WO2024034356A1

WO2024034356A1 - Absorbent article

Info

Publication number: WO2024034356A1
Application number: PCT/JP2023/026747
Authority: WO
Inventors: 青石川; 賢一郎黒田; 風花奥田
Original assignee: ユニ・チャーム株式会社
Priority date: 2022-08-08
Filing date: 2023-07-21
Publication date: 2024-02-15
Also published as: JP2024023022A

Abstract

Provided is an absorbent article that can maintain absorbent article performance while suppressing deterioration in texture. An absorbent article (1) comprises: a top sheet (10) that comes into contact with the skin of a wearer; and a non-skin side member (40) that is in contact with a non-skin surface of the top sheet. The top sheet is nonwoven fabric that has a first fiber layer (11) which is disposed on a skin surface of the top sheet, and a second fiber layer (12) that is in contact with a non-skin surface of the first fiber layer (11). The first fiber layer includes thermoplastic resin fibers (51). The second fiber layer includes the thermoplastic resin fibers (51) and cellulosic fibers (52). The bonding strength between the first fiber layer and the second fiber layer is lower than the bonding strength between the top sheet and the non-skin side member.

Description

absorbent articles

The present invention relates to an absorbent article having a topsheet including multiple fibrous layers.

Patent Document 1 discloses a nonwoven fabric including a plurality of fiber layers and an absorbent article using the nonwoven fabric as a top sheet. The nonwoven fabric used for the topsheet includes a first fibrous layer and a second fibrous layer located on one main surface of the first fibrous layer. The first fiber layer includes core-sheath type composite fibers (thermoplastic resin fibers), and the second fiber layer includes core-sheath type composite fibers (thermoplastic resin fibers) and cellulose fibers.

JP2020-171688A

The nonwoven fabric of the above-mentioned absorbent article is placed on the side closer to the user's skin from the first fiber layer side. Therefore, body fluid discharged from the wearer is guided from the first fiber layer to the second fiber layer, and from the second fiber layer side to the second sheet or absorbent body located on the non-skin side of the top sheet. At this time, if delamination occurs between the top sheet and the second sheet or between the top sheet and the absorbent body, the mutual positions may shift or the transferability of body fluids may decrease, which may affect the performance of the absorbent article. There were times when I couldn't maintain it. Furthermore, in order to prevent the delamination, it is possible to increase the bonding strength between the top sheet and the second sheet or between the top sheet and the absorbent body. However, when the bonding strength is increased, the conformability of the top sheet to the skin may be lowered, resulting in a lower feel to the skin.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an absorbent article that can maintain the performance of the absorbent article while suppressing deterioration in texture.

An absorbent article according to one embodiment includes a top sheet that comes into contact with the wearer's skin, and a non-skin side member that comes into contact with the non-skin side of the top sheet. The top sheet is a nonwoven fabric having a first fiber layer disposed on the skin surface of the top sheet, and a second fiber layer contacting the non-skin surface of the first fiber layer. The first fiber layer includes thermoplastic resin fibers. The second fiber layer includes thermoplastic resin fibers and cellulose fibers. The bonding strength between the first fiber layer and the second fiber layer is lower than the bonding strength between the top sheet and the non-skin side member.

FIG. 1 is a plan view of an absorbent article according to an embodiment. FIG. 2 is a cross-sectional view taken along line AA shown in FIG. FIG. 3 is a schematic cross-sectional view of the top sheet. FIG. 4 is a diagram for explaining a method for manufacturing a nonwoven fabric for an absorbent article according to an embodiment.

(1) Outline of the embodiments At least the following matters will become clear from the description of this specification and the accompanying drawings.
An absorbent article according to one embodiment includes a top sheet that contacts the wearer's skin, and a non-skin side member that contacts the non-skin surface of the top sheet. The top sheet is a nonwoven fabric having a first fiber layer disposed on the skin surface of the top sheet, and a second fiber layer in contact with the non-skin surface of the first fiber layer. The first fiber layer includes thermoplastic resin fibers. The second fiber layer includes thermoplastic resin fibers and cellulose fibers. The bonding strength between the first fiber layer and the second fiber layer is lower than the bonding strength between the top sheet and the non-skin side member. According to this aspect, the second fiber layer located on the non-skin side of the first fiber layer contains cellulose fibers. The cellulose fibers are arranged in the second fiber layer, which is difficult to come into direct contact with the skin. Therefore, the cellulose fibers of the second fiber layer retain body fluids, thereby maintaining the ability to absorb body fluids, while suppressing stickiness to the skin due to the cellulose fibers retaining the body fluids coming into contact with the skin. Furthermore, cellulose fibers are less likely to be disposed on the skin surface of the top sheet, and fuzzing of the cellulose fibers can be suppressed. Since the bonding strength between the first fiber layer and the second fiber layer is relatively low, when the top sheet rubs against the skin, the first fiber layer easily follows the contact, and it is possible to suppress a decrease in the feel of the top sheet. In addition, in a nonwoven fabric manufactured in an integrated manner, such as an air-through nonwoven fabric, at least fibers are arranged to bridge the first fiber layer and the second fiber layer by intersecting the fibers, and the first fiber layer and the second fiber layer are bonded. Even if the strength is relatively low, separation of the first fiber layer and the second fiber layer can be suppressed, and the performance of the nonwoven fabric can be maintained. Since the bonding strength between the top sheet and the non-skin side member is relatively high, it prevents delamination between the top sheet and the non-skin side member, suppresses misalignment between the top sheet and the non-skin side member, and prevents the transfer of body fluids. can ensure sex. Therefore, the absorbent performance of the absorbent article can be maintained.

The invention according to aspect 2 may have the following features in the invention according to aspect 1. The top sheet and the non-skin side member are bonded to each other with an adhesive spaced apart from each other in a plane direction. The distance between the adhesives is shorter than the average fiber length of the fibers arranged on the non-skin surface of the topsheet. According to this aspect, the fibers arranged on the non-skin surface of the top sheet are likely to be arranged overlapping the adhesive and are likely to be adhered by the adhesive. Therefore, the fibers arranged on the non-skin surface of the topsheet are less likely to come off from the nonwoven fabric, and are more likely to remain within the topsheet, allowing the performance of the absorbent article to be maintained. Further, the fibers are not bonded to each other in the spaces between the adhesives, and the degree of freedom in deformation of the fibers is increased. Therefore, the followability of the top sheet can be further improved while suppressing delamination between the first fiber layer and the second fiber layer. In addition, since the fibers have a high degree of freedom in deformation, it is possible to suppress the cutting of the fibers and prevent the cut fibers from becoming fluffy and causing a deterioration in the feel of the fabric.

The invention according to aspect 3 may have the following features in the invention according to aspect 1 or aspect 2. The top sheet and the non-skin side member are joined by compressed parts arranged at intervals in a plane direction. The distance between the compressed parts is shorter than the average fiber length of the fibers arranged on the non-skin surface of the top sheet. According to this aspect, the fibers arranged on the non-skin surface of the top sheet are likely to be arranged overlapping the compressed portions and are likely to be joined by the compressed portions. Therefore, the fibers arranged on the non-skin surface of the topsheet are less likely to come off from the nonwoven fabric, and are more likely to remain within the topsheet, allowing the performance of the absorbent article to be maintained. In addition, the fibers are not bonded to each other at intervals between the compressed parts, and the degree of freedom in deforming the fibers is increased. Therefore, the followability of the top sheet can be further improved while suppressing delamination between the first fiber layer and the second fiber layer. In addition, since the fibers have a high degree of freedom in deformation, it is possible to suppress the cutting of the fibers and prevent the cut fibers from becoming fluffy and causing a deterioration in the feel of the fabric.

The invention according to aspect 4 may have the following features in the invention according to any one of aspects 1 to 3. A plurality of convex portions protruding toward the skin side and a plurality of concave portions recessed toward the non-skin side between the convex portions are formed on the skin surface of the top sheet. The fiber density in the concave portion is higher than the fiber density in the convex portion. The distance between the convex portions is shorter than the average fiber length of the fibers arranged on the non-skin surface of the top sheet. According to this aspect, since the interval between the protrusions is shorter than the average fiber length of the fibers arranged on the non-skin surface of the top sheet, the fibers are likely to be arranged in the recesses that are the intervals between the protrusions. The recessed portions have a relatively high fiber density, and fibers are less likely to come off. On the other hand, the convex portions have a relatively low fiber density. Therefore, there are gaps between the fibers, the cushioning properties are high, and the ends of the fibers are less likely to be exposed to the skin surface of the top sheet, making it possible to suppress deterioration of the feel due to fluffing. Further, since the convex portions are easy to come into contact with the skin, and the concave portions are difficult to come into contact with the skin, it is possible to suppress the fibers from coming off, keep the fibers within the top sheet, and maintain the performance of the absorbent article. Furthermore, since the fiber density is low in the convex portions, the degree of freedom in deforming the fibers is high, and the followability of the top sheet can be further improved. In addition, since the fibers have a high degree of freedom in deformation, it is possible to suppress the cutting of the fibers and to prevent the cut fibers from becoming fluffy and resulting in poor texture.

