JP2003041470A - Elastic composite sheet and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastic composite sheet suitable for the production of a disposable diaper having elastic elongation in the girth direction. SOLUTION: This elastic composite sheet 11 usable as a back sheet 3 of the disposable diaper is formed by intermittently attaching the second sheets 22 inelastically extensible in the girth direction to at least one surface of the first sheet 21 elastically extensible in the girth direction. The second sheet 22 is an assembly of filaments, and has a uniform weight. The apparent density of the second sheet 22 in the direction orthogonal to the girth direction is changed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an elastic composite sheet suitable for use in disposable wearable articles such as disposable diapers and a method for producing the same.

[0002]

In Japanese Patent Laid-Open No. 4-227260, an elastically stretchable film and an elastically stretchable nonwoven fabric are bonded as a liquid-impervious leakproof sheet used as a backsheet of a disposable body fluid treatment product. Things are disclosed. An example of a body fluid treatment article is a pants-type diaper, and for the top sheet of this diaper, for example, a liquid-permeable and elastically stretchable nonwoven fabric is used, and a liquid-absorbent material is provided between the top sheet and the back sheet. The core intervenes. The diaper thus formed is elastically extendable in the waistline direction, for example, and fits well around the waistline when worn.

[0003]

In the diaper that uses the elastically stretchable back sheet and top sheet as in the conventional example and has elastic stretchability in the waist circumference direction, If the backsheet and topsheet are low in elongation stress so that they fit loosely, that is, they are easily stretched, the crotch region of the diaper is also likely to be stretched,
When the core absorbs body fluid and becomes heavier, it may easily sag. When the diaper is in such a state, the crotch region may be separated from the wearer's legs and the body fluid may be easily leaked, or the wearer's gait may be hindered.

An object of the present invention is to provide an elastic composite sheet which can solve the problems of the conventional example and a method for manufacturing the elastic composite sheet.

[0005]

The present invention for solving the above problems comprises a first invention relating to an elastic composite sheet and a second invention relating to a method for producing the sheet.

The first aspect of the present invention is applicable to at least one surface of the first sheet that is elastically extendable in at least one of the two directions orthogonal to each other and is inelastically extendable in at least one direction in the one direction. The second sheet is an elastic composite sheet which is intermittently joined in the one direction.

In the elastic composite sheet, the first
The invention is characterized in that the second sheet has a uniform basis weight, and the apparent density changes in the direction orthogonal to the one direction.

The second aspect of the present invention is directed to at least one surface of the first sheet that is elastically stretchable in at least one of the two directions orthogonal to each other, and is inelastic in the one direction. A stretchable second sheet is intermittently joined in the one direction, and a composite sheet is stretched in the one direction,
Then, the elastic composite sheet is contracted by the elastic restoring force of the first sheet to produce an elastic composite sheet.

In this manufacturing method, the second aspect of the invention is characterized as follows. The composite sheet has both side edge portions extending in a direction orthogonal to the one direction, grips the both side edge portions, is within the elastic limit of the first sheet, and is less than or equal to a breaking elongation and the second sheet. The elastic composite sheet is stretched and shrunk in the one direction at a breaking elongation or less. At least one of the both side edge portions is gripped so that a non-grip portion exists between the grip portion and the grip portion in the orthogonal direction.

The first invention has the following preferred embodiments. (1) The elastic extensional stress of the elastic composite sheet in the one direction is high in the portion having a high apparent density and low in the portion having a low apparent density in each of the directions orthogonal to the one direction. It changes in the part. (2) In the elastic composite sheet, in a direction orthogonal to the one direction, a portion in which the extension stress in the one direction gradually increases as the extension rate increases and then increases rapidly, and an extension rate. , And a portion that changes so as to increase rapidly with the increase of. (3) The disposable diaper has a skin contacting surface and a clothing contacting surface, and one of these two surfaces is formed by the elastic composite sheet, and the one direction of the elastic composite sheet coincides with the width direction of the diaper. I am allowed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The elastic composite sheet according to the present invention and the manufacturing method thereof will be described in detail below with reference to the accompanying drawings.

