JP6636855B2 - Absorbent articles - Google Patents

Description

  The present invention relates to an absorbent article having an elastic film elastic structure in which an elastic film is sandwiched between sheet layers.

  In an absorbent article, in order to improve the fit to the body surface, it is general to give elasticity to appropriate places such as around the legs and around the torso. Conventionally, as a method for imparting elasticity, a method of arranging and fixing a number of elongated elastic elastic members such as thread rubber in a state of being elongated in the longitudinal direction has been widely adopted, but is excellent in area fit. As an alternative, a method has been proposed in which an elastic film is attached while being stretched in a direction in which elasticity is imparted. (See, for example, Patent Document 1).

  The elastic film in which the elastic film is sandwiched between sheet layers (hereinafter, also referred to as elastic film elastic structure) has a structure in which an elastic film is laminated between a first sheet layer made of a nonwoven fabric and a second sheet layer made of a nonwoven fabric. The first sheet layer and the second sheet layer are arranged at intervals in the stretching direction and in a direction perpendicular to the stretching direction in a state where the elastic film is stretched in the stretching direction along the surface thereof. A large number of joints are joined through through holes formed in the elastic film. In such a stretchable elastic film structure, in the natural length state, as the elastic film contracts between the joints, the interval between the joints becomes narrower, and the elastic film expands and contracts between the joints in the first sheet layer and the second sheet layer. Shrinking wrinkles are formed that extend in a direction intersecting the direction. Conversely, when the elastic film is stretched between the joints, the interval between the joints and the shrinkage wrinkles in the first sheet layer and the second sheet layer are widened, and the first sheet layer and the second sheet layer are completely developed. Elastic extension is possible up to the state. This elastic film stretch structure has excellent surface fitting properties, of course, there is no bonding between the first sheet layer and the second sheet layer and the elastic film, and very little bonding between the first sheet layer and the second sheet layer. There is an advantage that it is very flexible because it is small, and that the through holes of the elastic film also contribute to the improvement of air permeability.

  On the other hand, in the absorbent article, even if elasticity is imparted only to an arbitrary portion, in order to facilitate manufacturing, elastic elastic members are attached to a wide area including an elastic region for imparting elasticity. After that, a non-stretchable region that does not require stretchability has been processed so that the contraction force of the elastic stretch member does not act (hereinafter, also referred to as killing the stretchability). For example, when imparting elasticity in the width direction around the trunk of a pants-type disposable diaper, after attaching an elongated elastic elastic member over the entire width direction, the width direction central portion overlapping with the absorber is finely cut, and Killing elasticity is widely practiced.

  However, the method of cutting elasticity by cutting thread rubber in the elastic structure using thread rubber, if applied directly to the elastic film elastic structure, would cut the entire elastic film in the direction intersecting the stretching direction, Since continuous cutting is required over a wide range, the first sheet layer and the second sheet layer may be cut, or even if the first sheet layer and the second sheet layer are not cut, the first sheet layer and the second sheet layer may have cutting traces (melting traces and pressures). (Trace) may remain largely.

JP-T-2004-532758

  Therefore, a main object of the present invention is to provide a novel non-stretchable region in an elastic film stretchable structure and a formation form thereof.

Absorbent articles that have solved the above problems ,
An elastic film is laminated between a first sheet layer and a second sheet layer, and the elastic film can expand and contract in the expansion and contraction direction, and the first and second sheet layers are in the expansion and contraction directions. And, with a large number of joints arranged at intervals in a direction orthogonal to this, and joined through a through hole formed in the elastic film, comprising an elastic film stretchable structure,
The region having the elastic film stretchable structure has a non-stretchable region and a stretchable region that is provided on at least one side in the stretchable direction of the non-stretchable region and that can be stretched in the stretchable direction.
In the non-stretchable region, since the area ratio of the joint portion is higher than that of the stretchable region, the elastic limit elongation in the stretchable direction is 130% or less.
It is characterized by the following .

As a result of examining a method of killing the elasticity of the elastic film elastic structure, the elastic film is sandwiched between the first sheet layer and the second sheet layer while extending in the elastic direction of the elastic region, and the elastic film is stretched in the elastic direction and perpendicular to the elastic direction. Are welded at a large number of places arranged at intervals in the direction in which the elastic film is melted at a large number of places to form through holes, and the first sheet layer and the second sheet layer are formed at the positions of the through holes. In the technique of forming the elastic film elastic structure by the technique of joining, when the area ratio (the ratio per unit area) of the joint portion is increased to a certain level or more, it has been found that the elasticity can be substantially killed. That is, in such an elastic film elastic structure, since the first sheet layer and the second sheet layer are contracted by the elastic film, that is, the portion between the through holes is basically reduced as the area ratio of the joining portion is increased, The elastic limit elongation tends to decrease. When the area ratio of the joint becomes higher than a certain level, the elastic limit elongation decreases, and most of the portions between the through holes of the elastic film are deteriorated by heat at the time of welding and the elasticity is reduced. The property almost disappears and it does not expand or contract. Therefore, according to the present absorbent article , the continuity of the elastic film in the stretchable region and the non-stretchable region can be maintained while substantially reducing the stretchability, and the appearance is improved.
Here, the “elastic limit elongation” means the elongation at the elastic limit (in other words, the state where the first sheet layer and the second sheet layer are completely expanded), and the length at the elastic limit is 100 times the natural length. %, And the “area ratio” means the ratio of the target portion to the unit area, and the target portion (for example, the joint, the penetration, The total area of the openings (openings of the holes) is divided by the area of the target region and expressed as a percentage. In particular, the “area ratio of the joint portion” means the area ratio in a state in which the area extends to the elastic limit in the direction of expansion and contraction. Things.

