WO2020246397A1

WO2020246397A1 - Expandable/contractible sheet, and absorbent article provided with expandable/contractible sheet

Info

Publication number: WO2020246397A1
Application number: PCT/JP2020/021470
Authority: WO
Inventors: 織恵辻村; 淳岩崎; 政宏南岡; 賢治安藤; 弘行横松
Original assignee: 花王株式会社
Priority date: 2019-06-04
Filing date: 2020-05-29
Publication date: 2020-12-10
Also published as: CN113905702A; CN113905702B

Abstract

The present invention has a first sheet (11), a second sheet (12), and a plurality of elastic members (13) that are disposed in a stretched state between the two sheets (11, 12) and that extend in one direction. The first sheet (11) and the second sheet (12) are joined by a plurality of fusion-bonded parts (15) that are positioned so as to sandwich the elastic members (13) on both sides and that are formed with gaps therebetween along the direction in which the elastic members (13) extend. The elastic members (13) are secured only by friction with the two sheets (11, 12) in a space demarcated by the fusion-bonded parts (15), the first sheet (11), and the second sheet (12). The second sheet (12) has a low-porosity region (20) on the thickness-direction inner side along the entirety of the region between the fusion-bonded parts. In the low-porosity region (20), some of constituent fibers are melted and solidified so that the fibrous shape thereof is lost, and the fibrous shape of the remaining constituent fibers is maintained.

Description

Elastic sheet and absorbent article with the elastic sheet

The present invention relates to an elastic sheet. The present invention also relates to an absorbent article provided with the elastic sheet.

As a sheet used for absorbent articles such as diapers, an elastic sheet in which an elastic member such as rubber thread is joined between two sheets in an extended state is known. For example, in Patent Document 1, the elastic elastic members are fixed by intermittently welding the inner sheet and the outer sheet in a state where a plurality of elastic elastic members arranged in parallel are sandwiched between the inner sheet and the outer sheet. The sheet is listed. The elastic elastic member is arranged in a cross-sectional space closed by a welded portion between the inner sheet and the outer sheet in the vicinity of both side portions in the radial direction thereof, and forms the outer surface of the elastic elastic member and the closed space. It is fixed by the frictional force with the seat.

In Patent Document 2, a hydrophobic non-woven fabric and a hydrophilic non-woven fabric are joined via an elastic member, and the hydrophilicity is formed by forming irregularities on at least the hydrophilic non-woven fabric of both of these non-woven fabrics. The non-woven fabric has a higher fiber density than other parts and includes a protrusion protruding from the hydrophobic non-woven fabric, in which the hydrophobic non-woven fabric and the hydrophilic non-woven fabric are in direct contact with each other. The composite sheet is described.

Apart from these techniques, the applicant first has a hydrophobic sheet having a plurality of recesses, a hydrophilic sheet, and a sheet having a plurality of elastic members arranged in an extended state between the sheets. Therefore, we have proposed a sheet in which the hydrophobic sheet has a fused portion at the top in the recessed portion and the thickness of the fused portion is within a predetermined range (Patent Document 3).

Japanese Unexamined Patent Publication No. 2008-104853 Japanese Unexamined Patent Publication No. 2017-12319 Japanese Unexamined Patent Publication No. 2017-13188

The present invention includes a first sheet made of a fiber sheet, a second sheet arranged facing the first sheet and made of a fiber sheet, and an elastic member arranged between both sheets in an extended state and extending in one direction. The present invention relates to an elastic sheet having elasticity and having elasticity 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 with the elastic member interposed therebetween and formed at intervals along the extending direction of the elastic member. It is preferable to have.
The elastic member is formed on the surface of the elastic member, the first sheet, and the space defined by the fused portion, the first sheet, and the second sheet located on both sides of the elastic member. It is preferable that the sheets are fixed between the two sheets only by friction with the second sheet.
When the elastic sheet is cross-sectionally viewed along a direction orthogonal to the extending direction of the elastic member at the forming position of the fused portion, the first sheet is more than the length in which the second sheet is in contact with the elastic member. It is preferable that the length in contact with the elastic member is longer.
When the elastic sheet is cross-sectionally viewed along the direction orthogonal to the extending direction of the elastic member at the forming position of the fused portion, the second sheet is formed inside the thickness direction in the entire area between the fused portions. It is preferable to have a low porosity region in which the porosity between them is relatively lower than the other regions.
In the low porosity region, it is preferable that a part of the constituent fibers loses the fiber morphology and is in a melt-solidified state, and the rest of the constituent fibers maintains the fiber morphology.

The present invention also relates to an absorbent article composed of an absorbent body and an exterior body located on the non-skin facing surface side of the absorbent body.
The exterior body includes the stretchable sheet. The stretchable sheet is preferably arranged so that the first sheet of the stretchable sheet faces the skin.

FIG. 1 is a partially cutaway plan view showing an embodiment of the elastic sheet of the present invention. FIG. 2 is an enlarged plan view showing a main part of the elastic sheet shown in FIG. FIG. 3 is a cross-sectional view taken along the Y direction showing an enlarged main part of the elastic sheet shown in FIG. 4 (a) to 4 (c) are diagrams for explaining the action and effect of the elastic sheet shown in FIG. FIG. 5 is a diagram for explaining the action and effect of the elastic sheet shown in FIG. 1 (corresponding to FIG. 4). FIG. 6 is a perspective view showing a state in which the elastic sheet shown in FIG. 1 is relaxed. FIG. 7 is a microscope image of an example of the low porosity region according to the present invention. FIG. 8 is a schematic view showing an apparatus suitably used for producing the elastic sheet of the present invention. FIG. 9 is an enlarged view of a main part of the apparatus shown in FIG. FIG. 10 is an enlarged view of the first contact portion shown in FIG.

Detailed description of the invention

From the viewpoint of reducing discomfort caused by sweat and preventing the occurrence of eczema, heat rash, rash, etc., it is desirable that the sheet used for the absorbent article has an excellent effect of separating the absorbed sweat from the skin. The elastic sheet described in Patent Document 1 is formed by joining two sheets to each other without using an adhesive. However, the elastic sheet having such a structure causes sweat on the skin contact surface side. It may remain, and the stretchable sheet with sweat may come into contact with the skin, causing discomfort. Patent Documents 2 and 3 disclose elastic sheets in which two sheets are joined via an adhesive, but the effect of joining the two sheets without using an adhesive and separating sweat from the skin. It does not disclose the elastic sheet having.

The present invention relates to an elastic sheet capable of eliminating the above-mentioned drawbacks of the prior art, and to provide an absorbent article provided with the elastic sheet.

Hereinafter, the present invention will be described based on the preferred embodiment with reference to the drawings. FIG. 1 shows an embodiment of the elastic sheet of the present invention. The figure is a partially broken plan view when the elastic sheet 10 is stretched to the maximum stretched state. The maximum stretched state is a first sheet constituting the stretchable sheet 10 until each elastic member, which will be described later, is stretched to reach a design dimension (dimensions when the elastic member is unfolded in a plane state without any influence of the elastic member). It is a state in which the 11 and the second sheet 12 are stretched. In the fractured portion shown in FIG. 1, the first fused

portions

15a and 15b, which will be described later, are omitted.

As described above, the elastic sheet 10 has a first sheet 11 and a second sheet 12 which is arranged to face the first sheet. A plurality of linear elastic members 13 such as rubber threads are arranged between the two

sheets

11 and 12. Specifically, a plurality of elastic members 13 are intermittently arranged at predetermined intervals. The plurality of elastic members 13 extend in one direction without intersecting each other. FIG. 1 shows a state in which the elastic members 13 extend in parallel with each other. Each elastic member 13 is fixed between the two

sheets

11 and 12 in an extended state. In the following description, the extending direction of the elastic member 13 is also referred to as the X direction. Further, the direction orthogonal to the extending direction of the elastic member 13 is also referred to as a Y direction.

The first sheet 11 is made of a fiber sheet. The first sheet 11 can be a hydrophilic fiber sheet or a hydrophobic fiber sheet. When the first sheet 11 is a hydrophilic sheet, various advantages described later occur. In the hydrophilic fiber sheet, the contact angle of the constituent fibers collected from any part of the fiber sheet with water is less than 90 degrees. The contact angle of the fiber with water can be measured, for example, according to the method described in Japanese Patent Application Laid-Open No. 2015-142721. From the viewpoint of facilitating the formation of the fused portion described later, the first sheet is preferably a hydrophilic non-woven fabric containing a fiber obtained by imparting hydrophilicity to a synthetic fiber made of a heat-sealing resin as a constituent fiber. Examples of the heat-sealing resin include polyethylene and polypropylene. The fibers constituting the fiber sheet may be core-sheath type composite fibers whose surface is made of a heat-sealing resin only.

