JP6447924B2 - Disposable diapers - Google Patents

Description

  The present invention relates to a disposable diaper having an elastic 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 region material such as rubber thread while being stretched in the longitudinal direction has been widely adopted, but stretchability is imparted to some extent. In the case where the user wants to do so, a mode is adopted in which the rubber thread is fixed in a state of being arranged side by side in the width direction.

  In the case of using a plurality of thread rubbers arranged in parallel, the tightening force is different between the thread rubber and the periphery thereof, so that the wearer's skin is pressed in a streak shape and the touch is not good. In particular, problems remain around the sensitive waist.

  On the other hand, there is also proposed a non-woven fabric / elastomer film / non-woven fabric that is pressed into a planar shape to give stretchability and that takes into consideration the touch. (For example, refer to Patent Document 1).

  However, since the stretchable sheet according to Patent Document 1 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 sheets are in different positions, the stretching stress is uniform.

  If this stretchable sheet is applied to both the waist circumference and the waist circumference, the required tightening force is different, and therefore two types of stretchable sheets having different stretching stresses for those portions are required.

Japanese Patent No. 4562391

  Then, the main subject of this invention is providing the disposable diaper which can give a required clamping force with respect to both the circumference | surroundings of a waist and a waist | hip | lumbar circumference essentially with one sheet of elastic sheets.

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

(Basic form)
The disposable diaper of the present invention has a stretchable region in the width direction around the waist including the waist and waist, and is stretchable in the width direction.
The sheet on the back surface constituting the circumference of the trunk is an elastic sheet,
In the stretchable sheet, an elastic film stretchable in the width 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 are laminated. The sheet layer is joined at a large number of spaced joints, either directly or via an elastic film,
The stretchable sheet contracts due to the contraction force of the elastic film, and can expand when an external force is applied in the width direction.
In this invention, the said expansion-contraction area | region of the front-back direction edge part of the said expansion-contraction sheet is return | folded to the inner surface side, and it is set as the double structure of an expansion-contraction sheet.
If the stretchable sheet is doubled, in other words, if the stretchable region is doubled, the stretch stress in that region is substantially doubled and increased with respect to the stretch stress in the non-double region. Therefore, the waist circumference can be tightened firmly. On the other hand, in a non-double region, it can be tightened without excessive pressure by a small stretching stress.

  Although the length in the front-rear direction to be doubled can be selected as appropriate, it can be set to 8 mm to 50 mm, and this can be set around the waist and a single region around the waist.

  On the other hand, the stretching stress can be made different by making the joint area ratio occupied by the total area of the joints included in the unit area differ between the dual structure region and other regions.

Under the condition that the elastic stress around the waist needs to be larger than the elastic stress around the waist, the double structure around the waist is required to double the elastic stress around the waist. There is an effective method when it is not necessary to do so.
That is, for the junction area ratio occupied by the total area of the junction included in the unit area, the junction area ratio of the dual structure region is made larger than the junction area ratio of other regions. By making it larger than the joint area ratio, the stretching stress is reduced.
However, even if the stretching stress is small, the double structure is adopted, and as a result, the stretching stress of the double structure can be made larger than the stretching stress of other regions.

  An absorber is arranged in the waist area, and a liquid-impervious cover sheet is provided over the end of the absorber and the folded portion of the double structure. Can do. According to this aspect, even if the body fluid absorbed from the end portion of the absorbent body flows out in the front-rear direction, the body fluid can be prevented from flowing out by the liquid-impermeable cover sheet.

  In the present invention, the arrangement pattern of the joints is not limited. One example is a staggered arrangement that exhibits a good appearance.

  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.

In the junction part of the expansion-contraction area | region of this invention, there exists the following joining form example, for example.
(1) A form in which 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.

