Absorbent article

Abstract

This absorbent article includes: a non-fixed region which is formed in a central region and in which a back sheet and a skin-side structure part are not fixed and thus the back sheet and the skin-side structure part are relatively slidable; and a fixed region other than the non-fixed region. When the absorbent article is viewed from a non-skin side after the non-fixed region and the fixed region are caused to absorb the same amount of colored liquid from the skin side, the relationship Ln > Lf is satisfied, where Ln is the L* value in the non-fixed region and Lf is the L* value in the fixed region, the L* values being defined in the CIE L*a*b* color system.

Description

Absorbent articles

[0001] This disclosure relates to absorbent articles.

[0002] Traditionally, absorbent products such as sanitary napkins, panty liners, and incontinence pads have been known to have an impermeable backsheet, an absorbent core, and a permeable topsheet, in that order. Because absorbent products are worn in close contact with delicate areas of the skin, many wearers are concerned about friction between the absorbent product and their skin.

[0003] As a means of preventing chafing and improving wearing comfort, it is known to use a top sheet with an uneven surface (for example, Patent Document 1). Also known are absorbent articles in which a drug such as a skin care agent is applied to the skin-facing side of the top sheet (for example, Patent Document 2).

[0004] Japanese Patent Publication No. 2017-55841 Japanese Patent Publication No. 2023-19296

[0005] The technologies disclosed in Patent Documents 1 and 2 involve modifications to components that come into direct contact with the skin. While such technologies can reduce damage caused by friction between the skin-facing surface of an absorbent article and the skin, they do not improve the wearing comfort by preventing friction itself. Therefore, there is a need for a configuration that minimizes friction and improves wearing comfort by allowing the skin-facing surface of the absorbent article to conform as closely as possible to the skin.

[0006] Furthermore, when users replace absorbent items and attempt to dispose of used items, they typically fold or roll the absorbent item inwards and wrap it in the packaging sheet or paper. Even if this action is performed quickly, it is unavoidable that bodily fluids will be visible through the non-skin side of the absorbent item. Some users may find this visibility unpleasant and uncomfortable. Therefore, there is a need to minimize the discomfort experienced when disposing of used absorbent items.

[0007] In view of the above, one aspect of this disclosure aims to provide a technology that improves the wearing comfort by enabling the skin-side surface of the absorbent article to conform well to the wearer's skin, and reduces discomfort when the absorbent article is viewed from the non-skin side.

[0008] One aspect of the present disclosure is an absorbent article having an impermeable backsheet and a skin-side structure disposed on the skin side of the backsheet, wherein the skin-side structure includes an absorbent portion directly disposed on the skin side of the backsheet and a permeable top sheet disposed on the skin side of the absorbent portion, the absorbent article having a central region including a portion facing a bodily fluid outlet that faces the wearer's bodily fluid outlet when worn, a front region forward of the central region and a rear region backward of the central region, the backsheet and the skin-side structure are not fixed, and the backsheet and the skin-side structure are relatively slidable, having a non-fixed region formed in the central region and a fixed region other than the non-fixed region, and after absorbing the same amount of coloring liquid from the skin side into the non-fixed region and the fixed region respectively, the absorbent article is viewed from the non-skin side and CIE L ＊ a ＊ b ＊ L defined by the color system ＊ The value is Ln, and L in the fixed region. ＊ Let the value be Lf, and Ln > Lf.

[0009] According to one aspect of this disclosure, it is possible to provide a technology that improves the wearing comfort by enabling the skin-facing surface of an absorbent article to conform well to the wearer's skin, and also reduces discomfort when the absorbent article is viewed from the non-skin side.

[0010] This is a plan view of an absorbent article according to one embodiment of the present disclosure, as seen from the skin side. This is a cross-sectional view taken along line I-I in Figure 1. This is a cross-sectional view taken along line II-II in Figure 1. This is a plan view of an absorbent article according to a modified example. This is a plan view of an absorbent article according to yet another modified example. This is a plan view of an absorbent article according to yet another modified example. This is a diagram illustrating the injection cylinder used in the example.

[0011] The embodiments of this disclosure will be described in detail below with reference to the drawings. In each drawing, unless otherwise specified, the same or corresponding components may be denoted by the same reference numerals and their descriptions may be omitted. Also, the drawings are schematic in order to aid in understanding the invention, and some dimensions may be shown larger or smaller than they actually are. Furthermore, in cross-sectional views, two components may be shown separated to indicate that no other component is interposed between them.

[0012] The absorbent articles according to the embodiments of this disclosure may specifically be sanitary napkins, light incontinence pads, panty liners, diapers, etc., but are preferably used as sanitary napkins. In the following, this embodiment will be described based on the example of a sanitary napkin.

[0013] <Basic Structure of Absorbent Articles> Figure 1 shows a plan view of an absorbent article 1 according to one embodiment of the present disclosure, as seen from the side facing the skin when worn (skin side). Figure 2 shows a cross-sectional view taken along line I-I in Figure 1, and Figure 3 shows a cross-sectional view taken along line II-II in Figure 1. In the cross-sectional views, the gray color indicates the joining or fixing of layers. That is, the gray area in the cross-sectional view indicates that the two members sandwiching the gray area are joined or fixed to each other. Two members laminated without an intervening gray area are in direct contact or can be in direct contact, but are not joined or fixed to each other.

[0014] As shown in Figures 1 to 3, the absorbent article 1 is made up of an impermeable backsheet 2, an absorbent portion 4, and a permeable topsheet 3, which are laminated in this order from the non-skin side to the skin side. When the wearer is wearing the absorbent article 1, the backsheet 2 side (non-skin side) is fixed to underwear such as shorts by a slip-prevention portion (described in detail later), and the topsheet 3 side (skin side) is in contact with the skin. In this specification, the portion of the backsheet 2 laminated on the skin side is called the skin-side structure 15. The skin-side structure 15 is a portion that includes at least the absorbent portion 4 and the topsheet 3, and may also include an intermediate sheet, as will be described later. Alternatively, the skin-side structure 15 may be the entire portion up to the surface that comes into contact with the wearer's skin. The skin-side structure 15 is arranged such that the absorbent portion 4 is directly superimposed on (in direct contact with) the backsheet 2. However, although the absorbent portion 4 of the skin-side structure 15 is mainly in contact with the backsheet 2, the topsheet 3, or another layer other than the absorbent portion 4 and the topsheet 3, such as the sidesheet 7, may also be in contact with the backsheet 2 around the absorbent portion 4. Within the skin-side structure 15, the components may or may not be fixed to each other, but the absorbent portion 4 and the topsheet 3 may be fixed together by adhesive or embossing as shown in Figures 2 and 3.

[0015] The absorbent article 1 may include wings wg, wg extending from both side portions. The wings wg, wg are portions for folding back to the non-skin side of the underwear during wearing to securely fix the absorbent article 1 to the underwear. The portion excluding the wings wg, wg is called the main body of the absorbent article (also referred to as the absorbent article main body) bd. The absorbent article main body bd has a predetermined length in the front-back direction D1 and has an elongated shape with a predetermined width in the lateral direction D2 orthogonal to the front-back direction D1. The front-back direction (longitudinal direction) D1 of the absorbent article 1 is a direction corresponding to the front-back direction of the wearer's body during wearing, and the lateral direction (lateral direction) D2 is a direction corresponding to the left-right direction of the wearer's body. The width of the absorbent article main body may be substantially constant, but may also vary over the front-back direction D1. Further, the absorbent article 1 shown in FIGS. 1 to 3 has a shape and structure that are substantially line-symmetric with respect to the center line (front-back direction center line) CL extending in the front-back direction, but the structure of the absorbent article does not necessarily have to be line-symmetric.