The invention according to aspect 5 may have the following features in the invention according to any one of aspects 1 to 4. A compressed portion is formed in the recessed portion by compressing at least the first fiber layer and the second fiber layer in the thickness direction. According to this aspect, it is possible to suppress the fibers of the first fiber layer and the fibers of the second fiber layer from coming off by the pressing part, and to suppress fluffing due to the fibers coming off. Moreover, the compressing part is provided in a recessed part that is more recessed than the convex part, so that it is difficult to come into direct contact with the body. Therefore, it is possible to suppress the discomfort caused by the pressing part hitting the body.

The invention according to aspect 6 may have the following features in the invention according to any one of aspects 1 to 5. The non-skin surface of the top sheet in the region where the convex portion is arranged is located closer to the skin than the non-skin surface of the surrounding top sheet. The convex portion is formed at least on the first fiber layer and the second fiber layer. According to this aspect, the non-skin surface of the top sheet in the area where the convex portion is arranged is located closer to the skin than the non-skin surface of the surrounding top sheet, and is located closer to the skin than the surrounding area. It is raised against the parts. When the convex portion rubs against the body, the fibers of the first fiber layer and the fibers of the second fiber layer may come off due to the rubbing. At this time, unfused cellulose fibers are easier to escape than fused thermoplastic resin fibers. Since a space is formed between the top sheet and the non-skin side member in the area where the convex part is arranged, when the cellulose fibers are pulled out due to rubbing between the skin and the convex parts, the cellulose fibers are easily guided into the space. Therefore, it is possible to suppress the discomfort caused by the cellulose fibers exposed from the fiber layer coming into contact with the skin.

The invention according to aspect 7 may have the following features in the invention according to any one of aspects 1 to 5. The non-skin surface of the top sheet in the region where the convex portion is arranged is at the same position in the thickness direction as the non-skin surface of the surrounding top sheet, and is at a position that is less than the non-skin surface of the surrounding top sheet. It is located on the skin side. According to this aspect, the non-skin surface of the top sheet in the region where the convex portion is arranged is not raised toward the skin side with respect to the surroundings, so that the transfer of body fluids from the top sheet to the non-skin side member is facilitated. This can improve the transfer of body fluids to the non-skin side. In addition, since the non-skin surface of the top sheet in the region where the convex portions are arranged is not raised toward the skin side with respect to the surroundings, the convex portions are less likely to be crushed during use of the absorbent article, and the shape of the convex portions is Easy to maintain.

The invention according to aspect 8 may have the following features in the invention according to any one of aspects 1 to 7. The first fiber layer contains thermoplastic resin fibers in a proportion of 90% to 100% by weight. According to this aspect, 90% by weight or more of the first fiber layer is thermoplastic resin fibers, which suppresses stickiness to the skin and keeps the skin surface of the top sheet dry compared to a form containing a large amount of cellulose fibers. can be kept. Furthermore, 90% by weight or more of the first fiber layer is thermoplastic resin fiber, and compared to a form in which the first fiber layer contains a large amount of cellulose fiber, no cellulose fiber is arranged on the skin surface of the top sheet, Since the probability of direct contact between cellulose fibers and the skin is low, fuzzing of cellulose fibers can be suppressed.

The invention according to aspect 9 may have the following features in the invention according to any one of aspects 1 to 8. The thickness of the first fiber layer is greater than or equal to the thickness of the second fiber layer. According to this aspect, the thickness of the first fiber layer is large, and the distance between the second fiber layer mainly composed of cellulose fibers and the skin can be ensured. Therefore, liquid residue on the skin surface of the top sheet can be suppressed, and the skin surface of the top sheet can be kept dry. Further, since the first fiber layer mainly includes thermoplastic resin fibers, body fluids drawn into the first fiber layer can be quickly transferred to the non-skin side, and liquid drainage can be improved.

The invention according to aspect 10 may have the following features in the invention according to any one of aspects 1 to 9. The second fiber layer is arranged on the non-skin surface of the top sheet. The cellulose fibers of the second fiber layer are more difficult to join by fusion than thermoplastic resin fibers, and therefore fibers are likely to come off. However, according to this aspect, the bonding strength between the second fiber layer and the non-skin side member is relatively high, and the bonding can suppress the cellulose fibers from coming off.

The invention according to aspect 11 may have the following features in the invention according to any one of aspects 1 to 9. The top sheet has a third fiber layer located on the non-skin side of the second fiber layer and arranged on the non-skin surface of the top sheet. The weight ratio of thermoplastic resin fibers in the third fiber layer is higher than the weight ratio of thermoplastic resin fibers in the second fiber layer. According to this aspect, the third fiber layer is arranged on the non-skin side of the second fiber layer, and the weight ratio of thermoplastic resin fibers in the third fiber layer is high, so that body fluids drawn into the second fiber layer are absorbed. Easy to pull into the third fiber layer side. In particular, if the weight ratio of the thermoplastic resin fibers in the third fiber layer is high and the thickness of the third fiber layer is relatively low, the fiber density of the third fiber layer will be high and the ability to draw in body fluids will be improved. You can improve. It is possible to further suppress liquid residue on the skin surface of the top sheet and keep the skin surface of the top sheet dry. In addition, since the first fiber layer and the third fiber layer, which have a high weight ratio of thermoplastic resin fibers, are arranged on the skin surface and non-skin surface of the top sheet, the thermoplastic resin fibers are fused to form both sides of the top sheet. The strength of the top sheet is improved, and the functions of the top sheet (body fluid attraction, etc.) can be maintained. Further, by forming fused portions of fibers on both sides of the topsheet, it is possible to suppress the fibers from coming off from the topsheet.

The invention according to aspect 12 may have the following features in the invention according to any one of aspects 1 to 11. The absorbent article has a front-back direction and a width direction perpendicular to the front-back direction. The bonding strength of the first fiber layer and the second fiber layer along the width direction is higher than the bonding strength of the first fiber layer and the second fiber layer along the front-rear direction. When worn, absorbent articles are subjected to forces from various directions, such as being pinched by the legs while sitting or being pulled by the movement of the legs while walking. At this time, the absorbent article is more susceptible to force along the width direction than force along the front-rear direction. Since the bonding strength between the first fiber layer and the second fiber layer in the width direction is high, it is possible to prevent the first fiber layer and the second fiber layer from unintentionally peeling off due to external force. In addition, since the bonding strength of the first fiber layer and the second fiber layer in the front-rear direction is low, when the first fiber layer rubs against the skin, the first fiber layer and the second fiber layer do not move in the front-rear direction. By partially adhering weakly or peeling off, the first fiber layer can easily follow the skin and improve the feel.

The invention according to aspect 13 may have the following features in the invention according to any one of aspects 1 to 12. The absorbent article has a front-back direction and a width direction perpendicular to the front-back direction. The non-skin side member is a core wrap sheet that covers the skin side of the absorbent core. The bonding strength of the core wrap sheet and the absorbent core along the width direction is lower than the bonding strength of the first fiber layer and the second fiber layer along the width direction. Absorbent articles are more susceptible to forces along the width direction than forces along the front-rear direction. At this time, the skin side of the absorbent article is more likely to receive force from the legs than the non-skin side, and the shape of the absorbent article in a cross-sectional view along the width direction is such that the widthwise length of the skin side is on the non-skin side. The shape is a trapezoid or triangle that is shorter than the length in the width direction. Since the bonding strength along the width direction of the first fiber layer and the second fiber layer located on the skin side is high, the first fiber layer and the second fiber layer may unintentionally peel off due to external force. can be suppressed. Further, even if the bonding strength between the core wrap sheet and the absorbent core located on the non-skin side is relatively low, the external force received is low and the bonded state can be maintained.

The invention according to aspect 14 may have the following features in the invention according to any one of aspects 1 to 13. It has a side sheet that covers the sides of the top sheet. A portion of the side sheet is joined to a liquid-impermeable back sheet disposed on the non-skin side of the absorbent core. The bonding strength between the top sheet and the side sheet is higher than the bonding strength between the first fiber layer and the second fiber layer. According to this aspect, the bonding strength between the top sheet and the side sheet is relatively high. At least a portion of the side sheet is joined to the back sheet. Therefore, even if the first fiber layer and the second fiber layer delaminate and follow the body, displacement of the entire absorbent article can be suppressed via the side sheet.

The invention according to aspect 15 may have the following features in the invention according to any one of aspects 1 to 14. The cellulose fibers are rayon fibers, and are dispersed throughout the second fiber layer. Rayon fibers particularly easily absorb sweat in addition to excreta such as menstrual blood, and can improve sweat absorption performance. Since the rayon fibers are dispersed over the entire surface of the top sheet, sweat can be absorbed over the entire surface of the top sheet. In addition, since the cellulose fibers are not present in the form of fiber lumps in the second fiber layer, but are dispersed throughout the entire layer, there is less variation in the basis weight of the fibers in the nonwoven fabric. , a nonwoven fabric with good texture can be obtained.

(2) Method for manufacturing absorbent article and nonwoven fabric for absorbent article according to embodiment Hereinafter, a method for manufacturing absorbent article 1 and nonwoven fabric for absorbent article according to the embodiment will be described with reference to the drawings. In addition, in the description of the following drawings, the same or similar parts are given the same or similar symbols. However, it should be noted that the drawings are schematic and the ratio of each dimension is different from the actual one. Therefore, specific dimensions etc. should be determined with reference to the following explanation. Furthermore, the drawings may include portions with different dimensional relationships and ratios. Further, in the cross-sectional view, each component is shown separated for convenience of explanation, but in an actual product, each component is in contact with each other. The absorbent article 1 may be an absorbent article such as a sanitary napkin, a panty liner, an incontinence pad, a fecal pad, a disposable diaper, a shorts-type napkin, or the like. The absorbent article 1 may be an article that is used by being attached to a wearing article such as underwear, or may be an absorbent article that is used without being attached to a wearing article. The absorbent article 1 of the embodiment is a sanitary napkin.