The above-described absorbent article includes an outer body constituting a front body and a rear body, and an inner body including an absorber fixed to an inner surface of the outer body, and both sides of the outer body in the front body and a rear body. The disposable diaper having a waist opening and a pair of right and left leg openings formed by joining a side seal portion by joining the both side portions of the outer body to each other to form a waist opening and a pair of left and right leg openings. And
The exterior body in at least one of the front body and the back body extends in the width direction corresponding to the space between the side seal portions in at least a part of the front-rear direction, and the elastic film elastic structure has the elastic direction in the width direction. It is prepared so that
Among the regions having the elastic film stretching structure, the non-stretching region is provided in a region overlapping with the absorber, and the stretching region is provided on both sides in the width direction.
Is preferred .

  ADVANTAGE OF THE INVENTION According to this invention, the advantage that a favorable non-stretchable area | region can be formed in an elastic film stretchable structure is brought.

It is a top view (inner side) of a pants type disposable diaper in a fully developed state. It is a top view (outer surface side) of a pants type disposable diaper in a fully developed state. (A) is a plan view of a main part of the exterior body, (b) is a cross-sectional view taken along line DD of (a), (c) is a cross-sectional view in a mounted state, and (d) is a cross-sectional view in a natural length state. (A) is CC sectional drawing of FIG. 1, (b) is EE sectional drawing of FIG. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is a top view showing only a main part of a pants type disposable diaper in a fully developed state. It is sectional drawing which shows roughly the principal part cross section of the exterior body extended to some extent in the width direction. It is a principal part schematic plan view of the exterior body of a fully developed state. It is a principal part enlarged plan view which shows the pattern of a joining part. It is a top view (outer surface side) of a pants type disposable diaper in a fully developed state. It is a principal part enlarged plan view which shows the pattern of a joining part. It is a photograph in the natural length state of the sample of an embodiment. It is a photograph in the extension state of the sample of an embodiment. It is a top view which shows the example of various arrangement | positioning of a joining part. It is an enlarged photograph of a joined part. It is an enlarged photograph of the joined part in the state which peeled the 1st sheet layer and the 2nd sheet layer. It is a schematic diagram showing a manufacturing flow of a pants type disposable diaper. It is the schematic of an exterior body assembly process.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The dot pattern in the cross-sectional view indicates a joining means such as a hot melt adhesive.
1 to 7 show a pants-type disposable diaper. The pants-type disposable diaper (hereinafter, also simply referred to as a diaper) includes an outer body 20 forming a front body F and a back body B, and an inner body 10 fixed to and integrated with the inner surface of the outer body 20. The inner body 10 has an absorbent body 13 interposed between a liquid-permeable top sheet 11 and a liquid-impermeable back side sheet 12. At the time of manufacturing, after the back surface of the inner body 10 is joined to the inner surface (upper surface) of the outer body 20 by a joining means such as a hot melt adhesive (shaded portion 10B in FIG. 7), the inner body 10 and the outer body 20 are joined. Is folded at the center in the front-rear direction (longitudinal direction), which is the boundary between the front body F and the back body B, and both sides thereof are joined to each other by heat welding or hot melt adhesive to form the side seal portion 21. Thereby, a pants-type disposable diaper having a waist opening and a pair of left and right leg openings is formed.

(Example of structure of interior body)
As shown in FIGS. 4 to 6, the inner body 10 has an absorber 13 interposed between a liquid-permeable top sheet 11 made of a nonwoven fabric or the like and a liquid-impermeable backside sheet 12 made of polyethylene or the like. It has a structure which absorbs and retains the excreted liquid that has passed through the topsheet 11. The planar shape of the interior body 10 is not particularly limited, but is generally a substantially rectangular shape as shown in the illustrated embodiment.

  As the liquid-permeable surface sheet 11 that covers the surface side (skin contact surface side) of the absorber 13, a perforated or non-porous nonwoven fabric or a porous plastic sheet is preferably used. The material fibers constituting the non-woven fabric can be synthetic fibers such as olefins such as polyethylene or polypropylene, polyesters, polyamides, etc., recycled fibers such as rayon and cupra, and natural fibers such as cotton. A nonwoven fabric obtained by an appropriate processing method such as a spun bond method, a thermal bond method, a melt blown method, and a needle punch method can be used. Among these processing methods, the spunlace method is excellent in that it is rich in flexibility and drapability, and the thermal bond method is excellent in that it is bulky and soft. When a large number of through-holes are formed in the liquid-permeable top sheet 11, urine and the like are quickly absorbed, resulting in excellent dry touch properties. The liquid-permeable topsheet 11 extends to the back side of the absorber 13 wrapping around the side edge of the absorber 13.

  A liquid-impermeable backing sheet 12 covering the back side (non-skin contacting side) of the absorber 13 is a liquid-impermeable plastic sheet such as polyethylene or polypropylene. Those having wetness are preferably used. This water-impermeable and moisture-permeable sheet is, for example, a microporous sheet obtained by melt-kneading an inorganic filler in an olefin resin such as polyethylene or polypropylene to form a sheet, and then stretching it uniaxially or biaxially. is there.

The absorber 13 is a known one, for example, a pile of pulp fibers, an aggregate of filaments such as cellulose acetate, or a nonwoven fabric, and is obtained by mixing and fixing a superabsorbent polymer as necessary. Can be used. The absorber 13 can be packaged with a packaging sheet 14 having liquid permeability and liquid holding properties, such as crepe paper, if necessary, for holding the shape and the polymer.
The shape of the absorber 13 is formed in an approximately hourglass shape having a constricted portion 13N narrower than the front and rear sides at the crotch portion, but may be any suitable shape such as a rectangular shape. Although the size of the constricted portion 13N can be appropriately determined, the length of the constricted portion 13N in the front-rear direction can be about 20 to 50% of the entire length of the diaper, and the width of the narrowest portion is 40% of the entire width of the absorber 13. About 60%. In the case where the inner body 10 has such a constricted portion 13N, if the planar shape of the inner body 10 is substantially rectangular, the remaining portion of the inner body 10 corresponding to the constricted portion 13N of the absorber 13 does not have the absorber 13. A part is formed.

