Absorbent article

Abstract

An absorbent article of the present application is provided with a nonwoven fabric intermediate sheet (30) disposed between a liquid-permeable front sheet (10) and an absorbent body (40) in abutment with the non-skin-contacting surface side of the front sheet (10), the front sheet (10) including an upper layer (11) disposed on the skin-contacting surface side and a lower layer (12) disposed on the non-skin-contacting surface side, the upper layer containing a plurality of fibers having different contact angles with water from each other, the contact angle with water of the fibers constituting the upper layer being greater than the contact angle with water of the fibers constituting the lower layer, the intermediate sheet (30) having an embossed portion, the area ratio of the embossed portion (15, 31) of the intermediate sheet (30) being greater than that of the front sheet (10), and the contact angle with water of the fibers constituting the intermediate sheet (30) being greater than the contact angle with water of the fibers constituting the front sheet (10).

Description

Technical Field

[0001] This invention relates to absorbent articles. Background Technology

[0002] For absorbent products such as menstrual pads, incontinence pads, and sanitary pads that are used to absorb fluids excreted from the body, the front side that forms the skin-contacting surface should be designed to prevent liquid residue from remaining on the surface, from the perspective of inhibiting adhesion.

[0003] As a front sheet that is not prone to liquid residue on the surface, a front sheet made of nonwoven fabric with an upper and lower two-layer structure is known.

[0004] For example, Patent Document 1 discloses a nonwoven fabric for absorbent articles having a first fiber layer facing the skin and a second fiber layer adjacent to the first fiber layer as the front sheet of the absorbent article.

[0005] Furthermore, a nonwoven fabric intermediate sheet is disposed below and adjacent to the front sheet; this nonwoven fabric intermediate sheet is also called a secondary layer or second sheet. This intermediate sheet is disposed to improve the diffusion of liquid in the planar direction, etc.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2019-063414 Summary of the Invention

[0009] The present invention relates to an absorbent article comprising a liquid-permeable front sheet, a back sheet, and an absorbent body located between the front sheet and the back sheet, and having a length direction corresponding to the wearer's front-back direction and a width direction orthogonal to the length direction.

[0010] The front sheet preferably comprises an upper layer disposed on the skin-contact side and a lower layer disposed on the non-skin-contact side. The upper layer preferably comprises a variety of fibers with different contact angles with water. Preferably, the contact angle between the fibers constituting the upper layer and water is greater than that between the fibers constituting the lower layer and water. Preferably, a non-woven fabric intermediate sheet is disposed adjacent to the front sheet between the front sheet and the absorbent. The intermediate sheet preferably has embossed portions, and the ratio of the total area of ​​the embossed portions to the sheet area (i.e., the area ratio of the embossed portions) of the intermediate sheet is larger than that of the front sheet. The contact angle between the fibers constituting the intermediate sheet and water is preferably greater than that between the fibers constituting the front sheet and water. Attached Figure Description

[0011] Figure 1 This is a cross-sectional schematic diagram of an example of a front sheet of an absorbent article that can be used in this invention.

[0012] Figure 2 This is a plan view showing an example of the front side of an absorbent article that can be used in this invention, viewed from the side that contacts the skin.

[0013] Figure 3 This is a schematic diagram illustrating a method for manufacturing an example of the front sheet of an absorbent article that can be used in this invention.

[0014] Figure 4 This is a cross-sectional schematic diagram along the width direction of the portion opposite the excretion portion, according to one embodiment of the absorbent article of the present invention.

[0015] Figure 5 (a) and Figure 5 Figure (b) is an example of an intermediate sheet of an absorbent article that can be used in the present invention. Figure 5 (a) is a planar schematic diagram. Figure 5 (b) is a schematic diagram of section III-III of (a). Detailed Implementation

[0016] In a two-layer front sheet, a hydrophilicity gradient is created between the upper and lower layers, making the lower fiber layer more hydrophilic than the upper fiber layer. This promotes liquid transfer to the lower layer and prevents liquid from remaining on the upper layer of the front sheet. Furthermore, to prevent the surface of the front sheet from becoming sticky, it is desirable to allow liquid to transfer rapidly not only from the upper layer of the front sheet but also from the entire front sheet to the absorbent.

[0017] The present invention provides an absorbent article that prevents liquid from remaining on the front sheet and allows the liquid to be quickly transferred from the front sheet to the absorbent.

[0018] Hereinafter, the present invention will be described based on its preferred embodiments with reference to the accompanying drawings.

[0019] The absorbent article of the present invention is generally elongated in shape, having a length direction corresponding to a direction extending from the wearer's abdomen, through the crotch, towards the back, and a width direction orthogonal to this length direction. This length direction corresponds to the wearer's front-to-back direction.

[0020] The absorbent article has a crotch portion disposed in the crotch area of ​​the wearer, and a front portion and a rear portion extending therefore and backward. The crotch portion has an excretory portion relative area, which includes an excretory portion relative portion disposed opposite to the wearer's vaginal opening or other excretory portions when the absorbent article is worn, for example located at the center of the absorbent article in the length direction and at the center of the absorbent article in the width direction and in the vicinity thereof.

[0021] Absorbent articles typically include a front sheet on the skin-contacting side of the wearer, a back sheet on the non-skin-contacting side, and an absorbent material disposed between the front and back sheets. The front sheet can be one or more liquid-permeable sheets, such as nonwoven fabric or perforated membranes. The skin-contacting side of the front sheet can be irregularly shaped. For example, multiple protrusions can be formed in a scattered pattern on the skin-contacting side of the front sheet. Alternatively, ridges and grooves extending in one direction can be alternately formed on the skin-contacting side of the front sheet. For this purpose, a multilayer sheet formed by laminating two or more sheets of nonwoven fabric in a peelable or non-peelable manner can also be used to form the front sheet. When the front sheet is irregularly shaped or ridged, the protrusions or ridges can be solid or hollow.

[0022] On the other hand, as the back sheet, materials such as membranes with liquid impermeability or liquid non-permeability, spunbond-meltblown-spunbond nonwoven fabrics, etc., can be used. Multiple micropores can be formed in the liquid impermeability or liquid non-permeability membrane to give the membrane water vapor permeability. For purposes such as further improving the skin feel of absorbent items, a high-quality sheet such as a nonwoven fabric may be laminated on the outer surface of the back sheet.

[0023] The absorbent body includes an absorbent core. The absorbent core may include, for example, a composite of hydrophilic fibers such as cellulose (e.g., pulp), a composite of the hydrophilic fibers and an absorbent polymer, an accumulation of absorbent polymer, or a laminated structure in which an absorbent polymer is carried between two absorbent sheets. Regarding the absorbent core, at least its skin-contact surface can be covered by a liquid-permeable coating chip, or the entire surface including both the skin-contact and non-skin-contact surfaces can be covered by the coating chip. As the coating chip, materials such as sheet paper containing hydrophilic fibers or liquid-permeable nonwoven fabric can be used.

[0024] In this instruction manual, "skin-contact side" refers to the side of an absorbent article or its constituent parts (such as absorbent cores) that faces the wearer's skin when the absorbent article is worn, i.e., the side relatively closer to the wearer's skin. "Non-skin-contact side" refers to the opposite side of the absorbent article or its constituent parts that faces the skin when the absorbent article is worn, i.e., the side relatively farther from the wearer's skin. Furthermore, "when wearing" as used here refers to maintaining the usual proper wearing position, i.e., the correct wearing position of the absorbent article.

[0025] In addition to the aforementioned front panel, back panel, and absorbent core, depending on the specific application of the absorbent article, leak-proof flaps extending along the length direction are sometimes provided on both sides of the skin-contact side. The leak-proof flaps typically include a base end and a free end. The leak-proof flaps have a base end on the skin-contact side of the absorbent article and stand upright from the skin-contact side. The leak-proof flaps are made of a liquid-repellent or water-repellent material that is breathable. An elastic member, such as a rubber thread, can be arranged in an extended state at or near the free end of the leak-proof flap. By contracting this elastic member when the absorbent article is worn, the leak-proof flap stands upright towards the wearer's body, effectively preventing liquid excreted onto the front panel from flowing across the front panel and leaking outwards in the width direction of the absorbent article. Furthermore, the absorbent article may have an adhesive layer on the non-skin-contact surface. The adhesive layer is used to secure the absorbent article to underwear or other absorbent articles when worn.

[0026] Reference Figure 1 and Figure 2 A preferred example of the front sheet of the absorbent article used in the present invention will be described.