In such a case, in the stretchable region, the elastic film stretchable at least in the width direction is laminated between the first sheet layer that does not have stretchability and the second sheet layer that does not have stretchability. In addition, the first sheet layer and the second sheet layer are formed by being joined through a through-hole formed in the elastic film at a large number of spaced joints.
In the case where the through hole is formed, there is an advantage that air permeability is ensured. The through holes do not need to be formed in all the joints, and exhibit air permeability even if formed in some of the joints. When the elastic film can expand and contract only in the width direction, the through hole has a shape extending in the width direction from the edge of the joint. When the elastic film can be expanded and contracted in both the width direction and the orthogonal direction, the through hole has a shape extending in both directions from the edge of the joint portion, and in some cases, may have an annular shape around the joint portion.

  The joint is provided with a configuration in which the orthogonal direction length is longer than the width direction length.

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, it is possible to give a necessary tightening force to both the waist circumference and the waist circumference with a single elastic sheet.

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 a schematic plan view of still another example in which the joint area ratio is different. It is a schematic plan view of still another example in which the joint area ratio is different. 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 an expansion | extension and 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 explanatory drawing of the other example of a formation method of a through-hole. (A) And (b) is explanatory drawing which shows the junction arrangement pattern of the expansion-contraction area | region around a waist. It is a top view (inner surface side) of the underpants type disposable diaper of a full deployment state. It is a top view (outer surface side) of the underpants type disposable diaper of a full deployment state. (A) is 18a-18a sectional drawing of FIG. 16, (b) is 18b-18b sectional drawing of FIG. It is 19-19 sectional drawing of FIG. It is 20-20 sectional drawing of FIG. It is a top view which shows only the principal part of the underpants type disposable diaper of a full expansion | deployment state. It is a top view for description of the example of the joint arrangement pattern in the trunk periphery region of the exterior body extended to some extent in the width direction. It is a top view for description of the other example of a junction arrangement pattern. It is a photograph in the natural length state of the sample of the embodiment. It is the photograph in the expansion | extension state of the sample of the example of an embodiment. It is a photograph which shows the natural length state after an elastic film tears. It is outline | summary explanatory drawing of a peeling test. It is a top view which shows the various arrangement | sequence examples of a junction part. It is an expansion state outline top view of a tape type disposable diaper.

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

The disposable diaper of this invention has an expansion-contraction area | region which can be expanded-contracted in the width direction. As shown in FIGS. 7 to 9, this stretchable region is, for example, between a first sheet layer 21 made of non-woven fabric that does not have stretchability and a second sheet layer 22 made of non-woven fabric that does not have stretchability, for example. The elastic film 30 that can be expanded and contracted in the width 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 intervals. 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, as shown in FIG. 11 , the first sheet layer 21, the elastic film 30 and the second sheet are disposed between the anvil roll 60 having the projections 60a formed in a predetermined pattern on the outer surface and the ultrasonic horn 61. The 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.

Opposite roll 63 is arranged to face the anvil roll 60. A driving roll 65 is provided with respect to the facing roll 63 and serves as a nip roll that sandwiches the elastic film 30.
In the structure of such an apparatus, after the elastic film 30 is circulated around the opposing roll 63, the nip position with the drive roll 65 is reached, and thereafter the anvil roll 60 is circulated.

  At that time, by making the peripheral speed of the driving anvil roll 60 faster than the peripheral speed of the driving roll 65 (and thus the peripheral speed of the opposing roll 63), the elastic film 30 is stretched and the anvil roll 60 Joining is performed by the group of protrusions 60 a 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 in the manufacturing process of the elastic film 30 (based on the length of the natural state as 100%) Can be set.

  FIG. 8 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. 9 (schematic diagram), the stretchable sheet contracts due to the contraction force of the elastic film 30 and can be stretched when an external force is applied in the width direction (left-right direction in FIG. 9). Therefore, when this stretchable sheet is used, for example, in the waist circumference direction of a disposable diaper, the waist or waist is contracted.

