Patent Application
20210338494
The present invention relates to an absorbent article.
Known absorbent articles such as a sanitary napkin, a pantiliner, and an incontinence pad are made by sandwiching an absorbing part between a permeable top sheet and an impermeable back sheet.
Also, there is an absorbent article that is configured to be deformable according to movement of the body of a wearer. For example, Patent Document 1 describes a configuration including a shrinkable absorption structure disposed between a front-side sheet and a back-side sheet. The absorption structure includes a large number of block-shaped absorbers that are independent of each other; and the back-side sheet has stretchability at least in the longitudinal direction, is in a contracted state when not stretched, and stretches at a predetermined ratio in the longitudinal direction in response to a predetermined tensile load (e.g., claim 1).
[Patent Document 1] Japanese Patent No. 5779414
With the configuration disclosed in Patent Document 1, the entire absorbent article has stretchability and therefore can expand and contract along with the expansion and contraction of underwear caused by the movement of the body. However, the configuration disclosed in Patent Document 1 does not take into account the friction between the absorbent article and the skin, which may occur when the body of a wearer of the absorbent article moves during, for example, walking. Such friction may reduce the wear comfort and, in some cases, may cause the wearer to feel, for example, itchiness or pain.
In view of the above problems, one object of the present invention is to provide an absorbent article that is more comfortable to wear and configured to prevent friction between the absorbent article and the skin which may occur while the absorbent article is worn.
According to a first aspect of the present invention, an absorbent article includes a permeable top sheet, an impermeable back sheet, an absorbing part disposed between the top sheet and the back sheet, and a friction reducing layer disposed between the back sheet and the absorbing part. The friction between the friction reducing layer and the back sheet or the friction between the friction reducing layer and the absorbing part is less than the friction between the absorbing part and the back sheet.
An aspect of the present invention makes it possible to provide an absorbent article that is more comfortable to wear and configured to prevent friction between the absorbent article and the skin which may occur while the absorbent article is worn.
An embodiment of the present invention is described below with reference to the accompanying drawings. Unless otherwise mentioned, the same reference number is assigned to the same component or corresponding components throughout the drawings, and repeated descriptions of those components may be omitted. Also, the drawings are schematic diagrams for facilitating the understanding of the invention, and some dimensions may be greater than or less than the actual dimensions.
The absorbent article body 8 is a portion of the absorbent article 1 excluding wings W described later. As a whole, the body 8 has an elongated shape that has a predetermined length in the longitudinal direction (the front-back direction, i.e., a first direction D1 in the figure) and a predetermined width in the width direction (a second direction D2 in the figure) orthogonal to the longitudinal direction D1. Although the width of the body 8 is substantially constant in the illustrated example, the width of the body 8 may vary along the longitudinal direction D1. The absorbent article 1 may have a shape and a structure that are substantially axisymmetric with respect to a center line (longitudinal center line) CL extending in the longitudinal direction.
In the example of
The body 8 of the absorbent article 1 includes a region (body fluid outlet region) A that faces a body fluid outlet such as the vaginal opening of a wearer wearing the absorbent article 1, and the body fluid outlet region A has a center Ac. The center Ac is located on the longitudinal center line CL and near the center of the body fluid outlet region A in the longitudinal direction D1. The absorbent article 1 includes a middle region M including the body fluid outlet region A, a front region F next to the front end of the middle region M, and a rear region R next to the rear end of the middle region M.
The middle region M may include wings W that extend from the lateral sides of the middle region M and are used to reliably fix the absorbent article 1 to the underwear when the absorbent article 1 is worn. The front region F extends from positions corresponding to or near the front starting points of the wings W to the front end, and the rear region R extends from positions corresponding to or near the rear starting points of the wings W to the rear end. Also, when the wings W are provided, in the longitudinal direction D1, the center Ac of the body fluid outlet region A may be located in the midpoint in the length of the lateral edges of the wings W or in the midpoint between the front starting points and the rear starting points of the wings W.