[0027] Figure 1 and Figure 2 The front panel 10 shown is a two-layer structure with liquid permeability, comprising an upper layer 11 and a lower layer 12. In the front panel 10, the upper layer 11 is disposed on the side that contacts the wearer's skin, i.e., the skin-contact side, and the lower layer 12 is disposed on the opposite side of the skin-contact side, i.e., the non-skin-contact side. The lower layer 12 is configured to abut against the intermediate panel 30 adjacent to the non-skin-contact side of the front panel 10 (see reference). Figure 4 ).

[0028] like Figure 1 As shown, the front panel 10 has an upper layer 11 and a lower layer 12 divided by a boundary surface F. The upper layer 11 and lower layer 12 shown in the figure have a fixed portion 15 that joins the two layers 11 and 12 together, and a non-fixed portion 16 that is not joined to the upper layer 11 and lower layer 12 by the fixed portion 15. The non-fixed portion 16 contains the boundary surface F between the upper layer 11 and lower layer 12, but the fixed portion 15 does not contain the boundary surface F. In this embodiment, the fixed portion 15 is formed by laminating a fiber assembly constituting the upper layer 11 and a fiber assembly constituting the lower layer to form a laminate, and then performing an embossing process on the laminate. The fixed portion 15 is an embossed portion for the front panel 10.

[0029] like Figure 1As shown, when a fixing portion 15 is formed to join the upper layer 11 and the lower layer 12 together, the skin-contact side of the upper layer 11 in the front sheet 10 has a concave-convex shape. In the fixing portion 15 of the front sheet 10, both the upper layer 11 and the lower layer 12 have recesses 17. The recesses 17 on the skin-contact side of the upper layer 11 form protrusions 18 relative to each other. As described below, the protrusions 18 exist in the area surrounded by the fixing portion 15 that constitutes the recesses 17.

[0030] like Figure 2 As shown, in the front panel 10, the fixing part 15 preferably has a first fixing part row L1 and a second fixing part row L2 that are inclined to each other relative to the X direction and are composed of the fixing part 15. Figure 2 The first fixed connection row L1 and the second fixed connection row L2 shown are formed in a parallel manner, and each has a portion with a wider interval and a portion with a narrower interval between adjacent fixed connection rows. Figure 2 The fastening portions 15 that constitute the first fastening portion row L1 and the second fastening portion row L2 shown are discontinuous lines. The X direction is preferably aligned with the length or width direction of the absorbent article. The X direction may also be a direction inclined relative to both the length and width directions of the absorbent article.

[0031] In the first and second fixing rows L1, where fixing portions 15 are formed, multiple groove-shaped recesses 17 are formed extending along each fixing row. Within the area surrounded by the fixing portions 15, three types of protrusions 18a, 18b, and 18c, each with a different area, are formed protruding towards the skin-contacting surface. The heights of the protrusions 18a, 18b, and 18c can be different or the same. The first protrusion 18a and the third protrusion 18c shown in the figure are both rhomboid in shape, with the first protrusion 18a having a larger top view area compared to the third protrusion 18c. The second protrusion 18b is parallelogram-shaped when viewed from above, having a top view area between the first protrusion 18a and the third protrusion 18c. All fixing portions 15 are recesses 17, which are thinner than the other protrusions 18a, 18b, and 18c. Figure 2 In the front panel 10 shown, protrusions 18a, 18b, and 18c with different top-view areas are formed within the divided sections of different areas surrounded by the fixed portion 15. This prevents bodily fluids excreted onto the front panel 10 from spreading in one direction, which is therefore preferable. Furthermore, Figure 2 In the front panel 10 shown, the area surrounded by the fixing portion 15 has a diamond-shaped division with the largest top view area, which is surrounded by two divisions of different sizes with a smaller top view area. Therefore, the wearable part includes... Figure 2When the front panel 10 is used as an absorbent article, even if the first protrusion 18a in the largest division area is flattened by the wearer's skin, the second and third protrusions 18b and 18c in the smaller division area around it remain and limit the diffusion of bodily fluids, which is therefore more preferable.

[0032] The upper layer 11 of the front panel 10 is composed of a fiber assembly containing heat-stretchable fibers. The upper layer 11 may consist solely of heat-stretchable fibers, or it may contain a second fiber different from the heat-stretchable fibers. Details of the second fiber will be described later.

[0033] Examples of heat-stretchable fibers include fibers that elongate by changing the crystallization state of the resin through heating, or fibers whose apparent length increases after the curling is released following a curling process. By including heat-stretchable fibers in the upper layer 11, the upper layer 11 and the front sheet 10 become fluffy and three-dimensional due to the elongation of the heat-stretchable fibers, thus presenting a good appearance.

[0034] Preferred heat-stretchable fibers include composite fibers comprising a first resin component and a second resin component having a melting point or softening point lower than that of the first resin component, wherein the second resin component is continuously present on a portion or throughout the fiber surface. Furthermore, fibers that thermally fuse with other fibers during heat stretching are preferred. The first resin component in the heat-stretchable fiber typically exhibits the fiber's heat stretchability, while the second resin component typically exhibits thermal fusion properties. The fiber is configured to stretch by applying a temperature lower than the melting point of the first resin component to the fiber containing such components.

[0035] As such a heat-stretchable fiber, for example, the fibers described in Japanese Patent Application Publication No. 2004-218183, Japanese Patent Application Publication No. 2005-350836, Japanese Patent Application Publication No. 2007-303035, Japanese Patent Application Publication No. 2007-204899, Japanese Patent Application Publication No. 2007-204901 and Japanese Patent Application Publication No. 2007-204902, or Japanese Patent Application Publication No. 2008-101285 can be used.

[0036] Specifically, the first resin component can include polyolefin resins such as polypropylene (PP) (excluding polyethylene resin), polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), etc. They can be used alone or in combination of two or more.

[0037] Furthermore, as a second resin component, examples include high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE). These can be used alone or in combination of two or more. In addition to polyethylene resin, other resins such as PP, ethylene-vinyl acetate copolymer (EVA), and ethylene-vinyl alcohol copolymer (EVOH) can also be used. From the viewpoint of obtaining a fluffy, textured, and strong front sheet by forming thermally bonded joints between fibers, it is preferable to use only polyethylene resin as the second resin component.

[0038] In terms of easily obtaining heat-elongated fibers endowed with heat-welding properties, it is preferable to use PP or PET as the first resin component and HDPE as the second resin component when combining the first and second resin components.

[0039] The melting points of resin components 1 and 2 were measured using a differential scanning calorimeter (DSC6200, manufactured by Seiko Instruments Co., Ltd.). A finely chopped fiber sample (2 mg sample mass) was thermally analyzed at a heating rate of 10 °C / min, and the peak melting temperature of each resin was measured. The melting point was defined by its peak melting temperature. When the melting point of a resin component could not be clearly measured using this method, the resin was defined as a "resin without a melting point." In this case, the softening point was defined as the temperature at which the resins were fused together to a point where the weld strength of the fibers could be measured, and this temperature was used as the temperature at which the molecules of the resin component began to flow.

[0040] In a preferred embodiment comprising a first resin component and a second resin component, the thermal elongation of the thermally elongated fiber at a temperature 10°C higher than the melting point or softening point of the second resin component is preferably 0.5% or more, more preferably 3% or more, more preferably 5% or more, and preferably 20% or less.

[0041] The thermal elongation of fibers can be measured, for example, using the following method. A Seiko Instruments TMA / SS6000 thermomechanical analyzer was used as the measuring device. Multiple fibers with a length of 10 mm or more were collected as samples, with a total mass of 0.5 mg per 10 mm of fiber length. These fibers were arranged in parallel, and both ends were mounted on the clamps of the apparatus in a manner that prevented the fibers from loosening. The distance between the clamps was set to 10 mm. The measurement start temperature was set to 25°C, and a fixed load of 0.73 mN / dtex was applied along the fiber length direction. Under this condition, the fibers were heated at a rate of 5°C / min. The elongation of the fibers at this point was measured, specifically the elongation C (mm) at a temperature 10°C higher than the melting or softening point of the second resin component. The elongation C (mm) can be calculated by subtracting the fiber length before measurement from the measured fiber length.

[0042] The thermal elongation (%) of the fiber is calculated based on "(C [mm] / distance between clamps [mm]) × 100".

[0043] Figure it out.

[0044] The lower layer 12 of the front sheet 10 comprises a fiber assembly that does not contain the aforementioned heat-stretchable fibers, or contains heat-stretchable fibers at a lower mass ratio than the upper layer 11. In detail, the lower layer 12 is composed only of fibers other than heat-stretchable fibers, or is composed of heat-stretchable fibers and other fibers.

