JP2024123541A - Absorbent articles - Google Patents

Abstract

To provide an absorbent article having a good wearing feeling while having a high fitting property and a leakage prevention property in a back side area that can prevent stuffiness and a skin trouble.SOLUTION: An absorbent article includes a pair of fastening tapes extending from a back side area and a pair of gather parts disposed in a horizontal direction side part of the back side area. The gather part includes a gather layer including a first non-woven fabric layer, a second non-woven fabric layer, and an elastic member disposed between these non-woven fabric layers, an outer layer non-woven fabric layer disposed on a non-skin side of the gather layer, and a film layer composed of a moisture-permeable film disposed between the outer layer non-woven fabric layer and the gather layer. The gather layer is divided into a low extension area and a high extension area disposed on a horizontal direction outer side of the low extension area. The low extension area is joined to the film layer joined to the outer layer non-woven fabric layer. The high extension area is joined neither to the film layer nor to the outer layer non-woven fabric layer, and is not overlapped with the film layer at least partially.SELECTED DRAWING: Figure 3

Description

The present invention relates to an absorbent article that is worn around the waist of a wearer.

Absorbent articles such as disposable diapers can be divided into, for example, a dorsal region that is located on the dorsal side of the wearer, a ventral region that is located on the ventral side of the wearer, and a crotch region that is located between the wearer's legs. Among such absorbent articles, flat-type diapers in which the dorsal region and ventral region are separate can cover the wearer's waist by, for example, attaching a fastening tape located on the side end of the dorsal region onto the ventral region.

On the other hand, when an absorbent article is worn by a wearer who often lies in a supine position, there is a concern that excrement such as feces and urine may leak from the back region. In response to this, for example, Patent Document 1 discloses an absorbent article that includes multiple elastic stretch members arranged horizontally on the back body where the fastening member is provided, and a waterproof film formed to extend laterally beyond the absorbent body of the back body, in order to improve the fit and leak prevention in the back region (back body).

Patent No. 4750545

In the absorbent article described in Patent Document 1, if the waterproof film is extended widely to the gathered portion where the elastic member is arranged in order to improve leak prevention, there is a concern that the wearing comfort of the gathered portion may be reduced. In addition, with this configuration, the moisture permeability and breathability of the absorbent article may decrease, and there is a concern that stuffiness and associated skin troubles may occur.

The present invention relates to an absorbent article that has a high level of fit and leak resistance in the back region, while providing a comfortable fit and preventing stuffiness and skin troubles.

An absorbent article according to one embodiment of the present invention has a vertical direction extending from the wearer's abdominal side through the crotch region to the back side, a horizontal direction perpendicular to the vertical direction and corresponding to the wearer's left-right direction, and a thickness direction perpendicular to the vertical and horizontal directions, and is divided along the vertical direction into a abdominal region, a crotch region, and a back region.
The absorbent article comprises:
A pair of fastening tapes extending laterally outward from ends of the back region in the lateral direction;
and a pair of gather portions arranged on the lateral sides of the back region and stretchable in the lateral direction.
The gathered portion is
a gather layer including a first nonwoven fabric layer disposed on the skin side, a second nonwoven fabric layer disposed on the non-skin side of the first nonwoven fabric layer, and an elastic member disposed between the first nonwoven fabric layer and the second nonwoven fabric layer and extending in the lateral direction;
an outer nonwoven fabric layer disposed on the non-skin side of the gather layer so as to overlap the entire gather layer in the thickness direction;
and a film layer made of a moisture-permeable film, the film layer being disposed between the outer nonwoven fabric layer and the gathered layer so as to overlap a portion of the gathered layer in the thickness direction.
The gather layer is
A low elongation region;
a high elongation region that is disposed laterally outward of the low elongation region and has a higher elongation rate in the lateral direction than the low elongation region.
The low elongation region is
It is bonded to the film layer which is bonded to the outer nonwoven fabric layer.
The high elongation region is
It is not bonded to either the film layer or the outer nonwoven fabric layer, and at least a part of it does not overlap with the film layer in the thickness direction.

The absorbent article of the present invention has a high level of fit and leak resistance in the back area, while providing a comfortable fit and preventing stuffiness and skin troubles.

FIG. 1 is a plan view of an absorbent article (disposable diaper) according to one embodiment of the present invention, showing the state in which the elastic members of each part are stretched and spread out flat as viewed from the skin side (top sheet side). FIG. 2 is a schematic cross-sectional view of the disposable diaper taken along line II-II in FIG. 1. FIG. 2 is a schematic partial cross-sectional view of the disposable diaper taken along line III-III in FIG. 1. 3A and 3B are enlarged plan views of the moisture-permeable film of the disposable diaper, in which (A) shows an example of a non-uniformly stretched moisture-permeable film, and (B) shows an example of a uniformly stretched moisture-permeable film. 2 is a graph showing an example of the pore size distribution of the moisture-permeable film, in which the horizontal axis represents the pore size (μm) and the vertical axis represents the pore volume (ml/g).

The following describes an embodiment of the present invention with reference to the drawings.

[Overall structure of disposable diaper]
1 and 2 show a so-called flat-type disposable diaper 1 as an absorbent article according to one embodiment of the present invention. The flat-type disposable diaper 1 will be referred to as diaper 1 hereinafter.
The diaper 1 has a longitudinal direction X, a transverse direction Y, and a thickness direction Z. The longitudinal direction X extends from the wearer's abdomen through the crotch area to the back. The transverse direction Y is perpendicular to the longitudinal direction X and corresponds to the left-right direction of the wearer. The thickness direction Z is perpendicular to the longitudinal direction X and the transverse direction Y of the diaper 1.
In the present disclosure, "the inner side in the lateral direction Y" means the side in the lateral direction Y that is closer to the vertical center line CL that divides the diaper 1 in half in the lateral direction Y, and "the outer side in the lateral direction Y" means the side away from the vertical center line CL.
In the present disclosure, the "waist side" in the longitudinal direction X means the side approaching the waist end W of the diaper 1 in the longitudinal direction X.
In the present disclosure, a plan view means that each component is viewed from the thickness direction Z. In the present disclosure, the skin side of each component refers to the side that faces the skin of a wearer when the disposable diaper is worn. The non-skin side of each component refers to the clothing side that faces the opposite side to the skin side of a wearer when the disposable diaper is worn.
In the present disclosure, "multiple members overlap in the thickness direction Z" means that multiple members overlap in a plan view seen from the thickness direction Z.