FIG. 1 is a plan view of the absorbent article 1 viewed from the skin side T1. FIG. 2 is a cross-sectional view taken along line AA shown in FIG. FIG. 3 is a schematic cross-sectional view of the top sheet 10. FIG. 3(A) is a diagram schematically showing a cross section of the top sheet in which the convex portions 18 and the concave portions 19 are not formed. FIG. 3(B) is a diagram schematically showing a cross section of the first form of the top sheet in which the convex portions 18 and the concave portions 19 are formed. FIG. 3(C) is a diagram schematically showing a cross section of the second form of the top sheet in which the convex portions 18 and the concave portions 19 are formed. Here, the "skin side" corresponds to the side facing the wearer's skin during use. "Non-skin side" corresponds to the side that is turned away from the wearer's skin during use. The absorbent article 1 has a front-back direction L, a width direction W, and a thickness direction T that are orthogonal to each other. In the front-rear direction L of the absorbent article 1, the side that contacts the user's lower abdomen is referred to as the "front side", and the side that contacts the user's buttocks is referred to as the "rear side".

Note that the outer portion in the present invention is a portion that occupies a certain range in the width direction W including the outer edge in the width direction W, and the outer edge is the outer edge in the width direction W. Note that the outer edge of a component that occupies a certain range in the front-rear direction is an edge that connects points located on the outer side of the component in the width direction over the entire component. The inner part in the present invention is a part occupying a certain range in the width direction W including the inner edge in the width direction W, and the inner edge is the inner edge in the width direction W. Note that the inner edge of a component that occupies a certain range in the front-rear direction is an edge that connects points located on the inner side of the component in the width direction over the entire component. Further, the front end portion and the rear end portion in the present invention are portions occupying a certain range in the front-rear direction L including the edge in the front-rear direction L, and the front end edge and the rear end edge are edges in the front-rear direction L. The outer edge includes a front edge and a rear edge, and the outer edge includes a front edge and a rear edge. Moreover, the inner side is a side that includes the inner edge and extends along the front-rear direction L. The outer side is a side that includes the outer edge and extends along the front-rear direction L. In addition, in this specification, the term "along the front-back direction L" means a direction with an angle of less than 45 degrees with respect to the front-back direction L, and the term "along the width direction W" It means a direction having an angle of less than 45° with respect to the width direction W.

The absorbent article 1 has a front region S1, a rear region S2, and a crotch region S3. The crotch region S3 is a region located under the crotch of the wearing article when the absorbent article 1 is attached to the wearing article, and between the wearer's legs. The front side region S1 is located in front of the crotch region S3. The front edge of the front side region S1 defines the front edge of the absorbent article 1. The rear region S2 is located further back than the crotch region S3. The rear edge of the rear region S2 defines the rear edge of the absorbent article 1. In the case of an absorbent article having wings, the crotch region S3 may be a region where the wings are provided, and in the case where the absorbent core has a constricted portion that is constricted inward in the width direction, the constricted portion may be a region provided with the wings. It may be a provided area. Alternatively, the crotch region S3 may be a region located in the center of a region obtained by dividing the absorbent article into three equal parts in the front-rear direction L.

The absorbent article 1 has at least an absorbent core 31, a top sheet 10, and a back sheet 20. The absorbent article 1 has a vertically long shape. The top sheet 10 is a sheet that comes into contact with the wearer's skin. The top sheet 10 is a liquid permeable sheet. The top sheet 10 may be configured to cover the entire skin surface of the absorbent article 1 with one sheet as in this embodiment, or may include a center sheet that covers the center of the absorbent core 31 in the width direction W; It may also include a side seat arranged on the outer side of the center seat in the width direction W. The top sheet 10 of this embodiment is made of a nonwoven fabric manufactured by a manufacturing method described below. The top sheet 10 will be explained in detail later.

The back sheet 20 is arranged on the non-skin side T2 than the absorbent core 31, and is a liquid-impermeable sheet. The back sheet 20 is a liquid-impermeable sheet. The back sheet 20 may be a polyethylene sheet, a laminated nonwoven fabric mainly made of polypropylene, a breathable resin film, spunbond, or a sheet in which a breathable resin film is bonded to a nonwoven fabric such as spunlace.

The absorbent core 31 constitutes an absorbent body. The absorbent core 31 may be constructed of an absorbent material that absorbs liquid. The absorbent material constituting the absorbent core 31 can be formed from, for example, hydrophilic fibers, pulp, and super absorbent polymers (SAP). As shown in FIG. 2, the absorbent body may have a core wrap sheet 32 that covers the absorbent core 31, or may not have a core wrap sheet in a modified example.

The absorbent article 1 has a non-skin side member 40 that comes into contact with the non-skin side of the top sheet 10. The non-skin side member 40 is a member that comes into contact with the non-skin side of the top sheet 10, and in this embodiment is configured by the core wrap sheet 32. Examples of the non-skin side member 40 include a second sheet and an absorbent body (core wrap sheet). In addition, in the form in which a plurality of members contact the non-skin side of the top sheet 10, each of the plurality of members may constitute the non-skin side member 40. The top sheet 10 and the non-skin side member 40 may be bonded using an adhesive or the like, or may be overlapped without being bonded.

The absorbent article 1 of the present embodiment is configured to maintain the performance of the absorbent article while suppressing a decrease in texture. will be explained in detail. The top sheet 10 includes a first fiber layer 11 disposed on the skin surface (the surface that touches the wearer's skin) of the top sheet, and a second fiber layer 12 that contacts the non-skin surface of the first fiber layer 11. It is a non-woven fabric with The nonwoven fabric may be a nonwoven fabric obtained by an air-through method, as in the manufacturing method described later, or may be a nonwoven fabric obtained by another method. The top sheet 10 only needs to include the first fiber layer 11 and the second fiber layer 12, and may be composed of only the first fiber layer 11 and the second fiber layer 12. The third fiber layer 13 may be included as shown in FIG.

The top sheet 10 of this embodiment is a nonwoven fabric manufactured by an air-through method, and has a first fiber layer 11, a second fiber layer 12, and a third fiber layer 13. As shown in FIG. 3(A), the first fiber layer 11, the second fiber layer 12, and the third fiber layer 13 are laminated in the thickness direction T. The air-through method is an example of a method for producing a nonwoven fabric, and includes a hot air penetration step in which a web is formed by laminating fibers and hot air (for example, at 100° C. or higher) is passed through the web. Note that the method for manufacturing the top sheet 10 will be described in detail later.

The first fiber layer 11 may contain thermoplastic resin fibers 51 in a proportion of 90% to 100% by weight based on the total weight of the first fiber layer 11. The thermoplastic resin fiber 51 is made of an ester polymer, an olefin polymer, an amide polymer, an acrylic polymer, a vinyl alcohol polymer, a copolymer containing these as main components, or a copolymer containing these as main components. Examples include blends consisting of a combination of polymers. When the weight percent of the thermoplastic resin fibers 51 is 90% or more and less than 100%, the first fiber layer 11 may include cellulose fibers such as rayon as fibers other than the thermoplastic resin fibers 51. Note that the ratio of fibers constituting the fiber layer can be calculated by pulling out a predetermined number (for example, 100 fibers) of fibers from the surface of the nonwoven fabric and calculating the weight ratio of the pulled out fibers. 90% by weight or more of the first fiber layer 11 is thermoplastic resin fiber 51, and compared to a form in which the first fiber layer 11 contains a large amount of cellulose fibers 52, stickiness to the skin is suppressed, and the top sheet 10 is less sticky to the skin. Can keep surfaces dry. Moreover, since the first fiber layer 11 mainly includes the thermoplastic resin fibers 51, the body fluid drawn into the first fiber layer 11 can be quickly transferred to the non-skin side, and the liquid drainage can be improved. Furthermore, 90% by weight or more of the first fiber layer is thermoplastic resin fiber 51, and the first fiber layer 11 contains many cellulose fibers 52. is not arranged, and the probability that the cellulose fibers come into direct contact with the skin is low, thereby suppressing fuzzing of the cellulose fibers 52.

The second fiber layer 12 includes thermoplastic resin fibers 51 and cellulose fibers 52. The thermoplastic resin fibers 51 can be the same as the thermoplastic resin fibers 51 of the first fiber layer 11. As the cellulose fiber 52, natural fibers such as hemp; regenerated fibers such as viscose rayon, cupro, and solvent-spun cellulose fibers (for example, Lenzing Glyocel (registered trademark) and Tencel (registered trademark)) can be used. Note that the ratio of the thermoplastic resin fibers 51 to the cellulose fibers 52 in the second fiber layer 12 is not particularly limited, but preferably, the ratio of the thermoplastic resin fibers 51 to the cellulose fibers 51 is based on the total weight of the second fiber layer 12. 30 to 90% by weight, and the cellulosic fibers 52 may be 10 to 70% by weight. Since the second fiber layer 12 contains cellulose fibers 52 in an amount of 10% by weight or more, the sweat absorption performance of the nonwoven fabric can be improved. Further, since the second fiber layer 12 has 30% or more of thermoplastic resin fibers 51, the thermoplastic resin fibers 51 are mixed in the cellulose fibers, and the sheet strength of the second fiber layer 12 can be maintained. Can be done.

