RU2659888C2 - Pant-type disposable diaper and production method for same - Google Patents

Abstract

FIELD: hygiene.

SUBSTANCE: outer covering (3) includes a laminate of stretchable sheet (30) containing elastic fibres and non-elastic fibres, and a non-stretchable sheet containing no elastic fibres. Thickness of side seal (4) is greater in comparison with the thickness of sections other than the side seal (4), in front side part (F) and rear side part (R), respectively, which constitute the side seal.

EFFECT: at outside end surface (40) there is formed smooth area (35) in which outside end surface (40) of side seal (4) is smooth, elastic fibres being present in smooth area (35).

31 cl, 13 dwg, 1 tbl

Description

FIELD OF THE INVENTION

The present invention relates to a pull-on disposable diaper with side seams.

State of the art

Typically used are widely known stretchable disposable diapers, including: an absorbent block and an outer shell that is located on the side of the surface of the absorbent block not facing the skin, and on which the absorbent block is fixed; in which a pair of side seams, a hole for the waist and a pair of holes for the legs are formed by bonding both transverse side edges of the front section of the outer shell with the corresponding transverse side edges of the rear section (outer shell. For example, in patent literature 1 describes the use of a stretchable disposable outer shell a diaper with the aforementioned structure of an elastic sheet having a structure in which filamentary elastic filaments are integrated into the surface of the stretchable fibrous th layer, mainly consisting of inelastic fibers.

In addition, for fastening sheets superimposed on each other at the production stage of absorbent articles, such as disposable diapers and sanitary towels, heating roller devices are traditionally widely used. Typically, side seams are formed using a heating roller device. Other known bonding methods include ultrasonic welding methods (e.g., see Patent Literature 2) and laser beam methods (e.g., see Patent Literature 3).

A stretchable disposable diaper is usually produced according to the following steps. First, a continuous (uncut) diaper strip is produced, such as a continuous diaper strip, indicated by reference number 10 in figures 6 and 13, where a plurality of diapers in uncut form are placed on one line in one direction (conveyor movement direction). Then, the front portion and the rear portion of the outer shell, which are superposed on each other, are fastened together with a fastening means, such as a heating roller device, in that place of the continuous strip of diapers where the side seam is to be formed. The bonded portion is then cut with a cutting device, such as a cutting machine, to separate each diaper. When the user wears such a conventional pull-on disposable diaper manufactured as described above, the side seams (sections along the cut line of the fastened sections resulting from cutting with the aforementioned cutting device) protrude outward from the outer surface of the diaper in a state where the left and right lateral lateral the edges of the area intended for location on the front side of the body, and the left and right transverse side edges of the area intended for location on the back Torons shell superposed at the location of their flat on each other (in the style of "gassho", palm to palm type).

List of references

Patent Literature

Patent Literature 1: Japanese Patent No. 4841475

Patent Literature 2: JP 2006-82556 A

Patent Literature 3: JP 2010-188629 A

SUMMARY OF THE INVENTION

The present invention relates to a pull-on disposable diaper, including: an absorbent block and an outer shell that is located on the side of the surface of the absorbent block not facing the skin, and on which the absorbent block is fixed; in which a pair of side seams, a hole for the waist and a pair of holes for the legs are formed by bonding portions of both transverse lateral edges of the portion intended to be located on the front side of the body, the outer shell with the corresponding sections of the transverse side edges of the rear portion of the outer shell. The outer sheath is formed by incorporating an elastic sheet including elastic fibers and inelastic fibers therein. Each side seam is formed by bonding by fusing a portion of the transverse side edge of the portion intended to be located on the front side of the body, the outer shell with a portion of the transverse side edge of the rear portion of the outer shell in a state where the portion of the transverse side edge of the portion intended to be located on the front side of the body and the transverse lateral edge portion of the rear portion is flat on top of each other (gassho style), and the elastic fibers are inside such bonded by fusion plot. On the outer end surface of the side seam, the end portion of each elastic fiber protrudes no more than the peripheral portion of the end portion.

Also, the present invention (the first aspect of the invention) relates to a pull-on disposable diaper, including: an absorbent block and an outer shell, which is located on the side of the surface of the absorbent block, not facing the skin, and on which the absorbent block is fixed; in which a pair of side seams, a hole for the waist and a pair of holes for the legs are formed by bonding portions of both transverse side edges of the front portion of the outer shell with the corresponding sections of the transverse side edges of the rear portion of the outer shell. The outer shell is formed by incorporating a laminate therein, consisting of an elastic sheet that includes elastic fibers and inelastic fibers, and an inelastic sheet that does not include elastic fibers. The thickness of the side seam exceeds the thickness of the section, not counting the side seam, in each of the sections (front section and rear section) that form the side seam. A smooth region is formed on the outer end surface of each side seam in which the outer end surface is smooth and the elastic fibers are inside the smooth region.

Also, the present invention (the second aspect of the invention) relates to a pull-on disposable diaper, including: an absorbent block and an outer shell, which is located on the side of the surface of the absorbent block, not facing the skin, and on which the absorbent block is fixed; in which a pair of side seams, a hole for the waist and a pair of holes for the legs are formed by bonding portions of both transverse side edges of the front portion of the outer shell with the corresponding sections of the transverse side edges of the rear portion of the outer shell. The outer shell is formed by incorporating an elastic sheet therein. The elastic sheet has a structure in which filamentary elastic filaments are attached to the surface of an extensible fibrous layer, mainly consisting of inelastic fibers. In sections of the outer shell, with the exception of the side seams, part of the inelastic fibers are bonded by fusion with elastic filaments and pressed into elastic filaments. On the outer end surface of each side seam, a region is formed of spherical end sections assembled close to each other, where the corresponding spherical end sections of inelastic fibers are assembled close to each other, and the end section of each elastic filament is inside this region.

The present invention (the second aspect of the invention) also relates to a method for manufacturing the aforementioned stretchable disposable diaper, the production method comprising the steps of: producing a continuous strip of diapers by stacking a continuous portion intended to be placed on the front side of the body, in which there are many sections, designed to be located on the front side of the body, each of which includes the aforementioned front section, lined up in a continuous line in one the direction, and a continuous portion intended for location on the rear side of the body, in which a plurality of portions intended for location on the rear side of the body, each of which includes the aforementioned rear portion, is lined up in a continuous line in one direction; and forming a side seam by fusing and cutting a section on a continuous strip of diapers where a side seam is to be formed, the fusion and cutting being carried out in a state where the continuous strip of diapers is stretched along the stretching direction of the elastic sheet included in the continuous strip of diapers.

Brief Description of the Drawings

In FIG. 1 is a perspective view schematically illustrating an embodiment of a pull-on disposable diaper according to the present invention (first aspect of the invention).

In FIG. 2 is a plan view schematically illustrating the diaper illustrated in FIG. 1 in a state where the diaper is deployed and extended.

In FIG. 3 is a cross-sectional view schematically illustrating a cross-section along line I-I of FIG. 1.

In FIG. 4 is a perspective view with a partially cut away part, schematically illustrating an elastic sheet used as an outer shell of a diaper illustrated in FIG. 1.

In FIG. 5 is a perspective view of a cross-section of an outer end surface in a portion of a side seam on one side and a neighborhood of such an end surface in a state where the opening for the waist of the diaper illustrated in FIG. 1, open.

In FIG. 6 is a perspective view schematically illustrating some production steps of the diaper illustrated in FIG. one.

In FIG. 7 is a perspective view schematically illustrating an apparatus suitable for use in manufacturing the elastic sheet illustrated in FIG. four.

In FIG. 8 is a perspective view schematically illustrating an embodiment of a pull-on disposable diaper according to the present invention (second aspect of the invention).

In FIG. 9 is a top view with a partially cut away part, schematically illustrating the diaper illustrated in FIG. 8, in a state where the diaper is deployed and extended.

In FIG. 10 is a cross-sectional view schematically illustrating a cross-section along line I-I of FIG. 8.

In FIG. 11 is a perspective view of a cross-section of an outer end surface in a portion of a side seam on one side and a neighborhood of the end surface in a state where the opening for the waist of the diaper illustrated in FIG. 8, open.

In FIG. 12 is a cross-sectional view schematically illustrating the outer end surface of the side seam of the diaper illustrated in FIG. 8, and the vicinity of the end surface.

In FIG. 13 is a perspective view schematically illustrating some production steps of the diaper illustrated in FIG. 8.

Description of Embodiments

Recently, there is a need for stretchable disposable diapers with the appearance of a conventional undergarment. However, pull-on disposable diapers have side seams that are not found in regular underwear. Conventional side seams protrude outward from the outer parts of the diaper and are therefore very noticeable in the appearance of the diaper. Therefore, it is difficult to consider the appearance of the currently stretched disposable diapers as the same as conventional underwear. Also, the corresponding end sections of the elastic threadlike elements that are fixed in the outer sheath protrude outward from the outer end surface of each side seam. Therefore, the outer end surface may be prickly to the touch, and the user may experience pain while touching the outer end surface with his finger while pulling on the diaper. This texture of the side seam is another important factor that distinguishes stretchable disposable diapers from regular underwear. In particular, the corresponding end portions of the elastic threadlike elements that protrude outward from the outer end surface of the side seam, for example, are portions of the hardened resin that solidified after melting, or portions of the resin that formed on the protrusions during pressing simultaneously with the heat-melting technology. The outer end surface of the side seam contains a large number of such protruding resin portions, and therefore, when the user touches the outer end surface with his finger, the resin portions may prick the user's finger and the user may experience pain.

Another possible way to obtain a stretchable disposable diaper with the appearance of conventional underwear relates to mechanical cutting using a cutting device, such as a cutting machine, of the tip on the end surface of a conventional side seam, which is formed according to the conventional method using, for example, heating roller device or ultrasonic welding, as described in patent literature 2, thereby reducing the height of the protrusion of the side seam above the outer surface p dguznika. However, the side seams formed according to conventional methods are formed by pressing the outer shell in the thickness direction, and therefore the thickness (width) of the fusion-bonded portion consisting of materials forming the side seam is relatively small. When mechanically cutting such a thin, fusion-bonded portion, highly protruding resin patches that protrude from the diaper are likely to occur on the cut edge portion. If the user touches such a section of the cutting edge with his hand, the protruding sections of the resin may prick his / her hand and cause pain from the injection.

In addition, in conventional pull-on disposable diapers, the side seams not only protrude much more from the diaper than their peripheral parts, but also the width of the fastened section (the section fastened by fusion) between the left / right transverse lateral edge of the section intended to be located on the front side body, and the left / right transverse lateral edge of the area intended for location on the rear side of the body, is usually about centimeters and is relatively large. This gives rise to problems such as a problem associated with a difficult tear of the side seam during removal of the diaper, and the fact that the side seam can cause pain if it is touched with a finger. Usually, when removing the diaper, the user breaks the side seam by grabbing one side (the area intended to be located on the front side of the body) with one hand and the other side (the area intended for location on the back side of the body) with the other hand, while clamping the side seam between them, followed by separation of the captured parts from each other in the vertical direction (longitudinal direction of the diaper); however, rupture of the side seam will be easier if the width of the joint portion of the side seam is small. However, a stretchable disposable diaper has yet to be provided with an appearance similar to underwear, which is less likely to cause pain if the side seam is touched by hand, and with a slight rupture of the side seam when removing the diaper.

The present invention (the first aspect of the invention) relates to a pull-on disposable diaper with an appearance similar to underwear, which is less likely to cause pain if the side seam is touched by hand, and with a slight rupture of the side seam while removing the diaper.

The present invention (the second aspect of the invention) relates to a pull-on disposable diaper with an appearance similar to underwear, despite the presence of side seams, which is less likely to cause pain if the side seam is touched by hand, and to a method for manufacturing such a diaper.

The present invention (first aspect of the invention) is described below in accordance with its preferred embodiments with reference to the drawings. As illustrated in FIG. 1-3, a diaper 1, which relates to an embodiment of the stretchable disposable diaper according to the present invention, is a stretchable disposable diaper that includes: an absorbent assembly 2 in the assembly and an outer casing 3 that is located on the surface side of the absorbent assembly 2 in the assembly not facing the skin, and on which the absorbent assembly 2 is fixed in the assembly; in which a pair of side seams 4, 4, a hole for the waist 5 and a pair of holes for the legs 6, 6 are formed by bonding portions of both transverse lateral edges 3F, 3F of the front portion F of the outer shell 3, which extend in the longitudinal direction X, with corresponding sections of the transverse the lateral edges 3R, 3R of the rear portion R of the outer shell 3, which extend in the longitudinal direction X.

In the plan view, where the diaper 1 is in the expanded and extended state, as illustrated in FIG. 2, the diaper 1 has a longitudinal direction X, which corresponds to the front to back direction with respect to the wearer's body, and a transverse direction Y, which is perpendicular to the longitudinal direction X. The diaper 1 can be divided into: a section of the crotch M , which is located in the crotch area of the wearer; and the front section F , which is located in front of the crotch section M in the longitudinal direction X; and a rear portion R , which is located after the crotch portion M in the longitudinal direction X. The longitudinal direction X is a direction that extends from the front portion F to the rear portion R through the crotch portion M. The crotch portion M is the region where the recesses are formed to form the corresponding leg openings 6, 6 in the corresponding sections of the transverse side edges along the longitudinal direction X.

It should be noted that in the present description, the “skin-facing surface” is the surface of the disposable diaper or its constituent elements (such as the absorbent assembly 2 in the assembly), which is facing the user's skin while wearing the disposable diaper, while “ non-skin surface "is the surface of a disposable diaper or its constituent elements, which, while wearing a disposable diaper, is facing in the opposite direction from the user's skin (that is, towards udders). The “longitudinal direction X” (i.e., the length direction) is equivalent to the direction along the long sides of the disposable diaper or absorbent assembly 2 in the assembly, which is an integral part of the diaper, while the “transverse direction Y” is equivalent to the width direction of the disposable diaper or absorbent assembly 2 in assembly, which is an integral part of the diaper.

As illustrated in FIG. 2, the absorbent assembly 2 in the assembly has an elongated elongated shape that is relatively long in one direction (longitudinal direction X) and includes: an upper sheet 21 that forms a surface facing the skin; bottom sheet 22, which forms a surface not facing the skin; and an absorbent element 23 holding the liquid, located so as to fill the gap between the two sheets 21, 22. The absorbent element 23 has a shape elongated in the same direction as the longitudinal direction X. The absorbent assembly 2 in the assembly is attached to the central part of the outer shell 3 using known means of attachment (for example, glue) so that the length direction of the absorbent assembly 2 in the assembly is equivalent to the longitudinal direction X of the diaper 1 in the state when the diaper is deployed and a stretched state (the state illustrated in FIG. 2).

As for the upper sheet 21, the lower sheet 22 and the absorbent element 23, which make up the absorbent assembly 2 in the assembly, various materials traditionally used in the art can be used without particular limitation. For example, a liquid permeable sheet, such as one of various nonwovens subjected to hydrophilization treatment, or a porous film, can be used for the topsheet 21. For the bottom sheet 22, liquid impervious or water-repellent material can be used. Examples of liquid impervious materials that can be used include: resin films; microporous moisture-permeable resin films; and laminating materials consisting of resin films and non-woven materials. Examples of water-repellent materials that can be used include: multilayer composite non-woven materials, such as spunbond / meltblown / spunbond non-woven materials; Spunbond non-woven materials; thermally bonded non-woven materials; and non-woven materials obtained by air packing. For the absorbent element 23, it is possible to apply an element formed, inter alia, by an absorbent core consisting of water-absorbing polymer particles and a fibrous material such as cellulose fiber. The absorbent core may be wrapped with a core wrapping sheet, such as sanitary paper.

As illustrated in FIG. 2, on the respective transverse sides of the absorbent assembly 2 in the assembly, which extend along the longitudinal direction X, provide lateral flaps 24, 24, each of which consists of a waterproof / water-repellent and breathable sheet material. Each lateral lapel 24 rises due to the reduction of the elastic elements 25 of the lateral lapels, which are stretched along the free end of the lateral lapel, which prevents leakage of liquid from the inside outward in the transverse direction Y. In this context, the expression "expanded and stretched state" refers to a state in which the side seams are torn to return the diaper to the expanded (open) state, and the elastic elements in different parts of the expanded diaper are stretched m order to expand the diaper before it is projected size (size in the case when the diaper is deployed in the same plane in a state where the effect of the presence of elastic members completely excluded).

The outer shell 3 includes an elastic sheet 30 with a structure in which two sheets 31, 32 are arranged in layers. As illustrated in FIG. 2, the front and rear end portions (in the longitudinal direction X of the outer shell 3) are folded back towards the side of the surface facing the skin, and with the help of glue, a plurality of elastic threadlike elements 51 for the waist between two outer shells 3 are attached and fixed in tension , 3 (two inelastic sheets 36, 36), which, when bent backward, are opposite each other. At the same time, assemblies are formed on the waist at the edge of the opening for the waist 5.

