JP6342680B2 - Pants-type disposable diaper - Google Patents

Description

  The present invention relates to a pants-type disposable diaper having a side seal portion.

  Conventionally, as a pants-type disposable diaper, an absorbent main body and an exterior body arranged on the non-skin-facing surface side of the absorbent body and fixing the absorbent body are provided, and the exterior body of the front body One in which a pair of side seal portions, a waist opening portion, and a pair of leg openings are formed by joining the left and right side edges and the left and right side edges of the exterior body in the back body is widely used.

  For example, in Patent Documents 1 to 3, in the pants-type disposable diaper having such a configuration, the seal strength (bonding strength) of the side seal portion is partially varied from the viewpoint of good fit that does not select the wearer's body shape. It is described. In these documents, the seal strength of the side seal part is partially varied by partially varying the pattern of the seal part formed by heat seal processing or the like. These documents do not describe the relationship between the sheet-like member constituting the side seal portion and the seal strength.

  A pants-type disposable diaper is usually manufactured through the following steps. That is, a diaper continuous body in which a plurality of diapers are continuous in one direction (conveying direction), and the front body side and the back body side of the exterior body that overlap each other at the side seal portion formation planned site in the diaper continuous body, Are joined to each other by a joining means such as a heat roll device, and then the joined portion is cut by a cutting means such as a cutter, thereby being divided into individual diapers. Side seal portions of the conventional pants-type disposable diaper manufactured by such a so-called heat seal method (the cut edges of the joint portion produced by cutting by the cutting means) are the left and right sides of the front body when the diaper is worn. It protrudes from the outer surface of the diaper in a shape in which the edge and the left and right side edges of the back body overlap in a palm-like shape.

JP 2006-6780 A JP 2009-34209 A Japanese Utility Model Publication No. 9-287

  In recent years, pants-type disposable diapers have been desired to have the same appearance as normal underwear. However, the pants-type disposable diaper has a side seal portion that does not exist in normal underwear. However, the conventional side seal portion protrudes outward from the diaper rather than the peripheral portion, and is very conspicuous in the appearance of the diaper. Because of its existence, underpants-type disposable diapers are difficult to say with the same appearance as underwear. Further, the side seal portion formed by heat sealing processing or the like as described in Patent Documents 1 and 2 is hard and difficult to say because it is formed by heating and compressing the exterior body. This is a cause of lowering the wearing feeling of diapers. Such a decrease in wearing feeling due to the side seal portion is not in normal underwear.

  A conventional side seal portion formed according to a conventional method using heat sealing processing, ultrasonic processing, or the like as described in Patent Documents 1 and 2 as a method for imparting an appearance similar to normal underwear to a pants-type disposable diaper A method of lowering the protruding height of the side seal part from the outer surface of the diaper by physically cutting the tip part of the side seal part by a cutting means such as a cutter is conceivable. However, the side seal part formed according to the ordinary method is formed by compressing the exterior body in the thickness direction, so the thickness (width) of the fused part of the forming material in the side seal part is compared. However, when the fused portion having a small thickness is physically cut, the cut end becomes a pointed protrusion-shaped resin toward the outside of the diaper, and the protrusion-shaped resin is touched by hand. There is a risk of tingling in your hand and feeling pain. In the present specification, the sensation of “chickle” means a sensation (pain) that is usually felt when a protrusion is touched with a finger. For example, the tip of an object that is smaller than a fingertip or has a tip is used. It is a sensation (pain) when touched with a fingertip. In the side seal part of the pants-type disposable diaper, the “projections” that can cause such a tingling sensation include, for example, a resin that has been hardened and cured by melting, a resin that has been compressed simultaneously with heat melting, and has become a projection. And a resin having a comparatively sharp shape by cutting the resin sharply.

  In addition, the side seal part (fused part) is easily broken when the diaper is discarded, on the premise that the side seal part will not be broken when the diaper is worn. The operability is required to be excellent. A pants-type disposable diaper having an appearance like an underwear and having an excellent feeling of wearing has not been provided yet, while having a side seal portion having a practically sufficient seal strength and excellent operability.

  Therefore, the present invention relates to a pants-type disposable diaper having an appearance like an underwear and having an excellent feeling of wearing while having a side seal portion having practically sufficient sealing strength and excellent operability.

  The present invention comprises an absorbent main body and an exterior body that is disposed on the non-skin-facing surface side of the absorbent main body and fixes the absorbent main body, and both side edges of the exterior body on the ventral side A pants-type disposable diaper in which a pair of side seal parts, a waist opening part, and a pair of leg opening parts are formed by joining both side edges of the exterior body at the back side part, and the thickness of the side seal part Is larger than the thickness of the portions other than the side seal portions of the ventral side portion and the dorsal side portion constituting this, and the ventral side portion and the dorsal side portion constituting the side seal portion are: Each of the plurality of sheet-like members includes a laminated structure, and among the plurality of sheet-like members, the melting point of the constituent fibers of at least one sheet-like member is the melting point of the constituent fibers of the other sheet-like members. Unlike the ventral side and the Each of the laminated structures of the side portions includes a low-melting-point innermost layer-type laminated structure in which an innermost layer is a low-melting-point sheet-like member having the lowest melting point among the plurality of sheet-like members, The diaper continuum obtained by superimposing the front body continuum including the abdomen and the back body continuum including the back side is formed by irradiating a laser beam and fusing it. A pants-type disposable diaper.

  ADVANTAGE OF THE INVENTION According to this invention, while providing the side seal part which has practically sufficient seal strength and is excellent in operativity, the underpants type disposable diaper which has the appearance like underwear and is excellent in a feeling of wear is provided.

FIG. 1 is a perspective view schematically showing one embodiment of a pants-type disposable diaper of the present invention. FIG. 2 is a plan view schematically showing an unfolded and extended state of the diaper shown in FIG. FIG. 3 is a cross-sectional view schematically showing a cross section taken along line II of FIG. 4 is a cross-sectional view schematically showing a cross section taken along line II-II in FIG. FIG. 5 is a partially broken perspective view schematically showing an elastic sheet used as an outer package of the diaper shown in FIG. FIG. 6 is a perspective view schematically showing an apparatus suitably used for manufacturing the stretchable sheet shown in FIG.

  Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. The diaper 1 which is one embodiment of the underpants type disposable diaper of this invention is distribute | arranged to the non-skin opposing surface side of this absorptive main body 2 and this absorptive main body 2, and this absorption as shown in FIGS. An exterior body 3 to which the main body 2 is fixed, and along the longitudinal direction X of the exterior body 3 at the side edges 3F, 3F and the back side R along the longitudinal direction X of the exterior body 3 at the ventral side F. A pants-type disposable diaper in which the side edges 3R, 3R are joined to form a pair of side seals 4, 4, a waist opening 5, and a pair of leg openings 6, 6. In FIG. 4, from the viewpoint of ease of explanation, there are places where adjacent constituent members in the side seal portion 4 are described without being in close contact with each other, but in fact, adjacent constituent members in the side seal portion. The two are in close contact.

  The diaper 1 has a longitudinal direction X corresponding to the wearer's front-rear direction and a lateral direction Y orthogonal to the wearer's front-rear direction in a plan view in an unfolded and extended state as shown in FIG. The diaper 1 can be divided into a crotch part M disposed in the crotch part when worn, and a ventral side part F and a back side part R located in the longitudinal direction X. The vertical direction X is a direction extending from the ventral side F to the back side R via the crotch M. The crotch part M is an area in which recessed portions for forming the leg openings 6 and 6 are formed at both side edges along the vertical direction X.

  In addition, in this specification, a skin opposing surface is a surface turned to a wearer's skin side at the time of wear of a disposable diaper in a disposable diaper or its component (for example, absorptive main part 2), and a non-skin opposing surface is It is a surface in the disposable diaper or a component thereof directed to the side opposite to the skin side (clothing side) when the disposable diaper is worn. Moreover, the vertical direction X corresponds to the direction (longitudinal direction) along the long side of the absorbent main body 2 which is a disposable diaper or its constituent member, and the horizontal direction Y is the absorbent main body 2 which is a disposable diaper or its constituent member. Matches the width direction of.

  As shown in FIG. 2, the absorbent main body 2 has a vertically long shape in which one direction (vertical direction X) is relatively long, and includes a topsheet 21 that forms a skin facing surface and a non-skin facing surface. A back sheet 22 to be formed and a liquid-retaining absorbent 23 interposed between the two sheets 21 and 22 are provided. The absorbent 23 has a shape that is long in the same direction as the longitudinal direction X. . The absorbent main body 2 has its longitudinal direction aligned with the longitudinal direction X of the diaper 1 in the unfolded and extended state (the state shown in FIG. 2), and a known joining means (such as an adhesive) at the center of the outer package 3. It is joined by.

  As the top sheet 21, the back sheet 22, and the absorber 23 that constitute the absorbent main body 2, various types that are conventionally used in the technical field can be used without particular limitation. As the surface sheet 21, for example, a liquid permeable sheet such as various nonwoven fabrics or perforated films subjected to a hydrophilic treatment can be used. Moreover, as the back sheet 22, a liquid-impermeable material or a water-repellent material can be used. As the liquid-impermeable material, a resin film, a resin film having fine pores and moisture permeability, a laminate material of a resin film and a nonwoven fabric, and the like can be used. A composite nonwoven fabric having a multilayer structure composed of bond, meltblown, spunbond, or the like, a spunbond nonwoven fabric, a heat bond nonwoven fabric, an air-through nonwoven fabric, or the like can be used. As the absorbent body 23, an absorbent core comprising an absorbent core made of water-absorbing polymer particles and a fiber material such as pulp fiber can be used. The absorbent core is a core wrap sheet such as tissue paper. It may be covered.