The second sheet 12 is also made of a fiber sheet. Like the first sheet 11, the second sheet 12 may be a hydrophilic fiber sheet or a hydrophobic fiber sheet. When the first sheet 11 described above is a hydrophilic fiber sheet, the second sheet 12 is preferably a hydrophobic fiber sheet. The hydrophobic fiber sheet has a contact angle of the constituent fibers collected from any part of the fiber sheet with water of 90 degrees or more. From the same viewpoint as described above, the second sheet 12 is preferably a sheet containing the synthetic fiber made of the heat-sealing resin described above as a constituent fiber. The forming material may be the same or different between the first sheet 11 and the second sheet 12.

As shown in FIG. 1, the first sheet 11 and the second sheet 12 are joined by a plurality of fused portions. Both

sheets

11 and 12 are fused at the fused portion. "Fusion" means that a molten portion is formed on both

sheets

11 and 12 by heat, and the molten portions are mixed and then cooled to integrally bond the portions. The elastic sheet 10 of the present embodiment has a pair of first fused

portions

15a and 15b located on both sides of the elastic member 13 and a pair of first fused portions in the Y direction as fusion portions. It has a plurality of

second fusion portions

16a and 16b located between the

attachment portions

15a and 15b. The fused portions of the first fused

portions

15a and 15b and the second fused

portions

16a and 16b are formed at intervals along the extending direction of the elastic member 13, that is, the X direction. Two second fused portions 16 are arranged side by side between a pair of first fused

portions

15a and 15b in the Y direction. The fused

portions

15a, 15b, 16a, 16b are separated from each other, and are arranged in this order in a row along the Y direction. By arranging the fused portions in this way, folds described later can be formed on each surface of the elastic sheet 10.

The elastic member 13 is located between the first fused

portions

15a and 15b located on both sides of the elastic member 13 with the elastic member 13 sandwiched therein, by friction only with the first sheet 11 and the second sheet 12, both sheets 11, It is fixed between twelve. Between the first fused

portions

15a and 15b, a space defined by the first fused

portions

15a and 15b, the first sheet 11, and the second sheet 12 is formed in a cross section along the Y direction. In this space, the elastic member 13 is fixed between the two

sheets

11 and 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 elastic 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 elastic 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 elastic sheet 10 is formed while maintaining the good texture and breathability inherent in the first sheet 11 and the second sheet 12. Further, the elastic sheet 10 is highly elastic.

As described above, the elastic member 13 is both formed by friction between the surface of the elastic member 13 and the first sheet 11 and the second sheet 12 in the space along the Y direction between the pair of first fused

portions

15a and 15b. It is fixed to the

sheets

11 and 12. More specifically, as shown in FIG. 2, which is an enlarged view of a main part of FIG. 1, the side edge 151a on the elastic member 13 side of one first fused portion 15a and the elastic member 13 of the other first fused portion 15b. The first fused portion interval D, which is the interval between the side edge 151b on the side, is made narrower than the diameter d1 of the elastic member 13 in the maximum extended state of the elastic sheet 10, and the pair of first fused portions 15a The elastic member 13 is fixed between the first and

second sheets

11 and 12 only by the friction generated on the surface of the elastic member 13 in the space by the pinching pressure of, 15b. In FIG. 2, it seems that the elastic member 13 is joined to the pair of first fused

portions

15a and 15b, but in reality, the elastic member 13 is not joined to the pair of first fused

portions

15a and 15b. It has become.

From the viewpoint of securely fixing the elastic member 13 only by friction between the surface of the elastic member 13 and the first sheet 11 and the second sheet 12 in the space between the pair of first fused

portions

15a and 15b, the first The 1-fused portion interval D preferably has a value of d2 / D of 1.1 or more when the diameter of the elastic member 13 in the relaxed state of the elastic sheet 10 is d2 (see FIG. 2). It is more preferably 2 or more, and even more preferably 1.3 or more. The higher the value of d2 / D, the higher the frictional force between the surface of the elastic member 13 and the first sheet 11 and the second sheet 12, which is preferable. The diameter d2 of the elastic member 13 in the relaxed state of the elastic sheet 10 is the diameter of the elastic member 13 at the portion where the elastic member 13 is not pinched in the relaxed state of the elastic sheet 10.

When the above d2 is expressed by fineness, the fineness is preferably 155 dtex or more, and more preferably 310 dtex or more, from the viewpoint of ensuring the elasticity of the elastic sheet 10. Further, it is 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 more preferably 310 dtex or more and 940 dtex or less.

As shown in FIG. 3, when the elastic sheet 10 is viewed in cross section along the direction orthogonal to the extending direction of the elastic member 13, that is, the Y direction in the figure at the forming positions of the fused

portions

15a and 15b, the second The length of the first sheet 11 in contact with the elastic member 13 is longer than the length of the sheet 12 in contact with the elastic member 13. The reason for this is that, in the elastic member 13 in the same cross-sectional view, the portion on the first sheet 11 side is Z outer in the thickness direction of the elastic sheet 10 as compared with the portion on the second sheet 12 side of the elastic member 13. When the elastic member 13 is bisected in the thickness direction Z in the same cross-sectional view, the elastic member 13 has an asymmetrical shape between the second sheet 12 side and the first sheet 11 side. (See Fig. 3). In other words, in the same cross-sectional view, 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 rises outward in the thickness direction on the first sheet 11 side. Has a part. Further, on the second sheet 12 side of the elastic member 13, the portion between the first fused

portions

15a and 15b in the cross-sectional view along the Y direction is a portion other than the portion between the first fused

portions

15a and 15b in the same cross-sectional view. It is a relatively flat part.

Further, as shown in FIG. 3, in the stretchable sheet 10, the second sheet 12 has a porosity between the constituent fibers relative to the other regions in the thickness direction Z in the entire area between the fused

portions

15a and 15b. It has a low porosity region 20. The other region is a region other than the low porosity region 20 in the second sheet 12, that is, a region other than the region overlapping the elastic member 13 in the thickness direction Z, and is a region composed of fibers. Therefore, the first fused

portions

15a and 15b and the second fused portion 16 which are regions where the fibers are melted and lose the original fiber state do not correspond to other regions. The low porosity region 20 may have a porosity of the entire thickness direction lower than the porosity of the other regions in the thickness direction. On the other hand, on the surface side of either one in the thickness direction, the fibers are melted and the porosity is low, but in the inside in the thickness direction, the form in which the fibers maintain the fiber morphology and the porosity is high is low. It is excluded from the porosity region 20. Inside the low porosity region 20 in the thickness direction, portions having a lower porosity than the other regions may be continuously present in the Y direction or may be intermittently present in the same direction. The stretchable sheet has a low porosity region 20 on the second sheet 12. The low porosity region 20 is formed on the second sheet 12 located between the pair of first fused

portions

15a and 15b in the Y direction, and faces the first sheet 11 with the elastic member 13 interposed therebetween. ing. The low porosity region 20 has a lower porosity than the other regions, but the low porosity region 20 and the elastic member 13 are not fused to each other.

In the elastic sheet 10 shown in FIG. 3, the first sheet 11 has a region 21 in which the porosity between the constituent fibers inside in the thickness direction is lower than that in other regions other than the

fusion portions

15a and 15b. .. The porosity of the entire thickness direction of the region 21 may be lower than the porosity of the other regions in the first sheet 11 in the thickness direction. The other region is a region other than the region 21 having a low porosity in the first sheet 11, that is, a region other than the region overlapping the elastic member 13 in the thickness direction Z, and the first sheet 11 and the second sheet 12 are A region that is not joined and is composed of fibers. Therefore, the first fused

portions

15a and 15b and the second fused portion 16 which are regions where the fibers are melted and lose the original fiber state do not correspond to other regions. Such a region 21 may have a lower porosity over the entire thickness direction than the other regions in the first sheet 11, or the internal porosity in the thickness direction of the first sheet 11 may be lower than the other regions. The porosity on the surface side in the thickness direction may be higher than that of the inside of the region. Hereinafter, a region having the above-mentioned porosity and overlapping with the elastic member 13 in the thickness direction Z, and a region composed of sheets arranged to face the low porosity region 20 with the elastic member 13 interposed therebetween, is defined as a region. 2 Also referred to as a low porosity 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 substantially flat portion of the elastic member 13. As a result, at the forming positions of the fused

portions

15a and 15b, the surface of the second sheet 12 facing the elastic member 13 is along the substantially flat portion of the elastic member 13. Therefore, in the elastic sheet of the present embodiment, the surface on the second sheet side is substantially flat between the pair of first fused

portions

15a and 15b, while the surface on the first sheet side is outward in the thickness direction Z. It is raised to the side. That is, in the present embodiment, the low porosity region 20 has a shape that follows the shape of the elastic member 13. Specifically, the low porosity region 20 is in close contact with the surface of the elastic member 13 facing the low porosity region 20, and has a shape that follows the shape of the surface.

