JP2017064235A5 - - Google Patents

Description

Absorbent article having stretchable part

  The present invention relates to an absorbent article having a stretchable part, typically a disposable diaper, a disposable pad or a sanitary napkin, comprising a stretchable sheet in which a first sheet layer and a second sheet layer sandwich an elastic film.

  In an absorbent article, for example, a disposable diaper, in order to improve fit to the body surface, it is common to impart stretchability to appropriate places such as around the legs and around the trunk. As a method for imparting stretchability, conventionally, a method of fixing an elongated elastic stretchable member such as rubber thread in a stretched state in the longitudinal direction has been widely adopted, but it is desired to impart stretchability to a certain width. In such a case, a mode is adopted in which the rubber thread is fixed in a state of being arranged side by side with an interval in the width direction.

  On the other hand, it is also known to form so-called three-dimensional gathers in addition to so-called flat gathers for preventing side leakage from around the legs, and it is common to use rubber thread as the expansion and contraction means.

  However, the hot melt adhesive for fixing the rubber thread to the sheet is likely to be temporally or thermally deteriorated, and there is a possibility that the adhesive force is lowered under wet conditions.

It has also been proposed to use an elastic film instead of juxtaposing the rubber thread (Patent Document 1). However, the fixing means of the elastic film is not clear.
On the other hand, in place of a plurality of thread rubbers arranged in parallel, it has been proposed to use a nonwoven fabric / elastomer film / nonwoven fabric as a material that presses against a surface strip to give stretchability and takes the touch into consideration. (For example, refer to Patent Document 2).

  However, Patent Document 2 supplies an elastic film that expands and contracts in the continuous MD direction between the first outer layer and the second outer layer, which has a higher melting point or no melting point, and at a predetermined position. And a second outer layer are directly bonded by welding, and then a pulling force is applied to the CD direction to form a through hole penetrating the first outer layer, the elastic film, and the entire second outer layer at the bonding site. is there.

Moreover, since the stretchable sheet according to Patent Document 2 is intended for continuous production, the pattern of the raised portions in the thermal bonding roller forming the joint portion is uniform in the width direction and the circumferential direction, and thus the produced stretchable sheet. Even if the sheet has different positions in the width direction, the stretching stress is uniform.
Therefore, it cannot be said that this stretchable sheet has a wide range of uses.

  However, this type of expansion / contraction means around the legs is a factor that increases the number of members because a separate elastic member is provided on the seat, and also requires problems such as positioning control during manufacturing and hinders stable production. There is.

Japanese Patent Laid-Open No. 2000-300606 Japanese Patent No. 4562391

  Then, the main subject of this invention is providing the absorbent article which has an expansion-contraction part from which an expansion-contraction stress differs with positions in an expansion-contraction sheet.

  The present invention that has solved the above problems is as follows.

(Basic form)
The absorbent article of the present invention includes a three-dimensional gather formed on both sides by an elastic sheet having an elastic part that can be extended and contracted in the front-rear direction.
In the stretchable sheet, an elastic film that is stretchable in the front-rear direction is laminated between a first sheet layer made of, for example, a non-woven fabric that does not have stretchability, and a second sheet layer, made of, for example, a non-woven fabric that does not have stretchability. In addition, the first sheet layer and the second sheet layer are joined at a large number of joints that are spaced apart, either directly or via an elastic film.
The expansion / contraction part contracts due to the contraction force of the elastic film, and can expand when an external force is applied in the front-rear direction.
In the stretchable sheet, the joint area ratio occupied by the total area of the joints included in the unit area is different in the width direction, so that the stretch stress in the front-rear direction is different between the width directions. Thereby, the expansion-contraction part which can be expanded-contracted in the said front-back direction is formed.

  The stretchable part is formed in the middle in the front-rear direction, and it can be a region that does not exhibit stretchability or has low stretchability up to the end in the front-rear direction.

  The stretchable part may be a straight line or a curved line. For example, a disposable diaper may draw a constricted curve toward the center in the width direction in the crotch area.

  Although there is no limitation on the arrangement of the joints, for example, it can be staggered.

In the said expansion-contraction part, it can be set as the structure from which the junction part area ratio differs in the front-back direction.
For example, in the disposable diaper, in the stretchable part, the joint area ratio is different in the front-rear direction, and the joint area ratio increases toward the edge at least in the front-rear direction edge side of the stretchable part. It can be adopted. The central part of the stretchable part strengthens the stretch force and weakens the stretch force from there toward the end, thereby preventing the diaper end from becoming easily rounded, and also has the advantage of improving wearability to the wearer. .

  In the said expansion-contraction part, the structure from which the junction area ratio differs in the width direction may be sufficient.

  One aspect thereof is such that the width direction side edge of the stretchable portion has a high joint area ratio, and the center in the width direction has a low joint area ratio. In this case, the outer shape of the diaper is easily rounded in the cross section and the fitting property is improved.

  In the second aspect, the width direction side edge of the expansion / contraction part has a low bonding area ratio of the folds and the width direction center has a high bonding area ratio of the folds. In this case, there is an advantage that the tightening force at the crotch portion is high for a person with thick legs.

  The elastic film may be stretchable in the width direction.

  In addition to a circular shape, the joint may have a length in the width direction that is longer than the length in the front-rear direction.

  The absorbent article of the present invention includes disposable diapers, sanitary napkins and the like.

In the stretchable sheet of the present invention, no hole penetrating the first sheet layer and the second sheet layer is formed. This point is different from the stretchable sheet shown in FIG. 5 or 7 of Japanese Patent No. 4562391.
However, the first sheet layer and the second sheet layer may be joined through through holes formed in the elastic film at a large number of joints spaced apart. That is, a through hole may be formed in the elastic film.

In the joint part of the expansion-contraction part of this invention, there exists the following joining form example, for example.
(1) The first sheet layer and the second sheet layer are partially melted and joined to the elastic film, that is, the first sheet layer and the second sheet layer are joined via the elastic film.
(2) A mode in which the elastic film melts and moves into the first sheet layer and the second sheet layer, and the first sheet layer and the second sheet layer are directly joined without interposing the elastic film.
(3) It is an intermediate form between the form of (1) and the form of (2), and both surface portions of the elastic film melt and move into the first sheet layer and the second sheet layer, but elastic A form in which the first sheet layer and the second sheet layer are bonded via the remaining elastic film by partially remaining the film.