  As shown in FIG. 2, side cuffs 24 and 24 made of a sheet material that is liquid-resistant or water-repellent and breathable are provided on both the left and right sides of the absorbent main body 2 along the longitudinal direction X. . Each side cuff 24 stands up when the side cuff elastic member 25 arranged in an extended state along the free end contracts, and prevents the liquid from flowing out in the lateral direction Y. Here, the expanded and extended state means that the side seal portion is peeled off, the diaper is set in the expanded state, the elastic member of each part is expanded in the expanded diaper, and the design dimensions (the influence of the elastic member is eliminated at all). In this state, it is expanded until it becomes the same size as when expanded in a flat shape.

  The exterior body 3 includes a laminated body of the first exterior sheet 30 and the second exterior sheet 36. The sheet 30 forms the outer surface of the diaper 1 (the non-skin facing surface of the exterior body 3), and the sheet 36 forms the inner surface of the diaper 1 (the skin facing surface of the exterior body 3). The sheets 30 and 36 are bonded to each other by a known bonding means such as an adhesive, a heat seal, an ultrasonic seal, or the like on the opposing surfaces. As shown in FIGS. 2 and 4, the front and rear end portions of the sheet 30 in the vertical direction X (extending portions from the front and rear end portions in the vertical direction X of the sheet 36) are respectively folded back to the skin facing surface side. A plurality of thread-like waist elastic members 51 are bonded and fixed together with an adhesive in an expanded state between the two sheets 30 and 30 facing each other by the folding. As a result, a waist gather is formed at the opening end of the waist opening 5.

  As shown in FIGS. 2 to 4, the first exterior sheet 30 includes two sheets, an outer layer sheet 31 and an inner layer sheet 32, and a plurality of thread-like elastic filaments 33 sandwiched between the sheets 31 and 32. The elastic sheet is extendable in the same direction as the direction in which the elastic filament 33 extends (lateral direction Y). In the exterior body 3, the first exterior sheet 30 and the second exterior sheet 36 are joined to each other on opposite surfaces under the stretched state of the sheet 30, so that the exterior body 3 as a whole is at least in the sheet 30. The elastic filament 33 has elasticity in the extending direction. The outer layer sheet 31 forms the outer surface of the diaper 1 (the non-skin facing surface of the outer package 3), and the inner layer sheet 32 forms a bonding surface with the second outer sheet 36. Details of the first exterior sheet 30 will be described later. By using the stretchable sheet as a sheet constituting the exterior body, the appearance of the diaper becomes more like an underwear, and the wearing feeling of the diaper and the softness of the side seal part are improved.

  In this embodiment, as shown in FIGS. 2 and 4, a body cover sheet 37 that crosses the absorbent body 2 in the lateral direction Y is disposed on the skin facing surface of the exterior body 3 (second exterior sheet 36). ing. The sheet 37 has an adhesive, a heat seal, and other components of the diaper 1 opposite to the sheet 37 (absorbent body 2 (surface sheet 21), side cuff 24, exterior body 3 (second exterior sheet 36)). It is joined partially or entirely by a known joining means such as an ultrasonic seal. The sheet 37 is arranged so as to cross the front and rear end portions in the longitudinal direction X of the absorbent main body 2 in the lateral direction Y, and one sheet 37 is arranged on each of the ventral side portion F and the back side portion R. Each sheet 37 has a rectangular shape that is long in the lateral direction Y in a plan view as shown in FIG. 2, and is continuous over the entire length of the exterior body 3 in the lateral direction Y. Each sheet 37 is arranged in the vicinity of the opening end of the waist opening 5 (the folded portion of the first exterior sheet 30 and the arrangement site of the waist elastic member 51), and is longer than the longitudinal end of the absorbent main body 2. Extending in the transverse direction Y through the outside in the direction X, and extending in the transverse direction Y through the inside in the longitudinal direction X (on the absorbent main body 2) than the longitudinal end portion, A longitudinally inward portion.

  The side seal portion 4 includes a plurality of sheets constituting the exterior body 3 [first exterior sheet 30 (outer layer sheet 31, inner layer sheet 32), second exterior sheet 36] and other sheets superimposed on the exterior body 3 ( The main body cover sheet 37) is formed by fusing with overlapping edges, and has a fusing part. The thickness (width) 4W (see FIG. 3) of the side seal portion 4 (the fused portion of the side seal portion 4) is less noticeable from the viewpoint of giving the diaper 1 an appearance like underwear. The smaller one is desirable, but if it is too small, the sealing strength is lowered and the side seal portion 4 may be broken while the diaper 1 is worn. From this point of view, the thickness 4W of the side seal portion 4 is preferably 0.2 mm or more, more preferably 0.25 mm or more, and preferably 2 mm or less, more preferably 1.5 mm or less, more specifically, Preferably it is 0.2-2 mm, More preferably, it is 0.25-1.5 mm.

  As an example of means capable of adjusting the thickness 4W (see FIG. 3) of the side seal portion 4 to the specific range, a front body continuous body (not shown) including the ventral side F and a back body continuous including the back side R are provided. A laser beam is used as a fusing means for a diaper continuous body (not shown) obtained by superimposing a body (not shown), and a portion of the diaper continuous body where the side seal portion 4 is to be formed is irradiated with the laser light. The method of forming the side seal part 4 by fusing this is mentioned. That is, when the side seal portion 4 is formed by irradiating the diaper continuous body with laser light and fusing it, the thickness 4W of the side seal portion 4 can be in the specific range. In addition, on the basis of a virtual straight line (not shown) that bisects the diaper 1 in the longitudinal direction X, the abdominal side F side is the front body of the diaper 1 and the back side R side is the back body of the diaper 1. The front body continuum is formed with a plurality of front bodies connected in one direction (conveying direction), and the back body continuum is formed with a plurality of back bodies connected in one direction (conveying direction).

  As shown in FIG. 3, the thickness (width) 4W of the side seal portion 4 (the fused portion of the side seal portion 4) is the side seal portion 4 of each of the ventral portion F and the back portion R constituting the side seal portion 4 ( It is larger than the thickness 3W of the portion other than the fused portion). The specific magnitude relationship of the thickness [the thickness 3W of the portion other than the side seal portion 4 of the ventral portion F or the back portion R <the thickness 4W of the side seal portion 4 (fused portion)] is such as a heat roll device. It is difficult to realize by the side seal portion forming method using the pressure heating means. The side seal part (fused part) formed in accordance with a conventional method using a pressure heating means has the side seal part because the abdominal side part and the back side part constituting the side seal part are pressurized in the thickness direction. Is smaller than the original thickness of the ventral part and the dorsal part (thickness of the part other than the side seal part in each of the ventral part and the dorsal part). That is, in a diaper having a side seal part formed by heating and pressurizing the diaper continuum (the front body continuum and the back body continuum), (thickness 3W> thickness 4W). In order to make (thickness 3W <thickness 4W) as in this embodiment, it is important not to pressurize the diaper continuous body in the thickness direction in the step of forming the side seal portion. As a method of dividing the diaper continuous body without applying pressure and forming the side seal portion, fusing using laser light can be mentioned. That is, a method of forming a side seal part by using a laser beam as a fusing means of the diaper continuous body, irradiating the laser beam to a portion where the side seal part is to be formed in the diaper continuous body, and fusing it. It is done. The side seal part formed by such a method satisfies the relationship (thickness 3W <thickness 4W), and the tactile sensation is improved as compared with the side seal part formed by heating and pressurizing the diaper continuous body. The tingling sensation is reduced. The “feeling of tingling” here is as described above. In addition, “the part other than the side seal part 4 of the ventral side part F or the back side part R”, which is a measurement target of the thickness 3W, is a part having the same layer configuration as the part constituting the side seal part 4. For example, the part located between the absorptive main body 2 and the side seal part 4 is mentioned.

The difference (4W-3W) between the thickness 4W and the thickness 3W is preferably 0.10 mm or more, more preferably 0.15 mm or more, and preferably 0.5 mm or less, more preferably 0.45 mm or less, more specifically. Is preferably 0.10 to 0.5 mm, more preferably 0.15 to 0.45 mm. Thicknesses 4W and 3W are respectively observed at a magnification of 50 to 200 times with a microscope (VHX-1000 manufactured by KEYENCE Corp.) at three locations separated in the longitudinal direction in the side seal part of one diaper. In the cross section, the thickness of the part to be measured can be obtained, and can be obtained as an average value of the three thicknesses. During the cross-sectional observation, the measurement target part was observed with no load for thickness 4W, and the measurement target part was observed with a load of 0.5 cN / cm ² sandwiched between flat plates.

  As one of the main features of this embodiment, the abdominal side part F and the back side part R which comprise the side seal part 4 are each comprised including the laminated structure of a some sheet-like member, Among the sheet-like members, the melting point of the constituent fibers of at least one sheet-like member is configured to be different from the melting point of the constituent fibers of the other sheet-like members, and the laminated structure of the ventral side portion F and the back side portion R is The low melting-point innermost layer type laminated structure 41 and the high melting point innermost layer type laminated structure 42 are included. The low-melting innermost layer type laminated structure 41 has an innermost layer [a laminated structure (a laminated structure of the dorsal side R or the ventral side F) opposite to the inner layer structure (a laminated structure of the ventral part F or the dorsal side R). The layer forming the facing surface] is a laminated structure composed of a low melting point sheet-like member having the lowest melting point of the constituent fibers among the plurality of sheet-like members constituting the laminated structure 41. The high melting innermost layer type laminated structure 42 is a laminated structure in which the innermost layer is a high melting point sheet-like member having the highest melting point of the constituent fibers among the plurality of sheet-like members constituting the laminated structure 41.

