Patent Application
20210220188
The present invention relates to an absorbent article and a top sheet.
As absorbent articles such as sanitary napkins, panty liners, and incontinence pads, an absorbent article that includes a liquid permeable top sheet, a liquid impermeable back sheet, and an absorbent body interposed between the liquid permeable top sheet and the liquid impermeable back sheet is known. A nonwoven fabric formed by accumulating fibers is often used as the top sheet. It is known that the top sheet is subjected to a shaping process by heat, pressure, and the like, in order to improve the diffusibility of body fluids and enhance texture.
For example, Patent Document 1 describes an absorbent article that includes a liquid permeable top sheet formed of two layers of a cushion layer and a skin contact layer. In the absorbent article described in Patent Document 1, heat-embossed portions are formed on the entire top sheet. The heat-embossed portions are arranged in a staggered pattern, and the long-side direction of the heat-embossed portions corresponds to the transverse direction of the absorbent article. In addition, the distance between two adjacent heat-embossed portions in each of the long-side direction and the short-side direction of the heat-embossed portions is twice or more the thickness of a member that is subjected to heat embossing.
Japanese Patent No. 4953613
However, in the absorbent article described in Patent Document 1, long sides and short sides of the heat-embossed portions are arranged in parallel in respective directions, and thus, the heat-embossed portions tend to be located in close proximity. In particular, body fluids may be readily held in regions between heat-embossed portions that are arranged in the short-side direction of the heat-embossed portions, and may remain in the top sheet. Further, in the absorbent article described in Patent Document 1, the appearance of the heat-embossed portions is not taken into consideration, and the requirements of users who attach importance to the design are not sufficiently met.
In view of the above, it is an object of one aspect of the present invention to provide an absorbent article that prevents body fluids from remaining in a top sheet and has excellent design.
According to one embodiment of the present invention, an absorbent article includes a top sheet, a liquid impermeable back sheet, and an absorbent body interposed between the top sheet and the back sheet. Welded portions are formed on at least a part of the top sheet. The welded portions constitute a plurality of units, and each of the units includes rod portions that are arranged radially in planar view. The distance between adjacent units is greater than the diameter of a smallest virtual circle inscribed in the rod portions included in each of the units.
According to an aspect of the present invention, an absorbent article that prevents body fluids from remaining in a top sheet and has excellent design can be provided.
In the following, embodiments of the present invention are described below with reference to the accompanying drawings. In the drawings, unless otherwise indicated, the same or corresponding elements may be denoted by the same reference numerals, and a duplicate description thereof may be omitted. In order to facilitate understanding of the present invention, the depiction of certain elements in the figures may be enlarged or reduced.
According to an embodiment of the present invention, an absorbent article that includes a top sheet having a predetermined configuration is provided. Examples of the absorbent article include a sanitary napkin, a panty liner, an incontinence pad, and a disposable diaper. Further, according to an embodiment of the present invention, a top sheet is provided.
As illustrated in
As illustrated in
The absorbent body 4 has a size and a shape such that the absorbent body 4 does not protrude from the back sheet 2 in planar view. At both end portions in the longitudinal direction of the absorbent body 4, outer end portions of the back sheet 2 and the top sheet 3 are bonded to each other with an adhesive such as a hot-melt adhesive or with an adhesive means such as a heat seal or an ultrasonic seal. Further, side nonwoven fabrics 7, 7 are provided at side portions of the top sheet 3 along the longitudinal direction D1. The side nonwoven fabrics 7, 7 and the back sheet 2 are bonded to each other with an adhesive means as described above, at side portions (both end portions in the width direction) of the absorbent body 4. A slip preventive portion 9 for securing the absorbent article 1 to the underwear may be provided on the back surface of the back sheet 2.
