RU2639962C2 - Trunks-shaped disposable diaper - Google Patents

Abstract

FIELD: human vital needs satisfaction.SUBSTANCE: elastic elements (51a, 51b) are disposed in the front portion (F) and the rear portion (R) by attachment thereto in the stretched state by means of an adhesive. The end part (52a, 52b) of the elastic element (51a, 51b) and the part near the end part are painted so that they have a colour different from the background colour of the front (F) or rear (R) portion. The end part (52a, 52b) of each elastic element (51a, 51b) does not reach the side seam position (4) and, thus, a region (9a, 9b) not containing elastic elements is formed between the side seam (4) and the end part (52a, 52b) of each elastic element (51a, 51b). In the region (9a, 9b) not containing elastic elements, no adhesive is provided to join the elastic elements (51a, 51b).EFFECT: increased wearing convenience.29 cl, 12 dwg

Description

FIELD OF THE INVENTION

[0001] The present invention provides a pull-on disposable diaper.

State of the art

[0002] Traditionally, stretchable disposable diapers are widely used, including a crotch portion in which the absorbent member is located, as well as a front portion and a back portion that extend from the crotch portion, respectively, toward the front side and the rear side of the wearer, with a pair of side seams , a waist hole and a pair of leg holes are formed when the left and right side edges of the front portion are joined with the corresponding left and right transverse side edges of the rear TKA. As a rule, elastic elements are attached to the front section and the rear section and are fixed in such a stretched state.

[0003] In stretchable disposable diapers, the side seams are often made wide due to the manufacturing process. However, such wide lateral seams are the reason for the deterioration of the appearance of the diaper, and in particular, as a rule, prevent the diaper from giving an appearance similar to underwear. Thus, it is desirable to produce a side seam having the smallest possible width. However, reducing the width of the side seam typically reduces the visibility of the side seam, and thus typically reduces the level of comfort during side seam rupture.

[0004] In addition, reducing the width of the side seam, as a rule, reduces the strength of the connection, which can cause the loss of elastic elements that are fixed in the side seam. To prevent the loss of elastic elements, it is effective to change the position of the end part of each elastic element and move it inward with respect to the side seam in the transverse direction, as well as firmly securing each end part in this internal position.

[0005] For example, Patent Documents 1 and 2 describe well-known conventional technologies, according to which the end portion of the elastic element is not located in the side seam. Patent Document 1 describes a stretchable absorbent article in which a part with a modified tensile strength is located inside with respect to each side seam in the front section and the rear section of the diaper; and no continuous elastic element is located between the part with the changed tensile strength and the side seam. Patent Document 2 describes that elastic elements located below the waist that are present in the lower portion of the stretchable disposable diaper need not be present along the entire length in the direction of the circumference of the body, but should only be present in some parts in the direction of the circumference of the body.

List of references

Patent Literature

[0006] Patent Document 1: Japanese Patent Application No. 2011-234847 A

Patent Document 2: Japanese Patent Application No. 2012-249943 A

SUMMARY OF THE INVENTION

[0007] However, the aforementioned patent documents do not address a problem associated with a deterioration in the visibility of the side seam, which typically occurs in cases where a narrow width of the side seam is made.

[0008] The present invention provides a stretchable disposable diaper which comprises: a crotch portion; the front section, which is located in front of the crotch area; and a back portion that extends from the crotch portion; and a pair of side seams formed by connecting both edge parts of the sides of the front portion with corresponding edge parts of the sides of the rear portion. The pull-on disposable diaper has a longitudinal direction that corresponds to the anteroposterior direction of the user, and a transverse direction that is perpendicular to the longitudinal direction.

Each side seam includes a fusion-connected portion that extends continuously in the longitudinal direction of the diaper, and virtually no unconnected portion is present in a section located externally with respect to the fusion-connected portion in the transverse direction of the diaper.

Numerous elastic elements in the stretched state are located in each section, representing the front section or the rear section, and are attached to the front section and the rear section by adhesive.

At least the end part of the elastic element, which is located near the side seam, and the part near the end part, are painted so that they have a color that differs from the background color of the front section or the rear section in which this elastic element is located.

The end portion of both end parts of at least some of the elastic elements that are located close to the side seam do not reach the position of the side seam and end at a point located inside with respect to the side seam in the transverse direction, and thus not containing of elastic elements, a region is formed between the side seam and the end portion of each of these elastic elements.

In the area not containing elastic elements, no adhesive is present for bonding the elastic elements.

Brief Description of the Drawings

[0009] FIG. 1 is a perspective view schematically illustrating a pull-on disposable diaper according to an embodiment of the present invention.

FIG. 2 is a plan view schematically illustrating the diaper illustrated in FIG. 1, in its open uncompressed state.

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

FIG. 4 is a side view illustrating a state in which the diaper illustrated in FIG. 1, is wearing.

FIG. 5 is a partially cut-away perspective view schematically illustrating an elastic sheet used as the outer covering of a diaper illustrated in FIG. one.

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

FIG. 7 is a perspective view illustrating a device suitably used to form the side seams of the diaper illustrated in FIG. one.

FIG. 8 (a) to 8 (c) are explanatory diagrams showing how side seams are formed while cutting and separating a continuous web of diapers by using the apparatus illustrated in FIG. 7.

FIG. 9 is an image (corresponding to FIG. 8 (c)) illustrating yet another example of a method for manufacturing a pull-on disposable diaper by using the device illustrated in FIG. 7.

FIG. 10 is a schematic diagram illustrating other sheets that can be suitably used as the outer covering of the diaper illustrated in FIG. one.

Description of Embodiments

[0010] The present invention is described below according to its preferred embodiments with reference to the drawings. As illustrated in FIG. 1-3, a diaper 1, which is a pull-on disposable diaper according to an embodiment of the present invention, the draw-on disposable diaper comprising: an absorbent member 2; and an outer cover 3 that is located on the non-skin side of the surface of the absorbent element 2, and to which the absorbent element 2 is attached; 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 connecting both edge parts 3F, 3F of the sides of the outer cover 3 in the front portion F, which extend in the longitudinal direction X, with corresponding edge parts 3R, 3R of the sides of the outer cover 3 in the rear portion R, which extend in the longitudinal direction X.

[0011] In a plan view in which the diaper 1 is in its open uncompressed state, as illustrated in FIG. 2, the diaper 1 has a longitudinal direction X, which corresponds to the anteroposterior direction of the user, and a transverse direction Y, which is perpendicular to the longitudinal direction X. The diaper 1 has a crotch portion M which is located in the crotch portion of the user when the diaper is put on, the front portion F which is located in front of the crotch portion M in the anteroposterior direction of the user, and the rear portion R, which is located behind the crotch portion M in the per dnezadnem direction of the user. The crotch portion M is a region where recesses for forming the corresponding leg openings 6, 6 are formed in respective edge portions of the sides in the longitudinal direction X.

[0012] It should be noted that, as used herein, a “skin-facing surface” is the surface of a disposable diaper or its constituent elements (such as an absorbent element 2) that faces the wearer's skin when the disposable diaper is worn while “Non-skin surface” is the surface of the disposable diaper or its constituent elements, which is directed in the opposite direction relative to the skin of the user when the disposable diaper is over Eva (i.e. towards clothing). The “longitudinal direction X” (i.e., the direction of length) is the direction of the long sides of the disposable diaper or absorbent element 2, which is its constituent element, while the “transverse direction Y” is the transverse direction of the disposable diaper or absorbent element 2, which is its constituent element.

[0013] As illustrated in FIG. 2, the absorbent element 2 has a longitudinally elongated shape that is relatively elongated in one direction (longitudinal direction X), and includes: a face sheet 21 that forms a surface facing the skin; the back sheet 22, which forms a surface not facing the skin; and a liquid-retaining absorbent material 23 arranged so that it is between the two sheets 21, 22. The absorbent material 23 has a shape that is elongated in a direction that is the longitudinal direction X. The absorbent element 2 is attached to the center section of the outer coating 3 in a known manner (for example, by means of adhesive) so that the longitudinal direction of the absorbent element 2 corresponds to the longitudinal direction X of the diaper 1 in its open uncompressed state (given th state illustrated in FIG. 2).

[0014] As the face sheet 21, the back sheet 22, and the absorbent material 23, which constitutes the absorbent element 2, it is possible to use various materials that are traditionally used in the technical field to which the present invention relates, without particular limitation. For example, with respect to the front sheet 21, it is possible to use a liquid-permeable sheet, such as sheets of various nonwoven webs that are hydrophilized, or a porous film. As for the back sheet 22, it is possible to use impervious to liquids or water-repellent material. Examples of liquid impervious materials that can be used include: polymer films; microporous moisture-permeable polymer films; and the multilayer materials that make up the polymer films and nonwoven webs. Examples of water-repellent materials that can be used include: multilayer composite nonwoven webs, such as spunbond / meltblown / spunbond nonwoven webs; spunbond nonwoven fabrics; fused nonwoven webs; and breathable non-woven fabrics. As for the absorbent material 23, it is possible to use a material that contains an absorbent core made of water absorbent polymer particles and a fibrous material such as cellulosic fiber. The absorbent core may cover the core wrapping sheet, such as tissue paper.

[0015] As illustrated in FIG. 2, the side cuffs 24, 24, each of which is liquid resistant / water-repellent and breathable sheet material, are located on the respective side sides of the absorbent element 2, which extend in the longitudinal direction X. Each side cuff 24 rises due to compression of the side elastic elements 25 of the cuff which are stretched along the free edge of the side cuff, and as a result, the fluid is prevented from exiting in the transverse direction Y. In the present description The term “open uncompressed state” means a state in which the side seams 4 open, bringing the diaper into an open (expanded) state, and the elastic elements in different parts of the open diaper are stretched so that the diaper is expanded, acquiring its predetermined size (a size that has a diaper in a flattened flat state, in which the effect of elastic elements completely disappears).

[0016] The outer coating 3 includes an elastic sheet 30 having a two-layer structure, which are two sheets 31, 32. As illustrated in FIG. 2, the longitudinal front portion and the longitudinal rear end portions of the outer cover 3, which includes the elastic sheet 30, are folded back toward the skin side of the surface, and the plurality of thread-like front elastic elements for the waist 51a and the rear elastic elements for the waist 51b are connected and fixed in the stretched state by adhesive between two outer coatings 3, 3, which are two elastic sheets 30, 30, which are located opposite each other when bent back. At least both end regions of each elastic element for the waist 51a, 51b are connected and fixed by adhesive, and preferably each elastic element for the waist is connected and fixed by adhesive throughout its length in its longitudinal direction. Thus, assemblies are formed for the waist along the open end portion of the hole for the waist 5.