Among these forms, in particular, in the form (2) and the form (3), the difference in elastic film strength occurs between the joined part and the non-joined part. Therefore, after the stretched state of the stretch sheet holding the extension is once released and contracted to make a product; or after the stretch sheet holding the stretch is combined with another member, the stretched state is once released and contracted When the product is stretched mechanically or manually in the expansion / contraction direction, breakage occurs at the boundary between the joined portion and the non-joined portion.
As a result, a through hole is formed.

The stretchable sheet having stretchable parts that can be stretched in the front-rear direction and formed on at least both side parts can be manufactured, for example, by the following method.
A supply step of interposing an elastic film stretchable in at least one direction (front-rear direction of the product) in a stretched state between the first sheet layer not stretchable and the second sheet layer not stretchable;
In this supplying step, the elastic film is interposed between the first sheet layer and the second sheet layer, and is spaced from the outside of the first sheet layer and the second sheet layer by a heat melting device. The elastic film is provided with heat melting energy by a large number of heat melting portions opened to melt the elastic film, and the first sheet layer and the second sheet layer can be directly connected to the elastic film through the elastic film. Joining process of joining with,
Including
In the joining step, the stretchable sheet is formed in which no hole is formed in the entire joint region and the first sheet layer and the second sheet layer remain. And an absorptive article is manufactured using this elastic sheet as a material.

  The elastic film is passed through a nip roll step in which a pair of opposing nips are arranged in the front-rear direction, and the elastic speed is increased by increasing the peripheral speed of the front nip roll step relative to the peripheral speed of the rear nip roll step between the front and rear nip roll steps. A method is provided for feeding a film to the feeding step in a stretched state. Another method may be to pass only a pair of nip rolls while winding the elastic film around the drive roll in, for example, an S shape.

The heat melting apparatus has an anvil roll and an ultrasonic horn, and the anvil roll has a plurality of protrusions formed on the outer surface thereof spaced apart in the roll length direction and the outer peripheral direction. The aspect which comprises the said thermal fusion part with an ultrasonic horn is provided.
Instead of the ultrasonic heat melting apparatus, other heat melting means may be used.

The melting point of the elastic film is lower than the melting point of the first sheet layer made of nonwoven fabric and the melting point of the second sheet layer made of nonwoven fabric, higher than this melting point, and lower than the melting points of the first sheet layer and the second sheet layer. When the melting energy corresponding to the temperature is applied, the elastic film is melted by heat, while the first sheet layer and the second sheet layer are not melted at all or are partially melted. As a result, holes are formed in the entire joint region. The first sheet layer and the second sheet layer remain.
However, the line speed at the time of manufacturing the elastic sheet is high. Therefore, even if a melting energy corresponding to a temperature higher than the melting point of the first sheet layer and the second sheet layer is given, the first sheet layer and the second sheet layer are not melted at all or are partially melted. A form in which no hole is formed can be obtained.

From such a viewpoint, the melting point of the elastic film is preferably about 80 to 145 ° C, the melting point of the first sheet layer and the second sheet layer is about 85 to 190 ° C, particularly preferably about 130 to 190 ° C, The difference between the melting points of the first sheet layer and the second sheet layer and the melting point of the elastic film 30 exhibiting a lower melting point is preferably about 50 to 80 ° C.
As a suitable specific example, the melting point of the elastic film is 95 to 125 ° C., the melting point of the first sheet layer is more than 125 ° C. to 160 ° C., more preferably 130 to 160 ° C., and the melting point of the second sheet layer is 125. More than ℃ ~ 160 ℃, more preferably 130-160 ℃.

As a preferred example of the joint portion, the area of the joint portion in the stretchable region is 0.14 to 3.5 mm ² , and the area of the opening of the through hole in the natural length state is 1 to 1 of the area of the joint portion. And the area ratio of the joint in the stretchable region is 1.8 to 22.5%.
Here, the “area ratio” means the ratio of the target portion to the unit area, and the total area of the target portion (for example, joints and openings of through holes) in the target region (for example, the stretchable region) is the area of the target region. In particular, the “joint area ratio” means the area ratio in a state of being stretched to the elastic limit in the stretching direction. In addition, the area of the opening of the through hole means a value in a state in which the stretchable structure is in a natural length, and the area of the opening of the through hole is not uniform in the thickness direction, such as different between the front and back of the elastic film. Means the minimum value.
The joint area ratio in the present specification can be selected by selecting the size, shape, separation interval, arrangement pattern in the roll length direction and roll circumferential direction, etc. of the protrusions of the anvil roll described later.

“Elongation stress” is measured by a tensile test according to JIS K7127: 1999 “Plastics—Test method for tensile properties—” with an initial chuck interval (distance between marked lines) of 50 mm and a tensile speed of 300 mm / min. It means “stress when stretched to 50% of elastic limit (N / 35 mm)”. When a test piece having a width of 35 mm cannot be cut out, the test piece is created with a width that can be cut out, and the measured value is set to a value converted into a width of 35 mm.
If the target area is small and sufficient specimens cannot be collected, a comparatively small specimen can be compared at least if it is a comparison of stretching stress.
Moreover, since a plurality of extensional stresses are different in the region, how to collect the test piece becomes a problem. Therefore, apart from obtaining the absolute value of the stretching stress, for comparison of the stretching stress, a test piece is collected for each part of the stretchable sheet, and each test piece is 150% from the 100% length in the natural state. It is also possible to compare the magnitude by the stress when stretched to% length.

  As described above, according to the present invention, an absorbent article having a three-dimensional gather formed on both sides is obtained by an elastic sheet having an elastic part that can expand and contract in the front-rear direction. And since the three-dimensional gather is joined using, for example, the melting of the constituent layers, the joined portion does not come off, and as a result, there is no deterioration in the region where the stretching force is exerted and it is stable.