[0045] The upper layer 11 of the front sheet 10 is a fiber assembly containing heat-stretchable fibers, and the lower layer of the front sheet 10 is a fiber assembly that does not contain heat-stretchable fibers or contains heat-stretchable fibers at a lower mass ratio than the upper layer. Therefore, liquid is less likely to remain on the front sheet 10. In other words, a front sheet for absorbent articles can be provided that prevents liquid from remaining on the surface of the front sheet 10 and maintains a good skin feel after liquid absorption.

[0046] The front sheet 10 is constructed such that the contact angle between the fibers constituting the upper layer 11 and water is greater than the contact angle between the fibers constituting the lower layer 12 and water. The contact angle between fibers and water is one of the indicators of the hydrophilicity of fibers; the smaller the contact angle, the higher the hydrophilicity. That is, the front sheet 10 is constructed such that the constituent fibers of the lower layer 12 have higher hydrophilicity than the constituent fibers of the upper layer 11.

[0047] The contact angle between the fibers constituting the lower layer 12 and water is preferably 60° or more, more preferably 65° or more, and even more preferably 70° or more. It is also preferably 95° or less, more preferably 90° or less, and even more preferably 85° or less. Similarly, the contact angle between the fibers constituting the lower layer 12 and water is preferably 55° or more, more preferably 60° or more, and even more preferably 65° or more. It is also preferably 90° or less, more preferably 85° or less, and even more preferably 80° or less. The contact angle between the fibers and water can be appropriately adjusted, for example, by changing the raw materials of the fibers, or by performing hydrophilic or hydrophobic treatment on the fiber surface. By adjusting the contact angle between the fibers and water to the above range, a hydrophilic gradient can be formed between the upper layer 11 and the lower layer 12, where the hydrophilicity of the lower layer 12 is greater than that of the upper layer 11. Therefore, bodily fluids excreted to the upper layer 11 can easily penetrate to the lower layer 12, which has a higher hydrophilicity.

[0048] [Methods for measuring the contact angle with water]

[0049] The contact angle between the fiber and water can be measured, for example, by cutting fibers located on the outer surface (skin-contact surface) of the upper layer 11 constituting the front sheet 10 and fibers located on the outer surface (non-skin-contact surface) of the lower layer 12 into 1mm lengths, and using these as measurement samples to measure the contact angle between these samples and water. An automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. is used as the measuring device. Distilled water is used in the contact angle measurement.

[0050] The sample was placed on the sample stage of the contact angle meter, kept horizontal. A water droplet was dropped directly above the fibers of the sample, using a 10 picoliter jet from an inkjet nozzle (CTC-25 pulse jet, manufactured by Cluster Technology, with a nozzle orifice diameter of 25 μm). The droplet was recorded using a high-speed video recording device connected to a horizontally positioned camera. Ideally, the recording device would be a personal computer equipped with a high-speed capture device, for subsequent image analysis. In this measurement, images were recorded every 17 ms. From the recorded images, the initial image of the water droplet falling onto the fibers removed from the nonwoven fabric was analyzed using the accompanying FAMAS software (version 2.6.2, droplet method, θ / 2 method, non-reflective image processing algorithm, frame mode, threshold level of 200, no curvature correction). This image was used to calculate the angle between the surface of the water droplet in contact with the air and the fiber, and this angle was set as the contact angle. The contact angle of each sample was measured at two different locations.

[0051] The contact angles of five measurement samples (N=5) obtained from the fibers on the skin-contact surface of the upper layer 11 are measured to one decimal place. The arithmetic mean of the measurements from these ten locations (rounded to two decimal places) is defined as the contact angle between the fibers of the upper layer constituting the front sheet and water. Similarly, the contact angles of five measurement samples (N=5) obtained from the fibers on the non-skin-contact surface of the lower layer 12 are measured to one decimal place. The arithmetic mean of the measurements from these ten locations (rounded to two decimal places) is defined as the contact angle between the fibers of the lower layer constituting the front sheet and water. Regarding the boundary between the upper layer 11 and the lower layer 12, for example, the areas where the fiber assemblies of the upper layer 11 and lower layer 12 of the front sheet 10 exist can be divided using the contact angles of each fiber. The boundary surface F can be defined as the dividing line between the different contact angles of the fibers.

[0052] like Figure 1 As shown, the upper layer 11 of the front sheet 10 is composed of a variety of fibers with different contact angles with water. For example, the upper layer 11 is preferably a fiber assembly composed of a thermally elongating fiber and a second fiber different from the thermally elongating fiber, and each fiber has a different hydrophilicity.

[0053] By making the contact angle between the fibers constituting the upper layer 11 and water larger than the contact angle between the fibers constituting the lower layer 12 and water, it has the advantage of further reducing liquid residue on the surface of the front sheet 10. Furthermore, by including multiple fibers with different contact angles with water in the upper layer 11 constituting the front sheet 10, liquid diffusion on the front sheet 10 can be suppressed, and liquid can easily penetrate into the thickness direction of the front sheet 10, thus making it less likely for liquid to remain on the front sheet 10.

[0054] Furthermore, when the fibers constituting the upper layer 11 include a variety of fibers with different contact angles, from the viewpoint of more easily demonstrating the effects of the present invention, the content of fibers in the upper layer 11 with a larger contact angle with water than the fibers constituting the lower layer 12 is preferably 50% or more, more preferably 90% or more.

[0055] The percentage of fibers in the upper layer 11 that have a larger contact angle with water than the fibers in the lower layer 12 can be measured by the following method.

[0056] [Method for measuring the content of fibers in the upper layer that have a larger contact angle with water than the fibers in the lower layer]

[0057] When viewing the front sheet 10 from the skin-contact side, a predetermined area (e.g., an area enclosed by a 3cm x 3cm square) is determined from the area opposite the excretory portion. Five fibers contained within a 1mm distance from the upper skin-contact surface and five fibers contained in the lower layer are taken out in the thickness direction. The contact angle between each fiber and water is measured using the method described in the [Method for measuring the contact angle with water].

[0058] For each sample, the contact angles at six different locations were measured. The contact angles with water at 30 locations obtained by measuring the fibers contained in the upper layer 11 were compared with those at 30 locations obtained by measuring the fibers contained in the lower layer 12.

[0059] Specifically, the fibers taken from the upper layer 11 are arranged in descending order of their contact angles with water (N=30 for each fiber). Similarly, the fibers taken from the lower layer 12 are arranged in descending order of their contact angles with water (N=30 for each fiber). The calculation method for "the percentage of fibers in the upper layer 11 with a larger contact angle with water than the fibers in the lower layer 12" is as follows.

[0060] The contact angles of fibers taken from the upper layer 11 with water are compared with those of fibers taken from the lower layer 12. A content of 50% or more is defined as the case where 15 or more contact angles of fibers constituting the upper layer 11 are greater than those of fibers constituting the lower layer 12. A content of 100% is defined as the case where all 30 contact angle values ​​of fibers taken from the upper layer 11 are greater than those of fibers taken from the lower layer 12.

[0061] In addition, regarding the location for removing fibers from the upper layer 11 and the lower layer 12, it is ideal to select the central area of ​​the absorbent material (the area opposite the excretory part).

[0062] When the fibers constituting the lower layer 12 are of two or more types, the content of the fiber constituting the upper layer 11 that has a larger contact angle with water than the most abundant fiber constituting the lower layer 12 is preferably 50% or more, more preferably 90% or more. Furthermore, the term "most abundant fiber" in the lower layer 12 refers to the fiber with the highest number of fibers constituting the lower layer 12, and the content of the "most abundant fiber" is preferably 50% or more, more preferably 80% or more, in the fibers constituting the lower layer 12.

[0063] From the viewpoint that the effect of making it less likely for liquid to remain on the front sheet 10 is more significant, the upper layer 11 preferably includes a thermally elongated fiber and a second fiber different from the thermally elongated fiber, and the contact angle of the thermally elongated fiber is greater than that of the second fiber.

[0064] From the viewpoint of presenting a hydrophilic gradient between the upper layer 11 and the lower layer 12, and further improving the introduction of residual bodily fluids on the skin-contact surface of the upper layer 11 to the lower layer 12, it is preferable that the contact angle between each fiber constituting the upper layer 11 and water is greater than the contact angle between the fibers constituting the lower layer 12 and water. When the lower layer 12 contains multiple fibers, it is preferable that the contact angle between the fiber with the largest contact angle among the constituent fibers of the upper layer 11 and water is greater than the contact angle between the most abundant fiber among the constituent fibers of the lower layer 12 and water. More preferably, the contact angle between each fiber constituting the upper layer 11 and water is greater than the contact angle between the most abundant fiber among the constituent fibers of the lower layer 12 and water. Furthermore, it is preferable that the contact angle between each fiber constituting the upper layer 11 and water is greater than the contact angle between each fiber constituting the lower layer 12 and water.