In the present embodiment, which is illustrated in FIGS. 2 and 3, the outer sheath 3 includes a laminate consisting of an elastic sheet 30 and an inelastic sheet 36. The elastic sheet 30 includes elastic fibers (filamentary elastic filaments 33 (see FIG. .4)), as well as inelastic fibers, while the inelastic sheet 36 does not include elastic fibers, which are a necessary component of the elastic sheet 30, and therefore essentially does not have elasticity. In this context, the term "elasticity" refers to the elasticity of the sheet itself, as such. The inelastic sheet 36 preferably does not have elasticity in the longitudinal direction X or in the transverse direction Y, and more preferably does not have elasticity in both directions X and Y.

The expression "the sheet essentially does not have elasticity in a certain direction" means that the sheet is hardly elongated, even when a force is applied to the sheet that stretches the sheet in that particular direction. For example, if a sample is 15 cm long and 5 cm wide is stretched in the length direction using a tensile testing machine, such as a Tensilon testing machine, and an elongation at break when the sample is torn is 10% or less, the sample is considered to be essentially does not have elasticity in the length direction. Note that the elongation at break can be calculated as follows:

(The length of the sample at the time of rupture is the length of the original sample) / length of the original sample × 100.

In the outer casing 3, the elastic sheet 30 and the inelastic sheet 36 are connected to each other by their respective mating surfaces in a state where the elastic sheet 30 is in a stretched state. Therefore, the outer casing 3 generally has elasticity, at least in the direction in which the elastic filaments 33 are stretched in the elastic sheet 30 (i.e., in the transverse direction Y). In the present embodiment, the sheets 30, 36 are joined using an adhesive, such as hot-melt adhesive, substantially along the entire region of their respective mating surfaces. Examples of “bonding substantially throughout the region” include instances where sheets 30, 36 are bonded with glue tightly applied with a spray gun, etc. on sheet 30 and / or sheet 36; and cases where the sheets 30, 36 are connected evenly using a uniform distribution pattern of glue using a spray gun, a spray gun, a roller coater, or the like.

For the non-elastic sheet 36, it is preferable to use a non-woven fabric made according to one of various methods, with examples including non-woven fabrics of the spunbond type, non-woven materials obtained by air packing, and needle-punched non-woven materials. Preferred among the materials mentioned above are non-woven spunbond materials. Preferably, in the spunbond type nonwoven fabric, the direction of orientation of the fibers coincides with the direction in which the elastic filaments 33 stretch in the elastic sheet 30 (i.e., in the transverse direction Y). Examples of fibers included in the nonwoven fabric used for inelastic sheet 36 include fibers made from polyethylene (PE), polypropylene (PP), polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), and polyamides. The fibers included in the nonwoven fabric used for the inelastic sheet 36 may be short fibers or long fibers, and may be hydrophilic or water repellent. Bicomponent fibers such as core-sheath or side-by-side fibers, split fibers, modified cross-sectional fibers, crimped fibers or heat-shrinkable fibers can also be used. Only one type of fiber can be used, or two or more types of fibers can be used in combination.

From the point of view of more reliable formation of the smooth region 35 (described later), it is preferable that the inelastic sheet 36 be formed from one type of a specific material or include one type of a specific material, the content of which exceeds or is equal to 90 wt.%, Taking into account all materials, forming an inelastic sheet 36. In particular, it is preferable, for example, that the inelastic sheet 36 is formed only of PP fibers, or the content of PP fibers in it is greater than or equal to 90% by weight, taking into account all materials forming an inelastic th sheet 36. Thus, with regard to the fiber (s) of which the inelastic sheet 36 (nonwoven fabric) consists, it is preferable from the above point of view to use an elementary fiber consisting of one type of resin (for example, an elementary fiber consisting of PP), not fibers comprising many types of resins, such as bicomponent fibers or split fibers.

In the present embodiment of the invention illustrated in FIG. 2 and 3, the elastic sheet 30 forms the outer surface of the diaper 1 (the surface of the outer shell 3 not facing the skin), and the inelastic sheet 36 forms the inner surface of the diaper 1 (the surface of the outer shell 3 facing the skin). In the central part in the thickness direction (vertical direction in FIG. 3) of the side seam 4 there are two inelastic sheets 36, that is, one inelastic sheet 36 from the front portion F and one inelastic sheet 36 from the rear portion R, and on both sides the thickness direction are elastic sheets 30 so as to be sandwiched between two inelastic sheets 36.

Side seams 4 are formed by bonding by fusing the edges of several sheets (outer sheet 31, inner sheet 32 and inelastic sheet 36), which form the outer shell 3, in a state where the edges are superimposed, and each side seam includes a sealed by fusion plot. From the point of view of making a less visible side seam 4 and obtaining a diaper 1 with an appearance similar to underwear, it is preferable that the thickness (width) 4W (see Fig. 3) of the side seam 4 (bonded by fusion of the side seam 4) is small. However, if it is too small, the lateral seam 4 will protrude above the surface in the form of a protrusion and can cause pain. Therefore, from the aforementioned point of view, the thickness 4W of the side seam 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 and, in particular, preferably from 0.2 to 2 mm, more preferably 0.25 to 1.5 mm. By adjusting the thickness of the side seam 4 (width of the fusion-bonded portion) 4W to a thickness of the order of millimeters, various effects can be achieved that cannot be achieved with conventional side seams in which the width of the fusion-bonded portion is of the order of centimeters, such as the following effects: side seam tears easily when removing the diaper; the user is less likely to feel pain if the side seam is touched with a finger; and the side seam can be made less noticeable, and you can get a diaper with an appearance, like underwear. An example of a means capable of bringing the thickness of 4W to a thickness of the aforementioned order includes a method of forming a side seam 4 using a laser beam as a melting and cutting means for alloying and cutting the outer shell 3 (sheets 31, 32, 36) (continuous strip described below) diapers (continuous front section of the shell and continuous back section of the shell)); and fusion and cutting of the outer shell section 3, where a side seam 4 is to be formed by irradiating said section with a laser beam.

As illustrated in FIG. 3, the thickness (width) 4W of the side seam 4 (fusion-bonded portion of the side seam 4) exceeds the thickness of the 3W section, not counting the side seam 4 (fusion-bonded portion), on each of the front portion F and the rear portion R that form the side seam 4. Such a specific ratio of thickness dimensions (that is, “thickness 3W of the section, not counting the side seam 4, in the front portion F or the rear portion R" <”of the thickness 4W of the side seam 4 (fusion-bonded portion)") is difficult to achieve with using the method of forming a side seam using We use pressure molding and heating means, such as a heating roller device. The side seam (fusion bonded portion) formed according to the conventional method using pressure pressing and heating means is formed by pressure pressing the front portion and the rear portion, which form the side seam, in the thickness direction, and therefore the thickness of the side seam becomes smaller, than the original thickness of the front section and the rear section (that is, the thickness of the section, not counting the side seam, on each of the front section and the rear section). Thus, in a diaper with side seams formed by heating and pressing under pressure the continuous strip of diapers described below (a continuous section intended to be located on the front side of the body and a continuous section intended to be located on the back side of the body), the ratio thickness 3W> 4W thickness. It is important during the side seam formation step to ensure a ratio of thickness 3W <thickness 4W, as in the present embodiment, not by pressing under pressure a continuous strip of diapers in the thickness direction. An example of a method for cutting and separating a continuous strip of diapers without pressing under pressure is similar, and the formation of a side seam is fusion and cutting using a laser beam, in particular, it is a method of forming a side seam using a laser beam as a means of fusion and cutting continuous diaper strips; and fusing and cutting a section on a continuous strip of diapers where a side seam is to be formed by irradiating said section with a laser beam. The side seam formed according to this method satisfies the ratio “thickness 3W <thickness 4W”, and therefore the texture improves and the degree of scratchiness is reduced compared to the side seam formed by heating and pressing under pressure a continuous strip of diapers. Note that the “section, apart from the side seam 4, in the front portion F or the rear portion R", where the thickness 3W is measured, is a section with a structure similar to the structure of the section that the side seam 4 consists of, and in particular, is a section located, for example, between the absorbent assembly 2 in the assembly and the side seam 4.

Each of the 4W, 3W thicknesses can be measured by examining the cross section of the side seam in a separate diaper at a magnification of 50x to 200x using a microscope (VHX-1000; Keyence product), etc. at three points that are located separately from each other in the length direction; finding the thickness of the section by measuring each cross section; and finding the average thicknesses measured at three points. In the study of the cross section, the section to be measured, in the case of measuring the thickness 4W, is examined in an unloaded state, while in the case of the thickness 3W, the section to be measured is examined when the section is placed between flat plates with a load of 0.5 cN / cm ² .

The elastic sheet 30 is described below. The elastic sheet 30 has a structure in which elastic filamentary filaments (elastic fibers) are attached to the surface of an extensible fibrous layer, mainly consisting of inelastic fibers. In the present embodiment, as illustrated in FIG. 4, the elastic sheet 30 includes two sheets, that is, an outer sheet 31 and an inner sheet 32, and a plurality of elastic filament filaments 33 sandwiched between the sheets 31, 32. Each of the sheets 31, 32 is a “stretchable fibrous layer, essentially consisting of inelastic fibers "(although inelastic fibers are not shown in Fig. 4). The percentage of inelastic fibers in each of the sheets 31, 32, mainly consisting of inelastic fibers, is preferably 90 wt.% Or more and more preferably 91 wt.% Or more, and may be 100 wt.%. As illustrated in FIG. 2 and 3, sheet 31 forms the outer surface (the surface of the outer shell 3 not facing the skin) of the diaper 1; and sheet 32 forms a surface adjacent to the inelastic sheet 36.

Both the outer sheet 31 and the inner sheet 32 are stretchable. The sheets 31, 32 are stretchable in the same direction (transverse direction Y) as the direction in which the elastic filaments 33 stretch. In this context, the term “stretchable” covers: (a) cases where the fibers of which the sheets 31 are made, 32 are themselves extensible; and (b) cases where the fibers of which the sheets 31, 32 are composed are not themselves extensible, but the sheets 31, 32 are generally extensible as a result of, for example, the separation of the fibers that were bonded at the points of intersection, bonding and etc. fibers to obtain the resulting structural change in the three-dimensional structure formed by the fibers, or rupture of the fibers that make up the sheets.

The outer sheet 31 and the inner sheet 32 in the form of raw textile materials, before joining the elastic filaments 33 can be stretchable. Alternatively, before attaching the elastic filaments 33, the sheets 31, 32 in the form of raw textile materials may be sheets that are inextensible but which can be made extensible by processing, which will result in the extension of the elastic filaments 33. Examples of specific methods for converting sheets to a tensile state include heat treatment, drawing between the rollers, drawing by passing (engaging) a pair of rollers or gears between the teeth and grooves, and gearing, and drawing in tension on a wide frame. Considering the preferred method of manufacturing the elastic sheet 30, which is further described below, the sheets 31, 32 in the form of raw textile materials are preferably not stretchable, since the ease of transportation of the sheets 31, 32 is improved when the sheets 31, 32 are fused to the sheets elastic filaments 33.

The outer sheet 31 and the inner sheet 32 are stretchable and substantially inelastic. In this context, the term "elastic" refers to the ability to stretch and contract after removal of the tensile force. Sheets 31, 32 do not have this ability. If the sheets 31, 32 are flexible, the sheets, as constituent fibers, must contain fibers including an elastic resin. However, fibers including elastic resin tend to stick together, which can degrade the texture of the nonwoven. Therefore, in the present embodiment, sheets 31, 32 are made substantially inelastic to prevent texture deterioration.

Elastic filaments 33 are formed by stretching an elastic resin in a molten or softened state, as further described below. The plurality of elastic filaments 33 are substantially uncut along the entire length of the elastic sheet 30 (along the entire length of the outer casing 3 in the transverse direction Y). Many elastic filaments 33 are positioned so that they stretch in the same direction (transverse direction Y) and do not intersect with each other. It should be noted that in the present invention, random crossing of the elastic filaments 33 is allowed due to unavoidable variations in the production conditions of the elastic sheet 30. The elastic filaments 33 may stretch linearly or may curvy stretch provided that they do not intersect each other.

Elastic filaments 33 are attached to the outer sheet 31 and the inner sheet 32 in a substantially unstretched state. Since elastic filaments 33 are in an unstretched state, there are advantages, such as the absence of relaxation (elastic recovery) due to stretching; and the elasticity of the filaments does not deteriorate after processing such as drawing, and during storage of the starting textile material obtained after joining the elastic filaments 33 to the sheets 31, 32. Also, the packaged starting textile material does not deform due to contraction. For example, if elastic filaments 33 are attached to sheets 31, 32 after double stretching relative to their original length, and then the filaments return to a length that is 1.3 times their original length, then from this state the filaments can only be stretched to a length of 1.7 times their original length. In contrast, attachment of elastic filaments in an unstretched state is preferable, since it can be stretched to the length to which sheets 31, 32 can be stretched, or to maximize the elongation of elastic filaments 33, since the starting point from which stretching of elastic sheet, different from the above case.

The diameter of the elastic filament 33 is not specifically limited, although in terms of maintaining a balance between the texture of the elastic sheet 30 and the effectiveness of the elastic filaments 33, the diameter is preferably 10 μm or more, and more preferably 20 μm or more, and preferably 200 μm or less and more preferably 130 μm or less and, in particular, preferably 10 to 200 μm, and more preferably 20 to 130 μm.

The cross section of the elastic filament 33 may be round, although in some cases it may be oval. For example, in cases where the elastic sheet 30 is produced according to the manufacturing method described below (see FIG. 7), the cross section of the elastic filaments 33 tends to become oval. In such cases, it is preferable to place the elastic filaments 33 in the elastic sheet 30 so that the major axis of the ellipse is in the same direction as the plane direction of the elastic sheet 30 and the minor axis of the ellipse is in the same direction as the thickness direction of the elastic sheet 30.

From the point of view of obtaining an elastic sheet 30 with sufficient elasticity and an excellent texture similar to a fabric texture, the pitch between adjacent elastic filaments 33, 33 (i.e., the distance between the respective centers of adjacent elastic filaments) is preferably 0.1 mm or more, and more preferably 0.4 mm or more, and preferably 5 mm or less and more preferably 1 mm or less and, in particular, preferably from 0.1 to 5 mm and more preferably from 0.4 to 1 mm, provided that the diameter of the elastic filament 3 3 is in the above range of values.

In the elastic sheet 30, a plurality of elastic filaments 33 are attached to the outer sheet 31 and the inner sheet 32 along their entire length. In this context, the term “attached along their entire length” does not require that all fibers (the fibers of which the sheets 31, 32 are composed) in contact with the elastic filaments 33 are connected to the elastic filament 33, which means that the elastic filaments 33 and the fibers (inelastic fibers) of which the sheets 31, 32 are composed are joined in such a way that in the elastic filaments 33 there are no deliberately formed loose regions. Since the elastic filaments 33 join the sheets 31, 32 along their entire length, the force for attaching the elastic filaments 33 to the sheets 31, 32 can be increased sufficiently. As a result, the elastic filaments 33 are less likely to tear away from the sheets 31, 32, even if the elastic sheet 30 is stretched and lengthened. If the elastic filaments 33 come off from the sheets 31, 32, gaps will form between the elastic filaments 33 and the sheets 31, 32 in the natural state (relaxation state), and folds should obviously form in the elastic sheet 30, which will give a sense of harmony to the whole elastic sheet 30.

In the elastic sheet 30, a portion of the plurality of inelastic fibers included in the outer sheet 31 and the inner sheet 32 are bonded and pressed into the elastic filaments 33. All or some of the inelastic fibers located on the periphery of each elastic filament 33 can be pressed into the elastic filament 33. In this context (according to the present invention), the term “pressed” refers to a state in which at the intersection of the inelastic fiber and the elastic filament 33 the inelastic fiber at the intersection is embedded in the portion of the elastic filament 33 located at the intersection. Therefore, a state in which the corresponding surfaces of the inelastic fiber and the elastic filament 33 are joined together in a line or at a point is not covered by the meaning of the word “depressed” according to the present invention. In addition, from the point of view of increasing the bond strength between inelastic fibers and elastic filaments 33, it is preferable that the inelastic fiber be pressed into the elastic filament 33 to a depth that is greater than or equal to half its diameter.

Since the elastic filaments 33 and inelastic fibers that are part of the outer sheet 31 and the inner sheet 32 are joined in the aforementioned state, the bond strength between the elastic filaments 33 and the sheets 31, 32 is increased, and when the elastic sheet 30 is stretched, peeling of the elastic filaments from the sheets tends to occur less likely. As a result, during the stretching of the elastic sheet 30, the sheets 31, 32 are stretched with a good reaction speed to stretch the elastic filaments 33, while providing the preferred effect of excellent elasticity imparted to the elastic sheet 30. In addition, since the elastic filaments 33 and non-elastic fibers included in the composition of the sheets 31, 32 are connected in the aforementioned state, the elastic filaments 33 are in close contact with the sheets 31, 32, and therefore the difference in thickness between the sections where the elastic filaments are present nty 33, and sections where they are absent, less noticeable, thereby providing the preferred effect in the form of excellent texture of the elastic sheet 30.

