阅读说明：本技术 吸收性物品 (Absorbent article ) 是由 园田纯子 市川诚 川端训功 田中嘉则 于 2018-02-19 设计创作，主要内容包括：提供一种能够兼顾穿戴时的腹侧部与背侧部的分离难度和拆下时的长度方向上的分离容易性并且进一步进行改善的吸收性物品。在吸收性物品中,腹侧部(11)以及背侧部(13)的宽度方向上的至少一端部相互间以重叠的状态在接合部(14a)处互相接合。接合部包括多个熔融接合部(30)。熔融接合部包括：热粘接部(MC),其是将腹侧部的多个片材和背侧部的多个片材在厚度方向上互相热粘接而成的；以及侧壁部(SW),将腹侧部的多个片材和背侧部的多个片材在厚度方向上互相热粘接从而形成该侧壁部(SW),以使该侧壁部(SW)从热粘接部的周缘沿着厚度方向呈筒形延伸。热粘接部的厚度方向上的位置自腹侧部与背侧部之间的分界偏移。侧壁部的厚度方向上的尺寸大于热粘接部的厚度方向上的尺寸。侧壁部的长度方向上的尺寸小于侧壁部的宽度方向上的尺寸。(Provided is an absorbent article which can be further improved while satisfying both the difficulty of separation between a front side portion and a back side portion when worn and the ease of separation in the longitudinal direction when removed. In the absorbent article, at least one end portion in the width direction of the front side portion (11) and the back side portion (13) are joined to each other at a joint portion (14a) in a superposed state. The joint includes a plurality of fusion joints (30). The fusion joint includes: a heat-bonding section (MC) formed by mutually heat-bonding a plurality of sheets of the ventral section and a plurality of sheets of the dorsal section in the thickness direction; and a side wall Section (SW) formed by thermally bonding the plurality of sheets of the front side section and the plurality of sheets of the back side section to each other in the thickness direction so that the side wall Section (SW) extends in a cylindrical shape in the thickness direction from the peripheral edge of the thermally bonded section. The position of the thermal bonding portion in the thickness direction is offset from the boundary between the ventral portion and the dorsal portion. The dimension of the side wall portion in the thickness direction is larger than the dimension of the thermal bonding portion in the thickness direction. The dimension of the side wall portion in the longitudinal direction is smaller than the dimension of the side wall portion in the width direction.)

1. An absorbent article comprising a front side portion and a back side portion, at least one end portion in a width direction of the front side portion and at least one end portion in a width direction of the back side portion being joined to each other at a joint portion in a state of overlapping in a thickness direction along a length direction, wherein,

the joint comprises a plurality of fusion joints,

the plurality of fusion splices each comprising:

a heat-bonded portion formed by thermally bonding the plurality of sheets of the front side portion and the plurality of sheets of the back side portion to each other in the thickness direction; and

a side wall portion formed by thermally bonding the plurality of sheets of the front side portion and the plurality of sheets of the back side portion to each other in the thickness direction so as to extend in a cylindrical shape in the thickness direction from a peripheral edge of the thermally bonded portion,

the position in the thickness direction of the thermal bonding portion is offset from a boundary between the front side portion and the back side portion,

a dimension in the thickness direction of the side wall portion is larger than a dimension in the thickness direction of the thermal bonding portion,

a dimension of the side wall portion in the longitudinal direction is smaller than a dimension of the side wall portion in the width direction.

2. The absorbent article of claim 1,

the joint has a pressure-bonding section array in which the plurality of fusion-bonded sections are arranged at intervals along the longitudinal direction.

3. The absorbent article of claim 2, wherein,

the joint has only one row of the crimping portions as the plurality of fusion joints.

4. The absorbent article of claim 2, wherein,

the joined portion has, in the longitudinal direction, a waist-side end region including an end portion near a waist opening portion, a leg-side end region including an end portion far from the waist opening portion, and a central region between the waist-side end region and the leg-side end region,

at least the waist side end regions and the central region have only one row of the rows of crimps as the plurality of fusion splices.

5. The absorbent article according to any one of claims 1 to 4, wherein,

the maximum dimension in the longitudinal direction of the thermal bonding section is equal to or greater than the maximum dimension in the width direction of the thermal bonding section.

6. The absorbent article according to any one of claims 1 to 5, wherein,

the dimension of the side wall portion in the longitudinal direction is 50 to 200 [ mu ] m,

the dimension of the side wall portion in the width direction is 100 to 400 [ mu ] m.

7. The absorbent article of claim 6,

both ends in the width direction of the front side portion and the back side portion are joined to each other at a pair of joining portions including the joining portion in a state of being overlapped in the thickness direction along the longitudinal direction,

both of the pair of joints include the plurality of fusion joints,

the difference between the dimension in the width direction of the side wall portion of one of the pair of joining portions and the dimension in the width direction of the side wall portion of the other joining portion is within 40 μm.

8. The absorbent article according to claim 6 or 7,

the difference between the inner dimension and the outer dimension of the side wall portions in the width direction of each of the pair of joining portions is within 40 μm.

9. The absorbent article according to any one of claims 1 to 8, wherein,

the thermal bonding portion is closer to the stomach-side portion than to the back-side portion in the thickness direction within the side wall portion.

10. The absorbent article according to any one of claims 1 to 9, wherein,

in the joint portion, an end edge in the longitudinal direction of the front side portion and an end edge in the longitudinal direction of the back side portion are offset from each other in the longitudinal direction.

Technical Field

The present invention relates to an absorbent article.

Background

There is known an absorbent article (exemplified by a pants-type disposable diaper) including a front side portion and a back side portion, wherein at least one end portion in a width direction of the front side portion and at least one end portion in a width direction of the back side portion are joined to each other at least one joining portion in a state of being overlapped in a thickness direction along a longitudinal direction. For example, patent document 1 discloses a pants-type disposable diaper. The pants-type disposable diaper includes a pair of joined portions (side seal portions) each having a plurality of welded portions formed by heat sealing or ultrasonic sealing. Further, patent document 2 discloses a disposable diaper. In this disposable diaper, one end of both end portions in the width direction of the abdomen-side portion and the back-side portion (both right and left side portions of the waist opening) is joined to each other to form a joined portion, and the other end is provided with a joining member which is not joined and can be joined to each other. Patent document 3 discloses an apparatus for performing ultrasonic sealing.

Disclosure of Invention

Problems to be solved by the invention

In an absorbent article such as a pants-type disposable diaper, when a wearer or a caregiver of the wearer removes a used absorbent article from the wearer, a method of peeling a front side portion and a back side portion apart from each other in a longitudinal direction at a joint portion is generally employed. Therefore, it is necessary to join the ventral-side portion and the dorsal-side portion at the joint portion so as to be easily separated in the longitudinal direction for detachment. On the other hand, when the absorbent article is worn on the wearer, a force is mainly applied to the joint portion in the lateral direction of the wearer, that is, in the width direction. Therefore, it is necessary to join the front and back portions at the joint portion so as to be difficult to separate in the width direction for wearing. This applies not only to an absorbent article in which both ends in the width direction of the abdomen-side portion and the back-side portion (both the left and right side portions of the waist opening portion) are joined to each other to form a pair of joined portions, but also to an absorbent article in which one of the ends is joined to each other to form a joined portion and the other end is left unjoined to form a joinable joining member that can be joined to each other. In this way, it is desired to achieve both the difficulty of separating the front and back side portions when the absorbent article is worn and the ease of separating the front and back side portions when the absorbent article is removed.

In patent document 1, the area of each welded portion in the vicinity of the waist opening is made relatively small, and the area of each welded portion in the region distant from the waist opening is made relatively large. In this case, it is considered that the abdomen-side portion and the back-side portion are more easily separated in the vicinity of the waist opening portion than in the region distant from the waist opening portion. However, at the welded portion, the plurality of sheets of the ventral portion and the plurality of sheets of the dorsal portion are all laminated together, melted and pressed to be welded together. Therefore, in order to peel the front and back portions apart, it is necessary to peel a welded portion formed by welding all the sheets of the front and back portions or a region in the vicinity thereof. Therefore, it cannot be said that the force for peeling, i.e., the force for separation, is necessarily small, and it may be difficult for the wearer to peel.

An object of the present invention is to provide an absorbent article that can achieve both difficulty in separating the front and back side portions when worn and ease of separation in the longitudinal direction when removed, and that is further improved.

Means for solving the problems

An absorbent article (1) according to the present invention includes a front side portion and a back side portion, at least one end portion in a width direction of the front side portion and at least one end portion in a width direction of the back side portion being joined to each other at a joining portion in a state of overlapping in a thickness direction along a length direction, wherein the joining portion includes a plurality of fusion joining portions each including: a heat-bonded portion formed by thermally bonding the plurality of sheets of the front side portion and the plurality of sheets of the back side portion to each other in the thickness direction; and a side wall portion formed by thermally bonding the plurality of sheets of the front side portion and the plurality of sheets of the back side portion to each other in the thickness direction so as to extend in a cylindrical shape along the thickness direction from a peripheral edge of the thermal bonding portion, a position in the thickness direction of the thermal bonding portion being offset from a boundary between the front side portion and the back side portion, a dimension in the thickness direction of the side wall portion being larger than a dimension in the thickness direction of the thermal bonding portion, and a dimension in the length direction of the side wall portion being smaller than a dimension in the width direction of the side wall portion.

The absorbent article includes a heat-bonded portion and a side wall portion extending in a cylindrical shape in a thickness direction from a peripheral edge of the heat-bonded portion at a fusion-bonded portion of the bonded portion, and a dimension in a length direction of the side wall portion (a thickness in the length direction of the tube) is smaller than a dimension in a width direction (a thickness in the width direction of the tube). Thus, the longitudinal portion of the tube of the side wall portion is easily broken, and the width portion is not easily broken. In addition, the dimension (thickness) of the side wall portion in the thickness direction is larger than the dimension (thickness) of the thermal bonding portion in the thickness direction. That is, in the thermal bonding portion, the stacked plurality of sheets of the front side portion and the plurality of sheets of the back side portion are, for example, melted, pressurized, and bonded, whereby the dimension in the thickness direction is made small (thin). Thus, at the thermal bonding portion, the plurality of sheets are relatively strongly bonded to each other. On the other hand, in the side wall portion, the stacked plurality of sheets of the front side portion and the plurality of sheets of the back side portion are, for example, melted at the periphery of the heat-bonded portion and joined without applying pressure, whereby the dimension in the thickness direction is made large (thick). Thus, at the side wall portion, the plurality of sheets are relatively weakly joined to each other. The position of the thermal bonding portion in the thickness direction is offset from the boundary between the front and back portions. Therefore, when the ventral portion and the dorsal portion are separated from each other, the thermal bonding portion is not included in the separation portion.