The back sheet 2 is a sheet that prevents body fluids (such as menstrual blood, vaginal discharge, and urine), having permeated the absorbent body 4 and reached the back surface of the back sheet 2, from being transferred to the underwear. The back sheet 2 may use a sheet material such as an olefin resin sheet formed of polyethylene or polypropylene and having at least a water shielding property. Alternatively, the back sheet 2 may use a polyethylene-sheet-laminated nonwoven fabric or a nonwoven fabric layered sheet having a waterproof film interposed therebetween such that impermeability is substantially ensured. Further, a material having moisture permeability is desirably used to prevent stuffiness. As such a water shielding and permeable sheet material, a microporous sheet is preferably used. The microporous sheet is obtained by forming a sheet by melting and kneading inorganic filler with an olefin resin such as polyethylene and polypropylene, and subsequently stretching the sheet in one axial direction or two axial directions.
The top sheet 3 is a liquid permeable sheet that causes body fluids to quickly pass through and to be transferred to the absorbent body 4 layered on the back surface of the top sheet 3. As the top sheet 3, a nonwoven fabric composed of synthetic or natural fibers is preferably used. Alternatively, a woven fabric laminated with a porous plastic sheet may be used.
Examples of fibers constituting the top sheet 3 include synthetic fibers such as olefin such as polyethylene or polypropylene, polyester such as polyethylene terephthalate or polybutylene terephthalate, polyamide such as nylon 6 or nylon 66; regenerated fibers such as rayon or cuprammonium rayon; mixed fibers thereof; and natural fibers such as cotton. Further, composite fibers such as core-in-sheath fibers having a high-melting-point fiber as a core and a low-melting-point fiber as a sheath, side-by-side fibers, or split fibers may be used. These fibers can be used alone or in combination with two or more kinds.
Further, examples of a method for processing a nonwoven fabric include a spunlace method, a spunbond method, a thermal bond method, a melt blown method, and a needle punch method. Among the above methods, the spunlace method is preferred in terms of flexibility, the spunbond method is preferred because a nonwoven fabric with high drape properties can be manufactured, and the thermal bond method is preferred because a soft nonwoven fabric with high bulkiness can be manufactured.
Further, the top sheet 3 may be subjected to treatment for providing hydrophilicity or hydrophobicity. The treatment may be performed by mixing a hydrophilic agent or a hydrophobic agent with a fiber material beforehand, or applying a hydrophilic agent or a hydrophobic agent to the surface of a nonwoven fabric beforehand.
The top sheet 3 may have a multi-layer structure in which a first top sheet (top sheet) 3A and a second top sheet (second sheet) 3B are laminated (
The above-described materials may be used as the material of the first top sheet 3A and the material of second top sheet 3B. Preferably, hydrophilic nonwoven fabrics formed by the thermal bond method or the spunbond method are used as the first top sheet 3A and the second top sheet 3B. More preferably, nonwoven fabrics formed by the thermal bond method are used because the nonwoven fabrics formed by the thermal bond method include fine, bulky fibers and have enhanced texture. If the first top sheet (top sheet) 3A and the second top sheet (second sheet) 3B are formed of different materials, the first top sheet 3A is preferably formed of a thermally bonded nonwoven fabric, and the second top sheet 3B is preferably formed of a spunbonded nonwoven fabric. Accordingly, the top sheet 3 is configured such that the fiber density of the first top sheet 3A is lower than the fiber density of the second top sheet 3B. With this configuration, body fluids can readily flow from the first top sheet 3A into the second top sheet 3B by capillary action, thus allowing body fluids discharged onto the first top sheet 3A to be rapidly directed into the absorbent body 4. In addition, the user can recognize that body fluids are securely absorbed because body fluids are not readily seen from the surface.
Note that the top sheet 3 may include three or more layers. In this case, the three or more layers may have the same configuration, or may have different configurations. Further, the above-described materials may be used as the materials of the layers.
The material of the absorbent body 4 is not particularly limited, and preferably includes cotton-like pulp and a water-absorptive polymer. Examples of the water-absorptive polymer include a superabsorbent polymer (SAP), a superabsorbent polymer fiber (SAF), and a combination thereof. Examples of the pulp include cellulose fibers such as dissolving pulp and chemical pulp made from wood, and synthetic cellulose fibers such as rayon and acetate. Materials of the chemical pulp include softwood pulp and hardwood pulp. Because of a long fiber length, the softwood pulp is preferably used.
