Absorbent article

Abstract

The present invention relates to an absorbent article (1) comprising an absorbent core (10) having a length direction, a width direction and a thickness direction orthogonal to each other, the absorbent core (10) having comminuted liquid retaining fibers, the liquid retaining fibers having broadleaf wood liquid retaining fibers made of broadleaf wood, the absorbent core (10) having a plurality of high density portions (100) aggregated from the liquid retaining fibers, the absorbent core (100) having a low density portion on one side or the other side of the thickness direction of at least one of the high density portions (100) having a lower density of the liquid retaining fibers than the high density portion.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 202080081098.1 with the same title, International Application No. PCT / JP2020 / 044119, filed on November 26, 2020. TECHNICAL FIELD

[0002] The present application relates to an absorbent article. BACKGROUND

[0003] As an example of an absorbent article, a sanitary napkin that absorbs excreted liquid such as menstrual blood is known. Such a sanitary napkin includes an absorbent body (absorbent core), and the absorbent core includes water-retentive (liquid-retentive) fibers. Generally, as the water-retentive fibers, needle-leaf wood pulp fibers having a long fiber length are used. In addition, Patent Literature 1 discloses an absorbent article in which the absorbent core 4 is provided to contain, in addition to water-absorptive fibers 12F as water-retentive fibers, fiber blocks 11 as aggregates in which synthetic fibers are deposited in a lump shape, thereby improving the softness and the cushioning property of the absorbent core 4.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2019-98187 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] Such an absorbent article is required to have sufficient absorbency even in the case of long-term wearing. However, in the conventional absorbent article, it is difficult to simultaneously improve the absorbency of excreted matter and form a soft absorbent body to prevent the absorbent body from being twisted and bent in the case of long-term wearing. For example, in the absorbent article of Patent Literature 1, in order to improve the cushioning property of the absorbent body, fiber blocks containing synthetic fibers having low water-absorptivity are contained, and thus there is a possibility that the water-absorbing property is deteriorated accordingly.

[0009] The present application has been made in view of the above-described problems, and an aspect of the present application is to provide an absorbent article that simultaneously realizes softness and absorbency.

[0010] MEANS FOR SOLVING PROBLEMS

[0011] The main aspect of the present application for achieving the above aspect is to provide an absorbent article having a length direction, a width direction, and a thickness direction orthogonal to each other, the absorbent article including an absorbent core having comminuted liquid-retentive fibers, the liquid-retentive fibers having broadleaf wood liquid-retentive fibers made of broadleaf wood, the absorbent core having a plurality of high-density portions that are portions in which the liquid-retentive fibers are aggregated and low-density portions that are portions in which the liquid-retentive fibers have a lower density than the high-density portions, the low-density portions being located on one side in the thickness direction or the other side in the thickness direction of at least one of the high-density portions.

[0012] Other features of the present application than the above will be clear from reading the description of the present application and the accompanying drawings.

[0013] Effects of Invention

[0014] According to the present application, it is possible to provide an absorbent article that realizes both softness and absorbency. BRIEF DESCRIPTION OF DRAWINGS

[0015] [ Figure 1 ] is a schematic plan view of the sanitary napkin 1 as viewed from the skin side in the thickness direction.

[0016] [ Figure 2 ] is Figure 1 a schematic cross-sectional view of the sanitary napkin 1 as viewed along the arrow A-A in

[0017] [ Figure 3A ] is a graph showing the distribution of fiber length of the broadleaf wood liquid-retentive fibers (broadleaf wood pulp) and the coniferous wood liquid-retentive fibers (coniferous wood pulp).

[0018] [ Figure 3B ] is a graph showing the distribution of average fiber width of the broadleaf wood pulp and the coniferous wood pulp.

[0019] [ Figure 4 ] Figure 4 A is a graph illustrating a method for manufacturing a comminuted pulp for the absorbent body 10.

[0020] Figure 4 B is a graph illustrating a method for manufacturing the absorbent body 10 using a comminuted pulp or the like.

[0021] [ Figure 5 ] is an enlarged photograph of a fiber lump 100 obtained when a pulp sheet containing the broadleaf wood pulp is comminuted.

[0022] [ Figure 6 ] Figure 6 A is a schematic plan view of the fiber lump 100 as viewed from a prescribed direction.

[0023] Figure 6 B is Figure 6A is a view of the fiber block 100 in the thickness direction of the absorbent 10, viewed along the arrow B-B.

[0024] [ Figure 7 ] Figure 7 A is a view of the fiber block 100 in the thickness direction of the absorbent 10.

[0025] Figure 7 B is a view of the fiber block 100 in the thickness direction of the absorbent 10.

[0026] Figure 7 C is a view of the fiber block 100 in the thickness direction of the absorbent 10.

[0027] [ Figure 8 ] Figure 8 A is a schematic cross-sectional view of the absorbent 10 of a region provided with a press section 40 (linear press section 41).

[0028] Figure 8 B is a schematic cross-sectional view of the absorbent 10 of a region provided with a press section 40 (linear press section 41) having a high press section 45 and a low press section 46.

[0029] [ Figure 9 ] is a schematic cross-sectional view showing a modification of the absorbent 10. DETAILED DESCRIPTION

[0030] According to the description and drawings of the present specification, at least the following matters are clarified.

[0031] An absorbent article having a length direction, a width direction, and a thickness direction orthogonal to each other, the absorbent article including an absorbent core having comminuted liquid-retaining fibers, the liquid-retaining fibers having broadleaf wood liquid-retaining fibers made of broadleaf wood, the absorbent core having a plurality of high-density portions and low-density portions, the high-density portions being portions in which the liquid-retaining fibers are aggregated, the low-density portions being portions in which the liquid-retaining fibers have a lower density than the high-density portions, the low-density portions being located on one side in the thickness direction or the other side in the thickness direction of at least one of the high-density portions.

[0032] According to the absorbent article, moisture such as menstrual blood absorbed by the absorbent core is easily moved in the thickness direction from the low-density portions to the high-density portions (fiber blocks) due to capillary phenomenon. Thus, the entire absorbent core is easily able to absorb and retain moisture, and the absorbency can be improved. In addition, the broadleaf wood liquid-retaining fibers have a smaller area and volume per fiber than the needle-leaf wood liquid-retaining fibers, which reduces the sites at which the fibers are entangled with each other, so that the area (volume) of the entangled sites themselves is also small. Thus, the movement of the fibers is less likely to interfere with each other, and the softness of the absorbent can be improved. Thus, an absorbent article that has both softness and absorbency can be achieved.

[0033] In such an absorbent article, it is desirable that the high-density portion has a central portion that is a portion in which the liquid-retaining fibers are concentrated and are not entangled with the fibers of the low-density portion, and a fluff portion that is a portion in which the fibers are entangled with the fibers of the low-density portion, the average density of the high-density portion is higher than the average density of the absorbent core, and the weight of the fibers included in the central portion is greater than the weight of the fibers included in the fluff portion.

[0034] According to the absorbent article, more moisture is easily absorbed from the periphery of the high-density portion to the central portion via the fluff portion due to capillary phenomenon. This makes it possible to increase the total amount of moisture that can be held by the absorbent core.

[0035] In such an absorbent article, it is desirable that the high-density portion has a central portion that is a portion in which the liquid-retaining fibers are concentrated and are not entangled with the fibers of the low-density portion, and a fluff portion that is a portion in which the fibers are entangled with the fibers of the low-density portion, the average density of the high-density portion is higher than the average density of the absorbent core, and the weight of the fibers included in the central portion is less than or equal to the weight of the fibers included in the fluff portion.

[0036] According to the absorbent article, the area of the fluff portion having a lower density than the central portion is made large. Therefore, a large number of voids are formed among the liquid-retaining fibers, making the high-density portion easily deformable when subjected to an external force. This improves the softness of the absorbent core. In addition, since a large number of voids are present in the fluff portion, this makes it easy for a liquid containing a substance other than moisture, such as menstrual blood, to pass through the fluff portion and reach the central portion. Therefore, it is possible to achieve good absorbency while improving the softness of the absorbent article.

[0037] In such an absorbent article, it is desirable that the high-density portion has a planar shape, the maximum width of the area occupied by the fluff portion in the planar direction of the high-density portion is longer than the maximum width of the area occupied by the fluff portion in the direction orthogonal to the planar direction; and, among the plurality of high-density portions included in the absorbent core, the proportion of the high-density portions that are arranged such that the direction orthogonal to the planar direction coincides with the thickness direction of the absorbent core is greater than the proportion of the high-density portions that are arranged such that the direction orthogonal to the planar direction coincides with the length direction or the width direction of the absorbent core.

[0038] According to the absorbent article, the gradient of the fiber density in the thickness direction (Z direction) of the high-density portion is larger than the gradient of the fiber density in the planar direction (X and Y directions). Therefore, the capillary phenomenon is more likely to act in the thickness direction, and moisture is easily absorbed. Also, the moisture absorbed into the central portion of the high-density portion is unlikely to spread to the outside in the planar direction due to the fluff portion that spreads in the planar direction. This makes it easy for the moisture to remain in the high-density portion. Therefore, it is possible to further improve the absorbency of the absorbent article.

[0039] In such an absorbent article, it is desirable that, in the planar direction of the high-density portion, the diameter of a circle circumscribed around the central portion be set as Rc, the diameter of a circle circumscribed around the fluff portion be set as Ro, and (Ro-Rc) < Rc be satisfied.

[0040] According to the absorbent article, since the proportion of the fluff portion in the high-density portion is reduced, the entanglement sites between the fibers of the fluff portion and the fibers of the low-density portion around the fluff portion are reduced. This weakens the bonding of the high-density portion and the low-density portion, making the absorbent core soft overall. Therefore, it is possible to further improve the softness of the absorbent article.

[0041] In such an absorbent article, it is desirable that, in the planar direction of the high-density portion, the diameter of a circle circumscribed around the central portion be set as Rc, the diameter of a circle circumscribed around the fluff portion be set as Ro, and (Ro-Rc) ≥ Rc be satisfied.

[0042] According to the absorbent article, the proportion of the fluff portion in the high-density portion is increased, which increases the entanglement sites between the fibers of the fluff portion and the fibers of the low-density portion around the fluff portion. This makes it easy for the position of the high-density portion to be fixed to the low-density portion of the absorbent core, making it unlikely for the absorbent core to twist or deform. Therefore, it is possible to suppress the shape collapse of the absorbent article.

[0043] In such an absorbent article, it is desirable that at least a part of the high-density portion be in contact with the sheet member adjacent to the skin side of the absorbent core in the thickness direction.

[0044] According to the absorbent article, moisture such as menstrual blood is drawn from the sheet member adjacent to the skin side of the absorbent core to the inside of the absorbent core, and the moisture is held in the high-density portion, making it unlikely for the moisture to remain in the skin side sheet, which suppresses the re-wetting of the skin side sheet with the moisture. Therefore, when the absorbent article is worn, it is unlikely for the moisture to come into contact with the skin of the wearer. This makes it possible to suppress the occurrence of skin problems such as skin rash and the discomfort of the wearer.

[0045] In such an absorbent article, it is desirable that at least a portion of the high-density portion is in contact with a sheet member adjacent to the skin-facing side of the absorbent core in the thickness direction.

[0046] According to the absorbent article, moisture such as menstrual blood easily penetrates from the skin-facing side of the absorbent core to the non-skin-facing side and is held in the high-density portion provided on the non-skin-facing side in the thickness direction. This makes it less likely for moisture to remain on the skin-facing surface of the absorbent core, making it less likely for rewetting and the like to occur. Thus, when the absorbent article is worn, it is less likely for moisture to come into contact with the wearer's skin. This makes it possible to suppress the occurrence of skin problems such as skin rash and to make the wearer feel uncomfortable.

[0047] In such an absorbent article, it is desirable that at least a portion of the high-density portion is in contact with both a sheet member adjacent to the skin-facing side of the absorbent core in the thickness direction and a sheet member adjacent to the non-skin-facing side of the absorbent core in the thickness direction.

[0048] According to the absorbent article, the proportion of the high-density portion in the thickness direction of the absorbent core is increased, making it easy to hold moisture over a large range in the thickness direction. That is, it is possible to increase the water retention capacity of the absorbent core compared to a case where no high-density portion is present in the absorbent core.

[0049] In such an absorbent article, it is desirable that the absorbent core further includes a topsheet disposed on the skin-facing side with respect to the thickness direction of the absorbent core, and a press portion that integrally presses (compresses) the topsheet and the absorbent core in the thickness direction, the press portion being in contact with the high-density portion in the thickness direction.

[0050] According to the absorbent article, a portion of moisture that moves in the planar direction along the press portion (linear press portion) is absorbed from the skin-facing side to the non-skin-facing side in the thickness direction by the high-density portion, making it easy to be absorbed by the absorbent core. This makes it possible to suppress excessive spreading of moisture in the planar direction of the absorbent core, to improve the absorbency of the absorbent core.

[0051] In such an absorbent article, it is desirable that the press portion includes a low press portion and a high press portion in which the absorbent core is pressed to have a higher density than the low press portion, the low press portion being in contact with the high-density portion in the thickness direction.

[0052] According to the absorbent article, the provision of the low press portion makes it possible to suppress excessive deformation of the absorbent core when worn, making it less likely for the absorbent core to be damaged. Furthermore, moisture that moves in the planar direction along the low press portion is easily attracted to the thickness direction of the absorbent core due to the high-density portion, making it possible to balance the softness and the absorbency of the absorbent core.