[0016] The body fluid discharge port facing portion Q shown in FIG. 1 is a portion that faces the body fluid discharge port such as the vaginal opening of the wearer during wearing and is on the front-back direction center line CL. The body fluid discharge port facing portion Q may be in the range of 10 mm or more and 50 mm or less in the front-back direction D1 and 10 mm or more and 30 mm or less in the width direction D2, but the size of the body fluid discharge port facing portion Q is not necessarily limited to the above range.

[0017] The absorbent article 1 has a central region C including the body fluid discharge port facing portion Q, a front region F in front of the central region C, and a rear region R behind the central region C. The above-described wings wg, wg may extend outward in the lateral direction D2 (outward in the width direction D2) from the side of the central region C. The central region C may be a region corresponding to the crotch portion of the wearer's underwear during wearing. Further, the central region C may be a region from one edge to the other edge in the front-back direction D1 of the wings wg at the position in the lateral direction D2 where the wings wg are connected to the absorbent article main body bd (the base end of the wings wg).

[0018] The length (total length) of the absorbent article 1 in the front-to-back direction D1 is preferably 150 mm or more and 450 mm or less, more preferably 170 mm or more and 360 mm or less. The thickness of the portion of the absorbent article body bd containing the absorbent part 4 is measured at a location other than the area compressed in the thickness direction, and is preferably 0.3 mm or more and 30 mm or less, more preferably 1.0 mm or more and 15 mm or less. However, the absorbent article body bd may be partially bulged by bulging the absorbent part 4 in a part of the absorbent part 4, for example, the area opposite the body fluid outlet Q and the area near it, and in the center of the width direction D2 of the rear area.

[0019] One embodiment of this disclosure may be an absorbent article without wings wg, wg. In that case, assuming that wings wg, wg are formed, the region from one edge to the other in the front-rear direction D1 at the base end of the wings wg, wg in the lateral direction D2 can be defined as the central region C.

[0020] On the skin-facing side of the top sheet 3, side sheets 7, 7 are superimposed, extending in the front-to-back direction D1 along both sides of the absorbent portion 4. The side sheets 7, 7 extend to both sides and are joined to the back sheet 2, which also extends to both sides, to form wings wg, WG. The side sheets 7, 7 may extend inward in the width direction D2 to form gathers. The absorbent article 1 does not necessarily have side sheets 7, 7; in that case, the wings wg may be formed by joining the back sheet 2 and a sheet positioned on the non-skin side of the back sheet 2.

[0021] In the example shown in FIG. 1, both the backsheet 2 and the topsheet 3 have the same length in the front-rear direction D1 from the front end to the rear end of the absorbent article 1. On the other hand, the width of the topsheet 3 (the length in the lateral direction D2) is smaller than the width of the backsheet 2. Further, the absorbent body portion 4 is provided sandwiched between the topsheet 3 and the backsheet 2 so as not to be exposed to the outside. For example, as shown in FIG. 1, the absorbent body portion 4 is arranged so as to fit within the backsheet 2 in plan view, that is, so as not to protrude from the backsheet 2. Further, the absorbent body portion 4 is configured and arranged so as to fit within the region where the topsheet 3 and the side sheets 7, 7 are provided. For example, the absorbent body portion 4 may protrude from the topsheet 3 at both ends in the width direction D2, but in that case, the protruding portions are covered by the side sheets 7, 7.

[0022] As the backsheet 2, at least a sheet material having water barrier properties such as an olefin resin sheet such as polyethylene or polypropylene can be used. A laminated nonwoven fabric in which a nonwoven fabric is laminated on a polyethylene sheet or the like, or a laminated sheet of a nonwoven fabric in which a waterproof film is interposed to ensure substantially liquid impermeability can be used. Further, it is more desirable to use a material having moisture permeability from the viewpoint of preventing stuffiness. As such a water barrier / moisture permeable sheet material, a microporous sheet obtained by melt-kneading an inorganic filler in an olefin resin such as polyethylene or polypropylene, forming a sheet, and then stretching it in one or two axial directions can be used.

[0023] The top sheet 3 is a permeable sheet that allows bodily fluids such as menstrual blood, vaginal discharge, and urine to pass through quickly. Suitable materials for the top sheet 3 include perforated or non-perforated nonwoven fabrics and porous plastic sheets. Suitable materials for the nonwoven fabric include, for example, olefins such as polyethylene and polypropylene, synthetic fibers such as polyester and polyamide, regenerated fibers such as rayon and cupro, and blends thereof, as well as natural fibers such as cotton, which can be used individually or in combination of two or more. Processing methods for the nonwoven fabric include the spunlace method, spunbond method, thermal bond method, meltblown method, and needle punch method. Of these processing methods, the spunlace method is preferred for producing flexible nonwoven fabrics, the spunbond method for producing nonwoven fabrics with good drape, and the thermal bond method for producing bulky and soft nonwoven fabrics. Furthermore, composite fibers such as core-sheath type fibers, side-by-side type fibers, and split type fibers, which use fibers with high melting points as a core and fibers with low melting points as a sheath, can be used.

[0024] As the side sheet 7, a water-repellent nonwoven fabric or a hydrophilic nonwoven fabric can be used. For example, to prevent menstrual blood or vaginal discharge from penetrating or to enhance the feel against the skin, it is preferable to use a water-repellent nonwoven fabric coated with a silicone-based or paraffin-based water-repellent agent. Also, to improve the absorbency of menstrual blood, etc. in the wing wg, it is preferable to use a hydrophilic nonwoven fabric as the nonwoven fabric material. As for the type of nonwoven fabric, an air-through nonwoven fabric that is soft, does not easily crease or wrinkle, and is resistant to folding is preferred.

[0025] As shown in Figures 2 and 3, the absorbent body 4 can be configured to include an absorbent body 4a that substantially absorbs bodily fluids and a covering sheet 4b that encloses the absorbent body 4a.

[0026] The materials constituting the absorbent body 4a are not limited as long as they can absorb and retain bodily fluids, but it is preferable that they include cotton-like pulp and a superabsorbent polymer. As the superabsorbent polymer, superabsorbent polymer granules (SAP), superabsorbent polymer fibers (SAF), and combinations thereof can be used. As the pulp, examples include cellulose fibers such as chemical pulp and dissolved pulp obtained from wood, and artificial cellulose fibers such as rayon and acetate. Recycled pulp and recycled fibers can also be used. As raw materials for chemical pulp, hardwoods and softwoods can be used, but softwoods are preferably used because of their long fiber length. The absorbent body 4a can be manufactured by the fiber stacking or airlaid method. Furthermore, as the absorbent body 4a, a thin sheet consisting of a layer of superabsorbent polymer granules and / or superabsorbent polymer fibers sandwiched between sheets of nonwoven fabric or the like, a so-called SAP sheet, can also be used. When an SAP sheet is used, the encasing sheet 4b can be omitted.

[0027] Furthermore, synthetic fibers may be mixed into the absorbent body 4a. As synthetic fibers, polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon, and copolymers thereof can be used, and two of these can also be mixed and used. In addition, composite fibers such as core-sheath fibers, side-by-side fibers, and split fibers, with a high-melting-point fiber as the core and a low-melting-point fiber as the sheath, can also be used. Furthermore, hydrophobic fibers can be surface-treated with a hydrophilizing agent to impart affinity to body fluids.

[0028] The structure in which the absorbent body 4a is wrapped by the covering sheet 4b prevents the fibrous or granular material contained in the absorbent body 4a from spilling out, and also prevents the entire absorbent part 4 from becoming distorted or cracked, thus improving the shape retention of the absorbent part 4. However, the covering sheet 4b is not necessarily required.

