Absorbent article and method for manufacturing same

Abstract

Provided is an absorbent article that includes an absorber containing an absorbent core enclosed in a core wrap sheet of crepe paper, and that makes it possible to achieve both improvement of rewet by increasing liquid diffusibility in a plane direction in the core wrap sheet and suppression of breakage of the core wrap sheet. The absorbent article (1) is provided with an absorber 11. The absorber includes an absorbent core (11a), a skin-side core wrap sheet (11b1) positioned on the skin side in the thickness direction of the absorbent core, and a non-skin-side core wrap sheet (11b2) positioned on the non-skin side in the thickness direction of the absorbent core. The skin-side core wrap sheet and the non-skin-side core wrap sheet are composed of crepe paper having unevenness. The degree of unevenness of the skin-side core wrap sheet is smaller than the degree of unevenness of the non-skin-side core wrap sheet.

Description

Absorbent article and manufacturing method thereof

[0001] The present invention relates to an absorbent article and a method for manufacturing the same.

[0002] Absorbent articles are known that include an absorbent body containing an absorbent core wrapped in a core wrap sheet of crepe paper. For example, Patent Document 1 discloses an absorbent article having a longitudinally elongated absorbent body including an absorbent core containing a water-absorbent polymer, an inner sheet disposed on the skin-facing side of the absorbent core, and an outer sheet that entirely wraps the absorbent core on which the inner sheet is disposed. The outer sheet and the inner sheet each carry the same type of functional particles. The outer sheet has a liquid permeation rate faster than that of the inner sheet. The outer sheet has a crepe rate greater than that of the inner sheet.

[0003] JP 2014-68680 A

[0004] In Patent Document 1, the absorbent core is entirely wrapped in an outer sheet, which is a core-wrap sheet. However, the outer sheet has a high crepe ratio, i.e., a high degree of unevenness (number and / or size of wrinkles). Therefore, the outer sheet tends to have low diffusibility of body fluids in the planar direction (hereinafter simply referred to as "liquid diffusibility"). In this case, body fluids that reach the outer sheet from the topsheet tend to transfer directly to the absorbent core. This tends to concentrate the absorption of body fluids in the absorbent core in a relatively small area of ​​the absorbent body in a planar view. As a result, the absorbent article may be prone to rewetting after absorbing body fluids.

[0005] One possible way to improve liquid dispersibility and suppress rewetting is to reduce the crepe ratio of the outer sheet, i.e., to reduce the degree of unevenness. However, reducing the degree of unevenness makes the outer sheet less likely to deform. Therefore, there is a risk that the outer sheet will break when subjected to external forces applied to the absorbent article in response to the wearer's movements during use.

[0006] Therefore, the object of the present invention is to provide an absorbent article and a manufacturing method thereof that has an absorbent body including an absorbent core wrapped in a crepe paper core wrap sheet, and that can achieve both improved rewetting by improving the liquid diffusion in the planar direction in the core wrap sheet and suppression of breakage of the core wrap sheet.

[0007] One aspect of the present invention is an absorbent article having a longitudinal direction, a width direction and a thickness direction which are perpendicular to each other, and comprising a top sheet, a back sheet and an absorbent body located between the top sheet and the back sheet, wherein the absorbent body includes an absorbent core containing pulp fibers, a skin-side core wrap sheet located on the skin side of the absorbent core in the thickness direction, and a non-skin-side core wrap sheet located on the non-skin side of the absorbent core in the thickness direction, and the skin-side core wrap sheet and the non-skin-side core wrap sheet are made of crepe paper having an uneven surface, and the degree of unevenness of the skin-side core wrap sheet is smaller than the degree of unevenness of the non-skin-side core wrap sheet.

[0008] Another aspect of the present invention is a method for manufacturing an absorbent article having a longitudinal direction, a width direction, and a thickness direction that are orthogonal to one another, the method comprising a top sheet, a back sheet, and an absorbent body located between the top sheet and the back sheet, the absorbent body including an absorbent core containing pulp fibers, a skin-side core wrap sheet located on the skin side of the absorbent core in the thickness direction, and a non-skin-side core wrap sheet located on the non-skin side of the absorbent core in the thickness direction. The method comprises the steps of: a continuous top sheet in which the top sheet is continuous; a continuous skin-side core wrap sheet in which the skin-side core wrap sheet is continuous and formed of crepe paper having an uneven surface; a continuous non-skin-side core wrap sheet in which the non-skin-side core wrap sheet is continuous and formed of crepe paper having an uneven surface; a plurality of the absorbent cores; and a continuous back sheet in which the back sheet is continuous. and a forming step of forming a laminate in which the top sheet portion of the continuous top sheet, the skin side core wrap sheet portion of the continuous skin side core wrap sheet, the absorbent core, the non-skin side core wrap sheet portion of the continuous non-skin side core wrap sheet, and the back sheet portion of the continuous back sheet are stacked in this order, wherein the forming step includes a coating step of applying a composition containing a hydrophilic solvent to at least one of the top sheet portion of the continuous top sheet and the skin side core wrap sheet portion of the continuous skin side core wrap sheet, and wherein the degree of unevenness of the skin side core wrap sheet portion of the continuous skin side core wrap sheet after the forming step is smaller than the degree of unevenness of the non-skin side core wrap sheet portion of the continuous non-skin side core wrap sheet.

[0009] According to the present invention, an absorbent article and a manufacturing method thereof can be provided, which has an absorbent body including an absorbent core wrapped in a crepe paper core wrap sheet, and which can achieve both improved rewetting by improving the liquid diffusion in the planar direction in the core wrap sheet and suppression of breakage of the core wrap sheet.

[0010] Fig. 1 is a plan view in an unfolded state showing an example of the configuration of a disposable diaper according to an embodiment. Fig. 2 is a bottom view in an unfolded state showing an example of the configuration of a disposable diaper according to an embodiment. Fig. 3 is a cross-sectional view taken along the line CW-CW in Fig. 1. Fig. 4 is a plan view showing an example of the configuration of an absorbent body according to an embodiment. Fig. 5 is a schematic view showing an example of a method for manufacturing an absorbent article according to an embodiment.

[0011] The present disclosure relates to the following aspects: [Aspect 1] An absorbent article having a longitudinal direction, a width direction, and a thickness direction that are perpendicular to one another, and comprising a topsheet, a backsheet, and an absorbent body located between the topsheet and the backsheet, wherein the absorbent body includes an absorbent core containing pulp fibers, a skin-side core wrap sheet located on the skin side of the absorbent core in the thickness direction, and a non-skin-side core wrap sheet located on the non-skin side of the absorbent core in the thickness direction, the skin-side core wrap sheet and the non-skin-side core wrap sheet being made of crepe paper having an uneven surface, and the unevenness of the skin-side core wrap sheet is smaller than the unevenness of the non-skin-side core wrap sheet.

[0012] In this absorbent article, the unevenness (number and / or size of wrinkles) of the skin-side core wrap sheet, which is made of uneven crepe paper, is smaller than the unevenness of the non-skin-side core wrap sheet. That is, in this absorbent article, the unevenness of the skin-side core wrap sheet is relatively small. This improves the liquid diffusibility in the planar direction of the skin-side core wrap sheet and also increases the contact area between the topsheet and the skin-side core wrap sheet and the contact area between the skin-side core wrap sheet and the absorbent core. Therefore, during use, body fluid (including sweat) released into the absorbent article and transferred from the topsheet to the skin-side core wrap sheet can be diffused in the planar direction of the skin-side core wrap sheet and then transferred to the absorbent core. Therefore, body fluid can be absorbed over a very wide area within the absorbent core, thereby reducing the amount of body fluid absorbed per unit area in a planar view of the absorbent core. This makes the absorbent article less susceptible to rewetting after absorbing body fluid. On the other hand, by relatively increasing the degree of unevenness of the non-skin-side core wrap sheet made of crepe paper, the non-skin-side core wrap sheet can be made more easily deformed. As a result, even if the absorbent article expands and contracts due to the wearer's body movements during use, the non-skin-side core wrap sheet can follow the expansion and contraction, thereby preventing breakage. In this case, the unevenness of the non-skin-side core wrap sheet absorbs the external force caused by the body movements, reducing the external force acting on the skin-side core wrap sheet (which has a small degree of unevenness and cannot be said to tolerate a large external force), thereby preventing breakage of the skin-side core wrap sheet. In this way, an absorbent article having an absorbent body including an absorbent core wrapped in a crepe paper core wrap sheet can achieve both improved rewet by improving the liquid diffusibility in the planar direction of the skin-side core wrap sheet and preventing breakage of the core wrap sheet.

[0013] [Aspect 2] The absorbent article according to aspect 1, wherein the skin side core wrap sheet comprises fibers constituting the skin side core wrap sheet and a composition containing a hydrophilic solvent carried by the fibers.

[0014] In this absorbent article, the fibers constituting the skin-side core wrap sheet are supported with a composition containing a hydrophilic solvent (which can be water), and the hydrophilic solvent makes the fibers more compatible with body fluids. Therefore, during use, body fluid released into the absorbent article and transferred from the top sheet to the skin-side core wrap sheet can be more easily diffused in the planar direction of the skin-side core wrap sheet. In other words, the liquid diffusibility in the planar direction of the skin-side core wrap sheet can be further improved. This can further suppress rewetting of the absorbent article.

[0015] [Aspect 3] The absorbent article of aspect 2, wherein the composition further comprises a hydrophilic antimicrobial agent.

[0016] In this absorbent article, the fibers constituting the skin-side core wrap sheet are loaded with a composition further containing a hydrophilic antibacterial agent. The effect of the hydrophilic antibacterial agent makes the fibers more compatible with body fluids. Therefore, during use, body fluid released into the absorbent article and transferred from the top sheet to the skin-side core wrap sheet can be more easily diffused in the planar direction of the skin-side core wrap sheet. In other words, the liquid diffusibility in the planar direction of the skin-side core wrap sheet can be further improved. This can further suppress rewetting of the absorbent article. Furthermore, the antibacterial agent can impart antibacterial properties to body fluids transferring from the top sheet to the absorbent body.

[0017] [Aspect 4] The absorbent article according to aspect 3, wherein the solvent includes a non-volatile organic substance.

[0018] In this absorbent article, the fibers constituting the skin-side core wrap sheet are supported with a solvent containing a hydrophilic, non-volatile organic substance. The hydrophilic, non-volatile organic substance allows for stable and continuous compatibility between body fluids and the fibers. Therefore, during use, body fluids released into the absorbent article and transferred from the top sheet to the skin-side core wrap sheet can be more easily diffused in the planar direction of the skin-side core wrap sheet. In other words, the liquid diffusibility in the planar direction of the skin-side core wrap sheet can be further improved. This further reduces rewetting of the absorbent article. Furthermore, since the hydrophilic, non-volatile organic substance is less likely to volatilize, irritation to the skin can be reduced.

[0019] [Aspect 5] The absorbent article according to any one of aspects 1 to 4, wherein the degree of unevenness in the center of the longitudinal direction and the center of the width direction of the skin-side core wrap sheet is smaller than the degree of unevenness at both ends of the longitudinal direction and both ends of the width direction.