It is a top view of the example of arrangement pattern of a joined part. It is a schematic plan view of the example from which a junction area ratio differs. It is a schematic plan view of the other example from which a junction area ratio differs. It is a schematic plan view of another example from which a junction area ratio differs. It is sectional drawing for description before joining of an elastic sheet. It is sectional drawing for description of the joining state of an elastic sheet. It is sectional drawing for description of the contracted state of an elastic sheet. It is sectional drawing for description of the joining state of the expansion-contraction sheet | seat in which a through-hole is formed. It is a schematic diagram of the example of joining means. It is a top view for description of the example of formation of a through hole. It is a top view for description of the formation example of the through-hole which differs in an aspect. It is a top view for description of the example of formation of a through hole. It is an expanded state outline top view of the tape type disposable diaper of the 1st example. It is an expansion state outline top view of a tape type disposable diaper of the 2nd example. It is an expansion state outline top view of a tape type disposable diaper of the 3rd example. It is an expansion state outline top view of a tape type disposable diaper of the 4th example. It is an expansion state outline top view of a tape type disposable diaper of the 5th example. It is an expansion state outline top view of a tape type disposable diaper of the 6th example. It is an expansion state outline top view of a tape type disposable diaper of the 6th example. It is a top view of the example of a tape type disposable diaper. FIG. It is a 22-22 line arrow directional view. It is a 23-23 line arrow directional view. It is a top view which shows the various arrangement | sequence examples of a junction part. It is an expanded state top view of an example of a pants type disposable diaper. FIG. It is a 22-22 line arrow directional view. It is a 28-28 line arrow directional view. It is a 29-29 line arrow directional view.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The absorbent article of the present invention means a product that absorbs and retains body fluids such as disposable diapers, sanitary napkins, and absorbent pads.
The absorbent article includes a three-dimensional gather formed on both sides by an elastic sheet having an elastic part that can expand and contract in the front-rear direction.

As shown in FIGS. 5 to 8, the stretchable sheet is between a first sheet layer 21 made of, for example, a non-woven fabric that does not have stretchability, and a second sheet layer 22 made of, for example, a non-woven fabric that does not have stretchability, The elastic film 30 that can be expanded and contracted in the front-rear direction is laminated, and the first sheet layer 21 and the second sheet layer 22 are directly or via the elastic film 30 with a large number of bonding portions. 40 is joined.
Here, “the first sheet layer 21 and the second sheet layer 22 are not stretchable” does not mean that the first sheet layer 21 and the second sheet layer 22 are not stretched at all. It means not.

At the time of joining, for example, as shown in FIG. 9, the first sheet layer 21, the elastic film 30, and the second sheet are disposed between the anvil roll 60 having the protrusions 60 a formed in a predetermined pattern on the outer surface and the ultrasonic horn 61. The sheet layer 22 is supplied, and ultrasonic melting energy is applied by the ultrasonic horn 61. For example, the elastic film 30 is mainly melted to join the first sheet layer 21 and the second sheet layer 22.
In addition, about the example of joining form, it explains in full detail later.

  The elongation rate in the manufacturing process of the elastic film 30 (based on the length of the natural state being 100%) is, for example, that the peripheral speed of the driving anvil roll 60 is faster than the peripheral speed of the rear driving roll 62. It can be set by selecting the speed difference between the rolls. 63 is a guide roller.

  FIG. 6 schematically shows a cross section of the stretchable sheet after joining in the stretched state. When the stretched state of the stretchable sheet is released, as shown in FIG. 7 (schematic diagram), the stretchable sheet contracts due to the contraction force of the elastic film 30 and can be stretched by applying an external force in the front-rear direction (left-right direction in FIG. 7). Therefore, when the expansion / contraction direction of this stretchable sheet is matched with, for example, the front / rear direction of the disposable diaper, the disposable diaper can be expanded / contracted in the front / rear direction.

And since an elastic sheet can be manufactured with a predetermined area, when it is desired to apply a contracting force to the entire desired area, the elastic sheet cut into the desired area may be applied. In conventional disposable diapers, it is generally performed by fixing a plurality of thread rubbers in parallel to the sheet, but this reduces quality due to deterioration of thread rubber and hot melt adhesive for fixing to the sheet, In addition, it is inferior in terms of stable productivity during production. These problems can be solved by the above stretchable sheet.
Moreover, as can be seen from the contracted state of FIG. 7, the outer surface of the stretchable sheet is formed with regular fine wrinkles or folds, so that the wearer's skin feel is good.

On the other hand, in the above example, the first sheet layer 21 and the second sheet layer 22 are joined by melting the elastic film 30. In this case, (1) the mode in which the first sheet layer 21 or the second sheet layer 22 is joined on the surface of the elastic film 30, (2) the surface portion of the elastic film 30 is melted, and the first sheet layer 21 and the second sheet A mode of invading and bonding between the respective fibers of the layer 22 (3) Almost all of the elastic film 30 is melted and invaded and bonded between the respective fibers of the first sheet layer 21 and the second sheet layer 22. There are aspects. In the present invention, the bonding mode between the layers is not limited to these examples.
Among these aspects, in the aspect such as (3), it can be evaluated that the first sheet layer 21 and the second sheet layer 22 are joined directly, that is, without interposing an elastic film.
The above aspects (1) to (3) are cases where the melting point of the elastic film 30 is lower than the melting points of the first sheet layer 21 and the second sheet layer 22, but the melting point of the elastic film 30 is the first sheet layer. 21 and / or higher than the melting point of the second sheet layer 22. In this case, the elastic film 30 side surface portion of the first sheet layer 21 and / or the second sheet layer 22 is activated or melted and joined to the elastic film 30.
Furthermore, the elastic film 30 may be partly melted, and the first sheet layer 21 and / or the second sheet layer 22 may be joined by melting.
The 1st sheet layer 21 and / or the 2nd sheet layer 22 are nonwoven fabrics, and the fiber may have a core-sheath structure. In this case, for example, only the sheath component of the fiber can be melted and contribute to the joining.

The main feature of the present invention is that at least a stretchable portion is provided in the central region in the width direction, and the stretchable portions are formed on both sides of the absorbent article.
And, in the stretchable sheet, the stretchable stress in the front-rear direction is different between the width directions because the joint area ratio occupied by the total area of the joints included in the unit area is different in the width direction. It is.
As a means for this, the ratio of the total area of the joints included in the unit area of the region to the unit area, that is, the joint area ratio is selected.
The present invention provides a high effect or advantage when applied to a disposable diaper, particularly a tape-type disposable diaper. Let's assume that this is applied to a tape-type disposable diaper. For example, when it is desired to give stretchability only to the legs, if the other region, for example, the side edge region or the front and back region of the diaper also shows stretchability, the shape and flatness of that region are not determined, and the diaper is applied to the wearer. It is hard to put on. Further, if the widthwise central region is stretchable, the folds or wrinkles of the central region that repeats unevenness in the front-rear direction may reach the side edge region, and so-called side leakage may occur. Therefore, the use of the stretchable sheet is extremely useful when the stretchability is provided only around the legs.