1, the diaper 1 is divided into a ventral region A arranged on the ventral side of a wearer, a dorsal region B arranged on the dorsal side of the wearer, and a crotch region C located between the ventral region A and the dorsal region B and arranged in the crotch area of the wearer. The ventral region A, the crotch region C, and the dorsal region B are arranged along the longitudinal direction X.
FIG. 1 shows the diaper 1 in an unfolded, flat state (unfolded and stretched state) in which the elastic members of each portion are stretched to achieve the design dimensions without any effect of the elastic members.

The diaper 1 includes a fastening tape 7 extending outward in the lateral direction Y from an end B1 in the lateral direction Y of the back region B. The fastening tape 7 includes an engagement portion 71 and a base end portion 72 fixed to the end portion B1. The engagement portion 71 is configured to be able to engage with a target tape 8 arranged on the surface of the ventral region A. The engagement portion 71 includes, for example, a hook of a hook-and-loop fastener. In this case, the target tape 8 is composed of, for example, a sheet material including a hook-and-loop fastener loop or a raised nonwoven fabric with which the hook can be engaged. When worn, the back region B and the ventral region A are integrated by the fastening tape 7 engaging with the target tape 8, and are arranged around the hips and waist of the wearer.

The crotch region C is configured to be narrower than the ventral region A and the dorsal region B, for example, and includes leg openings that are narrowed inward in the lateral direction Y. The crotch region C is capable of absorbing and retaining excrement such as urine due to a laminated structure including the absorbent 4 described below.

As shown in FIG. 2, the diaper 1 includes a top sheet 2, an absorbent body 4, a back sheet 3, and an exterior body 6. In the crotch region C, the diaper 1 has a configuration in which the exterior body 6, the back sheet 3, the absorbent body 4, and the top sheet 2 are laminated in the thickness direction Z. These members are joined to each other by known joining means such as a hot melt adhesive.

The top sheet 2 forms part of the skin-facing surface of the diaper 1 and is positioned so as to contact the wearer's skin. The top sheet 2 is liquid-permeable and is formed, for example, from a nonwoven fabric containing synthetic or natural fibers. The material for the top sheet 2 can be any sheet material that can be used as a top sheet for absorbent articles.

The absorbent body 4 is disposed between the top sheet 2 and the back sheet 3. The absorbent body 4 absorbs moisture from the wearer's excrement, such as urine, from the surface on the top sheet 2 side, and diffuses the moisture inside to retain the moisture from the excrement.
The absorbent body 4 has, for example, an absorbent core 40 and a core wrap sheet 41 .
The absorbent core 40 is mainly composed of an absorbent material capable of retaining moisture. Specifically, the absorbent core 40 has a structure in which a hydrophilic fiber stack is supported with an absorbent polymer, or a structure made of only a water-absorbent polymer, or the like.
The core wrap sheet 41 covers the absorbent core 40 and has a function of, for example, maintaining the shape of the absorbent core 40. The core wrap sheet 41 is formed, for example, of a thin, soft paper material such as tissue paper or a liquid-permeable nonwoven fabric. Note that the absorbent body 4 does not need to have a core wrap sheet 41 depending on the shape of the absorbent core 40, etc.

The back sheet 3 is disposed on the non-skin side of the absorbent body 4. The back sheet 3 is preferably leak-proof, and is made of a sheet material that is liquid impermeable and water repellent. Examples of such sheet materials include a thermoplastic resin film and a sheet material made of a laminate of such a film and a nonwoven fabric. In this embodiment, the back sheet 3 is made of a moisture-permeable film 30, which will be described later.

The exterior body 6 is disposed on the non-skin side of the back sheet 3 and forms part of the outer surface of the non-skin side of the diaper 1. From the viewpoint of realizing moisture permeability, breathability, and a good feel against the skin, the exterior body 6 is preferably composed of a nonwoven fabric, and from the viewpoint of imparting leak prevention, it is preferable that the exterior body 6 has functions such as liquid impermeability and water repellency. Examples of sheet materials constituting the exterior body 6 include air-through nonwoven fabric, spunbond nonwoven fabric, and spunbond-meltblown-spunbond (SMS) nonwoven fabric, and these can be used alone or in combination of two or more.

Furthermore, the diaper 1 preferably includes a pair of side sheets 5. The pair of side sheets 5 are arranged on the skin side of the lateral Y side portions of the top sheet 2, and form a three-dimensional gather 50 in the crotch region C. Specifically, the outer end of the side sheet 5 in the lateral Y direction is joined to a member on the non-skin side (such as the top sheet 2 and the back sheet 3 in the example of FIG. 2) by adhesive or heat sealing. On the other hand, the inner end of the side sheet 5 in the lateral Y direction is configured as a free end that is not joined to other members, and a thread-like or band-like elastic member 51 is arranged thereon. The elastic member 51 extends in the vertical direction X and is attached to the side sheet 5 in a stretched state. As a result, when worn, the inner end of the side sheet 5 in the lateral Y direction stands up against the skin side due to the contraction of the elastic member 51, and the three-dimensional gather 50 is formed. The side sheet 5 is made of a sheet material having functions such as poor liquid permeability and water repellency, and as an example, it is made of a nonwoven fabric having these functions.