The third fiber layer 13 contains thermoplastic resin fibers 51 in a proportion of 90% to 100% by weight based on the total weight of the third fiber layer 13. The thermoplastic resin fibers 51 can be the same as the thermoplastic resin fibers 51 of the first fiber layer 11. When the weight percent of the thermoplastic resin fibers 51 is 90% or more and less than 100%, the third fiber layer 13 may include cellulose fibers such as rayon as fibers other than the thermoplastic resin fibers 51.

The basis weight of the fibers in the first fiber layer 11 may be 9 g/m ² or more and 18 g/m ² or less, and the basis weight of the fibers in the second fiber layer 12 may be 9 g/m ² or more and 18 g/m ² or less. The basis weight of the fibers of the third fiber layer 13 may be 6 g/m ² or more and 12 g/m ² or less. The top sheet 10 of this embodiment is configured as follows. The first fiber layer 11 contains 100% by weight of thermoplastic resin fibers 51, and the basis weight of the first fiber layer 11 as a whole is 12 g/m ² . The second fiber layer 12 contains thermoplastic resin fibers 51 and cellulose fibers 52 in an amount of 50% by weight each, and the basis weight of the second fiber layer 12 as a whole is 12 g/m ² . The third fiber layer 13 contains 100% by weight of thermoplastic resin fibers 51, and the basis weight of the third fiber layer 13 as a whole is 9 g/m ² .

The bonding strength between the first fiber layer 11 and the second fiber layer 12 is lower than the bonding strength between the top sheet 10 and the non-skin side member 40. The bonding strength between the top sheet 10 and the non-skin side member 40 is the bond strength between the fiber layer forming the non-skin side of the top sheet 10 and the non-skin side member 40. For example, in a form in which the third fiber layer 13 constitutes the non-skin side of the top sheet 10 as in the present embodiment, the bonding strength between the third fiber layer 13 and the non-skin side member 40 is In the case where the second fiber layer 12 constitutes the non-skin side of the top sheet 10, it is the bonding strength between the second fiber layer 12 and the non-skin side member 40. The first fiber layer 11 and the second fiber layer 12 may be joined by intersecting fibers or fusion of fibers, instead of being joined by an adhesive. On the other hand, the top sheet 10 and the non-skin side member 40 may be joined by an adhesive or heat fusion using a compressed part or the like. Furthermore, when comparing the bonding strength, the strength when peeled in the same direction can be compared, and evaluation can be performed, for example, by the following method. (1) Color cellulose fibers such as rayon fibers and check the interlayer thickness between the first fiber layer and the second fiber layer. (2) Prepare another nonwoven fabric from the same lot (80 mm in peeling direction x 25 mm in width direction). Peel off the interlayer thickness confirmed in (1) by hand to create a 30 mm gripping part. (3) Set the conditions for the constant speed extension type tensile tester (Shimadzu Autograph). - Conditions: Peel test mode - Grasp interval 30 mm - Chuck interval 50 mm - Tensile speed 100 mm/min (4) Measurement is performed by holding the upper and lower layers between the upper and lower chucks of the tensile testing machine. (1) Regarding the peel strength between the top sheet and the non-skin side member, since the interlayer can be easily distinguished, the above (1) is omitted and the peel strength is measured using the same procedure as (2) to (4). As for the samples, n=5 were measured and the average values were compared. In addition, if the sample cannot be collected with the specified dimensions (width direction and peeling direction), evaluate it by collecting it with measurable dimensions, convert the evaluation results to a length in the width direction of 25 mm, and compare. shall be taken as a thing.

According to this aspect, the second fiber layer 12 located on the non-skin side T2 than the first fiber layer 11 includes cellulose fibers 52. Since the cellulose fibers 52 retain body fluids, the body fluid absorption performance can be improved. Moreover, the second fiber layer 12 is sandwiched between the first fiber layer 11 and the third fiber layer 13, and is difficult to come into direct contact with the skin. The cellulose fibers 52 are arranged in the second fiber layer 12, which is difficult to come into direct contact with the skin. Therefore, the cellulose-based fibers 52 of the second fiber layer 12 retain body fluids, thereby maintaining the absorption performance of body fluids, while suppressing stickiness to the skin caused by the cellulose-based fibers 52 retaining the body fluids coming into contact with the skin. can. In order to suppress stickiness to the skin, the first fiber layer 11 preferably does not contain cellulose fibers 52. Furthermore, in order to quickly transfer body fluids to the absorbent body without being retained in the second fiber layer 12, it is preferable that the third fiber layer 13 also not contain cellulose fibers 52.

Since the bonding strength between the first fiber layer 11 and the second fiber layer 12 is relatively low, when the top sheet 10 rubs against the skin, the first fiber layer 11 tends to follow and the feel of the top sheet 10 decreases. can be suppressed. In addition, in a nonwoven fabric manufactured by integrating each fiber layer, such as an air-through nonwoven fabric, fibers are arranged to bridge the first fiber layer 11 and the second fiber layer 12 by at least the intersection of the fibers, and the first fiber layer 11 Even if the bonding strength between the first fiber layer 11 and the second fiber layer 12 is relatively low, separation of the first fiber layer 11 and the second fiber layer 12 can be suppressed, and the performance of the nonwoven fabric can be maintained. Since the bonding strength between the top sheet 10 and the non-skin side member 40 is relatively high, delamination between the top sheet 10 and the non-skin side member 40 is prevented, and positional displacement between the top sheet 10 and the non-skin side member 40 is suppressed. Moreover, it is possible to ensure the transferability of body fluids. Therefore, the absorbent performance of the absorbent article 1 can be maintained.

A first fiber layer 11 and a third fiber layer 13 are arranged on the outer surface (skin-side surface and non-skin-side surface) of the top sheet 10, respectively. The cellulose fibers 52 are more difficult to heat-seal than the thermoplastic resin fibers 51, and may easily come off or become fluffy in the state of a nonwoven fabric. On the other hand, the thermoplastic resin fibers 51 are easily thermally fused by being heated during the production of the nonwoven fabric, are difficult to come off in the nonwoven fabric state, and are difficult to fuzz. Since the first fiber layer 11 touches the wearer's skin, when the nonwoven fabric rubs against the skin, fuzzing of the cellulose fibers 52 is suppressed, and a good feel can be maintained.

The first fiber layer 11 and the third fiber layer 13, which have a high proportion of thermoplastic resin fibers 51, have a high liquid drawing property compared to the second fiber layer 12, which has a high proportion of cellulose fibers 52. Since the first fiber layer 11 is arranged on the wearer's skin side (the side from which body fluids are discharged), body fluids can be quickly drawn into the top sheet 10, suppressing the residual fluid, and keeping the surface of the top sheet 10 dry. can be kept. Further, the third fiber layer 13 is arranged on the surface that comes into contact with the non-skin side member 40. The third fiber layer 13 contains a large amount of thermoplastic resin fibers 51, and has higher liquid transferability than the second fiber layer 12. Therefore, the transferability of the liquid from the top sheet 10 to the non-skin side member 40 can be ensured.

The cellulose fibers 52 of the second fiber layer 12 may be rayon fibers. The cellulose fibers 52 do not exist in the form of fiber lumps within the nonwoven fabric, but may be dispersed and arranged throughout the second fiber layer 12. That is, the cellulose fibers may be distributed continuously and in layers in the planar direction (front-back direction L and width direction). Rayon fibers particularly easily absorb sweat in addition to excreta such as menstrual blood, and can improve sweat absorption performance. Since the rayon fibers are dispersed over the entire surface of the top sheet 10, sweat can be absorbed over the entire surface of the top sheet 10. In addition, since the cellulose fibers 52 are not present in the form of fiber lumps in the nonwoven fabric, but are dispersed throughout the nonwoven fabric, there is little variation in the basis weight of the fibers in the nonwoven fabric. A nonwoven fabric with good texture can be obtained. In addition, compared to natural fibers such as cotton, rayon fibers can control the fiber length, so small pieces of natural fibers are less likely to remain on the production line, and the fabric has a better texture than other natural fibers. Nonwoven fabrics can be stably produced. The fiber length of rayon may be 20 mm or more and 60 mm or less, preferably 35 mm or more and 50 mm or less.

The weight ratio of the thermoplastic resin fibers in the third fiber layer 13 may be higher than the weight ratio of the thermoplastic resin fibers in the second fiber layer 12. The third fiber layer 13 is arranged on the non-skin side T2 of the second fiber layer 12, and since the weight ratio of the thermoplastic resin fibers 51 in the third fiber layer 13 is high, body fluids drawn into the second fiber layer 12 are absorbed. It is easy to draw it into the third fiber layer 13 side. In particular, if the weight ratio of the thermoplastic resin fibers in the third fiber layer is high and the thickness of the third fiber layer is relatively low, the fiber density of the third fiber layer will be high and the ability to draw in body fluids will be improved. You can improve. Liquid residue on the skin surface of the top sheet 10 can be further suppressed, and the skin surface of the top sheet 10 can be kept dry. Since the first fiber layer 11 and the third fiber layer 13 having a high weight ratio of thermoplastic resin fibers 51 are arranged on the skin surface and the non-skin surface of the top sheet 10, the top sheet is formed by fusing the thermoplastic resin fibers. The strength of both sides of the top sheet 10 is improved, and the functions of the top sheet 10 (ability to draw in body fluids, etc.) can be maintained. Further, by forming fused portions of fibers on both sides of the top sheet 10, it is possible to suppress the fibers from coming off from the top sheet.