[0029] The material of the covering sheet 4b is not particularly limited, but may be nonwoven fabric, paper, etc. As for nonwoven fabrics, air-through nonwoven fabric, spunbond nonwoven fabric, flexible spunbond nonwoven fabric, etc. are used. As for paper, crepe paper is used. When the absorbent body 4a is wrapped by the covering sheet 4b, the back sheet 2 and the covering sheet 4b will be in direct contact within the absorbent article 1. Therefore, from the viewpoint of reducing friction between the back sheet 2 and the absorbent part 4, and consequently friction between the back sheet 2 and the skin-side structure part 15 on the skin side of the back sheet 2, an air-through nonwoven fabric is preferred.

[0030] Furthermore, an intermediate sheet may be provided between the top sheet 3 and the absorbent portion 4 to facilitate the transfer and diffusion of bodily fluids that have reached the top sheet 3 toward the non-skin side and / or in the planar direction. However, the intermediate sheet 5 may be omitted. If an intermediate sheet is provided, the material of the intermediate sheet can be, for example, the same material as the top sheet 3 described above.

[0031] Furthermore, although not shown in Figure 1, a slip-prevention portion (hereinafter also referred to as the slip-prevention portion for the main body, which will be described in detail later) may be provided on the non-skin side of the backsheet 2 of the absorbent article body bd. The slip-prevention portion prevents the absorbent article 1 from shifting away from the underwear when the absorbent article 1 is worn by attaching the slip-prevention portion to the underwear.

[0032] <Regarding the non-fixed and fixed areas> In one embodiment of the present disclosure, the absorbent article 1 has a non-fixed area 25 in the absorbent article body bd where the back sheet 2 and the skin-side structural part 15 directly arranged on the skin side of the back sheet 2 are not fixed.

[0033] In conventional absorbent products, the backsheet and the skin-facing structure are fixed in the thickness direction throughout the entire absorbent product using adhesive or the like. Therefore, the backsheet and the skin-facing structure, for example, the backsheet and the absorbent part, cannot slide relative to each other. Consequently, when a wearer moves their body while wearing a conventional absorbent product, the underwear moves with the body's movement, and the entire absorbent product (the layered structure from the top sheet to the backsheet), which is fixed to the underwear by anti-slip parts, also follows this movement of the underwear. On the other hand, the skin of the body, especially the groin area, does not move much, so the skin-facing surface of the absorbent product moves in a way that rubs against the wearer's skin. Therefore, conventional absorbent products are prone to a decrease in comfort due to friction.

[0034] In contrast, as shown in Figures 1 and 2, in the absorbent article 1 according to one embodiment of the present disclosure, the absorbent article body bd has an unfixed region 25 in which the back sheet 2 and the skin-side structural part 15 directly arranged on the skin side of the back sheet 2 are not fixed. In the cross-sectional view of Figure 2, the back sheet 2 and the absorbent part 4 are shown separated, but this is shown to indicate that there is no other member (including adhesive) interposed between the back sheet 2 and the absorbent part 4, and the back sheet 2 and the absorbent part 4 are in direct contact or can be in direct contact in the thickness direction.

[0035] The non-fixed region 25 is a region in which the backsheet 2 and the skin-side structure 15 are not bonded together by adhesive means including adhesive 8 or means other than adhesive 8, and in which the backsheet 2 and the skin-side structure 15 are relatively slidable. More specifically, it includes a region in which the backsheet 2 and the absorbent portion 4 are not bonded together and are relatively slidable. Furthermore, within the non-fixed region 25, not only the absorbent portion 4 but also the top sheet 3 may be slidable relative to the backsheet 2, or layers other than the absorbent portion 4 and the top sheet 3, such as the side sheet 7, may be slidable relative to the backsheet 2. Thus, within the absorbent article 1, the backsheet 2 can move along the surface facing the skin-side structure 15, and the backsheet 2 can move along the surface facing the backsheet 2 of the skin-side structure 15. As a result, the skin-side structure 15 can follow the skin, and the backsheet 2 can follow the underwear. Therefore, regardless of the movement of the back sheet 2, the skin-side structure 15 can conform well to the wearer's skin while remaining in close contact with it (high conformability to the skin is achieved). As a result, friction between the skin and the skin-side surface of the absorbent article 1 during application is reduced, and a superior wearing comfort can be obtained that could not be achieved by simply modifying the configuration of the top sheet 3.

[0036] In the non-fixed region 25, the back sheet 2 and the skin-side structure 15 are directly laminated, and no other material is interposed between them. Therefore, in the manufacture of the absorbent article 1 according to this embodiment, the number of materials can be reduced, and the manufacturing process can also be simplified.

[0037] In the example shown in Figure 1, the non-fixed area 25 is formed over the entire lateral direction D2 of the absorbent portion 4. This allows the entire lateral direction D2 of the absorbent portion 4 to slide relative to the backsheet 2, further improving the skin conformity of the skin-facing surface of the absorbent article 1. Alternatively, the non-fixed area 25 may be formed over both ends of the lateral direction D2 of the absorbent article body bd. In that case, it is preferable that the edges of the lateral direction D2 of the absorbent article body bd are closed by applying adhesive to the edges or by applying a sealing process such as heat sealing, in the front region F and rear region R in the configuration with wings wg, and over the entire front-to-back direction D1 in the configuration without wings wg.

[0038] Furthermore, as shown in Figures 1 and 2, it is preferable that the outer end of the non-fixed region 25 in the lateral direction D2 and the outer end of the absorbent portion 4 in the lateral direction D2 are separated by a length k in the lateral direction D2. This separation provides play for the absorbent portion 4, making it easier for the absorbent portion 4 to move relative to the backsheet 2, thereby improving the skin-side structure portion 15's conformity to the skin. The length k in the lateral direction D2 between the outer end of the non-fixed region 25 in the lateral direction D2 and the outer end of the absorbent portion 4 in the lateral direction D2 is preferably 0.5 mm or more and 5 mm or less, and more preferably 1 mm or more and 3.5 mm or less.

[0039] Furthermore, if the backsheet 2 and the skin-side structure 15 are relatively slidable, the non-fixed area 25 does not necessarily have to be formed over the entire length of the lateral direction D2. For example, the lateral adhesive 8a may be extended so that the edge of the absorbent part 4 in the lateral direction D2 extends beyond the center, thereby bonding the end of the absorbent part 4 in the lateral direction D2 to the backsheet 2 along the front-rear direction D1. In that case, the length of the lateral direction D2 to which the backsheet 2 and the absorbent part 4 are bonded is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less.

[0040] Furthermore, the non-fixed area 25 may be formed in the central area C, preferably extending over the entire central area C as shown in Figure 1. Since the difference in fit is particularly easily felt by the wearer in the crotch area, the improvement in fit can be more clearly felt by forming the non-fixed area 25 in the central area C that faces the crotch area, more preferably extending over the entire central area C.

[0041] Furthermore, the non-fixed region 25 may extend forward beyond the boundary between the central region C and the front region F. That is, the non-fixed region 25 may also be formed in the front region F. In that case, for example, as shown in Figure 1, the non-fixed region 25 may extend in the front-rear direction D1 to near the center of the front region F in the front-rear direction D1. Furthermore, the non-fixed region 25 may extend backward beyond the boundary between the central region C and the rear region R. That is, the non-fixed region 25 may also be formed in the rear region R. In that case, the non-fixed region 25 may extend backward beyond the boundary between the central region C and the rear region R to a length equal to or greater than the length in the front-rear direction D1 to which the non-fixed region 25 extends forward beyond the rear end of the front region F.

