JP7701282B2 - Shorts-type absorbent article - Google Patents

Description

The present invention relates to shorts-type absorbent articles such as shorts-type sanitary napkins and disposable diapers, and in particular to shorts-type absorbent articles in which the back region of the absorbent body is easily deformed to conform to the valley between the buttocks and the bulge of the buttocks.

Numerous shorts-type absorbent articles have been proposed to improve fit and prevent leakage. For example, Patent Document 1 discloses an absorbent article in which a plurality of recesses are formed in an absorbent core, in a rear portion of the core that is located rearward of the center position of the absorbent article in the longitudinal direction, and distributed in the longitudinal and lateral directions, and the recesses are formed by through-holes or low basis weight portions. Patent Document 2 also discloses a pants-type diaper in which the absorbent body has at least one channel (low basis weight portion of the absorbent body) extending along the longitudinal direction, and at least one of the back waist belt and the ventral waist belt is located in the widthwise center, extends outward from the inner edge in the longitudinal direction, has a low stretch area with low stretchability in the width direction, and is adjacent to both sides of the low stretch area in the width direction, has a pair of high stretch areas with high stretchability in the width direction, at least one of the rear and front longitudinal portions of the channel overlaps with the low stretch area in the thickness direction, and in a plan view, the inner edge in the width direction of each of the pair of high stretch areas is located between the edge of the absorbent body facing the high stretch area in the width direction and the channel.

JP 2018-102716 A JP 2020-108746 A

However, as described in Patent Documents 1 and 2 above, when a perforation or low basis weight portion is formed in the absorbent body to prevent distortion of the absorbent body and improve the fit, the liquid retention of the absorbent body decreases accordingly, increasing the possibility of leakage to the outside.

Furthermore, users of disposable shorts- or pants-type sanitary napkins use them in the hope that they will not leak no matter what position they sleep in, will not soil bedding such as sheets or bedding, and will not require the trouble of washing as they do not require wearing cloth shorts. However, because the absorbent body does not easily deform along the cleavage of the buttocks, menstrual blood tends to flow down the buttocks groove to the back, causing leakage from the back waist area. This can be particularly unsettling on nights when menstrual flow is heavy, and the quality of sleep deteriorates.

The main objective of the present invention is to provide a shorts-type absorbent article that maintains the liquid-retaining properties of the absorbent body while allowing the absorbent article to easily deform along the gap between the buttocks and the bulge of the buttocks, thereby preventing leakage from the back side.

In a first aspect for solving the above problems, a shorts-type absorbent article is provided which comprises an absorbent main body having an absorbent body interposed between a liquid-permeable top sheet and a liquid-impermeable leak-proof sheet, and an exterior body which is integrally provided on the outer surface side of the absorbent main body, and in a product state, a waist opening and a pair of left and right leg openings are formed by joining the front and rear sections of the exterior body at both side portions,
An embossed groove is provided on the leakproof sheet side of the absorbent body along a portion corresponding to the buttocks of a wearer, the groove being recessed toward the top sheet side;
A plurality of first linear elastic portions are provided across the embossed groove and spaced apart along the embossed groove,
The present invention provides a shorts-type absorbent article, characterized in that a second linear stretch portion is provided along approximately the width direction of the shorts-type absorbent article, and a third linear stretch portion is provided along approximately the front-to-rear direction of the shorts-type absorbent article, so as to surround the top of the bulge of the wearer's buttocks.

In the first aspect, an embossed groove is provided on the leakproof sheet side of the absorbent body along the area corresponding to the wearer's buttocks groove, which is recessed into the top sheet side, and a plurality of the first linear stretchable parts are provided so as to cross this embossed groove, so that the embossed groove becomes the folding base due to the contraction force of the first linear stretchable parts, and the absorbent body is easily deformed into a protrusion on the skin side along the buttocks groove, and the absorbent body fits securely into the valley between the buttocks. In addition, the second linear stretchable part and the third linear stretchable part are provided so as to surround the top of the bulge of the wearer's buttocks, and the contraction force of these second linear stretchable part and third linear stretchable part causes the absorbent body to deform three-dimensionally along the bulge of the buttocks. In this way, the absorbent body deforms along the valley and bulge of the buttocks and fits the shape of the wearer's buttocks, so leakage from the back side can be reliably prevented. This effect is achieved without providing any penetrations or low basis weight parts in the absorbent body of the absorbent body, and the liquid retention of the absorbent body is maintained.

In a second aspect, the shorts-type absorbent article according to claim 1 is provided, in which the first linear stretchable portion and the second linear stretchable portion are provided on the exterior body, and the third linear stretchable portion is provided on the absorbent body.

In the second aspect, the flow direction in the production line is aligned with the direction in which each linear stretchable portion extends, and from the viewpoint of manufacturing, the first linear stretchable portion and the second linear stretchable portion are provided on the exterior body, and the third linear stretchable portion is provided on the absorbent body, to facilitate manufacturing.

As a third aspect, the shorts-type absorbent article according to claim 1 or 2 is provided, in which the third linear stretchable portion is provided only on the outer widthwise portion of the wearer's buttocks and not on the inner widthwise portion.

In the third aspect, the second and third linear stretchable parts are arranged to surround the top of the wearer's buttocks, and the third linear stretchable part is arranged only on the widthwise outer part of the buttocks, and not on the widthwise inner part. This allows the second and third linear stretchable parts to be arranged to surround the top of the wearer's buttocks in a roughly U-shape. Since the widthwise inner side is close to the buttocks groove, if the contraction force in the front-to-back direction is too strong, the part that has deformed along the buttocks valley will have unevenness in the front-to-back direction, making it difficult for the absorbent body to fit into the buttocks groove.

As a fourth aspect, the shorts-type absorbent article according to any one of claims 1 to 3 is provided, in which the first linear stretch portion, the second linear stretch portion, and the third linear stretch portion are provided in an area that overlaps with the absorbent body in the thickness direction.

In the fourth aspect, each linear stretchable portion is primarily intended to deform the absorbent body along the valleys and bulges of the buttocks, and is therefore arranged only in areas that overlap the absorbent body in the thickness direction, and is not arranged to extend beyond the absorbent body.

As a fifth aspect, the shorts-type absorbent article according to any one of claims 1 to 4 is provided, in which the first linear stretch portion, the second linear stretch portion, and the third linear stretch portion are each made of a thread-like elastic stretch material.

