JP7545230B2 - Stretchable sheet and absorbent article comprising said stretchable sheet - Google Patents

Description

The present invention relates to a stretchable sheet. The present invention also relates to an absorbent article that includes the stretchable sheet.

Stretchable sheets made by joining elastic members such as rubber threads between two sheets in a stretched state are known as sheets used in absorbent articles such as diapers. For example, Patent Document 1 describes a sheet in which multiple elastic members arranged in parallel are sandwiched between an inner sheet and an outer sheet, and the elastic members are fixed by intermittently welding the inner sheet to the outer sheet. The elastic members are arranged in a cross-sectional space closed by the welded parts of the inner sheet and the outer sheet near both sides in the diameter direction, and are fixed by the frictional force between the outer surface of the elastic members and the sheet that forms the closed space.

JP 2008-104853 A

The technology described in Patent Document 1 has the advantage that the elastic member can be bonded between two sheets without using adhesive. However, as a result of the inventor's investigation, it was found that the stretchable sheet described in the document has room for improvement in terms of its stretchability.

Therefore, the present invention is concerned with providing a stretchable sheet that can eliminate the drawbacks of the conventional technology described above, and an absorbent article that includes the stretchable sheet.

The present invention provides a stretchable sheet comprising a first sheet made of a fiber sheet, a second sheet made of a fiber sheet disposed opposite the first sheet, and an elastic member disposed in a stretched state between the two sheets and extending in one direction, the stretchable sheet having stretchability along the extending direction of the elastic member,
the first sheet and the second sheet are joined by a plurality of fused portions located on both sides of the elastic member and spaced apart along the extension direction of the elastic member,
the elastic member is fixed between the first sheet and the second sheet only by friction between a surface of the elastic member and the first sheet and the second sheet in a space defined by the fused portion, the first sheet, and the second sheet located on both sides of the elastic member with the elastic member sandwiched therebetween;
when the stretchable sheet is viewed in cross section along a direction perpendicular to a direction in which the elastic member extends, at a position where the fused portion is formed, a length over which the first sheet is in contact with the elastic member is longer than a length over which the second sheet is in contact with the elastic member,
The present invention provides a stretchable sheet in which, when the stretchable sheet is viewed in cross section along a direction perpendicular to the extension direction of the elastic member at the position where the fused portion is formed, the second sheet has a thick film region throughout the entire area between the fused portions in which the fiber structure has completely lost its fiber shape due to melting and solidification of the constituent fibers throughout the thickness direction, and the thick film region has a shape that conforms to the shape of the elastic member.

The present invention also provides an absorbent article comprising an absorbent body and an exterior body located on the non-skin-facing side of the absorbent body, the exterior body including the stretchable sheet.

According to the present invention, there are provided a stretchable sheet and an absorbent article which have a small difference in stretch properties between when stretched and when contracted.

FIG. 1 is a partially cutaway plan view showing one embodiment of a stretch sheet of the present invention. FIG. 2 is an enlarged plan view showing a main part of the stretch sheet shown in FIG. FIG. 3 is an enlarged cross-sectional view taken along the Y direction, showing a main part of the stretchable sheet shown in FIG. FIG. 4 is a graph showing the relationship between stress and elongation for stretch sheets of the present invention and the prior art. FIG. 5 is a microscope image of an example of a thick film region according to the present invention. FIG. 6 is a perspective view showing the stretchable sheet shown in FIG. 1 in a relaxed state. FIG. 7 is a schematic diagram showing an apparatus that is preferably used for producing the stretch sheet of the present invention. FIG. 8 is an enlarged view of a main portion of the device shown in FIG. FIG. 9 is an enlarged view of the first contact portion shown in FIG.

The present invention will be described below based on preferred embodiments with reference to the drawings. FIG. 1 shows one embodiment of the stretchable sheet of the present invention. This figure is a partially cutaway plan view of the stretchable sheet 10 stretched to its maximum stretched state. The maximum stretched state refers to the state in which the first sheet 11 and the second sheet 12 constituting the stretchable sheet 10 are stretched until each elastic member described below is stretched to the designed dimensions (the dimensions when spread out flat with all the influence of the elastic members eliminated). Note that the first fused parts 15a and 15b described below are omitted in the broken portion shown in FIG. 1.

As described above, the stretchable sheet 10 has a first sheet 11 and a second sheet 12 arranged opposite the first sheet. A plurality of linear elastic members 13 such as rubber threads are arranged between the two sheets 11 and 12. The elastic members 13 extend in one direction without crossing each other. FIG. 1 shows the elastic members 13 extending parallel to each other. Each elastic member 13 is fixed in a stretched state between the two sheets 11 and 12. In the following description, the direction in which the elastic members 13 extend is also referred to as the X-direction. The direction perpendicular to the direction in which the elastic members 13 extend is also referred to as the Y-direction.

Each of the first sheet 11 and the second sheet 12 is made of a fiber sheet. The first sheet 11 may be a hydrophilic fiber sheet or a hydrophobic fiber sheet. The second sheet 12 may be a hydrophilic fiber sheet or a hydrophobic fiber sheet. A hydrophilic fiber sheet is one in which the contact angle of the constituent fibers with water taken from any point of the fiber sheet is less than 90 degrees. The contact angle of the fibers with water can be measured, for example, according to the method described in JP 2015-142721 A. From the viewpoint of facilitating the formation of the fused portion described later, when one or both of the first sheet 11 and the second sheet 12 are hydrophilic fiber sheets, it is preferable that they are hydrophilic nonwoven fabrics containing, as constituent fibers, fibers obtained by imparting hydrophilicity to synthetic fibers made of a heat-fusible resin. Examples of heat-fusible resins include polyethylene and polypropylene. The fibers constituting the fiber sheet may be core-sheath type composite fibers, etc., in which only the surface is made of a heat-fusible resin. A hydrophobic fiber sheet is one in which the contact angle between the constituent fibers of the fiber sheet and water taken from any point on the fiber sheet is 90 degrees or more. From the same viewpoint as above, when one or both of the first sheet 11 and the second sheet 12 are hydrophobic fiber sheets, it is preferable that the sheets contain synthetic fibers made of the above-mentioned heat-fusible resin as constituent fibers. The first sheet 11 and the second sheet 12 may be made of the same material or different materials.

As shown in FIG. 1, the first sheet 11 and the second sheet 12 are joined by a plurality of fusion parts. The sheets 11 and 12 are fused at the fusion parts. "Fusion" refers to the formation of molten parts in the sheets 11 and 12 by heat, and the molten parts are mixed together and then cooled to be integrally bonded. The stretchable sheet 10 of this embodiment has, as fusion parts, a pair of first fusion parts 15a, 15b located on both sides of the elastic member 13 with the elastic member 13 therebetween, and a plurality of second fusion parts 16a, 16b located between the pair of first fusion parts 15a, 15b in the Y direction. The fusion parts of the first fusion parts 15a, 15b and the second fusion parts 16a, 16b are formed at intervals along the direction in which the elastic member 13 extends, i.e., the X direction. Two second fused parts 16 are arranged side by side between a pair of first fused parts 15a, 15b in the Y direction. Each fused part 15a, 15b, 16a, 16b is spaced apart from one another and arranged in this order in a row along the Y direction. By arranging the fused parts in this way, pleats, which will be described later, can be formed on each surface of the stretch sheet 10.