[0042] Areas other than the non-fixed area 25 are fixed areas 21 in which the back sheet 2 and the skin-side structure 15 are bonded together by adhesive 8 or other adhesive means. In the examples shown in Figures 1 and 2, the fixed areas 21 are formed by bonding the back sheet 2 and the skin-side structure 15 to the front area F and the rear area R, respectively, with the main adhesive 8b. In the wings wg, wg as well, the fixed areas 21 are formed by bonding the back sheet 2 and the side sheet 7 together with the side adhesive 8a.

[0043] In this embodiment, the location where the fixed area 21 is formed in the absorbent article body bd may be at least one, preferably both, of the front area F and the rear area R. The smaller the area of ​​the fixed area 21, the larger the area of ​​the non-fixed area 25, which is preferable in that the back sheet 2 and the skin-side structure 15 can slide more easily (with less force) over a wider area, thus improving the skin-following ability of the skin-side structure 15 to the skin. However, the presence of the fixed area 21 is also preferable in that the larger the area of ​​the fixed area 21, the more it is possible to prevent the laminated structure of the absorbent article 1 from breaking and the absorbent article 1 from disintegrating even when a large force is applied to the absorbent article 1, thereby improving the robustness of the absorbent article 1.

[0044] In this specification, "relatively slidable" means that the two members are able to slide relative to each other due to the force applied to the absorbent article when the user of the absorbent article handles it in the normal manner, and that this sliding is perceptible to the user of the absorbent article in the normal manner (i.e., by human senses such as sight and touch). Furthermore, the direction of sliding may be any direction perpendicular to the thickness of the absorbent article 1, and may include one or more directions inclined with respect to the front-to-back direction D1, the side-to-side direction D2, and the front-to-back direction D1 and / or the side-to-side direction D2 of the absorbent article 1. Therefore, even if there is a part within the fixed area 21 where the back sheet 2 and the skin-side structure 15 are not adhered, if they cannot slide relative to each other, that part is not included in the "unfixed area". For example, if the fixed area 21 is formed by applying adhesive in a spiral pattern using a spiral gun or spiral coater, a closed area where adhesive is not attached is formed. However, since the areas within such closed areas where adhesive is not attached are not relatively slidable between the back sheet 2 and the skin-side structure 15, these areas are not included in the non-fixed area 25. The same applies to a fixed area 21 formed by overlapping and applying multiple annular adhesives while shifting them in one direction.

[0045] From the viewpoint of ensuring that the backsheet 2 and the skin-side structure 15 can slide sufficiently relative to each other, the area of ​​the non-fixed area 25 in the overlapping region of the backsheet 2 and the absorbent portion 4, that is, the area of ​​the non-fixed area 25 relative to the area of ​​the absorbent portion 4, is preferably 50% or more, more preferably 70% or more. Having the non-fixed area 25 be 50% or more of the absorbent portion 4 further improves the conformability of the absorbent article 1 to the skin. The area of ​​the non-fixed area 25 in the main body bd, that is, the area of ​​the non-fixed area 25 relative to the area of ​​the main body bd, is preferably 20% or more, more preferably 30% or more.

[0046] Furthermore, the non-fixed area 25 is preferably an area with a certain degree of continuous area so that the back sheet 2 and the skin-side structure 15 can slide sufficiently relative to each other. For example, the non-fixed area 25 is preferably a continuous area where the maximum length in the front-to-back direction D1 is 50 mm or more and the maximum length in the lateral direction D2 is 50 mm or more, and more preferably a continuous area where the maximum length in the front-to-back direction D1 is 60 mm or more and the maximum length in the lateral direction D2 is 60 mm or more. Moreover, the non-fixed area 25 may be a continuous area where the maximum length in the front-to-back direction D1 is greater than or equal to the length in the front-to-back direction D1 of the central area C and the maximum length in the lateral direction D2 is greater than or equal to the length in the lateral direction D2 of the absorbent part 4.

[0047] <Color when viewed from the non-skin side in a used state> Generally, the color of backsheet 2 is white, and its brightness is high. For example, the L color of backsheet 2 itself ＊The value (Lo) is preferably 80 or more, more preferably 85 or more. Therefore, in the used absorbent article in which body fluid, particularly menstrual blood, is absorbed, the color of the body fluid is likely to be seen through from the non-skin side. When replacing the absorbent article, the user discards the used absorbent article. At that time, usually, an operation of folding or rolling up the used absorbent article on the skin side is performed. Even if this operation is performed quickly, the body fluid will inevitably be seen through from the non-skin side of the absorbent article. Depending on the user of the absorbent article, some users may not feel comfortable with the body fluid being seen through from the non-skin side and may feel uncomfortable. Also, although the used absorbent article is folded or rolled up on the skin side, it may be discarded in a dedicated box or the like without being wrapped in a packaging sheet or toilet paper. In that case, it may cause discomfort to the person who discards the contents of the box.

[0048] In contrast, in the present embodiment, after the same amount of coloring liquid is absorbed from the skin side under the same conditions in the non-fixed region 25 and the fixed region 21, respectively, the CIE L ＊ a ＊ b ＊ value (Ln) in the non-fixed region 25 defined in the color system and the L ＊ value (Lf) in the fixed region 21 are compared, and Ln > Lf. Here, the coloring liquid may be colored body fluid (e.g., menstrual blood), commercially available pseudo body fluid (e.g., pseudo menstrual blood), or other coloring liquid. Since the non-fixed region 25 is formed in the central region C, with the above configuration, at least in the central region C, the L ＊ value of the color of the coloring liquid seen through from the non-skin side ＊A higher value (brightness) results in a color that appears closer to white or lighter. The central region C is the region where the absorption of bodily fluids is greatest, including the part Q opposite the bodily fluid outlet. Therefore, when the absorbent article 1 absorbs bodily fluids and becomes a used absorbent article, the bodily fluids that show through from the non-skin side in the central region C, especially menstrual blood, will appear lighter, making the color of the bodily fluids less noticeable and reducing discomfort for those who see the used absorbent article. Furthermore, since the fixed region 21 is formed in the central region C in this embodiment, the above Ln > Lf is obtained when the same amount of colored liquid or bodily fluid is absorbed into the central region of the absorbent article 1 according to this embodiment and the central region of a conventional absorbent article having the same configuration as the absorbent article 1 according to this embodiment except for the absence of a non-fixed region, respectively, when the central region C of the absorbent article 1 according to this embodiment is viewed from the non-skin side, Ln > Lf ＊ The value is L, which is the central region of an absorbent article using conventional technology where the entire region is a fixed area, as viewed from the non-skin side. ＊ This means that the value is greater than the conventional value. In other words, compared to the conventional technology, in this embodiment, even if colored bodily fluids are discharged, the color that is visible through the non-skin side is lighter.

[0049] Furthermore, as mentioned above, the reason why Ln > Lf is that in the non-fixed region 25, the back sheet 2 and the skin-side structure 15 are not fixed together and are not in close contact with each other. Therefore, the liquid diffuses from the top sheet 3 side to the non-skin side of the skin-side structure 15, and it is difficult for the skin-side surface of the back sheet 2 to come into close contact with the liquid that seeps out onto the non-skin side surface of the skin-side structure 15.

[0050] After the same amount of coloring solution was absorbed into the non-fixed region 25 and the fixed region 21 from the skin side under the same conditions, the absorbent article 1 was viewed from the non-skin side, and the L in the non-fixed region 25 was observed. ＊ The value (Ln) and L in the fixed region 21 ＊ The difference from the value (Lf), i.e., Ln-Lf, is preferably 3 or more, and more preferably 5 or more.