  Here, regarding the “melting point of the constituent fiber”, when the sheet-like member includes two or more kinds of constituent fibers having different melting points, the constituent fiber having a relatively high melting point among the two or more kinds of constituent fibers. Let the melting point be the “melting point of the constituent fibers” of the sheet-like member. In addition, when the constituent fiber includes two or more kinds of resins having different melting points, such as a composite fiber, the melting point of the resin having a relatively high melting point out of the two or more kinds of resins is set to the melting point of the constituent fiber. And The “constituent fiber” in the “melting point of the constituent fiber” is a fiber having a constituent fiber ratio of the sheet-like member of 15% by mass or more (a mass ratio of 15% by mass or more of the total mass of all constituent fibers of the sheet-like member Fiber) or a fiber having a fiber resin composition ratio of 15% or more (a fiber having a resin content ratio of 15 mass% or more in the total mass of the resin derived from all the constituent fibers of the sheet-like member).

  The main features of this embodiment will be further described with reference to FIG. 4. Four types of seats 31, 32, 36, included in each of the ventral portion F and the back portion R of the side seal portion 4 will be described. 37, only the outer layer sheet 31 located in the outermost layer is different in composition from the other three types of sheets 32, 36, 37, and the melting point of the constituent fibers is higher than those of these other sheets. The other sheets 32, 36, and 37 have the same composition, and therefore the melting points of the constituent fibers are the same. That is, the laminated structure including these four types of sheets includes two types of sheet-like members (two types of the sheet 31 and the sheets 32, 36, and 37) having different melting points of the constituent fibers, and the relative structure thereof is included. The sheet 31 that is a sheet-like member having a high fiber melting point is the high-melting sheet-like member, and the sheets 32, 36, and 37 that are sheet-like members having relatively low melting points of the constituent fibers are all in the low-melting sheet shape. It corresponds to a member.

  And the part shown by the code | symbol 41 in FIG. 4 in each of the abdominal part F and the back part R (sheet | seat laminated structure) is the innermost layer (the abdominal part F and the back part R in the side seal part 4) of this part. Since the layer adjacent to the boundary is formed from the sheet 37 which is the low melting point sheet-like member, the low melting innermost layer type laminated structure is formed. Moreover, the part (sheet | seat laminated structure) shown by the code | symbol 42 in FIG. 4 in each of the ventral | abdominal side part F and the back | dorsal side part R has the innermost layer of this part formed from the sheet | seat 31 which is the said high melting point sheet-like member. Therefore, it is the above-mentioned high melting point innermost layer type laminated structure.

  In the present embodiment, the low-melting-point innermost layer type laminated structure 41 is arranged in a portion other than the upper end portion and the lower end portion in the longitudinal direction (longitudinal direction X) of the side seal portion 4. The upper end of the vertical direction X is arranged. More specifically, as shown in FIG. 4, the refractory innermost layered laminated structure 42 has an upper end portion in the longitudinal direction (vertical direction X) of the side seal portion 4, that is, an open end portion ( The low melting innermost layer laminated structure 41 is disposed at the folded portion of the first exterior sheet 30 and the waist elastic member 51, and the low melting innermost layer laminated structure 41 is located at the upper end in the longitudinal direction of the side seal portion 4. It is arranged near the laminated structure 42 (position away from the lower end in the longitudinal direction).

  When the side seal part is formed using the conventional heat seal method, due to the compatibility of this method with the side seal part and the constituent fibers in the vicinity thereof, the sheets having a low melting point of the constituent fibers, such as the low melting point sheet-like member, are used. In the case of joining by fusion, the joining strength may be smaller than joining by fusion of sheets having a high melting point such as the high melting point sheet-like member. On the other hand, when a laser beam sealing method is used, that is, by irradiating a diaper continuum obtained by overlaying the front body continuum and the back body continuum with laser light and fusing it. When the side seal portion is formed, due to the compatibility between this system and the side seal portion and the constituent fibers in the vicinity thereof, joining by fusion of sheets having low melting points of the constituent fibers, such as the low melting point sheet-like member, Compared to the joining by fusion of sheets having a high melting point such as a high melting point sheet-like member, the joining strength is high. Based on such knowledge, in this embodiment, formation of the side seal part 4 by the laser seal method is adopted, and the ventral side part F and the back side part constituting the side seal part 4 are at least the low melting point maximum. The inner layer type laminated structure 41 is included. Therefore, in this embodiment, the peel strength of the side seal portion 4 is higher in the portion where the low melting innermost layer type laminated structure 41 exists than in the portion where the high melting point innermost layer type laminated structure 42 exists.

  As described above, in the present embodiment, the abdomen side portion F and the back side portion R constituting the side seal portion 4 are each the low melting point innermost layer type in which the sheet 37 that is the low melting point sheet-like member is the innermost layer. Since the laminated structure 41 is included, in the side seal portion 4, the ventral side portion F and the back side portion R are firmly bonded via the seat 37, and thereby, a practically sufficient seal strength (peeling) is applied to the side seal portion 4. Strength). Therefore, it is difficult for the side seal part 4 to be broken when the diaper 1 is worn. The peel strength of the side seal portion is measured as follows.

[Measurement method of peel strength of side seal part]
The peel strength was measured using TENSILON RTC-1150A manufactured by ORIENTEC. Using a sample with the side seal portion cut to a length of 30 mm, the sample was opened at the center layer, chucked on the apparatus, and then peeled off at a speed of 300 mm / min. The value of the maximum point load at this time was defined as the peel strength of the side seal portion. When the sample size is less than 30 mm, the sample is cut with the maximum length x (mm) that can be collected, and the peel strength is measured by the same method. The obtained peel strength a was converted by the formula “a × (30 / x)” to obtain 30 mm peel strength.

  Further, when the diaper 1 is discarded, usually, an operation of grasping the opening end portion of the waist opening 5 and the vicinity thereof (the upper end side of the diaper 1) with both hands and tearing the diaper 1 by the side seal portion 4 is performed. However, in the present embodiment, the upper end portion in the longitudinal direction of the side seal portion 4 that is the starting point of tearing of the diaper 1 is not the low melting point innermost layer type laminated structure 41 having relatively high seal strength (peel strength). Since the high melting point innermost layer type laminated structure 42 having relatively low sealing strength (peeling strength) is located, the diaper 1 can be easily torn at the side seal portion 4. Thus, the diaper 1 has a practically sufficient seal strength and is excellent in operability.

  In the present embodiment, as shown in FIG. 4, the high melting innermost layer type laminated structure 42 includes a folded portion of the first exterior sheet 30 (expandable sheet) including the two sheets 31 and 32. Therefore, the number of the sheet-like members is larger than that of the low-melting-point innermost layer type laminated structure 41 that does not include the folded portion of the sheet. With such a configuration, there is an effect that the feeling of wearing the diaper is improved by increasing the firm feeling of the waist part, which is a part including a high melting innermost layer type laminated structure having a relatively large number of laminated sheet-like members. .

  Moreover, in this embodiment, the specific magnitude relationship (the thickness 3W of the portion other than the side seal portion 4 of the ventral portion F or the back portion R <the thickness 4W of the side seal portion 4) is realized. The side seal portion 4 is formed by irradiating the diaper continuous body with laser light and fusing it, and is formed through fusing by such laser light irradiation. A large number of gaps (not shown) exist in the fused portion of the forming material in the side seal portion 4 formed. It is inferred that such voids originate from voids between the constituent fibers of the sheet before fusing by fusing. That is, when the side seal part is formed by fusing by laser light irradiation, the form of the sheet before the fusing is maintained without being almost destroyed. This is not the heat sealing process widely used as the means for forming the side seal portion. In the heat sealing process, since the sheet to be processed is pressed in the thickness direction, the gaps between the constituent fibers of the sheet are crushed by this pressure, so that the gaps are not formed in the finally obtained side seal part. Is almost nonexistent. As in this embodiment, the shape of the constituent fibers of the sheet is maintained by subjecting the sheet to be heat-sealed without crushing the processed sheet in the thickness direction, and inside the side seal part (fused part). A large number of gaps are formed, the cushioning property and flexibility of the side seal portion are enhanced, and the air permeability is ensured. As a result, the feeling of use such as the texture of the diaper, the improvement of the wearing feeling, and the reduction of the feeling of stuffiness in the diaper is led to. Moreover, since the gap exists in the fusion part of the side seal part 4, the state of the fusion part becomes close to the vicinity thereof, so that the appearance of the diaper is similar to that of underwear. It is done.

  Examples of the method for forming the side seal portion using laser light include the following methods. The workpiece sheet (continuous diaper) is brought into contact with a support member having a light passage portion through which laser light can pass, and the light passing from the support member side to the workpiece sheet in a pressurized state. A method of irradiating the processed sheet with laser light through a section. In such a method of forming the side seal portion, the light passage portion can be, for example, a slit-like opening that penetrates the support member in the thickness direction.

From the viewpoint of more surely realizing the above-mentioned “state in which there are a large number of voids in the fused portion of the forming material in the side seal portion”, the laser light irradiation conditions used for forming the side seal portion include the following conditions: preferable. That is, using a CO ₂ laser, the wavelength output of laser light is 24 W, the diameter of the spot (the portion irradiated with the laser light) is 0.3 mm, and the scanning speed of the laser light is 325 mm / s. From the same viewpoint, the width of the slit-shaped opening (light passage portion) of the support member (the length in the direction orthogonal to the conveyance direction of the processed sheet) is preferably 2 mm. From the same point of view, it is preferable that the applied pressure for bringing the processed sheet into a pressurized state at the time of laser light irradiation is 0.4 MPa.