[0020] In this absorbent article, the skin-side core wrap sheet has a relatively small degree of unevenness in the longitudinal center and width center, i.e., the region where body fluid is excreted (hereinafter also referred to as the "excretory outlet contact region"). This allows the planar liquid diffusibility of the skin-side core wrap sheet in the excretory outlet contact region to be relatively increased. This allows the skin-side core wrap sheet to quickly diffuse body fluid released into the excretory outlet contact region in the planar direction and then transfer it to the absorbent core during use. This allows body fluid to be absorbed over a very wide area within the absorbent body, thereby making the absorbent article less susceptible to rewetting. Furthermore, the skin-side core wrap sheet has a relatively large degree of unevenness at both longitudinal and widthwise ends, i.e., the end regions of the absorbent body (hereinafter also referred to as the "end regions"). This allows the planar liquid diffusibility of the skin-side core wrap sheet in the end regions to be relatively reduced. This makes it possible to suppress the diffusion of bodily fluids that have diffused outward from the excretory opening contact area in the edge regions during use, thereby suppressing leakage of bodily fluids out of the absorbent article in the edge regions during use.

[0021] [Aspect 6] The absorbent article according to any one of Aspects 1 to 5, wherein the degree of unevenness of the skin side core wrap sheet is smaller than the degree of unevenness of the skin side of the topsheet.

[0022] In this absorbent article, the unevenness of the skin-side core wrap sheet is smaller than the unevenness of the skin-side of the topsheet, which allows the skin-side core wrap sheet to easily contact the topsheet. This allows bodily fluid released onto the topsheet during use to quickly transfer from the topsheet to the skin-side core wrap sheet, where it is dispersed in the planar direction by the skin-side core wrap sheet and then transferred to the absorbent core. Furthermore, by relatively increasing the unevenness of the skin-side of the topsheet, bodily fluid absorbed into the absorbent core is less likely to come into contact with the wearer's skin through the topsheet, making rewetting less likely.

[0023] [Aspect 7] An absorbent article according to any one of aspects 1 to 6, wherein the crepe paper in the skin-side core wrap sheet and the non-skin-side core wrap sheet has a concave surface on the side opposite to the convex portion of the unevenness, and the concave portion encompasses a portion of the pulp fibers of the absorbent core.

[0024] In this absorbent article, the crepe paper in the skin-side core wrap sheet includes a portion of the pulp fibers of the absorbent core in the concave portion on the surface opposite the convex portion. This increases the contact area between the skin-side core wrap sheet and the absorbent core. This allows body fluids discharged into the absorbent article to be quickly transferred from the skin-side core wrap sheet to the absorbent core during use. Furthermore, the crepe paper in the non-skin-side core wrap sheet includes a portion of the pulp fibers of the absorbent core in the concave portion on the surface opposite the convex portion. This facilitates the diffusion of body fluids that have not been absorbed by the absorbent core in the planar direction, allowing them to be absorbed by the absorbent core at the longitudinal and / or widthwise end portions. Furthermore, by including the pulp fibers in the concave portion on the surface opposite the convex portion, excessive deformation of the skin-side core wrap sheet and the non-skin-side core wrap sheet, which would otherwise result in a reduction in absorption performance, can be prevented.

[0025] [Aspect 8] The absorbent article according to any one of Aspects 1 to 7, further comprising a non-skin-side elastic member extending along the longitudinal direction at a position overlapping the absorbent body in the thickness direction and on the non-skin side of the absorbent body in the thickness direction.

[0026] This absorbent article includes a non-skin-side elastic member extending longitudinally at a position overlapping the absorbent body in the thickness direction and closer to the skin than the absorbent body in the thickness direction, making it easier to press the skin-side portion of the absorbent body against the body. This allows body fluids released into the absorbent article to be transferred more quickly from the topsheet to the absorbent body during use. Furthermore, the non-skin-side elastic member can reinforce the non-skin-side core wrap sheet, further reducing breakage of the non-skin-side core wrap sheet.

[0027] [Aspect 9] The absorbent article of Aspect 8, further comprising a pair of leak-proof walls located on both sides of the topsheet in the width direction and extending along the longitudinal direction, each of the pair of leak-proof walls including a leak-proof elastic member extending along the longitudinal direction, the contractile force per unit length of the leak-proof elastic member being smaller than the contractile force per unit length of the non-skin-side elastic member.

[0028] In this absorbent article, a pair of leak-barrier walls located on both sides of the topsheet in the width direction and extending along the longitudinal direction each further comprise a leak-proof elastic member extending along the longitudinal direction, thereby preventing side leakage of body fluids in the width direction. In addition, the non-skin-side elastic member, which has a greater contractile force per unit length than the leak-proof elastic member, is provided on the non-skin side, making it easier to press the skin-side portion of the absorbent body against the body. This prevents side leakage of body fluids released into the absorbent article during use, while allowing the body fluids to be transferred more quickly from the topsheet to the absorbent body.

[0029] [Aspect 10] An absorbent article described in any one of aspects 1 to 9, having a pair of embossed portions formed in a groove shape extending from the surface of the top sheet toward the absorbent body and extending along the longitudinal direction, wherein the degree of unevenness of the skin-side core wrap sheet in the area between the pair of embossed portions is smaller than the degree of unevenness of the skin-side core wrap sheet in areas located outside each of the pair of embossed portions in the width direction.

[0030] This absorbent article has a pair of embossed portions extending along the longitudinal direction, and the unevenness of the skin-side core wrap sheet in the region between the pair of embossed portions (hereinafter also referred to as the "inner region") is relatively small. This allows the skin-side core wrap sheet to have relatively high planar liquid diffusibility in the inner region. This allows the skin-side core wrap sheet to more quickly diffuse body fluid released into the inner region in the planar direction and transfer it to the absorbent core during use. This allows body fluid to be absorbed over a very wide area within the absorbent, thereby making the absorbent article less susceptible to rewetting. Furthermore, the unevenness of the skin-side core wrap sheet in regions located widthwise outward of each of the pair of embossed portions (hereinafter also referred to as the "outer region") is relatively large. This allows the skin-side core wrap sheet to have relatively low planar liquid diffusibility in the outer region. This allows body fluid that has diffused from the inner region outward (over the embossed portions) to be suppressed in the outer region during use, while allowing the body fluid to transfer to the absorbent core. Therefore, when in use, leakage of bodily fluids out of the absorbent article can be suppressed in the outer region.

[0031] [Aspect 11] A method for manufacturing an absorbent article having a longitudinal direction, a width direction, and a thickness direction that are orthogonal to one another, the method comprising: a topsheet; a backsheet; and an absorbent body located between the topsheet and the backsheet, the absorbent body including an absorbent core containing pulp fibers; a skin-side core wrap sheet located on the skin side of the absorbent core in the thickness direction; and a non-skin-side core wrap sheet located on the non-skin side of the absorbent core in the thickness direction. The method comprises preparing a continuous topsheet, a continuous skin-side core wrap sheet, a continuous non-skin-side core wrap sheet, a continuous non-skin-side core wrap sheet, a continuous non-skin-side core wrap sheet, a plurality of the absorbent cores, and a continuous backsheet, the method comprising the steps of: and a forming step of forming a laminate in which the top sheet portion of the continuous top sheet, the skin side core wrap sheet portion of the continuous skin side core wrap sheet, the absorbent core, the non-skin side core wrap sheet portion of the continuous non-skin side core wrap sheet, and the back sheet portion of the continuous back sheet are stacked in this order, wherein the forming step includes a coating step of applying a composition containing a hydrophilic solvent to at least one of the top sheet portion of the continuous top sheet and the skin side core wrap sheet portion of the continuous skin side core wrap sheet, and the degree of unevenness of the skin side core wrap sheet portion of the continuous skin side core wrap sheet after the forming step is smaller than the degree of unevenness of the non-skin side core wrap sheet portion of the continuous non-skin side core wrap sheet.

[0032] In this absorbent article manufacturing method, the unevenness of the skin-side core wrap sheet can be relatively reduced by applying a composition to the topsheet and transferring it to the skin-side core wrap sheet in contact with the topsheet, or by applying a composition to the skin-side core wrap sheet. This increases the contact area between the topsheet and the skin-side core wrap sheet, thereby improving the stability of the bond between the topsheet and the skin-side core wrap sheet. Furthermore, because the unevenness of the skin-side core wrap sheet of the manufactured absorbent article is relatively small, during use, body fluid (including sweat) released into the absorbent article and transferred from the topsheet to the skin-side core wrap sheet can be diffused in the planar direction of the skin-side core wrap sheet and then transferred to the absorbent core. Therefore, body fluid can be absorbed over a very wide area within the absorbent core, reducing the amount of body fluid absorbed per unit area in a planar view of the absorbent core. This makes the absorbent article less susceptible to rewetting after absorbing body fluid. In addition, by relatively increasing the degree of unevenness of the non-skin side core wrap sheet of crepe paper, the non-skin side core wrap sheet can be made easier to deform, thereby preventing the non-skin side core wrap sheet or the skin side core wrap sheet from breaking during use.

[0033] [Embodiment 12] A method as described in embodiment 11, wherein in the application step, the composition is applied only to the central portion of the continuous top sheet in the longitudinal direction and the width direction of the top sheet portion, and only to the central portion of the continuous skin side core wrap sheet in the longitudinal direction and the width direction of the skin side core wrap sheet portion.

[0034] In this absorbent article manufacturing method, the composition is applied to the longitudinal and widthwise central portions of the top sheet or skin-side core wrap sheet, i.e., the excretory opening contact area. This allows the degree of unevenness in the skin-side core wrap sheet to be relatively small. Therefore, the contact area between the top sheet and the skin-side core wrap sheet in the excretory opening contact area can be increased. This further increases the stability of the bond between the top sheet and the skin-side core wrap sheet in the excretory opening contact area. Furthermore, the composition is not applied to the ends of the top sheet or skin-side core wrap sheet other than the longitudinal and widthwise central portions. In this way, by not applying the composition to the longitudinal and widthwise ends, where the adhesive is primarily disposed when bonding sheets together, the adhesive can function properly at the ends. This prevents problems such as the adhesive not functioning properly during transport, causing sheets at the ends of the absorbent article to turn up.

[0035] [Aspect 13] The method according to Aspect 11 or 12, wherein in the application step, the composition is applied, in a plan view, only to the area of ​​the continuous top sheet where the absorbent core is disposed, and only to the area of ​​the continuous skin-side core wrap sheet where the absorbent core is disposed.

[0036] In this method for manufacturing an absorbent article, the composition is applied only to the area of ​​the top sheet or skin-side core wrap sheet where the absorbent core is located in a plan view. By limiting the area to which the composition is applied in this way, even if the skin-side core wrap sheet is joined to the non-skin-side core wrap sheet outside the area where the absorbent core is located, it is possible to prevent the composition from diffusing from the skin-side core wrap sheet to the non-skin-side core wrap sheet. This prevents the degree of unevenness of the non-skin-side core wrap sheet from decreasing and the adhesive from becoming difficult to function when joining the sheets together.

[0037] [Aspect 14] The method according to any one of Aspects 11 to 13, wherein the composition further comprises a hydrophilic antibacterial agent, the solvent comprises water and an organic solvent, and the amount of water in the solvent is less than the amount of the organic solvent.

[0038] In the method for manufacturing an absorbent article, the composition further contains a hydrophilic antibacterial agent, and the solvent contains water and an organic solvent, with the amount of water being less than the amount of the organic solvent. By reducing the water content in the composition, rusting in the manufacturing equipment can be suppressed. Meanwhile, by increasing the organic solvent content in the composition, the antibacterial agent itself can be prevented from being exposed on the surface of the topsheet, which can cause irritation to the wearer's skin.