[0017] The side seams 4 are formed by connecting together the two edge parts of the outer sheet 31 and the inner sheet 32, which make up the outer cover 3, in a state in which the edge parts overlap, and each side seam includes a fused joint part 40, as illustrated in FIG. 3. The fusion-coupled portion 40 is formed by fusion-bonding the outer cover 3 constituting the front portion F with the outer coating 3 constituting the rear portion R in a state in which the corresponding edge portions overlap. The fusion-bonded portion 40 extends continuously in the longitudinal direction X of the diaper 1. The term “fusion-bonded th” means that the outer coating 3, which contains the thermoplastic polymer, is joined in its molten state.

[0018] In the side seam 4 having the fusion-connected portion 40, the unconnected parts are practically absent in the section external to the fusion-connected portion 40 in the transverse direction Y of the diaper 1. This provides a useful effect to improve the appearance of the diaper 1. The term “practically absent ”not only means that the unconnected part in the section is completely absent from the outside with respect to the fused joint part 40 in the transverse direction Y, but also allows the presence of the unconnected part having having a very small width (for example, 1 mm or less), which inevitably forms due to variability and other factors in relation to the manufacturing conditions of the side seams.

[0019] Besides the fact that there is practically no unconnected part in the side seam 4, it is preferable that the thickness T1 of the side seam is small (see Fig. 3). By reducing the thickness T1 of the side seam, this side seam 4 becomes less noticeable, and the diaper 1 can take on an appearance resembling that of underwear. However, if the thickness T1 is excessively small, the joint strength of the side seam may become insufficient, and the side seam 4 may undesirably tear while wearing the diaper 1. From the above point of view, the thickness T1 of the side seam 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 more specifically, preferably from 0.2 mm to 2 mm inclusive, more preferably from 0.25 mm to 1.5 mm inclusive. The thickness of the side seam T1 can be measured by observing in an unloaded condition the cross section of the side seam of one diaper when magnified from 50-fold to 200-fold using a VHX-1000 microscope manufactured by Keyence, etc., at three separate points at longitudinal direction; determination of the thickness of the section, measured in each cross section; and calculating the average thicknesses measured at three points.

[0020] A preferred method for manufacturing side seams having the aforementioned shape is described in detail below.

[0021] As described above, by making the less visible side seam 4, the diaper 1 can acquire an appearance resembling underwear. However, making a less visible side seam 4 typically reduces the convenience level of tearing the side seam 4 during removal of the diaper 1. Thus, the diaper according to the present invention has a structure designed to increase the level of comfort during tearing of the side seam 4. More specifically, how illustrated in FIG. 4, an end portion 52a, 52b located near the side seam 4 of both end parts of each of the elastic elements for the waist 51a, 51b, which are located along the open end portion of the waist hole, does not reach the position of the side seam 4 and ends at a point located inside relative to the side seam 4 in the transverse direction Y. Thus, a region 9a, 9b not containing elastic elements is formed between the side seam 4 and the end portion 52a, 52b of each of these elastic elements for the waist 51a, 51b. The elastic-free regions 9a, 9b are formed in each of the front portion F and the rear portion R of the diaper 1 so that a side seam 4 is located between them. Each elastic-free region 9a, 9b is formed only in the longitudinal upper region of the side seam 4 .

[0022] In the elastic-free region 9a, 9b, there is no adhesive for attaching elastic elements for the waist 51a, 51b to the backwardly bent portion of the outer cover 3. In other words, in the elastic-free region 9a, 9b there is no elastic element for the waist 51a , 51b, and also there is no adhesive. As a result, an assembly is not formed in the elastic-free region 9a, 9b due to compression of the elastic elements for the waist 51a, 51b, and when the diaper 1 is worn, the elastic-free region 9a, 9b retains the flat sheet shape of the outer cover 3. On the other side, in the areas located inside in the transverse direction Y with respect to the area 9a, 9b not containing elastic elements, elastic elements for the waist 51a, 51b are attached in an extended state to the outer coating 3 by means of adhesive 11a, 11b, and thus assemblies are formed due to compression of the elastic elements for the waist 51a, 51b. Since no assembly is formed in the elastic region 9a, 9b, the position of the side seam 4 is easily visible. In addition, the thickness of the elastic-free region 9a, 9b is small, while the thickness in the regions located inside in the transverse direction Y with respect to the elastic-free region 9a, 9b is large. Thus, the torn area can be easily detected by touch sensation. It should be noted that, as illustrated in FIG. 4, in regions located inside in the transverse direction Y with respect to regions 9a, 9b containing elastic elements, adhesive 11a, 11b is applied periodically in the longitudinal direction X of the diaper 1 at the positions where the elastic elements 51a, 51b are located.

[0023] In the elastic-free region 9a, 9b, an assembly is not formed and no adhesive is applied. Thus, when the diaper 1 is measured from the outside of the outer cover 3, the lightness of the non-elastic region 9a, 9b is different from the lightness of other regions, in particular, the lightness of the region adjacent to the elastic region 9a, 9b. Lightness can be expressed, for example, as the value of L in the color representation system L-a-b. The value of L is in the range from 0 to 100, and the larger the numerical value, the higher the lightness. To measure the value of L, artificial skin is placed under the measured section. Artificial leather has a low L value and dark color; thus, the lightness L1 of the elastic region-free region 9a, 9b, i.e., the region in which there are no assemblies, takes on a low value, and thus the region appears dark, since artificial skin can be observed through this region. On the other hand, the lightness L2 in the region in which the assemblies are formed, and which is the region adjacent to the elastic-free regions 9a, 9b, takes on a high value, and thus the region looks bright because the assemblies cover the artificial skin. Thus, the ratio L2 / L1 of the luminosity L1 of the elastic-free region 9a, 9b and the luminosity L2 of the region adjacent to the elastic-free region 9a, 9b is more than 1. For this reason, a tearing region of different lightness can be easily detected visually. In addition, due to the synergy between this difference in lightness and the aforementioned tactile difference, the torn area can be detected even more easily. The aforementioned L2 / L1 ratio is preferably 1.02 or more, more preferably 1.04 or more, and preferably 1.3 or less, more preferably 1.25 or less, and more specifically, preferably from 1.02 to 1.3 inclusive more preferably 1.04 to 1.25 inclusive. The value L of lightness is measured as follows. The diaper 1 is stretched 1.6 times or 2.6 times in the Y direction as a measurement sample, and in particular in the case of an adult diaper, this diaper is stretched in the Y direction to a circumference of 60 cm or 100 cm, by using as the base points, the end part from the inside, in the transverse direction Y, of each of the left and right side seams 4. Then, imitation leather (product of Beaulax Co., Ltd. under the name Bio Skin Plate, number P001-001; color No. 10 ) is placed on the inside of the diaper 1. Spectral di differential colorimeter is placed in tight contact with the outer side of the diaper 1 without leaving any space between the differential colorimeter section and measured in the diaper 1 in such a way that does not receive any external color. As the spectral differential colorimeter, for example, NF 333 portable spectral differential colorimeter manufactured by Nippon Denshoku Industries Co., Ltd. can be used. According to the present embodiment, it is preferable that the L2 / L1 ratio is more than 1 in one of the cases or in both cases, when the diaper 1 is stretched 1.6 times or stretched 2.6 times in the Y direction. Stretch is 1, 6 times, as a rule, corresponds to the degree of stretching in the state in which the diaper is worn by a user having a minimum size within the range of acceptable sizes of the diaper. 2.6 times stretching typically corresponds to the degree of stretching in the state in which the diaper is worn by a user having a maximum size within the range of acceptable diaper sizes.

[0024] In addition, in order to further improve the visibility of the side seam 4 according to the present invention in at least one of the front portion F and the rear portion R, at least the end portion 52a, 52b of the elastic member for the waist 51a, 51b , which is located near the side seam 4, and the part near the end part is painted so that they have a color that differs from the background color of the front section F or the rear section R, in which this elastic element is located for the waist 51a, 51b. Thus, in addition to the difference in lightness between the region 9a, 9b not containing elastic elements and regions located inside in the transverse direction Y relative to region 9a, 9b containing elastic elements, the difference in contrast between these regions also becomes apparent, and due to the synergy between these differences torn area can be detected even more easily. For example, at least the end portion 52a of the front elastic element for the waist 51a, which is located in the front portion F, and the part near the end part (preferably the entire region of the front elastic element for the waist 51a) are painted so that they have a color that differs from the background color of the outer cover 3 constituting the front portion F. On the other hand, with regard to the rear portion R, at least the end portion 52b of the rear elastic element for the waist 51b, which is located in the rear portion R, and h close to the end portion (or the entire area of the rear elastic element for the waist 51b) can be painted or not so that they have a color that differs from the background color of the outer cover 3 constituting the rear portion R. In this case, the elastic elements for the waist 51a, 51b, which are painted in such a way that they have a color that differs from the background color of the front portion F or the rear portion R, are visible when viewed from the outside of the diaper 1, i.e., are visible through the outer cover 3 which holds T located inside the waist elastic members 51a, 51b.

[0025] From the point of view of further improving the visibility of the side seam 4, the color difference between the color of the elastic element for the waist 51a, 51b and the background color of the outer cover 3, which is expressed as the difference between the outer coating value a and the elastic element value a, is preferably 10 or more preferably 15 or more.

[0026] In addition, from the point of view of further improving the visibility of the side seam 4, it is preferable that the color of the front elastic element for the waist 51a, which is located in the front section F, is different from the color of the rear elastic element for the waist 51b, which is located in the rear section R. In addition to the fact that the respective colors of the elastic elements 51a, 51b are different from each other, it is preferable that the colors of the elastic elements differ from the background color of the outer coating 3.