Although the absorbent article 1 in the illustrated example includes the wings W, the absorbent article 1 may be configured to not include the wings W. In this case, the front region F may be a region extending forward from positions corresponding to or near the front starting points of wings W that are assumed to be formed, and the rear region R may be a region extending backward from positions corresponding to or near the rear starting points of wings W that are assumed to be formed.
The overall length of the absorbent article 1 is preferably between 150 and 450 mm, and more preferably between 170 and 290 mm.
The absorbing part 4 is provided between the top sheet 2 and the back sheet 3 so as not to be exposed to the outside. For example, as illustrated in
At the front and rear ends of the absorbing part 4, end seals Ee may be formed by bonding the outer edges of the back sheet 2 and the top sheet 3 with an adhesive such as a hot melt or by a bonding technique such as heat sealing or ultrasonic sealing. Also, at the lateral ends of the absorbing part 4, the side nonwoven fabrics 7 and the back sheet 2 may be bonded to each other by a bonding technique as described above to form the wings W. Embossments Ew may be formed on the wings W to increase the bonding strength and improve the design.
Thus, the entire periphery of the absorbing part 4 may be sealed. This makes it possible to prevent a body fluid absorbed by the absorbing part 4 from leaking from the side of the absorbing part 4 and also make it possible to improve the shape stability of the absorbent article 1. The strength of the end seals Ee is preferably greater than that of the side seals. This allows the back sheet 2 and the absorbing part 4 to slide relative to each other as described later, and also makes it possible to stabilize the shape of the absorbent article 1.
The back sheet 2 may be formed of a sheet material having at least a waterproof property such as an olefinic resin sheet made of polyethylene or polypropylene. Also, the back sheet 2 may be implemented by a laminated nonwoven fabric formed by stacking a nonwoven fabric on, for example, a polyethylene sheet, or a laminated sheet that is made substantially impermeable by stacking a waterproof film between nonwoven fabrics. Further, a sheet having moisture permeability is more preferably used to prevent stuffiness. As the water-impermeable and moisture-permeable sheet, a microporous sheet is preferably used. A microporous sheet is obtained by melt-mixing an inorganic filler with an olefin resin such as polyethylene or polypropylene to form a sheet, and by stretching the sheet uniaxially or biaxially.
The top sheet 3 is a permeable sheet through which body fluids such as blood, discharge, and urine can permeate rapidly. The top sheet 3 is preferably formed of a porous or nonporous nonwoven fabric or a porous plastic sheet. The nonwoven fabric may be formed by using one of or a combination of two or more of the following materials: olefins such as polyethylene and polypropylene, synthetic fibers such as polyester and polyamide, regenerated fibers such as rayon and cupra, a blend of these fibers, and natural fibers such as cotton. The nonwoven fabric may be produced by, for example, spunlacing, spunbonding, thermal bonding, melt-blowing, or needle punching. Among these production methods, spunlacing is preferable to produce a flexible nonwoven fabric, spunbonding is preferable to produce a nonwoven fabric with good draping characteristics, and thermal bonding is preferable to produce a bulky and soft nonwoven fabric. Also, bicomponent fibers may be used for the synthetic fibers. Examples of bicomponent fibers include a core-in-sheath fiber including a high-melting-point fiber as a core and a low-melting-point fiber as a sheath, a side-by-side fiber, and a split fiber.
As illustrated in
The absorber 41 may be implemented by any material that can absorb and hold a body fluid, and preferably includes cotton pulp and an absorbent polymer. Examples of absorbent polymers include superabsorbent polymer (SAP) granular powder (SAP), superabsorbent fibers (SAF), and a combination of them. Examples of the pulp include chemical pulp obtained from wood, cellulose fibers such as dissolving pulp, and artificial cellulose fibers such as rayon and acetate. Hardwood and softwood may be used as the materials of the chemical pulp, but softwood is preferably used because of its long fiber length. The absorber 41 may be produced by fiber stacking or an air-laid method.