For the above reasons, when the ventral portion and the dorsal portion of the joint portion are peeled apart from each other in the longitudinal direction, the joint portion can start to be broken at the side wall portion that is relatively weakly joined and at the portion in the longitudinal direction where the joint portion is likely to be broken. Thus, the front and back portions can be easily peeled apart from each other along the interface between the front and back portions, and the front and back portions need not be peeled apart from each other at the strongly bonded thermal bonding portion or the vicinity thereof. Therefore, in this absorbent article, the abdomen-side portion and the back-side portion of the joint portion can be peeled apart from each other with a relatively small force. Specifically, the ventral portion and the dorsal portion can be easily separated from each other along the interface between the two portions with a relatively small force from the outer surface of the tube to the inner surface of the tube in the side wall portion at one longitudinal side portion of the side wall portion. In addition, when the front and back portions can be peeled off from each other from the outer surface of the tube to the inner surface of the tube at the longitudinal direction portion of the side wall portion, the front and back portions can be easily peeled off from each other from the inner surface of the tube to the outer surface of the tube at the other longitudinal direction portion of the side wall portion. This makes it possible to easily peel the ventral portion and the dorsal portion of the joint portion apart from each other. That is, the operation of the wearer to peel the ventral portion and the dorsal portion apart from each other can be assisted.

On the other hand, when the wearer wears the absorbent article, a force applied to the joint portion according to the movement of the wearer acts mainly in the width direction. Further, in this absorbent article, the dimension in the width direction of the side wall portion (the thickness in the width direction of the tube) is larger than the dimension in the longitudinal direction (the thickness in the longitudinal direction of the tube). Therefore, when a large force in the width direction is applied to the side wall portion, the portion of the side wall portion having a large thickness in the width direction receives the force. Therefore, even if a crack occurs in the surface of the side wall portion facing the inside of the tube from the outside surface of the tube, the crack may be in any of a state of being separated from the upper surface or the lower surface of the side wall portion before reaching the inside surface of the tube of the side wall portion, and a state of being stopped by reaching the thermal bonding portion having high bonding strength. Therefore, the front side portion and the back side portion of the joint portion can be prevented from being peeled apart from each other and the absorbent article can be prevented from being broken when worn.

In this way, by forming the side wall portion having a short dimension in the longitudinal direction and a long dimension in the width direction around the fusion bonded portion, the ease of peeling, i.e., the ease of separation, can be made different in the longitudinal direction and the width direction, i.e., anisotropy can be imparted to the fusion bonded portion. This makes it possible to further improve the ease of separation when the absorbent article is removed and the difficulty of separation between the front and back side portions when the absorbent article is worn.

According to the absorbent article of the above (1), the absorbent article of the present invention may be such that (2) the joint has a row of pressure bonded parts in which the plurality of fusion-bonded parts are arranged at intervals along the longitudinal direction.

In this absorbent article, a plurality of fusion-bonded portions are arranged at intervals in the longitudinal direction (a row of pressure-bonded portions). Therefore, when the absorbent article is removed, the abdomen-side portion and the back-side portion can be peeled off from each other with a relatively small force over a relatively long distance in the longitudinal direction. This makes it easier to peel the ventral portion and the dorsal portion of the joint apart from each other.

According to the absorbent article of the above (2), the absorbent article of the present invention may be such that (3) the joint has only one row of the pressure-bonded parts as the plurality of fusion-bonded parts.

When the absorbent article has a plurality of rows of the crimping portions in the width direction, there is a possibility that: the force for peeling the front and back side portions in the longitudinal direction is distributed in each row, and the crack due to peeling develops in the direction inclined with respect to the longitudinal direction and in the width direction, and the force required for peeling is large. In addition, the plurality of rows may have the same bonding strength, but the bonding strength may vary depending on the production yield, and even if the fusion-bonded portion of one row is broken, the fusion-bonded portion of the other row may not be broken. Therefore, the absorbent article has only one row of the pressure bonded parts as a plurality of fusion bonded parts. Therefore, when the absorbent article is removed, the force of separating the front side portion and the back side portion in the longitudinal direction can be concentrated on the row of the pressure-bonded sections. This makes it possible to easily peel the ventral portion and the dorsal portion of the joint portion apart from each other with a small force.

According to the absorbent article of the above (2), the absorbent article of the present invention may be such that (4) the joint has, in the longitudinal direction, a waist-side end region including an end portion close to a waist opening, a leg-side end region including an end portion distant from the waist opening, and a central region between the waist-side end region and the leg-side end region, and at least the waist-side end region and the central region have only one row of the rows of the pressure bonded portions as the plurality of fusion-bonded parts.

The absorbent article has a plurality of fused joints arranged in a line at least in the waist-side end regions and the central region at the joints. Therefore, when the absorbent article is removed, the force of separating the front side portion and the back side portion in the longitudinal direction can be concentrated on the row of the plurality of fusion-bonded portions, and the above state can be achieved up to at least the central region in the longitudinal direction of the bonded portions. This makes it possible to easily peel the ventral portion and the dorsal portion of the joint portion apart from each other with a smaller force, and to suppress the joint portion from being cracked in the width direction or from being cracked in the width direction.

According to the absorbent article of any one of the above (1) to (4), in the absorbent article of the present invention, (5) the maximum dimension in the longitudinal direction of the heat-bonded portion may be equal to or larger than the maximum dimension in the width direction of the heat-bonded portion.

In this absorbent article, the maximum dimension in the longitudinal direction of the heat-bonded portion is larger than the maximum dimension in the width direction, that is, the heat-bonded portion has a shape that is long in the longitudinal direction. This makes it possible to further reduce the thickness of the tube formed by the side wall portion in the longitudinal direction and to further increase the thickness in the width direction. Therefore, when the absorbent article is removed, the front side portion and the back side portion can be more easily separated from the thin portion, and even if a large force is applied in the width direction during wearing, the force is received by the thick portion of the side wall portion, and therefore, the front side portion and the back side portion of the joint portion can be prevented from being peeled apart and the absorbent article can be prevented from being broken.

The absorbent article of the present invention according to any one of the above (1) to (5), (6) the side wall portion may have a dimension (one side) in the longitudinal direction of 50 μm to 200 μm and a dimension (one side) in the width direction of 100 μm to 400 μm.

In the absorbent article, the side wall portion has a longitudinal dimension of 50 to 200 μm and a lateral dimension of 100 to 400 μm. Therefore, when a large force is applied to the side wall in the longitudinal direction, the ventral portion and the dorsal portion can be easily peeled apart, and even if a large force is applied in the width direction, the ventral portion and the dorsal portion can be prevented from being peeled apart or broken. When the longitudinal dimension is less than 50 μm, peeling is likely to occur when the garment is worn (by a force along the width direction), and when the longitudinal dimension is greater than 200 μm, peeling may be difficult when the garment is removed. Further, in the case where the width direction dimension is less than 100 μm, peeling is likely to occur at the time of wearing, and in the case where the width direction dimension is more than 400 μm, peeling may be difficult (by a force along the longitudinal direction) at the time of detaching.

According to the absorbent article of the invention described in (6), in the absorbent article of the invention, (7) both end portions in the width direction of the front side portion and the back side portion may be joined to each other at a pair of joining portions including the joining portion in a state of overlapping in the thickness direction along the longitudinal direction, both of the pair of joining portions may include the plurality of fusion-joined portions, and a difference between a dimension (one side) in the width direction of the side wall portion of one of the pair of joining portions and a dimension (one side) in the width direction of the side wall portion of the other joining portion may be within 40 μm.

In this absorbent article, the dimension in the width direction of the side wall portion (the thickness in the width direction of the tube) is set to be substantially the same in one joined portion in the width direction (for example, the left joined portion) and the other joined portion in the width direction (for example, the right joined portion). Therefore, when the wearer intends to remove the absorbent article, both the left and right joint portions can be peeled off with substantially the same force. This makes it easier for the wearer to peel the left and right joint portions apart.

According to the absorbent article of the above (6) or (7), the absorbent article of the present invention may be such that (8) a difference between an inner dimension and an outer dimension of the side wall portions of the pair of joined portions in the width direction is within 40 μm.

In this absorbent article, the inner dimension (tube thickness) and the outer dimension (tube thickness) in the width direction of one side wall portion are substantially the same. Therefore, the force required to peel off the inner portion in the width direction is substantially the same as the force required to peel off the outer portion with respect to one side wall portion. Therefore, when the wearer intends to remove the absorbent article, the direction of the force tending to peel the front and back portions apart can be suppressed from becoming a direction inclined with respect to the longitudinal direction and a width direction, and the front and back portions can be suppressed from breaking in the direction inclined with respect to the longitudinal direction and the width direction.

According to the absorbent article of any one of (1) to (8) above, in the absorbent article of the present invention, (9) the heat-bonded portion may be located closer to the abdominal portion than to the back portion in the thickness direction in the side wall portion.

In this absorbent article, the thermal bond portion is located in the cylindrical side wall portion at a position close to the abdomen side portion in the thickness direction. Thus, when the wearer bends over and peels off the abdomen-side portion and the back-side portion of his disposable pants, the heat-bonded portion is easily visible, and therefore the wearer can more reliably grasp the vicinity of the fused portion with the fingers and perform the peeling operation. This makes it easier to peel the ventral portion and the dorsal portion of the joint apart from each other.

According to the absorbent article of any one of the above (1) to (9), the absorbent article of the present invention may be such that (10) in the joined portion, the end edge in the longitudinal direction of the front side portion and the end edge in the longitudinal direction of the back side portion are offset from each other in the longitudinal direction.

In this absorbent article, the longitudinal end edges of the front side portion and the longitudinal end edges of the back side portion are offset in the longitudinal direction. Therefore, when the wearer intends to remove the absorbent article, the wearer can more easily grasp the end portion of the abdomen-side portion with one hand and the end portion of the back-side portion with the other hand. This makes it easier to peel the ventral portion and the dorsal portion of the joint apart from each other.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide an absorbent article that can achieve both difficulty in separating the front and back side portions when worn and ease of separation in the longitudinal direction when removed.

Drawings

Fig. 1 is a perspective view showing a structural example of a disposable diaper according to an embodiment.

Fig. 2 is a plan view showing a developed state of the disposable diaper of fig. 1.

Fig. 3 is a plan view showing a configuration example of a joint portion of the disposable diaper of fig. 1.

Fig. 4 is a schematic diagram for explaining a configuration example of the joint portion of fig. 3.

Fig. 5 is a plan view and a perspective view showing a structure of a fusion bonded portion of the bonded portion of fig. 4.

Fig. 6 is a schematic diagram for explaining a state of peeling of the fusion-spliced portion of fig. 5.