[0051] Furthermore, L in the non-fixed region 25 ＊ Value (Ln), L in fixed region 21 ＊The L value (Lf), and the color L of the unused (before coloring solution absorption) backsheet 2 as seen from the non-skin side. ＊ From the value (Lo), L in the non-fixed region 25 due to absorption of the coloring solution. ＊ The rate of decrease in value (Rtn) and L in the fixed region 21 due to absorption of the coloring solution. ＊ When calculating the rate of decrease in value (Rtf), it is possible that Rtn < Rtf. That is, in the non-fixed region 25, the color L of the absorbent article as seen from the non-skin side when an unused absorbent article 1 becomes a used absorbent article that has absorbed body fluids. ＊ The value does not decrease significantly. Therefore, in the non-fixed region 25, and by extension at least in the central region C, the color of bodily fluids that show through the used absorbent material when viewed from the non-skin side is not noticeable. Note that Rtn = (Lo - Ln) / Lo × 100 (%) and Rtf = (Lo - Lf) / Lo × 100 (%).

[0052] Note that L in the non-fixed region 25 ＊ The rate of value decrease (Rtn) and L in the fixed region 21 ＊ The difference from the rate of decline (Rtf) may preferably be 5 points or more, and more preferably 7 points or more.

[0053] <Modifications> The following describes modifications of the absorbent article of this disclosure.

[0054] Figure 4 shows an absorbent article 1 according to a modified example. The example shown in Figure 4 differs from the absorbent article 1 shown in Figure 1 in that the range of the non-fixed area 25 is different and compression grooves (Ef, Ec, Er) that are recessed from the skin side to the non-skin side are formed, but the other configuration is the same as the absorbent article 1 shown in Figure 1. In the absorbent article 1 shown in Figure 4 as well, the back sheet 2 and the skin-side structure part 15 are not fixed to each other, so the absorbent article 1 conforms well to the skin and a product with excellent wearing comfort is provided. Furthermore, when a coloring liquid is absorbed into the non-fixed area 25 and the fixed area 21 under the same conditions, the L in the non-fixed area 25 as seen from the non-skin side of the absorbent article 1 ＊ The value (Ln) is L in the fixed region 21. ＊ Since it is greater than the value (Lf), it can reduce the discomfort experienced when disposing of used absorbent materials.

[0055] In the example shown in Figure 4, the absorbent article 1 may have compression grooves (also called fit embossing) that are recessed from the skin side to the non-skin side, including a front compression groove Ef formed in the front region F, a central compression groove Ec mainly formed in the central region C, and a rear compression groove Er formed in the rear region R. Such compression grooves can be formed by compressing the desired locations from the skin side in the thickness direction after stacking the components of the skin-side structure 15. The presence of compression grooves allows the absorbent article 1 to be easily deformed to conform to the shape of the body when worn, and also allows body fluids to be guided in the desired direction within the skin-side structure 15.

[0056] The rear compression groove Er may include a substantially V-shaped portion Erv having a substantially V-shape with a vertex sp that can be positioned facing the gluteal cleft when worn. The substantially V-shaped portion Erv may include a compression groove having two parts that extend rearward from the vertex sp located in the center of the lateral direction D2, so as to move away from each other from the anterior-posterior centerline CL. The two parts may extend linearly or curved. Furthermore, the rear portions in the direction of extension of the two parts may be curved and terminate facing forward, as shown in Figure 4. Note that the two parts do not necessarily have to be joined at the vertex sp.

[0057] In this embodiment, the non-fixed region 25 is formed beyond the apex sp of the substantially V-shaped portion Erv included in the rear compression groove Er. In other words, the apex sp of the substantially V-shaped portion Erv included in the rear compression groove Er is included in the non-fixed region 25. Generally, bodily fluids tend to accumulate in compression grooves due to capillary action, and especially in the parts where the tips of the compression grooves are connected or in close proximity. Here, when the absorbent article 1 is used overnight or for a long period of time, a large amount of bodily fluid may diffuse into the rear region R. In such cases, bodily fluids tend to accumulate at the apex sp of the substantially V-shaped portion Erv as shown in Figure 4, and furthermore, a large amount of bodily fluid seeps out onto the non-skin side of the skin-side structure portion 15 corresponding to the apex sp. As a result, the color of the bodily fluid becomes particularly noticeable when viewed from the non-skin side of the backsheet 2 at the location corresponding to the apex sp on the non-skin side of the absorbent article 1. However, by, for example, extending the non-fixed area 25 to the vicinity of the vertex sp, and in particular by ensuring that the vertex sp is included in the non-fixed area 25, the color of the bodily fluids can be made less noticeable at the position corresponding to the vertex sp when the used absorbent material is viewed from the non-skin side, thereby improving the effect of reducing discomfort.

[0058] Figure 5 shows an absorbent article 1 according to another modified example. The example shown in Figure 5 differs from the absorbent article 1 shown in Figure 1 in that the range of the non-fixed area 25 is different, but the other configurations are the same as those of the absorbent article 1 shown in Figure 1. Figure 5 also clearly shows the arrangement of the anti-slip portion 9. In the absorbent article 1 shown in Figure 5, there is also a non-fixed area 25 in which the back sheet 2 and the skin-side structure portion 15 are not fixed, so the absorbent article 1 conforms well to the skin and a product with excellent wearing comfort is provided. Furthermore, when the coloring liquid is absorbed into the non-fixed area 25 and the fixed area 21 under the same conditions, the L in the non-fixed area 25 as seen from the non-skin side of the absorbent article 1 ＊ The value (Ln) is L in the fixed region 21. ＊ Since it is greater than the value (Lf), it can reduce the discomfort experienced when disposing of used absorbent materials.

[0059] The material constituting the anti-slip portion 9 is not particularly limited, as long as it can suppress the shifting of the absorbent article 1 against the underwear when it is attached to the underwear, and allows the absorbent article 1 to be easily removed from the underwear after use. The anti-slip portion 9 is preferably formed as a layer of adhesive, and it is preferable to use a hot-melt type adhesive. The main components of the anti-slip portion 9 can be a styrene polymer, a tackifier, a plasticizer, or a combination thereof.

[0060] Examples of styrene-based polymers include styrene-ethylene-butylene-styrene block copolymers, styrene-butylene-styrene block copolymers, styrene-isobutylene-styrene copolymers, and styrene-butadiene-styrene block copolymers, and one or more of these can be used. Among these, styrene-butadiene-styrene block copolymers are preferred due to their good thermal stability. In addition, tackifiers and plasticizers that are solid at room temperature can be used. Examples of tackifiers include C5 petroleum resins, C9 petroleum resins, dicyclopentadiene petroleum resins, rosin petroleum resins, polyterpene resins, and terpene phenol resins. Examples of plasticizers include monomer plasticizers such as triflethyl phosphate, dibutyl phthalate, and dioctyl phthalate, as well as polymer plasticizers such as vinyl polymers and polyesters.

[0061] The arrangement of the anti-slip portion 9 is not particularly limited and may be a known arrangement. The anti-slip portion 9 only needs to be provided within the range of the absorbent article body bd in a plan view, and may extend beyond the range in which the absorbent portion is located. However, it is preferable that the anti-slip portion 9 be provided within the range in which the absorbent portion 4 is located, as this allows the body bd to be more stably fixed to the underwear. The anti-slip portion 9 may be provided over the entire range in which the absorbent portion 4 is located, or it may be provided in a part of the above range. In that case, the anti-slip portion 9 may be provided continuously or discontinuously.