[0027] The elastic sheet 30 constituting the aforementioned outer coating 3 has a structure in which filamentary elastic fibers are attached to the surface of an extensible fibrous layer, which are mainly non-elastic fibers. According to the present embodiment, as illustrated in FIG. 5, the elastic sheet 30 includes two sheets, including an outer sheet 31 and an inner sheet 32, and multiple filamentous elastic fibers 33 located between the sheets 31, 32. Each of the sheets 31, 32 is a “stretchable fibrous layer which constitute mainly inelastic fibers ”(although inelastic fibers are not illustrated in FIG. 5). The percentage of inelastic fibers in each of the sheets 31, 32, which mainly comprise inelastic fibers, is preferably 90 wt.% Or more and more preferably 91 wt.% Or more, and it can be 100 wt.%. As illustrated in FIG. 2 and 3, the sheet 31 forms the outer surface of the diaper 1, and the sheet 32 forms the inner surface of the diaper 1. The elastic fibers 33 extend in the transverse direction Y of the diaper 1. Although not illustrated in FIG. 1 and 2, the elastic fibers 33 are at least in the diaper 1 region below the waist, and they are preferably in the entire region in the longitudinal direction X of the diaper 1. The elastic fibers 33 are present in a substantially unstretched state.

[0028] Both sheets (outer sheet 31 and inner sheet 32) are stretchable. The sheets 31, 32 are extensible in the transverse direction Y, which is the direction in which the elastic fibers 33 extend. Here, the term “extensible” extends to (a) cases in which the constituent fibers of the sheets 31, 32 themselves are extensible; and (b) cases in which the constituent fibers themselves are not extensible, but sheets 31, 32 are generally extensible, for example, as a result of the separation of fibers that were joined at the points of intersection, bonding and other binding of the fibers and resulting structural changes in the three-dimensional structure formed by the fibers, or rupture of the constituent fibers.

[0029] The outer sheet 31 and the inner sheet 32 can be extensible in their original textile state before joining the elastic fibers 33. Alternatively, the sheets 31, 32 can be sheets that are not stretch in their original textile state before joining the elastic fibers 33, but become extensible by processing so that they become extensible after bonding elastic fibers 33. Examples of specific methods for imparting extensibility to the sheets are terms eskaya processing, stretching between rolls, stretching by engagement between the teeth and the recesses or between the gears, and tensile strain via tensioning frame. For the purposes of the preferred method of manufacturing the elastic sheet 30, which is described in detail below, it is preferable that the sheets 31, 32 are not extensible in their original textile state, from the point of view that the ability to move sheets 31, 32 is improved during the fusion process of elastic fibers 33 to sheets 31, 32.

[0030] The outer sheet 31 and the inner sheet 32 are stretchable and practically inelastic. Here, the term “elastic” means a characteristic of the possibility of stretching and contraction after the disappearance of the tensile force. Sheets 31, 32 do not have this characteristic. If the sheets 31, 32 are elastic, the sheets must contain fibers comprising an elastic polymer as their constituent fibers. However, fibers comprising an elastic polymer typically exhibit stickiness, which can degrade the texture of the nonwoven fabric. Thus, according to the present embodiment, the sheets 31, 32 are practically inelastic, which prevents texture deterioration.

[0031] Elastic fibers 33 are formed by stretching the elastic polymer in its molten or softened state, as described in detail below. The multiple elastic fibers 33 are substantially continuous throughout the entire length of the elastic sheet 30, that is, throughout the entire length of the outer cover 3 in the transverse direction Y. The multiple elastic fibers 33 are arranged so that they extend in the same direction, i.e. in the transverse direction Y, and as a result of this, they do not intersect with each other. It should be noted that, according to the present invention, an unintentional intersection of the elastic fibers 33 is allowed, caused by the inevitable variability of the manufacturing conditions of the elastic sheet 30. The elastic fibers 33 can run in a straight line, or they run in a tortuous manner, provided that they do not intersect with each other.

[0032] As described above, the elastic fibers 33 are attached to the outer sheet 31 and the inner sheet 32 in a substantially unstretched state. Since the elastic fibers 33 are not stretched, the elastic sheet 30 has the advantage that there is no relaxation (creep) that causes the stretching, and that the elasticity does not deteriorate after processing, such as stretching, and during storage of the original textile material obtained as a result of joining the elastic fibers 33 into sheets 31, 32. In addition, there is no deformation in the folded starting textile material. If, for example, elastic fibers 33 are attached to sheets 31, 32 after stretching twice with respect to their original length, and then the fibers return to a state in which their length is 1.3 times the original length, then from this state of the fiber can only be stretched to 1.7 times the original length. On the other hand, the advantage of joining the elastic fibers in an unstretched state is that it becomes possible to stretch to the extent that the sheets 31, 32 can stretch, or to the maximum degree of stretching of the elastic fibers 33, since the initial state for stretching the elastic sheet is different from the above case.

[0033] The diameter of the elastic fiber 33 is not limited in a specific way, but from the point of view of balancing the texture of the elastic sheet 30 and the ability to produce elastic fibers 33, their diameter is preferably 10 μm or more and more preferably 20 μm or more, and preferably 200 μm or less and more preferably 130 microns or less, and more specifically, preferably from 10 to 200 microns inclusive, and more preferably from 20 to 130 microns inclusive.

[0034] The cross section of the elastic fiber 33 may be round, but in some cases it may be elliptical. For example, in cases where the elastic sheet 30 is manufactured according to the method described in Japanese Patent Application No. 2008-17912 A, which is the preferred method for manufacturing the elastic sheets, the cross section of the elastic fibers 33 is typically elliptical. In such cases, it is preferable in the elastic sheet 30 to arrange the elastic fibers 33 so that the main axis of the elliptical shape extends in the same direction as the plane direction of the elastic sheet 30, and the minor axis extends in the same direction as the thickness direction of the elastic sheet 30.

[0035] From the point of view of giving the elastic sheet 30 sufficient elasticity and excellent texture close to the fabric texture, the spacing between adjacent elastic fibers 33, 33 (ie, the distance between the respective centers of adjacent elastic fibers) 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 more specifically, preferably from 0.1 to 5 mm inclusive and more preferably from 0.4 to 1 mm inclusive, provided that the diameter is elastic th fiber 33 is in the above range.

[0036] In the elastic sheet 30, numerous elastic fibers 33 are attached to the outer sheet 31 and the inner sheet 32 along their entire length. Here, the term “attach along their entire length” does not require that all fibers (constituting fibers in sheets 31, 32) in contact with elastic fibers 33 are attached to elastic fibers 33, but means that elastic fibers 33 and constituent fibers (inelastic fibers) of the sheets 31, 32 are connected so that in the elastic fibers 33 there are no undesirably formed unconnected sections. Since the elastic fibers 33 are attached to the sheets 31, 32 throughout their length, the force for attaching the elastic fibers 33 to the sheets 31, 32 can increase sufficiently. As a result, the elastic fibers 33 are less prone to peeling from the sheets 31, 32, even if the elastic sheet 30 is stretched and lengthened. If the elastic fibers 33 peel off from the sheets 31, 32, gaps will be formed between the elastic fibers 33 and the sheets 31, 32 in their natural state (relaxation state), and the formation of wrinkles in the elastic sheet 30, which will disturb the sense of integrity of the entire elastic sheet 30, is likely. .

[0037] In the elastic sheet 30, some of the many inelastic fibers that are contained in the outer sheet 31 and the inner sheet 32 are fused to and hidden in the elastic fibers 33. All or some of the inelastic fibers that exist on the periphery of each elastic fiber 33 may be hidden in the elastic fiber 33. Here, the term “hidden” means a state in which, at the intersection of the inelastic fiber and the elastic fiber 33, a portion of the inelastic fiber existing at the point intersection, immersed in the part of the elastic fiber 33 existing at this intersection. Thus, a state in which the corresponding surfaces of the inelastic fiber and the elastic fiber 33 are connected to each other along a line or at a point is not considered to be “hidden” according to the present invention. In addition, from the point of view of improving the bond strength between the inelastic fibers and the elastic fibers 33, it is preferable that the inelastic fiber is hidden in the elastic fiber 33 to such an extent that it is more than or equal to half the diameter of the fiber.

[0038] Since the elastic fibers 33 and the inelastic fibers that are contained in the outer sheet 31 and the inner sheet 32 are joined in the aforementioned state, the bond strength between the elastic fibers 33 and the sheets 31, 32 is increased, and peeling is less likely to occur between the elastic fibers and sheets when the elastic sheet 30 is stretched. As a result of this, when the elastic sheet 30 is stretched, the sheets 31, 32 are stretched with good sensitivity according to the stretching of the elastic fibers 33, thereby providing a useful effect in that the elastic sheet 30 is imparted with excellent elasticity. In addition, since the elastic fibers 33 and the inelastic fibers that are contained in the sheets 31, 32 are connected in the aforementioned state, the elastic fibers 33 are in close contact with the sheets 31, 32, and thus the thickness differences between sections become less noticeable. where elastic fibers 33 are present, and in sections where they are absent, thus providing the beneficial effect that the elastic sheet 30 is imparted with an excellent texture.

[0039] By manufacturing the elastic sheet 30 according to the method described in Japanese Patent Application No. 2008-17912 A, which is the preferred method of manufacturing the elastic sheet 30, a “state in which inelastic fibers are fused to elastic fibers 33 and are hidden is obtained in them. ” According to this manufacturing method, no heat acts on the sheets 31, 32, but the elastic fibers 33 that are obtained by melt spinning are fused to the sheets 31, 32 before the elastic fibers solidify. Thus, only the fibers that are on the periphery of the elastic fibers 33 are connected to the elastic fibers 33, and the fibers that are located further retain the texture of the sheet 31, 32, thus providing the advantage of maintaining an excellent texture of the elastic sheet 30.

[0040] As described above, in the elastic sheet 30, bonding of the elastic fibers 33 to the sheets 31, 32 is achieved by fusing the fibers (inelastic fibers) constituting the sheets 31, 32 to the elastic fibers 33 in the state in which they are latent in the elastic fibers 33; therefore, bonding is not achieved by using an adhesive such as a hot-melt adhesive. Thus, no adhesive is present between the sheets 31, 32 (stretchable fibrous layers, consisting mainly of inelastic fibers) and elastic fibers 33 connected to them.

