Stretchable sheet and underpants-type absorbent article provided with same

Abstract

The purpose of the present disclosure is to provide a stretchable sheet in which the elasticity of an elastic member does not easily degrade.　The stretchable sheet (2) having a first direction (D1) and a second direction (D2) is characterized by comprising: a first sheet (21) and a second sheet (23); and a plurality of elastic members (25) between the first sheet (21) and the second sheet (23), the plurality of elastic members (25) extending in the first direction (D1) and being disposed spaced apart from each other in the second direction (D2), wherein at least some of the plurality of elastic members (25) are (i) disposed stretched in the first direction (D1) at a stretch ratio of 2.8-4.0, and (ii) fixed while sandwiched and pressed by a plurality of welding part groups (35) in which a plurality of welding part pairs (31), for welding the first sheet (21) and the second sheet (23), disposed at both ends in the second direction (D2) are disposed spaced apart from each other in the first direction (D1), and (iii) the stretchable sheet (2) has a fracture elongation of 7.0 times or more in a tensile test performed at 100°C.

Description

Stretchable sheet and a pant-type absorbent article provided with the stretchable sheet

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

[0002] In 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, the plurality of elastic members are disposed in a stretched state in the first direction, and a pair of welding portions 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 portions spaced apart in the first direction (hereinafter, may be referred to as "conventional welded stretchable sheet"). Consideration has been given to improvements thereof.

[0003] For example, in Patent Document 1, 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, and the first surfaces 1f and 2f of the pair of sheets 1 and 2 are joined to each other by a welding structure without an adhesive, and hold the elastic members F, extend in a direction Dp intersecting the stretching direction Df of the elastic members F, and a plurality of joining portions 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 portions 3 in a state where the elastic members F are contracted, each joining portion 3 includes a plurality of strong joining portions 3s disposed on both sides of the elastic members F in the intersecting direction Dp, and a weak joining portion 3w disposed between adjacent elastic members F among the elastic members F and between adjacent strong joining portions 3s among the plurality of strong joining portions 3s, and the joining strength between the pair of sheets 1 and 2 in the weak joining portion 3w is smaller than the joining strength between the pair of sheets 1 and 2 in the strong joining portion 3s. A stretchable sheet is disclosed.

[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.

[0005] International Publication No. 2018 / 070158, Japanese Patent Publication No. 2009-056156

[0006] Patent documents 1 and 2 do not disclose the stretchable sheet relating to this disclosure. The purpose of this disclosure is to provide a stretchable sheet in which the elasticity of the elastic member is less likely to be inhibited.

[0007] The Disclosers have found an expandable sheet having a first and second direction that are orthogonal to each other, wherein the expandable sheet comprises a first sheet that is heat-weldable, a second sheet that is heat-weldable, and a plurality of elastic members that extend in the first direction and are spaced apart in the 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, which are located at both ends in the second direction, are fixed in a state where they are sandwiched between a plurality of welded parts that are 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.

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

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

[0010] Specifically, this disclosure relates to the following embodiments. [Embodiment 1] An expandable sheet having a first direction and a second direction that are orthogonal to each other, wherein the expandable sheet comprises a first sheet having heat-welding properties, a second sheet having heat-welding properties, and a plurality of elastic members extending in the first direction and spaced apart in the second direction between the first sheet and the second sheet, wherein at least a portion of the plurality of elastic members is (i) arranged in a state stretched in the first direction at a stretching ratio of 2.8 to 4.0 times, (ii) fixed in a state where welding pairs for welding the first sheet and the second sheet, which are arranged at both ends in the second direction, are sandwiched between a plurality of welding groups 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.

[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, in pant-type absorbent articles, using a highly stretchable sheet is preferable from the following viewpoints. For example, in pant-type absorbent articles, the weight of the pant-type absorbent article increases as the wearer's posture changes (standing, sitting, lying down, etc.) and as bodily fluids are absorbed. By using a highly stretchable sheet, the shifting of the pant-type absorbent article can be suppressed. In addition, by using a highly stretchable sheet in pant-type absorbent articles, the wearer's size range can be expanded, and wearer dissatisfaction with the size can be reduced.