In the cross-sectional view of the elastic sheet 10 along the Y direction, when the low porosity region 20 is viewed along the Y direction, the thickness of the low porosity region 20 is constant. “Constant thickness” means that the difference between the maximum thickness and the minimum thickness of the low porosity region 20 is 5 μm or less. The maximum thickness of the low porosity region 20 is measured by using image data obtained by magnifying and observing a cross section of a sample in the [method for measuring porosity] described later.

In the low porosity region 20, some of the constituent fibers have lost their fiber morphology and are in a melt-solidified state, and the rest of the constituent fibers maintain their fiber morphology. That is, the low porosity region 20 is a region in which fibers having a melt-solidified portion and fibers having no melt-solidified portion are mixed. The second low porosity region 21 may have fibers having a melt-solidified portion. The abundance of the fibers having the melt-solidified portion in the second low porosity region 21 is preferably 0 to 20% of the fibers existing in the second low porosity region 21. The abundance of fibers having a melt-solidified portion can be measured by observation with a scanning electron microscope. The abundance of fibers and the melt-solidified state of the fibers (state of constituent fibers) can be confirmed by the method described later.

The elastic sheet of the present invention can be suitably used for an exterior body forming an outer surface of an absorbent article. From the viewpoint of facilitating the absorption of sweat by coming into contact with the wearer's skin, the elastic sheet 10 shown in FIG. 3 is hydrophilic as the first sheet 11 as shown in FIGS. 4A to 4C. It is preferable to use the one with the first sheet 11 facing the skin. In such a usage state, at the position where the elastic member 13 of the elastic sheet 10 overlaps with the elastic member 13 in the thickness direction Z, the sweat E in contact with the hydrophilic first sheet 11 is drawn in the thickness direction Z, and the first sheet 11 Shifts to the elastic member 13 side of the above [see FIG. 4 (a)]. Since the elastic member 13 and the first sheet 11 are in close contact with each other, a capillary force acts between them. Due to this, sweat E reaches between the elastic member 13 and the first sheet 11 [see FIG. 4 (b)]. As described above, the elastic member 13 is sandwiched between the pair of first fused

portions

15a and 15b by the first sheet 11 and the second sheet 12 and is in close contact with each other. Therefore, the sweat E is the elastic member 13. Diffuses well along the interface between the surface of the surface and the first sheet 11. In particular, in the low porosity region 20 of the present embodiment, since the porosity between the constituent fibers is lower than in other regions, a large capillary force acts. As a result, the diffused sweat E is likely to be drawn into the low porosity region 20 [see FIG. 4 (c)].

When the second sheet 12 is used with the skin facing surface side, the low porosity region 20 has a lower porosity between the constituent fibers than the other regions in the second sheet 12, so that the plane of the second sheet 12 is flat. The sweat E absorbed in the direction shifts to the low porosity region 20. As a result, the sweat E absorbed in a wide range can be concentrated in the low porosity region 20, and the contact area between the portion containing the sweat E and the skin S can be reduced. Further, the capillary force is larger at the interface between the low porosity region and the elastic member 13 than at the interface between the low porosity region 20 and the skin S. Due to this difference in capillary force, the sweat E that has reached the low porosity region 20 is held between the low porosity region 20 and the surface of the elastic member 13, and is in a state where it is difficult to return to the skin side (see FIG. 5). .. As a result, the absorbed sweat E can be separated from the skin S, and the discomfort caused by the sweat E can be reduced.

As described above, in the thickness direction Z of the elastic sheet 10, the absorbed sweat E can be separated from the skin S, and the absorbed sweat can be prevented from coming into contact with the skin S. As a result, the discomfort caused by sweat can be reduced. Further, by separating the sweat E from the skin S to the side far from the skin S, the moisture due to the sweat E can be prevented from being trapped inside the absorbent article, and the sweat can be effectively transpired to the outside of the absorbent article.

Further, in the elastic sheet of the present invention, as described above, the second sheet 12 is elastic when the elastic sheet is cross-sectionally viewed along the Y direction at the forming positions of the first fused

portions

15a and 15b. The length of the first sheet 11 in contact with the elastic member 13 is longer than the length of contact with the member 13. Therefore, when the elastic sheet of the present invention is used as, for example, an exterior body forming the outer surface of the absorbent article, and the elastic sheet is arranged so that the second sheet 12 faces the wearer's skin, the second sheet The low porosity region 20 formed in 12 can reduce the degree to which the elastic member 13 presses on the wearer's skin. Therefore, there is an advantage that a feeling of strangeness is less likely to occur when the absorbent article is worn. On the contrary, when the elastic sheet is arranged on the absorbent article so that the second sheet 12 faces the clothing side, most of the cross section of the elastic member 13 is on the wearer's skin side. There is an advantage that the elastic sheet gently contacts the wearer's skin as it will be present.

The porosity is measured by the following method.
[Measurement method of porosity]
After freezing the elastic sheet using liquid nitrogen or the like, a portion of the elastic sheet to which the elastic member is fixed by a pair of first fusion portions is cut out from the central portion in the extension direction of the elastic member. At this time, the elastic member is cut along a direction orthogonal to the extension direction, and this is used as a sample. As described above, the elastic member is fixed only by friction between the first sheet and the second sheet, and the elastic member and the first sheet and the second sheet are not fused to each other. Therefore, 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 magnified and observed using a scanning electron microscope (for example, JSM-IT100 manufactured by JEOL Ltd.). The magnification at the time of observation is 100 to 200 times so that the first sheet and the second sheet can be observed in the thickness direction of the sample, and both ends between the pair of first fused portions can be observed in the extension direction of the elastic member. Set to the magnification of. In this observation field of view, the sheet having a longer length in contact with the elastic member is regarded as the first sheet, the shorter sheet is regarded as the second sheet, and the area occupied by the fibers in the second sheet is measured by image analysis. Specifically, the image of the observation field is binarized by setting a threshold value at the brightness boundary between the fiber and the portion where the fiber does not exist by using image processing software such as ImageJ. In general, when binarized with white and black, the fibers become white and the portion where the fibers do not exist becomes black, so that the white portion can be identified as a fiber and the black portion as a void. When only the peripheral side surface of the fiber is observed instead of the cross section of the fiber, all the portions other than the cross section are identified as voids. Next, the outer edge of the second sheet between the fused portions in the observation field of view is traced along the contour of the white portion to identify the contour of the low porosity region. The boundary between the low porosity region and the fused portion may be unclear because the melt-solidified portion of the fiber is integrated between the fibers, but the boundary is specified by the following method. First, a fiber having a cross-sectional shape of a fiber having a melt-solidified portion and in which more than half of the contour circumference of the fiber cross-section is identifiable is specified. Next, a portion where the plurality of the fibers are continuous is specified along the thickness direction Z of the stretchable sheet, and the contour of the fibers is traced over the plurality of fibers along the thickness direction. The area of the specified low porosity region was measured using the image processing software, and this was designated as the area of the low porosity region (A ₁ ), and the portion identified as a void in the region surrounded by the contour. The area of the void is measured, and this is defined as the void area (A ₂ ) in the low porosity region. Next, the porosity (GR) in the low porosity region is calculated by the following formula [1].
GR (%) = (A ₂ / A ₁ ) x 100 ... Equation [1]
GR: Porosity in the low porosity region A ₁ : Area in the low porosity region A ₂ : Porosity area in the low porosity region The porosity can be measured at any three locations where a pair of first fused portions are formed. The average value is taken as the porosity in the low porosity region.