  As the low-melting-point sheet-like member (sheets 32, 36, and 37 in the present embodiment) and the high-melting-point sheet-like member (sheet 31 in the present embodiment), nonwoven fabrics by various manufacturing methods are preferably used. A heat roll nonwoven fabric, a spunlace nonwoven fabric, a spunbond nonwoven fabric, a melt blown nonwoven fabric, a needle punched nonwoven fabric, etc. are mentioned. Moreover, since the nonwoven fabric comprised from a short fiber is comparatively bulky, its texture is particularly good. Moreover, since the nonwoven fabric comprised from a long fiber has a comparatively high fiber density, it becomes easy to obtain high sealing strength. Among these, a spunbond nonwoven fabric is particularly preferable as the low-melting sheet-like member, and an air-through nonwoven fabric is preferable as the high-melting-point sheet-like member from the viewpoint of the balance between the texture of the diaper and the seal strength.

  Moreover, as a constituent fiber of each of the low melting point sheet-like member and the high melting point sheet-like member, for example, polyester such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), Examples thereof include fibers made of polyamide and the like. These fibers may be short fibers or long fibers, and may be hydrophilic or water repellent. Moreover, a core-sheath type or side-by-side type composite fiber, a split fiber, a modified cross-section fiber, a crimped fiber, a heat-shrinkable fiber, or the like can also be used. In the case of a conjugate fiber, for example, a combination of PET / PE, PP / PE, PP / low-melting point PP, PET / low-melting point PET, etc. can be used. These fibers can be used alone or in combination of two or more. In addition, these fibers can also be used as a copolymer to which each material is added or an additive such as a lubricant is added.

  As an example of a particularly preferable combination of fibers, the low-melting-point sheet-like member is composed of a single fiber made of PP (PP single fiber content: 100% by mass), and the high-melting-point sheet-like member has a core portion. What is comprised from the core-sheath-type composite fiber (PET / PE core-sheath-type composite fiber content rate 100 mass%) which PET and a sheath part consist of PE is mentioned. According to such a combination of fibers, the above-described effects can be more reliably achieved.

  The diaper 1 mentioned above can be manufactured by the method similar to this kind of underpants type disposable diaper fundamentally. That is, the diaper 1 is obtained by superimposing the front body continuum including the ventral side F and the back body continuum including the back side R to obtain a diaper continuum, and the side seal part 4 is scheduled to be formed in the diaper continuum. It can be manufactured by a manufacturing method including a step of forming the side seal portion 4 by cutting a part. In the diaper continuous body, a plurality of diaper 1 precursors (pants-type disposable diapers in which the pair of side seal portions 4 and 4 are not formed) are continuous in one direction (lateral direction Y).

  The cutting of the site where the side seal portion 4 is to be formed in the diaper continuous body is preferably performed by fusing to melt and cut the site to be formed, from the viewpoint of further ensuring the above-described effects. . Examples of the fusing means include laser light, a heated cutting blade, heat sealing using a known overheated heat sealing means, ultrasonic sealing using a known ultrasonic sealing means that has been overvibrated, and the like. It is done. Among these fusing means, laser light is particularly preferable because the width 4W (see FIG. 3) of the side seal portion 4 can be made relatively small and effective for making the side seal portion 4 inconspicuous from the outside.

  Hereinafter, the first exterior sheet 30 will be described. FIG. 5 shows the sheet 30. The sheet 30 has a configuration in which a thread-like elastic filament is bonded to one surface of an extensible fiber layer mainly composed of inelastic fibers. In this embodiment, as shown in FIG. 5, the outer layer sheet 31 and the inner layer The sheet 32 includes two sheets and a plurality of thread-like elastic filaments 33 sandwiched between the sheets 31 and 32. The sheets 31 and 32 are both “extensible fiber layers mainly composed of inelastic fibers” (in FIG. 5, illustration of inelastic fibers is omitted). The content of non-elastic fibers in the sheets 31 and 32 mainly composed of non-elastic fibers is preferably 60% by mass or more, more preferably 80% by mass or more, and may be 100% by mass.

  Both the outer layer sheet 31 and the inner layer sheet 32 are extensible. The sheets 31 and 32 can be extended in the same direction as the direction in which the elastic filament 33 extends (lateral direction Y). Stretchable means (a) when the constituent fibers themselves of the sheets 31 and 32 are stretched, and (b) even if the constituent fibers themselves are not stretched, the fibers bonded at the intersections are separated or the fibers are This includes the case where the three-dimensional structure formed by a plurality of fibers is structurally changed due to bonding or the like, or the constituent fibers are broken, and the sheets 31 and 32 are extended as a whole.

  The outer layer sheet 31 and the inner layer sheet 32 may be already stretchable in the state of the original fabric before being joined to the elastic filament 33. Alternatively, it is not stretchable in the state of the original fabric before being joined to the elastic filament 33, but is processed so as to be stretchable after being joined to the elastic filament 33, and becomes stretchable. Also good. Specific methods for making the sheet stretchable include heat treatment, roll-to-roll stretching, bite-and-gap stretching with teeth and gears, and tensile stretching with a tenter. In view of a preferable manufacturing method of the first exterior sheet 30 to be described later, the sheets 31 and 32 have good transportability when the elastic filament 33 is fused to the sheets 31 and 32. It is preferable that the original fabric is not stretchable.

  The outer layer sheet 31 and the inner layer sheet 32 are extensible and substantially inelastic. Elasticity is a property that can be stretched and contracts when released from the stretched force, and the sheets 31 and 32 do not have such a property. When the sheets 31 and 32 have elasticity, a fiber containing an elastic resin is required as a constituent fiber thereof, and the fiber containing the elastic resin tends to exhibit a sticky feeling that contributes to lowering the texture of the nonwoven fabric. Therefore, in this embodiment, the sheets 31 and 32 are made substantially inelastic to prevent the texture from being lowered.

  As will be described later, the elastic filament 33 is formed by being stretched in a state where the elastic resin is melted or softened. Each of the plurality of elastic filaments 33 is substantially continuous over the entire length of the first exterior sheet 30 (the entire length in the lateral direction Y of the exterior body 3). The plurality of elastic filaments 33 are arranged so as to extend in one direction (lateral direction Y) without crossing each other. In the present invention, the elastic filaments 33 are allowed to cross unintentionally due to unavoidable fluctuations in the manufacturing conditions of the sheet 30. The plurality of elastic filaments 33 may each extend linearly or may meander while meandering as long as they do not cross each other.

  The elastic filament 33 is joined to the outer layer sheet 31 and the inner layer sheet 32 in a substantially non-stretched state. Since the elastic filament 33 is not stretched, relaxation (creep) due to stretching does not occur, and the stretchability is reduced during storage of the original fabric after the elastic filament 33 is bonded to the sheets 31 and 32 or after processing such as stretching. There is an advantage that there is no. Further, there is no deformation due to the tightness of the wound-up raw material. Further, for example, when the elastic filament 33 is stretched twice and bonded to the sheets 31 and 32, if it is temporarily returned to 1.3 times the initial value, it can be stretched only 1.7 times from this state. However, when pasting is performed in a non-stretched state, the initial origin when the stretchable sheet is stretched is different, so that the stretchable length of the sheets 31, 32 or the maximum elongation of the elastic filament 33 is stretched. There is an advantage that becomes possible.

  The diameter of the elastic filament 33 is not particularly limited, but is preferably 10 μm or more, more preferably 20 μm or more, and preferably 200 μm from the viewpoint of the balance between the texture of the first exterior sheet 30 and the productivity of the elastic filament 33. In the following, it is more preferably 130 μm or less, more specifically, preferably 10 to 200 μm, and more preferably 20 to 130 μm.

  The elastic filament 33 may have a circular cross section, but in some cases may have an elliptical cross section. For example, when the 1st exterior sheet 30 is manufactured according to the manufacturing method (refer FIG. 7) mentioned later, the cross section of the elastic filament 33 tends to become an ellipse. In this case, in the sheet 30, the elastic filament 33 is arranged so that the major axis of the ellipse is in the same direction as the planar direction of the sheet 30 and the minor axis is in the same direction as the thickness direction of the sheet 30. It is preferable.

  The pitch of the adjacent elastic filaments 33, 33 (the distance between the centers of the adjacent elastic filaments) is the elastic filament 33 from the viewpoint of the first exterior sheet 30 exhibiting sufficient stretchability and good cloth-like texture. Is preferably 0.1 mm or more, more preferably 0.4 mm or more, and preferably 5.0 mm or less, more preferably 1.0 mm or less, more specifically, provided that the diameter is within the above-mentioned range. The thickness is preferably 0.1 to 5.0 mm, more preferably 0.4 to 1.0 mm.

  In the first exterior sheet 30, the plurality of elastic filaments 33 are joined to the outer layer sheet 31 and the inner layer sheet 32 over the entire length thereof. Here, “bonded over the entire length” does not require that all the fibers in contact with the elastic filament 33 (component fibers of the sheets 31 and 32) are bonded to the elastic filament 33. This means that the elastic filament 33 and the constituent fibers (non-elastic fibers) of the sheets 31 and 32 are bonded to the elastic filament 33 in such a manner that there is no intentionally formed non-bonded portion. Since the elastic filament 33 is bonded to the sheets 31 and 32 over their entire length, the bonding force between the elastic filament 33 and the sheets 31 and 32 can be sufficiently increased. As a result, even if the sheet 30 is stretched, the elastic filament 33 is difficult to peel from the sheets 31 and 32. When the elastic filament 33 is peeled off from the sheets 31 and 32, in the natural state (relaxed state), floating occurs between the elastic filament 33 and the sheets 31 and 32, and the sheet 30 is easily wrinkled. The sheet 30 as a whole lacks a sense of unity.