It should be noted that the aforementioned state, when inelastic fibers are pressed into the elastic filaments 33, can be observed in sections of the outer shell 3 (elastic sheet 30), which were not subjected to bonding, although they do not have to be visible in sections that are bonded, such as side seams 4. In this context, a “bonding method” refers to a method comprising melting the material (resin) included in the outer shell 3, including examples of heating and pressing under pressure, such as embossing, ultrasonic welding and laser beam irradiation. When the section is held together, a change in the initial state occurs when inelastic fibers are pressed into the elastic filaments 33 and the indented state may disappear. Therefore, whether or not inelastic fibers are pressed into the elastic filaments 33, should be checked in the section of the outer shell 3, which was not subjected to bonding.

By manufacturing the elastic sheet 30 according to the production method described below (see FIG. 7), it is possible to obtain “a state in which inelastic fibers are bonded and pressed into the elastic filaments 33”. According to the production method described below, heating is applied not to sheets 31, 32, but to elastic filaments 33, which are obtained by melt molding and fastened by fusion with sheets 31, 32 until the elastic filaments 33 cure. Therefore, only fibers are joined to elastic filaments 33 located on the periphery of the elastic filaments 33, and the fibers located further away support the texture of the sheets 31, 32, while providing the advantage of maintaining the excellent texture of the elastic sheet 30.

As described above, in the elastic sheet 30, the attachment of the elastic filaments 33 to the sheets 31, 32 is ensured by fusion bonding of the fibers (inelastic fibers) of which the sheets 31, 32 are composed, with the elastic filaments 33 in a state when they are pressed into the elastic filaments 33 ; that is, the attachment is not provided with an adhesive such as hot-melt adhesive. Thus, there is no glue between the sheets 31, 32 (stretchable fibrous layers, mainly consisting of inelastic fibers) and the elastic filaments 33 connected to them.

The elastic sheet 30 is stretchable in the same direction as the direction (transverse direction Y) in which the elastic filaments 33 are stretched. The elasticity of the elastic sheet 30 is due to the elasticity of the elastic filaments 33. When the elastic sheet 30 is stretched and extended in the same direction as the direction in which elastic filaments 33 are stretched, elastic filaments 33 and sheets 31, 32 are stretched. When the tension / extension of the elastic sheet 30 is stopped, the elastic filaments 33 are shortened, and in accordance with the reduction, the sheets 31, 32 are returned to their state before tension and elongation. In addition, in the elastic sheet 30 there are no other elastic filaments attached in a position perpendicular to the elastic filaments 33, and therefore, when the elastic sheet 30 is stretched and extended in the same direction as the direction (transverse direction Y) in which the elastic filaments are stretched 33, the elastic sheet 30 is stretched, with almost no appearance of the so-called “width contraction”, in which the elastic sheet 30 is reduced in the transverse direction Y.

Below will be described the materials forming the elastic sheet 30. As the fibers that make up the outer sheet 31 and the inner sheet 32 (extensible fibrous layers, mainly consisting of inelastic fibers), inelastic fibers that are essentially inelastic are used; and specific examples thereof include fibers consisting of polyethylene (PE), polypropylene (PP), polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), and polyamides. The fibers of which the sheets 31, 32 are composed may be short fibers or long fibers, and may be hydrophilic or water repellent. Bicomponent fibers such as core-sheath or side-by-side fibers, split fibers, modified cross-sectional fibers, crimped fibers or heat-shrinkable fibers can also be used. Only one type of fiber can be used, or two or more types of fibers can be used in combination.

Each of the outer sheet 31 and the inner sheet 32 may be a nonwoven material consisting of uncut filaments or short fibers. In particular, from the point of view of manufacturing a thick and bulk elastic sheet 30, it is preferable that the sheets 31, 32 are non-woven materials consisting of short fibers. Examples of non-woven materials include air-filled non-woven materials, hot-rolled non-woven materials, spunlace woven nonwovens, spunbond non-woven materials, and meltblown non-woven materials. Sheet 31 and sheet 32 may be of the same type, or may be of different types. In this context, the expression "sheets of the same type" refers to sheets in which, for example, the method of producing sheets, the types of fibers that make up the sheets, the diameter and length of the constituent fibers, the thickness and bulk of the sheets are always the same. If one or more of these conditions is different, then the sheets are "sheets of different types."

It is preferable that the fibers (inelastic fibers) included in each of the outer sheet 31 and the inner sheet 32 consist of at least two components including a low melting point component and a high melting point component. In such cases, the fibers that make up the sheets are joined together at their intersection points by heat bonding by fusion, at least by melting the component with a low point. An example of a preferred core-sheath bicomponent fiber comprising at least two components, including a low melting point component and a high melting point component, is a fiber in which the core is a high melting point PET or PP , and the shell consists of PET, PP or PE with a low melting point. In particular, it is preferable to use such bicomponent fibers, since bonding during fusion with elastic filaments 33 becomes strong, and delamination between them is less likely.

The thickness of each outer sheet 31 and each inner sheet 32 is preferably 0.05 mm or more, and more preferably 0.1 mm or more, and preferably 5 mm or less, and more preferably 1 mm or less, and in particular preferably from 0.05 to 5 mm and more preferably from 0.1 to 1 mm. The thickness of each sheet can be set by, firstly, placing the sheet to be measured between flat plates with a load of 0.5 cN / cm ² applied to them; examination of the cross section of this sheet at magnification from 50x to 200x using a microscope (VHX-1000; product of Keyence), etc. at three points that are located separately from each other in the direction of the length of an individual diaper; finding the thickness of each cross section; and finding the average thicknesses measured at three points. Furthermore, in terms of texture, thickness and aesthetics of the design, the bulk of each sheet 31, 32 is preferably 3 g / m ² or more, and more preferably 5 g / m ² or more, and preferably 100 g / m ² or less, and more preferably 30 g / m ² or less and, in particular, preferably from 3 to 100 g / m ² , and more preferably from 5 to 30 g / m ² .

In terms of elasticity, texture, thickness and cost, the bulk (surface density) of the plurality of elastic filaments 33 located between sheets 31, 32 (the bulk of the layer of elastic filaments) is preferably 3 g / m²or more, and more preferably 4 g / m²or more, and preferably 30 g / m² or less, and more preferably 15 g / m² or less and, in particular, preferably from 3 to 30 g / m², and more preferably 4 to 15 g / m².

The material for elastic filament 33 is, for example, a thermoplastic elastomer or rubber. In particular, when a thermoplastic elastomer such as conventional thermoplastic resins is used as the material, melt spinning with an extruder becomes possible. In addition, the elastic filaments thus obtained can be easily thermally bonded by fusion, and are therefore suitable for producing the elastic sheet 30. Examples of thermoplastic elastomers include styrene-based elastomers such as SBS (styrene-butadiene-styrene), SIS (styrene-isoprene-styrene), SEBS (styrene-ethylene-butadiene-styrene) and SEPS (styrene-ethylene-propylene-styrene); olefin-based elastomers (ethylene-based olefin elastomers or propylene-based elastomers copolymerized with ethylene, butene, octene or the like); polyester elastomers; and polyurethane based elastomers. Only one type of elastomer may be used, or two or more types of elastomers may be used in combination. Furthermore, core-sheath bicomponent fibers or side-by-side bicomponent fibers made from the aforementioned resins can be used.

One of the main features of the diaper 1 according to the present embodiment of the invention, which includes an outer casing 3 comprising an elastic sheet 30 structured as described above, is that a smooth region 35 is formed on the outer end surface 40, where the outer end surface 40 of each side seam 4 is smooth; and that the end portion 33a of each elastic filament 33 is inside the smooth region 35, as illustrated in figure 5. As illustrated in figure 3, the outer end surface 40 of each side seam 4 is located on each side of the diaper 1 and is continuous along the entire length of the side seam 4 in the length direction (vertical direction in FIG. 1). At least in the wear state of the diaper 1 (the state where the hole for the waist 5 is open), the outer end surface 40 is not protected externally. It should be noted that in FIG. 5 is an explanatory drawing schematically illustrating a smooth region 35 in a narrow sense, and a smooth region according to the present invention (first aspect of the invention) is not limited to the configuration illustrated in FIG. 5.

In the present embodiment, a smooth region 35 is formed throughout the entire region of the outer end surface 40 of the side seam 4; and the entire area of the outer end surface 40 is a smooth surface. A smooth region 35 is formed by coating corresponding end portions (not shown) of the numerous fibers of the outer shell 3, (elastic sheet 30; inelastic sheet 36), which otherwise would be unprotected outside the outer end surface 40, with a resin formed from the material included in the composition of the outer shell 3. Thus, the smooth region contains small protrusions and depressions created by the corresponding end sections of the fibers that make up the shell, and therefore is not flat, although it is smooth th, and it is not rough to the touch, and creates a feeling of smoothness.

The resin forming the smooth region 35 (the resin covering the corresponding end portions of the numerous fibers that make up the outer shell 3) is formed mainly from the inelastic sheet 36. At the stage of formation of the side seam 4, when, for example, the section of the outer shell 3, where form a side seam 4, irradiate with a laser beam, and fuse and cut such a section, sections of the inelastic sheet 36 that are in the vicinity of the above section where the side seam is to be formed are heated with the heat necessary for lavleniya and cutting to a temperature equal to or higher than the melting point of such sites, and become molten. The molten resin becomes fluid and therefore covers the area of the cut edge of the outer shell 3 resulting from fusion and cutting; and then the resin is cooled and cured, thereby forming a smooth region 35. That is, in the elastic sheet 30, which is in the stretched state, elastic filaments 33 (elastic fibers), which are fibers that are part of the elastic sheet 30, are released during fusion and cutting and they are affected by the compressive force, due to which the length of the elastic sheet 30 is shortened in the transverse direction Y. In addition, the corresponding end sections of the fibers included in the outer sheet 31 and the inner sheet 32, which form the elastic sheet 30, as well as the corresponding end portions of the elastic filaments 33, become spherical in the cut edge portion of the elastic sheet 30. The molten resin formed from the inelastic sheet 36 covers the corresponding spherical end portions of the elastic filaments 33 and fibers, included in the outer sheet 31 and the inner sheet 32, whereby a smooth region 35 is formed.

As illustrated in FIG. 5, in the smooth region 35, the corresponding end sections 33a of the elastic filaments 33 of the outer shell 3 (elastic sheet 30) on the front portion F side are spaced at predetermined intervals therebetween in the length direction (longitudinal direction X) of the region 35 (side seam 4); and also the corresponding end sections 33a of the elastic filaments 33 of the outer shell 3 (elastic sheet 30) from the rear portion R are arranged at predetermined intervals therebetween in the longitudinal direction X. In the transverse direction Y, the end portion 33a of each elastic filament 33 is substantially the same location that the surface of the smooth region 35 (the surface of the resin surrounding the elastic filaments 33), or a little inside (downward in FIG. 5) in the transverse direction Y, so that the surface of the smooth region, but essentially end sections 33a did not protrude outward in the transverse direction Y more than the surface of the smooth region. In other words, on the outer end surface 40 of the side seam 4, the end section 33a of each elastic filament 33 is located essentially in the same place as the peripheral part of the end section, that is, serves as the outer surface of the smooth region 35 and does not protrude outward more than the peripheral part of the end section.

Due to the formation of this smooth region 35 on the outer end surface 40 of the side seam 4 in this way, the texture of the outer end surface 40 is improved and, for example, the outer end surface is not felt prickly when the user wearing the diaper 1 touches the outer end surface with his / her finger, and which is less likely to hurt. In addition, since elastic filaments 33 are present in the smooth region 35 and are subject to compressive forces during the wear of the diaper 1, it is unlikely that the compressive force will decrease during the wear of the diaper, and therefore disadvantages, such as the diaper 1 slipping during wear, effectively eliminated. In addition, as described above, a smooth region 35 is formed by coating the corresponding end portions of the numerous fibers that make up the outer shell 3, with resin formed from the material that is part of the outer shell 3, and at least in the smooth region 35 ( the outer end surface 40) and its surroundings, the gaps between the numerous fibers that make up the shell, are filled with resin. Thus, due to the adhesive effect of the resin, a side seam 4 is provided with a bond strength sufficient for practical use.

The above-mentioned diaper 1 can be produced, for example, according to the production method described below. A method of manufacturing a stretchable disposable diaper according to the present embodiment of the invention includes the steps of producing a continuous strip of diapers by superimposing on each other a continuous portion for positioning on the front side of the body including the front portion F and a continuous portion for positioning from the back sides of the body including the rear portion R; and forming a side seam 4 by fusing and cutting a section on a continuous strip of diapers where a side seam 4 is to be formed. It should be noted that with reference to an imaginary straight line (not shown) that divides the diaper 1 into two parts in the longitudinal direction X, the region the front portion F is the front portion of the shell of the diaper 1, and the region of the rear portion R is the rear portion of the shell of the diaper 1. A continuous front portion of the shell is formed by aligning in a continuous line A number of sections intended to be located on the front side of the body in one direction (direction of movement), and a continuous rear portion of the shell is formed by lining up a continuous line of many sections intended to be located on the back side of the body in one direction (direction of movement).

First, as illustrated in FIG. 6, the absorbent assemblies 2 in the assembly, which are manufactured separately according to the conventional method, are spaced apart and fixed on the inelastic sheet 36 of the ribbon-like outer shell 3 (which is a laminate consisting of a continuous elastic sheet 30 and a continuous inelastic sheet 36; a continuous outer shell), which is continuously fed from a roll of raw textile material (not shown). Each absorbent assembly 2 in the assembly and / or inelastic sheet 36 is pre-coated with glue, such as hot-melt adhesive, and each absorbent assembly 2 in the assembly is fixed to the outer shell 3 (inelastic sheet 36) with glue. In parallel with the placement of the absorbent assemblies 2 in the assembly, a plurality of elastic elements for the waist 51 are placed on both sides 3a, 3a of the continuous outer shell 3, which extend along the width direction in the extended state, the elastic elements being stretched to a predetermined degree of extension. During the insertion of the waist elastic members 51 by means of an adhesive applicator (not shown), hot melt adhesive is continuously or intermittently applied to each waist elastic member 51.

Then, as illustrated in FIG. 6, in predetermined parts of the continuous outer shell 3, where the absorbent assemblies 2 in the assembly and the elastic elements 51 for the waist are located, form leg openings (LH). The step of forming openings for the legs can be carried out using means similar to conventional means used in the manufacturing methods of this type of product, such as rotary cutting machines or laser cutting machines. It should be noted that the leg openings can be formed before the absorbent assemblies 2 are placed in the assembly, and not after their placement, as in the present embodiment.

Then, the continuous outer shell 3 is folded in the width direction (a direction perpendicular to the length direction of the continuous outer shell 3) so that the region of the front portion F and the region of the rear portion R overlap each other. In particular, as illustrated in FIG. 6, after fixing the waist elastic members 51 by folding inward both transverse edges 3a, 3a of the continuous outer sheath 3 that extend along the length direction (travel direction MD), so as to close the elastic members 51; moreover, the outer shell 3 is folded in half together with the absorbent nodes 2 in the assembly in the width direction CD. That is, the continuous front portion of the shell including the front portion F and the continuous rear portion of the shell including the rear portion R are superimposed. The length direction (direction of movement MD (machine direction)) of the continuous outer shell 3 is equivalent to the transverse direction Y of the diaper 1, and the width direction CD (across the machine direction) of the continuous outer shell 3 is equivalent to the longitudinal direction X of the diaper 1. Thus, a continuous strip of diapers 10 is obtained , in which many predecessors of the diaper (stretchable disposable diapers, not yet containing a pair of side seams 4, 4) are lined up in a continuous line in one direction (transverse to board Y).

Then the section 4 'on the continuous strip of diapers 10, where the side seam is to be formed, is fused and cut to form the side seam 4. The fusion and cutting means are not specifically limited, provided that the means can melt and cut material (materials) (fibers) etc.) to form a section 4 '(elastic sheet 30), and examples of such means include: laser beams; heated cutting discs; heat sealing using known heat sealing means using overheating; and ultrasonic welding using known ultrasonic welding means using ultra-long vibration. Among the aforementioned alloying and cutting means, laser beams are particularly preferred due to the advantages that the width 4W (see FIG. 3) of the side seam 4 can be made relatively small and the side seam 4 can be made less visible from the outside.

Section 4 ’, where the side seam is to be formed, contains a section with a twelve-layer structure in which twelve sheets are layered (see Fig. 1), on the edge of the hole for waist 5 and in its vicinity; and a section with a six-layer structure, in which six sheets are layered, in other areas. As illustrated in FIG. 3 and 5, the six-layer structure section consists of three sheets (outer sheet 31 and inner sheet 32 of elastic sheet 30 and inelastic sheet 36), which form a single outer shell 3 (which is a laminate consisting of elastic sheet 30 and inelastic sheet 36 ) in the front section F; and three sheets 31, 32, 36, which form a single outer shell 3 in the rear portion R, and is formed by arranging said six sheets in layers. On the other hand, in a section with a twelve-layer structure, there are two sheets of outer shells 3 on each front section F and rear section R, since during the production of a continuous strip of diapers 10, both transverse edges 3a, 3a of the continuous outer shell are folded inward to close elastic elements 51 for the waist, as described above (see Fig. 6), and therefore, four outer shells 3, 3 are finally layered, as a result of which a section with a twelve-layer structure is formed by arranging twelve sheets 31, 32, 36 layers.