Fig. 7 is a schematic diagram for explaining a method of forming a joint portion of the disposable diaper of fig. 1.

Fig. 8 is a schematic diagram for explaining another configuration example of the joint part of fig. 3.

Fig. 9 is a plan view showing a structure of a fusion bonded portion of the bonded portion of fig. 8.

FIG. 10 is an SEM photograph showing a cross section of a fusion-bonded part of the example.

Fig. 11 is a graph showing a relationship between the shape and strength of the fusion-bonded portion.

Fig. 12 is a graph showing a relationship between the shape and strength of the molten bond.

Fig. 13 is a graph showing a relationship between the shape and strength of the fusion-bonded portion.

Detailed Description

Hereinafter, an absorbent article according to an embodiment of the present invention will be described by taking a pants-type disposable diaper (hereinafter also simply referred to as "disposable diaper") as an example. However, the present invention is not limited to this example, and can be applied to various absorbent articles within a range not departing from the scope of the subject matter of the present invention. Examples of the absorbent article include a so-called 3-sheet type or 2-sheet type disposable diaper, and a disposable diaper in which a joint portion is formed on one of left and right side portions of a waist opening portion, and a joint (engaging) member capable of being joined (or locked) to each other is formed on the other side portion without forming a joint portion.

(embodiment 1)

Fig. 1 and 2 are views showing a disposable diaper 1 according to the present embodiment. Fig. 1 is a perspective view showing the structure of a disposable diaper 1, and fig. 2 is a plan view showing a state in which the disposable diaper 1 is unfolded. The disposable diaper 1 has a longitudinal direction L, a width direction W orthogonal to the longitudinal direction L, and a thickness direction T orthogonal to the longitudinal direction L and the width direction W in the state shown in fig. 2, and has a central axis CL passing through the center in the width direction W and extending in the longitudinal direction L, and a central axis CW passing through the center in the length direction L and extending in the width direction W. The direction toward the center axis CL is an inner direction in the width direction W, and the direction away from the center axis CL is an outer direction in the width direction W. The direction toward the central axis CW is an inner direction in the longitudinal direction L, and the direction away from the central axis CW is an outer direction in the longitudinal direction L. The disposable diaper 1 placed on a horizontal plane is referred to as "planar view" when viewed from above in the vertical direction along the thickness direction T, and the shape recognized in the planar view is referred to as "planar shape". The "skin side" refers to a side relatively close to the skin surface of the wearer in the thickness direction T of the disposable diaper 1 when the disposable diaper 1 is worn, and the "non-skin side" refers to a side relatively distant from the skin surface of the wearer in the thickness direction T of the disposable diaper 1 when the disposable diaper 1 is worn. The longitudinal direction L, the width direction W, and the thickness direction T shown in fig. 2 are also used for each direction of the disposable diaper 1 in the state shown in fig. 1.

The disposable diaper 1 is an underpants type diaper including a front side portion 11, a back side portion 13, and an intermediate portion 12 between the front side portion 11 and the back side portion 13. The abdomen-side portion 11 is a portion of the disposable diaper 1 that contacts the abdomen of the wearer. The intermediate portion 12 is a portion of the disposable diaper 1 that contacts the crotch of the wearer. The back side portion 13 is a portion of the disposable diaper 1 that contacts the buttocks and/or the back of the wearer. Both end portions 11a and 11b in the width direction W of the abdomen-side portion 11 and both end portions 13a and 13b in the width direction W of the back-side portion 13 are joined to each other by a pair of joining portions 14a and 14b in a state of being overlapped in the thickness direction T along the longitudinal direction L. Further, in the disposable diaper 1, the waist opening WO is formed by the end portion 11e on the opposite side to the intermediate portion 12 in the longitudinal direction L of the abdomen-side portion 11 and the end portion 13e on the opposite side to the intermediate portion 12 in the longitudinal direction L of the back-side portion 13. In the disposable diaper 1, the pair of leg openings LO, LO are formed by the both side portions 12a, 12b in the width direction W of the intermediate portion 12.

The directions of the disposable diaper 1 in the state shown in fig. 1 are as follows. The longitudinal direction L is a direction along the outer shape of the disposable diaper 1 from the abdomen-side portion 11 (or the back-side portion 13) toward the back-side portion 13 (or the abdomen-side portion 11) through the intermediate portion 12. The width direction W is a direction along the outer shape of the disposable diaper 1 along the surface of the joint portion 14a (or the joint portion 14b) and from the inner end edge of the joint portion 14a (or the joint portion 14b) along the central portion of the peripheral surface of the stomach side portion 11 or the back side portion 13 to the inner end edge of the joint portion 14b (or the joint portion 14a) and along the surface of the joint portion 14a (or the joint portion 14 b). The thickness direction T is a direction perpendicular to a plane tangent to the outer surface of the disposable diaper 1, i.e., a tangent plane. In particular, the longitudinal direction, the width direction, and the thickness direction of the pair of joint portions 14a and 14b in the state shown in fig. 1 are the same as the longitudinal direction L, the width direction W, and the thickness direction T in the state shown in fig. 2.

The disposable diaper 1 includes an absorbent main body 10. The absorbent body 10 includes a liquid-permeable top sheet 2, a liquid-impermeable back sheet 3, and an absorbent body 4 located between the top sheet 2 and the back sheet 3. Examples of the top sheet 2 include a liquid-permeable nonwoven fabric or woven fabric, a synthetic resin film having liquid-permeable holes formed therein, and a composite sheet of the above materials. Examples of the back sheet 3 include a liquid-impermeable nonwoven fabric, a synthetic resin film, a composite sheet of the above materials, and an SMS nonwoven fabric. In the present embodiment, the absorber 4 includes an absorbent core and a core cladding that surrounds the absorbent core. Examples of the absorbent body 4 include pulp fibers, synthetic fibers, and absorbent polymers. The absorbent body 4 is bonded to the front sheet 2 and the back sheet 3 with an adhesive, and the front sheet 2 and the back sheet 3 are bonded to each other with an adhesive at their peripheral edge portions. As the adhesive, a known material generally used in disposable diapers, for example, a thermoplastic adhesive can be used.

The disposable diaper 1 further comprises a liquid-impermeable cover sheet 5. In the present embodiment, the cover sheet 5 includes a cover sheet 5a positioned on the skin side and a cover sheet 5b positioned on the non-skin side, and the cover sheet 5a and the cover sheet 5b are in the thickness direction TThe upper portions are laminated and bonded together with an adhesive or the like. In the present embodiment, both ends in the longitudinal direction L of the covering sheet 5b are folded back toward the skin side so as to cover both ends in the longitudinal direction L of the covering sheet 5 a. The covering sheet 5b at the folded-back position of the abdomen-side portion 11 constitutes an end portion 11e of the abdomen-side portion 11, and the covering sheet 5b at the folded-back position of the back-side portion 13 constitutes an end portion 13e of the back-side portion 13. The absorbent main body 10 is disposed on the skin-side surface of the cover sheet 5 such that the topsheet 2 faces the skin. In the disposable diaper 1, the outer surface of the disposable diaper 1, which is the non-skin side surface, is formed by the cover sheet 5b, and the inner surface of the disposable diaper 1, which is the skin side surface, is formed by the topsheet 2, and the cover sheets 5b and 5b of the end portions 11e and 13e, respectively. Examples of the material of the cover sheet 5 include any liquid impermeable sheet such as impermeable nonwoven fabric or synthetic resin film, a composite sheet of the above materials, SB nonwoven fabric, and SMS nonwoven fabric. Examples of the material of the cover sheet 5 include polyolefin materials such as polypropylene and polyethylene. The weight per unit area of the cover sheet 5 is, for example, 5g/m²～100g/m²Preferably 10g/m²～50g/m². The dimension (thickness) of the cover sheet 5 in the thickness direction T is, for example, 0.2mm to 5mm, preferably 0.2mm to 2 mm. The cover sheet 5 may be one sheet or may not be folded back.

The disposable diaper 1 further includes a pair of liquid-impermeable leakage preventing walls 6a, 6b and elastic members 8(8a, 8b, 8c, 8d, 8 e). The pair of leakage preventing walls 6a and 6b are disposed on both sides of the top sheet 2 in the width direction W along the longitudinal direction L. The elastic members 8a extend in the width direction W between the cover sheet 5a and the cover sheet 5b at the stomach side portion 11 and are arranged and sandwiched at intervals in the longitudinal direction L, and the elastic members 8b extend in the width direction W between the cover sheet 5a and the cover sheet 5b at the back side portion 13 and are arranged and sandwiched at intervals in the longitudinal direction L. The elastic members 8a and 8b are used to stretch and contract the waist opening WO. The elastic member 8c is continuously disposed so as to extend substantially along the longitudinal direction L at both end portions in the width direction W of a portion on the back side portion 13 side of the intermediate portion 12 and extend along the width direction W at a central portion of the intermediate portion 12. The elastic member 8c allows both the pair of leg openings LO and LO to expand and contract. Elastic members 8d and 8e extending in the longitudinal direction L are disposed at the inner ends of the pair of leakage preventing walls 6a and 6b in the width direction W, respectively. The elastic member 8d is for expanding and contracting the leakage preventing wall 6a, and the elastic member 8e is for expanding and contracting the leakage preventing wall 6 b. The elastic member 8 may be a rubber band.

Next, the structure of each of the pair of joining portions 14a and 14b will be described. Since the basic structures of the joint portion 14a and the joint portion 14b are substantially the same, the joint portion 14a will be mainly described below.

Fig. 3 is a plan view schematically showing an example of the structure of the joint portion 14a of the disposable diaper 1. Fig. 3 is a view of the joint portion 14a of the disposable diaper 1 of fig. 1 as viewed from the back side portion 13 side. The joining portion 14a is formed by joining the end portion 11a of the front side portion 11 in the width direction W and the end portion 13a of the back side portion 13 in the width direction W so as to overlap in the thickness direction T along the longitudinal direction L. The dimension of the joint portion 14a in the longitudinal direction L and the dimension in the width direction W are not particularly limited, and examples thereof include 50mm to 250mm and 3mm to 20 mm. In the present embodiment, the joint portion 14a is formed by shifting the end edge 11ae in the longitudinal direction L of the end portion 11a of the front side portion 11 by a predetermined length Δ in the longitudinal direction L with respect to the end edge 13ae in the longitudinal direction L of the end portion 13a of the back side portion 13_CThe joining is performed in the manner of (1). As a_CThe size of (A) is, for example,. + -. 0.5mm to 10 mm. The joint 14a includes a plurality of fusion joints 30. That is, the end portion 11a and the end portion 13a are joined by at least a plurality of fusion-joined portions 30. In the present embodiment, the fusion-bonded portion 30 is formed by an ultrasonic sealing method. The joining portion 14a may be joined to all or a part of the portion other than the portion where the plurality of fusion-joined portions 30 are formed, for example, with an adhesive (hot melt adhesive, for example).