[0039] The absorbent article and the manufacturing method thereof according to the embodiment will be described below using a pants-type disposable diaper (hereinafter simply referred to as a "disposable diaper") as an example of the absorbent article. However, the type of absorbent article is not limited to this example, and other types of absorbent articles may be used as long as they do not deviate from the scope of the present invention. Examples of such absorbent articles include tape-type diapers, incontinence pads, sanitary napkins, and panty liners.

[0040] First, an absorbent article according to an embodiment will be described. Figures 1 to 4 are diagrams showing an example of the configuration of a disposable diaper 1 according to an embodiment. Figures 1 and 2 are a plan view and a bottom view, respectively, of a disposable diaper in an unfolded state, showing an example of the configuration of the disposable diaper according to an embodiment. Figure 3 is a schematic cross-sectional view taken along line CW-CW in Figure 1. Figure 4 is a plan view showing an example of the configuration of an absorber according to an embodiment.

[0041] In the unfolded state shown in Fig. 1 , the disposable diaper 1 has a longitudinal direction L, a width direction W, and a thickness direction T that are perpendicular to each other, and has a longitudinal centerline CL that passes through the center of the width direction W and extends in the longitudinal direction L, and a widthwise centerline CW that passes through the center of the longitudinal direction L and extends in the width direction W. Here, the directions and sides approaching the longitudinal centerline CL are referred to as the inward and inner sides in the width direction W, respectively, and the directions and sides moving away from the longitudinal centerline CL are referred to as the outward and outer sides in the width direction W, respectively. Meanwhile, the directions and sides approaching the widthwise centerline CW are referred to as the inward and inner sides in the longitudinal direction L, respectively, and the directions and sides moving away from the widthwise centerline CW are referred to as the outward and outer sides in the longitudinal direction L, respectively. In addition, the side in the longitudinal direction L facing the edge of the disposable diaper 1 corresponding to the wearer's abdomen (the abdominal edge) is also referred to as the front side in the longitudinal direction L, and the side facing the edge of the disposable diaper 1 corresponding to the wearer's back (the dorsal edge) is also referred to as the rear side in the longitudinal direction L. Furthermore, "plan view" refers to the disposable diaper 1 unfolded on a plane including the longitudinal direction L and the width direction W, viewed from above in the thickness direction T, and "planar shape" refers to the shape as perceived in a planar view. "Planar direction" refers to any direction parallel to a plane including the width direction W and the longitudinal direction L. "Skin side" and "non-skin side" refer to the side that is relatively closer to and farther from the wearer's skin surface in the thickness direction T when the disposable diaper 1 is worn by a wearer. "A direction along the longitudinal direction L" is not limited to being parallel to the longitudinal direction L, but also includes a range of ±30° with respect to the longitudinal direction L. "A direction along the width direction W" is not limited to being parallel to the width direction W, but also includes a range of ±30° with respect to the width direction W. These definitions are used not only for the disposable diaper 1 but also for the absorbent body of the disposable diaper 1 and the various materials disposed therein.

[0042] 1 , the disposable diaper 1 includes, in the longitudinal direction L, a ventral section (ventral waist belt) 2 located at the front, a dorsal section (dorsal waist belt) 3 located at the rear, and an absorbent main body 10 located between the ventral section 2 and the dorsal section 3. In this embodiment, the ventral section 2 has a generally rectangular shape extending in the width direction W, the dorsal section 3 also has a generally rectangular shape extending in the width direction W but with a front portion in the longitudinal direction L extending forward, and the absorbent main body 10 has a generally rectangular shape extending in the longitudinal direction L.

[0043] The abdominal portion 2 is a portion that contacts the wearer's abdomen. The back portion 3 is a portion that contacts the wearer's buttocks or back. The absorbent main body 10 is a portion that contacts the wearer's crotch (excretory opening). One end of the absorbent main body 10 in the longitudinal direction L is layered and joined to the skin-side surface of the abdominal portion 2, and the other end is layered and joined to the skin-side surface of the back portion 3. Both end portions 2a, 2a in the width direction W of the abdominal portion 2 and both end portions 3a, 3a in the width direction W of the back portion 3 are layered in the thickness direction T and joined along the longitudinal direction L to form the disposable diaper 1. In this case, in the disposable diaper 1, the outer end portions of the abdominal portion 2 in the longitudinal direction L and the outer end portions of the back portion 3 in the longitudinal direction L define a waist opening through which the wearer's waist passes. In addition, in the disposable diaper 1, a pair of leg openings through which the wearer's pair of legs pass are defined by both ends in the width direction W of the absorbent body 10, the inner end in the longitudinal direction L of the ventral portion 2, and the inner end in the longitudinal direction L of the dorsal portion 3.

[0044] In this embodiment, in the state shown in Fig. 1 , the abdominal portion 2 and the back portion 3 are spaced apart from each other in the longitudinal direction L. That is, the abdominal portion 2 and the back portion 3 are formed separately from each other. In another embodiment, the disposable diaper 1 further includes a crotch portion located between the abdominal portion 2 and the back portion 3, one end of which is connected to the abdominal portion 2 and the other end of which is connected to the back portion 3. In this case, the abdominal portion 2, the back portion 3, and the crotch portion may be formed integrally with or separately from each other.

[0045] In this embodiment, the ventral portion 2 includes liquid-impermeable cover sheets 21, 22, and 24. The cover sheet 21 is located on the skin side, and the cover sheet 22 is located on the non-skin side. The cover sheets 21 and 22 are laminated in the thickness direction T and joined to each other by adhesive or heat fusion. The cover sheet 24 is laminated on the cover sheet 21 so as to cover the front end of the absorbent main body 10 in the longitudinal direction L from the skin side. Similarly, in this embodiment, the back portion 3 includes liquid-impermeable cover sheets 31, 32, and 34. The cover sheet 31 is located on the skin side, and the cover sheet 32 ​​is located on the non-skin side. The cover sheets 31 and 32 are laminated in the thickness direction T and joined to each other by adhesive or heat fusion. The cover sheet 34 is laminated on the cover sheet 31 so as to cover the rear end of the absorbent main body 10 in the longitudinal direction L from the skin side. Examples of materials for each cover sheet include liquid-impermeable nonwoven fabrics and synthetic resin films. The types of liquid-impermeable nonwoven fabrics and synthetic resin films and their materials will be described later. At least one of the cover sheets 24, 34 may be omitted. Each cover sheet may be made up of multiple sheets.

[0046] In this embodiment, the abdominal portion 2 includes a plurality of elastic members 23 for waist gathering between the cover sheets 21 and 22. The plurality of elastic members 23 extend along the width direction W, are arranged in the abdominal portion 2 at intervals in the longitudinal direction L, and are joined to the cover sheets 21 and 22 by adhesive or heat fusion. Note that the elastic members 23 do not have to be arranged in the region of the abdominal portion 2 that is located on the non-skin side of the absorbent main body 10. Similarly, in this embodiment, the back portion 3 includes a plurality of elastic members 33 for waist gathering between the cover sheets 31 and 32. The plurality of elastic members 33 extend along the width direction W, are arranged in the back portion 3 at intervals in the longitudinal direction L, and are joined to the cover sheets 31 and 32 by adhesive or heat fusion. Note that the elastic members 33 do not have to be arranged in the region of the back portion 3 that is located on the non-skin side of the absorbent main body 10. In this embodiment, the back portion 3 further includes a plurality of elastic members 35 for leg gathers between the cover sheets 31 and 32. The plurality of elastic members 35 are arranged inward in the longitudinal direction L from the elastic members 33 so as to be convex toward the stomach portion 2 in a plan view. An example of the material for each elastic member is rubber thread.

[0047] In this embodiment, the absorbent body 10 includes a liquid-permeable topsheet 12, a liquid-impermeable backsheet 13, and an absorbent body 11 located between the topsheet 12 and the backsheet 13 and absorbing and retaining liquid. Examples of materials for the topsheet 12 include liquid-permeable nonwoven fabrics or woven fabrics, synthetic resin films with liquid-permeable holes formed therein, and combinations of the same or different types thereof. Examples of materials for the backsheet 13 include liquid-impermeable but breathable nonwoven fabrics, synthetic resin films with air vents formed therein, and combinations of the same or different types thereof. A liquid-permeable diffusion sheet located between the topsheet 12 and the absorbent body 11 that diffuses liquid in the planar direction may also be provided.

[0048] Examples of the surface sheet 12 include a flat sheet without any irregularities, a sheet extending in the longitudinal direction L and having a plurality of convex portions spaced apart in the width direction W and a plurality of concave portions provided between each of the plurality of convex portions, and a sheet having a plurality of convex portions that are approximately circular in plan view and arranged in a checkerboard pattern in plan view.

[0049] The type of liquid-permeable or liquid-impermeable nonwoven fabric is not particularly limited as long as it can be used for absorbent articles, and examples thereof include meltblown nonwoven fabrics, spunbond nonwoven fabrics, airlaid nonwoven fabrics, and air-through nonwoven fabrics. The material of the nonwoven fabric is not particularly limited as long as it can be used for absorbent articles, and examples thereof include synthetic resin fibers and pulp fibers. The synthetic resin is not particularly limited as long as it can be used for absorbent articles, and examples thereof include olefin-based resins such as polyethylene and polypropylene, polyamide-based resins such as 6-nylon and 6,6-nylon, and polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate. Pulp fibers will be described later. The type of liquid-permeable or liquid-impermeable synthetic resin film is not particularly limited as long as it can be used for absorbent articles, and examples thereof include known film materials. The material of the synthetic resin film is not particularly limited as long as it can be used for absorbent articles, and examples thereof include the synthetic resins described above.

[0050] The absorbent body 11 includes an absorbent core 11a that absorbs and retains liquid and a core wrap sheet 11b that encases the absorbent core 11a. Materials for the absorbent core 11a include absorbent materials, such as pulp fibers and superabsorbent polymers. Examples of pulp fibers include cellulosic fibers. Examples of cellulosic fibers include wood pulp, crosslinked pulp, non-wood pulp, regenerated cellulose, and semi-synthetic cellulose. Examples of superabsorbent polymers (SAPs) include polyacrylate-based, polysulfonate-based, and maleic anhydride-based water-absorbing polymers. Examples of materials for the core wrap sheet 11b include liquid-permeable nonwoven fabrics (including tissues) made of synthetic resin fibers or pulp fibers, and composite sheets thereof. The type of synthetic resin fiber is not particularly limited as long as it can be used in absorbent articles, and examples include known synthetic fibers. The types of nonwoven fabric, synthetic resin, and pulp fiber are as described above. Details of the absorbent body 11 will be described later.

[0051] The absorbent body 11 and the topsheet 12, and the absorbent body 11 and the backsheet 13 are each bonded to each other with an adhesive. The topsheet 12 and the backsheet 13 are bonded to each other at their peripheral portions with an adhesive. The adhesive may be, for example, a hot melt adhesive. The shape of the absorbent main body 10 is not limited to the above example as long as it is long in the longitudinal direction L, and may be, for example, a rectangle with rounded corners, a rectangle with outwardly convex curved short sides, or an hourglass shape.

