Absorbent article

Abstract

[Problem] To suppress a reduction in diffusion performance due to a slit being crushed in an absorbent layer. [Solution] The problem is solved as follows: an absorbent body 56 spanning from a front portion F to a back portion B is formed by two layers of absorbent layers 55, an absorbent layer 55a with a slit 40 is provided with a slit 40 that is continuous in a longitudinal direction LD without branching, and the two lateral edges 59 of the slit 40 are spaced apart in a width direction WD in an unfolded state and have a first portion 40a where a spacing d1 between the two lateral edges 59 of the slit 40 in the width direction WD is the minimum spacing and a second portion 40b where a spacing d2 in the width direction WD is the maximum spacing wider than in the first portion 40a. With this arrangement, even if the absorbent body 56 is compressed in the width direction WD and the two lateral edges 59 of the slit 40 come into contact, the gap of the slit 40 is maintained in the portion other than the first portion 40a.

Description

absorbent articles

[0001] The present invention relates to an absorbent article having an absorbent body with slits.

[0002] In absorbent articles such as various general disposable diapers (pad type, tape type, pants type, etc.), sanitary napkins, etc., it is possible to absorb more excreted liquid such as urine by spreading the excreted liquid more widely. For example, if a slit extending in the front-rear direction is provided in the middle region of the absorber in the width direction, the excreted liquid is guided in the front-rear direction through the slit, allowing a wider area of ​​the absorber to be used for absorption (see, for example, Patent Documents 1 and 2).

[0003] However, because an absorbent article is held between the wearer's legs, when the wearer has their legs closed, the portion having the absorbent body is compressed in the width direction, which inevitably reduces the area of ​​the slit. If the slits in conventional absorbent articles have both side edges that are parallel and linear along the front-to-back direction, when the portion having the absorbent body is compressed in the width direction, the both side edges of the slit come into contact with each other, causing the slit to disappear partially or almost entirely, resulting in a problem of reduced diffusion performance.

[0004] JP 2012-143535 A JP 2012-245236 A

[0005] Therefore, a main object of the present invention is to suppress the deterioration of diffusion performance due to the collapse of the slits.

[0006] The above-mentioned problems are solved by the absorbent article described below. <First Aspect> An absorbent article comprising: a crotch region, front and rear regions extending to the front and rear of the crotch region, an absorbent body including at least one absorbent layer extending from the front to the rear regions and having a slit provided at least in the crotch region that is not branched and extends in the front-to-rear direction, and a liquid-permeable top sheet provided on the front side of the absorbent layer, wherein both side edges of the slit are spaced apart in the width direction over the entire front-to-rear direction in an unfolded state, and the slit has, in an unfolded state, a first portion where the widthwise spacing between both side edges of the slit is minimum, and a second portion where the widthwise spacing between both side edges of the slit is maximum and wider than that of the first portion.

[0007] (Effects) In this absorbent article, if the portion having the absorbent body is not compressed in the width direction, or if it is compressed, the side edges of the slit do not come into contact at all, the entire front-to-back direction of the slit contributes to improving diffusion performance. Even if the portion having the absorbent body is compressed in the width direction and the side edges of the slit come into contact, the side edges of the first portion come into contact first, preventing further compressive deformation in the width direction. This makes it easier to maintain the slit gap (the distance between the side edges) in portions other than the first portion (including the second portion). As a result, this absorbent article can prevent a decrease in diffusion performance due to slit collapse.

[0008] <Second Aspect> The absorbent article of the first aspect, wherein the slit has the first portions and the second portions alternately and repeatedly, and the ratio of the dimension of the slit in the front-to-back direction other than the first portions to the dimension of the slit in the front-to-back direction is 50 to 80%.

[0009] (Operation and Effect) In order to achieve both the function of preventing the slit from collapsing by the first portion and the diffusion performance by the portion other than the first portion, it is desirable to have a configuration like this mode.

[0010] <Third Aspect> The absorbent article of the first or second aspect, wherein both side edges of part or all of the slit are wavy portions having amplitude in the width direction, and the wavy portion on one side edge of the slit and the wavy portion on the other side edge of the slit have the same waveform but are in opposite phase or out of phase with each other.

[0011] (Effects) The shape of the side edges of the slit is not particularly limited as long as it has the first and second parts described above, but it is preferable to have wavy parts with the same waveform on both side edges as in this embodiment, as this improves the deformation characteristics and appearance of the absorbent article.

[0012] <Fourth Aspect> The absorbent article of the first or second aspect, wherein one of both side edges of a part or all of the slit is a wavy portion having amplitude in the width direction, and the other side edge is linear.

[0013] (Effects) In the third aspect, when one side of the absorbent layer having a slit is shifted in the front-to-back direction relative to the other side across the slit and the slit is compressed in the width direction, there is a risk that the wavy portions will interlock and the crush prevention function of the first portion will not be exerted. However, when configured as in this aspect, such interlocking will not occur, which is preferable.

[0014] <Fifth Aspect> The absorbent article of the first or second aspect, wherein one of both side edges of part or all of the slit is a first wavy portion having a widthwise amplitude, and the other side edge is a second wavy portion having a smaller amplitude than the first wavy portion.

[0015] (Effects) In the third aspect, when one side of the absorbent layer having a slit is shifted in the front-to-back direction relative to the other side across the slit and the slit is compressed in the width direction, the wavy portions may interlock and the crush prevention function of the first portion may not be exerted. However, when configured as in this aspect, the portions do not interlock completely and a gap remains between the first and second wavy portions, which is preferable.

[0016] <Sixth Aspect> The absorbent article of any one of the first to fifth aspects, wherein the absorber has an absorbent layer having the slit and an absorbent layer having no slit, and the absorbent layer having no slit has a length spanning the entire length of the slit in the front-to-rear direction and a width spanning both sides of the slit in the width direction.