As shown in FIG. 1, the joint area ratio is a percentage of the total area of the joints 40, 40... Included in the unit area S. The unit area S in this case is desirably set to a size that includes 10 or more joints (it is difficult to compare the stretching stress with a small number). In the example of FIG. 1, 13 joint portions are included. Moreover, the external shape which defines unit area S may be other shapes, such as a rectangle and a circle, besides a square.
An example of the joint 40 is a circle shown in FIG. Of course, the shape may be an ellipse or a rectangle. In FIG. 1, Lm is an arrangement interval length in the machine direction, Lc is an arrangement interval length in an orthogonal direction (cross direction) orthogonal to the machine direction, Pm is a machine direction (MD pitch length, Pc is an orthogonal direction (cross direction: CD) ) Pitch length.

The aspect from which a junction area ratio changes with the area | regions in an elastic sheet was shown in FIGS.
In FIG. 2, for the regions A and B, the expansion stress is in the relationship of A> B by setting the joint area ratio to A <B.
For example, when the pitch length Pm and the pitch length Pc are long and A is compared with the case B when the pitch length Pm and the pitch length Pc are short, the case A (when the joint area ratio is low) is long. In the case where the pitch length Pm · Pc is short, the elongation ratio is larger than that in B (when the joint area ratio is high). As a result, the stretching stress has a relationship of A> B.
The form of FIG. 2 differs in the extensional stress in the lateral direction of FIG. 2 for each region, so that the region A having a large stretching stress corresponds to the central region in the width direction of the absorbent article. And B area | region where expansion / contraction stress is small (so-called expansion / contraction is small) is made to respond | correspond to the both outer sides of center A area | region.

  In the case of FIG. 3, in the intermediate region, the B region having a small expansion and contraction stress is arranged before and after the intermediate region A in the front-rear direction. In this example, the front and rear B regions and the B region can correspond to, for example, front and rear end portions of the disposable diaper. Since the stretching stress is small at the front and rear end portions, the shape stability is good. It becomes easy to attach to.

In the present invention, the difference in the joint area ratio can be achieved by changing the joint area in addition to the density of the arrangement pattern.
In order to understand this, FIG. 4 shows an example in which a large number of small junctions are arranged in the region C so as to have the same junction area as the region D. By setting the joint area to A <C = D, the stretching stress is in the relationship of A> C = D.

  By the way, the elastic film in the present invention may be stretchable only in the front-rear direction, but a two-way stretchable film that stretches in the direction perpendicular to the direction can also be used.

  Physical properties such as the thickness, material, strain / stress characteristics, and melting point of the elastic film can be selected as appropriate. By selecting the relationship between this elastic film, the ultrasonic melting energy applied thereto, and the elongation rate of the elastic film at the time of manufacturing the stretchable sheet, as shown in FIG. 31 can be formed. When the first sheet layer 21 and the second sheet layer 22 are formed of, for example, a nonwoven fabric, the nonwoven fabric exhibits air permeability. Therefore, for example, when used as an outer sheet or an outer sheet of a disposable diaper, the air permeability is good.

  The reason why the ventilation through hole 31 is formed is not necessarily clear, but the elastic film 30 is melted by the ultrasonic melting energy, and the coupling portion 40 is thinned by the pressing by the projection 60 a of the anvil roll 60. At this time, the elastic film 30 is also thinned, the peripheral portion of the joint portion 40 reaches the breaking strength, the breakage is started by the stretching stress acting on the stretched elastic film 3, shrinks to the balanced portion, and opens. it is conceivable that.

  FIG. 10 schematically shows an example of forming the through hole 31 in the case of a circular through hole. A substantially crescent-shaped through hole 31 is formed on both sides of the connecting portion 40 in the machine direction (extension direction).

  The coupling portion can have a long shape in a direction (cross direction: CD direction) orthogonal to the machine direction (extension direction). In this case, for example, as shown in FIG. 11, a semicircular through hole 31 having a large opening can be formed.

On the other hand, it is not essential for the through holes 31 to be formed in all the coupling portions. If it is required to reliably form the through-hole 31 or to open a large hole, the technique shown in FIG. 12 can be adopted.
That is, as shown in FIG. 12B, the stretchable sheet in which the coupling portion 40 is formed is passed between a pair of rolls 64 having ridges or protrusions 64a, and between adjacent protrusions 64a and 64a of one roll 64. The through-hole 31 can be formed by biting the protrusion 64a of the other roll 64 and applying a deformation force to the stretchable sheet.

(Application example to disposable diapers)
The stretchable sheet according to the present invention can be applied to disposable diapers. As shown in FIG. 13, the tape-type disposable diaper TD1 having the tape T on both sides on the back side extends in the front-rear direction around the crotch area on both sides of the product, that is, expands and contracts in the front-rear direction. The three-dimensional gather G which has the expansion-contraction part 83 can be formed.
In this example, when the stretchable sheet is manufactured, the stretchable portion 83 is formed by partially making the engagement portion area ratio smaller than the engagement portion area ratio of other portions.

In the example of FIG. 13, the engagement portion area ratio of the expansion / contraction portion 83 along the front-rear direction and the engagement portion area ratio are different between the width-direction both side regions, so that the expansion / contraction in the front-rear direction is performed between the width directions. It is set as the structure from which the stress differs.
In addition, the engagement part area ratio of the expansion / contraction part 83 and the front / rear area in the front / rear direction are different, so that the expansion / contraction stress in the front / rear direction is different between the front / rear directions. It is what.
Thus, since the expansion-contraction part 83 expands / contracts, the whole expansion-contraction part 83 contact | abuts to a wearer's leg periphery planarly, and fit property and adhesiveness improve.

In the area other than the expansion / contraction part 83, it is possible to increase the engagement part area ratio so as not to substantially expand and contract.
On the other hand, in a region other than the stretchable portion 83, a certain degree of stretchability can be exhibited as long as the engagement portion area ratio is not excessively increased.

  Since the tape-type disposable diaper has a general structure other than the tape T and can be used as long as it is known to those skilled in the art, its illustration and description are kept to a minimum. And materials and structures, such as an absorber and a top sheet, can be chosen suitably.

  The tape-type disposable diaper may be of a so-called “fundoshi” type in which the front body is wrapped with a long tape Ta as shown in FIG.