[0053] In such an absorbent article, it is desirable that, when the absorbent core is divided into three in the length direction, i.e., into a length direction central region and length direction end regions (left and right), the weight of the high density portion contained per unit area of the length direction central region is greater than the weight of the high density portion contained per unit area of the length direction end regions.

[0054] According to the absorbent article, moisture such as menstrual blood is more likely to remain in the length direction central region of the absorbent core than in the length direction end regions, which makes it easy to inhibit leakage of menstrual blood or the like to the outside in the length direction.

[0055] In such an absorbent article, it is desirable that, when the absorbent core is divided into three in the width direction, i.e., into a width direction central region and width direction end regions (left and right), the weight of the high density portion contained per unit area of the width direction central region is greater than the weight of the high density portion contained per unit area of the width direction end regions.

[0056] According to the absorbent article, moisture such as menstrual blood is more likely to remain in the width direction central region of the absorbent core than in the width direction end regions, which makes it easy to inhibit leakage of menstrual blood or the like to the outside in the width direction.

[0057] In such an absorbent article, it is desirable that the absorbent core contains a high absorbency polymer, and the maximum outer diameter of the high density portion is greater than the maximum outer diameter of the high absorbency polymer.

[0058] According to the absorbent article, when a high absorbency polymer (SAP) swells, the possibility of a high density portion being disposed between adjacent 2 SAPs is high, and therefore, the SAPs are less likely to come into contact with each other, and gel blocking is inhibited. This makes it possible to inhibit a decrease in the absorbency of the SAP, and to improve the absorbency of the absorbent core.

[0059] In such an absorbent article, it is desirable that the average fiber length of the broadleaf wood liquid retaining fiber is less than 2 mm, and the absorbent core contains a liquid retaining fiber formed of a material other than a broadleaf tree, and that has an average fiber length longer than the average fiber length of the broadleaf wood liquid retaining fiber.

[0060] According to the absorbent article, the broadleaf wood liquid retaining fiber having a short fiber length and the liquid retaining fiber having a long fiber length are easily entangled, and the shape of the absorbent core is easily maintained. Therefore, compared to a case where the absorbent core is formed of only the liquid retaining fiber having a long fiber length, the softness is improved, the inter-fiber distance is made shorter, which makes it less likely for liquid to accumulate between the fibers, and the liquid return property is improved. In addition, compared to a case where the absorbent core is formed of only the liquid retaining fiber having a short fiber length, it is possible to inhibit the occurrence of shape collapse.

[0061] In such an absorbent article, it is desirable that the average fiber length of the hardwood liquid retaining fiber be less than 2 mm, and that the absorbent core contain a hydrophobic thermoplastic fiber having an average fiber length longer than the average fiber length of the hardwood liquid retaining fiber.

[0062] According to the absorbent article, by entangling the hardwood fiber having a short average fiber length with the fiber having a long average fiber length with each other, it becomes less likely that the shape of the absorbent core collapses. In addition, the inclusion of the hydrophobic fiber improves the diffusivity of moisture in the absorbent core. Thus, it is easy to absorb and retain moisture over a large area of the absorbent core. Therefore, it is possible to further improve the absorbency of the absorbent article.

[0063] In such an absorbent article, it is desirable that the average fiber length of the hardwood liquid retaining fiber be less than 2 mm, and that the absorbent core contain a hydrophobic thermoplastic fiber having an average fiber length longer than the average fiber length of the hardwood liquid retaining fiber. 2 less than 2500 fibers / mm 2 between a plurality of the hardwood liquid retaining fibers.

[0064] According to the absorbent article, the hardwood pulp having a short fiber width is dense, which improves the probability of contact of the excreted liquid with the fiber. In addition, since the probability of contact of a plurality of the hardwood pulp with the SAP is improved, it becomes more likely that the excreted liquid contained in the hardwood pulp is attracted by the superabsorbent polymer located between the fibers of the hardwood pulp, which makes it possible to reduce the backflow of liquid even in the absorption of a plurality of excreted liquids.

[0065] In such an absorbent article, it is desirable that the standard deviation of the fiber length of the hardwood liquid retaining fiber be 0.27 or less, and that the standard deviation of the fiber width of the hardwood liquid retaining fiber be 7.55 or less.

[0066] According to the absorbent article, when the distribution range is narrow and the standard deviation is small, it becomes easy to maintain a uniform fiber density in the absorbent body, which reduces the uneven distribution of the fiber in the planar direction, making it easy for the excreted liquid to diffuse in a concentric circular shape.

[0067] In such an absorbent article, it is desirable that the value obtained by adding the average fiber length of the hardwood liquid retaining fiber to the standard deviation of the fiber length of the hardwood liquid retaining fiber be less than twice the value of the average fiber length of the hardwood liquid retaining fiber; and that the value obtained by subtracting the standard deviation of the fiber length of the hardwood liquid retaining fiber from the average fiber length of the hardwood liquid retaining fiber be greater than 1 / 2 the value of the average fiber length of the hardwood liquid retaining fiber.

[0068] According to the absorbent article, further reduction in unevenness of fibers is achieved, and the excreted liquid is easily diffused uniformly.

[0069] In such an absorbent article, it is desirable that the absorbent core contain a plurality of thermoplastic fibers, the absorbent core has a press portion that integrally presses the absorbent core in the thickness direction, and the thermoplastic fibers are fusion-bonded to each other in the press portion.

[0070] According to the absorbent article, the thermoplastic fibers are fusion-bonded to each other, and this makes it easy to stabilize the shape of the absorbent body. Therefore, when the absorbent article is worn, even if the wearer moves the body greatly, it is easy to suppress the absorbent body from collapsing in shape or deteriorating in water absorbency.

[0071] In such an absorbent article, it is desirable that the absorbent article be at least any one of a sanitary napkin for use in menstruation, a sheet for use in secretion, and a light incontinence pad.

[0072] According to the absorbent article, it is possible to achieve a sanitary napkin for use in menstruation, a sheet for use in secretion, and a light incontinence pad that simultaneously have softness and absorbency.

[0073] In such an absorbent article, it is desirable that a pair of wings extending from a central region in the length direction to both outer sides in the width direction be provided.

[0074] According to the absorbent article, when the absorbent article is worn, by folding the wings from the outer sides in the width direction to the inner sides (crotch sides of the underpants of the wearer), it is possible to easily attach the absorbent article to an undergarment (underpants) or the like.

[0075] In such an absorbent article, it is desirable that an adhesive portion be provided on a non-skin side surface of the absorbent article, the adhesive portion being a portion for use in attaching the absorbent article to an undergarment of a wearer when the absorbent article is worn.

[0076] According to the absorbent article, when the absorbent article is worn, by attaching the adhesive portion to a skin side surface of an undergarment or the like of the wearer, the position of the absorbent article is fixed, and it is possible to suppress positional deviation.

[0077] In such an absorbent article, it is desirable that a functional substance be provided in at least a part of the absorbent core.

[0078] According to the absorbent article, since the functional substance is more likely to be held in the high-density portion of the absorbent core, it is possible to more effectively exert the function of the functional substance in the absorbent article. For example, holding an antibacterial agent in the high-density portion of the absorbent core makes it possible to more easily produce an antibacterial effect in a portion where urine or menstrual blood is accumulated. In addition, holding and accumulating a perfume, a cooling agent, a warming agent, or the like in the high-density portion makes it possible to easily maintain the effects of these functional substances for a long time.

[0079] In such an absorbent article, it is desirable that, when fibers contained in the absorbent core are separated by a shaking sieve machine according to the regulation of JIS K0069, a value obtained by dividing the weight of fibers remaining in a 14-mesh sieve of the shaking sieve machine by the weight of the absorbent core before the separation be larger than a value obtained by dividing the weight of fibers passing through a 60-mesh sieve of the shaking sieve machine by the weight of the absorbent core before the separation.

[0080] According to the absorbent article, the proportion of the high-density portion in which fibers are aggregated is high, so that, since voids are generated in the inside of the absorbent body, for example, moisture such as a body fluid easily passes through the absorbent body, which makes it possible to improve the liquid permeability of the absorbent core. In addition, the high-density portion itself easily holds liquid, so that the water retention of the absorbent core becomes high. Therefore, it is possible to further improve the water absorbency of the absorbent core.

[0081] Embodiment

[0082] <Basic structure of a sanitary napkin>

[0083] As an example of the absorbent article of the present embodiment, a sanitary napkin 1 (hereinafter, also simply referred to as "napkin 1") is described. In the following description, although a sanitary napkin is adopted as an example of an absorbent article, the absorbent article of the present embodiment also includes a so-called secretion sheet (for example, a sanitary pad), a light incontinence pad, and the like, and the present application is not limited to a sanitary napkin.

[0084] Figure 1 is a schematic plan view of the napkin 1 as viewed from the skin side in the thickness direction. Figure 2 is Figure 1 in the napkin 1 is a schematic cross-sectional view as viewed in the direction of the arrow A-A. In addition, as shown in Figure 1 and Figure 2The various directions employed in the following description are shown in the drawings. That is, the direction along the product length direction of the sanitary napkin 1 is defined as the "length direction", the direction orthogonal to the length direction along the short side direction of the product of the sanitary napkin 1 is defined as the "width direction", and the direction orthogonal to the length direction and the width direction is defined as the "thickness direction". In the length direction, the side corresponding to the wearer's abdomen when the sanitary napkin 1 is used is referred to as the "front side", and the side corresponding to the wearer's back is referred to as the "back side". In the thickness direction, the side that comes into contact with the wearer's skin when the sanitary napkin 1 is worn is referred to as the "skin side (upper side)", and the side opposite to the skin side is referred to as the "non-skin side (lower side)".

[0085] The sanitary napkin 1 is a sheet-like member having an elongated shape in plan view, and is formed by laminating a pair of side sheets 2, a topsheet (top sheet) 3, a second sheet 4, an absorbent body 10 (absorbent core), a cover sheet 6, and a backsheet (back sheet) 5 in this order from the skin side to the non-skin side in the thickness direction (see FIG. 1). These various members are joined to each other by an adhesive such as a hot-melt adhesive (HMA) or the like, which is adjacent in the thickness direction. Note that examples of the application pattern of the adhesive include an omega pattern, a spiral pattern, a stripe pattern, and the like. Figure 2 ) These various members are joined to each other by an adhesive such as a hot-melt adhesive (HMA) or the like, which is adjacent in the thickness direction. Note that examples of the application pattern of the adhesive include an omega pattern, a spiral pattern, a stripe pattern, and the like.

[0086] In addition, the sanitary napkin 1 includes a sanitary napkin main body portion 20 provided with the absorbent body 10, and a pair of wing portions 30 extending from the length direction central region of the sanitary napkin main body portion 20 to both outer sides in the width direction. The length direction central region provided with the wing portions 30 is a region that comes into contact with the wearer's discharge port (crotch portion) when the sanitary napkin 1 is used.

[0087] The topsheet 3 is a member that comes into contact with the wearer's skin when the sanitary napkin 1 is used, and allows a liquid such as menstrual blood or the like to permeate and move to the absorbent body 10 from the skin side to the non-skin side in the thickness direction. Therefore, the topsheet 3 is made of a soft sheet material of an appropriate type such as a hot-air nonwoven fabric or the like, which is liquid permeable.

[0088] The second sheet 4 is a liquid permeable sheet, and examples thereof include a hot-air nonwoven fabric or the like, which is the same as the topsheet 3. The second sheet 4 is provided on the skin side surface of the absorbent body 10, and functions to prevent backflow of excretions such as menstrual blood or the like, to improve diffusion of excretions, and to improve cushioning properties. However, the sanitary napkin 1 can also not have the second sheet 4.

[0089] The cover sheet 6 can be a liquid permeable sheet or a liquid impermeable sheet, and examples thereof include tissue paper (toweling), a spunbond / meltblown / spunbond (SMS) nonwoven fabric, or the like. The cover sheet 6 is provided between the absorbent body 10 and the backsheet 5. However, the sanitary napkin 1 can also not have the cover sheet 6.

[0090] The backing sheet 5 prevents liquid absorbed by the absorbent body 10 through the top sheet 3 from seeping into the clothing side (non-skin side), such as underwear, when using the sanitary napkin 1. The backing sheet 5 is made of a soft, impermeable sheet of a suitable type, such as a polyethylene (PE) resin film. It is explained that the planar dimensions of the top sheet 3 and the backing sheet 5 are larger than the planar dimensions of the absorbent body 10.

[0091] Side sheet 2 can be a liquid-permeable sheet or a liquid-impermeable sheet, examples of which include the same hot-air nonwoven fabric and SMS nonwoven fabric as top sheet 3.

[0092] Moreover, such as Figure 1 As shown, the outer peripheries of the side pieces 2, top piece 3, and back piece 5 are joined together by adhesive or fusion bonding, thereby holding the absorbent 10 between these pieces. Additionally, a pair of side pieces 2 extend outwards in the width direction from both sides of the top piece 3, forming a pair of wings 30 together with the back piece 5. Furthermore, as... Figure 2 As shown, on the non-skin side of the main body 20 of the sanitary napkin (the non-skin side surface of the backing 5), a plurality of main body adhesive portions (equivalent to anti-slip portions) formed by applying a suitable adhesive (e.g., hot melt adhesive) are provided at intervals in the width direction. When using the sanitary napkin 1, by attaching these main body adhesive portions to the skin side surface of the wearer's underwear or the like, the sanitary napkin 1 is fixed, thereby preventing positional displacement. Similarly, on the non-skin side of the wing 30 (the non-skin side surface of the backing 5), wing adhesive portions (equivalent to anti-slip portions) formed by applying a hot melt adhesive or the like are provided (see reference). Figure 2 ).