[0017] (Effects) When an absorbent body includes only one absorbent layer having a slit, the slit is easily compressed in the width direction. However, when the absorbent body has an absorbent layer having a slit and an absorbent layer without a slit as in the present embodiment, the absorbent layer without a slit resists deformation, making the absorbent body as a whole less likely to be compressed in the width direction, and not only making the slit less likely to be crushed, but also making it less likely that one side of the absorbent layer with a slit will shift in the front-to-back direction relative to the other side across the slit, which is preferable.

[0018] <Seventh Aspect> The absorbent article of the sixth aspect, wherein the absorbent layer without a slit is provided directly below the absorbent layer with a slit, the absorbent layer without a slit has a groove provided on a surface thereof, and a part or all of the groove overlaps with the slit except for the first portion.

[0019] (Effects) As described above, when the two side edges of the first portion of the slit come into contact, the contact area inhibits the flow of excrement into the slit and the diffusion of excrement along the slit. In contrast, by forming a groove on the surface of the absorbent layer directly below the slit, as in this embodiment, and configuring the groove to overlap a portion or all of the groove with a portion other than the first portion of the slit (including the second portion), even when the two side edges of the first portion of the slit come into contact, excrement that has flowed into the slit in a portion other than the first portion can diffuse through the groove, thereby suppressing a decrease in diffusibility compared to a case where such a groove is not present. Note that "the groove and the slit overlap" means that the bottom of the groove overlaps between the two side edges of the slit.

[0020] <Eighth Aspect> The absorbent article according to the seventh aspect, wherein the grooves are not provided in an area of ​​60% or more in the front-to-rear direction of the crotch portion.

[0021] (Operation and Effect) When grooves are provided in the absorbent layer, the amount of absorption by the absorbent layer decreases, so it is desirable to limit the range in which the grooves are provided as in this embodiment.

[0022] <Ninth Aspect> The absorbent article according to the seventh or eighth aspect, wherein the groove extends across both the front and rear of the first portion of the slit.

[0023] (Effect) When the grooves are arranged in this manner, even if the two side edges of the first part of the slit come into contact, the grooves act as tunnels connecting the gaps on both the front and back sides of the first part, thereby suppressing the decrease in diffusion compared to when such grooves are not present.

[0024] <Tenth Aspect> The absorbent article according to any one of the first to ninth aspects, wherein the slit is continuous from the front end to the rear end of the absorbent layer having the slit.

[0025] (Effects) When the slits are continuous (pierce through) from the front end to the rear end of the absorbent layer as in this embodiment, the slits are particularly prone to being compressed in the width direction. Therefore, each of the above-mentioned embodiments is particularly significant when such slits are present.

[0026] The present invention provides advantages such as being able to suppress a decrease in diffusion performance due to collapse of the slits.

[0027] 1. A plan view showing the inner surface of a pad-type disposable diaper. 1-1 cross-sectional view of FIG. 1. 2-2 cross-sectional view of FIG. 1. 3-3 cross-sectional view of FIG. 1. 4-4 cross-sectional view of FIG. 1 in the seventh embodiment. 2. A plan view of an absorbent body. 3. A plan view of various absorbent layers having slits. 4. A plan view of an absorbent layer showing a state in which one side and the other side of the slit in the absorbent layer are shifted in the front-to-rear direction. 5. A plan view of an absorbent layer showing a state in which the portion having the absorbent body is compressed in the width direction and both side edges of the slit are in contact. 6. A plan view of various absorbent layers having grooves and no slits. 7. A plan view of various absorbent layers having grooves and no slits. 8. A cross-sectional view corresponding to the 1-1 cross-sectional view of FIG. 1, showing another example. 9. A plan view of an absorbent layer of the example shown in FIG. 12. 10. A plan view of another example of an absorbent layer having slits.

[0028] A pad-type disposable diaper will be described in detail below as an example of an absorbent article, with reference to the accompanying drawings. Adjacent components in the thickness direction may be fixed or joined as needed, in addition to the fixed or joined portions described below, in a manner similar to that of known diapers. The dotted patterns indicate adhesives, such as hot melt adhesives, used as the fixing or joining means. Hot melt adhesives can be applied by known methods, such as slot coating, continuous or dotted bead coating, spiral, Z-shaped, or wavy spray coating, or pattern coating (transfer of hot melt adhesive using a relief printing method). Alternatively or in addition to this, hot melt adhesive can be applied to the outer periphery of the elastic member to fix the elastic member to an adjacent member. Hot melt adhesives include, for example, EVA-based, adhesive rubber-based (elastomer-based), polyolefin-based, and polyester / polyamide-based adhesives, but are not limited thereto. Material welding, such as heat sealing or ultrasonic sealing, can also be used to fix or join the components. In areas where liquid permeability in the thickness direction is required, adjacent components in the thickness direction are fixed or joined in an intermittent pattern. For example, when such intermittent fixing or joining is performed using a hot melt adhesive, intermittent pattern coating such as a spiral, Z-shaped, or wavy pattern can be suitably used. When coating an area greater than the coating width of a single nozzle, intermittent pattern coating such as a spiral, Z-shaped, or wavy pattern can be performed with or without gaps in the width direction WD. Material welding methods such as heat sealing and ultrasonic sealing can also be used to join the components.