In the fifth aspect, the first linear stretch section, the second linear stretch section, and the third linear stretch section are each made of a thread-like elastic stretch member. This allows the absorbent body to reliably deform along the valleys and bulges of the buttocks due to the contractile force of the thread-like elastic stretch member.

In a sixth aspect, the exterior body is a stretchable sheet in which a stretchable elastic film is laminated between a first sheet layer having no stretchability and a second sheet layer, and the first sheet layer and the second sheet layer are joined at a number of spaced joints directly or via an elastic film, and the stretchable sheet is contracted by the contraction force of the elastic film and is stretchable when an external force is applied,
The present invention provides a shorts-type absorbent article as described in any one of claims 1 to 4, wherein the first linear stretchable portion and the second linear stretchable portion are constituted by areas where the area ratio of the joint provided in a predetermined portion of the stretch sheet is different from that of adjacent areas, and the third linear stretchable portion is constituted by a thread-like elastic stretchable material.

In the sixth aspect, the exterior body is made of a stretchable sheet in which an elastic film is laminated between a first sheet layer and a second sheet layer, and the first linear stretchable portion and the second linear stretchable portion are formed by portions of the stretchable sheet in which the joint area ratio is changed. This eliminates the need for a process for arranging a thread-like elastic stretchable member in the exterior body, simplifying manufacturing.

In a seventh aspect, a shorts-type absorbent article according to any one of claims 1 to 6 is provided, in which the outer contour of the back edge of the absorbent body has a constricted portion in the center that is recessed toward the center in the front-to-rear direction, and bulging portions formed of curves that bulge outward in the front-to-rear direction are formed on both sides of the constricted portion.

In the seventh aspect, the outer contour of the rear edge of the absorbent body is formed into a predetermined shape, making it easier for the rear region of the absorbent body to deform along the valley between the buttocks and the bulge of the buttocks.

As explained above in detail, according to the present invention, the absorbent article can easily deform along the gap and bulge of the buttocks while maintaining the liquid retention of the absorbent body, preventing leakage from the back side.

1 is a perspective view showing a shorts-type napkin 1 according to the present invention. FIG. 2 is a plan view of the skin contact surface side in an unfolded state. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. 4 is a cross-sectional view taken along line IV-IV in FIG. 2. FIG. 2 is an exploded perspective view of the shorts-type napkin 1. 5A is a view taken along line VIA-VIA in FIG. 5, (B) is a view taken along line VIB-VIB in FIG. 5, and (C) is a view taken along line VIC-VIC in FIG. FIG. 2 is an explanatory cross-sectional view of the stretch sheet before bonding. FIG. 4 is a cross-sectional view for explaining a joining state of the stretch sheet. FIG. 2 is a cross-sectional view for explaining a contracted state of the stretch sheet. FIG. 4 is a cross-sectional view for illustrating a joining state of a stretch sheet in which a through hole is formed. 1 is a schematic diagram of an example of a stretching and joining means. FIG. 11 is a plan view of an example of an arrangement pattern of joints. 11A to 11C are schematic plan views of examples in which the bonded area ratios are different. FIG. 13 is a plan view for explaining an example of forming a through hole. 11A to 11C are explanatory plan views of examples of through-hole formation in different modes. 11A to 11C are explanatory diagrams illustrating another example of a through-hole forming method. 1A to 1C are plan views showing various examples of arrangements of joints.

The following describes in detail the embodiments of the present invention with reference to the drawings.

As shown in Figs. 1 and 2, the shorts-type napkin 1 of the present invention is composed of an absorbent body 10 in which an absorbent body 13 is sandwiched between a liquid-permeable top sheet 11 and a liquid-impermeable leak-proof sheet 12, and an exterior body 20 that is integrally provided on the outer surface side of the absorbent body 10. In the product state shown in Fig. 1, the front and rear portions of the exterior body 20 are joined at the side seal portions 2 on both sides to form a shorts-type sanitary napkin with a waist opening W and a pair of left and right leg openings L, L.

(Structure of the absorbent body 10)
First, an example of the structure of the absorbent body 10 will be described with reference to Figures 2 to 5. The absorbent body 10 absorbs and retains body fluids, and is configured by sandwiching an absorbent body 13 made of cotton-like pulp or the like between a liquid-permeable top sheet 11 made of nonwoven fabric or the like and a liquid-impermeable leak-proof sheet 12 made of polyethylene or the like.

The surface sheet 11 is preferably made of a nonwoven fabric with or without holes, a porous plastic sheet, or the like. The fibers constituting the nonwoven fabric may be synthetic fibers such as olefins such as polyethylene or polypropylene, polyesters, or polyamides, as well as regenerated fibers such as rayon or cupra, or natural fibers such as cotton. Nonwoven fabrics obtained by appropriate processing methods such as spunlace, spunbond, thermal bond, meltblown, and needle punch can be used. Of these processing methods, the spunlace method is excellent in terms of flexibility and drapeability, and the thermal bond method is excellent in terms of bulk and high compression recovery. When a large number of through holes are formed in the surface sheet 11, bodily fluids are quickly absorbed, and the sheet has excellent dry touch. The fibers of the nonwoven fabric may be either long or short fibers, but it is preferable to use short fibers to give the fabric a towel-like texture. In addition, in order to facilitate embossing, it is preferable to use olefin fibers such as polyethylene or polypropylene with a relatively low melting point. In addition, composite fibers such as core-sheath fibers, side-by-side fibers, and split fibers, which have a core made of fibers with a high melting point and a sheath made of fibers with a low melting point, can also be used.

The leak-proof sheet 12 is made of a sheet material such as polyethylene that is at least water-proof, but it is preferable to use a material that is moisture-permeable in order to prevent stuffiness. This water-proof and moisture-permeable sheet material is a microporous sheet obtained by melt-kneading an inorganic filler into an olefin resin such as polyethylene or polypropylene to form a sheet, and then stretching it in a uniaxial or biaxial direction. If the sheet thickness is the same, the rigidity is lower than that of a non-porous sheet, so it is superior in terms of flexibility. The leak-proof sheet 12 may be a polylaminated nonwoven fabric formed by laminating a plastic film and a nonwoven fabric.