[0052] The basis weights of the top sheet 12, back sheet 13, and absorbent body 11 are adjusted appropriately depending on the absorption performance required for the disposable diaper 1, but are not particularly limited as long as they can be used as sheets for the disposable diaper 1. The basis weight of the top sheet 12 is, for example, 5 to 200 g / m ２ The basis weight of the back sheet 13 is, for example, 5 to 200 g / m ２ The basis weight of the absorbent core 11a is, for example, 10 to 2000 g / m ２ The basis weight of the core wrap sheet 11b is, for example, 5 to 100 g / m ２Examples include:

[0053] The average fiber diameter (diameter) of the fibers constituting the core wrap sheet 11b is not particularly limited as long as it can be used as each sheet of the disposable diaper 1. Examples of the average fiber diameter of these fibers include 5 to 100 μm, and preferably 10 to 50 μm. By setting the average fiber diameter to 5 μm or more, the fibers do not become too thin, and for example, it is possible to make it difficult for a liquid composition applied to the core wrap sheet 11b to move vertically downward (or fall) from the fibers due to gravity. By setting the average fiber diameter to 100 μm or less, the fibers do not become too thick, and for example, it is possible to increase the surface area per volume of the fibers, making it easier to hold a large amount of liquid composition.

[0054] In this embodiment, the absorbent body 10 further includes an exterior sheet 14 laminated on the non-skin side of the backsheet 13. Both side portions of the exterior sheet 14 in the width direction W wrap around to the skin side of the laminate of the topsheet 12, absorber 11, and backsheet 13 to form a pair of leak barrier walls 15 extending in the longitudinal direction L. Each leak barrier wall 15 has its outer edge in the width direction W fixed to the edge of the absorbent body 10 in the width direction W, and its inner edge in the width direction W left unfixed. Both ends of the leak barrier walls 15 in the longitudinal direction L are covered and fixed by cover sheets 24 and 34. Examples of materials for the exterior sheet 14 and the leak barrier walls 15 include hydrophobic sheets such as hydrophobic nonwoven fabrics. In another embodiment, examples of materials for the exterior sheet 14 and the leak barrier walls 15 include hydrophilic sheets such as hydrophilic nonwoven fabrics. Each leak preventing wall 15 includes, at its inner end in the width direction W, two leak preventing elastic members 16 extending along the longitudinal direction L. The leak preventing elastic members 16 are exemplified by rubber threads. In another embodiment, each of the pair of leak preventing walls 15 has its inner end in the width direction W folded back further outward in the width direction W. In another embodiment, the number of leak preventing elastic members 16 is one, or three or more.

[0055] In this embodiment, the absorbent main body 10 further includes one or more non-skin-side elastic members 17 and one or more non-skin-side elastic members 18 between the backsheet 13 and the outer sheet 14, at a position overlapping the absorbent body 11 in the thickness direction T. The non-skin-side elastic members 17 extend along the longitudinal direction L at each of both end portions of the absorbent main body 10 in the width direction W. The non-skin-side elastic members 17 are used for leg gathers. Meanwhile, the non-skin-side elastic members 18 extend along the longitudinal direction L at the center of the absorbent main body 10 in the width direction W, from the rear end portion in the longitudinal direction L to near the center. The non-skin-side elastic members 18 are used to press the rear (back side) portion of the absorbent main body 10 in the longitudinal direction L against the wearer's buttocks or back. An example of the material for each non-skin-side elastic member is rubber thread.

[0056] Next, the absorbent body 11 will be described. The absorbent body 11 is a layer having liquid absorption and liquid retention properties. In this embodiment, the absorbent body 11 has a single-layer structure. In another embodiment, the absorbent body 11 has a two-layer structure having an upper layer and a lower layer. In this case, the lengths of the upper and lower layers in the width direction W and the longitudinal direction L may be the same or different, and the amounts and types of absorbent materials may be different. In another embodiment, the absorbent body 11 has a multi-layer structure having three or more layers.

[0057] The shape of the absorbent body 11 (and core wrap sheet 11b) in a plan view is not particularly limited as long as it is a shape extending in the longitudinal direction L. In this embodiment, the absorbent body 11 (and core wrap sheet 11b) has a rectangular shape extending in the longitudinal direction L. However, the shape is not limited to this example, and examples include a rectangle with arc-shaped short sides, a rectangle with rounded corners, an oval, and an hourglass shape. The length (thickness) of the absorbent body 11 in the thickness direction T is, for example, 0.5 to 20 mm, the length (length) in the longitudinal direction L is, for example, 15 to 40 cm, and the length (width) in the width direction W is, for example, 5 to 15 cm.

[0058] The shape of the absorbent core 11a in a plan view is not particularly limited as long as it extends in the longitudinal direction L and fits within the core wrap sheet 11b. In this embodiment, the absorbent body 11 has a generally hourglass shape with a central portion in the longitudinal direction L tapered inward. However, the shape is not limited to this example, and examples include a rectangle with arc-shaped short sides, a rectangle with rounded corners, and an ellipse.

[0059] The core wrap sheet 11b includes a skin-side core wrap sheet 11b1 arranged on the skin side of the absorbent core 11a in the thickness direction T, and a non-skin-side core wrap sheet 11b2 arranged on the non-skin side of the absorbent core 11a in the thickness direction T. In this embodiment, the skin-side core wrap sheet 11b1 and the non-skin-side core wrap sheet 11b2 are integrally formed, i.e., formed from a single sheet. Both ends in the width direction W of the single sheet are joined to each other to form a cylindrical shape, the absorbent core 11a is enclosed within it, and both ends in the longitudinal direction L are sealed to form the absorbent body 11. In this case, the skin-side core wrap sheet 11b1 is located closer to the skin side than half the dimension (thickness) of the absorbent core 11a in the thickness direction T, and the non-skin-side core wrap sheet 11b2 is located on the non-skin side. In another embodiment, the skin-side core wrap sheet 11b1 and the non-skin-side core wrap sheet 11b2 are formed separately from each other. Furthermore, in another embodiment, at least one of the skin side core wrap sheet 11b1 and the non-skin side core wrap sheet 11b2 is formed of a plurality of sheets.

[0060] The skin-side core wrap sheet 11b1 and the non-skin-side core wrap sheet 11b2 are made of crepe paper. Crepe paper is a creped nonwoven fabric (including paper) made of synthetic resin fibers, pulp fibers, or the like, and has an uneven structure with multiple wrinkled recesses and protrusions. The unevenness of the skin-side core wrap sheet 11b1 is smaller than that of the non-skin-side core wrap sheet 11b2. Here, the "unevenness" refers to the number of wrinkles (protrusions) per unit length in a direction (e.g., width direction W) perpendicular to the direction in which the wrinkles extend (e.g., longitudinal direction L) and / or the size of the wrinkles. The "unevenness size" refers to the height H and / or width D of the wrinkles, as shown in FIG. 3(b). However, the height H of the irregularities refers to the height from the bottom of the recess (the portion between adjacent protrusions 51) to the top of the protrusion 51. The width D of the irregularities refers to the distance between the tops of adjacent protrusions 51 or the distance between the bottoms of adjacent recesses. A small degree of irregularity refers to a small number of irregularities, a low height H of the irregularities, and / or a large width D of the irregularities, and does not include a case where there are no irregularities. This is to maintain a certain degree of ease of deformation on the skin side of the absorbent body 11. The method for measuring the degree of irregularity of the core wrap sheet will be described later.

[0061] The degree of unevenness of the crepe paper can be adjusted by creping conditions, applying a liquid to the crepe paper, etc. For example, when a liquid is applied to the crepe paper, the applied portion is soaked in the liquid and softens, making the unevenness more likely to collapse. This reduces the degree of unevenness. In this case, from the viewpoint of easily maintaining affinity with body fluids and the degree of unevenness, a hydrophilic and non-volatile liquid is preferably used as the liquid applied to the crepe paper.

[0062] In this embodiment, the degree of unevenness across the entire surface of the skin-side core wrap sheet 11b1 does not need to be smaller than that of the non-skin-side core wrap sheet 11b2. Examples of areas with a small degree of unevenness include, in a plan view, a central portion (equivalent to one unit) excluding both end portions (equivalent to one unit each) when the skin-side core wrap sheet 11b1 is divided into three in the width direction W, a central portion (equivalent to two units) excluding both end portions (equivalent to one unit each) when the skin-side core wrap sheet 11b1 is divided into four in the width direction W, and a central portion (equivalent to three or one unit) excluding both end portions (equivalent to one or two units each) when the skin-side core wrap sheet 11b1 is divided into five in the width direction W. And / or examples of the portions with a small degree of unevenness include, for example, the central portion (one portion) of the entire surface of the skin side core wrap sheet 11b1 when viewed in a plane, excluding both end portions (one portion each) when the skin side core wrap sheet 11b1 is divided into three portions in the longitudinal direction L, the central portion (two portions) excluding both end portions (one portion each) when the skin side core wrap sheet 11b1 is divided into four portions in the longitudinal direction L, and the central portion (three portions) excluding both end portions (one portion each) when the skin side core wrap sheet 11b1 is divided into five portions in the longitudinal direction L.

[0063] In another embodiment, the portion with the small degree of unevenness is, for example, a portion of 20% or more of the entire surface of the skin side core wrap sheet 11b1 when viewed in a plane, including the center in the longitudinal direction L and the width direction W (the intersection of the longitudinal center line CL and the width center line CW), with a portion of 40% or more being preferred, and a portion of 60% or more being more preferred.

[0064] In either case, the portion with a small degree of unevenness preferably includes an excretory outlet contact area in a plan view, and is preferably a region overlapping the absorbent core 11a. The excretory outlet contact area is a region that faces or contacts the wearer's excretory outlet when the absorbent article (including the disposable diaper 1) is in use. The excretory outlet contact area is set appropriately depending on the type and use of the absorbent article. For example, the excretory outlet contact area is set at the center or slightly forward of the center of the absorbent body in the longitudinal direction L, with a length of about 1 / 10 to 1 / 2 of the total length of the absorbent body, and at approximately the center of the absorbent body in the width direction W, with a width of about 1 / 3 to 1 / 2 of the total width of the absorbent body.

[0065] In this embodiment, the body-side core wrap sheet 11b1 and the non-skin-side core wrap sheet 11b2 encase the absorbent core 11a so that the unevenness and wrinkles of the crepe paper extend along the longitudinal direction L. However, each of the body-side core wrap sheet 11b1 and the non-skin-side core wrap sheet 11b2 does not need to have unevenness or wrinkles over its entire surface. It is sufficient for each of the body-side core wrap sheet 11b1 and the non-skin-side core wrap sheet 11b2 to have unevenness or wrinkles over 90% or more of its entire surface, including the excretory opening contact area, preferably 95% or more, and more preferably 98% or more. This makes it easier to prevent breakage due to external force in each of the body-side core wrap sheet 11b1 and the non-skin-side core wrap sheet 11b2.

[0066] In the disposable diaper 1 described above, the unevenness (number and / or size of the unevenness) of the skin-side core wrap sheet 11b1, which is made of crepe paper with unevenness, is smaller than the unevenness of the non-skin-side core wrap sheet 11b2. That is, in the disposable diaper 1, the unevenness of the skin-side core wrap sheet 11b1 is relatively small. This improves the liquid diffusibility in the planar direction of the skin-side core wrap sheet 11b1 and also increases the contact area between the topsheet 12 and the skin-side core wrap sheet 11b1 and the contact area between the skin-side core wrap sheet 11b1 and the absorbent core 11a. Therefore, during use, bodily fluids (including sweat) released into the disposable diaper 1 and transferred from the topsheet 12 to the skin-side core wrap sheet 11b1 can be diffused in the planar direction of the skin-side core wrap sheet 11b1 and then transferred to the absorbent core 11a. Therefore, body fluids can be absorbed over a very wide area within the absorbent body 11, thereby reducing the amount of body fluid absorbed per unit area in a plan view of the absorbent body 11. This makes it difficult for the disposable diaper 1 to rewet after absorbing body fluids.

