A stretchable sheet, and a pant-type absorbent article equipped with the stretchable sheet.

Abstract

To provide an elastic sheet in which the elasticity of the elastic material is not easily inhibited. [Solution] An expandable sheet 2 having a first direction D1 and a second direction D2 that are orthogonal to each other, wherein the expandable sheet 2 comprises a first sheet 21 having heat-weldability, a second sheet 23 having heat-weldability, and a plurality of elastic members 25 extending in the first direction D1 and spaced apart in the second direction D2 between them, wherein at least a portion of the plurality of elastic members 25 is (i) arranged in a state stretched in the first direction D1 with a stretch ratio of 2.8 to 4.0 times, (ii) welded part pairs 31 that weld the first sheet 21 and the second sheet 23, which are arranged at both ends of the second direction D2, are fixed in a state where they are sandwiched between a plurality of welded part groups 35 spaced apart in the first direction D1, and (iii) has a breaking elongation of 7.0 times or more in a tensile test at 100°C.

Description

Technical Field

[0001] The present disclosure relates to a stretchable sheet and a pant-type absorbent article including the stretchable sheet.

Background Art

[0002] Regarding an improvement of a stretchable sheet having a first direction and a second direction orthogonal to each other, and including a first sheet, a second sheet, and a plurality of elastic members disposed therebetween, extending in the first direction and spaced apart in the second direction, in which the plurality of elastic members are disposed in a stretched state in the first direction and a pair of welding parts for welding the first sheet and the second sheet disposed at both ends in the second direction are fixed in a state of being sandwiched by a group of welding parts spaced apart in the first direction (hereinafter sometimes referred to as "conventional welded stretchable sheet"), studies have been conducted.

[0003] For example, Patent Document 1 discloses a stretchable sheet including a pair of sheets 1 and 2 whose first surfaces 1f and 2f face or contact each other, a plurality of elastic members F disposed between the first surfaces 1f and 2f of the pair of sheets 1 and 2 and spaced apart from each other, the pair of sheets 1 and 2 being joined in a welded structure to each other without an adhesive on the first surfaces 1f and 2f of the pair of sheets 1 and 2, holding the elastic members F, extending in a direction Dp intersecting the stretching direction Df of the elastic members F, and a plurality of joining parts 3 spaced apart from each other in the stretching direction Df between the adjacent elastic members F, and a plurality of folds P appearing between the plurality of joining parts 3 in a state where the elastic members F are contracted. Each joining part 3 includes a plurality of strong joining parts 3s disposed on both sides of the elastic members F in the intersecting direction Dp, and weak joining parts 3w disposed between adjacent elastic members F among the elastic members F and between adjacent strong joining parts 3s among the plurality of strong joining parts 3s. The joining strength between the pair of sheets 1 and 2 in the weak joining part 3w is smaller than the joining strength between the pair of sheets 1 and 2 in the strong joining part 3s.

[0004] Patent Document 2 discloses a method for forming an expandable portion, which involves stretching a plurality of elongated elastic members in the longitudinal direction and sandwiching them parallel to each other between an inner sheet and an outer sheet, joining the inner sheet and the outer sheet near both ends in the width direction of each elastic member, releasing the tension applied to the elastic members to expand their diameter by contraction, and then sandwiching and fixing the elastic members between a joint near one end in the width direction and a joint near the other end in the width direction of the elastic member, characterized in that the distance between the joint near one end in the width direction and the joint near the other end in the width direction of some elastic members is made different from the distance between the joint near one end in the width direction and the joint near the other end in the width direction of other elastic members. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2018 / 070158 [Patent Document 2] Japanese Patent Publication No. 2009-056156 [Overview of the project] [Problems that the invention aims to solve]

[0006] Patent documents 1 and 2 do not disclose the stretchable sheet described herein. This disclosure aims to provide an elastic sheet in which the elasticity of the elastic member is less likely to be inhibited. [Means for solving the problem]

[0007] The Disclosers present a stretchable sheet having a first and second direction that are orthogonal to each other, The above-mentioned stretchable sheet comprises a first sheet having heat-welding properties, a second sheet having heat-welding properties, and a plurality of elastic members extending in a first direction and spaced apart in a second direction between the first and second sheets, wherein at least a portion of the plurality of elastic members is (i) arranged in a state stretched in the first direction with an elongation ratio of 2.8 to 4.0 times, (ii) welded parts pairs that weld the first and second sheets together, located at both ends in the second direction, are fixed in a state of being compressed between a plurality of welded parts spaced apart in the first direction, and (iii) has a breaking elongation of 7.0 times or more in a tensile test at 100°C. [Effects of the Invention]

[0008] The elastic sheet relating to this disclosure is less susceptible to inhibition of elasticity. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a diagram illustrating a stretchable sheet 2 and a disposable diaper 1 according to the first embodiment. [Figure 2] Figure 2 is a diagram illustrating the stretchable sheet 2 and disposable diaper 1 according to the first embodiment. [Figure 3] Figure 3 is a diagram illustrating the stretchable sheet 2 and disposable diaper 1 according to the first embodiment. [Figure 4] Figure 4 is a diagram illustrating the stretchable sheet 2 and disposable diaper 1 according to the first embodiment. [Figure 5] Figure 5 is a diagram illustrating the stretchable sheet 2 and disposable diaper 1 according to the first embodiment. [Modes for carrying out the invention]

[0010] Specifically, this disclosure relates to the following aspects: [Aspect 1] A stretchable sheet having a first direction and a second direction that are orthogonal to each other, The above-mentioned stretchable sheet comprises a first sheet having heat-welding properties, a second sheet having heat-welding properties, and a plurality of elastic members that extend in a first direction and are spaced apart in a second direction between the first and second sheets. At least some of the above-mentioned multiple elastic members are (i) It is installed in a state where it is extended in the first direction with an extension ratio of 2.8 to 4.0 times, (ii) The welding portion pairs that weld the first sheet and the second sheet, which are located at both ends in the second direction, are fixed in a state of being sandwiched between multiple welding portion groups that are spaced apart in the first direction. (iii) Having a breaking elongation of 7.0 times or more in a tensile test at 100°C, A stretchable sheet characterized by the following features.

[0011] In stretchable sheets, arranging elastic members at a high stretch ratio is preferable from the viewpoint of increasing the stretchability of the stretchable sheet and reducing the amount of elastic members used. Furthermore, using a highly elastic stretchable sheet in pant-type absorbent garments is preferable from the following viewpoints. For example, in pant-type absorbent garments, the wearer's posture changes (standing, sitting, lying down, etc.), and the weight of the garment increases as it absorbs bodily fluids. By using a highly elastic stretchable sheet, the shifting of the garment can be suppressed. In addition, by using a highly elastic stretchable sheet in pant-type absorbent garments, the wearer's size range can be expanded, reducing wearer dissatisfaction with the size.

[0012] Generally, in the production of a stretchable sheet, an elastic member is disposed in a state of being stretched in a first direction at a high draw ratio, and when forming a pair of welding portions at both ends of the elastic member stretched at the high draw ratio in a second direction, if the elastic member is sandwiched between a roll provided with a plurality of protrusions and an anvil roll using a welding device, the elastic member tends to be partially or entirely broken. In this specification, when forming a pair of welding portions, sandwiching the elastic member between the protrusions of the welding device and the anvil roll may be simply referred to as "sandwiching of the elastic member by the welding device". Also, when forming a pair of welding portions, the portion of the elastic member sandwiched between the protrusions of the welding device and the anvil roll may be simply referred to as "sandwiched portion of the elastic member".