Based on the total weight of the top sheet 10, the top sheet 10 may contain thermoplastic resin fibers 51 in a proportion of 50% by weight or more and less than 90% by weight. Further, the top sheet 10 may contain cellulose fibers 52 in a proportion of 10% by weight or more and 40% by weight or less, based on the total weight of the topsheet 10.

The bonding strength of the first fiber layer 11 and the second fiber layer 12 along the width direction W may be higher than the bonding strength of the first fiber layer 11 and the second fiber layer 12 along the front-rear direction L. When worn, the absorbent article 1 is subjected to forces from various directions, such as being pinched by the legs while sitting or being pulled by the movement of the legs while walking. At this time, the absorbent article 1 is more susceptible to the force along the width direction W than the force along the front-rear direction L. Since the bonding strength of the first fiber layer 11 and the second fiber layer 12 in the width direction W is high, unintentional peeling of the first fiber layer 11 and the second fiber layer 12 due to external force is suppressed. can. In addition, since the bonding strength of the first fiber layer 11 and the second fiber layer 12 in the front-rear direction L is low, when the first fiber layer 11 rubs against the skin, the first fiber layer 11 and the second fiber layer By partially adhering or peeling off the layer 12 in the front-rear direction L, the first fiber layer 11 can easily follow the skin, and the touch can be improved.

The non-skin side member 40 is a core wrap sheet 32, and the bonding strength of the core wrap sheet 32 and the absorbent core 31 in the width direction W is the same as that of the first fiber layer 11 and the second fiber layer 12 in the width direction. It may be lower than the bonding strength. The absorbent article 1 is more susceptible to force along the width direction W than force along the front-rear direction L. At this time, in the absorbent article 1, the skin side T1 is more likely to receive force from the legs than the non-skin side T2. The shape of the absorbent article 1 in a cross-sectional view along the width direction W is a trapezoid or a triangle in which the length of the skin side T1 in the width direction W is shorter than the length of the non-skin side T2 in the width direction W. Since the bonding strength along the width direction W between the first fiber layer 11 and the second fiber layer 12 located on the skin side T1 within the top sheet 10 is high, the first fiber layer 11 and the second fiber layer 12 may unintentionally bond against external forces. Peeling of the two fiber layers 12 can be suppressed. Moreover, even if the bonding strength along the width direction W between the core wrap sheet 32 and the absorbent core 31 located on the non-skin side T2 is relatively low, the external force received is low and the bonded state can be maintained.

The top sheet 10 and the non-skin side member 40 may be bonded by an adhesive 35 (see FIG. 3) arranged at intervals in the plane direction. The distance between the adhesives 35 that join the top sheet 10 and the non-skin side member 40 may be shorter than the average fiber length of the fibers arranged on the non-skin side of the top sheet 10. According to this aspect, the fibers arranged on the non-skin surface of the top sheet 10 are likely to be arranged overlapping the adhesive 35 and easily adhered by the adhesive 35. Therefore, the fibers arranged on the non-skin surface of the topsheet 10 are difficult to come off from the nonwoven fabric, and easily remain within the topsheet 10, so that the performance of the absorbent article can be maintained. In addition, the fibers are not bonded to each other at intervals between the adhesives 35, and the degree of freedom in deformation of the fibers is increased. Therefore, the followability of the top sheet 10 can be further improved while suppressing delamination between the first fiber layer 11 and the second fiber layer 12. In addition, since the fibers have a high degree of freedom in deformation, it is possible to suppress the cutting of the fibers and prevent the cut fibers from becoming fluffy and causing a deterioration in the feel of the fabric. In the present embodiment, the third fiber layer 13 is arranged on the non-skin surface of the top sheet 10, and the third fiber layer 13 contains 100% by weight of thermoplastic resin fibers. Therefore, the distance between the adhesives 35 is configured to be shorter than the average fiber length of the thermoplastic resin fibers 51. In addition, in the form in which the interval between the adhesives 35 changes, it is sufficient that the average fiber length is shorter than the interval between at least some of the adhesives 35. To measure the average fiber length, a predetermined number (for example, 100) of fibers are pulled out from the non-skin surface of the top sheet 10 using tweezers or the like, and the average length of the pulled out fibers is calculated.

The distance between the adhesives that join the top sheet 10 and the non-skin side member 40 may be shorter than the average fiber length of the cellulose fibers 52. The cellulose fibers 52 are more difficult to thermally fuse than the thermoplastic resin fibers, and are easier to come off than the thermoplastic resin fibers 51 when formed into a nonwoven fabric. Since the distance between the adhesives is shorter than the average fiber length of the cellulose fibers 52, the cellulose fibers 52 can be bonded with the adhesive and the cellulose fibers 52 can be prevented from coming off.

In a modification, the top sheet 10 and the non-skin side member 40 may be joined by compressed parts (not shown) arranged at intervals in the plane direction. The interval between the pressed parts may be shorter than the average fiber length of the fibers arranged on the non-skin surface of the top sheet 10. According to this aspect, the fibers arranged on the non-skin surface of the top sheet are likely to be arranged overlapping the compressed portions and are likely to be adhered by the compressed portions. Therefore, the fibers arranged on the non-skin surface of the topsheet 10 are difficult to come off from the nonwoven fabric, and easily remain within the topsheet 10, so that the performance of the absorbent article can be maintained. In addition, the fibers are not joined at intervals between the compressed parts, and the degree of freedom in deforming the fibers is increased. Therefore, the followability of the top sheet 10 can be further improved while suppressing delamination between the first fiber layer 11 and the second fiber layer 12. In addition, since the fibers have a high degree of freedom in deformation, it is possible to suppress the cutting of the fibers and prevent the cut fibers from becoming fluffy and causing a deterioration in the feel of the fabric.

In the top sheet 10, the thickness of the first fiber layer 11 may be greater than or equal to the thickness of the second fiber layer 12. According to this aspect, the first fiber layer 11 is thick, and a distance between the second fiber layer 12 mainly composed of cellulose fibers 52 and the skin can be ensured. Therefore, liquid residue on the skin surface of the top sheet 10 can be suppressed, and the skin surface of the top sheet 10 can be kept dry. Moreover, since the first fiber layer 11 mainly includes the thermoplastic resin fibers 51, the body fluid drawn into the first fiber layer 11 can be quickly transferred to the non-skin side, and the liquid drainage can be improved.

In the top sheet 10, the thickness of the third fiber layer 13 may be greater than or equal to the thickness of the second fiber layer 12. According to this aspect, the thickness of the third fiber layer 13 mainly composed of the thermoplastic resin fibers 51 is large, and the transferability of bodily fluids from the top sheet 10 to the non-skin side member 40 can be improved. Further, the thickness of the first fiber layer 11 may be greater than or equal to the thickness of the third fiber layer 13. When the nonwoven fabric rubs against the skin, fluffing of the cellulose fibers 52 can be suppressed and a good texture can be maintained. Further, since the third fiber layer 13 has a relatively low thickness, it is possible to promote the transfer of body fluid from the second fiber layer 12 side to the non-skin side member 40 and suppress rewetting of the body fluid.

Note that the thicknesses of the first fiber layer 11, the second fiber layer 12, and the third fiber layer 13 are measured by the following method. (1) Freeze the absorbent article with liquid nitrogen, cut it cross-sectionally with a cutter, and wait for it to dry. (2) Soak in PAC fabric dye dissolved in water at 40-50°C for one hour, take it out and wait for it to dry naturally. (3) Since the dyed part becomes cellulose fiber, the layer containing the dyed part is identified as the second fiber layer, and both sides in the thickness direction are identified as the first fiber layer and the third fiber layer. . (4) Take an enlarged photograph of the cross section using a digital microscope VHX-7000 manufactured by Keyence Corporation, select the distance between two points for planar measurement, and measure the thickness of each fiber layer of the nonwoven fabric. (5) Measure arbitrary distances at 10 points for each nonwoven fabric, and use the average value as the thickness. In addition, when comparing the thickness of each fiber layer, the comparison is made at a position where the convex portion 18 and the concave portion 19 are not formed.

As shown in FIG. 3(B), the skin surface of the top sheet 10 has a plurality of convex portions 18 protruding toward the skin side, and a plurality of convex portions 18 that are recessed toward the non-skin side T2 between the convex portions 18. A recess 19 may be formed. The convex portion 18 may be solid and protrude toward the skin side T1. In this specification, "solid" means that there is no space where the fiber density is significantly lower than the surrounding area, which would impede the movement of liquid within the convex portion 18. If d is the difference in height between the highest part 16 where the height of the skin surface of the top sheet is highest and the deepest part 17 where the height of the skin surface of the top sheet is the lowest, then the height is d/2 from the deepest part 17. The portion that protrudes upward from the position can be called a convex portion 18, and the portion that is depressed downward can be called a concave portion 19.