  The tape-type disposable diaper may be a so-called “straight type” having both side edges straight as shown in FIG.

  The pad type disposable diaper PD which does not include a tape as shown in FIG. 16 and is arranged inside the underwear or inside the tape type disposable diaper may be used.

Further, as shown in FIG. 17, the stretching stress can be made different between the front and rear in the stretchable part 83 </ b> B. That is, it is preferable to increase the expansion / contraction stress in the middle part in the front-rear direction of the expansion / contraction part 83B and decrease the expansion / contraction stress in the front / rear direction.
The center part of the stretchable part where gaps are easy to be formed strengthens the stretch force so that it closely adheres to the legs. There is also an advantage that it is easy to attach to.
Such an embodiment is an embodiment that cannot be used when thread rubber is used.

As shown in FIG. 18, in the stretchable part 83C, the stretch stress can be made different in the width direction. This brings about an advantage that fitting according to the wearer's body shape is possible.
That is, when the outer stretching stress in the width direction of the stretchable portion 83C is increased and the inner stretching stress in the width direction is decreased, the outer shape of the diaper becomes an arc shape along the body shape, so that the fit to the wearer is improved. .
On the contrary, as shown in FIG. 19, when the expansion / contraction stress in the width direction of the expansion / contraction portion 83C is reduced and the expansion / contraction stress in the width direction is increased, the wearer with a thick thigh is Tightening force increases and fit is enhanced.
These forms are contrasted in that they can be easily achieved while the selection and arrangement of the thickness of the thread rubber is troublesome in the conventional example in which the thread rubber is fitted in a plane by parallel arrangement.

(Specific examples of absorbent articles)
As a specific example of the absorbent article of the present invention, particularly in a disposable diaper, a cover-type disposable diaper that does not have an absorbent element on the use surface side, or an elastic sheet as an exterior sheet, and the absorbent element is provided on the use surface side You can also
As this absorbent body, an absorbent body mainly composed of cotton-like pulp, or an absorbent body containing a polymer-absorbing polymer in a cotton-like pulp layer can be used.

In a cover-type disposable diaper, if an absorbent body is not provided, or even if an absorbent body is provided, if it is thin (for example, less than 2 mm) and the absorbent capacity is small, it is desirable that through holes are not formed or few in the elastic film. For this purpose, the melting point of the elastic film 30 is set higher than the melting points of the first sheet layer 21 and / or the second sheet layer 22, but the joining portion is formed, but the through hole is not formed.
In this embodiment, the basis weight of the absorber is 200 g / m ² or less, more desirably 150 g / m ² or less.

Absorbers to be used, including the absorbers that will be described in more detail later, are known ones such as pulp fiber stacks, aggregates of filaments such as cellulose acetate, or non-woven fabrics as basic elements. What mixed an adsorbent polymer, adhering, etc. can be used. This absorbent body can be packaged with a packaging sheet having liquid permeability and liquid retention, such as crepe paper, if necessary, for holding the shape and polymer.
The shape of the absorbent body can be formed in an almost hourglass shape having a narrowed portion narrower than the front and rear sides at the crotch portion, and can also have an appropriate shape such as a rectangular shape.

<Specific examples of tape-type disposable diapers>
20-23 has shown an example of the tape type disposable diaper, and this disposable diaper interposes the absorber 3 between the inner surface of the back surface sheet 9 which forms the back surface, and the liquid-permeable top sheet 2. It is what has been.
On both sides of the disposable diaper, that have standing gathers G (seat) is provided by the stretch sheet 1 having extendable telescopic part in the front-rear direction.

(Liquid impervious back sheet)
The back sheet 9 constituting the liquid-impermeable back sheet extends outside the periphery of the absorber 3 and blocks movement of excrement absorbed by the absorber 3 to the back side. . As the stretched back sheet 9, a sheet having moisture permeability can be used without impairing water shielding from the viewpoint of preventing stuffiness.

  In order to make the appearance and feel like the outer surface of a cloth diaper, the entire back surface of the back sheet 6 is covered with a nonwoven fabric layer 9A, and the outer periphery of the back sheet 6 extends to the outer periphery of the diaper. A spunbonded nonwoven fabric is suitable as the nonwoven fabric layer 9A.

(Top sheet)
As the top sheet 2, a perforated or non-porous nonwoven fabric or a perforated plastic sheet is used. As the material fiber constituting the nonwoven fabric, synthetic fibers such as polyethylene or polypropylene, synthetic fibers such as polyester and amide, recycled fibers such as rayon and cupra, and natural fibers such as cotton can be used. Moreover, as a processing method of a nonwoven fabric, well-known methods, such as the spunlace method, the spun bond method, the SMS method, the thermal bond method, the melt blown method, the needle punch method, the air through method, the point bond method, can be used. The basis weight of the nonwoven fabric used for the liquid-permeable top sheet 2 is preferably 15 to 30 g / m ² , and the thickness is preferably 0.05 to 1 mm.

  The top sheet 2 extends outward from the periphery of the absorber 3, and a portion extending outward from the side edge of the absorber 3 is fixed to the stretchable sheet 1 by, for example, a hot melt adhesive. In addition, the dot pattern in a figure represents the adhering part.

(3D gathering around the legs)
On both sides of the disposable diaper, leg gathering three-dimensional gathers G are provided. An example of the configuration is shown.
In the illustrated example, the stretchable sheet 1A that forms a three-dimensional gather is obtained by laminating a wide first sheet layer 21, short-width elastic films 30 and 30, and a wide second sheet layer 22. Of course, each constituent layer of the stretchable sheet 1A may have the same width.
The elastic sheet 1A is fixed to the back sheet 9 on the outer side.

  The stretchable sheet 1A of the leg gathering three-dimensional gathers is fixed to the inner surface of the article (in the illustrated form, the top sheet 2 surface) by means of a hot melt adhesive at both ends in the front-rear direction, and is a lying portion. The middle part in the front-rear direction is a non-fixed free part, and as a result of contraction force acting, as shown in FIG. 23, it stands up with respect to the use surface of the diaper (the surface of the top sheet 2 in the illustrated embodiment). A leg gathering solid gather G is constructed.

As shown in FIGS. 20 and 23, regions other than the stretchable portion 83 and the stretchable portion 84 of the stretchable sheet 1A are substantially non-stretchable regions by increasing the bonding area ratio.
The inside of the stretchable sheet 1A constitutes a three-dimensional gather G with the stretchable part 83, and the outside of the stretchable sheet 1A constitutes a planar gather with the stretchable part 84.
In this example, it is possible not to form the stretchable portion 84. It is also possible to change the bonding area ratio between the stretchable part 83 and the stretchable part 84.