The absorbent body 4 is preferably manufactured by a fiber lamination method or an air laid method. In order to maintain the shape of the absorbent body 4, the absorbent body 4 may be surrounded by a colored or an uncolored (white) encapsulating sheet made of a crepe paper sheet or a nonwoven fabric.
As the side nonwoven fabrics 7, water-repellent nonwoven fabrics or hydrophilic non-woven fabrics may be used in order to prevent the permeation of body fluids or to enhance texture. The side nonwoven fabrics 7 may be composed of natural fibers, synthetic fibers, or regenerated fibers. For water repellency, the side nonwoven fabrics 7 may be coated with a water-repellent agent such as a silicon-based or a paraffin-based water-repellent agent.
According to an embodiment of the present invention, the top sheet 3 is subjected to a shaping process in which three-dimensional recesses and projections are formed. Subjecting the top sheet 3 to the shaping process improves the function of directing body fluids, enhances texture by reducing the area of the top sheet 3 that contacts the skin, and also increases the stiffness of the top sheet 3. In addition, recessed portions (shaped portions) formed by the shaping process can represent predetermined shapes that can be visually recognized, thus improving the design and appearance of the top sheet 3.
The shaping process may be a process in which the thickness of a sheet is locally varied by heating and/or applying pressure to the sheet or by using an agent to locally denature the material of the sheet. The shaping process is preferably a process (welding process) in which a plurality of welded portions are formed spaced apart from each other. The welded portions are portions where fibers included in the sheet are at least partially welded (fused) and the bulk density is increased. The thicknesses of the welded portions are smaller than the thicknesses of portions surrounding the welded portions. That is, the welded portions are recessed portions or dented portions. The welded portions may be formed by what is known as heat embossing that uses a roller or the like to apply heat and pressure.
If the top sheet 3 includes a single layer, fibers included in the single layer are welded, thereby forming welded portions. If the top sheet 3 includes two or more laminated layers, fibers between the laminated layers are welded, or fibers included in the same layer and fibers between the laminated layers are welded, thereby forming welded portions.
According to an embodiment of the present invention, welded portions can be formed over at least a part of the top sheet 3. That is, a plurality of welded portions, spaced apart from each other, may be formed over a part of the surface of the top sheet 3, or may be formed over the entire surface of the top sheet 3 as illustrated in
The ratio of the area (hereinafter may be referred to as the “area ratio”) of the welded portions of the above-described part of the top sheet 3 to the area of the top sheet 3, which is taken as 100%, may be set to 1% to 50%. By setting the area ratio of the welded portions to 1% or more, an effect of directing body fluids can be improved. In addition, by setting the area ratio of the welded portions to 50% or less, an excessive increase in the stiffness of the top sheet 3 and in the stiffness of the absorbent article 1 can be prevented, and also body fluids can be prevented from being excessively held in the top sheet 3. As a result, hindering the diffusion of body fluids can be prevented.
In the following, welded portions formed on the top sheet 3 will be described in more detail.
As illustrated in
As described above, because the welded portions each include the rod portions 12, body fluids can be readily directed along the long sides of the rod portions 12 to regions where no rod portions 12 are formed. Accordingly, body fluids can be readily directed in a desired direction on the top sheet 3 and/or in the top sheet 3 in accordance with the arrangement of the plurality of rod portions 12.
The shape of each of the rod portions 12 in planar view may be an angular shape, or may be a rounded shape such as an elongated elliptical shape. As long as each of the rod portions 12 can be perceived as having a rod shape, the rod portions 12 may be each formed in a recessed shape. Specifically, each of the rod portions 12 may have a polygonal shape such as a triangle shape or a quadrilateral shape. Examples of the quadrilateral shape include a rectangular shape, a parallelogram shape (including a diamond shape), and a trapezoidal shape. If each of the rod portions 12 has a polygonal shape, one vertex of each of the polygonal-shaped rod portions 12 is disposed facing the center of a corresponding unit 20. In this manner, body fluids discharged within the unit 20 can be rapidly directed to the outside of the unit 20 along the two sides of the vertex of each of the rod portions 12.