In the top sheet 10, the thickness Td1 of the first fiber layer 11 in the concave portion 19 is thinner than the thickness Tc1 of the first fiber layer 11 in the convex portion 18. Here, the thickness Td1 of the first fiber layer 11 in the recess 19 is the thickness of the first fiber layer 11 in the deepest part 17, and the thickness Tc1 of the first fiber layer 11 in the convex part 18 is the thickness of the first fiber layer 11 in the highest part 16. This is the thickness of the fiber layer 11. The dimensions of the convex portion 18 include, for example, a width of 0.25 to 5 mm, a height of 0.25 to 5 mm, and a pitch of 0.5 to 10 mm. The dimensions of these convex portions 18 can be measured from a planar photograph or a planar image by observing the top sheet 10 in a non-pressurized state under magnification using a magnifying observation means such as a scanning electron microscope.

The plurality of convex portions 18 are formed as a plurality of ridges extending continuously in the front-rear direction L, and the plurality of recesses 19 are adjacent to the ridges in the width direction W (i.e., adjacent to the ridges in the width direction W). may be formed as a plurality of grooves that extend continuously in the front-rear direction L. Because the top sheet 10 has such a ridge-groove structure, it has excellent cushioning properties in the thickness direction T, provides a good touch, and also directs excrement in the front-rear direction L where the ridges and grooves extend. can be spread along. The convex portion 18 may be formed on at least the first fiber layer 11 and the second fiber layer 12, and may be formed on the first fiber layer 11, the second fiber layer 12, and the third fiber layer 13.

The fiber density of the concave portions 19 may be higher than the fiber density of the convex portions 18. The distance between the convex portions 18 may be shorter than the average fiber length of the fibers arranged on the non-skin surface of the top sheet 10. The distance between the convex portions 18 is shorter than the average fiber length of the fibers arranged on the non-skin surface of the top sheet 10. The fibers are likely to be arranged in the recesses that are the intervals between the protrusions. The recessed portions have a relatively high fiber density, and fibers are less likely to come off. Further, since the convex portions 18 are easily in contact with the skin, while the concave portions 19 are difficult to come into contact with the skin, fibers are prevented from coming off, and the fibers are retained within the top sheet 10, thereby maintaining the performance of the absorbent article. On the other hand, the convex portion 18 has a relatively low fiber density. Therefore, there are gaps between the fibers, the cushioning properties are high, the ends of the fibers are not easily exposed to the skin surface of the top sheet 10, and deterioration of the feel due to fluffing can be suppressed. Further, in the convex portions 18, since the fiber density is low, the degree of freedom in deforming the fibers is high, and the followability of the top sheet can be further improved. In addition, since the fibers have a high degree of freedom in deformation, it is possible to suppress the cutting of the fibers and prevent the cut fibers from becoming fluffy and causing a deterioration in the feel of the fabric.

As shown in FIG. 3(B), the non-skin surface of the top sheet 10 may have a substantially flat surface structure. Therefore, the non-skin surface of the top sheet 10 in the area where the convex portion 18 is arranged is at the same position in the thickness direction as the non-skin surface of the surrounding top sheet, and is on the non-skin side of the non-skin surface of the surrounding top sheet 10. May be located in Since the non-skin surface of the top sheet 10 in the area where the convex portions 18 are arranged is not raised toward the skin side with respect to the surroundings, the transfer of body fluids from the top sheet 10 to the non-skin side member 40 is further promoted, and the body fluids are Migration to the non-skin side can be improved. In addition, since the non-skin surface of the top sheet in the region where the convex portions 18 are arranged is not raised toward the skin side with respect to the surroundings, the convex portions 18 are less likely to be crushed during use of the absorbent article, and the convex portions 18 are Easy to maintain shape.

As another example, as shown in FIG. 3(C), the convex portion 18 may have a hollow portion instead of being solid and protruding toward the skin side T1. The non-skin surface of the top sheet 10 in the area where the convex portions 18 are arranged may be located closer to the skin side T1 than the surrounding non-skin surfaces of the top sheet 10. The non-skin surface of the top sheet 10 in the region where the convex portion 18 is arranged is located on the skin side T1 from the non-skin surface of the surrounding top sheet 10, and is raised from the non-skin side member 40 compared to the surrounding area. ing. The convex portion 18 may be formed on the first fiber layer 11 and the second fiber layer 12, and may also be formed on the third fiber layer 13. When the convex portion 18 rubs against the body, the fibers of the first fiber layer 11 and the fibers of the second fiber layer 12 may come off due to the rubbing. At this time, the unfused cellulose fibers 52 are easier to escape than the thermoplastic resin fibers 51 that are fused. However, since a space is formed between the top sheet 10 and the non-skin side member 40 in the area where the convex portions 18 are arranged, the cellulose fibers 52 may come off due to the skin rubbing against the convex portions 18. When this happens, the cellulose fibers 52 are easily guided into the space. Therefore, it is possible to suppress the discomfort caused by the cellulose fibers 52 exposed from the fiber layer coming into contact with the skin.

The convex portion 18 and the concave portion 19 extend in the front-rear direction L and are arranged at intervals in the width direction, and are provided at the center of the top sheet 10 in the width direction W, and are located at the sides of the top sheet 10 in the width direction W. It does not have to be provided. For example, the convex portion 18 and the concave portion 19 are provided at least within a range of up to 20 mm from the center of the top sheet 10 in the width direction W, and at least within a range of up to 20 mm from the outer edge of the top sheet 10 in the width direction W. It does not have to be provided. By providing the convex portions 18 and the concave portions 19, the contact area of the top sheet 10 with the skin can be reduced. On the other hand, by providing the convex portions 18 and the concave portions 19 that extend in the front-rear direction and are spaced apart in the width direction W, the length of the top sheet in the width direction may be shortened, which may increase manufacturing costs. Therefore, the convex part 18 and the concave part 19 are provided in the part that easily comes into contact with the excretory opening (vaginal opening, urinary opening) (the center of the top sheet in the width direction W), and the convex part 18 and the recessed part 19 are provided in the part that is difficult to come into contact with the excretory opening (the outer part of the top sheet). By not providing the portion 18 and the recessed portion 19, manufacturing costs can be reduced. Furthermore, in a configuration in which the outer side of the top sheet overlaps with the side sheet, the region of the top sheet where the convex portions 18 and the recessed portions 19 are not formed can be joined to the side sheet, and the top sheet 10 and the side sheet can be joined to each other. can be stably joined.

The top sheet 10 may include a compressed portion 14, as shown in FIG. 3(B). The compression section 14 may compress at least the first fiber layer 11 and the second fiber layer 12 in the thickness direction. The compressing portions 14 of this embodiment are arranged intermittently along the front-rear direction L in the recess 19. The compressing parts 14 may be arranged at equal intervals in the front-rear direction L in the recessed part 19, or may be arranged at non-equal intervals. In the concave portions 19 adjacent to each other in the width direction W, the compressed portions 14 may be located at the same position in the front-rear direction L, or may be located at different positions. The compressed portion 14 may be formed spanning the first fiber layer 11 and the second fiber layer 12, or may be formed spanning the first fiber layer 11, the second fiber layer 12, and the third fiber layer 13. may be done. According to this aspect, it is possible to suppress the fibers of the first fiber layer 11 and the fibers of the second fiber layer 12 from coming off by the pressing part 14, and to suppress fluffing due to the fibers coming off. Moreover, the compressing part 14 is provided in a recessed part 19 that is more recessed than the convex part 18, so that it is difficult to come into direct contact with the body. Therefore, it is possible to suppress the discomfort caused by the pressing part 14 hitting the body.

Here, the basis weight, thickness, fiber density, and fineness of the nonwoven fabric constituting the top sheet are measured by the following method.
(1) Basis weight of non-woven fabric: A non-woven fabric is cut into a 5 cm x 5 cm size sample, and the mass is measured after drying in an atmosphere of 100° C. or higher. Calculate the basis weight of the sample by dividing the measured mass by the area of the sample. The average value of the basis weights of 10 samples is defined as the basis weight of the nonwoven fabric.
(2) Thickness of nonwoven fabric: Can be measured by a method similar to the method for measuring the thickness of the fiber layer described above. Specifically, the absorbent article was frozen in liquid nitrogen, cut in the cross-sectional direction with a cutter, an enlarged photograph of the cross section was taken with a digital microscope VHX-7000 manufactured by Keyence Corporation, and two points of planar measurement were taken. Select the spacing and measure the thickness of the nonwoven fabric.
(3) Fiber density of nonwoven fabric: The fiber density of the nonwoven fabric is calculated by dividing the weight of the nonwoven fabric determined by the above method by the thickness of the nonwoven fabric determined by the above method.
(4) Fiber fineness: The fiber fineness is determined by measuring the cross-sectional area of the fiber by enlarging the cross-sectional shape of the target fiber using a scanning electron microscope. Calculated from the specific gravity of the fiber components.

Next, based on FIG. 4, a method S100 for manufacturing a nonwoven fabric for absorbent articles will be described. Manufacturing method S100 is configured to obtain a nonwoven fabric that can ensure desired texture and absorption rate. FIG. 4 is a diagram schematically showing the manufacturing method S100, and MD shown in the figure indicates the transport direction, and the products are manufactured in order along the MD direction. Note that in this embodiment, the nonwoven fabric obtained by the manufacturing method is used for the top sheet 10. The manufacturing method S100 is an air-through method and includes at least a web forming step S101 and a hot air penetration step S105.