[0029] In addition, as the nonwoven fabric in the following description, known nonwoven fabrics can be used appropriately depending on the location and purpose. The constituent fibers of the nonwoven fabric can be selected without particular limitation, for example, synthetic fibers such as polyolefins (e.g., polyethylene or polypropylene), polyesters, and polyamides (including single-component fibers and core-sheath and other composite fibers), regenerated fibers (e.g., rayon or cupra), and natural fibers (e.g., cotton), and mixtures of these can also be used. In order to increase the flexibility of the nonwoven fabric, it is preferable that the constituent fibers be crimped fibers. Furthermore, the constituent fibers of the nonwoven fabric can be hydrophilic fibers (including fibers made hydrophilic by a hydrophilizing agent), hydrophobic fibers, or water-repellent fibers (including fibers made water-repellent by a water-repellent agent). Furthermore, nonwoven fabrics are generally classified into staple fiber nonwoven fabrics, long fiber nonwoven fabrics, spunbond nonwoven fabrics, meltblown nonwoven fabrics, spunlace nonwoven fabrics, thermal bond (air-through) nonwoven fabrics, needle-punched nonwoven fabrics, point-bond nonwoven fabrics, laminated nonwoven fabrics (including SMS nonwoven fabrics and SMMS nonwoven fabrics in which a meltblown layer is sandwiched between spunbond layers), and the like, depending on the fiber length, sheet formation method, fiber bonding method, and laminated structure, and any of these nonwoven fabrics can be used.

[0030] 1 to 5 show an example of a pad-type disposable diaper 100. This pad-type disposable diaper 100 is intended to be placed inside an outer garment such as a pants-type disposable diaper. It is narrow and does not have side flaps SF extending laterally beyond the absorbent body 56. However, although not shown, it may have a pair of side flaps SF that do not include the absorbent body 56 and extend laterally beyond both side edges of the absorbent body 56. The pad-type disposable diaper 100 of this example has a crotch region C, a front portion F extending forward from the crotch region C, and a rear portion B extending rearward from the crotch region C. Here, the crotch region C refers to the range in the front-to-rear direction LD that includes the constricted region 56N when the absorbent body 56 has a constricted region 56N, which will be described later. When the absorbent body 56 does not have a constricted region 56N, the crotch region C refers to the portion that is centrally located in the front-to-rear direction LD and whose dimension in the front-to-rear direction LD is 20 to 30% of the overall length Y of the product.

[0031] The pad-type disposable diaper 100 in this example has a constricted region 56N cut out on both sides of the crotch region C, but it can be modified as needed, such as by cutting out the four corners, or by not having the constricted region 56N but instead being a rectangle with long sides (side edges 59) along the front-to-back direction LD.

[0032] As shown in Figures 1 to 5, the pad-type disposable diaper 100 of this example comprises an absorbent body 56 that absorbs and retains urine, a packaging sheet 58 that wraps the absorbent body 56, a top sheet 30 provided on the front side of the absorbent body 56, a back waterproof sheet 11 provided on the back side of the absorbent body 56, and rising gathers 60 that rise from starting ends 61 extending along the front-to-back direction LD and are provided on both sides of the surface in the width direction WD.

[0033] (Top sheet) The top sheet 30 is liquid permeable, and examples thereof include a perforated or non-perforated nonwoven fabric, a perforated plastic sheet, etc. Furthermore, the top sheet 30 may consist of a single sheet, or a laminated sheet obtained by bonding two or more sheets together. Similarly, the top sheet 30 may consist of a single sheet, or two or more sheets in the planar direction.

[0034] The side edges of the top sheet 30 extend to form part of the rising gathers 60 as shown in the illustrated example, but may also be folded back at the side edges of the absorbent element 50, passing between the back waterproof sheet 11 and the rising gathers 60 and wrapping around to the back side of the absorbent element 50, or may not be folded back at the side edges of the absorbent element 50 but may extend out to the side of the side edges of the absorbent element 50 to form part of the side flaps SF.

[0035] The top sheet 30 is preferably fixed to an adjacent backside member by a material welding joining means such as heat sealing or ultrasonic sealing, or by a hot melt adhesive, in order to prevent misalignment relative to the backside member, etc. In the illustrated example, the top sheet 30 is fixed to the portion of the packaging sheet 58 located on the front side of the absorbent body 56, etc., by a hot melt adhesive applied to the backside of the top sheet 30.

[0036] (Back waterproof sheet) The material of the back waterproof sheet 11 is not particularly limited, but examples include a waterproof resin film made of a polyolefin resin such as polyethylene or polypropylene, or a waterproof nonwoven fabric. It is preferable to use a moisture-permeable material for the back waterproof sheet 11 in order to prevent stuffiness. A suitable moisture-permeable waterproof resin film is a microporous waterproof resin film obtained by kneading an inorganic filler into a polyolefin resin such as polyethylene or polypropylene, forming the sheet, and then stretching it uniaxially or biaxially.

[0037] (Absorbent body) The absorbent body 56 (i.e., each layer of the absorbent layer 55 described below) can be formed from a fiber assembly. This fiber assembly can be made by stacking staple fibers such as cotton-like pulp or synthetic fibers, or a filament assembly obtained by opening a tow (fiber bundle) of synthetic fibers such as cellulose acetate as needed. The overall fiber weight of the absorbent body 56 can be, for example, 100 to 450 g / m when stacking cotton-like pulp or staple fibers. ２ In the case of a filament aggregate, for example, 30 to 120 g / m ２ The fineness of synthetic fibers is, for example, 1 to 16 dtex, preferably 1 to 10 dtex, and more preferably 1 to 5 dtex. In the case of a filament aggregate, the filaments may be non-crimped fibers, but are preferably crimped fibers. The crimp degree of the crimped fibers can be, for example, 5 to 75, preferably 10 to 50, and more preferably 15 to 50, particles per 2.54 cm. Uniformly crimped fibers can also be used. It is preferable to have superabsorbent polymer particles dispersed and retained in the absorbent body 56.