[0065] When the upper layer 11 contains a second fiber different from the heat-elongating fiber in addition to the heat-elongating fiber, the second fiber can be, for example, a non-heat-elongating heat-welding fiber containing two components with different melting points, and which does not elongate upon heating. Specifically, for example, a composite fiber can be used, which contains a high-melting-point component and a low-melting-point component having a melting point lower than that of the high-melting-point component, the low-melting-point component being continuously present in at least a portion of the fiber surface along its length. Various forms of the heat-welding composite fiber can be listed, such as core-sheath type and parallel type; concentric or eccentric core-sheath type fibers, where the core is composed of a high-melting-point component and the sheath is composed of a low-melting-point component, are preferred. Furthermore, from the viewpoint of effectively embodying the heat-welding properties of the second fiber, it is preferable that both the high-melting-point component and the low-melting-point component constituting the second fiber are resin components.

[0066] When using non-thermally elongated thermoplastic fibers as the second fiber, the preferred combination of high-melting-point and low-melting-point components is as follows. Specifically, PP can be used as the high-melting-point component, and one or more of polyethylene (HDPE), ethylene-propylene copolymers (LDPE and LLDPE), and polystyrene can be used as the low-melting-point component.

[0067] In addition, as another example of a preferred combination of high-melting-point and low-melting-point components, polyester resins such as PET and PBT can be used as high-melting-point components, and one or more of polyethylene, ethylene-propylene copolymers such as HDPE, LDPE and LLDPE, polystyrene, PP and copolyesters can be used as low-melting-point components.

[0068] As another example of a preferred combination of high-melting-point and low-melting-point components, one or more of polyamide polymers, two or more copolymers of the aforementioned high-melting-point components can be used as the high-melting-point component, and one or more of the two or more copolymers of the aforementioned low-melting-point components can be used as the low-melting-point component.

[0069] In addition to the combinations mentioned above, it may also include natural fibers such as cotton and pulp, as well as fibers such as rayon and cellulose acetate that are not heat-weldable and not heat-stretchable.

[0070] Whether the upper layer 11 of the front sheet 10 contains heat-stretchable fibers can be determined by measuring the heat elongation of the fibers taken from the front sheet 10 using the following method.

[0071] [Methods for identifying heat-extensible fibers]

[0072] First, 10 fibers were collected from the front slide. The length of the collected fibers was set to 1 mm. The collected fibers were clamped between the specimen slides, and the total length of the clamped fibers was measured. The measurement was performed using a VHX-6000 digital microscope manufactured by KEYENCE Corporation. The measurement was performed as follows: the fibers were observed at a magnification of 50 to 100 times, and the observed image was measured using the measuring tool assembled in the device. The length obtained in the above measurement was set as "total length of the fibers collected from the front slide" F1. The fibers with the measured total length were placed in a sample container (product name: Robot Container 52-023P, 15 μL, aluminum) for a DSC6200 manufactured by SII NanoTechnology Co., Ltd. The container containing the fibers was placed in the sample placement position in the heating furnace of the DSC6200, and the temperature of the heating furnace was preset to be 10°C lower than the melting point or softening point of the low melting point component (second resin component) of the fibers. Starting from a temperature (displayed as "sample temperature" in the measurement software) measured by a thermocouple positioned directly below the sample placement location on the DSC6200, which is within ±1°C of the melting or softening point of the low-melting-point component (second resin component), heat for 60 seconds, then quickly remove. Remove the heat-treated fiber from the sample container of the DSC, clamp it between specimen slides, and measure the total length of the clamped fiber. Measure using a KEYENCE VHX-900 microscope and VH-Z20R lens. Measurements are performed as follows: observe the fiber at 50-100x magnification, and measure the observed image using the measuring tool assembled in the device. Set the length obtained in the above measurement as "total length of the heat-treated fiber" F2. Calculate the thermal elongation (%) according to the following formula. When the thermal elongation is greater than 0%, the fiber is determined to be a thermally elongated fiber; when the thermal elongation is less than 0%, the fiber is determined to be a non-thermally elongated fiber. The fiber with a thermal elongation of 0% or less is the second fiber of the present invention. In addition, "elongation of 0% or less" means that the total length of the fiber does not change before and after heating, or the total length of the fiber becomes shorter due to heating (thermal shrinkage).

[0073] Fiber elongation at heat (%) = 100 × (F2 - F1) / F1

[0074] In addition, when it is determined by the above method that the upper layer 11 contains a second fiber in addition to the thermally elongated fiber, the contact angle of each fiber is measured separately by the above method.

[0075] In the front sheet 10, preferably, the average fiber diameter of the fiber with the smallest average fiber diameter among the fibers constituting the upper layer 11 is greater than the average fiber diameter of the fibers constituting the lower layer 12. By adopting this structure, the fiber density of the lower layer 12 is denser than that of the upper layer 11, thus exhibiting stronger capillary forces and excellent absorption of body fluid from the upper layer 11 to the lower layer 12. As a result, a sheet with a good skin feel can be obtained, which efficiently transfers absorbed body fluid to the non-skin-contact side and minimizes the feeling of liquid residue. The lower layer 12 can use one or more fibers. When the lower layer 12 contains multiple fibers, the fiber diameter of the fibers constituting the upper layer 11 is compared with the fiber diameter of the fiber with the largest average fiber diameter among the fibers constituting the lower layer 12.

[0076] The average fiber diameter of the fiber with the smallest average fiber diameter among the fibers constituting the upper layer 11, when expressed in terms of fiber fineness (dtex), is preferably 2.0 dtex or more, more preferably 2.5 dtex or more, and even more preferably 3.0 dtex or more, preferably 8.0 dtex or less, more preferably 7.0 dtex or less, and even more preferably 6.0 dtex or less. Similarly, the fiber diameter of the constituent fibers of the lower layer 12, when expressed in terms of fineness, is preferably 1.0 dtex or more, more preferably 1.2 dtex or more, and even more preferably 1.5 dtex or more, preferably 5.0 dtex or less, more preferably 4.0 dtex or less, and even more preferably 3.0 dtex or less. When the lower layer 12 contains multiple fibers, the fiber with the largest average fiber diameter among the fibers constituting the lower layer 12 only needs to be within the above-mentioned range.

[0077] The fineness of the fiber can be measured using the following method: A 50mm × 100mm (area 5000mm²) section is cut from the front sheet 10 in an unloaded state. 2 A rectangular sample was prepared for measurement. Next, regarding the fineness of the fibers in the upper layer 11, a cross-sectional observation was performed on the measurement sample. Using 10 standard fibers located on the outer surface (skin-contact surface) of the upper layer 11 as the object, the fiber thickness was actually measured using an electron microscope, and the arithmetic mean Dn (μm) of the fiber thickness was calculated. Then, using a differential scanning calorimeter (DSC), the resin composition of the standard fibers at a position 10 mm away from the skin-contact surface was determined, and the theoretical fiber density Pn (g / cm³) was calculated. 3 Based on the arithmetic mean of fiber fineness Dn (μm) and theoretical fiber density Pn (g / cm³),3 The weight (g) of each 10,000 m fiber length was calculated, and this calculated value was set as the fineness (dtex) of the upper layer 11 fibers. Regarding the fineness of the lower layer 12 fibers, a cross-section of the measurement sample was observed. Ten standard fibers located on the outer surface (non-skin-contact surface) of the measurement sample were used as the subjects, and the fineness was measured in the same manner as the fibers on the skin-contact surface side.

[0078] like Figure 1 and Figure 2 As shown, when a fixing portion 15 is formed to join the upper layer 11 and the lower layer 12 together, as... Figure 2 As shown, when viewed from above, the front panel 10 preferably has a macroscopic pattern including a row of fixed portions, which is formed by alternating straight first fixed portions 15a and second fixed portions 15b arranged in one direction.