[0062] For example, the anti-slip portion 9 may include a plurality of strip-shaped anti-slip portions 9 that extend along the front-to-back direction D1 and are spaced apart from each other in the lateral direction D2, as shown in Figure 7. In such a configuration, the absorbent article body bd can be continuously fixed to the underwear along the front-to-back direction D1, and if the anti-slip portion 9 is an adhesive layer, the anti-slip portions 9 can be arranged over a wide area without the adhesive force of the anti-slip portion 9 becoming excessively strong. In the example shown in Figure 7, three anti-slip portions 9 are provided along the front-to-back direction D1, but the number of anti-slip portions 9 is not limited to three; there may be one, two, or four or more. In a configuration that includes strip-shaped anti-slip portions 9 extending along the front-to-back direction D1, it is preferable to have anti-slip portions 9 that overlap with the front-to-back center line CL, as this allows the absorbent article body bd to be fixed to the underwear more stably.

[0063] The anti-slip portion 9 may include a plurality of strip-shaped anti-slip portions that extend along the lateral direction D2 and are spaced apart from each other in the front-rear direction D1. In such an example, the absorbent article body bd can be continuously fixed to the underwear along the lateral direction D2, and if the anti-slip portion 9 is an adhesive layer, the anti-slip portion 9 can be placed over a wide area without the adhesive force of the anti-slip portion 9 becoming excessively strong.

[0064] As shown in Figure 5, when a plurality of strip-shaped anti-slip portions 9 are provided that extend along the front-to-back direction D1 and are separated from each other in the lateral direction D2, it is preferable that the anti-slip portions 9 are provided over the entire front-to-back direction D1 of the non-fixed area 25. This increases the effect of making the color of the bodily fluids that have been absorbed into the used absorbent article less noticeable from the non-skin side in the non-fixed area 25. The reason for this is thought to be as follows: Normally, when the absorbent article 1 is removed from the underwear during replacement, the skin-side structure 15 is pulled away from the underwear, but the backsheet 2 tries to remain on the underwear side due to the anti-slip portions 9. As a result, a space is created between the backsheet 2 and the skin-side structure 15 in the non-fixed area 25, and a distance is created between the liquid that has seeped out to the non-skin side of the skin-side structure 15 and the backsheet 2, so the liquid is less likely to show through from the backsheet side. Furthermore, since the anti-slip portion 9 is provided on the non-skin side of the back sheet 2, an additional layer is placed on the non-skin side, making the color of bodily fluids less noticeable when viewed from the non-skin side.

[0065] Therefore, in terms of making bodily fluids that show through to the non-skin side in the non-fixed area 25 less noticeable, the ratio of the total area of ​​the anti-slip portion 9 to the area of ​​the non-fixed area 25 in a plan view is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more, 60% or more, or 70% or more.

[0066] Figures 6 and 7 show another modified example of the absorbent article 1. The examples shown in Figures 6 and 7 are the same as the absorbent article 1 shown in Figure 1, except that the extent of the non-fixed area 25 is different. In the absorbent articles shown in Figures 6 and 7, there is also a non-fixed area 25 in which the back sheet 2 and the skin-side structure 15 are not fixed, so the absorbent article 1 conforms well to the skin and a product with excellent wearing comfort is provided. Furthermore, when the coloring liquid is absorbed into the non-fixed area 25 and the fixed area 21 under the same conditions, the L in the non-fixed area 25 as seen from the non-skin side of the absorbent article 1 ＊ The value (Ln) is L in the fixed region 21. ＊Since it is greater than the value (Lf), it can reduce the discomfort when disposing of used absorbent material. Figures 6 and 7 also show the fold lines (FL1, FL2, FLa) for folding the absorbent material 1.

[0067] Absorbent article 1 is generally provided as an individual package wrapped in a packaging sheet or the like. In this case, the absorbent article 1, which is long in the front-to-back direction D1, is folded in the front-to-back direction D1 together with the packaging sheet. By folding the absorbent article 1, it can be provided in a compact state that is convenient for carrying, etc.

[0068] In the example shown in Figure 6, the front of the absorbent article 1 is folded towards the skin along the first fold line FL1 along the lateral direction D2, and similarly, the rear of the absorbent article 1 is folded towards the skin along the second fold line FL2 along the lateral direction D2. Here, both the first fold line FL1 and the second fold line FL2 may be formed along the boundary between the non-fixed region 25 and the fixed region 21. That is, the first fold line FL1 may be formed along the front end of the non-fixed region 25, and the second fold line FL2 may be formed along the rear end of the non-fixed region 25. This allows the absorbent article 1 to be folded at a position where its rigidity changes, making it easier to fold the absorbent article 1 and preventing wrinkles near the fold lines.

[0069] Furthermore, where fold lines are typically formed, the back sheet 2 and the skin-side structure 15 tend to adhere closely together. As a result, bodily fluids that seep out onto the non-skin side of the skin-side structure 15 come into close contact with the skin-side surface of the back sheet 2, making the color of the bodily fluids more noticeable. In contrast, as shown in Figure 6, by positioning the fold lines along the boundary between the non-fixed area 25 and the fixed area 21, the area where the back sheet 2 and the skin-side structure 15 come into close contact becomes the edge of the non-fixed area 25 in the front-to-back direction D1. This avoids hindering the effect of making bodily fluids less noticeable when viewed from the non-skin side in the non-fixed area 25.

[0070] In the example shown in Figure 6, the absorbent article 1 was folded in three inwards, but in the example shown in Figure 7, the absorbent article 1 is folded in four. In the example shown in Figure 7, the front of the absorbent article 1 is folded towards the skin along the first fold line FL1 along the horizontal direction D2, and the rear of the absorbent article 1 is folded towards the skin along the second fold line FL2 along the horizontal direction D2. However, before folding along the second fold line FL2, the rear of the absorbent article 1 can be pre-folded towards the skin or non-skin side along the auxiliary fold line FLa located behind the second fold line FL2. With the four-fold shown in Figure 7, the absorbent article 1 can be provided in an even more compact state.

[0071] In Figure 7, the second fold line FL2 is located further forward than the second fold line FL2 shown in Figure 6. In the example shown in Figure 7, the first fold line FL1 and the second fold line FL2 are formed along the boundary between the non-fixed region 25 and the fixed region 21, so the same effects as those described with reference to Figure 6 can be obtained.

[0072] The absorbent article 1 described above was a product with wings, but the same effect can be obtained with a product without wings using the above configuration. However, the product with wings allows the back sheet 2 to be firmly fixed to the underwear, making it easier for the back sheet 2 and the skin-side structure 15 to slide relative to each other, thus improving the wearing comfort.

[0073] Furthermore, the technology disclosed herein is applicable to sanitary napkins, panty liners, incontinence pads, and diapers, but is particularly suitable for use with sanitary napkins. Since sanitary napkins are often used with the skin side in close contact with the genital area, friction between the absorbent material and the skin is more likely to occur due to the wearer's movements compared to other absorbent items. Therefore, by using the embodiment of the disclosed invention in sanitary napkins, a better wearing experience is more easily felt compared to conventional products.

[0074] The embodiments of this disclosure will be described in more detail below with reference to examples.

[0075] <Sample> As a sample, we used a sanitary napkin that has the same basic structure as a commercially available conventional product (manufactured by Daio Paper Corporation, with wings, 32.5 cm), but has a non-fixed area and a fixed area as explained with reference to Figures 1 to 3.