[0038] The absorbent body 56 can be sized appropriately as long as it extends from the front portion F to the rear portion B, but it preferably extends to or near the periphery of the product in both the front-to-rear direction LD and the width direction WD. Note that the reference numeral 56X indicates the overall width of the absorbent body 56, and the reference numeral 56Y indicates the overall length of the absorbent body 56.

[0039] 1, it is preferable that the absorbent body 56 has a front portion F, a rear portion B, and a narrower constricted region 56N located between them and narrower than the front portion F and the rear portion B (forming a roughly hourglass shape in plan view), because this improves the fit around the legs of the absorbent body 56 itself and the rising gathers 60. In this case, the width of the narrowest portion of the absorbent body 56 can be determined as appropriate, and can be, for example, 0.5 to 0.8 times the overall width 56X of the absorbent body 56.

[0040] (Superabsorbent polymer particles) The absorbent body 56 (i.e., each layer of the absorbent layer 55 described below) can contain superabsorbent polymer particles in part or all thereof. The superabsorbent polymer particles include not only "particles" but also "powder." As the superabsorbent polymer particles, those used in this type of disposable diaper can be used as they are. For example, when sieved using a 500 μm standard sieve (JIS Z8801-1:2006) (shaking for 5 minutes), the proportion of particles remaining on the sieve is preferably 30% by weight or less, and when sieved using a 180 μm standard sieve (JIS Z8801-1:2006) (shaking for 5 minutes), the proportion of particles remaining on the sieve is preferably 60% by weight or more.

[0041] The material for the superabsorbent polymer particles is not particularly limited, but one with a water absorption capacity of 40 g / g or more is preferred. Examples of superabsorbent polymer particles include starch-based, cellulose-based, and synthetic polymer-based materials, and examples that can be used include starch-acrylic acid (salt) graft copolymers, saponified starch-acrylonitrile copolymers, crosslinked products of sodium carboxymethylcellulose, and acrylic acid (salt) polymers. The shape of the superabsorbent polymer particles is preferably a commonly used powder-like shape, but other shapes can also be used.

[0042] The highly absorbent polymer particles preferably have a water absorption rate of 70 seconds or less, particularly 40 seconds or less. If the water absorption rate is too slow, the liquid supplied into the absorbent body 56 tends to flow back out of the absorbent body 56, which is known as backflow.

[0043] Furthermore, the highly absorbent polymer particles preferably have a gel strength of at least 1000 Pa. This effectively prevents the sticky feeling after absorbing liquid, even when the absorbent body 56 is bulky.

[0044] The basis weight of the superabsorbent polymer particles can be determined appropriately depending on the absorption amount required for the application of the absorbent body 56. Therefore, although it cannot be generalized, it is generally recommended that the basis weight of the absorbent body 56 as a whole be 50 to 350 g / m ２ The polymer weight can be 50 g / m ２ If it is less than 350 g / m, it will be difficult to ensure sufficient absorption. ２ Above this, the effect saturates.

[0045] The ratio of the fibers to the superabsorbent polymer particles in the absorbent body 56 is not particularly limited, and can be, for example, a weight ratio of fibers to superabsorbent polymer particles of 40:60 to 65:35.

[0046] (Wrapping Sheet) In order to ensure or enhance the shape retention of the absorbent body 56, it is preferable to wrap the entire absorbent body 56 in a wrapping sheet 58, or to wrap each layer of the absorbent layer 55 (described later) in a separate wrapping sheet 58. The wrapping sheet 58 can also be omitted. When using a wrapping sheet 58, the material that can be used may be tissue paper, particularly crepe paper, nonwoven fabric, polylaminated nonwoven fabric, or a sheet with small holes. However, when the absorbent body 56 contains superabsorbent polymer particles, it is desirable that the sheet does not allow the superabsorbent polymer particles to escape. When using nonwoven fabric instead of crepe paper, hydrophilic SMS nonwoven fabric (SMS, SSMMS, etc.) is particularly suitable, and polypropylene, polyethylene / polypropylene composite material, etc. can be used. The basis weight is 5 to 40 g / m ２ , especially 10 to 30 g / m ２ It is preferable that:

[0047] The packaging form of the packaging sheet 58 can be determined as appropriate, but from the standpoint of ease of manufacturing and preventing leakage of superabsorbent polymer particles from the front and rear edges, it is preferable to wrap it around the absorbent body 56 in a cylindrical shape so as to surround the front, back, and both side surfaces, with the front and rear edges extending beyond the front and rear of the absorbent body 56, and to join the overlapping wound parts and the overlapping parts of the extending front and rear edges by a joining means such as a hot melt adhesive or material welding.

[0048] (External Nonwoven Fabric) When it is undesirable for the back waterproof sheet 11 to be exposed on the back surface, such as when the back waterproof sheet 11 is a waterproof resin film, an external nonwoven fabric 12 can be provided on the back surface of the product to cover the back waterproof sheet 11, as in the illustrated example. The external nonwoven fabric 12 can also be omitted. If necessary, a joining member 8 can be provided on the outside of the external nonwoven fabric 12, which can be fixed or joined to an outer diaper or underwear, as in known pad-type disposable diapers, but this is not necessary.

[0049] (Rising gathers) The rising gathers 60 are provided on both sides of the surface in the width direction WD so as to rise from starting ends 61 extending in the front-to-back direction LD. The rising gathers 60 are preferably provided from the front portion F to the rear portion B, and particularly preferably extend from a position in front of the front end of the absorbent body 56 to a position in back of the rear end of the absorbent body 56.