[0041] The elastic sheet 30 is elastic in a direction that represents the direction (transverse Y direction) in which the elastic fibers 33 extend. The elasticity of the elastic sheet 30 is ensured by the elasticity of the elastic fibers 33. When the elastic sheet 30 stretches and lengthens in the same direction, as the direction in which the elastic fibers 33 extend, these elastic fibers 33 and the sheets 31, 32 are stretched. When the stretching / extension of the elastic sheet 30 is stopped, the elastic fibers 33 are compressed, and in accordance with this compression, the sheets 31, 32 return to their state that existed before they were stretched and extended. Furthermore, in the elastic sheet 30, there are no other elastic fibers connected in a state perpendicular to the elastic fibers 33, and thus, when the elastic sheet 30 is stretched and elongated in the transverse direction Y, which is a direction, in which the elastic fibers 33 pass, the elastic sheet 30 is stretched, and so-called “transverse shrinkage" rarely occurs, in which the elastic sheet 30 is reduced in the transverse direction Y.

[0042] The materials from which the elastic sheet 30 is formed will be described below. Inelastic fibers, which are substantially inelastic, are used as the fibers constituting the outer sheet 31 and the inner sheet 32 (extensible fibrous layers consisting mainly of inelastic fibers), and corresponding specific examples are the fibers that make up polyethylene (PE) polypropylene (PP), polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), and polyamides. The fibers constituting the sheets 31, 32 may be short fibers or long fibers, and they may be hydrophilic or water repellent. In addition, conjugated fibers, such as those containing core and cladding fibers or containing parallel constituent fibers, split fibers having a modified fiber cross-section, corrugated fibers or shrink fibers, can be used. Individual fibers of the same type may be used, or fibers of two or more types may be used in combination.

[0043] Each sheet (outer sheet 31 and inner sheet 32) may be a non-woven fabric that consists of continuous fibers 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 webs consisting of short fibers. Exemplary non-woven webs are breathable non-woven webs, thermally laminated non-woven webs, hydro-woven non-woven webs, spunbond non-woven webs and melt-woven non-woven webs. Sheet 31 and sheet 32 may be of the same type, or they may be of different types. Here, “sheets of the same type” means sheets in which, for example, are the same processes for the manufacture of sheets, the types of constituent sheets of fibers, the diameter and length of the constituent fibers, the thickness and surface density of the sheets. If one or more of these conditions are different, then the sheets are “sheets of various types”.

[0044] It is preferred that the constituent fibers (inelastic fibers) in each of the outer sheet 31 and the inner sheet 32 include at least two components, including a low-melting component and a high-melting component. In such cases, the constituent fibers are connected to each other at respective intersection points by fusion bonding of at least the fusible component. An exemplary preferred core and cladding fiber conjugate consisting of at least two components, including a low melting component and a refractory component, is a fiber in which the core is a high melting point PET or PP and the clad is a low temperature melting PET, PP or PE. The use of such conjugated fibers is particularly preferred since the fusion bond with the elastic fibers 33 becomes strong and the likelihood of delamination between them is also reduced.

[0045] The thickness of each of the outer sheet 31 and the 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 more particularly preferably from 0.05 to 5 mm inclusive, and more preferably 0.1 to 1 mm inclusive. The thickness of each sheet can be determined by first placing the measured sheet between the flat plates under a load of 0.5 cN / cm ² ; observation of the cross section of this sheet with magnification from 50 times to 200 times with a Keyence VHX-1000 microscope or similar device at three separate points in the longitudinal direction of one diaper and measuring the thickness of each cross section; and calculating an average thickness value measured at three points. Furthermore, in terms of texture, thickness and aesthetics of the structure, the surface density 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 preferred 30 g / m ² or less, and more specifically, preferably from 3 to 100 g / m ² inclusive, and more preferably from 5 to 30 g / m ² inclusive.

[0046] From the point of view of elasticity, texture, thickness and cost, the surface density of the numerous elastic fibers 33 located between the sheets 31, 32 (the surface density of the elastic fiber layer) is preferably 3 g / m ² or more and more preferably 4 g / m ² or more, and preferably 30 g / m ² or less and more preferably 15 g / m ² or less, and more specifically, preferably from 3 to 30 g / m ² inclusive and more preferably from 4 to 15 g / m ² inclusive.

[0047] The material for elastic fiber 33 is, for example, a thermoplastic elastomer or rubber. In particular, by using a thermoplastic elastomer as a material, it becomes possible to spin from the melt using an extruder, as is the case with conventional thermoplastic polymers. Furthermore, the elastic fibers obtained as a result of this can easily be fused, and thus are suitable for the elastic sheet 30. Exemplary thermoplastic elastomers are 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 (elastomers based on ethylene-α-olefin copolymers or elastomers based on propylene copolymers containing ethylene, butene, octene, etc.); polyester elastomers; and polyurethane based elastomers. One elastomer of the same type can be used individually, or two or more types of elastomers can be used in combination. In addition, conjugate fibers consisting of the aforementioned polymers that form the core and cladding or parallel components can be used.

[0048] The distinguishing characteristics described in Japanese Patent Application No. 2008-17912 are appropriately applied as distinctive characteristics with respect to the elastic sheet 30, which is not the sheets described above.

[0049] As described above, each elastic fiber 33 extends along the entire length of the diaper 1 in the transverse direction Y, and thus the end portion of each elastic fiber 33 reaches the side seam 4. Thus, the elastic fibers 33 are present in the aforementioned elastic elements of the area 9a, 9b. However, the elastic fibers 33 are not bonded and are not fixed by adhesive, and thus, the elastic fibers 33 do not constitute a purpose for which the presence / absence of the region 9a, 9b not containing elastic elements is determined. Only elastic elements that are bonded by adhesive represent a purpose for which the presence / absence of the region 9a, 9b of the elastic element is not determined.

[0050] The diaper 1 according to the present embodiment may be suitably manufactured, for example, using the manufacturing method described below. The manufacturing method of the diaper 1 according to the present embodiment includes the following steps: obtaining a multilayer continuous outer coating by applying a continuous outer coating on the side of the front portion F and a continuous outer coating on the side of the rear portion R; and the formation of the side seam 4 by melting and cutting out the section, in a multilayer continuous outer coating, where the side seam 4 should be formed.

[0051] First, as illustrated in FIG. 6, the absorbent elements 2, which are manufactured separately using the conventional method, are periodically positioned and fixed on the inner sheet 32 of the continuous outer coating 3 (continuous elastic sheet 30; ribbon-shaped outer coating), which continuously comes from the spool of the original textile material (not illustrated in the drawings). An adhesive, such as a hot-melt adhesive, is applied in advance to each absorbent element 2 and / or inner sheet 32, and each absorbent element 2 is attached to the outer coating 3 (inner sheet 32) by adhesive. Parallel to the arrangement of the absorbent elements 2, numerous elastic elements for the waist 51a, 51b are located on both sides 3a, 3a of the continuous outer cover 3 and extend in the transverse direction (in the processing direction MD) in a stretched state, where the elastic elements are stretched to a predetermined degree of stretching. During the introduction of the elastic elements for the waist 51a, 51b, hot-melt adhesive is applied continuously or periodically throughout the length of each elastic element for the waist 51a, 51b by means of an adhesive applicator (not illustrated in the drawings). However, it should be noted that the application of the adhesive is controlled so that the elastic elements for the waist 51a, 51b are not attached to either the outer sheet 31 or the inner sheet 32 in section 110C, where a side seam is to be formed, which will be described later.

[0052] Next, as illustrated in FIG. 6, leg openings LH are formed in predetermined sections of the continuous outer cover 3 in which the absorbent elements 2 and elastic elements for the waist 51a, 51b are located. This step of forming leg openings can be carried out using devices similar to traditional devices that are used in the manufacturing methods of products of these types, such as rotating knives or laser knives. It should be noted that the leg openings may be formed before the location of the absorbent elements 2, but not after their location according to the present embodiment.

[0053] Next, the continuous outer cover 3 is folded in the transverse direction (a direction perpendicular to the longitudinal direction of the continuous outer cover 3) so that the side of the front portion F and the side of the rear portion R overlap each other. More specifically, as illustrated in FIG. 6, after fixing the elastic elements for the waist 51 by folding back both sides 3a, 3a of the continuous outer cover 3, which extend in the longitudinal direction (direction of movement or machine direction MD), so that they cover the elastic elements 51, the outer cover 3 folds in half, together with absorbent elements 2, in the transverse direction CD. Thus, the continuous outer coating on the side of the front portion F and the continuous outer coating on the side of the rear portion R overlap each other. The longitudinal direction (direction of movement or machine direction MD) of the continuous outer cover 3 corresponds to the transverse direction Y of the diaper 1, and the transverse direction CD (perpendicular to the machine direction) of the continuous outer cover 3 corresponds to the longitudinal direction X of the diaper 1. Thus, a continuous web of diapers 110 ( multilayer continuous outer covering), in which numerous blanks of diapers (stretchable disposable diapers, which are not yet available ara side seams 4, 4) are arranged continuously in one direction (transverse direction Y).

[0054] Next, the continuous web of diapers 110 is melted and cut in section 110C where a side seam is to be formed, and as a result, a side seam 4 is formed. FIG. 7 illustrates a laser melting / cutting device 120, which is suitably used to form side seams 4. By using this device 120, it is possible to successfully form side seams 4, in which virtually no unconnected part is present in a section located outside with respect to fusion-connected portion 40 in the transverse direction Y, and in which the side seam 4 has a small thickness.

[0055] This method of forming a side seam 4 by using a laser fusion / cutting device 120 illustrated in FIG. 7 represents a method for forming side seams 4, each of which includes a fusion joint portion 40 (see FIG. 3) made by fusion bonding of both edge portions of the sides of the front portion F of the outer cover 3 with the corresponding edge portions of the sides of the rear portion R the outer coating 3 in a state in which the edge parts overlap, moreover:

at least some of the sheets constituting the outer coating 3 include a polymeric material; and

the manufacturing method includes the step of forming a fusion-connected part 40, on which the following is carried out: production of one surface of the multilayer sheet in which both edge parts of the sides of the front portion F of the outer coating 3 and the corresponding edge parts of the sides of the rear portion R of the outer coating 3 overlap, pressing against the supporting an element that has a translucent section through which the laser beam can pass; and irradiation, from the side of the support member through the translucent section, of the multilayer sheet which is in a compressed state, by laser radiation which has such a wavelength that it is absorbed by the sheets constituting the multilayer sheet and which causes the sheets to produce heat; and thus cutting and separating the multilayer sheet and, at the same time, fusing the cut edge parts in a compressed outer coating 3 that was formed by the above cutting / separation. This method is described below with reference to FIG. 7.