[0093] The absorbent core 10 is a longitudinally elongated component that absorbs and retains liquids (excrement) such as menstrual blood within its interior. Details regarding the absorbent core 10 will be described later. The second sheet 4, the absorbent core 10, and the cover sheet 6 have the same planar shape and are stacked in the thickness direction. It should be noted that in this embodiment, these components are joined together by hot melt adhesive (HMA), but they may not be joined together.

[0094] In addition, the sanitary napkin 1 is provided with multiple pressing portions 40 (recesses) (see reference). Figure 1). The press portion 40 is a portion recessed from the skin side to the non-skin side in the thickness direction, and is a portion having a higher fiber density than the adjacent portions. In the press portion 40, at least the entire thickness direction region of the top sheet 3, the second sheet 4, and the absorbent body 10 is pressed (embossed) from the skin side in the thickness direction, and these components are integrated. Thus, the sanitary napkin 1 is less likely to become distorted. However, the structure of the present application is not limited to the above structure, and can be a structure in which the press portion 40 is provided only on the absorbent body 10, or can be a structure in which the press portion 40 is provided only from the top sheet 3 to the portion of the absorbent body 10 located on the skin side in the thickness direction, or the press portion 40 can be provided from the back sheet 5 to the absorbent body 10. In addition, the arrangement pattern of the press portion 40 is not limited to the pattern shown in the drawing. Figure 1

[0095] <Configuration of Absorbent Body 10>

[0096] The absorbent body 10 has liquid-absorbing fibers, and is shaped in an elongated shape in plan view. In addition, the absorbent body 10 can contain materials other than the liquid-absorbing fibers (for example, hydrophobic fibers such as thermoplastic resin fibers). In the case of having the liquid-absorbing fibers and the thermoplastic resin fibers (hydrophobic fibers), the absorbent body 10 is formed in a state in which these fibers are mixed with each other.

[0097] Examples of the liquid-absorbing fibers include pulp such as wood pulp obtained from coniferous trees or broad-leaved trees; non-wood pulp such as bagasse, kenaf, bamboo, hemp, or cotton (for example, cotton linter); regenerated cellulose fibers such as rayon fibers; and semi-synthetic fibers such as acetate fibers.

[0098] In the absorbent body provided in the conventional absorbent article, coniferous wood liquid-absorbing fibers (also referred to as coniferous wood pulp) as liquid-absorbing fibers made of coniferous wood are used in many cases. In contrast, in the absorbent body 10 of the present embodiment, at least a part of the liquid-absorbing fibers includes broad-leaved wood liquid-absorbing fibers (also referred to as broad-leaved wood pulp) as liquid-absorbing fibers made of broad-leaved wood. The broad-leaved wood liquid-absorbing fibers (broad-leaved wood pulp) have a characteristic in which the fiber length is shorter than that of the coniferous wood liquid-absorbing fibers (coniferous wood pulp).

[0099] Figure 3A ​is a graph showing the distribution of fiber length of hardwood liquid-retentive fibers (hardwood pulp) and softwood liquid-retentive fibers (softwood pulp). The horizontal axis represents fiber length (mm), and the vertical axis represents frequency (%). As shown in the graph, the average fiber length of the softwood pulp is 2.5 mm, and the distribution range of fiber length is wide (including fibers of 3 mm or more, and the standard deviation is 1.6). In contrast, the average fiber length of the hardwood pulp is 0.79 mm, and the distribution range of fiber length is narrow (the standard deviation is 0.27). In the sanitary napkin 1 of the present embodiment, by using the hardwood pulp for the absorbent body 10, the average fiber length of the liquid-retentive fibers is made shorter (specifically, less than 2 mm).

[0100] Note that the average fiber length of the pulp fibers refers to the length-weighted average fiber length L(l) measured using the center-line fiber length (Cont). The length-weighted average fiber length is measured as an L(l) value by Kajaani Fiber Lab Fiber Properties (off-line) manufactured by Metso Automation USA, Inc. Note that this is also recommended by JIS P 8226-2 (Measurement methods of fiber length of pulp - by automated optical analysis method, non-polarizing method). In addition, the average fiber width of the pulp fibers described below is measured as Fiber Width.

[0101] The average fiber length and the average fiber width are measured excluding fiber clumps as described in the evaluation method of JIS. Therefore, the data of the average fiber length and the average fiber width shown in the present specification are results measured excluding the fiber clumps 100 described below.

[0102] In addition, the average fiber length of fibers other than the pulp fibers is measured in accordance with "A7.1.1 A Method (Standard Method) for measuring the length of each fiber on a glass plate with a scale" of "A7.1 Measurement of fiber length" of Appendix A of JIS L 1015:2010. The above method is a test method corresponding to ISO 6989 issued in 1981.

[0103] Examples of the thermoplastic resin fiber include a single fiber formed of polyethylene (PE), polypropylene (PP), or polyethylene terephthalate (PET), or the like, a fiber formed of PE and PP polymers, or a composite fiber formed of PP and PE and having a core-sheath structure, and the like. In addition, in the thermoplastic resin fiber, the degree of crimping can be adjusted. For example, as the thermoplastic resin fiber, by using a composite fiber of a core-sheath type or eccentric type formed of two synthetic fiber components having different melting points, the fiber can be crimped. In the present embodiment, the average fiber length of the thermoplastic resin fiber is about 30 mm. In addition, the average number of crimps per unit length of the thermoplastic resin fiber is set to be less than the average number of crimps per unit length of the liquid-retaining fiber. This reduces entanglement between the thermoplastic resin fiber and the liquid-retaining fiber, so that it is less likely to leave a crease. Therefore, even in the case of containing the thermoplastic resin fiber, it is possible to improve the comfort and improve the leakage prevention. Note that, as a method of measuring the average number of crimps, the following method can be employed: for example, a plurality of test pieces (for example, test pieces of 5 cm square size) arranged side by side in the width direction can be sampled, and using a microscope VH-Z450 manufactured by Keyence Corporation of Japan or the like, the number of crimps per 1 inch (2.54 cm) is measured several times in a state where no load is applied to the fibers in the test pieces. The number of crimps (average number of crimps per unit length) can be calculated from the average value thereof.

[0104] Figure 3B is a graph showing the distribution of the average fiber width of the broadleaf wood pulp and the coniferous wood pulp. The horizontal axis represents the fiber width (pm), and the vertical axis represents the frequency (%). As shown in Figure 3B the average fiber width of the coniferous wood pulp is about 30 pm (upper graph), and the distribution range of the fiber width is wide (standard deviation is 11.9). In contrast, the average fiber width of the broadleaf wood pulp is about 15 pm (lower graph), and the distribution range of the fiber width is narrow (standard deviation is 7.55). In the sanitary napkin 1 of the present embodiment, the use of the broadleaf wood pulp in the absorbent body 10 makes the average fiber width of the water-retaining fiber shorter compared to the case where only the coniferous wood pulp is used.

[0105] Furthermore, it is desirable that the average fiber width of the broadleaf wood pulp be 15 pm or less, and the fiber density number be 300 fibers / mm 2 or more and less than 2500 fibers / mm 2(absorbent polymer (SAP) and the like) between the pulp fibers. In this case, the fibers are short and thin, and thus the absolute area of the fibers is small, making it less likely for the fibers to entangle, and the hardwood pulp is dense with a short fiber width, which increases the probability of the exudate contacting the fibers, and the exudate contained in the hardwood pulp is more likely to be absorbed into the superabsorbent polymer between the pulp fibers, thus reducing the backflow of the liquid even in the absorption of multiple exudates.

[0106] In addition, as can be seen from the distribution range, both the distribution range of the fiber length and the distribution range of the fiber width of the hardwood pulp are narrower than those of the softwood pulp. That is, the standard deviation of the fiber length of the hardwood pulp is 0.27 or less, and the standard deviation of the fiber width of the hardwood pulp is 7.55 or less. Furthermore, the value obtained by adding the standard deviation of the fiber length of the hardwood pulp to the average fiber length of the hardwood pulp (0.79 + 0.27 = 1.06) is less than the value twice the average fiber length of the hardwood pulp (1.58), and the value obtained by subtracting the standard deviation of the fiber length of the hardwood pulp from the average fiber length of the hardwood pulp (0.79 - 0.27 = 0.52) is greater than the value one-half the average fiber length of the hardwood pulp (0.395).

[0107] As described above, the narrow distribution range and the small standard deviation make it easy to maintain a uniform fiber density in the absorbent body, which reduces the uneven distribution of the fibers in the planar direction, making it easy for the exudate to spread in a concentric circle shape.

[0108] In addition, the absorbent body 10 can contain fibers other than those described above, for example, natural fibers such as cellulose, regenerated cellulose fibers such as rayon, and the like.

[0109] In addition, the thickness of the absorbent body 10 is desirably 2 mm or more and 10 mm or less. When the thickness of the absorbent body 10 is less than 2 mm, the absorbent body 10 is too thin and is likely to be distorted, and when the thickness exceeds 10 mm, the absorbent body 10 is too hard and is likely to cause discomfort to the wearer.

[0110] In addition, since the hardwood pulp is finer and the distance between the fibers is shorter than the softwood pulp, the fiber number density of the hardwood pulp is greater than that of the softwood pulp when compared under the same density. Note that the fiber number density corresponds to the average fiber number per unit area, and is a value estimated from the number of fibers contained per unit area in a fine and dense packing structure by "fiber thickness + average fiber distance". From this estimated value, the fiber number density of the hardwood pulp is 1182.2 fibers / mm 2 , which is the fiber number density of the softwood pulp (200.3 fibers / mm 2about 6 times. Therefore, when using broadleaf wood pulp, the density can be increased compared to when using coniferous wood pulp.

[0111] It is desirable that the fiber number density be 300 fibers / mm 2 and less than 2500 fibers / mm 2 When the fiber number density is less than 300 fibers / mm 2 , although it is less likely to leave a fold, the absorbent 10 becomes thin and twisted in use, which reduces the area of the absorbent, making it more likely to leak. When the fiber number density is 2500 fibers / mm 2 or more, the absorbent 10 is processed too hard, and the discomfort in use increases. If the fiber number density is 300 fibers / mm 2 or more and less than 2500 fibers / mm 2 , the capillary effect can be increased, thinning and softening can be achieved, and the absorbency can be increased.

[0112] <Method of manufacturing the absorbent 10>

[0113] As a method of manufacturing the absorbent 10, a method of aggregating a pulverized pulp and a superabsorbent polymer or the like is known. Figure 4 A is a diagram that describes a method of manufacturing a pulverized pulp used in the absorbent 10. Figure 4 B is a diagram that describes a method of manufacturing the absorbent 10 using a pulverized pulp or the like. Note that this section will describe a case of manufacturing the absorbent 10 containing a liquid-retaining fiber, a thermoplastic resin fiber, and a superabsorbent polymer (SAP).

[0114] First, a pulverized pulp that is a raw material for the absorbent 10 is manufactured. The pulverized pulp is manufactured by pulverizing a pulp sheet PS that is a raw material using a conveyance mechanism 61 and a sawing machine 62. The conveyance mechanism 61 conveys the pulp sheet PS supplied from a roll in a prescribed direction. The sawing machine 62 is a rotating body provided with a plurality of blades on the outer peripheral surface of a cylindrical roller, and rotates on the downstream side in the conveyance direction to cut the pulp sheet PS as shown in Figure 4 A. Therefore, the pulp sheet PS is finely pulverized, and a pulverized pulp that is a raw material for the absorbent 10 is manufactured. Note that instead of the sawing machine 62, a hammer-type pulverizer can be used to pulverize the pulp sheet PS in a manner of striking.

[0115] In the past, in the case of pulverizing pulp sheets made of coniferous wood, the fibers of the coniferous wood pulp were broken one by one, and long linear coniferous wood pulp fibers (average fiber length of about 2.5 mm) were formed. On the other hand, in the present embodiment, pulp sheets PS containing broadleaf wood pulp are used. As described above, in the broadleaf wood pulp (broadleaf wood pulp fibers), the average fiber length is short (average fiber length of less than 2 mm), so that the fibers are less likely to entangle with each other as compared with the coniferous wood pulp. Therefore, in the pulp sheets PS containing the broadleaf wood pulp, the sites where the fibers entangle with each other are less, and the pulp sheets are brittle and likely to collapse. When such pulp sheets PS are pulverized by the chipper 62, the fibers of the broadleaf wood pulp do not break one by one, but fiber blocks 100 (also referred to as so-called "knots") in which a plurality of fibers are gathered in a fiber ball (fiber cluster) form are separated from the pulp sheets PS and collapse.

[0116] In addition, as described above, the average fiber width of the broadleaf wood pulp is about 15 μm. That is, the broadleaf wood pulp has a characteristic that not only the fiber length is short but also the fiber is thin. Therefore, in the broadleaf wood pulp, the cross-sectional area and the volume of each fiber are small, and the fibers are more likely to be gathered in a fiber ball form, and the amount of fibers contained in the fiber ball is more than that in the case of the coniferous wood. Note that it is not preferable to form such fiber blocks using the pulp manufactured by the conventional air-laid method. This is because: the binder contained between the pulp fibers easily hinders the suction of moisture, and makes the fiber blocks themselves hard. In addition, since the pulp is cellulose, it is difficult to perform heat fusion bonding. Therefore, it is difficult to form the fiber blocks using a method such as heat fusion bonding.