The web forming step S101 includes a first fiber layer 11 containing thermoplastic resin fibers 51 in a ratio of 90% to 100% by weight, a second fiber layer 12 containing thermoplastic resin fibers 51 and cellulose fibers 52, and a heat treatment. A third fiber layer 13 containing plastic resin fibers 51 in a proportion of 90% to 100% by weight is laminated in the thickness direction T to form a web. In this embodiment, the fibers forming the third fiber layer 13 are supplied from a third supply section (not shown), and the fibers forming the third fiber layer 13 are laminated. Therefore, the third fiber layer 13 is in contact with the conveying surface 121 of the conveying device 120. Next, the fibers forming the second fiber layer 12 are supplied from a second supply section (not shown), and the fibers forming the second fiber layer 12 are laminated. The second fiber layer 12 is laminated on the third fiber layer 13. Therefore, the third fiber layer 13 is arranged between the conveyance surface 121 and the second fiber layer 12, and the second fiber layer 12 is not in direct contact with the conveyance surface 121. Next, the fibers forming the first fiber layer 11 are supplied from a first supply section (not shown), and the fibers forming the first fiber layer 11 are laminated. The first fiber layer 11 is laminated on the second fiber layer 12. Therefore, the third fiber layer 13, the second fiber layer 12, and the first fiber layer 11 are stacked in this order from the conveying surface 121 upward. In this state, each fiber is only laminated, not joined to each other, and can be easily separated.

The hot air penetration step S105 is a step after the web forming step S101, and hot air is passed through the web in a state where the third fiber layer 13 of the web is placed facing the conveyance surface 121 having air permeability. In the hot air penetration step S105, hot air is applied from the first fiber layer 11 side toward the conveying surface 121 in a state in which the first fiber layer 11, the second fiber layer 12, and the third fiber layer 13 are laminated. The conveyance surface 121 has a shape such as a mesh having voids to ensure air permeability. The hot air passes through the web and through the gaps in the conveying surface 121. The hot air is hot air at a predetermined temperature (for example, 100° C. or higher), and as the hot air passes through the web, the fibers in the web intersect with each other, making each fiber layer familiar. Therefore, in the state after the hot air penetration step S105, each fiber and each fiber layer partially intersect with each other and become difficult to separate.

The manufacturing method S100 may include an interlacing step S103 after the web forming step S101 and before the hot air penetration step S105. In the intertwining step S103, a high temperature fluid is sprayed onto the web to intertwine the fibers of the web. Furthermore, the fused portions 15 may be formed at the intersections of the thermoplastic resin fibers 51 due to the heat generated during intertwining.

The manufacturing method S100 may include an unevenness forming step (not shown) after the hot air penetration step S105. In the unevenness forming step, the web is passed between a pair of gear rolls (not shown), the web is pressed, and at least one surface of the first fiber layer 11 and the third fiber layer 13 is formed outward in the thickness direction T. A plurality of convex portions 18 that protrude in the direction toward the wafer, and a plurality of concave portions 19 (see FIG. 3) that are recessed inward in the thickness direction between the convex portions 18 (see FIG. 3) are formed. Note that the unevenness forming step may be performed continuously after the hot air penetration step S105, or may be performed as a separate step after being wound up as a nonwoven fabric. The above-mentioned nonwoven fabric can be obtained by such manufacturing method S100.

According to the manufacturing method S100 of the present embodiment, the third fiber layer 13 of the web is placed facing the conveying surface 121, and hot air is applied in this state. Therefore, compared to a configuration in which the second fiber layer 12 including cellulose fibers 52 faces the conveyance surface 121, it is difficult for the cellulose fibers 52 to come into direct contact with the conveyance surface 121, and in addition, the thickness of the third fiber layer 13 Therefore, the distance between the cellulose fibers 52 and the conveyance surface 121 can be ensured. Therefore, problems such as the cellulose fibers 52 adhering to the conveying surface 121 or entering the voids of the conveying surface 121 for ensuring air permeability can be suppressed. Further, since hot air is applied with the first fiber layer 11 disposed on the front side, scattering of the cellulose fibers 52 can be suppressed. Therefore, it is possible to obtain a nonwoven fabric with a desired texture and absorption rate by the air-through method while suppressing problems such as the cellulose fibers 52 scattering or adhering to the conveying surface.

In the web forming step S101, the basis weight of the thermoplastic resin fibers 51 of the first fiber layer 11 may be made higher than the basis weight of the cellulose fibers 52 of the second fiber layer 12. According to this aspect, a distance between the surface to which hot air is applied and the second fiber layer 12 can be secured, and scattering of the cellulose fibers 52 can be further suppressed. Further, in an absorbent article in which the first fiber layer 11 is arranged on the surface that contacts the skin, a distance between the second fiber layer mainly composed of cellulose fibers and the skin can be ensured. The cellulose fibers are not easily arranged on the surface that comes into contact with the skin, and when the nonwoven fabric rubs against the skin, the cellulose fibers 52 are prevented from becoming fluffy and a good texture can be maintained. In addition, in an absorbent article in which the first fiber layer 11 is disposed on the surface that contacts the skin, since the basis weight of the thermoplastic resin fibers in the first fiber layer 11 is relatively high, sweat absorption and body fluid drawing properties are improved. can be ensured and liquid residue can be suppressed. The basis weight of the thermoplastic resin fibers 51 of the first fiber layer 11 may preferably be 1.5 times or more the basis weight of the cellulose fibers 52 of the second fiber layer 12, and more preferably the The basis weight of the fibers in the second fiber layer 12 may be 2.0 times or more.

In the web forming step S101, the basis weight of the thermoplastic resin fibers 51 of the third fiber layer 13 may be made higher than the basis weight of the cellulose fibers 52 of the second fiber layer 12. According to this aspect, the distance between the conveyance surface 121 and the second fiber layer 12 can be ensured, and the cellulose fibers 52 may remain on the conveyance surface 121 or the cellulose fibers 52 can be placed in the gaps of the conveyance surface 121 to ensure air permeability. It is possible to further suppress problems caused by The basis weight of the thermoplastic resin fibers 51 of the third fiber layer 13 may preferably be 1.5 times or more the basis weight of the cellulose fibers 52 of the second fiber layer 12, and more preferably the basis weight of the thermoplastic resin fibers 51 of the third fiber layer 13. The basis weight of the cellulose fibers 52 of the second fiber layer 12 may be 2.0 times or more.

In the web forming step S101, the basis weight of the fibers of the first fiber layer 11 may be made higher than the basis weight of the fibers of the third fiber layer 13. According to this aspect, in the absorbent article 1 in which the first fiber layer 11 is arranged on the surface that contacts the skin, it is possible to ensure a distance between the second fiber layer mainly composed of cellulose fibers and the skin. The cellulose fibers are not easily arranged on the surface that comes into contact with the skin, and when the nonwoven fabric rubs against the skin, the cellulose fibers 52 are prevented from becoming fluffy and a good texture can be maintained. Further, since the basis weight of the third fiber layer 13 is relatively low, transfer of body fluid from the second fiber layer 12 side to the non-skin side member 40 can be promoted, and rewetting of the body fluid can be suppressed.

In the intertwining step S103, a high temperature fluid is sprayed onto the web to intertwine the thermoplastic resin fibers 51. The intertwining step S103 may form a fused portion 15 in which the thermoplastic resin fibers 51 are fused together. In the intertwining step S103, the number of fused parts 15 per unit area in the third fiber layer 13 may be greater than the number of fused parts 15 per unit area in the first fiber layer 11. According to this aspect, since many fused portions 15 are formed in the third fiber layer 13 facing the conveying surface 121, unfused fibers may remain on the conveying surface 121 or Problems such as unfused fibers entering the void can be suppressed. Moreover, a large number of fused parts 15 are formed in the third fibrous layer 13, which is one of the first fibrous layer 11 and the third fibrous layer 13 constituting the outer surface of the nonwoven fabric, and the fused part 15 in the other, the first fibrous layer 11, is formed. By forming a small amount of 15, both a relatively hard surface and a relatively soft surface can be formed in the nonwoven fabric. Therefore, by manufacturing an absorbent article in which the first fiber layer 11 is arranged so as to be in contact with the skin, the feel of the absorbent article can be improved. In addition, by forming many fusion points in the third fiber layer 13 that is difficult to touch the skin, it becomes easier to maintain the shape of the nonwoven fabric in areas that are less likely to rub against the skin. Therefore, twisting of the nonwoven fabric can be suppressed while maintaining the texture of the nonwoven fabric itself.

In the unevenness forming step, convex portions 18 and concave portions 19 are formed on at least one side of the web. Either the first fiber layer 11 or the third fiber layer 13 is arranged on the one side surface. The thickness of the fiber layer (first fiber layer or third fiber layer) arranged on one side is thicker than the thickness of the fiber layer (third fiber layer or first fiber layer) arranged on the other side. It's okay to be. According to this aspect, since the thickness of the fiber layer (first fiber layer or third fiber layer) on one side in which the convex portions 18 and the concave portions 19 are formed is relatively thick, a predetermined thickness can be maintained even in the concave portions, Exposure of the cellulose fibers 52 to the outer surface of the nonwoven fabric can be suppressed. In addition, compared to the fiber layer on one side, the fiber layer on the other side (the third fiber layer or the first fiber layer) is less likely to be biased due to the formation of convex portions and concave portions, and is uniform over the entire fiber layer. Easy to ensure thickness. Therefore, by reducing the thickness of the fiber layer on the other side, it is possible to suppress the weight of the fibers and reduce manufacturing costs.

