the hydrophobic nonwoven fabric used for the backing sheet are not particularly limited as long as they are hydrophobic. For example, hydrophobic thermoplastic resin fibers such as polyolefin fibers like PE and PP; polyester fibers like PET; and various composite fibers such as core-sheath type composite fibers can be used. In the present invention, the basis weight of the backing sheet is not particularly limited as long as it does not hinder the effects of the present invention, and any basis weight can be adopted taking into consideration wet strength, flexibility, breathability, liquid impermeability, etc. For example, a basis weight of 8 g / m² is one such basis weight. 2 ~60g / m 2 A basis weight within the range of 15 g / m² is possible, preferably 15 g / m². 2 ~50g / m 2 It is within the range. Furthermore, the thickness of the backing sheet is not particularly limited as long as it does not hinder the effects of the present invention. For example, a thickness in the range of 0.01 mm to 5.0 mm can be used, but from the viewpoint of wet strength, flexibility, breathability, and liquid impermeability, it is preferably in the range of 0.05 mm to 3.0 mm. [Adhesive layer] In the above-described embodiment, as shown in Figure 2, the panty liner 1 has a first adhesive layer A made of hot-melt adhesive, with a surface sheet 2, a low-absorbency sheet 4, and a back sheet 3 arranged between each sheet (i.e., between the surface sheet 2 and the low-absorbency sheet 4, and between the low-absorbency sheet 4 and the back sheet 3). １ and second adhesive layer A ２They are joined to each other via the adhesive layer. In this way, when the surface sheet (absorbent layer) and the low-absorbent sheet (low-absorbent layer), and the low-absorbent sheet (low-absorbent layer) and the back sheet are joined via the first adhesive layer and the second adhesive layer, respectively, misalignment and deformation between these sheets become less likely to occur, making the absorbent article even less prone to warping. In the above embodiment, the first adhesive layer A １ and second adhesive layer A ２ The adhesive arrangement patterns in the above are all spiral arrangement patterns extending in the longitudinal direction L, but in the present invention, the arrangement patterns are not limited to such patterns, and any arrangement pattern such as omega-shaped, wavy, zigzag, stripe-shaped, or band-shaped, which extends in the longitudinal direction and / or the width direction, can be adopted. Furthermore, it is preferable that the first adhesive layer between the surface sheet and the low-absorbency sheet, and the second adhesive layer between the low-absorbency sheet and the back sheet, are arranged such that their respective arrangement patterns do not overlap in the thickness direction of the absorbent article (i.e., the arrangement patterns of the first adhesive layer and the second adhesive layer do not overlap in a plan view). When the first and second adhesive layers are arranged in arrangement patterns that do not overlap in the thickness direction of the absorbent article, a certain number of joint points that can become bending initiation points are formed, thereby improving the overall strength of the absorbent article, making it more resistant to twisting, and also providing a more appropriate degree of flexibility. This makes it possible to more effectively and reliably achieve both resistance to twisting (especially resistance to twisting when wet) and excellent wearability. In this specification, the arrangement pattern in which the first adhesive layer and the second adhesive layer do not overlap in the thickness direction of the absorbent article includes not only an embodiment in which the arrangement pattern of the first adhesive layer and the arrangement pattern of the second adhesive layer do not completely overlap in the thickness direction of the absorbent article, but also an embodiment in which each arrangement pattern partially overlaps in the thickness direction of the absorbent article. Furthermore, in the above-described embodiment, the sheets are joined together by a hot-melt adhesive (i.e., between the surface sheet 2 and the low-absorbency sheet 4, and between the low-absorbency sheet 4 and the back sheet 3). However, in the present invention, the means for joining the sheets together are not particularly limited as long as they do not hinder the effects of the present invention, and the sheets may be joined together by any joining means, such as heat fusion. For example, if the sheets are joined together by heat fusion, the joint (fused joint) is less susceptible to decomposition by liquid excretions such as urine, so the bonded state can be maintained well even when the absorbent article is wet, and the absorbent article is less likely to wrinkle. [Absorbent] The panty liner 1 according to the above embodiment does not have an absorbent body for absorbing and retaining liquid excrement such as urine, in addition to the surface sheet 2 as an absorbent layer. However, the absorbent article of the present invention may include such an absorbent body as long as it does not hinder the effects of the present invention. Specifically, the absorbent article of the present invention may have an absorbent body capable of absorbing and retaining liquid excrement positioned between the surface sheet and the low-absorbency sheet, for example, as long as it does not hinder the effects of the present invention. When such an absorbent body is positioned between the surface sheet and the low-absorbency sheet, even if some of the liquid excrement supplied onto the surface sheet permeates through the surface sheet, the absorbent body can absorb and retain the liquid excrement, thereby suppressing leakage and backflow of liquid excrement from the absorbent article, and as a result, a good wearing experience of the absorbent article can be more reliably provided to the wearer. Furthermore, the absorbent material is not particularly limited as long as it is capable of absorbing and retaining liquid excrement, and any absorbent material known in this field can be used. Examples of such absorbent materials include an absorbent core made of an absorbent material covered with a core wrap sheet such as hydrophilic tissue. Examples of absorbent materials that make up the absorbent core include hydrophilic fibers and superabsorbent polymers, and more specifically, cellulose fibers such as crushed pulp and cotton; regenerated cellulose fibers such as rayon and fibril rayon; semi-synthetic cellulose fibers such as acetate and triacetate; granular materials made of superabsorbent polymers such as sodium acrylate copolymer; and any combination of two or more of these. Furthermore, in addition to the panty liners of the embodiments described above, the present invention can be applied to various absorbent articles such as sanitary napkins and (light) incontinence pads. Moreover, the absorbent articles of the present invention are not limited to the embodiments described above, and can be appropriately combined or modified without departing from the purpose and spirit of the present invention. In this specification, ordinal numbers such as "first," "second," etc., are used to distinguish the items to which they are assigned, and do not indicate the order, priority, importance, etc. of each item. 1. Panty liners (an example of absorbent material) 2. Surface sheet (an example of an absorbent layer with liquid-absorbing properties) 3. Back sheet 4. Low-absorption sheet (an example of a low-absorption layer) 5. Release sheet 6. Adhesive layer 7. Clothing A １ First adhesive layer A ２ Second adhesive layer