[0117] Figure 5 is an enlarged photograph of the fiber block 100 obtained when the pulp sheet containing the broadleaf wood pulp is pulverized. As shown in Figure 5 the fiber block 100 obtained in the present process includes: a central portion 101 in which the broadleaf wood pulp fibers are gathered at a high density, and a fluff portion 102 around the central portion 101 in which the density is lower than that of the central portion 101. The fluff portion 102 is formed by peeling the portion where the fibers are entangled with each other from the pulp sheet PS. That is, the pulp sheet PS is formed by gathering a plurality of such fiber blocks 100, and therefore, by cutting the pulp sheet PS by the chipper 62, the portion where the adjacent fiber blocks 100 and 100 are entangled is peeled, and separated into individual fiber blocks 100, and at the same time, the portion where the entanglement is peeled becomes the fluff portion 102.

[0118] In the present embodiment, the "fiber block 100" is obtained as follows: the pulp sheet PS containing the broadleaf wood pulp is pulverized by the chipper 62, and the fiber blocks 100 are separated from the pulp sheet PS. Figure 4A shown method of pulverizing pulp sheet PS to obtain a sample using a shaking sieve machine (for example, a shaking sieve machine SS-HK60 manufactured by Azone Corporation) that conforms to the test method prescribed in JIS K 0069, separating by fiber size, and taking as "fiber block 100" those that satisfy the following conditions. First, the sample is placed on a 14-mesh sieve provided on the shaking sieve machine. Note that the "sieve" refers to a standard sieve metal mesh prescribed in JIS Z 8801, and for example, a 14-mesh sieve refers to a metal mesh with a mesh opening of 1.18 mm, a wire diameter of 0.63 mm, and an open area of 42.3%. In addition, a cylinder having the same diameter as the sieve is installed below the sieve, and a suction device (for example, a Wonder-Gun W101 manufactured by Osawa & Company, minimum suction inner diameter: 22 mm, pressure: 0.5 Mpa) is installed in a hole punched in the side of the cylinder at a height of 70 mm below the sieve in such a way as to not form a gap. Further, an air ejection device (for example, an air gun AG-101 manufactured by TONE, nozzle length: 95 mm, nozzle inner diameter: 4 mm, pressure: 0.5 Mpa) is installed at a height of 50 mm above the sieve. Next, while oscillating at an amplitude of 70 mm and 60 times / minute for 15 minutes, the air ejection device is caused to uniformly eject air, and at the same time, the suction device is used to suction air, and fibers are separated from the sample. Then, those remaining on the sieve (14-mesh) after 15 minutes are taken as "fiber block 100 (knots)"

[0119] In addition, in the photograph in Figure 5 A, white fiber block 100 is shown in a black background, but in the central portion of the fiber block 100, the area in which the black background cannot be seen through is the central portion 101 in which the hardwood preservative fibers are gathered at a high density. On the other hand, around the central portion 101, the portion in which the black background can be seen through the fiber block 100 is the fluff portion 102.

[0120] Next, the fiber block 100 is used to manufacture the absorbent body 10. As shown in Figure 4 B, the drum 70 is a hollow cylindrical cylinder, and a plurality of recesses 71 are formed at a prescribed pitch on the circumferential surface thereof as molds for filling the absorbent material. When the drum 70 is rotated so that the recesses 71 enter the material supply portion 80, the absorbent material supplied from the material supply portion 80 is deposited (gathered) into the recesses 71 due to suction by the suction portion 72.

[0121] The material supply portion 80 with the protective cover 80a is formed in such a way as to cover the upper portion of the drum 70, and the material supply portion 80 supplies the recesses 71 with the pulp sheet PS using a pulverizer (refer to Figure 4A) a mixture of the pulverized pulp (containing at least broadleaf wood pulp and fiber blocks 100) obtained by pulverization and a thermoplastic resin. In addition, the material supply section 80 includes a particle supply section 81 for supplying superabsorbent polymer particles (SAP), and supplies the superabsorbent polymer particles to the recesses 71. The mixture of the water-absorbent fibers and the thermoplastic fibers and the superabsorbent polymer particles are deposited in the mixed state in the recesses 71, and the absorbents 10 are formed in the recesses 71.

[0122] When the recesses 71 in which the absorbents 10 are housed reach the bottommost portion of the drum due to further rotation of the drum 70, the absorbents 10 are released from the recesses 71, placed on the base material (e.g., the cover sheet 6, etc.) conveyed by the conveyer, and transferred to the next process.

[0123] The absorbents 10 formed contain the liquid-retaining fibers in a plurality of fiber blocks 100 at high density. That is, the high-density portions formed of the fiber blocks 100 are dispersed in the absorbents 10. Therefore, in the region in which the fiber blocks 100 (high-density portions) are dispersed in the absorbents 10, the density of the liquid-retaining fibers is higher in the central portion in the thickness direction than in the end portions in the thickness direction, unlike the press section 40. In other words, the absorbents 10 have a low-density portion in which the density of the liquid-retaining fibers is lower than in the high-density portion on one side in the thickness direction or on the other side in the thickness direction of at least one high-density portion (fiber block 100).

[0124] Note that the density of the fiber blocks 100 (high-density portions) can be measured as follows. First, the weight of the fiber blocks 100 is measured using an electronic balance or the like. At this time, if the weight of the fiber blocks 100 is less than the minimum measurable weight of the electronic balance, a plurality of the fiber blocks 100 are gathered and measured until the weight can be measured, and the average value is defined as the average weight of the fiber blocks 100. Next, the thickness (Z-direction length of B described later) of the fiber blocks 100 is measured by a microscope. As described above, when a plurality of the fiber blocks 100 are gathered to measure the weight, the thickness is measured for all of the fiber blocks 100 used for the weight measurement, and the average value is defined as the average thickness of the fiber blocks 100. Similarly, the area (XY-plane area of A described later) of the fiber blocks 100 is measured by the measurement of the microscope. At this time, the areas of all of the fiber blocks 100 for which the weight measurement was performed are measured, and the average value is defined as the average area of the fiber blocks 100. Based on these measured values (calculated values), the density of the fiber blocks 100 can be calculated by "average weight / (average thickness x average area)". Figure 6 B of the Z-direction length). As described above, when a plurality of the fiber blocks 100 are gathered to measure the weight, the thickness is measured for all of the fiber blocks 100 used for the weight measurement, and the average value is defined as the average thickness of the fiber blocks 100. Similarly, the area (XY-plane area of A described later) of the fiber blocks 100 is measured by the measurement of the microscope. At this time, the areas of all of the fiber blocks 100 for which the weight measurement was performed are measured, and the average value is defined as the average area of the fiber blocks 100. Based on these measured values (calculated values), the density of the fiber blocks 100 can be calculated by "average weight / (average thickness x average area)". Figure 6 B of the Z-direction length). As described above, when a plurality of the fiber blocks 100 are gathered to measure the weight, the thickness is measured for all of the fiber blocks 100 used for the weight measurement, and the average value is defined as the average thickness of the fiber blocks 100. Similarly, the area (XY-plane area of A described later) of the fiber blocks 100 is measured by the measurement of the microscope. At this time, the areas of all of the fiber blocks 100 for which the weight measurement was performed are measured, and the average value is defined as the average area of the fiber blocks 100. Based on these measured values (calculated values), the density of the fiber blocks 100 can be calculated by "average weight / (average thickness x average area)".

[0125] <Performance of the absorbents 10>

[0126] In the absorbent body 10 (absorbent core) of the present embodiment, by providing the plurality of fiber blocks 100 in a dispersed manner, the liquid absorbency and softness are improved compared to the absorbent body of the conventional product.

[0127] As described above, the liquid-retaining fibers are gathered at a high density in the fiber block 100, and therefore, the density of the liquid-retaining fibers is higher in the portion of the absorbent body 10 in which the fiber block 100 (high-density portion) is disposed than in other portions. That is, the absorbent body 10 includes the fiber block 100 as a high-density portion and a low-density portion in which the density of the liquid-retaining fibers is lower than in the high-density portion (fiber block 100). The fiber block 100 (high-density portion) is disposed adjacent to the low-density portion in the thickness direction of the absorbent body 10. In other words, the absorbent body 10 of the present embodiment includes the fiber block 100 as a high-density portion and a low-density portion adjacent to one side (skin side) or the other side (non-skin side) in the thickness direction of each high-density portion. The high-density portion and the low-density portion are provided in the thickness direction of the absorbent body 10 so that the volume (thickness) of the absorbent body 10 is easily maintained compared to a case in which the high-density portions are continuously disposed in the thickness direction like the press portions 40, so that an absorbent body 10 that is soft and has high cushioning properties can be achieved.

[0128] According to such an absorbent body 10, when moisture such as menstrual blood adheres to the skin side in the thickness direction of the absorbent body 10, for example, the moisture is absorbed in the thickness direction of the absorbent body 10 and easily moves from the low-density portion to the high-density portion (fiber block 100) due to capillary phenomenon. That is, the low-density portion and the high-density portion (fiber block 100) are disposed adjacent to each other in the thickness direction of the absorbent body 10 so that the absorbed moisture can be guided and held in the fiber block 100. Therefore, the entire absorbent body 10 (absorbent core) easily absorbs and holds the moisture, so that the absorbency of the absorbent body 10 can be improved.

[0129] In addition, since the liquid-retaining fibers included in the absorbent body 10 (absorbent core) of the present embodiment are made of broadleaf wood liquid-retaining fibers, the average fiber length is short, the fiber diameter is thin, and therefore the cross-sectional area and volume of each fiber are small compared to liquid-retaining fibers made of coniferous wood fibers. Therefore, the number of entanglement points at which one broadleaf wood liquid-retaining fiber is entangled with another broadleaf wood liquid-retaining fiber is small, and in addition, the area (volume) of the entanglement points is reduced. This makes it less likely for the fibers to be entangled with each other compared to coniferous wood water-retaining fibers. Therefore, the movement of the liquid-retaining fibers is less likely to interfere with each other, the softness of the absorbent body 10 is improved, so that it is less likely for the user of the sanitary napkin 1 to feel stiffness.

[0130] Furthermore, compared to liquid-retaining fibers formed solely from coniferous wood fibers, the shorter fiber width reduces the number of entanglement points when viewed in the planar direction. Additionally, the fiber thickness is smaller compared to liquid-retaining fibers formed solely from coniferous wood fibers. Therefore, with equal density and thickness of the absorbent, a large amount of broadleaf wood fibers can be incorporated in the thickness direction compared to using only coniferous wood fibers, while achieving the same or lower stiffness, thus making it less likely that the wearer will perceive the stiffness of the absorbent 10.

[0131] In particular, the absorbent body 10 of the sanitary napkin 1 comprises multiple densely packed fiber blocks 100 (high-density sections) of liquid-retaining fibers. When this high-density section is formed from long-fibered coniferous water-retaining fibers, the number of tangles increases, and the high-density section becomes harder, potentially causing the wearer to experience a harder and more uncomfortable feeling when wearing the sanitary napkin. In contrast, in this embodiment, the liquid-retaining fibers constituting the fiber blocks 100 (high-density sections) are short in length, and the number of tangles is reduced. This increases the softness of the fiber blocks 100 (high-density sections) themselves, making it less likely to cause the wearer to experience a feeling of hardness and discomfort.

[0132] As described above, in the absorbent core 10 of this embodiment, by providing a high-density section (fiber block 100) densely packed with liquid-retaining fibers made of broadleaf wood in a dispersed form, both good absorbency and good softness can be achieved. It should be noted that highly absorbent polymer particles (SAP) can be contained within the high-density section (fiber block 100). In this case, since the proportion of SAP in contact with the liquid-retaining fibers increases, the absorption performance of the absorbent core 10 when repeatedly absorbing moisture can be improved.

[0133] In addition, such as Figure 5 As explained, the fiber block 100 includes a central portion 101 and a napped portion 102 outside the central portion 101. The central portion 101 is a portion where liquid-retaining fibers are densely packed, and the napped portion 102 is a portion where the density of liquid-retaining fibers is lower than that of the central portion 101. The central portion 101 is surrounded by the napped portion 102, which is surrounded by fibers other than those in the fiber block 100 (i.e., fibers constituting the low-density portion of the absorbent body 10). That is, the napped portion 102 is entangled with the fibers constituting the low-density portion of the absorbent body 10, while the central portion 101 is not entangled with the fibers constituting the low-density portion, but is entangled with the napped portion 102. Therefore, when the absorbent body 10 absorbs moisture such as excrement, firstly, the liquid-retaining fibers constituting the low-density portion absorb moisture, and the moisture absorbed by the low-density portion moves to the central portion 101 of the fiber block 100 via the napped portion 102 due to capillary action. In this way, the water absorbed by the absorbent 10 is drawn into the center from the outside of the fiber block 100.

[0134] In such a fiber block 100, if the total amount (weight) of the liquid-retaining fibers contained in the central portion 101 is greater than the total amount (weight) of the liquid-retaining fibers contained in the fluff portion 102, the amount of moisture that can be held in the central portion 101 increases, and the water absorbency of the absorbent body 10 can be improved. That is, in the central portion 101 of the fiber block 100 (high-density portion), a large amount of moisture is easily drawn from the surroundings, and the total amount of moisture that can be held by the absorbent body 10 can be increased.

[0135] On the contrary, the total amount (weight) of the liquid-retaining fibers contained in the central portion 101 can be less than or equal to the total amount (weight) of the liquid-retaining fibers contained in the fluff portion 102. In this case, the area of the fluff portion 102 surrounding the central portion 101 is large, but the density of the fluff portion 102 is lower than that of the central portion 101, and thus a large number of voids are formed among the liquid-retaining fibers, so that the fluff portion 102 is easily deformed when an external force is applied. Therefore, the absorbent body 10 containing such a fiber block 100 is high in softness, and the skin touch feeling when the sanitary napkin 1 is worn becomes soft, so that it is less likely to cause the wearer to feel uncomfortable. In addition, since a large number of voids are present in the fluff portion 102, even a liquid containing a substance other than water, such as menstrual blood, easily passes through the fluff portion 102 and reaches the central portion 101. Therefore, it is possible to improve the softness while ensuring good absorbency.