The elastic member 13 is fixed between the first sheet 11 and the second sheet 12 only by friction between the first fused parts 15a and 15b located on both sides of the elastic member 13. Between the first fused parts 15a and 15b, a space is formed in the cross section along the Y direction, defined by the first fused parts 15a and 15b, the first sheet 11, and the second sheet 12. In this space, the elastic member 13 is fixed between the first sheet 11 and the second sheet 12 only by friction between the surface of the elastic member 13 and the first sheet 11 and the second sheet 12. That is, in the stretchable sheet 10, the elastic member 13 is not fixed to the first sheet 11 and the second sheet 12 by a joining means such as an adhesive or fusion. In the stretchable sheet 10, the elastic member 13 and the first sheet 11, and the elastic member 13 and the second sheet 12 are not fused to each other. As a result, the stretchable sheet 10 is formed while maintaining the good texture and breathability inherent to the first sheet 11 and the second sheet 12. In addition, the stretchable sheet 10 is highly stretchable.

As described above, the elastic member 13 is fixed to the first and second sheets 11 and 12 in the space along the Y direction between the pair of first fusion parts 15a and 15b by friction between the surface of the elastic member 13 and both sheets 11 and 12. In detail, as shown in Fig. 2, which is an enlarged view of the main part of Fig. 1, the first fusion part interval D, which is the interval between the side edge 151a on the elastic member 13 side of one first fusion part 15a and the side edge 151b on the elastic member 13 side of the other first fusion part 15b, is made narrower than the diameter d1 of the elastic member 13 in the maximum stretched state of the stretchable sheet 10, and the elastic member 13 is fixed between the first and second sheets 11 and 12 only by friction generated on the surface of the elastic member 13 in the space by the clamping pressure of the pair of first fusion parts 15a and 15b. In FIG. 2, the elastic member 13 appears to be joined to the pair of first fused portions 15a, 15b, but in reality, the elastic member 13 is not joined to the pair of first fused portions 15a, 15b.

In order to reliably fix the elastic member 13 in the space between the pair of first fused portions 15a, 15b only by friction between the surface of the elastic member 13 and the first and second sheets 11, 12, the first fused portion interval D is preferably such that the value of d2/D is 1.1 or more, more preferably 1.2 or more, and even more preferably 1.3 or more, where d2 (see FIG. 2) is the diameter of the elastic member 13 in the relaxed state of the stretchable sheet 10. The higher the value of d2/D, the higher the frictional force between the surface of the elastic member 13 and the first and second sheets 11, 12, which is preferable. The diameter d2 of the elastic member 13 in the relaxed state of the stretchable sheet 10 is the diameter of the elastic member 13 at the portion where the elastic member 13 is not clamped in the relaxed state of the stretchable sheet 10.

When the above d2 is expressed as fineness, from the viewpoint of ensuring the elasticity of the elastic sheet 10, the fineness is preferably 155 dtex or more, and more preferably 310 dtex or more. It is also preferably 1240 dtex or less, and more preferably 940 dtex or less. The fineness of the elastic member 13 is preferably 155 dtex or more and 1240 dtex or less, and even more preferably 310 dtex or more and 940 dtex or less.

3, when the stretchable sheet 10 is viewed in cross section along the direction perpendicular to the direction in which the elastic member 13 extends, i.e., along the Y direction in the figure, at the formation position of the fused portions 15a and 15b, the length over which the first sheet 11 contacts the elastic member 13 is longer than the length over which the second sheet 12 contacts the elastic member 13. The reason for this is that in the elastic member 13 viewed in cross section, the portion on the first sheet 11 side is raised outward in the thickness direction Z of the stretchable sheet 10 compared to the portion on the second sheet 12 side of the elastic member 13, and when the elastic member 13 is divided in half in the thickness direction Z in the cross section, the second sheet 12 side and the first sheet 11 side of the elastic member 13 have asymmetric shapes (see FIG. 3). In other words, in the cross section, the elastic member 13 has a substantially flat portion on the second sheet 12 side between the pair of fused portions 15a and 15b and a portion on the first sheet 11 side that is raised outward in the thickness direction. In addition, on the second sheet 12 side of the elastic member 13, the portion between the first fused portions 15a and 15b in a cross-sectional view along the Y direction is substantially flat compared to the portion other than the portion between the first fused portions 15a and 15b in the same cross-sectional view.

3, the stretchable sheet 10 has a thick film region 20 in which the fiber structure of the second sheet 12 is completely lost due to melting and solidification of the fiber structure in the entire thickness direction Z in the entire area between the fused portions 15a and 15b. In the thick film region 20, the resin constituting the fiber structure of the second sheet 12 is in a lump form to form a thick film. In the thick film region 20, all the fiber structure is melted and solidified, and the fiber structure is completely lost. Therefore, when the thick film region 20 is observed under a microscope, no fiber is observed in the thick film region 20. Although there may be some voids (closed voids or open voids) in the thick film region 20, the thick film region 20 is generally solid. In the thick film region 20, the fiber structure is melted and solidified, but the thick film region 20 and the elastic member 13 are not fused to each other. The stretchable sheet has the thick film region 20 only in the second sheet 12. The thick film region 20 is formed in the second sheet 12 located between the pair of first fused portions 15a, 15b in the Y direction, and faces the first sheet 11 with the elastic member 13 sandwiched therebetween. In the first sheet 11, the region overlapping with the elastic member 13 in the thickness direction Z and facing the thick film region 20 with the elastic member 13 sandwiched therebetween is a fibrous region 21 in which at least a part of the fiber of the constituent fibers is maintained. The fibrous region 21 is composed of the constituent fibers of the first sheet 11. The fibrous region 21 may be in a state in which the constituent fibers of the first sheet 11 maintain their fiber form throughout the entire region. Alternatively, the fibrous region 21 may have a portion where the constituent fibers of the first sheet 11 have lost their fiber form and are melted and solidified, and a portion where the fiber form of the constituent fibers is maintained. In the stretchable sheet 10 shown in FIG. 3, the first sheet 11 has a fibrous region 21.

In the cross-sectional view shown in FIG. 3, the surface of the second sheet 12 facing the elastic member 13 is in close contact with the approximately flat portion of the elastic member 13. As a result, at the formation position of the fused portions 15a and 15b, the surface of the second sheet 12 facing the elastic member 13 is along the approximately flat portion of the elastic member 13. Therefore, in the stretchable sheet of this embodiment, between the pair of first fused portions 15a and 15b, the surface on the second sheet side is approximately flat, while the surface on the first sheet side is raised outward in the thickness direction Z. That is, in this embodiment, the thick film region 20 has a shape that follows the shape of the elastic member 13. Specifically, the thick film region 20 is in close contact with the surface of the elastic member 13 that faces the thick film region 20, and has a shape that follows the shape of the surface.