[0076] <Test Method> After absorbing the coloring solution into the non-fixed and fixed regions of the same sample under the same conditions, the sample was taken from the backsheet side. ＊ The values ​​were measured. The colored solution was absorbed via an injection tube, a dedicated device. Figure 8 shows a general perspective view and a plan view of the injection tube 60. The injection tube 60 has a structure in which a recess 62 is located in the center and a through hole 64 is provided on its bottom surface. The through hole 64 on the bottom surface of the injection tube 60 has the shape of three through slits that intersect each other at the center of the bottom surface, and the length of each slit was 23 mm. First, the injection tube 60 was placed on the skin side of the sanitary napkin sample, (i) opposite the bodily fluid outlet in the non-fixed area, and 10 mL of blue colored solution at 25°C was injected through the injection tube 60. Subsequently, the position of the injection tube 60 was changed, and (ii) the colored solution was injected in the same manner into the lateral center of the front fixed area. The colored solution used was prepared by dissolving 0.2 g of blue powder (manufactured by Beni Fuji Chemical Industry Co., Ltd., Food Blue No. 1) in 1 L of water. After injecting (i) and (ii), the material was left for 3 minutes to allow the liquid to be fully absorbed into the absorbent material. Then, using a spectrophotometric colorimeter (NF555, manufactured by Nippon Denshoku Industries Ltd.), the L in the non-skin side of the sanitary napkin sample was measured. ＊ (ii) the value (Ln), and L in the fixed region ＊ The values ​​(Lf) were measured for each. Note that even before the coloring solution was absorbed, L was measured from the non-skin side. ＊ The value (Lo) was measured. All measurements were taken in a dark place, with the napkin sample suspended so that the front of the absorbent material was facing upwards and the back was facing downwards.

[0077] The results are shown in Table 1.

[0078]

[0079] As shown in Table 1, after absorbing the coloring solution, the non-skin side L of the sanitary napkin sample ＊The values ​​were higher in the non-fixed region than in the fixed region (Ln > Lf), indicating that the non-fixed region was closer to white. Furthermore, visual observation of the non-skin side of the sanitary napkin sample confirmed that the color of the translucent coloring liquid was less noticeable in the non-fixed region than in the fixed region.

[0080] Furthermore, in both the non-fixed and fixed regions, L is absorbed by the coloring solution. ＊ When the rate of decrease in value was calculated, L in the non-fixed region ＊ The rate of decrease in value Rtn (= (Lo - Ln) / Lo × 100 (%)) is L in the fixed region. ＊ The value reduction rate Rtf (= (Lo - Lf) / Lo × 100 (%)) was smaller. In other words, in the non-fixed region, it was found that the brightness of the non-skin side did not decrease much before and after absorption. In this experiment, L in the non-fixed region ＊ The rate of decrease in value Rtn and L in the fixed region ＊ The difference from the rate of decrease (Rtf) was 7 points.

[0081] Although the present disclosure has been described above based on embodiments, the present disclosure is not limited to these embodiments. The above embodiments can be modified, altered, replaced, added, deleted, and combined in various ways within the scope of the claims, and these also fall within the technical scope of the present disclosure. Furthermore, the above-mentioned components can be combined in any way.

[0082] The specific aspects of this disclosure are further described below.

[0083] (Note 1) The embodiment of Note 1 is an absorbent article having an impermeable backsheet and a skin-side structural part disposed on the skin side of the backsheet, wherein the skin-side structural part includes an absorbent part directly disposed on the skin side of the backsheet and a permeable top sheet disposed on the skin side of the absorbent part, the absorbent article having a central region including a body fluid outlet facing part that faces the body fluid outlet of the wearer when worn, a front region in front of the central region and a rear region behind the central region, the backsheet and the skin-side structural part are not fixed and the backsheet and the skin-side structural part are relatively slidable, having a non-fixed region formed in the central region and a fixed region other than the non-fixed region, and after the same amount of coloring liquid is absorbed from the skin side into the non-fixed region and the fixed region respectively, the absorbent article is viewed from the non-skin side and CIE L ＊ a ＊ b ＊ L defined by the color system * The value is Ln, and L in the fixed region. ＊ Let the value be Lf, and Ln > Lf.

[0084] Absorbent items are used by attaching them to underwear with the backsheet side facing outwards. When the wearer's body moves, the underwear moves in accordance with that movement, and the absorbent item also moves in accordance with the movement of the underwear (including deformation and / or shifting). In this case, even though the absorbent item moves in accordance with the movement of the underwear, the skin in the crotch area to which the skin-facing side of the absorbent item is in contact does not move much, so friction is likely to occur between the skin-facing side (topsheet side) of the absorbent item and the skin in contact with that side. For this reason, especially when the absorbent item is worn for a long time or when there is vigorous movement, the feeling of wearing it may be impaired due to friction.

[0085] In contrast, the absorbent article according to the embodiment described in Appendix 1 above has an unfixed region where the back sheet and the skin-side structure are not fixed, and is configured so that the back sheet and the skin-side structure are relatively slidable. Therefore, one of the opposing back sheets and skin-side structures can move independently along the surface relative to the other. Thus, even if the back sheet moves in accordance with the movement of the underwear while the absorbent article is in close contact with the wearer's skin, the movement of the back sheet is not directly transmitted to the skin-side structure, preventing the absorbent article from rubbing against the skin. In other words, because the components inside the absorbent article are relatively slidable, even if the back sheet moves in accordance with the underwear, the skin-side surface of the absorbent article can follow the wearer's skin and maintain close contact with the skin, making it difficult for friction to occur between the absorbent article and the skin, thus improving the wearing comfort.

[0086] Furthermore, in this embodiment, after the same amount of coloring liquid is absorbed from the skin side into the non-fixed area and the fixed area, the absorbent article is viewed from the non-skin side, and the L in the non-fixed area is measured. ＊ The value (Ln) is L in the fixed region. ＊ The value (Lf) is higher than expected. This is because, in the non-fixed area, the backsheet and the skin-side structure are not fixed together, and they are not in constant overall contact. As a result, the liquid diffuses from the topsheet to the skin-side structure, and even if it seeps onto the non-skin side of the skin-side structure (for example, the non-skin side of the absorbent part), the skin-side surface of the backsheet does not adhere closely to the non-skin side of the skin-side structure where the liquid has seeped out. Therefore, in the used state of the absorbent article according to this embodiment, the color of the bodily fluids viewed from the non-skin side of the absorbent article appears lighter in the non-fixed area. Consequently, when disposing of a used absorbent article, the bodily fluids visible through the non-skin side of the absorbent article are less noticeable, reducing discomfort during disposal.

[0087] (Note 2) In the embodiment of Note 2, when viewed from the non-skin side of the absorbent article, CIE L before absorbing the coloring liquid ＊ a ＊ b ＊ L defined by the color system ＊ Let the value be Lo, and L in the non-fixed region.＊ Value reduction rate Rtn = (Lo - Ln) / Lo × 100 (%), L in the fixed region ＊ If the rate of decrease in value Rtf = (Lo - Lf) / Lo × 100 (%), then Rtn < Rtf.

[0088] According to the embodiment described in Appendix 2 above, in the non-fixed region, L after absorption of body fluids ＊ Since the value does not decrease significantly compared to before fluid absorption, even when a large amount of fluid is absorbed over a larger area, the fluid is less noticeable when viewed from the non-skin side.

[0089] (Note 3) In the embodiment of Note 3, the absorbent article has a front-to-back direction corresponding to the front-to-back direction of the body when worn, and a lateral direction perpendicular to the front-to-back direction, and the non-fixed region is formed over the entire front-to-back direction of the central region and over the entire lateral direction of the absorbent portion.

[0090] According to the embodiment described in Appendix 3 above, since the non-fixed area is formed over the entire front-to-back direction of the central area and over the entire lateral direction of the absorbent part, the back sheet and the skin-side structure can easily slide relative to each other over a large range in the lateral direction, and the skin-side surface of the absorbent article conforms more easily to the wearer's skin (hereinafter also referred to as conformability). Furthermore, since the central area is an area where the wearer is likely to feel friction between the absorbent article and their skin, this embodiment makes it even easier to feel an improvement in wearing comfort.