[0079] In detail, such as Figure 2 As shown, the front panel 10 has a first fixing row L1, which is formed by a plurality of straight first fixing portions 15a and straight second fixing portions 15b shorter than the first fixing portions 15a, alternating and along one direction (in... Figure 2 The first fixing parts L1 are arranged in a manner extending from the upper left to the lower right on the paper. Multiple rows of first fixing parts L1 are formed with different intervals between adjacent rows of first fixing parts L1. The first fixing parts L1 are inclined relative to the X direction in this figure, and the rows of first fixing parts L1 are arranged parallel to each other without intersecting. Similarly, in the second fixing part row L2, multiple first fixing parts 15a and second fixing parts 15b are arranged alternately and along one direction (in... Figure 2 The second fixing portions L2 are arranged in a manner extending from the upper right to the lower left on the paper. Multiple rows of second fixing portions L2 are formed with varying intervals between adjacent rows. The second fixing portions L2 are inclined relative to the X direction in this figure, and are arranged parallel to each other without intersecting. Each second fixing portion row L2 is arranged to extend in a direction intersecting with each first fixing portion row L1. This arrangement of the first fixing portions L1 and the second fixing portions L2 prevents bodily fluids from spreading in one direction on the front panel 10, which is therefore preferable.

[0080] In addition, such as Figure 2As shown, preferably, the first fixing portion 15a and the second fixing portion 15b in the first fixing portion row L1, and the first fixing portion 15a and the second fixing portion 15b in the second fixing portion row L2, are arranged in a manner that do not intersect each other. Considering the first fixing portion row L1, the first fixing portion 15a and the second fixing portion 15b constituting the second fixing portion row L2 are arranged in a manner that do not connect adjacent first fixing portions 15a and second fixing portions 15b in the extending direction of the first fixing portion row L1. Furthermore, considering the second fixing portion row L2, the first fixing portion 15a and the second fixing portion 15b constituting the first fixing portion row L1 are arranged in a manner that do not connect adjacent first fixing portions 15a and second fixing portions 15b in the extending direction of the second fixing portion row L2.

[0081] The region containing the intersection of the first fixed-fitting section L1 and the second fixed-fitting section L2 is a non-joining region N1 that is not joined by each fixed-fitting section 15a, 15b. The non-joining region N1 is formed by a first non-fixed region in the first fixed-fitting section L1 located between adjacent first fixed-fitting sections 15a and 15b in the row direction, and a second non-fixed region in the second fixed-fitting section L2 located between adjacent first fixed-fitting sections 15a and 15b in the row direction. The non-joining region N1 is formed between adjacent first protrusions 18a and 18c in the X direction and the Y direction orthogonal to the X direction, respectively, and each protrusion 18a, 18b, and 18c is continuous through the non-joining region N1. Both the first fixed-fitting section 15a and the second fixed-fitting section 15b are recesses 17, which are thinner than each protrusion 18 and the non-joining region N1.

[0082] As mentioned above, such as Figure 2 As shown, by arranging the first fixed portion row L1 and the second fixed portion row L2 having two types of fixed portions 15a and 15b in such a way as forming a non-bonding region N1, the body fluid can be efficiently diffused in the sheet plane direction and absorbed by the lower layer 12 side via the non-bonding region N1 formed between each fixed portion 15. Therefore, the liquid residue on the sheet surface can be further reduced more effectively.

[0083] The content of the heat-stretchable fiber in the upper layer 11 is preferably 20% by mass or more, more preferably 30% by mass or more, more preferably 80% by mass or less, and more preferably 70% by mass or less in the total mass of the upper layer 11. Furthermore, the content of the second fiber is preferably 20% by mass or more, more preferably 30% by mass or more, more preferably 80% by mass or less, and more preferably 70% by mass or less in the total mass of the upper layer 11.

[0084] As the fiber constituting the lower layer 12, for example, a non-thermally elongating heat-welding fiber containing two components with different melting points can be used, and the fiber does not substantially elongate upon heating. The same fiber as the second fiber of the upper layer 11 can be used as the non-thermally elongating heat-welding fiber. Furthermore, it may also include natural fibers such as cotton and pulp, as well as fibers that are not thermally weldable and are non-thermally elongating, such as rayon and acetate fibers.

[0085] The following is for reference Figure 3 This describes a preferred manufacturing method for the front sheet 10 using the thermally elongated composite fiber. Figure 3 This describes one embodiment of a manufacturing apparatus suitable for this manufacturing method. First, a lower layer web 12A, serving as the blank for the lower layer 12, is produced using a predetermined web forming mechanism (not shown). The lower layer web 12A is configured to contain no heat-stretching fibers, or to contain heat-stretching fibers at a lower ratio than the upper layer 11. Furthermore, an upper layer web 11A, serving as the blank for the upper layer 11, is produced separately from the lower layer web 12A using a predetermined web forming mechanism (not shown). The upper layer web 11A contains heat-stretching fibers. There are no particular limitations on the web forming mechanism; for example, carding, airflow, etc., can be used.

[0086] Next, the upper mesh fabric 11A and the lower mesh fabric 12A are conveyed in one direction R while being overlapped to form a laminate 10A. This laminate is then conveyed and introduced into the hot embossing device 21. The hot embossing device 21 includes an engraving roller 22 with protrusions on its circumferential surface corresponding to the shape of the fixing portion 15, and a smoothing roller 23 with a smooth circumferential surface. Each roller 22 and 23 can be heated to a specified temperature. By guiding the laminate 10A between the rollers 22 and 23, the laminate 10A is subjected to integral hot embossing processing. Through hot embossing processing, a processed laminate 10B with the fixing portion 15 is obtained, which is formed by bonding the upper mesh fabric 11A and the lower mesh fabric 12A in a non-peelable manner.

[0087] The hot embossing process is carried out at a suitable temperature where at least one of the components constituting the upper mesh 11A and the lower mesh 12A is melted and the meshes 11A and 12A are hot-fused together. The processing temperature for the hot embossing process is preferably a temperature above the melting point of the low-melting-point component of the thermally elongated fiber in the upper mesh 11A and below the melting point of the high-melting-point component.

[0088] Next, the processed laminate 10B, with the fixed portion 15 formed thereon, is introduced into the hot air blowing device 25. After being introduced into the hot air blowing device 25, hot air heated to a predetermined temperature is blown onto the processed laminate 10B to perform hot air processing. The hot air processing is appropriately performed at a temperature at which the heat-elongating fibers in the processed laminate 10B elongate, and at a temperature above the melting point of the low-melting-point component of the heat-elongating fibers but below the melting point of the high-melting-point component.

[0089] By applying hot air to the processed laminate 10B, the thermally elongated fibers contained in the upper layer 11 elongate in the portion other than the fixing portion 15. The elongated portion of the thermally elongated fibers moves outward in the thickness direction of the processed laminate 10B, forming a protrusion 18 in the region of the upper layer 11 surrounded by the fixing portion 15. In this way, a target front sheet 10 made of nonwoven fabric is obtained.

[0090] Furthermore, in the front sheet 10 manufactured in this manner, the heat-stretchable fibers that are heat-stretched by hot air processing remain heat-stretchable fibers. That is, the heat-stretchable fibers present in the front sheet 10 exist in a heat-stretchable state. In order for the fibers to also be able to heat-stretch after hot air processing, for example, the temperature of the hot air blown onto the processed laminate 10B during hot air processing can be set above the melting point or softening point of the second resin component constituting the heat-stretchable fibers in the processed laminate 10B, within a range of +10°C to the melting point or softening point of the second resin component, and below the melting point or softening point of the first resin component. When manufacturing the front sheet 10, by performing heat treatment under these conditions, the low-melting-point second resin component can be melted to form fusion points between fibers, thus obtaining a fluffy front sheet 10 with excellent texture and strength. In addition, it is possible to prevent the deterioration of the sheet's texture and the reduction of the sheet's strength due to excessive melting of the heat-stretchable fibers.

[0091] like Figure 4 As shown, in the absorbent article of the present invention, a nonwoven fabric intermediate sheet 30 is disposed adjacent to the front sheet 10 between the front sheet 10 and the absorbent body 40. Figure 5 (a) is a top view of the intermediate sheet, showing a preferred example of the intermediate sheet 30 preferably used in the absorbent article of the present invention.

[0092] The nonwoven fabric constituting the intermediate sheet 30 has an embossed portion 31 formed by embossing a fiber layer containing the nonwoven fabric or fiber web. In the embossed portion 31, a portion of the fiber layer constituting the intermediate sheet 30 is compacted. In the intermediate sheet 30, the embossed portion 31 is compacted and thinner than the non-embossed portion 32.

[0093] like Figure 5 As shown in (b), in the embossed portion 31 of the intermediate piece 30, both the skin-contact side and the non-skin-contact side can be recessed portions 31b, and either the skin-contact side or the non-skin-contact side can be recessed portions 31b.

[0094] like Figure 5 As shown in (a), when viewed from above, the intermediate sheet 30 preferably has a plurality of embossed portions 31 formed in a state of being separated from each other by non-embossed portions 32. Figure 5In the intermediate sheet 30 shown in (a), the embossed portion 31 is configured as follows: a plurality of mutually parallel first embossed portion rows R3 extending in one direction XY1, and a plurality of mutually parallel second embossed portion rows R4 extending in another direction XY2 intersecting the one direction.