In a cross-sectional view of the stretchable sheet 10 along the Y direction, when the thick film region 20 is viewed along the Y direction, the thickness of the thick film region 20 is constant. "Constant thickness" means that the difference between the maximum thickness and the minimum thickness of the thick film region 20 is 5 μm or less.
From the viewpoint of further improving the stretch characteristics of the stretchable sheet 10, which will be described later, the maximum thickness of the thick film region 20 is preferably 1 μm or more and 15 μm or less, and more preferably 3 μm or more and 13 μm or less.

The maximum thickness of the thick film region 20 is measured by the following method.
After freezing the stretchable sheet using liquid nitrogen or the like, a portion where the elastic member is fixed by a pair of first fusion parts is cut out from the center of the stretchable sheet in the stretchable direction of the elastic member. At this time, the elastic member is cut along a direction perpendicular to the stretchable direction, and this is used as a sample. As described above, the elastic member is fixed only by friction with the first sheet and the second sheet, and the elastic member is not fused to the first sheet and the second sheet, so that when the sample is cut out, the elastic member may come off from the sample. If the elastic member remains in the sample, the elastic member is removed from the sample. Next, the cross section of the sample is observed under magnification using a scanning electron microscope (for example, JSM-IT100, manufactured by JEOL Ltd.). The magnification during observation is set to 100 to 200 times so that the second sheet can be observed in the thickness direction of the sample, and both ends between the pair of first fusion parts in the stretchable direction of the elastic member can be observed. When the cross section of the sample is observed under magnification, a thick region is observed between the pair of first fused portions of the second sheet as a region in which the fibrous form has been lost. The maximum thickness of the thick region is measured using image data of the cross section of the sample.

In the method for measuring the maximum thickness of the thick film region, the cut surface of the sample is observed in a state similar to the microscope image shown in FIG. 5. FIG. 5 is a microscope image of the formation positions of fused parts 15a and 15b observed from the thick film region side. The cavity in FIG. 5 is the part where the elastic member was placed. The thick film region is a film-like part that is continuous with the first fused part, and the fibrous form of the sheet has been lost.

The stretchable sheet 10 having the above configuration has better stretch characteristics than the stretchable sheet described in Patent Document 1. The reason is as follows. As described above, the stretchable sheet 10 has a thick film region 20 and a fibrous region 21 facing it at the formation position of the fused parts 15a and 15b. The thick film region 20 is a solid region formed by melting and solidifying the fibers constituting the second sheet 12, so it has high rigidity. The high rigidity of the thick film region 20, coupled with the fact that the thick film region 20 is not fused to the elastic member 13, means that the thick film region 20 is less likely to deform. Therefore, when the stretchable sheet 10 is stretched, the diameter of the elastic member 13 gradually changes to become thinner due to the stretching, but the thick film region 20 does not follow the change and maintains its original shape. As a result, the contact area between the elastic member 13 and the thick film region 20 gradually decreases. Due to this, the frictional force of the elastic member 13 due to the thick film region 20 gradually decreases, and the inherent elasticity of the elastic member 13 becomes apparent. As a result, the stress when the elastic sheet 10 is stretched approaches the inherent elongation stress of the elastic member 13. In contrast, in the elastic sheet described in Patent Document 1, the region corresponding to the thick film region 20 is made of fibers. In other words, this region is an area that can be easily deformed (in this sense, this region will be referred to as the "easily deformable region" below), so when the elastic sheet is stretched, the easily deformable region deforms in accordance with the thinning elastic member. In other words, even if the diameter of the elastic member changes, there is no significant change in the adhesion between the elastic member and the easily deformable region. In short, even if the elastic sheet described in Patent Document 1 is stretched, there is no significant change in the frictional force between the elastic member and the easily deformable region. As a result, in the elastic sheet described in Patent Document 1, the inherent elasticity of the elastic member is impaired due to the frictional force with the easily deformable region. This means that the stress when the stretchable sheet described in Patent Document 1 is stretched is higher than the inherent elongation stress of the elastic member. Thus, when compared under the same conditions, the stretchable sheet of the present invention has the advantage that it can be stretched with a lower stress than the stretchable sheet described in Patent Document 1, as shown in FIG. 4. On the other hand, as shown in FIG. 4, there is essentially no difference in the characteristics when contracted from an extended state between the stretchable sheet of the present invention and the stretchable sheet described in Patent Document 1. Therefore, the stretchable sheet of the present invention has a smaller difference in stretch characteristics between the extended state and the contracted state than the stretchable sheet of Patent Document 1. In other words, the stretchable sheet of the present invention has a smaller hysteresis in the stress-elongation curve when extended and when contracted.

Regarding the hysteresis of the stress-elongation curve, in the present invention, the stress-elongation curve of the elastic sheet is obtained by the following method. First, a sheet piece 600 mm long and 50 mm wide is cut out from the elastic sheet along the elastic member. The cut out sheet piece is rolled into a ring shape with an inner diameter of 550 mm, and the overlapping ends are fixed at two points with a predetermined distance in the width direction using a stapler to prepare a ring-shaped test piece. The stapler core is fixed so that it is long in the longitudinal direction of the sheet piece. Next, the ring-shaped test piece is stretched to twice its original length using a tensile tester (for example, the tensile tester "Autograph AG-X" manufactured by Shimadzu Corporation) under conditions of a chuck distance of 100 mm and a speed of 300 mm/min, and then contracted at a speed of 300 mm/min to obtain a graph of the stress-elongation curve. In the obtained stress-elongation ratio relationship, if the stress at 1.8 times the stretching in the second cycle is A and the stress at 1.8 times the shrinking in the second cycle is B, the value of B/A is preferably 0.83 or more, more preferably 0.84 or more. When the stretchable sheet is used as the exterior body of an absorbent article such as a diaper, A is an indicator of the ease of spreading the absorbent article, and B is an indicator of the fit of the absorbent article. The closer the value of B/A is to 1, that is, the closer the stresses at the time of stretching and at the time of shrinking are to each other, the more preferable it is, but from the viewpoint of further reducing the feeling of tightness when worn, the value of B/A is preferably 0.90 or less, more preferably 0.88 or less.

In addition, as described above, in the stretchable sheet 10, when the stretchable sheet is viewed in cross section along the Y direction at the formation position of the first fused portions 15a and 15b, the length over which the first sheet 11 contacts the elastic member 13 is longer than the length over which the second sheet 12 contacts the elastic member 13, and the thick film region 20 follows the shape of the elastic member 13. Therefore, when the stretchable sheet 10 is used as, for example, the exterior body and the second sheet 12 is arranged so that it faces the skin of the wearer, the thick film region 20 formed on the second sheet 12 can reduce the degree to which the elastic member 13 presses against the skin of the wearer. In other words, there is an advantage in that it is less likely to cause discomfort when wearing the absorbent article. Conversely, if the stretchable sheet is placed in the absorbent article so that the second sheet 12 faces the clothing, most of the cross section of the elastic member 13 will be on the wearer's skin side, which has the advantage that the stretchable sheet 10 will be in gentle contact with the wearer's skin.