As shown in the cross-sectional views of Figures 3 and 4, the top sheet 11 and the leak-proof sheet 12 are arranged to extend outward from the outer edge of the absorbent body 12, and the laminated sheet portion of the top sheet 11 and the leak-proof sheet 12 forms a flap portion at the outer edge of the absorbent body 13 without the absorbent body 13 being interposed.

The absorbent 13 interposed between the leak-proof sheet 12 and the top sheet 11 may be any material capable of absorbing and retaining bodily fluids, and is composed, for example, of cotton-like pulp and a water-absorbent polymer. The water-absorbent polymer is mixed, for example, as granular powder, into the pulp that constitutes the absorbent. 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. Coniferous pulp, which has longer fibers, is more suitable than hardwood pulp in terms of functionality and cost.

Synthetic fibers may also be mixed into the absorbent 13. The synthetic fibers may be, for example, polyolefins such as polyethylene or polypropylene, polyesters such as polyethylene terephthalate or polybutylene terephthalate, polyamides such as nylon, or copolymers of these. They may also be a mixture of two of these. Composite fibers such as core-sheath fibers with a high melting point fiber as the core and a low melting point fiber as the sheath, side-by-side fibers, and split fibers may also be used. In the case of hydrophobic fibers, it is desirable to use synthetic fibers that have been surface-treated with a hydrophilizing agent so that they have affinity for body fluids.

The absorbent body 13 in the illustrated example is surrounded by an envelope sheet 14 made of crepe paper or nonwoven fabric to maintain the shape of the absorbent body 13 and improve diffusion, but this envelope sheet 14 does not have to be provided.

The planar shape of the absorbent body 13 is formed with a larger area on the back side than on the wearer's ventral side, as shown in FIG. 2. As a specific planar shape, a constricted portion 13a is formed on both sides of the region corresponding to the wearer's crotch portion, which is recessed toward the center in the width direction, and a substantially straight front side edge is formed along the front-rear direction extending forward from the ventral side edge, and the outer line 13b of the ventral side edge connecting the left and right edges is formed as an arc-shaped curve that bulges outward. On the other hand, a rear side edge is formed from a back side edge that is approximately the same widthwise position as the ventral side edge of the constricted portion 13a toward the rear, and the rear side edge is formed from an approximately straight rear side edge along the front-rear direction extending further rearward from the edge, and the outer line 15 of the back side edge connecting the left and right edges is formed in a predetermined shape.

The outline 15 of the back edge of the absorbent body 13 has a constricted portion 16 in the center that is recessed toward the center in the front-to-rear direction, and bulging portions 17 are formed on both sides of the constricted portion 16, each of which is a curved line that bulges outward in the front-to-rear direction. By providing the constricted portion 16, the back edge of the absorbent body 13 and its neighboring portion can be easily folded along a fold line that extends in the front-to-rear direction from the bottom of the constricted portion 16 to the center in the width direction, and the rear portion of the absorbent body 13 can be easily deformed along the valley between the buttocks. In addition, by providing bulging portions 17 on both sides of the constricted portion 16, the regions on both sides that are folded in the center in the width direction can be easily deformed along the bulge of the buttocks.

2 and 4, in the present shorts-type napkin 1, an embossed groove 18 is provided on the surface of the absorbent body 10 on the leak-proof sheet 12 side (non-skin contact side) along a region corresponding to the wearer's buttocks crease, which is recessed on the top sheet 11 side (skin contact side). The embossed groove 18 is formed by squeezing at least the leak-proof sheet 12 and the absorbent body 13 together from the outer surface side of the leak-proof sheet 12, and is formed along the front-rear direction of the shorts-type napkin 1. The embossed groove 18 is a region on the rear side of the center of the front-rear direction of the shorts-type napkin 1 (CL: see FIG. 2), and extends from a region corresponding to the wearer's anus to the outline 15 of the rear edge of the absorbent body 13. By providing the embossed groove 18, the embossed groove 18 serves as a base end for bending, and the widthwise center of the rear part of the absorbent body 10 is easily deformed along the cleavage of the wearer's buttocks.

In particular, it is preferable that the embossed groove 18 is provided so that the rear edge is connected to the bottom of the constricted portion 16 formed in the center of the outline 15 of the rear edge of the absorbent body 13. This creates continuity between the effect of the absorbent body 10 deforming along the cleavage of the buttocks by forming the constricted portion 16 and the effect of the absorbent body 10 deforming along the cleavage of the buttocks by the embossed groove 18, and the combination of these two effects makes it even easier for the widthwise center of the rear portion of the absorbent body 10 to deform along the cleavage of the wearer's buttocks.

The dimensions of the embossed groove 18 are preferably 5 to 15 mm in width and 50 to 150 mm in length.

As a modified example of the absorbent body 10, although not shown, the width dimension of the top sheet 11 may be made slightly longer than the width of the absorbent body 13, and the absorbent body 13 may be merely covered, with a side sheet separate from the top sheet 11 being disposed on the outer side thereof, specifically a side sheet made of a nonwoven fabric material that has been appropriately treated to be water repellent or hydrophilic depending on the purpose of preventing the penetration of menstrual blood or vaginal discharge, or improving the feel on the skin. Such a side sheet may be made of natural fibers, synthetic fibers, or recycled fibers, and formed by an appropriate processing method, but it is preferable to use a nonwoven fabric with a reduced basis weight to provide breathability in order to eliminate the stiff feeling and prevent stuffiness.

The side sheet is bonded from the middle of the width to the outside with an adhesive such as hot melt over a range from a predetermined inner position to the outer edge of the leakproof sheet 12, and the laminated sheet portion of the side sheet and the leakproof sheet 12 forms side flap portions on both sides of the absorbent body 13 without the absorbent body 13 being interposed.

The inner side portion of the side sheet is folded almost twice, and one or more thread-like elastic stretch members are arranged in a stretched state in the longitudinal middle portion inside this double sheet, with both ends or appropriate positions in the longitudinal direction fixed. The double sheet portion is laminated at the front and rear ends to form non-standing portions bonded to the absorbent body 13, so that a pair of left and right three-dimensional gathers that stand up against the skin can be formed in the longitudinal middle portion.