In cases where a laser beam is used as a means for fusion and cutting, for example, when a section 4 ′ with a six-layer structure where a side seam is to be formed, is irradiated with a laser beam in materials (elastic filaments 33, inelastic fibers, etc. ) forming sheets 31, 32, 36 in section 4 ', heat is generated due to direct exposure to the laser beam, so such materials evaporate and escape from the section on a continuous strip of diapers. In this case, the above-mentioned materials forming a sheet in the vicinity of section 4 ’are directly heated by a laser beam and melted. As a result, section 4 'is fused and cut, and the strip-like continuous strip of diapers 10 is cut and separated so that a single diaper precursor is separated from the continuous strip of diapers 10, and at the same time, sections of the cut edges of six sheets 31, 32, 36 in the separated the diaper precursor, which is formed during cutting / separation, as well as the sections of the cut edges of six sheets 31, 32, 36 on a continuous strip of diapers 10, from which the diaper precursor is separated, are fused. The cut edges of the sheets 31, 32, 36 are in the molten state due to the generation of heat during irradiation with the laser beam and immediately after the cessation of irradiation. However, after the irradiation ceases, the sections of the cut edges are easily cooled by the components of the melting and cutting device (not shown), which are in contact with the continuous strip of diapers 10 and separated by the diaper precursor, and are quickly cooled due to atmospheric air and heat transfer to the components of the device. curing. Thus, the sections of the cut edges are converted into fusion-bonded sections in which the materials forming the sections of the cut edges are melted and combined. The same applies when a section with a twelve-layer structure 4 ’, where a side seam is to be formed, is irradiated with a laser beam, and a fusion-bonded section is formed in section 4’. When a fusion-bonded section is formed in one diaper 1, one side seam is formed from a pair of side seams 4, 4. The same operation is repeated, due to which stretchable disposable diapers 1 are continuously produced, each of which includes the aforementioned outer shell 3 ( representing a laminate consisting of an elastic sheet 30 and an inelastic sheet 36), including a pair of side seams 4, 4.

When fusing and cutting the aforementioned continuous strip of diapers 10, it is especially important to fuse and cut (for example, irradiation with a laser beam) in a state where the continuous strip of diapers 10 and, in particular, the peripheral part of the section to be fused and cut (section 4 ', where to form a side seam) is pressed under pressure (pressing) in the thickness direction. When melting and cutting a continuous strip of diapers 10 in a compressed state, the sections of the cut edges of the sheets 31, 32, 36, formed as a result of fusion and cutting, are bonded during fusion more reliably, and as a result, the strength of the side seam 4 when bonded by fusion increases. From the point of view of increasing the strength of the side seam 4 during fusion bonding, it is preferable to apply pressure molding (pressing) of the continuous strip of diapers 10 not only during fusion and cutting (for example, during laser beam irradiation), but also before fusion and cutting and after him. The method of pressing under pressure a continuous strip of diapers 10 is not particularly limited, and examples include a method of winding a continuous strip of diapers 10 around a support of a predetermined shape, such as a cylindrical shape or a flat plate shape, with a predetermined tensile force applied thereto and fusing and cutting into support while maintaining the force of tension; and a method of placing a continuous strip of diapers 10 between the support and another element (pressing element).

It should be noted that when fusing and cutting a continuous strip of diapers 10, whether or not the continuous strip of diapers 10 (outer shell 3) is in a stretched state is not a problem. In particular, the side seam 4 can be formed using: (i) the stage of fusion and cutting (for example, irradiation with a laser beam) of a continuous strip of diapers 10, which is obtained by stacking on top of each other a continuous section, designed to be located on the front side of the body (representing a laminate consisting of a continuous elastic sheet 30 and a continuous non-elastic sheet 36) including the aforementioned front portion F, and a continuous portion intended to be arranged on the back side la, including the aforementioned rear portion R, in a state where the continuous strip of diapers 10 is stretched along the stretching direction (direction of movement MD; the direction in which the elastic filaments 33 are pulled; the transverse direction Y of the diaper 1) of the elastic sheet 30 included continuous strip of diapers 10; or (ii) the step of fusing and cutting a continuous strip of diapers 10 in an unstretched state (natural state) without stretching the continuous strip of diapers 10.

In cases where “fusion and cutting of the outer shell is carried out in a stretched state”, as described above in (i), if the outer shell 3 does not include an inelastic sheet 36 and is formed only by an elastic sheet 30, then the corresponding end sections of the fibers (inelastic fibers) included in the outer sheet 31 and the inner sheet 32 of the elastic sheet 30 will become spherical and a large number of such spherical end sections will be on the outer end surface 40 of the side seam 4, as described on below; and the outer end surface 40 and its surroundings will be formed as a result of the connection of such spherical end sections of the fibers with each other. The connection of such spherical end portions with each other creates gaps between adjacent spherical end portions, which can reduce the bond strength of the side seam 4. In contrast, in cases where the outer shell 3 includes an inelastic sheet 36, as in the present embodiment even if the end portions of the fibers become spherical during the formation of the side seam 4, the molten resin formed from the inelastic sheet 36 will cover the spherical end portions of the fibers he, and the gaps between the spherical end sections will be filled with molten resin. Thus, bond strength is less likely.

For example, suppose that the section 4 ’of the outer shell 3, in the stretched state where the side seam is to be formed, is irradiated with a laser beam, so that it is fused and cut. In this case, immediately after fusion and cutting, the corresponding end sections of the numerous fibers (inelastic fibers) of which the sheets 31, 32 are composed, are in the molten state at the cutting edges of the sheets 31, 32 of the elastic sheet 30, which were formed as a result of fusion and cutting. due to the melting of the resin component, and due to surface tension, the molten resin becomes spherical. In addition, after fusion and cutting, sheets 31, 32 come out of their extended state and try to return to their unstretched state (natural state). Thus, in addition to surface tension, a corresponding force is applied to the corresponding spherical end sections of the numerous inelastic fibers in sheets 31, 32, which returns the fibers to an unstretched state, as a result, the molten resin accumulates at the end sections, creating a larger sphere. If a large amount of molten resin accumulates in the respective spherical end sections of the numerous inelastic fibers 34, the spherical end sections will be combined in a mass of amorphous resin (a large amount of resin). However, due to the tensile force of the numerous elastic filaments 33, which are everywhere located on the sections of the cut edges of the sheets 31, 32, the amount of molten resin that accumulates at each end section of the inelastic fiber does not become so large as to cause the end sections to combine; therefore, at a time when the inelastic fibers return from the expanded state to the unextended state, the molten resin is cured, while the spherical shape of the end sections is maintained and as a result, the end sections of the inelastic fibers become spherical.

On the other hand, in cases where “fusion and cutting of the outer shell is carried out in an unstretched state”, as described above in paragraph (ii), the corresponding end sections of the fibers included in the outer shell 3 do not become spherical at all, as described below. Thus, there is no decrease in the bond strength of the side seam 4. In particular, if the continuous strip of diapers 10 (outer shell 3) is fused and cut in an unstretched state (natural state) without stretching, the corresponding end sections of numerous fibers (inelastic fibers) formed in the result of fusion and cutting, temporarily become spherical due to the surface tension of the molten resin; however, since the continuous strip of diapers 10 is in an unstretched state, and the tensile force of the elastic filament 33 does not work, a large amount of molten resin accumulates on the spherical end sections, and as a result, the end sections combine and form a large volume of amorphous resin. The molten resin cures in such a bulk state, forming a side seam 4.

However, in case (ii), the volume of a large amount of resin that is on the outer end surface 40 of the side seam 4 thus formed is less than the volume of the resin in an uncompressed state before fusion. Therefore, the end portion of the elastic filament 33, in all likelihood, will protrude outward from the outer end surface 40 of the diaper, which can make the side seam 4 prickly to the touch when touching the skin. However, upon receipt of the outer shell 3 with the inelastic sheet 36, as in the present embodiment, the molten resin formed from the inelastic sheet 36 covers the corresponding end portions of the elastic filaments 33 or their periphery, and therefore such a deterioration in texture is effectively eliminated.

As described above, in the present embodiment, during the formation of the side seam 4, even when the end portions of the fibers become spherical, the molten resin formed from the inelastic sheet 36 covers such spherical end portions of the fibers and the gaps between the spherical end portions filled with molten resin, as in the case described above (i); or a large amount of molten resin is collected at the spherical end portions and the end portions are combined to form a large amount of amorphous resin, as in case (ii) described above. Thus, the front portion F and the rear portion R are firmly connected in the side seam 4 and at the same time provide the side seam 4 with bond strength sufficient for practical use (tear strength). Accordingly, during wear of the diaper 1, a rupture of the side seam 4 is less likely to occur. The tear strength of the side seam is measured as follows.

The method of measuring the tensile strength when tearing the side seam

Tear strength was measured using a Tensilon RTC-1150A test machine from Orientec Co., Ltd. A sample was obtained by cutting a side seam 30 mm long. The sample was deployed in the area with the Central layer, clamped using the clamps of the device, and then subjected to delamination at a speed of 300 mm / min. The maximum value of the load applied at a certain point, established during such a process, was taken as the tensile strength during tearing of the side seam. If the sample size is less than 30 mm, cut the side seam of the maximum length x (mm), which can be tested, and according to the same method measure the tensile strength at tear. The resulting tensile strength at tear A is converted according to the mathematical formula A × (30 / x) to find the tensile strength at tear of a 30 mm sample.

From the point of view of bond strength sufficient for practical use (tear strength) and ease of handling, the tear strength of each side seam 4 is preferably 10 N or more, more preferably 13 N or more, and preferably 75 N or less, more preferably 70 N or less and, in particular, preferably from 10 N to 75 N, more preferably from 13 N to 70 N.

A method of manufacturing an elastic sheet 30 is described according to a preferred embodiment of the invention with reference to FIG. 7. In the present embodiment, which is illustrated in FIG. 7, numerous elastic filaments 33 that are molded from spinning dies 61 are received in a molten state and drawn at a predetermined speed, wherein before curing the elastic filaments 33, the elastic filaments 33 are fused to the outer sheet 31 and the inner sheet 32 so that the elastic filaments 33 were located in the same direction without intersecting with each other. Then, sheets 31, 32, with which the elastic filaments 33 are bonded by fusion, are pulled in the direction in which the elastic filaments 33 are stretched to obtain stretchable sheets 31, 32.

As illustrated in FIG. 7, the spinning dies 61 are provided with a spinning head 62. The spinning head 62 is connected to an extruder. The resin can be fed into the spinning head 62 using a gear pump. The elastic resin, which has been melted, mixed and plasticized, is fed into the spinning head 62 using an extruder. The spinning head 62 contains a large number of spinning dies 61 arranged linearly in one row. The spinning dies 61 are arranged along the width direction of the sheets 31, 32. The spacing between adjacent spinning dies 61 is equal to the spacing between the elastic filaments 33 in the elastic sheet 30 to be obtained. Spinning spinneret 61 is usually round and contains a cylindrical bore of the spinneret.

The elastic filaments 33 that have been molded in the molten state are combined with sheets 31, 32 that are fed from a roll of the original textile material at the same speed, clamped, held between sheets 31, 32 and received at a given speed. The speed of reception of elastic filaments 33 is equivalent to the feed speed of the sheets 31, 32 per roll. The rate of reception of elastic filaments 33 affects the diameter and stretch ratio of elastic filament 33. The tensile strength of elastic filaments 33 due to stretching prevents irregularities in the arrangement of elastic filaments 33 caused by air currents or static electricity when elastic filaments 33 are attached to sheets 31, 32. In this way, elastic filaments can be placed in one direction without causing them to intersect with each other.

Elastic filaments 33 are combined with sheets 31, 32 before they are cured, that is, in a state where they are capable of fusion bonding. As a result, the elastic filaments 33 are bonded by fusion with the sheets 31, 32 in a state where they are clamped and held between the sheets 31, 32. That is, when bonded by fusion of the elastic filaments 33 before curing with the sheets 31, 32 that are moving, the elastic filaments 33 accepted and extended. During bonding by fusion, elastic filaments 33, sheets 31, 32 do not heat from the outside. In other words, elastic filaments 33 and sheets 31, 32 are bonded by fusion only due to the heat of fusion of the elastic filaments 33, which are in a state where they are capable of fusion bonding. As a result, of all the fibers that make up the sheets 31, 32, only the fibers that are around the elastic filaments 33 are bonded by fusion with the elastic filaments 33, while the fibers which are located at some distance from the elastic filaments are not bonded by fusion with them. As a result, it is possible to maintain a minimum level of heat applied to the sheets 31, 32, while maintaining the excellent texture inherent in non-woven materials. Therefore, the obtained elastic sheet 30 has an excellent texture.

Before the molded elastic filaments 33 are combined with the sheets 31, 32, the elastic filaments 33 are stretched, while their molecules are oriented in the direction of stretching. The diameter of the elastic filaments is also reduced. From the point of view of a sufficient degree of stretching of the elastic filaments 33 and from the point of view of preventing breakage of the elastic filaments 33, the temperature of the elastic filaments 33 can be controlled by blowing the formed elastic filaments 33 with air (hot air or cold air) with a given temperature.

The stretching of the elastic filaments 33 can be carried out in the form of stretching (stretching the melt) in the molten state, when the resin composition (elastic resin), which consists of the elastic filament 33, is melted; or can be carried out in the form of stretching (stretching the softened material) in the softened state when the resin composition is in the process of cooling. In this context, the term "molten state" is a state in which the resin flows under the action of an external force applied to it. The melting temperature of the resin is measured as the temperature of the Tanδ peak when measuring viscoelastic characteristics (which are measured, for example, by applying vibrational deformation in the direction of rotation to the resin sandwiched between parallel circular flat plates). In order to prevent breakage of the filaments during the drawing of the resin composition, it is preferable to provide long drawing zones. From the above point of view, the melting temperature of the resin composition is preferably from 130 ° C to 300 ° C. From the point of view of heat resistance (molding temperature) of the resin composition, the melting temperature is preferably from 130 ° C to 220 ° C. The softening temperature is measured as the temperature of the inflection point of the curve of the dynamic elastic modulus G ’, among other viscoelastic characteristics of the measured sample of the resin composition, converted into a sheet. A state in the range from softening temperature to melting point is taken as a “softened state”. In terms of crystal growth of the resin composition during storage of the elastic sheet 30 and deterioration of the elasticity of the elastic sheet 30 due to body temperature, the softening temperature is preferably 60 ° C or higher, more preferably 80 ° C to 180 ° C.

In order to provide bonding by fusion of the fibers, the temperature of the elastic filaments 33 during bonding of the elastic filaments 33 and sheets 31, 32 is preferably 100 ° C or higher. From the point of view of maintaining the shape of each elastic filament 33 and obtaining an elastic sheet 30 with excellent elasticity, the temperature of the elastic filament is preferably 180 ° C or lower, and more preferably is in the range from 120 ° C to 160 ° C. The temperature during bonding can be measured using a film, for example, consisting of modified polyethylene or modified polypropylene, which has a melting point different from the melting point of the resin composition of which elastic filaments 33 is used as a multilayer substrate for attaching elastic filaments 33, and studies bonding conditions. If the elastic filaments 33 are bonded by fusion with a multilayer substrate, the bonding temperature is greater than or equal to the melting point of the multilayer substrate.

During the attachment of the elastic filaments 33 to the sheets 31, 32, the elastic filaments 33 are essentially in an unstretched state (a state where they do not contract when external force is removed). In a state where elastic filaments are attached to the sheets, at least a portion of the fibers (inelastic fibers) of which the sheets 31, 32 are composed is fastened by fusion with elastic filaments 33, or, more preferably, both elastic filaments 33 and at least a portion of the fibers of which the sheets 31, 32 are composed are bonded by fusion, since in this way sufficient bonding strength can be obtained. The elasticity of the obtained elastic sheet 30 depends on the density of the bonding points between the elastic filaments 33 and the sheets 31, 32. The elasticity can also be adjusted using the bonding temperature, bonding pressure and dispersion of the bonding points when drawing sheets 31, 32, described below. When bonding by fusion of the fibers that make up the sheets 31, 32, and elastic filaments 33, the bond strength at each of the bonding points is increased. A decrease in the density of the bonding points is preferable, since in this case the suppression of the elasticity of the sheets 31, 32 is less likely, and it is possible to obtain an elastic sheet 30 that has sufficient bonding strength.

When combining the elastic filaments 33 with the sheets 31, 32, the elastic filaments 33 are arranged in the same direction so that they do not intersect with each other. Then, in a state where the elastic filaments 33 are combined with the sheets 31, 32 and the elastic filaments 33 are clamped and held between the sheets 31, 32, the three components are clamped and pressed under pressure using a pair of pressure rolls 63, 63. The clamping and pressing conditions by pressure affect the texture of the obtained elastic sheet 30. If the clamping and pressing force is too large, the elastic filaments 33 are more likely to cut into the sheets 31, 32, and the texture of the obtained elastic sheet 30 will deteriorate. From this point of view, the force of clamping and pressing under pressure with the help of pressure rolls 63, 63 should be used only to the extent that makes the elastic filaments 33 come into contact with both sheets 31, 32, and it should not be excessively large.