[0012] Generally, in the manufacture of stretchable sheets, when an elastic member is arranged in a state where it has been stretched in a first direction at a high stretch ratio, and when forming a welded pair at both ends of the elastic member stretched in a second direction, if the elastic member is sandwiched between the multiple protrusions and the anvil roll using a welding device equipped with a roll having multiple protrusions and an anvil roll, the elastic member tends to break partially or entirely. In this specification, when forming a welded pair, the act of 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 welded pair, the portion of the elastic member sandwiched between the protrusions of the welding device and the anvil roll may be simply referred to as the "sandwiched portion of the elastic member."

[0013] However, in the above-mentioned stretchable sheet, although at least a portion of the elastic member is arranged in a state stretched in the first direction at a predetermined stretch ratio, the elastic member has a predetermined elongation at break in a tensile test at 100°C. Therefore, 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.

[0014] [Aspect 2] The stretchable sheet according to aspect 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.

[0015] 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 is more likely to function 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. Furthermore, since the first and second sheets are not welded at the pinched portion of the elastic member, the pinched portion of the elastic member can exhibit elasticity after welding by the welding device is completed.

[0016] [Aspect 3] The stretchable sheet according to aspect 1 or 2, wherein at least a portion of the plurality of elastic members further has a tensile strength of 0.90 to 1.30 mN / dtex when stretched 5.0 times in the 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] An expandable sheet having a first direction and a second direction that are orthogonal to each other, wherein the expandable sheet comprises a first sheet having heat-welding properties, a second sheet having heat-welding properties, and a plurality of elastic members extending in the first direction and spaced apart in the second direction between the first sheet and the second sheet, wherein at least a portion of the plurality of elastic members is (i) arranged in a state stretched in the first direction and having a fineness of 60 to 470 dtex, (ii) a pair of welded portions arranged at both ends in the second direction is fixed in a state of being sandwiched between a plurality of groups of welded portions 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.

[0019] A stretchable sheet equipped with thin elastic members is preferable from the viewpoint of skin feel because it has less 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 welding pairs are formed at both ends of the stretched elastic members, if the elastic members are pinched by the welding device, 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 members are thin with a predetermined fineness, these elastic members have a predetermined elongation at break in a tensile test at 100°C. Therefore, even if the elastic members are pinched by the welding device and partially compressed and heated by the protruding portion and anvil roll, the pinched portion of the elastic members is less likely to break. As a result, the elasticity of the elastic members in the above-mentioned stretchable sheet is less likely to be inhibited. Furthermore, because the above-mentioned stretchable sheet is equipped with predetermined thin elastic members, it has a superior feel against the skin.

[0021] [Aspect 5] The stretchable sheet according to aspect 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.

[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 aspect 4 or 5, 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.

[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 aspects 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.

[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 becomes more uniform among the group of welded parts.

[0027] [Aspect 8] An elastic sheet according to any one of aspects 1 to 7, 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.

[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 aspects 1 to 8, 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.

[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] The stretchable sheet according to any one of aspects 1 to 9, wherein at least a portion of the plurality of elastic members is a multifilament containing a plurality of 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 stretchable sheet according to aspect 10, wherein the multifilament is twisted.

[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 stretchable sheet according to aspect 10 or 11, wherein the multifilament has 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 sandwiched by a welding device, the voids with the above-described porosity provided by the multifilaments act as a buffer, making it difficult for the single threads constituting the multifilaments to break in the sandwiched 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 multifilaments are twisted, it is preferable that the multifilaments have the above-described porosity. This is because increasing the porosity by reducing the twist makes the single threads more likely to unravel, and in the sandwiched portion of the elastic members, the single threads separate, impairing the elasticity of the elastic members and potentially causing them to break partially or completely. Conversely, decreasing the porosity tends to result in insufficient buffering in the sandwiched portion of the elastic members, making them more prone to breaking.

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

[0038] In a conventional welded stretchable sheet, when manufacturing a stretchable sheet in which at least one of the fineness and elongation ratio of the elastic member is different, as disclosed in Patent Document 2, it is necessary to change the interval between a pair of joining portions, and it is necessary to change the arrangement of a plurality of protruding portions in a welding apparatus including a roll having a plurality of protruding portions and an anvil roll, which is a manufacturing apparatus for the stretchable sheet.