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 may be applied. In this regard, in conventional disposable diapers, it is common to fix a plurality of thread rubbers in parallel on a sheet, but this is due to deterioration of hot rubber adhesive for fixing to thread rubbers and sheets. It is inferior in terms of quality deterioration and stable productivity during production. These problems can be solved by the stretchable sheet according to the present invention.
Moreover, as can be seen from the contracted state of FIG. 9, 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.

  Now, in the region of the stretchable sheet, the joint area ratio occupied by the total area of the joints included in the unit area is different in the front-rear direction of the disposable diaper, so that the stretch stress is different. desirable.

Here, the junction area ratio is a percentage of the total area of the junctions 40, 40... Included in the unit area S in the unit area S, as shown in FIG. . 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 the arrangement interval length in the machine direction, Lc is the arrangement interval length in the orthogonal direction (cross direction) orthogonal to the machine direction, Pm is the machine direction (MD pitch length, and Pc is the 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.
FIG. 2 shows that the area A, B, and C have a joint area ratio of A <B <C so that the stretching stress is in the relationship of A>B> C.
For example, when the pitch length Pm and the pitch length Pc are long and A is compared with the case C when the pitch length Pm and the pitch length Pc are short, a case where the pitch length Pm · Pc is long is A (when the joint area ratio is low). In the case where the pitch length Pm · Pc is short, the elongation ratio is larger than in C (when the joint area ratio is high). As a result, the stretching stress has a relationship of A>B> C. B is the case of the middle case.
In the form of FIG. 2, the elongation stress differs for each region. Therefore, when the absorbent article is worn, the contraction force varies for each region, which is useful.

  In the case of FIG. 3, this is an example in which the stretching stress in the intermediate region in the horizontal direction in the drawing is made smaller than the regions on both sides. In this example, in the waist of the disposable diaper, the intermediate region is made to correspond to the region where the absorbent body exists, and the stretching stress is made small or substantially non-stretchable. It is effective in the case of giving sufficient stretching stress to the side part) to fit the disposable diaper comfortably to the wearer.

  As shown in FIG. 4, the regions having different joint area ratios are effective when arranged in the vertical direction (front-rear direction of the disposable diaper) in FIG. 4.

  Furthermore, as shown in FIG. 5, when the junction area ratio is made different in the vertical direction of FIG. 5, as shown in FIG. 6, the junction area ratio is made different in the horizontal direction of FIG. .

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. 6 shows an example in which a large number of small junctions are arranged in the region E and the junction area is the same as that of the region D. By setting the joint area to A <E = D, the stretching stress is in the relationship of A> E = D.

  By the way, the elastic film in the present invention may be stretchable only in the width direction, but a two-way stretchable film that stretches in the direction perpendicular to the direction is suitable.

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 during the production of the elastic sheet, as shown in FIG.
Through-holes 31 can be formed around the periphery. 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 it is used as a member around the waist of a disposable diaper, it becomes a waist sheet with good breathability.

  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 balance point, and opens. it is conceivable that.

  FIG. 12 schematically shows an example of forming the through hole 31 in the case of a circular through hole. The crescent-shaped through holes 31 are 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. 13, it is possible to form a semicircular through hole 31 having a large opening, which is suitable when it is desired to improve air permeability.

On the other hand, it is not essential that the through holes 31 are formed in all the coupling portions. If it is required to reliably form the through hole 31 or make a large opening, the method shown in FIG. 14 can be adopted.
That is, as shown in FIG. 14B, the stretchable sheet in which the coupling portion 40 is formed is passed between a pair of rolls 64 having protrusions or protrusions 64a, and between the 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 pants-type disposable diapers)
The stretchable sheet formed as described above is applied to a disposable diaper. As an example, an application example to a pants-type disposable diaper will be described.

  15-20 has shown the underpants 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. 18 to 20, the interior body 10 has an absorbent body 13 interposed between a liquid-permeable top sheet 11 made of a 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.

