JP2023153503A - Composite sheet and absorbent article - Google Patents

Abstract

To provide a composite sheet excellent in air permeability, moisture permeability, leakage prevention property, elasticity, touch feeling, and appearance.SOLUTION: In a composite sheet 1 of the present invention, an elastic moisture permeable film 2 having a minute hole and a non-elastic non-woven fabric 3 overlap each other and are bonded to each other with a plurality of bonding parts 4 dispersed between overlapping surfaces. The moisture permeable film 2 can extend, and a non-bonding part 31 with the moisture permeable film 2 in the non-woven fabric 3 extends according to extension of the moisture permeable film 2. In a natural state of the moisture permeable film 2, the non-bonding part 31 of the non-woven fabric 3 projects to the side opposite to the moisture permeable film 2 side to form a part or overall of a projection 5.SELECTED DRAWING: Figure 1

Description

The present invention relates to a stretchable composite sheet in which a stretchable porous moisture-permeable film and a non-stretchable nonwoven fabric are laminated and integrated.

As a moisture permeable film, a resin moisture permeable film having micropores is known. Such a moisture-permeable film is generally produced by stretching a resin film containing fillers and additives to form a large number of micropores. Patent Document 1 describes a moisture-permeable film containing linear low-density polyethylene, branched low-density polyethylene, a filler, and a dispersant for the filler.

Absorbent articles such as disposable diapers and sanitary napkins typically include a top sheet forming a skin-facing surface, a back sheet forming a non-skin-facing surface, and an absorbent body disposed between the two sheets. It is well known that a composite sheet in which a resin film and a nonwoven fabric are laminated and integrated is used as a leak-proof sheet that forms the non-skin facing surface (outer surface) of an absorbent article, such as a back sheet (Patent Document 2). ~5). In the composite sheet, from the viewpoint of making the absorbent article feel good to the touch, the resin film is often used on the inside (skin facing side) and the nonwoven fabric is used on the outside (non-skin facing side).

Patent Document 2 describes the use of a composite sheet made of a stretchable sheet made of a thermoplastic synthetic resin elastomer film and a non-stretchable nonwoven fabric as a leak-proof sheet for a disposable diaper. Patent Document 2 does not describe imparting moisture permeability to the film. Patent Document 3 describes the use of a composite sheet made of a non-porous moisture-permeable film and a stretchable nonwoven fabric as a leak-proof sheet for an absorbent article. Patent Document 4 describes a stretchable composite sheet that can be used as a constituent member of an absorbent article, in which a moisture-permeable film is entirely bonded to one surface of a stretchable nonwoven fabric. The composite sheets described in Patent Documents 2 to 4 have an uneven structure in which convex stripes and grooved stripes extending in one direction are alternately arranged in a direction perpendicular to the one direction in a natural state where no external force is applied. has.

Japanese Patent Application Publication No. 1-144432 Japanese Patent Application Publication No. 10-99373 JP2004-305771A Japanese Patent Application Publication No. 2008-284717 JP2019-201691A

Components such as leak-proof sheets, which are placed relatively far from the wearer's skin in absorbent articles, must have excellent breathability and moisture permeability to prevent stuffiness while being worn, and have good leak-proof properties. It is required to be able to prevent the leakage of excrement, to have excellent elasticity and improve the fit of the absorbent article, to have a small number of constituent members, and to have a good texture and appearance. Conventional composite sheets have room for improvement in terms of these required performances.

An object of the present invention is to provide a composite sheet that is excellent in air permeability, moisture permeability, leak-proofing properties, elasticity, texture, and appearance.

In the present invention, a stretchable moisture permeable film having micropores and a non-stretchable nonwoven fabric are overlapped and joined to each other at a plurality of joints scattered between the mutually overlapping surfaces,
The moisture permeable film is a composite sheet in which the moisture permeable film is expandable and contractible, and the non-bonded portion of the nonwoven fabric with the moisture permeable film expands and contracts as the moisture permeable film expands and contracts.

Further, the present invention is an absorbent article comprising the composite sheet of the present invention described above.

According to the present invention, a composite sheet is provided that is excellent in air permeability, moisture permeability, leak-proofing properties, elasticity, texture, and appearance.

FIG. 1 is a schematic perspective view of an embodiment of the composite sheet of the present invention in its natural state. FIG. 2 is a cross-sectional view schematically showing a cross section taken along the line II in FIG. 1 (a cross section along the thickness direction and the expansion/contraction direction). FIG. 3 is a schematic perspective view of another embodiment of the composite sheet of the present invention in its natural state. FIG. 4 is a schematic perspective view of still another embodiment of the composite sheet of the present invention in its natural state. FIG. 5 is a photograph corresponding to FIG. 2 of still another embodiment of the composite sheet of the present invention. FIG. 6 is a schematic cross-sectional view along the lateral and thickness direction of the crotch area of a disposable diaper that is an embodiment of the absorbent article of the present invention. FIG. 7 is a schematic exploded perspective view of the diaper shown in FIG. 6.

Hereinafter, the present invention will be explained based on preferred embodiments thereof with reference to the drawings. In addition, in the description of the following drawings, the same or similar parts are given the same or similar symbols. The drawings are basically schematic, and the ratio of each dimension may differ from the actual one.

1 and 2 show a composite sheet 1 which is an embodiment of the composite sheet of the present invention. The composite sheet 1 includes a stretchable moisture permeable film 2 having micropores and a non-stretchable nonwoven fabric 3. In the composite sheet 1, a moisture permeable film 2 and a nonwoven fabric 3 overlap each other and are bonded to each other at a plurality of bonding portions 4 scattered between their mutually overlapping surfaces. The moisture permeable film 2 is expandable and contractible, and as the moisture permeable film 2 expands and contracts, the non-bonded portion 31 of the nonwoven fabric 3 with the moisture permeable film 2 expands and contracts.
In the composite sheet 1, the moisture-permeable film 2 has elasticity in one direction indicated by the symbol Y in the figure, and the composite sheet 1 also has elasticity in the same direction Y.

The composite sheet 1 has excellent air permeability, moisture permeability, leakproof properties, stretchability, feel and appearance. The breathability, moisture permeability, leak-proofing properties, and elasticity of the composite sheet 1 are mainly due to the moisture permeable film 2, and the feel and appearance are mainly due to the nonwoven fabric 3.
Conventional composite sheets of this type include, for example, 1) a combination of a non-porous stretchable moisture permeable film and a non-stretchable nonwoven fabric, and 2) a combination of a perforated non-stretchable moisture permeable film and a non-stretchable nonwoven fabric. and 3) a combination of a moisture permeable film and a stretchable nonwoven fabric are known, but the above 1) has poor breathability because the moisture permeable film is non-porous, and the above 2) has poor elasticity, The above 3) is poor in the feel of the nonwoven fabric. In contrast, the composite sheet of the present invention, typified by Composite Sheet 1, achieves the above-mentioned excellent properties by just having at least one sheet (one layer) of each of a perforated stretchable moisture-permeable film and a non-stretchable nonwoven fabric. are doing.
Furthermore, as will be described later, one embodiment of the composite sheet of the present invention employs an olefin resin and an inorganic filler as the main raw materials of the moisture permeable film, thereby a) using relatively inexpensive raw materials; b) Improved bonding strength with synthetic rubber-based components (e.g., adhesives, pressure-sensitive adhesives, anti-slip agents, etc.) that are conventionally widely used in absorbent products such as disposable diapers and sanitary napkins. , c) improved air permeability due to expansion of micropores when the composite sheet is stretched, and d) reduced environmental impact due to reduction in the amount of resin used. The above d) is because the moisture-permeable film is porous and contains an inorganic filler, which corresponds to the volume of the inorganic filler and the volume of the pores, compared to a case where the moisture-permeable film is non-porous and consists only of resin. Since the amount of resin used can be reduced, the burden on the environment is reduced.

In the present invention, "stretchability" means the property of being able to stretch in a predetermined direction and contracting when the stretch is released.
In the present invention, whether an object has elasticity is evaluated based on the degree of flexible deformation of the object or the residual strain after elongation. Specifically, the following tensile test was carried out on the object to be evaluated for the presence or absence of stretchability (moisture permeable film, nonwoven fabric, etc.), and the measured degree of flexibility deformation was 0.060 N/(mm・(g/m ² )). ) or less, or if the measured residual strain after 30% elongation is 11% or less, the evaluation object is evaluated to have elasticity in the tensile direction. On the other hand, if the measured degree of flexible deformation is more than 0.060N/(mm・(g/m ² )) and the measured residual strain after 30% elongation is more than 11%, the evaluation object is It has no stretchability in the tensile direction and is evaluated as non-stretchable.
The "stretchable moisture-permeable film" used in the present invention is a moisture-permeable film that has stretchability in at least one direction, and the "non-stretchable nonwoven fabric" is a moisture-permeable film that is stretchable in at least one direction. It is a non-woven fabric that does not have elasticity.

(Tensile test: measurement of flexibility deformation degree and residual strain after 30% elongation)
A test piece is cut out from the evaluation object into a rectangular shape in plan view with a length of 150 mm in the machine direction (flow direction during manufacture of the evaluation object) and a length of 30 mm in the width direction perpendicular to the machine direction. Fix the test piece to a tensile testing machine (product name: AG-1S, manufactured by Shimadzu Corporation) between a pair of gripping jigs provided in the tensile testing machine so that the mechanical direction of the test piece is the tensile direction. do. At that time, the length between the pair of gripping jigs, that is, the length (initial length) _L0 of the test piece in the machine direction before the tensile test is fixed to be 100 mm. After fixation, the load read by the tensile tester is set to zero, and the test piece is stretched at a deformation rate of 200 mm/min to 1.3 times _L0 (that is, 30% elongation), and then immediately A cycle test is performed to deflate to ₀ . From the data obtained in the cycle test, the load (F _3% ) at 1.03 times deformation during the elongation process is read, and from the following formula, the degree of flexible deformation of the test piece [N/(mm・(g/m ² ))].
Flexible deformation degree [N/(mm・(g/m ² ))] = F _3% [N]/(0.03 x 30 [mm] x basis weight of test piece [g/m ² ])
In addition, in the cycle test, the length L1 of the test piece in the machine direction when the load becomes 0.01 [N] or less during the process of shrinking the test piece is measured, and from the following formula, the length _L1 of the test piece is Calculate the residual strain after 30% elongation.
Residual strain after 30% elongation (%) = {(L ₁ [mm] - L ₀ [mm])/L ₀ }× 100
For each type of evaluation target, three test pieces are prepared, and the above-mentioned cycle test is performed on each test piece to calculate the degree of flexible deformation and the residual strain after 30% elongation. The arithmetic mean value of the degree of flexible deformation of each of the three test pieces is taken as the degree of flexible deformation of the evaluation object, and the arithmetic mean value of the residual strain after 30% elongation of each of the three test pieces is taken as 30% of the evaluation object. This is the residual strain after elongation.
In addition, if the test piece cannot be fixed in a rectangular shape in a plan view with a length _L0 of 100 mm in the machine direction and a length of 30 mm in the width direction due to the small size of the evaluation target, the maximum similarity of the rectangular shape in a plan view is determined. Fix the specimen so that it takes the shape. In that case, measure the above _L0 value, set the deformation rate so that the deformation rate per unit sample length is equal, perform a tensile test, and when calculating the degree of flexible deformation, the length in the width direction of the test piece Change it accordingly.