The abundance of fibers having a melt-solidified portion is the total number of fibers having a melt-solidified portion observed by the same method as the above-mentioned method for measuring porosity. When the area of the melt-solidified portion existing in the contour of the low void ratio region 20 is larger than the cross-sectional area of the fiber observed in other regions and the contour of the fiber is unclear in the melt-solidified portion, the melt The area of the solidified portion (B2) and the average cross-sectional area (B1) per fiber observed in other regions are measured, and the number of fibers (B) per fiber solidified portion is calculated by the following formula [2]. Find and add this to the total number of fibers with melted and solidified portions. The average cross-sectional area (B1) per fiber is the average value of three arbitrarily selected fibers in other regions.
B = B2 / B1 ... [2]
B: Number of fibers per melt-solidified portion B1: Average cross-sectional area per fiber B2: Area of melt-solidified portion The abundance of fibers having a melt-solidified portion is determined by the pair of first fused portions in the elastic sheet. Measure at any three formed points and use the average value of these.

The porosity of the second low porosity region and other regions can also be measured in the same manner as described above. The porosity of the second low porosity region is determined after the contour of the second low porosity region is specified from the first sheet in the above-mentioned image of the observation field of view. The porosity of the other region is a region other than the region overlapping the elastic member 13 in the thickness direction Z in the second sheet, and is performed by magnifying and observing an arbitrary portion in the region other than the fused portion.

Regarding the state of the constituent fibers in the low porosity region 20, the sample was observed by the same method as the above-mentioned method for measuring the porosity, and the following conditions (1) to (4) were applied to the second sheet in the region overlapping the elastic member. Check if all of the above are satisfied.
Condition (1): Not all fibers are resinified in the region overlapping the elastic member.
Condition (2): At least one fiber has a resinified melt-solidified portion, and is integrated with other fibers adjacent to the fiber via the melt-solidified portion.
Condition (3): There is a gap (void) between the fibers or between the melt-solidified portion of the fiber and another fiber. The gap is in the range of 1 μm to 50 μm.
Condition (4): At least one fiber does not have a melt-solidified portion and maintains the fiber morphology.

In the method for measuring porosity, the cut surface of the sample is observed in a state like the microscope image shown in FIG. 7, for example. The cavity in the central portion of the microscope image shown in FIG. 7 is a portion where elastic members are arranged, and a film-like portion located sandwiching the elastic member is a first fused portion. In the microscope image shown in FIG. 7, the low porosity region is indicated by a frame. As shown in FIG. 7, the melt-solidified portion of the fiber in the low porosity region is a portion in which a part of the fiber is integrated with other fibers, and the fibers are grouped together, so that the entire portion is a single mass. It has become. Further, in FIG. 7, the portion facing the low porosity region across the cavity is the second low porosity region. In the figure, the second low porosity region has few melt-solidified portions, so that the fibers are separated and not integrated.

The first sheet 11 preferably has a second low porosity region 21. With such a configuration, the effect of separating the sweat E described above from the skin S is achieved. Specifically, the sweat E absorbed in a wide range can be concentrated in the second low porosity region 21, and the contact area between the portion containing the sweat E and the skin S can be reduced. Further, since the capillary force is higher at the interface between the second low porosity region and the elastic member 13 than at the interface between the second low porosity region 21 and the skin S, the second low porosity region is reached. Sweat E is held between the second low porosity region and the surface of the elastic member 13, and is in a state where it is difficult to return to the skin side. As a result, the absorbed sweat E can be separated from the skin S, and the discomfort caused by the sweat E can be reduced.

From the viewpoint of further improving the effect of separating sweat E from the skin between the first fused

portions

15a and 15b of the first sheet 11, the first sheet 11 is formed between the pair of first fused

portions

15a and 15b. It is preferable to have a plurality of regions having different porosities. In the region between the pair of first fused

portions

15a and 15b in the first sheet 11, the region having a relatively low porosity among the plurality of regions having different porosities has the following configurations (c1) to (c3). ), Or a combination of two or more of these.
Configuration (c1): A portion that comes into contact with the skin is formed in the region between the pair of first fused

portions

15a and 15b in the first sheet 11.
Configuration (c2): Located in the center of the region between the pair of first fused

portions

15a and 15b in the first sheet 11 in the Y direction.
Configuration (c3): The length in the Y direction is the same as or longer than the length in the Y direction of the region having a relatively high porosity among the plurality of regions having different porosities.
From the viewpoint of further improving the effect, the length of the region having a relatively low porosity in the Y direction is the length of the region having a relatively high porosity in the Y direction with respect to the configuration (c3). On the other hand, it is preferably 100% or more, more preferably 120% or more, and preferably 200% or less, more preferably 150% or less.

The region having a relatively high porosity and the region having a relatively low porosity between the first fused

portions

15a and 15b of the first sheet 11 are specified by the following method. First, the region where the first sheet 11 and the elastic member 13 overlap is divided into 10 regions in the Y direction, and each of these regions is divided into 10 regions by using the image processing software described above to cover the entire area of the region. And the void area are measured. Next, the porosity in each of the 10 regions is calculated by dividing the void area by the area of the entire region. Next, the 10 regions are divided into two groups so that the difference in porosity is 30% or more. Of the two groups, the region belonging to the group with the higher porosity is referred to as the "region having a relatively high porosity", and the region belonging to the group having the lower porosity is referred to as the "region having a relatively low porosity". To do.

As described above, the first and

second sheets

11 and 12 are joined by a plurality of fused portions arranged along the Y direction. In the relaxed state of the elastic sheet 10, the elastic member 13 shown in FIG. 1 contracts, and the elastic sheet 10 becomes narrower in the X direction. The first sheet 11, which has lost its place due to the narrowing of the width, protrudes in the direction away from the elastic member 13 as shown in FIG. 6, with the second fused portion 16 as the starting point of bending. That is, in the elastic sheet 10, a convex portion 17 is formed on the first sheet 11 so as to project in the direction away from the elastic member 13 along the thickness direction Z of the elastic sheet 10. The convex portion 17 reduces the contact area between the elastic sheet and the skin and increases the ratio of the sweat diffusion area to the contact area, so that the sweat evaporation effect is further improved. The perspiration diffusion area is the low porosity region 20, or the area where the elastic sheet is wet by the perspiration that has migrated and diffused between the low porosity region 20 and the elastic member 13.

In the present embodiment, the first and

second sheets

11 and 12 project so as to be separated from each other along the thickness direction as shown in FIG. 6 with the second fused portion 16 as the starting point of bending. That is, in the elastic sheet 10, convex portions 17 are formed on the first sheet 11 and the second sheet 12 so as to protrude from each other along the thickness direction Z, respectively. With such a configuration, the transpiration effect is further improved, and the contact area between the sweat-wet elastic sheet 10 and the skin is reduced, so that the wearing feeling of the absorbent article using the sheet is further improved. To do. The convex portion 17 is a portion of the elastic sheet 10 that forms folds, which will be described later, and is a portion that follows the shape of the elastic member 13 at a position where the first sheet 11 and the second sheet 12 overlap the elastic member 13. Is a different part.

As shown in FIG. 6, the convex portion 17 continuously extends along the Y direction. A plurality of folds are formed on each surface of the elastic sheet 10 by the convex portion 17. The stretchable sheet 10 in the state shown in FIG. 6 exhibits a flexible texture and an excellent appearance due to the folds.

From the viewpoint of further improving the transpiration effect of sweat, when the distance between two elastic members 13 adjacent to each other along the Y direction is Le (see FIG. 1), the second fusion along the Y direction with respect to the distance Le The value of L16 / Le, which is the ratio of the length L16 (see FIG. 1) of the landing portion 16, is preferably 0.25 or more, more preferably 0.50 or more, and more preferably 0.70 or more. Is more preferable. The closer the value of L16 / Le is to 1, the more preferable it is from the viewpoint of ensuring the joint strength.

From the same viewpoint as described above, the distance Le between two elastic members 13 adjacent to each other along the Y direction is preferably 1 mm or more. The Le value 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 further preferably 1 mm or more and 6 mm or less.

From the same viewpoint as described above, when the distance between two fused portions adjacent to each other along the X direction is Lf (see FIG. 1), the value of Lf is preferably 6 mm or less, and preferably 5 mm or less. More preferably, it is 3 mm or less. The lower limit of Lf is not particularly limited, and the smaller the value, the larger the sweat diffusion area, which is preferable.