  Solid gathers BS that fit around the legs are formed on both sides of the interior body 10. As shown in FIGS. 5 and 6, the three-dimensional gather BS includes a fixing portion fixed to the side of the back surface of the inner body, and a side portion of the surface of the inner body through the side of the inner body from the fixing portion. A main body portion extending to the front, a front and rear end portion of the main body portion being laid down and fixed to a side portion of the surface of the interior body, and a free portion formed by fixing the bottom portion to the side portion. The portion is formed of a gathered nonwoven fabric 15 formed into a double sheet by folding.

  Further, between the double sheets, an elongated gather elastic member 16 is disposed at a free end portion or the like. The gather elastic member 16 is used to form a three-dimensional gather BS by erecting a free part by elastic stretching force as shown by a two-dot chain line in FIG. 5 in a product state.

  The liquid-impermeable back sheet 12 is folded back together with the liquid-permeable top sheet 11 on both sides in the width direction of the absorber 13. As the liquid-impermeable back side sheet 12, it is desirable to use an opaque sheet so as to prevent browning such as defecation and urine. As the opacity, a film formed by internally adding a pigment or a filler such as calcium carbonate, titanium oxide, zinc oxide, white carbon, clay, talc, barium sulfate or the like to a plastic is preferably used.

  As the gather elastic member 16, a commonly used material such as styrene-based rubber, olefin-based rubber, urethane-based rubber, ester-based rubber, polyurethane, polyethylene, polystyrene, styrene-butadiene, silicone, and polyester can be used. In addition, in order to make it difficult to see from the outside, it is preferable that the thickness is 925 dtex or less, the tension is 150 to 350%, and the interval is 7.0 mm or less. As the gather elastic member 16, a tape-shaped member having a certain width can be used in addition to a thread-shaped member as shown in the illustrated embodiment.

  The material fibers constituting the gathered nonwoven fabric 15 are, similarly to the liquid-permeable surface sheet 11, olefin-based, polyester-based, amide-based, or other synthetic fibers such as polyethylene or polypropylene, as well as recycled fibers such as rayon or cupra, and cotton. Natural fibers such as spun bond method, thermal bond method, melt blown method, non-woven fabric obtained by an appropriate processing method such as a needle punch method can be used, especially to prevent stuffiness It is preferable to use a nonwoven fabric which has a low basis weight and is excellent in air permeability. Further, the gathered nonwoven fabric 15 is a silicone-based, paraffin-based metal-based, alkylchromic claroid-based water repellent to prevent the penetration of urine and the like, to prevent rash, and to enhance the feel (dryness) to the skin. It is desirable to use a water-repellent non-woven fabric coated with such a material.

(Example of exterior structure)
As shown in FIGS. 4 to 6, the exterior body 20 is provided with an elastic film 30 and an elongated elastic member 24 along the width direction between the first sheet layer 20A and the second sheet layer 20B, Elasticity in the width direction is provided. The planer shape of the exterior body 20 has a pseudo hourglass shape as a whole due to the concave leg surrounding lines 29 formed to form the leg openings on both sides of the middle. The exterior body 20 may be divided into two parts in the front and rear, and may be arranged so that both are separated at the crotch part in the front and rear direction.

  More specifically, in the exterior body 20 of the illustrated embodiment, the waist portion 23 has a waist portion 23 in a waist portion 23 of a waist portion T defined as a vertical range of the side seal portion 21 to which the front body F and the back body B are joined. An elastic member 24 is provided. The waist elastic member 24 in the illustrated form is an elongated elastic member such as a plurality of thread rubbers arranged at intervals in the longitudinal direction, and gives an elastic force so as to tighten around the body of the body. The waist elastic members 24 are not arranged close to each other and are substantially arranged as a single bundle. Instead, the waist elastic members 24 are spaced at intervals of about 3 to 8 mm so as to form a predetermined elastic zone, and three or more, preferably, Five or more are arranged. Although the elongation rate when the waist elastic member 24 is fixed can be determined as appropriate, it can be about 230 to 320% for a normal adult. As the waist elastic member 24, one or a plurality of belt-like elastic members may be used.

  As the waist elastic member 24, thread rubber is used in the illustrated example, but a tape-shaped elastic member may be used, for example. Alternatively, an elastic film described later may extend to the waist 23. . The waist elastic member 24 in the illustrated embodiment is sandwiched between the folded portion 20C formed by folding the constituent material of the second sheet layer 20B inward at the waist opening edge, and the constituent material of the first sheet layer 20A and the second member. It may be sandwiched between the components of the sheet layer 20B.

The constituent materials of the first sheet layer 20A and the second sheet layer 20B can be used without any particular limitation as long as they are sheet-shaped, but it is preferable to use a nonwoven fabric from the viewpoint of air permeability and flexibility. The material of the nonwoven fabric is not particularly limited. For example, synthetic fibers such as olefins such as polyethylene and polypropylene, polyesters and polyamides, regenerated fibers such as rayon and cupra, natural fibers such as cotton, and mixed fibers and composite fibers using two or more of these. And the like. Further, the nonwoven fabric may be manufactured by any processing. Examples of the processing method include known methods, for example, a spunlace method, a spunbond method, a thermal bond method, a melt blown method, a needle punch method, an air through method, a point bond method, and the like. When a nonwoven fabric is used, the basis weight is preferably about 10 to 25 g / m ² . In addition, the first sheet layer 20A and the second sheet layer 20B may be a pair of layers in which a part or the whole thereof is formed by folding a single material and facing each other.