  A solid gather BS that fits around the legs is formed on both sides of the interior body 10. As shown in FIGS. 19 and 20, the three-dimensional gather BS includes a fixed portion fixed to a side portion on the back surface of the interior body, and a side portion on the surface of the interior body from the fixed portion to the side of the interior body. The body part that extends to the front, the front and rear ends of the body part in a lying state, and the lying part that is fixed to the side of the surface of the interior body, and the freedom part that is formed with this lying part being unfixed The part is formed of a gathered nonwoven fabric 15 that is turned into a double sheet by folding.

  Further, between the double sheets, an elongated gather elastic member 16 is disposed at the tip of the free part. The gather elastic member 16 is for forming a three-dimensional gather BS by raising a free part by elastic expansion and contraction force as shown by a two-dot chain line in FIG. 19 in the product state.

  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.

  As the gathered elastic member 16, materials such as styrene rubber, olefin rubber, urethane rubber, ester rubber, polyurethane, polyethylene, polystyrene, styrene butadiene, silicon, and polyester that are usually used can be used. In order to make it difficult to see from the outside, it is preferable that the thickness is 925 dtex or less, the tension is 150 to 350%, and the interval is 7.0 mm or less. The gathered elastic member 16 may be a tape-like member having a certain width in addition to the thread-like shape shown in the figure.

  In the same manner as the liquid-permeable surface sheet 11, the material fiber constituting the gathered nonwoven fabric 15 is made of synthetic fibers such as polyethylene or polypropylene, synthetic fibers such as polyester or amide, recycled fibers such as rayon or cupra, and cotton. Non-woven fabric obtained by an appropriate processing method such as a spunbond method, a thermal bond method, a melt blown method, a needle punch method, etc. can be used. It is preferable to use a nonwoven fabric that suppresses the basis weight and has excellent air permeability. Furthermore, for the gathered nonwoven fabric 15, in order to prevent the transmission of urine and the like, to prevent fogging, and to enhance the touch to the skin (dry feeling), silicon-based, paraffin metal-based, alkylchromic croid-based water repellent, etc. It is desirable to use a water-repellent non-woven fabric coated with.

(External body structure example)
As shown in FIGS. 16 to 21, the exterior body 20 is provided with an elastic film 30 between the first sheet layer 21 and the second sheet layer 22, and is given stretchability in the width direction. . 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, as shown in FIG. 16, in the exterior body 20 of the illustrated embodiment, the waist region T defined as the longitudinal range of the side seal portion 26 in which the front body Fr and the back body Ba are joined. Among them, the stretch stress in the waist region 23 is formed larger than the stretch stress in the waist region TX. Thereby, the expansion-contraction force which clamps a waist periphery moderately can be given. Here, the waist area T = the waist area 23 + the waist area TX

  The waist area 23 includes a folded portion 20C obtained by folding the extending portion of the exterior body 20 having the elastic film described above to the inner surface side.

Although the constituent material of the 1st sheet layer 21 and the 2nd sheet layer 22 can be used without a limitation especially if it is a sheet form, it is preferable to use a nonwoven fabric from a viewpoint of air permeability and a softness | 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 . Further, the first sheet layer 21 and the second sheet layer 22 may be a pair of layers in which a part or all of the first sheet layer 21 is folded and faced.