1 and 2 are a perspective view of a pants-type disposable diaper 1 in which an elastic composite sheet 11 is used as a back sheet 3, and an exploded perspective view of the diaper 1. Diaper 1
2 is a top sheet 2 having an hourglass shape in FIG.
A back sheet 3 and a liquid-absorbent core 4 interposed between the two sheets 2 and 3. The two sheets 2 and 3 have the same shape and the same size, and overlap each other at a portion extending from the peripheral edge of the core 4 to be joined to each other, and form a front waist region 6, a back waist region 7, and a crotch region 8 of the diaper 1. Is formed. Front and back waist area 6,7
Are overlapped with the top sheet 2 as the inner side, and the side edge portions 17 and 18 are joined to each other at a welding portion 9 which is intermittently formed in the vertical direction. Diaper 1 has a waist opening 1
2 and a pair of leg-surrounding openings 13, and the waist elastic member 14 and the leg-surrounding elastic member 16 extend in the circumferential direction of the openings 12 and 13 at the edges of the respective openings 12 and 13. These elastic members 14 and 16 are between the top sheet 2 and the back sheet 3 and are joined to at least one of the sheets 2 and 3 in an extended state.

In the diaper 1 thus formed, the top sheet 2 and the back sheet 3 are elastically extendable in the width direction of the diaper 1. The back seat 3 is formed such that the front and rear waist regions 6, 7 are more easily stretched in the width direction than the crotch region 8, and the entire top sheet 2 is stretched more than the front and rear waist regions 6, 7 of the back seat 3. Easily or equally easily stretchable. In the diaper 1, when the diaper 1 is worn, the top sheet 2 and the back sheet 3 elastically and easily extend in the waist circumference direction, that is, in the width direction of the diaper 1 in the front and rear waist areas 6, 7 to wear the wearer. Fits around the torso. On the other hand, in the crotch region 8, the top sheet 2 and the back sheet 3 are hardly stretched, or even if they are stretched, they are not as wide as those in the front and rear waist regions 6 and 7 and do not easily stretch. Such a diaper 1
Then, even if the core 4 absorbs body fluid and becomes heavy, the crotch region 8
Does not easily hang down.

The top sheet 2 is liquid-permeable and can be obtained by a nonwoven fabric having elastic stretchability or a perforated plastic film. In this case, the non-woven fabric may be elastic fibers made of urethane or the like, crimped fibers or crimped composite fibers, and the film may be made of plastic elastomer or the like.

The backsheet 3 is liquid impermeable and has a straight side edge 1 extending in the front-rear direction of the diaper 1 in FIG.
7, 18 and a curved edge portion 26 for forming the leg opening 13, and front and rear end edge portions 19a, 19b extending in the width direction.
An elastic composite sheet 11 (see FIG. 2) in which a first sheet 21 located inside of the diaper 1 and a second sheet 22 located outside of the diaper 1 are laminated and joined at a number of welding sites 23. Has been formed. The first sheet 21 has elastic extensibility in the width direction of the diaper 1 and is formed of a nonwoven fabric or a plastic film. In the figure, a liquid impermeable film is used to make the back sheet 3 liquid impermeable. The second sheet 22 is an aggregate of continuous fibers 24, and when the first sheet 21 elastically extends in the width direction of the diaper 1, the second sheet 22 is inelastically expanded in the width direction of the diaper 1 accompanying it. When the first sheet 21 elastically contracts, the second sheet 2 is accompanied by the contraction.
2 also contracts. In the contraction of the second sheet 22, the continuous fibers 2
4 is bent between the welded portions 23 and 23.

FIG. 3A shows the backsheet 3 of FIGS.
FIG. 3 is a perspective view of a material sheet 30 used to obtain the elastic composite sheet 11 forming the, and (b) is a perspective view of the elastic composite sheet 11 obtained from the material sheet 30, that is, the back sheet 3. . (B) is also an enlarged view of the back sheet 3 of FIG. 1. The material sheet 30 includes the first sheet 21, the second sheet 22 and the welding portion 23 of the back sheet 3.
The first layer 31, the second layer 32, and both layers 3 corresponding to
1 and 32 are joined together by a welded portion 33, and the side edge portions 17 and 18 and the front and rear edge portions 19a and 19b of the back sheet 3
And the side edge portions 47, 48 and the front and rear edge portions 49a, 4 corresponding to
9b and a curved edge portion 46 corresponding to the leg edge portion 26. The first layer 31 is 100% or more in the double-headed arrow A direction corresponding to the width direction of the diaper 1, and more preferably 200.
% Or more, and more preferably 400% or more, is formed by a film 35 having a thickness of 5 to 100 μm and capable of elastic expansion. The second layer 32 is made of polyethylene, polypropylene, an ethylene-propylene copolymer, an ethylene-propylene-butene copolymer, a mixture of two or more kinds of these polymers, or the like, and a continuous fiber 34 having a fiber diameter of 0.1 to 50 μm.
And is formed of a fiber aggregate having a basis weight of ^{2 to} 100 g / m ² . However, in the figure, only some of the continuous fibers 34 are shown. The breaking elongation of the continuous fibers 34 is preferably 200% or more. Film 35
It is preferable that the area 33 where the continuous fiber 34 and the continuous fiber 34 are bonded has an area of 0.03 to 10 mm ² , and the ratio of the whole area to the area of the film 35 is 1 to 50%. The material sheet 30 has a double-headed arrow A
After being stretched in the direction, the elastic composite sheet 11 that can be used as the back sheet 3 in FIG. 3B is obtained by contracting with the elastic restoring force of the film 35.