Synthetic fibers may also be added to the absorber 41. Examples of materials of the synthetic fibers include polyolefin such as polyethylene and polypropylene, polyester such as polyethylene terephthalate or polybutylene terephthalate, polyamide such as nylon, and a copolymer of these materials. Also, the synthetic fibers may be formed by mixing two or more of these materials. Also, bicomponent fibers may be used for the synthetic fibers. Examples of bicomponent fibers include a core-in-sheath fiber including a high-melting-point fiber as a core and a low-melting-point fiber as a sheath, a side-by-side fiber, and a split fiber. Further, a material obtained by surface-treating hydrophobic fibers with a hydrophilic agent to have an affinity to body fluids may be used as the synthetic fibers.
The absorbing part 4 may be implemented by a polymer sheet including a superabsorbent polymer sandwiched in a predetermined region between a skin-side sheet and an underwear-side sheet.
The thickness of the absorbing part 4 may be between 0.3 and 30 mm, and is preferably between 1.0 and 15 mm. The absorber 41 does not necessarily have a uniform thickness in its entirety, and the body fluid outlet region 50, a region near the body fluid outlet region 50, and a central portion of the rear region in the width direction may be bulging.
The side nonwoven fabrics 7 may be implemented by a water-repellent nonwoven fabric or a hydrophilically-treated nonwoven fabric. For example, a water-repellent nonwoven fabric coated with a silicon- or paraffin-repellent is preferably used to more prevent penetration of body fluids such as blood and discharge or to improve the feel. Also, to improve the absorbency of the wings W for absorbing, for example, menstrual blood, the wings W are preferably formed of a hydrophilically-treated nonwoven fabric. As a type of the nonwoven fabric, an air-through nonwoven fabric, which is soft and unlikely to be creased and wrinkled, is preferably used.
As illustrated in
A friction reducing layer 6 is disposed between two contacting objects and has a function to reduce friction or a frictional force between the two objects. In the present embodiment, the friction reducing layer 6 is configured such that at least one of the friction between the friction reducing layer 6 and the absorbing part 4 and the friction between the friction reducing layer 6 and the back sheet 2 becomes less than the friction between the absorbing part 4 and the back sheet 2.
As illustrated in
While the absorbent article 1 is worn, there may be a case where the wearer moves the legs largely or continuously in, for example, a walking motion. In such a case, the underwear may be deformed by the force and movement of the legs, and the back sheet 2 may also deform and move along with the deformation of the underwear. Here, if the back sheet 2 and the absorbing part 4 are stuck together by friction or with an adhesive, the structure including the absorbing part 4 and components above the absorbing part 4 (e.g., the absorbing part 4, the top sheet 2, and any additional component) may deform and move along with the back sheet 2, and therefore moves relative to the skin of the wearer facing the absorbent article. As a result, the skin may be rubbed by the surface of the top sheet 2 of the absorbent article 1. This rubbing may reduce the wear comfort and cause the wearer to feel itchiness or pain.
In contrast, in the present embodiment, the friction reducing layer 6 is provided between the back sheet 2 and the absorbing part 4 so that the back sheet 2 and the absorbing part 4 can slide relative to each other in the in-plane direction and the back sheet 2 and the absorbing part 4 are less likely to move along with each other. This configuration makes it possible to prevent or reduce the movement of the absorbing part 4 and the top sheet 3 disposed on the absorbing part 4 relative to the skin of the wearer even when the back sheet 2 deforms and moves along with the deformation of the underwear. Accordingly, this configuration makes it possible to reduce the friction between the top sheet 2 of the absorbent article 1 and the skin and thereby improve the wear comfort.