As shown in Figs. 1 and 2, the diaper 1 may further include leg elastic members 52 arranged at the lateral Y side edges of the crotch region C. This allows leg gathers to be formed around the legs in the crotch region C, improving the leak-proofing and fit of the crotch region C.

1, the diaper 1 has a pair of gathers 10 arranged in the lateral side portion B2 of the back region B, which stretch in the lateral direction Y. As shown in FIG. 1, the lateral side portion B2 of the back region B is an area in the back region B where the absorbent body 4 is arranged, or an area located outside the lateral direction Y of an area obtained by virtually extending the absorbent body 4 in the longitudinal direction X. The pair of gathers 10 are arranged near the base ends 72 of the pair of fastening tapes 7. In this embodiment, the gathers 10 include a side sheet 5, a back sheet 3, and an exterior body 6. The gathers 10 can provide stretchability around the waist when the fastening tape 7 is fastened to the target tape 8 and the diaper 1 is arranged around the waist. This can improve the wearing comfort and fit of the diaper 1 around the waist.

[Gathered section configuration]
As shown in the partial cross-sectional view of FIG. 3 , the gathered portion 10 has a gathered layer 11 , an outer nonwoven fabric layer 12 , and a film layer 13 .
The gather layer 11 has a first nonwoven fabric layer 14 , a second nonwoven fabric layer 15 , and an elastic member 16 .
The gathered portion 10 is a portion in which an elastic member 16 is disposed and exhibits its stretchability. Note that, although Fig. 3 shows the configuration of the gathered portion 10 on the left side, the gathered portion 10 on the right side is configured in the same manner.

The first nonwoven fabric layer 14 is composed of a nonwoven fabric arranged on the skin side. In this embodiment, the first nonwoven fabric layer 14 is composed of a side sheet 5. Examples of nonwoven fabrics that constitute the first nonwoven fabric layer 14 include air-through nonwoven fabrics, spunbond nonwoven fabrics, and SMS nonwoven fabrics, and these can be used alone or in combination of two or more types.

The second nonwoven fabric layer 15 is composed of a nonwoven fabric arranged on the non-skin side of the first nonwoven fabric layer 14. In this embodiment, the second nonwoven fabric layer 15 is composed of a nonwoven fabric arranged on the non-skin side of the side sheet 5, for example, separate from the side sheet 5 and the exterior body 6 (see FIG. 1). As such a nonwoven fabric, for example, a nonwoven fabric that can be used as the first nonwoven fabric layer 14 described above can be appropriately used. In FIG. 3, the second nonwoven fabric layer 15 is not directly bonded to the first nonwoven fabric layer 14, but may be appropriately bonded to the first nonwoven fabric layer 14 as long as the extensibility of the elastic member 16 is not impaired.

The elastic member 16 is disposed between the first nonwoven fabric layer 14 and the second nonwoven fabric layer 15, and extends in the horizontal direction Y. The elastic member 16 is formed of an elongated elastic member such as a thread-like or strip-like rubber. The elastic member 16 "extending in the horizontal direction Y" includes not only a state strictly parallel to the horizontal direction Y, but also a state in which the elastic member 16 extends in the horizontal direction Y as a whole. The gathered layer 11 includes at least one elastic member 16, and from the viewpoint of improving fit, it is more preferable that the gathered layer 11 includes a plurality of elastic members 16 arranged at a distance in the vertical direction X. The elastic member 16 is fixed to the first nonwoven fabric layer 14 and the second nonwoven fabric layer 15 by an adhesive or the like in a state stretched in the horizontal direction Y. This forms the gathered layer 11 that is stretchable in the horizontal direction Y.

The outer nonwoven fabric layer 12 is disposed on the non-skin side of the gather layer 11 so as to overlap the entire gather layer 11 in the thickness direction Z. The outer nonwoven fabric layer 12 constitutes the outer surface of the non-skin side of the gather portion 10, and in this embodiment, is constituted by the exterior body 6. The outer nonwoven fabric layer 12 is disposed over the entire gather portion 10 in a plan view. In FIG. 3, the outer nonwoven fabric layer 12 is not joined to the gather layer 11 in the region outside the gather portion 10 in the lateral direction Y, but in practice it may be joined as appropriate.

The film layer 13 is disposed between the gather layer 11 and the outer nonwoven fabric layer 12 so as to overlap a portion of the gather layer 11 in the thickness direction Z. By overlapping only a portion of the gather layer 11 in the thickness direction Z, it is possible to provide an area in the gathered portion 10 where the film layer 13 is not present. In the example shown in FIG. 3, the film layer 13 extends from the inner side of the gather layer 11 in the lateral direction Y to the middle part of the gather layer 11 in the lateral direction Y.

The film layer 13 is composed of a moisture-permeable film 30. In this embodiment, the moisture-permeable film 30 is a film material that constitutes the back sheet 3. In other words, the film layer 13 in this embodiment is composed of a part of the back sheet 3.

The moisture permeable film 30 constituting the film layer 13 has a property of releasing water vapor derived from excrement, sweat, etc. to the outside to suppress stuffiness. "Moisture permeability" means a property of water vapor diffusing from a high humidity side to a low humidity side according to the second law of thermodynamics without air movement. Moisture permeability can be evaluated, for example, by the value of moisture permeability measured based on JIS Z0208. The moisture permeable film 30 preferably has a value of moisture permeability of, for example, 0.5 g/100 cm ² hr or more. In order to achieve such moisture permeability, the moisture permeable film 30 preferably contains a plurality of micropores. A detailed method of measuring moisture permeability and a detailed configuration of the moisture permeable film 30 will be described later.