In the examples illustrated in
In the example illustrated in
The aspect ratio of the rod portion 12 is preferably approximately 2 to 10, and is more preferably approximately 2.5 to 6. As used herein, the “aspect ratio” is the value of the ratio of the length of the rod portion 12 to the width of the rod portion 12. That is, the “aspect ratio” is the value of the ratio of the length in the long-side direction of the rod portion 12 to the length in the short-side direction perpendicular to the long-side direction of the rod portion 12. If the rod portion 12 has a shape that varies in width, the aspect ratio may be the value of the ratio of the maximum length to the maximum width of the rod portion 12. Further, if the rod portion 12 is curved, the aspect ratio may be the value of the ratio of the distance between both ends of the rod portion 12 to the maximum width of the rod portion 12.
The aspect ratio of 2 or more can facilitate directing bodily fluids along the long edge portions or the long sides of the rod portion 12. The aspect ratio of 10 or less can prevent the flow of body fluids in the short-side direction of the rod portion 12 from being hindered.
The length (in the long-side direction) of the rod portion 12 may be 1.0 mm to 10 mm. The maximum width of the rod portion 12 may be 0.5 mm to 2.0 mm.
As illustrated in
If one unit 20 includes three or more rod portions 12, the three or more rod portions 12 included in the one unit can be arranged such that the centerlines of the three or more rod portions 12 intersect at one point. For example, as indicated by a unit 20 on the right side of
With the above-described radial arrangement, excessive proximity of a plurality of rod portions 12 in a unit 20 can be prevented. For example, arranging two or more rod portions 12 in parallel or arranging three or more rod portions 12 in parallel can be prevented. In this manner, a plurality of rod portions 12 can be prevented from being arranged too close to each other.
Further, as indicated by a unit 20 on the left side of
Further, a plurality of units 20 are formed on the top sheet 3, and each of the units 20 includes a plurality of rod portions 12. In the example of
As illustrated in
A plural number of rod portions 12 may be included in one unit 20. Preferably, two to five rod portions 12 may be included in one unit 20. By setting the number of rod portions 12 included in a unit to two or more, the unit can represent a highly designed shape, and also body fluids can be readily directed along the rod portions 12. Further, by setting the number of rod portions 12 included in a unit to five or less, the rod portions 12 can be prevented from being arranged too close to each other, thus preventing an excessive increase in stiffness of the unit 20 and in the vicinity thereof.
Further, as illustrated in
If three rod portions 12 are included in one unit, one virtual circle can be inscribed in the rod portions 12. Thus, the one virtual circle is set to be the smallest virtual circle C. Conversely, if four or more rod portions 12 are included in one unit, a plurality of virtual circles may be inscribed in the rod portions 12. Thus, the smallest virtual circle of the plurality of virtual circles is set to be the smallest virtual circle C. As in the examples illustrated in
The above-described relationship between the distance between units 20 and the size of a virtual circle inscribed in rod portions 12 allows the units 20 to be sufficiently spaced apart from each other. Therefore, a plurality of rod portions 12 included in one unit 20 can be integrally recognized by the user. In addition, because each unit 20 can represent a predetermined shape, a variety of designs may be possible.
The diameter a of the smallest virtual circle C may be 0.5 mm to 5 mm. By setting the diameter a to 0.5 mm or more, a more reliable pathway of body fluids can be formed at the center of a unit 20. In addition, a plurality of rod portions 12 are prevented from being arranged too close to each other, thus preventing an excessive increase in stiffness. By setting the diameter a to 5 mm or less, a plurality of rod portions 12 included in one unit 20 can be formed integrally, and the shape formed by the one unit 20 can be readily recognized.