[0039] The stretchable sheet includes two or more types of elastic members having different fineness or elongation ratio. However, in the stretchable sheet, since at least a part of the plurality of elastic members is a predetermined one, even when the elastic member is sandwiched by the welding apparatus, the sandwiched portion of the elastic member is difficult to break. Therefore, the elasticity of the elastic member is hardly inhibited without changing the roll having a plurality of protruding portions in the welding apparatus. Further, the stretchable sheet can be a stretchable sheet having preferable stretchability according to the use of the stretchable sheet.

[0040] [Aspect 14] The stretchable sheet according to any one of Aspects 1 to 13, wherein at least a part of the plurality of elastic members contains titanium oxide in an amount less than 3.0% by mass.

[0041] In the stretchable sheet, since at least a part of the plurality of elastic members contains a predetermined amount of titanium oxide, the surface of the elastic member has a plurality of convex portions due to the titanium oxide particles. Therefore, the contact area between the first sheet and the second sheet and the elastic member becomes small, and even when the elastic member is sandwiched by the welding apparatus, the sandwiched portion of the elastic member easily escapes from between the protruding portion of the welding apparatus and the anvil roll. As a result, the elasticity of the elastic member in the stretchable sheet is hardly inhibited. Further, by containing a predetermined amount of titanium oxide, it is possible to suppress the elastic member from becoming too hard and suppress the sandwiched portion of the elastic member from breaking starting from the titanium oxide particles.

[0042] [Aspect 15] At least a part of the plurality of elastic members is the stretchable sheet according to any one of Aspects 1 to 14, containing 0.05 to 5.0% by mass of an oil agent.

[0043] In the stretchable sheet, at least a part of the plurality of elastic members contains a predetermined amount of an oil agent. Therefore, the friction between the first sheet and the second sheet and the elastic members is reduced, and even when the elastic members are sandwiched by the welding device, the sandwiched portion of the elastic members is likely to escape from between the protruding portion of the welding device and the anvil roll. As a result, the elasticity of the elastic members in the stretchable sheet is less likely to be inhibited.

[0044] [Aspect 16] In a state where the stretchable sheet is stretched, each of the plurality of elastic members has a region between welding portion pairs partitioned by two welding portion pairs continuous in the first direction, and at least a part of the plurality of elastic members has at least two non-breaking regions between welding portion pairs continuously in the first direction, where the region between welding portion pairs is partitioned into a region having no breaking portion where at least a part of the elastic member is broken, the stretchable sheet according to any one of Aspects 1 to 15.

[0045] In the stretchable sheet, at least a part of the plurality of elastic members continuously has at least two non-breaking regions between welding portion pairs in the first direction, so the elasticity of the elastic members in the stretchable sheet is less likely to be inhibited.

[0046] [Aspect 17] At least a part of the plurality of elastic members has a flat portion, and the flat portion has an outer diameter smaller than the interval between the welding portion pairs in a state where the stretchable sheet is stretched, the stretchable sheet according to any one of Aspects 1 to 16.

[0047] In the stretchable sheet, at least a part of the plurality of elastic members has a predetermined flat portion. Although the flat portion is derived from the sandwiched portion of the elastic member, the flat portion can pass through the welding portion pair, so it is difficult to inhibit the expansion and contraction of the elastic member. As a result, the elasticity of the elastic members in the stretchable sheet is less likely to be inhibited.

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

[0049] [Aspect 19] The pant-type absorbent article according to aspect 18, wherein the pant-type absorbent article comprises a waist portion, a side seal portion, and a waist direction, and the stretchable sheet is arranged in the side seal portion such that the first direction and the waist direction coincide.