[0136] Figure 6 A is a schematic plan view of the fiber block 100 as viewed in a prescribed direction. Figure 6 B is Figure 6 A is a view of A taken along arrows B-B. In Figure 6 A and Figure 6 B, when "X direction", "Y direction", and "Z direction" are defined as three directions orthogonal to each other, Figure 6 A indicates an example of the shape of the fiber block 100 on the XY plane, Figure 6 B indicates an example of the shape of the fiber block 100 on the XZ plane. Hereinafter, also Figure 6 The "XY direction" in A is referred to as the "planar direction" of the fiber block 100, and the "XZ direction" in A is referred to as the "thickness direction" of the fiber block 100. Figure 6 The "XZ direction" in B is referred to as the "thickness direction" of the fiber block 100.

[0137] As shown in Figure 6 A and Figure 6 B, the shape of the fiber block 100 (high-density portion) is planar, and the length in the Z direction is shorter than the lengths in the X direction and the Y direction. Specifically, in Figure 6 A, the diameter of a circle circumscribing the fiber block 100 in the central portion 101 is denoted as Rc, the diameter of a circle circumscribing the fiber block 100 in the fluff portion 102 is denoted as Ro, and Figure 6The length (width) of the fiber block 100 in the Z direction on the XZ plane of B is denoted as Ho, where Ho is shorter than Ro (Ro > Ho). That is, the maximum width (Ro) of the area occupied by the napped portion 102 in the X and Y directions is greater than the maximum width Ho of the area occupied by the napped portion 102 in the Z direction. It should be noted that the shape of the fiber block 100 is not fixed, and the maximum length of the napped portion 102 in the X direction may not be the same as the maximum length in the Y direction. However, for ease of explanation in this specification, the diameter Ro of the circumcircle of the napped portion 102 is defined as the maximum length of the fiber block 100 in the X and Y directions (planar directions).

[0138] In addition, Figure 6 A and Figure 6 In the fiber block 100 shown in B, when there is no significant unevenness in the fiber density distribution in the napped portion 102, the total amount (weight) of fibers in the napped portion 102 in the planar direction (XY direction) of the fiber block 100 is greater than the total amount (weight) of fibers in the napped portion 102 in the thickness direction (Z direction) of the fiber block 100. When the fiber block 100 (high-density portion) is arranged adjacent to the low-density portion inside the absorber 10, the gradient of fiber density in the thickness direction (Z direction) of the fiber block 100 is greater than the gradient of fiber density in the planar direction (X and Y directions). Therefore, in the fiber block 100, capillary action is more likely to occur more strongly in the thickness direction, and moisture is more likely to be absorbed in the thickness direction. In addition, when the fiber block 100 absorbs moisture, the moisture introduced and retained in the central portion 101 is unlikely to diffuse from the center outward in the planar direction. This is because the napped portion, which diffuses radially from the central portion 101 in the planar direction, inhibits the movement of moisture from the center outward in the planar direction.

[0139] The fiber density gradients in the planar and thickness directions can be determined, for example, by the following method. First, using a microscope, the area Sh1 of the high-density portion in the planar direction is measured, and the area Sh2 of the entire region (high-density portion + low-density portion) in the planar direction is measured. Then, Sh1 / Sh2 is calculated and defined as the density gradient in the planar direction. Similarly, using a microscope, the area St1 of the high-density portion in the thickness direction is measured, and the area St2 of the entire region (high-density portion + low-density portion) in the thickness direction is measured. Then, St1 / St2 is calculated and defined as the density gradient in the thickness direction. By comparing the calculated Sh1 / Sh2 and St1 / St2, it can be determined that the larger this value is, the smaller the proportion of low-density regions, that is, the smaller the gradient between roughness and density.

[0140] Moreover, among the plurality of fiber blocks 100 included in the absorbent body 10 (absorbent core), there are cases where the fiber blocks 100 are arranged with their thickness directions (Z directions) along the thickness direction of the absorbent body 10 (absorbent core), and cases where the fiber blocks 100 are arranged with their thickness directions (Z directions) along a direction perpendicular to the thickness direction of the absorbent body 10 (absorbent core). The proportion (number) of the former fiber blocks 100 is greater than the proportion (number) of the latter fiber blocks 100. That is, it is more likely that the fiber blocks 100 are arranged so that the planar direction (length direction and width direction) of the absorbent body 10 coincides with the planar direction (X direction and Y direction) of the fiber blocks 100. This makes it easier for the absorbent body 10 to absorb moisture in the thickness direction, makes it less likely for the absorbed moisture to spread in the length direction, and improves the absorbency of the sanitary napkin 1 in the width direction. Note that the state where the thickness direction of the fiber blocks 100 is along the thickness direction of the absorbent body refers to a state where the angle formed between the thickness direction of the absorbent body and the thickness direction of the fiber blocks 100 is less than 45 degrees. In addition, among the fiber blocks 100 included in the absorbent body 10, the proportion where the planar direction of the absorbent body 10 coincides with the planar direction of the fiber blocks 100 can be found by cutting the absorbent body 10 to a prescribed size (for example, 1 cm square), and checking the relationship between the thickness direction of each fiber block 100 included in the absorbent body 10 and the thickness direction of the absorbent body 10.

[0141] In addition, it is preferable that, in the planar direction (XY direction) of the A, Figure 7 That is, it is preferable that, in the planar direction of the fiber blocks 100, the width of the region where the central portion 101 is formed is greater than the width of the region where the fuzz portion 102 is formed. In this case, the proportion of the fuzz portion 102 in the fiber blocks 100 decreases, which reduces the sites where the fibers constituting the fuzz portion 102 and the fibers in the low-density portion (absorbent body 10) around the fuzz portion 102 are entangled with each other. Thus, this weakens the bonding of the fiber blocks 100 and the low-density portion, making the absorbent body 10 soft overall. Therefore, it is possible to further improve the softness of the sanitary napkin 1.

[0142] On the other hand, in the planar direction (XY direction) of the A, Figure 7In the planar direction (XY direction) of A, the diameter Rc of the circumscribed circle of the central portion 101 can be less than or equal to the difference between the diameter Ro of the circumscribed circle of the napped portion 102 and the diameter Rc of the circumscribed circle of the central portion 101 ((Ro-Rc)≥Rc). That is, in the planar direction of the fiber block 100, the width of the region forming the central portion 101 can also be less than or equal to the width of the region forming the napped portion 102. In this case, the proportion of the napped portion 102 in the fiber block 100 increases, which increases the portion where the fibers constituting the napped portion 102 become entangled with the fibers in the low-density portion (absorbent body 10) surrounding the napped portion 102. This makes it easier to fix the position of the fiber block 100 inside the absorbent body 10, making it less likely for the absorbent body 10 to twist or deform. For example, even if the wearer moves their body significantly when using the sanitary napkin 1, it is possible to prevent the absorbent body 10 from collapsing. As described above, the composition of the fiber block 100 included in the absorbent body 10 can be adjusted according to how the sanitary napkin 1 is used.

[0143] Furthermore, the absorption performance of the absorber 10 can be improved by arranging at least one of the plurality of fiber blocks 100 included in the absorber 10 in the thickness direction in the following manner. Figure 7 A~ Figure 7 Figure C illustrates the arrangement of the fiber blocks 100 in the thickness direction of the absorber 10.

[0144] Figure 7 A is a schematic cross-sectional view showing the arrangement of the fiber block 100 in contact with a sheet member adjacent to the skin side in the thickness direction of the absorbent 10. Figure 7 In case A, moisture (e.g., menstrual blood) excreted into the sheet member (e.g., the second sheet 4, the top sheet 3) adjacent to the skin side of the absorbent 10 is drawn into the interior of the absorbent 10 by the fiber block 100 (high-density portion) adjacent to the non-skin side of the sheet member in the thickness direction. The moisture is retained in the central portion 101 of the fiber block 100, making it unlikely that moisture will remain on the surface of the sheet (second sheet 4 or top sheet 3) on the skin side. Furthermore, moisture retained in the central portion 101, where the liquid-retaining fibers are concentrated in a high density, is unlikely to move to the outside of the central portion 101, making it unlikely that so-called rewetting (where moisture returns from the interior of the absorbent 10 to the skin side) will occur. Therefore, by arranging the fiber block 100 in contact with the sheet member adjacent to the skin side in the thickness direction of the absorbent 10, moisture is unlikely to come into contact with the wearer's skin when using the sanitary napkin 1, thus suppressing skin problems such as rashes and preventing discomfort to the wearer.

[0145] Figure 7 B is a schematic cross-sectional view showing the arrangement of the fiber block 100 in contact with the sheet member adjacent to the non-skin side in the thickness direction of the absorbent 10.Figure 7 In B, moisture (e.g., excreted menstrual blood, etc.) penetrates from the skin side of the absorbent body to the non-skin side, and is held in the fiber block 100 (high-density portion) provided in contact with the sheet member (e.g., cover sheet 6) on the non-skin side in the thickness direction of the absorbent body 10. That is, the moisture is more likely to concentrate on the non-skin side in the thickness direction of the absorbent body 10. This makes it less likely for the moisture to remain on the skin side of the absorbent body 10 in contact with the wearer's skin when the sanitary napkin 1 is worn. In addition, the moisture is held near the cover sheet 6 on the non-skin side farthest from the skin side, which makes it less likely for rewetting, etc., to occur. Therefore, even in the case where the fiber block 100 is provided in contact with the sheet member on the non-skin side in the thickness direction of the absorbent body 10, the moisture is less likely to contact the wearer's skin when the sanitary napkin 1 is used, making it possible to inhibit the occurrence of skin problems such as skin rash, etc., and to make the wearer feel uncomfortable.

[0146] Figure 6 C is a schematic cross-sectional view showing the case where the fiber block 100 is arranged in contact with the sheet member on both the skin side and the non-skin side in the thickness direction of the absorbent body 10. Figure 6 C shows the case where one fiber block 100 is in contact with both the skin side and the non-skin side, but it can also be that each of a plurality of fiber blocks 100 is in contact with the skin side or the non-skin side. In this case, the proportion of the fiber block 100 in the thickness direction of the absorbent body 10 becomes higher, making it easy for the moisture to be held in a large range in the thickness direction of the absorbent body 10. That is, it is possible to increase the water retention capacity in the thickness direction of the absorbent body 10 compared to the case where the fiber block 100 is not present in the absorbent body 10. Also, it is possible to obtain Figure 1 A and Figure 1 The effect explained in B makes it possible to further improve the absorbency of the absorbent body 10 while making it less likely for the wearer to feel uncomfortable.

[0147] In addition, as explained in Figure 8 In the sanitary napkin 1, a plurality of press portions 40 of the unit press top sheet 3 (and the second sheet 4) and the absorbent body 10 (absorbent core) are provided, as explained in Figure 8 As shown, these press portions 40 include linear press portions 41 (so-called hinges) having a prescribed width and extending in the length direction. When the sanitary napkin 1 is used, when the absorbent body 10 is bent and deformed according to the body shape of the wearer, the linear press portions 41 each function as a bending guide portion, and the linear press portions 41 also have the function of moving the moisture (e.g., menstrual blood, etc.) absorbed by the absorbent body 10 along the linear press portions 41. Therefore, it is possible to prevent the menstrual blood, etc., from being concentrated and absorbed into one portion of the absorbent body 10 beyond the absorption capacity of that portion. That is, by dispersing the moisture (e.g., menstrual blood, etc.) in a large range of the absorbent body 10, it is possible to absorb the moisture in a wide area of the absorbent body 10.

[0148] However, since the linear pressing portion 41 is embossed or the like from the skin side in the thickness direction, the density of the linear pressing portion 41 is higher than the density of other regions of the absorbent body 10, so moisture easily moves, and therefore, for example, menstrual blood or the like sometimes excessively spreads along the linear pressing portion 41. That is, it is possible that menstrual blood or the like does not get absorbed in the thickness direction of the absorbent body 10, but rather becomes more likely to spread in the planar direction (length direction or width direction).

[0149] In contrast, in the present embodiment, the fiber block 100 (high-density portion) is provided so as to contact the pressing portion 40 (linear pressing portion 41) in at least a portion of the thickness direction of the absorbent body 10, making it possible to control the spread of moisture. Figure 8 A is a schematic cross-sectional view of the absorbent body 10 of a region in which the pressing portion 40 (linear pressing portion 41) is provided. In Figure 8 In A, the fiber block 100 is provided so as to contact the non-skin side of the linear pressing portion 41 in the thickness direction. In this case, a portion of the moisture that moves in the planar direction along the linear pressing portion 41 moves from the skin side to the non-skin side in the thickness direction in a manner that is attracted (absorbed) by the fiber block 100. It is possible to suppress the excessive spread of moisture in the planar direction of the absorbent body 10 along the linear pressing portion 41, and it is possible to improve the absorbency of the absorbent body 10.