[0056] As illustrated in FIG. 7, the laser coupler 120 comprises: a hollow cylindrical roller 123, which is rotated in the direction of arrow A and which has a cylindrical (annular) support member 121; an irradiating head 135, which is located in the hollow section of the support element 121 and which emits a laser beam 130; and a belt-type pressure device 126, which includes an endless pressure belt 124 (pressure element) serving as a pressure device, and multiple rollers 125a, 125b, 125c that rotate in a state in which the pressure belt 124 connects the rollers. The laser coupler 120 includes a tension adjusting mechanism (not illustrated in the drawings) that can increase / decrease and adjust the tension of the pressure strip 124, which extends above the outer peripheral surface of the annular support member 121 (peripheral surface section of the cylindrical roller 123). By adjusting the tension, the pressure applied to the continuous web of diapers 110 (multilayer sheet) by the support member 121 and pressure band 124 can be adjusted as necessary. The continuous web of diapers 110 is the starting material for the manufacture of diapers 1 according to the present embodiment and is made in such a way that the multiple diapers 1 are aligned continuously in the transverse direction Y. In this continuous web of diapers 110 in the section 110C to be cut / separated and in the surrounding regions the elements for the waist 51a, 51b are not attached to the outer cover 3 and are in an unconnected state.

[0057] The support member 121 forms a peripheral surface section (a section that is pressed against the workpiece of the cylindrical roller 123, and is clamped and fixed between the pair of annular frame members 122, 122, and corresponding left and right edge portions of the sides of the cylindrical roller 123 are formed. The support element 121 is, for example, one annular element having the same length as the circumference of the annular frame elements 122, and it is made of a metal material such as iron, aluminum, not zhaveyuschaya steel or copper, or a refractory material such as ceramic material.

[0058] The support member 121 has translucent sections through which a laser beam can pass. The support member 121 has, as translucent sections, slit-like openings 127 that pierce the support member 121 in the thickness direction. Each hole 127 is rectangular in a plan view, and multiple holes 127 are formed at predetermined intervals between them in the circumferential direction of the cylindrical support element 121, so that the longitudinal direction of the hole 127 corresponds to the transverse direction of the support element 121 (i.e., a direction parallel to relative to the axis of rotation of the cylindrical roller 123). The support member 121 ensures that the laser beam passes through the openings 127, but the laser beam is not allowed to pass through (sections) other than the openings 127. Methods of forming the openings 127 in the support member 121 include: (1) a method for making the openings 127, according to which is carried out, for example, etching, perforation or laser processing, in predetermined sections of the support element 121; and (2) a method comprising using multiple curved rectangular elements as a support element 121 instead of a single annular element and arranging these elements between the pair of frame elements 122, 122, between which there are predetermined gaps in the circumferential direction of the frame elements 122. According to the method ( 2), the gap between the two adjacent elements is a slit-like opening 127.

[0059] It should be noted that, in this laser coupler 120, the slit-like hole 127 that pierces the support member 121 in the thickness direction is a translucent section through which the laser beam can pass. Thus, the continuous web section of the diapers 110, which covers the opening 127, i.e., the section 110C to be cut / removed, is pressed by the pressing tape 124, but is not between the supporting member 121 and the pressing tape 124. Thus, strictly speaking, on the subject cutting / separating section 110C does not act compressive force created by placing between the elements 121, 124. Even though the section to be cut / separated blocking the hole 127 is not between the elements 121, 124, its vicinity, etc. e. the sections of the continuous web of diapers 110, which overlap the vicinity of the opening 127, comprise elements 121, 124 between themselves. Thus, the section to be cut / separated does not move before and after the action of the laser beam, and thus the cut edge parts that are formed by cutting / separating the continuous web of diapers 110 when not exposed to the laser beam, they do not move. In other words, the section to be cut / separated in the continuous web of diapers 110 is a section that limits the compressive force generated by the interposition between the elements 121, 124, and is a section that is actually affected by the compressive force.

[0060] The belt-type pressure device 126 comprises: endless pressure belt 124; and three rollers 125a, 125b, 125c, which rotate in a state in which the pressure belt 124 connects the rollers. The rollers 125a, 125b, 125c can be drive rollers, or they can be drive rollers that follow the rotation of the cylindrical roller 123. When one or more of the rollers 125a, 125b, 125c are rotated, the pressure belt 124 moves with the same speed, like a cylindrical roller 123 (support element 121). It turns out that the support member 121 and the pressure strip 124 are supported within a predetermined temperature range by air cooling, water cooling, etc.

[0061] As the pressing tape 124, a tape made of metal or polymer can be used that has heat resistance, which can withstand the heat generated during processing, and this can be, for example, a tape made from a metal material such as iron, aluminum or stainless steel. In addition, as a clamping tape 124, a tape is generally used that does not transmit a laser beam directed onto a continuous web of diapers 110, which is a blank, but, alternatively, a tape having such a transmittance can be used.

[0062] As illustrated in FIG. 7, an irradiation head 135 is present in the hollow section of the hollow cylindrical roller 123 (support member 121), which emits a laser beam 130 towards the support member 121, which forms the peripheral surface section of the cylindrical roller 123. The irradiation head 135 is a galvanic scanner that can provide free scanning the laser beam 130 and includes, for example, a mechanism that causes the laser beam 130 to move forward and backward in a direction parallel to the axis of rotation of the cylinder one roller 123; a mechanism for moving, in the circumferential direction of the cylindrical roller 123, a position (irradiation point) at which the laser beam 130 is incident on a continuous web of diapers 110 on the supporting member 121; and a mechanism that keeps the diameter of the spot of the laser beam 130 on the peripheral surface of the cylindrical roller 123 constant. In this configuration, the laser irradiation mechanism can move the irradiation point of the laser beam 130 in an arbitrary manner simultaneously simultaneously in the circumferential direction of the cylindrical roller 123 and in a direction perpendicular to the circumferential direction (i.e., in a direction parallel to the axis of rotation of the cylindrical roller 123).

[0063] As illustrated in FIG. 7, a continuous web of diapers 110 is guided onto the outer surface of the support member 121, which forms a peripheral surface section of a cylindrical roller 123 rotated in the direction of arrow A, in a state in which a predetermined tension is applied to it by drive rollers, etc. ( not illustrated in the drawings). The continuous web of diapers 110 is then moved a predetermined distance by rotating the cylindrical roller 123 in its circumferential direction so that it passes over the support member 121. After that, the continuous web of diapers 110 is separated from the support member 121 by exhaust rollers and pinch rollers (not illustrated in the drawings) ) By moving the continuous web of diapers 110 so that it extends above the support member 121, which forms the peripheral surface section of the cylindrical roller 123, with a predetermined tension applied thereto, so that it is pressed by the pressure tape 124, sections of the continuous web of diapers 110, which are between the support member 121 and the clamping tape 124 and their surroundings are brought into a state in which they are compressed in the thickness direction before being cut and cut by the action of a laser beam. Thus, in those cases where, for example, the continuous web of diapers 110 includes a nonwoven fabric made of synthetic polymer, the continuous web of diapers 110 can be compressed more efficiently; and as a result of this, when the laser beam acting on the continuous web of diapers 110 in such a compressed state cuts and separates, the cut off edge parts of the plurality of sheets that make up the cut / separated section can be fused more reliably, and thus further increases the strength of the fusion joint by the fusion-connected part in each side seam 4.

[0064] The angle of rotation that the support member 121 (cylindrical roller 123) provides from the moment the continuous web of diapers 110 enters the support member 121, until it is separated from it, can be, for example, from 90 degrees to 270 degrees inclusive, and preferably from 120 degrees to 270 degrees inclusive. In addition, if the case where the continuous web of diapers 110 is compressed when a cylindrical support element 121 (cylindrical roller 123) comes into contact with it around its perimeter in its circumferential direction is considered as a 360-degree rotation, the angular interval for compressing the continuous web of diapers 110 in contact with the support member 121 by means of the clamping tape 124 is preferably 90 degrees or more and more preferably 120 degrees or more, and preferably 270 degrees or less and more preferably 270 degrees or less, and more specifically, preferably from 90 degrees to 270 degrees inclusive, and more preferably from 120 degrees to 270 degrees inclusive.

[0065] In the method of forming side seams 4, which is illustrated in FIG. 7, while the continuous web of diapers 110 is continuously moving, one surface 110a of the continuous web of diapers 110 (see FIG. 8 (a)) is pressed against the outer surface of the support member 121, from which the peripheral surface section of the cylindrical roller 123 is formed, and which has slit-like openings 127 through which the laser beam 130 can pass, and by acting on the continuous web of diapers 110, which is in a compressed state, by the laser beam 130 from the side of the support member 121 through the opening s 127 110 a continuous web of diapers is cut and separated, and simultaneously connected by melting the cut edge portions are formed by cutting and separation into multiple sheets in the above compressed state. In this way, side seams 4 are formed.

[0066] More specifically, as illustrated in FIG. 7, the pressing tape 124 is pressed against another surface 110b (see FIG. 8 (a); a surface on the opposite side with respect to the aforementioned first surface 110a, which is the surface adjacent to the supporting member 121) of the continuous web of diapers 110, which is pressed against the supporting element 121, and the continuous web of diapers 110 in this state is affected by a laser beam 130 from the side of the support element 121 through the slit-like hole 127. Thus, diapers 1 having a pair of side 4. It is preferable to direct the laser beam 130 onto a continuous web of diapers 110, which is in a compressed state between the support member 121 and the pressure strip 124, from the point of view of reliable fusion bonding of the cut edge parts of the sheets under the influence of radiation and increasing the bond strength by side fusion seam 4.