(Structure of exterior body 20)
Next, the exterior body 20 will be described with reference to Figures 2 to 6. The exterior body 20 has a laminated sheet structure in which at least the waist area of the front body F and the back body B includes an inner nonwoven fabric 21 arranged on the skin side and an outer nonwoven fabric 22 arranged on the non-skin side, and an elastic stretch member is disposed in a predetermined region between the inner nonwoven fabric 21 and the outer nonwoven fabric 22 to impart stretchability in the width direction.

The laminated sheet structure including the inner nonwoven fabric 21 and the outer nonwoven fabric 22 may be provided over the entire length of the exterior body 20, but as shown in the illustrated example, the inner nonwoven fabric 21 may be divided into two parts, front and back, and arranged so that they are spaced apart in the front-to-back direction at the crotch portion, and only the outer nonwoven fabric 22 extends in the crotch portion. The exterior body 20 may also be divided into two parts, front and back, and arranged so that they are spaced apart in the front-to-back direction at the crotch portion.

The planar shape of the exterior body 20 is an overall pseudo-hourglass shape due to the concave cut lines 23 around the legs that form leg openings L on both sides of the middle.

2 and 5, the exterior body 20 is given widthwise stretchability by arranging a predetermined elastic member in the waist region 3 of the front body F, the waist region 3 of the back body B, and a part of the intermediate region 4 between them in the exterior body 20. The waist region 3 is an area defined as the vertical range of the side seal portion 2 where the front body F and the back body B are joined. The waist region 3 can be divided into a waist region 5 provided near the opening edge of the waist opening W, and a hip region 6 located toward the center in the front-to-rear direction. Here, the relationship is waist region 3 = waist region 5 + hip region 6.

2 and 5, the exterior body 20 has a plurality of thread-like elastic stretch members 24 (five in the illustrated example) fixed in a stretched state at appropriate positions between the inner nonwoven fabric 21 and the outer nonwoven fabric 22 along the width direction and at intervals in the front-rear direction in the waist area 5 with hot melt adhesive, forming a widthwise stretch area. In addition, in the waist area 6, the inner nonwoven fabric 21 and the outer nonwoven fabric 22 are joined at a number of joints 26 arranged at intervals in the width direction and the front-rear direction, with the elastic film 25 stretched in the width direction between them. In this embodiment, the waist area 3 of the front body F, the waist area 3 of the back body B, and a part of the intermediate area 4 between them constitute the stretch area made of the above-mentioned elastic stretch members (thread-like elastic stretch members 24 and elastic film 25). The center of the intermediate region 4 in the front-to-rear direction is a non-stretchable region because no elastic film 25 is present.

(Stretchable sheet using elastic film 25)
The stretchable sheet using the elastic film 25 may be the stretchable sheet described in Japanese Patent No. 6052746. The publication describes a disposable diaper having a stretchable region that is stretchable in the width direction. The contents of the publication are summarized below.

As shown in Figures 7 to 10, the stretchable region is formed by laminating an elastic film 25 stretchable in the width direction between an inner nonwoven fabric 21 made of, for example, a nonwoven fabric that has no stretchability, and an outer nonwoven fabric 22 made of, for example, a nonwoven fabric that has no stretchability, and the inner nonwoven fabric 21 and the outer nonwoven fabric 22 are joined at a number of spaced joints 26, either directly or via the elastic film 25. Here, the fact that the inner nonwoven fabric 21 and the outer nonwoven fabric 22 are "not stretchable" does not mean that they do not stretch at all, but rather that they do not stretch substantially in comparison with the degree of stretchability of the elastic film.

When bonding, as shown in FIG. 11, the inner nonwoven fabric 21, the elastic film 25, and the outer nonwoven fabric 22 are fed between an anvil roll 60 having protrusions 60a formed on the outer surface in a predetermined pattern and an ultrasonic horn 61, and ultrasonic melting energy is applied by the ultrasonic horn 61, for example by melting mainly the elastic film 25, thereby bonding the inner nonwoven fabric 21 and the outer nonwoven fabric 22.

An opposing roll 63 is disposed opposite the anvil roll 60. A driving roll 65 is provided for this opposing roll 63, forming a nip roll that pinches the elastic film 25.

In this device structure, the elastic film 25 is wound around the opposing roll 63, reaches a nip position with the drive roll 65, and then wound around the anvil roll 60.

At that time, the peripheral speed of the anvil roll 60 is made faster than the peripheral speed of the driving roll 65 (and therefore the peripheral speed of the opposing roll 63), thereby stretching the elastic film 25 and bonding is performed by the group of protrusions 60a of the anvil roll 60 and the ultrasonic horn 61.

At this time, by selecting a speed difference that makes the peripheral speed of the anvil roll 60 faster than the peripheral speed of the drive roll 65, the elongation rate (based on the length in the natural state being 100%) of the elastic film 25 during the manufacturing process can be set.

Figure 8 shows a schematic cross-section of the stretch sheet in a stretched state after bonding. When the stretch sheet is released from the stretched state, it contracts due to the contraction force of the elastic film 25, as shown in Figure 9 (schematic diagram), and can be stretched by applying an external force in the width direction (left and right direction in Figure 9). Therefore, if this stretch sheet is used around the waist of a shorts-type napkin, for example, it will contract the waist or hip area.

Since the stretch sheet can be manufactured with a specified area, it can be applied when it is desired to apply a contraction force to the entire desired area. In conventional absorbent articles such as disposable diapers, this is generally done by fixing multiple rubber threads in parallel to the sheet, but this leads to a decrease in quality due to deterioration of the rubber threads and the hot melt adhesive used to fix the sheet, and is inferior in terms of stable productivity during manufacturing. These problems can be solved by the stretch sheet of the present invention.

Moreover, as can be seen from the contracted state in Figure 9, the outer surface of the stretch sheet is formed with regular fine wrinkles or folds, providing a good feel to the wearer's skin.

On the other hand, in the above example, the inner nonwoven fabric 21 and the outer nonwoven fabric 22 are joined by melting the elastic film 25. In this case, there are modes such as (1) the inner nonwoven fabric 21 or the outer nonwoven fabric 22 being joined on the surface of the elastic film 25, (2) the surface portion of the elastic film 25 melts and penetrates between the fibers of the inner nonwoven fabric 21 and the outer nonwoven fabric 22 to join them, and (3) the elastic film 25 is almost entirely melted and penetrates between the fibers of the inner nonwoven fabric 21 and the outer nonwoven fabric 22 to join them. In the present invention, the joining modes between layers are not limited to these examples.