The stretchable sheet 10 can be suitably used as an exterior body that forms the outer surface of an absorbent article. As described above, the stretchable sheet 10 has good stretching properties, so an absorbent article equipped with the stretchable sheet 10 can easily spread the stretchable sheet 10 with little force. In other words, it is easy to put on and has a good fit to the wearer's body.

In this embodiment, the first and second sheets 11, 12 are folded at the second fused portion 16 and protrude away from each other along the thickness direction as shown in FIG. 6. That is, in the stretchable sheet 10, the first sheet 11 and the second sheet 12 each have a protrusion 17 that protrudes away from each other along the thickness direction Z. The protrusion 17 is a portion that forms pleats in the stretchable sheet 10, which will be described later, and is a portion that is different from the portion of the first sheet 11 and the second sheet 12 that follows the shape of the elastic member 13 at the position where the first sheet 11 and the second sheet 12 overlap the elastic member 13.

As shown in FIG. 6, the convex portions 17 extend continuously along the Y direction. The convex portions 17 form multiple folds on each side of the stretchable sheet 10. The folds give the stretchable sheet 10 in the state shown in FIG. 6 a soft feel and an excellent appearance.

From the viewpoint of further improving the stretch characteristics of the stretchable sheet 10, when the distance between two adjacent elastic members 13 along the Y direction is Le (see FIG. 1), the ratio of the length L16 (see FIG. 1) of the second fused portion 16 along the Y direction to the distance Le, L16/Le, is preferably 0.25 or more, more preferably 0.50 or more, and even more preferably 0.70 or more. From the viewpoint of ensuring the bonding strength, the closer the value of L16/Le is to 1, the more preferable it is.

From the same viewpoint as above, it is preferable that the distance Le between two adjacent elastic members 13 along the Y direction is 1 mm or more. The value of Le is preferably 10 mm or less, more preferably 8 mm or less, and even more preferably 6 mm or less. The value of Le is preferably 1 mm or more and 10 mm or less, more preferably 1 mm or more and 8 mm or less, and even more preferably 1 mm or more and 6 mm or less.

From the same viewpoint as above, when the distance between two adjacent fused portions along the X direction is Lf (see FIG. 1), the value of Lf is preferably 6 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less. There is no particular restriction on the lower limit of Lf, and the smaller the value, the more the stretch properties of the stretchable sheet 10 are improved, so it is preferable, but the effect of the present invention is sufficiently achieved if Lf is narrow, about 1 mm. Therefore, the value of Lf is preferably 1 mm or more and 6 mm or less, and more preferably 1 mm or more and 5 mm or less.

Furthermore, from the same viewpoint as above, the length in the X direction, which is the width of the first fused portion 15 and the second fused portion 16, is preferably 3 mm or less, more preferably 2 mm or less, and even more preferably 1 mm or less, independently of each other. There is no particular limit to the lower limit of the width, and the smaller the better, but the effect of the present invention is sufficiently achieved if the width is narrow, about 0.2 mm. Therefore, the width is preferably 0.2 mm or more and 3 mm or less, more preferably 0.2 mm or more and 2 mm or less, and even more preferably 0.2 mm or more and 1 mm or less.

The materials constituting the stretchable sheet 10 will be described in detail. For the first and second sheets 11 and 12, for example, nonwoven fabrics manufactured by various manufacturing methods such as air-through nonwoven fabric, heat-rolled nonwoven fabric, spunlace nonwoven fabric, spunbonded nonwoven fabric, meltblown nonwoven fabric, etc., and laminates formed by laminating two or more of these can be used. From the viewpoint of forming soft pleats that are beautiful to the eye and have a good feel, it is preferable that the fiber sheet used as both sheets or one of the sheets is air-through nonwoven fabric, heat-rolled nonwoven fabric, spunlace nonwoven fabric, spunbonded nonwoven fabric, meltblown nonwoven fabric, etc. In particular, it is preferable to use a laminated nonwoven fabric obtained by laminating a spunbonded nonwoven fabric layer and a meltblown nonwoven fabric layer as the second sheet, since the thick film region 20 can be easily formed. Examples of laminated nonwoven fabrics consisting of a spunbond nonwoven fabric layer (S) and a meltblown nonwoven fabric layer (M) include SM nonwoven fabrics and SMS nonwoven fabrics.

As described above, nonwoven fabric is preferably used as the first and second sheets 11, 12. The basis weight of the nonwoven fabric is preferably 5 g/ ^m2 or more and 50 g/ ^m2 or less, particularly preferably 8 g/ ^m2 or more and ³⁰ g/m2 or less. The buckling strength of the nonwoven fabric having such a basis weight is preferably 50 cN or less in the direction crossing the machine direction (CD), particularly preferably 30 cN or less, and preferably 70 cN or less and particularly preferably 50 cN or less in the machine direction (MD). The use of a soft sheet can enhance the formability of the folds. The buckling strength is measured by the following method.

Buckling strength test method:
A rectangular test piece is taken, 150 mm in the machine direction (MD) and 30 mm in the direction perpendicular to the machine direction (CD). Five test pieces are cut out from the sheet to be measured. Using this test piece, a cylinder with a diameter of 45 mm is made, and the upper and lower ends of the overlapping parts are stapled together, and this is used as the measurement sample. The measurement sample is compressed to 20 mm in maximum strength using the compression test mode of the Tensilon universal testing device under the measurement conditions of a compression speed of 10 mm/min and a measurement distance of 20 mm. The measurement environment is 20°C and 65% RH. In this measurement, the average value of the maximum strength of each measurement sample is calculated, and this is used as the buckling strength in the perpendicular direction (CD).
The buckling strength in the machine direction (MD) is measured in the same manner as above, except that a rectangular test specimen is taken, 150 mm in the cross-machine direction (CD) and 30 mm in the machine direction (MD).

The first and second sheets 11, 12 are not limited to being two separate sheets, but may be formed by folding a single sheet to form two opposing surfaces, with one sheet constituting one surface and the other sheet constituting the other surface. When the first and second sheets 11, 12 are each formed from a single sheet, it is preferable that the single sheet is a hydrophilic fiber sheet.

The elastic member 13 can be made from any of a variety of well-known elastic materials used in absorbent articles such as disposable diapers and sanitary napkins, without any particular restrictions. For example, the material can be synthetic rubber such as styrene-butadiene, butadiene, isoprene, neoprene, natural rubber, EVA, elastic polyolefin, polyurethane, etc., and the shape can be a thread or string (such as flat rubber) with a rectangular, square, circular, polygonal, etc. cross section, or a multifilament type thread.