  Further, in the first exterior sheet 30, some of a large number of inelastic fibers contained in the outer layer sheet 31 and the inner layer sheet 32 are fused with the elastic filament 33 and buried in the elastic filament 33. The non-elastic fibers embedded in the elastic filament 33 may be all or a part of the non-elastic fibers existing around the elastic filament 33. As used herein (according to the present invention), “buried” means that at the intersection of the inelastic fiber and the elastic filament 33, the portion of the inelastic fiber that is present at the intersection is the intersection of the elastic filament 33. The state that has entered the part that exists in the. Therefore, the state in which the non-elastic fibers and the elastic filaments 33 are joined by dots or lines on their surfaces is not included in the burial according to the present invention. Further, from the viewpoint of improving the bonding strength between the non-elastic fiber and the elastic filament 33, the non-elastic fiber is preferably embedded in the elastic filament 33 with a degree of half or more of its diameter.

  The bonding state between the elastic filament 33 and the non-elastic fibers contained in the outer layer sheet 31 and the inner layer sheet 32 is as described above, so that the bonding strength between the elastic filament 33 and the sheets 31 and 32 is increased. When the exterior sheet 30 is extended, peeling between the two is less likely to occur. As a result, when the sheet 30 is stretched, the sheets 31 and 32 follow the elongation of the elastic filament 33 and stretch with good responsiveness, so that an advantageous effect that the stretchability of the sheet 30 becomes good is achieved. . In addition, since the elastic filament 33 and the non-elastic fibers included in the sheets 31 and 32 are joined as described above, the elastic filament 33 and the sheets 31 and 32 are in close contact with each other, and the presence of the elastic filament 33 is present. Since it is more difficult to feel the level difference between the part that is present and the part that is not present, there is also an advantageous effect that the texture of the sheet 30 is improved.

  The embedded state of the non-elastic fiber in the elastic filament 33 is seen in the portion of the first exterior sheet 30 where the sealing process is not performed, but the sealing process such as the side seal portion 4 is performed. It is not always seen in the part. Here, the sealing process is a process involving melting of the forming material (resin) of the sheet 30, and examples thereof include a heat and pressure process such as an emboss process, an ultrasonic seal process, and a laser beam irradiation process. When the sealing process is performed, a change occurs in the buried state of the inelastic fiber in the elastic filament 33 which originally existed, and the buried state may disappear. Therefore, confirmation of whether or not the inelastic fiber is buried in the elastic filament 33 should be performed at a portion of the exterior body 3 where the sealing process is not performed.

  When the first exterior sheet 30 is manufactured according to a manufacturing method (see FIG. 7) described later, a “state in which the non-elastic fibers are fused with the elastic filaments 33 and embedded in the elastic filaments 33” is obtained. According to the manufacturing method described later, heat is not applied to the sheets 31 and 32, and the elastic filaments 33 are fused to the sheets 31 and 32 before the elastic filaments 33 obtained by melt spinning are solidified. Only the fibers present around the filament 33 are bonded to the elastic filament 33, and the fibers located further away from the filament 33 maintain the texture of the sheets 31 and 32, so the texture of the sheet 30 is good. There is an advantage that it is kept.

  As described above, the elastic filament 33 in the first exterior sheet 30 is joined to the sheets 31 and 32 in a state where the fibers (non-elastic fibers) constituting the sheets 31 and 32 are buried in the elastic filament 33. It is made by fusing to a metal, and is not made by using an adhesive such as a hot-melt adhesive. Therefore, there is no adhesive between the sheets 31 and 32 (extensible fiber layer mainly composed of non-elastic fibers) and the elastic filaments 33 bonded thereto. Since there is no adhesive between the sheets 31 and 32 and the elastic filament 33, the seal strength of the side seal portion including these becomes higher.

  The first exterior sheet 30 can be expanded and contracted in the same direction as the direction in which the elastic filament 33 extends (lateral direction Y). The stretchability of the sheet 30 appears due to the elasticity of the elastic filament 33. When the sheet 30 is stretched in the same direction as the elastic filament 33 extends, the elastic filament 33 and the sheets 31 and 32 extend. When the stretching of the sheet 30 is released, the elastic filament 33 contracts, and the sheets 31 and 32 return to the state before stretching as the contraction occurs. Further, in the sheet 30, there is no other elastic filament bonded in a state orthogonal to the elastic filament 33, so the sheet 30 is stretched in the same direction as the direction in which the elastic filament 33 extends (lateral direction Y). When stretched, the stretchable sheet 30 stretches with little so-called width shrinkage shrinking in the lateral direction Y.

  The constituent fibers and forms of the outer layer sheet 31 and the inner layer sheet 32 (extensible fiber layer mainly composed of inelastic fibers) constituting the first exterior sheet 30 are as described above. The sheet 31 and the sheet 32 may be the same type or different types. As used herein, the “same type of sheet” means sheets having the same manufacturing process, types of constituent fibers of the sheet, fiber diameters and lengths of the constituent fibers, sheet thickness, basis weight, and the like. . When at least one of these is different, it is a “heterogeneous sheet”.

The thicknesses of the outer layer sheet 31 and the inner layer sheet 32 are each preferably 0.05 mm or more, more preferably 0.1 mm or more, and preferably 5.0 mm or less, more preferably 1 mm or less, more specifically preferably Is 0.05 to 5.0 mm, more preferably 0.1 to 1.0 mm. The thickness of the sheet was measured by sandwiching the measurement target sheet between flat plates with a load of 0.5 cN / cm ² , and using three microscopes (VHX-manufactured by KEYENCE) 1000) or the like, and the thickness is obtained at each cross section, and can be obtained as an average value of three thicknesses. The basis weights of the sheets 31 and 32 are each preferably 3 g / m ² or more, more preferably 5 g / m ² or more, and preferably 100 g / m ² or less, from the viewpoints of texture, thickness, and design properties. , more preferably 30 g / m ² or less, and more specifically, preferably 3~100g / m ^2, more preferably at 5 to 30 g / m ^2.

The basis weight of the plurality of elastic filaments 33 arranged between the sheets 31 and 32 (basis weight of the elastic filament layer) is preferably 3 g / m ² or more from the viewpoints of stretchability, texture, thickness, cost, and the like. preferably 4g / m ² or more, and preferably 30 g / m ² or less, more preferably 15 g / m ² or less, more specifically, preferably 3 to 30 g / m ^2, more preferably 4 to 15 g / m ² .

  The elastic filament 33 is made of, for example, a thermoplastic elastomer or rubber. In particular, when a thermoplastic elastomer is used as a raw material, melt spinning using an extruder is possible in the same manner as a normal thermoplastic resin, and the elastic filament thus obtained is easy to be heat-sealed. Suitable for the exterior sheet 30. Examples of the thermoplastic elastomer include styrene such as SBS (styrene-butadiene-styrene), SIS (styrene-isoprene-styrene), SEBS (styrene-ethylene-butadiene-styrene), and SEPS (styrene-ethylene-propylene-styrene). -Based elastomers, olefin-based elastomers (ethylene-based α-olefin elastomers, propylene-based elastomers copolymerized with ethylene, butene, octene, etc.), polyester-based elastomers, polyurethane-based elastomers, and the like. Two or more kinds can be used in combination. Further, core-sheath type or side-by-side type composite fibers made of these resins can also be used.

  Hereinafter, the manufacturing method of the 1st exterior sheet | seat 30 (elastic sheet) is demonstrated, referring FIG. 6 based on the preferable embodiment. In this embodiment, as shown in FIG. 6, the elastic filament 33 is spun from the spinning nozzle 61 and drawn and stretched at a predetermined speed before the elastic filament 33 is solidified. The elastic filaments 33 are fused to the outer layer sheet 31 and the inner layer sheet 32 so that the filaments 33 are arranged in one direction without crossing each other, and then the sheets 31, 32 to which the elastic filaments 33 are fused are joined to the elastic filaments 33. The sheet is stretched along the extending direction of the sheet to impart extensibility to the sheets 31 and 32.

  As shown in FIG. 6, the spinning nozzle 61 is provided in the spinning head 62. The spinning head 62 is connected to the extruder. The resin can also be supplied to the spinning head 62 via a gear pump. The elastic resin melt-kneaded by the extruder is supplied to the spinning head 62. In the spinning head 62, a large number of spinning nozzles 61 are arranged in a straight line. The spinning nozzle 61 is disposed along the width direction of the sheets 31 and 32. The interval between the adjacent spinning nozzles 61 corresponds to the interval between the elastic filaments 33 in the target first exterior sheet 30. The spinning nozzle 61 is usually circular and has a cylindrical nozzle hole.

  The melted elastic filaments 33 spun together with the sheets 31 and 32 fed out from the original fabric at the same speed, and are sandwiched between the sheets 31 and 32 and taken up at a predetermined speed. The take-up speed of the elastic filament 33 coincides with the feeding speed of both sheets 31 and 32. The take-up speed of the elastic filament 33 affects the diameter of the elastic filament 33 and the draw ratio. The tension generated in the elastic filament 33 by stretching prevents the elastic filament 33 from being disturbed due to wind or static electricity when the elastic filament 33 is bonded to the sheets 31 and 32. Thereby, the elastic filaments can be arranged in one direction without crossing each other.

  The elastic filament 33 joins the sheets 31 and 32 before solidification, that is, in a state where it can be fused. As a result, the elastic filament 33 is fused to the sheets 31 and 32 while being sandwiched between the sheets 31 and 32. That is, the elastic filament 33 is pulled and stretched by fusing the elastic filament 33 before solidification to the conveyed sheets 31 and 32. When the elastic filament 33 is fused, heat is not applied to the sheets 31 and 32 from the outside. That is, the elastic filament 33 and the sheets 31 and 32 are fused only by heat of fusion caused by the elastic filament 33 that can be fused. As a result, of the constituent fibers of both sheets 31 and 32, only the fibers present around the elastic filament 33 are fused to the elastic filament 33, and the fibers present at a position further away are not fused. As a result, since the heat applied to both sheets 31 and 32 is kept to a minimum, the good texture inherent to the nonwoven fabric itself is maintained. Thereby, the texture of the obtained first exterior sheet 30 is improved.