[0067] On the other hand, by relatively increasing the unevenness of the non-skin-side core wrap sheet 11b2 made of crepe paper, the non-skin-side core wrap sheet 11b2 can be made more deformable. As a result, even if the disposable diaper 1 expands and contracts due to the wearer's body movements during use, the non-skin-side core wrap sheet 11b2 can follow the expansion and contraction, thereby preventing breakage. In this case, the unevenness of the non-skin-side core wrap sheet 11b2 absorbs the external force caused by the wearer's body movements, thereby reducing the external force acting on the skin-side core wrap sheet 11b1 (which has a small unevenness and cannot be said to tolerate a large external force), and thus preventing breakage of the skin-side core wrap sheet 11b1.

[0068] In this way, in a disposable diaper 1 having an absorbent body 11 including an absorbent core 11a wrapped in a crepe paper core wrap sheet 11b, it is possible to achieve both improved rewetting by improving the liquid diffusion in the planar direction of the skin-side core wrap sheet 11b1 and suppression of breakage of the core wrap sheet 11b.

[0069] In this embodiment, the number of irregularities per unit length in the direction perpendicular to the direction in which the irregularities (wrinkles) extend in the longitudinal direction L, i.e., the average number of irregularities per unit length of 1 cm in the width direction W, in the skin-side core wrap sheet 11b1, is, for example, 1 to 50. Having one or more irregularities makes the skin-side core wrap sheet 11b1 more easily deformable and reduces breakage of the skin-side core wrap sheet 11b1. Having 50 or fewer irregularities improves the liquid diffusibility in the planar direction of the skin-side core wrap sheet 11b1 and increases the contact area with both the topsheet 12 and the absorbent core 11a.

[0070] In this embodiment, the skin-side core wrap sheet 11b1 has an irregularity height H (average), which is the size of the irregularities (wrinkles), of, for example, 0.1 to 1 mm. Having an irregularity height H of 0.1 mm or more allows the skin-side core wrap sheet 11b1 to be easily deformed, thereby preventing the skin-side core wrap sheet 11b1 from breaking. Having an irregularity height H of 1 mm or less improves the liquid diffusibility in the planar direction of the skin-side core wrap sheet 11b1 and increases the contact area with both the topsheet 12 and the absorbent core 11a. Furthermore, the irregularity width D (average), which is the size of the irregularities, is, for example, 0.2 to 10 mm. Having an irregularity width D of 0.2 mm or more allows the skin-side core wrap sheet 11b1 to be easily deformed, thereby preventing the skin-side core wrap sheet 11b1 from breaking. By making the width D of the irregularities 10 mm or less, the liquid diffusibility in the planar direction of the skin side core wrap sheet 11b1 can be improved, and the contact areas with both the top sheet 12 and the absorbent core 11a can be increased.

[0071] In this embodiment, the non-skin-side core wrap sheet 11b2 has, on average, 2 to 100 irregularities extending along the longitudinal direction L per unit length of 1 cm in the width direction W. Having two or more irregularities makes the non-skin-side core wrap sheet 11b2 more easily deformable, thereby preventing breakage of the non-skin-side core wrap sheet 11b2 and the skin-side core wrap sheet 11b1. Having 100 or fewer irregularities improves the liquid diffusibility of the non-skin-side core wrap sheet 11b2 in the planar direction to a certain extent, and increases the contact area between the backsheet 13 and the absorbent core 11a.

[0072] In this embodiment, the non-skin-side core wrap sheet 11b2 has an average height (wrinkle height) of 0.2 to 2 mm, which is the size of the irregularities. Having an irregularity height H of 0.2 mm or more allows the non-skin-side core wrap sheet 11b2 to be easily deformed, thereby preventing breakage of the non-skin-side core wrap sheet 11b2 and the skin-side core wrap sheet 11b1. Having an irregularity height H of 6 mm or less allows the non-skin-side core wrap sheet 11b2 to have a somewhat improved liquid diffusibility in the planar direction, and allows for increased contact areas with both the backsheet 13 and the absorbent core 11a. Furthermore, the average width D of the irregularities, which is the size of the irregularities, is 0.1 to 5 mm, for example. Having an irregularity width D of 0.1 mm or more allows the non-skin-side core wrap sheet 11b2 to be easily deformed, thereby preventing breakage of the non-skin-side core wrap sheet 11b2 and the skin-side core wrap sheet 11b1. By making the width D of the irregularities 5 mm or less, the liquid diffusibility in the planar direction of the non-skin side core wrap sheet 11b2 can be improved to some extent, and the contact area with both the back sheet 13 and the absorbent core 11a can be increased.

[0073] In a preferred aspect of this embodiment, the skin side core wrap sheet 11b1 includes fibers that constitute the skin side core wrap sheet 11b1 and a composition containing a hydrophilic solvent carried by the fibers. In other words, the skin side core wrap sheet 11b1 includes (is coated with) a composition containing a hydrophilic solvent.

[0074] As described above, the fibers constituting the skin-side core wrap sheet 11b1 include synthetic resin fibers, pulp fibers, and mixtures thereof. The composition is a hydrophilic solvent containing a functional agent having a predetermined function. Examples of functional agents having a predetermined function include antibacterial agents, deodorants, warming agents, herbal medicines, fragrances, and mixtures of at least two of these. The hydrophilic solvent refers to a solvent that is miscible with water in any ratio, and examples include water, hydrophilic organic solvents, and mixtures thereof.

[0075] In the disposable diaper 1 described above, the fibers constituting the skin-side core wrap sheet 11b1 are supported with a composition containing a hydrophilic solvent, which allows the fibers to be more compatible with body fluids. Therefore, during use, body fluid released into the disposable diaper 1 and transferred from the topsheet 12 to the skin-side core wrap sheet 11b1 can be more easily diffused in the planar direction of the skin-side core wrap sheet 11b1. In other words, the liquid diffusibility in the planar direction of the skin-side core wrap sheet 11b1 can be further improved. This further reduces rewetting of the disposable diaper 1.

[0076] The fibers constituting the topsheet 12 may be supported with a composition containing a hydrophilic solvent. In other words, the topsheet 12 may contain (or be coated with) a composition containing a hydrophilic solvent. In this case, the composition of the topsheet 12 migrates to the skin-side core wrap sheet 11b1 over time, achieving the same effect as when the composition is disposed in the skin-side core wrap sheet 11b1. In this case, the amount of composition contained in the topsheet 12 is less than the amount of composition contained in the skin-side core wrap sheet 11b1.

[0077] In a preferred aspect of this embodiment, the composition further comprises a hydrophilic antimicrobial agent, in other words, the functional agent contained in the composition comprises a hydrophilic antimicrobial agent.

[0078] Here, a hydrophilic antibacterial agent refers to an antibacterial agent that dissolves 40 g or more in 100 g of water at 25°C within 5 hours. There are no particular limitations on the antibacterial agent, as long as it is hydrophilic and has antibacterial function, i.e., the function of suppressing bacterial growth. Examples of the type of antibacterial agent include cationic antibacterial agents. Examples of cationic antibacterial agents include guanidine antibacterial agents, biguanide antibacterial agents, and quaternary ammonium salts. Examples of guanidine antibacterial agents include polyhexamethylene guanidine (PHMG), and examples of biguanide antibacterial agents include polyhexamethylene biguanide (PHMB), also known as polyaminopropyl biguanide. Examples of quaternary ammonium salts include benzalkonium chloride and benzethonium chloride. These antibacterial agents may be used alone or in combination.

[0079] In the disposable diaper 1 described above, the fibers constituting the skin-side core wrap sheet 11b1 are loaded with a composition further containing a hydrophilic antibacterial agent. The effect of the hydrophilic antibacterial agent makes the fibers more compatible with body fluids. Therefore, during use, body fluids released into the disposable diaper 1 and transferred from the topsheet 12 to the skin-side core wrap sheet 11b1 can be more easily diffused in the planar direction of the skin-side core wrap sheet 11b1. In other words, the liquid diffusibility in the planar direction of the skin-side core wrap sheet 11b1 can be further improved. This further suppresses rewetting of the disposable diaper 1. Furthermore, the antibacterial agent can impart antibacterial properties to body fluids transferring from the topsheet 12 to the absorbent body 11.

[0080] In a preferred aspect of this embodiment, the solvent contains a non-volatile organic substance. In other words, the solvent contained in the composition contains a hydrophilic, non-volatile organic solvent.

[0081] Here, non-volatile organic substances (solvents) refer to organic solvents having a vapor pressure of 50 Pa or less at 25°C. There are no particular limitations on the solvent, as long as it is an organic solvent that is hydrophilic and non-volatile and can dissolve the antibacterial agent. Examples of types of solvents include glycols and alcohols. Examples of glycols include propylene glycol (PG), dipropylene glycol (DPG), 1,3-butylene glycol (BG), and polyethylene glycol 400 (PEG400). Examples of alcohols include 3-methoxy-3-methyl-1-butanol. These organic solvents may be used alone or in combination.

[0082] In the disposable diaper 1 described above, the fibers constituting the skin-side core wrap sheet 11b1 are supported with a solvent containing a hydrophilic, non-volatile organic substance. The hydrophilic, non-volatile organic substance allows for stable and continuous compatibility between body fluids and the fibers. Therefore, during use, body fluids released into the disposable diaper 1 and transferred from the topsheet 12 to the skin-side core wrap sheet 11b1 can be more easily diffused in the planar direction of the skin-side core wrap sheet 11b1. In other words, the liquid diffusibility in the planar direction of the skin-side core wrap sheet 11b1 can be further improved. This further reduces rewetting of the disposable diaper 1. Furthermore, the hydrophilic, non-volatile organic substance is less likely to volatilize, thereby reducing irritation to the skin.

[0083] In a preferred aspect of this embodiment, the composition (containing an antibacterial agent and a hydrophilic, non-volatile organic solvent) has a viscosity at 25°C of, for example, 5 mPa·s, preferably 50 mPa·s. By setting the viscosity lower limit within this range, the composition can be more likely to remain stably on the surface of the fiber without vertically moving downward (or falling), thereby enabling the fiber to more stably and continuously exhibit compatibility with body fluids. From the viewpoint of ease of application, the upper limit is, for example, 12,000 mPa·s. The viscosity is measured using a HAAKE RheoStress 1 (sensor: cone φ60 mm, 1° angle C60 / 1) manufactured by Thermo Fisher Scientific Co., Ltd., under the conditions of 38 ml of composition, temperature 25°C, humidity 50%, and shear rate: 10.0 (l / s).

[0084] The lower limit of the total ratio of the antibacterial agent and the solvent to the composition is, for example, 90% by mass, preferably 95% by mass or more, from the viewpoint of ensuring antibacterial activity. In addition to the antibacterial agent and the organic solvent, the composition may further contain another solvent, such as water. In terms of suppressing volatility of the composition and suppressing rust on the manufacturing equipment, the amount of water is preferably less than the amount of the organic solvent. Furthermore, from the viewpoint of ensuring antibacterial activity, the lower limit of the ratio of the antibacterial agent to the total ratio of the antibacterial agent and the solvent is, for example, 1% by mass, preferably 2% by mass. From the viewpoint of solubility in the solvent, the upper limit is, for example, 60% by mass, preferably 50% by mass. Note that the solvent of the composition can be identified and quantified using GC / MS (gas chromatography / mass spectrometry), and the antibacterial agent of the composition can be identified and quantified using LC / MS (high performance liquid chromatography / mass spectrometry).