(Fastening tape)
Fastening tapes T that protrude from the side edges are attached to the side flaps of the back part B, and the front target tape 6 is stuck along the width direction on the waist part surface of the abdomen part Fr. When wearing on the body, with the diaper applied to the body, the fastening tape T on both sides is turned from each side of the waist to the abdomen outer surface and fastened to the front target tape 6 via the hook material 5. The front target tape 6 can be omitted. In this case, the fastening tape T is directly hooked and fixed to the nonwoven fabric on the outer surface of the diaper. Reference numeral 7 denotes a dividing perforation.

The constituent material of the first sheet layer 21 and the second sheet layer 22 can be used without particular limitation as long as it is a sheet, but it is preferable to use a nonwoven fabric from the viewpoint of air permeability and flexibility. The nonwoven fabric is not particularly limited as to what the raw fiber is. For example, synthetic fibers such as olefins such as polyethylene and polypropylene, polyesters and polyamides, recycled fibers such as rayon and cupra, natural fibers such as cotton, and mixed fibers and composite fibers using two or more of them. Etc. can be illustrated. Furthermore, the nonwoven fabric may be manufactured by any processing. Examples of the processing method include known methods such as a spunlace method, a spunbond method, a thermal bond method, a melt blown method, a needle punch method, an air through method, and a point bond method. When using a nonwoven fabric, the basis weight is preferably about 10 to 25 g / m ² .

By the way, the shape in the natural length state of each joint part 40 and the through-hole 31 is arbitrary, such as a perfect circle, an ellipse, polygons, such as a rectangle (including a linear or rounded thing), a star shape, a cloud shape, etc. It can be made into the shape. The size of each joint 40 may be determined as appropriate, but if it is too large, the effect of the hardness of the joint 40 on the feel will increase, and if it is too small, the joint area will be small and the materials will not be sufficiently bonded together. Therefore, in the normal case, the area of each joint 40 is preferably about 0.14 to 3.5 mm ² . The opening area of each through hole 31 may be equal to or larger than the joint portion because the joint portion is formed through the through hole 31, but is preferably about 1 to 1.5 times the area of the joint portion.

Moreover, as a junction part of this invention, although you may transfer directly from a main expansion-contraction part to a non-expandable area | region, the transition expansion / contraction part of the intermediate | middle can also be formed.
In general, the area and the area ratio of each joint 40 in each region are preferably set as follows.
(Non-stretchable area)
Area of the joint 40: 0.14 to 3.5 mm ² (particularly 0.25 to 1.0 mm ² )
Area ratio of the joint 40: 16 to 45% (especially 25 to 45%)
(Main stretchable part 83)
Area of the joint 40: 0.14 to 3.5 mm ² (particularly 0.14 to 1.0 mm ² )
Area ratio of the joint 40: 1.8 to 19.1% (particularly 1.8 to 10.6%)
(Transition expansion / contraction part)
Area of the joint 40: 0.14 to 3.5 mm ² (particularly 0.25 to 1.0 mm ² )
Area ratio of the joint 40: 8 to 22.5% (particularly 12.5 to 22.5%)

  The planar arrangement of the joints 40 and the through-holes 31 can be determined as appropriate, but is preferably a regularly repeated planar arrangement, such as an oblique lattice shape as shown in FIG. 24 (a) or as shown in FIG. 24 (b). Hexagonal lattice shape (these are also called staggered shapes), a square lattice shape as shown in FIG. 24C, a rectangular lattice shape as shown in FIG. 24D, and a parallel shape as shown in FIG. Body lattice (in the form shown in the figure, two groups are provided so that a large number of groups of parallel diagonal rows intersect each other), etc. (in which these are inclined at an angle of less than 90 degrees with respect to the expansion / contraction direction) In addition to those that are regularly repeated, the group of joints 40 (group unit arrangement may be regular or irregular, and may be a pattern, a character shape, etc.) shall be regularly repeated. You can also. The arrangement form of the joint portion 40 and the through-hole 31 may be the same or different in the main stretchable portion 83, the transition stretchable portion, and the non-stretchable region.

The elastic film 30 is not particularly limited, and can be used without particular limitation as long as it is a resin film having its own elasticity. For example, a styrene-based elastomer, an olefin-based elastomer, a polyester-based elastomer, a polyamide-based elastomer, and a polyurethane-based film can be used. A product obtained by processing one or two or more blends of thermoplastic elastomers such as elastomers into a film by extrusion molding such as a T-die method or an inflation method can be used. Moreover, as the elastic film 30, the thing in which many holes and slits were formed for ventilation other than a non-porous thing can also be used. In particular, the tensile strength in the stretching direction is 8 to 25 N / 35 mm, the tensile strength in the direction perpendicular to the stretching direction is 5 to 20 N / 35 mm, the tensile elongation in the stretching direction is 450 to 1050%, and the direction perpendicular to the stretching direction. It is preferable that the elastic film 30 has a tensile elongation of 450 to 1400%. Note that the tensile strength and tensile elongation (breaking elongation) were JIS K7127 except that a tensile tester (for example, AOUTGRAPHAGS-G100N manufactured by SHIMADZU) was used and the test piece was a rectangular shape having a width of 35 mm and a length of 80 mm. According to 1999 “Plastics—Testing Method for Tensile Properties”, it means a value measured with an initial chuck interval of 50 mm and a tensile speed of 300 mm / min. Although the thickness of the elastic film 30 is not specifically limited, It is preferable that it is about 20-40 micrometers. The basis weight of the elastic film 30 is not particularly limited, but is preferably about 30 to 45 g / m ² , particularly preferably about 30 to 35 g / m ² .

(Application example to pants-type disposable diapers)
Said elastic sheet is applied to an absorbent article, The application example to a pants type disposable diaper is also demonstrated.
In addition, the dotted pattern part in sectional drawing has shown joining means, such as a hot-melt-adhesive.