The gathered portion 10 has a film layer 13, which can improve the leak-proofing of the gathered portion 10. On the other hand, although the moisture-permeable film 30 constituting the film layer 13 has moisture permeability, it tends to have lower moisture permeability and breathability compared to nonwoven fabric, and it is thought that water vapor derived from excrement, sweat, etc. is trapped inside the gathered portion 10, making it prone to stuffiness. In contrast, in this embodiment, the breathability and moisture permeability of the gathered portion 10 can be improved by providing an area in the gathered portion 10 where the film layer 13 is not present. Furthermore, in this embodiment, the gathered portion 10 has the following configuration from the viewpoint of improving fit and wearing comfort while effectively exerting the leak-proofing provided by the film layer 13.

The gather layer 11 is divided into a low stretch region 17 and a high stretch region 18 along the lateral direction Y. The low stretch region 17 is located inside the gather layer 11 in the lateral direction Y, and has a relatively low stretch rate in the lateral direction Y. The high stretch region 18 is located outside the low stretch region 17 in the lateral direction Y, and has a higher stretch rate in the lateral direction Y than the low stretch region 17. The stretch rate of each region in the lateral direction Y refers to the ratio of the length of each region in the lateral direction Y in the expanded and stretched state in which the diaper 1 is stretched flat to the length of each region in the lateral direction Y in the natural state in which no external force is applied to the gather layer 11.

(Method of measuring elongation rate)
The gathered portion 10 of the diaper 1 is cut out to obtain a cut piece. The range of the gathered portion 10 in the longitudinal direction X is the range in which the elastic member 16 is arranged, and the range in the transverse direction Y is the range in which the elastic member 16 exerts its stretchability. The cut piece in its natural state in which the elastic member 16 is not stretched is visually confirmed, and the boundary between the low elongation region 17 and the high elongation region 18 is marked with a marker or the like. The boundary is a portion where the height of the gathers changes, but if the height of the gathers is difficult to distinguish, it may be the position of the end of the film layer 13 in the transverse direction Y that is visible in a plan view in the natural state. The cut piece is further cut along the longitudinal direction X at the marked positions to obtain measurement samples of the low elongation region 17 and the high elongation region 18, respectively. For each region sample, all of the elastic members 16 fixed by adhesive or the like are removed from the first nonwoven fabric layer 14 and the second nonwoven fabric layer 15 using an organic solvent such as ethyl acetate.
After the elastic member 16 is removed, the length of the first nonwoven fabric layer 14 or the second nonwoven fabric layer 15 in the sample in each region is measured in the lateral direction Y. This length is defined as the length of each region in the lateral direction Y in the expanded and stretched state.
Next, the length of the elastic members 16 in each removed region in their natural, unstretched state is measured. The average length of all the elastic members 16 in each region is calculated, and this value is regarded as the length of each region in its natural state in the lateral direction Y.
Then, for each region, the ratio of the length in the lateral direction Y in the expanded and stretched state to the length in the lateral direction Y in the natural state is calculated, and this is defined as the stretch rate of each region.

The low elongation region 17 is bonded to the film layer 13 which is bonded to the outer nonwoven fabric layer 12. In this configuration, the film layer 13 is arranged so as to overlap the low elongation region 17 in the thickness direction Z. The joints between the low elongation region 17 and the film layer 13, and between the film layer 13 and the outer nonwoven fabric layer 12, are formed by an adhesive such as a hot melt adhesive or a pressure sensitive adhesive, as will be described in detail later. The low elongation region 17 is integrated with the film layer 13 and the outer nonwoven fabric layer 12, so that the bending rigidity is relatively increased. As a result, in the low elongation region 17, the elongation due to the elastic member 16 is reduced. On the other hand, in the low elongation region 17, the lamination of the film layer 13 increases the leakproofness.

The high elongation region 18 is not bonded to either the film layer 13 or the outer nonwoven fabric layer 12. In other words, the high elongation region 18 is not constrained by either the film layer 13 or the outer nonwoven fabric layer 12. This reduces the bending rigidity of the high elongation region 18, allowing the elastic member 16 to fully exert its elongation in the high elongation region 18.

Furthermore, at least a portion of the high elongation region 18 does not overlap with the film layer 13 in the thickness direction Z. For example, the entire high elongation region 18 does not have to overlap with the film layer 13 in the thickness direction Z, or a portion of the high elongation region 18 does not have to overlap with the film layer 13 in the thickness direction Z. As a result, as shown in FIG. 3, a gap S is formed between the high elongation region 18 and the outer nonwoven fabric layer 12 without the film layer 13 in between. Therefore, with the above configuration, the flexibility of the high elongation region 18 can be increased, and the gap S can increase the breathability of the gathered portion 10.

[Effects of the above configuration]
In the above configuration, the film layer 13 is laminated with the low elongation region 17, thereby improving the leakproofness of the region on the inside in the lateral direction Y, where excrement leakage is particularly likely to occur in the gathered portion 10. Furthermore, by providing the high elongation region 18 on the outside in the lateral direction Y, the elongation of the gathered portion 10 can be sufficiently ensured and the fit can be maintained. In addition, the high elongation region 18 includes a region that does not overlap with the film layer 13, thereby improving the flexibility of the high elongation region 18 and giving the high elongation region 18 a fluffy and soft feel. This improves the feel on the skin and improves the wearing comfort. In addition, in the above configuration, the gap S functions as an air passage, and the breathability in the gathered portion 10 can be improved. As a result, stuffiness in the gathered portion 10 can be suppressed, and skin troubles associated with stuffiness can be suppressed. Therefore, according to the absorbent article (diaper 1) of the above configuration, it is possible to have high fitting and leakproofness around the waist, while having a good wearing comfort and preventing stuffiness and skin troubles.