  In the present embodiment, as shown in FIG. 2, the elastic film elastic structure 20 </ b> X is provided in the waistline region T of the front body F, the waistline region T of the backbody B, and the intermediate region L therebetween in the exterior body 20. Is formed. That is, in the elastic structure 20 </ b> X of the exterior body 20, an intermediate portion in the width direction including a portion overlapping the absorber 13 (a part or all of the overlapping portion may be included, and it is desirable to include substantially the entire interior body fixing portion 10 </ b> B). A non-stretchable region 70 is provided, and a portion up to the side seal portion 21 on both sides in the width direction is a stretchable region 80. As shown in FIG. 3, the elastic film 30 is laminated between the first sheet layer 20 </ b> A and the second sheet layer 20 </ b> B over the entire stretchable region 80 and the non-stretchable region 70. In a state where 30 is stretched in the width direction, the first sheet layer 20A and the second sheet layer 20B are in the stretching direction and the direction orthogonal thereto (the width direction and the front-rear direction in the pants-type disposable diaper as illustrated). Are joined through through holes 31 formed in the elastic film 30 at a large number of joints 40 arranged at intervals. In this case, it is desirable that the first sheet layer 20A and the second sheet layer 20B and the elastic film 30 (excluding a melt-solidified material described later) are not joined, but they can be joined.

  In the elastic region 80, as shown in FIG. 3D, in the natural length state of the elastic film 30, the first sheet layer 20A and the second sheet layer 20B between the joints expand in the direction in which the elastic film 30 separates from each other, and Wrinkles 25 extending in a direction intersecting with the wrinkles 25 are formed, and as shown in FIG. 3 (c), even in a mounted state where the wrinkles 25 extend to some extent in the width direction, the wrinkles 25 are stretched but remain. Further, as shown in the illustrated embodiment, the first sheet layer 20A and the second sheet layer 20B are not joined to the elastic film 30 except at least between the first sheet layer 20A and the second sheet layer 20B in the joint 40. As can be seen from FIG. 3 (c) assuming the mounted state and FIGS. 3 (a) and 3 (b) assuming the fully expanded state of the first sheet layer 20A and the second sheet layer 20B, in these states, the elastic film A gap is formed between the through-hole 31 of the joint at 30 and the joint 40, and even if the material of the elastic film 30 is a non-porous film or sheet, air permeability is added by the gap. The state of the shrinking wrinkles 25 in the mounted state and the natural length state also appears in the sample photographs of FIGS. The elastic limit elongation of the elastic region 80 can be adjusted by the area ratio of the joint portion 40. In a normal case, the elastic limit elongation in the elastic direction of the elastic region 80 is 200% or more (preferably 265 to 295%). It is desirable.

  Characteristically, as shown in FIG. 9, in the non-stretchable region 70, the area ratio of the joining portion 40 is higher than that in the stretchable region 80, and a part or all of the portion between the through holes 31 in the elastic film 30 is heated. Since the heat-deteriorated portion 32 has reduced elasticity due to deterioration, the elastic limit elongation in the stretching direction is 130% or less (preferably 120% or less, more preferably 100%). In the non-stretchable region 70, as can be seen from the sample photographs in FIGS. 13 and 14, a streaky bulging portion or an extremely small wrinkle is formed between the joining portions 40, but the area ratio of the joining portion 40 is very small. In addition, since the elastic film 30 is thermally degraded into the thermally degraded portion 32 at the portion between the joints 40, the elasticity is substantially eliminated. In addition, the continuity of the elastic film 30 in the stretchable region 80 and the non-stretchable region 70 can be maintained, and the appearance can be improved.

  The shapes of the individual joints 40 and the through holes 31 in the natural length state are arbitrary shapes such as polygons (including linear and rounded shapes) such as a perfect circle, an ellipse, and a rectangle, a star, and a cloud. It can be.

The size of the individual joints 40 may be appropriately determined, but if it is too large, the hardness of the joints 40 has a large effect on the feel, and if it is too small, the joint area is small and the materials cannot be bonded sufficiently. Therefore, in the normal case, it is preferable that the area of each joint portion 40 is about 0.14 to 0.75 mm ² . The area of the opening of each through-hole 31 may be equal to or larger than the joint because the joint is formed through the through-hole 31, but may be about 1 to 1.5 times the area of the joint 40. preferable. The area of the opening of the through hole 31 means a value in a state where the elastic structure 20X has a natural length, and the area of the opening of the through hole 31 is uniform in the thickness direction such that the front and back of the elastic film 30 are different. If not, it means the minimum value.

In addition, it is preferable that the area and the area ratio of the individual bonding portion 40 in each region are usually as follows.
(Non-stretchable area 70)
Area of the joint 40: 0.14 to 0.75 mm ² (particularly 0.14 to 0.35 mm ² )
Area ratio of the joint 40: 19 to 53%
(Elastic area 80)
Area of the joint 40: 0.14 to 3.5 mm ² (particularly 0.14 to 1.0 mm ² )
Area ratio of the joint 40: 1.8 to 19.1% (especially 1.8 to 10.6%)

  In order to make the area ratios of the joints 40 in the non-stretchable region 70 and the stretchable region 80 different as described above, the number of the joints 40 per unit area can be changed as shown in FIG. The area of each joint 40 may be changed as shown in FIG. In the former case, the area of the joint 40 can be the same in the non-stretchable region 70 and the stretchable region 80 or can be different. In the latter case, the number of the joints 40 per unit area is The elastic region 70 can be the same or different in the elastic region 80.