[0050] 2 to 4 includes a main portion 66 extending from a starting end 61 extending along the front-to-back direction LD toward the center in the width direction WD, a front collapsed portion 67F formed by fixing the front end of the main portion 66 in a collapsed state, a rear collapsed portion 67B formed by fixing the rear end of the main portion 66 in a collapsed state, an unfixed risen portion 68 located between the front collapsed portion 67F and the rear collapsed portion 67B of the main portion 66, and a plurality of gathered elastic members 63 attached to the risen portion 68 at intervals in the width direction WD and extending along the front-to-back direction LD. The gathered elastic members 63 are fixed to the risen portion 68 in a stretched state along the front-to-back direction LD. As a result, the risen portion 68 contracts and rises together with the gathered elastic members 63 when at its natural length, and stretches together with the gathered elastic members 63 in response to external forces, thereby conforming and deforming to the body surface (fitting).

[0051] (Absorbent layer having slits) As shown in Figures 1 to 6, the absorber 56 is an absorbent layer 55 that extends from the front portion F to the rear portion B, and preferably includes at least one absorbent layer 55a that has a slit 40 that is provided at least in the crotch region C and extends in the front-to-rear direction LD without branching. It is preferable that a plurality of absorbent layers 55 are laminated, but as long as it has an absorbent layer 55a with slits 40, the absorbent layer 55 may be made up of only one layer, as shown in Figures 12 and 13. Having the slits 40 in at least the crotch region C improves urine diffusion.

[0052] The thickness of the absorbent layer 55 can be determined as appropriate, but for example, the thickness of the absorbent layer 55a having the slits 40 can be set to, for example, 3 to 12 mm. The thickness of the absorbent layer 55b without the slits 40 can be set to, for example, 2 to 11 mm.

[0053] When multiple absorbent layers 55 are stacked, it is preferable to have an absorbent layer 55a with slits 40 and an absorbent layer 55b without slits 40, since this prevents a decrease in absorption capacity due to the provision of slits 40. In this case, the absorbent layer 55a with slits 40 may be any layer in the thickness direction, but it is preferable to have at least the topmost layer be an absorbent layer 55a with slits 40 and have an absorbent layer 55b without slits 40 below it, since this facilitates effective urine diffusion. Although not shown, conversely, the topmost layer may be an absorbent layer 55b without slits 40, and an absorbent layer 55a with slits 40 may be included below it (at least one of the middle layer and the bottom layer). Alternatively, all absorbent layers 55 may have slits 40. Figures 2 and 3 illustrate a two-layer absorbent body 56 in which the upper absorbent layer 55 is an absorbent layer 55a with slits 40 and the lower absorbent layer 55 is an absorbent layer 55b without slits 40.

[0054] If the both side edges 59 of the linear slit 40 in the front-to-rear direction LD in the crotch region C are parallel and linear along the front-to-rear direction LD as in conventional pad-type disposable diapers, even if the both side edges 59 of the slit 40 are spaced apart in the width direction WD over the entire length of the front-to-rear direction LD in the unfolded state, when the wearer stands up or moves, foot pressure is applied and the portion having the absorber 56 is compressed in the width direction WD, which may cause the both side edges 59 of the slit 40 to come into contact with each other, resulting in partial or almost complete disappearance of the slit 40. Therefore, as shown in the example of Figures 1 to 6, it is preferable that the both side edges 59 of the slit 40 are spaced apart in the width direction WD over the entire length of the front-to-rear direction LD in the unfolded state, and that the slit 40 has a first portion 40a where the distance between the both side edges 59 of the slit 40 in the width direction WD is minimum, and a second portion 40b where the distance between the both side edges 59 in the width direction WD is maximum. In the present pad-type disposable diaper 100, if the portion having the absorbent body 56 is not compressed in the width direction WD, or if it is compressed but the side edges 59 of the slit 40 do not come into contact at all, the entire slit 40 in the front-to-rear direction LD contributes to improved diffusion performance. Even if the portion having the absorbent body 56 is compressed in the width direction WD by the wearer closing their legs, for example, and the side edges 59 of the slit 40 come into contact as shown in Figure 9 , the side edges 59 of the first portion 40a come into contact first, preventing further compressive deformation in the width direction WD. This makes it easier to maintain the gap of the slit 40 (distance d3 between the side edges 59) in the portions other than the first portion 40a (including the second portion 40b). As a result, the present pad-type disposable diaper 100 can suppress a decrease in diffusion performance due to collapse of the slit 40.

[0055] The slit 40 may be a single slit in the center of the width direction WD as shown in the illustrated example, or multiple slits may be provided spaced apart in the width direction WD. Multiple slits 40 may also be provided spaced apart in the front-to-rear direction LD. Although not shown, for example, multiple slits 40 may be provided independently in the crotch region C, front portion F, and rear portion B. Furthermore, multiple slits 40 extending in the front-to-rear direction LD without branching may be connected via a branch portion, as described in Patent Documents 1 and 2. In other words, the term "slit" refers to an entity or portion that does not include a branch portion. Furthermore, a "slit extending in the front-to-rear direction LD" refers to a slit in which the angle between the front-to-rear direction LD and the center line of the slit 40 (or a tangent line if not a straight line) is 45 degrees or less, particularly 30 degrees or less. In contrast, a slit extending along the front-to-rear direction LD refers to a slit in which the front-to-rear direction LD and the center line of the slit 40 (or a tangent line if not a straight line) are parallel (the angle is approximately 0 degrees).

[0056] As shown in FIGS. 1 and 5 , the slit 40 may be provided at least in the crotch region C, but preferably extends from the crotch region C to the rear region B, and more preferably extends from the front region F through the crotch region C to the rear region B. Specifically, the length of the slit 40 in the front-to-rear direction LD is desirably 290 mm or more, preferably 380 mm or more. The upper limit of the length of the slit 40 in the front-to-rear direction LD is the entire length of the absorbent layer 55 having the slit 40. The slit 40 may be continuous from the front end to the rear end of the absorbent layer 55a in which it is formed, as shown in FIG. 7 , or may be provided only in the middle of the absorbent layer 55a in the front-to-rear direction LD, as shown in FIG. 14( a). Alternatively, the slit 40 may be continuous to the front end of the absorbent layer 55a but not to the rear end, as shown in FIG. 14( b). Alternatively, the slit 40 may be continuous to the rear end of the absorbent layer 55a but not to the front end, as not shown.