In order to reliably obtain the above-mentioned effects, it is preferable that the elongation rates of the low elongation region 17 and the high elongation region 18 be within the following ranges.
The elongation percentage of the low elongation region 17 is preferably 110% or more, more preferably 120% or more, and is preferably 200% or less, more preferably 190% or less.
The elongation percentage of the high elongation region 18 is preferably 130% or more, more preferably 140% or more, and is preferably 300% or less, more preferably 280% or less.
The ratio of the elongation rate of the low elongation region 17 to the elongation rate of the high elongation region 18 is preferably 30% or more, more preferably 40% or more, and is preferably 90% or less, more preferably 80% or less.

[Example of film layer configuration]
Although the film layer 13 may be discontinued, for example, at the boundary between the low elongation region 17 and the high elongation region 18, from the viewpoint of stably forming the above-mentioned gap S, it is preferable that the film layer 13 extends slightly outward in the lateral direction Y from the boundary between the low elongation region 17 and the high elongation region 18. From this viewpoint, it is preferable that the film layer 13 has a first bonding region 31 and an end region 32.

The first bonding region 31 is a region bonded to the low elongation region 17 and the outer nonwoven fabric layer 12, and is arranged, for example, so as to overlap the low elongation region 17 in the thickness direction Z. The first bonding region 31 includes, for example, a skin side bonding portion H1 and a non-skin side bonding portion H2. The skin side bonding portion H1 is arranged on the skin side and bonds the low elongation region 17. The non-skin side bonding portion H2 is arranged on the non-skin side and bonds the outer nonwoven fabric layer 12. The skin side bonding portion H1 and the non-skin side bonding portion H2 are composed of, for example, an adhesive such as a hot melt adhesive or a pressure sensitive adhesive, and may be arranged continuously or discontinuously in the first bonding region 31. When the skin side bonding portion H1 and the non-skin side bonding portion H2 are arranged discontinuously, they have a discontinuous coating pattern. Examples of such coating patterns include a stripe shape, a spiral shape, a summit shape, an omega shape, and a curtain shape.

The end region 32 includes a side end 35 and is located on the outside in the lateral direction Y of the first joining region 31. The side end 35 is the end of the moisture permeable film 30 on the outside in the lateral direction Y, and is the end on the outside in the lateral direction Y when the moisture permeable film 30 is stretched in a flat shape. In the example shown in FIG. 3, the end region 32 is a region that extends outward in the lateral direction Y from the boundary of the low elongation region 17. By providing the end region 32, the outer nonwoven fabric layer 12 can be separated from the uneven high elongation region 18 to the non-skin side at the boundary between the high elongation region 18 and the low elongation region 17. This allows the gap S to be formed stably, and the breathability of the gathered portion 10 can be effectively improved.

The dimension of the end region 32 in the horizontal direction Y is preferably 5 mm or more, more preferably 7 mm or more, from the viewpoint of increasing the thickness of the gap S, and is preferably 30 mm or less, more preferably 25 mm or less, from the viewpoint of suppressing an increase in the rigidity of the gathered portion 10. The dimension of the end region 32 in the horizontal direction Y means the dimension in the horizontal direction Y when the moisture permeable film 30 of the end region 32 is stretched out in a plane.

Furthermore, it is preferable that the end region 32 has a second bonding region 33 adjacent to the first bonding region 31 in the horizontal direction Y. The second bonding region 33 is not bonded to the gather layer 11, and is bonded to the outer nonwoven fabric layer 12. In other words, the second bonding region 33 is not bonded to the high elongation region 18 that may face the thickness direction Z. On the other hand, in the second bonding region 33, a non-skin side bonding portion H2 extends outward in the horizontal direction Y from the first bonding region 31. The non-skin side bonding portion H2 in the second bonding region 33 is made of, for example, an adhesive such as a hot melt adhesive or a pressure sensitive adhesive, similar to the first bonding region 31, and is arranged continuously or discontinuously.

By including the second bonding region 33 in which the end region 32 is bonded to the outer nonwoven fabric layer 12, the rigidity of the outer nonwoven fabric layer 12 located near the boundary between the low elongation region 17 and the high elongation region 18 can be locally increased. This makes it easier for the outer nonwoven fabric layer 12 to separate from the uneven gather layer 11 toward the non-skin side, and allows the gap S to be formed larger. Therefore, the above configuration can more effectively increase the breathability of the gather portion 10.

Furthermore, it is preferable that the end region 32 includes a side end portion 35 and has a non-bonded region 34 that is not bonded to either the gather layer 11 or the outer nonwoven fabric layer 12. When the end region 32 has a second bonded region 33, the non-bonded region 34 is located outside the second bonded region 33 in the lateral direction Y. By having the end region 32 have the non-bonded region 34, the non-bonded region 34 becomes easier to bend toward the skin in the thickness direction Z, and the thickness of the gap S can be made larger. This makes it possible to more effectively increase the breathability of the gathered portion 10.

Specifically, from the viewpoint of effectively increasing the thickness of the gap S, the dimension of the non-bonded region 34 in the horizontal direction Y is preferably 5 mm or more, and more preferably 7 mm or more. Also, from the viewpoint of suppressing an increase in the rigidity of the gathered portion 10, the dimension of the non-bonded region 34 in the horizontal direction Y is preferably 30 mm or less, and more preferably 20 mm or less. The dimension of the non-bonded region 34 in the horizontal direction Y means the dimension in the horizontal direction Y when the moisture permeable film 30 of the non-bonded region 34 is stretched out in a plane.