[0067] FIG. 8 (a) -8 (c) explain how the continuous web of diapers 110 is cut and divided at the same time as the formation of side seams 4 by using a laser coupler 120. FIG. 8 (a) schematically illustrates a section 110C into a continuous web of diapers 110 that is cut / separated by a laser beam 130, as well as its surroundings. The section 110C to be cut / separated in the continuous web of diapers 110 is located in the center, in the direction of movement A, of the continuous web of diapers 110 where the absorbent elements 2 are not located. The section 110C to be cut / separated is, for example, a four-layer section, layers which form four sheets. As illustrated in FIG. 8 (a), the four-layer structured section comprises two sheets (outer sheet 31 and inner sheet 32) in the front portion F and two sheets 31, 32 in the rear portion R, and it is formed by stacking these four sheets. It should be noted that although the elastic fibers 33 separate the mutually overlapping sheets 31, 32 between them, the elastic fibers 33 are not shown in the illustration in FIG. 8 (a) -8 (c) for ease of explanation.

[0068] In the continuous web section 110C of the diaper 110 to be cut / removed, one or both sheets, including an outer sheet 31 constituting one surface 110a (a surface pressed against the support member 121) of the continuous web of diapers 110, and a sheet (inner sheet 32) not constituting a sheet constituting the aforementioned single surface 110a are sheets that produce heat by absorbing laser radiation 130. In addition, before exposure to the laser beam 130, two mutually overlapping sheets are to be th cutting / separation section 110C and their surroundings can be connected by means of adhesive, and so on. e., or they do not have to be connected without fail.

[0069] As illustrated in FIG. 8 (b), the continuous web of diapers 110 enters the support member 121, which rotates in the direction of arrow A, so that the aforementioned one surface 110a is pressed against the support member 121 and the section 110C to be cut / separated is located on the slotted hole 127. In addition , the continuous web of diapers 110 is compressed in the thickness direction while it is moving in the direction of arrow A due to the fact that the other surface 110b is pressed by the pressure tape 124. Then, the section to be cut / removed is I 110C, which moves in this compressed state, is irradiated with a laser beam 130 through an opening 127 from the side of the support member 121. As described above, the point of action of the laser beam 130 is determined so that it can arbitrarily move in the circumferential direction of the cylindrical roller 123, and it set so as to follow the movement of the hole 127 in the circumferential direction. Thus, during the movement, the section 110C located at the hole 127 to be cut / separated is continuously exposed to the laser beam 130 for a certain period of time.

[0070] When the laser beam 130 acts on the section 110C to be cut / separated, the materials (synthetic fibers, etc.) from which the sheets 31, 32 are formed in the section 110C to be cut / separated, generate heat due to the direct action of the laser beam 130, and thus they evaporate and are removed from the section in a continuous web of diapers. Meanwhile, the aforementioned sheet forming materials in the vicinity of the section 110C to be cut / separated are indirectly heated by the laser beam 130 and melted. As a result of this, as illustrated in FIG. 8 (c), the section 110C to be cut off / melted is melted and cut, and thus the continuous web of diapers 110 is cut and separated, and as a result, one diaper 1 is separated from the continuous web of diapers 110, and simultaneously in the separated diaper 1 are fused the cut edge parts of the four sheets 31, 32 that were formed by cutting / separating, as well as the cut edge parts of the four sheets 31, 32 in the continuous web of diapers 110 from which the diaper was separated. These cut edge portions are compressed (compressed) by being placed between the support member 121 and the pressure strip 124 before they are formed (i.e., before the continuous web of diapers 110 is cut and separated by the action of the laser beam 130).

[0071] According to the method of forming the side seams 4 by using the device that is illustrated in FIG. 7, cutting / separation of the continuous web of diapers 110 and fusion bonding of the cut edge parts of the sheets, which are in a compressed state and which were formed in two places by cutting / separation, is carried out simultaneously by a single exposure to a laser beam. Thus, in comparison with the methods in which two fusion joints are formed by double exposure to a laser beam, fusion bonding and cutting / separation can be carried out at the same stage with almost half the laser output power, and thus, diapers 1 can be effectively manufactured. In addition, since fusion bonding and cutting / separation can be carried out in one step, no unconnected portions are formed into which the cut edge portions ists are not connected by melting. Thus, the diaper 1 has an excellent appearance.

[0072] The cut off edge portions of the sheets 31, 32 are in a molten state due to the generation of heat during exposure to the laser beam 130 and immediately after the irradiation is stopped. However, after the cessation of irradiation, the cut off edge parts are easily cooled by contact with the support element 121, as well as quickly cooled by the surrounding air and by heat transfer to the support element 121 and the pressure belt 124 and, thus, solidify, and the compressed state under the action of the support element 121 and the pressure strip 124 is stored in the continuous web of diapers 110, and a separate blank of the diaper is separated from the continuous web of diapers 110 under the action of the laser beam 130. Thus, cut s edge portions in turn connected by melting parts 40, in which the materials from which the cut edge portions are formed, including adhesive melted and joined to each other. By forming the fusion-connected portion 40, one side seam is formed from a pair of side seams 4, 4 of the separate diaper 1. If necessary, the cut edge parts of the sheets 31, 32 can be forcedly cooled by known cooling devices such as a suction device or an air evacuation device, which promotes the formation of fused parts 40.

[0073] After the section 110C to be cut / separated is cut off and separated, the laser beam 130 is moved so that its irradiation point coincides with another hole 127 adjacent to the hole in a direction opposite to the direction of movement A, and a laser beam 130 is discharged through this other opening 127 to another section 110C to be cut / separated, which is located thereon. Thus, this other section 110C to be cut / removed is cut off / separated and fused in the same manner, and another side seam 4 is formed, which is paired with the previously formed side seam 4. After this, the same operation is repeated, and thus diapers 1 are continuously manufactured, each of which has a pair of side seams 4, 4. According to this method, the side seams 4 of the diaper 1 are formed by fusion bonding under the action of a laser beam and are not formed by other joining methods Nia melting.

[0074] In the fusion-connected portion 40 of the side seam 4 formed as described above, due to the method by which the fusion-connected portion is formed, melting and cutting are carried out in a state in which the elastic members 51a, 51b are stretched, and thus, the elastic the elements are contracted and extended in the Y direction from the fusion joint portion 40 of the side seam 4. As a result, numerous small cavities are formed in the fusion joint portion 40. Thus, in the X direction, the cavities are located in the same positions as the elastic elements. The presence of these cavities is an advantage in that the degree to which the fused part 40 transmits and reflects light varies depending on the angle of incidence of the light, and the visibility of the side seam 4, which has a small thickness T1 and is less noticeable, is improved. In addition, the absence of elastic elements 51a, 51b in the positions of the cavities is an advantage because the side seam 4 is easily torn during removal of the diaper 1 by tearing the side seam 4. On the other hand, if the elastic elements are present in the side seam 4, this may be the disadvantage is that the elastic elements can stretch during tearing of the side seam 4, and the elastic elements can be difficult to cut.

[0075] If the diameter Φ of the spot of the laser beam 130 (that is, the area affected by the laser beam 130) on the continuous web of diapers 110 is less than the width W of the slotted hole 127 (see FIG. 8 (b); the length of the hole 127 in the circumferential direction of the cylindrical roller 123) through which the laser beam 130 is emitted (i.e., if Φ / W is less than 1), then, as illustrated in FIG. 9, a pair of side seams 4, 4 formed by the action of a laser beam 130 may be located in the continuous web section of the diapers 110, which overlaps the opening 127 (i.e., in the section located between the pair-forming edges of the slit-like opening 127, which extend in a direction perpendicular to relative to the direction of movement in the top view). In other words, fusion-connected portions 40 can be formed, even in the continuous web section of the diaper 110, which is not between the support member 121 and the pressure belt 124, provided that this section is near the opening 127, i.e., is a section, which is actually affected by the compressive force created by placing between the elements 121, 124, as described above.

[0076] In the diaper 1 made as described above, the thickness T1 of the side seam 4 is more than the thickness T2 of each of the front portion F and the rear portion R of the outer cover, which make up the side seam, in respective sections adjacent to the side seam 4, as illustrated in FIG. 3 and described above. The thickness T2 of each of the front section F and the rear section R of the outer cover 3 can be measured by placing the measured section (side seam) between the flat plates in a position almost in the middle of the side seam 4 and the transverse side edge of the absorbent element 2 while applying a load of 0.5 cN / cm ² ; observing the cross-section of one diaper at a magnification of 50x to 200x using a VHX-1000 microscope manufactured by Keyence, etc., at three separate points in the longitudinal direction; determination of the thickness of the section, measured in each cross section; and calculating the average thicknesses measured at three points.

[0077] The present invention is described above in accordance with its preferred embodiments, but the present invention is not limited to the above-described embodiments. For example, according to the embodiments described above, laser beam melting / cutting by using the apparatus illustrated in FIG. 7 is an example of a preferred method for manufacturing side seams 4, but the method for manufacturing side seams S is not limited thereto, and other methods such as thermal bonding, ultrasonic bonding, high frequency bonding or adhesive bonding can be used.

[0078] The outer coating, which is illustrated in FIG. 10, can be used as an outer coating. The outer cover 6 illustrated in this drawing includes an outer sheet 61 and an inner sheet 62, and numerous elastic elements 80 extending in the transverse direction of the diaper 1 are stretched between the sheets 61, 62. The elastic elements 80 are attached only in their both end parts at least one of the outer sheet 61 and the inner sheet 62. In addition, the elastic elements 80 are in an unfixed state with respect to both sheets, including the outer sheet 61 and the inner sheet 62, in the region part located between both end parts. The outer sheet 61 and the inner sheet 62 are connected periodically by connected parts 63 between each pair of elastic elements 80 that are adjacent to each other in the longitudinal direction X of the diaper 1. As illustrated in the drawing, it is preferable that the connected parts 63 form a row 64 of connected parts a row 64, in which the connected parts are arranged in a straight line in the longitudinal direction X of the diaper 1. In addition, it is preferable that the rows of 64 connected parts are aligned in the transverse direction enii Y of the diaper 1. By using this external cover 6 it is possible to create folds having excellent appearance.

[0079] According to the embodiment described above, the diaper includes an outer cover 3 that extends from the front portion F to the rear portion R through the crotch portion M, and an absorbent member located on its inner surface. Alternatively, the present invention extends to a pull-on disposable diaper formed in such a way that the absorbent element is located between the front section including the elastic elements located below the waist and the rear section also including the elastic elements located below the waist.

[0080] According to the embodiment described above, elastic-free regions 9a, 9b are formed in each of the front portion F and the rear portion R of the diaper 1 so that there is a side seam 4 between them. Alternatively, the elastic-free region can only be formed in the front section F of the diaper 1. Alternatively, areas without elastic elements can be formed simultaneously in the front section F and the rear section R.