Next, a preferred method for manufacturing the stretchable sheet 10 shown in Figures 1 to 6 will be described with reference to Figure 7. This figure shows an apparatus suitable for use in manufacturing the stretchable sheet 10. The apparatus 100 shown in this figure includes an ultrasonic fusion unit 30. The ultrasonic fusion unit 30 includes an ultrasonically vibrating horn 31 and a receiving roll 32 arranged opposite the tip surface of the horn 31. The horn 31 is made of metal such as an aluminum alloy or titanium alloy, and is designed to resonate in the frequency band to be used. The horn 31 is connected to a booster (not shown), and the ultrasonic vibration transmitted from the booster to the horn 31 is amplified or attenuated inside the horn 31 and applied to the object to be welded.

The receiving roll 32 is designed to be able to adjust its temperature, and as a result, the first sheet 11 and the second sheet 12 in contact with the receiving roll 32 can be heated. That is, the first sheet 11 and the second sheet 12 can be heated by being wrapped around the receiving roll 32. The receiving roll 32 can adjust its temperature by, for example, equipping the inside of the rotating shaft side with a heater for heating the receiving roll 32 and a temperature sensor for measuring the temperature of the receiving roll 32. A horn 31, which will be described later, is pressed against the second sheet 12, and ultrasonic vibrations are applied directly to it.

8 shows an enlarged view of the main part of the ultrasonic fusion unit 30 in FIG. 7. The ultrasonic fusion unit 30 includes a receiving roll 32 having contact portions 40 and 41 formed on the peripheral surface thereof, and a horn 31 that can contact the contact portions. The Y direction shown in FIG. 8 is the width direction (axial direction) of the receiving roll 32, which coincides with the Y direction of the elastic sheet 10 to be manufactured. As shown in the figure, a pair of convex portions is arranged along the axial direction on the peripheral surface of the receiving roll 32 in the ultrasonic fusion unit 30. A concave portion 42 is formed between the pair of convex portions. The pair of convex portions is collectively referred to as the first contact portion 40. The receiving roll 32 has the first contact portion 40 intermittently provided along the rotation direction R of the roll (see FIG. 7). In addition, a plurality of second contact portions 41 are intermittently provided on the peripheral surface of the receiving roll 32 along the rotation direction R of the receiving roll 32. The first contact portion 40 and the second contact portion 41 form a convex portion protruding toward the horn 31 on the peripheral surface of the receiving roll. That is, the first contact portion 40 and the second contact portion 41 are located on the side closer to the horn 31. In the receiving roll 32, the first contact portions 40 are located on the same line in the rotation direction R, and the second contact portions 41 are located on the same line in the rotation direction R. In the receiving roll 32 in this embodiment, the first contact portion 40 and the two second contact portions 41 are arranged alternately in the width direction. On the other hand, in the horn 31, the surface having the portion that contacts the first contact portion 40 and the second contact portion 41 is a flat surface without unevenness.

8 and 9, the first contact portion 40 has a recess 42 at approximately the center in the Y direction, i.e., the roll width direction. The recess 42 has a rectangular shape in cross section along the width direction of the receiving roll 32. The recess 42 has a volume that can accommodate at least a portion of the elastic member 13 in a stretched state. In other words, the recess 42 has a volume that allows the elastic member 13 to partially protrude from the upper surface of the first contact portion 40 when the elastic member 13 is accommodated in the recess 42. The opening width of the recess 42 along the Y direction roughly corresponds to the first fusion interval D (see FIG. 2) in the target stretchable sheet 10.

In this manufacturing method, a first sheet 11, a second sheet 12, and a plurality of elastic members 13 arranged in a stretched state between the two sheets 11, 12 are used. Returning to FIG. 7, the first sheet 11 unwound from the original roll 11a of the first sheet 11 is transported while being wound around the circumferential surface of the receiving roll 32. With the first sheet 11 wound around the circumferential surface of the receiving roll 32, a plurality of elastic members 13 each unwound from its roll 13a are arranged in a stretched state on the surface of the first sheet 11. The elastic members 13 are transported while being partially accommodated in the recess 42 of the first contact portion 40 provided on the circumferential surface of the receiving roll 32. At this point, the first sheet 11 is already accommodated in the recess 42 (see FIG. 8).

When partially accommodated in the recess 42 in a stretched state, the degree of stretch of the elastic member 13 is greater than the degree of stretch of the elastic member 13 in the maximum stretched state of the stretchable sheet 10, and the diameter of the elastic member 13 is smaller than the opening width along the Y direction of the recess 42. In this way, in the resulting stretchable sheet 10, the clamping pressure by the pair of first fused portions 15a, 15b can be increased, and sufficient frictional force can be ensured between the elastic member 13 and the first and second sheets 11 and 2.

After the elastic member 13 is accommodated in the recess 42, the second sheet 12 unwound from the original roll 12a of the second sheet 12 is supplied to the circumferential surface of the receiving roll 32. This prepares a laminate in which the stretched elastic member 13 is arranged between the first sheet 11 and the second sheet 12. That is, the laminate is supplied so that the elastic member 13 in the laminate passes through the recess 42 under a state in which the convex parts 40 and 41 of the receiving roll 32 face the joint parts of the sheet members. In the laminate, the first sheet 11 and the second sheet 12 are preheated by being wound around the receiving roll 32 as described above. Ultrasonic vibration is applied to the laminate by the horn 31 (see Figures 8 and 9). At this time, the laminate is pressurized by the horn 31, and a substantially flat part of the elastic member 13 is formed on the second sheet 12 side, and the second sheet 12 is in close contact with the elastic member 13 and is in a state along the substantially flat part.

The ultrasonic fusion unit 30 fuses the first sheet 11 and the second sheet 12 in the laminate at positions on both sides of the elastic member 13 and at multiple positions spaced apart along the Y direction. This forms the pair of first fusion parts 15a, 15b and the second fusion part 16 described above. As shown in FIG. 8, on the peripheral surface of the receiving roll 32, the first abutment part 40 and the second abutment part 41 protrude more than other parts and are located closer to the horn 31, so that the first sheet 11 and the second sheet 12 located on the first abutment part 40 and the second abutment part 41 are fused to each other, forming the first fusion part 15 and the second fusion part 16 that join these sheets. At this time, the elastic member 13 is partially contained in the recess 42, and the elastic member 13 is not fused to either the first sheet 11 or the second sheet 12, and is maintained in a non-bonded state. By the fusion of the ultrasonic fusion parts 30, a thick film region 20 is formed between the pair of first fusion parts 15a, 15b of the second sheet 12, and a fibrous region 21 is formed between the pair of first fusion parts 15a, 15b of the first sheet 11. By applying ultrasonic waves in this manner, a stretchable sheet 10 in the form shown in FIG. 1 is obtained.