[0150] Note that, in the linear pressing portion 41 (hinge), since the entire region of the absorbent body 10 in the thickness direction is continuously pressed by embossing or the like, it is possible that the following problems occur. That is, when the sanitary napkin 1 is worn, it is more likely that a gap is created between the wearer's skin and the back sheet 5. In addition, at the linear pressing portion 41, the thickness of the absorbent body 10 is reduced, which reduces the water retention capacity when viewed in the planar direction (length direction and width direction) of the absorbent body 10. In addition, since the absorbent body 10 is pressed in the linear pressing portion 41, the skin touch can become poor. In contrast, in the case where the fiber block 100 is in contact with the linear pressing portion 41, due to the action of the central portion 101 (high-density region) of the fiber block 100 and the raised portion 102 (low-density region) that surrounds the central portion 101, it is less likely that the above-mentioned problems occur.

[0151] In addition, sometimes the pressing portion 40 includes a high-pressing portion 45 in which the absorbent core is strongly pressed, and a low-pressing portion 46 in which the absorbent core is pressed to have a lower density than the high-pressing portion 45. Figure 8 B is a schematic cross-sectional view of the absorbent body 10 of a region in which the pressing portion 40 (linear pressing portion 41) having the high-pressing portion 45 and the low-pressing portion 46 is provided. In Figure 6In B, the region from the skin side to the non-skin side in the thickness direction that is pressed deeply is the high-pressing portion 45, and the region that is pressed more shallowly than the high-pressing portion 45 is the low-pressing portion 46. In the case where all of the pressing portions 40 are high-pressing portions 45, it is possible that the absorbent body 10 is excessively bent in the high-pressing portion 45, making it easy for the absorbent body 10 to break or less likely to fit the subtle concavities and convexities of the wearer's body. In contrast, by providing the low-pressing portion 46, it is possible to suppress excessive deformation of the absorbent body 10 and prevent the absorbent body 10 from breaking.

[0152] Further, in the sanitary napkin 1 of the present embodiment, at least a part of the fiber block 100 (high-density portion) is provided in contact with the low-pressing portion 46 in the thickness direction. In the example of B, the low-pressing portion 46 and the fiber block 100 are in contact with each other in the thickness direction, and the high-pressing portion 45 and the fiber block 100 are in contact with each other in the width direction. According to such a configuration, moisture such as menstrual blood that moves in the planar direction along the high-pressing portion 45 and the low-pressing portion 46 is easily drawn into the thickness direction of the absorbent body by the fiber block 100, and thus it is possible to balance the soft fit and the absorbency of the absorbent body 10. Figure 1

[0153] Note that the sanitary napkin 1 has a plurality of creases extending in the width direction, and the sanitary napkin 1 is distributed to the market after being individually packaged in a state of being folded in the length direction by the creases. For example, the absorbent body is folded at two positions in the length direction, i.e., a first crease and a second crease (both not shown) are provided near both ends in the length direction of the wing portion 30. That is, the first crease and the second crease are folding guides for folding the absorbent body 10. In the case where such folding guides are provided, the fiber block 100 (high-density portion) can be provided in contact with the folding guides in the thickness direction. In this case, moisture is easily drawn into the inside of the absorbent body 10 even in the folding guides (creases), and it is possible to suppress the moisture from remaining on the skin side surface of the creases.

[0154] Further, in such a case, it is preferable that the average density of the fiber block 100 be higher than the average density of the absorbent body 10 in the folding guides. According to the above-described configuration, even in the case where excreted liquid flows into the folding guides, the excreted liquid is more likely to be absorbed by the fiber block 100, making it possible to suppress the excreted liquid from spreading in the width direction along the folding guides. Thus, it is possible to suppress leakage of the excreted liquid.

[0155] ​Further, as another way of the folding guide portion, a low basis weight region (not shown) having a lower basis weight than other regions of the absorbent body 10 can be provided. For example, in a case where a low basis weight region extending in the length direction is provided in the central portion in the width direction of the absorbent body, the absorbent body 10 is more likely to be folded in a mountain shape in the width direction, and the absorbent body 10 is more likely to fit the crotch portion of the wearer when the sanitary napkin 1 is worn. In a case where such a low basis weight region is provided, the fiber block 100 (high density portion) can be provided so as to be in contact with the low basis weight region in the thickness direction. In this case, even in the folding guide portion (low basis weight region), moisture is easily absorbed into the inside of the absorbent body 10, and the retention of moisture on the skin side surface of the low basis weight region can be suppressed.

[0156] Further, in the sanitary napkin 1 of the present embodiment, it is preferable that the weight of the fiber block 100 per unit area in the central region in the length direction of the absorbent body 10 (absorbent core) be greater than the weight of the fiber block 100 per unit area in the both end regions in the length direction. For example, in the central region in the length direction of the absorbent body 10, the amount of the fiber block 100 contained in the central region can be increased by increasing the thickness compared to the both end regions. The density of the fiber block 100 can also be made higher in the central region in the length direction than in the both end regions. In this case, moisture such as menstrual blood is more likely to remain in the central region in the length direction of the absorbent body 10 than in the both end regions in the length direction of the absorbent body 10. This makes it possible to easily suppress leakage of menstrual blood to the outside in the length direction.

[0157] Note that the central region in the length direction of the absorbent body 10 refers to a region of the central portion when the absorbent body 10 is divided into three in the length direction, and the both end regions in the length direction refer to regions located at both ends (sides) when the absorbent body 10 is divided into three in the length direction.

[0158] Likewise, in the sanitary napkin 1 of the present embodiment, it is preferable that the weight of the fiber block 100 per unit area in the central region in the width direction of the absorbent body 10 (absorbent core) be greater than the weight of the fiber block 100 per unit area in the both end regions in the width direction. In this case, moisture such as menstrual blood is more likely to remain in the central region in the width direction of the absorbent body 10 than in the both end regions in the width direction of the absorbent body 10. This makes it possible to easily suppress leakage of menstrual blood to the outside in the width direction.

[0159] Note that the central region in the width direction of the absorbent body 10 refers to a region of the central portion when the absorbent body 10 is divided into three in the width direction, and the both end regions in the width direction refer to regions located at both ends (sides) when the absorbent body 10 is divided into three in the width direction.

[0160] Furthermore, in the sanitary napkin 1 of this embodiment, the average density of the fiber block 100 (the average density of the central portion 101 and the napped portion 102) is higher than the average density of the absorbent body 10. Therefore, throughout the absorbent body 10, due to capillary action, moisture easily moves from the low-density portion to the high-density portion (fiber block 100), thereby improving the absorbency of the absorbent body 10.

[0161] Additionally, it is desirable that the maximum outer diameter of the fiber block 100 (with respect to the highly absorbent polymer particles (SAP) contained in the absorber 10) Figure 2 The maximum value of Ro in A is greater than the maximum outer diameter of the SAP before it swells and absorbs water. In absorbent 10, multiple fiber blocks 100 and SAP are mixed. When the outer diameter of the SAP before swelling is greater than the outer diameter of the fiber block 100, the outer diameter of the swollen SAP becomes even larger, making it more likely that the swollen SAP will come into contact with each other. In this case, at the points where the SAPs come into contact with each other, it is less likely that the SAP and water will come into contact. That is, the contact area between the SAP surface and water becomes smaller, potentially causing so-called "gel blockage," where water absorption is hindered, reducing the absorbency of the SAP.

[0162] In contrast, when the outer diameter of the fiber block 100 is larger than the outer diameter of the SAP before swelling, there is a higher probability that the fiber blocks 100 will be placed between two adjacent SAPs when the SAP swells, making it less likely for the SAPs to come into contact with each other. This makes it easier to suppress the occurrence of "gel blockage." This also helps to prevent a decrease in the absorbency of the SAP and improves the overall water absorption efficiency of the absorbent 10.

[0163] Furthermore, in the absorbent 10 of this embodiment, in addition to the broadleaf wood liquid-retaining fibers with short average fiber length (average fiber length less than 2 mm), it also includes liquid-retaining fibers made of materials other than broadleaf wood, whose average fiber length is longer than that of broadleaf wood fibers. Examples of liquid-retaining fibers with an average fiber length longer than that of broadleaf wood fibers include: coniferous wood liquid-retaining fibers made of coniferous wood, and rayon fibers. Thus, the mixture of short-fiber-length broadleaf wood liquid-retaining fibers and long-fiber-length liquid-retaining fibers (e.g., coniferous wood liquid-retaining fibers) makes the fibers easy to entangle, and can easily maintain the shape of the absorbent 10. Therefore, compared with the case where the absorbent is formed only of long-fiber-length liquid-retaining fibers, a highly flexible absorbent 10 can be achieved, and compared with the case where the absorbent is formed only of short-fiber-length liquid-retaining fibers, an absorbent 10 that is less likely to collapse in shape can be achieved. That is, it is possible to achieve both absorbency and flexibility of the absorbent 10.

[0164] Furthermore, the absorbent fiber, which has an average fiber length longer than that of hardwood fibers, may contain hydrophobic thermoplastic fibers. In this configuration, fibers with shorter average fiber lengths intertwine with fibers with longer average fiber lengths, making it less likely for the absorbent body 10 to collapse. In addition, the presence of hydrophobic fibers improves the diffusivity of moisture within the absorbent body 10. Therefore, moisture easily diffuses over a wide area of ​​the absorbent body 10, and is easily absorbed and retained throughout the entire absorbent body 10. Thus, the absorbency of the absorbent body 10 can be further improved.

[0165] Furthermore, in the sanitary napkin 1 of this embodiment, in the pressing portion 40 where at least the top sheet 3 and the absorbent core 10 are integrally pressed in the thickness direction, multiple thermoplastic fibers are fused together. When forming the pressing portion 40, the fusion bonding of the thermoplastic fibers enhances the integrity of the top sheet 3 and the absorbent core 10, while also making it easier to stabilize the shape of the absorbent core 10. Therefore, for example, even if the wearer moves their body significantly while wearing the sanitary napkin 1, it is easy to prevent the absorbent core 10 from collapsing or becoming less absorbent.

[0166] To explain, when thermoplastic fibers are thermally bonded together in areas other than the pressing portion 40 of the absorbent body 10, problems may arise at these thermally bonded areas, such as the absorbent body 10 hardening or becoming film-like, resulting in reduced liquid spreadability. On the other hand, the pressing portion 40 of the absorbent body 10 is adapted to the deformation of the absorbent body 10 by pressing and hardening it; therefore, the pressing portion 40 is less affected by the thermal bonding of thermoplastic fibers, hardening, or reduced liquid spreadability. Therefore, even if thermoplastic fibers are fused together in the pressing portion 40 of the sanitary napkin 1, problems are unlikely to occur.

[0167] Furthermore, it is desirable that the average fiber length of the liquid-retaining fibers of hardwood is less than the width of the pressing section 40. For example, the aforementioned linear pressing section 41 (refer to...) Figure 9 The length (width) of the water-retaining fiber in the width direction is approximately 1.0 mm to 2.0 mm, which is greater than the average fiber length of the water-retaining fiber of the hardwood (0.79 mm in this embodiment). In this configuration, the probability of the water-retaining fiber overlapping the two ends of the pressing section 40 in the width direction is low. That is, it becomes easier to prevent the water-retaining fiber from being configured to cross the two ends of the pressing section 40 in the width direction (i.e., the interface between the pressing section and the non-pressed section). When the water-retaining fiber crosses the interface between the pressing section and the non-pressed section, the interface becomes harder compared to when it does not cross. In contrast, by reducing the amount of water-retaining fiber crossing the interface between the pressing section 40 and the non-pressed section, it is possible to provide an absorbent article that reduces the perceived stiffness when the pressing section deforms and achieves a comfortable wearing experience.

[0168] Furthermore, the density of the fiber blocks 100 can have a gradient along the thickness direction of the absorbent 10. If the density of the fiber blocks 100 near the skin-side surface in the thickness direction of the absorbent 10 is higher than the density in other areas in the thickness direction, liquids such as menstrual blood can be easily absorbed from the skin-side surface. Conversely, if the density of the fiber blocks 100 near the non-skin-side surface in the thickness direction of the absorbent 10 is higher than the density in other areas in the thickness direction, liquids can be easily repelled to locations away from the wearer's skin.

[0169] <Variation Example>

[0170] In the above embodiment, the shape of the absorber 10 is described as follows: Figure 1 In the case of a cuboid shape (with a rectangular cross-section) as shown, the absorber 10 can also be deformed to have a portion protruding towards the skin side in the thickness direction. Figure 6 This is a schematic cross-sectional view showing a modified example of the absorber 10. In the modified example, the absorber 10 is located at the center in the transverse (left-right direction) direction. Figure 9 The region between the linear pressing portions 41 and 41 has a high portion 10H of the absorbent body, which is a portion that bulges towards the skin in the thickness direction relative to the base 10L of the absorbent body. An inclined portion 10S is formed between the high portion 10H and the base 10L of the absorbent body, tilting in the thickness direction. By providing such a high portion 10H of the absorbent body in the center of the absorbent body 10, the cushioning of the wearer's groin area and the absorbency of excrement can be improved when wearing the sanitary napkin 1.

[0171] Furthermore, when the absorber 10 is provided with an inclined portion 10S, it can have the following configuration: in the inclined portion 10S, a portion of the fiber block 100 (high-density portion) is crushed or the napped portion 102 is unevenly arranged. Additionally, the planar direction of the fiber block 100 ( Figure 4 The XY directions in A can be configured along the inclined surface of the inclined section 10S. Figure 4 The example shown is as follows: a portion of the fiber blocks 100 is configured such that their central portion 101 contacts the skin-side surface of the inclined portion 10S, one end of the napped portion 102 extends along the apex direction of the high portion 10H of the absorbent body, and the other end of the napped portion 102 extends along the direction of the base 10L of the absorbent body. Therefore, by configuring the napped portion 102 in this way, even when the absorbent body 10 has a high portion 10H or an inclined portion 10S, softness and absorbency can be achieved in the same way as in the above-described embodiment.