In the composite sheet 1, as shown in FIGS. 1 and 2, in the natural state of the moisture permeable film 2,
A convex portion 5 is formed that protrudes on the side opposite to the moisture-permeable film 2 side, and a portion or the whole of the convex portion 5 is a non-bonded portion 31 of the nonwoven fabric 3. In the present invention, "natural state" means a state in which no external force is applied to the object (moisture permeable film, composite sheet, etc.). The natural state of the moisture permeable film 2 is also the natural state of the composite sheet 1.

In the composite sheet 1, in the natural state of the moisture-permeable film 2, a plurality of pleated convex portions 5 (non-bonded portions 31 of the non-woven fabric 3) extend in a direction intersecting the stretching direction (direction Y) of the moisture-permeable film 2. At the same time, a concave portion 6 having the joint portion 4 at the bottom extends in the same direction as the convex portion 5 between the adjacent convex portions 5 , 5 . In the illustrated form, the extending direction of the convex portions 5 and the concave portions 6 is a direction (direction X) orthogonal to the expansion/contraction direction of the moisture permeable film 2.
In the natural state of the composite sheet 1, the nonwoven fabric 3 side has an uneven structure in which a plurality of convex portions 5 and concave portions 6 extending in the direction X are arranged alternately in the direction Y, whereas the moisture permeable film The second side is substantially smooth and flat.
The convex portion 5 of the composite sheet 1 is formed by the non-bonded portion 31 of the nonwoven fabric 3 protruding in the direction away from the moisture permeable film 2, and is a hollow portion formed by the gap between the non-bonded portion 31 and the moisture permeable film 2. It has 7.
A composite sheet 1 having such a convex portion 5 having a hollow structure, that is, a composite sheet 1 in which the non-bonded portion 31 of the nonwoven fabric 3 is separated from the moisture-permeable film 2 to form the convex portion 5 in a natural state, can be stretched, for example. It can be manufactured by superimposing the nonwoven fabric 3 on the moisture permeable film 2 in a state and bonding them to each other at the joint portion 4, and then releasing the moisture permeable film 2 from the stretched state to bring it into the natural state.
In this way, in the composite sheet 1, the moisture-permeable film 2 and the nonwoven fabric 3 are joined together while the moisture-permeable film 2 is stretched, and when the moisture-permeable film 2 is in its natural state, the non-woven fabric 3 is bonded. The joint portion 31 is separated from the moisture permeable film 2 and becomes a convex portion 5 having a hollow structure.

In addition, in the composite sheet of the present invention, it is not essential that the non-bonded portions 31 of the nonwoven fabric 3 protrude to the side opposite to the moisture permeable film 2 side to form the convex portions 5 in the natural state. The composite sheet of the present invention has a configuration in which the non-bonded portion 31 is not substantially separated from the moisture permeable film 2 in a natural state and no convex portions 5 are formed, that is, both the moisture permeable film 2 side and the nonwoven fabric 3 side are formed. Forms that are substantially flat without a textured structure are included.

Further, in the composite sheet of the present invention, the pattern of the bonded portions 4 (specifically, the position and shape of the bonded portions 4 in plan view) is not particularly limited, and any pattern may be adopted. The pattern of the joints 4 determines the pattern of the recesses 6 formed at positions corresponding to the joints 4, which in turn determines the pattern of the concavo-convex structure made up of the projections 5 and recesses 6.
3 and 4 show other embodiments of the uneven structure that can be employed in the composite sheet of the present invention. Regarding other embodiments to be described later, configurations different from the above-described composite sheet 1 will be explained, and configurations similar to the composite sheet 1 will be denoted by the same reference numerals and explanations will be omitted. The description of the composite sheet 1 applies as appropriate to structures not particularly described in other embodiments to be described later.
The composite sheet 1A shown in FIG. 3 differs from the composite sheet 1 in which the convex portions 5 and concave portions 6 (joint portions 4) are arranged irregularly in that these are arranged regularly. Further, the convex portions 5 of the composite sheet 1 are continuous over the entire length of the composite sheet 1 in the direction X, whereas the convex portions 5 of the composite sheet 1A have a long shape in the direction The recess 6 exists between the protrusions 5 and 5.
The composite sheet 1B shown in FIG. 4 has a convex portion 5 having a closed shape in plan view, and a concave portion 6 surrounding the convex portion 5, so that the convex portion 5 extends from one end of the sheet to the other end. This is different from the composite sheet 1 which extends in one direction. The plan view shape of the convex portions 5 in the composite sheet 1B is not particularly limited, and may be, for example, circular, oval, quadrangular, or the like.
Among the embodiments of the composite sheet described above, the composite sheet 1 in particular has a good texture and appearance because the convex portions 5 and the concave portions 6 are regularly arranged as shown in FIG. It is suitable for applications that require good quality, for example, as a leak-proof sheet for absorbent articles.

FIG. 5 shows a photograph corresponding to FIG. 2 of another embodiment of the composite sheet of the present invention. The convex portions 5 of the composite sheets 1, 1A, and 1B described above had a hollow structure with a hollow portion 7, but the convex portion of the composite sheet shown in FIG. It has a solid structure filled with the constituent fibers of the nonwoven fabric 3.
A composite sheet having such a convex portion 5 having a solid structure can be obtained by, for example, obtaining a composite sheet precursor by overlapping a non-woven fabric 3 on a non-stretched moisture permeable film 2 and joining them together at a joint 4. The composite sheet precursor can be produced by introducing the composite sheet precursor into the meshing portion of a pair of mutually meshing processing members, such as a pair of tooth space rolls, and subjecting the composite sheet precursor to stretching processing (tooth space stretching processing). can. The composite sheet precursor introduced into the meshing portion has a "stretching margin" due to the meshing of one tooth and the bottom of the other of the pair of processing members, which partially destroys the bonds between the constituent fibers. As a result, the moisture permeable film 2 and the nonwoven fabric 3 are partially separated to form a non-bonded part 31, and elasticity is imparted in the direction of introduction into the interlocking part (the direction of flow when manufacturing the composite sheet). come to have. The convex portion 5 having a solid structure is a portion provided with the above-mentioned expansion margin by engagement of tooth grooves, and is more flexible than other portions.
In this way, in the composite sheet shown in FIG. 5, the moisture permeable film 2 and the nonwoven fabric 3 are joined together when the moisture permeable film 2 is in a non-stretched state, and when the moisture permeable film 2 is in its natural state, The non-bonded portion 31 of the nonwoven fabric 3 becomes a part of the convex portion 5 having a solid structure.

The composite sheet of the present invention can be produced by the above-mentioned two manufacturing methods: 1) After joining the moisture permeable film and the non-stretchable nonwoven fabric while the stretchable moisture permeable film is stretched, the moisture permeable film is stretched. (hereinafter also referred to as "manufacturing method A"); and 2) a method of bonding a stretchable moisture permeable film and a non-stretchable nonwoven fabric under a non-stretched state of the stretchable moisture permeable film to produce a composite sheet. It can also be manufactured by a manufacturing method other than the method (hereinafter also referred to as "manufacturing method B") which includes a step of obtaining a precursor and subjecting the composite sheet precursor to tooth groove stretching processing.
For example, the following manufacturing method C can be mentioned. Manufacturing method C includes a shaping step of rotating a concave-convex roll having concavities and convexities on the circumferential surface and deforming the non-stretchable nonwoven fabric into a concavo-convex shape by following the circumferential surface, and the non-stretchable nonwoven fabric deformed into the concavo-convex shape. is conveyed while being held on the peripheral surface of the uneven roll, a stretched moisture permeable film is superimposed on the non-stretchable nonwoven fabric being conveyed, and the two are bonded by adhesive or fusion. In manufacturing method C, as in manufacturing method A, the moisture permeable film and the nonwoven fabric are joined under the stretched state of the moisture permeable film, so that in the natural state of the composite sheet 1 manufactured by manufacturing method C, The non-bonded portion 31 of the nonwoven fabric 3 is separated from the moisture permeable film 2 to form a convex portion 5 having a hollow structure. As for manufacturing method C, for example, the method for manufacturing a composite sheet described in JP-A No. 2021-79106 may be appropriately adopted.

The moisture-permeable film 2 typically mainly contains an olefin resin and further contains an inorganic filler. The inorganic filler is a substance for forming micropores in the moisture permeable film 2. Details of the moisture permeable film 2 will be described later.

As the nonwoven fabric 3, nonwoven fabrics made by various manufacturing methods can be used on the premise that it is non-stretchable. As the nonwoven fabric 3, for example, spunbond nonwoven fabric, air-through nonwoven fabric, needle punched nonwoven fabric, etc. can be used. The nonwoven fabric 3 may have a single layer structure, or may have a laminated structure in which one or more types of nonwoven fabrics are laminated.
As the constituent fibers of the nonwoven fabric 3, various synthetic fibers, recycled fibers, and natural fibers can be used. Examples of synthetic fibers include fibers made of polyethylene, polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyamides. Examples of recycled fibers include fibers made of rayon or cupro. Examples of natural fibers include fibers made of cotton, linen, silk, and the like. The constituent fibers of the nonwoven fabric 3 may be short fibers or long fibers, and may be hydrophilic or water repellent. Further, core-sheath type or side-by-side type composite fibers, split fibers, irregular cross-section fibers, crimped fibers, heat-shrinkable fibers, etc. can also be used. These fibers can be used alone or in combination of two or more.

It is preferable that the nonwoven fabric 3 contains an olefin resin. As will be described later, the moisture permeable film 2 is typically made mainly of olefin resin, but since the nonwoven fabric 3 bonded to the moisture permeable film 2 contains an olefin resin, adhesives containing synthetic rubber can be used. When the agent is used, the bonding strength between the two is improved, and inconveniences such as peeling of the composite sheet 1 during use can be effectively prevented. As the synthetic rubber, for example, a styrene thermoplastic elastomer can be used. Therefore, it is preferable that the nonwoven fabric 3 is mainly made of synthetic fibers made of olefin resin such as ethylene, propylene, butene, or the like.

The basis weights of the moisture-permeable film 2 and the nonwoven fabric 3 are not particularly limited, and may be adjusted as appropriate depending on the use of the composite sheet 1 and the like.
For example, when the composite sheet 1 is used as a leak-proof sheet for an absorbent article, the basis weight of the moisture permeable film 2 is preferably 5 g/m ² or more, more preferably 6 g/m ² or more, and preferably 100 g/m 2 or more. m ² or less, more preferably 90 g/m ² or less. The basis weight of the nonwoven fabric 3 is preferably 5 g/m ² or more, more preferably 6 g/m ² or more, and preferably 100 g/m ² or less, more preferably 90 g/m ² or less.