FIG. 4 is a stretcher 50 used to stretch the material sheet 30 of FIG. 3 into the elastic composite sheet 11.
FIG. The extender 50 includes a pair of upper and lower chucks 5.
1, 52, an upper cylinder 53 extending upward from the chuck 51, and a lower cylinder 54 extending downward from the chuck 52. The upper cylinder 53 and / or the lower cylinder 54 can move up and down in the double-headed arrow B direction,
The chucks 51 and 52 are provided on both side edges 4 of the material sheet 30.
7, 48 can be gripped. However, the curved edge portion 46 is not gripped. In the illustrated example, the lower cylinder 54 is kept stationary and only the upper cylinder 53 is raised to extend the material sheet 30 upward by a required magnification in the width direction of the drawing, and then lowered to the original position. Release the grip of the chucks 51 and 52. The contracted material sheet 30 becomes the elastic composite sheet 11 (backsheet 3) in FIG. 3B when the portion held by the chucks 51 and 52 is cut off.

In FIG. 4, the stretching amount of the material sheet 30 by the stretching machine 50 is within the elastic limit of the film 35 and below the breaking elongation and below the breaking elongation of the continuous fiber 34. The continuous fiber 34 changes its direction in the double-headed arrow B direction between the welded portions 33 and 33 where it is bonded to the film 35, and inelastically expands while reducing its diameter. It remains as a permanent deformation of 34. When lowering the cylinder 53 of the extender 50,
The material sheet 30 contracts by the elastic restoring force of the film 35 to the state of the solid line in FIG. In such an expansion / contraction process, in the material sheet 30, the portion 37 between the side edge portions 47 and the portion 38 between the side edge portions 48 which are gripped by the upper and lower chucks 51 and 52 are located in the upper cylinder 53.
Is extended by an amount equal to the rising amount of
Curved edge 46 that was not directly gripped at 2
The portion 39 between them is hardly stretched due to the tension applied to the material sheet 30 generated when the upper cylinder 53 is lifted up, and is hardly stretched or slightly stretched as compared with the portions 37 and 38. As a result, the continuous fibers 34 are
When the material sheet 30 contracts at 38 and contracts,
The second layer 32 increases the apparent bulk of these portions 37, 38. However, the continuous fibers 34 in the other part 39 do not extend long, and when the material sheet 30 contracts,
The apparent bulk of the portion 39 of the second layer 32 is the same as that before the extension, or is almost not higher than that before the extension. In the second layer 32 before stretching, the continuous fibers 34 are uniformly distributed and the basis weight is uniform, and in the second fiber layer 32 after stretching,
The apparent density is low in the parts 37 and 38, and the apparent density is almost unchanged in the part 39. These parts 37, 38 become the front and rear waist regions 6, 7 of the elastic composite sheet 11 (back seat 3), and the part 39 becomes the crotch region 8. As is apparent from FIG. 3B, the second layer 32
A difference in shading due to the continuous fibers 34 occurs between the front and rear waist regions 6, 7 and the crotch region 8 in which the bulk of the is relatively changed.

In the present invention, the diaper 1 shown in the drawing is
This can be used as training pants, and in that case, the elastic composite sheet 11 used as the back sheet 3 can be changed from a liquid impermeable one to a liquid permeable one. Although the training pants thus obtained depend on the absorption capacity of the core 4, if the wearer leaks urine during training, a part of the urine exudes to the outside of the pants and causes discomfort to the wearer. , There is a thing to improve the training effect. In addition, the diaper 1 in the illustrated example is
It is also possible to use a known or well-known urine absorbing pad as a pad holder for bringing it into close contact with the body. If the urine collecting pad in this case has a leakproof structure, the diaper 1
Then, the core 4 can be removed, or the back sheet 3 can be made liquid-permeable. When the core 4 is removed, the topsheet 2 can be removed together. When the pants-type diaper 1 is used as these training pants or pad holders and the liquid permeable elastic composite sheet 11 is allowed to be used, instead of the first sheet 21 made of the film 35 illustrated in FIG. It is possible to use the first sheet 21 made of a fiber assembly that is elastically stretchable to the same extent as the film 35. This fiber assembly includes spunbonded nonwoven fabrics and meltblown nonwoven fabrics obtained by using long fibers or continuous fibers made of elastic polymers such as styrene elastomer and urethane. The basis weight of the fiber assembly is preferably 15 to 250 g / m ² .