[0013] However, in the above stretchable sheet, although at least a part of the elastic member is disposed in a state of being stretched in the first direction at a predetermined draw ratio, since the elastic member has a predetermined elongation at break in a tensile test at 100°C, even when sandwiching of the elastic member by the welding device occurs and the elastic member is partially compressed and heated by the protrusions and the anvil roll, the sandwiched portion of the elastic member is less likely to break. As a result, in the above stretchable sheet, the elasticity of the elastic member is less likely to be inhibited.

[0014] [Aspect 2] At least a part of the plurality of elastic members further has a tensile strength at 3.0-fold elongation of 0.58 to 0.78 mN / dtex in the tensile test at 100°C, in the stretchable sheet according to Aspect 1.

[0015] The above stretchable sheet has a predetermined tensile strength at 3.0-fold elongation in a tensile test at 100°C. Therefore, even when sandwiching of the elastic member by the welding device occurs, the sandwiched portion of the elastic member is less likely to lose its elasticity and is more likely to function as an elastic member. As a result, in the above stretchable sheet, the elasticity of the elastic member is less likely to be inhibited. Furthermore, since the first and second sheets are not welded together in the portion where the elastic member is sandwiched, the portion where the elastic member is sandwiched can exhibit elasticity after welding by the welding device is completed.

[0016] [Aspect 3] The stretchable sheet according to embodiment 1 or 2, wherein at least a portion of the above-mentioned multiple elastic members further has a tensile strength of 0.90 to 1.30 mN / dtex when stretched 5.0 times in the above-mentioned tensile test at 100°C.

[0017] The above-mentioned stretchable sheet has a tensile strength of 5.0 times its predetermined length in a tensile test at 100°C. Therefore, even if the elastic member is pinched by the welding device, the pinched portion of the elastic member is less likely to lose its elasticity, and it will function more easily as an elastic member. As a result, the elasticity of the elastic member is less likely to be inhibited in the above-mentioned stretchable sheet.

[0018] [Aspect 4] A stretchable sheet having a first direction and a second direction that are orthogonal to each other, The above-mentioned stretchable sheet comprises a first sheet having heat-welding properties, a second sheet having heat-welding properties, and a plurality of elastic members that extend in a first direction and are spaced apart in a second direction between the first and second sheets. At least some of the above-mentioned multiple elastic members are (i) It is arranged in an extended state in the first direction and has a fineness of 60 to 470 dtex, (ii) The pair of welded parts located at both ends in the second direction are fixed in a state of being sandwiched between multiple groups of welded parts located spaced apart in the first direction. (iii) Having a breaking elongation of 7.0 times or more in a tensile test at 100°C, A stretchable sheet characterized by the following features.

[0019] A stretchable sheet equipped with thin elastic components is preferable from the standpoint of skin feel because it reduces contact with the skin. Generally, in the manufacture of stretchable sheets, when thin elastic members are arranged in a state where they are stretched in a first direction, and when a pair of welded parts is formed at both ends of the stretched elastic members, if the elastic members are pinched by the welding equipment, the pinched portion of the elastic members tends to break easily.

[0020] However, in the above-mentioned stretchable sheet, although at least a portion of the elastic member is thin with a predetermined fineness, since the elastic member has a predetermined elongation at break in a tensile test at 100°C, even if the elastic member is pinched by the welding device and partially compressed and heated by the protruding portion and anvil roll, the pinched portion of the elastic member is less likely to break. As a result, the elasticity of the elastic member in the above-mentioned stretchable sheet is less likely to be inhibited. Furthermore, since the above-mentioned stretchable sheet is equipped with a predetermined thin elastic component, the stretchable sheet has a superior feel against the skin.

[0021] [Aspect 5] The stretchable sheet according to embodiment 4, wherein at least a portion of the above-mentioned multiple elastic members further has a tensile strength of 0.58 to 0.78 mN / dtex at 3.0 times elongation in the above-mentioned tensile test at 100°C.

[0022] The above-mentioned stretchable sheet has a tensile strength of 3.0 times its predetermined length in a tensile test at 100°C. Therefore, even if the elastic member is pinched by the welding device, the pinched portion of the elastic member is less likely to lose its elasticity, and it will function more easily as an elastic member. As a result, the elasticity of the elastic member is less likely to be inhibited in the above-mentioned stretchable sheet.

[0023] [Aspect 6] The stretchable sheet according to embodiment 4 or 5, wherein at least some of the above-mentioned multiple elastic members further have a tensile strength of 0.90 to 1.30 mN / dtex when stretched 5.0 times in the above-mentioned tensile test at 100°C.

[0024] The above-mentioned stretchable sheet has a tensile strength of 5.0 times its predetermined length in a tensile test at 100°C. Therefore, even if the elastic member is pinched by the welding device, the pinched portion of the elastic member is less likely to lose its elasticity, and it will function more easily as an elastic member. As a result, the elasticity of the elastic member is less likely to be inhibited in the above-mentioned stretchable sheet.

[0025] [Aspect 7] An elastic sheet according to any one of embodiments 1 to 6, wherein at least a portion of the above-mentioned multiple elastic members has a breaking elongation of 6.0 times or more in a tensile test at 50°C.

[0026] In the above-described stretchable sheet, at least some of the multiple elastic members have a predetermined elongation at break in a tensile test at 50°C. Therefore, even if the first and / or second sheets around the protruding part of the welding device tend to soften during the manufacturing of the stretchable sheet, and the stretch ratio of the elastic members becomes uneven within the group of welded parts, this unevenness in stretch ratio is easily corrected, and the stretch ratio of the elastic members tends to become uniform among the group of welded parts.

[0027] [Aspect 8] An elastic sheet according to any one of embodiments 1 to 7, wherein at least a portion of the above-mentioned multiple elastic members further has a tensile strength of 0.70 to 1.10 mN / dtex at 3.0 times elongation in a tensile test at 50°C.

[0028] In the above-described stretchable sheet, at least some of the multiple elastic members have a predetermined tensile strength when stretched to 3.0 times their original length in a tensile test at 50°C. Therefore, during the manufacture of the stretchable sheet, the first and / or second sheets around the protruding part of the welding device tend to soften easily, making them less likely to lose elasticity even when subjected to temperatures higher than room temperature, and thus easier to function as elastic members. As a result, the elasticity of the elastic members in the above-described stretchable sheet is less likely to be inhibited.

[0029] [Aspect 9] An elastic sheet according to any one of embodiments 1 to 8, wherein at least a portion of the above-mentioned multiple elastic members further has a tensile strength of 1.55 to 2.25 mN / dtex at 5.0 times elongation in a tensile test at 50°C.

[0030] In the above-described stretchable sheet, at least some of the multiple elastic members have a predetermined tensile strength when stretched to 5.0 times their original length in a tensile test at 50°C. Therefore, during the manufacture of the stretchable sheet, the first and / or second sheets around the protruding part of the welding device tend to soften easily, making them less likely to lose elasticity even when subjected to temperatures higher than room temperature, and thus easier to function as elastic members. As a result, the elasticity of the elastic members in the above-described stretchable sheet is less likely to be inhibited.

[0031] [Aspect 10] An elastic sheet according to any one of embodiments 1 to 9, wherein at least a portion of the above-mentioned multiple elastic members is a multifilament comprising multiple single threads.

[0032] In the above-described stretchable nonwoven fabric, at least a portion of the multiple elastic members are multifilaments. Therefore, even if the elastic members are pinched by the welding device, the voids in the multifilaments provide a buffering function, making it less likely for the single threads constituting the multifilaments to break at the pinched portion of the elastic members. As a result, the elasticity of the elastic members in the above-described stretchable sheet is less likely to be inhibited.

[0033] [Aspect 11] The above multifilament is twisted, as described in embodiment 10, in the stretchable sheet.