[0085] In a preferred aspect of this embodiment, the degree of unevenness in the center of the longitudinal direction L and the center of the width direction W of the skin side core wrap sheet 11b1 is smaller than the degree of unevenness at both ends of the longitudinal direction L and both ends of the width direction W.

[0086] Here, examples of the central portion of the skin side core wrap sheet 11b1 in the longitudinal direction L include, in a plan view, the central portion (one portion) excluding both end portions (one portion each) when the skin side core wrap sheet 11b1 is divided into three, preferably equal portions, in the longitudinal direction L, the central portion (two portions) excluding both end portions (one portion each) when the skin side core wrap sheet 11b1 is divided into four, preferably equal portions, in the longitudinal direction L, and the central portion (three or one portion) excluding both end portions (one or two portions each) when the skin side core wrap sheet 11b1 is divided into five, preferably equal portions, in the longitudinal direction L. The central portion in the longitudinal direction L is set appropriately depending on the performance required of the disposable diaper 1.

[0087] On the other hand, examples of the central portion in the width direction W of the skin side core wrap sheet 11b1 include, in a plan view, the central portion (one portion) excluding both end portions (one portion each) when the skin side core wrap sheet 11b1 is divided into three, preferably equal portions, in the width direction W; the central portion (two portions) excluding both end portions (one portion each) when the skin side core wrap sheet 11b1 is divided into four, preferably equal portions, in the width direction W; and the central portion (three or one portion) excluding both end portions (one or two portions each) when the skin side core wrap sheet 11b1 is divided into five, preferably equal portions, in the width direction W. The central portion in the width direction W is set appropriately depending on the performance required of the disposable diaper 1.

[0088] As shown in Figure 4, in this embodiment, in the skin-side core wrap sheet 11b1, the central portion in the longitudinal direction L and the central portion in the width direction W in a planar view are also referred to as the central region TA, the outer portion thereof is also referred to as the outer region MTA, and the portion of the outer region MTA that overlaps with the absorbent core 11a is also referred to as the outer central region NTA (note that these definitions also apply to the topsheet 12 and backsheet 13 that overlap in the thickness direction T). The central region TA in the skin-side core wrap sheet 11b1 is a portion with a small degree of unevenness, and in a planar view, it is a portion that includes the excretion opening contact area and is a region that overlaps with the absorbent core 11a. In this embodiment, the central region TA is, in a planar view, the central portion (two portions) when the skin-side core wrap sheet 11b1 is divided into four equal portions in the longitudinal direction L and the central portion (one portion) when the skin-side core wrap sheet 11b1 is divided into three equal portions in the width direction W. Reducing the degree of unevenness in the central region TA of the skin side core wrap sheet 11b1 in this manner can be achieved, for example, by applying a composition to the central region TA.

[0089] As described above, in the disposable diaper 1, the degree of unevenness in the body-side core wrap sheet 11b1 is relatively small in the center in the longitudinal direction L and the center in the width direction W, i.e., in the excretory outlet contact area (central area TA). This allows the body-side core wrap sheet 11b1 to have relatively high planar liquid diffusibility in the excretory outlet contact area. This allows the body-side core wrap sheet 11b1 to quickly diffuse body fluid released into the excretory outlet contact area in the planar direction during use and then transfer the body fluid to the absorbent core 11a. Therefore, body fluid can be absorbed over a very wide area (including the outer central area NTA) within the absorbent body 11, thereby making the disposable diaper 1 less susceptible to rewetting.

[0090] Furthermore, in the disposable diaper 1, the degree of unevenness of the skin-side core wrap sheet 11b1 is relatively large at both ends in the longitudinal direction L and both ends in the width direction W, i.e., at the end regions of the absorbent body 11 (hereinafter also referred to as "end regions"). This allows the liquid diffusibility in the planar direction of the skin-side core wrap sheet 11b1 in the end regions to be relatively small. This allows the end regions to suppress the diffusion of body fluids that have diffused outward from the excretory opening contact area (central region TA) during use. Therefore, the end regions can suppress leakage of body fluids out of the disposable diaper 1 during use. In this embodiment, the end regions are regions outside the central region TA, i.e., the outer central region NTA or its peripheral regions.

[0091] In a preferred aspect of this embodiment, the degree of unevenness of the skin side core wrap sheet 11b1 is smaller than the degree of unevenness of the skin side of the topsheet 12.

[0092] Here, examples of the topsheet 12 include sheets with irregularities, such as a sheet extending in the longitudinal direction L and including a plurality of convex portions spaced apart in the width direction W and a plurality of concave portions provided between each of the convex portions, and a sheet having a plurality of convex portions that are substantially circular in plan view and arranged in a checkerboard pattern in plan view. In this embodiment, the height (average) of the irregularities in the topsheet 12 is, for example, 0.2 to 3 mm. The width D (average) of the irregularities is, for example, 0.1 to 3 mm.

[0093] As described above, in the disposable diaper 1, by making the degree of unevenness of the skin-side core wrap sheet 11b1 relatively smaller than the degree of unevenness of the skin-side of the topsheet 12, it is possible to make it easier for the skin-side core wrap sheet 11b1 to come into contact with the topsheet 12. As a result, during use, bodily fluid released onto the topsheet 12 can be quickly transferred from the topsheet 12 to the skin-side core wrap sheet 11b1, where it can be diffused in the planar direction by the skin-side core wrap sheet 11b1 and then transferred to the absorbent core 11a. Furthermore, by making the degree of unevenness of the skin-side of the topsheet 12 relatively larger, it is possible to make it more difficult for bodily fluid absorbed into the absorbent core 11a to come into contact with the wearer's skin through the topsheet 12, making it less likely for rewetting to occur.

[0094] In a preferred aspect of this embodiment, the crepe paper in the skin-side core wrap sheet 11b1 and the non-skin-side core wrap sheet 11b2 has a concave surface on the side opposite the convex portions. In other words, as shown in Figure 3(b), the crepe paper has convex portions 51 that are not solid, and the opposite side has concave recesses 52 formed therein. The recesses 52 on the side opposite the convex portions 51 contain some of the pulp fibers of the absorbent core 11a. In other words, the recesses 52 are filled with pulp fibers.

[0095] As described above, in the disposable diaper 1, the crepe paper in the skin-side core wrap sheet 11b1 includes a portion of the pulp fibers of the absorbent core 11a in the recessed portion 52 on the surface opposite to the protruding portion 51. This increases the contact area between the skin-side core wrap sheet 11b1 and the absorbent core 11a. This allows bodily fluids excreted into the disposable diaper 1 during use to be quickly transferred from the skin-side core wrap sheet 11b1 to the absorbent core 11a.

[0096] Furthermore, the crepe paper in the non-skin-side core wrap sheet 11b2 includes some of the pulp fibers of the absorbent core 11a in the recessed portions 52 on the surface opposite to the protruding portions 51. This makes it easier for body fluids that have not been absorbed by the absorbent core 11a and have passed through to be diffused in the planar direction, and can be absorbed by the absorbent core 11a on the end sides in the longitudinal direction L and / or width direction W.

[0097] Furthermore, since the recessed portions 52 of the skin side core wrap sheet 11b1 and the non-skin side core wrap sheet 11b2 contain pulp fibers, it is possible to prevent the skin side core wrap sheet 11b1 and the non-skin side core wrap sheet 11b2 from deforming too much, which would result in a reduction in absorption performance (e.g., absorption speed, absorption amount, etc.).

[0098] In a preferred aspect of this embodiment, the disposable diaper 1 further comprises a plurality of non-skin-side elastic members 17 (and / or 18) extending along the longitudinal direction L at a position overlapping the absorbent body 11 in the thickness direction T and on the non-skin side of the absorbent body 11 in the thickness direction T.

[0099] As described above, the disposable diaper 1 includes the non-skin-side elastic member 17 (and / or 18), which makes it easier to press the skin-side portion of the absorbent body 11 against the body. This allows bodily fluids released into the disposable diaper 1 during use to be transferred more quickly from the topsheet 12 to the absorbent body. Furthermore, the non-skin-side core wrap sheet 11b2 can be reinforced by the non-skin-side elastic member 17 (and / or 18), which further prevents the non-skin-side core wrap sheet 11b2 from breaking.

[0100] In a preferred aspect of this embodiment, the disposable diaper 1 further comprises a pair of leakage preventing walls 15 located on both sides of the topsheet 12 in the width direction W and extending along the longitudinal direction L. Each of the pair of leakage preventing walls 15 includes a leakage preventing elastic member 16 extending along the longitudinal direction L. The contractile force per unit length of the leakage preventing elastic member 16 is smaller than the contractile force per unit length of the non-skin-side elastic member 17 (and / or 18).

[0101] As described above, the disposable diaper 1 is provided with a pair of leakage preventing walls 15 each having a leakage preventing elastic member 16, thereby preventing side leakage of body fluids in the width direction W. In addition, the non-skin-side elastic member 17 (and / or 18) is provided on the non-skin-side side, and has a contractile force per unit length greater than that of the leakage preventing elastic member 16, making it easier to press the skin-side portion of the absorbent body 11 against the body. This prevents side leakage of body fluids released into the disposable diaper 1 during use, while allowing the body fluids to be transferred more quickly from the topsheet 12 to the absorbent body 11.

[0102] In another embodiment, as shown virtually in Figure 1, the disposable diaper 1 may have a pair of embossed portions E formed in the shape of grooves extending from the surface of the topsheet 12 toward the absorbent body 11 in the thickness direction T and extending along the longitudinal direction L. The degree of unevenness of the skin-side core wrap sheet 11b1 in the region between the pair of embossed portions E is smaller than the degree of unevenness of the skin-side core wrap sheet 11b1 in the regions located outside each of the pair of embossed portions E in the width direction W.

[0103] As described above, in the disposable diaper 1, the degree of unevenness of the skin-side core wrap sheet 11b1 in the region between the pair of embossed portions E (the inner region) is relatively small. This allows the planar liquid diffusibility of the skin-side core wrap sheet 11b1 in the inner region to be relatively large. This allows the skin-side core wrap sheet 11b1 to quickly diffuse body fluid released into the inner region in the planar direction (outside the inner region) and then transfer it to the absorbent core 11a during use. This allows body fluid to be absorbed over a very wide area within the absorbent body 11, thereby making the disposable diaper 1 less susceptible to rewetting. The inner region can be defined as a region that includes the central region TA, which has a width between the pair of embossed portions E in the width direction W and extends in the longitudinal direction L within the absorbent core 11a.

[0104] Furthermore, the degree of unevenness of the skin-side core wrap sheet 11b1 is relatively large in the region (outer region) located widthwise outward of each of the pair of embossed portions E. This allows the planar liquid diffusibility of the skin-side core wrap sheet 11b1 in the outer region to be relatively small. As a result, during use, the diffusion of body fluids that have diffused from the inner region outward (over the embossed portions) is suppressed in the outer region, while the body fluids can be transferred to the absorbent core 11a. Therefore, during use, leakage of body fluids outside the disposable diaper 1 can be suppressed in the outer region. The outer region can be defined as the region of the absorbent core 11a generally excluding the central region TA.