Further, from the same viewpoint as described above, the lengths in the X direction, which are the widths of the first fused portion 15 and the second fused portion 16, are preferably 3 mm or less and 2 mm or less independently of each other. It is preferably 1 mm or less, and more preferably 1 mm or less. The lower limit of the width is not particularly limited, and the smaller the value, the more preferable.

The material constituting the elastic sheet 10 will be described in detail. As the first and

second sheets

11 and 12, for example, air-through non-woven fabric, heat roll non-woven fabric, spunlace non-woven fabric, spunbond non-woven fabric, non-woven fabric produced by various manufacturing methods such as melt blown non-woven fabric, and two or more of these are laminated and integrated. A laminated fabric or the like can be used. From the viewpoint of forming flexible folds that look beautiful and feel good, the fiber sheets used as both sheets or one sheet are air-through non-woven fabric, heat roll non-woven fabric, spunlace non-woven fabric, spunbond non-woven fabric, melt blown non-woven fabric and the like. Is preferable.

As described above, a non-woven fabric is preferably used as the first and

second sheets

11 and 12. The basis weight of the non-woven fabric is preferably 5 g / m ² or more and 50 g / m ² or less, and particularly preferably 8 g / m ² or more and 30 g / m ² or less. The buckling strength of the non-woven fabric having such a basis weight is preferably 50 cN or less in the direction orthogonal to the machine flow direction (CD), particularly preferably 30 cN or less, and preferably 70 cN or less in the machine flow direction (MD), particularly preferably 50 cN or less. Is. By using a soft sheet, the formability of the folds can be enhanced. Buckling strength is measured by the following method.

Buckling strength test method:
Take a rectangular test piece 150 mm in the machine flow direction (MD) and 30 mm in the direction orthogonal to the machine flow direction (CD). Five test pieces are cut out from the sheet to be measured. Using this test piece, a cylinder having a diameter of 45 mm is made, and the upper end and the lower end of the overlapping portion are fastened with a stapler or the like, and this is used as a measurement sample. With respect to this measurement sample, the maximum strength when compressed to 20 mm is measured under the measurement conditions of a compression speed of 10 mm / min and a measurement distance of 20 mm in the compression test mode of the Tencilon universal test device. The measurement environment is 20 ° C. and 65% RH. In such measurement, the average value of the maximum intensity of each measurement sample is obtained, and this is used as the buckling intensity in the orthogonal direction (CD).
The buckling strength in the machine flow direction (MD) is the same as above, except that a rectangular test piece of 150 mm in the direction orthogonal to the machine flow direction (CD) and 30 mm in the machine flow direction (MD) is taken. Be measured.

The first and

second sheets

11 and 12 are not limited to two separate sheets, but one sheet is bent to form two opposing surfaces, and a portion constituting one surface is 1 The portion constituting one sheet and the other surface may be used as another sheet. When the first and

second sheets

11 and 12 are composed of one sheet, the one sheet is preferably a hydrophilic fiber sheet.

As the material for forming the elastic member 13, various known elastic materials used for absorbent articles such as disposable diapers and sanitary napkins can be used without particular limitation. For example, examples of the material include synthetic rubber such as styrene-butadiene, butadiene, isoprene, and neoprene, natural rubber, EVA, elastic polyolefin, polyurethane, and the like, and the morphology includes a rectangular, square, circular, and polygonal cross section. Such as thread-like or string-like (flat rubber, etc.), multifilament type thread-like, or the like can be used.

Next, a suitable manufacturing method of the elastic sheet 10 shown in FIGS. 1 to 6 will be described with reference to FIG. The figure shows an apparatus preferably used for manufacturing the elastic sheet 10. The device 100 shown in the figure includes an ultrasonic fusion unit 30. The ultrasonic fusion unit 30 includes a horn 31 that vibrates ultrasonic waves and a receiving roll 32 that is arranged at a position facing the tip surface of the horn 31. The horn 31 is made of a metal such as an aluminum alloy or a titanium alloy, and is designed to resonate in the frequency band 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 welding object.

The receiving roll 32 is designed so that the temperature of the receiving roll 32 can be adjusted, whereby 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 wound around the receiving roll 32. The receiving roll 32 can adjust the temperature of the receiving roll 32 by, for example, providing a heater for heating the receiving roll 32 and a temperature sensor for measuring the temperature of the receiving roll 32 inside the rotating shaft side. it can. A horn 31, which will be described later, is pressed against the second sheet 12, and ultrasonic vibration is directly applied to the second sheet 12.

FIG. 9 shows an enlarged view of the main part of the ultrasonic fusion section 30 in FIG. The ultrasonic fusion portion 30 includes a receiving roll 32 in which

contact portions

40 and 41 forming convex portions are formed on the peripheral surface, and a horn 31 capable of contacting the convex portions. The Y direction shown in FIG. 9 is the width direction (axial direction) of the receiving roll 32, and this direction coincides with the Y direction in the stretchable sheet 10 to be manufactured. As shown in the figure, a pair of convex portions are arranged along the axial direction on the peripheral surface of the receiving roll 32 in the ultrasonic fusion portion 30. A concave portion 42 is formed between the pair of convex portions. The pair of convex portions are collectively referred to as a first contact portion 40. The receiving roll 32 is provided with a first contact portion 40 intermittently along the rotation direction R (see FIG. 8) of the roll. Further, 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 of the present embodiment, the first contact portion 40 and the two second contact portions 41 are alternately arranged side by side in the width direction thereof. On the other hand, in the horn 31, the surface having the portions that abut the first contact portion 40 and the second contact portion 41 is a flat surface without unevenness.

As shown in FIGS. 9 and 10, the first contact portion 40 is provided with a recess 42 in a substantially central portion in the Y direction, that is, in the roll width direction. The recess 42 has a rectangular shape in a cross-sectional view along the width direction of the receiving roll 32. The recess 42 has a volume for accommodating at least a part of the elastic member 13 in the extended state. In other words, the recess 42 has a volume such that the elastic member 13 can partially protrude from the upper surface of the first contact portion 40 in a state where the elastic member 13 is housed in the recess 42. The opening width of the recess 42 along the Y direction roughly corresponds to the first fused portion spacing D (see FIG. 2) in the target elastic sheet 10.

In this manufacturing method, the first sheet 11, the second sheet 12, and a plurality of elastic members 13 arranged in an extended state between the

sheets

11 and 12 are used. Returning to FIG. 8, the first sheet 11 unwound from the original fabric 11a of the first sheet 11 is conveyed while being wound around the peripheral surface of the receiving roll 32. In a state where the first sheet 11 is wound around the peripheral surface of the receiving roll 32, a plurality of elastic members 13 each unwound from the winding body 13a are arranged on the surface of the first sheet 11 in an extended state. .. The elastic member 13 is conveyed in a state of being partially housed in the recess 42 of the first contact portion 40 provided on the peripheral surface of the receiving roll 32. At this point, the first sheet 11 is previously housed in the recess 42 (see FIG. 9).

When a part of the elastic member 13 is accommodated in the recess 42 in the extended state, the degree of extension of the elastic member 13 is larger than the degree of extension of the elastic member 13 in the maximum extended state of the elastic sheet 10, and the diameter of the elastic member 13 is large. It is smaller than the opening width of the recess 42 along the Y direction. By doing so, in the obtained elastic sheet 10, the pinching pressure between the pair of first fused

portions

15a and 15b is increased, and the frictional force between the elastic member 13 and the first sheet 11 and the second sheet is sufficiently secured. can do.

After the elastic member 13 is housed in the recess 42, the second sheet 12 unwound from the original fabric 12a of the second sheet 12 is supplied to the peripheral surface of the receiving roll 32. As a result, a laminated body in which the stretched elastic member 13 is arranged between the first sheet 11 and the second sheet 12 is prepared. That is, the laminated body is supplied so that the elastic member 13 in the laminated body passes through the concave portion 42 in a state where the

convex portions

40, 41 of the receiving roll 32 and the joint portion of the sheet member face each other. In the laminated body, 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 laminated body by the horn 31 (see FIGS. 9 and 10). At this time, the laminated body is pressurized by the horn 31 to form a substantially flat portion on the second sheet 12 side of the elastic member 13, and the second sheet 12 is in close contact with the elastic member 13 to form the substantially flat portion. It will be in a state along the flattened part.