[0034] In the above-described stretchable sheet, at least a portion of the multiple elastic members are multifilaments and are twisted. Therefore, even if the elastic members are pinched by the welding device, the multiple single filaments are less likely to unravel, and the pinched portion of the elastic member can easily escape from between the protruding part of the welding device and the anvil roll. As a result, the elasticity of the elastic members in the above-described stretchable sheet is less likely to be inhibited.

[0035] [Aspect 12] The above multifilament is an expandable sheet according to embodiment 10 or 11, having a porosity of 15.0 to 30.0%.

[0036] In the above-described stretchable nonwoven fabric, at least a portion of the multiple elastic members are multifilaments having a predetermined porosity. Therefore, even if the elastic members are pinched by the welding device, the voids with the above-described porosity in the multifilaments provide a buffering function, making it difficult for the single threads constituting the multifilaments to break at the pinched portion of the elastic members. As a result, the elasticity of the elastic members in the stretchable sheet is less likely to be inhibited. Furthermore, in the case of conformance to embodiment 10, that is, when the multifilament is twisted, it is preferable that the multifilament has the above void ratio. This is because if the void ratio is increased by reducing the twist, the single filaments tend to unravel easily, and in the sandwiched portion of the elastic member, the single filaments separate, impairing the elasticity of the elastic member and potentially causing the elastic member to break partially or completely. Conversely, if the void ratio is reduced, the cushioning function in the sandwiched portion of the elastic member tends to be insufficient, making the elastic member more prone to breaking.

[0037] [Aspect 13] The stretchable sheet according to any one of embodiments 1 to 12, wherein the plurality of elastic members include two or more elastic members having at least one different fineness and stretch ratio.

[0038] In conventional welded stretchable sheets, when manufacturing stretchable sheets with different fineness and stretch ratios of elastic members, it is necessary to change the spacing between a pair of joints, as disclosed in Patent Document 2. This requires changing the arrangement of the multiple protrusions in the stretchable sheet manufacturing apparatus, specifically, in a welding apparatus that includes a roll with multiple protrusions and an anvil roll.

[0039] The above-mentioned stretchable sheet includes multiple elastic members, each containing two or more elastic members with different fineness or stretch ratios. However, in the above-mentioned stretchable sheet, at least a portion of the multiple elastic members are predetermined, so even if the elastic members are pinched by the welding device, the pinched portion of the elastic members is less likely to break. Therefore, the stretchability of the elastic members is less likely to be hindered even without changing the roll equipped with multiple protrusions in the welding device. Furthermore, the above-mentioned stretchable sheet can be made to have a preferred elasticity depending on the application of the stretchable sheet.

[0040] [Aspect 14] An elastic sheet according to any one of embodiments 1 to 13, wherein at least a portion of the above-mentioned multiple elastic members contains titanium oxide in an amount of less than 3.0% by mass.

[0041] In the above-described stretchable sheet, at least a portion of the multiple elastic members contain a predetermined amount of titanium oxide, so that the surface of the elastic members has multiple protrusions due to the titanium oxide particles. Consequently, the contact area between the first sheet and the second sheet and the elastic members is reduced, and even if the elastic members are pinched by the welding device, the pinched portion of the elastic members can easily escape from between the protrusions of the welding device and the anvil roll. As a result, the elasticity of the elastic members in the above-described stretchable sheet is less likely to be inhibited. In addition, by including a predetermined amount of titanium oxide, it is possible to suppress the elastic members from becoming too hard and to suppress the pinched portion of the elastic members from fracturing starting from the titanium oxide particles.

[0042] [Aspect 15] An elastic sheet according to any one of embodiments 1 to 14, wherein at least a portion of the above-mentioned multiple elastic members contains 0.05 to 5.0% by mass of an oil agent.

[0043] In the above-described stretchable sheet, at least some of the multiple elastic members contain a predetermined amount of lubricant. Therefore, friction between the first sheet and the second sheet and the elastic members is reduced, and even if the elastic members are pinched by the welding device, the pinched portion of the elastic member can easily escape from between the protruding part of the welding device and the anvil roll. As a result, the elasticity of the elastic members in the above-described stretchable sheet is less likely to be inhibited.

[0044] [Aspect 16] In the state in which the above-mentioned stretchable sheet is stretched, each of the plurality of elastic members has an inter-welded portion pair region that is partitioned by two welded portion pairs that are continuous in the first direction, At least a portion of the above-mentioned plurality of elastic members has at least two consecutive non-fractured regions between welded pairs in a first direction, where the region between the welded pairs is demarcated to a region where at least a portion of the elastic member does not have a fractured portion. An elastic sheet as described in any one of the descriptions 1 to 15.

[0045] In the above-described stretchable sheet, at least a portion of the multiple elastic members have at least two consecutive non-breaking regions between predetermined welded pairs in the first direction, so that the elasticity of the elastic members is less likely to be hindered in the stretchable sheet.

[0046] [Aspect 17] The stretchable sheet according to any one of embodiments 1 to 16, wherein at least a portion of the plurality of elastic members has a flattened portion, and the flattened portion has an outer diameter smaller than the distance between the welded portion pairs when the stretchable sheet is stretched.

[0047] In the above-described stretchable sheet, at least some of the multiple elastic members have a predetermined flattened portion. This flattened portion originates from the sandwiched portion of the elastic member, but since the flattened portion can pass through the welded pair, it does not easily hinder the expansion and contraction of the elastic member. As a result, the elasticity of the elastic member is less likely to be hindered in the above-described stretchable sheet.

[0048] [Aspect 18] A pant-type absorbent article comprising an elastic sheet as described in any one of embodiments 1 to 17. In the above-described pant-type absorbent article, similar to embodiment 1, the elasticity of the elastic member in the stretchable sheet is less likely to be inhibited.

[0049] [Aspect 19] The above-mentioned pant-type absorbent article comprises a waist section, a side seal section, and a waist-circumferential direction. The above-mentioned stretchable sheet is positioned in the side seal portion such that the first direction and the body circumference direction coincide. The pant-type absorbent article described in embodiment 18.

[0050] In the above-described pant-type absorbent product, the stretchable sheet is positioned in a predetermined direction on the side seal portion. Therefore, in the above-described pant-type absorbent product, the waist portion fits the wearer's waist and is less likely to slip down.

[0051] The stretchable sheet and the pant-type absorbent article equipped with the stretchable sheet described herein will be described in detail below. Figures 1 to 5 illustrate a disposable diaper 1 equipped with a stretchable sheet 2 according to an embodiment of the present disclosure. Specifically, Figure 1 is a perspective view of a three-piece type disposable diaper 1. Figure 2 is an unfolded view of the disposable diaper 1. Figure 3 is a plan view of the ventral portion 3 as seen from the skin side. Figure 4 is a partially enlarged view of the ventral portion 3 shown in Figure 3, with the elastic member in its natural state. Figure 5 is a partially enlarged view of the ventral portion 3 shown in Figure 3, with the elastic member 25 in a stretched state.

[0052] Disposable diaper 1, in its unfolded state as shown in Figure 1, has a height direction HD and a waist direction WD, and in its unfolded state as shown in Figure 2, it has a longitudinal direction L, a width direction W, and a thickness direction (not shown) which are orthogonal to each other. The width direction W corresponds to the waist direction WD. The stretchable sheet also has a first direction D1 and a second direction D2 which coincide with the width direction W and the longitudinal direction L, respectively.

[0053] In this specification, when referring to the disposable diaper 1, the height direction HD and the waist direction WD refer to the disposable diaper 1 in its unfolded state, and when referring to the longitudinal direction L, the width direction W, and the thickness direction, the disposable diaper 1 refers to the disposable diaper 1 in its unfolded state.