[0095] In the intermediate sheet 30, the area ratio of the embossed portion 31 is greater than the area ratio of the fixing portion 15 of the front sheet 10. The fixing portion 15 of the front sheet 10 is equivalent to the embossed portion of the front sheet in this invention. Therefore, the fixing portion 15 of the front sheet 10 will also be referred to as the embossed portion 15 of the front sheet 10 below.

[0096] The so-called embossed area ratio (embossing rate) refers to the ratio of the total area of ​​the embossed area to the area of ​​the entire sheet, and is measured in the following manner.

[0097] [Method for measuring the area ratio of embossed areas]

[0098] Cut a rectangular sample of the absorbent material from the front or middle sheet used for measurement. The sample is 50 mm long and 40 mm wide.

[0099] Next, using a microscope (KEYENCE VHX-900 microscope, lens VH-Z20R), a magnified photograph of the cut sample surface was obtained. The scale bar was matched with the magnified photograph, and the size of the embossed part in the overall area T within the field of view was measured to calculate the embossed part area U.

[0100] The area ratio (embossing rate) of the embossed part can be calculated using the formula (U / T)×100.

[0101] When the boundary between the embossed area and the rest of the area is unclear, it can be determined by examining a magnified photograph of the front or middle section of the sheet being measured. Because the fibers in the embossed area are flattened or in a membrane-like state, the embossed area can be identified by examining a magnified photograph of the sheet, thus distinguishing the boundary between the embossed area and the rest of the area.

[0102] Furthermore, when the absorbent item is a menstrual sanitary napkin, a compression groove from the front sheet to the absorbent core is usually provided as a leak-proof groove, but the sample was cut from a part without a leak-proof groove. Additionally, if there are embossings from the front sheet to the middle sheet or absorbent core other than leak-proof grooves, and it is impossible to cut the sample without these embossings, the sample can be cut with the embossings included, and the area ratio can be measured. Examples of embossings from the front sheet to the absorbent core other than leak-proof grooves include pin embossing formed across the entire front sheet when viewed from above.

[0103] Furthermore, in this invention, the intermediate sheet 30 is used such that the contact angle between the fibers constituting the intermediate sheet 30 and water is greater than the contact angle between the fibers constituting the front sheet 10 and water.

[0104] Regarding the contact angle between the fibers constituting the front sheet and the middle sheet and water, for each sheet, in the same manner as the contact angle measurement method, 5 measurement samples are taken from the fibers located on the skin-contact surface of the front sheet, and 5 measurement samples are taken from the fibers located on the non-skin-contact surface of the middle sheet and in the non-embossed portion 32. The contact angles of these 10 measurement samples (N=10) are measured to one decimal place. The arithmetic mean of the measurement values ​​of the 10 locations is taken as the value obtained (rounded to two decimal places) and set as the contact angle between the fibers constituting the front sheet or the middle sheet and water.

[0105] Furthermore, when the fibers constituting the intermediate sheet 30 contain multiple fibers with different contact angles, the content of fibers in the intermediate sheet 30 with a larger contact angle with water than the fibers constituting the lower layer 12 of the front sheet is preferably at least 50%, more preferably at least 80%. Regarding the content of fibers in the intermediate sheet 30 with a larger contact angle with water than the fibers constituting the lower layer 12 of the front sheet, this can be measured in the same manner as described above in the [Method for measuring the content of fibers in the upper layer with a larger contact angle with water than the fibers constituting the lower layer], except that fibers are removed from the intermediate sheet 30 instead of the upper layer 11. Furthermore, when the lower layer 12 contains multiple fibers, the content of fibers in the intermediate sheet 30 with a larger contact angle with water than the most abundant fiber constituting the lower layer 12 is preferably at least 50%, more preferably at least 80%. Furthermore, the contact angle of the fibers constituting the intermediate sheet 30 is preferably 97° or less, more preferably 90° or less, and on the other hand, preferably 75° or more, more preferably 78° or more.

[0106] The difference between the contact angle of the fibers constituting the intermediate sheet 30 and the contact angle with water, expressed as the former minus the latter, is preferably 2° or more, more preferably 5° or more, and further preferably 15° or less, more preferably 10° or less. Furthermore, this preferred range of contact angle difference also applies to the relationship between the upper layer 11 of the front sheet 10 and the intermediate sheet 30.

[0107] According to the absorbent article of the present invention, the hydrophilicity of the fibers constituting the lower layer 12 of the front sheet is higher than that of the fibers constituting the upper layer 11. Therefore, bodily fluids excreted to the upper layer 11 side are easily transferred to the lower layer 12 side, which has higher hydrophilicity. In addition, by using an intermediate sheet 30 with a larger embossed area ratio than the front sheet 10 and a larger contact angle with water than the lower layer of the front sheet 10, the speed at which liquid passes through the front sheet 10 and the intermediate sheet 30 increases. Even in cases of large excretion volume and fast excretion speed, liquid can be quickly transferred from the front sheet to the absorbent, further reliably preventing discomfort caused by the stickiness of the front sheet surface. The reason for this is as follows: when the embossed area ratio of the intermediate sheet is high, the absorbency of liquid from the front sheet to the embossed area of ​​the intermediate sheet or its vicinity is increased. On the other hand, liquid tends to remain in other parts. When the contact angle of the fibers constituting the intermediate sheet is increased to improve the water repellency, liquid is less likely to remain in that part. Through the embossed area and its vicinity, liquid is smoothly transferred to the absorbent 40. Furthermore, the structure of the present invention may exist at least in the area opposite the excretory portion (or the crotch area), preferably also in the rear portion, and even more preferably also in the front portion.

[0108] From the viewpoint of achieving this effect more reliably, the contact angle between the fibers constituting the intermediate sheet 30 and water is preferably greater than the contact angle between the fibers constituting the upper layer of the front sheet 10 and water.

[0109] Furthermore, from the viewpoint of improving the transferability of liquid from the front sheet, it is preferable that the contact angle with water increases in the order of the fibers constituting the lower layer of the front sheet, the fibers constituting the upper layer of the front sheet, and the fibers constituting the middle sheet. By making the contact angle between the fibers constituting the middle sheet and water larger than that between the fibers constituting the lower layer of the front sheet, it is also possible to prevent the backflow of liquid transferred to the absorbent.

[0110] From the viewpoint of improving the transferability of liquid from the front sheet 10, the area ratio (%) of the embossed portion of the middle sheet 30 is preferably 15% or more, more preferably 20% or more, and preferably 40% or less, more preferably 35% or less, preferably 15% or more and 40% or less, more preferably 20% or more and 35% or less.

[0111] From the same point of view, the difference between the area ratio of the embossed portion of the middle sheet 30 and the area ratio of the embossed portion of the front sheet 10 is preferably 2 percentage points or more, more preferably 5 percentage points or more, and preferably 40 percentage points or less, more preferably 35 percentage points or less, preferably 2 percentage points or more and 40 percentage points or less, and more preferably 5 percentage points or more and 35 percentage points or less.

[0112] On the other hand, from the viewpoint of surface liquid residue and skin feel of the front sheet 10, the area ratio (%) of the embossed portion of the front sheet 10 is preferably 5% or more, more preferably 7% or more, and preferably 13% or less, more preferably 11% or less, preferably 5% or more and 13% or less, more preferably 7% or more and 11% or less.

[0113] The front sheet 10 of the present invention is not limited to having a structure with a fixing portion (embossed portion) that bonds the upper and lower layers together, but it is preferable that the front sheet 10 has a fixing portion (embossed portion) that bonds the upper and lower layers together, and the area ratio of the embossed portion of the middle sheet 30 is greater than that of the front sheet 10. By adopting this structure, liquid is less likely to remain on the front sheet 10, and heat and rashes can be effectively prevented.

[0114] As the fiber constituting the intermediate sheet 30, for example, a non-thermally elongating heat-welding fiber containing two components with different melting points and which does not substantially elongate upon heating can be used. The same fiber as the second fiber of the upper layer 11 can be used as the non-thermally elongating heat-welding fiber. Furthermore, it may also include natural fibers such as cotton and pulp, as well as fibers that are not thermally weldable and are non-thermally elongating, such as rayon and acetate fibers.