The ultrasonic fusion section 30 fuses the first sheet 11 and the second sheet 12 in the laminated body at positions on both sides of the elastic member 13 and at a plurality of positions spaced apart along the Y direction. Let me. As a result, the pair of first fused

portions

15a and 15b described above and the second fused portion 16 are formed. As shown in FIG. 9, on the peripheral surface of the receiving roll 32, the first contact portion 40 and the second contact portion 41 are projected from the other portions and are located closer to the horn 31. , The first sheet 11 and the second sheet 12 located on the first contact portion 40 and the second contact portion 41 are fused, and the first fusion portion 15 and the second fusion portion 16 for joining these sheets are fused. Is formed. At this time, the elastic member 13 is partially housed in the recess 42, and the elastic member 13 is not fused to either the first sheet 11 or the second sheet 12, and the non-bonded state is maintained. Has been done. By the fusion by the ultrasonic fusion portion 30, a part of the constituent fibers is melted between the pair of

first fusion portions

15a and 15b of the second sheet 12 to form a low porosity region 20, and the first sheet is formed. A second low porosity region 21 is formed between the pair of first fused

portions

15a and 15b of 11. By applying ultrasonic waves in this way, the stretchable sheet 10 in the form shown in FIG. 1 can be obtained.

In the obtained elastic sheet 10, when the stretched state of the elastic member 13 is released, the length of the elastic member 13 becomes shorter and the diameter thereof becomes larger. As shown in FIG. 2, the elastic member 13 having an increased diameter has a first fused portion interval D or more, which is an interval between the two first fused

portions

15a and 15b, and is preferably a first fused portion interval. Exceeds D. As a result, the elastic member 13 is sandwiched by the two first fused

portions

15a and 15b, and is fixed only by the friction between the first sheet 11 and the second sheet 12. Further, due to the fusion, a portion of the constituent fibers between the pair of

first fusion portions

15a and 15b of the second sheet 12 is melted and solidified as the temperature decreases. As a result, the shape of the elastic member 13 having an increased diameter on the second sheet 12 side and the shape of the second sheet 12 are maintained substantially flat between the pair of first fused

portions

15a and 15b. The degree of extension of the elastic member 13 and the opening width of the recess 42 along the Y direction at the time of manufacturing the elastic sheet 10 may be appropriately set according to the desired extension state of the elastic sheet 10.

When the first and

second sheets

11 and 12 and the elastic member 13 constituting the elastic sheet 10 and the elastic member 13 are housed in the recess 42, the degree of extension of the elastic member 13 is such that the elastic sheet 10 has desired extensibility ( Stretch rate) and is selected to have the desired folds. In the present manufacturing method, the degree of extension of the elastic member 13 can be adjusted by appropriately adjusting the depth and width of the recesses 42 (first fused portion interval D) and the like.
From the viewpoint of easily forming the low porosity region 20, when the laminated body is supplied to the ultrasonic fusion unit 30 which is a fusion device in the present manufacturing method, the first sheet 11 and the elastic member 13 in the laminated body It is preferable to adjust the depth and width of the recess 42 so that there is no gap between the second sheet 12 and the second sheet 12. From the same viewpoint as described above, the size of the recess 42 is preferably within the following range. The width c of the recess 42 (see FIG. 10) is preferably 1. The diameter a of the elastic member 13 in the extended state (see FIG. 10), assuming that the elastic member 13 fits in the recess 42 together with the first sheet 11. It is more than 0 times and 2.0 times or less. The diameter a (see FIG. 10) of the elastic member 13 in the extended state is preferably 1.1 times or more and 1.5 times or less, more preferably 1.2 times or more 1 of the depth b (see FIG. 10) of the recess 42. It is 5.5 times or less, more preferably 1.3 times or more and 1.5 times or less.

From the viewpoint of easily forming the low porosity region 20, the linear pressure of the horn 31, that is, the pressure applied to the laminate by pressing the horn 31 against the laminate is preferably 3 N / mm or more, more preferably 3 2. N / mm or more, preferably 4 N / mm or less, more preferably 3.8 N / mm or less, preferably 3 N / mm or more and 4 N / mm or less, more preferably 3.2 N / mm or more 3. It is 8 N / mm or less.

As described above, in this manufacturing method, after preheating the second sheet 12, ultrasonic vibration is applied to the second sheet 12. By preheating the second sheet 12 before applying the ultrasonic vibration to the second sheet 12, the present inventors melt the low porosity region 20 formed by the ultrasonic vibration and the elastic member 13. I found that I wouldn't wear it. The reason for this is considered to be that since the second sheet obtains thermal energy by preheating, it is possible to seal the elastic member 13 to the extent that it can be fixed from both sides by weaker ultrasonic vibration. Further, since the ultrasonic vibration is weak, the frictional heat between the fibers due to the ultrasonic vibration 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. it is conceivable that. On the other hand, when ultrasonic vibration is applied to the second sheet without preheating, the second sheet and the elastic member overlapping the second sheet are fused between the pair of fused

portions

15a and 15b. From the viewpoint of further suppressing the 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 described 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, and more preferably 95 ° C. to 130 ° C. lower. It is 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 (for example, melting point 163 ° C.), the preheating temperature of the second sheet 12 is 40 ° C. (with respect to the melting point-). It is preferably in the range of 123 ° C.) to 60 ° C. (melting point −103 ° C.). From the viewpoint of more easily preheating the second sheet 12, the temperature of the receiving roll 32 is preferably set in a 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 having 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 (for example, DSC6200 manufactured by Seiko Instruments, Inc.). Specifically, a thermal analysis of a fiber sample (1 mg) finely cut from any 10 points on the web or non-woven fabric is performed at a heating rate of 10 ° C./min, and the melting peak temperature of the fiber constituents to be measured is determined by the constituent fibers. Let it be the melting point of. When there are a plurality of melting peak temperatures, the lowest melting peak temperature among them is defined as the melting point of the constituent fibers.

The elastic sheet 10 thus obtained can be used as a constituent material of an absorbent article such as a disposable diaper and a sanitary napkin, and is particularly preferably used for forming an elastic portion of the absorbent article. Absorbent articles are mainly used for absorbing and retaining body fluids excreted from the body such as urine and menstrual blood. Absorbent articles include, but are not limited to, disposable diapers, sanitary napkins, incontinence pads, panty liners, etc., and broadly include articles used for absorbing liquid discharged from the human body. To do. The absorbent articles include, for example, an absorbent main body having a liquid-retaining absorbent body interposed between the front sheet, the back sheet, and both sheets, and an exterior body located on the non-skin facing surface side of the absorbent main body. Those having and are mentioned. As described above, the elastic sheet of the present invention is preferably used for an exterior body. When the exterior body contains the elastic sheet of the present invention, from the viewpoint of more reliably exerting the above-mentioned effect of separating sweat from the skin, in the elastic sheet, the first sheet 11 in the elastic sheet faces the skin. It is preferably arranged so as to be on the side, and more preferably arranged so as to be in contact with the wearer's skin. The "skin facing surface" is a surface of the absorbent article or its constituent members (for example, an absorber) that is directed toward the wearer's skin when the absorbent article is worn, that is, a side relatively close to the wearer's skin. .. The absorbent article may further include various members according to its specific use. Such members are known to those of skill in the art.

Although the present invention has been described above based on the preferred embodiment, the present invention is not limited to the above embodiment. For example, in the above-described embodiment, the pair of first fused

portions

15a and 15b and the second fused portion 16 are intermittently provided on the same straight line in the Y direction, but these fused

portions

15a , 15b, 16 may be continuous 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, but instead of this, a shape such as an oval shape, a circular shape, or a rhombus shape may be adopted.

Further, in the above embodiment, the case where the first sheet 11 is a hydrophilic sheet and the second sheet 12 is a hydrophobic sheet has been mainly described, but the present invention is not limited to this, and the first sheet 11 is hydrophobic. It is a sex sheet, and the second sheet 12 may be a hydrophilic sheet. Alternatively, both the first sheet 11 and the second sheet 12 may be hydrophilic sheets, or both may be hydrophobic sheets.
Further, in the above-described embodiment, the elastic sheet 10 has a plurality of elastic members 13, but the elastic sheet 10 may have one elastic member 13.
Further, in the elastic sheet 10 in the above embodiment, the first sheet 11 has the second low porosity region 21, but the elastic sheet 10 does not have to have the second low porosity region 21. For example, the first sheet 11 may have a region facing the second sheet 12 with the elastic member 13 interposed therebetween having the same porosity as the other regions described above.