[0054] The disposable diaper 1 comprises an abdominal portion 3 made of an elastic sheet 2, a dorsal portion 7 made of an elastic sheet 2, and an absorbent body 101 positioned between the abdominal portion 3 and the dorsal portion 7. The abdominal portion 3 has a first abdominal end 5a and a second abdominal end 5b positioned at both ends in the width direction W, and the dorsal portion 7 has a first dorsal end 9a and a second dorsal end 9b positioned at both ends in the width direction W. The first abdominal end 5a and the first dorsal end 9a are connected by a side seal portion 11, and the second abdominal end 5b and the second dorsal end 9b are connected by a side seal portion 11, thereby forming a waist portion 13. The absorbent body 101 forms the crotch area 15.

[0055] The absorbent body 101 comprises a liquid-permeable top sheet 103, a liquid-impermeable back sheet 105, an absorbent material 107 between the top sheet 103 and the back sheet 105, an elastic member 109, and a three-dimensional gather 113 with an elastic member 111. However, since this structure is known in the art, a detailed explanation will be omitted.

[0056] The ventral portion 3 is composed of a first nonwoven fabric 21 with heat-sealing properties positioned on the skin side, a second nonwoven fabric 23 with heat-sealing properties positioned on the non-skin side, and a plurality of elastic members 25 positioned between the first nonwoven fabric 21 and the second nonwoven fabric 23. Each of the plurality of elastic members 25 extends in the width direction W and is positioned spaced apart in the longitudinal direction L.

[0057] As shown in FIG. 3, each of the plurality of elastic members 25 is disposed in a state of being stretched in the first direction D1 (width direction W). Further, each of the plurality of elastic members 25 is fixed in a state of being sandwiched by a plurality of welding part groups 35 in which welding part pairs 31 for welding the first nonwoven fabric 21 and the second nonwoven fabric 23 disposed at both ends in the second direction D2 (longitudinal direction L) are spaced apart in the first direction (width direction W).

[0058] As shown in FIG. 4, the welding part pair 31 is composed of a first welding part 33a disposed on one side in the second direction D2 (longitudinal direction L) and a second welding part 33b disposed on the other side in the second direction D2 (longitudinal direction L). Each of the first welding part 33a and the second welding part 33b welds the first nonwoven fabric 21 and the second nonwoven fabric 23, but joins the first nonwoven fabric 21 and the second nonwoven fabric 23 without welding the elastic member 25. The first welding part 33a and the second welding part 33b are disposed at an interval D. The elastic member 25 has a natural state width W0 in a natural state. Since there is a relationship of D < W0 between the natural state width W0 of the elastic member 25 in the natural state and the interval D of the welding part pair 31, the elastic member 25 is sandwiched by the welding part pair 31 in the natural state. As a result, the elastic member 25 is fixed in a state of being sandwiched by a welding part group 35 including a plurality of welding part pairs 31 in a natural state.

[0059] FIG. 5 is a diagram for explaining the state of the elastic member 25 when manufacturing the stretchable nonwoven fabric 1. As shown in FIG. 5, when the elastic member 25 is stretched at a predetermined stretching ratio and is in a stretched state, the elastic member has a stretched state width W1. Next, a welding device having a roll provided with a plurality of protrusions and an anvil roll forms a welding part group 35 including the welding part pair 31 so that the stretched state width W1 of the elastic member 25 in the stretched state and the interval D of the welding part pair 31 have a relationship of W1 < D, and forms a welding part group 35 including the welding part pair 31 between the plurality of protrusions and the anvil roll. Then, when the elastic member 25 is released from the stretched state to the natural state, as shown in FIG. 4, the elastic member 25 is fixed in a state of being sandwiched by a welding part group 35 including a plurality of welding part pairs 31.

[0060] In a welding apparatus having a roll with multiple protrusions and an anvil roll, when forming a group of welded parts 35 including a pair of welded parts 31, if the relative positions of the multiple protrusions and the elastic member 25 are misaligned, the elastic member 25 will be sandwiched between the multiple protrusions and the anvil roll, making the elastic member 25 more prone to partial or complete fracture.

[0061] Each of the multiple elastic members 25 according to the first embodiment is (i) arranged in a state stretched in the first direction with an elongation ratio of 2.8 to 4.0 times, and (iii) has a breaking elongation of 7.0 times or more in a tensile test at 100°C. As a result, the sandwiched portion of the elastic members is less likely to break, and the elasticity of the elastic members is less likely to be inhibited in the stretchable sheet.

[0062] In an expandable sheet according to another embodiment of the present disclosure (which may be referred to as the "second embodiment"), each of the plurality of elastic members 25 is (i) arranged in a state stretched in a first direction and has a fineness of 60 to 470 dtex, and (iii) has a breaking elongation of 7.0 times or more in a tensile test at 100°C. As a result, the portion of the elastic members sandwiched together is less likely to break, and the elasticity of the elastic members in the expandable sheet is less likely to be inhibited. Since the appearance of the stretchable sheet according to the second embodiment is identical to that of the stretchable sheet 2 according to the first embodiment, its illustration and description are omitted.

[0063] The stretchable sheet according to this disclosure has a first direction and a second direction that are orthogonal to each other. The stretchable sheet according to this disclosure comprises a first sheet having heat-weldability, a second sheet having heat-weldability, and a plurality of elastic members arranged between the first sheet and the second sheet, extending in a first direction and spaced apart in a second direction.

[0064] The first sheet and the second sheet are not particularly limited as long as they are heat-sealable, and examples include fabrics (e.g., nonwoven fabrics, woven fabrics, knitted fabrics), films, etc. Examples of the above-mentioned nonwoven fabrics include spunlace nonwoven fabrics, air-through nonwoven fabrics, spunbond nonwoven fabrics, SMS nonwoven fabrics, point-bond nonwoven fabrics, and stretchable nonwoven fabrics (for example, stretchable nonwoven fabrics obtained by stretching a nonwoven fabric containing elastomer fibers and stretchable thermoplastic fibers).

[0065] The above-mentioned fabric preferably contains heat-weldable fibers made of a thermoplastic resin, and examples of the thermoplastic resin include polyethylene resin, polypropylene resin, polyethylene terephthalate resin, etc. Examples of the heat-weldable fibers include single-component polyethylene resin fibers; single-component polypropylene resin fibers; core-sheath type composite synthetic fibers in which the core is polyethylene terephthalate resin and the sheath is polyethylene resin; core-sheath type composite synthetic fibers in which the core is polypropylene resin and the sheath is polyethylene resin; core-sheath type composite synthetic fibers in which the core is high-melting-point polypropylene resin and the sheath is low-melting-point polypropylene resin; side-by-side type composite synthetic fibers made of polyethylene terephthalate resin and polyethylene resin; side-by-side type composite synthetic fibers made of polypropylene resin and polyethylene resin, etc.

[0066] Furthermore, examples of the above-mentioned thermoplastic resins include those that are biodegradable, such as polybutylene succinate, poly(hydroxybutyrate / hydroxyhexanoate), polycaprolactone, poly(caprolactone / butylene succinate), poly(butylene succinate / adipate), poly(butylene succinate / carbonate), poly(butylene adipate / terephthalate), polyethylene succinate, polylactic acid, polyhydroxybutyrate, polyglycolic acid, or cellulose acetate. The above film preferably contains the above thermoplastic resin.