Another condition for clamping and pressing under pressure with the pressure rolls 63 is the temperature of the pressure rolls 63. Studies by the inventors have shown that instead of clamping and pressing under pressure in a state where the pressure rolls 63 are heated, an elastic sheet of 30 s can be obtained excellent texture without heating the pressure rolls (i.e., clamping and pressing under natural pressure) or while clamping and pressing under pressure while cooling. In cases of cooling the pressure rolls 63, it is preferable to use a cooling medium, such as cooling water, and adjust the temperature so that the temperature set on the surface of the pressure rolls 63 is from 10 to 50 ° C.

In this way, a composite 30 'is obtained in which the elastic filaments 33 are sandwiched and held between two sheets 31, 32. In the case of sheets 31, 32, which are extensible in nature, the composite 30', as such, turns into an elastic sheet 30. C on the other hand, in cases where sheets 31, 32 are used which are inextensible in nature, the composite 30 'including sheets 31, 32 is subjected to a drawing process. The drawing process is carried out using the drawing operation of the composite 30 ’in the direction in which the elastic filaments 33 are stretched, while giving extensibility to the sheets 31, 32. As illustrated in FIG. 7, in the present production method, a drawing apparatus is used including a pair of gear / grooved rollers 64, 65, where teeth and grooves are alternately formed in the circumferential direction; when the composite 30 ’is introduced between the rollers 64, 65 and the composite is moved, the composite 30’ is stretched along the direction of movement, that is, the direction in which the elastic filaments 33 stretch. Thus, the planned elastic sheet 30 is obtained.

The outer shell 3 is obtained by applying to the inelastic sheet 36 and attaching to it the thus obtained elastic sheet 30, when the elastic sheet 30 is in a stretched condition. For example, the elastic sheet 30 is moved in a stretched state and in this state is combined with the inelastic sheet 36, and the sheets 30, 36 are joined together with glue pre-applied to predetermined areas. From the point of view of facilitating the stretching and contraction of the outer shell 3 in the bonded state, it is preferable to fasten the elastic sheet 30 with the inelastic sheet 36 in a state where the elastic sheet 30 is stretched in the direction of travel 1.1-4.0 times, more preferably 1.2 -3.0 times, and even more preferably 1.5-2.5 times. The degree of stretching of the elastic sheet 30 can be determined by dividing the length of the elastic sheet in its stretched state by its length in the natural state (compressed state) before stretching. When combining or immediately after combining, sheets 30, 36 are clamped and pressed under pressure using a pair of pressure rollers. Using the above steps, an outer shell 3 was obtained which is a laminate consisting of an elastic sheet 30 and an inelastic sheet 36.

It should be noted that it is sufficient only that the elastic sheet according to the present invention includes elastic fibers and inelastic fibers, and the aforementioned elastic sheet 30 is not limited. The aforementioned elastic sheet 30 has a structure (two-layer structure) in which elastic fibers (elastic filaments 33) are attached to the surface of each of the extensible fibrous layers 31, 32, mainly consisting of inelastic fibers, and the elastic fibers and inelastic fibers in the elastic sheet 30 are uneven distributed in the direction of thickness. However, in the elastic sheet according to the present invention, elastic fibers and inelastic fibers can be mixed. In particular, the elastic sheet according to the present invention may be a mixed-type fiber sheet with a single layer structure in which the elastic fibers and inelastic fibers are uniformly distributed throughout the elastic sheet. In the present invention, a plurality of such elastic mixed fiber sheets can be stacked on top of each other. In addition, in the aforementioned diaper 1, including the elastic sheet 30, the “end portion” of each elastic filament 33 on the outer end surface 40 of the side seam 4 is inside the smooth region 35, as described above; however, in cases where instead of the aforementioned elastic sheet 30, the aforementioned mixed fiber elastic sheet is used, the elastic fibers in the elastic sheet will be inside the smooth region 35 and the parts of each elastic fiber present inside the smooth region 35 are not limited to its “end face” site ". However, note that even in cases where the aforementioned elastic sheet of mixed fibers is used, the structure of the smooth region 35 is basically the same as the case of using the elastic sheet 30, and the above description regarding the case of using the elastic sheet 30 is applied as necessary.

As for the inelastic fibers in the aforementioned mixed fiber elastic sheet in which the elastic fibers and inelastic fibers are mixed, fibers acceptable as inelastic fibers in the aforementioned elastic sheet 30 can be used without particular limitation. The material for elastic fibers, for example, can be a thermoplastic elastomer or rubber. As for the material of elastic fibers, without particular limitation, thermoplastic elastomers acceptable as the material of elastic filaments can be used 33. As for elastic fibers, bicomponent core-sheath fibers or side-by-side bicomponent fibers can be used including thermoplastic elastomer.

In particular, it is preferable that the elastic fiber in the mixed fiber elastic sheet is a fiber formed from a polymer including a thermoplastic polyurethane elastomer. Such a polymer may include only a thermoplastic polyurethane elastomer, or may include other polymers in addition to the thermoplastic polyurethane elastomer. The percentage of thermoplastic polyurethane elastomer in the total polymer amount of the elastic fiber is preferably 10 mass% or more, more preferably 30 mass% or more.

The percentage of elastic fiber in the elastic sheet of mixed fiber is preferably 10 wt.% Or more, more preferably 30 wt.% Or more.

Preferably, the elastic sheet of mixed fibers is a nonwoven material. Examples of nonwovens include air-filled nonwovens, hot-rolled nonwovens, spunlace nonwovens, spunbond nonwovens and meltblown nonwovens, spunbond / meltblown / spunbond nonwovens and needle punched nonwovens .

The thickness of the mixed fiber elastic sheet is preferably 0.5 mm or more, more preferably 0.7 mm or more, and preferably 4 mm or less, more preferably 3 mm or less, and in particular preferably from 0.5 to 4 mm, more preferably from 0.7 to 3 mm. In terms of texture, thickness, design aesthetics, etc., the bulk of the mixed fiber elastic sheet is preferably 20 g / m ² or more, more preferably 25 g / m ² or more, and preferably 90 g / m ² or less, more preferably 80 g / m ² or less and, in particular, preferably from 20 to 90 g / m ² , more preferably from 25 to 80 g / m ² .

An elastic sheet of mixed-type fibers can be produced in the same way as fibrous sheets of this type (i.e., fibrous sheets in which many types of fibers are mixed); for example, if the elastic sheet is a non-woven material, it can be produced according to known bonding methods using the Spunbond technology or the Meltblown technology (technology of forming fibers by blowing), and can be produced, for example, according to the method described in JP 2004 -244790 A or JP 2005-089870 A.

The present invention (the first aspect of the invention) is described above according to a preferred embodiment, however, the present invention is not limited to the above embodiments. For example, in the above embodiment of the invention, which is illustrated in FIG. 3 and 5, the inelastic sheet 36 is in the central part in the thickness direction (vertical direction in FIG. 3; the transverse direction in FIG. 5) of the side seam 4, and the elastic sheets 30 (outer sheet 31 and inner sheet 32) are on both sides in the thickness direction so that the inelastic sheet 36 is sandwiched between them, however, the order in which the sheets 30, 36 are arranged in layers is not particularly limited. For example, in contrast to the aforementioned embodiment of the invention, the elastic sheet 30 may be in the central part in the thickness direction of the side seam 4, and the inelastic sheets 36 may be on both sides thereof in the thickness direction so that the elastic sheet 30 is sandwiched between them. In addition, the outer shell 3 may include a plurality of one type of sheets 30 or 36 or both types of sheets 30, 36. Furthermore, as with the outer shells of stretchable disposable diapers of this type, the outer shell 3 according to the aforementioned embodiment may there are elastic elements that form folds below the waist, and elastic elements that form folds around the legs.

In the above embodiment, the outer casing 3 includes a laminate consisting of an elastic sheet 30 and an inelastic sheet 36, however, the outer casing should not include an inelastic sheet 36. However, from the point of view of, for example, increasing the bond strength of the side seam 4, it is preferable so that the outer casing 3 includes a laminate consisting of an elastic sheet 30 and an inelastic sheet 36 and, in particular, as in the aforementioned embodiment of the invention, it is preferable that the inelastic fox 36 located in the central portion in the thickness direction of the side seam 4 and the elastic plates 30 are on both sides of the non-elastic sheet 36 in the thickness direction so that the non-elastic sheet 36 is sandwiched therebetween. Such a structure is preferred, in particular in those cases where the bulk of the elastic sheet 30 is large and, in particular, in those cases where the bulk of the stretch sheet 30 is 10 g / m ² or more. As described above, an elastic sheet 30 is obtained by subjecting a composite 30 ', which includes sheets 31, 32, to a drawing process (see FIG. 7); in particular, in cases where the bulk of the elastic sheet 30 is large, the drawing process will make the elastic sheet wavy, and the entire sheet will be wavy. Therefore, if the outer casing 3 includes only the aforementioned corrugated elastic sheet 30, without including the inelastic sheet 36, the corrugated elastic sheets 30 will be joined together at a portion of the side seam 4 included in the outer shell 3. If the elastic sheets 30, 30 with a high bulk, having a wavy shape, join together, there is a possibility that the protrusions and depressions of the wavy shape on both sheets will not successfully coincide with each other, and the number of contact points between the two sheets 30, 30 will become small shim, leading to a decrease in bond strength. Conversely, in cases where the inelastic sheet 36 is in the central part in the thickness direction of the side seam 4, and on both sides of the inelastic sheet 36, the elastic sheets 30 are located so that the inelastic sheet 36 is sandwiched between them, as in the aforementioned an embodiment of the invention, even if the elastic sheets 30 on both sides of the inelastic sheet 36 are wavy in the thickness direction, the molten resin from the inelastic sheet 36 penetrates into the wavy protrusions and depressions during formation side seam 4 (that is, when the outer shell 3 is fused and cut). Thus, the bonding effect of the molten resin provides a side seam 4 with sufficient bond strength for practical use.

Below the present invention (the second aspect of the invention) is described according to preferred variants of its implementation with reference to the drawings. As illustrated in FIG. 81-0, a diaper 1A, which is an embodiment of a pull-on disposable diaper according to the present invention, is a pull-on disposable diaper that includes an absorbent assembly 2 in an assembly and an outer casing 3 that is located on the surface side of an absorbent assembly 2 in an assembly, not facing the skin, and on which the absorbent assembly 2 is fixed in the assembly; in which a pair of side seams 4, 4, a hole for the waist 5 and a pair of leg holes 6, 6 are formed when fastening portions of both transverse lateral edges 3F, 3F of the outer shell 3 on the front portion F, which stretch along the longitudinal direction X, with corresponding sections the transverse lateral edges 3R, 3R of the outer shell 3 in the rear portion R, which extend along the longitudinal direction X. It should be noted that the description of the diaper 1A (second aspect of the invention) mainly focuses on the description of signs that differ from the signs ysheupomyanutogo diaper 1 (the first aspect of the invention), and the same signs are accompanied by the same reference numerals in the drawings, and their explanation is omitted. An explanation of the characteristics of the diaper 1 (the first aspect of the invention), as necessary, applies to signs that are not specifically explained.

The outer shell 3 includes an elastic sheet 30 with a structure in which two sheets 31, 32 are arranged in layers. As illustrated in FIG. 9, the front and rear end portions (in the longitudinal direction X of the outer shell 3) are bent inward in the direction of the side of the surface facing the skin, and with glue, a plurality of threadlike elastic elements 51 for the waist between the two outer shells 3 are attached and fixed in tension. 3 (two elastic sheets 30, 30), which, when bent backward, are opposite each other. At the same time, assemblies are formed on the waist at the edge of the opening for the waist 5.

Side seams 4 are formed by bonding by fusing the edges of several sheets (outer sheet 31 and inner sheet 32), which form the outer shell 3, in a state where the edges are superimposed, and each side seam includes a fusion-bonded portion. From the point of view of making a less visible side seam 4 and obtaining a diaper 1A with an appearance like underwear, it is preferable that the thickness (width) 4W (see FIG. 10) of the side seam 4 (fusion-bonded portion of the side seam 4) is small. However, if it is too small, the lateral seam 4 will protrude above the surface in the form of a protrusion and can cause pain. Therefore, from the aforementioned point of view, the thickness 4W of the side seam 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 and, in particular, preferably 0.2 to 2 mm, more preferably 0.25 to 1.5 mm. An example of a method capable of bringing the thickness of 4W to the aforementioned range includes a method of forming a side seam 4 using a laser beam as a fusion and cutting device for alloying and cutting the outer shell 3 (sheets 31, 32); and fusion and cutting of the outer shell section 3, where a side seam 4 is to be formed by irradiating said section with a laser beam. The thickness of the 4W side seam can be measured by examining in an unloaded condition a cross section of the side seam in a separate diaper at magnification from 50x to 200x using a microscope (VHX-1000; Keyence product), etc. at three points that are located separately from each other in the length direction; finding the thickness of the section by measuring each cross section; and finding the average thicknesses measured at three points.

The elastic sheet 30 has a structure in which filamentary elastic filaments are attached to the surface of an extensible fibrous layer, mainly consisting of inelastic fibers. In the present embodiment, as illustrated in FIG. 4, the elastic sheet 30 includes two sheets, that is, the outer sheet 31 and the inner sheet 32, and a plurality of filiform elastic filaments 33 sandwiched between the sheets 31, 32. The structure of the elastic sheet 30 and its production method are similar to the structure and method described above . As illustrated in FIG. 9 and 10, the sheet 31 forms the outer surface (the surface of the outer shell 3 not facing the skin) of the diaper 1A, and the sheet 32 forms the inner surface (the surface of the outer shell 3 not facing the skin) of the diaper 1A.

One of the main features of the diaper 1A according to the present embodiment of the invention, which includes an outer casing 3 including an elastic sheet 30, is that on the outer end surface 40 of each side seam 4, an area 35 of closely spherical end faces assembled together areas in which the corresponding spherical end sections 34a of the numerous inelastic fibers 34 are collected close to each other, and that the end section 33a of each elastic filament 33 is within second region 35, as illustrated in FIG. 11 and 12. As illustrated in FIG. 10, on each side of the diaper 1A, there is an outer end surface 40 of each side seam 4, which is continuous along the entire length of the side seam 4 in the length direction (vertical direction in FIG. 8). At least in the wear state of the diaper 1A (a condition where the opening for the waist 5 is open), the outer end surface 40 is exposed on the outside. It should be noted that FIG. 11 and 12 are explanatory drawings schematically illustrating a region 35 of closely spherical end sections assembled in a narrow sense, and a region of closely spherical end regions assembled according to the present invention (second aspect of the invention) is not limited to the configuration illustrated in said figures.

In the present embodiment, an area 35 of closely spherical end sections assembled together is formed throughout the entire area of the outer end surface 40 of the side seam 4. In a region 35 of closely spherical end sections assembled, spherical end sections 34a, 34a that are adjacent to each other to a friend, they are joined together and combined, forming a section fused by fusion. As illustrated in FIG. 12, on the outer surface of the region 35 of closely spherical end sections assembled together, which forms the outer end surface 40 of the side seam 4, the corresponding substantially hemispherical tops of the plurality of spherical end sections 34a are arranged in a continuous line in the plane direction, and the outer surface of the region 35 represents a surface with protrusions and depressions, on which small protrusions and depressions are arranged in a continuous manner. Since the region 35 of the spherical end sections assembled close to each other is formed due to the interconnection of multiple spherical end sections 34a, gaps (not shown) are formed in the region 35 of the spherical end sections close to each other between adjacent spherical end sections 34a, 34a. Clearances do not have to be formed between all adjacent spherical end sections 34a, 34a in the region 35 of the spherical end sections assembled close together, although a very large number of gaps are formed.

As illustrated in FIG. 11, in the region 35 of the spherical end portions assembled close to each other, the corresponding end portions 33a of the elastic filaments 33 of the outer shell 3 (elastic sheet 30) from the front portion F are located at predetermined intervals therebetween in the length direction (longitudinal direction X) of the region 35 ( side seam 4), and also the corresponding end sections 33a of the elastic filaments 33 of the outer shell 3 (elastic sheet 30) from the rear portion R are located at predetermined intervals between them in the longitudinal direction X. Many the spherical end face portions 34a of the inelastic fibers 34 are arranged so that the intervals between the end portions 33a of the multiple elastic filaments 33 are filled with the spherical end portions 34a. As illustrated in FIG. 12, the end portion 33a of each elastic filament 33 is curved and rounded, and is not sharp. In the transverse direction Y, the end portion 33a of each elastic filament 33 is located essentially in the same place as the spherical end portions 34a of the inelastic fibers 34, or slightly inward (downward in FIGS. 11 and 12) in the transverse direction Y relative to the end portions 34a; and the end portions 33a essentially do not protrude outward in the transverse direction Y more than the end portions 34a. In other words, on the outer end surface 40 of the side seam 4, the end section 33a of each elastic filament 33 is located essentially in the same place as the peripheral part of the end section (i.e., in the same place as the end sections 34a of the inelastic fibers 34 or the outer the surface of the region 35 of the spherical end sections assembled close to each other) and does not protrude outward more than the peripheral part of the end section.