More specifically, the distance b between two adjacent units 20 may be 0.6 mm to 15 mm, and may preferably be 3 mm to 12 mm. Further, the value of the ratio (b/a) of the distance b to the diameter a, which exceeds 1, is preferably 1.1 to 10, and is more preferably 2 to 7. By setting the above value of the ratio to 1.1 or more, a plurality of rod portions 12 included in a unit 20 can be formed integrally, and the shape formed by the unit 20 can be readily recognized. By setting the above value of the ratio to 10 or less, body fluids can be directed along a plurality of units 20, that is, body fluids can be directed from rod portions 12 included in one unit 20 to rod portions 12 included in another unit 20.
From the viewpoint of design, the predetermined shape represented by a unit 20 is not limited to a geometric shape, and may be any shape that reminds people of a plant, an animal, a daily necessity, or an ornament. Examples of the predetermined shape include a flower, a leaf, a star, a snow crystal, and a ribbon (including a tied-ribbon shape). In the examples illustrated in
As described above, in the present embodiment, the predetermined shape can be represented by each unit 20 (welded portion 10) that includes rod portions 12 disposed spaced apart from each other. Accordingly, the total area of welded portions can be reduced, as compared to when a predetermined shape is represented by each continuous welded portion.
In order to improve the visibility of welded portions by placing priority on the design of the welded portions, the welding process (shaping process) may be performed under strengthened conditions such as high temperature and high pressure conditions. Further, such processing conditions may also be strengthened by the material of the top sheet 3 or by a combination of the material of the first top sheet 3A and the material of the second top sheet 3B. In such a case, fibers may be excessively welded, and as a result, a part of or the entirety of the welded portions may become non-porous. If the welded portions become non-porous, body fluids would not readily pass through the top sheet 3, and would remain in the welded portions and in the vicinities of the welded portions of the top sheet 3.
Conversely, in the present embodiment, the total area of welded portions can be reduced as compared to when a predetermined shape is represented by each continuous welded portion. Therefore, even when the welded portions are formed under strengthened processing conditions, the top sheet and the absorbent article can ensure liquid permeability while having an enhanced design represented by the shapes of the welded portions.
A unit 20 of
The shapes of rod portions 12 included in a unit 20 of
In the example illustrated in
In the examples illustrated in
In the example illustrated in
In the example of
Note that any welded portions other than units 20 including rod portions 12 are not formed in the illustrated examples, but any other welded portions may be formed. For example, dot-shaped welded portions or welded portions having any other shape may be formed. However, no welded portions are preferably formed in virtual circles C in order to reduce the total area of welded portions.
Further,
As illustrated in
As described above, the thickness of one rod portion 12 may be uniform, but is not necessarily uniform. Further, a plurality of rod portions 12 in one unit 20 may have the same thickness or may have different thicknesses.
The above-described arrangement of the staggered pattern allows body fluids, directed along rod portions 12 to the outside of the units 20, to be further directed to regions where no welded portions are formed. Accordingly, body fluids can be readily diffused on and/or in the entire top sheet 3, as indicated by arrows in
The grid pattern illustrated in
Further, in the examples illustrated in
Further, in the pattern illustrated in
As illustrated in
As described above, the relationship between the longitudinal direction D1 and the width direction D2 of the absorbent article versus the pattern of welded portions is not particularly limited. In the arrangement illustrated in
Further, if welded portions are formed by a compression drum, projections corresponding to the welded portions can be formed by linearly cutting the surface of the drum, that is, by cutting the surface of the drum along the virtual straight lines X1 and X2. Therefore, the manufacturing time and cost can be reduced. In this case, no welded portion is preferably formed in a region between the virtual straight line X1 and the virtual straight line X2, as illustrated in
In the following, preferred embodiments of the present invention will be described below.
An embodiment according to clause 1 provides an absorbent article including a top sheet, a liquid impermeable back sheet, and an absorbent body interposed between the top sheet and the back sheet. Welded portions are formed over at least a part of the top sheet. The welded portions constitute a plurality of units, and each of the units include rod portions that are arranged radially in planar view. The distance between adjacent units is greater than the diameter of a smallest virtual circle inscribed in the rod portions included in each of the units.