[0067] The above-mentioned multiple elastic members can be formed by improving known dry spinning methods, wet spinning methods, melt spinning methods, etc. The general dry spinning method is as follows: A polyol such as polytetramethylene glycol is dissolved in a solvent, and a diisocyanate such as MDI is added to the solution to react with the polyol and diisocyanate and produce a prepolymer. A glycol such as 1,4-butanediol is added to the prepolymer solution as a chain extender and reacts with the prepolymer to extend the chains and obtain a polymer solution. The obtained polymer solution is extruded from a spinneret, and the solvent is evaporated to form fibers. Elastic fibers can be obtained by stretching, heat treating, etc. General dry spinning methods are disclosed in Japanese Patent Publication No. 2011-144491, Japanese Patent Publication No. 2004-52127, Japanese Patent Publication No. 11-81045, etc.

[0068] Typical elastic members have a multi-block structure consisting of a hard segment and usually a soft segment. The hard segment is mainly composed of diisocyanate (such as MDI) and a glycol chain extender such as 1,4-butanediol, while the soft segment is mainly composed of polyol (such as PTMG). The performance of the elastic member is achieved through the combination of the hard and soft segments.

[0069] The elastic member according to this disclosure can achieve the above-mentioned performance by reducing the amount of chain extender added and decreasing the molecular weight of the hard segment. In wet spinning, melt spinning, and other methods, the elastic member according to this disclosure can be formed by reducing the amount of chain extender added and decreasing the molecular weight of the hard segment compared to known manufacturing methods.

[0070] At least a portion of the above-mentioned multiple elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number of strands) have a predetermined fineness.

[0071] Examples of the specified fineness mentioned above include high fineness and low fineness. The above-mentioned fineness levels are preferably 470 dtex or higher, more preferably 500 dtex or higher, and even more preferably 620 dtex or higher. Furthermore, the above-mentioned fineness levels are preferably 1120 dtex or lower, more preferably 940 dtex or lower, and even more preferably 800 dtex or lower.

[0072] The fineness of the above-mentioned materials is preferably 60 dtex or more, more preferably 80 dtex or more, and even more preferably 100 dtex or more. Alternatively, the fineness of the above-mentioned materials is preferably less than 470 dtex, more preferably 400 dtex or less, and even more preferably 300 dtex or less. In the stretchable sheet according to this disclosure, since multiple elastic members have the above-mentioned fineness, the stretchable sheet has less contact with the skin and has a superior feel against the skin.

[0073] In the stretchable sheet according to this disclosure, at least a portion of the plurality of elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number) are fixed in a state in which welding pairs for welding the first sheet and the second sheet, which are arranged at both ends in the second direction, are sandwiched and fixed by a plurality of welding groups arranged spaced apart in the first direction.

[0074] In the stretchable sheet according to this disclosure, at least a portion of the multiple elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number of members) are not fixed with adhesive. This makes it less likely for the elasticity of the stretchable sheet to be hindered.

[0075] Each of the welded portion pairs constituting the above-mentioned group of welded portions can be formed from a first welded portion and a second welded portion spaced apart in the second direction. The area of ​​the first welded portion and the second welded portion can be, for example, 0.04 to 10 mm². 2 This is one example. As a result, the elastic member is more easily fixed between the welded pair while being precisely compressed.

[0076] The spacing between the first and second welded portions in the second direction is preferably 0.05 mm or more, more preferably 0.10 mm or more, even more preferably 0.15 mm or more, and preferably 5.0 mm or less, more preferably 3.0 mm or less, and even more preferably 1.0 mm or less. The spacing between the first and second welded portions in the second direction is preferably 0.5 times or more, and more preferably 0.6 times or more, the natural width of the elastic member in its natural state. Furthermore, the spacing between the first and second welded portions in the second direction is preferably 0.95 times or less, and more preferably 0.9 times or less, the natural width of the elastic member in its natural state. This makes it easier to fix the elastic member in a compressed state by the group of welded portions.

[0077] In a group of welded portions that fix a single elastic member, the pitch of the welded portion pair in the first direction is preferably 1 mm or more, more preferably 2 mm or more, even more preferably 3 mm or more, and preferably 30 mm or less, more preferably 25 mm or less, and even more preferably 20 mm or less. This makes it easier to fix the elastic member while it is being compressed by the group of welded portions.

[0078] The above-mentioned group of welded parts can be formed by known methods using equipment known in the art. For example, the above-mentioned group of welded parts can be formed by known methods using a welding apparatus that includes, in addition to the above-mentioned welding apparatus that includes a roll with a plurality of protrusions and an anvil roll, a welding apparatus that includes an ultrasonic seal fixing horn with a plurality of protrusions and an anvil roll with a plurality of convex parts, a welding apparatus that includes a flat ultrasonic seal fixing horn and a grooved anvil roll with a plurality of uneven parts, a welding apparatus that includes a flat ultrasonic seal rotary horn and a grooved anvil roll with a plurality of uneven parts, and so on.

[0079] In the stretchable sheet according to this disclosure, at least a portion of the plurality of elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number of members) are arranged in a state in which they are stretched in a first direction at a predetermined stretch ratio. The above stretch ratio: M1 (times) is calculated using the following formula when an elastic member with a natural length: L0 (m) is stretched to a stretched length: L1 (m): M1(times)=L1 / L0 It is represented by [this].

[0080] The above-mentioned stretching ratio can be a high stretching ratio, a medium stretching ratio, etc. The above high stretch ratio is preferably 2.8 times or more, more preferably 3.0 times or more, and even more preferably 3.2 times or more. Furthermore, the above high stretch ratio is preferably 4.0 times or less, more preferably 3.8 times or less, and even more preferably 3.6 times or less. This makes it possible to increase the elasticity of the stretchable sheet and reduce the amount of elastic material used.

[0081] The above-mentioned mid-stretch ratio is preferably 2.5 times or more, and more preferably 2.60 times or more. Furthermore, the above-mentioned mid-stretch ratio is preferably less than 2.8 times, and more preferably 2.7 times or less.

[0082] In the stretchable sheet according to this disclosure, at least a portion of the multiple elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number of members) have a breaking elongation of preferably 7.0 times or more, more preferably 7.1 times or more, even more preferably 7.2 times or more, even more preferably 7.3 times or more, even more preferably 7.4 times or more, and even more preferably 7.5 times or more in a tensile test at 100°C, and preferably 11.0 times or less, more preferably 10.5 times or less, and even more preferably 10.0 times or less in a breaking elongation. As a result, the portions sandwiched between the elastic members become less likely to break, and the elasticity of the elastic members in the stretchable sheet is less likely to be inhibited.

[0083] Furthermore, the elongation ratio M2 (times) in the fracture elongation is calculated using the following formula when an elastic member with a natural length L2 (m) is stretched to a length L3 (m): M2 (times) = L3 / L2 It is represented by [this].

[0084] In the stretchable sheet according to this disclosure, at least a portion of the multiple elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number of members) have a tensile strength at 3.0 times elongation in a tensile test at 100°C, preferably 0.58 mN / dtex or more, more preferably 0.60 mN / dtex or more, even more preferably 0.62 mN / dtex or more, preferably 0.78 mN / dtex or less, more preferably 0.76 mN / dtex or less, and even more preferably 0.75 mN / dtex or less. As a result, the portion of the elastic members sandwiched together is less likely to lose elasticity and is more likely to function as an elastic member. Furthermore, if the tensile strength at 3.0 times elongation is low, the clamped portion of the elastic member tends to break easily. Conversely, if the tensile strength at 3.0 times elongation is high, when the elastic member is clamped by the welding device, if a partial fracture occurs in the clamped portion of the elastic member, a contraction force acts from that fracture point, causing the fracture to enlarge and making it easier for the elasticity of the elastic member to be impaired.

[0085] Furthermore, the elongation ratio M3 (times) for the tensile strength at 3.0 times elongation and the tensile strength at 5.0 times elongation described later is calculated using the following formula when an elastic member with a natural length of L4 (m) is stretched to a length of L5 (m): M3(x)=L5 / L4 It is represented by [this].