In this embodiment, as shown in FIG. 16, the waist area T of the front body Fr, the waist area T of the back body Ba, and the intermediate area L between them in the exterior body 20 are made of the stretchable sheet described above. A laminated stretchable structure 20X is formed. In this example, the waist region T, the waist region T of the back body Ba, and a part of the intermediate region L between them constitute the “stretchable region” of the present invention. As shown in FIG. 18A, the middle portion of the intermediate region L is a non-stretchable region because the elastic film 30 does not exist.
In the region of the stretchable structure 20X of the exterior body 20, an intermediate portion in the width direction including a portion overlapping with the absorber 13 (a part or all of the overlapping portion may be sufficient, and it is desirable to include substantially the entire interior body fixing portion 10B). A non-expandable region 70 is formed in the region, and portions up to the side seal portions 26 on both sides in the width direction are formed as an expandable region 80 that expands and contracts in the width direction. The elastic film 30 is laminated between the first sheet layer 21 and the second sheet layer 22 throughout the stretchable region 80 and the non-stretchable region 70, and the elastic film 30 is stretched in the width direction. In the state, the first sheet layer 21 and the second sheet layer 22 are a large number of joints 40 arranged at intervals in the expansion / contraction direction (width direction) and the direction orthogonal to the expansion direction (width direction), respectively ( In the example shown in the figure, they are joined through a through-hole 31 formed in the elastic film 30.

In such a laminated stretchable structure 20X, basically, the higher the area ratio of the joint portion 40, the smaller the portion where the first sheet layer 21 and the second sheet layer 22 are contracted by the elastic film 30, so that the elastic limit elongation is increased. Along with this, the area ratio of the opening of the through hole 31 in the elastic film 30 also increases, and the proportion of the stretchable direction continuous portion of the elastic film 30 occupying in the direction orthogonal to the stretchable direction decreases. There is a tendency that the elastic film 30 is easily torn as the contraction force generated is reduced.
By utilizing such characteristics, in the non-stretchable region 70, the area ratio of the joint portion 40 is higher than that of the stretchable region 80, so that the elastic limit elongation in the stretch direction is 130% or less (preferably 120% or less, more preferably In the stretchable region 80, the area ratio of the joint 40 is lower than that of the non-stretchable region 70, so that the elastic limit elongation in the stretchable direction is 200% or more (preferably 265 to 295%). be able to. Here, “elastic limit elongation” means the elongation at the elastic limit (in other words, the state where the first sheet layer and the second sheet layer are completely expanded), and the natural length of the length at the elastic limit is 100. The percentage is expressed as%.

  In the stretchable region 80, as shown in FIG. 9, in the natural length state of the elastic film 30, the first sheet layer 21 and the second sheet layer 22 between the joints swell in a direction away from each other and intersect the stretchable direction. As shown in FIG. 8, a shrinking ridge 25 that bulges in the direction is formed. Even in a mounted state that extends to some extent in the width direction, the degree of bulge of the shrinking ridge 25 is small but remains. In addition, the state of the shrinkage wrinkle 25 in the mounted state and the natural length state also appears in the sample photographs of FIGS.

  In the non-stretchable region 70, as can be seen from the sample photographs of FIGS. 24 to 26, streaks or very small wrinkles are formed between the joints 40, but the area ratio of the joints 40 is extremely high. Therefore, the elasticity is substantially killed.

  In the present embodiment, as shown in FIGS. 16, 17, and 22 (a), the end of the stretchable region 80 on the non-stretchable region 70 side is more than the main stretchable region 81 excluding the end. A buffer expansion / contraction region 82 with a low area ratio of the joint 40 is formed.

  On the other hand, as shown in FIG.22 (b), it can also be set as the form which does not have the buffer expansion-contraction area | region 82. FIG.

The shapes of the individual joints 40 and the through holes 31 in the natural length state are arbitrary shapes such as polygons (including linear and rounded ones) such as true circles, ellipses, and rectangles, stars, and clouds. It can be. 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, it is preferable that the area and the area ratio of each joint 40 in each region are as follows in a normal case.
(Non-stretchable region 70)
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 region 81)
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%)
(Buffer expansion / contraction region 82)
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%)

  Thus, in order to make the area ratios of the joint portions 40 at three places (the non-stretchable region 70, the main stretchable region 81, and the buffer stretchable region 82) different from each other, as shown in FIG. What is necessary is just to change the number of the parts 40, or to change the area of each junction part 40 as shown in FIG.23 (b). In the former case, the area of the joint 40 can be the same in two or more of the non-stretchable region 70, the main stretchable region 81, and the buffer stretchable region 82, and can be different in all locations. In this case, the number of joints 40 per unit area can be the same at two or more of the non-stretchable region 70, the main stretchable region 81, and the buffer stretchable region 82, and can be different at all locations.