Claims

Page 1 of 1 page Claims 1. An absorbent material consisting of an absorbent layer with liquid absorption properties and in which the longitudinal, width, and thickness directions are perpendicular to each other, in which the absorbent layer consists of a nodule-crevice structure, where the nodule protrudes directly toward the surface facing the skin of the absorbent material in the thickness direction and continues in a direction that intersects the longitudinal direction, and the crevice is collapsed toward the surface facing the non-skin side of the absorbent material in the thickness direction and continues in a direction parallel to the nodule, are arranged alternately in the longitudinal direction, and the nodule contains pores in which the surface of the absorbent layer on the surface facing the non-skin side is oriented.

2. An absorbent material according to claim 1 in which the direction that intersects the longitudinal direction is the width direction. 3.Absorbent material under claim 1 or 2 where the absorbent material consists of a low-absorbent layer with lower liquid absorption properties than the absorbent layer, on one or both sides of the surface side facing the skin and the surface side facing the non-skin side of the absorbent layer in the direction of the thickness of the absorbent material, and the absorbent layer and the low-absorbent layer are joined together.

4. Absorbent material under claim 3 where the low-absorbent layer is thicker than the absorbent layer.

5. Absorbent material under claim 3 or 4 where the low-absorbent layer consists of heat-meltable fibers and has a certain meltable area where the heat-meltable fibers are fused together, while the absorbent layer does not contain heat-meltable fibers or has a lower amount of heat-meltable fibers than the low-absorbent layer. 6.

7. Absorbent material under any of the claims 3 through 5 where the low-absorbent layer is composed of air-modified synthetic fibers and the air-modified synthetic fibers are placed on the surface side facing the non-skin side of the absorbent layer, in the direction of the thickness of the absorbent material.

8. Absorbent material under any of the claims 1 through 7 where the absorbent layer is the top sheet.