[0086] Furthermore, the tensile strength (mN / dtex) at 3.0 times elongation and the tensile strength at 5.0 times elongation described later can be obtained by dividing the obtained tensile strength (mN) by the fineness (dtex) of the elastic member. The reason for dividing the tensile strength (mN) by the fineness (dtex) of the elastic member is to evaluate the strength of the elastic member material itself.

[0087] In the stretchable sheet according to this disclosure, at least a portion of the multiple elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number of members) have a tensile strength at 5.0 times elongation in a tensile test at 100°C, preferably 0.90 mN / dtex or more, more preferably 0.94 mN / dtex or more, even more preferably 0.98 mN / dtex or more, preferably 1.30 mN / dtex or less, more preferably 1.28 mN / dtex or less, and even more preferably 1.26 mN / dtex or less. As a result, the portion of the elastic members sandwiched together is less likely to lose elasticity and is more likely to function as an elastic member.

[0088] In the stretchable sheet according to this disclosure, at least a portion of the multiple elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number of members) have a breaking elongation of preferably 6.0 times or more, more preferably 6.1 times or more, even more preferably 6.2 times or more, and even more preferably 6.6 times or more in a tensile test at 50°C, and preferably 9.0 times or less, more preferably 8.5 times or less, and even more preferably 8.0 times or less in a breaking elongation. As a result, the elasticity of the elastic members in the stretchable sheet is less likely to be inhibited.

[0089] In the stretchable sheet according to this disclosure, at least a portion of the multiple elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number of members) have a tensile strength at 3.0 times elongation in a tensile test at 50°C, preferably 0.70 mN / dtex or more, more preferably 0.75 mN / dtex or more, even more preferably 0.80 mN / dtex or more, preferably 1.10 mN / dtex or less, more preferably 1.05 mN / dtex or less, and even more preferably 1.00 mN / dtex or less. As a result, the elasticity of the elastic members in the stretchable sheet is less likely to be inhibited.

[0090] In the stretchable sheet according to this disclosure, at least a portion of the multiple elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number of members) have a tensile strength at 5.0 times elongation in a tensile test at 50°C, preferably 1.55 mN / dtex or more, more preferably 1.60 mN / dtex or more, even more preferably 1.65 mN / dtex or more, preferably 2.25 mN / dtex or less, more preferably 2.20 mN / dtex or less, and even more preferably 2.15 mN / dtex or less. This makes it easier for the elongation ratio of the elastic members to become uniform among the welded groups.

[0091] In this specification, tensile tests may be performed as follows: (1) Leave the elastic member undisturbed in a constant temperature room at 50°C for two weeks. (2) Cut the elastic material to a length of 50 mm and fix it to a total of two toothpicks with a 30 mm gap between them to create a test sample. (3) Turn on the power to the tensile testing machine (manufactured by Shimadzu Corporation, product name: AGX-50NV) and the thermostatic chamber (manufactured by Shimadzu Corporation, model number: TCR1L-220-X), heat the test space to the test temperature (100°C or 50°C), and stop heating 10 minutes after the test space reaches the test temperature. (4) Place the test sample in the chucks (distance between chucks: 30 mm) inside the test space.

[0092] (5) Reheat the test space to the test temperature. (6) After reaching the test temperature, heating is stopped, and a tensile test is performed at a speed of 500 mm / min until the elastic member breaks under the following conditions, and data on the elongation ratio and tensile strength (mN) are obtained. (7) From the obtained data, calculate the elongation at break (times), tensile strength at 3.0 times elongation (mN / dtex), and tensile strength at 5.0 times elongation (mN / dtex). (8) Tensile tests are performed a total of 10 times on different test samples, and the average value is adopted.

[0093] In the stretchable sheet according to this disclosure, at least a portion of the multiple elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number of strands) can be multifilaments containing multiple single filaments. As a result, even if the elastic members are pinched by a welding device, the gaps in the multifilaments provide a buffering function, making it less likely for the single filaments constituting the multifilaments to break at the pinched portion of the elastic members.

[0094] The above multifilament is preferably twisted. This makes it less likely for the multiple single filaments to unravel even if an elastic member is trapped between them, and also makes it easier for the trapped portion of the elastic member to escape from between the protruding part of the welding device and the anvil roll.

[0095] The above multifilament preferably has a void ratio of 15.0% or more, more preferably 17.5% or more, even more preferably 20.0% or more, and preferably 35.0% or less, more preferably 30.0% or less, and even more preferably 27.5% or less. As a result, even if an elastic member is sandwiched between the multifilament, the voids with the above void ratio in the multifilament provide a buffering function, making it difficult for the single threads constituting the multifilament to break.

[0096] Furthermore, even when the multifilaments are twisted, it is preferable that the multifilaments have the above-mentioned void ratio. This is because if the void ratio is increased by reducing the twist, the single filaments tend to unravel, and in the portion sandwiched between the elastic members, the single filaments separate, impairing the elasticity of the elastic members and potentially causing them to break partially or completely. Also, if the void ratio is reduced, the cushioning function in the portion sandwiched between the elastic members tends to be insufficient, making the elastic members more prone to breaking.

[0097] The method for measuring the void ratio is as follows: (1) A stainless steel blade (Beauty M Stainless Steel Blade for Face and Eyebrow Shaving, BTM-10H1, manufactured by Kai Corporation) is pressed vertically against an elastic member composed of a multifilament containing multiple single threads to cut the elastic member. (2) The elastic member is attached to the sample stage with its cross-section facing upwards, and gold deposition is performed for 120 seconds using a twin coater (JEOL Ltd., JEC-550) to prepare the sample. (3) Place the sample on the observation stand of an electron microscope (Keyence Corporation, desktop electron microscope, VHX-D500 / D510) and focus on the cross-section of the sample at 500x magnification.

[0098] (4) Adjust the color tone so that the brightness of the void area is 0, and use the automatic area measurement function to determine the area of ​​the void area: A1 (μm 2 ) Measure. (5) After specifying the "circle" mode, use the area measurement function for specifying the shape to measure the area of ​​each of the multiple single filaments: a²(μm 2) was measured, and each area: a²(μm 2 ) are added together to obtain the total area of ​​multiple single filaments: A2 (μm 2 Calculate ). (6) Vorticity: V (%) is given by the following formula: V(%) = 100 × A1 / (A1 + A2) (7) The porosity is measured a total of 10 times from different samples of the same elastic material, and the average value is adopted.

[0099] In the stretchable sheet according to this disclosure, the plurality of elastic members may include two or more elastic members that differ in at least one of their fineness and stretch ratio. This makes it less likely for the stretchability of the elastic members to be hindered without changing the roll equipped with multiple protrusions in the welding device. Furthermore, the stretchable sheet can be made to have preferred stretchability depending on the application of the stretchable sheet.

[0100] In the stretchable sheet according to this disclosure, at least a portion of the multiple elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number of members) contains titanium oxide in a ratio of preferably more than 0.0 mass%, more preferably 0.1 mass or more, even more preferably 0.2 mass or more, preferably less than 3.0 mass, more preferably 2.0 mass or less, and even more preferably 1.5 mass or less. As a result, the contact area between the first sheet and the second sheet and the elastic members is reduced, and even if the elastic members are pinched by the welding device, the pinched portion of the elastic members can easily escape from between the protruding portion of the welding device and the anvil roll, while preventing the elastic members from becoming too hard and preventing the pinched portion of the elastic members from fracturing starting from the titanium oxide particles.

[0101] In the stretchable sheet according to this disclosure, at least a portion of the multiple elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number of members) contains an oil agent in a ratio of preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, preferably preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 1.0% by mass or less. As a result, friction between the first sheet and the second sheet and the elastic members is reduced, and even if the elastic members are pinched by the welding device, the pinched portion of the elastic member can easily escape from between the protruding part of the welding device and the anvil roll.