In these embodiments, such as (3), the inner nonwoven fabric 21 and the outer nonwoven fabric 22 can be considered to be bonded directly, i.e., without the interposition of the elastic film 25.

In the above embodiments (1) to (3), the melting point of the elastic film 25 is lower than the melting points of the inner nonwoven fabric 21 and the outer nonwoven fabric 22, but the melting point of the elastic film 25 may be higher than the melting points of the inner nonwoven fabric 21 and/or the outer nonwoven fabric 22. In this case, the surface portion of the inner nonwoven fabric 21 and/or the outer nonwoven fabric 22 facing the elastic film 25 is activated or melted and bonded to the elastic film 25.

Furthermore, in addition to the elastic film 25 being partially melted, the inner nonwoven fabric 21 and/or the outer nonwoven fabric 22 may also be melted to bond them together.

The inner nonwoven fabric 21 and/or the outer nonwoven fabric 22 may be nonwoven fabrics whose fibers have a core-sheath structure. In this case, for example, only the sheath component of the fibers may melt and contribute to the joining.

Now, within the region of the stretch sheet, it is desirable that the area ratio of the joints, which is the total area of the joints contained within a unit area, differs in a given region, so that the stretch stress differs.

The joint area ratio here is the percentage of the total area of the joints 26, 26... contained within the unit area S, as shown in Figure 12. In this case, it is desirable to set the unit area S to a size that includes 10 or more joints (it is difficult to compare expansion and contraction stresses with a small number of joints). In the example of Figure 12, 13 joints are included. Also, the outer shape that defines the unit area S may be other shapes such as a rectangle or a circle in addition to a square.

An example of the joint 26 is a circle as shown in FIG. 12. Of course, it may be an ellipse, a rectangle, or other shape. In FIG. 12, Lm is the arrangement interval length in the machine direction, Lc is the arrangement interval length in the orthogonal direction (cross direction) perpendicular to the machine direction, Pm is the pitch length in the machine direction (MD), and Pc is the pitch length in the orthogonal direction (cross direction: CD).

Figure 13 shows how the bond area ratio varies depending on the region within the stretch sheet.

Figure 13 shows that for regions α, β, and γ, the joint area ratio is set to α<β<γ, resulting in a relationship of α>β>γ for the expansion and contraction stresses.

For example, when comparing α, where the pitch length Pm and pitch length Pc are long, with γ, where the pitch length Pm and pitch length Pc are short, the elongation rate is greater when the pitch length Pm and Pc are long (when the joint area ratio is low) than when the pitch length Pm and Pc are short (when the joint area ratio is high). As a result, the relationship of the stretching stress is α>β>γ. β is the intermediate case.

In the embodiment shown in FIG. 13, the elongation stress differs from region to region, so that when the absorbent article is worn, the contraction force differs from region to region, which is useful.

The elastic film 25 in the present invention may be stretchable only in the width direction, but a two-way stretchable film that also stretches in the perpendicular direction is preferable.

The thickness, material, strain/stress characteristics, melting point, and other physical properties of the elastic film 25 can be selected as appropriate. By selecting this elastic film 25, the relationship between the ultrasonic melting energy applied to it, and the elongation rate of the elastic film 25 during the manufacture of the stretch sheet, it is possible to form through holes 27 around the joints 26, as shown in FIG. 10. When the inner nonwoven fabric 21 and the outer nonwoven fabric 22 are formed from nonwoven fabric, for example, the nonwoven fabric is breathable, so the formation of the through holes 27 provides breathability on both the front and back of the stretch sheet. Therefore, when used as a component around the waist of a shorts-type napkin, for example, it becomes a waist sheet with good breathability.

The reason why the ventilation holes 27 are formed is not entirely clear, but it is believed that the elastic film 25 melts due to ultrasonic melting energy, and the joint 26 becomes thinner due to pressure from the protrusions 60a of the anvil roll 60. At this time, as the elastic film 25 also becomes thinner, the surrounding area of the joint 26 reaches its breaking strength, and the stretching stress acting on the stretched elastic film initiates breakage, causing it to shrink to the equilibrium point and opening a hole.

Figure 14 shows a schematic example of the formation of through holes 27 in the case of circular through holes. Approximately crescent-shaped through holes 27 are formed on both sides of the joint 26 in the machine direction (stretch direction).

The joints can be elongated in the direction (cross direction: CD) perpendicular to the machine direction (stretch direction). In this case, as shown in FIG. 15, for example, a large semicircular through hole 27 can be formed, which is a suitable method for increasing breathability.

On the other hand, it is not essential that through holes 27 are formed in all joints. If it is required to reliably form through holes 27 or to open the holes widely, the method shown in Figure 16 can be used.

That is, as shown in FIG. 16(B), the stretchable sheet with the joints 26 formed is passed between a pair of rolls 64 having ridges or protrusions 64a, and the protrusions 64a of one roll 64 are inserted between the adjacent protrusions 64a of the other roll 64, applying a deformation force to the stretchable sheet to form through holes 27.

In the shorts-type napkin 1 according to the present invention, as shown in Figs. 2 and 5, a laminated stretch structure 7 made of the above-mentioned stretch sheet is formed in the waist area 6 of the front body F, the waist area 6 of the back body B, and a part of the intermediate area 4 between them in the exterior body 20. An elastic film 25 is laminated between the inner nonwoven fabric 21 and the outer nonwoven fabric 22 throughout this laminated stretch structure 7, and with the elastic film 25 stretched in the width direction, the inner nonwoven fabric 21 and the outer nonwoven fabric 22 are joined (through through holes 27 formed in the elastic film 25 in the illustrated example) at numerous joining sections 26 arranged at intervals in the stretch direction (width direction) and in the direction perpendicular thereto (front-rear direction).

The shape of each joint 26 and through hole 27 in the natural length state can be any shape, such as a perfect circle, an ellipse, a polygon such as a rectangle (including linear and rounded corners), a star, a cloud, etc. The size of each joint 26 can be determined appropriately, but if it is too large, the hardness of the joint 26 will have a large effect on the feel, and if it is too small, the joint area will be small and the materials will not be able to bond sufficiently to each other, so in general, it is preferable that the area of each joint 26 is about 0.14 to 3.5 ^mm2 . The opening area of each through hole 27 may be equal to or larger than the joint because the joint 26 is formed through the through hole 27, but it is preferable that it is about 1 to 1.5 times the area of the joint 26.