In the obtained stretchable sheet 10, when the stretched state of the elastic member 13 is released, the length of the elastic member 13 is shortened and the diameter of the elastic member 13 is increased. As shown in FIG. 2, the elastic member 13 with an increased diameter is equal to or larger than the first fusion interval D, which is the interval between the two first fusion portions 15a and 15b, and preferably exceeds the first fusion interval D. As a result, the elastic member 13 is sandwiched between the two first fusion portions 15a and 15b and is fixed only by the friction between the first sheet 11 and the second sheet 12. In addition, the fusion causes the portion of the second sheet 12 where the constituent fibers are melted between the pair of first fusion portions 15a and 15b to solidify due to a decrease in temperature. As a result, the shape of the second sheet 12 side of the elastic member 13 with an increased diameter and the shape of the second sheet 12 are maintained approximately flat between the pair of first fusion portions 15a and 15b. The degree of stretching of the elastic member 13 during manufacturing of the stretchable sheet 10 and the opening width of the recess 42 along the Y direction can be set appropriately according to the desired stretch state of the stretchable sheet 10.

When the first and second sheets 11, 12 and the elastic member 13 constituting the stretchable sheet 10 are housed in the recesses 42, the degree of stretch of the elastic member 13 is selected so that the stretchable sheet 10 has the desired extensibility (stretch rate) and desired pleats. In this manufacturing method, the degree of stretch of the elastic member 13 can be adjusted by, for example, appropriately adjusting the depth and width of the recesses 42 (first fused portion spacing D).
From the viewpoint of easily forming the thick film region 20, in this manufacturing method, it is preferable to adjust the depth and width of the recess 42 so that no gap exists between the first sheet 11, the elastic member 13, and the second sheet 12 in the laminate when the laminate is supplied to the ultrasonic fusion unit 30, which is a fusion device. From the same viewpoint as above, the dimensions of the recess 42 are preferably within the following range. The width c (see FIG. 9) of the recess 42 is preferably more than 1.0 times and not more than 2.0 times the diameter a (see FIG. 9) of the elastic member 13 in the stretched state, assuming that the elastic member 13 fits into the recess 42 together with the first sheet 11. The diameter a (see FIG. 10) of the elastic member 13 in the stretched state is preferably 1.3 times or more and not more than 2.0 times, more preferably 1.4 times or more and not more than 1.9 times, and even more preferably 1.5 times or more and not more than 1.8 times the depth b (see FIG. 9) of the recess 42.

From the viewpoint of easily forming the thick film region 20, the linear pressure of the horn 31, i.e., the pressure applied to the laminate by pressing the horn 31 against the laminate, is preferably 4 N/mm or more, more preferably 4.2 N/mm or more, and is also preferably 5 N/mm or less, more preferably 4.8 N/mm or less, and is preferably 4 N/mm or more and 5 N/mm or less, more preferably 4.2 N/mm or more and 4.8 N/mm or less.

As described above, in this manufacturing method, ultrasonic vibration is applied to the second sheet 12 after preheating the second sheet 12. The inventors have found that by preheating the second sheet 12 before applying ultrasonic vibration to the second sheet 12, the thick film region 20 formed by ultrasonic vibration and the elastic member 13 are less likely to fuse. This is thought to be because the second sheet obtains thermal energy by preheating, and therefore weaker ultrasonic vibrations can seal the elastic member 13 to a degree that allows it to be fixed from both sides. Furthermore, because the ultrasonic vibrations are weak, the frictional heat between the fibers caused by the ultrasonic vibrations generated inside the second sheet 12 is higher than the frictional heat generated at the interface between the second sheet 12 and the elastic member 13. On the other hand, when ultrasonic vibrations are applied to the second sheet without preheating, the second sheet and the elastic member overlapping the second sheet are fused between the pair of fusion parts 15a and 15b. From the viewpoint of further suppressing fusion between the second sheet 12 and the elastic member 13, the preheating temperature of the second sheet 12 is preferably lower than the melting point of the constituent fibers of the second sheet 12. From the same viewpoint as above, the preheating temperature of the second sheet 12 is preferably 90°C to 135°C lower than the melting point of the constituent fibers of the second sheet 12, more preferably 95°C to 130°C lower, and even more preferably 100°C to 125°C lower. For example, when the constituent fibers of the second sheet 12 are single fibers made of polypropylene, particularly a homopolymer of propylene (e.g., melting point 163°C), the preheating temperature of the second sheet 12 is preferably within the range of 40°C (-123°C lower than the melting point) to 60°C (-103°C lower than the melting point). From the viewpoint of more easily preheating the second sheet 12, the temperature of the receiving roll 32 is preferably set within the range of 90°C to 135°C lower than the melting point of the constituent fibers of the second sheet 12. The melting point of the constituent fibers of the second sheet 12 means the melting point of the resin with the lowest melting point among the constituent resins of the constituent fibers in the second sheet 12. The melting point of the constituent fibers can be measured by thermal analysis using a differential scanning calorimeter (e.g., DSC6200 manufactured by Seiko Instruments Inc.). Specifically, thermal analysis of fiber samples (1 mg) finely cut from any 10 locations of the web or nonwoven fabric is performed at a heating rate of 10°C/min, and the melting peak temperature of the measured fiber component is taken as the melting point of the constituent fibers. When there are multiple melting peak temperatures, the lowest melting peak temperature among them is taken as the melting point of the constituent fibers.

In the manufacturing method of the stretchable sheet 10, ultrasonic vibration is preferably used. On the other hand, when heat sealing is used to fuse the first sheet 11 and the second sheet 12, the elastic member 13 and the second sheet 12 are fused, and the fixation of the elastic member 13 between the first sheet 11 and the second sheet 12 may not be realized only by the friction of the two sheets 11 and 12. In addition, when heat sealing is used, the elastic member 13 is deformed by melting, so it is difficult to form a thick film region 20 that conforms to the shape of the elastic member 13. For example, in a manufacturing method using heat sealing, when the diameter of the elastic member 13 in the stretched state is a and the depth of the recess 42 is b, if the relationship between a and b is a>b, the second sheet 12 and the elastic member 13 are fused between a pair of first fused portions 15a and 15b. Furthermore, in a manufacturing method using heat sealing, if the magnitude relationship between a and b is b<a, when the pair of first fused portions 15a, 15b is viewed in cross section along the Y direction, the second sheet between the pair of first fused portions 15a, 15b will be linear along the Y direction and will not be shaped along the elastic member 13.

The stretchable sheet 10 can be used as a constituent material for absorbent articles such as disposable diapers and sanitary napkins, and is particularly preferably used for forming stretchable parts of absorbent articles. Absorbent articles are primarily used to absorb and retain body fluids such as urine and menstrual blood excreted from the body. Absorbent articles include, but are not limited to, disposable diapers, sanitary napkins, incontinence pads, panty liners, and the like, and broadly include articles used to absorb fluids excreted from the human body. Examples of absorbent articles include those that have an absorbent body having a top sheet, a back sheet, and a liquid-retaining absorbent interposed between the two sheets, and an exterior body located on the non-skin-facing side of the absorbent body. As described above, the stretchable sheet of the present invention is preferably used for the exterior body. The absorbent article may further have various members according to its specific use. Such members are known to those skilled in the art.