  The plane arrangement of the joints 40 and the through holes 31 can be determined as appropriate, but a plane arrangement that repeats regularly is preferable, and an oblique lattice shape as shown in FIG. 28 (a) or as shown in FIG. 28 (b). Hexagonal lattice shape (these are also called staggered shapes), a square lattice shape as shown in FIG. 28 (c), a rectangular lattice shape as shown in FIG. 28 (d), and a parallel shape as shown in FIG. 28 (e). 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 in the main stretchable region 81, the buffer stretchable region 82, and the non-stretchable region 70, or may be different.

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 .

The melting point of each constituent member of the stretchable sheet according to the present invention can be selected as appropriate. As described above, the preferred example is that the elastic film has a melting point of 95 to 125 ° C, more preferably 100 to 120 ° C. The melting point of the 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 more than 125 ° C to 160 ° C, more preferably 130 to 160 ° C.
The ultrasonic welding temperature can be changed by selecting ultrasonic energy from the horn. The ultrasonic energy from this horn cannot be directly converted into temperature, but when measured with a non-contact type thermometer, the temperature on the horn side is 40 ° C. to 30 ° C., and the temperature on the anvil roll side is 38 ° C. to 28 ° C. Shows stable productivity.
Further, under this stable operation, it is preferable to give melting energy converted to 125 ° C. to 145 ° C. from the horn side to the elastic film, which is higher than the melting point temperature of the elastic film, as estimated from observation of the bonding state. . Moreover, it is desirable that it is lower than melting | fusing point temperature of a 1st sheet layer and a 2nd sheet layer. The difference between the melting points of the first sheet layer 21 and the second sheet layer 22 and the melting point of the elastic film 30 is preferably about 10 to 45 ° C.
As a 1st sheet layer and a 2nd sheet layer, in the case of the waist circumference sheet of a disposable diaper, an optimal nonwoven fabric is a spunbond nonwoven fabric.

In the present invention, as shown in FIG. 16, there is a relationship of waist circumference region T = waist circumference region 23 + waist circumference region TX. The waist area 23 is a folded portion 20C. If the folded pattern is used as it is in the arrangement pattern of the joint portions 40 in the waist region TX, the stretching stress may become too large. Therefore, as shown in FIG. 15A, the joint area ratio of the waist area 23 can be made larger than the joint area ratio of the waist area TX, and the stretching stress can be reduced.
Thereby, although the stretching stress of the waist region 23 is not excessively increased, an appropriate stretching stress larger than the stretching stress of the waist region TX can be obtained.

The arrangement pattern of the joint portions 40 in the waist circumference region 23 in the present invention is not limited to a straight line as shown in FIG. 15A (may be a straight line in a plurality of rows). As shown in FIG. 15B, the positions in the width direction can be shifted on a plurality of rows in the front-rear direction.
In this case, since it is necessary to expand and contract in the width direction, the width direction (machine direction) pitch length Pm is preferably longer than the front-rear direction (cross direction) pitch length Pc.

The illustrated example is an example in which the stretchable structure 20X is applied to the waistline region T of the exterior body 20. However, the stretchable structure 20X may be applied to other regions, or the waistline region T and the back body Ba of the front body Fr. Appropriate changes can be made, such as a configuration in which the laminated stretchable structure 20X is not provided in the intermediate region L between the waistline region T (the illustrated configuration typically shown in FIG. 18A). is there.
Of course, the stretchable sheet may be divided into the front body Fr and the back body Ba. Moreover, although this embodiment has a non-stretchable region, it is also possible to adopt a form in which the entire laminated structure is a stretchable region and does not have a non-stretchable region.