The means for forming the joint portion 4 is not particularly limited, and known joining means such as adhesives and fusion bonding (for example, heat sealing, ultrasonic sealing, etc.) can be used. In general, adhesives are preferable as the bonding means because adhesives cause less damage to the moisture permeable film 2 and nonwoven fabric 3 than fusion bonding. That is, it is preferable that the moisture permeable film 2 and the nonwoven fabric 3 are bonded to each other at the bonding portion 4 using an adhesive. As the adhesive, a known adhesive such as a hot melt adhesive can be used.

When an adhesive is used as a means for joining the moisture-permeable film 2 and the nonwoven fabric 3 in the joining part 4, it is preferable that the adhesive contains synthetic rubber. The reason is the same as the reason why it is preferable that the nonwoven fabric 3 contains an olefin resin, and is as described above.

The adhesive used as a means for forming the joint portion 4 is applied to one or both of the moisture permeable film 2 and the nonwoven fabric 3. The adhesive application pattern is not particularly limited, but from the viewpoint of maintaining high air permeability and moisture permeability derived from the moisture permeable film, it is preferable to apply the adhesive to the entire surface to be applied, rather than applying it in a solid manner. It is preferable to apply the coating intermittently so that there are uncoated areas. Examples of such an intermittent application pattern of the adhesive include a spiral shape, a summit shape, an omega shape, a curtain shape, a stripe shape, and the like.

The composite sheet of the present invention has excellent air permeability, moisture permeability, leak proofing properties, and elasticity, and is therefore useful for applications requiring these properties. Suitable uses for the composite sheet of the present invention include leak-proof sheets for absorbent articles such as disposable diapers and sanitary napkins; waterproof sheets for rain gear and the like. The composite sheet of the present invention is particularly useful as a component of absorbent articles.

The present invention includes absorbent articles comprising the composite sheet of the present invention described above. The absorbent articles of the present invention broadly include articles used for absorbing bodily fluids (urine, soft stool, menstrual blood, sweat, etc.) discharged from the human body, such as disposable diapers, sanitary napkins, sanitary shorts, Incontinence pads and the like are included.
The absorbent article of the present invention typically includes a top sheet forming a skin-facing surface, a back sheet forming a non-skin-facing surface, and a liquid-retaining absorbent body disposed between these sheets. . The absorbent article may further include leak-proof cuffs on both sides of the skin-facing surface along the longitudinal direction. The absorbent article of the present invention also includes a pants-type absorbent article that includes an absorbent main body including the above-mentioned top sheet, absorbent core, and back sheet, and an exterior body disposed on the non-skin-facing side of the absorbent main body. Articles are included. Diaper 10, which will be described later, is a pants-type absorbent article. The topsheet is typically liquid permeable. The absorbent body typically includes an absorbent core and a core wrap sheet surrounding the absorbent core. As the top sheet, absorbent core, and core wrap sheet, those commonly used in this type of absorbent article can be used without particular limitation.

In this specification, the "skin-facing surface" refers to the surface of an absorbent article or its constituent members (e.g., back sheet, exterior body) that faces the wearer's skin when the absorbent article is worn, i.e., The "non-skin-facing surface" refers to the side of the absorbent article or its constituent members that is opposite to the skin side when the absorbent article is worn, that is, the side that is relatively far from the wearer's skin. It is the surface to which you can face.

In the absorbent article of the present invention, the composite sheet of the present invention described above is preferably used as a leak-proof sheet, and is particularly useful as a leak-proof sheet forming the outer surface (non-skin facing surface) of the absorbent article. Examples of such a leak-proof sheet include the above-mentioned back sheet and exterior body.
One embodiment of the absorbent article of the present invention includes the composite sheet of the present invention as a leak-proof sheet forming the outer surface (non-skin facing surface) of the absorbent article.
In addition, in the absorbent article of the present invention, when the composite sheet of the present invention is used as a leak-proof sheet, the composite sheet itself may be used as a leak-proof sheet, or the composite sheet and other sheet materials (e.g. A laminated sheet with a non-woven fabric) may be used as a leak-proof sheet.

6 and 7 show a pants-type disposable diaper 10, which is an embodiment of the absorbent article of the present invention. Diaper 10 has a vertical direction X that extends from the ventral side of the wearer to the back side through the crotch area, and a horizontal direction Y that is orthogonal to the vertical direction X. The diaper 10 has a crotch region located in the crotch region of the wearer, a ventral region region located on the ventral side (front side) of the wearer relative to the crotch region, and a region located on the wearer's back side (more than the crotch region). It is divided into three parts: the dorsal part located on the rear side), and the dorsal part located on the rear side). The diaper 10 includes an absorbent main body 11 and an exterior body 20 as a leak-proof sheet disposed on the non-skin facing side of the absorbent main body 11. The diaper 10 has a pair of side seals, a waist opening, and a pair of leg openings, with both side edges along the longitudinal direction X of the exterior body 20 in each of the ventral and dorsal parts being joined together. It is said to be pants-shaped.

The absorbent body 11 includes a top sheet 12 located relatively close to the wearer's skin, a back sheet 13 located relatively far from the wearer's skin, and between both sheets 12 and 13. The absorbent body 14 is disposed in the absorber 14. The absorbent body 14 includes an absorbent core 15 and a core wrap sheet 16 surrounding the absorbent core 15. A pair of leak-proof cuffs 17, 17 that stand up on the wearer's skin side when worn are provided on both left and right sides of the absorbent main body 11 along the longitudinal direction X.

As shown in FIG. 7, the exterior body 20 includes an outer layer sheet 21 that forms the non-skin facing surface (outer surface) of the diaper 1 in the worn state, and an inner layer sheet 22 that is disposed opposite to the skin facing surface of the outer layer sheet 21. Including laminates. Both sheets 21 and 22 are joined to each other via a joining means such as an adhesive. The inner layer sheet 22 is composed of one continuous sheet, whereas the outer layer sheet 21 is composed of a plurality of sheets combined. Specifically, the outer layer sheet 21 includes a ventral outer layer sheet 21A constituting the ventral side portion, a dorsal outer layer sheet 21C constituting the dorsal side portion, and a dorsal outer layer sheet 21C located between both sheets 21A and 21C and forming the crotch portion. The crotch outer layer sheet 21B constitutes the crotch outer layer sheet 21B. The sheets 21A, 21B, and 21C constituting the outer layer sheet 21 are overlapped at their ends in the longitudinal direction They are joined together and integrated by means. An elastic member 23 for forming waist gathers is disposed in a region of the exterior body 20 that corresponds to the wearer's torso circumference so that it can be expanded and contracted in the lateral direction Y, and a region of the exterior body 20 that corresponds to the wearer's leg circumference is arranged such that it can be expanded and contracted in the lateral direction Y. , an elastic member 24 for forming leg gathers is arranged so as to be expandable and contractible. The elastic members 23 and 24 are clamped and fixed between the outer layer sheet 21 and the inner layer sheet 22 by bonding means such as adhesive.

The crotch outer layer sheet 21B, which is a part of the exterior body 20, is formed from the composite sheet 1 described above. In the diaper 10, the crotch outer layer sheet 21B made of the composite sheet 1 has elasticity in the lateral direction Y of the diaper 10, and in the natural state of the composite sheet 1 (moisture permeable film 2), the nonwoven fabric 3 side is It has an uneven structure in which a plurality of convex portions 5 and ten concave portions 6 extending in the vertical direction X are alternately arranged in the horizontal direction Y.
In addition, the crotch outer layer sheet 21B made of the composite sheet 1 may have elasticity in the longitudinal direction The side has a concavo-convex structure in which a plurality of convex portions 5 and concave portions 6 extending in the horizontal direction Y of the diaper 10 are alternately arranged in the vertical direction X.
A leak-proof sheet for the crotch area of an absorbent article, such as the crotch outer layer sheet 21B, is required to have good air permeability, moisture permeability, leak-proofing properties, elasticity, feel and appearance. The composite sheet of the present invention represented by No. 1 is useful as a leak-proof sheet for the crotch area of absorbent articles.

The composite sheet of the present invention is useful not only as the crotch outer layer sheet 21B, but also as the ventral outer layer sheet 21A and the back outer layer sheet 21C. Note that the ventral outer layer sheet 21A and the back outer layer sheet 21C, particularly the portions of both sheets 21A and 21C located around the waist of the wearer, may be required to have higher breathability than the crotch outer layer sheet 21B. In such cases, one way to improve the breathability of a composite sheet is to form pores with a larger opening diameter than the micropores in the moisture-permeable film that makes up the composite sheet, in addition to the micropores. It will be done. If such pores are formed in a moisture-permeable film, there is a concern that the leak-proof properties of the composite sheet will deteriorate, but leak-proof properties are usually not required for components placed around the wearer's waist in absorbent articles. Therefore, if the composite sheet is used for applications that require a low level of leak-proofing, there is room to form pores in addition to the micropores in the moisture-permeable film that constitutes the composite sheet.
From this point of view, the moisture-permeable film constituting the composite sheet of the present invention may have, in addition to the micropores, pores with a larger opening diameter than the micropores. This improves the air permeability of the moisture permeable film and, in turn, improves the air permeability of the composite sheet.
The diameter of the pores in the moisture permeable film is preferably 0.5 mm or more, more preferably 0.6 mm or more, and preferably 10 mm or less, more preferably 8 mm or less, from the viewpoints of air permeability and strength.
On the other hand, the diameter of the micropores in the moisture permeable film is usually preferably 0.001 μm or more, more preferably 0.005 μm or more, and preferably 500 μm or less, more preferably 300 μm or less.
The aperture diameter refers to the length across the pore or micropore at the narrowest position (diameter if the pore or micropore is circular in plan view). The opening diameter can be determined from a microscopic photograph of the pore or micropore.
Forming pores with a larger opening diameter than micropores in a moisture permeable film can be achieved by, for example, pressing the peripheral surface of a roll having an uneven structure on the peripheral surface against the moisture permeable film. This can be achieved by physically making holes.

The composite sheet of the present invention can be used not only as the exterior body 20 (outer layer sheet 21) but also as the back sheet 13 in the diaper 10. Furthermore, the composite sheet of the present invention can be used not only for pants-type diapers such as the diaper 10 but also for expandable diapers, in which case, as a back sheet forming the outer surface (non-skin facing surface) of the expandable diaper. It is preferable to use Typically, a deployable diaper is equipped with a pair of fastening tapes extending in the transverse direction on the back side, and when worn, the pair of fastening tapes are attached to a fastening area provided on the outer surface of the ventral side. It is designed to stay in place.