Although the present invention has been described based on the preferred embodiment, the present invention is not limited to the above embodiment. For example, in the above embodiment, the pair of first fused parts 15a, 15b and the second fused part 16 are intermittently provided on the same straight line in the Y direction, but these fused parts 15a, 15b, 16 may be continuously provided on the same straight line in the Y direction.
In the above-described embodiment, the first fused portion 15 and the second fused portion 16 have a rectangular shape. However, instead of this, for example, an oval, a circle, a diamond, or other shape may be adopted.

In addition, in the above embodiment, the stretchable sheet 10 has multiple elastic members 13, but the stretchable sheet 10 may have only one elastic member 13.

In relation to the above-mentioned embodiment, the present invention further discloses the following stretchable sheet, an absorbent article including the same, and a method for manufacturing the stretchable sheet.

＜1＞
A stretchable sheet comprising a first sheet made of a fiber sheet, a second sheet made of a fiber sheet disposed opposite the first sheet, and an elastic member disposed in a stretched state between the first and second sheets and extending in one direction, the stretchable sheet having stretchability along the extending direction of the elastic member,
the first sheet and the second sheet are joined by a plurality of fused portions located on both sides of the elastic member and spaced apart along the extension direction of the elastic member,
the elastic member is fixed between the first sheet and the second sheet only by friction between a surface of the elastic member and the first sheet and the second sheet in a space defined by the fused portion, the first sheet, and the second sheet located on both sides of the elastic member with the elastic member sandwiched therebetween;
when the stretchable sheet is viewed in cross section along a direction perpendicular to a direction in which the elastic member extends, at a position where the fused portion is formed, a length over which the first sheet is in contact with the elastic member is longer than a length over which the second sheet is in contact with the elastic member,
A stretchable sheet, wherein when the stretchable sheet is viewed in cross section along a direction perpendicular to the extension direction of the elastic member at the position where the fused portion is formed, the second sheet has a thick film region throughout the entire area between the fused portions in which the fiber form has been completely lost due to melting and solidification of the constituent fibers throughout the thickness direction, and the thick film region has a shape that conforms to the shape of the elastic member.

＜2＞
When the stretchable sheet is viewed in cross section along a direction perpendicular to the extension direction of the elastic member at a position where the fused portion is formed, a portion of the elastic member on the first sheet side protrudes outward in the thickness direction of the stretchable sheet compared to a portion of the elastic member on the second sheet side,
The stretchable sheet according to <1> above, wherein when the elastic member is divided into two equal parts in the thickness direction in the cross-sectional view, the second sheet side and the first sheet side of the elastic member have an asymmetric shape.
＜3＞
The stretch sheet described in <2> above, in a cross-sectional view along a direction perpendicular to the extension direction of the elastic member, the second sheet side of the elastic member has a portion between the fused portions located on both sides of the elastic member that is approximately flat compared to the portion other than between the fused portions.
＜4＞
The stretchable sheet according to <2> or <3>, wherein, between the fused portions, the surface on the second sheet side is substantially flat, while the surface on the first sheet side is raised outward in the thickness direction.
＜5＞
The thick film region is in close contact with a surface of the elastic member that faces the thick film region, and has a shape that follows the shape of the surface. The stretchable sheet according to any one of <1> to <4>.
＜6＞
The stretchable sheet according to any one of <1> to <5>, wherein when the stretchable sheet is viewed in cross section along a direction perpendicular to the extension direction of the elastic member at the position where the fused portion is formed, the surface of the second sheet facing the elastic member is in close contact with the elastic member.
＜７＞
The stretchable sheet according to any one of <1> to <6>, wherein the thick film region is provided only in the second sheet.
＜8＞
The stretchable sheet according to any one of <1> to <7>, wherein the thick film region and the elastic member are not fused to each other.
＜9＞
The stretchable sheet according to any one of <1> to <8>, wherein, in a cross-sectional view of the stretchable sheet along the perpendicular direction, when the thick film region is viewed along the perpendicular direction, the difference between the maximum thickness and the minimum thickness in the thick film region is 5 μm or less.
＜10＞
The stretchable sheet according to any one of <1> to <9>, wherein the maximum thickness of the thick film region is preferably 1 μm or more and 15 μm or less, more preferably 3 μm or more and 13 μm or less.

<11>
The stretch sheet according to any one of <1> to <10> above, wherein, for the fused portions located on both sides of the elastic member, a distance between a side edge on the elastic member side of one fused portion and a side edge on the elastic member side of the other fused portion is D, and a diameter of the elastic member in a relaxed state of the stretch sheet is d2, the value of d2/D is 1.1 or more, preferably 1.2 or more, and more preferably 1.3 or more.
＜12＞
The stretch sheet according to any one of <1> to <11>, wherein the fineness of the elastic member in the relaxed state of the stretch sheet is 155 dtex or more and 1240 dtex or less, preferably 310 dtex or more and 940 dtex or less.
＜13＞
The stretchable sheet according to any one of <1> to <12>, wherein the distance Lf between adjacent fused portions in the extension direction of the elastic member is 1 mm or more and 6 mm or less.
＜14＞
The stretchable sheet according to any one of <1> to <12>, wherein the distance Lf between adjacent fused portions in the extension direction of the elastic member is 1 mm or more and 5 mm or less.
＜15＞
The stretchable sheet according to any one of <1> to <14>, wherein the fused portion has a length along the extension direction of the elastic member of 0.2 mm or more and 3 mm or less.
＜16＞
The stretch sheet according to any one of <1> to <15>, wherein the fused portion has a length along the extension direction of the elastic member of 0.2 mm or more and 2 mm or less, preferably 0.2 mm or more and 1 mm or less.
＜１７＞
The stretch sheet according to any one of <1> to <16>, wherein other fused portions joining the first sheet and the second sheet are intermittently disposed between the fused portions adjacent to each other in a direction perpendicular to the extension direction of the elastic members, between adjacent elastic members.
＜18＞
The stretch sheet according to <17>, wherein the other fused portion has a length along the extension direction of the elastic member of 0.2 mm or more and 3 mm or less, preferably 0.2 mm or more and 2 mm or less, and more preferably 0.2 mm or more and 1 mm or less.
＜19＞
The stretch sheet according to <17> or <18>, wherein the value of L16/Le is 0.25 or more, preferably 0.50 or more, and more preferably 0.70 or more, where Le is the distance between adjacent elastic members, and L16 is the length of the other fused portion along the orthogonal direction.
＜20＞
The stretch sheet according to any one of <17> to <19>, wherein the first sheet and the second sheet are each formed with a convex portion that protrudes away from each other along the thickness direction, with the other fused portion serving as a folding starting point, the convex portion extends continuously along the orthogonal direction, and a plurality of folds are formed by the convex portion.