(Front / rear holding sheet)
As shown also in FIG. 18, in order to cover the front and rear end portions of the interior body 10 mounted on the inner surface of the exterior body 20 and to prevent leakage from the front and rear edges of the interior body 10, the front and rear pressing sheets 50, 60 are provided. May be provided. Explaining in more detail about the illustrated form, the front presser sheet 50 extends over the entire width direction from the inner surface of the folded portion 20C of the waist side end portion to the position overlapping the front end portion of the interior body 10 in the inner surface of the front body Fr. The rear pressing sheet 60 extends across the entire width direction from the inner surface of the folded portion 20C at the waist side end portion to the position overlapping the rear end portion of the interior body 10 in the rear body Ba inner surface. When a slight non-adhesive portion is provided over the entire width direction (or only the central portion) at the crotch side edges of the front and rear pressing sheets 50, 60, not only does the adhesive not protrude, but this portion is slightly removed from the surface sheet. Can float and function as a leak-proof wall.

  If the front and rear pressing sheets 50 and 60 are attached separately as in the illustrated form, there is an advantage that the degree of freedom of material selection is increased, but there are also disadvantages such as an increase in materials and manufacturing processes. Therefore, the folded portion 20C formed by folding the exterior body 20 on the inner surface of the diaper can be extended to a portion overlapping the interior body 10 to form a portion equivalent to the above-described pressing sheets 50 and 60.

<Peel test>
As the first sheet layer and the second sheet layer, a spunbond nonwoven fabric having a basis weight of 17 g / m ^{2 made} of PE / PP composite fiber (core: polypropylene (melting point: 165 ° C.), sheath: polyethylene (melting point: 130 ° C.)), An elastic film having a basis weight of 35 g / m ² , a thickness of 35 μm, and a melting point of 110 to 120 ° C. was used. The elastic film is sandwiched between the first sheet layer and the second sheet layer so that the MD direction is aligned in a natural length state (regardless of whether it is a natural length or a stretched state in relative comparison of peel strength), Using a sonic seal device ("Haru SUH-30" manufactured by Suzuki Co., Ltd.), as shown in FIG. 29 (a), a rectangular joint 40 having a long side along the MD direction (short side 1.0 mm, long side) 1.5 mm) is formed in a rectangular lattice shape with a 1 mm interval in the CD direction perpendicular to the MD direction and a 17 mm interval in the MD direction, and a sample with an elastic film having a CD direction length of 100y80 mm and a MD direction length of 100x is 50 mm. 100 was produced (Example). The ultrasonic seal was pressed for about 3 seconds and was bonded so that the same person had the same pressure. The MD direction of the nonwoven fabric is the direction of fiber orientation of the nonwoven fabric (the direction along which the nonwoven fabric fibers are aligned). For example, a measurement method according to the fiber orientation test method based on zero distance tensile strength of the TAPPI standard method T481, It can be discriminated by a simple measuring method for determining the fiber orientation direction from the tensile strength ratio in the direction and the width direction.
Further, a sample without an elastic film was produced in the same manner as in the example except that the elastic film was removed and a two-layer structure was used (comparative example). This sample without an elastic film is considered to be the same as the structure of Patent Document 1 in which the first sheet layer and the second sheet layer are joined without an elastic film in terms of peel strength.
Then, using these laminated stretchable structure samples, as shown in FIG. 29 (b), the first sheet layer and the second sheet layer were peeled off from one end in the CD direction of the sample 100 by 101z: 30 mm by hand. Each of the peeled portions 101 is grasped with a chuck of a tensile tester, and the remaining 50 mm length is peeled from the above-mentioned peeling port in the expansion / contraction direction under the conditions of 50 mm between chucks and 300 mm / min. Was the peel strength. As the tensile test, Tensilon universal testing machine RTC-1210A manufactured by ORIENTEC was used.
As a result, the peel strength of the comparative example sample was 2.7 N, whereas the peel strength of the example sample was 10.2 N, which was a remarkably high value.