In the present embodiment, the plurality of fusion-bonded portions 30 are arranged at intervals along the longitudinal direction L. That is, the joint 14a has a pressure-bonding section row 30L in which a plurality of fusion-bonded sections 30 are arranged at intervals along the longitudinal direction L. In the present embodiment, the joint portion row 30L is one row in the joint portion 14 a. However, the pressure-bonding section row 30L is not limited to one row, and a plurality of rows may be arranged in the width direction W at intervals entirely or partially. In the present embodiment, the interval between the molten bond portions 30 is constant. However, the interval between the molten bond portions 30 may vary depending on the position.

The joint portion 14a has, in the longitudinal direction L, a waist-side end region 21 including an end portion near the waist opening WO, a leg-side end region 23 including an end portion distant from the waist opening WO and near the leg opening LO, and a central region 22 between the waist-side end region 21 and the leg-side end region 23. The waist-side end region 21 is a region in the range of 1/8 to 1/3 from the end of the waist opening WO of the joint 14a in the longitudinal direction L, the leg-side end region 23 is a region in the range of 1/8 to 1/3 from the end of the leg opening LO of the joint 14a in the longitudinal direction L, and the central region 22 is the remaining region. Wherein the waist-side end region 21 and the leg-side end region 23 do not have to have the same length in the longitudinal direction L. In the present embodiment, both the waist-side end region 21 and the leg-side end region 23 are regions in the range of 1/5. In the present embodiment, the waist-side end region 21, the center region 22, and the leg-side end region 23 have a row of pressure-bonded sections 30L along the longitudinal direction L. However, each region may have a plurality of rows of the pressure-bonding sections 30L, or may partially have one row of the pressure-bonding sections 30L and partially have a plurality of rows of the pressure-bonding sections 30L.

Fig. 4 is a schematic diagram for explaining the structure of the joint portion 14a of fig. 3. In this figure, the elastic members 8a, 8b, and 8c are omitted. Fig. 4 (a) is a schematic view of the engaging portion 14a viewed from the end portion side in the width direction W. This figure shows an example of a laminated state of the cover sheets 5 at the joint portion 14 a. In the present embodiment, at the end 11a of the abdomen-side portion 11, the end of the cover sheet 5b on the side of the waist opening WO in the longitudinal direction L is folded back toward the skin so as to cover the end of the cover sheet 5a in the longitudinal direction L. Thus, the end portion 11a includes a region a where three cover sheets, i.e., the cover sheet 5B, the cover sheet 5a, and the folded-back cover sheet 5B, are laminated, and a region B where two cover sheets, i.e., the cover sheet 5a and the cover sheet 5B, are laminated. Similarly, at the end 13a of the back portion 13, the end of the covering sheet 5b on the side of the waist opening WO in the longitudinal direction L is folded back toward the skin so as to cover the end of the covering sheet 5a in the longitudinal direction L. Thus, the end portion 13a has a region a where three cover sheets are laminated and a region B where two cover sheets are laminated. As indicated by the open arrows in the figure, the end portions 11a and 13a are stacked and joined so as to overlap each other in the thickness direction T, thereby forming the joint portion 14 a. In the present embodiment, the end portion 11a and the end portion 13a are joined to each other in the region a and to each other in the region B. The size of the region A is not particularly limited, and may be, for example, 10mm to 100 mm. The number of layers of the covering sheets 5 of each of the front and back portions 11, 13 is not particularly limited, and may be one layer or two or more layers. The cover sheet 5 may not be folded back.

The end portions 11a and 13a at the joint portion 14a are joined by at least a plurality of fusion joining portions 30. Fig. 4 (b) is a schematic view of the joint portion 14a as viewed from the back side portion 13 side in the thickness direction T. This figure shows an example of the arrangement of the fusion splice 30. In the present embodiment, as the pressure-bonding section row 30L, a row of pressure-bonding section rows 31L is arranged in the waist-side end region 21, a row of pressure-bonding section rows 32L is arranged in the center region 22, and a row of pressure-bonding section rows 33L is arranged in the leg-side end region 23. A plurality of fusion-bonded portions 30a are arranged in the pressure-bonding section row 31L along the longitudinal direction L, a plurality of fusion-bonded portions 30b are arranged in the pressure-bonding section row 32L along the longitudinal direction L, and a plurality of fusion-bonded portions 30c are arranged in the pressure-bonding section row 33L along the longitudinal direction L. In the present embodiment, the fusion-bonded portions 30a of the pressure-bonding section row 31L, the fusion-bonded portions 30b of the pressure-bonding section row 32L, and the fusion-bonded portions 30c of the pressure-bonding section row 33L all have the same planar shape. In other words, when the fusion-bonded portions 30a, 30b, and 30c are formed by the ultrasonic sealing method, the planar shape 31 of the distal end portion of the ultrasonic horn used for the fusion-bonded portions 30a, 30b, and 30c is the same. In the present embodiment, the planar shape 31 of the distal end portion of the ultrasonic horn is as followsShown is a circle (perfect circle), and the dimension d in the longitudinal direction L₁₁The dimension d in the width direction W₁₂(diameter of circle). As d₁₁＝d₁₂The size of (B) is not particularly limited, and may be, for example, 0.5mm to 5 mm. As the distance d between the fusion-spliced portions 30a adjacent in the longitudinal direction L₁₃(the distance between the centers of circles) is not particularly limited, and may be 1mm to 30 mm. The reason for this will be described later.

The detailed structure of the fusion-bonded part 30 will be described. Fig. 5 is a plan view and a perspective view showing an example of the structure of the fusion-bonded part 30a of the bonded part 14 a. Fig. 5 (a) is a plan view, fig. 5 (b) is a perspective view including a cross section viewed from the width direction W, and fig. 5 (c) is a perspective view including a cross section viewed from the longitudinal direction L. Here, the structure of the fusion-bonded portion 30a is explained, but in the present embodiment, the other fusion-bonded portions 30b and 30c have the same structure.

The fusion-bonded part 30a includes a thermal bonding part MC1 and a side wall part SW 1. In the thermally bonded portion MC1, the plurality of cover sheets 5a and 5b of the front side portion 11 and the plurality of cover sheets 5a and 5b of the back side portion 13 are thermally bonded to each other in the thickness direction T. In the present embodiment, the heat-adhesive portion MC1 is formed by melting the cover sheets 5a and 5b by energy supplied from the distal end portion of the ultrasonic horn and compressing the cover sheets 5a and 5b in the thickness direction T by the distal end portion. Therefore, the thermally bonded portion MC1 is strongly bonded in the thickness direction T. The dimension d in the thickness direction T of the laminate sheet is obtained by laminating a plurality of cover sheets 5a and 5b of the front and back side portions 11 and 13 only_TOIn contrast, the dimension (thickness) D of the thermal bond MC1 in the thickness direction T_T1Is significantly smaller. As d_TOThe size of (D) is, for example, 200 to 5000. mu.m_T1The size of (B) is, for example, 15 to 100. mu.m. If D is_T1When the size of (2) is less than 15mm, the thermal bonding between the cover sheets is unstable, and the perforation is likely to occur during the thermal bonding. If D is_T1If the size of (2) is larger than 100. mu.m, a portion which is not completely thermally bonded is formed, and a portion which needs to be additionally torn is formed. In addition, the method can be used for producing a composite materialThe planar shape of the thermal bonding portion MC1 is substantially the same as the planar shape 31 of the distal end portion of the ultrasonic horn. That is, the dimension D in the longitudinal direction L_L1The dimension d in the longitudinal direction L of the planar shape 31 of the tip end₁₁Substantially the same, dimension D in width direction W_W1Dimension d in the width direction W of the planar shape 31 of the tip end₁₂Are substantially identical. In the present embodiment, the planar shape of the thermal bonding portion MC1 is a circle (perfect circle) as shown in the figure, and D is the number_L1And D_W1The size of (B) is not particularly limited, and may be, for example, 0.5mm to 5 mm. At D_L1、D_W1(i.e. d)₁₁、d₁₂) If the thickness is less than 0.5mm, the absolute amount of the side wall portion is small, and therefore, the force is not applied sequentially from the end of the pattern of the thermal bond portion but applied to the entire portion at once at the time of breaking, and therefore, peeling is easily caused (by the force in the width direction W) at the time of wearing. At D_L1、D_W1If the thickness exceeds 5mm, the side wall portion may be difficult to peel off because the absolute amount is large. At this time, the distance (i.e., d) between the tip portions of the ultrasonic horn adjacent to each other₁₃) In the case of 1mm to 30mm, the distance between the adjacent thermal bonding portions MC1 is also 1mm to 30 mm. When the distance is less than 1mm, the fused joint is more than the fracture surface, and therefore, the separation may be difficult (by a force in the longitudinal direction) at the time of removal. In the case where the distance is more than 30mm, on the contrary, the existence of the fusion-bonded portion is small, and thus peeling may be easily caused at the time of wearing.

On the other hand, the plurality of cover sheets 5a and 5b of the front side portion 11 and the plurality of cover sheets 5a and 5b of the back side portion 13 are thermally bonded to each other in the thickness direction T so that the side wall portion SW1 extends cylindrically from the peripheral edge of the heat-adhesive portion MC1 in the thickness direction T. In the present embodiment, the side wall portion SW1 is formed by melting the plurality of cover sheets 5a and 5b by energy supplied from the distal end portion of the ultrasonic horn or heat of the heat-bonding portion MC1, and by causing the plurality of cover sheets 5a and 5b to be pulled by compression of the heat-bonding portion MC1 without being pressed by the distal end portion, in the thickness direction TIs slightly compressed. Therefore, the side wall portion SW1 is bonded more weakly in the thickness direction T than the thermal bonding portion MC 1. The dimension d in the thickness direction T of the laminate sheet is obtained by laminating a plurality of cover sheets 5a and 5b of the front and back side portions 11 and 13 only_TOIn contrast, the dimension (thickness) d of the side wall portion SW1 in the thickness direction T_T1Smaller but larger than the dimension D of the thermal bonding portion MC1 in the thickness direction T_T1. Thus, in the molten bond 30a, d_T0＞d_T1＞D_T1. As d_T1Examples of the size of (B) include 100 to 1000. mu.m. If d is_T1When the size of (2) is less than 100. mu.m, the thermal bonding is excessively performed, and the crack is hard to occur. If d is_T1When the size of (2) is larger than 1000. mu.m, spots are generated in the portion where the thermal adhesion is not achieved, and the base point at the time of cracking is unstable. Here, the cylindrical side wall portion SW1 has an outer surface OS constituting an outer surface of the cylinder and an inner surface IS constituting an inner surface of the cylinder. The outer surface OS and the inner surface IS are the outer surface and the inner surface of the melted portion where the peripheral edge of the self-heating adhesive portion MC1 IS raised along the thickness direction T, for example, as observed by a scanning electron microscope. The outer surface OS and the inner surface IS may not be parallel to each other or have similar shapes, may not be smooth but may be uneven, may be formed such that fibers protrude from the surface, or may not intersect the surface of the thermal bonding portion MC1 perpendicularly. Here, the cylindrical shape is an elongated and hollow shape, and is referred to as a tubular shape. The cylindrical shape may be curved or meandered as long as it extends in the thickness direction T, and the shape of the cross section perpendicular to the thickness direction T may have various shapes such as a circle, an ellipse, a polygon, or a combination of the above shapes, and the shape and the area of the cross section perpendicular to the thickness direction T may not be constant in the thickness direction T. With such a shape, when the joint portion 14a is peeled, the cylindrical side wall portion SW1 of the fusion-bonded portion 30a is broken.