[0172] ===Other Implementation Methods===

[0173] The above describes embodiments of the present application, but the above-described embodiments are merely for facilitating understanding of the present application and are not intended to limit the explanation of the present application. In addition, the present application can be changed or modified within the scope of the gist thereof, and of course, the present application includes equivalents thereof.

[0174] In the above-described embodiments, the sanitary napkin 1 as an example of the absorbent article has a pair of the wing portions 30, but the present application is not limited thereto. That is, the wing portions 30 can not be provided.

[0175] Further, in the above-described embodiments, the absorbent body 10 is covered by two sheets of the second sheet 4 and the cover sheet 6, but the present application is not limited thereto. For example, the skin-side surface and the non-skin-side surface of the absorbent body 10 can be covered by one sheet in a manner that the skin-side surface and the non-skin-side surface are wrapped by one sheet.

[0176] In the above-described embodiments, as examples of the absorbent article, the sanitary napkin, the secretion sheet (panty liner), and the light incontinence pad are described, but the present application can be applied to an absorbent article other than these. For example, the present application can be applied to a breast pad, a feces incontinence pad, a panty-type sanitary napkin, and a belt-type or panty-type disposable diaper. That is, by providing the absorbent core including the high-density portion (fiber block and knot) and the low-density portion described in the above-described embodiments, a breast pad, a feces incontinence pad, and the like having both softness and absorbency can be realized.

[0177] <Concerning Functional Substances>

[0178] In the above-described embodiments, a functional substance can be provided in at least a part of the absorbent core. As the functional substance, for example, a warming agent, a cooling agent, a perfume, an antibacterial agent, and the like can be used.

[0179] The warming agent has a function of alleviating physiological pain and a cold feeling of the wearer, and includes a warming stimulant that makes the wearer who is stimulated feel warm by stimulating the wearer's sense of temperature. The warming stimulant is mixed with a volatile solvent (or, the warming stimulant has volatility).

[0180] The warm-sensations stimulating agent stimulates and activates TRPVl which is one of the temperature-sensitive TRP channels, including capsaicin, vanillyl butyl ether, and the like. That is, the wearer's TRPVl is activated, and the wearer is made to feel hot (the wearer generates heat in the body) via the sympathetic nervous system. From the viewpoint of the wearer's safety, the warm-sensations stimulating agent is preferably a compound of plant origin, and examples of the warm-sensations stimulating agent include: capsaicinoids, capsaicin (LD50: 47 mg / kg, molecular weight: 305), capsaicinoids (including dihydrocapsaicin, nordihydrocapsaicin, homodihydrocapsaicin, homocapsaicin, and norvanillylamine, and the like), capsanthin, nicotinyl benzyldryl ether (LD50: 2,188 mg / kg, molecular weight: 213), beta-butoxyethyl nicotinate, N-acyl vanillylamides, nonanoic acid vanillylamide, polyols, chili powder, chili tincture, chili extract, nonanoic acid vanillyl ether, vanillyl alcohol alkyl ether derivatives (e.g., vanillyl ethyl ether, vanillyl butyl ether (LD50: 4,900 mg / kg, molecular weight: 210), vanillyl pentyl ether, vanillyl hexyl ether), isovanillyl alcohol alkyl ether, ethyl vanillyl alcohol alkyl ether, veratryl alcohol derivatives, substituted benzyl alcohol derivatives, substituted benzyl alcohol alkyl ethers, vanillin propylene glycol acetal, ethyl vanillin propylene glycol acetal, ginger extract, ginger oil, gingerol (LD50: 250 mg / kg, molecular weight: 294), shogaol, hesperidin, and pyrrolidone carboxylic acid, and any combination thereof.

[0181] The solvent is not particularly limited to certain solvents as long as it contains the warm-sensations stimulating agent, and examples thereof include lipophilic solvents and hydrophilic solvents. The solvent may, for example, dissolve or disperse the warm-sensations stimulating agent, and the like. Note that in the case where the warm-sensations stimulating agent is a volatile substance, a solvent is not necessarily required, and the warm-sensations stimulating agent alone can be used. Examples of the lipophilic solvent include fats and oils such as natural oils (e.g., fatty acid esters such as glycerin triester, coconut oil, linseed oil, tri(caprylic acid / capric acid) glyceride, and the like), hydrocarbons (e.g., paraffin such as liquid paraffin), and the like. In addition, examples of the hydrophilic solvent include water and alcohols. Examples of the above-mentioned alcohols include lower alcohols such as methanol, ethanol, ethylene glycol, and glycerin, and the like; and higher alcohols such as octanol, lauryl alcohol, and myristyl alcohol, and the like.

[0182] The cooling agent has an effect of suppressing the wearer's discomfort caused by stuffiness and stickiness, and it is preferable that the cooling agent stimulate the temperature-sensitive TRP channel as with the warm-sensations stimulating agent. As the cooling agent, menthol (e.g., l-menthol) and derivatives thereof (e.g., menthyl lactate), methyl salicylate, camphor, essential oils from plants (e.g., peppermint and eucalyptus), and the like can be used.

[0183] The perfume has an action of volatilizing a scent component into the atmosphere at atmospheric pressure to make the wearer less likely to perceive an unpleasant odor of excrement. The perfume can use any of the same perfumes conventionally used in the art, and in particular, if a green herbaceous perfume (green herbaceous scent) is used, it is possible to safely and easily alleviate a mental unpleasant symptom without causing physical stimulation to the body and without oral administration. Furthermore, the perfume also provides a comfortable feeling.

[0184] The green herbaceous scent is a scent note including a green scent (green note) or a herbaceous scent (herbaceous note). The green scent refers to a fresh scent of grass and seedlings. The herbaceous scent (herbaceous note) refers to a scent note of natural herbs using herbaceous plants. The perfume composition including a perfume having a green herbaceous scent preferably includes one or more perfumes selected from the group consisting of cis-3-hexenol, formic acid cis-3-hexenyl ester, acetic acid cis-3-hexenyl ester, propionic acid cis-3-hexenyl ester, butyric acid cis-3-hexenyl ester, trans-2-hexenal, trans-2-hexenyl acetate, hexyl acetate, styrallyl acetate, 2-methyl-3-(3,4-methylenedioxyphenyl)-propanal (IFF, Inc., product name: heliotropin), 3(4)-(5-ethylbicyclo[2,2,1]heptyl-2)-cyclohexanol, 2-pentyloxyallylglycolate (IFF, Inc., product name: allyl amyl glycolate), 4-methyl-3-decen-5-ol (Givaudan, product name: methyl decenol), hexanal, 2,4-dimethyl-3-cyclohexenyl carboxaldehyde (IFF, Inc., product name: muguet aldehyde), and phenylacetaldehyde. Commercially available products can also be used as such a perfume. Such a perfume mainly produces a green scent. The perfume composition including a perfume having a green herbaceous scent preferably further includes one or more perfumes selected from the group consisting of l-menthol, 1,8-cineol, methyl salicylate, citronellal, camphor, borneol, isobornyl acetate, terpinyl acetate, eugenol, anethole, 4-methoxybenzyl alcohol, and estragol. Such a perfume mainly produces a herbaceous scent.

[0185] The antibacterial agent has an action of inhibiting growth of bacteria in the body fluid or the like absorbed by the absorbent article to make it less likely to generate an odor due to putrefaction or the like. The antibacterial agent can be any of the same antibacterial agents conventionally used in the art. Examples of the cationic antibacterial agent include: quaternary ammonium salts, guanidium-based antibacterial agents (e.g., chlorhexidine gluconate, or chlorhexidine hydrochloride), biguanide-based antibacterial agents, metal ion carriers, hexetidine, and metronidazole, and the like, with quaternary ammonium salts being preferred.

[0186] The quaternary ammonium salt is not particularly limited as long as it is a substance having a quaternary ammonium salt structure in the molecule, and examples of the quaternary ammonium salt include: alkyltrimethylammonium salts, polyoxyethylene alkylmethylammonium salts, alkylbenzyldimethylammonium salts, alkylpyridinium salts, and the like. Examples of the quaternary ammonium salt include the following compounds represented by the following formulas (1) to (4).

[0187] [R(CH3)3N + ]lX Formula (1)

[0188] [R(CH3)N + (CH2CH2O) m H[(CH2CH2O) n H]]lX Formula (2)

[0189] [R(CH3)2N + CH2C6H5]lX Formula (3)

[0190] [RPy + ]lX Formula (4)

[0191] (In the formulas, R each independently represents an alkyl group, X each independently represents a monovalent or divalent anion. l each independently represents an integer of 1 or 2, m and n each independently represent an integer of 2 to 40, and Py represents a pyridine ring.)

[0192] In addition, examples of the biguanide-based antibacterial agent include polyaminopropyl biguanide and salts thereof such as hydrochloride, stearate, phosphate, and the like, chlorhexidine gluconate, chlorhexidine hydrochloride, polyhexamethylene guanidine hydrochloride, polyhexamethylene guanidine phosphate, polyhexamethylene biguanide hydrochloride, polyhexamethylene biguanide isostearate, poly[oxyethylene(dimethylimino)ethylene(dimethylimino)dichloroethane], and any combination thereof. As the metal ion carrier, a substance that can release metal ions, such as a metal salt, can be used. Examples of the metal ion include silver ion, zinc ion, aluminum ion, cobalt ion, zirconium ion, cerium ion, iron ion, copper ion, nickel ion, platinum ion, and the like, with silver ion being preferred. Examples of the metal salt include nitrate salts such as silver nitrate, aluminum nitrate, cobalt nitrate, zirconium nitrate, cerium nitrate, iron nitrate, copper nitrate, nickel nitrate; acetate salts such as silver acetate; hydrochloride salts such as cerium chloride, iron chloride, zinc chloride, copper chloride; sulfate salts such as silver sulfate, aluminum sulfate, copper sulfate, zinc sulfate, and the like.

[0193] By providing such a functional substance in an absorbent core having a high-density portion (fiber mass or knot) and a low-density portion, the functional substance is more likely to be retained in the high-density portion, making it possible to more effectively exert the effect of the functional substance in the absorbent article. For example, by retaining an antibacterial agent in the high-density portion (fiber mass or knot) of the absorbent core, it is more likely to exert an antibacterial effect in the portion where urine or menstrual blood is accumulated. In addition, by retaining and accumulating a perfume, a cooling agent, a warming agent, and the like in the high-density portion (fiber mass or knot), it is possible to easily make the effect of these functional substances last for a long time.

[0194] Relationship between the proportion of high-density portions and water absorption

[0195] The relationship between the proportion of high-density portions (proportion of high-density portions) contained in the absorbent and the water absorption of the absorbent is described. Specifically, four kinds of samples (absorbents) having different proportions of high-density portions (knots) are prepared, and an experiment to measure the water absorption rate is performed for each sample, and the water absorption is verified from the results.

[0196] First, based on the method described in Figure 4 A and Figure 4 B, four kinds of absorbents (absorbent cores) are manufactured as samples. When manufacturing each absorbent, first, as shown in Example 1 A, a pulper is used to pulverize the pulp sheet (pulper roll). At this time, by adjusting the rotation speed of the pulper, the amount of pulp to be pulverized per unit time is changed so that the proportion of high-density portions (knots) contained in the pulverized pulp can be increased or decreased. In this experiment, the pulp pulverized by the pulper at a processing amount of 120 kg / h is used as Example 1, the pulp pulverized at a processing amount of 240 kg / h is used as Example 2, and the pulp pulverized at a processing amount of 360 kg / h is used as Example 3. In addition, the pulp pulverized at a processing amount of 60 kg / h is used as Comparative Example. Then, the four kinds of pulverized pulp are processed as in Example 2 B, and absorbents are formed, respectively. Each absorbent has the same shape and has a predetermined area (for example, 200 mm in the length direction x 70 mm in the width direction), a basis weight of 300 g / m 2 , and a thickness of 2.0 mm.

[0197] Next, for the four kinds of samples, the proportion of high-density portions (knots) (i.e., the proportion of the weight of high-density portions contained in the total weight of the absorbent) is measured. The proportion of high-density portions can be measured by a shaking sieve machine (for example, a shaking sieve machine SS-HK60 manufactured by Azone Corporation) according to the test method specified in JIS K 0069, as follows.

[0198] First, the total weight of each of the four samples (absorbent of Examples 1 to 3 and Comparative Example) was measured using an electronic balance or the like and recorded. Next, the sample of Example 1 was placed on a 14-mesh sieve provided on a shaking sieve machine. In addition, a cylinder having the same diameter as the sieve was installed below the sieve, and a suction device (e.g., Wonder-Gun W101 manufactured by Osawa & Company, minimum suction inner diameter: 22 mm, pressure: 0.5 MPa) was installed in a hole formed in the side of the cylinder at a height of 70 mm below the sieve in such a manner that no gap was produced. Furthermore, an air jet device (e.g., air jet gun AG-101 manufactured by TONE, nozzle length: 95 mm, nozzle inner diameter: 4 mm, pressure: 0.5 MPa) was installed at a height of 50 mm above the sieve. Note that, as the sieve wire installed on the sieve, a standard sieve wire specified in JIS Z 8801 was used. For example, the 14-mesh sieve is a sieve wire having a mesh of 1.18 mm, a wire diameter of 0.63 mm, and an open area of 42.3%.