  On the other hand, the above-described stretchable structure 20X can be applied not only to a pants-type disposable diaper but also to a tape-type disposable diaper.

For example, as shown in FIG. 29, a stretchable structure X that expands and contracts in the width direction can be formed in a waist-around portion of a tape-type disposable diaper TD1 having tapes on both sides on the back side.
That is, the elastic sheet can be manufactured, and the elastic stress in the width direction can be made different between the waist region 23 and the waist region TX of the waist region T.

  As the entire structure of the tape-type disposable diaper, a publicly known one can be used as long as it is known to those skilled in the art, and therefore illustration and description thereof are omitted. 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. The tape-type disposable diaper may be a so-called “straight type” whose both side edges are straight.

  Among the stretchable regions, the joint area ratio can be made different from other regions along the leg-cut portion. That is, the inseam area is constricted toward the center, and among the leg-surrounding parts extending in the front-rear direction along the constriction, a stretchable region having a different joint area ratio is formed in the constricted inclined portion. Can do.

<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 state 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 used automatic thickness measuring instrument (KES-G5 Handy Compression measurement program), load: 10 gf / cm ^2, and the pressure area: automatically measured under the conditions of 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 a standard state (test location is temperature 20 ± 5 ° C, 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 stretchable sheet of the present invention can also be applied to auxiliary materials such as tape-type disposable diaper tape.

  A ... E region, Ba ... back body, Fr ... front body, L ... intermediate region, 10 ... interior body, 11 ... liquid permeable top sheet, 12 ... liquid impervious back side sheet, 13 ... absorber, 13N DESCRIPTION OF SYMBOLS ... Constricted part, 14 ... Packaging sheet, 15 ... Gathered nonwoven fabric, 16 ... Gather elastic member, 20 ... Exterior body, 21 ... First sheet layer, 22 ... Second sheet layer, 20C ... Folded part, 20X ... Stretch structure, 24 DESCRIPTION OF SYMBOLS ... Elastic part of waist part, 25 ... Shrinkage fold, 29 ... Line around leg, 30 ... Elastic film, 31 ... Through-hole, 40 ... Joint part, 70 ... Non-stretchable region, 80 ... Stretchable region, 81 ... Main stretchable region, 82 ... buffer expansion / contraction area.

Claims (3)

A disposable diaper that is stretchable in the width direction and has a stretchable region in the width direction around the waist including the waist and waist.
The sheet on the back surface constituting the circumference of the trunk is an elastic sheet,
In the stretchable sheet, an elastic film stretchable in the width 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 are laminated. The sheet layer is joined at a large number of spaced joints, either directly or via an elastic film,
The stretchable sheet contracts due to the contraction force of the elastic film, and is extensible when an external force is applied in the width direction.
The stretchable region at the end portion in the front-rear direction of the stretchable sheet is folded back to the inner surface side to form a double structure of the stretchable sheet,
The joint area ratio occupied by the total area of the joints included in the unit area is different between the double structure region and other regions, so that the stretching stress is different ,
About the junction area ratio occupied by the total area of the junction included in a unit area, the junction area ratio of the dual structure region is larger than the junction area ratio of other regions, and the expansion and contraction of the dual structure region Disposable diapers characterized in that the stress is greater than the stretching stress in other areas .   The absorbent body is arrange | positioned in the waist area | region, The liquid-impermeable cover sheet is provided ranging over this absorber edge part and the folding | turning part of the said double structure. Disposable diapers.   No hole is formed in the entire joining region of the joint, leaving the first sheet layer and the second sheet layer, and penetrating at least a boundary portion between the elastic film and the joint in the extending direction. The disposable diaper of Claim 1 in which the hole is provided.