＜21＞
The stretchable sheet according to <20>, wherein the convex portion is a portion different from a portion of the first sheet and the second sheet that conforms to the shape of the elastic member at a position where the first sheet and the second sheet overlap the elastic member.
＜22＞
The stretch sheet according to any one of <1> to <21>, wherein the interval between adjacent elastic members is 1 mm or more and 10 mm or less.
＜23＞
The stretch sheet according to any one of <1> to <22>, wherein the distance Le between adjacent elastic members is 1 mm or more and 10 mm or less, preferably 1 mm or more and 8 mm or less, and more preferably 1 mm or more and 6 mm or less.
＜24＞
The stretchable sheet according to any one of <1> to <23>, wherein the second sheet is a laminated nonwoven fabric in which a spunbonded nonwoven fabric layer and a meltblown nonwoven fabric layer are laminated.
＜25＞
A nonwoven fabric is used as the first sheet and the second sheet,
The stretch sheet according to any one of <1> to <24> above, wherein the nonwoven fabric has a basis weight of 5 g/ ^m2 or more and 50 g/ ^m2 or less, preferably 8 g/ ^m2 or more and 30 g/ ^m2 or less.
＜26＞
The stretch sheet according to <25>, wherein the buckling strength of the nonwoven fabric is 50 cN or less, preferably 30 cN or less, in a direction perpendicular to the machine direction, and 70 cN or less, preferably 50 cN or less, in the machine direction.
＜27＞
The stretch sheet according to any one of <1> to <26> above, wherein in the stress-elongation ratio relationship obtained by stretching the sheet to twice its original size under conditions of a chuck distance of 100 mm and a speed of 300 mm/min, and then shrinking the sheet at a speed of 300 mm/min, the value of B/A is 0.83 or more and 0.90 or less, where A is the stress at 1.8 times the original size during the second cycle of elongation, and B is the stress at 1.8 times the original size during the second cycle of shrinkage.
＜28＞
The stretch sheet according to <27>, wherein the value of B/A is 0.84 or more and 0.88 or less.
＜29＞
The stretchable sheet according to any one of <1> to <28>, wherein in the first sheet, a region that overlaps with the elastic member in the thickness direction and faces the thick film region across the elastic member is a fibrous region in which the fiber form of at least a portion of the constituent fibers is maintained.
＜30＞
The stretchable sheet according to <29>, wherein the fibrous region is in a state in which the constituent fibers of the first sheet maintain their fibrous form throughout the entire region.

＜31＞
The stretch sheet described in <29>, wherein the fibrous region has a portion where the constituent fibers of the first sheet have lost their fibrous form and are melted and solidified, and a portion where the fibrous form of the constituent fibers is maintained.
＜32＞
The stretchable sheet according to any one of <1> to <31>, wherein the first sheet and the second sheet in the stretchable sheet are two separate sheets.
＜33＞
The stretchable sheet according to any one of <1> to <31>, wherein the first sheet and the second sheet in the stretchable sheet are formed by folding a single sheet to form two opposing surfaces, the portion constituting one surface being the first sheet and the portion constituting the other surface being the second sheet.
＜34＞
An absorbent article comprising an absorbent body and an exterior body located on a non-skin facing side of the absorbent body,
An absorbent article, wherein the exterior body includes the stretchable sheet according to any one of <1> to <33>.
＜35＞
The absorbent article according to <34> above, wherein the second sheet in the stretchable sheet is arranged to face the skin of the wearer.
＜36＞
The absorbent article according to <34> above, wherein the second sheet in the stretchable sheet is arranged to face the clothing side.

REFERENCE SIGNS LIST 10 Stretchable sheet 11 First sheet 12 Second sheet 13 Elastic members 15a, 15b First fused portion 16 Second fused portion 17 Convex portion 20 Thick film region 21 Fibrous region

Claims (8)

A stretchable sheet comprising a first sheet made of a fiber sheet, a second sheet made of a fiber sheet disposed opposite the first sheet, and an elastic member disposed in a stretched state between the first and second sheets and extending in one direction, the stretchable sheet having stretchability along the extending direction of the elastic member,
the first sheet and the second sheet are joined by a plurality of fused portions located on both sides of the elastic member and spaced apart along the extension direction of the elastic member,
the plurality of fused portions include a pair of first fused portions located on both sides of the elastic member with the elastic member interposed therebetween,
the elastic member is fixed between the first sheet and the second sheet in a space defined by the pair of first fused portions, the first sheet, and the second sheet only by friction between a surface of the elastic member and the first sheet and between the first sheet and the second sheet,
when the stretchable sheet is viewed in cross section along a direction perpendicular to a direction in which the elastic member extends, at positions where the pair of first fused portions are formed, a length over which the first sheet is in contact with the elastic member is longer than a length over which the second sheet is in contact with the elastic member,
When the stretch sheet is viewed in cross section along a direction perpendicular to the extension direction of the elastic member at a position where the pair of first fusion bonded portions are formed,
the second sheet has a thick film region in the entire area between the pair of first fused portions, in which constituent fibers in the entire thickness direction have completely lost their fibrous form and become membrane-like due to melting and solidification,
the first sheet has a fibrous region in which the fibrous form of at least a part of the constituent fibers is maintained over the entire area between the pair of first fused portions,
The thick film region is a stretchable sheet having a shape that conforms to the shape of the elastic member and is not fused to the elastic member. The plurality of fused portions include the pair of first fused portions and a second fused portion,
2. The stretch sheet according to claim 1 , wherein second fused portions are intermittently disposed between adjacent first fused portions between adjacent elastic members in a direction perpendicular to the extension direction of the elastic members. The stretch sheet according to claim 2 , wherein the distance between adjacent fused portions in the direction in which the elastic member extends is 1 mm or more and 6 mm or less. The stretch sheet according to claim 2 or 3 , wherein the plurality of fused portions have a length along the extension direction of the elastic member of 0.2 mm or more and 3 mm or less. The stretchable sheet according to any one of claims 1 to 4, wherein the distance between adjacent elastic members is 1 mm or more and 10 mm or less. The stretchable sheet according to any one of claims 1 to 5, wherein the second sheet is a laminated nonwoven fabric formed by laminating a spunbond nonwoven fabric layer and a meltblown nonwoven fabric layer. The stretchable sheet according to any one of claims 1 to 6, in which the stress-elongation ratio relationship obtained by stretching the sheet to twice its original length under conditions of a chuck distance of 100 mm and a speed of 300 mm/min, and then shrinking the sheet at a speed of 300 mm/min, is such that, when the stress at 1.8 times the original length during the second cycle of stretching is A and the stress at 1.8 times the original length during the second cycle of shrinking is B, the value of B/A is 0.83 to 0.90. An absorbent article comprising an absorbent body and an exterior body located on a non-skin facing side of the absorbent body,
An absorbent article, wherein the exterior body comprises the stretchable sheet according to claim 1 .

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