[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 are diagrams illustrating a disposable diaper 1 equipped with the 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] In its unfolded state as shown in Figure 1, the disposable diaper 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, it 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 a crotch portion 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 comprising 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 having heat-welding properties and positioned on the skin side, a second nonwoven fabric 23 having heat-welding properties and 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 Figure 3, each of the multiple elastic members 25 is arranged in an extended state in the first direction D1 (width direction W). Furthermore, each of the multiple elastic members 25 is fixed in a state where welding pairs 31, which weld the first nonwoven fabric 21 and the second nonwoven fabric 23, are located at both ends in the second direction D2 (longitudinal direction L), and are sandwiched between multiple welding groups 35 that are spaced apart in the first direction (width direction W).

[0058] As shown in Figure 4, the welded portion pair 31 consists of a first welded portion 33a located in one of the second directions D2 (longitudinal direction L) and a second welded portion 33b located in the other of the second directions D2 (longitudinal direction L). The first welded portion 33a and the second welded portion 33b weld the first nonwoven fabric 21 and the second nonwoven fabric 23, respectively, but join the first nonwoven fabric 21 and the second nonwoven fabric 23 without welding the elastic member 25. The first welded portion 33a and the second welded portion 33b are spaced apart by a distance D. The elastic member 25 has a natural width W0 in its natural state. Since there is a relationship D < W0 between the natural width W0 of the elastic member 25 in its natural state and the distance D of the welded portion pair 31, the elastic member 25 is compressed between the welded portion pair 31 in its natural state. As a result, in its natural state, the elastic member 25 is fixed in a state of being sandwiched between a group of welded parts 35, which includes a plurality of welded part pairs 31.

[0059] Figure 5 is a diagram illustrating the state of the elastic member 25 when manufacturing the stretchable sheet 2. As shown in Figure 5, when the elastic member 25 is stretched at a predetermined stretching ratio and reaches the stretched state, the elastic member has a stretched width W1. Next, a welding device having a roll with multiple protrusions and an anvil roll forms a group of welded parts 35 including the welded parts 31, such that the stretched width W1 of the elastic member 25 in the stretched state and the spacing D of the welded part pairs 31 have the relationship W1 < D. The group of welded parts 35 including the welded part pairs 31 is formed between the multiple protrusions and the anvil roll. Next, when the elastic member 25 is released from the stretched state and returned to its natural state, as shown in Figure 4, the elastic member 25 is fixed in a state of being sandwiched between the group of welded parts 35 including the multiple welded 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 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 a stretch 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 in the stretchable sheet is less likely to be inhibited.

[0062] In the stretchable 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 the 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 sandwiched portion of the elastic members is less likely to break, and the elasticity of the elastic members in the stretchable sheet is less likely to be inhibited. Note that the appearance of the stretchable sheet according to the second embodiment is the same as that of the stretchable sheet 2 according to the first embodiment, so it is not shown or described.

[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 that is heat-weldable, a second sheet that is heat-weldable, and a plurality of elastic members that extend in the first direction and are spaced apart in the second direction between the first sheet and the second sheet.

[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 nonwoven fabrics include spunlace nonwoven fabrics, air-through nonwoven fabrics, spunbond nonwoven fabrics, SMS nonwoven fabrics, point-bond nonwoven fabrics, and stretchable nonwoven fabrics (e.g., 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 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 resin 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-mentioned film preferably contains the above-mentioned 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. A 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 thereto to react with the polyol and diisocyanate to produce a prepolymer. A glycol such as 1,4-butanediol is added to the prepolymer solution as a chain extender and reacted 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] A typical elastic member has a multi-block structure consisting of a hard segment and 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 exhibit 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 known manufacturing 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.

[0070] At least a portion of the above-mentioned 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 strands) has a predetermined fineness.

[0071] The above-mentioned predetermined fineness can be described as high fineness, low fineness, etc. The above-mentioned high fineness can be described as preferably 470 dtex or more, more preferably 500 dtex or more, and even more preferably 620 dtex or more. The above-mentioned high fineness can be described as preferably 1120 dtex or less, more preferably 940 dtex or less, and even more preferably 800 dtex or less.

[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 the 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 of members) 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 mm.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 in a compressed state 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 stretch ratio M1 (times) is expressed by the following formula: M1 (times) = L1 / L0 when an elastic member with a natural length L0 (m) is stretched to a stretched length L1 (m).