  The planar arrangement of the bonding portion 40 and the through-holes 31 can be determined as appropriate, but is preferably a planar arrangement that is regularly repeated, such as an oblique lattice shape as shown in FIG. Hexagonal lattices (these are also called staggered), square lattices as shown in FIG. 15C, rectangular lattices as shown in FIG. 15D, and parallel as shown in FIG. A body lattice (a form in which two groups of a large number of parallel oblique rows are provided so as to intersect with each other as shown in the figure), etc. (these are inclined at an angle of less than 90 degrees with respect to the stretching direction. In addition to those that are regularly repeated as described above, the groups of the joints 40 (the arrangement of the groups may be regular or irregular, and may be patterns or characters) may be repeated regularly. Can also. The arrangement of the joints 40 and the through holes 31 may be the same in the stretchable region 80 and the non-stretchable region 70, or may be different.

  As shown in FIG. 11, a non-stretchable region 70 in which, for example, the joint portion 40 is arranged in the form of a display 71 can be provided other than the portion overlapping the absorber 13. In addition, as the display 71, a display known in the field of absorbent articles, for example, a pattern for decoration (including a one-point picture or a character), a method of use or use assistance, a function display such as a size, A mark such as a product name and a characteristic function can be displayed. In the illustrated form, a flower pattern display 71 as a plant pattern is added, but it goes without saying that various patterns such as an abstract pattern, an animal pattern, and a natural phenomenon pattern can be used.

The elastic film 30 is not particularly limited, and may be used without particular limitation as long as it is a resin film which has elasticity itself and decreases in elasticity due to thermal deterioration. Examples thereof include a styrene-based elastomer, an olefin-based elastomer, and a polyester. One or a blend of two or more thermoplastic elastomers such as a system-based elastomer, a polyamide-based elastomer, and a polyurethane-based elastomer may be processed into a film by extrusion molding such as a T-die method or an inflation method. The elastic film 30 may be a non-porous film or a film having a large number of holes and slits for ventilation. In particular, the tensile strength in the stretching direction is 8 to 25 N / 35 mm, the tensile strength in the direction perpendicular to the stretching direction is 5 to 20 N / 35 mm, the tensile elongation in the stretching direction is 450 to 1050%, and the direction is perpendicular to the stretching direction. It is preferable that the elastic film 30 has a tensile elongation of 450 to 1400%. The tensile strength and the tensile elongation (elongation at break) were measured using a tensile tester (for example, AUTOGRAPH AGS-G100N manufactured by Shimadzu Corporation), except that the test piece was formed in a rectangular shape having a width of 35 mm and a length of 80 mm according to JIS K7127. : In accordance with 1999 "Plastic-Testing method for tensile properties-", it means a value measured at an initial chuck interval of 50 mm and a tensile speed of 300 mm / min. The thickness of the elastic film 30 is not particularly limited, but is preferably about 20 to 40 μm. The weight of the elastic film 30 is not particularly limited, but is preferably about 30 to 45 g / m ² , and particularly preferably about 30 to 35 g / m ² .

In the non-stretchable region 70, the joining of the first sheet layer 20A and the second sheet layer 20B in the joining portion 40 is performed as long as the elasticity of the elastic film 30 between the through holes 31 is partially or entirely reduced by thermal degradation. Is not particularly limited. For example, the bonding of the first sheet layer 20A and the second sheet layer 20B at the bonding portion 40 may be performed by a hot melt adhesive, or may be performed by bonding means such as heat sealing or ultrasonic sealing. When using joining means by material welding, as described in Patent Document 1, a through hole of an elastic film is formed by extrusion, and the first sheet layer 20A and the second sheet layer 20B are directly welded at the position of the through hole. Although they can be joined, they have low peel strength and may be peeled off when a strong force is applied. In the case of Patent Document 1, since the through holes of the elastic film are formed by extrusion, as shown in FIG. 8B, the elastic film 30 remains between the first sheet layer 20A and the second sheet layer 20B. Alternatively, there is a possibility that extruded fragments (not shown) remain movably around the through hole 31.
Therefore, when using the joining means by material welding, as shown in FIG. 8A, the joining of the first sheet layer 20A and the second sheet layer 20B at the joining portion 40 is at least performed by the first sheet layer 20A and the second sheet layer 20B. It is preferable that the elastic film 30 is formed by the molten and solidified product 30m over the second sheet layer 20B. When the first sheet layer 20A and the second sheet layer 20B are joined using the molten and solidified product 30m of the elastic film 30 as an adhesive as described above, the peel strength becomes high, so that both high air permeability and high peel strength can be achieved. Become.

  As shown in FIGS. 18 and 19, for example, such a joint structure can provide a substantially uniform elongation rate between the first sheet layer 20A and the second sheet layer 20B in a direction orthogonal to the direction of expansion and contraction. In a state where the elastic film 30 is sandwiched while being stretched in the expansion and contraction direction, and is welded in a predetermined pattern of the joint portion 40 between the expansion and contraction region 80 and the non-stretchable region 70, the elastic film 30 is melted at many places to form the through holes 31. At the same time, it is possible to simply and efficiently manufacture the first sheet layer 20A and the second sheet layer 20B at a position of the through hole 31 by joining at least the melt of the elastic film 30 to join the first sheet layer 20A and the second sheet layer 20B. In the stretchable region 80 and the non-stretchable region 70 manufactured by this method, in the natural length state, the shape and area of each joint 40 and the shape and area of each through hole 31 are substantially equal. Then, when welding the stretchable region 80 and the non-stretchable region 70 using this method, in the non-stretchable region 70, the area ratio of the joining portion 40 is set higher than that in the stretchable region 80, and the heat of welding is reduced in the elastic film 30. By transmitting a part or all of the portion between the through holes 31 to partially or entirely degrade the portion between the through holes 31 by the heat of welding to reduce the elasticity, the above-described thermally deteriorated portion 32 is formed. The non-stretchable region 70 can be formed. Therefore, the elastic film 30 elastic structure 20X having the elastic region 80 and the non-elastic region 70 can be manufactured very simply and efficiently. In addition, the manufactured elastic region 80 has both high air permeability and high peel strength.