Hereinafter, the moisture permeable film constituting the composite sheet of the present invention will be described in detail based on preferred embodiments thereof.
The moisture-permeable film has air permeability, moisture permeability, leak-proofing properties, and elasticity. The moisture permeable film is a resin film mainly made of resin and has many micropores, and the breathability of the moisture permeable film is mainly due to the micropores. Further, the moisture permeability of the moisture permeable film may be developed by the resin, but it can be improved by the presence of micropores regardless of whether or not the resin has moisture permeability. Further, the elasticity of the moisture-permeable film is mainly due to the resin (for example, the olefin resin described below).

Moisture permeable films typically contain a resin and an inorganic filler. Such a moisture-permeable film is produced by stretching a resin processed product containing a resin and an inorganic filler, and forming a large number of micropores in the resin processed product.

As the resin that is the main raw material for the moisture permeable film, resins that exhibit elasticity when formed into a film can be used, such as olefin resins, ester resins (polyethylene terephthalate, polybutylene terephthalate, etc.), amide resins (nylon etc.), acrylonitrile resins, vinyl resins, vinylidene resins, urethane resins, etc., and one type of these resins can be used alone or two or more types can be used in combination. Among these resins, olefin resins are particularly suitable as resins for moisture-permeable films because high-quality moisture-permeable films can be manufactured at relatively low cost.
Olefin resins used for moisture permeable films typically contain polymers and copolymers of monoolefins such as ethylene, propylene, butene, etc. as a main component. Specific examples include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and polypropylene.

From the viewpoint of improving the flexibility of the moisture permeable film and, by extension, the flexibility of the composite sheet of the present invention, the moisture permeable film preferably contains an olefin resin composition having a low density.
In the present specification, the term "olefin resin composition" includes both cases in which only one type of various olefin resins is contained and cases in which two or more types of various olefin resins are contained. Furthermore, the term "olefin resin composition" is a concept that consists only of various olefin resins and does not contain other resins or components other than resins. Note that the moisture-permeable film used in the present invention may contain resins other than olefin resins.

The olefin resin composition contained in the moisture permeable film preferably has a density of less than 0.900 g/cm ³ , more preferably 0.895 g/cm ³ or less, and 0.885 g/cm ³ or less It is more preferable that
In addition, the density of the olefin resin composition contained in the moisture permeable film is preferably 0.840 g/cm ³ or more, which prevents blocking from occurring in the moisture permeable film, and the density should be 0.850 g/cm ³ or more. is more preferable, and even more preferably 0.860 g/cm ³ or more.
To summarize the above, the density of the olefin resin composition contained in the moisture-permeable film is preferably 0.840 g/cm ³ or more and less than 0.900 g/cm 3 , and preferably 0.850 g/cm ³ or more and less than 0.850 g/cm ³ or more. It is more preferably .895 g/cm ³ or less, and even more preferably 0.860 g/cm ³ or more and 0.885 g/cm ³ or less.

The olefin resin composition contained in the moisture permeable film is composed of a low melting point olefin resin with a melting point of less than 90°C (hereinafter also simply referred to as "low melting point olefin resin") and a melting point of 95°C or higher. It is preferable to contain a certain high melting point olefin resin (hereinafter also simply referred to as "high melting point olefin resin"). Low-melting point olefin resins have the advantage of imparting flexibility to moisture-permeable films, while high-melting point olefin resins can solidify moisture-permeable films obtained by melt molding in a short time, making high-speed molding possible. There are benefits.
The melting point of the low melting point olefin resin is preferably 80°C or lower, more preferably 70°C or lower, in order to further enhance the above merits. Further, in order to obtain the morphological stability of the moisture permeable film, it is preferable that the low melting point olefin resin has a melting point of 40° C. or higher.
The melting point of the high melting point olefin resin is preferably 100°C or higher, more preferably 110°C or higher, from the viewpoint of further enhancing the above merits.

The melting point of the olefin resin composition contained in the moisture permeable film is measured by the following method.
Approximately 2.0 mg of moisture-permeable film was used as a sample, and a differential scanning calorimeter (DSC7000X, manufactured by Hitachi High-Tech Science Co., Ltd.) was used to measure the temperature in the range of 10°C to 260°C, at a heating rate of 10°C/min, in an air environment. Differential scanning calorimetry (DSC) is performed under the following conditions. In the obtained DSC curve, an endothermic peak that occurs when the olefin resin melts is observed, and the melting point of the olefin resin is the temperature at the top of the observed endothermic peak. The melting point of the additive contained in the moisture permeable film and the melting point of the olefin resin can be distinguished by collecting the additive that has bleed out from the moisture permeable film and measuring its melting point. be.
The following methods can be used to efficiently collect additives from a moisture-permeable film. First, a moisture-permeable film is kneaded at 160° C. and 30 rpm for 10 minutes using a Laboplast Mill (manufactured by Toyo Seiki) to obtain a resin mass. Next, using a lab press (manufactured by Toyo Seiki), the resin mass is pressed at 150° C. and 13 MPa for 1 minute, and then cool-pressed at room temperature and 13 MPa for 1 minute to obtain a pressed film with a film thickness of approximately 0.5 mm. Finally, the press film is stored in a 50°C environment for one week. By doing so, more additives bleed out on the surface of the press film than in the moisture-permeable film state, so that the additives can be collected efficiently. Methods for collecting additives from the press film surface include, for example, wiping or scraping with a spatula.

The content of the low melting point olefin resin in the moisture permeable film is 30 parts by mass or more in 100 parts by mass of the resin (specifically, for example, the olefin resin composition) in the moisture permeable film. The content is preferable from the viewpoint of being able to maintain a small residual strain after elongation deformation while imparting satisfactory flexibility to the resin, more preferably 35 parts by mass or more, and even more preferably 40 parts by mass or more. The amount is preferably 95 parts by mass or less because blocking is less likely to occur in the moisture-permeable film, more preferably 92 parts by mass or less, still more preferably 90 parts by mass or less.
The content of the high melting point olefin resin in the moisture permeable film is 5 parts by mass or more in 100 parts by mass of the resin (specifically, for example, the olefin resin composition) in the moisture permeable film. The amount is preferably 8 parts by mass or more, and even more preferably 10 parts by mass or more. The amount is preferably 70 parts by mass or less from the viewpoint of achieving both flexibility of the moisture-permeable film, more preferably 65 parts by mass or less, and still more preferably 60 parts by mass or less.

The density of the low melting point olefin resin is preferably 0.895 g/cm 3 or less, more preferably 0.885 g/cm ³ or less, and even more preferably 0.875 g/cm ³ from the viewpoint of improving the flexibility of the moisture permeable film. ³ or less.
In addition, from the viewpoint of maintaining the strength of the moisture permeable film, the density of the low melting point olefin resin is preferably 0.840 g/cm ³ or more, more preferably 0.850 g/cm ³ or more, and even more preferably 0.860 g/cm 3 or more. It is ³ or more.
To summarize the above, the density of the low melting point olefin resin is preferably 0.840 g/cm ³ or more and 0.895 g/cm ³ or less, assuming that the density of the low melting point olefin resin is lower than the density of the high melting point olefin resin used together. More preferably 0.850 g/cm ³ or more and 0.885 g/cm ³ or less, still more preferably 0.860 g/cm ³ or more and 0.875 g/cm ³ or less.
A preferred example of the low melting point olefin resin is a copolymer of ethylene and an α-olefin, and examples of the α-olefin include propylene, 1-butene, 1-pentene, and 1-hexene. From the viewpoint of reliably adjusting the melting point and density of the low melting point olefin resin within the above-mentioned preferred ranges, the low melting point olefin resin is preferably a random copolymer. In particular, a copolymer of ethylene and α-olefin polymerized using a metallocene catalyst is more preferable because it further improves the strength of the film against tearing and punch-through.

The density of the high melting point olefin resin is preferably relatively low from the viewpoint of achieving flexibility of the moisture permeable film, preferably 0.950 g/cm ³ or less, more preferably 0.940 g/cm ³ or less, and even Preferably it is 0.930 g/cm ³ or less.
In addition, from the viewpoint of suppressing blocking, the density of the high melting point olefin resin is preferably 0.900 g/cm ³ or more, more preferably 0.905 g/cm ³ or more, and even more preferably 0.910 g/cm ³ or more. be.
To summarize the above, the density of the high melting point olefin resin is preferably 0.900 g/cm ³ or more and 0.950 g/cm ^{3 or} less, assuming that the density of the high melting point olefin resin is higher than the density of the low melting point olefin resin used in combination. More preferably 0.905 g/cm ³ or more and 0.940 g/cm ³ , still more preferably 0.910 g/cm ³ or more and 0.930 g/cm ³ or less.
As the high-melting point olefin resin, it is preferable to use low-density polyethylene or linear low-density polyethylene. In particular, using linear low-density polyethylene improves heat resistance during stretching and allows uniform stretching. It is preferable from the viewpoint of obtaining. In particular, linear low-density polyethylene polymerized with a metallocene catalyst is more preferable because it further improves the strength of the film against tearing and punching through.

In the moisture-permeable film, the inorganic filler is a substance that peels off at the interface with the resin used in combination to form micropores. From the viewpoint of ensuring that the function of the inorganic filler is exhibited, the average particle diameter D50 of the inorganic filler is preferably 0.5 μm or more, more preferably 1 μm or more, and preferably 30 μm or less, more preferably 10 μm or less. It is.
The average particle diameter D50 of the inorganic filler is the weight cumulative particle diameter at a cumulative weight of 50% by mass measured by laser diffraction scattering particle size distribution measuring method.

Examples of inorganic fillers include calcium carbonate, gypsum, talc, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium phosphate, aluminum hydroxide, zinc oxide, titanium oxide, alumina, and mica. , zeolites and carbon black, and mixtures thereof. In particular, calcium carbonate is preferable because it is easy to adjust the average particle size D50 to the above-mentioned preferable range.

The content of the inorganic filler in the moisture-permeable film is preferably 50 parts by mass based on 100 parts by mass of the resin in the moisture-permeable film, from the viewpoint of the breathability of the moisture-permeable film and the balance between moisture permeability and leak-proofing properties. The content is more preferably 60 parts by mass or more, still more preferably 80 parts by mass or more, and preferably 400 parts by mass or less, more preferably 350 parts by mass or less, and even more preferably 200 parts by mass or less. If the content of inorganic filler is too low, the size and number of micropores may be insufficient, resulting in insufficient air permeability and moisture permeability. If the content of inorganic filler is too high, leakage prevention This may lead to a decrease in sexual performance.