[0081] According to the embodiment described above, each elastic-free region 9a, 9b is formed only in the longitudinal upper region of the side seam 4. Alternatively, the elastic-free region can be formed only in the longitudinal lower region of the side seam 4, or it can be formed simultaneously in the longitudinal upper region and the longitudinal lower region of the side seam 4 by changing the positions in which the elastic elements connected by adhesive are located. Alternatively, a region free of elastic elements can only be formed in the central region. In addition, a region not containing elastic elements can be formed in the entire region, in the longitudinal direction X, of the side seam 4.

[0082] Regarding the above-described embodiments, the present invention further describes the following stretchable disposable diapers.

{1} A stretchable disposable diaper, which comprise: the crotch area; the front section, which is located in front of the crotch area; and a back portion that is located posterior to the crotch portion; and a pair of side seams formed by connecting both edge parts of the sides of the front portion with the corresponding transverse side edge parts of the rear portion, wherein:

the pull-on disposable diaper has a longitudinal direction that corresponds to the anteroposterior direction of the user, and a transverse direction that is perpendicular to the longitudinal direction;

each side seam includes a fusion-connected portion that extends continuously in the longitudinal direction of the diaper;

unconnected parts are practically absent in the section located outside with respect to the fusion-connected part in the transverse direction of the diaper;

numerous stretched elastic elements are located in each portion representing the front portion or the rear portion, and are attached to each of the front portion and the rear portion by adhesive;

at least the end part of the elastic element, which is located near the side seam, and the part near the end part, are painted so that they have a color that differs from the background color of the front section or the rear section in which this elastic element is located;

the end portion of both end parts of at least some of the elastic elements that are located near the side seam does not reach the position of the side seam and ends at a point located inside with respect to the side seam in the transverse direction, and thus not containing elastic elements, a region is formed between the side seam and the end portion of each of these elastic elements; and

in the area that does not contain elastic elements, there is no adhesive to connect the elastic elements.

[0083] {2} A stretchable disposable diaper according to condition {1}, in which an unconnected portion having a width of 1 mm or less is present.

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

{4} A stretchable disposable diaper according to any one of the conditions {1} to {3}, wherein the thickness of the side seam is preferably 2 mm or less, more preferably 1.5 mm or less.

{5} A stretchable disposable diaper according to any of the conditions {1} - {4}, wherein:

the disposable diaper further includes an outer cover and elastic waist elements located in the outer cover; and

the color difference between the color of the elastic element for the waist and the background color of the outer cover, which is expressed as the difference between the value a of the outer cover and the value a of the elastic element, is preferably 10 or more, more preferably 15 or more.

{6} A stretchable disposable diaper according to any of the conditions {1} - {5}, wherein:

the disposable diaper further includes an outer cover, and front elastic elements for the waist located in the front portion in the outer cover; and

at least the end part of the front elastic element for the waist and the part near the end part, and also preferably the entire region of the front elastic element for the waist, is painted so that they have a color that differs from the background color of the outer coating constituting the front portion.

[0084] {7} A stretchable disposable diaper according to any of the conditions {1} to {6}, wherein:

the disposable diaper further includes an outer cover;

the outer coating includes an outer sheet and an inner sheet; and

the outer sheet and the inner sheet are extensible due to the fact that the constituent fibers of the sheets themselves are made extensible.

{8} A pull-on disposable diaper according to any of the conditions {1} - {7}, wherein:

the disposable diaper further includes an outer cover;

the outer coating includes an outer sheet and an inner sheet; and

the outer and inner constituent fibers of the sheets themselves are not stretchable, but the outer sheet and inner sheet as a whole are stretchable as a result of separation of the fibers that were joined at the points of intersection, bonding, and other binding of the fibers and resulting from a structural change in the three-dimensional structure formed fibers, or rupture of constituent fibers.

{9} A stretchable disposable diaper according to any of the conditions {1} - {8}, wherein:

the disposable diaper further includes an outer cover;

the outer coating includes an outer sheet and an inner sheet; and

constituent fibers (inelastic fibers) in each of the outer sheet and inner sheet include at least two components, including a low-melting component and a high-melting component.

{10} A stretchable disposable diaper according to condition {9}, in which the constituent fibers (inelastic fibers) in each of the outer sheet and inner sheet are connected to each other at the fiber intersection points by fusion bonding of at least a low-melting component.

{11} A stretchable disposable diaper according to any of the conditions {1} to {10}, wherein the color of the elastic elements located in the front portion is different from the color of the elastic elements located in the rear portion.

[0085] {12} A stretchable disposable diaper according to any one of the conditions {1} to {11}, wherein when the diaper is measured from the outside of the outer coating, the lightness of the non-elastic region is different from the lightness of other regions.

{13} A stretchable disposable diaper according to condition {12}, wherein, when the diaper is measured from the outside of the outer coating, the ratio L2 / L1 of the lightness L1 of the elastic region-free and lightness L2 of other regions is preferably 1.02 or more, more preferably 1 , 04 or more.

{14} A stretchable disposable diaper according to the condition {12} or {13}, wherein when the diaper is measured from the outside of the outer coating, the ratio L2 / L1 of the lightness L1 of the non-elastic region and the lightness L2 of other regions is preferably 1.3 or less, preferably 1.25 or less.

{15} A stretchable disposable diaper according to any one of the conditions {1} to {14}, in which multiple cavities are present in a fusion-connected portion of the side seam.

{16} A stretchable disposable diaper according to condition {15}, in which, in the longitudinal direction, the cavities are located in the same positions as the elastic elements.

{17} A stretchable disposable diaper according to any one of the conditions {1} to {16}, in which an area without elastic elements is formed in at least one of the longitudinal upper region of the side seam and the longitudinal lower region of the side seam.

[0086] {18} A stretchable disposable diaper according to condition {17}, in which an area without elastic elements is formed only in the longitudinal upper region of the side seam.

{19} A stretchable disposable diaper according to any of the conditions {1} - {18}, wherein:

the region below the waist in the front section and the rear section includes an elastic sheet having a structure in which filamentary elastic fibers are attached to the surface of the stretchable fibrous layer, which are mainly non-elastic fibers; and

some inelastic fibers are fused to and immersed in elastic fibers.

{20} A pull-on disposable diaper according to condition {19}, in which:

elastic fibers are located between the two sheets making up the elastic sheet; and

no adhesive is present between sheets and elastic fibers.

{21} A stretchable disposable diaper according to any of the conditions {1} - {20}, wherein:

the disposable diaper further includes an outer cover and elastic waist elements located in the outer cover; and

elastic elements for the waist, which are painted in such a way that they have a color that differs from the background color of the front section or the rear section, are visible when viewed from the outside of the diaper, that is, they are visible through the outer cover, which contains elastic elements for the waist .

{22} A manufacturing method for a stretchable disposable diaper according to any of the conditions {1} to {21}, the manufacturing method comprising the following steps:

obtaining a multilayer continuous outer coating by applying a continuous outer coating on the side of the front section and a continuous outer coating on the side of the rear section; and

the formation of a side seam by melting and cutting out a section, in a multilayer continuous outer coating, where a side seam should be formed.

{23} A method of manufacturing a stretchable disposable diaper according to condition {22}, the method comprising the step of forming, through the use of a laser device for melting / cutting, side seams, each of which includes a fused joint made by fusion of both edge parts of the sides the front portion of the outer coating with the corresponding edge portions of the sides of the rear portion of the outer coating in a state in which the edge portions overlap, why:

at least some of the sheets constituting the outer coating include polymeric material; and

the fusion-connected part is formed when: the production of one surface of the multilayer sheet is carried out, in which both edge parts of the sides of the front portion of the outer coating and the corresponding edge parts of the sides of the rear portion of the outer coating overlap, pressing against a support member that has a translucent section through which to pass a laser beam; and irradiation, from the side of the support member through the translucent section, of the multilayer sheet which is in a compressed state, by laser radiation which has such a wavelength that it is absorbed by the sheets constituting the multilayer sheet and which causes the sheets to produce heat; and thus cutting and separating the multilayer sheet and, at the same time, fusing the cut edge parts in a compressed outer coating that are formed by cutting / separation.

[0087] {24} A method of manufacturing a stretchable disposable diaper according to condition {22} or {23}, in which the sheets constituting the outer coating become stretchable when fusion processing, stretching between the rollers, stretching by engagement between the teeth and the recesses or between gears, or deformation stretching using a tension frame.

{25} A method of manufacturing a stretchable disposable diaper according to any one of the conditions {22} - {24}, in which elastic fibers are formed by stretching the elastic polymer in its molten or softened state.

{26} A method of manufacturing a stretchable disposable diaper according to any of the conditions {22} to {25}, wherein:

no heat affects the sheets that make up the outer coating; and

the elastic fibers that are obtained by melt spinning are fused to the sheets before the elastic fibers harden.

{27} A method of manufacturing a stretchable disposable diaper according to any one of the conditions {22} - {26}, in which the sheets constituting the outer coating are preferably not stretchable in their original textile state.

{28} A stretchable disposable diaper according to any of the conditions {1} to {21}, wherein the disposable diaper is made by a method of manufacturing a stretchable disposable diaper, comprising the following steps:

obtaining a multilayer continuous outer coating by applying a continuous outer coating on the side of the front section and a continuous outer coating on the side of the rear section; and

the formation of a side seam by melting and cutting out a section, in a multilayer continuous outer coating, where a side seam should be formed.

[0088] {29} A stretchable disposable diaper according to the condition {28}, wherein the disposable diaper is made by a method of manufacturing a stretchable disposable diaper, comprising the step of forming, using a laser device for melting / cutting, side seams, each of which includes a fused joint made by fusion bonding of both edge parts of the sides of the front portion of the outer cover with the corresponding edge parts of the sides of the rear portion uzhnogo coating in a state in which the overlapping edge portions, wherein:

at least some of the sheets constituting the outer coating include polymeric material; and

the fusion-connected part is formed when: the production of one surface of the multilayer sheet is carried out, in which both edge parts of the sides of the front portion of the outer coating and the corresponding edge parts of the sides of the rear portion of the outer coating overlap, pressing against a support member that has a translucent section through which to pass a laser beam; and irradiation, from the side of the support member through the translucent section, of the multilayer sheet which is in a compressed state, by laser radiation which has such a wavelength that it is absorbed by the sheets constituting the multilayer sheet and which causes the sheets to produce heat; and thus cutting and separating the multilayer sheet and, at the same time, fusing the cut edge parts in a compressed outer coating that are formed by cutting / separation.