In the fusion-bonded part 30a, the position of the thermal bonding part MC1 in the thickness direction T is shifted from the boundary BU between the front and back parts 11 and 13 toward the front and back parts 11 and 13 by at least Δ_BThe amount of (c). Wherein the heat is bondedThe position of the portion MC1 in the thickness direction T is the position of the center of the heat-bonded portion MC1 in the thickness direction T, and when the heat-bonded portion MC1 is uneven, the position is the position of the center of the heat-bonded portion MC1 in the thickness direction T at the joint where the heat-bonded portion MC1 and the side wall portion SW1 are joined in the longitudinal direction L. For example, in the example of fig. 5, the position of the thermal bonding portion MC1 in the thickness direction T is shifted by Δ from the boundary BU between the plurality of covering sheets 5a and 5b of the abdomen-side portion 11 and the plurality of covering sheets 5a and 5b of the back-side portion 13 toward (the end portion 11a of) the abdomen-side portion 11_BThe amount of (c). Delta_BIs at least larger than the dimension D of the thermal bonding part MC1 in the thickness direction T_T1The value of (b) 1/2 is equal to or less than the dimension in the thickness direction T of the laminate of the cover sheet 5b and the cover sheet 5 a. As a_BThe size of (B) is, for example, 10 to 500. mu.m. At this time, the plane including boundary BU does not intersect thermal bond MC 1.

Further, at the fusion-bonded portion 30a, the dimension d in the longitudinal direction L of the side wall portion SW1_L1(thickness d in the longitudinal direction of the tube)_L1LAnd d_L1R) Is smaller than the dimension d in the width direction W_W1(thickness d in the width direction of the tube)_W1LAnd d_W1R)(d_L1＜d_W1). Of these, the dimension d of the side wall portion SW1 in the longitudinal direction L_L1The width in the longitudinal direction L of the cross section (the width of one of the cross sections existing on both sides in the longitudinal direction L of the thermal bonding portion MC 1) when the side wall portion SW1 is virtually cut by a cross section perpendicular to the width direction W through the center of gravity of the planar shape of the thermal bonding portion MC 1. When the width is not constant in thickness direction T, the width is set to be the width at boundary BU. As d_L1The size of (B) is, for example, 50 to 200. mu.m. In the present embodiment, the widths of the cross sections existing on both sides in the longitudinal direction L of the thermal bonding portion MC1 are substantially equal. On the other hand, the dimension d in the width direction W of the side wall portion SW1_W1(thickness in the width direction of the tube) is a cross section obtained by virtually cutting the side wall portion SW1 with a cross section perpendicular to the longitudinal direction L through the center of gravity of the planar shape of the heat-bonded portion MC1Width in the width direction W (width of one of cross sections existing on both sides in the width direction W of the thermal bonding portion MC 1). When the width is not constant in thickness direction T, the width is set to be the width at boundary BU. As d_W1The size of (B) is, for example, 100 to 400. mu.m. In the present embodiment, the widths of the cross sections existing on both sides in the width direction W of the thermal bonding portion MC1 are substantially equal. Therefore, the cylindrical side wall portion SW1 of the fusion-bonded portion 30a is relatively easy to break due to its small width in the longitudinal direction L, that is, thin, with respect to the force from the longitudinal direction L, and is relatively difficult to break due to its large width in the width direction W, that is, thick, with respect to the force from the width direction W, of the cylindrical side wall portion SW1 of the fusion-bonded portion 30 a.

The operational effects of the joint portion 14a having the above-described configuration will be described. Fig. 6 is a schematic diagram for explaining a state where the fusion-spliced portion 30 of fig. 5 is peeled. As described above, the fusion-bonded part 30a of the bonded part 14a includes the thermal bonding part MC1 and the side wall part SW1 extending in a cylindrical shape along the thickness direction T from the peripheral edge of the thermal bonding part MC1, and the dimension d in the longitudinal direction L of the side wall part SW1 (the thickness in the longitudinal direction of the cylinder) is_L1Is smaller than the dimension (thickness of the barrel in the width direction) d in the width direction W_W1. Therefore, the portion of the side wall portion SW1 in the longitudinal direction L of the tube is easily broken, and the portion in the width direction W is not easily broken. In addition, the dimension d of the side wall portion SW1 in the thickness direction T_T1(thickness) is larger than the dimension D of the thermal bonding part MC1 in the thickness direction_T1(thickness). Thus, the plurality of sheets (cover sheets 5a, 5b) are relatively strongly joined to each other at the thermal bond portion MC1, and the plurality of sheets (cover sheets 5a, 5b) are relatively weakly joined to each other at the side wall portion SW 1. Since the position of the thermal bonding portion MC1 in the thickness direction T is offset from the boundary BU between the front and back portions 11 and 13, the thermal bonding portion MC1 is not included in the separated portion when the front and back portions 11 and 13 are separated from each other.

For the reasons described above, (the end 11a of) the ventral portion 11 and the back at the joint portion 14a are joined along the longitudinal direction T as shown in fig. 6 (a)When the side portions 13 are peeled apart from each other, (the end portions 13a of) the side portions SW1 which can be relatively weakly joined and the portion SW1 in the longitudinal direction L which is easy to break in the side wall portion SW1_LThe fracture begins. This makes it possible to easily peel the ventral portion 11 and the dorsal portion 13 apart from each other along the boundary CP1 between the ventral portion and the dorsal portion. In other words, the stomach portion 11 and the back portion 13 need not be peeled apart at the region where the strong thermal bonding portion MC1 is bonded or in the vicinity thereof. Therefore, in the disposable diaper 1, the abdomen-side portion 11 and the back-side portion 13 at the joint portion 14a can be peeled apart from each other with a relatively small force.

Specifically, the portion SW1 on one side in the longitudinal direction L of the side wall portion SW1_L1Here, the ventral portion 11 and the dorsal portion 13 can be easily separated from each other along the boundary CP1 (can start to break) with a relatively small force from the outer surface OS of the tube of the side wall portion SW1 to the inner surface IS of the tube. Further, once enabled at the portion SW1 of the side wall portion SW1_L1The ventral portion 11 and the dorsal portion 13 are separated from each other from the outer surface OS of the tube to the inner surface IS of the tube, so that the other side SW1 in the longitudinal direction L can be directly peeled off_L2The ventral-side portion 11 and the dorsal-side portion 13 are easily separated from each other along the dividing surface CP1 from the inner surface IS of the tube of the side wall portion SW1 to the outer surface OS of the tube. This makes it possible to easily peel (break) the ventral portion 11 and the dorsal portion 13 from each other at the joint portion 14 a.

On the other hand, when the disposable diaper 1 is worn by the wearer, a force applied to the joint portion 14a according to the movement of the wearer acts mainly in the width direction W. Further, in the disposable diaper 1, the dimension (thickness in the width direction of the tube) d in the width direction W of the tube of the side wall portion SW1_W1Is larger than the dimension in the length direction (thickness of the barrel in the length direction) d_L1. Therefore, when a large force in the width direction W is applied to the side wall portion SW1, the dimension d in the width direction W of the side wall portion SW1_W1Larger part SW1_WBearing the force. Therefore, even if the crack CP2 IS generated from the outer surface OS of the tube toward the inner surface IS of the side wall portion SW1, the crack CP2 IS formed toward the inner surface IS of the tube of the side wall portion SW1 before reaching the inner surface IS of the tube of the side wall portion SW1The side wall portion SW1 is in any one of a state where the upper surface US (fig. 6 b) or the lower surface DS is separated and a state where it reaches and stops at the thermal bonding portion MC1 having high bonding strength. Therefore, the situation in which the disposable diaper 1 is broken due to the abdomen-side portion 11 and the back-side portion 13 at the joint portion 14a being peeled apart from each other when worn can be suppressed.

In this way, in the disposable diaper 1, the side wall portion SW1 is formed around the thermal bond portion MC1 in the fusion-bonded portion 30a in such a manner that the side wall portion SW1 is short in the longitudinal direction L (d)_L1) That is, the portion in the longitudinal direction L is thick and the side wall portion SW1 is long in the width direction W (d)_W1) I.e., the portion in the width direction W is thin. This makes it possible to make the peeling easiness, i.e., the separation easiness, different in the longitudinal direction L and the width direction W, i.e., to make the peeling easiness (separation easiness) anisotropic. This makes it possible to achieve both ease of separation when the disposable diaper 1 is removed and difficulty of separation between the abdomen-side portion 11 and the back-side portion 13 when worn, and further improve the diaper. In the above-described embodiment, the disposable diaper 1 has the above-described structure (exemplified by the plurality of fusion-bonded portions 30a) for both of the pair of bonded portions 14a and 14 b. However, the present invention is not limited to this example, and at least one of the pair of joining portions 14a and 14b may be configured as described above. As a result, the disposable diaper 1 as a whole can be improved while achieving both ease of separation at the time of removal and difficulty of separation between the abdomen-side portion 11 and the back-side portion 13 at the time of wearing, as compared with the case where the disposable diaper does not have any of the above-described structures.

In the above-described embodiment, the disposable diaper 1 has the above-described structure (exemplified by the plurality of fusion-bonded portions 30a) for both of the pair of bonded portions 14a and 14 b. However, the present invention is not limited to this example, and at least one of the pair of joining portions 14a and 14b may be configured as described above.

For example, the absorbent article may be one in which one of the pair of joint portions (for example, the joint portion 14a) has the above-described structure and the other has the same structure as the conventional one. As a result, the disposable diaper 1 as a whole can be improved while achieving both ease of separation at the time of removal and difficulty of separation between the abdomen-side portion 11 and the back-side portion 13 at the time of wearing, as compared with the case where the disposable diaper does not have any of the above-described structures.