The friction reducing layer 6 may be formed of any material that can reduce the friction between the back sheet 2 and the absorbing part 4 and enable them to slide relative to each other in a direction along the contact surface. For example, the friction reducing layer 6 may be a sheet-like part including a base sheet 6b and a friction reduced portion 6a that is formed by applying a friction reducing treatment to at least a part of one surface of the base sheet 6b.
As illustrated in
In the example of
Also in the example of
Also, as illustrated in
Here, the friction reducing treatment may be performed, for example, by applying a material (composition) including a substance capable of imparting slipperiness or a material composed of a substance capable of imparting slipperiness. Examples of substances capable of imparting slipperiness include organic substances such as silicone resin, fluororesin, and polyacetal resin, and inorganic substances such as talc, silica, and mica. The form of the material to be applied may be, for example, but is not limited to, solution, emulsion, suspension, or powder. When the material is applied in the form of powder, the material is preferably applied to the back sheet 2. When the friction reducing layer 6 formed as a sheet-like part as illustrated in
Also, the material including a substance capable of imparting slipperiness or the material composed of a substance capable of imparting slipperiness may be in the form of powder. In this case, silicone powder having excellent dispersibility is preferably used.
The base sheet 6b may be implemented by a film formed of a thermoplastic resin or a combination of thermoplastic resins, a planar body including fibers such as a woven fabric or a nonwoven fabric, a planar body including pulp, or a laminate structure of these materials. Examples of thermoplastic resins used as the materials of the base sheet 6b include olefins such as polyethylene and polypropylene, polyester, and polyvinyl alcohol. Polyethylene is preferable because of its inexpensiveness and good workability.
In the examples illustrated in
For example, as illustrated in
In the examples illustrated in
Also, depending on the degree of the friction reducing effect of the friction reducing layer 6 and the application of the absorbent article 1, the length of the friction reducing layer 6 may be made less than the length of the absorbing part 4 and/or the width of the friction reducing layer 6 may be made less than the width of the absorbing part 4.
In any one of the examples of
Regardless of whether the friction reducing layer 6 is implemented as a sheet-like part (
Also, the friction reducing layer 6 may have any size and any shape as long as the friction reducing layer 6 can reduce the friction between the back sheet 2 and the absorbing part 4 and enable them to slide relative to each other in a direction along the contact surface. In the example illustrated in
The static friction coefficient of the friction reducing layer 6 with the back sheet 2 is preferably less than or equal to 98%, more preferably less than or equal to 90%, still more preferably less than or equal to 75%, and further preferably less than or equal to 60% of the static friction coefficient of the absorbing part 4 with the back sheet 2 measured under the same conditions. Also, the static friction coefficient of the absorbing part 4 with the friction reducing layer 6 is preferably less than or equal to 90%, more preferably less than or equal to 80%, still more preferably less than or equal to 65%, and further preferably less than or equal to 50% of the static friction coefficient of the absorbing part 4 with the back sheet 2 measured under the same conditions.
The dynamic friction coefficient of the friction reducing layer 6 with the back sheet 2 is preferably less than or equal to 98%, more preferably less than or equal to 90%, still more preferably less than or equal to 75%, and further preferably less than or equal to 60% of the dynamic friction coefficient of the absorbing part 4 with the back sheet 2 measured under the same conditions. Also, the dynamic friction coefficient of the absorbing part 4 with the friction reducing layer 6 is preferably less than or equal to 80%, more preferably less than or equal to 50%, still more preferably less than or equal to 30%, further preferably less than or equal to 10%, and particularly preferably less than or equal to 5% of the dynamic friction coefficient of the absorbing part 4 with the back sheet 2 measured under the same conditions.
When the absorbing part 4 is enveloped in the enveloping sheet 45, the static friction coefficient and the dynamic friction coefficient of the absorbing part 4 with the friction reducing layer 6 may be represented by the static friction coefficient and the dynamic friction coefficient of the enveloping sheet 45 with the friction reducing layer 6.