[0102] The above-mentioned oils can be any that can be contained in elastic members in the art without particular limitation. Examples include the treatment agent for polyurethane elastic fibers disclosed in Japanese Patent Application Publication No. 2012-031551, the modifier comprising a mixture of silicone oil, modified silicone, and metal soap disclosed in Japanese Patent Application Publication No. 2007-100248, and the modifier for manufacturing elastic fibers disclosed in Japanese Patent Application Publication No. 2009-287127.

[0103] In the stretchable sheet according to this disclosure, each of the plurality of elastic members may have a region between welded pairs that is partitioned by two welded pairs that are continuous in the first direction when the stretchable sheet is stretched. Furthermore, the region between welded pairs may be further partitioned into a non-broken region between welded pairs, which is a region in which at least a part of the elastic member has fractured portions, and a broken region between welded pairs, which is a region in which at least a part of the elastic member has fractured portions. It is preferable that at least a portion of the plurality of elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, on a number basis) have the non-broken regions between welded pairs in the first direction, preferably in a sequence of at least two, more preferably 50% or more (on a number basis), and even more preferably 100% (on a number basis). As a result, the elasticity of the elastic component is less likely to be inhibited in the aforementioned stretchable sheet.

[0104] In the stretchable sheet according to this disclosure, at least a portion of the plurality of elastic members (preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, even more preferably 95% or more, and even more preferably 100%, i.e., all or more, based on the number) may have flattened portions. Preferably, the flattened portions have an outer diameter smaller than the distance between the welded portion pairs when the stretchable sheet is stretched. This allows the flattened portions to pass through the welded portion pairs, thus making it less likely for them to hinder the stretching and contracting of the elastic members.

[0105] The flattened portion mentioned above is caused by the elastic member being clamped by the welding device, and represents a section where the diameter of the elastic member is partially thicker. Furthermore, the state in which the stretchable sheet is stretched means that the first and second sheets constituting the stretchable sheet are stretched to their maximum extent in the first direction without damaging the first and second sheets.

[0106] The stretchable sheet relating to this disclosure can be used for any application requiring stretchability. Examples of such applications include sanitary products, such as disposable diapers (e.g., adult disposable diapers, baby disposable diapers, pet disposable diapers), urine pads, incontinence pads, sanitary napkins, panty liners, sanitary shorts, tampons, absorbent shorts, breast pads, pet sheets, bed sheets, pressure ulcer pads, masks (e.g., disposable masks), bandages, adhesive bandages, etc. Among the above sanitary products, disposable diapers (e.g., adult disposable diapers, baby disposable diapers, pet disposable diapers), urine pads, incontinence pads, sanitary napkins, panty liners, sanitary shorts, tampons, absorbent shorts, breast pads, pet sheets, etc. are also referred to as absorbent articles.

[0107] This disclosure also relates to absorbent articles in the form of pant-type garments. Examples of absorbent articles in the form of pant-type garments include disposable adult diapers (e.g., disposable adult diapers, disposable baby diapers, disposable pet diapers), sanitary shorts, and the like. The pant-type absorbent article relating to this disclosure may be provided with the above-mentioned stretchable sheet at any location where stretchability is required.

[0108] For example, the above-mentioned pant-type absorbent article comprises a waist portion, a side seal portion, and a waist direction, and the stretchable sheet can be positioned in the side seal portion such that the first direction and the waist direction coincide. As a result, in the above-mentioned pant-type absorbent article, the waist portion fits the wearer's waist and is less likely to slip down. [Examples]

[0109] The following examples illustrate this disclosure, but this disclosure is not limited to these examples. [Manufacturing Example 1] 2400 g of polytetramethylene ether diol with an average molecular weight of 1,800 and 550.2 g of 4,4'-diphenylmethane diisocyanate were reacted under a dry nitrogen atmosphere at 80°C for 3 hours with stirring to obtain a polyurethane prepolymer with isocyanate caps at the ends, and the polyurethane prepolymer was cooled to room temperature. 4320 g of dimethylacetamide was added to the polyurethane prepolymer to prepare a polyurethane prepolymer solution. 48.66 g of ethylenediamine (chain extender) and 8.22 g of diethylamine (chain extension inhibitor) were dissolved in 2340 g of dimethylacetamide and added to the polyurethane prepolymer solution at room temperature to obtain a polyurethane solution with a viscosity of 450 Pa·s (30°C).

[0110] To the above polyurethane solution, 1% by mass of 4,4'-butylidenebis-(3-methyl-6-t-butylphenol) and 0.5% by mass of 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole were added relative to the polyurethane solid content, and then 2.9% by mass of titanium dioxide was added to obtain a spinning stock solution. The above spinning stock solution was extruded into hot air through the pores of a spinneret to evaporate the solvent. The dried yarn was false-twisted as it passed through a ring false-twisting machine, and elastic member No. 1A was formed by winding it onto a paper tube at a speed of 500 m / min after passing through a godet roller. Next, by changing the size of the pores of the spinneret, elastic members No. 1B to No. 1E were formed, which had the same composition as elastic member No. 1A but different fineness. The fineness of elastic members No. 1A to No. 1E is listed in Table 1.

[0111] [Manufacturing Examples 2-5] By varying the amount of diethylamine (chain elongation inhibitor), elastic members No. 2A to No. 2D, No. 3A to No. 3E, No. 4A to No. 4D, and No. 5A to No. 5D were formed, all having the same composition but different fineness. The fineness of elastic members No. 2A to No. 5D is shown in Table 1. For elastic members that do not contain titanium dioxide, the elastic members were formed in Manufacturing Example 1 without adding titanium dioxide. Furthermore, for elastic members containing oil, a predetermined amount of a treatment agent consisting of 50% by mass of 10 cst of dimethyl silicon and 50% by mass of 10 cst of mineral oil was applied to the yarn on an oiling roller when winding it onto a paper tube.

[0112] [Comparative Manufacturing Example 1] Lycra® T-127, manufactured by Toyo Perontex Co., Ltd., was used as the elastic members No. 6A to No. 6F. The fineness of elastic members No. 6A to No. 6F is listed in Table 1. The titanium dioxide and oil content of each elastic member No. 6A to No. 6F are reference values ​​obtained through analysis.

[0113] [Manufacturing Example 6] Four elastic members No. 1A were placed between two long sheets of nonwoven fabric (width: 200 mm) at a distance of 10 mm in the second direction and at a predetermined stretch ratio in the first direction. A welding device having a roll with multiple protrusions and an anvil roll was used to form a group of welded sections including welded sections, and the four elastic members were fixed in a compressed state by the group of welded sections to form an expandable sheet No. 1A. The welded sections were formed under conditions that ensured sufficient welding between the two sheets of nonwoven fabric.

[0114] The two nonwoven fabrics are SMS nonwoven fabrics with a basis weight of 13 g / m². 2 It had a structure and was composed of single fibers of polypropylene resin. Details of the welded areas are as follows: - Area of ​​the first and second welded parts constituting the welded pair: 0.375 mm² 2 - Distance between the first and second welded parts constituting the welded pair: 0.27 mm - Pitch of welded pair: 7.8mm

[0115] Elastic members No. 1A was replaced with elastic members No. 1B to No. 1E, respectively, to form stretchable sheets No. 1B to No. 1E. The relationship between elastic members No. 1A to No. 1E and stretchable sheets No. 1A to No. 1E is shown in Table 1.

[0116] [Manufacturing Examples 7-10 and Comparative Manufacturing Example 2] Elastic sheets No. 2A to No. 6F were formed in the same manner as in Manufacturing Example 6. The relationship between elastic members No. 2A to No. 6F and elastic sheets No. 2A to No. 6F is shown in Table 1.