[0057] In the illustrated example, no spacer is provided to ensure a gap between both side edges 59 of the slit 40, but such a spacer may be provided. Although not shown, examples of such a spacer include an independent absorbent layer that is provided independently between both side edges 59 of the slit 40 and in the same layer as the absorbent layer 55a having the slit 40, and a protrusion that protrudes from the absorbent layer 55b adjacent to the absorbent layer 55a having the slit 40 so as to enter between both side edges 59 of the slit 40.

[0058] The shape of the slit 40 may have one or more first portions 40a and one or more second portions 40b, as shown in FIG. 7(c), or may have the first portions 40a and the second portions 40b alternately repeated in the direction along the slit 40 as shown in FIGS. 7(a), 7(b), 7(d), 7(e), and 7(f). The former is preferable when prioritizing diffusion performance when the portion having the absorbent body 56 is not compressed in the width direction WD. However, the latter is preferable to achieve both the collapse prevention function of the slit 40 by the first portion 40a and the diffusion performance of the portions other than the first portion 40a. In the latter case, it is more preferable that the proportion of the dimension of the slit 40 in the front-to-rear direction LD other than the first portion 40a be 50 to 80%.

[0059] The planar shape of each of the side edges 59 of the slit 40 is not particularly limited as long as it has a first portion 40a and a second portion 40b, but any of the following (i) to (iii) is preferable because the first portion 40a and the second portion 40b alternate in a direction along the slit 40. (i) As shown in Figures 7(a) to 7(e), the side edges 59 of at least a portion of the slit 40 are wavy portions having an amplitude in the width direction WD, and the wavy portions on one side edge of the slit 40 and the wavy portions on the other side edge of the slit 40 are in opposite phase or out of phase with each other. (ii) As shown in Figure 7(f), the slit shape has one side edge having a wavy portion having an amplitude in the width direction WD and the other side edge being linear along the front-to-rear direction, etc. (iii) As shown in Figure 14 (c), a slit shape in which both side edges 59 of at least a part of the slit 40 are wavy portions having an amplitude in the width direction WD, one side edge is a first wavy portion 40c having an amplitude in the width direction WD, and the other side edge is a second wavy portion 40d having an amplitude smaller than that of the first wavy portion 40c.

[0060] When a wavy portion is provided on the side edge of the slit 40, the shape of the wavy portion is not particularly limited, and may be a shape with a continuously changing slope (for example, a sine wave) as shown in Figure 7(a), a rectangular wave with an intermittently changing amplitude as shown in Figure 7(e), or a triangular wave with an intermittently changing slope (not shown).

[0061] If the waveforms of the wavy portions of both side edges 59 of the slit 40 are the same, when the wearer's movements cause the phases of the wavy portions of both side edges 59 to shift and compress the slit 40 in the width direction WD, the waveforms may interlock, preventing the first portion 40a from performing its collapse prevention function and potentially causing the slit 40 to become blocked as shown in Figure 8. This problem is particularly likely to occur when the slit 40 is continuous from the front end to the rear end of the absorbent layer 55 containing it, as shown in Figures 7(a) and 7(e). This problem is even more likely to occur when the absorber 56 consists solely of such an absorbent layer 55, as shown in Figures 12 and 13. Therefore, when the waveforms of the wavy portions of both side edges 59 of the slit 40 are the same, it is also possible to make one of the side edges 59 of the slit 40 straight and the other wavy, resulting in a shape that does not interlock with the slit 40, as shown in the example of Figure 7(f). This shape also has the advantage that, because one side of the slit 40 is straight, the absorbent layer 55 is not scraped away, thereby preventing a reduction in urine absorption capacity. As another example of a shape that prevents the slit 40 from interlocking even when misaligned, as shown in Figure 14 (c), it is possible to change the amplitude in the width direction WD of the waveform of the wavy portions on both side edges 59 of the slit 40 between a first wavy portion 40c and a second wavy portion 40d having an amplitude smaller than that of the first wavy portion 40c, thereby making the wavy portions on both side edges 59 of the slit 40 have different shapes.

[0062] 1 to 6, it is also preferable to dispose an absorbent layer 55 without slits 40, which has a length spanning the entire slit 40 in the front-to-rear direction and a width spanning both sides of the slit 40 in the width direction WD, above or below the absorbent layer 55 with slits 40. This makes the absorbent layer 55b without slits 40 less likely to be compressed in the width direction WD as a whole, thereby making the slits 40 less likely to be crushed, and also makes it less likely that one side of the absorbent layer 55 with slits 40 will shift in the front-to-rear direction LD relative to the other side across the slit 40. It is more preferable that the absorbent layer 55 without slits 40 has a larger dimension in the width direction WD than the absorbent layer 55 with slits 40 within the range (preferably the entire length) of the slit 40 in the front-to-rear direction LD, and both side portions of the absorbent layer 55 with slits 40 extend beyond both sides of the absorbent layer 55 with slits 40 in the width direction WD.

[0063] The width direction WD spacing d1 of the first portions 40a can be determined as appropriate, but is preferably about 5 to 20 mm, and more preferably about 10 to 15 mm, for example. The width direction WD spacing d2 of the second portions 40b can be determined as appropriate, but is preferably 1.5 to 3.0 times, and more preferably 2.0 to 2.5 times, the width direction WD spacing d1 of the first portions 40a.