When the absorbent article 1 is used, the friction between the friction reducing layer 6 and the back sheet 2 or the absorbing part 4 may be less than the friction between the skin and the absorbent article 1 (the friction between the skin and the top sheet 3).
In each of the examples illustrated in
The thickness of the friction reducing layer 6 may be about 50 to about 1,000 μm. When the friction reducing layer 6 is a sheet-like part (
The antislip parts 9 may be adhesive or non-adhesive layers for fixing the absorbent article 1 to the underwear. The adhesive layers preferably include, for example, a styrene polymer, a tackifier, a plasticizer, or a combination of them as a main component. The antislip parts 9 implemented as non-adhesive layers may be formed of any material that increases the friction between the absorbent article 1 and an object to which the absorbent article 1 is attached. One of or a combination of materials including natural or synthetic rubbers as base polymers may be used for the non-adhesive layers.
In the example of
The portion where the antislip parts 9 are provided on the back sheet 2 is firmly fixed to the underwear, and therefore tends to deform along with the underwear when the wearer moves and to rub the crotch (or private parts) facing the absorbent article. However, with the configuration where the friction reducing layer 6 overlaps the antislip parts 9 in plan view, the back sheet 2 and the absorbing part 4 can smoothly slide at the overlapping positions in a direction along their contact surface. This configuration enables the absorbing part 4 and the top sheet 2 placed on the absorbing part 4 to smoothly follow the movement of the body and enables the back sheet 2 to follow the movement of the underwear.
The friction reducing layer 6 is preferably provided at least in the middle region M, the rear region R, or both of the middle region M and the rear region R. In the example illustrated in
Also, in the rear region R, the absorbent article tends to move due to the movement of the legs during, for example, walking. That is, each time the right or left leg is moved forward in the walking direction during walking, the underwear is pulled by the moved leg, and the absorbent article is pulled along with the underwear in the walking direction. Therefore, friction is likely to occur between the absorbent article and the skin facing the absorbent article. Accordingly, the wear comfort can be effectively improved by providing the friction reducing layer 6 at least in the rear region R to prevent friction. Also, because the rear region R is adjacent to the middle region M, the movement of the rear region R tends to be transmitted to the middle region M. Therefore, providing the friction reducing layer 6 in the rear region R makes it possible to prevent friction between the absorbent article and the skin not only in the rear region R but also in the middle region M in front of the rear region R.
The back sheet 2 may be partially bonded directly or via the friction reducing layer 6 to the absorbing part 4. The bonded portion between the back sheet 2 and the absorbing part 4 makes it possible to stabilize the shape of the absorbent article and makes it possible to prevent the entire absorbent article from being damaged even when the wearer makes hard movements.
When the back sheet 2 and the absorbing part 4 are partially bonded to each other, the plan-view area of the bonded portion may be less than or equal to 20%, preferably less than or equal to 10%, more preferably less than or equal to 5%, and still more preferably 1% of the plan-view area (100%) of the absorbing part 4. Further preferably, the back sheet 2 and the absorbing part 4 may not be directly or indirectly bonded to each other. Setting the plan-view area at a value less than or equal to 20% makes it possible to avoid preventing the sliding operation between the back sheet 2 and the absorbing part 4.
The back sheet 2 and the absorbing part 4 may be bonded to each other in at least a portion of the front region F. The front region F is less affected by the movement of the body, and the friction between the absorbent article 1 and the skin is less likely to occur in the front region F than in the middle region M and the rear region R. Therefore, bonding the back sheet 2 and the absorbing part 4 in at least a portion of the front region F makes it possible to improve the shape stability of the absorbent article 1 while enabling the relative movement between the back sheet 2 and the absorbing part 4 and thereby maintaining the effect of improving the wear comfort.