[0091] Furthermore, since the central region includes the area opposite the bodily fluid drainage port, when a used absorbent material is viewed from the non-skin side, the bodily fluids are primarily visible through the central region. Therefore, having a non-fixed area in the central region where the color of the bodily fluids is faintly visible from the non-skin side improves the effect of reducing discomfort by making the bodily fluids less noticeable when the absorbent material is viewed from the non-skin side during disposal.

[0092] (Note 4) In the embodiment of Note 4, a compression groove is provided that is recessed from the skin side to the non-skin side, and the compression groove includes a rear compression groove in the rear region that has a substantially V shape with a apex at the front, and the non-fixed region extends to a position beyond the apex to the rear.

[0093] According to the embodiment described in Appendix 4 above, a rear compression groove having a shape including a roughly V-shape with its apex facing forward is provided in the rear region facing the buttocks, allowing the absorbent material to be deformed to conform to the shape of the buttock crease, which gradually becomes shallower towards the rear. In this embodiment with a rear compression groove including a roughly V-shape, if bodily fluids move from the central region to the rear region due to nighttime or prolonged use, the bodily fluids tend to accumulate particularly at the apex of the roughly V-shape due to capillary action. As a result, a large amount of bodily fluid seeps out onto the non-skin side surface of the non-skin side structure corresponding to the apex, and this bodily fluid becomes more noticeable when the backsheet is in close contact with it. Consequently, in the rear region where the roughly V-shaped compression groove is provided, the bodily fluids visible from the non-skin side become more noticeable. In contrast, by extending the non-fixed region beyond the apex to a position further rearward, the color of the bodily fluids as seen from the non-skin side can be made less noticeable even in the rear region, reducing discomfort.

[0094] (Note 5) In the embodiment of Note 5, the back sheet is provided with a non-skin side portion for securing the absorbent article to the underwear when worn, and the non-slip portion includes a plurality of continuous strip-shaped non-slip portions in the front-to-back direction, and the strip-shaped non-slip portions are provided over the entire front-to-back direction of the non-fixed area.

[0095] According to the embodiment described in Appendix 5 above, the non-skin side of the backsheet is provided with multiple continuous, band-shaped anti-slip sections in the front-to-back direction. This securely fixes the absorbent article to the underwear in the front-to-back direction, preventing the absorbent article from shifting away from the underwear and preventing leakage of bodily fluids. Furthermore, when the absorbent article is removed from the underwear during replacement, the skin-side structure is pulled away from the underwear, but the backsheet tends to remain attached to the underwear due to the anti-slip sections. As a result, a space is created between the backsheet and the skin-side structure in the non-fixed area, and a distance is created between the liquid seeping from the non-skin side of the skin-side structure and the backsheet, making the liquid less visible from the backsheet side. Moreover, since the non-skin side of the non-fixed area has anti-slip sections, forming an additional layer on the non-skin side, the color of the bodily fluids, which is already less noticeable in the non-fixed area, becomes even less noticeable.

[0096] (Note 6) In the embodiment of Note 6, the fixed area is provided in front of and behind the non-fixed area, the absorbent article is folded towards the front skin along the fold line along the transverse direction, and the fold line is formed along the boundary between the non-fixed area and the fixed area.

[0097] According to the embodiment described in Appendix 6 above, when individually packaging absorbent articles, the absorbent articles can be folded along fold lines in the horizontal direction, thereby providing the absorbent articles as compact individual packaging. Furthermore, by positioning the fold lines along the boundary between the non-fixed area and the fixed area, folding becomes easier. In addition, normally, at the location where the fold lines are formed, the back sheet and the skin-side structure tend to adhere closely, and the non-skin side of the skin-side structure from which bodily fluids have seeped out tends to come into close contact with the skin-side surface of the back sheet. However, according to this embodiment, the folding position, which is a place where the back sheet and the skin-side structure tend to adhere closely, is at the front-to-back edge of the non-fixed area, thus preventing the effect of making bodily fluids less noticeable from the non-skin side in the non-fixed area from being hindered.

[0098] This application claims priority based on Japanese Patent Application No. 2024-169799, filed on 30 September 2024, the entire contents of which are incorporated herein by reference.

[0099] 1 Absorbent article 2 Back sheet 3 Top sheet 4 Absorbent body 4a Absorbent body 4b Wrapping sheet 7 Side sheet 8 Adhesive 8a Side adhesive 8b Body adhesive 9 Anti-slip part for body (anti-slip part) 15 Skin-side structure 21 Fixed area 25 Non-fixed area 60 Injection tube bd Absorbent article body C Central area CL Front-to-back center line D1 Front-to-back direction (longitudinal direction) D2 Lateral direction (short direction) F Front area Q Opposite part of body fluid outlet wg Wing

Claims

1. An absorbent article having an impermeable backsheet and a skin-side structural part disposed on the skin side of the backsheet, wherein the skin-side structural part includes an absorbent part directly disposed on the skin side of the backsheet and a permeable top sheet disposed on the skin side of the absorbent part, the absorbent article having a central region including a body fluid outlet facing portion that faces the wearer's body fluid outlet when worn, a front region forward of the central region and a rear region backward of the central region, the backsheet and the skin-side structural part are not fixed, and the backsheet and the skin-side structural part are relatively slidable, having a non-fixed region formed in the central region and a fixed region other than the non-fixed region, and after absorbing the same amount of coloring liquid from the skin side into the non-fixed region and the fixed region respectively, the absorbent article is viewed from the non-skin side and CIE L ＊ a ＊ b ＊ L in the non-fixed region defined by the color system * The value is Ln, and L in the fixed region. ＊ An absorbent article whose value is Lf, and where Ln > Lf.

2. When viewed from the non-skin side of the absorbent article, the L value in the CIE La b color system before absorbing the coloring liquid is defined as Lo, and the L value reduction rate Rtn = (Lo - Ln) / Lo × 100 (%) in the non-fixed region, and the L value reduction rate Rtf = (Lo - Lf) / Lo × 100 (%) in the fixed region. The absorbent article according to claim 1, wherein Rtn < Rtf. ＊ a ＊ b ＊ value in the color system is Lo, and the L value in the non-fixed region ＊ is Lo, and the L value reduction rate Rtn = (Lo - Ln) / Lo × 100 (%) in the non-fixed region, and the L value in the fixed region ＊ is Lo, and the L value reduction rate Rtf = (Lo - Lf) / Lo × 100 (%) in the fixed region. When the absorbent article according to claim 1 is such that Rtn < Rtf. ＊ value reduction rate Rtf = (Lo - Lf) / Lo × 100 (%), the absorbent article according to claim 1, wherein Rtn < Rtf.

3. The absorbent article according to claim 1 or 2, wherein the absorbent article has a front-to-back direction corresponding to the front-to-back direction of the body when worn, and a lateral direction perpendicular to the front-to-back direction, and the non-fixed region is formed over the entire front-to-back direction of the central region and over the entire lateral direction of the absorbent portion.

4. The absorbent article according to claim 3, wherein a compression groove is provided that is recessed from the skin side to the non-skin side, the compression groove includes a rear compression groove in the rear region that has a substantially V-shape with a apex at the front, and the non-fixed region extends to a position beyond the apex at the rear.

5. The absorbent article according to claim 3, wherein the non-skin side of the back sheet is provided with an anti-slip portion for securing the absorbent article to underwear when worn, the anti-slip portion includes a plurality of continuous strip-shaped anti-slip portions in the front-to-back direction, and the strip-shaped anti-slip portions are provided over the entire front-to-back direction of the non-fixed area.

6. The absorbent article according to claim 3, wherein the fixed area is provided in front of and behind the non-fixed area, the absorbent article is folded towards the front skin along the fold line along the transverse direction, and the fold line is formed along the boundary between the non-fixed area and the fixed area.

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