In addition to the above-mentioned resin (preferably an olefin resin composition) and inorganic filler, the moisture-permeable film may further contain a pore-opening promoter. The pore opening promoter is used for the purpose of smoothly forming micropores by stretching a resin sheet containing a resin and an inorganic filler. As mentioned above, from the viewpoint of improving the flexibility of the moisture permeable film, it is preferable to include a low melting point olefin resin in the moisture permeable film. Since this resin is relatively unlikely to cause such interfacial peeling, such interfacial peeling can be promoted by using a pore-opening promoter in addition to a low melting point olefin resin as a raw material for the moisture permeable film.
As the pore opening promoter, a substance known as a mold release agent for metal and resin is suitably used. Specific examples include metal soaps, silicones, fluororesins, fatty acid amides, and hydrocarbon paraffin waxes. In particular, it is preferable to use metal soap because it can form micropores more smoothly.
As the metal soap, metal salts of fatty acids are preferably used. Examples of fatty acids include caprylic acid, palmitic acid, stearic acid, capric acid, oleic acid, myristic acid, and lauric acid. Examples of metal salts include calcium, aluminum, magnesium, zinc, and other salts of these fatty acids.
In particular, if the chain length of the hydrocarbon chain in the fatty acid added to hydrophobize the surface of the inorganic filler described later is the same as the chain length of the hydrocarbon chain in the fatty acid constituting the metal soap, the fatty acid This is preferred because the metal soap can more smoothly migrate to the surface-modified inorganic filler. In particular, it is preferred that both the fatty acid and the fatty acid constituting the metal soap be stearic acid.
Note that fatty acids themselves are known as substances similar to metal salts of fatty acids and that can be incorporated into moisture permeable films. Fatty acids are used for the purpose of increasing the dispersibility of inorganic fillers. However, fatty acids do not have the function of promoting interfacial peeling between the resin and the inorganic filler. Therefore, in the present invention, metal salts of fatty acids and fatty acids are clearly distinguished physically and functionally.

In particular, if a metal soap with a melting point of 200°C or lower is used, the metal soap will be sufficiently melted and mixed uniformly into the molten resin during kneading of the resin-containing compound during the manufacturing process of the moisture permeable film. Preferable from this point of view. From this viewpoint, the melting point of the metal soap is more preferably 180°C or lower, even more preferably 160°C or lower.

In addition, in relation to the resin mentioned above, it is recommended to use a metal soap whose precipitation temperature is higher than the solidification temperature of the resin, so that fine pores can be formed successfully, and the metal soap has high moisture permeability. This is preferable from the viewpoint of obtaining a moisture-permeable film having high water resistance. Specifically, since the precipitation temperature of the metal soap is higher than the solidification temperature of the resin, the metal soap precipitates faster than the resin solidifies, so that the metal soap can be smoothly transferred to the surface of the inorganic filler. become. As a result, the mold releasability between the inorganic filler and the resin during stretching is improved, and micropores are smoothly formed. In order to make this advantage even more remarkable, when the precipitation temperature of the metal soap is Ts (°C) and the solidification temperature of the resin is Tp (°C), the value of Ts - Tp should be larger than 0°C. The temperature is preferably 1°C or higher, more preferably 2°C or higher, and even more preferably 2°C or higher. Further, the value of Ts-Tp is preferably 50°C or less.

Provided that the value of Ts-Tp is within the above range, the precipitation temperature Ts of the metal soap is preferably 80°C or more and 180°C or less, more preferably 90°C or more and 170°C or less, and 100°C. More preferably, the temperature is 160°C or less.
On the other hand, the solidification temperature Tp of the resin is preferably 60°C or more and 130°C or less, more preferably 70°C or more and 120°C or less, provided that the value of Ts-Tp is within the above-mentioned range. More preferably, the temperature is 80°C or higher and 115°C or lower.

The precipitation temperature Ts of metal soap is measured by the following method using a hot stirrer and a thermocouple. Using a hot stirrer, add 0.43 g of metal soap to 5.0 g of paraffin oil and heat while stirring until the metal soap is dissolved. After stopping stirring the liquid with the stirrer, lower the temperature of the paraffin oil at a cooling rate of 0.2°C/min, read the temperature of the paraffin oil with a thermocouple when metal soap begins to precipitate, and measure the temperature of the paraffin oil with a thermocouple. Let it be the precipitation temperature of soap. Note that if the metal soap does not dissolve in the paraffin oil even though the paraffin oil is heated to 210°C, the precipitation temperature is defined as 210°C.
On the other hand, the solidification temperature Tp of the resin is measured by the following method in accordance with JIS K 7121 (How to determine extrapolated crystallization end temperature). Using approximately 2.0 mg of moisture-permeable film as a sample, using a differential scanning calorimeter (DSC7000X, manufactured by Hitachi High-Tech Science Co., Ltd.), the measurement temperature range was 30°C to 260°C, the heating rate was 10°C/min, and the cooling rate was Differential scanning calorimetry (DSC) is performed under the conditions of 50° C./min, an air environment, and a data sampling period of 0.5 s. In the temperature decreasing process of the obtained DSC curve, an exothermic peak that occurs when the resin solidifies (crystallizes) is observed. The solidification temperature of the resin is determined by a straight line that extends the baseline on the lower temperature side to the higher temperature side, and a curve on the lower temperature side of the peak, with the highest slope for the peak with the highest calorific value in the cooling process.2 This is the temperature at the intersection of approximate straight lines drawn between point data. If two or more exothermic peaks overlap, use, for example, the software PeakFit v4.12 (manufactured by Hulinx Co., Ltd.) to perform peak separation, and then determine the solidification temperature using the method described above.

The content of the pore opening promoter in the moisture permeable film is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass, based on 100 parts by mass of the resin in the moisture permeable film, from the viewpoint of promoting the formation of micropores. At least 1.0 parts by mass, more preferably at least 1.0 parts by mass, and from the viewpoint of obtaining good film formability, preferably at most 20 parts by mass, more preferably at most 15 parts by mass, even more preferably at most 10 parts by mass. .

In addition, when the moisture permeable film contains an inorganic filler and the pore opening promoter in the moisture permeable film is a metal soap, the content of the metal soap in the moisture permeable film is determined from the point that fine pores can be successfully generated. The amount is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2 parts by mass or more, based on 100 parts by mass of the inorganic filler in the moisture permeable film. In order to maintain good moldability, the amount is preferably 10 parts by mass or less, more preferably 9 parts by mass or less, and even more preferably 8 parts by mass or less.

The moisture-permeable film may further contain triglyceride in addition to the above-mentioned resin (preferably an olefin resin composition), an inorganic filler, and, if necessary, a pore-opening promoter. Triglycerides can function as a water repellent that improves water repellency and leak-proofing properties in a moisture-permeable film.
In the technical field of moisture permeable films used in the present invention, triglycerides have been blended into moisture permeable films; Preferably, it is of a type different from triglycerides. Specifically, the triglyceride suitably used in the present invention is a hydrocarbon group containing a group derived from a fatty acid having 16 to 22 carbon atoms, and having no unsaturated bond or substituent. triglyceride" (hereinafter also referred to as "specific triglyceride"). As a result of studies conducted by the present inventors, it has been found that by using a specific triglyceride, the water repellency of a moisture-permeable film containing the specific triglyceride is increased more than ever, and the leak-proof property of the moisture-permeable film is improved more than ever.

From the viewpoint of making the above-mentioned advantages even more remarkable, the content of the specific triglyceride in the moisture-permeable film is preferably 0.1 parts by mass or more, and 0.5 parts by mass or more based on 100 parts by mass of the resin. It is more preferable that the amount is 1.0 parts by mass or more.
Further, from the viewpoint of film formability, the content of the specific triglyceride is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and more preferably 20 parts by mass or less based on 100 parts by mass of the resin. It is even more preferable.
Taking all the above into consideration, the content of the specific triglyceride is preferably 0.1 parts by mass or more and 30 parts by mass or less, and more preferably 0.5 parts by mass or more and 25 parts by mass or less, based on 100 parts by mass of the resin. Preferably, the amount is 1.0 parts by mass or more and 20 parts by mass or less, more preferably.

In addition, from the viewpoint of fully exhibiting both the effect of the metal soap used as a pore-opening promoter and the effect of the water repellent, and from the viewpoint of preventing deterioration of processability due to excessive content of additives, moisture permeable film is included. The ratio of the specific triglyceride to the metal soap is preferably 30 parts by mass or more and 300 parts by mass or less of the metal soap per 100 parts by mass of the specific triglyceride. From the viewpoint of making this advantage even more remarkable, it is more preferable that the metal soap is used in an amount of 35 parts by mass or more and 230 parts by mass or less, and more preferably 40 parts by mass or more and 220 parts by mass or less per 100 parts by mass of the specific triglyceride. is more preferable.

The specific triglyceride will be explained below. The specific triglyceride is represented by the following formula (1).

In the formula (1), R ¹ , R ² and R ³ represent the same or different hydrocarbon groups. At least one of R ¹ , R ² , and R ³ is a group derived from a fatty acid having 16 to 22 carbon atoms, and the group is a hydrocarbon group having no unsaturated bond and no substituent. . Note that the alkyl group of palmitic acid, which is a fatty acid having 16 carbon atoms, has 15 carbon atoms.
The above-mentioned "hydrocarbon group having no unsaturated bond" refers to a hydrocarbon group having neither a carbon-carbon double bond nor a triple bond. In other words, it is an alkyl group. Moreover, the above-mentioned "hydrocarbon group having no substituent" means that the hydrogen atom contained in the hydrocarbon group is not substituted with another atom or atomic group (for example, a hydroxyl group). Therefore, the above-mentioned "hydrocarbon group having no unsaturated bond or substituent" has the same meaning as an unsubstituted alkyl group.

In the specific triglyceride represented by formula (1), at least one of R ¹ , R ² , and R ³ has 16 to 20 carbon atoms, from the viewpoint of obtaining a moisture-permeable film with higher water repellency. It is a group derived from a fatty acid, and the group is preferably a hydrocarbon group having no unsaturated bond or substituent.
Furthermore, in the specific triglyceride represented by the formula (1), any one or two of R ¹ , R ² , and R ³ is a group derived from a fatty acid having 16 to 22 carbon atoms (the The group is a hydrocarbon group having no unsaturated bonds and no substituents.) If the group is a group other than a hydrocarbon group having no unsaturated bond or substituent, there is no particular restriction on the type as long as the group is derived from a fatty acid, but the group has higher water repellency. From the viewpoint of obtaining a moisture-permeable film, it is preferable that the group has no unsaturated bond and no substituent.