[0080] The above stretching ratio can be a high stretching ratio, a medium stretching ratio, etc. The high stretching ratio is preferably 2.8 times or more, more preferably 3.0 times or more, and even more preferably 3.2 times or more. Also, the high stretching 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 portion of the elastic members sandwiched together becomes 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 expressed by the following formula when an elastic member with a natural length L2 (m) is stretched to a length L3 (m): M2 (times) = L3 / L2.

[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, 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, in a tensile test at 100°C. 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 expressed by the following formula: M3 (times) = L5 / L4, when an elastic member with a natural length of L4 (m) is stretched to a length of L5 (m).

[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, 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, in a tensile test at 100°C. 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, 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, in a tensile test at 50°C. 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, preferably 1.55 mN / dtex or more, more preferably 1.60 mN / dtex or more, even more preferably 1.65 mN / dtex or more, and 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, in a tensile test at 50°C. This makes it easier for the elongation ratio of the elastic members to become uniform among the welded groups.

[0091] In this specification, a tensile test can be performed as follows: (1) The elastic member is left standing in a constant temperature chamber at 50°C for two weeks. (2) The elastic member is cut to a length of 50 mm and fixed to two toothpicks with a 30 mm gap between them to create a test sample. (3) The power to the tensile testing machine (manufactured by Shimadzu Corporation, product name: AGX-50NV) and the power to the constant temperature chamber (Thermostatic Chamber, manufactured by Shimadzu Corporation, model number: TCR1L-220-X) are turned on, and the test space is heated to the test temperature (100°C or 50°C), and heating is stopped 10 minutes after the test space reaches the test temperature. (4) The test sample is placed in a chuck (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, stop heating and perform a tensile test at a speed of 500 mm / min until the elastic member breaks under the following conditions, and obtain data on the elongation ratio and tensile strength (mN). (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) Perform a total of 10 tensile tests on different test samples and adopt the average value.

[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 in 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 when 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 porosity described above is as follows: (1) A stainless steel blade (Beauty M Stainless Steel Facial / Eyebrow Shaver, 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 a 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 create a sample. (3) The sample is placed on the observation stand of an electron microscope (Keyence Corporation, Desktop Electron Microscope, VHX-D500 / D510), and the cross-section of the sample is focused at a magnification of 500x.

[0098] (4) Adjust the color tone so that the brightness of the void area becomes 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(6) Calculate the void ratio: V (%) using the following formula: V (%) = 100 × A1 / (A1 + A2) (7) Measure the void ratio a total of 10 times from different samples of the same elastic member and adopt the average value.

[0099] In the stretchable sheet according to this disclosure, the plurality of elastic members may include two or more elastic members having at least one different 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 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) contains titanium oxide in a ratio of preferably more than 0.0% by mass, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, preferably less than 3.0% by mass, more preferably 2.0% by mass or less, and even more preferably 1.5% by 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 member 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 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) 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 members 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 is caused by the elastic member being sandwiched by the welding device, and refers to a portion where the diameter of the elastic member is partially thicker. The stretched state of the stretchable sheet means the state in which the first and second sheets constituting the stretchable sheet are stretched to the 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 hygiene 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-mentioned hygiene 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, etc. The absorbent articles in the form of pant-type garments according to this disclosure may be provided with the aforementioned 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.

[0109] The present disclosure will be explained below with examples, but the present disclosure is not limited to these examples. [Production 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 above 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 have the same composition as elastic member No. 1A but different fineness. The fineness of 1E is listed in Table 1.

[0111] [Manufacturing Examples 2-5] By varying the amount of diethylamine (chain elongation inhibitor), elastic members No. 2A-2D, No. 3A-3E, No. 4A-4D, and No. 5A-5D were formed, all having the same composition but different fineness. The fineness of elastic members No. 2A-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. 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 Toreoperontex Co., Ltd. was used as elastic members No. 6A to No. 6F. The fineness of elastic members No. 6A to No. 6F is listed in Table 1. The amount of titanium dioxide and oil in each of the elastic members No. 6A to No. 6F are reference values ​​obtained by analysis.