[0105] Next, a method for manufacturing an absorbent article according to the embodiment will be described. Fig. 5 is a schematic diagram showing an example of a method for manufacturing an absorbent article according to the embodiment.

[0106] The absorbent article manufactured by this manufacturing method, i.e., the disposable diaper 1, has the following configuration. The disposable diaper 1 includes a topsheet 12, a backsheet 13, and an absorbent body 11 located between the topsheet 12 and the backsheet 13. The absorbent body 11 includes an absorbent core 11a containing pulp fibers, a skin-side core wrap sheet 11b1 located on the skin side of the absorbent core 11a in the thickness direction T, and a non-skin-side core wrap sheet 11b2 located on the non-skin side of the absorbent core 11a in the thickness direction T.

[0107] This manufacturing method includes a preparation step S1 and a formation step S2, and the formation step S2 includes a coating step S21.

[0108] The preparation process S1 includes preparing a continuous top sheet 112 made of a continuous top sheet 12, a continuous skin-side core wrap sheet 111b1 made of a continuous skin-side core wrap sheet 11b1 formed of crepe paper with unevenness, a continuous non-skin-side core wrap sheet 111b2 made of a continuous non-skin-side core wrap sheet 11b2 formed of crepe paper with unevenness, a plurality of absorbent cores 11a, and a continuous back sheet 113 made of a continuous back sheet 13.

[0109] In this embodiment, a continuous exterior sheet 114 having continuous leak-proof walls 115 is prepared, which is a continuous exterior sheet 14 (including the leak-proof elastic members 16 and the non-skin-side elastic members 17, 18) further having leak-proof walls 15. Then, a continuous backside sheet 113 is laminated at the center in the width direction W on the skin side of the continuous exterior sheet 114 having the continuous leak-proof walls 115, thereby preparing a continuous laminate 120 composed of the continuous backside sheet 113, the continuous exterior sheet 114, and the continuous leak-proof walls 115.

[0110] However, in this embodiment, the skin side core wrap sheet 11b1 (divided into two in the width direction W) and the non-skin side core wrap sheet 11b2 are formed as a single unit, so the continuous skin side core wrap sheet 111b1 (divided into two in the CD direction) and the continuous non-skin side core wrap sheet 111b2 are a single continuous core wrap sheet 111b.

[0111] The forming process S2 forms a laminate in which the surface sheet 12 portion of the continuous surface sheet 112, the skin side core wrap sheet 11b1 portion of the continuous skin side core wrap sheet 111b1, the absorbent core 11a, the non-skin side core wrap sheet 11b2 portion of the continuous non-skin side core wrap sheet 111b2, and the back sheet 13 portion of the continuous back surface sheet 113 are stacked in this order.

[0112] First, as shown in FIG. 5(a), the absorbent core 11a is placed on the portion of the continuous non-skin-side core wrap sheet 111b2 (the center in the CD direction) of the continuous core wrap sheet 111b.

[0113] Next, as shown in Figure 5(b), the continuous skin-side core wrap sheets 111b1 of the continuous core wrap sheet 111b located on both sides of the absorbent core 11a in the CD direction are folded and joined onto the absorbent core 11a. Then, the front and rear sides of the continuous core wrap sheet 111b in the MD direction of the absorbent core 11a are cut to the size of one absorbent body 11. This forms an absorbent body 11 in which the skin-side core wrap sheet 11b1, absorbent core 11a, and non-skin-side core wrap sheet 11b2 are laminated in this order.

[0114] Next, as shown in FIG. 5( c ), the topsheet 12 portion of the continuous topsheet 112 and the absorbent body 11 are arranged so as to face each other.

[0115] Next, as shown in Figure 5(d), the topsheet 12 portion of the continuous topsheet 112 is joined to the absorbent body 11. At the same time, the backsheet 13 portion of the continuous backsheet 113 is arranged to face the absorbent body 11. However, in this embodiment, the backsheet 13 portion of the continuous laminate 120 composed of the continuous backsheet 113, continuous exterior sheet 114, and continuous leak-barrier 115 is arranged to face the absorbent body 11.

[0116] Next, as shown in Figure 5(e), the topsheet 12 portion and absorbent body 11 of the continuous topsheet 112 are joined to the backsheet 13 portion of the continuous laminate 120. Then, the front and rear sides of the absorbent core 11a in the MD direction of the continuous topsheet 112 and the continuous laminate 120 are cut to the size of one piece of the topsheet 12 and backsheet 13 (and exterior sheet 14 and leak barrier 15). This forms the absorbent main body 10 in which the topsheet 12, absorbent body 11 and backsheet 13 (and exterior sheet 14 and leak barrier 15) are laminated in this order.

[0117] Here, the joining of the top sheet 12 portion of the continuous top sheet 112 to the absorbent body 11 (step in Figure 5(c)) and the joining of the absorbent body 11 to the back sheet 13 portion of the continuous laminate 120 (step in Figure 5(d)) may be performed simultaneously.

[0118] However, the forming step S2 includes an application step S21. In FIG. 5(b), the application step S21 is a step of applying a composition containing a hydrophilic solvent to the continuous skin-side core wrap sheet 111b1 or the skin-side core wrap sheet 11b1 portion of the absorbent body 11 after folding the continuous skin-side core wrap sheet 111b1 (schematically indicated as P1). In this case, the composition is applied to the skin-side surface of the skin-side core wrap sheet 11b1. Examples of application methods include a non-contact application method (e.g., spraying the composition onto the skin-side core wrap sheet 11b1 with a spray device) or a contact application method (e.g., ejecting the composition onto the skin-side core wrap sheet 11b1 from a nozzle). The application position is a portion with a relatively small degree of unevenness, as described in the embodiment of the disposable diaper 1.

[0119] In Figure 5 (c), the application step S21 may be a step of applying a composition containing a hydrophilic solvent to the topsheet 12 portion of the continuous topsheet 112 (schematically shown as P2). In this case, the composition is applied to the skin-side or non-skin-side surface of the topsheet 12 portion. The application method is as described above. After application, when the continuous topsheet 112 is joined to the absorbent body 11, the composition migrates from the topsheet 12 portion to the skin-side core wrap sheet 11b1. The migration can be largely controlled by adjusting the viscosity of the composition. The application position is a portion of the skin-side core wrap sheet 11b1 where the degree of unevenness is relatively small, as described in the embodiment of the disposable diaper 1.

[0120] In Figure 5 (d), the application step S21 may be a step of applying a composition containing a hydrophilic solvent to the top sheet 12 portion of the continuous top sheet 112 (schematically shown as P3). In this case, the composition is applied to the skin-side surface of the top sheet 12 portion. The application method is as described above. After application, the composition migrates from the top sheet 12 portion to the skin-side core wrap sheet 11b1. The migration can be largely controlled by adjusting the viscosity of the composition. The application position is a portion of the skin-side core wrap sheet 11b1 where the degree of unevenness is relatively small, as described in the embodiment of the disposable diaper 1.

[0121] The coating step S21 may be carried out in any one of the above three modes, or may be carried out in a combination of two or more modes.

[0122] Here, the degree of unevenness of the skin-side core wrap sheet 11b1 portion of the continuous skin-side core wrap sheet 111b1 after the forming step S2 is smaller than the degree of unevenness of the non-skin-side core wrap sheet 11b2 portion of the continuous non-skin-side core wrap sheet 111b2. This is because in the application step S21, a solvent-containing composition is applied or transferred to the skin-side core wrap sheet 11b1 portion of the continuous skin-side core wrap sheet 111b1, so that the applied portion is soaked in the liquid and softens, and the unevenness is flattened, thereby reducing the degree of unevenness.

[0123] Thereafter, the abdominal section 2 is joined to one end of the absorbent body 10 in the longitudinal direction L, and the dorsal section 3 is joined to the other end, thereby completing the disposable diaper 1 .

[0124] In this manufacturing method, the unevenness of the skin-side core wrap sheet 11b1 can be relatively reduced by the composition applied to the topsheet 12 and transferred to the skin-side core wrap sheet 11b1 in contact with the topsheet 12, or by the composition applied to the skin-side core wrap sheet 11b1. This increases the contact area between the topsheet 12 and the skin-side core wrap sheet 11b1, thereby improving the stability of the bond between the topsheet 12 and the skin-side core wrap sheet 11b1. Furthermore, because the unevenness of the skin-side core wrap sheet 11b1 of the manufactured disposable diaper 1 is relatively small, during use, bodily fluids (including sweat) released into the disposable diaper 1 and transferred from the topsheet 12 to the skin-side core wrap sheet 11b1 can be diffused in the planar direction of the skin-side core wrap sheet 11b1 and then transferred to the absorbent core 11a. Therefore, body fluids can be absorbed over a very wide area within the absorbent body 11, thereby reducing the amount of body fluid absorbed per unit area in a plan view of the absorbent body 11. This makes it less likely for rewetting to occur after absorbing body fluids in the disposable diaper 1. Furthermore, by relatively increasing the degree of unevenness of the non-skin-side core wrap sheet 11b2 of the crepe paper, the non-skin-side core wrap sheet 11b2 can be made more easily deformed, thereby preventing breakage of the non-skin-side core wrap sheet 11b2 and the skin-side core wrap sheet 11b1 during use.

[0125] The method for making the unevenness of the skin-side core wrap sheet 11b1 smaller than that of the non-skin-side core wrap sheet 11b2 is not limited to the above. For example, in the preparation step S1, crepe paper with a small unevenness may be used for the skin-side core wrap sheet 11b1 (continuous skin-side core wrap sheet 111b1), and crepe paper with a large unevenness may be used for the non-skin-side core wrap sheet 11b2 (continuous non-skin-side core wrap sheet 111b2).

[0126] In this embodiment, as a preferred aspect, in the application process S21, the composition is applied only to the central portion of the surface sheet 12 portion of the continuous surface sheet 112 in the longitudinal direction L and width direction W, and only to the central portion of the skin side core wrap sheet 11b1 portion of the continuous skin side core wrap sheet 111b1 in the longitudinal direction L and width direction W.

[0127] In the manufacturing method, the composition is applied to the center of the top sheet 12 or the skin-side core wrap sheet 11b1 in the longitudinal direction L and width direction W, i.e., approximately in the excretion opening contact area. This allows the degree of unevenness of the skin-side core wrap sheet 11b1 to be relatively small in the excretion opening contact area. This increases the contact area between the top sheet 12 and the skin-side core wrap sheet 11b1 in the excretion opening contact area. This further increases the stability of the bond between the top sheet 12 and the skin-side core wrap sheet 11b1.

[0128] Furthermore, the composition is not applied to the ends of the topsheet 12 or the skin-side core wrap sheet 11b1 other than the center in the longitudinal direction L and the width direction W. In this way, by not applying the composition to the ends in the longitudinal direction L and the width direction W, where the adhesive is mainly disposed when joining sheets together, the adhesive can function properly at the ends. This prevents the adhesive from not functioning properly during transport in the manufacturing process, thereby preventing problems such as the sheets at the ends of the disposable diaper turning up.

[0129] In this embodiment, as a preferred aspect, in the application step S21, the composition is applied, in a planar view, only to the area in the continuous top sheet 112 where the absorbent core 11a is located, and only to the area in the continuous skin-side core wrap sheet 111b1 where the absorbent core 11a is located.