Furthermore, it is preferable that the non-bonded region 34 is turned up toward the skin side. This allows a thick gap S to be formed more reliably, and the breathability of the gathered portion 10 can be improved even more effectively. The non-bonded region 34 may be folded back toward the inside in the lateral direction Y, or may be raised toward the skin side in the thickness direction Z. Such turning up of the non-bonded region 34 may be formed by previously imparting a crease to the moisture permeable film 30, or may be formed so that the non-skin side is pulled by sufficiently bonding a low-basis-weight moisture permeable film 30 as described below to the outer nonwoven fabric layer 12, and the non-skin side is naturally turned up.

[Example of gather layer configuration]
From the viewpoint of improving breathability, the gather layer 11 is preferably configured as follows.
For example, the elastic member 16 preferably includes gather joints H3 that join the first nonwoven fabric layer 14 and the second nonwoven fabric layer 15 and are discontinuously arranged along the lateral direction Y. The gather joints H3 are arranged throughout the low elongation regions 17 and the high elongation regions 18 and are alternately arranged with non-jointed portions along the lateral direction Y. This allows the elastic member 16 to be discontinuously joined to the first nonwoven fabric layer 14 and the second nonwoven fabric layer 15.

The gather joint H3 may be configured with an adhesive, such as a hot melt adhesive, or a pressure sensitive adhesive, disposed on the elastic member 16. Examples of discontinuous application patterns in the gather joint H3 include stripe, spiral, summit, omega, and curtain patterns. When the gather joint H3 is configured with an adhesive, the adhesive may be applied to both the skin side and non-skin side of the elastic member 16, or may be applied to either the skin side or non-skin side. For example, when the elastic member 16 has an elongated shape such as rubber thread, by applying the adhesive to either the skin side or non-skin side of the elastic member 16, the adhesive can migrate to the opposite side due to its fluidity, and both the first nonwoven fabric layer 14 and the second nonwoven fabric layer 15 can be bonded.

In the above configuration, the first nonwoven fabric layer 14 and the second nonwoven fabric layer 15 protrude from each other in the thickness direction Z at the non-jointed portion so as to be spaced apart from the elastic member 16 (see FIG. 3), forming vertical pleats F extending in the vertical direction X. The interior of these vertical pleats F can function as air passages, improving the breathability of the gathered layer 11. Furthermore, the vertical pleats F that are not joined to the elastic member 16 have high flexibility in the thickness direction Z, and therefore have a soft and fluffy feel. This improves the feel of the gathered layer 11 against the skin.

[Example of moisture permeable film configuration]
Hereinafter, there will be described a preferred example of the structure of the moisture permeable film 30 constituting the film layer 13. When the film layer 13 is constituted by the back sheet 3, it is preferred that the back sheet 3 has the following structure.

The moisture-permeable film 30 preferably has a plurality of micropores (microvoids). The moisture-permeable film is, for example, made of a resin film and has a single-layer structure or a laminated structure. The moisture-permeable film is obtained, for example, by melt-kneading a hydrophobic thermoplastic resin (such as a polyolefin resin) and inorganic fine particles (such as calcium carbonate) that are incompatible with the thermoplastic resin to form a film, and then stretching the film uniaxially or biaxially. The film can be formed, for example, by an inflation method or a T-die method. In the moisture-permeable film manufactured in this way, a large number of micropores are formed starting from the interface between the thermoplastic resin and the inorganic fine particles by stretching.

As shown in Figures 4(A) and (B), in the moisture-permeable film 30, a force is applied to inorganic fine particles 36 such as calcium carbonate particles along the stretching direction E during stretching, and the inorganic fine particles 36 are pulled in the stretching direction E, forming micropores 37. Therefore, the moisture-permeable film 30 includes inorganic fine particles 36 and micropores 37 adjacent to the inorganic fine particles 36.

In the moisture-permeable film 30, for example, it is preferable that the pore volume per unit mass of the micropores 37 having a pore diameter in the range of 0.06 μm to 0.16 μm is larger than the pore volume per unit mass of the micropores 37 having a pore diameter in the range of 2.5 μm to 3.5 μm. This allows a large number of micropores 37 having small pore diameters in the range of 0.06 μm to 0.16 μm to be formed, thereby increasing the permeability of water vapor (moisture). On the other hand, the number of micropores 37 having a pore diameter in the range of 2.5 μm to 3.5 μm can be regulated, and moisture leakage can be more reliably prevented. Therefore, a moisture-permeable film 30 with high leak-proof properties can be obtained.

(Method of measuring pore volume)
The pore volume can be measured by the following method in accordance with the mercury intrusion method specified in JIS R 1655. First, a measurement sample of a predetermined size (for example, 10 mm x 10 mm) is cut out from the moisture-permeable film 30 to be measured. This measurement sample is set in a mercury porosimeter (for example, "Autopore IV9520", manufactured by Shimadzu Corporation), and the pore size distribution in the pore diameter range of 0.06 μm to 3.5 μm is measured. Based on the obtained pore size distribution (see FIG. 5), the cumulative pore volume in the pore diameter range of 0.06 μm to 0.16 μm and the cumulative pore volume in the pore diameter range of 2.5 μm to 3.5 μm are measured. If the cumulative pore volume in the pore diameter range of 0.06 μm or more and 0.16 μm or less is greater than the cumulative pore volume in the pore diameter range of 2.5 μm or more and 3.5 μm or less, it is determined that "the pore volume per unit mass of micropores having pore diameters in the range of 0.06 μm or more and 0.16 μm or less is greater than the pore volume per unit mass of micropores having pore diameters in the range of 2.5 μm or more and 3.5 μm or less."

As such, a method of forming a large number of small micropores 37 includes, for example, a method of uniformly stretching the moisture-permeable film 30. As shown in FIG. 4A, if the moisture-permeable film 30 is stretched non-uniformly, a region that is not sufficiently stretched will occur in part of the moisture-permeable film 30, and a portion that cannot be sufficiently opened from the small inorganic fine particles 36 (unopened portion 38 shown by a thick line) may be formed. Furthermore, in the area of the moisture-permeable film 30 where the stretching force is large, the inorganic fine particles 36 are pulled to a large extent, forming large micropores 37, and in the area where the stretching force is small, the inorganic fine particles 36 are not pulled so much, making it easier for small micropores 37 to be formed. For this reason, the size of the micropores 37 may not be correlated with the size of the inorganic fine particles 36.