[0199] Next, while the air jet device was uniformly jetting air and the suction device was sucking air under conditions of an amplitude of 70 mm and 60 times / minute, the fibers were separated from the absorbent. Then, the fibers remaining on the sieve (14-mesh) after 15 minutes were regarded as "Knots" (corresponding to the high-density portion (fiber lump 100) described above), and the weight of the Knots was measured and recorded. Next, the fibers that had passed through the 14-mesh sieve were collected and placed on a 60-mesh sieve, and the fibers were again separated under the same conditions. Then, the fibers remaining on the sieve (60-mesh) after 15 minutes were determined to be "Accept", and the weight was measured and recorded. In addition, the fibers that had passed through the sieve (60-mesh) were determined to be "Fine", and the weight of "Fine" was recorded as a value obtained by subtracting the weights of "Knots" and "Accept" from the total weight of the sample (absorbent) of Example 1. Then, when each of the measured weights was divided by the total weight of each sample (absorbent), the content rates (wt%) of "Knots", "Accept", and "Fine" in the sample were obtained.

[0200] This operation was performed on each of the four samples (Examples 1 to 3 and Comparative Example), and the content rates of "Knots", "Accept", and "Fine" were calculated for each sample. Note that, for a commercially available absorbent article, the content rates of "Knots" (high-density portion), "Accept", and "Fine" can be measured in the same manner. In this case, the sheets (top sheet 3, second sheet 4, cover sheet 6, and the like) stacked above and below the absorbent in the state of the product were peeled off, and then the fibers were separated in accordance with the above-described method to perform the measurement. In addition, in the case where the size of the absorbent is large, the measurement can be performed in multiple stages.

[0201] The content of "Knots" (high density portions) and the like was measured for each of the four samples, and then the water absorbency of the sample was measured. First, a surface sheet (corresponding to the topsheet 3 described above, for example, the surface sheet of Sofy SPORTS manufactured by Uni-Charm Corporation, etc.) was placed on the upper surface (one side surface in the thickness direction) of each sample, and a perforated acrylic plate (for example, an acrylic plate of 200 mm (length) x 100 mm (width) having a hole of 40 mm x 10 mm in the center) was overlaid thereon. Then, using an automatic burette (for example, Multidosimat E725-1 manufactured by Shibata Kagaku Kiki K.K.), 2 ml of artificial menstrual blood was injected into the hole of the acrylic plate at 90 ml / minute. As the "artificial menstrual blood", artificial menstrual blood obtained by adding glycerin 80 g, sodium carboxymethylcellulose 8 g, sodium chloride 10 g, sodium bicarbonate 4 g, Red No. 102 8 g, Red No. 2 2 g, and Yellow No. 5 2 g to 1 L of ion exchange water and thoroughly stirring the components was used. Then, the time from the start of the injection of the artificial menstrual blood until the artificial menstrual blood disappeared from the surface sheet (discharge time) was measured. Since the more easily the absorbent absorbs moisture, the shorter the discharge time, the water absorbency of the absorbent can be evaluated from the length of the measured discharge time.

[0202] The relationship between the content of "Knots", "Accept", and "Fine" measured for each sample and the discharge time is shown in Table 1. According to Table 1, it was confirmed that the higher the content of "Knots" (high density portions) in the absorbent, the shorter the discharge time. In general, it is known that when the absorption speed for body fluid (i.e., the discharge time) is 10 seconds or less when wearing a sanitary napkin, the wearer is likely to feel comfortable, and when the absorption speed for body fluid exceeds 20 seconds, the wearer is likely to feel uncomfortable. In Examples 2 and 3, the discharge time was shorter than 10 seconds, the evaluation of the water absorbency was "excellent", and the absorbent was suitable as a sanitary napkin. In addition, in Example 1, since the discharge time was shorter than 20 seconds, the absorbent can also be used as a sanitary napkin. On the other hand, in the comparative examples, the discharge time was 20 seconds or more, and the evaluation of the water absorbency of the absorbent was "poor".

[0203] [Table 1]

[0204] Example 3 Comparative Example Content rate (%) of Knots Content rate (%) of Accept Content rate (%) of Fine 13.5 28.0 37.4 7.5 Discharge time (sec) 75.3 59.7 50.2 79.5 Water absorption evaluation 11.2 12.3 12.4 13.0 Good 12 8 6 20 Good Good Poor Poor ​

[0205] Therefore, it was found that in Examples 1 to 3 in which the content of Knots was higher than the content of Fine in the absorbent body, the evaluation of water absorbency was good (excellent or acceptable). It is considered that this is because, as compared with the case of Fine in which the fiber is so fine as to pass through a 60-mesh sieve, the higher the content of Knots in which fibers are aggregated, the more easily voids are generated inside the absorbent body, and thus moisture such as body fluid more easily passes through the absorbent body, thereby realizing an absorbent body excellent in permeability. Furthermore, since Knots (high-density portions) themselves easily hold liquid as described above, the higher the content of Knots, the more excellent the absorbent body in water retention can be formed.

[0206] Therefore, it is desirable that the content of Knots contained in the absorbent body is higher than the content of Fine. In other words, it is desirable that, when fibers of the absorbent body (absorbent core) are separated using a sieve shaker in accordance with the regulation of JIS K 0069, the value obtained by dividing the weight of fibers (Knots) remaining on a 14-mesh sieve by the weight of the absorbent body is greater than the value obtained by dividing the weight of fibers (Fine) passing through a 60-mesh sieve by the weight of the absorbent body. The content of Knots (high-density portions) in the absorbent body is set to such a relationship that the water absorbency of the absorbent body (absorbent core) can be further improved.

[0207] BRIEF DESCRIPTION OF DRAWINGS

[0208] 1 sanitary napkin (absorbent article),

[0209] 2 side sheet, 3 top sheet, 4 second sheet,

[0210] 5 back sheet, 6 cover sheet,

[0211] 10 absorbent body (absorbent core),

[0212] 10H high portion in absorbent body, 10L base portion in absorbent body, 10S inclined portion,

[0213] 20 sanitary napkin main body portion,

[0214] 30 wing portion,

[0215] 40 press portion, 41 linear press portion, 45 high press portion, 46 low press portion,

[0216] 61 conveyance mechanism, 62 sawdust machine,

[0217] 70 roller, 71 recessed portion, 72 suction portion,

[0218] 80 material supply portion, 80a protective cover,

[0219] 81 particle supply portion,

[0220] 100 fiber block (high density portion)

[0221] 101 central portion, 102 napping portion,

[0222] PS sheet

Claims

1. An absorbent article having a length direction, a width direction, and a thickness direction orthogonal to each other, the absorbent article including an absorbent core having comminuted liquid-retentive fibers, the liquid-retentive fibers having broadleaf wood liquid-retentive fibers made of broadleaf wood, the absorbent core having a plurality of high-density portions and low-density portions, the high-density portions being portions in which the liquid-retentive fibers are concentrated, the high-density portions being fiber blocks in which the broadleaf wood liquid-retentive fibers are concentrated in a form of a hairball, the low-density portions being portions in which the liquid-retentive fibers have a lower density than the high-density portions, the low-density portions being located on one side in the thickness direction or the other side in the thickness direction of at least one of the high-density portions, the high-density portions having a central portion and a hair-raising portion outside the central portion, the central portion being a portion in which the liquid-retentive fibers are concentrated and not entangled with fibers of the low-density portions, the hair-raising portion being a portion entangled with fibers of the low-density portions, the high-density portions having a planar shape, with respect to a maximum width of an area occupied by the hair-raising portion in a planar direction of the high-density portion, with respect to a maximum width of an area occupied by the hair-raising portion in a direction orthogonal to the planar direction, the maximum width of the former being longer than the maximum width of the latter; and of the plurality of high-density portions included in the absorbent core, with respect to the high-density portions arranged such that the direction orthogonal to the planar direction coincides with the thickness direction of the absorbent core, with respect to the high-density portions arranged such that the direction orthogonal to the planar direction coincides with the length direction or the width direction of the absorbent core, the proportion of the high-density portions of the former being greater than the proportion of the high-density portions of the latter.

2. The absorbent article according to claim 1, wherein the average density of the high-density portions is higher than the average density of the absorbent core, and the weight of the fibers included in the central portion is greater than the weight of the fibers included in the hair-raising portion.

3. The absorbent article according to claim 1, wherein the average density of the high-density portions is higher than the average density of the absorbent core, and the weight of the fibers included in the central portion is less than or equal to the weight of the fibers included in the hair-raising portion.

4. The absorbent article according to claim 2, wherein in the planar direction of the high-density portion, a diameter of a circle circumscribing the central portion is set as Rc, a diameter of a circle circumscribing the hair-raising portion is set as Ro, (Ro - Rc) < Rc is satisfied.

5. The absorbent article according to claim 2, wherein in the planar direction of the high-density portion, a diameter of a circle circumscribing the central portion is set as Rc, a diameter of a circle circumscribing the hair-raising portion is set as Ro, (Ro - Rc) ≥ Rc is satisfied.

6. The absorbent article according to claim 1, wherein at least a portion of the high-density portions is in contact with a sheet member adjacent to a skin side of the absorbent core in the thickness direction.

7. The absorbent article according to claim 1, wherein at least a portion of the high-density portions is in contact with a sheet member adjacent to a non-skin side of the absorbent core in the thickness direction.

8. The absorbent article according to claim 1, wherein at least a portion of the high-density portion is in contact with both of: a sheet member adjacent to the skin side of the absorbent core in the thickness direction, and a sheet member adjacent to the non-skin side of the absorbent core in the thickness direction.

9. The absorbent article according to claim 1, wherein the absorbent article further comprises: a topsheet disposed on the skin side with respect to the thickness direction of the absorbent core, and a press portion integrally pressing the topsheet and the absorbent core in the thickness direction; the press portion and the high-density portion are in contact with each other in the thickness direction.

10. The absorbent article according to claim 9, wherein the press portion comprises: a low press portion, and a high press portion in which the absorbent core is pressed to have a higher density than the low press portion, the low press portion and the high-density portion are in contact with each other in the thickness direction.

11. The absorbent article according to claim 1, wherein when the absorbent core is divided into three in the length direction, i.e., into a length direction central region and length direction end regions, a weight of the high-density portion contained per unit area of the length direction central region is greater than a weight of the high-density portion contained per unit area of the length direction end regions.

12. The absorbent article according to claim 1, wherein when the absorbent core is divided into three in the width direction, i.e., into a width direction central region and width direction end regions, a weight of the high-density portion contained per unit area of the width direction central region is greater than a weight of the high-density portion contained per unit area of the width direction end regions.

13. The absorbent article according to claim 1, wherein the absorbent core contains a superabsorbent polymer, and a maximum outer diameter of the high-density portion is greater than a maximum outer diameter of the superabsorbent polymer.

14. The absorbent article according to claim 1, wherein an average fiber length of the hardwood liquid-retaining fiber is less than 2 mm, and the absorbent core contains a liquid-retaining fiber formed of a material other than hardwood, and an average fiber length thereof is longer than the average fiber length of the hardwood liquid-retaining fiber.

15. The absorbent article according to claim 14, wherein an average fiber length of the hardwood liquid-retaining fiber is less than 2 mm, and the absorbent core contains a hydrophobic thermoplastic fiber having an average fiber length longer than the average fiber length of the hardwood liquid-retaining fiber.

16. The absorbent article according to claim 1, wherein an average fiber width of the hardwood liquid-retaining fiber is 15 μm or less, The number of the broad-leaved wood liquid-retaining fibers contained in the absorbent core per unit area is 300 fibers / mm 2 above and less than 2500 fibers / mm 2 , and a superabsorbent polymer is present between a plurality of the hardwood liquid-retaining fibers.

17. The absorbent article according to claim 1, wherein a standard deviation of fiber lengths of the hardwood liquid-retaining fiber is 0.27 or less, and a standard deviation of fiber widths of the hardwood liquid-retaining fiber is 7.55 or less.

18. The absorbent article according to claim 17, wherein a value obtained by subtracting the standard deviation of the fiber length of the hardwood fiber retaining fiber from the average fiber length of the hardwood fiber retaining fiber, the value is less than 2 times the average fiber length of the hardwood fiber retaining fiber; and a value obtained by subtracting the standard deviation of the fiber length of the hardwood fiber retaining fiber from the average fiber length of the hardwood fiber retaining fiber, the value is greater than 1 / 2 the average fiber length of the hardwood fiber retaining fiber.

19. The absorbent article according to claim 1, wherein the absorbent core contains a plurality of thermoplastic fibers, the absorbent core has a press portion that integrally presses the absorbent core in the thickness direction, and in the press portion, the thermoplastic fibers are fusion-bonded to each other.

20. The absorbent article according to claim 1, wherein the absorbent article is at least any one of a sanitary napkin for use in the physiological period, a sheet for use in the secretion, and a light incontinence pad.

21. The absorbent article according to claim 1, wherein a pair of wings extending from a central region in the length direction to the outside in the width direction is provided.

22. The absorbent article according to claim 1, wherein an adhesive portion is provided on a non-skin side surface of the absorbent article, the adhesive portion is a portion for sticking the absorbent article to an undergarment of a wearer when the absorbent article is worn.

23. The absorbent article according to claim 1, wherein a functional substance is provided in at least a part of the absorbent core.

24. The absorbent article according to claim 1, wherein when fibers contained in the absorbent core are separated using a shaking sieve machine according to the stipulation of JIS K 0069, a value obtained by dividing the weight of fibers remaining in a 14-mesh sieve of the shaking sieve machine by the weight of the absorbent core before the separation is greater than a value obtained by dividing the weight of fibers passing through a 60-mesh sieve of the shaking sieve machine by the weight of the absorbent core before the separation.

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