  Until the spun elastic filament 33 merges with the sheets 31 and 32, the elastic filament 33 is stretched and molecules are oriented in the stretching direction. Also, the diameter is reduced. From the viewpoint of sufficiently stretching the elastic filament 33 and from the viewpoint of preventing yarn breakage of the elastic filament 33, wind of a predetermined temperature (hot air or cold air) is blown onto the spun elastic filament 33 to adjust the temperature of the elastic filament 33. You may adjust it.

  The stretching of the elastic filament 33 is not only stretching in the molten state (melt stretching) of the resin composition (elastic resin) constituting the elastic filament 33, but also stretching in the softened state (softening stretching) in the cooling process. Also good. As used herein, the molten state is a state in which the resin flows when an external force is applied. The melting temperature of the resin is measured as a peak temperature of Tan δ by viscoelasticity measurement (for example, measured by adding vibration strain in the rotational direction to a resin sandwiched between circular parallel plates). In order to prevent yarn breakage during stretching of the resin composition, it is preferable to secure a long stretching section. From this viewpoint, the melting temperature of the resin composition is preferably 130 to 300 ° C. Further, from the viewpoint of heat resistance (molding temperature) of the resin composition, the melting temperature is preferably 130 to 220 ° C. The softening temperature is measured as the temperature at the inflection point of the storage elastic modulus G ′ in the viscoelastic property of the measurement sample of the resin composition in sheet form. The range from the softening temperature to the melting temperature is called a softened state. The softening temperature is preferably 60 ° C. or higher, more preferably 80 ° C. to 180 ° C., from the viewpoint of crystal growth of the resin composition during storage of the stretchable sheet 30 and a decrease in stretchability of the stretchable sheet 30 due to body temperature.

  At the time of joining the elastic filament 33 and the sheets 31 and 32, the elastic filament 33 is substantially in a non-stretched state (a state in which the elastic filament 33 does not shrink when an external force is removed). In the joined state of the two, at least a part of the fibers (non-elastic fibers) constituting the sheets 31 and 32 are fused to the elastic filament 33, or further, the fibers constituting the sheets 31 and 32 are formed with the elastic filament 33. It is more preferable that both at least a part are fused. This is because sufficient bonding strength can be obtained. The expansion / contraction characteristics of the obtained first exterior sheet 30 are affected by the density of the joining points between the elastic filament 33 and the sheets 31 and 32. The expansion / contraction characteristics can be adjusted by the joining temperature, the joining pressure, and the deviation of the joining points due to the stretching of the sheets 31 and 32 described later. By fusing the constituent fibers of the sheets 31 and 32 to the elastic filament 33, the bonding strength of each bonding point increases. Lowering the density of the joining points is preferable because the first exterior sheet 30 having a sufficient joining strength can be obtained because the expansion and contraction inhibition by the sheets 31 and 32 is reduced.

  When the elastic filaments 33 are merged with the sheets 31 and 32, the elastic filaments 33 are arranged in one direction without crossing each other. Then, in a state where the elastic filament 33 is joined with the sheets 31 and 32 and the elastic filament 33 is sandwiched between the sheets 31 and 32, these three members are clamped by a pair of nip rolls 63 and 63.

  In this way, a composite 30 ′ in which the elastic filament 33 is sandwiched between the two sheets 31 and 32 is obtained. When the sheets 31 and 32 that are inherently extensible are used, the composite 30 ′ becomes the first exterior sheet 30 (expandable sheet) itself. On the other hand, when the sheets 31 and 32 that are not inherently extensible are used, the composite 30 ′ including the sheets 31 and 32 is stretched. This stretching process is performed by an operation of stretching the composite 30 ′ along the direction in which the elastic filament 33 extends to impart extensibility to the sheets 31 and 32. In this manufacturing method, as shown in FIG. 6, using a stretching device including a pair of tooth gap rolls 64, 65 in which teeth and roots are alternately formed in the circumferential direction, By introducing the composite 30 ′ and transporting it, the composite 30 ′ is stretched along the transport direction, that is, the direction in which the elastic filament 33 extends. Thus, the target first exterior sheet 30 (expandable sheet) is obtained.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, in the above-described embodiment, the high melting point innermost layer type laminated structure 42 is disposed only at the upper end in the longitudinal direction of the side seal portion 4, but may be disposed only at the lower end, and is disposed at both upper and lower ends. May be. Moreover, you may arrange | position the elastic member for waist circumference gathers formation, and the elastic member for leg gather formation similarly to the exterior body in this kind of underpants type disposable diaper in the exterior body 3 in the said embodiment. Moreover, the exterior body 3 may have either one or both of both sheets 30 and 36.

  Regarding the above-described embodiment of the present invention, the following additional notes are disclosed.

<1>
An absorbent body and an exterior body disposed on the non-skin-facing surface side of the absorbent body and fixing the absorbent body, and on both side edges and back side of the exterior body on the abdominal side A pants-type disposable diaper in which a pair of side seal parts, a waist opening part and a pair of leg opening parts are formed by joining both side edges of the exterior body,
The thickness of the side seal portion is larger than the thickness of the portion other than the side seal portion of the ventral side portion and the back side portion constituting the side seal portion,
The ventral side portion and the back side portion constituting the side seal portion are each configured to include a laminated structure of a plurality of sheet-like members, and at least one sheet-like shape among the plurality of sheet-like members. The melting point of the constituent fiber of the member is different from the melting point of the constituent fiber of the other sheet-like member,
The laminated structures of the ventral side portion and the dorsal side portion each include a low melting point innermost layer type laminated structure in which an innermost layer is a low melting point sheet-like member having the lowest melting point among the plurality of sheet-like members. ,
The side seal part is formed by irradiating a continuous diaper obtained by superimposing a front body continuum including the ventral part and a back body continuum including the back side by irradiating a laser beam. A pants-type disposable diaper that is formed by.
<2>
The pants-type disposable diaper according to <1>, wherein the low melting innermost layer type laminated structure is arranged in a portion other than the upper end and the lower end in the longitudinal direction of the side seal portion.

<3>
The laminated structure of the ventral side portion and the dorsal side portion includes a high melting point innermost layer type laminated structure in which an innermost layer is composed of a high melting point sheet-like member having the highest melting point among the plurality of sheet-like members. ,
The pants-type disposable diaper according to <1> or <2>, wherein the high melting innermost layer type laminated structure is disposed on at least one of an upper end portion and a lower end portion in the longitudinal direction of the side seal portion.
<4>
The high-melting innermost layer type laminated structure is a pants-type disposable diaper according to the item <3>, wherein the number of laminated sheet-like members is larger than that of the low melting point innermost layer type laminated structure.
<5>
The exterior body includes a laminated body of a first exterior sheet that forms a non-skin facing surface of the exterior body and a second exterior sheet that forms a skin facing surface of the exterior body,
The first exterior sheet has the longitudinal front and rear end portions (extending portions from the longitudinal front and rear end portions of the first exterior sheet) folded back to the skin facing surface side, respectively. 4> The underpants-type disposable diaper according to any one of the above.
<6>
A body cover sheet that crosses the absorbent body in the lateral direction is disposed on the skin facing surface of the exterior body (the second exterior sheet), and the body cover sheet has an overall length in the lateral direction of the exterior body. The underpants type disposable diaper as described in any one of said <1>-<5> which is continuous over and comprises the said side seal part.

<7>
The pants-type disposable diaper according to any one of <1> to <6>, wherein the side seal portion has a thickness 4W of preferably 0.2 mm or more, and more preferably 0.25 mm or more.
<8>
The pants-type disposable diaper according to any one of <1> to <7>, wherein the side seal portion has a thickness 4W of preferably 2 mm or less, more preferably 1.5 mm or less.
<9>
The difference (4W-3W) between the thickness 4W of the side seal portion and the thickness 3W of the portions other than the side seal portions of the abdominal side portion and the back side portion constituting the side seal portion is preferably 0. The pants-type disposable diaper according to any one of <1> to <8>, which is 10 mm or more, more preferably 0.15 mm or more.
<10>
The difference (4W-3W) between the thickness 4W of the side seal portion and the thickness 3W of the portions other than the side seal portions of the abdominal side portion and the back side portion constituting the side seal portion is preferably 0. The underpants-type disposable diaper according to any one of <1> to <9>, which is 0.5 mm or less, more preferably 0.45 mm or less.

<11>
In each of the ventral side portion and the dorsal side portion of the side seal portion, among the plurality of sheet-like members included therein, the outer-layer sheet positioned in the outermost layer is made up of constituent fibers compared to other sheet-like members. The underpants-type disposable diaper according to any one of <1> to <10>, which has a high melting point.
<12>
In each of the ventral side portion and the back side portion of the side seal portion, among the plurality of sheet-like members included therein, the other sheet-like members other than the outer-layer sheet positioned in the outermost layer have the same composition. The pants-type disposable diaper according to any one of <1> to <11>, wherein the constituent fibers have the same melting point.