The absorbent article may be one in which the front side portion and the back side portion are joined to each other at both ends in the width direction to form a joining portion (for example, the joining portion 14a) having the above-described structure, and the other is not joined to form a joining (engaging) member capable of joining (or engaging) the front side portion and the back side portion to each other. Examples of the joining (engaging) member include a surface fastener. In this case as well, the disposable diaper 1 as a whole can be further improved while achieving both ease of separation at the time of removal and difficulty of separation between the abdomen-side portion 11 and the back-side portion 13 at the time of wearing, as compared with the case without any of the above-described structures.

Next, an example of a method for manufacturing the disposable diaper 1 will be described. In the example of the method for manufacturing the disposable diaper 1, the method for forming the pair of joint portions 14a and 14b is different from the conventional manufacturing method. Specifically, the following is shown.

First, a disposable diaper continuous body (not shown) in which disposable diapers in the state shown in fig. 2 are continuously connected in the width direction W is formed by a conventional manufacturing method. The disposable diaper continuum has a structure in which an end 11b of the abdomen-side portion 11 of one of the adjacent disposable diapers is connected to an end 11a of the abdomen-side portion 11 of the other one, and an end 13b of the back-side portion 13 of the one is connected to an end 13a of the back-side portion 13 of the other one. The disposable diaper continuous body is arranged and conveyed such that the width direction W of the disposable diaper is parallel to the conveyance direction MD. In this case, the longitudinal direction L of the disposable diaper is parallel to the transverse direction CD. Next, the disposable diaper continuous body is conveyed in the conveyance direction MD and folded in the longitudinal direction L along the central axis CW of the disposable diaper by the folding device. Thus, each of the disposable diapers in the disposable diaper continuum is in a state in which the end 11a of the abdomen-side portion 11 and the end 13a of the back-side portion 13 are laminated, and the end 11b of the abdomen-side portion 11 and the end 13b of the back-side portion 13 are laminated. The continuous disposable diaper in this state is supplied to the joint forming device.

Fig. 7 is a schematic diagram for explaining a method of forming a joint portion of the disposable diaper 1. The joint forming device 40 is a device that performs ultrasonic sealing, and joins the end 11a of the front side portion 11 and the end 13a of the back side portion 13 by ultrasonic sealing, and joins the end 11b of the front side portion 11 and the end 13b of the back side portion 13 by ultrasonic sealing. A specific example of such a device is a sealing device described in japanese patent application laid-open No. 2006-192902 (patent document 3). As shown in fig. 7 (a), in the joined portion forming apparatus 40, portions of the plurality of sheets at positions corresponding to the pair of joined portions 14a and 14b are sandwiched by the horn 42 and the anvil 43 of the ultrasonic wave generating member 41 disposed in the rotary cylinder, and the plurality of sheets are thermally bonded to each other by applying ultrasonic energy for a predetermined period. The horn 42 has a tip end portion having a planar shape corresponding to the planar shape of the thermally bonded portion MC 1.

In the present embodiment, the disposable diaper continuous body S is conveyed in the conveyance direction MD and the portions of the plurality of covering sheets 5a, 5b at the positions corresponding to the pair of joined portions 14a, 14b are sandwiched by the horn 42 and the anvil 43 at the position P1. That is, the plurality of covering sheets 5a and 5b at the end 11a of the abdomen-side portion 11 and the plurality of covering sheets 5a and 5b at the end 13a of the back-side portion 13 are sandwiched therebetween, and the plurality of covering sheets 5a and 5b at the end 11b of the abdomen-side portion 11 and the plurality of covering sheets 5a and 5b at the end 13b of the back-side portion 13 are sandwiched therebetween. Next, the disposable diaper continuous body S is conveyed in the conveyance direction MD, and ultrasonic energy is applied to the plurality of cover sheets 5a and 5b sandwiched therebetween. Next, the disposable diaper continuous body S is conveyed in the conveyance direction MD and continuously applied with the energy of the ultrasonic wave through the position P2 and the position P3. The plurality of covering sheets 5a, 5b are then released from the horn 42 and anvil 43 at position P4. That is, the horn 42 and the anvil 43 are disengaged from the plurality of covering pieces 5a, 5b, and returned to the position P1 again via the position P5 and the position P6. According to such an operation, the portions of the plurality of cover sheets 5a and 5b at the positions corresponding to the pair of joining portions 14a and 14b are thermally bonded to each other by the energy of the ultrasonic waves, and the fusion-bonded portion 30a of the pair of joining portions 14a and 14b is formed in each disposable diaper of the disposable diaper continuous body S. Next, the joint portions 14a and the joint portions 14b of the adjacent disposable diapers in the disposable diaper continuous body S are cut in the transverse direction CD to manufacture the disposable diaper 1. Fig. 7 (b) shows that the fused bond 30a is not formed in the portions of the plurality of covering sheets 5a, 5b of the disposable diaper continuous body S before reaching the position P1 at positions corresponding to the pair of bonds 14a, 14 b. On the other hand, fig. 7 (c) shows that the fused joint portion 30a including the thermal bond portion MC1 and the side wall portion SW1 is formed at the portion of the plurality of covering sheets 5a, 5b of the disposable diaper continuous body S corresponding to the pair of joint portions 14a, 14b when reaching the position P4.

In the above-described manufacturing method, (the horn 42 and the anvil 43 of) the ultrasonic wave generating member 41 sandwiches the plurality of covering sheets 5, applies the energy of the ultrasonic wave to the same portion of the plurality of covering sheets 5, and continues to move together with the plurality of covering sheets 5 for a predetermined time. That is, the ultrasonic wave generating member 41 continuously presses the same portion for a predetermined time and applies ultrasonic energy to the plurality of cover sheets 5 to perform thermal bonding. Therefore, not only the thermally bonded portion MC1 can be formed at the portion pressed by the horn 42 and the anvil 43 and to which the energy of the ultrasonic wave is applied, but also the side wall portion SW1 can be formed by sufficiently transmitting the energy to the portion around the thermally bonded portion MC1 and thermally bonding the same. The side wall portion SW1 formed around the thermally bonded portion MC1 can be formed by controlling the magnitude of the ultrasonic energy, the length of the predetermined time, the pressing pressure, the shape of the distal end portion of the horn 42, the properties of the plurality of cover sheets 5, and the like within appropriate ranges. However, depending on the manufacturing yield, some of the plurality of fusion-bonded parts 30a may not have the above-described structure.

In the present embodiment, as a preferred mode, each of the pair of joints 14a and 14b has a pressure-bonding section row 30L in which a plurality of fusion-bonded sections 30 are arranged at intervals along the longitudinal direction L. In this case, when the disposable diaper 1 is removed, the abdomen-side portion 11 and the back-side portion 13 can be peeled apart from each other with a relatively small force at the fusion-bonded portions 30 arranged continuously over a relatively long distance along the longitudinal direction L. This makes it easier to peel the ventral portion 11 and the dorsal portion 13 of each of the pair of joining portions 14a and 14b apart from each other. In the present embodiment, as a more preferable mode, each of the pair of joints 14a and 14b has only one row of pressure-bonded parts 30L as the plurality of fusion-bonded parts 30. Here, in the case where a plurality of rows of the pressure-bonded sections are provided in the width direction W, when the disposable diaper is removed, there is a possibility that: the force for peeling the ventral portion 11 and the dorsal portion 13 apart in the longitudinal direction L is distributed in each row, and the crack due to peeling develops in the direction inclined with respect to the longitudinal direction L and the width direction W, and the force required for peeling apart is large. Therefore, the disposable diaper 1 has only one row of the pressure-bonded part rows 30L. Therefore, when the disposable diaper 1 is removed, the force of separating the abdomen-side portion 11 and the back-side portion 13 in the longitudinal direction L can be concentrated on the row of the pressure-bonded sections 30L. This makes it possible to easily peel the ventral portion 11 and the dorsal portion 13 of each of the pair of joining portions 14a and 14b apart from each other with a small force.

In the present embodiment, as another preferred mode, the pair of joints 14a and 14b each have a waist-side end region 21, a leg-side end region 23, and a central region 22, and at least the waist-side end region 21 and the central region 22 have only one row of pressure-bonded parts 31L as the plurality of fusion-bonded parts 30. That is, the disposable diaper 1 includes a plurality of fusion-bonded parts 30a (pressure-bonded part row 31L) arranged in a row not only in the waist-side end region 21 of each of the pair of bonded parts 14a, 14b, but also in the adjacent central region 22 thereof a plurality of fusion-bonded parts 30b (pressure-bonded part row 32L) arranged in a row. Therefore, when the disposable diaper 1 is removed, the force of separating the abdomen-side portion 11 and the back-side portion 13 in the longitudinal direction L can be concentrated on the series of the plurality of fused joint portions 30a and 30b, and the above state can be achieved up to at least the central region 22 in the longitudinal direction L of each of the pair of joint portions 14a and 14 b. This makes it easier to peel the ventral portion 11 and the dorsal portion 13 of each of the pair of joint portions 14a and 14b apart from each other with a smaller force, and prevents the ventral portion 11 and the dorsal portion 13 from being cracked in the width direction W or the joint portions of the pair of joint portions 14a and 14b from being cracked in the width direction W when worn.

In the present embodiment, as another preferable mode, the shape of the side wall portion SW1 may be such that the dimension d in the longitudinal direction L is realized_L1< dimension d in width direction W_W1The planar shape of the thermal bonding portion MC1, that is, the planar shape 31 of the distal end portion of the horn 42 of the ultrasonic-wave generating member 41 is not particularly limited. Examples of the shape include a circle, a semicircle, an ellipse, a semiellipse, a polygon, or a combination of the above shapes. In the present embodiment, as another preferable aspect, the thermal bonding section MC1 has a maximum dimension D in the longitudinal direction L of the thermal bonding section MC1 in the planar shape of the thermal bonding section MC1_L1Is the maximum dimension D in the width direction W_W1The above. In other words, the maximum dimension (d) in the transverse direction CD of the distal end portion of the planar shape 31 of the distal end portion of the horn 42 is₁₁) Is the largest dimension (d) in the conveying direction MD₁₂) The above. Such a shape includes, for example, D_L1＝D_W1Or its semicircle, square, or D_L1＞D_W1An ellipse or a semi-ellipse thereof, a rectangle, or a combination thereof, which is long in the longitudinal direction L. In addition, the maximum dimension D in the longitudinal direction L_L1The maximum distance between two straight lines parallel to the width direction W and tangent to the outer edge of the thermal bonding portion MC1 is the maximum distance between the two straight lines when the thermal bonding portion MC1 is sandwiched in the longitudinal direction L. On the other hand, the maximum dimension D of W in the width direction_W1The maximum distance between two straight lines parallel to the longitudinal direction L and tangent to the outer edge of the thermal bonding portion MC1 is the maximum distance between the two straight lines when the thermal bonding portion MC1 is sandwiched in the width direction W. In such a disposable diaper 1, the thickness of the tube formed by the side wall portion SW1 can be made thinner in the longitudinal direction L and thicker in the width direction W. Therefore, when the disposable diaper 1 is removed, the abdomen-side portion 11 and the back-side portion 13 can be more easily separated from each other from the thin portion on the longitudinal direction L side. And areFurther, even if a large force is applied in the width direction W during wearing, the force is received by the thick portion on the width direction W side, and therefore, the state in which the abdomen-side portion 11 and the back-side portion 13 at the joint portion 14a are separated and the disposable diaper 1 is broken can be suppressed. Among them, the planar shape of the heat-bonding portion MC1, that is, the planar shape 31 of the distal end portion of the horn 42 of the ultrasonic-wave generating member 41 is preferably a circle. This allows the thickness of the tube formed by the side wall portion SW1 to be appropriately thin in the longitudinal direction L and thick in the width direction W.