[0117] [Examples 1-5 and Comparative Example 1] For elastic members No. 1A to No. 6F, (i) elongation at break in tensile tests (100°C, 50°C), (ii) tensile strength at 3.0 times elongation in tensile tests (100°C, 50°C), and (iii) tensile strength at 5.0 times elongation in tensile tests (100°C, 50°C) were measured. The results are shown in Table 1. In Table 1, "Elongation at break in a tensile test at 100°C" is written as "Elongation at break / 100°C", "Tensile strength at 3.0 times elongation in a tensile test at 100°C" is written as "3 times strength / 100°C", and "Tensile strength at 5.0 times elongation in a tensile test at 100°C" is written as "5 times strength / 100°C". Also in Table 1, "Elongation at break in a tensile test at 50°C" is written as "Elongation at break / 50°C", "Tensile strength at 3.0 times elongation in a tensile test at 50°C" is written as "3 times strength / 50°C", and "Tensile strength at 5.0 times elongation in a tensile test at 50°C" is written as "5 times strength / 50°C".

[0118] Stretchable sheets No. 1A to No. 6F were evaluated over a length of 50m according to the following criteria. The results are shown in Table 1. A: None of the four elastic members were completely severed, and none of the four elastic members had partial fractures or minor partial fractures. B: None of the four elastic members were completely severed, and at least one of the four elastic members had a moderate partial fracture. C: At least one of the four elastic members was completely fractured.

[0119] For stretchable sheets No. 1A to No. 6F, we evaluated (i) whether they had at least two consecutive non-breaking regions between welded pairs in the first direction, and (ii) whether the flattened portion had an outer diameter smaller than the distance between welded pairs when the stretchable sheet was stretched. The results are shown in Table 1. In Table 1, item (iv) "Whether or not there are at least two consecutive non-breaking regions between welded pairs in the first direction" is denoted as "non-breaking region," where "Yes" means there are two consecutive regions and "No" means there are not two consecutive regions. Also in Table 1, item "Whether or not the flattened portion has an outer diameter smaller than the distance between welded pairs when the stretchable sheet is stretched" is denoted as "specified flattened portion," where "Yes" means the elastic member has a flattened portion and the flattened portion has an outer diameter smaller than the distance between welded pairs when the stretchable sheet is stretched, where "No" means the elastic member does not have a flattened portion and the sandwiching portion of the elastic member is partially or completely broken, the elastic member has a flattened portion and the flattened portion has an outer diameter larger than the distance between welded pairs when the stretchable sheet is stretched, and combinations thereof.

[0120] [Table 1] [Explanation of Symbols]

[0121] 1. Disposable diapers 2. Stretchable sheet 21 1st nonwoven fabric 23 Second nonwoven fabric 25 Elastic members 31 Welded Pair 33a 1st weld part 33b 2nd weld part 35 Weld group D1 1st direction D2 2nd direction D interval W0 Natural width W1 Extended width

Claims

1. A stretchable sheet having a first direction and a second direction that are orthogonal to each other, The stretchable sheet comprises a first sheet having heat-welding properties, a second sheet having heat-welding properties, and a plurality of elastic members that extend in a first direction and are spaced apart in a second direction between the first and second sheets. At least a portion of the plurality of elastic members is (i) It is installed in a state that is stretched in the first direction with an extension ratio of 2.8 to 4.0 times, (ii) The welding portion pairs that weld the first sheet and the second sheet, which are located at both ends in the second direction, are fixed in a state of being sandwiched between multiple welding portion groups that are spaced apart in the first direction. (iii) Having a breaking elongation of 7.0 times or more in a tensile test at 100°C, A stretchable sheet characterized by the following features.

2. The stretchable sheet according to claim 1, wherein at least a portion of the plurality of elastic members further has a tensile strength of 0.58 to 0.78 mN / dtex at 3.0 times elongation in the tensile test at 100°C.

3. The stretchable sheet according to claim 1, wherein at least a portion of the plurality of elastic members further has a tensile strength of 0.90 to 1.30 mN / dtex at 5.0 times elongation in the tensile test at 100°C.

4. A stretchable sheet having a first direction and a second direction that are orthogonal to each other, The stretchable sheet comprises a first sheet having heat-welding properties, a second sheet having heat-welding properties, and a plurality of elastic members that extend in a first direction and are spaced apart in a second direction between the first and second sheets. At least a portion of the plurality of elastic members is (i) It is arranged in an extended state in the first direction and has a fineness of 60 to 470 dtex, (ii) The pairs of welded parts located at both ends in the second direction are fixed in a state of being sandwiched between multiple groups of welded parts located spaced apart in the first direction. (iii) Having a breaking elongation of 7.0 times or more in a tensile test at 100°C, A stretchable sheet characterized by the following features.

5. The stretchable sheet according to claim 4, wherein at least a portion of the plurality of elastic members further has a tensile strength of 0.58 to 0.78 mN / dtex at 3.0 times elongation in the tensile test at 100°C.

6. The stretchable sheet according to claim 4, wherein at least a portion of the plurality of elastic members further has a tensile strength of 0.90 to 1.30 mN / dtex at 5.0 times elongation in the tensile test at 100°C.

7. The stretchable sheet according to any one of claims 1 to 6, wherein at least a portion of the plurality of elastic members has a breaking elongation of 6.0 times or more in a tensile test at 50°C.

8. The stretchable sheet according to any one of claims 1 to 6, wherein at least a portion of the plurality of elastic members further has a tensile strength of 0.70 to 1.10 mN / dtex at 3.0 times elongation in a tensile test at 50°C.

9. The stretchable sheet according to any one of claims 1 to 6, wherein at least a portion of the plurality of elastic members further has a tensile strength of 1.55 to 2.25 mN / dtex at 5.0 times elongation in a tensile test at 50°C.

10. The stretchable sheet according to any one of claims 1 to 6, wherein at least a portion of the plurality of elastic members is a multifilament comprising a plurality of single threads.

11. The stretchable sheet according to claim 10, wherein the multifilaments are twisted together.

12. The stretchable sheet according to claim 10, wherein the multifilament has a porosity of 15.0 to 30.0%.

13. The stretchable sheet according to any one of claims 1 to 6, wherein the plurality of elastic members include two or more elastic members having at least one different fineness and stretch ratio.

14. The stretchable sheet according to any one of claims 1 to 6, wherein at least a portion of the plurality of elastic members contains titanium oxide in an amount of less than 3.0% by mass.

15. The stretchable sheet according to any one of claims 1 to 6, wherein at least a portion of the plurality of elastic members contains 0.05 to 5.0% by mass of an oil agent.

16. In the state in which the stretchable sheet is stretched, each of the plurality of elastic members has an inter-welded portion pair region that is partitioned by two welding portion pairs that are continuous in the first direction, At least a portion of the plurality of elastic members has at least two consecutive non-breakage regions between welded pairs in a first direction, where the inter-welded region is demarcated in a region where at least a portion of the elastic member does not have a fractured portion. The stretchable sheet according to any one of claims 1 to 6.

17. The stretchable sheet according to any one of claims 1 to 6, wherein at least a portion of the plurality of elastic members has a flattened portion, and the flattened portion has an outer diameter smaller than the distance between the welded portion pairs when the stretchable sheet is stretched.

18. A pant-type absorbent article comprising the stretchable sheet described in any one of claims 1 to 6.

19. The aforementioned pant-type absorbent article comprises a waist portion, a side seal portion, and a waist direction. The stretchable sheet is positioned in the side seal portion such that the first direction and the body circumference direction coincide. The pants-type absorbent article according to claim 18.

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