  25 to 29 show a pants-type disposable diaper. This pants-type disposable diaper (hereinafter also simply referred to as a diaper) has an exterior body 20 that forms a front body Fr and a back body Ba, and an interior body 10 that is fixed to and integrated with the inner surface of the exterior body 20. The interior body 10 is formed by interposing an absorbent body 13 between a liquid-permeable top sheet 11 and a liquid-impermeable back sheet 12. In manufacturing, after the back surface of the interior body 10 is joined to the inner surface (upper surface) of the exterior body 20 by a joining means such as a hot melt adhesive (shaded portion 10B in FIG. 21), the interior body 10 and the exterior body 20 are joined. Is folded at the center in the front-rear direction (vertical direction), which is the boundary between the front body Fr and the back body Ba, and both side portions thereof are joined to each other by heat welding or hot melt adhesive to form the side seal portion 26. Thus, a pants-type disposable diaper having a waist opening and a pair of left and right leg openings is formed.

(Structural example of interior body)
As shown in FIGS. 27 to 29, the interior body 10 has an absorbent body 13 interposed between a liquid-permeable top sheet 11 made of nonwoven fabric or the like and a liquid-impermeable back side sheet 12 made of polyethylene or the like. The excretory fluid that has permeated through the top sheet 11 is absorbed and retained. The planar shape of the interior body 10 is not particularly limited, but is generally rectangular as illustrated.

  As the liquid-permeable surface sheet 11 covering the surface side (skin contact surface side) of the absorbent body 13, a porous or non-porous nonwoven fabric or a porous plastic sheet is preferably used. The material fibers that make up the nonwoven fabric can be synthetic fibers such as polyethylene or polypropylene, synthetic fibers such as polyester or polyamide, recycled fibers such as rayon or cupra, natural fibers such as cotton, and the spunlace method. A nonwoven fabric obtained by an appropriate processing method such as a spun bond method, a thermal bond method, a melt blown method, or a needle punch method can be used. Among these processing methods, the spunlace method is excellent in terms of flexibility and drapeability, and the thermal bond method is excellent in terms of being bulky and soft. When a large number of through holes are formed in the liquid permeable surface sheet 11, urine and the like are quickly absorbed, and the dry touch property is excellent. The liquid permeable top sheet 11 is wound around the side edge of the absorber 13 and extends to the back side of the absorber 13.

  As the liquid-impermeable back sheet 12 that covers the back surface side (non-skin contact surface side) of the absorbent body 13, a liquid-impermeable plastic sheet such as polyethylene or polypropylene is used. Those having wettability are preferably used. This water-impervious and moisture-permeable sheet is a microporous sheet obtained by, for example, melt-kneading an inorganic filler in an olefin resin such as polyethylene or polypropylene to form a sheet, and then stretching in a uniaxial or biaxial direction. is there.

Absorbent body 13 is a known one, for example, a pulp fiber stack, a filament aggregate such as cellulose acetate, or a non-woven fabric, mixed with a superabsorbent polymer as necessary, fixed, etc. Can be used. The absorbent body 13 can be packaged with a wrapping sheet 14 having liquid permeability and liquid retention, such as crepe paper, if necessary, for holding the shape and polymer.
The shape of the absorber 13 is formed in a substantially hourglass shape having a narrowed portion 13N having a narrower width than the front and rear sides in the crotch portion, but may be an appropriate shape such as a rectangular shape. Although the size of the constricted portion 13N can be determined as appropriate, the length in the front-rear direction of the constricted portion 13N can be about 20 to 50% of the total length of the diaper, and the width of the narrowest portion is 40% of the total width of the absorber 13. It can be about -60%. In the case of having such a constricted portion 13N, if the planar shape of the interior body 10 is substantially rectangular, the remainder of the interior body 10 that does not have the absorber 13 in the portion corresponding to the constricted portion 13N of the absorber 13 A part is formed.

  Solid gathers GA that fit around the legs are formed on both sides of the interior body 10. This three-dimensional gather GA is formed by the stretchable sheet 1B according to the present invention, and as shown in FIGS. 28 and 29, a fixed portion fixed to the side of the back surface of the interior body, and from this fixed portion to the interior body A body part that extends to the side of the surface of the interior body through the side, a lodging part that is formed by fixing the front and rear ends of the body part to the side part of the surface of the interior body in a lying state, and this lodging part The space is an unfixed free part.

  In addition, the elastic sheet 1B forming the three-dimensional gather GA has an elastic film 30 disposed on the tip side thereof to constitute an elastic part that expands and contracts in the front-rear direction, and is elastic as shown by a two-dot chain line in FIG. The free part is raised by the stretching force of the film 30 to form the three-dimensional gather GA.

  The liquid-impermeable back sheet 12 is folded back on the both sides in the width direction of the absorber 13 together with the liquid-permeable surface sheet 11. As the liquid-impermeable back side sheet 12, it is desirable to use an opaque sheet so that brown such as defecation and urine does not appear. As the opacification, a plastic film and a pigment and filler such as calcium carbonate, titanium oxide, zinc oxide, white carbon, clay, talc and barium sulfate are preferably used.

(External body structure example)
As shown in FIGS. 25 to 27, the exterior body 20 is provided with an elastic film 30 and an elongated elastic member 24 along the width direction between the first sheet layer 21 and the second sheet layer 22. Elasticity in the width direction is given. The planar shape of the exterior body 20 has a pseudo hourglass shape as a whole due to concave leg-around lines 29 formed to form leg openings on both sides of the middle. The exterior body 20 may be divided into two parts in the front-rear direction so that both are separated in the front-rear direction at the crotch part.

  More specifically, in the exterior body 20 of the illustrated embodiment, the waist portion 23 is located on the waist portion 23 in the waist region T defined as the longitudinal range of the side seal portion 26 where the front body Fr and the back body Ba are joined. An elastic member 24 is provided. The waist elastic member 24 in the illustrated form is an elongated elastic member such as a plurality of rubber bands arranged at intervals in the vertical direction, and gives a stretching force so as to tighten around the body torso. The waist elastic members 24 are not arranged substantially as a single bundle with a close interval, but with a spacing of about 3 to 8 mm so as to form a predetermined stretch zone, preferably three or more, preferably Five or more are arranged. The stretch rate at the time of fixing the waist elastic member 24 can be determined as appropriate, but can be about 230 to 320% in the case of a normal adult. As the waist elastic member 24, one or a plurality of belt-like elastic members can be used.

  In the illustrated example, thread rubber is used for the waist elastic member 24. However, for example, a tape-like elastic member may be used. Alternatively, the elastic film 30 may extend to the waist 23. The waist elastic member 24 in the illustrated form is sandwiched between folded portions 20C formed by folding the constituent material of the second sheet layer 22 to the inner surface side at the waist opening edge. You may pinch | interpose between the structural materials of the sheet | seat layer 22. FIG.