The specific triglyceride is preferably one in which the number of carbon atoms in fatty acid residues is adjusted. By doing so, the water repellency of the moisture permeable film can be improved. Specifically, the following (A) or (B) is preferable as the specific triglyceride.
(A) A triglyceride containing at least a group derived from a fatty acid having 18 carbon atoms in one molecule and a group derived from a fatty acid having 16 to 22 carbon atoms (excluding fatty acids having 18 carbon atoms) in one molecule. triglycerides, including mixtures of triglycerides containing at least
(B) One molecule contains at least one group derived from a saturated fatty acid having 18 carbon atoms, and at least one group derived from a saturated fatty acid having 16 to 22 carbon atoms (excluding fatty acids having 18 carbon atoms). Contains 1 triglyceride.
In particular, from the perspective of further increasing liquid repellency, triglycerides contain in one molecule at least one group derived from a saturated fatty acid with 18 carbon atoms, and saturated fatty acids with 16 to 22 carbon atoms (18 carbon The triglyceride is preferably a triglyceride containing at least one group derived from a fatty acid (excluding fatty acids).
As a specific example, a combination of a fatty acid having 18 carbon atoms and a fatty acid having 16 carbon atoms is as shown in (C) or (D) below.
(C) a triglyceride containing in one molecule at least a group derived from a fatty acid having 18 carbon atoms (i.e., stearic acid) (the group is a hydrocarbon group having no unsaturated bond or substituent); and a carbon atom. A triglyceride containing a mixture with a triglyceride containing in one molecule at least a group derived from a number 16 fatty acid (i.e., palmitic acid) (the group is a hydrocarbon group having no unsaturated bond or substituent).
(D) One molecule contains at least one group derived from a fatty acid having 18 carbon atoms (the group is a hydrocarbon group having no unsaturated bond or substituent), and a fatty acid having 16 carbon atoms A triglyceride containing at least one group derived from (the group is a hydrocarbon group having no unsaturated bond and no substituent).

As in the case (C) above, when the specific triglyceride includes multiple types of triglycerides, at least one type of triglyceride contains at least one group derived from a saturated fatty acid having 16 carbon atoms in one molecule. (This triglyceride is also referred to as "triglyceride 16.") is preferred. Triglyceride 16 may contain one group derived from a saturated fatty acid having 16 carbon atoms in one molecule (this triglyceride is also referred to as "triglyceride P"), or may contain two groups ( This triglyceride is also referred to as "triglyceride PP"), or it may contain three triglycerides (this triglyceride is also referred to as "triglyceride PPP").
The remaining fatty acid residues in triglyceride P and triglyceride PP are not particularly limited, and may be, for example, residues of saturated fatty acids having 12 or more and 24 or less carbon atoms.

The triglyceride 16 may be composed only of triglyceride P, may be composed only of triglyceride PP, or may be composed only of triglyceride PPP.
The triglyceride 16 may be a combination of two or more selected from triglyceride P, triglyceride PP, and triglyceride PPP. For example, triglyceride 16 can be a combination of triglyceride P and triglyceride PP, a combination of triglyceride P and triglyceride PPP, a combination of triglyceride PP and triglyceride PPP, or a combination of triglyceride P, triglyceride PP, and triglyceride PPP.

As in the case (C) above, when the specific triglyceride includes multiple types of triglycerides, at least one type of triglyceride contains at least one group derived from a saturated fatty acid having 18 carbon atoms in one molecule. (This triglyceride is also referred to as "triglyceride 18.") is also preferred. Triglyceride 18 may contain one group derived from a fatty acid having 18 carbon atoms in one molecule (this triglyceride is also referred to as "triglyceride S"), or may contain two groups (this (This triglyceride is also referred to as "triglyceride SS."), or it may contain three triglycerides (this triglyceride is also referred to as "triglyceride SSS").
The remaining fatty acid residues in triglyceride S and triglyceride SS are not particularly limited in type, and may be, for example, residues of saturated fatty acids having 12 or more and 24 or less carbon atoms.

The triglyceride 18 may be composed only of triglyceride S, may be composed only of triglyceride SS, or may be composed only of triglyceride SSS.
The triglyceride 18 may be a combination of two or more selected from triglyceride S, triglyceride SS, and triglyceride SSS. For example, triglyceride 18 can be a combination of triglyceride S and triglyceride SS, a combination of triglyceride S and triglyceride SSS, a combination of triglyceride SS and triglyceride SSS, or a combination of triglyceride S, triglyceride SS, and triglyceride SSS.

In the case of (C) above, the specific triglyceride may be composed only of triglyceride 16 and triglyceride 18, or may be composed of other triglycerides in addition to triglyceride 16 and triglyceride 18. Other triglycerides include triglycerides that do not have any groups derived from fatty acids having 14 to 22 carbon atoms, and triglycerides containing groups derived from fatty acids having 14 to 22 carbon atoms (with the exception of triglyceride 16 and triglyceride 18). ).

A group derived from a saturated fatty acid having 16 carbon atoms is designated as "P", a group derived from a saturated fatty acid having 18 carbon atoms is designated as "S", and a group other than a saturated fatty acid having 16 carbon atoms and a saturated fatty acid having 18 carbon atoms When "X" and "Y" are groups derived from fatty acids, examples of combinations of aliphatic groups constituting the specific triglyceride include PPP, SSS, PPX, SSX, PXY, SXY, PPS, PSS, and PSX. It will be done. The structures of triglycerides represented by PPX, SSX, PXY, SXY and PSX are (a) to (m) below. Although the structures of PPS and PSS are not shown, the structure of PPS is based on the structure of PPX, and the structure of PSS is based on the structure of SSX.

As the specific triglyceride, the various triglycerides described above can be used alone. For example, in the case of (D) above, the specific triglyceride contains in one molecule at least one group derived from a saturated fatty acid having 16 carbon atoms, and at least one group derived from a saturated fatty acid having 18 carbon atoms. It may be composed of a group containing 1 or more fatty acids and no other groups derived from fatty acids. Alternatively, the specific triglyceride contains one group derived from a saturated fatty acid having 16 carbon atoms, one group derived from a saturated fatty acid having 18 carbon atoms, and one group derived from another fatty acid. It may also be composed of triglycerides.

The specific triglyceride may be a combination of two or more of the various triglycerides described above. For example, the specific triglyceride may be a combination of (C) and (D). Alternatively, a combination of two or more of the above (D) may be used.
Furthermore, the specific triglyceride may be a combination of one or more of the aforementioned triglycerides and other triglycerides. Other triglycerides include, for example, triglycerides containing groups derived from fatty acids having 14 to 22 carbon atoms (excluding triglyceride 16 and triglyceride 18).
In the present invention, it is preferable to use the various triglycerides described above alone or to use a combination of two or more of the various triglycerides described above from the viewpoint of further increasing the water repellency of the moisture permeable film.

The triglycerides contained in the moisture-permeable film used in the present invention are 28% by mass or more and 96% by mass or less, particularly 28% by mass or more, based on the total amount of groups derived from fatty acids contained in all triglycerides in the moisture-permeable film. 70% by mass or less, especially 29% by mass or more and 67% by mass or less, is a group derived from a fatty acid having 18 carbon atoms (the group is a hydrocarbon group having no unsaturated bonds and no substituents). However, it is preferable from the viewpoint of obtaining a moisture permeable film with higher water repellency.
Note that the above-mentioned "all triglycerides" is a general term for specific triglycerides and triglycerides other than the specific triglycerides contained in the moisture permeable film (hereinafter the same applies unless otherwise specified).

In addition, from the viewpoint of further increasing the water repellency of the moisture permeable film and from the viewpoint of shortening the time until water repellency develops, all triglycerides contained in the moisture permeable film used in the present invention are contained in the moisture permeable film. Of the total amount of groups derived from fatty acids contained in the triglyceride, 28% by mass or more and 68% by mass or less are groups derived from fatty acids having 18 carbon atoms (the group does not have unsaturated bonds or substituents). 26% by mass or more and 70% by mass or less is a group derived from a fatty acid having 16 carbon atoms (the group is a hydrocarbon group having no unsaturated bond or substituent). ) is preferable. However, the condition is that the sum of the proportion of groups derived from fatty acids having 18 carbon atoms and the proportion of groups originating from fatty acids having 16 carbon atoms does not exceed 100% by mass.
In this case, the proportion of groups derived from fatty acids having 18 carbon atoms is preferably 29% by mass or more and 66% by mass or less, and even more preferably 30% by mass or more and 64% by mass or less.
On the other hand, the proportion of groups derived from fatty acids having 16 carbon atoms is preferably 27% by mass or more and 69% by mass or less, and even more preferably 28% by mass or more and 68% by mass or less. The greater the proportion of groups derived from fatty acids having 16 carbon atoms, the easier it is for triglycerides to precipitate on the surface of the moisture-permeable film, and the time it takes to develop water repellency becomes shorter.

In addition, from the viewpoint of increasing the thermal stability of the moisture permeable film and further increasing the water repellency of the moisture permeable film, the triglyceride contained in the moisture permeable film of the present invention has a group derived from fatty acids contained in all triglycerides. Based on the total amount, 28% by mass or more and 47% by mass or less is a group derived from a fatty acid having 18 carbon atoms (the group is a hydrocarbon group having no unsaturated bond or substituent), and 40 It is preferable that 60% by mass or less is a group derived from a fatty acid having 22 carbon atoms (the group is a hydrocarbon group having no unsaturated bond and no substituent). However, the condition is that the sum of the proportion of groups derived from fatty acids having 18 carbon atoms and the proportion of groups originating from fatty acids having 22 carbon atoms does not exceed 100% by mass.
In this case, the proportion of groups derived from fatty acids having 18 carbon atoms is more preferably 30% by mass or more and 45% by mass or less, and even more preferably 32% by mass or more and 43% by mass or less.
On the other hand, the proportion of groups derived from fatty acids having 22 carbon atoms is more preferably 42% by mass or more and 58% by mass or less, and even more preferably 44% by mass or more and 56% by mass or less. The higher the proportion of groups derived from fatty acids having 22 carbon atoms, the higher the melting point of the triglyceride and the higher the thermal stability of the molded article. Furthermore, contamination of the rolls of processing machines can be reduced.

Based on the total amount of fatty acid-derived groups contained in all triglycerides, groups derived from fatty acids with 16 carbon atoms, groups derived from fatty acids with 18 carbon atoms, and groups derived from fatty acids with 22 carbon atoms. The respective proportions of groups are determined in the following manner.
Wipe off triglyceride that bleeds out on the surface of the film with a cellulose wipe.
The ester bonds in the obtained triglyceride are hydrolyzed with an alkali, and the methyl-esterified fatty acids are quantitatively analyzed by gas chromatography.

Note that whether or not alkyl chains having different numbers of carbon atoms exist in one molecule of triglyceride can be determined by TOF-MS (time-of-flight mass spectrometry). Specifically, the molecular weight distribution of triglyceride is measured by TOF-MS, and it is determined from the molecular weight of one molecule whether or not the molecule contains an alkyl group having a different number of carbon atoms. Whether or not alkyl chains having different numbers of carbon atoms exist in one molecule of compounds having the same molecular weight can be determined using a tandem mass spectrometer (MS/MS) as a mass spectrometer. The first mass separation section selects a specific ion, and the second mass separation section separates and detects fragment ions generated by collision with an inert gas, thereby making a distinction.