In the embodiment according to clause 1, the welded portions are formed over at least the part of the top sheet, the welded portions constitute a plurality of units, and each of the units includes the rod portions that are arranged radially in planar view. Accordingly, regions where the rod portions are arranged in parallel and in close proximity can be reduced or eliminated. In addition, in each of the units, the virtual circle inscribed in the rod portions can be drawn. Accordingly, a predetermined distance can be maintained between the rod portions even in the vicinity of the center of each of the units, thereby preventing the rod portions from being located close to each other, and preventing body fluids from remaining in the top sheet.
Further, the distance between the adjacent units is greater than the diameter of the smallest virtual circle inscribed in the rod portions included in each of the units. Accordingly, the sufficient distance can be maintained between the adjacent units, and an effect of preventing remaining body fluids can be improved. Further, the plurality of rod portions included in each of the units can be integrally recognized, and the integrally recognized rod portions can represent a predetermined shape. Accordingly, the design of the top sheet and the design of the absorbent article can be enhanced.
In an embodiment according to clause 2, the top sheet is formed by laminating a first top sheet and a second top sheet. The first top sheet is on the skin side and the second top sheet is on the underwear side when the absorbent article is worn.
In the embodiment according to clause 2, the sheets forming the top sheet can have respective functions.
In an embodiment according to clause 3, the diameter of the virtual circle is 0.5 mm to 5.0 mm.
In the embodiment according to clause 3, the diameter of the virtual circle is in a predetermined range. Accordingly, body fluids remaining in the vicinity of the center of each of the units can be further eliminated. In addition, the predetermined shape can be more clearly represented by one unit, thereby enhancing the design of the top sheet.
In an embodiment according to clause 4, the number of the rod portions included in each of the units is 2 to 5.
In the embodiment according to clause 4, a predetermined number of rod portions is included in each of the units. Accordingly, a variety of shapes may be formed by the units. In addition, the rod portions are prevented from being located close to each other, thus preventing an excessive increase in the stiffness of the top sheet.
In an embodiment according to clause 5, each of the rod portions has an aspect ratio of 2 to 10.
In the embodiment according to clause 5, each of the rod portions has a predetermined aspect ratio. Accordingly, body fluids can be readily directed in the long-side direction of each of the rod portions. In addition, hindering the diffusion of body fluids due to excessively long rod portions can be prevented.
In an embodiment according to clause 6, the units are arranged in a staggered pattern.
In the embodiment according to clause 6, body fluids can be readily diffused, as compared to when the same number of units are arranged in a grid pattern.
In an embodiment according to clause 7, each of the rod portions has a kite shape whose short sides face a center of a corresponding unit.
In the embodiment according to clause 7, body fluids reaching near the center of the unit can be rapidly diffused along the sides of the rod portions to the outside of the unit. In addition, the design can be enhanced.
In an embodiment according to clause 8, the rod portions have polygonal shapes, and one side of a polygonal-shaped rod portion included in one unit and one side of a polygonal-shaped rod portion included in another unit are in a same virtual straight line.
In the embodiment according to clause 8, the top sheet can readily deform in a direction in which the virtual straight line extends, thus allowing the absorbent article to readily deform following the movement of the wearer's body. Further, if the welded portions are formed by a compression drum, projections corresponding to the welded portions are formed by linearly cutting the surface of the drum. Therefore, the manufacturing time and cost can be reduced.
An embodiment according to clause 9 provides a top sheet that is liquid permeable and is used in an absorbent article. The top sheet includes welded portions formed over at least a part of the top sheet. The welded portions constitute a plurality of units, and each of the units includes a plurality of rod portions that are arranged radially in planar view. The diameter of a smallest virtual circle inscribed in the rod portions included in each of the units is smaller than the distance between adjacent units.
In the embodiment according to clause 9, the top sheet that exhibits an effect similar to that of clause 1 can be provided.
The present application is based on and claims priority to Japanese Patent Application No. 2018-173444 filed on Sep. 18, 2018, with the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-173444 | Sep 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/027571 | 7/11/2019 | WO | 00 |