Moreover, it is usually preferable that the area and area ratio of each joint 26 be as follows: Area of joint 26: 0.14 to 3.5 mm ² (particularly 0.14 to 1.0 mm ² ), Area ratio of joint 26: 1.8 to 19.1% (particularly 1.8 to 10.6%).

The planar arrangement of the joints 26 and through holes 27 can be determined as appropriate, but a regularly repeated planar arrangement is preferable, and in addition to regularly repeated arrangements such as a diagonal lattice as shown in FIG. 17(A), a hexagonal lattice as shown in FIG. 17(B) (also called a staggered arrangement), a square lattice as shown in FIG. 17(C), a rectangular lattice as shown in FIG. 17(D), a parallelepiped lattice as shown in FIG. 17(E) (a form in which two groups of a large number of parallel diagonal rows are arranged so as to intersect with each other as shown in the figure), and the like (including those inclined at an angle of less than 90 degrees with respect to the stretching direction), it is also possible to have a regularly repeated group of joints 26 (the arrangement of the group units may be regular or irregular, and may be a pattern or letter-like form, etc.). The arrangement form of the joints 26 and through holes 27 may be the same in appropriate areas, or may be different.

The elastic film 25 is not particularly limited, and any resin film having elasticity itself can be used. For example, a blend of one or more thermoplastic elastomers such as styrene-based elastomers, olefin-based elastomers, polyester-based elastomers, polyamide-based elastomers, and polyurethane-based elastomers, processed into a film shape by extrusion molding such as a T-die method or an inflation method, can be used. In addition to non-perforated elastic films 25, those having a large number of holes or slits for ventilation can also be used. In particular, it is preferable that the elastic film 25 has a tensile strength of 8 to 25 N/35 mm in the stretching direction, a tensile strength of 5 to 20 N/35 mm in the direction perpendicular to the stretching direction, a tensile elongation of 450 to 1050% in the stretching direction, and a tensile elongation of 450 to 1400% in the direction perpendicular to the stretching direction. The tensile strength and tensile elongation (elongation at break) refer to values measured using a tensile tester (e.g., AOUTGRAPHAGS-G100N manufactured by Shimadzu Corporation) in accordance with JIS K7127:1999 "Plastics - Testing method for tensile properties" with the exception that the test piece is a rectangle of width 35 mm x length 80 mm, with an initial chuck distance of 50 mm and a tensile speed of 300 mm/min. The thickness of the elastic film 25 is not particularly limited, but is preferably about 20 to 40 μm. The basis weight of the elastic film ²⁵ is not particularly limited, but is preferably about 30 to 45 g/m2, and more preferably about 30 to 35 g/ ^m2 .

The melting points of the components of the stretch sheet can be selected as appropriate, but in a suitable example, the melting point of the elastic film 25 is 95 to 125°C, more preferably 100 to 120°C, the melting point of the inner nonwoven fabric 21 is greater than 125°C to 160°C, more preferably 130 to 160°C, and the melting point of the outer nonwoven fabric 22 is greater than 125°C to 160°C, more preferably 130 to 160°C.

The ultrasonic welding temperature can be changed by selecting the ultrasonic energy from the horn. This ultrasonic energy from the horn cannot be directly converted into temperature, but when measured with a non-contact thermometer, stable productivity is achieved at temperatures of 40°C to 30°C on the horn side and 38°C to 28°C on the anvil roll side.

In addition, judging from observation of the bonding state during this stable operation, it is preferable to apply melting energy equivalent to 125°C to 145°C to the elastic film 25 from the horn side, which is higher than the melting point temperature of the elastic film 25. It is also preferable that the melting point is lower than the melting points of the inner nonwoven fabric 21 and the outer nonwoven fabric 22. It is also preferable that the difference between the melting points of the inner nonwoven fabric 21 and the outer nonwoven fabric 22 and the melting point of the elastic film 25 is about 10 to 45°C.

For the inner nonwoven fabric 21 and outer nonwoven fabric 22, in the case of the waist sheet of the shorts-type napkin 1, the most suitable nonwoven fabric is a spunbond nonwoven fabric.

As shown in FIG. 2, the shorts-type napkin 1 has an intermediate region 4 between the front and rear waist regions 3, 3, and a leg-around portion 8 is formed that is narrowed toward the center in the width direction from the central end of the waist region 3 in the front-rear direction (the lower end of the front body F as seen in FIG. 2) to the intermediate region.

It is sufficient that the leg-around portion 8 is formed on at least one of the front body F and the back body B. Of course, it is preferable that the leg-around portion 8 is formed on the front body F and the back body B.

In the present invention, as shown in FIG. 2, it is desirable that the joint area ratio of the total area of the joints 26 included in a unit area in the exterior body 20 formed from a stretch sheet is different between the leg area 8 and the area Q adjacent thereto.

To repeat, a smaller joint area ratio results in a larger stretching stress. Therefore, by reducing the joint area ratio of the leg area 8 and increasing the stretching stress, and increasing the joint area ratio and decreasing the stretching stress in the adjacent region Q, a large stretching force acts on the leg area 8, resulting in an excellent fit.

(Linear stretchable part)
2, the shorts-type napkin 1 according to the present invention is provided with a plurality of first linear stretchable portions 30 which cross the embossed grooves 18 and are spaced apart along the embossed grooves 18. In addition, a second linear stretchable portion 31 which runs approximately along the width direction of the shorts-type napkin 1, and a third linear stretchable portion 32 which runs approximately along the front-rear direction of the shorts-type napkin 1 are provided so as to surround the peak of the bulge of the wearer's buttocks.

The first linear stretchable portion 30 is provided in a straight line extending a predetermined length across the embossed groove 18 in the groove width direction and on both sides of the embossed groove 18. The first linear stretchable portion 30 is provided in multiple locations along the embossed groove 18, preferably 3 to 10 locations, and five locations in the illustrated example.

The second linear stretchable portion 31 is provided linearly along the width direction on the front and back sides of the peak of the wearer's buttocks. In other words, it is provided at two locations on the left and right, spaced apart in the front-to-rear direction.

The third linear stretchable portion 32 is provided in a straight line along the front-to-rear direction on the outer width side of the apex of the wearer's buttocks.