[0064] When the side edges of the slit 40 are wavy, the distance d5 between adjacent convex vertices in the front-to-rear direction LD can be determined as appropriate, but is preferably 50 to 205 mm, and more preferably 68.5 to 102.5 mm. The distance d6 between adjacent concave vertices in the front-to-rear direction LD can also be determined as appropriate, but is preferably 50 to 205 mm, and more preferably 68.5 to 102.5 mm. When the side edges of the slit 40 are wavy, the distance (wavelength) d5 between adjacent convex vertices in the front-to-rear direction LD and the distance (wavelength) d6 between adjacent concave vertices in the front-to-rear direction LD are the same. The length (amplitude) e in the width direction WD from the vertex of the convex portion to the vertex of the concave portion can be determined as appropriate, but is preferably 5 to 30 mm, and more preferably 10 to 15 mm. 14(c), the length (amplitude) e1 in the width direction WD from the apex of the convex portion to the apex of the concave portion of the first wavy portion 40c can be set as appropriate, but is preferably 10 to 35 mm, and more preferably 15 to 25 mm.Furthermore, the length (amplitude) e2 in the width direction WD from the apex of the convex portion to the apex of the concave portion of the second wavy portion 40d is preferably 1 / 1.5 to 1 / 4.0, and more preferably 1 / 1.5 to 1 / 2.0, of the length (amplitude) e1 in the width direction WD from the apex of the convex portion to the apex of the concave portion of the first wavy portion 40c.

[0065] (Grooves) As shown in Figures 1 and 6, when an absorbent layer 55b without slits 40 is provided below an absorbent layer 55a with slits 40, it is preferable to provide grooves 57 on the surface of the absorbent layer 55b without slits 40. The grooves 57 may be formed by embossing the absorbent layer 55, or by reducing the basis weight of the material, such as fibers, in the portion that will become the grooves 57 depending on the shape of the mold used to manufacture the absorbent layer 55. In the former case, the bottoms of the grooves 57 are compressed in the thickness direction and have a higher density than the portion other than the grooves 57, while in the latter case, the density of the bottoms of the grooves 57 and the portion other than the grooves 57 is approximately the same. By providing an absorbent layer 55 with grooves 57 below an absorbent layer 55a with slits 40, it is possible to further improve urine diffusibility while minimizing the decrease in absorption capacity.

[0066] 4 and 5, when an absorbent layer 55b having a groove 57 directly below an absorbent layer 55a having a slit 40 and no slit 40 is provided, it is preferable that a part or all of the groove 57 overlaps with the slit 40. As described above, when both side edges 59 of the first portion 40a of the slit 40 come into contact with each other, the flow of urine into the slit 40 and the diffusion of urine in the direction along the slit 40 are hindered at these contacting portions. In contrast, if a groove 57 is formed on the surface of the absorbent layer 55 directly below the absorbent layer 55 having the slit 40 and is configured so that part or all of it overlaps with parts of the slit 40 other than the first part 40a (including the second part 40b), even if the side edges 59 of the first part 40a of the slit 40 come into contact, urine that has flowed into the slit 40 at parts other than the first part 40a will diffuse through the groove 57 in the lower absorbent layer 55, allowing urine to be supplied to a wider area of ​​the lower absorbent layer 55, thereby suppressing a decrease in diffusivity compared to when such a groove 57 is not present.

[0067] As shown in Fig. 10(a) etc., a plurality of grooves 57 may be provided at intervals in any direction such as the front-rear direction LD or the width direction WD, or only one groove 57 may be provided as shown in Fig. 11(a) . When a plurality of grooves 57 are provided, all of the grooves 57 may have portions overlapping with the slits 40 as shown in Fig. 10(a) etc., or as shown in Fig. 10(c) , in addition to the grooves 57 overlapping with the slits 40, there may also be grooves 57 that do not overlap with the slits 40.

[0068] The degree of overlap between one groove 57 and the slit 40 can be determined as appropriate. For example, as shown in Figures 10(a) and 10(b) and 11(a), when the groove 57 is provided along the center of the slit 40, it is preferable that the groove 57 extend to both the front and rear of the first portion 40a. It is particularly preferable that the overlapping region between one groove 57 and the slit 40 extend across multiple second portions 40b. In this case, it is preferable that the width of the groove 57 is greater than 0.6 times (particularly 1 time) the distance d1 in the width direction WD between both side edges 59 of the slit 40 in the first portion 40a and less than the distance d2 in the width direction WD between both side edges 59 of the slit 40 in the second portion 40b. Also, as shown in Figures 10(d) and 11(b), it is also preferable that 50% or more, particularly 60% or more of the area of ​​the groove 57 extend into a region that does not overlap with the slit 40. In this case, it is preferable that the area of ​​the region where the groove 57 and the slit 40 overlap is larger than half the square of the width of the groove 57 .

[0069] 10 and 11 , the direction in which the groove 57 extends is not particularly limited, and the groove 57 may extend along the slit 40 (along the front-rear direction LD in the illustrated example), or may extend along a diagonal direction intersecting the slit 40 as shown in Figures 10(d) and 11(b), or may extend in a horizontal direction (not shown). In the example shown in Figure 10, the groove 57 extends linearly, but may be bent as shown in Figure 11(b) or may extend in a curved shape (not shown).

[0070] Because the grooves 57 themselves absorb a small amount of urine, it is also preferable that no grooves 57 be present in an area of ​​60% or more of the crotch region C in the front-to-back direction LD. For the same reason, the ratio of the area of ​​the bottoms of the grooves 57 to the area of ​​the absorbent layer 55b containing the grooves 57 (the total area of ​​the bottoms of all the grooves 57 if there are multiple grooves 57) is preferably 0.5% to 4.0%, and more preferably 1.2% to 2.0%. The specific dimensions of the grooves 57 may be determined as appropriate, but the length may be, for example, 51 to 205 mm, and more preferably 90 to 102.5 mm. The width of the grooves 57 may be, for example, 1 to 10 mm, and more preferably 3 to 5 mm.