With respect to the above-described embodiment, the present invention further discloses the following elastic sheet, an absorbent article including the same, and a method for producing the elastic sheet.
<1>
It has a first sheet made of a fiber sheet, a second sheet arranged opposite to the first sheet and made of a fiber sheet, and an elastic member arranged between both sheets in an extended state and extending in one direction. An elastic sheet having elasticity 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 with the elastic member interposed therebetween and formed at intervals along the extending direction of the elastic member. Ori
The elastic member is formed on the surface of the elastic member, the first sheet, and the space defined by the fused portion, the first sheet, and the second sheet located on both sides of the elastic member. It is fixed between both seats only by friction with the second seat,
When the elastic sheet is cross-sectionally viewed along a direction orthogonal to the extending direction of the elastic member at the forming position of the fused portion, the first sheet is more than the length in which the second sheet is in contact with the elastic member. The length in contact with the elastic member is longer,
When the elastic sheet is cross-sectionally viewed along a direction orthogonal to the extending direction of the elastic member at the forming position of the fused portion, the second sheet is formed inside in the thickness direction in the entire area between the fused portions. It has a low porosity region where the porosity between fibers is relatively lower than the other regions.
In the low porosity region, a stretchable sheet in which a part of the constituent fibers loses the fiber morphology and is in a melt-solidified state, and the rest of the constituent fibers maintains the fiber morphology.

<2>
When the elastic sheet is cross-sectionally viewed along a direction orthogonal to the extending direction of the elastic member at the formation position of the fusion portion, the portion of the elastic member on the first sheet side is the second elastic member. Compared to the part on the sheet side, the elastic sheet is raised outward in the thickness direction.
The elastic sheet according to <1>, wherein when the elastic member is bisected in the thickness direction in the same cross-sectional view, the second sheet side and the first sheet side of the elastic member have an asymmetrical shape. ..
<3>
In a cross-sectional view along a direction orthogonal to the extending direction of the elastic member, on the second sheet side of the elastic member, the portions between the fused portions located on both sides of the elastic member are other than between the fused portions. The elastic sheet according to <2>, which is a substantially flat portion as compared with the portion.
<4>
The above-mentioned <2> or <3>, wherein the surface on the second sheet side is substantially flat between the fused portions, while the surface on the first sheet side is raised outward in the thickness direction. Elastic sheet.
<5>
The elastic sheet according to any one of <1> to <4>, wherein the low porosity region has a shape that conforms to the shape of the elastic member.
<6>
When the elastic sheet is cross-sectionally viewed along a direction orthogonal to the extending direction of the elastic member at the formation position of the fusion portion, the surface of the second sheet facing the elastic member is in close contact with the elastic member. The elastic sheet according to any one of <1> to <5>.
<7>
The low porosity region is any one of the above <1> to <6>, which is in close contact with the surface of the elastic member facing the low porosity region and has a shape that follows the shape of the surface. The elastic sheet according to 1.
<8>
When the elastic sheet is viewed in cross section along the orthogonal direction and the low porosity region is viewed along the orthogonal direction, the difference between the maximum thickness and the minimum thickness in the low porosity region is 5 μm or less. The elastic sheet according to any one of <1> to <7>.
<9>
The elastic sheet according to any one of <1> to <8>, wherein the low porosity region and the elastic member are not fused to each other.
<10>
The elastic sheet according to any one of <1> to <9>, wherein the first sheet is a hydrophilic sheet.

<11>
The elastic sheet according to any one of <1> to <10>, wherein the second sheet is a hydrophobic sheet.
<12>
For the fused portions located on both sides of the elastic member, the distance between the side edge on the elastic member side in one fused portion and the side edge on the elastic member side in the other fused portion is defined as D. When the diameter of the elastic member in the relaxed state of the elastic sheet is d2, the value of d2 / D is 1.1 or more, preferably 1.2 or more, more preferably 1.3 or more. The elastic sheet according to any one of 1> to <11>.
<13>
The elastic sheet according to any one of <1> to <12>, 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. ..
<14>
The elasticity according to any one of <1> to <13>, wherein the distance Lf between adjacent fused portions in the extending direction of the elastic member is 6 mm or less, preferably 5 mm or less, more preferably 3 mm or less. Sheet.
<15>
The elastic sheet according to any one of <1> to <14>, wherein the length of the fused portion along the extending direction of the elastic member is 3 mm or less, preferably 2 mm or less, more preferably 1 mm or less. ..
<16>
The elastic sheet according to any one of <1> to <15>, wherein the fineness of the elastic member in the relaxed state of the elastic sheet is 155 dtex or more and 1240 dtex or less, preferably 310 dtex or more and 940 dtex or less.
<17>
Another fusion portion for joining the first sheet and the second sheet is arranged between the adjacent elastic members and the fusion portions adjacent to each other in the orthogonal direction. The elastic sheet according to any one of <1> to <16>.
<18>
When the distance between the adjacent elastic members is Le and the length of the other fused portion along the orthogonal direction is L16, the value of L16 / Le is 0.25 or more, preferably 0.50 or more, and more. The elastic sheet according to <17>, which is preferably 0.70 or more.
<19>
The elastic sheet according to <17> or <18>, wherein the length of the other fused portion along the extending direction of the elastic member is 3 mm or less, preferably 2 mm or less, more preferably 1 mm or less.
<20>
The elastic sheet according to any one of <1> to <19>, wherein the first sheet has a plurality of regions having different porosities between the fused portions.

<21>
The first sheet has a region having a relatively high porosity and a region having a relatively low porosity among the plurality of regions.
The elastic sheet according to <20>, wherein the region having a relatively low porosity forms a portion that comes into contact with the skin.
<22>
The first sheet has a region having a relatively high porosity and a region having a relatively low porosity among the plurality of regions.
The elastic sheet according to <20> or <21>, wherein the region having a relatively low porosity is located at the center of the fused portions in the orthogonal direction.
<23>
The first sheet has a region having a relatively high porosity and a region having a relatively low porosity among the plurality of regions.
The region having a relatively low porosity has a length in the orthogonal direction equal to or longer than the length in the orthogonal direction of the region having a relatively high porosity, said <20>. The elastic sheet according to any one of <22>.
<24>
The first sheet has a region having a relatively high porosity and a region having a relatively low porosity among the plurality of regions.
The length of the region having a relatively low porosity in the orthogonal direction is 100% or more, preferably 120% or more, with respect to the length of the region having a relatively high porosity in the orthogonal direction. The elastic sheet according to any one of <20> to <23>, which is 200% or less, preferably 150% or less.
<25>
The first sheet has a region having a relatively high porosity and a region having a relatively low porosity among the plurality of regions.
The expansion / contraction according to any one of <20> to <24>, wherein the difference between the region having a relatively high porosity and the region having a relatively low porosity is 30% or more. Sex sheet.
<26>
The stretchability according to any one of <1> to <25>, wherein a convex portion is formed on the first sheet along the thickness direction of the stretchable sheet in a direction away from the elastic member. Sheet.
<27>
The elastic sheet according to any one of <1> to <26>, wherein convex portions projecting apart from each other along the thickness direction are formed on the first sheet and the second sheet, respectively.
<28>
The convex portion is a portion different from the portion along the shape of the elastic member at a position where the first sheet and the second sheet overlap the elastic member, and continuously extends along the orthogonal direction. The elastic sheet according to <26> or <27>, wherein a plurality of folds are formed by the convex portions.
<29>
Non-woven fabric is used as the first sheet and the second sheet.
The elasticity according to any one of <1> to <28>, wherein the basis weight of the non-woven fabric is 5 g / m ² or more and 50 g / m ² or less, preferably 8 g / m ² or more and 30 g / m ² or less. Sheet.
<30>
The elasticity according to <29>, wherein the buckling strength of the non-woven fabric is 50 cN or less, preferably 30 cN or less in the direction orthogonal to the machine flow direction, and 70 cN or less, preferably 50 cN or less in the machine flow direction. Sheet.

<31>
The stretchable sheet according to any one of <1> to <30>, wherein the first sheet and the second sheet are two separate sheets in the stretchable sheet.
<32>
In the elastic sheet, the first sheet and the second sheet are formed by bending one sheet to form two opposing surfaces, and a portion constituting one surface constitutes the first sheet and the other surface. The elastic sheet according to any one of <1> to <30>, wherein the portion to be formed is the second sheet.
<33>
An absorbent article composed of an absorbent body and an exterior body located on the non-skin facing surface side of the absorbent body.
An absorbent article in which the exterior body includes the elastic sheet according to any one of <1> to <32>.
<34>
The absorbent article according to <33>, wherein the second sheet in the elastic sheet is arranged so as to face the wearer's skin.
<35>
The absorbent article according to <33>, wherein the second sheet in the elastic sheet is arranged so as to face the clothing side.