[0115] From the viewpoint of improving the transferability of liquid from the front sheet 10 to the absorber 40, and from the viewpoint of preventing liquid backflow from the absorber 40, the basis weight of the intermediate sheet 30 is preferably 15 g / m³. 2 The above, and more preferably 17.5 g / m 2 The above is preferably 40g / m 2 The preferred value is 37.5 g / m³. 2 Furthermore, 15 g / m² is preferred. 2 Above and 40g / m 2 The preferred value is 17.5 g / m³. 2 Above and 37.5g / m 2 the following.

[0116] The weight of the intermediate sheet 30 can be greater or less than the weight of the front sheet 10, but it is preferably approximately equal to the weight of the front sheet 10.

[0117] In this invention, the front sheet 10 and the middle sheet 30 are not necessarily joined together. However, it is preferable that the front sheet 10 and the middle sheet 30 are joined together, for example as shown below. Figure 4 As shown, the front sheet 10 and the intermediate sheet 30 are joined together by a compression portion 35 that is integrally compressed. Alternatively, the front sheet 10 and the intermediate sheet 30 may be joined together with an adhesive, either as an alternative to this structure or together with it. By joining the front sheet 10 and the intermediate sheet 30, the transferability of liquid from the front sheet 10 to the intermediate sheet 30 is further improved.

[0118] In the absorbent article of the present invention, the constituent fibers of the front sheet 10 and the middle sheet 30 preferably contain inorganic fillers. Examples of inorganic fillers include titanium dioxide, silicon dioxide, and calcium carbonate. In the present invention, one or more of these inorganic fillers may be used alone or in combination. In terms of the concealment of the nonwoven fabric, titanium dioxide, especially titanium dioxide, is preferred among these inorganic fillers.

[0119] From the viewpoint of improving the concealment of the color of absorbed liquids such as menstrual blood, the content of inorganic filler in the constituent fibers of the front sheet 10 or the middle sheet 30 is preferably 0.5% by mass or more, more preferably 1.0% by mass or more. On the other hand, the content of inorganic filler in the constituent fibers of both the front sheet and the middle sheet 30 is preferably 10% by mass or less, more preferably 9.0% by mass or less, and further preferably 0.5% by mass or more and 10% by mass or less, more preferably 1.0% by mass or more and 9.0% by mass or less.

[0120] The present invention has been described above based on its preferred embodiments, but the present invention is not limited to the above embodiments.

[0121] For example, the top view shape of each embossed part of the intermediate piece 30 can be a rectangle instead of a square, or it can be any other shape such as a circle, triangle, or ellipse. In addition, the embossed parts are not limited to multiple independent embossed parts, but can also be a grid-like continuous embossed part, etc.

[0122] Experimental Example

[0123] The present invention will now be described in further detail with reference to experimental examples. However, the scope of the present invention is not limited to these experimental examples.

[0124] [Experimental Example 1]

[0125] use Figure 3 The manufacturing apparatus shown is used to produce a front sheet 10, which includes an upper layer 11 (gram weight 12.5 g / m²) composed only of two types of fibers: a heat-stretchable fiber (core resin: PP (melting point 164°C) / sheath resin: HDPE (melting point 126°C)) and a heat-fused fiber (core resin: PET (melting point 251°C) / sheath resin: HDPE (melting point 126°C)) as a second fiber. 2 The lower layer 12 (gram weight 12.5 g / m²) consists only of heat-fused fibers (core resin: PET (melting point 251℃) / sheath resin: HDPE (melting point 126℃)). 2 The upper layer 11 contains 50% by mass of heat-stretchable fibers and 50% by mass of heat-fusion fibers.

[0126] The front panel 10 has a textured surface formed by hot embossing. Figure 2 The fixed portions 15 formed by the pattern shown are configured such that: the length of the first fixed portion 15a in each fixed portion row L1, L2 is 8.1 mm, the length of the second fixed portion 15b is 5.6 mm, and the interval between the first fixed portion 15a and the second fixed portion 15b in a fixed portion row is 2.0 mm. Table 1 shows the contact angle and fineness of the constituent fibers of the two layers 11, 12, and the area ratio of the fixed portions (embossed portions) of the fabricated front sheet 10.

[0127] Furthermore, the percentage (%) of inorganic filler (titanium oxide) in the constituent fibers of the front sheet is shown in Table 1. The basis weight of the fabricated front sheet 10 is 25 g / m². 2 .

[0128] As the intermediate sheet, a nonwoven fabric containing 100% by mass of heat-melting fibers (core resin: PET (melting point 251℃) / sheath resin: HDPE (melting point 126℃)) is used, which is processed by heat embossing to... Figure 5 The pattern shown in (a) is provided with embossed portions 31. The contact angle and average fiber diameter of the intermediate sheet 30 are shown together in Table 1. For either the first embossed portion row R3 or the second embossed portion row R4, the length L3 of the embossed portion along the row is set to 0.77 mm, and the arrangement pitch L4 of the embossed portion along the row is set to 1.4 mm. The contact angle and average fiber diameter of the constituent fibers of the manufactured intermediate sheet 30, as well as the area ratio of the embossed portion of the manufactured intermediate sheet 30, are shown in Table 1.

[0129] Furthermore, the percentage (%) of inorganic filler (titanium oxide) in the constituent fibers of the intermediate sheet is shown in Table 1. The basis weight of the produced intermediate sheet 30 is 25 g / m². 2 .

[0130] An absorbent article (menstrual sanitary napkin) with a front sheet 10 and an intermediate sheet 30 is manufactured. Except for the front sheet 10 and the intermediate sheet 30 adjacent to it, the structure of the rest of the absorbent article is the same as that of the menstrual sanitary napkin (Laurier Slim Guard (registered trademark) heavy flow daytime winged sanitary napkin) manufactured by Kao Corporation.

[0131] [Experimental Example 2]

[0132] Except for changing the amount of inorganic filler, an intermediate sheet with the same embossed pattern as in Experimental Example 1 was obtained in the same manner as in Experimental Example 1. Menstrual sanitary napkins were manufactured in the same manner as in Experimental Example 1, except that the intermediate sheet was used. The contact angle and average fiber diameter of the intermediate sheet 30 are shown together in Table 1.

[0133] [Experiment Example 3]

[0134] The menstrual sanitary napkin (Laurier Slim Guard (registered trademark) heavy flow daytime winged sanitary napkin) manufactured by Kao Corporation was used as Experimental Example 3.

[0135] [Evaluation of liquid transit time]

[0136] The liquid penetration time of the sanitary napkins prepared in Experiments 1 and 2, and Experiment 3 was investigated. The shorter the liquid penetration time, the better the liquid permeability of the sanitary napkin, and the less likely liquid is to remain on the front side. The liquid penetration time was measured using a LISTER testing machine manufactured by LenzingTechnik. The sanitary napkins from Experiments 1, 2, and 3 were placed on the measuring section of the machine, and the liquid penetration time was investigated when 5g of test solution (simulated blood) was injected. The test solution was adjusted as follows: 1500g of deionized water was added to a 2L beaker, and while stirring with a magnetic stirrer, 5.3g of sodium carboxymethyl cellulose [manufactured by Kanto Chemical Co., Ltd., CMC-Na] was added (this solution is designated as "A"). Next, 556g of deionized water was added to a 1L beaker, and while stirring, 27.0g of sodium chloride [manufactured by Kanto Chemical Co., Ltd.] and 12g of sodium bicarbonate [NaHCO3, manufactured by Kanto Chemical Co., Ltd.] were added until completely dissolved (this solution is designated as "B"). Then, 900g of glycerol was measured into a 3L beaker, and the above solutions (A) and (B) were added and stirred. Next, 15ml of an aqueous solution of the nonionic surfactant "Emulgen 935" [manufacturer / distributor Kao Corporation] with a concentration (surfactant / water) of 1g / L was added, along with 0.3g of Edible Red No. 2 [distributor: Aizen Co., Ltd., Hodogaya Chemical Industry Co., Ltd.; manufacturer: Yamato Kasei Corporation], and stirred. The solution obtained in this manner was filtered using a glass filter, and the filtrate was used as simulated blood. Alternatively, when adjusting the simulated blood, other nonionic surfactants can be used instead of the above surfactants, and the same results can be obtained.

[0137] Table 1 shows the liquid transit time.

[0138] [Evaluation of Concealment (Concealment Rate of Red Board)]

[0139] The sheet obtained by overlapping the front and middle sheets prepared in Experimental Examples 1 and 2 will be used as an evaluation sample for concealment (masking). Concealment is represented by the concealment rate of the red plate as shown below. The concealment rate of the red plate will be determined using a colorimeter (product number SZ-Σ80) manufactured by Nippon Denshoku Co., Ltd. as follows.