The top of the wearer's buttocks refers to the tops of the buttocks that bulge outward on both the left and right sides of the gluteal sulcus when the wearer is standing, and although this varies depending on the body type, it generally ranges from 120 to 300 mm, preferably 150 to 250 mm, in height from the center (CL) in the front-to-back direction of the shorts-type napkin 1, and from 20 to 110 mm, preferably 30 to 95 mm, on both the left and right sides from the center line in the width direction. Therefore, the second linear stretchable portion 31 and the third linear stretchable portion 32 are provided to surround the outside of this range.

The first linear stretchable portion 30, the second linear stretchable portion 31, and the third linear stretchable portion 32 are provided independently of each other and are not connected to or intersecting with each other.

By arranging the first linear stretchable portion 30 so that it crosses the embossed groove 18, the contraction force of the first linear stretchable portion 30 causes the embossed groove 18 to become the folding base, making it easier for the absorbent body 10 to deform into a protruding stripe toward the skin along the buttocks groove, allowing the absorbent body 10 to fit securely in the cleavage area of the buttocks.

Furthermore, since the second linear stretchable portion 31 and the third linear stretchable portion 32 are provided so as to surround the top of the wearer's buttocks, the contraction force of these linear stretchable portions 31, 32 makes it easier for the absorbent body 10 to deform three-dimensionally along the buttocks.

In this way, the absorbent body 10 deforms along the valley and bulge of the buttocks and fits the shape of the wearer's buttocks, reliably preventing leakage of bodily fluids from the back.

In the embodiment shown in Figures 2 to 6, the first linear stretchable portion 30, the second linear stretchable portion 31, and the third linear stretchable portion 32 are made of a thread-like elastic stretchable member. The fineness of the thread-like elastic stretchable member is preferably 470 dtex or more.

The first linear stretchable portion 30 and the second linear stretchable portion 31 are provided on the exterior body 20 as shown in Figs. 6(A) and (B), and the third linear stretchable portion 32 is provided on the absorbent main body 10 as shown in Fig. 6(C). Specifically, the first linear stretchable portion 30 and the second linear stretchable portion 31 are provided on the surfaces of the exterior body 20 facing the absorbent main body 10, and the third linear stretchable portion 32 is provided on the surface of the leakproof sheet 12 facing the exterior body 20.

To explain in more detail, most of the first linear stretchable portions 30 are provided on the surface of the inner nonwoven fabric 21 facing the absorbent body 10, and one or several, one in the illustrated example, located at the front end of the embossed groove 18 are provided on the surface of the outer nonwoven fabric 22 extending forward from the inner nonwoven fabric 21 facing the absorbent body 10, but all of the first linear stretchable portions 30 may be provided on the surface of the inner nonwoven fabric 21 facing the absorbent body 10.

The second linear elastic portion 31 is provided on the surface of the inner nonwoven fabric 21 facing the absorbent body 10, and is preferably provided in an area that overlaps in the thickness direction with the area where the elastic film 25 is disposed.

The first linear stretchable portion 30 and the second linear stretchable portion 31 are provided on the exterior body 20, and the third linear stretchable portion 32 is provided on the absorbent body 10, mainly for manufacturing reasons. In other words, the first linear stretchable portion 30 and the second linear stretchable portion 31 provided on the exterior body 20 are arranged along the width direction of the shorts-type napkin 1, so that in the manufacture of the exterior body 20 in which the width direction is the line flow direction, it is easy to arrange the thread-like elastic stretchable member along the line flow direction. Similarly, the third linear stretchable portion 32 provided on the absorbent body 10 is arranged along the front-rear direction of the absorbent body 10, so that in the manufacture of the absorbent body 10 in which the front-rear direction is the line flow direction, it is easy to arrange the thread-like elastic stretchable member along the line flow direction.

The third linear stretchable portion 32 may be provided on both the widthwise outer side and the widthwise inner side of the wearer's left and right buttocks bulging portions, respectively, but as shown in the figure, it is preferable to provide it only on the widthwise outer side and not on the widthwise inner side. Since the widthwise inner side of each of the left and right buttocks bulging portions is close to the buttocks groove, if the contraction force in the front-to-back direction is increased, when the widthwise central portion of the absorbent body 10 is deformed into a protrusion along the valley between the buttocks, this protrusion may cause unevenness in the front-to-back direction. By providing the third linear stretchable portion 32 only on the widthwise outer side, the top of the buttocks bulging is surrounded by the second linear stretchable portion 31 and the third linear stretchable portion 32 in an approximately U-shape.

The first linear stretchable portion 30, the second linear stretchable portion 31, and the third linear stretchable portion 32 are arranged only in the area where they overlap the absorbent body 13 of the absorbent main body 10 in the thickness direction, and do not extend outside the absorbent body 13. This makes it easier for the absorbent body 13 to deform along the valleys and bulges of the buttocks.

In addition, it is preferable that in the area where the first linear stretchable portion 30, the second linear stretchable portion 31, and the third linear stretchable portion 32 are arranged, other thread-like elastic stretchable members are not arranged adjacently or overlappingly in addition to the thread-like elastic stretchable members that constitute them. If other thread-like elastic stretchable members are arranged adjacently or overlappingly, the contraction force of the thread-like elastic stretchable members reduces the effect of the contraction force of the first linear stretchable portion 30, the second linear stretchable portion 31, and the third linear stretchable portion 32, or the contraction direction changes, making it difficult to fit the valley or bulge of the buttocks. However, as in the above-mentioned elastic film 25, if an elastic member that uniformly contracts almost the entire area where these linear stretchable portions 30, 31, and 32 are arranged in the exterior body 20 is arranged in an overlapping manner, there is no problem because the contraction direction of the first linear stretchable portion 30, the second linear stretchable portion 31, and the third linear stretchable portion 32 does not change.

The stretch rate of the first linear stretchable portion 30 is preferably higher than that of other areas of the exterior body 20 where the elastic film 25 is disposed, and is preferably 275% or more (based on the length in the natural state being 100%). In addition, the stretch width, which is the range of length change when a tensile force is applied and released, is preferably 10 to 30 mm.

The stretch rate of the second linear stretchable portion 31 is preferably higher than that of other areas of the exterior body 20 where the elastic film 25 is disposed, and is preferably 275% or more (based on the length in the natural state being 100%). In addition, the stretch range, which is the range of length that changes when a tensile force is applied and released, is preferably 70 to 90 mm.