{30} A stretchable disposable diaper according to condition {28} or {29}, in which the sheets constituting the outer cover become stretchable when heat treated, stretch between the rollers, stretch by engagement between teeth and recesses or between gears, or strain stretch using the tension frame.

{31} A stretchable disposable diaper according to any one of the conditions {28} - {30}, in which the elastic fibers are formed by stretching the elastic polymer in its molten or softened state.

{32} A pull-on disposable diaper according to any of the conditions {28} - {31}, the diaper being manufactured as follows:

no heat affects the sheets that make up the outer coating; and

fusion bonding of the elastic fibers that are obtained by melt spinning to the sheets is carried out before the elastic fibers harden.

Industrial applicability

[0089] According to the present invention, the level of convenience during tearing of the side seam of the diaper is increased, and the diaper can be easily changed.

Claims (63)

1. A stretchable disposable diaper comprising: a crotch area; the front section that extends from the front side of the crotch section; and a back portion that extends from a back side of the crotch portion; and a pair of side seams formed by connecting both edge parts of the sides of the front portion with the corresponding edge parts of the sides of the rear portion, wherein: the pull-on disposable diaper has a longitudinal direction that corresponds to the anteroposterior direction of the user, and a transverse direction that is perpendicular to the longitudinal direction; each side seam includes a fusion-connected portion that extends continuously in the longitudinal direction of the diaper; unconnected parts are essentially absent in a section located externally with respect to the fusion-connected part in the transverse direction of the diaper; in each of the front and rear sections, a plurality of elastic elements are located in a stretched state, the elastic elements being attached to each of the front section and the rear section by adhesive; at least the end part of the elastic element, which is located near the side seam, and the part near the end part, are painted so that they have a color that differs from the background color of the front section or the rear section in which this elastic element is located; the end part of both end parts of at least some of the elastic elements, which is located near the side seam, does not reach the position of the side seam and ends at a point located inside with respect to the side seam in the transverse direction, and thus not containing elastic elements an area is formed between the side seam and the end portion of each of these elastic elements; and an area that does not contain elastic elements does not contain an adhesive for bonding elastic elements. 2. A stretchable disposable diaper according to claim 1, comprising an unconnected portion having a width of 1 mm or less. 3. A stretchable disposable diaper according to claim 1, wherein the thickness of the side seam is 0.2 mm or more. 4. A stretchable disposable diaper according to claim 1, wherein the thickness of the side seam is 0.25 mm or more. 5. A stretchable disposable diaper according to claim 1, wherein the thickness of the side seam is 2 mm or less. 6. A stretchable disposable diaper according to claim 1, wherein the thickness of the side seam is 1.5 mm or less. 7. A stretchable disposable diaper according to claim 1, wherein: the disposable diaper further includes an outer cover and elastic waist elements located in the outer cover; and the color difference between the color of the elastic element for the waist and the background color of the outer cover, which is expressed as the difference between the value a of the outer cover and the value a of the elastic element, is 10 or more. 8. A stretchable disposable diaper according to claim 1, wherein: the disposable diaper further includes an outer cover and elastic waist elements located in the outer cover; and the color difference between the color of the elastic element for the waist and the background color of the outer cover, which is expressed as the difference between the value a of the outer cover and the value a of the elastic element, is 15 or more. 9. A stretchable disposable diaper according to claim 1, wherein: the disposable diaper further includes an outer cover and front elastic elements for the waist located in the front portion in the outer cover; and at least the end portion of the front elastic element for the waist and the part near the end part, and also preferably the entire region of the front elastic element for the waist, is painted so that they have a color that differs from the background color of the outer coating constituting the front portion. 10. A stretchable disposable diaper according to claim 1, wherein: the disposable diaper further includes an outer cover; the outer coating includes an outer sheet and an inner sheet; and the outer sheet and the inner sheet are extensible due to the fact that the constituent fibers of the sheets themselves are made extensible. 11. A stretchable disposable diaper according to claim 1, wherein: the disposable diaper further includes an outer cover; the outer coating includes an outer sheet and an inner sheet; and the fibers that make up the outer and inner sheets themselves are not stretchable, but the outer sheet and inner sheet are generally stretchable as a result of the separation of the fibers that were joined at the points of intersection, bonding and other binding of the fibers and resulting from a structural change in the three-dimensional structure formed by fibers, or rupture of constituent fibers. 12. A stretchable disposable diaper according to claim 1, wherein: the disposable diaper further includes an outer cover; the outer coating includes an outer sheet and an inner sheet; and component fibers (inelastic fibers) in each of the outer sheet and inner sheet include at least two components, including a low-melting component and a high-melting component. 13. The stretchable disposable diaper according to claim 12, wherein the constituent fibers (inelastic fibers) in each of the outer sheet and inner sheet are connected to each other at the fiber intersection points by fusion bonding of at least the fusible component. 14. The stretchable disposable diaper according to claim 1, wherein the color of the elastic elements located in the front section is different from the color of the elastic elements located in the rear section. 15. The stretchable disposable diaper according to claim 1, wherein, when the diaper is viewed from the outside of the outer coating, the lightness of the non-elastic area is different from the lightness of other areas. 16. The stretchable disposable diaper according to claim 15, wherein, when the diaper is viewed from the outside of the outer cover, the ratio L2 / L1 of the lightness L1 of the elastic region and lightness L2 of other regions is 1.02 or more. 17. The stretchable disposable diaper according to claim 15, wherein, when the diaper is viewed from the outside of the outer coating, the ratio L2 / L1 of the lightness L1 of the elastic region and lightness L2 of other regions is 1.04 or more. 18. The stretchable disposable diaper according to claim 15, wherein, when the diaper is viewed from the outside of the outer coating, the ratio L2 / L1 of the lightness L1 of the elastic region-free region and the lightness L2 of other regions is 1.3 or less. 19. The stretchable disposable diaper according to claim 15, wherein, when the diaper is viewed from the outside of the outer cover, the ratio L2 / L1 of the lightness L1 of the elastic region-free region and the lightness L2 of other regions is 1.25 or less. 20. A stretchable disposable diaper according to claim 1, in which the fusion-connected part of the side seam contains many cavities. 21. A stretchable disposable diaper according to claim 20, in which, in the longitudinal direction, the cavities are located in the same positions as the elastic elements. 22. The stretchable disposable diaper according to claim 1, wherein the region containing no elastic elements is formed in at least one of a longitudinal upper region of a side seam and a longitudinal lower region of a side seam. 23. A stretchable disposable diaper according to claim 22, in which the region not containing elastic elements is formed only in the longitudinal upper region of the side seam. 24. A stretchable disposable diaper according to claim 1, in which: the region below the waist in the front section and the rear section includes an elastic sheet having a structure in which filamentary elastic fibers are attached to the surface of an extensible fibrous layer made essentially of inelastic fibers; and part of the inelastic fibers is fused to the elastic fibers and immersed in them. 25. A stretchable disposable diaper according to claim 1, wherein: the disposable diaper further includes an outer cover and elastic waist elements located in the outer cover; and elastic elements for the waist, which are colored so that they have a color that differs from the background color of the front section or the rear section, are visible when viewed from the outside of the diaper, i.e. are visible through the outer cover, which contains elastic elements for the waist. 26. A stretchable disposable diaper according to claim 1, wherein the disposable diaper is made by a method of manufacturing a stretchable disposable diaper, comprising the following steps: obtaining a multilayer continuous outer coating by applying a continuous outer coating on the side of the front section and a continuous outer coating on the side of the rear section; and the formation of a side seam by melting and cutting a section, in a multilayer continuous outer coating, where a side seam should be formed. 27. A stretchable disposable diaper according to claim 26, wherein the disposable diaper is made by a method of manufacturing a stretchable disposable diaper, comprising the step of forming, by using a laser device for melting / cutting, side seams, each of which includes a fused joint made by fusing both edge parts of the sides of the front portion of the outer coating with the corresponding edge parts of the sides of the rear portion of the outer coating in a state in which the edge portions overlap, wherein: at least some of the sheets constituting the outer coating include polymeric material; and the fusion-connected part is formed by: manufacturing one surface of the multilayer sheet in which both edge parts of the sides of the front portion of the outer coating and the corresponding edge parts of the sides of the rear portion of the outer coating overlap, pressing against a support member that has a translucent section through which the laser can pass Ray; and irradiating, from the side of the support member through the translucent section, a multilayer sheet that is in a compressed state, by laser radiation that has such a wavelength that it is absorbed by the sheets constituting the multilayer sheet and which causes the sheets to produce heat; and, thus, cutting and separating the multilayer sheet and, at the same time, joining by fusion of the cut edge parts, in a compressed outer coating, which are formed by cutting / separation. 28. A method of manufacturing a stretchable disposable diaper according to claim 1, the method comprising the following steps: obtaining a multilayer continuous outer coating by applying a continuous outer coating on the side of the front section and a continuous outer coating on the side of the rear section; and the formation of a side seam by melting and cutting out a section, in a multilayer continuous outer coating, where a side seam should be formed. 29. A method of manufacturing a stretchable disposable diaper according to claim 28, comprising the step of forming, using a laser device for melting / cutting, side seams, each of which includes a fused joint made by fusion of both edge parts of the sides of the front of the outer coating with the corresponding edge parts of the sides of the rear portion of the outer coating in a state in which the edge parts overlap, wherein: at least some of the sheets constituting the outer coating include polymeric material; and the fusion-connected part is formed by manufacturing one surface of the multilayer sheet in which both edge parts of the sides of the front portion of the outer coating and the corresponding edge parts of the sides of the rear portion of the outer coating overlap, pressing against a support member that has a translucent section through which the laser beam can pass ; and irradiating, from the side of the support member through the translucent section, a multilayer sheet that is in a compressed state, by laser radiation that has such a wavelength that it is absorbed by the sheets constituting the multilayer sheet and which causes the sheets to produce heat; and, thus, cutting and separating the multilayer sheet and, at the same time, joining the cut edge parts in a compressed outer coating that are formed by cutting / separation.

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