<13>
The low-melting-point sheet-like member is composed of a single fiber made of polypropylene, and the high-melting-point sheet-like member is composed of a core-sheath type composite fiber having a core part made of polyethylene terephthalate and a sheath part made of polyethylene. The pants-type disposable diaper according to any one of> to <12>.
<14>
The pants-type disposable diaper according to any one of <3> to <13>, wherein the low-melting-point sheet-like member is a spunbond nonwoven fabric, and the high-melting-point sheet-like member is an air-through nonwoven fabric.
<15>
Any of <3> to <14>, wherein the peel strength of the side seal portion is greater in a portion where the low melting innermost layer type laminated structure exists than in a portion where the high melting point innermost layer type laminated structure exists. A pants-type disposable diaper according to claim 1.
<16>
The constituent fibers of the low-melting-point sheet-like member and the high-melting-point sheet-like member are one or more selected from the group consisting of polyethylene fiber, polypropylene fiber, polyethylene terephthalate fiber, polybutylene terephthalate fiber, and polyamide fiber. The pants-type disposable diaper according to any one of <3> to <15>.
<17>
The pants-type disposable diaper according to any one of <3> to <16>, wherein the constituent fibers of the low-melting-point sheet-like member and the high-melting-point sheet-like member are long fibers.
<18>
Any of the above <3> to <17>, wherein the constituent fibers of the low-melting-point sheet-like member and the high-melting-point sheet-like member are one type or two or more types selected from the group consisting of the following core-sheath type composite fibers. A pants-type disposable diaper according to claim 1.
A core-sheath type composite fiber whose core part is made of polyethylene terephthalate and whose sheath part is made of polyethylene. Core-sheath type composite fiber whose core part is made of polypropylene and whose sheath part is made of polyethylene. Sheath-type composite fiber, core-sheath type composite fiber <19> whose core is made of polyethylene terephthalate and whose sheath is made of low-melting-point polyethylene terephthalate
The underpants-type disposable diaper according to any one of <1> to <18>, wherein a large number of voids exist in a fusion bonding portion of the forming material in the side seal portion.

<20>
The exterior body is configured to include an elastic sheet, and the elastic sheet has a configuration in which a thread-like elastic filament is bonded to one surface of an extensible fiber layer mainly composed of non-elastic fibers. The pants type according to any one of <1> to <19>, wherein a part of the non-elastic fiber is fused with the elastic filament and buried in the elastic filament in a portion other than the side seal portion. Disposable diapers.
<21>
The stretchable sheet includes two sheets of an outer layer sheet and an inner layer sheet as the fiber layer, and these two sheets are extendable in the same direction as the direction in which the elastic filament extends (lateral direction). The pants-type disposable diaper according to any one of <1> to <20>.
<22>
The pants-type disposable according to <20> or <21>, wherein the constituent fiber itself of the fiber layer is stretched so that the fiber layer is stretchable in the same direction as the direction in which the elastic filament extends (lateral direction). Diapers.
<23>
Even if the constituent fibers themselves of the fiber layer do not stretch, 1) the fibers bonded at the intersection are separated from each other, and 2) the three-dimensional structure formed by a plurality of fibers is structurally changed by the bonding of the fibers. Or 3) The pants-type disposable diaper according to the above <20> or <21>, wherein the constituent fiber is torn so that the fiber layer can extend in the same direction as the direction in which the elastic filament extends (lateral direction).
<24>
The underpants-type disposable diaper according to any one of <20> to <23>, wherein no adhesive is present between the fiber layer and the elastic filament bonded thereto.
<25>
The pants-type disposable diaper according to any one of <20> to <24>, wherein the elastic filament is bonded to the fiber layer in a substantially non-stretched state.
<26>
The pants-type disposable diaper according to any one of <1> to <25>, wherein the elastic filament is formed by being stretched in a state where an elastic resin is melted or softened.
<27>
The exterior body includes a stretchable sheet having a configuration in which a thread-like elastic filament is bonded to one surface of an extensible fiber layer mainly composed of inelastic fibers, and the fiber layer is heat-treated, stretched between rolls, The pants-type disposable diaper according to any one of <1> to <26>, wherein the pants-type disposable diaper is configured to be stretchable by biting or stretching by a tooth gap or a gear or by tensile stretching by a tenter.

<28>
It is a manufacturing method of the underpants type disposable diaper as described in any one of said <1>-<27>, Comprising: The front body continuous body containing the said abdominal side part and the back body continuous body containing the said back side part The diaper continuum obtained by superimposing has a step of forming the side seal part by irradiating a laser beam and fusing it.
Each of the front body continuum and the back body continuum includes the exterior body, and the exterior body has a thread-like elastic filament bonded to one surface of an extensible fiber layer mainly composed of non-elastic fibers. The manufacturing method of the underpants type disposable diaper which is comprised including the elastic sheet which has the structure which carried out.
<29>
The method for producing a pants-type disposable diaper according to <28>, wherein the elastic filament is formed by being stretched in a state where an elastic resin is melted or softened.
<30>
The method for producing a pants-type disposable diaper according to the above <28> or <29>, wherein the fiber layer is stretchable by heat treatment, inter-roll stretching, biting or gear biting or tensile stretching using a tenter.
<31>
The said fiber layer is a manufacturing method of the underpants type disposable diaper as described in any one of said <28>-<30> which is not expandable in the state of the original fabric before joining with the said elastic filament.
<32>
In the step of forming the side seal portion, the diaper continuum is brought into contact with a support member having a light passage portion through which laser light can pass, and the diaper continuum in a pressurized state is brought into contact with the support member. Irradiate the diaper continuum with laser light from the side through the light passage part,
The laser light is a CO ₂ laser, the laser light has a wavelength output of 24 W, a laser light spot diameter of 0.3 mm, a laser light scanning speed of 325 mm / s,
The light passage portion is a slit-like opening that penetrates the support member in the thickness direction, and the width of the opening is 2 mm,
The manufacturing method of the underpants type disposable diaper as described in any one of said <28>-<31> whose applied pressure with respect to the said diaper continuous body of a pressurization state is 0.4 Mpa.
<33>
The underpants type disposable diaper manufactured by the manufacturing method as described in any one of said <28>-<32>.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to such examples.

[Example 1]
According to a conventional method, a pants-type disposable diaper having the same basic configuration as the diaper 1 shown in FIGS. As an absorbent main body, an absorbent main body of a commercially available pants-type disposable diaper (made by Kao, trade name “Relief is a pants-like undergarment”) is shown in FIG. 5 as a first exterior sheet constituting the exterior body. The following stretchable sheet A having the same structure as the stretchable sheet 30 is used, and a spunbond nonwoven fabric having a basis weight of 18 g / m ^{2 made} of a single fiber of PP is used as the second exterior sheet. The following stretchable sheet A was disposed on the second exterior sheet on the inner layer) and on the non-skin facing surface side (outermost layer). A spunbonded nonwoven fabric having a basis weight of 18 g / m ^{2 made} of a single fiber of PP was used as the main body cover sheet. In the manufacture of the diaper of Example 1, using a laser beam as a fusing means of a diaper continuum (a laminate of a front body continuum including the abdomen and a back body continuum including the back side), the diaper continuum The side seal portion was formed by irradiating a laser beam to the portion where the side seal portion was to be formed and fusing it. The laser beam irradiation was performed using an apparatus having the same configuration as the laser type bonding apparatus described in Japanese Patent Application Laid-Open No. 2010-188629 related to the previous application of the present applicant. As the laser light, a CO ₂ laser was used, the laser output was 24 W, the spot diameter was 0.3 mm, the scanning speed was 90 mm / s, and the energy density D was 0.89 J / mm ² . The energy density D (unit: J / mm ² ) is a value obtained by dividing the energy of the irradiated laser light by the area of the irradiated region, and is calculated by the following formula (1). In formula (1), P is the laser output (W), φ is the diameter (mm) of the spot of the laser beam on the sheet to be melted (diaper continuum), and v is the scanning speed (mm / s) of the laser beam.

<Elastic sheet A>
According to the manufacturing method shown in FIG. 6, an elastic sheet A having a configuration in which an elastic filament is sandwiched between two different fiber layers made of non-elastic fibers (non-elastic fiber content: 100 mass%) was manufactured. At the time of manufacturing the stretchable sheet A, as shown in FIG. 6, a composite in which an elastic filament is sandwiched between two sheets is used in a circumferential direction such as a pair of tooth gap rolls 64 and 65. By passing an elastic expression treatment device (stretching device) provided with a pair of tooth gap rolls alternately formed in the actual length direction, the composite was imparted with stretchability to obtain a stretchable sheet A. The elastic sheet A has a large number of elastic filaments arranged in parallel with each other at a predetermined interval.
Elastic filament: Styrenic thermoplastic elastomer, fiber diameter 110 μm
-Basis weight of elastic filament: 10 g / m ²
One fiber layer (the inner layer sheet): a spunbonded nonwoven fabric having a basis weight of 18 g / m ^{2 made} of a single PP fiber (non-elastic fiber, fiber thickness 3.5 dtex). The other fiber layer (the outer layer sheet) : Basis weight of air-through nonwoven fabric / elastic sheet A having a basis weight of 20 g / m ² made of core-sheath type composite fiber (non-elastic fiber, fiber thickness: 3.0 dtex) of PET (core) / PE (sheath): 48 g / m ²

  The configuration of the side seal portion of the diaper of Example 1 will be described with reference to FIG. 4. Of the four types of sheets 31, 32, 36, and 37 existing in the side seal portion, the core of the constituent fiber of the sheet 31 is PET is a core-sheath type composite fiber whose sheath is made of PE, and the constituent fibers of the other sheets 32, 36, 37 are all single fibers of PP. Moreover, since the melting point of the PET / PE core-sheath composite fiber is the melting point of the resin having a relatively high melting point as described above, it is the melting point of PET (265 ° C.). Here, since the melting point of the single fiber of PP is 165 ° C. and lower than the melting point of PET, the sheets 32, 36, and 37 are all the low-melting-point sheet-like members, and the sheet 31 is the high-melting-point sheet-like member. It is. Therefore, as shown in FIG. 4, the ventral side portion and the back side portion constituting the side seal portion of the diaper of Example 1 are respectively arranged in order from the upper end side in the longitudinal direction of the side seal portion in order of the low melting point maximum 41. An inner layer type laminated structure and a high melting point innermost layer type laminated structure 42 indicated by reference numeral 42 are included.