In the unevenness forming step, a plurality of protrusions 18 and recesses 19 are provided extending in the front-rear direction L and spaced apart in the width direction W, and the protrusions 18 and recesses 19 are not provided on the sides of the web in the width direction W. In addition, it may be provided at the center of the web in the width direction W. That is, the convex portion 18 and the concave portion 19 extend in the front-rear direction L and are arranged at intervals in the width direction, and are provided at the center of the top sheet 10 in the width direction W. It does not have to be provided on the side. For example, the convex portion 18 and the concave portion 19 are provided at least within a range of up to 20 mm from the center of the top sheet 10 in the width direction W, and at least within a range of up to 20 mm from the outer edge of the top sheet 10 in the width direction W. It does not have to be provided. By providing the convex portions 18 and the concave portions 19, the contact area of the top sheet 10 with the skin can be reduced. On the other hand, by providing the convex portions 18 and the concave portions 19 that extend in the front-rear direction and are spaced apart in the width direction W, the length of the top sheet 10 in the width direction W may be shortened, which may increase manufacturing costs. . Therefore, the convex part 18 and the recessed part 19 are provided in the part (the center in the width direction W of the top sheet 10) that easily comes into contact with the excretory opening (vaginal opening, urinary opening), and in the part that does not easily come into contact with the excretory opening (the outer part of the top sheet 10). By not providing the convex portions 18 and concave portions 19, manufacturing costs can be reduced. Furthermore, in a configuration in which the outer side of the top sheet overlaps with the side sheet, the region of the top sheet where the convex portions 18 and the recessed portions 19 are not formed can be joined to the side sheet, and the top sheet 10 and the side sheet can be joined to each other. can be stably joined.

In the web forming step S101, the length of the first fiber layer 11 in the orthogonal direction perpendicular to the conveying direction of the web may be made longer than the length of the second fiber layer 12 in the orthogonal direction. During conveyance of the web, the first fiber layer 11 and the second fiber layer 12 are continuous in the conveyance direction MD. Since the length of the first fiber layer 11 in the orthogonal direction is longer than the length of the second fiber layer 12 in the orthogonal direction, the entire second fiber layer 12 can be covered by the first fiber layer 11. Since the second fibrous layer contains a comparatively large amount of cellulose fibers, the fibers have weak fusion properties, and if hot air is directly applied during the hot air penetration step, the cellulose fibers may curl up. However, by covering the second fiber layer 12 with the first fiber layer 11, it is possible to suppress the cellulose fibers of the second fiber layer 12 from curling up.

In the web forming step, the length of the third fiber layer in the orthogonal direction perpendicular to the conveying direction of the web may be made longer than the length of the second fiber layer in the orthogonal direction. During conveyance of the web, the third fiber layer 13 and the second fiber layer 12 are continuous in the conveyance direction MD. Since the length of the third fiber layer 13 in the orthogonal direction is longer than the length of the second fiber layer 12 in the orthogonal direction, the entire second fiber layer 12 can be covered by the third fiber layer 13. Since the second fiber layer contains a relatively large amount of cellulose fibers, the fibers have weak adhesion, and when the cellulose fibers come into contact with a conveyance surface such as a metal or resin mesh belt during the hot air penetration process, There is a risk that cellulose fibers may get caught in the voids on the conveying surface. However, by covering the second fiber layer 12 with the third fiber layer 13, it is possible to suppress the cellulose fibers of the second fiber layer 12 from being caught on the conveyance surface.

Although the present invention has been described above in detail using the embodiments described above, it is clear for those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modifications and variations without departing from the spirit and scope of the present invention as defined by the claims. Therefore, the description in this specification is for the purpose of illustrative explanation and does not have any limiting meaning on the present invention.

In a modification, the second fiber layer 12 may be arranged on the non-skin surface of the top sheet 10. That is, the top sheet 10 may have the first fiber layer 11 and the second fiber layer 12 and may not have the third fiber layer 13. According to this aspect, the cellulose-based fibers 52 of the second fiber layer 12 are more difficult to join by fusion than the thermoplastic resin fibers 51, and therefore the fibers are likely to come off. However, since the bonding strength between the top sheet 10 and the non-skin side member 40 is configured to be higher than the bonding strength between the first fiber layer 11 and the second fiber layer 12, the second fiber layer 12 and the non-skin side member 40 The bonding strength of can suppress the cellulose fibers 52 from coming off.

Additionally, in a modified example, the absorbent article may include a side sheet that covers the sides of the top sheet 10. Note that the side sheet may cover the skin side T1 of the top sheet 10, or may cover the non-skin side T2 of the top sheet 10. At least a portion of the side sheet may be joined to a liquid-impermeable back sheet disposed on the non-skin side of the absorbent core. The bonding strength between the top sheet and the side sheet may be higher than the bonding strength between the first fiber layer and the second fiber layer. According to this aspect, even if the first fibrous layer 11 and the second fibrous layer 12 delaminate and follow the body, displacement of the entire absorbent article can be suppressed via the side sheet.

Note that the entire contents of Japanese Patent Application No. 2022-126553 filed on August 8, 2022 are incorporated herein by reference.

1 : Absorbent article 10 : Top sheet 11 : First fiber layer 12 : Second fiber layer 13 : Third fiber layer 14 : Compressed part 15 : Fusion part 18 : Convex part 19 : Concave part 31 : Absorbent core 32 : Core Wrap sheet 40: Non-skin side member 51: Thermoplastic resin fiber 52: Cellulose fiber L: Front-back direction T: Thickness direction T1: Skin side T2: Non-skin side W: Width direction

Claims

a top sheet that contacts the wearer's skin;
An absorbent article comprising: a non-skin side member that comes into contact with the non-skin side of the top sheet,
The top sheet is a nonwoven fabric having a first fiber layer disposed on the skin surface of the top sheet, and a second fiber layer in contact with the non-skin surface of the first fiber layer,
The first fiber layer includes thermoplastic resin fibers,
The second fiber layer includes thermoplastic resin fibers and cellulose fibers,
The absorbent article, wherein the bonding strength between the first fiber layer and the second fiber layer is lower than the bonding strength between the top sheet and the non-skin side member.
The top sheet and the non-skin side member are joined by an adhesive spaced apart in a plane direction,
The absorbent article according to claim 1, wherein the distance between the adhesives is shorter than the average fiber length of the fibers arranged on the non-skin surface of the top sheet.
The top sheet and the non-skin side member are joined by compressed parts arranged at intervals in a plane direction,
The absorbent article according to claim 1, wherein a distance between the compressed parts is shorter than an average fiber length of fibers arranged on the non-skin surface of the top sheet.
A plurality of convex portions protruding toward the skin side and a plurality of concave portions recessed toward the non-skin side between the convex portions are formed on the skin surface of the top sheet,
The fiber density in the concave portion is higher than the fiber density in the convex portion,
The absorbent article according to claim 1, wherein a distance between the convex portions is shorter than an average fiber length of fibers arranged on the non-skin surface of the top sheet.
The absorbent article according to claim 4, wherein the recessed portion is formed with a compressed portion that compresses at least the first fiber layer and the second fiber layer in the thickness direction.
The non-skin surface of the top sheet in the area where the convex portion is arranged is located closer to the skin than the non-skin surface of the surrounding top sheet,
The absorbent article according to claim 4, wherein the convex portion is formed in at least the first fiber layer and the second fiber layer.
The non-skin surface of the top sheet in the region where the convex portion is arranged is at the same position in the thickness direction as the non-skin surface of the surrounding top sheet, and is at a position that is more non-skin than the non-skin surface of the surrounding top sheet. 5. The absorbent article of claim 4, which is located laterally.
The absorbent article according to claim 1, wherein the first fiber layer contains thermoplastic resin fibers in a proportion of 90% to 100% by weight.
The absorbent article according to claim 8, wherein the thickness of the first fiber layer is greater than or equal to the thickness of the second fiber layer.
The absorbent article according to any one of claims 1 to 9, wherein the second fiber layer is arranged on the non-skin surface of the top sheet.
The top sheet has a third fiber layer located on the non-skin side of the second fiber layer and arranged on the non-skin surface of the top sheet,
The absorbent article according to any one of claims 1 to 9, wherein a weight ratio of thermoplastic resin fibers in the third fiber layer is higher than a weight ratio of thermoplastic resin fibers in the second fiber layer. .
The absorbent article has a front-back direction and a width direction perpendicular to the front-back direction,
From claim 1, wherein the bonding strength of the first fiber layer and the second fiber layer along the width direction is higher than the bonding strength of the first fiber layer and the second fiber layer along the front-rear direction. The absorbent article according to claim 9.
The absorbent article has a front-back direction and a width direction perpendicular to the front-back direction,
The non-skin side member is a core wrap sheet that covers the skin side of the absorbent core,
Claims 1 to 9, wherein the bonding strength of the core wrap sheet and the absorbent core along the width direction is lower than the bonding strength of the first fiber layer and the second fiber layer along the width direction. The absorbent article according to any one of the above.
It has a side sheet that covers the side of the top sheet,
A portion of the side sheet is joined to a liquid-impermeable back sheet disposed on the non-skin side of the absorbent core,
The absorbent article according to any one of claims 1 to 9, wherein the bonding strength between the top sheet and the side sheet is higher than the bonding strength between the first fiber layer and the second fiber layer.
The absorbent article according to any one of claims 1 to 9, wherein the cellulose fibers are rayon fibers and are dispersed throughout the second fiber layer.