Due to the formation in this way on the outer end surface 40 of the side seam 4 of said region 35 of the spherical end sections assembled close to each other while touching the region 35, the pressure (by pressing) is distributed by the spherical end sections 34a of the numerous inelastic fibers 34 forming the region 35, and for example , the outer end surface is not prickly to the touch when the user wearing the diaper 1A touches the outer end surface with his finger, and such a surface with less tnostyu will cause pain. Therefore, the texture of the outer end surface 40 is improved. In addition, since elastic filaments 33 are present in the region 35 of the spherical end sections assembled close to each other and are subject to compressive forces during the wear of the diaper 1A, it is unlikely that the compressive force will decrease during the wear of the diaper, and therefore disadvantages such as the slipping of the diaper 1A while wearing is effectively eliminated.

From the point of view of more reliably providing the aforementioned effects of the region 35 of the spherical end sections assembled closely together, the diameter of the spherical end section 34a of each inelastic fiber 34 is preferably 3 μm or more, more preferably 5 μm or more, and preferably 150 μm or less more preferably 130 microns or less and, in particular, is preferably from 3 to 150 microns, more preferably from 5 to 130 microns. The diameter of the spherical end portion 34a is measured by examining the outer end surface (the surface obtained by fusion and cutting) of the side seam using a microscope at magnification from 50x to 500x; and measuring the diameter of the spherical end portions of the fibers observed on a given surface.

The above-mentioned diaper 1A can be produced, for example, according to the production method described below. A method of manufacturing a stretchable disposable diaper according to the present embodiment of the invention includes the steps of: obtaining a continuous strip of diapers by superimposing on each other a continuous portion intended to be located on the front side of the body, including the front portion F, and a continuous portion, designed to be placed with the back side of the body including the rear portion R; and the formation of a side seam 4 by fusion and cutting of a section on a continuous strip of diapers, where it is necessary to form a side seam 4; moreover, fusion and cutting is carried out in a state where the continuous strip of diapers is stretched along the direction of extension (transverse direction Y) of the elastic sheet 30 included in the continuous strip of diapers. It should be noted that with reference to an imaginary straight line (not shown) that divides the diaper 1A into two parts in the longitudinal direction X, the region of the front portion F is the front portion of the diaper shell 1A, and the region of the rear portion R is the rear portion of the diaper shell 1A. A continuous front portion of the shell is formed by lining up a plurality of sections intended to be arranged on the front side of the body in one direction (direction of movement), and a continuous rear portion of the shell is formed by lining up a plurality of sections intended to be arranged on the rear side of the body , in one direction (direction of movement).

First, as illustrated in FIG. 13, the absorbent assemblies 2 in the assembly, which are manufactured separately according to the conventional method, are spaced apart and fixed on the inner sheet 32 of the ribbon-like outer shell 3 (continuous elastic sheet 30; continuous outer shell), which is continuously fed from a roll of raw textile material (not shown ) An adhesive, such as hot-melt adhesive, is applied in advance to each absorbent assembly 2 in the assembly and / or the inner sheet 32, and each absorbent assembly 2 in the assembly is fixed to the outer shell 3 (inner sheet 32) with glue. In parallel with the placement of the absorbent assemblies 2 in the assembly, a plurality of elastic elements for the waist 51 are placed on both sides 3a, 3a of the continuous outer shell 3. The many elastic elements for the waist 51 extend along the width direction in the extended state, the elastic elements being stretched with a predetermined degree of extension. During the introduction of elastic waist elements 51 using an adhesive applicator (not shown), hot melt adhesive is continuously applied to each elastic waist element 51 continuously or intermittently.

Then, as illustrated in FIG. 13, in predetermined sections of the continuous outer shell 3, on which the absorbent nodes 2 in the assembly and the elastic elements 51 for the waist are located, form leg openings LH. This step of forming leg openings can be carried out using means similar to the conventional means used in the manufacturing methods of this type of product, such as rotary cutting machines or laser cutting machines. It should be noted that the openings for the legs can be formed before placing the absorbent nodes 2 in the assembly, and not after their placement, as in the present embodiment of the invention.

Then, the continuous outer shell 3 is folded in the width direction (a direction perpendicular to the length direction of the continuous outer shell 3) so as to overlap the region of the front portion F and the region of the rear portion R. In particular, as illustrated in FIG. 13, after fixing the waist elastic members 51 by folding inwardly both sides 3a, 3a of the continuous outer casing 3 that extend along the length direction (direction of movement MD), so as to close the elastic members 51, the outer casing 3 is folded in half with absorbent nodes 2 in the assembly in the width direction of the CD. That is, the continuous front portion of the shell including the front portion F and the continuous rear portion of the shell including the rear portion R overlap each other. The length direction (direction of movement MD (machine direction)) of the continuous outer casing 3 is equivalent to the transverse direction Y of the diaper 1A, and the width direction CD (across the machine direction) of the continuous outer casing 3 is equivalent to the longitudinal direction X of the diaper 1A. Thus, a continuous strip of diapers 10 is obtained in which a plurality of diaper predecessors (pull-on disposable diapers that do not yet have a pair of side seams 4, 4) are arranged in a continuous line in one direction (transverse direction Y).

Then, the section 4 'on the continuous strip of diapers 10 where the side seam is to be formed is fused and cut in a state where the continuous strip of diapers 10 is stretched in the length direction (direction of movement MD), forming a side seam 4. The length direction of the continuous strip of diapers 10 is a direction similar to the elastic direction of the elastic sheet 30 on a continuous strip of diapers 10 (i.e., the transverse direction Y of the diaper 1A; the direction in which the elastic filaments stretch s 33). The fusion and cutting means is not particularly limited provided that the means can melt and cut the material (s) (fibers, etc.) to form section 4 ’(elastic sheet 30), and examples of such means include: laser beams; heated cutting discs; heat sealing using known heat sealing means using overheating; and ultrasonic welding using known ultrasonic welding means using ultra-long vibration. Among the aforementioned alloying and cutting means, laser beams are particularly preferred due to the advantages that the width 4W (see FIG. 10) of the side seam 4 can be made relatively small and the side seam 4 can be made less visible from the outside.

Section 4 ’, where the lateral seam is to be formed, contains a section with an eight-layer structure in which eight sheets are layered (see Fig. 8), on the edge of the waist hole 5 and in its vicinity; and a section with a four-layer structure, in which four sheets are layered, in other areas. As illustrated in FIG. 10 and 11, the four-layer structure section consists of two sheets (outer sheet 31 and inner sheet 32) that form a single outer shell 3 (elastic sheet 30) in the front portion F; and two sheets 31, 32, which form a single outer shell 3 in the rear portion R, and is formed by arranging said four sheets in layers. On the other hand, in the eight-layer section, there are two sheets of outer shells 3 on each front portion F and each rear portion R, since during the production of the continuous strip of diapers 10, both transverse edges 3a, 3a of the continuous outer shell are folded inward so that close the elastic elements 51 for the waist, as described above (see Fig. 13), and therefore, as a result, four outer shells 3.3 are layered, and as a result, the section with an eight-layer structure is formed by arranging eight sheets 31, 32 layers.

In cases where a laser beam is used as a fusion and cutting tool, for example, when a section 4 'with a four-layer structure where a side seam is to be formed, is irradiated with a laser beam in materials (elastic filaments 33, inelastic fibers, etc.) forming sheets 31, 32 in section 4 ', heat is generated due to direct exposure to the laser beam, so such materials evaporate and escape from the section on a continuous strip of diapers. In this case, the above-mentioned materials forming a sheet in the vicinity of section 4 ’are directly heated by a laser beam and melted. As a result, the section 4 'is fused and cut, and the strip-like continuous strip of diapers 10 is cut and separated so that a single diaper precursor is separated from the continuous strip of diapers 10, and at the same time, the sections of the cut edges of the four sheets 31, 32 in the separated diaper precursor , which is formed during cutting / separation, as well as sections of the trimming edges of four sheets 31, 32 on a continuous strip of diapers 10, from which the diaper precursor is separated, are fused. The cut edges of the sheets 31, 32 are in the molten state due to the generation of heat during irradiation with the laser beam and immediately after its termination. However, after the irradiation ceases, the sections of the cut edges are easily cooled by the components of the melting and cutting device (not shown), which are in contact with the continuous strip of diapers 10 and separated by the diaper precursor, and are quickly cooled due to atmospheric air and heat transfer to the components of the device. curing. Thus, the sections of the cut edges are transformed into bonded by fusion sections, in which the materials forming the sections of the cut edges are melted and combined. The same applies when section 4’s with an eight-layer structure where a side seam is to be formed is irradiated with a laser beam, and a fusion-bonded section is formed in section 4 ’. When a fusion-bonded section is formed in one diaper 1A, one side seam is formed from a pair of side seams 4, 4. The same operation is repeated, due to which stretchable disposable diapers 1A are continuously produced, each of which includes the aforementioned outer shell 3 ( elastic sheet 30), including a pair of side seams 4, 4.

What is especially important when fusing and cutting the aforementioned continuous strip of diapers 10 is that the fusion and cutting of a continuous strip of diapers 10 (for example, a continuous strip of diapers irradiated by a laser beam) occurs when the continuous strip of diapers 10 is stretched along the elastic direction of the elastic a sheet 30 of a continuous strip of diapers 10 (i.e., in the direction of movement MD; the direction in which the elastic filaments 33 are pulled). It is necessary to fuse and cut in a state where the elastic sheet 30 (sheets 31, 32 and elastic filaments 33) is stretched to form a spherical shape of the corresponding end sections 34a of the inelastic fibers 34 on the outer end surface 40 of the side seam 4 (which are fibers entering into the composition of the outer sheet 31 and the inner sheet 32 of the elastic sheet 30 forming the outer shell 3), thereby forming a region 35 of spherical end sections assembled close to each other on the outer rtsevoy surface 40.

It is assumed that the spherical end portion 34a of the inelastic fiber 34 (see FIGS. 11 and 12) is formed as follows, provided that the fusion and cutting is carried out in a state where the elastic sheet 30 (continuous strip of diapers 10) is stretched. For example, suppose that the section 4 ’where the side seam is to be formed, when the sheet 30 is stretched, is irradiated with a laser beam, so that it is fused and cut. In this case, immediately after fusion and cutting, the corresponding end sections of the numerous fibers (inelastic fibers 34) that make up the sheets 31, 32, in the areas of the cut edges of the sheets 31, 32, which are formed as a result of fusion and cutting, are in the molten state due to the melting of the resin component, and due to surface tension, the molten resin takes a spherical shape. In addition, after fusion and cutting, sheets 31, 32 leave their stretched state and try to return to their unstretched state (natural state). Therefore, in addition to surface tension, the corresponding spherical end sections of numerous inelastic fibers in sheets 31, 32 also exert a force that returns them to an unstretched state, and as a result, the molten resin accumulates at the end sections, thereby creating a larger sphere. If a large amount of molten resin accumulates in the respective spherical end sections of the numerous inelastic fibers 34, the spherical end sections will be combined in a mass of amorphous resin (a large amount of resin). However, due to the tensile force of the numerous elastic filaments 33, which are everywhere located on the sections of the cut edges of the sheets 31, 32, the amount of molten resin that accumulates at each end portion of the inelastic fiber 34 ’does not become so large as to cause the end portions to merge; therefore, at the time when the inelastic fibers 34 return from the expanded state to the unextended state, the molten resin is cured, while the spherical shape of the end portions is maintained, and as a result, spherical end portions 34a are formed. The corresponding end sections of the inelastic fibers 34 resulting from fusion and cutting are turned into spherical end sections 34a, and as a result, an area 35 of spherical end sections assembled close to each other is formed on the outer end surface 40 of the side seam 4.

In contrast, if the elastic sheet 30 (continuous strip of diapers 10) is fused and cut in an unstretched state (natural state) without stretching, the corresponding end portions of the numerous inelastic fibers 34 resulting from fusion and cutting become temporarily spherical due to the surface tension of the molten resins; however, since the sheet 30 is in an unstretched state, and the tensile force of the elastic filament 33 does not act, a large amount of molten resin accumulates at the spherical end sections, and as a result, the end sections combine and form a large volume of amorphous resin. The molten resin cures in such a bulk state, forming a side seam. In this case, the volume of a large amount of resin, which is located on the outer end surface of the side seam thus formed, is less than the volume of the resin in the uncompressed state before fusion. Therefore, the end portion of the elastic filament 33, in all likelihood, will protrude outward from the outer end surface of the diaper, which can make the side seam prickly to the touch when touching the skin.

When fusing and cutting the aforementioned continuous strip of diapers 10, it is important to fuse and cut the continuous strip of diapers 10 in a state when it is stretched along the elastic direction of the elastic sheet 30, and it is also important to fuse and cut (for example, irradiation with a laser beam) in a state where the continuous strip diapers 10 and, in particular, the peripheral part of the section to be fused and cut (section 4 ', where it is necessary to form a side seam), is under pressure (when pressed) in the direction and thickness. Due to the fusion and cutting of the continuous strip of diapers 10 in a compressed state, the sections of the cut edges of the sheets 31, 32 formed as a result of fusion and cutting are fused more securely, and as a result, the strength of the side seam 4 when bonded by fusion is increased. From the point of view of increasing the strength of the side seam 4 during fusion bonding, it is preferable to apply pressure molding (pressing) of the continuous strip of diapers 10 not only during fusion and cutting (for example, during laser beam irradiation), but also before fusion and cutting and after him. The method of pressing under pressure a continuous strip of diapers 10 is not particularly limited, and examples include a method of winding a continuous strip of diapers 10 around a support of a predetermined shape, such as a cylindrical shape or a flat plate shape, with a predetermined tensile force applied thereto and fusing and cutting into support while maintaining the force of tension; and a method of placing a continuous strip of diapers 10 between the support and another element (pressing element).

The present invention (the second aspect of the invention) is described above in accordance with its preferred embodiments, however, the present invention is not limited to the above embodiments. For example, in the aforementioned embodiment, the outer shell consists of one elastic sheet, although the outer shell may include a multilayer structure including an elastic sheet and another sheet. In this case, for example, the elastic sheet may form the surface side of the outer shell not facing the skin, and the inelastic sheet may form the side of the surface facing the skin (the surface on which the absorbent block is fixed). In addition, as with the outer shells of stretchable disposable diapers of this type, elastic elements forming folds below the waist and elastic elements forming folds around the legs can be located on the outer shell 3 according to the aforementioned embodiment.

With regard to the above embodiments of the present invention, the following features are further disclosed.

1. A pull-on disposable diaper, comprising: an absorbent block and an outer shell that is located on the side of the surface of the absorbent block not facing the skin, and on which the absorbent block is fixed; in which a pair of side seams, a hole for the waist and a pair of holes for the legs are formed by bonding sections of both transverse side edges of the front section of the outer shell with the corresponding sections of the transverse side edges of the rear section of the outer shell, in which:

the outer sheath is formed by incorporating an elastic sheet including elastic fibers and inelastic fibers therein;

each side seam is formed by bonding by fusing a portion of the transverse lateral edge of the outer shell in the front portion with a portion of the transverse lateral edge of the outer shell in the rear portion in a state where the transverse lateral edge portion in the front portion and the transverse lateral edge portion in the rear portion are flat on each other each other, and within such a fusion bonded portion, elastic fibers are present; and

on the outer end surface of the side seam, the end section of each elastic fiber does not protrude outward more than the peripheral part of the end section.

2. A stretchable disposable diaper according to claim 1, wherein the thickness of the side seam is preferably 0.2 mm or more, more preferably 0.25 mm or more.

3. A stretchable disposable diaper according to claim 1 or 2, wherein the thickness of the side seam is preferably 2 mm or less, more preferably 1.5 mm or less.

4. A stretchable disposable diaper according to any one of paragraphs 1-3, in which:

the outer sheath is formed by incorporating a laminate therein, consisting of the aforementioned elastic sheet and an inelastic sheet that does not include elastic fibers;

the thickness of the side seam exceeds the thickness of the section, not counting the side seam, on each of the front section and the rear section, which form a side seam; and

a smooth area is formed on the outer end surface of each side seam, where the outer end surface is smooth.

5. A stretchable disposable diaper according to paragraph 4, in which:

a smooth area is formed throughout the entire area of the outer end surface of the side seam; and

the entire area of the outer end surface contains small protrusions and depressions created by the fibers that make up the outer shell (the corresponding end sections of the fibers that make up the shell), and therefore is not flat, although it is smooth.

6. A stretchable disposable diaper according to paragraph 4 or 5, in which the inelastic sheet is formed from one type of a specific material, or includes one type of a specific material in an amount that is greater than or equal to 90 wt.%, Taking into account all materials included in the inelastic sheet.