  FIG. 18 shows an example of a method for manufacturing a pants-type disposable diaper. This production line has a lateral flow form in which the diaper width direction is the MD direction (machine direction, line flow direction), and the exterior body 20 is formed here, and the interior body 10 manufactured in another line is the exterior body. After being attached to the diaper 20, the diaper is folded at the center in the front-rear direction to join both sides of the front and rear exterior body 20 and is divided into individual diapers DP. In addition, in order to make the description easy to understand, the same names and reference numerals are used for the members that are continuous in the manufacturing process as those of the members after manufacturing.

  More specifically, this production line includes an exterior body assembly step 301, an interior body attachment step 302, a leg opening punching step 303, a folding step 304, and a side joining / separating step 305. The assembling process 301 is a characteristic process. That is, in the exterior body assembling step 301, the first sheet layer 20A and the second sheet layer 20B that are continuous in a band shape with a predetermined width are stuck together in the continuous direction, as shown in an enlarged manner in FIG. A state in which the elastic film 30 that is supplied to the sealing devices 60 and 61 and is continuous in a band shape with a predetermined width passes through the nip roll 90 having a lower feeding speed than the sealing devices 60 and 61 and is stretched in the MD direction due to a difference in speed. Is supplied to the sealing devices 60 and 61 so as to be sandwiched between the first sheet layer 20A and the second sheet layer 20B. In the illustrated embodiment, one sheet material is divided into two by the slitter 62 in order to separately supply the first sheet layer 20A, but separate sheet materials may be supplied before and after the first sheet layer 20A. Instead of separating the front and rear 20A, a front and back integrated sheet material may be supplied similarly to the second sheet layer 20B. Similarly, in the illustrated embodiment, one elastic film 30 is divided into two parts by the slitter 62 in order to separately supply the elastic film 30 before and after. However, separate elastic films 30 before and after the supply may be supplied. The elastic film 30 which is integral with the front and rear may be supplied without separating the film 30 from the front and rear.

  In the sealing devices 60 and 61, the seal roll 60 provided on the outer peripheral surface with a large number of pressurizing protrusions 60 p arranged in the pattern of the joints 40 in the above-described stretchable region 80 and the non-stretchable region 70 is disposed to face the seal roll 60. The first sheet layer 20A, the elastic film 30 extended in the MD direction, and the second sheet layer 20B are sandwiched by the anvil roll 61 having a smooth surface, and the pressing protrusion 60p is heated by heating the pressing protrusion 60p. Only at a portion pressed in the thickness direction between the elastic film 30 and the outer peripheral surface of the anvil roll 61, the through hole 31 is formed by melting the elastic film 30, and the first sheet layer 20A and the The two sheet layers 20B are joined by welding. Although the illustrated sealing devices 60 and 61 are assumed to be heat sealing devices, other devices such as an ultrasonic seal may be used.

  Thereafter, a pants-type disposable diaper can be formed by using a known manufacturing process. In the illustrated embodiment, the inner body 10 manufactured on a separate line is supplied to the outer body 20 formed by the sealing devices 60 and 61 at a predetermined interval in the MD direction in the inner body mounting step 302, The interior assembling bodies 10 and 20 are formed by being joined to the exterior body 20 by an appropriate means such as a melt adhesive or heat sealing, and then in a leg opening punching step 303, leg openings are sequentially formed by the cutter device 63. Then, after the interior assembled bodies 10 and 20 are folded at the center in the CD direction (horizontal direction orthogonal to the MD direction) in the folding step 304, they become both sides of each diaper DP in the side joining / separating step 305. The outer body 20 of the front body F and the outer body 20 of the back body B are joined to form a side seal portion 21 and a boundary of each diaper. And the outer package 20 is cut, the individual diapers DP is obtained.

When welding for forming the through hole 31 and the joint 40 is performed by using an ultrasonic seal (ultrasonic welding), and the heat is used to reduce the elasticity of the non-stretchable region 70, the speed of the production line is reduced. If the condition is slow (approximately 30 m / min), ultrasonic vibration is easily transmitted, and the area of the individual joints 40 in the non-stretchable region 70 is increased to a certain extent to ensure a sufficient thermal degradation area of the elastic film 30. However, when the speed of the production line is high (about 120 m / min), the welding of the joints 40 may be insufficient unless the area of each joint 40 is reduced to some extent. However, if the area of the joint portion 40 is simply reduced in order to sufficiently weld the joint portion 40, there is a possibility that the heat-deteriorated area of the elastic film 30 is insufficient to make the elastic film 30 non-stretchable. On the other hand, as described above, when the area of the joint 40 in the non-stretchable region 70 is 0.14 to 0.75 mm ² and the area ratio of the joint 40 in the non-stretchable region 70 is 19 to 53%. The ultrasonic welding is performed by arranging the small joining portions 40 at high density at a small interval, and there is little possibility that the welding becomes insufficient, and the thermal degradation area of the elastic film 30 is reduced. Is also narrow, so that it does not expand and contract sufficiently. The area of the joint 40 in the non-stretchable region 70 is 0.14 to 0.75 mm ² , and the distance (CD) between the stretch and contraction direction (MD direction) of the joint 40 in the non-stretchable region 70 is 40 m. The same applies to the case where the distances 40c in the directions are 1 mm or less.