[0140] First, the spectrophotometer of the attached red plate (using the red side as the measurement surface) was measured. Among the obtained absorption wavelengths, 500 cm⁻¹ was specifically selected. -1 Record the reflectance (Ra) at this point. Next, remove the red plate, place the sample on the sample stage, and then position the red plate so that the red side of the red plate is opposite to the back of the sample (the side opposite to the measurement surface). Measure one sample five times at different locations, and calculate the reflectance at 500cm. -1 The average reflectance (Rb) is used. The concealment rate of the red plate is calculated from the obtained values ​​of Ra and Rb according to the following formula (1).

[0141] Red board concealment rate (%) = [(Rb - Ra) / (100 - Ra)] × 100

[0142] Table 1 shows the concealment rate of the red panels.

[0143] [Table 1]

[0144]

[0145] As shown in Table 1, in the menstrual sanitary napkin of Experimental Example 1, the contact angle of the middle sheet is larger than that of the front sheet, thus improving liquid permeability compared to the menstrual sanitary napkin of Experimental Example 2. Furthermore, the content of inorganic filler in the middle sheet of Experimental Example 1 is higher than that of Experimental Example 2, thereby improving the concealment rate of the red plate.

[0146] That is, based on the comparison of the results of Experiment 1 and Experiment 2, it can be determined that: by making the contact angle of the constituent fibers of the intermediate sheet larger than that of the front sheet, the liquid permeability can be improved; and by making the content of inorganic filler in the constituent fibers of the intermediate sheet higher than that of the front sheet, the concealment rate of the red plate can be improved.

[0147] Furthermore, based on the comparison of the results of Experiment 1 and Experiment 3, it can be determined that by making the area ratio of the embossed part of the middle sheet larger than that of the front sheet, the liquid permeability can be further improved.

[0148] [Industrial Applicability]

[0149] The absorbent article according to the present invention enables liquid to be rapidly transferred from the front sheet to the absorbent, and makes it less likely for liquid to remain on the front sheet.

Claims

1. An absorbent article having a liquid-permeable front sheet, a back sheet, and an absorbent body located between the front sheet and the back sheet, and having a length direction corresponding to the wearer's front-back direction and a width direction orthogonal to the length direction, characterized in that: The front panel includes an upper layer disposed on the skin-contacting side and a lower layer disposed on the non-skin-contacting side. The upper layer contains a variety of fibers with different contact angles with water. The contact angle between the fibers constituting the upper layer and water is larger than the contact angle between the fibers constituting the lower layer and water. The front panel has embossed portions that bond the upper and lower layers together. The embossed portion has a straight first fixing portion and a straight second fixing portion that is shorter in length than the first fixing portion. The embossed portion forms a first row of fixing portions and a second row of fixing portions that are inclined in opposite directions relative to each other. The first and second fixed connection rows are formed in multiple parallel configurations. The plurality of first and second fixed connection rows alternately have portions with wide and narrow intervals between adjacent fixed connection rows. Each of the first and second fixed-connection rows is formed by arranging the first and second fixed-connection portions alternately and extending in one direction. The first and second fixing parts in the first fixing part row are arranged in a manner that does not overlap with the first and second fixing parts in the second fixing part row. Between the front sheet and the absorbent body, an intermediate sheet made of non-woven fabric is disposed adjacent to the front sheet. The intermediate sheet has embossed portions, and the area ratio of the total area of ​​the embossed portions of the intermediate sheet to the overall area of ​​the intermediate sheet is greater than the area ratio of the total area of ​​the embossed portions of the front sheet to the overall area of ​​the front sheet. The contact angle between the fibers constituting the intermediate sheet and water is greater than the contact angle between the fibers constituting the front sheet and water.

2. The absorbent article as claimed in claim 1, characterized in that: The upper layer is a fiber assembly containing heat-stretchable fibers. The lower layer is a fiber assembly that does not contain heat-stretchable fibers or contains heat-stretchable fibers at a lower mass ratio than the upper layer.

3. The absorbent article as described in claim 2, characterized in that: The heat-stretchable fiber comprises a first resin component and a second resin component having a melting point or softening point lower than that of the first resin component.

4. The absorbent article as described in claim 2 or 3, characterized in that: The content of the heat-stretchable fiber in the upper layer is more than 20% by mass and less than 80% by mass in the total mass of the upper layer.

5. The absorbent article as described in any one of claims 1 to 4, characterized in that: The upper layer comprises thermally elongated fibers and non-thermally elongated thermally bonded fibers, which are various fibers with different contact angles with water. The contact angle of the heat-stretchable fiber is larger than the contact angle of the non-heat-stretchable heat-fusion fiber.

6. The absorbent article according to any one of claims 1 to 5, characterized in that: The upper layer contains at least 50% of fibers whose contact angle with water is greater than that of the fibers constituting the lower layer.

7. The absorbent article according to any one of claims 1 to 5, characterized in that: The upper layer contains more than 90% of fibers whose contact angle with water is greater than that with water of the fibers constituting the lower layer.

8. The absorbent article according to any one of claims 1 to 5, characterized in that: The contact angle between each fiber constituting the upper layer and water is greater than the contact angle between the fibers constituting the lower layer and water.

9. The absorbent article according to any one of claims 1 to 8, characterized in that: The contact angle between the fibers constituting the upper layer and water is greater than 60° and less than 95°.

10. The absorbent article according to any one of claims 1 to 9, characterized in that: The contact angle between the fibers constituting the lower layer and water is 55° or more and 90° or less.

11. The absorbent article according to any one of claims 1 to 10, characterized in that: The contact angle between the fibers constituting the intermediate sheet and water is greater than the contact angle between the fibers constituting the upper layer of the front sheet and water.

12. The absorbent article according to any one of claims 1 to 11, characterized in that: The contact angle with water increases in the order of the fibers constituting the lower layer of the front sheet, the fibers constituting the upper layer of the front sheet, and the fibers constituting the middle sheet.

13. The absorbent article according to any one of claims 1 to 12, characterized in that: The constituent fibers of the front sheet and the constituent fibers of the middle sheet each contain 0.5% to 10% by mass of inorganic filler.

14. The absorbent article according to any one of claims 1 to 13, characterized in that: The front sheet and the middle sheet are joined together by a compression portion obtained by integrally compressing the front sheet and the middle sheet or by an adhesive.

15. The absorbent article according to any one of claims 1 to 14, characterized in that: The front panel has an embossed portion that joins the upper and lower layers together. A convex portion is formed in the area surrounded by the embossed portion, and a concave portion is formed in the embossed portion, thereby forming an uneven shape on the skin-contacting side of the upper layer.

16. The absorbent article according to any one of claims 1 to 15, characterized in that: The embossed sections constituting the first and second fixed connection rows are discontinuous lines.

17. The absorbent article according to any one of claims 1 to 16, characterized in that: In the area surrounded by the first and second fixed-fitting rows, three protrusions of different sizes are formed in such a way that they protrude toward the skin-contacting side.

18. The absorbent article as claimed in claim 17, characterized in that: The three types of protrusions with different areas each have a different protrusion height.

19. The absorbent article according to any one of claims 1 to 18, characterized in that: The area containing the intersection of the first fixed part row and the second fixed part row becomes a non-joined area that is not joined by the embossed part of the front panel.

20. The absorbent article according to any one of claims 1 to 19, characterized in that: The area ratio of the embossed portion of the intermediate sheet is 15% or more and 40% or less.

21. The absorbent article according to any one of claims 1 to 20, characterized in that: The front panel has embossed portions that bond the upper and lower layers together. The difference between the area ratio of the embossed portion of the intermediate sheet and the area ratio of the embossed portion of the front sheet is more than 2 percentage points.

22. The absorbent article according to any one of claims 1 to 21, characterized in that: The front panel has embossed portions that bond the upper and lower layers together. The difference between the area ratio of the embossed portion of the intermediate sheet and the area ratio of the embossed portion of the front sheet is more than 2 percentage points and less than 40 percentage points.

23. The absorbent article according to any one of claims 1 to 22, characterized in that: The front panel has embossed portions that bond the upper and lower layers together. The area ratio of the embossed portion of the front panel is 5% or more and 13% or less.

24. The absorbent article according to any one of claims 1 to 23, characterized in that: The average fiber diameter of the fiber with the smallest average fiber diameter in the upper layer is greater than the average fiber diameter of the fiber in the lower layer.

25. The absorbent article as claimed in claim 24, characterized in that: The average fiber diameter of the smallest fiber in the upper layer is above 2.0 dtex and below 8.0 dtex.

26. The absorbent article as claimed in claim 24 or 25, characterized in that: The average fiber diameter of the lower layer fibers is above 1.0 dtex and below 5.0 dtex.

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