7. A stretchable disposable diaper according to claim 5, wherein the inelastic sheet is formed only of polypropylene, or the amount of polypropylene is greater than or equal to 90% by weight, taking into account all materials included in the inelastic sheet.

8. The stretchable disposable diaper according to any one of paragraphs 4-7, wherein the inelastic sheet is in the central part in the thickness direction of the side seam, and the elastic sheets are on both sides in the thickness direction so that the inelastic sheet is sandwiched between the elastic sheets.

9. A stretchable disposable diaper according to any one of paragraphs 4-7, wherein the elastic sheet is in the central part in the thickness direction of the side seam and the inelastic sheets are on both sides in the thickness direction so that the elastic sheet is sandwiched between the inelastic sheets.

10. A stretchable disposable diaper according to any one of paragraphs 4-9, wherein the inelastic sheet does not have elasticity in the longitudinal direction or transverse direction, or does not have elasticity in both directions.

11. A stretchable disposable diaper according to any one of paragraphs 1-10, in which:

the elastic fibers that make up the elastic sheet are filiform elastic filaments;

the elastic sheet has a structure in which elastic filaments are attached to the surface of an extensible fibrous layer, mainly consisting of the aforementioned inelastic fibers;

in sections of the outer shell, with the exception of the side seams, part of the inelastic fibers are fastened by fusion with elastic filaments and pressed into them; and

the end portion of each elastic filament is inside a smooth region.

12. A stretchable disposable diaper according to claim 11, wherein there is no glue between the fibrous layer and the elastic filaments attached thereto.

13. A stretchable disposable diaper according to paragraph 11 or 12, in which:

the elastic sheet as fibrous layers includes two sheets, that is, an outer sheet and an inner sheet; and

two sheets are stretchable in the same direction (transverse direction) as the direction in which the elastic filaments stretch, since the fibers that make up the fibrous layers are themselves stretchable.

14. A stretchable disposable diaper according to any one of paragraphs 11-13, wherein the fibrous layer is stretchable in the same direction (transverse direction) as the direction in which the elastic filaments stretch, since the fibers included in the fibrous layer are themselves extensible.

15. A stretchable disposable diaper according to any one of paragraphs 11-14, in which:

the elastic sheet as fibrous layers includes two sheets, that is, an outer sheet and an inner sheet; and

two sheets are stretchable in the same direction (transverse direction) as the direction in which the elastic filaments stretch, because although the fibers that make up the fibrous layers themselves are inextensible, two sheets give stretchability as a result of: (1) separation fibers that were fastened at intersection points; (2) bonding the fibers to result in a resulting structural change in the three-dimensional structure formed by the fibers, or (3) breaking the fibers included in the sheets.

16. A stretchable disposable diaper according to any one of paragraphs 11-15, in which the elastic filaments are attached to the fibrous layer in a substantially unstretched condition.

17. A stretchable disposable diaper according to any one of paragraphs 11-14, wherein the elastic filaments are formed by stretching an elastic resin in its molten or softened state.

18. A stretchable disposable diaper according to any one of paragraphs 11-17, wherein a compressive force acts on the elastic filaments in the smooth area while the diaper is being worn.

19. A stretchable disposable diaper according to any one of paragraphs 11-18, wherein the fibrous layer is brought into a tensile state by heat treatment, stretching between the rollers, stretching by engaging the teeth and grooves, or by gearing, or stretching by stretching on a wide frame.

20. A stretchable disposable diaper according to any one of paragraphs 11-19, wherein the diameter of the elastic filament is preferably 10 μm or more, more preferably 20 μm or more.

21. The stretchable disposable diaper according to any one of paragraphs 11-20, wherein the diameter of the elastic filament is preferably 200 microns or less, more preferably 130 microns or less.

22. The stretchable disposable diaper according to any one of paragraphs 11-21, wherein the step between adjacent elastic filaments (the distance between the respective centers of adjacent elastic filaments) is preferably 0.1 mm or more, more preferably 0.4 mm or more.

23. A stretchable disposable diaper according to any one of paragraphs 11-22, wherein the step between adjacent elastic filaments (the distance between the respective centers of adjacent elastic filaments) is preferably 5 mm or less, more preferably 1 mm or less.

24. A stretchable disposable diaper according to any one of paragraphs 1-10, wherein elastic fibers and inelastic fibers are mixed in the elastic sheet.

25. The stretchable disposable diaper according to paragraph 24, wherein the elastic fiber is a fiber formed from a polymer including a thermoplastic polyurethane elastomer.

26. A stretchable disposable diaper according to any one of paragraphs 1-25, wherein a region of spherical end sections assembled close together is formed on the outer end surface of each side seam, in which corresponding spherical end sections of inelastic fibers are collected close together.

27. The stretchable disposable diaper according to paragraph 26, wherein in the region of the spherical end portions assembled close to each other, the spherical end portions that are adjacent to each other are joined together and are combined to form a fusion-bonded portion.

28. A stretchable disposable diaper according to paragraph 26 or 27, in which:

on the outer surface of the region of spherical end sections assembled close to each other, which forms the outer end surface of the side seam, the corresponding essentially hemispherical tops of the numerous spherical end sections are arranged in a continuous line in the plane direction; and the outer surface of the region is a surface with protrusions and depressions on which the small protrusions and depressions are arranged in a continuous manner.

29. A stretchable disposable diaper according to any one of paragraphs 1-28, in which each side seam is formed using the step of fusing and cutting a continuous strip of diapers, which is obtained by laying on top of each other a continuous section, designed to be located on the front side of the body, in which front sections, each of which includes the aforementioned front section, is lined up in a continuous line in one direction (direction of movement), and a continuous section intended for position with the rear side of the body, wherein the plurality of sections intended for location at the rear side of the body ,, each of which includes the aforementioned rear portion, built in a continuous line in one direction (displacement direction); moreover, fusion and cutting of a continuous strip of diapers is carried out in a state where the continuous strip of diapers is stretched along the direction of extension of the elastic sheet included in the continuous strip of diapers.

30. A stretchable disposable diaper according to any one of paragraphs 1-28, wherein each side seam is formed using the fusion and cutting step of a continuous strip of diapers, which is obtained by superimposing on each other a continuous portion intended to be located on the front side of the body, in which a plurality of front sections, each of which includes the aforementioned front section, is lined up in a continuous line in one direction (direction of movement); and a continuous portion intended to be arranged on the rear side of the body, in which a plurality of portions intended to be arranged on the rear side of the body, each of which includes the aforementioned rear portion, is lined up in a continuous line in one direction (direction of movement), wherein fusion and cutting a continuous strip of diapers is carried out without stretching the continuous strip of diapers.

31. A stretchable disposable diaper according to any one of claims 1-30, wherein the tensile strength at tearing of the side seam is preferably 10 N or more, more preferably 13 N or more.

32. A stretchable disposable diaper according to any one of paragraphs 1-31, wherein the tensile strength at tearing of the side seam is preferably 75 N or less, more preferably 70 N or less.

33. A stretchable disposable diaper according to claim 30, wherein the side seam is formed using a laser beam as a fusion and cutting means; and fusion and cutting of the section on a continuous strip of diapers where a side seam is to be formed, is carried out by irradiating said section with a laser beam.

34. A method of manufacturing a stretchable disposable diaper according to any one of paragraphs 1-28, wherein the production method includes the steps of:

obtaining a continuous strip of diapers by superimposing on each other a continuous portion intended for location on the front side of the body including the aforementioned front portion and a continuous portion intended for location on the back side of the body including the aforementioned rear portion; and

the formation of a side seam by fusing and cutting a section on a continuous strip of diapers, where a side seam is to be formed, the fusion and cutting being carried out in a state where the continuous strip of diapers is stretched along the stretching direction of the elastic sheet included in the continuous strip of diapers.

35. A method of manufacturing a stretchable disposable diaper according to any one of paragraphs 1-28, wherein the production method comprises the steps of:

obtaining a continuous strip of diapers by stacking on top of each other a continuous section, designed to be located on the front side of the body, including the front section, and a continuous section, designed to be located on the back side of the body, including the rear section; and

the formation of the side seam by fusing and cutting the section on a continuous strip of diapers, where it is necessary to form a side seam, and fusion and cutting is carried out without stretching the continuous strip of diapers.

36. A method of manufacturing a stretchable disposable diaper according to paragraph 34 or 35, in which:

a laser beam is used as a fusion and cutting means; and

a section on a continuous strip of diapers where a side seam is to be formed is fused and cut by irradiating said section with a laser beam.

37. A method of manufacturing a stretchable disposable diaper according to any one of paragraphs 34-36, wherein the fibrous layer is extensible by heat treatment, stretching between the rollers, stretching by engaging the teeth and grooves or by gearing, or by stretching on a tenter frame.

38. A method of manufacturing a stretchable disposable diaper according to any one of paragraphs 34-37, wherein the fibrous layer before attaching the elastic filaments in itself in the form of a starting textile material is not stretchable.

39. A stretchable disposable diaper according to paragraph 29 or 30, wherein when fusing and cutting a continuous strip of diapers, fusion and cutting (for example, irradiation with a laser beam) is carried out in a state where the peripheral part of the section to be fused and cut (the section where the lateral is to be formed seam), is pressed under pressure (pressing) in the direction of thickness.

40. A method of manufacturing a stretchable disposable diaper according to any one of paragraphs 1-3, 11-23 and 26-29, the production method comprising the steps of:

for obtaining a continuous strip of diapers by superimposing on each other a continuous section intended to be arranged on the front side of the body, in which a plurality of sections intended to be arranged on the front side of the body, each of which includes the front section, is lined up in a continuous line in one direction (direction of movement), and a continuous section intended for location on the rear side of the body, in which a plurality of sections intended for location on the rear side of the body each of which includes the rear section, lined up in a continuous line in one direction (direction of movement); and

the formation of a side seam by fusion and cutting of a section on a continuous strip of diapers where a side seam is to be formed, the fusion and cutting being carried out in a state where the continuous strip of diapers is stretched along the elastic direction of the elastic sheet included in the continuous strip of diapers.

41. A method of manufacturing a stretchable disposable diaper according to paragraph 40, wherein:

a laser beam is used as a fusion and cutting means for fusing and cutting a continuous strip of diapers; and

the section where the side seam is to be formed is fused and cut by irradiating said section with a laser beam.

42. A method of manufacturing a stretchable disposable diaper according to paragraph 40 or 41, in which when fusing and cutting a continuous strip of diapers, fusion and cutting (eg, irradiation with a laser beam) is carried out in a state where the peripheral part of the section to be fused and cut (section where to form a side seam), is pressed under pressure (pressing) in the direction of thickness.

43. A method of manufacturing a stretchable disposable diaper according to any one of paragraphs 34-42, wherein the fibrous layer is extensible by heat treatment, stretching between the rollers, stretching by engaging the teeth and grooves or by gearing, or by stretching on a tenter frame.

44. A method of manufacturing a stretchable disposable diaper according to any one of paragraphs 34-43, wherein prior to attaching the elastic filaments, the fiber layer itself is not in the form of a starting textile material.

45. A method of manufacturing a stretchable disposable diaper according to any one of paragraphs 34-44, wherein the elastic filaments are formed by stretching an elastic resin in its molten or softened state.

Examples

Below the present invention (the first aspect of the invention) is further described in detail using examples. However, the present invention is not limited to the following examples.

Example A1

A pull-on disposable diaper with a basic structure, the same as the diaper 1 illustrated in FIG. 1-3 were prepared according to the production method illustrated in FIG. 6. An absorbent block from a commercially available stretchable disposable diaper (product of Kao Corporation; product of the brand "Hatsuratsu Ultra-thin Underpants, Just Like Underwear") was used as an absorbent block. As the elastic sheet included in the outer shell, the following elastic sheet A was used with a structure similar to that of the elastic sheet 30 illustrated in FIG. 4. As a non-elastic sheet, a non-woven material of the "spunbond" type with a bulk of 18 g / m ² , consisting of elementary PP fiber, was used. The outer shell had a three-layer structure, including an elastic sheet A (the innermost layer), an inelastic sheet (intermediate layer) and an elastic sheet A (the outermost layer), arranged in order, starting from the side of the diaper surface facing the skin. In the manufacture of the diaper of Example A1, a laser beam was used as a fusion and cutting means for fusing and cutting a continuous strip of diapers, and a side seam was formed by fusing and cutting a section on a continuous strip of diapers where a side seam should be formed by irradiating said section with a laser beam, wherein the fusion and cutting was performed under the condition where a continuous strip of diapers has been stretched along the direction stretchable elastic (resilient) sheet a, an incoming part of a continuous strip of diapers. The laser beam was irradiated using a device having a structure similar to that of the laser fastening device described in Patent Literature 3. A CO ₂ laser was used as the laser beam, the laser output power was 24 W, the spot diameter was 0.3 mm, and 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 the value found by dividing the energy of the irradiating laser beam by the area of the irradiated area, and the energy density is calculated according to the following formula (1). In formula (1), P is the laser output (W), ϕ is the spot diameter (mm) of the laser beam on the sheet to be fused and cut (on a continuous strip of diapers), and v is the scanning speed of the laser beam (mm / from).

Stretch Sheet A

According to the manufacturing method illustrated in FIG. 7, produced elastic sheetAwith a structure in which elastic filaments are sandwiched and held between two fibrous layers of the same type, consisting of inelastic fibers (the percentage of inelastic fibers is 100 wt.%). In the manufacture of elastic sheet A by the method illustrated in FIG. 7, a composite including elastic filaments sandwiched and held between two sheets is elasticized by passing through an elasticity device (exhaust device) including a pair of gear / groove rollers, such as a pair of gear / groove rollers 64, 65 on which teeth and grooves are alternately formed in the circumferential direction (in the direction of the perimeter), thereby obtaining an elastic sheetA. In elastic sheetA numerous elastic filaments are arranged parallel to each other at predetermined intervals between them.

Elastic filament: styrene-based thermoplastic elastomer; fiber diameter: 110 microns.

The bulk of the elastic filament: 10 g / m ² .

Fibrous layer: non-woven material of the type "spunbond" with a bulk of 18 g / m ² , consisting of elementary PP-fiber (inelastic fiber; fiber thickness: 3.5 dtex).

The bulk of the elastic sheet A : 46 g / m ² .

Example A2

A stretchable disposable diaper was prepared according to Example A1, except that instead of elastic sheet A , the following elastic sheet B was used . It should be noted that in the manufacture of the diaper of Example A2 during folding and placement of the elastic sheet B (in the manufacture of the continuous strip of diapers 10), the fibrous layer including the PP fiber as an inelastic fiber (“single fiber layer” described below) , was a layer that was placed on another layer.

Stretch Sheet B

According to the manufacturing method illustrated in FIG. 7, the elastic sheet B produced with a structure in which the elastic filaments are clamped and held between the fibrous layers of two different types, each of which consists of non-elastic fibers (percentage of non-elastic fibers of 100 wt.%). In the manufacture of the elastic sheet B , which is illustrated in FIG. 7, a composite comprising elastic filaments sandwiched and held between two sheets is elasticized by passing through an elasticity device (exhaust device) including a pair of gear / groove rollers, such as a pair of gear / groove rollers 64, 65 on which teeth and grooves are alternately formed in the circumferential direction (along the perimeter), thereby obtaining an elastic sheet B. In the elastic sheet B, numerous elastic filaments are arranged parallel to each other at predetermined intervals between them.

Elastic filament: styrene-based thermoplastic elastomer; fiber diameter: 110 microns.

The bulk of the elastic filament: 10 g / m ² .

One fibrous layer: non-woven material of the "spanbond" type with the main mass of 18 g / m ² , consisting of elementary PP-fiber (inelastic fiber; fiber thickness: 3.5 dtex).

Other fibrous layer: non-woven fabric obtained by air packing, with a bulk of 20 g / m ² , consisting of bicomponent fiber core-sheath type PET (core) / PE (sheath) (non-elastic fibers; fiber thickness: 3.0 dtex )

The bulk of the elastic sheet B: 48 g / m ² .

Example A3

A stretchable disposable diaper was prepared according to Example A1, except that instead of the elastic sheet A , the following elastic sheet C was used .

Stretch Sheet C

The elastic sheet C was obtained by peeling the sheet of the outermost layer from a commercially available Unicharm Corporation Lifree Slim Wear Water-absorbent Underwear product by heating the layer with a hairdryer and melting hot-melt adhesive.

Example for comparison A1

A stretchable disposable diaper was prepared according to Example A1, except that only the elastic sheet was used as the outer shell forming member and the non-elastic sheet was not used.

Example for comparison A2

A stretchable disposable diaper was prepared according to Comparative Example A1, except that instead of elastic sheet A , elastic sheet B was used .

Example for comparison A3

A stretchable disposable diaper was prepared according to Comparative Example A1, except that instead of elastic sheet A , elastic sheet C was used .

A4 comparison example

A stretchable disposable diaper was prepared according to Example A1, except that in the manufacture of the diaper, instead of fusing and cutting with a laser beam, thermal bonding was used using means for heating and pressing under pressure (a heating roller device) and mechanical cutting of a thermally bonded section (pressed section) with using a cutting tool and using the aforementioned tools formed a side seam.