  When welding for forming the through hole 31 and the joint portion 40 is performed by using an ultrasonic seal (ultrasonic welding), and the heat of the welding is used to reduce the elasticity of the non-stretchable region 70, the joint portion 40 may be used. 12B, that is, the shape of each welded portion of the welding pattern in the ultrasonic welding is long in the MD direction as shown in FIGS. 12B and 12C, compared with the isotropic shape having the same area, The area of the elastic film 30 that has been thermally degraded can be increased, and the area to which ultrasonic vibrations are simultaneously applied does not increase as compared with the shape long in the CD direction as shown in FIG. Has the advantage that it is hard to be insufficient. Note that the shape that is long in the MD direction is, for example, a polygon such as an ellipse whose major axis is less than 45 degrees in the MD direction, a rectangle whose long side is less than 45 degrees in the MD direction (linear or rounded corners). And a cloud shape whose longitudinal direction is less than 45 degrees with respect to the MD direction.

  As described above, when the joint 40 and the through-hole 31 are simultaneously formed by welding, the melting point of the elastic film 30 and the melting points of the first sheet layer 20A and the second sheet layer 20B, and the processing temperature at the welding point may vary. Although the relationship can be appropriately determined, the melting points of the first sheet layer 20A and the second sheet layer 20B are set to be equal to or lower than the melting point of the elastic film 30, and the whole of the first sheet layer 20A and the second sheet layer 20B and the elastic The melting point of the first sheet layer 20A and the second sheet layer 20B is higher than the melting point of the elastic film 30, and the elastic film 30 It is preferable that the first sheet layer 20A and the second sheet layer 20B do not partially or entirely melt while being melted. That is, in the latter case, as can be seen from FIGS. 16 and 17, the fibers 20f of the first sheet layer 20A and the second sheet layer 20B continuous from the periphery of the joint 40 remain, and the first sheet layer 20A and The first sheet layer 20A and the second sheet layer 20B are joined by the molten and solidified product 30m of the elastic film 30 that has permeated and solidified over the second sheet layer 20B, and has an elasticity with respect to the first sheet layer 20A and the second sheet layer 20B. Not only is the bite of the melt-solidified product 30m of the film 30 good, but also the strength of the first sheet layer 20A and the second sheet layer 20B is not easily reduced, so that the peel strength is further improved. In order that the first sheet layer 20A and a part of the second sheet layer 20B do not melt, the core (including the central part of the monocomponent fiber as well as the core in the composite fiber) remains for all the fibers at the joint. The surrounding part (including not only the sheath of the conjugate fiber but also the surface layer side of the monocomponent fiber) melts, or some of the fibers do not melt at all, but the rest of the fibers melt completely or the core remains However, the surrounding portion includes a form in which it melts.

  From such a viewpoint, the melting point of the elastic film 30 is preferably about 80 to 145 ° C, and the melting points of the first sheet layer 20A and the second sheet layer 20B are about 85 to 190 ° C, particularly about 150 to 190 ° C. The difference between the melting points of the first sheet layer 20A and the second sheet layer 20B and the elastic film 30 is preferably about 60 to 80 ° C.

  The examples shown in FIGS. 1 and 2 and the like are examples in which the elastic film elastic structure 20X is applied to the elastic structure other than the waist portion 23 of the exterior body 20, but as in the example shown in FIG. Appropriate changes may be made such as applying or including such a form that the elastic film elastic structure 20X is not provided in the intermediate region L between the waist circumference region T of the front body F and the waist circumference region T of the back body B. It is possible. In addition, the above-mentioned elastic structure 20X is applicable not only to pants-type disposable diapers, but also to other elastic parts such as a waist around a tape-type disposable diaper, fastening tape, three-dimensional gathers, planar gathers, and the like, which are widely used in absorbent articles in general. Can also be applied. In the present embodiment, the non-stretchable region 70 is provided. However, the entire elastic film 30 stretchable structure 20 </ b> X may be configured as the stretchable region 80, and the non-stretchable region 70 may be omitted. Furthermore, although the expansion and contraction direction is the width direction in the illustrated example, the expansion and contraction direction may be the front and rear direction, or both the width direction and the front and rear direction.

(Front and back holding sheet)
As shown also in FIGS. 1 and 4, the front and rear holding sheets cover the front and rear ends of the interior body 10 attached on the inner surface of the exterior body 20 and prevent leakage from the front and rear edges of the interior body 10. 50 and 60 may be provided. Explaining the illustrated form in more detail, the front pressing sheet 50 extends over the entire width direction from the inner surface of the folded back portion 20C at the waist side end of the inner surface of the front body F to a position overlapping the front end of the interior body 10. The rear pressing sheet 60 extends over the entire width direction from the inner surface of the folded portion 20C at the waist side end of the inner surface of the rear body B to a position overlapping the rear end of the interior body 10. If a slight non-adhesive portion is provided over the entire crotch-side edge of the front and rear holding sheets 50 and 60 in the width direction (only the central portion may be provided), not only the adhesive does not protrude but also this portion is removed from the topsheet 11. It can be slightly lifted to function as a leak-proof wall.

  When the front and rear holding sheets 50 and 60 are attached separately as in the illustrated embodiment, there is an advantage that the degree of freedom of material selection is increased, but there are also disadvantages such as an increase in materials and manufacturing processes. Therefore, the folded portion 20 </ b> C formed by folding the outer body 20 on the inner surface of the diaper can be extended to a portion overlapping the inner body 10 to form a portion equivalent to the pressing sheets 50 and 60 described above.