[0130] In this manufacturing method, the composition is applied only to the area of ​​the topsheet 12 or the skin-side core wrap sheet 11b1 where the absorbent core 11a is located in a plan view. By limiting the area to which the composition is applied in this way, even if the skin-side core wrap sheet 11b1 is joined to the non-skin-side core wrap sheet 11b2 outside the area where the absorbent core 11a is located, the composition can be prevented from diffusing from the skin-side core wrap sheet 11b1 to the non-skin-side core wrap sheet 11b2. This prevents the degree of unevenness of the non-skin-side core wrap sheet 11b2 from decreasing and prevents the adhesive from becoming difficult to use when joining the sheets together.

[0131] In a preferred aspect of this embodiment, the composition further comprises a hydrophilic antibacterial agent, the solvent comprises water and an organic solvent, and the amount of water in the solvent is less than the amount of the organic solvent.

[0132] In this manufacturing method, the composition further contains a hydrophilic antibacterial agent, the solvent contains water and an organic solvent, and the amount of water is less than the amount of the organic solvent. By reducing the water content in the composition, rust generation in the manufacturing equipment can be suppressed. On the other hand, by increasing the organic solvent content in the composition, the antibacterial agent itself can be prevented from being exposed on the surface of the topsheet, which can cause irritation to the wearer's skin.

[0133] <Method for Measuring the Degree of Irregularity of Core Wrap Sheet> The degree of irregularity of the core wrap sheet is measured as follows. (1) Divide the absorbent article into thirds in the width and length directions to prepare nine samples. (2) After freezing each sample using liquid nitrogen, cut the sample in the thickness direction with a sharp utility knife so as not to distort the degree of irregularity, so that the sections where the degree of irregularity of each sample is to be measured (e.g., the center sections in the length and width directions, and the front-to-back sections in the length direction) can be viewed in cross section. The cut size may be 1 cm x 1 cm. (3) Prepare a microscope or optical microscope (e.g., VHX-7000 manufactured by Keyence Corporation) and take an image of the cross section of each sample at a magnification of 10 to 100 times. (4) In the captured image of each sample, measure the number of irregularities (wrinkles) per unit length and / or the height H and / or width D of the irregularities for each concave and convex portion. (5) Calculate the average of the measurements for nine samples (however, if there is a large difference depending on the location (±30% or more), calculate the average of at least three nearby samples) and use this as the final number of irregularities (wrinkles) per unit length and / or the height H of the irregularities and / or the width D of the irregularities.

[0134] <Method for measuring the area where antibacterial liquid (including antibacterial agent) has been applied> The method for measuring the amount of antibacterial liquid in the area where antibacterial liquid (including antibacterial agent) has been applied is as follows. (1) A sample of a predetermined size (e.g., 1 cm x 1 cm) is cut out from the part of the absorbent article where it is desired to check whether or not antibacterial liquid has been applied. (2) The antibacterial agent in the sample is identified and quantified using LC / MS (high performance liquid chromatography mass spectrometry). (3) Steps (1) to (2) above are performed on three samples, and the average value is calculated to determine the presence and amount of antibacterial liquid in that area. (4) Steps (1) to (3) above are performed on multiple parts of the absorbent article, and the areas where antibacterial liquid has been applied and the amount of antibacterial liquid in those areas are determined.

[0135] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0136] (1) Sample (a) Example 1 Topsheet (air-through nonwoven fabric): basis weight 30 g / m ２, skin side core wrap sheet (crepe paper tissue): basis weight 15 g / m ２ , Absorbent core (pulp fiber): basis weight 60 g / m ２ , Non-skin side core wrap sheet (crepe paper tissue): basis weight 15 g / m ２ , Back sheet (breathable film): basis weight 35 g / m ２ (b) Comparative Example 1 A simulated absorbent body having the same configuration as Example 1 was prepared. However, a simulated composition (1,3-butylene glycol (BG)) was applied to almost the entire surface of the skin-side core wrap sheet using a spray device. In this sample, it was possible to visually confirm that the crepe irregularities had almost completely disappeared due to the hydrophilic solvent before lamination. Furthermore, measurement using a microscope revealed that the irregularity height was 0.015 mm. (b) Comparative Example 1 A simulated absorbent body having the same configuration as Example 1 was prepared. However, the skin-side core wrap sheet was not coated with the simulated composition (1,3-butylene glycol (BG)). In this sample, the absence of a hydrophilic solvent before lamination meant that the crepe irregularities were visually confirmed. Furthermore, measurement using a microscope revealed that the irregularity height was 0.025 mm.

[0137] (2) Evaluation Method: 0.5 ml of artificial blood was dropped onto the samples of Example 1 and Comparative Example 1 from a height of 5 mm above the topsheet, and the degree of diffusion of the artificial blood on the topsheet and the skin-side core wrap sheet after 3 minutes was measured. The degree of diffusion was measured by measuring the spread width of the artificial blood in the MD and CD directions at the time of manufacturing each sheet. The artificial blood was prepared by mixing 80 g of glycerin, 8 g of CMC sodium salt, 10 g of NaCl, 4 g of NaHCO3, 8 g of red dye No. 102, 2 g of red dye No. 2, and 2 g of yellow dye No. 5 with 1000 cc of water, and adjusted to a viscosity of approximately 22 to 26 mPa·s.

[0138] (3) Evaluation Results (a) Example 1: Within the topsheet, the artificial blood diffused 17 mm in the MD direction and 18 mm in the CD direction. Meanwhile, within the skin-side core wrap sheet, the artificial blood diffused 31 mm in the MD direction and 35 mm in the CD direction. (b) Comparative Example 1: Within the topsheet, the artificial blood diffused 23 mm in the MD direction and 20 mm in the CD direction. Meanwhile, within the skin-side core wrap sheet, the artificial blood diffused 28 mm in the MD direction and 23 mm in the CD direction. (c) Summary: Comparing Example 1 and Comparative Example 1, it was found that the artificial blood moved from the topsheet to the skin-side core wrap sheet more quickly and diffused in the planar direction within the skin-side core wrap sheet in the case where the composition was applied to the skin-side core wrap sheet and the degree of unevenness was reduced (Example 1) than in the case where the composition was not applied to the skin-side core wrap sheet (Comparative Example 1).

[0139] The disposable diaper and its manufacturing method of the present invention are not limited to the above-mentioned embodiments, and it is possible to combine the embodiments or apply publicly known technologies within the scope that does not deviate from the purpose and intent of the present invention.

[0140] REFERENCE SIGNS LIST 1 absorbent article 11 absorbent body 11a absorbent core 11b1 skin-side core wrap sheet 11b2 non-skin-side core wrap sheet

Claims

1. An absorbent article having a longitudinal direction, a width direction and a thickness direction which are perpendicular to each other, comprising a top sheet, a back sheet and an absorbent body located between the top sheet and the back sheet, wherein the absorbent body comprises an absorbent core containing pulp fibers, a skin side core wrap sheet located on the skin side of the absorbent core in the thickness direction, and a non-skin side core wrap sheet located on the non-skin side of the absorbent core in the thickness direction, wherein the skin side core wrap sheet and the non-skin side core wrap sheet are made of crepe paper having an unevenness, and the degree of unevenness of the skin side core wrap sheet is smaller than the degree of unevenness of the non-skin side core wrap sheet.

2. The absorbent article according to claim 1, wherein the skin side core wrap sheet comprises: fibers constituting the skin side core wrap sheet; and a composition containing a hydrophilic solvent supported on the fibers.

3. The absorbent article of claim 2, wherein the composition further comprises a hydrophilic antimicrobial agent.

4. The absorbent article according to claim 3, wherein the solvent comprises a non-volatile organic substance.

5. An absorbent article as described in any one of claims 1 to 4, wherein the degree of unevenness in the center of the longitudinal direction and the center of the width direction of the skin side core wrap sheet is smaller than the degree of unevenness at both ends of the longitudinal direction and both ends of the width direction.

6. An absorbent article according to any one of claims 1 to 5, wherein the unevenness of the skin side core wrap sheet is smaller than the unevenness of the skin side of the top sheet.

7. An absorbent article as described in any one of claims 1 to 6, wherein the crepe paper in the skin side core wrap sheet and the non-skin side core wrap sheet is formed with a concave shape on the surface opposite the convex portion in the unevenness, and the concave portion includes a portion of the pulp fibers of the absorbent core.

8. An absorbent article as claimed in any one of claims 1 to 7, further comprising a non-skin-side elastic member extending along the longitudinal direction at a position overlapping with the absorbent in the thickness direction and on the non-skin side of the absorbent in the thickness direction.

9. An absorbent article as described in claim 8, further comprising a pair of leakproof walls located on both sides of the top sheet in the width direction and extending along the longitudinal direction, each of the pair of leakproof walls including a leakproof elastic member extending along the longitudinal direction, and the contractile force per unit length of the leakproof elastic member being smaller than the contractile force per unit length of the non-skin side elastic member.

10. An absorbent article as described in any one of claims 1 to 9, having a pair of embossed portions formed in a groove shape extending from the surface of the top sheet toward the absorbent body and extending along the longitudinal direction, and the degree of unevenness of the skin side core wrap sheet in the area between the pair of embossed portions is smaller than the degree of unevenness of the skin side core wrap sheet in areas located outside each of the pair of embossed portions in the width direction.

11. A method for manufacturing an absorbent article having a longitudinal direction, a width direction and a thickness direction perpendicular to each other, the method comprising: a top sheet, a back sheet, and an absorbent body located between the top sheet and the back sheet, the absorbent body including an absorbent core containing pulp fibers, a skin-side core wrap sheet located on the skin side of the absorbent core in the thickness direction, and a non-skin-side core wrap sheet located on the non-skin side of the absorbent core in the thickness direction, the method comprising the steps of: preparing a continuous top sheet in which the top sheet is continuous; a continuous skin-side core wrap sheet in which the skin-side core wrap sheets are continuous and formed of crepe paper having unevenness; a continuous non-skin-side core wrap sheet in which the non-skin-side core wrap sheets are continuous and formed of crepe paper having unevenness; a plurality of the absorbent cores; and a continuous back sheet in which the back sheet is continuous; a forming step of forming a laminate in which a portion of the top sheet of the continuous top sheet, a portion of the skin side core wrap sheet of the continuous skin side core wrap sheet, the absorbent core, a portion of the non-skin side core wrap sheet of the continuous non-skin side core wrap sheet, and a portion of the back sheet of the continuous back sheet are stacked in this order, wherein the forming step includes a coating step of applying a composition containing a hydrophilic solvent to at least one of the portion of the top sheet of the continuous top sheet and the portion of the skin side core wrap sheet of the continuous skin side core wrap sheet, and wherein the degree of unevenness of the portion of the skin side core wrap sheet in the continuous skin side core wrap sheet after the forming step is smaller than the degree of unevenness of the portion of the non-skin side core wrap sheet in the continuous non-skin side core wrap sheet.

12. The method according to claim 11, wherein in the application step, the composition is applied only to the central portions of the longitudinal and width directions of the surface sheet portion of the continuous surface sheet, and only to the central portions of the longitudinal and width directions of the skin side core wrap sheet portion of the continuous skin side core wrap sheet.

13. A method according to claim 11 or 12, wherein in the application step, the composition is applied, in a planar view, to at least one of the area of ​​the continuous top sheet where the absorbent core is located and the area of ​​the continuous skin side core wrap sheet where the absorbent core is located.

14. The method of any one of claims 11 to 13, wherein the composition further comprises a hydrophilic antimicrobial agent, and the solvent comprises water and an organic solvent, and in the solvent, the amount of water is less than the amount of the organic solvent.

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