Rating

For each of the diapers, the tensile strength at tearing of the side seam according to the method described above was evaluated by examples and examples for comparison, and the texture of the side seam was evaluated according to the method described below. The results are shown below in table 1.

Side seam texture

Five members of the working group participating in the test touched the outer end surface of the side seam of the diaper, evaluating the texture of the side seam with their index finger, and evaluated the texture by touch according to the following evaluation criterion. The term “prickly” referred to in the following evaluation criteria is described below. The average value of the assessment (in points) of the five members of the working group participating in the test was taken as the result of the evaluation of the diaper.

Criterion for evaluating the texture of the side seam

5: not prickly

4: not that prickly

3: can't say

2: pretty scratchy

1: prickly

Table 1 Example Example for comparison A1 A2 A3 A1 A2 A3 A4 The structure of the layers of the outer shell The innermost layer (surface side facing the skin) Elastic Sheet A Elastic sheet B Stretch Sheet C Elastic Sheet A Elastic sheet B Stretch Sheet C Elastic Sheet A Intermediate layer Inelastic sheet Inelastic sheet Inelastic sheet _ _ _ Inelastic sheet The outermost layer (surface side not facing the skin) Elastic Sheet A Elastic sheet B Stretch Sheet C _ _ _ Elastic Sheet A A method of forming a side seam (a method of cutting and separating a continuous strip of diapers) Laser fusion and cutting Laser fusion and cutting Laser fusion and cutting Laser fusion and cutting Laser fusion and cutting Laser fusion and cutting Cutting after
heating and pressing under pressure Continuous diaper strip condition (outer sheath) when cutting / separating Stretched condition Stretched condition Stretched condition Stretched condition Stretched condition Stretched condition _ Side Seam Thickness (mm) 0.40 0.63 0.43 0.41 0.34 0.16 0.15 The thickness of the section on the outer shell, not counting the side seam (mm) 0.35 0.50 0.34 0.23 0.32 0.16 1.00 Rating Tear strength of the side seam (N) 45.70 15,80 30.90 7.46 2.27 9.40 48,20 Side seam texture (maximum score: 5 points) 3.0 3,7 3.0 2.9 3.0 3,5 2,3

As can be seen from table 1, in each of the examples, the side seam had high tear strength and had bond strength sufficient for practical use; however, the degree of scratchiness of the side seam was minimal and the texture was excellent. It is assumed that in each example, a smooth region is formed on the outer end surface of the side seam, where essentially the entire region of the outer end surface is smooth. In contrast, in comparative examples A1-A3, an outer shell was formed comprising only an elastic sheet and not including an inelastic sheet, and the tensile strength at tearing of the side seam was insufficient compared to examples where the outer shell included inelastic sheet. It is assumed that in the comparison examples A1 – A3, the formation of the above smooth area did not occur on the outer end surface of the side seam. In the comparison example A4, since the side seam was formed by heating and pressing, the thickness of the side seam was less than the thickness of the sections, not counting the side seam (i.e., the thickness of the non-bonded side sections) in each of the front section and the rear section, of which consists of a side seam. Therefore, the end section of the side seam was sharp and the side seam to the touch was much more scratchy, as a result, the side seam had a poor texture compared to examples where the thickness of the side seam was greater than the thickness of the non-bonded side sections.

Below the present invention (the second aspect of the invention) is further described in detail using examples. However, the present invention is not limited to the following examples.

Example B1

A pull-on disposable diaper with a basic structure, the same as the diaper 1A illustrated in FIG. 8-10 were obtained according to the production method illustrated in FIG. 13. As an absorbent block, an absorbent block from a commercially available pull-on disposable diaper (product of Kao Corporation; product of the brand "Hatsuratsu Ultra-thin Underpants, Just Like Underwear") was used. As an elastic sheet, which is part of the outer

sheaths, the aforementioned elastic sheet A was used with a structure similar to that of the elastic sheet 30 illustrated in FIG. 4. In the manufacture of the diaper of Example B1, a laser beam was used as a fusion and cutting tool for fusing and cutting a continuous strip of diapers, and a side seam was formed by fusing and cutting a section on a continuous strip of diapers, where the side seam should be formed by irradiating the said section with a laser beam, and fusion and cutting was carried out in a state where a continuous strip of diapers was stretched along the direction of stretching of the stretchable (elastic) sheet A included into a continuous strip of diapers. The laser beam was irradiated using a device having a structure similar to that of the laser fastening device described in Patent Literature 3. A CO ₂ laser was used as the laser beam, the laser output power was 24 W, the spot diameter was 0.3 mm, and 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 the value found by dividing the energy of the irradiating laser beam by the area of the irradiated region, and the energy density is calculated according to the above formula (1).

Example B2

A stretchable disposable diaper was prepared according to Example B1, except that instead of the elastic sheet A , the aforementioned elastic sheet B was used . It should be noted that in the manufacture of the diaper of Example B2 during folding and placement of the aforementioned elastic sheet B (in the manufacture of a continuous strip of diapers), the fibrous layer including the PP fiber as an inelastic fiber (the “single fiber layer” described above) was a layer that was placed on another layer.

Example for comparison B1

A stretchable disposable diaper was prepared according to Example B1, except that during melting and cutting of a continuous strip of diapers using a laser beam in the manufacture of the diaper, a continuous strip of diapers was melted and cut in an unstretched state (without stretching).

B2 comparison example

A stretchable disposable diaper was prepared according to Example B2, except that during melting and cutting of a continuous strip of diapers using a laser beam in the manufacture of the diaper, a continuous strip of diapers was melted and cut in an unstretched state (without stretching).

Side seam texture rating

The five members of the working group participating in the test concerned the outer end surface of the side seam of each diaper,

obtained by examples and examples for comparison, with your index finger, and at the same time evaluated the texture to the touch according to the above "Criterion for evaluating the texture of the side seam". The average value of the assessment (in points) of the five members of the working group participating in the test was taken as the result of the evaluation of the diaper. The result was that the diaper rating of Example B1 was 2.9 and the diaper rating of Example B2 was 3.0, which meant that the degree of prickiness due to the side seams of the diapers in both examples was minimal. In contrast, the diaper score of Comparison Example B1 was 1.1, and the diaper score of Comparison Example B2 was 1.4, which meant that the side seams were significantly more prickly to the touch. As for the diapers according to the examples, it is assumed that since in the production of the diaper the side seam was formed by fusing and cutting a continuous strip of diapers in its extended state, the aforementioned region was formed over the entire area of the outer end surface of the side seam from spherical end sections , and therefore the degree of scratching was minimal. In contrast, with regard to diapers in the examples for comparison,

it is assumed that since the side seam was formed by fusing and cutting a continuous strip of diapers in an unstretched state, on the outer end surface of the side seam, the aforementioned region did not form from the spherical end sections collected close to each other, and therefore the degree of prickiness due to the side seam was significant.

Industrial applicability

According to the present invention (the first aspect of the invention), it is possible to provide a stretchable disposable diaper with an appearance similar to underwear that is not prickly to the touch, which is less likely to cause pain if the side seam is touched by hand, and the side seam of which is easily torn when the diaper is removed . As used herein, “prickly” to the touch refers to a sensation (pain) that usually occurs when a protruding object is touched by a hand or finger, and which, for example, is a sensation (pain) that occurs when the object is smaller than the tip finger, or pointed object has a sharp end that is touched by the tip of the finger. Examples of protruding objects in the side seam of the pull-on disposable diaper that may be causing this degree of scratching include hardened patches of resin that solidify after melting; areas of resin that formed on the protrusions during pressing during heat sealing; and relatively sharp, protruding sections of the resin formed by sharp cutting of the above sections of the resin.

Also, according to the present invention (the second aspect of the invention), it is possible to provide a stretchable disposable diaper with an appearance similar to underwear, despite the presence of side seams, and not prickly to the touch, which is less likely to cause pain if the side seam is touched by hand.

Claims (54)

1. A stretchable disposable diaper comprising: the absorbent block and the outer shell, which is located on the side of the surface of the absorbent block, not facing the skin, and to which the absorbent block is attached; however, a pair of side seams, a hole for the waist and a pair of holes for the legs are formed by connecting sections of both side edges of the outer shell in the front section with the corresponding sections of the side edges of the outer shell in the rear section, while: the outer sheath comprises an elastic sheet including elastic fibers and inelastic fibers; each side seam is formed by fusing a portion of the side edge of the outer shell in the front portion with a portion of the lateral edge of the outer shell in the rear portion in a state where the side edge portion in the front portion and the side edge portion in the rear portion are flat on top of each other, and inside the fusion joint contains elastic fibers; the thickness of the side seam exceeds the thickness of the section, not counting the side seam, on each of the front section and the rear section, which form a side seam; and on the outer end surface of the side seam, the end portion of each elastic fiber does not protrude outward more than the peripheral portion of the end portion of the outer end surface. 2. A stretchable disposable diaper according to claim 1, wherein the thickness of the side seam is 0.2 mm or more. 3. A stretchable disposable diaper according to claim 1, wherein the seam thickness is 2 mm or less. 4. A stretchable disposable diaper according to claim 1, in which: the outer shell comprises a laminate of an elastic sheet and an inelastic sheet that does not include elastic fibers; a smooth area is formed on the outer end surface of each side seam in which the outer end surface is smooth; and a smooth region is formed by coating the respective end portions of the fibers that make up the outer shell with resin obtained from the material forming the outer shell. 5. A stretchable disposable diaper according to claim 4, in which the inelastic sheet is formed from one type of a given material or includes one type of a specified material in an amount that exceeds or equal to 90 wt.% Of all materials forming an inelastic sheet. 6. A stretchable disposable diaper according to claim 4, wherein the inelastic sheet is located in the central part of the side seam in the thickness direction and on both sides in the thickness direction there is an elastic sheet so that the inelastic sheet is located in the middle. 7. The stretchable disposable diaper according to claim 4, wherein the elastic sheet is located in the central part of the side seam in the thickness direction and on both sides in the thickness direction there is an inelastic sheet so that the elastic sheet is in the middle. 8. A stretchable disposable diaper according to claim 4, in which: the elastic fibers that make up the elastic sheet are filiform elastic filaments; the elastic sheet has a structure in which elastic filaments are attached to the surface of an extensible fibrous layer, mainly consisting of inelastic fibers; in sections of the outer shell, with the exception of the side seams, part of the inelastic fibers are fused with elastic filaments and immersed in them; and the end portion of each elastic filament is inside a smooth region. 9. A stretchable disposable diaper according to claim 8, wherein there is no adhesive between the fibrous layer and the elastic filaments bonded to the fibrous layer. 10. A stretchable disposable diaper according to claim 8, in which the elastic sheet as fibrous layers contains two sheets, which include an outer sheet and an inner sheet; and two sheets are stretchable in the same direction as the direction in which the elastic filaments stretch, since the fibers that make up the fibrous layers are themselves stretchable. 11. A stretchable disposable diaper according to claim 8, in which the fibrous layer is stretchable in the same direction as the direction in which the elastic filaments stretch, since the fibers that make up the fibrous layer are themselves stretchable. 12. The stretchable disposable diaper according to claim 8, in which the elastic filaments are attached to the fibrous layer in a substantially unstretched state. 13. A stretchable disposable diaper according to claim 8, in which the elastic filaments are formed by stretching an elastic resin in its molten or softened state. 14. A stretchable disposable diaper according to any one of paragraphs. 1-7, in which elastic fibers and inelastic fibers are mixed in an elastic sheet. 15. The stretchable disposable diaper according to claim 14, wherein the elastic fiber is a fiber formed from a polymer including a thermoplastic polyurethane elastomer. 16. A stretchable disposable diaper according to claim 1, in which on the outer end surface of each side seam is formed a region of spherical sections collected close to each other, in which the corresponding spherical end sections of inelastic fibers are collected close to each other. 17. A stretchable disposable diaper according to claim 16, wherein in the region of the spherical sections collected adjacent to each other, the spherical end sections that are adjacent to each other are joined together and combined to form a melted joint. 18. The stretchable disposable diaper according to claim 16, wherein on the outer surface of the region of spherical sections assembled next to each other, which forms the outer end surface of the side seam, the corresponding substantially hemispherical vertices of the numerous spherical end sections are arranged in a continuous line in a planar direction; and the outer surface of the region is a surface with protrusions and depressions on which the small protrusions and depressions are arranged in a continuous manner. 19. The stretchable disposable diaper according to claim 1, in which each side seam is formed using the step of fusing and cutting a continuous strip of diapers, which is obtained by stacking on top of each other a continuous section, designed to be located on the front side of the body, in which there are many sections intended for location on the front side of the body, each of which includes the front section, is lined up in a continuous line in one direction, and a continuous section intended for I am on the back side of the body, in which many areas intended for location on the back side of the body, each of which includes the back section, are arranged in a continuous line in one direction, moreover, the fusion and cutting of a continuous strip of diapers is carried out in a state where a continuous strip diapers stretched along the direction of stretching of the elastic sheet, which is part of a continuous strip of diapers. 20. The stretchable disposable diaper according to claim 1, in which each side seam is formed using the step of fusing and cutting a continuous strip of diapers, which is obtained by stacking on top of each other a continuous section, designed to be located on the back side of the body, in which there are many sections intended for location on the front side of the body, each of which includes the front portion, lined up in a continuous line in one direction, and a continuous portion intended for location on the back side of the body, in which many areas intended for location on the back side of the body, each of which includes the back section, are arranged in a continuous line in one direction, moreover, fusion and cutting of a continuous strip of diapers is carried out without stretching the continuous strip of diapers. 21. A stretchable disposable diaper according to claim 20, in which the side seam is formed using a laser beam as a fusion and cutting means; and fusion and cutting of the section on a continuous strip of diapers where a side seam is to be formed, is carried out by irradiating said section with a laser beam. 22. A method of manufacturing a stretchable disposable diaper according to claim 1, wherein the production method comprises the steps of: obtaining a continuous strip of diapers by stacking on top of each other a continuous section, designed to be located on the front side of the body, in which many sections intended to be placed on the front side of the body, each of which includes the front section, are lined up in a continuous line in one direction, and a continuous portion intended for location on the rear side of the body, in which a plurality of portions intended for location on the rear side of the body, each of which includes self back section, lined up in a continuous line in one direction; and the formation of a side seam by fusing and cutting a section on a continuous strip of diapers, where a side seam is to be formed, the fusion and cutting being carried out in a state where the continuous strip of diapers is stretched along the stretching direction of the elastic sheet included in the continuous strip of diapers. 23. A method of manufacturing a stretchable disposable diaper according to claim 1, wherein the production method comprises the steps of: obtaining a continuous strip of diapers by superimposing on each other a continuous portion intended for location on the front side of the body including the front portion, and a continuous portion intended for location on the rear side of the body including the rear portion; and the formation of a side seam by fusing and cutting a section on a continuous strip of diapers, where it is necessary to form a side seam, and fusion and cutting is carried out without stretching a continuous strip of diapers. 24. A method of manufacturing a stretchable disposable diaper according to claim 22 or 23, in which: a laser beam is used as a fusion and cutting means for alloying and cutting a continuous strip of diapers; and the section where the side seam is to be formed is fused and cut by irradiating said section with a laser beam. 25. A method of manufacturing a stretchable disposable diaper according to claim 22 or 23, in which the fibrous layer before attaching elastic filaments in itself in the form of the original textile material is not stretchable. 26. A stretchable disposable diaper according to claim 19 or 20, wherein when fusing and cutting a continuous strip of diapers, fusion and cutting is performed in a state where the peripheral part of the section to be fused and cut is pressed in the thickness direction. 27. A method of manufacturing a stretchable disposable diaper according to claim 1, wherein the production method comprises the steps of: obtaining a continuous strip of diapers by stacking on top of each other a continuous section, designed to be located on the front side of the body, in which many sections intended to be placed on the front side of the body, each of which includes the front section, are lined up in a continuous line in one direction, and a continuous portion intended for location on the rear side of the body, in which a plurality of portions intended for location on the rear side of the body, each of which includes self back section, lined up in a continuous line in one direction; and the formation of a side seam by fusing and cutting a section on a continuous strip of diapers, where a side seam is to be formed, the fusion and cutting being carried out in a state where the continuous strip of diapers is stretched along the stretching direction of the elastic sheet included in the continuous strip of diapers. 28. A method of manufacturing a stretchable disposable diaper according to claim 27, in which: a laser beam is used as a fusion and cutting means for fusing and cutting a continuous strip of diapers; and the section where the side seam is to be formed is fused and cut by irradiating said section with a laser beam. 29. A method of manufacturing a stretchable disposable diaper according to claim 27, wherein when fusing and cutting a continuous strip of diapers, fusion and cutting is carried out in a state where the peripheral part of the section to be fused and cut is pressed in the thickness direction. 30. A method of manufacturing a stretchable disposable diaper according to claim 22 or 23, wherein before attaching the elastic filaments, the fibrous layer itself is not tensile in the form of a starting textile material. 31. A method of manufacturing a stretchable disposable diaper according to claim 22 or 23, wherein the elastic filaments are formed by stretching the elastic resin in its molten or softened state.

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