[0113] [Manufacturing Example 6] Four elastic members No. 1A were placed between two long nonwoven fabrics (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 a pair of welded sections, and the four elastic members were fixed in a state where they were sandwiched between the group of welded sections to form an expandable sheet No. 1A. The welded section pairs were set to ensure that the two nonwoven fabrics were sufficiently welded together.

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

[0115] Elastic members No. 1A were replaced with elastic members No. 1B to No. 1E, respectively, to form stretchable sheets No. 1B to 1E. The relationship between elastic members No. 1A to No. 1E and stretchable sheets No. 1A to 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 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 tensile tests at 100°C" is written as "elongation at break / 100°C", "tensile strength at 3.0 times elongation in tensile tests at 100°C" is written as "3 times strength / 100°C", and "tensile strength at 5.0 times elongation in tensile tests at 100°C" is written as "5 times strength / 100°C". Furthermore, 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] Elastic 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 only 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 or not there are at least two consecutive non-breakable regions between welded pairs in the first direction, and (ii) whether or not the flattened portion has an outer diameter smaller than the distance between welded pairs when the stretchable sheet is stretched. The results are shown in Table 1. In Table 1, the item related to (iv) "whether or not there are at least two consecutive non-breakable regions between welded pairs in the first direction" is written as "non-breakable region," where "present" means that there are two consecutive regions and "absent" means that there are not two consecutive regions. Furthermore, in Table 1, the item concerning "whether the flattened portion has an outer diameter smaller than the distance between the welded portion pairs when the stretchable sheet is stretched" is denoted as "specified flattened portion," where "Yes" means that the elastic member 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, and "No" means that the elastic member does not have a flattened portion and the sandwiched 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 the welded portion pairs when the stretchable sheet is stretched, and combinations thereof.

[0120]

[0121] 1 Disposable diaper 2 Stretchable sheet 21 First nonwoven fabric 23 Second nonwoven fabric 25 Elastic member 31 Welded pair 33a First welded part 33b Second welded part 35 Welded group D1 First direction D2 Second direction D Spacing W0 Natural width W1 Stretched width

Claims

1. An expandable sheet having a first direction and a second direction perpendicular to each other, wherein the expandable sheet comprises a first sheet having heat-welding properties, a second sheet having heat-welding properties, and a plurality of elastic members extending in the first direction and spaced apart in the 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) fixed in a state where welding pairs for welding the first and second sheets, which are arranged at both ends in the second direction, are sandwiched between a plurality of welding groups 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.

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 or 2, wherein at least a portion of the plurality of elastic members further have a tensile strength of 0.90 to 1.30 mN / dtex at 5.0 times elongation in the tensile test at 100°C.

4. An expandable sheet having a first direction and a second direction that are orthogonal to each other, wherein the expandable sheet comprises a first sheet having heat-welding properties, a second sheet having heat-welding properties, and a plurality of elastic members extending in the first direction and spaced apart in the second direction between the first sheet and the second sheet, wherein at least a portion of the plurality of elastic members is (i) arranged in an extended state in the first direction and has a fineness of 60 to 470 dtex, (ii) a pair of welded portions arranged at both ends in the second direction is fixed in a state of being sandwiched between a plurality of welded portions arranged 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.

5. The stretchable sheet according to claim 4, wherein at least a portion of the plurality of elastic members further have 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 or 5, wherein at least a portion of the plurality of elastic members further have 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 have 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 7, 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 8, 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 9, 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 or 11, wherein the multifilament has a porosity of 15.0 to 30.0%.

13. The stretchable sheet according to any one of claims 1 to 12, 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 13, 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 14, wherein at least a portion of the plurality of elastic members contains 0.05 to 5.0% by mass of an oil agent.

16. The stretchable sheet according to any one of claims 1 to 15, wherein, in an extended state, each of the plurality of elastic members has a region between welded pairs that is partitioned by two welded pairs that are continuous in a first direction, and at least a portion of the plurality of elastic members has at least two continuous non-broken regions between welded pairs in the first direction, wherein the region between welded pairs is partitioned by a region in which at least a portion of the elastic member does not have a fractured portion.

17. The stretchable sheet according to any one of claims 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.

18. A pant-type absorbent article comprising the stretchable sheet described in any one of claims 1 to 17.

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

Images