<Formation test of non-stretchable area>
As the first sheet layer 20A and the second sheet layer 20B, PE / PP composite fibers having a fineness of 1.7 to 1.9 dtex (core: polypropylene (melting point: 165 ° C), sheath: polyethylene (melting point: 130 ° C)) are used as raw materials. A spunbond nonwoven fabric having a basis weight of 17 g / m ² , and MD3 (trade name: 35 g / m ² , thickness: 0.04 mm, melting point: 90 to 100 ° C.) manufactured by Exten, as the elastic film 30, are used for MD of the nonwoven fabric. With the elastic film stretched 3.5 times in the MD direction so that the direction becomes the stretching direction, the length in the MD direction is 40 m in the pattern shown in FIG. 12B and at various intervals shown in Table 1. The rectangular joint 40 having a length of 1 mm, a length 40c in the CD direction of 0.5 mm, and an area of 0.5 mm ² was formed by ultrasonic sealing, and the elastic limit elongation was measured. The ultrasonic seal was set based on the conditions under which the elastic film and the PE layers of the fibers of the first sheet layer and the second sheet layer melted. As a result, as shown in Table 1, when the distance between the joints in the MD direction is 1 mm or less and the distance in the CD direction is 1 mm or less, the stretch between the through-holes is deteriorated due to thermal deterioration of most of the through holes, It was found to be non-stretchable.

<Description of terms in the specification>
The following terms in the specification have the following meanings unless otherwise specified in the specification.
-"Elongation rate" means the value when the natural length is 100%.
・ "Cost" is measured as follows. After pre-drying the sample or test piece, the sample or test piece is left in a test room or apparatus in a standard condition (the test place is at a temperature of 20 ± 5 ° C. and a relative humidity of 65% or less) to make it a constant weight. Predrying refers to making a sample or a test piece a constant weight in an environment where the relative humidity is 10 to 25% and the temperature does not exceed 50 ° C. Preliminary drying may not be performed for fibers having an official moisture content of 0.0%. A sample having a size of 200 mm × 250 mm (± 2 mm) is cut from a test piece in a constant weight state using a rice tsubomi (200 mm × 250 mm, ± 2 mm). The weight of the sample is measured, and the weight per square meter is calculated and used as the basis weight.
- "thickness" is used automatic thickness measuring instrument (KES-G5 Handy Compression measurement program), load: 0.098 N / cm ^2, and the pressure area: automatically measured under the conditions of 2 cm ^2.
-If there is no description of environmental conditions in tests and measurements, the tests and measurements shall be performed in a test room or apparatus under standard conditions (test location: temperature 20 ± 5 ° C, relative humidity 65% or less). .

  INDUSTRIAL APPLICABILITY The present invention can be used for general absorbent articles having a stretchable structure, such as various types of disposable diapers such as a tape type and a pad type, sanitary napkins, etc., in addition to the pants type disposable diapers as described above.

  B: back body, F: front body, T: waist area, L: middle area, 10: interior body, 11: top sheet, 12: liquid-impermeable back side sheet, 13: absorber, 13N: constricted portion , 14: packaging sheet, 15: gather nonwoven fabric, 16: gather elastic member, 20: exterior body, 20A: first sheet layer, 20B: second sheet layer, 20C: folded portion, 20X: elastic structure, 21: side seal Part, 24 ... waist elastic member, 25 ... shrinking wrinkle, 29 ... leg circumference line, 30 ... elastic film, 31 ... through hole, 32 ... heat degraded part, 40 ... joint, 70 ... non-stretchable area, 71 ... display , 80...

Claims (4)

An elastic film is laminated between a first sheet layer and a second sheet layer, and the elastic film can expand and contract in the expansion and contraction direction, and the first and second sheet layers are in the expansion and contraction directions. And, with a large number of joints arranged at intervals in a direction orthogonal to this, and joined through a through hole formed in the elastic film, comprising an elastic film stretchable structure,
The region having the elastic film stretchable structure has a non-stretchable region and a stretchable region that is provided on at least one side in the stretchable direction of the non-stretchable region and that can be stretched in the stretchable direction.
In the non-stretchable region, the area ratio of the joint portion is 19 to 53%, and the elasticity of the elastic film is partially or entirely reduced by thermal degradation, thereby reducing the elasticity. direction of the elastic limit elongation are 130% or less,
The shape of the joint is a shape long in the MD direction,
An absorbent article characterized by the above. An elastic film is laminated between a first sheet layer and a second sheet layer, and the elastic film can expand and contract in the expansion and contraction direction, and the first and second sheet layers are in the expansion and contraction directions. And, with a large number of joints arranged at intervals in a direction orthogonal to this, and joined through a through hole formed in the elastic film, comprising an elastic film stretchable structure,
The region having the elastic film stretchable structure has a non-stretchable region and a stretchable region that is provided on at least one side in the stretchable direction of the non-stretchable region and that can be stretched in the stretchable direction.
In the non-stretchable region, the area of the joining portion is 0.14 to 0.75 mm ² , and the spacing of the joining portion in the stretching direction and the spacing in the direction orthogonal to the stretching direction are each 1 mm or less, Since a part or all of the portion between the through holes in the elastic film is reduced in elasticity due to thermal deterioration, the elastic limit elongation in the stretching direction is 130% or less.
An absorbent article characterized by the above.   The absorbent article according to claim 2, wherein the shape of the joint is long in the MD direction. An exterior body constituting the front body and the back body, and an interior body including an absorber fixed to the inner surface of the exterior body, including both sides of the exterior body in the front body and both sides of the exterior body in the back body. Are joined to form a side seal portion, the waist opening and a pair of left and right leg openings are formed, and a pants-type disposable diaper,
The exterior body in at least one of the front body and the back body extends in the width direction corresponding to the space between the side seal portions in at least a part of the front-rear direction, and the elastic film elastic structure has the elastic direction in the width direction. It is prepared so that
Among the regions having the elastic film stretching structure, the non-stretching region is provided in a region overlapping with the absorber, and the stretching region is provided on both sides in the width direction.
The absorbent article according to claim 1.