As described in detail above, according to the present invention, there is provided an elastic sheet and an absorbent article having an excellent effect of separating sweat from the skin.

Claims

It has a first sheet made of a fiber sheet, a second sheet arranged opposite to the first sheet and made of a fiber sheet, and an elastic member arranged between both sheets in an extended state and extending in one direction. An elastic sheet having elasticity 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 with the elastic member interposed therebetween and formed at intervals along the extending direction of the elastic member. Ori
The elastic member is formed on the surface of the elastic member, the first sheet, and the space defined by the fused portion, the first sheet, and the second sheet located on both sides of the elastic member. It is fixed between both seats only by friction with the second seat,
When the elastic sheet is cross-sectionally viewed along a direction orthogonal to the extending direction of the elastic member at the forming position of the fused portion, the first sheet is more than the length in which the second sheet is in contact with the elastic member. The length in contact with the elastic member is longer,
When the elastic sheet is cross-sectionally viewed along a direction orthogonal to the extending direction of the elastic member at the forming position of the fused portion, the second sheet is formed inside in the thickness direction in the entire area between the fused portions. It has a low porosity region where the porosity between fibers is relatively lower than the other regions.
In the low porosity region, a stretchable sheet in which a part of the constituent fibers loses the fiber morphology and is in a melt-solidified state, and the rest of the constituent fibers maintains the fiber morphology.
When the elastic sheet is cross-sectionally viewed along a direction orthogonal to the extending direction of the elastic member at the formation position of the fusion portion, the portion of the elastic member on the first sheet side is the second elastic member. Compared to the part on the sheet side, the elastic sheet is raised outward in the thickness direction.
The elastic sheet according to claim 1, wherein when the elastic member is bisected in the thickness direction in the same cross-sectional view, the second sheet side and the first sheet side of the elastic member have an asymmetrical shape.
In a cross-sectional view along a direction orthogonal to the extending direction of the elastic member, on the second sheet side of the elastic member, the portions between the fused portions located on both sides of the elastic member are other than between the fused portions. The elastic sheet according to claim 2, which is a substantially flat portion as compared with the portion.
The stretchable sheet according to claim 2 or 3, wherein the surface on the second sheet side is substantially flat between the fused portions, while the surface on the first sheet side is raised outward in the thickness direction. ..
The elastic sheet according to any one of claims 1 to 4, wherein the low porosity region has a shape that conforms to the shape of the elastic member.
When the elastic sheet is cross-sectionally viewed along a direction orthogonal to the extending direction of the elastic member at the forming position of the fused portion, the surface of the second sheet facing the elastic member is in close contact with the elastic member. The elastic sheet according to any one of claims 1 to 5.
The low porosity region is in close contact with the surface of the elastic member facing the low porosity region, and has a shape that follows the shape of the surface, according to any one of claims 1 to 6. The elastic sheet described.
When the elastic sheet is viewed in cross section along the orthogonal direction and the low porosity region is viewed along the orthogonal direction, the difference between the maximum thickness and the minimum thickness in the low porosity region is 5 μm or less. The elastic sheet according to any one of claims 1 to 7.
The elastic sheet according to any one of claims 1 to 8, wherein the low porosity region and the elastic member are not fused to each other.
The elastic sheet according to any one of claims 1 to 9, wherein the first sheet is a hydrophilic sheet.
The elastic sheet according to any one of claims 1 to 10, wherein the second sheet is a hydrophobic sheet.
For the fused portions located on both sides of the elastic member, the distance between the side edge on the elastic member side in one fused portion and the side edge on the elastic member side in the other fused portion is defined as D. The elastic sheet according to any one of claims 1 to 11, wherein the value of d2 / D is 1.1 or more when the diameter of the elastic member in the relaxed state of the elastic sheet is d2.
The elastic sheet according to any one of claims 1 to 12, wherein the distance Le between adjacent elastic members is 1 mm or more and 10 mm or less.
The elastic sheet according to any one of claims 1 to 13, wherein the distance Lf between the fused portions adjacent to each other in the extending direction of the elastic member is 6 mm or less.
The elastic sheet according to any one of claims 1 to 14, wherein the length of the fused portion along the extending direction of the elastic member is 3 mm or less.
The stretchable sheet according to any one of claims 1 to 15, wherein the fineness of the elastic member in the relaxed state of the stretchable sheet is 155 dtex or more and 1240 dtex or less.
A claim that another fusion portion for joining the first sheet and the second sheet is arranged between the adjacent elastic members and the fusion portions adjacent to each other in the orthogonal direction. Item 2. The elastic sheet according to any one of Items 1 to 16.
The 17th aspect of the present invention, wherein the value of L16 / Le is 0.25 or more when the distance between the adjacent elastic members is Le and the length of the other fused portion along the orthogonal direction is L16. Elastic sheet.
The elastic sheet according to claim 17 or 18, wherein the length of the other fused portion along the extending direction of the elastic member is 3 mm or less.
The elastic sheet according to any one of claims 1 to 19, wherein the first sheet has a plurality of regions having different porosities between the fused portions.
The first sheet has a region having a relatively high porosity and a region having a relatively low porosity among the plurality of regions.
The stretchable sheet according to claim 20, wherein the region having a relatively low porosity forms a portion that comes into contact with the skin.
The first sheet has a region having a relatively high porosity and a region having a relatively low porosity among the plurality of regions.
The stretchable sheet according to claim 20 or 21, wherein the region having a relatively low porosity is located at the center of the fused portions in the orthogonal direction.
The first sheet has a region having a relatively high porosity and a region having a relatively low porosity among the plurality of regions.
20 to 20 to claim that the region having a relatively low porosity has a length in the orthogonal direction equal to or longer than the length in the orthogonal direction of the region having a relatively high porosity. The elastic sheet according to any one of 22.
The first sheet has a region having a relatively high porosity and a region having a relatively low porosity among the plurality of regions.
The length of the region having a relatively low porosity in the orthogonal direction is 100% or more and 200% or less with respect to the length of the region having a relatively high porosity in the orthogonal direction. The elastic sheet according to any one of 20 to 23.
The first sheet has a region having a relatively high porosity and a region having a relatively low porosity among the plurality of regions.
The elastic sheet according to any one of claims 20 to 24, wherein the difference between the region having a relatively high porosity and the region having a relatively low porosity is 30% or more. ..
The stretchable sheet according to any one of claims 1 to 25, wherein a convex portion is formed on the first sheet so as to project in a direction away from the elastic member along the thickness direction of the stretchable sheet.
The elastic sheet according to any one of claims 1 to 26, wherein the first sheet and the second sheet each have convex portions protruding so as to be separated from each other along the thickness direction.
The convex portion is a portion different from the portion along the shape of the elastic member at a position where the first sheet and the second sheet overlap the elastic member, and continuously extends along the orthogonal direction. The elastic sheet according to claim 26 or 27, wherein a plurality of folds are formed by the protrusions.
Non-woven fabric is used as the first sheet and the second sheet.
The elastic sheet according to any one of claims 1 to 28, wherein the nonwoven fabric has a basis weight of 5 g / m 2 or more and 50 g / m 2 or less.
The elastic sheet according to claim 29, wherein the buckling strength of the non-woven fabric is 50 cN or less in the direction orthogonal to the machine flow direction and 70 cN or less in the machine flow direction.
The stretchable sheet according to any one of claims 1 to 30, wherein the first sheet and the second sheet in the stretchable sheet are two separate sheets.
In the elastic sheet, the first sheet and the second sheet are formed by bending one sheet to form two opposing surfaces, and a portion constituting one surface constitutes the first sheet and the other surface. The elastic sheet according to any one of claims 1 to 30, wherein the portion to be formed is the second sheet.
An absorbent article composed of an absorbent body and an exterior body located on the non-skin facing surface side of the absorbent body.
An absorbent article, wherein the exterior body includes the elastic sheet according to any one of claims 1 to 32.
The absorbent article according to claim 33, wherein the second sheet in the elastic sheet is arranged so as to face the wearer's skin.
The absorbent article according to claim 33, wherein the second sheet of the elastic sheet is arranged so as to face the clothing side.