When the back sheet 2 and the absorbing part 4 are not bonded to each other as in the examples of
The present embodiment may be applied to a diaper in addition to a sanitary napkin, a pantiliner, an incontinence pad and so on. The present embodiment is particularly preferably applied to a sanitary napkin. Because a sanitary napkin is often used with its skin side placed in contact with the private parts, the movement of the wearer is more likely to cause friction between the absorbent article and the skin compared with other types of absorbent articles. Accordingly, using the present embodiment makes it possible to reduce the friction between an absorbent article and the skin and prevent the reduction in wear comfort. In some cases, the present embodiment can also prevent, for example, itchiness, pain, and rashes suffered by a wearer.
Preferred embodiments of the present invention are described below as appendices.
According to an embodiment of Appendix 1, an absorbent article includes a permeable top sheet, an impermeable back sheet, an absorbing part disposed between the top sheet and the back sheet, and a friction reducing layer disposed between the back sheet and the absorbing part. The friction between the friction reducing layer and the back sheet or the friction between the friction reducing layer and the absorbing part is less than the friction between the absorbing part and the back sheet.
According to the embodiment of Appendix 1, the friction reducing layer provided between the back sheet and the absorbing part can reduce the friction between the back sheet and the absorbing part. This configuration enables the back sheet and the absorbing part to slide relative to each other and thereby makes it possible to prevent the back sheet and the absorbing part and the top sheet placed on the absorbing part to move along with each other. Therefore, even when an underwear moves along with the movement of legs and the back sheet fixed to the underwear moves along with the movement of the underwear, the movement of the back sheet is less likely to be transmitted to the absorbing part and the top sheet, and the absorbing part and the top sheet can move along with the skin of the private parts contacting the absorbent article. This in turn makes it possible to suppress the movement of the absorbing part and the top sheet relative to the skin, and thereby makes it possible to prevent friction between the absorbent article and the skin.
According to an embodiment of Appendix 2, the absorbent article includes a middle region including a body fluid outlet portion that faces a body fluid outlet of a wearer when the absorbent article is worn and a rear region disposed next to the rear end of the middle region, and the friction reducing layer is provided in at least one or both of the middle region and the rear region.
The embodiment of Appendix 2 makes it possible to prevent friction between the absorbent article and the skin in the middle region corresponding to the body fluid outlet and surrounding portions that are delicate and soft and/or makes it possible to specifically prevent friction between the absorbent article and the skin in the rear region where the absorbent article is particularly likely to move during, for example, walking.
According to an embodiment of Appendix 3, the friction reducing layer is a sheet-like part inserted between the back sheet and the absorbing part. A friction reducing treatment is applied to at least one surface of the sheet-like part.
The embodiment of Appendix 3 can reliably reduce the friction. Also, the configuration of the friction reducing layer can be changed according to the purpose of the absorbent article by just changing the sheet-like part to be inserted, i.e., without greatly changing the manufacturing process.
According to an embodiment of Appendix 4, the friction reducing layer is formed by applying a friction reducing treatment to at least one of the back sheet and the absorbing part.
The embodiment of Appendix 4 makes it possible to provide the friction reducing layer without increasing the number of components and thereby makes it possible to reduce the manufacturing costs. Also, this embodiment makes it possible to reduce the thickness of the entire absorbent article.
According to an embodiment of Appendix 5, the friction reducing treatment is a process of applying a material including one or more of a silicone resin, a fluororesin, and a polyacetal resin.
The embodiment of Appendix 5 makes it possible to improve the friction reducing effect of the friction reducing layer.
According to an embodiment of Appendix 6, the absorbent article further includes
The embodiment of Appendix 6 makes it possible to stably fix the absorbent article to an underwear with the antislip part. Also, even in this case, the back sheet can be reliably slid relative to the absorbing part and the top sheet.
The present application is based on and claims priority to Japanese Patent Application No. 2018-182563 filed on Sep. 27, 2018, the entire contents of which are hereby incorporated herein by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-182563 | Sep 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/028149 | 7/17/2019 | WO | 00 |