[0071] Grooves 57 extending in an oblique direction such as diagonally forward or diagonally backward as shown in FIG. 10(d) and FIG. 11(b) are particularly preferable because they have excellent diffusibility.

[0072] <Explanation of Terms Used in the Specification> The following terms used in the specification have the following meanings unless otherwise specified in the specification.

[0073] The "front-to-back direction" refers to the direction indicated by the symbol LD in the figure (vertical direction), and the "width direction" refers to the direction indicated by the symbol WD in the figure (left-to-right direction), and the front-to-back direction and the width direction are perpendicular to each other.

[0074] "Front side" means the side closest to the wearer's skin when worn, and "rear side" means the side farthest from the wearer's skin when worn.

[0075] "Front" means the side closest to the wearer's skin when worn, and "back" means the side farthest from the wearer's skin when worn.

[0076] - "Basis weight" is measured as follows. After pre-drying the sample or test piece, it is left in a test room or device under standard conditions (test location: temperature 23±1°C, relative humidity 50±2%) until it reaches a constant weight. Pre-drying refers to bringing the sample or test piece to a constant weight in an environment at a temperature of 100°C. Note that pre-drying is not necessary for fibers with an official moisture regain of 0.0%. Using a sample collection template (100mm x 100mm), a sample measuring 100mm x 100mm is cut from the test piece when it has reached a constant weight. The weight of the sample is measured and multiplied by 100 to calculate the weight per square meter, which is the basis weight.

[0077] The water absorption amount is measured according to JIS K7223-1996 "Test method for water absorption amount of superabsorbent resins."

[0078] The water absorption rate is the "time to the end point" when 2 g of superabsorbent polymer and 50 g of physiological saline are used and tested according to JIS K7224-1996 "Test method for water absorption rate of superabsorbent polymers."

[0079] "Deployed state" means a state in which the device is deployed flat without contraction (including any contraction such as contraction due to an elastic member) or slack.

[0080] ・Unless otherwise specified, the dimensions of each part refer to the dimensions in the unfolded state, not the natural length state.

[0081] - If there is no description of the environmental conditions for a test or measurement, the test or measurement shall be carried out in a test room or device under standard conditions (the test location shall be a temperature of 23±1°C and a relative humidity of 50±2%).

[0082] The present invention is suitable for pants-type disposable diapers such as those in the above examples.

[0083] 11...back waterproof sheet, 30...top sheet, 40...slit, 40a...first portion, 40b...second portion, 40c...first wavy portion, 40d...second wavy portion, 55...absorbent layer, 55a...absorbent layer with slit, 55b...absorbent layer without slit, 56...absorbent body, 56N...constricted region, 57...groove, 58...packaging sheet, 59...side edges, 60...rising gathers, 61...starting end, 63...gathered elastic member, 63a...first gathered elastic member, 63b...second gathered elastic member, 63c...third gathered elastic member, 66...main portion, 67F...front collapsed portion, 67B...rear collapsed portion, 68...rising portion, B...rear portion, F...front portion, LD...front-to-back direction, C...crotch portion, WD...width direction, SF...side flaps.

Claims

1. An absorbent article comprising a crotch portion, a front portion and a rear portion extending forward and backward from the front and rear sides of the crotch portion respectively, and an absorbent body including one or more absorbent layers that extend in the front-rear direction without branching and are provided at least in the crotch portion and have a slit extending from the front portion to the rear portion, and a liquid-permeable topsheet provided on the front side of the absorbent layer, wherein both side edges of the slit are spaced apart in the width direction over the entire front-rear direction in the unfolded state, and the slit has a first portion where the widthwise interval between both side edges of the slit is minimum and a second portion where the widthwise interval between both side edges of the slit is wider than the first portion and maximum in the unfolded state.

2. The absorbent article according to claim 1, wherein the slit has the first portion and the second portion alternately and repeatedly, and the ratio of the front-rear dimension other than the first portion to the front-rear dimension of the slit is 50 to 80%.

3. The absorbent article according to claim 1 or 2, wherein both side edges of part or all of the slit are wavy portions having an amplitude in the width direction, and the wavy portion of one side edge of the slit and the wavy portion of the other side edge of the slit have the same waveform and are in opposite phases or have a phase shift.

4. The absorbent article according to claim 1 or 2, wherein one of the two side edges of part or all of the slit is a wavy portion having an amplitude in the width direction, and the other side edge is straight.

5. The absorbent article according to claim 1 or 2, wherein one of the two side edges of part or all of the slit is a first wavy portion having an amplitude in the width direction, and the other side edge is a second wavy portion having an amplitude smaller than that of the first wavy portion.

6. The absorbent article according to claim 1 or 2, wherein the absorbent body has an absorbent layer having the slit and an absorbent layer not having the slit, and the absorbent layer not having the slit has a length extending over the entire front-rear direction of the slit and a width extending on both sides in the width direction of the slit.

7. The absorbent layer without the slit is provided directly below the absorbent layer with the slit, the absorbent layer without the slit has grooves provided on its surface, and part or all of the grooves overlap with the slit outside the first portion. The absorbent article according to claim 6.

8. The absorbent article according to claim 7, wherein the crotch portion does not have the groove in a range of 60% or more in the front-rear direction.

9. The absorbent article according to claim 7, wherein the groove extends across both the front and rear sides of the first portion in the slit.

10. The absorbent article according to claim 1, wherein the slit is continuous from the front end to the rear end of the absorbent layer having the slit.

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