In the present invention, in addition to the illustrated example, FIG.
The raw material sheet 30 is made of continuous fibers 3 on the lower surface side of the first layer 31.
It is also possible to provide an extensible third layer composed of 4 and obtain a backsheet 3 having a three-layer structure from the material sheet. Between the third layer and the second layer 32, the properties and basis weight of the continuous fiber can be changed.

FIG. 5 shows the first part of the material sheet 30 of FIG.
1 layer 31 is made of elastically extensible fiber aggregate,
In addition, on the lower surface side of the first layer 31, a third layer having the same structure as the second layer 32 is formed.
The material sheet 30 provided with layers is stretched by the stretching machine 50 shown in FIG.
Of the elastic composite sheet 11 (back sheet 3) obtained by
It is a force / strain curve. Material sheet 30 and expanded
The conditions at this time are as follows. 1.Material sheet composition 1) First layer Fiber made of styrene elastomer
Nonwoven fabric of fibers having a diameter of 15 μm 2) Second layer Fiber diameter 12μ made of polypropylene
m continuous fiber aggregate 3) 3rd layer Same as 2nd layer 4) Basis weight First layer: Second layer: Third layer = 45: 1
5:15 (g / m^Two) 5) Joining of each layer Welding at 106 ° C, welding area ratio 11% 6) Elongation at break 300% 7) Sample shape Width (vertical direction in Fig. 5) 150 x length (Fig.
5 lateral direction) 250 mm curved portion R = 30 mm 2.Tensile conditions 1) Distance between chucks 130 mm, pulling speed 130 mm
/ Min 2) Tensile speed 130mm / min 3) Growth rate 100% 3.Tensile test results An elastic composite sheet obtained by stretching and contracting the material sheet 30.
For the part 11, the odors at the parts L, M, N shown in FIG.
25mm in width and 50mm in length are sampled.
Distance between chucks is 30mm, pulling speed is 30mm / min
The result of the tensile test in Fig. 5 was as shown in Fig. 5.

As shown in FIG. 5, when the elastic composite sheet 11 is pulled in the width direction of the sheet 11 where the portions L and M that were directly gripped by the chucks 51 and 52 are pulled, the tensile stress gradually increases. After it becomes large, it changes so as to increase rapidly. At the portion N that was not directly gripped by the chucks 51 and 52, the tensile stress rapidly increases when the sheet 11 is pulled in the width direction. That is, in the elastic composite sheet 11, the parts L and M are likely to be elongated and the part N is difficult to be elongated in the initial stage of elongation. These parts L and M are shown in FIG.
In (a), corresponding to sites 37 and 38, N is site 3
Corresponds to 9. Regarding the back sheet 3,
The parts L and M correspond to the front and rear waist regions 6 and 7, and the part N corresponds to the crotch region 8.

In the material sheet 30, the higher the elongation rate in the width direction in FIG. 4, the longer the continuous fibers 34 extend and the larger the permanent deformation amount becomes. Therefore, in the elastic composite sheet 11 obtained after the contraction of the sheet 30, In the initial stage, only the force required to stretch the elastic first sheet 21 is sufficient to stretch the sheet. However, when the continuous fibers 34 of the second sheet 22 and / or the first sheet 21 are further expanded and become in a fully expanded state, it is necessary for the subsequent expansion stress to expand the continuous fibers 34. When a force is applied, the stress / strain curve rises sharply as indicated by L and M in FIG.