The triglyceride used in the present invention preferably does not contain groups derived from unsaturated fatty acids, from the viewpoint of further increasing the water repellency of the moisture permeable film. The term "not containing groups derived from unsaturated fatty acids" includes both cases where no groups derived from unsaturated fatty acids are contained and cases where a small amount of unsaturated fatty acids are unavoidably contained. A case where a small amount of unsaturated fatty acids is unavoidably included means, for example, that the proportion of groups derived from unsaturated fatty acids is based on the total amount of fatty acid-derived groups contained in all triglycerides in the moisture-permeable film. This is the case when it is 2% by mass or less.

Similarly to the above, the triglyceride used in the present invention preferably does not contain a group derived from a fatty acid having a hydroxyl group, from the viewpoint of further increasing the water repellency of the moisture permeable film. A fatty acid having a hydroxyl group is a fatty acid in which at least one hydrogen atom in a hydrocarbon group of the fatty acid is substituted with a hydroxyl group. The phrase "does not contain a group derived from a fatty acid having a hydroxyl group" includes both cases in which it does not contain any groups derived from a fatty acid having a hydroxyl group, and cases in which it inevitably contains a small amount of groups derived from a fatty acid having a hydroxyl group. A case where a small amount of groups derived from a fatty acid having a hydroxyl group is unavoidably included means, for example, based on the total amount of groups derived from fatty acids contained in all triglycerides in the moisture permeable film, the group derived from a fatty acid having a hydroxyl group is This is the case when the proportion of the group is 2% by mass or less.

From the viewpoint of further increasing the water repellency of the moisture-permeable film used in the present invention, in the moisture-permeable film, all the groups derived from fatty acids contained in triglycerides are hydrocarbon groups having no unsaturated bonds. preferable. Moreover, it is preferable that the groups derived from fatty acids contained in all triglycerides are hydrocarbon groups having no substituents.

The moisture permeable film used in the present invention may contain only triglyceride as the glyceride, or may contain monoglyceride and/or diglyceride in addition to triglyceride as long as the desired effect of the present invention is achieved. Good too.

The moisture-permeable film may contain other components than the above-mentioned resin such as olefin resin, inorganic filler, pore opening promoter, and specific triglyceride. Examples of such other components include dispersants for inorganic fillers, plasticizers, antioxidants, ultraviolet absorbers, colorants, and the like. In particular, dispersants and plasticizers are useful in imparting various additional properties to the moisture permeable film.

As the dispersant, one that can hydrophobize the surface of the inorganic filler is preferably used. From this point of view, it is preferable to use, for example, a fatty acid as the dispersant. Examples of fatty acids include caprylic acid, palmitic acid, stearic acid, capric acid, oleic acid, myristic acid, and lauric acid.

The plasticizer is used for the purpose of imparting flexibility and suppleness to the moisture permeable film and preventing rustling noise from occurring in the moisture permeable film. As the plasticizer, monoester, polyester, ethylene-α olefin cooligomer, low molecular weight polyethylene, olefin oligomer, liquid polyisoprene, liquid polybutadiene, etc. are preferably used.
A monoester is a compound obtained from a monobasic acid and a monohydric alcohol.
On the other hand, polyester is a compound obtained by any combination of a polybasic acid and a monohydric alcohol, a monobasic acid and a polyhydric alcohol, or a polybasic acid and a polyhydric alcohol.
Ethylene-α-olefin cooligomers are low molecular weight copolymers of ethylene and α-olefins such as propylene, 1-butene, 1-pentene, and 1-hexene.
As the above-mentioned basic acids, polybasic acids, monohydric alcohols, and polyhydric alcohols, for example, those listed below are preferably used.
Examples of monobasic acids include long-chain hydrocarbon monocarboxylic acids having 10 to 22 carbon atoms.
Examples of polybasic acids include dicarboxylic acids, tricarboxylic acids, and tetracarboxylic acids.
Examples of the monohydric alcohol include long-chain hydrocarbon monoalcohols having 10 to 22 carbon atoms.
Examples of the polyhydric alcohol include diols, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, and sucrose.

Among the polyesters used as plasticizers, particularly preferred are, for example, polyesters of diethylene glycol and dimer acid, in which both terminal carboxylic acids or alcohols are partially or completely blocked with stearyl alcohol or stearic acid, 1,3- Polyesters of butanediol and adipic acid, hexaesters consisting of trimethylolpropane-adipic acid-stearic acid, octaesters consisting of pentaerythritol-adipic acid-stearic acid, dodeca esters consisting of dipentaerythritol-adipic acid-stearic acid, etc. Can be mentioned.

Particularly preferable monoesters as plasticizers include, for example, esters having a total carbon number of 30 or more obtained by dehydrating a monocarboxylic acid having 1 to 40 carbon atoms and a monoalcohol having 1 to 40 carbon atoms. Can be mentioned. Among these, monoesters having a total carbon number of 30 or more obtained from a monocarboxylic acid and a monoalcohol are preferred, and monoesters having a branched chain and having a carbon number of 38 or more are more preferred. Specifically, isodecyl stearate, isodecyl behenate, isotridecyl stearate, 2-octadecyl stearate, 2-decyltetradecyl laurate, 2-decyltetradecyl stearate, 2-octadecyl behenate, Examples include stearyl isostearate, esters of stearic acid and C20 Guerbet alcohol, and esters of α-branched fatty acids (18 to 40 carbon atoms) and monoalcohols (6 to 36 carbon atoms).

The content of dispersant and plasticizer in a moisture-permeable film is determined from the viewpoint of clarifying the significance of their use and suppressing the adverse effects (for example, a decrease in film formability and strength) that may occur if they are used in excess. , preferably 0.01 parts by mass or more, more preferably 0.10 parts by mass or more, even more preferably 2.0 parts by mass or more, and preferably 18. It is 0 parts by mass or less, more preferably 16.0 parts by mass or less.

Additives other than the specific triglyceride that can be contained in the moisture-permeable film (pore opening promoters, dispersants, plasticizers, etc.) include at least a first additive having an SP value difference of less than 0.37 with the specific triglyceride. May contain. The first additive may be contained in an amount of 3.5 parts by mass or less per 100 parts by mass of the resin, inorganic filler, and specific triglyceride, without inhibiting the water repellency expressed by the specific triglyceride. This is preferable because it allows the formulation of agents. The first additive is 0.01 parts by mass or more and 3.5 parts by mass or less, based on a total of 100 parts by mass of the resin, inorganic filler, and specific triglyceride, from the viewpoint of improving leakage prevention without impairing water repellency. The content is preferably 0.03 parts by mass or more and 3.3 parts by mass or less, and even more preferably 0.06 parts by mass or more and 3.2 parts by mass or less. .
Further, the additive may include at least a second additive having an SP value difference of 0.37 or more with respect to the specific triglyceride. The second additive may be contained in an amount of 10 parts by mass or less based on a total of 100 parts by mass of the resin, inorganic filler, and specific triglyceride, so that the water repellency expressed by the specific triglyceride is not inhibited. This is preferable from the standpoint that it can be blended. When a second additive is included as an additive, the second additive contains a total of 100% of the resin, inorganic filler, and specific triglyceride, from the viewpoint of improving leakage prevention without impairing water repellency. It is preferably contained in an amount of 0.01 parts by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 8 parts by mass or less, and 1.5 parts by mass or more and 6 parts by mass or less. More preferably, it is included.
As mentioned above, in the technical field of moisture permeable films such as the moisture permeable film used in the present invention, triglycerides have been blended into moisture permeable films. As a result of studies conducted by the present inventors, it has been found that when additives are randomly added to the water repellent, the water repellency caused by triglycerides is inhibited. On the other hand, the first additive is used in an amount of 3.5 parts by mass or less based on 100 parts by mass of the resin, inorganic filler, and specific triglyceride, or the second additive is used in the resin, When used in an amount of 10 parts by mass or less based on a total of 100 parts by mass of the inorganic filler and specific triglyceride, the additive can be blended without inhibiting the water repellency developed by the specific triglyceride. From the viewpoint of making this advantage even more remarkable, the difference in SP value between the specific triglyceride and the second additive is more preferably 0.50 or more, and even more preferably 0.60 or more. Further, the difference is preferably 4.00 or less, more preferably 3.00 or less, and even more preferably 1.50 or less.

The SP value is a physical property value called a solubility parameter, and two types of substances with similar SP values have the property of mixing well. In other words, two types of substances with similar SP values are highly compatible. Therefore, when comparing the SP value of the specific triglyceride and the SP value of the additive, the SP value of the specific triglyceride may be larger, or the SP value of the additive may be larger. From the viewpoint of making the water repellency of the specific triglyceride less likely to be inhibited by the additive, it is preferable that the SP value of the specific triglyceride is larger than the SP value of the additive.

Examples of the first additive selected so that the difference in SP value from the specific triglyceride is less than 0.37 include fatty acids, alcohols, Some examples include monoesters, polyesters and metal soaps.

Examples of the second additive selected so that the difference in SP value from the specific triglyceride is 0.37 or more include olefin oligomer, ethylene-α olefin cooligomer, low molecular weight polyethylene, silicone rubber, fluororubber, Examples include fluororesin and polystyrene. In the present invention, only the second additive may be used as the additive, or the second additive and the first additive may be used in combination. In some cases, only the first additive may be used.

The SP value was calculated using the method of Fedors [R. F. FEDORS, POLYM. ENG. SCI. 14, 147 (1974)], and the unit is (cal/cm ³ ) ^1/2 .

In addition, when there are multiple types of specific triglycerides contained in the moisture-permeable film, the SP value δmix of the mixture shown below is calculated.
δmix=Σδiφi (cal/cm ³ ) ^1/2
In the above formula, δi represents the SP value of each component constituting the mixture, and φi represents the volume fraction of the component.

The moisture-permeable film is preferably one that is evaluated as having leak-proof properties in the leak-proof evaluation test described below. Thereby, the composite sheet of the present invention can have high leakproof properties. The above-mentioned moisture permeable film can be evaluated as having leak-proof properties in the leak-proof evaluation test described below.
In the leak-proof evaluation test below, the leak-proof property is evaluated by fixing the moisture-permeable film in a natural state. It is more preferable that the leak-proof property is evaluated as having leak-proof property even when the leak-proof property is evaluated by the same method as the leak-proof evaluation test described below except that it is fixed in an extended state such as an extended state. Stretchable moisture-permeable films tend to allow liquid to permeate more easily in the stretched state than in the natural state, and their leak-proof performance tends to decrease. By exhibiting leakproof performance, higher leakproof properties can be imparted to the composite sheet of the present invention.