<Explanation of terms in the specification>
The following terms in the specification have the following meanings unless otherwise specified in the specification.
“Elongation rate” means a value when the natural length is 100%.
・ "Weight" is measured as follows. After the sample or test piece has been pre-dried, it is left in a test room or apparatus in a standard state (test location is temperature 20 ± 5 ° C., relative humidity 65% or less) to obtain a constant weight. Pre-drying refers to making a sample or test piece constant in an environment where the relative humidity is 10 to 25% and the temperature does not exceed 50 ° C. In addition, it is not necessary to perform preliminary drying about the fiber whose official moisture content is 0.0%. A sample with a size of 200 mm × 250 mm (± 2 mm) is cut out from the test piece in a constant weight using a rice-basis plate (200 mm × 250 mm, ± 2 mm). Measure the weight of the sample, multiply it by 20, calculate the weight per square meter, and use it as the basis weight.
-"Thickness" is automatically measured using an automatic thickness measuring instrument (KES-G5 handy compression measurement program) under the conditions of load: 10 gFr / cm ² and pressure area: 2 cm ² .
・ If there is no description about the environmental conditions in the test and measurement, the test and measurement shall be performed in a test room or equipment in the standard condition (test location is temperature 20 ± 5 ℃, relative humidity 65% or less). .

INDUSTRIAL APPLICABILITY The present invention can be used for absorbent articles in general having a stretchable structure such as a pants-type disposable diaper as described above, various disposable diapers such as a tape type and a pad type, and a sanitary napkin.
The example of the sanitary napkin is almost the same as the example of FIG.

  A to D ... area, Ba ... back body, Fr ... front body, G, GA ... solid gather, T, Ta ... tape, TD ... tape type disposable diaper, 1A, 1B ... elastic sheet, 2 ... top sheet, 3 ... Absorber, 9 ... back sheet, 21 ... first sheet layer, 22 ... second sheet layer, 30 ... elastic film, 31 ... through-hole, 40 ... joint, 83, 84 ... stretchable part.

Claims (13)

An absorbent article provided with three-dimensional gathers formed on both sides by an elastic sheet having an elastic part that can expand and contract in the front-rear direction,
The three-dimensional gather is
At both ends in the front-rear direction of the absorbent article, the stretchable sheet is fixed to the inner surface of the absorbent article in a lying state, and at the middle part in the front-rear direction of the absorbent article, the stretchable sheet of the absorbent article The stretchable portion is not fixed to the inner surface, and the stretchable portion is provided in the unfixed portion, and the stretchable portion contracts in the front-rear direction, whereby the stretchable sheet stands on the use surface of the absorbent article. With the configuration,
In the stretchable sheet, an elastic film that is stretchable in at least the front-rear direction is laminated between the first sheet layer having no stretchability and the second sheet layer, and the first sheet layer and the second sheet layer The second sheet layer is joined at a large number of spaced joints, either directly or via an elastic film,
The stretchable part contracts due to the contraction force of the elastic film, and can be extended when an external force is applied in the front-rear direction.
In stretching portion, an absorbent article junction area fraction of an total area of the joint portions included in the unit area, characterized in that different in the width direction. An absorbent article provided with three-dimensional gathers formed on both sides by an elastic sheet having an elastic part that can expand and contract in the front-rear direction,
The three-dimensional gather is
At both ends in the front-rear direction of the absorbent article, the stretchable sheet is fixed to the inner surface of the absorbent article in a lying state, and at the middle part in the front-rear direction of the absorbent article, the stretchable sheet of the absorbent article The stretchable portion is not fixed to the inner surface, and the stretchable portion is provided in the unfixed portion, and the stretchable portion contracts in the front-rear direction, whereby the stretchable sheet stands on the use surface of the absorbent article. With the configuration,
In the stretchable sheet, an elastic film that is stretchable in at least the front-rear direction is laminated between the first sheet layer having no stretchability and the second sheet layer, and the first sheet layer and the second sheet layer The second sheet layer is joined at a large number of spaced joints, either directly or via an elastic film,
The stretchable part contracts due to the contraction force of the elastic film, and can be extended when an external force is applied in the front-rear direction.
The absorbent article characterized in that the joint area ratio occupied by the total area of the joints included in the unit area in the stretchable part is different in the front-rear direction. The absorptive article according to claim 1 or 2 joined in the state where the width of said elastic film is shorter than one width of said 1st sheet layer and the 2nd sheet layer in said elastic sheet. The absorption according to claim 1 or 2 , wherein in the stretchable sheet, a plurality of the elastic films having a width shorter than the width of the first sheet layer and the second sheet layer are arranged at intervals in the width direction. Sex goods. Among the plurality of elastic films, the elastic film on the center side in the width direction constitutes the three-dimensional gather, the elastic film on the outer side in the width direction constitutes a flat gather ,
5. The elastic film capable of expanding and contracting at least in the front-rear direction is laminated between the first sheet layer having no stretchability and the second sheet layer in the stretchable sheet of the planar gather. The absorbent article as described. The absorbent article according to claim 1, wherein the joint area ratio is different in the front-rear direction in the stretchable part. The absorptive article according to claim 2 or 6 with which said junction area rate is high toward the edge at least in the front-and-rear direction edge side in said elastic part . The width direction side edge side the joint area ratio of the stretchable portion is high, the absorbent article according to claim 1 or 6, wherein the bonding area ratio of the width direction center side is lower. The width direction side edge side the joint area ratio of the stretchable portion is low, the absorbent article according to claim 1 or 6, wherein the bonding area ratio of the width direction center side is higher. The absorbent article according to claim 1 , wherein the elastic film can be expanded and contracted in a width direction. The absorptivity according to claim 1 , 2 or 6, wherein the first sheet layer and the second sheet layer are joined and formed through a through hole formed in the elastic film at a plurality of joint portions spaced apart from each other. Goods. The absorbent article according to claim 1 , 2 or 6, wherein the joint portion has a length in the width direction longer than the length in the front-rear direction. Said absorbent article is a sanitary napkin, the absorbent article of the expansion and contraction sheet, according to claim 1, 2 or 6, further comprising a three-dimensional gathers formed on both sides with the extendable portion can be stretchable in the longitudinal direction .