In the present embodiment, D as the thermal bonding portion MC1_L1、D_W1Size of (2), i.e. d of the tip₁₁、d₁₂The size of (2) (exemplified as the diameter in the case of a circle) is not particularly limited, but is preferably 0.5mm to 5 mm. If the thickness is less than 0.5mm, the bonding strength of the fusion bonded portion 30 is too low, and the bonded portion 14a may peel off when worn. If the thickness is larger than 5mm, the bonding strength of the fusion-bonded part 30 becomes too high, and the bonded part 14a may be difficult to peel off when detached. The distance between the thermal bonding portions MC1 adjacent to each other in the longitudinal direction L, i.e., d at the tip end₁₃The size of (2) (exemplified as the distance between centers in the case of a circle) is not particularly limited, but is preferably 1mm to 10 mm. If the thickness is less than 1mm, the number of fusion-bonded parts 30 is too large, and the bonded part 14a may be difficult to peel off when detached. If the thickness exceeds 30mm, the number of fusion-bonded parts 30 is too small, and the bonded part 14a may peel off during wearing.

Further, the dimension d in the longitudinal direction L as the side wall portion SW1_L1The size of (B) is not particularly limited, but is preferably 50 to 200. mu.m. If the thickness is less than 50 μm, the joint portions 14a and 14b may be broken from the longitudinal direction L when worn (by a force in the width direction). If the thickness is larger than 200 μm, the joints 14a and 14b may be difficult to peel off during removal. d_L1More preferably 70 to 160 μm, and still more preferably 80 to 130 μm. On the other hand, the dimension d in the width direction W of the side wall portion SW1_W1The size of (A) is not particularly limited,preferably 100 to 400 μm. If the thickness is less than 100 μm, the joint portions 14a and 14b may be broken in the width direction W when worn. If the thickness is larger than 400 μm, the joints 14a and 14b may be difficult to peel off (by a force along the longitudinal direction) during removal. d_L1More preferably 110 to 200. mu.m, still more preferably 120 to 180 μm. The dimension d in the longitudinal direction L of the side wall portion SW1_L1And a dimension d in the width direction W_W1The peeling can be performed by applying a force in the longitudinal direction L, and the peeling or the breakage can be suppressed even when a large force is applied in the width direction W during wearing.

In another preferred aspect of the present embodiment, the dimension d of the side wall portion SW1 in the longitudinal direction L is_L1And the dimension d of the side wall portion SW1 in the width direction W_W1Ratio of (d)_L1/d_W1) Preferably 0.2 to 0.8. The dimension d in the longitudinal direction L of the side wall portion SW1 satisfying this ratio_L1And a dimension d in the width direction W_W1The peeling can be performed by applying a force in the longitudinal direction L, and the peeling or the breakage can be suppressed even if a large force is applied in the width direction W. When the ratio is less than 0.2 and when the ratio is more than 0.8, the joints 14a and 14b may be broken in the longitudinal direction L when worn or the joints 14a and 14b may not be peeled in the width direction W when detached. d_L1/d_W1More preferably 0.5 to 0.8. When the planar shape of the heat-bonding portion MC1, that is, the planar shape 31 of the distal end portion of the horn 42 of the ultrasonic-wave generating member 41 is made circular, d can be easily set_L1/d_W1In the preferred range, therefore, preferred.

In the present embodiment, the bonding strength when one fusion-bonded portion 30a is peeled off from the longitudinal direction L is preferably 0.5N to 5N. When the number of the peeling-off tool is less than 0.5N, peeling may be caused by a force in the width direction W during wearing, and when the number of the peeling-off tool is more than 5N, peeling may not be performed by a force in the longitudinal direction L during removal. On the other hand, the bonding strength when one fusion-bonded portion 30a is peeled from the width direction W is preferably 1.0N to 10N. When the number of the peeling-off tool is less than 1.0N, peeling may be caused by a force in the width direction W during wearing, and when the number of the peeling-off tool is more than 10N, peeling may not be performed by a force in the longitudinal direction L during removal.

In the present embodiment, as another preferable mode, the dimension d in the width direction of the side wall portion SW1 of one joint portion 14a of the pair of joint portions 14a, 14b_W1(FIG. 5 (a): d)_W1L、d_W1R) And the width direction W dimension d of the side wall portion SW1 of the other engaging portion 14b_W1(d_W1L、d_W1R) The difference is within 40 μm. That is, in one engaging portion (e.g., the engaging portion 14a) and the other engaging portion (e.g., the engaging portion 14b) in the width direction W, the dimension d in the width direction W of the side wall portion SW1 is set_W1The dimension (thickness in the width direction of the cylinder) is set to be substantially the same. Therefore, when the wearer intends to remove the disposable diaper 1, both the left and right joint portions 14a and 14b can be peeled off with substantially the same force. This allows the wearer to more easily peel the left and right joint portions 14a and 14b apart. In particular, in the case of the above-described manufacturing method, since the plurality of cover sheets 5 are stably held and thermally bonded for a predetermined period of time by the horn 42 and the anvil 43, the side wall portion SW1 having a high symmetry of shape can be stably formed.

In the present embodiment, as another preferable mode, the inner dimensions in the width direction W of the side wall portions SW1 of the pair of joining portions 14a and 14b (for example, FIG. 5 (a): d)_W1L) The dimension of the outer side (example: fig. 5 (a): d_W1R) The difference is within 40 μm. That is, the inner dimension in the width direction W (exemplified by the thickness of the cylinder, i.e., d)_W1L) The dimension of the outer side (example: thickness of the cylinder, i.e. d_W1R) Are set to substantially the same size. Therefore, in the one side wall portion SW1, the force required to peel off the inner portion in the width direction W is substantially the same as the force required to peel off the outer portion. Therefore, when the wearer intends to remove the disposable diaper 1, the direction of the force for separating the abdomen-side portion 11 and the back-side portion 13 can be prevented from becoming the direction inclined with respect to the longitudinal direction L and the width direction W, and the direction of the abdomen-side portion 11 and the back-side portion 13 in the longitudinal direction can be prevented from becoming the direction inclined with respect to the longitudinal direction L and the width direction WL is inclined and the width direction W is broken.

In the present embodiment, the thermal bonding portion MC1 is preferably located closer to the stomach portion 11 than to the back portion 13 in the thickness direction T in the side wall portion SW 1. Thus, when the wearer bends over to peel the abdomen-side portion 11 and the back-side portion 13 of the disposable diaper 1, the thermal adhesive portion MC1 is easily visible, and therefore the wearer can more reliably grasp the vicinity of the fused and bonded portion 30a with the fingers and perform the peeling operation. This makes it easier to peel the ventral portion 11 and the dorsal portion 13 apart from each other at the joint portion 14 a.

In the present embodiment, as another preferred mode, in each of the pair of joining portions 14a, 14b, the end edge 11ae in the longitudinal direction L of the end portion 11a or the end edge 11be in the longitudinal direction L of the end portion 11b of the stomach side portion 11 and the end edge 13ae in the longitudinal direction L of the end portion 13a or the end edge 13be in the longitudinal direction L of the end portion 13b of the back side portion 13 are shifted from each other by Δ in the longitudinal direction L_C(preferably. + -. 0.5mm to 10 mm). Therefore, when the wearer intends to remove the disposable diaper 1, the wearer can more easily grip the end portion 11a or 11b of the abdomen-side portion 11 with one finger and the end portion 13a or 13b of the back-side portion 13 with the other finger. This makes it easier to peel the ventral portion 11 and the dorsal portion 13 apart from each other at the joint portions 14a and 14 b. If Δ_CIs less than 0.5mm, it is difficult to grasp the end portions 11a, 11b with fingers, and if Δ is less than_CIf the absolute value of (a) is larger than 10mm, the end portions 11a and 11b may be caught by other objects and damaged.

(embodiment 2)

In embodiment 1, the plurality of fusion-bonded portions 30a, 30b, and 30c are arranged in a row at intervals along the longitudinal direction L in each of the pair of bonded portions 14a and 14 b. That is, the entire region of the pressure-bonding section row 30L in the longitudinal direction L is one row. The fusion-bonded portions 30a, 30b, and 30c have the same shape. However, in the present embodiment, in the pressure bonding section row 30L, the pressure bonding section row 32L of the center region 22 and the pressure bonding section row 33L of the leg-side end region 23 are different from the pressure bonding section row 31L of the waist-side end region 21. Hereinafter, the different points will be mainly described in detail.

Fig. 8 is a schematic diagram for explaining another configuration example of the joint part of fig. 3. Fig. 8 is a schematic view of the joint portion 14a as viewed from the back side portion 13 side in the thickness direction T, and shows an example of the arrangement of the fusion-bonded portion 30. In the present embodiment, as the pressure-bonding section row 30L, a row of pressure-bonding section rows 31L is arranged along the longitudinal direction L in the waist-side end region 21, a row of pressure-bonding section rows 32L is arranged along the longitudinal direction L in the center region 22, and two rows of pressure-bonding section rows 33L are arranged along the longitudinal direction L in the width direction W in the leg-side end region 23. In the present embodiment, the fusion-bonded portions 30a of the pressure-bonding section row 31L, the fusion-bonded portions 30b of the pressure-bonding section row 32L, and the fusion-bonded portions 30c of the pressure-bonding section row 33L have different planar shapes from each other. In other words, when the fusion-bonded portions 30a, 30b, and 30c are formed by the ultrasonic sealing method, the planar shape 31 of the distal end portion of the ultrasonic horn for the fusion-bonded portion 30a, the planar shape 32 of the distal end portion of the ultrasonic horn for the fusion-bonded portion 30b, and the planar shape 33 of the distal end portion of the ultrasonic horn for the fusion-bonded portion 30c are different from each other.