The stretch rate of the third linear stretchable section 32 is within a range that does not interfere with deformation to the cleavage of the buttocks, and is preferably smaller than that of the first linear stretchable section 30 and the second linear stretchable section 31, and is preferably 200% or more (based on the length in the natural state being 100%). In addition, the stretch width, which is the range of length that changes when a tensile force is applied and released, is preferably 70 to 90 mm.

In the above embodiment, the first linear stretch section 30 and the second linear stretch section 31 are made of a thread-like elastic stretch member, but as explained in the above section (Stretch sheet using elastic film 25), the joint 26 provided in a specific area of the stretch sheet may be made of an area having a different area ratio from the adjacent areas. That is, as described above, if the joint area ratio is small, the stretch stress is large, so in the first linear stretch section 30 and the second linear stretch section 31, the joint area ratio is made smaller than that of the adjacent areas, and the stretch stress is increased.

(Manufacturing method)
Next, a manufacturing method of the shorts-type napkin 1 according to the present invention will be described. First, the absorbent body 10 is manufactured by introducing a laminated structure having the absorbent body 13 interposed between the top sheet 11 and the leakproof sheet 12 between an embossing roll having protrusions at positions corresponding to the embossed grooves 18 and an anvil roll having a flat surface, thereby forming the embossed grooves 18 at predetermined positions in the leakproof sheet 12, and then fixing the third linear elastic portions 32 in an extended state to the outer surface of the leakproof sheet 12 with a hot melt adhesive.

Next, the outer body 20 is manufactured by interposing an elastic film 25 between the inner nonwoven fabric 21 and the outer nonwoven fabric 22, and fixing the thread-like elastic stretch member 24 in a stretched state around the waist with hot melt adhesive, and then fixing the first linear stretch portion 30 and the second linear stretch portion 31, which are made of the thread-like elastic stretch member, in a stretched state to the surface facing the absorbent body 10 with hot melt adhesive.

The absorbent body 10 is then turned over and joined to the surface of the outer body 20 facing the absorbent body 10 to complete the shorts-type napkin 1.

[Other examples]
In the above embodiment, as shown in FIG. 2, a region having a smaller joint area ratio in the leg surrounding portion 8 of the outer body 20 than in the adjacent region Q is provided, thereby allowing a large stretching force to act on the leg surrounding portion 8 and improving the fit around the legs. However, in addition to this configuration, or without providing such a region having a smaller joint area ratio, one or more thread-like or band-like elastic stretch members may be arranged in a stretched state along the leg cut lines 23 between the inner nonwoven fabric 21 and the outer nonwoven fabric 22 of the outer body 20, thereby allowing a stretching force to act on the leg surrounding portion 8 and improving the fit around the legs.

1...shorts-type napkin, 2...side seal portion, 3...torso region, 4...middle region, 5...waist region, 6...hip region, 7...laminated stretch structure, 8...leg region, 10...absorbent body, 11...surface sheet, 12...leakproof sheet, 13...absorbent body, 14...enveloping sheet, 15...outline of back edge, 16...neck portion, 17...bulge, 18...embossed groove, 20...outer body, 21...nonwoven fabric for inner surface, 2 2...Outer nonwoven fabric, 23...Leg cut line, 24...Thread-like elastic stretch member, 25...Elastic film, 26...Joint, 27...Through hole, 30...First linear stretch section, 31...Second linear stretch section, 32...Third linear stretch section, 60...Anvil roll, 61...Ultrasonic horn, 63...Opposite roll, 64...Roll, 65...Driving roll, B...Back body, F...Front body, L...Leg opening, W...Waist opening

Claims (7)

A shorts-type absorbent article comprising an absorbent body having an absorbent body interposed between a liquid-permeable top sheet and a liquid-impermeable leak-proof sheet, and an exterior body integrally provided on the outer surface side of the absorbent body, the front and rear parts of the exterior body being joined at both sides to form a waist opening and a pair of left and right leg openings in a manufactured state,
An embossed groove is provided on the leakproof sheet side of the absorbent body along a portion corresponding to the buttocks of a wearer, the groove being recessed toward the top sheet side;
A plurality of first linear elastic portions are provided across the embossed groove and spaced apart along the embossed groove,
A shorts-type absorbent article characterized in that a second linear stretch portion is provided along approximately the width direction of the shorts-type absorbent article, and a third linear stretch portion is provided along approximately the front-to-rear direction of the shorts-type absorbent article, so as to surround the top of the bulge of the wearer's buttocks. The shorts-type absorbent article according to claim 1, wherein the first linear stretchable portion and the second linear stretchable portion are provided on the exterior body, and the third linear stretchable portion is provided on the absorbent body. The shorts-type absorbent article according to claim 1 or 2, wherein the third linear stretchable portion is provided only on the outer widthwise portion of the wearer's buttocks and not on the inner widthwise portion. The shorts-type absorbent article according to any one of claims 1 to 3, wherein the first linear stretchable portion, the second linear stretchable portion, and the third linear stretchable portion are provided in an area that overlaps with the absorbent body in the thickness direction. The shorts-type absorbent article according to any one of claims 1 to 4, wherein the first linear stretchable portion, the second linear stretchable portion, and the third linear stretchable portion are each made of a thread-like elastic stretchable material. The exterior body is a stretchable sheet in which a stretchable elastic film is laminated between a first sheet layer having no stretchability and a second sheet layer, and the first sheet layer and the second sheet layer are joined at a number of spaced joints directly or via an elastic film, the stretchable sheet being contractible by the contraction force of the elastic film and extensible when an external force is applied,
The shorts-type absorbent article according to any one of claims 1 to 4, wherein the first linear stretchable portion and the second linear stretchable portion are constituted by areas in which the area ratio of the joints provided in a predetermined portion of the stretch sheet is different from that of adjacent areas, and the third linear stretchable portion is constituted by a thread-like elastic stretchable material. A shorts-type absorbent article according to any one of claims 1 to 6, in which the outer contour of the back edge of the absorbent body has a constricted portion formed in the center that is recessed toward the center in the front-to-rear direction, and bulging portions formed of curves that bulge outward in the front-to-rear direction on both sides of the constricted portion.

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