In contrast, as shown in FIG. 4(B), when the moisture-permeable film 30 is stretched uniformly, a sufficient stretching force is applied to the small inorganic fine particles 36 as well. As a result, the unopened portion 38 in the example of FIG. 4(A) becomes a fully opened micropore 37 (part shown by the thick line) in FIG. 4(B), and the number of small micropores 37 can be increased. Furthermore, when the moisture-permeable film 30 is stretched uniformly within its plane, micropores 37 corresponding to the size of the inorganic fine particles 36 are easily formed, and therefore there is a tendency for the size of the micropores 37 and the size of the inorganic fine particles 36 to be positively correlated.

As an index of uniform stretching of the moisture-permeable film 30, in a plan view seen from the thickness direction Z, the pore diameter of the micropores 37 arranged adjacent to the inorganic fine particles 36 having a size of 0.01 ^μm2 or more and ^0.5 μm2 or less is preferably smaller than the diameter of the micropores 37 arranged adjacent to the inorganic fine particles 36 having a size of ^1.0 μm2 or more and 1.5 μm2 or ^less . In the above configuration, since the moisture-permeable film 30 is uniformly stretched, the number of small micropores 37 adjacent to the small inorganic fine particles 36 can be increased, and a moisture-permeable film 30 having high moisture permeability and leakproofness can be obtained.

(Method of measuring size of inorganic fine particles and pore diameter of fine pores)
A sample for evaluation of a predetermined size (for example, 10 mm x 10 mm) is cut out from the moisture-permeable film 30. The cut-out sample for evaluation is fixed according to a conventional method and imaged at 1000 times magnification with a scanning electron microscope (SEM). From one image, the outlines of the portions corresponding to the inorganic fine particles and the adjacent micropores are extracted using an image analysis technique. The size of the area corresponding to the extracted inorganic fine particles and the size of the area corresponding to the adjacent micropores are measured. The pore diameter of the micropores is obtained by calculating the circle equivalent diameter from the size (area) of the area corresponding to the extracted micropores. Images of 100 locations are taken from one sheet of moisture-permeable film 30, and the average value of the pore diameters of the micropores arranged adjacent to inorganic fine particles having a size of 0.01 μm ² or more and 0.5 μm ² or less and the average value of the pore diameters of the micropores arranged adjacent to inorganic fine particles having a size of 1.0 μm ² or more and 1.5 μm ² or less are calculated.

As described above, when the micropores 37 are formed according to the size of the inorganic fine particles 36, the pore diameter of the micropores 37 can also be controlled by controlling the distribution of the size of the inorganic fine particles 36. From this viewpoint, in the moisture-permeable film 30, in a plan view seen from the thickness direction Z, it is preferable that the number of particles per unit area of the inorganic fine particles 36 having a size of 0.01 μm ² or more and 0.5 μm ² or less is smaller than the number of particles per unit area of the inorganic fine particles ³⁶ having a size of 0.5 μm ² or more and less than 2.0 μm ² , and the number of particles per unit area of the inorganic fine particles 36 having a size of 2.0 μm 2 or more is smaller than the number of particles per unit area of the inorganic fine particles 36 having a size of 0.5 μm ² or more and less than 2.0 μm ^2. With the above configuration, it is possible to form many minute micropores 37, and to obtain a moisture-permeable film 30 that satisfies both moisture permeability and leak prevention properties.

In addition, it is preferable that the moisture-permeable film 30 is configured to be thin while maintaining leakproofness by being uniformly stretched as described above. From this viewpoint, the basis weight of the moisture-permeable film 30 is preferably 8 g/ ^cm2 or more, more preferably 10 g/ ^cm2 or more, and is preferably 20 g/ ^cm2 or less, more preferably 18 g/ ^cm2 or less.

The moisture permeability of the moisture permeable film 30 is preferably 2.7 g/ ¹⁰⁰ cm2·h or more, more preferably 3 g/ ¹⁰⁰ cm2·h or more, and is preferably 12 g/ ¹⁰⁰ cm2·h or less, more preferably 10 g/ ¹⁰⁰ cm2·h or less. This allows the moisture permeability of the moisture permeable film 30 to be sufficiently high, making it possible to provide a comfortable diaper 1 with less stuffiness, while also ensuring the leakproofness of the moisture permeable film 30.

(Method of measuring moisture permeability)
The moisture permeability can be measured in accordance with JIS Z0208.
First, prepare a cup containing calcium chloride as a moisture absorbent, and place the cup horizontally. The mass of calcium chloride before the test is measured in advance. The moisture-permeable film to be measured is cut into a circle with a diameter 10 mm larger than the inner diameter of the cup to prepare a test piece, and place the test piece on the upper edge of the cup and adjust it so that the periphery of the test piece is located on a concentric circle of the upper edge of the cup. Prepare a ring-shaped packing along the upper edge of the cup, and push the packing so that the periphery of the test piece is in close contact with the upper edge of the cup. Furthermore, place a ring-shaped weight on it to prepare a test piece in which the moisture-permeable film is fixed to the upper edge of the cup. Leave this test piece at a temperature of 30°C ± 0.5°C and a humidity of 90 ± 2% RH for 1 hour, and measure the mass of calcium chloride after the test. Calculate the value obtained by subtracting the mass of calcium chloride before the test from the mass of calcium chloride after the test, and convert this to a value per 100 ^cm2 of the water vapor permeable surface of the test piece to calculate the moisture permeability.