[Example 2]
A pants-type disposable diaper was produced in the same manner as in Example 1 except that the following elastic sheet B was used instead of the elastic sheet A.

<Elastic sheet B>
According to the manufacturing method shown in FIG. 6, an elastic sheet B having a configuration in which an elastic filament is sandwiched between two same-type fiber layers made of non-elastic fibers (content of non-elastic fibers of 100% by mass) was manufactured. At the time of manufacturing the stretchable sheet B, as shown in FIG. 6, the composite in which the elastic filament is sandwiched between the two sheets is used in the circumferential direction such as the pair of tooth gap rolls 64 and 65. By passing an elastic expression treatment device (stretching device) provided with a pair of tooth gap rolls alternately formed in the (actual length direction), the composite was given stretchability, and an elastic sheet B was obtained. In the stretchable sheet B, a large number of elastic filaments are arranged in parallel with each other at a predetermined interval.
Elastic filament: Styrenic thermoplastic elastomer, fiber diameter 110 μm
-Basis weight of elastic filament: 10 g / m ²
Fiber layer (the inner layer sheet and the outer layer sheet): air-through with a basis weight of 20 g / m ^{2 made} of a core-sheath type composite fiber (non-elastic fiber, fiber thickness: 3.0 dtex) of PET (core) / PE (sheath) Basis weight of nonwoven fabric / expandable sheet B: 50 g / m ²

  The configuration of the side seal portion of the diaper of Example 2 will be described with reference to FIG. 4. Of the four types of sheets 31, 32, 36, and 37 existing in the side seal portion, the sheets 31 and 32 (of the first exterior sheet) The constituent fibers of the constituent sheet) are core-sheath type composite fibers in which the core part is made of PET and the sheath part is made of PE, and the constituent fibers of the other sheets 36 and 37 are all single fibers of PP. That is, the sheets 36 and 37 are both the low melting point sheet-like members, and the sheets 31 and 32 are both the high melting point sheet-like members. Therefore, as shown in FIG. 4, the ventral side portion and the back side portion constituting the side seal portion of the diaper of Example 2 are respectively arranged in order from the upper end side in the longitudinal direction of the side seal portion in order of the lowest melting point indicated by reference numeral 41. An inner layer type laminated structure and a high melting point innermost layer type laminated structure 42 indicated by reference numeral 42 are included.

[Comparative Example 1]
As the constituent fibers of each of the second exterior sheet and the main body cover sheet, the same fibers as the two sheets constituting the first exterior sheet (core-sheath type composite fiber having a core part made of PET and a sheath part made of PE) were used. A pants-type disposable diaper was produced in the same manner as Example 2 except for the above.

[Comparative Example 2]
A pants-type disposable diaper was produced in the same manner as in Example 2 except that the following elastic sheet C was used instead of the elastic sheet B.

<Elastic sheet C>
In accordance with the manufacturing method shown in FIG. 6, an elastic sheet C having a configuration in which an elastic filament is sandwiched between two same-type fiber layers made of non-elastic fibers (content of non-elastic fibers of 100% by mass) was manufactured. At the time of manufacturing the stretchable sheet C, as shown in FIG. 6, the composite in which the elastic filament is sandwiched between the two sheets is used in the circumferential direction such as the pair of tooth gap rolls 64 and 65. Stretchability was imparted to the composite by passing through an elastic expression treatment device (stretching device) provided with a pair of tooth gap rolls alternately formed in the actual length direction to obtain a stretchable sheet C. In the stretchable sheet C, a large number of elastic filaments are arranged in parallel with each other at a predetermined interval.
Elastic filament: Styrenic thermoplastic elastomer, fiber diameter 110 μm
-Basis weight of elastic filament: 10 g / m ²
Fiber layer (the inner layer sheet and the outer layer sheet): a spunbond nonwoven fabric having a basis weight of 18 g / m ^{2 made} of a single fiber of PP (non-elastic fiber, fiber thickness 3.5 dtex), basis weight of the stretch sheet C: 46g / m ²

  If the structure of the side seal part of the diaper of Comparative Examples 1 and 2 is described based on FIG. 4, in the diaper of Comparative Example 1, the constituent fibers of the four types of sheets 31, 32, 36, and 37 existing in the side seal part are: Each is a core-sheath type composite fiber in which the core part is made of PET and the sheath part is made of PE, and in the diaper of Comparative Example 2, the constituent fibers of the four types of sheets 31, 32, 36, 37 existing in the side seal part are: Both are single PP fibers. That is, the low-melting-point sheet-like member and the high-melting-point sheet-like member do not exist in the side seal portions of the diapers of Comparative Examples 1 and 2, and therefore, the ventral side portion and the back side that constitute these side seal portions. The portion does not include the low melting point innermost layer type laminated structure and the high melting point innermost layer type laminated structure 42.

[Evaluation]
About the diaper of each Example and the comparative example, five panelists evaluated the texture of the side seal part and the seal strength, respectively. For the texture of the side seal part, let each paneler touch the side seal part, ○ if it feels soft, X if it feels hard, the case where there are 4 or more panelists evaluated as ○, Evaluation ○ A case of 3 or less persons was regarded as an overall evaluation x. Also, regarding the seal strength of the side seal part, if each panelist peels off the side seal part, as a feeling at that time, if the seal strength is sufficient and feels easy to peel off, wear diapers that are easy to peel off The case where the occurrence of inconvenience such as tearing of the side seal portion was concerned was rated as x, the case where there were 4 or more panelists evaluated as ◯, the overall evaluation, and the case where the number was 3 or less was regarded as the overall evaluation x.

  As a result, in Examples 1 and 2, both the texture and the seal strength of the side seal portion were comprehensively evaluated, whereas Comparative Example 1 was an overall evaluation of the texture, and a comprehensive evaluation of seal strength ×. Further, Comparative Example 2 was an overall evaluation x of the texture and an overall evaluation o of the seal strength. From the above results, in order to improve the feeling of wearing the diaper by increasing the texture of the side seal portion, and to provide the side seal portion with practically sufficient seal strength and excellent operability, the side seal portion is It can be seen that it is effective to dispose the aforementioned low melting innermost layer type laminated structure and high melting point innermost layer type laminated structure on each of the ventral side portion and the back side portion constituting the same.

DESCRIPTION OF SYMBOLS 1 Pants type disposable diaper 2 Absorbent main body 3 Exterior body 30 1st exterior sheet (elastic sheet)
31 Outer layer sheet (high melting point sheet-like member)
32 Inner layer sheet (low melting point sheet-like member)
33 Elastic filament 36 Second exterior sheet (low melting point sheet-like member)
37 Body cover sheet (low melting point sheet-like member)
4 Side seal part 41 Low melting innermost layer laminated structure 42 High melting innermost layer laminated structure F Abdominal side M Crotch part R Back side

Claims (8)

An absorbent body and an exterior body disposed on the non-skin-facing surface side of the absorbent body and fixing the absorbent body, and on both side edges and back side of the exterior body on the abdominal side A pants-type disposable diaper in which a pair of side seal parts, a waist opening part and a pair of leg opening parts are formed by joining both side edges of the exterior body,
The thickness of the fusion part of the side seal part is larger than the thickness of the part other than the fusion part of the side seal part of the abdomen and the back part constituting the side seal part,
The ventral side portion and the back side portion constituting the side seal portion are each configured to include a laminated structure of a plurality of sheet-like members, and at least one sheet-like shape among the plurality of sheet-like members. The melting point of the constituent fiber of the member is different from the melting point of the constituent fiber of the other sheet-like member,
The laminated structures of the ventral side portion and the dorsal side portion each include a low melting point innermost layer type laminated structure in which an innermost layer is a low melting point sheet-like member having the lowest melting point among the plurality of sheet-like members. ,
The side seal part is formed by irradiating a continuous diaper obtained by superimposing a front body continuum including the ventral part and a back body continuum including the back side by irradiating a laser beam. A pants-type disposable diaper that is formed by. The pants-type disposable diaper according to claim 1 , wherein the low-melting-point sheet-like member of the innermost layer in the low-melting-point innermost layer type laminated structure is disposed in a portion other than the upper end and the lower end in the longitudinal direction of the side seal portion. The laminated structure of the ventral side portion and the dorsal side portion includes a high melting point innermost layer type laminated structure in which an innermost layer is composed of a high melting point sheet-like member having the highest melting point among the plurality of sheet-like members. ,
The pants-type disposable diaper according to claim 1 or 2, wherein the high-melting innermost layer type laminated structure is disposed on at least one of an upper end portion and a lower end portion in the longitudinal direction of the side seal portion.   The pants-type disposable diaper according to claim 3, wherein the high melting innermost layer type laminated structure has a larger number of laminated sheet-like members than the low melting innermost layer type laminated structure.   The low-melting-point sheet-shaped member is composed of a single fiber made of polypropylene, and the high-melting-point sheet-shaped member is composed of a core-sheath type composite fiber having a core part made of polyethylene terephthalate and a sheath part made of polyethylene. Or the underpants type disposable diaper of 4.   6. The peel strength of the side seal portion is higher in a portion where the low melting innermost layer type laminated structure exists than in a portion where the high melting point innermost layer type laminated structure exists. The pants-type disposable diaper described in 1.   The underpants type disposable diaper as described in any one of Claims 1-6 in which many space | gap exists in the fusion | melting part of the forming material in the said side seal part. The exterior body is configured to include an elastic sheet, and the elastic sheet has a configuration in which a thread-like elastic filament is bonded to one surface of an extensible fiber layer mainly composed of non-elastic fibers. The pants-type disposable diaper according to any one of claims 1 to 7, wherein a part of the non-elastic fiber is fused with the elastic filament and buried in the elastic filament in a portion other than the side seal portion.

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