As is apparent from FIGS. 4 and 5, in the present invention, when the side edges 46, 47, 48 of the material sheet 30 are gripped by the chucks 51, 52, the side edges 4 of the material sheet 30.
6, 47 and 48, a non-grasping portion (curved edge portion 4) is provided between the gripping portion (side edge portion 47) and the gripping portion (side edge portion 48).
6) is interposed, in other words, the side edge portion 46,
Since the material sheet 30 is stretched in the width direction (upward in the drawing) by gripping the gripping portions (47, 48) along 47, 48 in an intermittently arranged manner, the elastic composite sheet obtained after the stretching. In No. 11, the extension stress in the width direction changes in each part in the length direction orthogonal to the width direction. The elastic composite sheet of the present invention having such a change can be obtained by intermittently gripping only one of the opposite side edges of the material sheet.

As described above, the elastic composite sheet according to the present invention, in which the stretching stress in the width direction of the elastic composite sheet is different in each part in the longitudinal direction, is used in pants-type disposable diapers, training pants, and pants as a urine absorbing pad holder. In addition, it can be used for open-type disposable diapers and various other disposable wearing articles.

[0026]

The elastic composite sheet obtained by the manufacturing method according to the present invention can be elastically stretched in one direction and the stretching stress changes in the direction orthogonal to the one direction. When it is used for a wearing article of a mold, the stretching stress in the width direction of the article can be lowered in the waist region of the article, and the stretching stress in the width direction of the article can be increased in the crotch region.

[Brief description of drawings]

FIG. 1 is a perspective view of a disposable diaper.

FIG. 2 is an exploded view of the diaper of FIG.

FIG. 3A is a perspective view of a material sheet for making a backsheet. (B) An enlarged perspective view of a back sheet.

FIG. 4 is a side view of the extender.

FIG. 5 is a stress / strain curve of an elastic composite sheet.

[Explanation of symbols]

1 diaper 11 Elastic composite sheet 21 First Sheet 22 Second sheet 30 Composite sheet (material sheet) 46 Edge, non-grasping part 47 Edge and grip 48 edge, grip

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI theme code (reference) // A61F 5/44 D06M 17/00 B (72) Inventor Satoshi Mitsuno Wadahama Takasuka, Wadahama, Toyohama-cho, Mitoyo-gun, Kagawa Prefecture 1531-7 Unicharm Co., Ltd. Technical Center (72) Inventor Hiroki Goda 1531-7 Takada Wadahama, Toyohama Town, Mitoyo-gun, Kagawa 1531-7 Unicharm Co., Ltd. Technical Term F-term (reference) 3B029 BB02 BB05 BC02 BC05 4C098 AA09 CC02 CC08 CC12 CC14 DD03 DD10 DD22 DD23 DD25 4L032 AA05 AB04 AC02 AC04 BA05 BD01 DA00 EA00 4L047 AA13 AA14 BA07 BA08 BB01 BB08 CA05 CB10 CC04

Claims (5)

[Claims] 1. A second sheet, which is elastically stretchable in at least one of two mutually orthogonal directions, has a second sheet which is inelastically stretchable in the one direction on at least one surface of the first sheet. In the elastic composite sheet, the second composite sheet has a uniform basis weight, and the apparent density is changed in a direction orthogonal to the one direction. . 2. A direction orthogonal to the one direction such that the elastic extensional stress of the elastic composite sheet in the one direction is high at the portion having a high apparent density and is low at the portion having a low apparent density. The elastic composite sheet according to claim 1, wherein the elastic composite sheet is changed in each part. 3. The elastic composite sheet, in a direction orthogonal to the one direction, a portion in which the elongation stress in the one direction gradually increases with an increase in the elongation rate and then changes so as to rapidly increase. 2. A portion that changes so as to increase rapidly as the elongation rate increases.
Alternatively, the elastic composite sheet described in 2. 4. A disposable diaper has a skin contacting surface and a clothing contacting surface, and one of these two surfaces is formed by the elastic composite sheet, and the one direction of the elastic composite sheet is the width direction of the diaper. The elastic composite sheet according to any one of claims 1 to 3, which is matched with. 5. A second sheet inelastically extensible in one direction is provided on at least one surface of a first sheet elastically extensible in at least one direction out of two directions orthogonal to each other. A method for producing an elastic composite sheet from the composite sheet by extending the composite sheet formed by intermittently joining in the one direction, and then contracting the elastic sheet by the elastic restoring force of the first sheet, wherein the composite sheet is: It has both side edges extending in a direction orthogonal to one direction, and grips the both side edges to be within the elastic limit of the first sheet and not more than the breaking elongation of the second sheet and not more than the breaking elongation of the second sheet. The elastic composite sheet is stretched / contracted in one direction, and at least one of the both side edges is gripped so that a non-gripping portion exists between the gripping portions in the orthogonal direction. It said how.