[Other embodiments]
Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and scope of the present invention.

For example, the end region 32 may not have the second bonding region 33 and may be entirely configured as the non-bonded region 34. Alternatively, the end region 32 may not have the non-bonded region 34 and may be entirely configured as the second bonding region 33. As another example, the film layer 13 may not have the end region 32. In this case, the side end 35 of the film layer 13 forms the peripheral portion of the first bonding region 31 in the horizontal direction Y.

The sheet material included in the gathered portion 10 may be a sheet material different from the sheet material arranged in the crotch region C. For example, the first nonwoven fabric layer 14 may be composed of a nonwoven fabric different from the side sheet 5, and the moisture-permeable film constituting the film layer 13 may be a film material different from the back sheet. In addition, the outer nonwoven fabric layer 12 may be composed of a nonwoven fabric different from the exterior body 6.

1...Absorbent articles (disposable diapers)
Reference Signs List 2...Top sheet 3...Back sheet 4...Absorbent body 7...Fastening tape 10...Gathered portion 11...Gathered layer 12...Outer nonwoven fabric layer 13...Film layer 14...First nonwoven fabric layer 15...Second nonwoven fabric layer 16...Elastic member 17...Low elongation region 18...High elongation region 30...Moisture permeable film A...Ventral region B...Dorsal region C...Crotch region

Claims (13)

An absorbent article having a vertical direction extending from a wearer's abdomen through a crotch region to a back side, a horizontal direction perpendicular to the vertical direction and corresponding to a left-right direction of the wearer, and a thickness direction perpendicular to the vertical direction and the horizontal direction, and further divided along the vertical direction into a abdomen region, a crotch region, and a back region,
A pair of fastening tapes extending laterally outward from ends of the back region in the lateral direction;
A pair of gathers arranged on the lateral sides of the back region and stretchable in the lateral direction,
The gathered portion is
a gather layer having a first nonwoven fabric layer disposed on the skin side, a second nonwoven fabric layer disposed on the non-skin side of the first nonwoven fabric layer, and an elastic member disposed between the first nonwoven fabric layer and the second nonwoven fabric layer and extending in the lateral direction;
an outer nonwoven fabric layer disposed on the non-skin side of the gather layer so as to overlap the entire gather layer in the thickness direction;
a film layer that is disposed between the outer nonwoven fabric layer and the gather layer so as to overlap a portion of the gather layer in the thickness direction, the film layer being made of a moisture permeable film;
The gather layer is
A low elongation region;
a high elongation region disposed laterally outward of the low elongation region and having a higher elongation rate in the lateral direction than the low elongation region;
The low elongation region is
bonded to the film layer bonded to the outer nonwoven fabric layer,
The high elongation region is
an absorbent article which is not bonded to either the film layer or the outer nonwoven fabric layer, and at least a portion of which does not overlap with the film layer in the thickness direction. The film layer comprises:
a first bonding region bonded to the low elongation region and the outer nonwoven fabric layer;
The moisture permeable film further includes a side end portion that is an end portion on the outer side in the lateral direction, and further includes an end portion region located on the outer side in the lateral direction of the first bonding region,
The absorbent article of claim 1 , wherein the end regions are not joined to the gather layer. The end region is
a second bonding region adjacent to the first bonding region in the laterally direction;
The absorbent article according to claim 2 , wherein the second bonding region is bonded to the outer nonwoven fabric layer. The end region is
The absorbent article according to claim 2 or 3, further comprising a non-bonded region that includes the side end portion and is not bonded to either the gathered layer or the outer nonwoven fabric layer. The absorbent article according to claim 4 , wherein the non-bonded region has a dimension in the lateral direction of 5 mm or more. The absorbent article according to claim 4 or 5, wherein the non-bonded region is turned up toward the skin. The absorbent article according to claim 1 , wherein the high elongation region has a dimension in the lateral direction of 10 mm or more. The elastic member is
The absorbent article according to claim 1 , further comprising a gather joint that joins the first nonwoven fabric layer and the second nonwoven fabric layer and is discontinuously arranged along the lateral direction. The absorbent article according to claim 1 , wherein the moisture-permeable film has a plurality of micropores. The absorbent article according to claim 9 , wherein the moisture permeability of the moisture permeable film is 2.7 g/100 cm ² ·h or more and 12 g/100 cm ² ·h or less. In the moisture-permeable film,
11. The absorbent article according to claim 9 or 10, wherein the pore volume per unit mass of the micropores having a pore diameter in the range of 0.06 μm or more and 0.16 μm or less is greater than the pore volume per unit mass of the micropores having a pore diameter in the range of 2.5 μm or more and 3.5 μm or less. The moisture-permeable film has inorganic fine particles disposed adjacent to the micropores,
In the moisture permeable film, when viewed in a plan view from the thickness direction,
The absorbent article according to any one of claims ⁹ to ¹¹ , wherein the pore diameter of the micropores arranged adjacent to the inorganic fine particles having a size of 0.01 µm2 or more and 0.5 µm2 or less is smaller than the pore diameter of the micropores arranged adjacent to the inorganic fine particles having a size of 1.0 µm2 ^or more and 1.5 µm2 or ^less . In the moisture permeable film, when viewed in a plan view from the thickness direction,
The number of particles per unit area of the inorganic fine particles having a size of 0.01 μm ² or more and 0.5 μm ^{2 or less is less than the number of particles per unit area of the inorganic fine particles having a size of 0.5 μm 2 or} more and less than 2.0 μm ² , and
The absorbent article according to claim 12, wherein the number of particles per unit area of the inorganic fine particles having a size of ^{2.0 μm2} or more is smaller than the number of particles per unit area of the inorganic fine particles having a size of 0.5 ^μm2 or more and less than 2.0 μm2.

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