The planar shape 32 of the distal end portion of the ultrasonic horn forming the fusion-bonded portion 30b of the pressure-bonded part row 32L is an ellipse which is long in the width direction W and has a dimension d in the longitudinal direction L₂₁< dimension d in width direction W₂₂. As d₂₁And d₂₂The thickness is not particularly limited, and may be, for example, 0.5mm to 5 mm. As the distance d between the fusion-spliced portions 30b adjacent in the longitudinal direction L₂₃(the distance between the major axes of the ellipses) is not particularly limited, and may be 1mm to 30 mm.

At d₂₂If the thickness is less than 0.5mm, the fusion-bonded portion formed is not sequentially applied from the end of the pattern of the thermal-bonded portion but is applied to the entire portion at once at the time of breaking, so that the peel-off is easily caused at the time of wearing (by a force along the width direction W), and the above problem also depends on d₂₁Length of (d). At d₂₂When the thickness is more than 5mm, the molten bond portion is formed so as to be peeled offSince a force is applied to a surface of the side wall portion having a large thickness in the longitudinal direction L, the side wall portion may be difficult to peel off when detached. At d₂₁If the thickness is less than 0.5mm, the absolute amount of the side wall portion of the pattern of one thermally-bonded portion is small relative to the fracture cross section of the fusion-bonded portion to be formed, and therefore peeling is likely to occur when the garment is worn, and the above problem also depends on d₂₂Length of (d). At d₂₁If the thickness is more than 5mm, the molten bond portion formed may have a large number of side wall portions with respect to the fracture cross section, and therefore may be difficult to peel off (by a force along the longitudinal direction L) at the time of detachment. Furthermore, at a distance d₂₃If the thickness is less than 1mm, the molten bond portion formed is present in a large amount relative to the fracture cross section, and therefore, the molten bond portion may be difficult to peel (by a force along the longitudinal direction) at the time of detachment, and may be separated by the distance d₂₃If the thickness is more than 30mm, on the contrary, the number of fusion-bonded portions formed is small, and peeling may easily occur when the garment is worn.

The planar shape 33 of the distal end portion of the ultrasonic horn for forming the fusion-bonded portion 30c of the pressure-bonded part row 33L is a semicircle having a chord in the width direction W and is a shape (semicircle + rectangle) obtained by slightly stretching the chord portion of the semicircle in the width direction W, and two of them are arranged close to each other in the width direction W. As a dimension d in the longitudinal direction L₃₁Dimension d in width direction W₃₂And a dimension d between both ends of the tip end portions arranged in the width direction W₃₄The thickness is not particularly limited, and may be, for example, 0.5mm to 5 mm. As the distance d between the fusion-spliced portions 30c adjacent in the longitudinal direction L₃₃The distance between the centers of the (semi-) circles is not particularly limited, but may be 1mm to 30 mm. A dimension d between outer side ends of two fusion-bonded parts 30c adjacent in the width direction W₃₄Which is d₃₂X 2+ alpha, where alpha is less than d₃₂(＞0)。

Fig. 9 is a plan view showing an example of the structure of the fusion-bonded part 30 at the bonded part 14 a. Fig. 9 (a) shows a fusion-bonded portion 30b, and fig. 9 (c) shows a fusion-bonded portion 30 c. The fusion bonded portion 30b includes a thermal bonding portion MC2 and a side wall portion SW2, and the fusion bonded portion 30c includes a thermal bonding portion MC3 and a side wall portion SW 3.

In the fusion-bonded part 30c, the planar shape of the thermal bonding part MC3 is a shape (semi-circle + rectangle) having a semi-circle with a chord in the width direction W and obtained by slightly stretching a chord part of the semi-circle in the width direction W, and two parts are arranged close to each other in the width direction W. Side wall part SW3_I、SW3_ODimension d in the longitudinal direction L of_L3Is smaller than the dimension d in the width direction W_W3a、d_w3b. The planar shape can be regarded as a shape obtained by dividing the circle of the thermal bonding portion MC1 into half and arranging the half in the same direction. In this case, the molten bond 30c can receive a force in the width direction W at the time of wearing to prevent peeling, and can be easily peeled off by a force in the longitudinal direction L at the time of removing, similarly to the molten bond 30a of the pressure-bonded section row 31L. In this case, d_L3And d_L1Likewise, it is preferably 50 μm to 200 μm, d_W3a、d_w3bAnd d_W1Also preferably 100 to 400 μm.

In addition, side wall portion SW3 is seen from the top_IAt this time, the linear chord portion of the molten bond 30c faces inward in the width direction W. Therefore, even if a force is applied from the inside in the width direction W when worn, the force is received by the large flat surface of the chord portion, and therefore the side wall portion SW3 is compared with the side wall portion SW1_IBreakage does not occur easily. Two such side wall portions SW3 are arranged in the molten bond portion 30c along the width direction W. Therefore, the fusion-bonded portion 30c can increase the difficulty of separation (difficulty of fracture) in the width direction W as compared with the fusion-bonded portion 30a of one circle. That is, the resistance against the force from the inside in the width direction W when worn can be improved.

Further, since the fusion-bonded portions 30c of the pressure-bonded part row 33L are formed in two rows, there is a possibility that the force of separating the abdomen-side part 11 and the back-side part 13 in the longitudinal direction L may be dispersed in the disposable diaper 1 when the disposable diaper is removedEach column. Therefore, by bringing two fusion-bonded portions 30c adjacent to each other in the width direction W closer to each other in the width direction W, the dimension d between the outer end portions is set to be smaller₃₄Is set to d₃₂×2+α(0＜α＜d₃₂) This makes it possible to easily peel off the ventral portion 11 and the dorsal portion 13 substantially in a single line at the time of removal. However, in the case of peeling from the waist opening WO side, the fused joint portion 30c of the leg-side end region 23 can be peeled off relatively easily by the force of the peeling, and therefore, in this case, the dimension d between the outer ends may not necessarily be the same₃₄Is set to d₃₂×2+α。

In the fusion-bonded part 30b, the planar shape of the heat-bonded part MC2 is an elliptical shape elongated in the width direction W, that is, the dimension D in the longitudinal direction L of the heat-bonded part MC2_L2Smaller than the dimension D in the width direction W_W2. In this case, the dimension d of the side wall portion SW2 in the longitudinal direction L_L2Can be larger than the dimension d in the width direction W_W2In the present embodiment, the dimension d in the longitudinal direction L is further set_L2Is larger than the dimension d of the side wall parts SW1, SW3 in the length direction L_L1、d_L3(d_L2＞d_L1、d_L3) And is smaller than the dimension d of the side wall parts SW1, SW3 in the width direction W_W1、d_W3a、d_w3b(d_W1、d_W3a、d_w3b＞d_L2). However, d_L2Or may be with d_w3bTo the same extent or less than d_w3b. In this case, d_L2Preferably 70 to 250 μm.

In this case, the ease of peeling in the longitudinal direction L of the molten bond 30b is lower than that of the molten bonds 30a and 30 c. Therefore, it is also considered that the fusion-bonded parts 30a and 30c may be less likely to be peeled off by a force in the longitudinal direction L at the time of removal. However, in terms of the function of facilitating the peeling at the time of starting the peeling (starting the breaking) at the time of the detachment, the fusion-bonded portion 30a of the waist-side end region 21 (in the case of peeling from the waist opening WO side) or the fusion-bonded portion 30c of the leg-side end region 23 (in the case of peeling from the leg opening LO side) is sufficientThe effect is achieved. Therefore, when the peeling is started (the breakage is started), the fusion-bonded part 30b of the central region 22 can be peeled off relatively easily by the force of the peeling. Therefore, as long as at least one of the fusion-bonded portions 30a of the waist-side end region 21 and the fusion-bonded portions 30c of the leg-side end region 23 performs this function, it is not always necessary for each fusion-bonded portion 30b to perform its function. However, when the fusion-bonded part 30a or the fusion-bonded part 30c is accidentally peeled off during wearing, the fusion-bonded part 30b can stop the peeling off in the middle (the central region 22). This prevents the disposable diaper 1 from being unusable due to the breakage of the joint portions 14a and 14 b. In this respect, let d_L2＞d_L1、d_L3D is set so as not to excessively increase the force for separating the abdomen-side part 11 and the back-side part 13 in the longitudinal direction L when the disposable diaper 1 is removed_W1、d_W3a、d_w3b＞d_L2。

On the other hand, the dimension d in the width direction W of the side wall portion SW2_W2Less than the dimension d in the length direction L_L2And thus is smaller than the dimension d in the width direction W of the side wall portions SW1, SW3_W1、d_W3a、d_w3b. Therefore, the difficulty of peeling of each fusion-bonded part 30b with respect to the force from the width direction W at the time of wearing is reduced as compared with the fusion-bonded parts 30a and 30 c. Therefore, it is also considered that the peeling-off may be easily caused by a force in the width direction W when the wearer wears the garment. However, since the central region 22 is set to be longer in the longitudinal direction L, more of the fusion-bonded portions 30b can disperse and receive the force in the width direction W at the time of wearing, and thus there is no problem in difficulty in peeling at the time of wearing. Further, since the fused joint portion 30a of the waist-side end region 21 and the fused joint portion 30c of the leg-side end region 23 are strong against the force in the width direction W, the joint portions 14a and 14b can be dispersed as a whole and receive the force, which is not problematic. In this case, d_W2Preferably 60 to 200. mu.m.

Further, as described above, all of the fusion-bonded portions of the bonded portion 14a do not necessarily have the structures of the fusion-bonded portion 30a and the fusion-bonded portion 30c described above. The portion of the end portion side where peeling starts (where cracking starts) in the longitudinal direction L of the joint portion 14a, that is, the portion in the range of 20% or more from the end edge, may have the above-described structure, and is preferably 40% or more, and more preferably 60% or more.

In the present embodiment, the shapes of the thermal bonding portions of the pressure- bonding section rows 31L, 32L, and 33L, that is, the shapes of the distal end portions of the ultrasonic horns are the same in the rows. However, the present embodiment is not limited to this example, and the shape of the heat-bonding portion in each pressure-bonding section row, that is, the shape of the distal end portion of the ultrasonic horn may be partially or entirely different. The plurality of fusion-bonded parts in each of the pressure- bonding part rows 31L, 32L, and 33L may be all in one row in the longitudinal direction L, or may be a part or all in two rows or three or more rows. In the case where the rows of pressure-bonding sections are arranged in plural rows, it is preferable in terms of ease of separation that the rows are close to each other in the width direction W, for example, that the end portions of the side wall portions facing each other of the adjacent fusion-bonded sections are close to each other to a distance equal to or less than the dimension in the width direction W of the fusion-bonded sections.

This embodiment can also exhibit the operational effects of embodiment 1 in addition to the operational effects described above.