(Leak proof evaluation test)
Place the evaluation target and a pulp sheet (manufactured by Lion Corporation, Lead Healthy Cooking Paper Double (product name), basis weight 40 g/m ² ) on a filter paper (manufactured by Advantech Toyo Co., Ltd., No. 2, diameter 70 mm) in this order. Overlap with The evaluation target is fixed in a natural state, and its size in plan view is adjusted so that the entirety overlaps with the filter paper. The pulp sheet has a rectangular shape of 25 mm x 30 mm in plan view. 0.265 g of a wet tension test mixture (manufactured by Kanto Kagaku Co., Ltd.) with a surface tension of 44 mN/m at 25°C was injected into the center of the upper surface of the pulp sheet using a dropper, and immediately after the injection, the pulp sheet was A cylindrical acrylic resin plate with a diameter of 60 mm and a thickness of 5 mm was placed on top of the plate, and a 500 g weight was placed on top of the plate and pressurized for 1 hour. One hour after placing the weight, remove the weight and visually observe whether or not the test liquid oozes into the filter paper. The above series of operations is carried out three times for the evaluation object, and if no seepage of the test liquid is observed on the filter paper in any of the three times, the evaluation object is evaluated as having leak-proof properties, In other cases, it is evaluated that there is no leak-proof property.

To supplement the leak-proof evaluation test, the evaluation target (moisture-permeable film) can have a rectangular shape in plan view that is larger than the size of the pulp sheet (25 mm x 30 mm). If this size cannot be prepared because the size of the evaluation target is small, etc., cut out the largest similar shape of the square shape in plan view and use it as a test piece, and calculate the surface pressure that the pulp sheet receives and the per unit area. Perform the test by adjusting the pulp sheet and test liquid so that the test liquid volume conditions are the same. In addition, if the evaluation target is part of a product such as an absorbent article, remove the evaluation target from the product and use it for testing with sufficient care to avoid tears.
In addition, if the test liquid injected onto the top surface of the pulp sheet overflows from the pulp sheet during pressurization and enters the filter paper from the edge of the object to be evaluated, use a polyethylene film that is impermeable to the test liquid. etc., to prevent the evaluation liquid from entering the filter paper from the edge of the object to be evaluated.

The moisture permeable film has a degree of flexibility deformation in the stretching direction (the machine direction of the moisture permeable film) measured by the tensile test, preferably 0.060 N/(mm·(g/m ² )) or less, more preferably It is 0.057 N/(mm·(g/m ² )) or less, more preferably 0.055 N/(mm·(g/m ² )) or less. As a result, the composite sheet of the present invention has high elasticity and can be particularly easily stretched. Furthermore, when the composite sheet of the present invention is used as a component of an absorbent article, it can be stretched without hindering the movement of the wearer of the absorbent article, thereby reducing the discomfort felt by the wearer. The moisture permeable film described above may have a degree of flexibility deformation in the stretching direction within the above range. On the other hand, the lower limit of the flexibility deformation degree of the moisture-permeable film in the stretching direction is preferably 0.005 N/(mm·(g/m ² )) or more from the viewpoint of maintaining the strength of the composite sheet of the present invention.

The moisture-permeable film has a residual strain after 30% elongation measured by the tensile test described above, which is preferably 11% or less, more preferably 10% or less, and still more preferably 9% or less. As a result, the composite sheet of the present invention has high elasticity and can be particularly easily shrunk. Further, when the composite sheet of the present invention is used as a component of an absorbent article, the composite sheet follows the movements of the wearer of the absorbent article, so that the discomfort given to the wearer can be reduced. The moisture permeable film described above may have a residual strain within the above range after 30% elongation. On the other hand, the lower limit of the residual strain after 30% elongation of the moisture-permeable film is better as it is smaller, and is most preferably 0%.

The moisture permeable film has moisture permeability and can transmit moisture. The moisture permeable film has a moisture permeability measured in accordance with JIS L 1099 A-2, preferably 0.4 g/(100 cm ² h) or more, more preferably 0.45 g/(100 cm ² h) or more. , more preferably 0.8 g/(100 cm ² ·h) or more. As a result, the composite sheet of the present invention has high moisture permeability, and when the composite sheet is used as a component of an absorbent article, moisture inside the absorbent article can be appropriately dissipated to the outside. The moisture permeable film described above may have a moisture permeability within the above range. On the other hand, the upper limit of the moisture permeability of the moisture permeable film is preferably 4.5 g/(100 cm ² · h) or less, more preferably 3.5 g/ (100 cm ² ·h) or less, more preferably 3.0 g/(100 cm ² ·h) or less. Moisture permeability is measured by the following method.

(Method for measuring moisture permeability)
This measurement method is based on JIS L 1099 A-2. Pour about 25 mL of ion-exchanged water into a glass bottle with a diameter of 2.03 cm (area 3.23 cm ² ) (Laboran screw tube bottle No. 8, manufactured by As One), and cover the opening of the glass bottle with one test piece so that there is no gap. A test piece (for example, a moisture-permeable film) is fixed to a glass bottle with a rubber band to serve as an evaluation sample. After measuring the mass (W1) of the evaluation sample, the sample is stored in a constant temperature bath controlled at 40° C. and 20% RH for 10 to 15 hours. After storage, the mass (W2) of the evaluation sample is measured, the storage time (T1, unit: h) is recorded, and the moisture permeability is calculated using the following formula.
Moisture permeability [g/( ^100cm2・h)]={(W1-W2)/(T1×3.23)}×100

The air permeability of the moisture permeable film in its natural state is preferably 3000 seconds or less, more preferably 2500 seconds or less. Air permeability is measured by the following method. Such air permeability is an index of the time required for 25 cc of air to pass through the moisture permeable film to be evaluated in the thickness direction, and the smaller the value of air permeability, the higher the breathability of the moisture permeable film. It is evaluated as. A composite sheet including a moisture permeable film having an air permeability within the above range can have high air permeability. The moisture permeable film described above may have an air permeability within the above range. On the other hand, the lower limit of the air permeability of the moisture permeable film in its natural state is preferably 1 second or more from the viewpoint of maintaining the strength of the moisture permeable film. In addition, since the moisture permeable film used in the present invention has micropores and is stretchable, it is possible to stretch the moisture permeable film in the machine direction (stretch direction). The micropores are enlarged and the air permeability can be improved (the air permeability value can be reduced). Therefore, a preferred embodiment of the moisture permeable film used in the present invention is a moisture permeable film stretched in the machine direction (stretching direction). The stretching treatment can be performed according to a conventional method. Further, the stretching ratio is not particularly limited, but may be, for example, 1.3 times.

(Method of measuring air permeability)
This measurement method is based on JIS P8117. Using an air permeability tester (product name: Gurley Densometer, manufactured by Kumagai Riki Kogyo Co., Ltd.), measure the time required for 25 cc of air to pass through the evaluation target (moisture permeable film) in the thickness direction. . The state of the evaluation target at the time of the test is a natural state or an elongated state (for example, a 30% elongated state). If 25 cc of air does not pass through the moisture-permeable film even after 10,000 seconds or more and the measurement is not completed, the measurement is not possible and the moisture-permeable film is evaluated as having no air permeability.

Next, a preferred method for manufacturing the moisture permeable film used in the present invention will be explained.
A suitable method for producing a moisture-permeable film includes the step of stretching a resin sheet formed by melt-molding a compound containing a resin, an inorganic filler, and an additive in at least one direction.
The details of the resin, inorganic filler, and additives contained in the compound are as described above. Further, the blending amounts of the resin, inorganic filler, and additives contained in the compound are the same as the blending amounts of these components contained in the moisture permeable film. Furthermore, the types and amounts of optional components contained in the compound are also the same as those contained in the moisture permeable film.

The moisture-permeable film used in the present invention can be efficiently produced, for example, by the following method.
First, the components constituting the compound described above are premixed using a Henschel mixer, a super mixer, or the like, and then kneaded using a single-screw or twin-screw extruder to form pellets. Next, a resin sheet is obtained by forming a film using a molding machine using the obtained pellets. As the molding machine, for example, a T-die type or an inflation type can be used.

Regarding the dispersant, it may be used alone or mixed with other components constituting the compound, but preferably it is attached to the surface of the inorganic filler in advance to produce a surface-modified inorganic filler. It is preferable to prepare a compound by mixing this surface-modified inorganic filler with other components constituting the compound. By doing so, it is possible to successfully stretch the resin sheet while suppressing the occurrence of unintended pinholes, and it is possible to obtain a moisture permeable film that has both high moisture permeability and high water resistance.

When the resin sheet described above is stretched uniaxially or biaxially, interfacial peeling occurs between the resin and the inorganic filler, and micropores are formed. For this stretching, a roll method that can stretch the film in the machine direction, a tenter method that can stretch the film in the width direction in addition to the machine direction, and the like are used. In this way, the moisture-permeable film used in the present invention is obtained. The resin sheet is preferably stretched at least 1.1 times in at least one axis direction, more preferably 1.5 times or more, and preferably 2 times or more so that the area increases with stretching. More preferred. In addition, from the viewpoint of avoiding a decrease in tear strength due to excessive molecular orientation due to excessive stretching, it is preferable to stretch at 5.0 times or less, more preferably at 4.5 times or less, It is more preferable to stretch by a factor of at most 2 times.

In both uniaxial stretching and biaxial stretching, the temperature of the resin film during stretching should be set at 30°C or higher and 100°C or lower in order to uniformly stretch the film without breaking the film. The temperature is preferably 35°C or higher and 95°C or lower, and even more preferably 40°C or higher and 90°C or lower.

Although the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit of the present invention.
Regarding the embodiments of the present invention described above, the following additional notes are further disclosed.

<1>
A stretchable moisture-permeable film having micropores and a non-stretchable nonwoven fabric are overlapped and bonded to each other at a plurality of joints scattered between the mutually overlapping surfaces,
The composite sheet wherein the moisture permeable film is expandable and contractible, and as the moisture permeable film expands and contracts, the non-bonded portion of the nonwoven fabric with the moisture permeable film expands and contracts.
<2>
In the natural state of the moisture-permeable film, the moisture-permeable film has a convex portion protruding on the side opposite to the moisture-permeable film side, and a portion or the whole of the convex portion is the non-bonded portion of the nonwoven fabric, <1>. Composite sheet described in.
<3>
In the natural state of the moisture-permeable film, the plurality of pleated convex portions extend in a direction intersecting the stretching direction of the moisture-permeable film, and the joint portions are formed between adjacent convex portions. The composite sheet according to <2> above, wherein the concave portion at the bottom extends in the same direction as the convex portion.
<4>
<2>, wherein the convex portion is formed by the non-bonded portion of the nonwoven fabric protruding in a direction away from the moisture permeable film, and has a hollow portion formed by a gap between the non-bonded portion and the moisture permeable film. Or the composite sheet according to <3>.
<5>
The composite sheet according to <2> or <3>, wherein the convex portion has a solid structure in which the convex portion is filled with constituent fibers of the nonwoven fabric.
<6>
The composite sheet according to any one of <1> to <5>, wherein the nonwoven fabric contains an olefin resin.
<7>
The composite sheet according to any one of <1> to <6>, wherein the moisture permeable film and the nonwoven fabric are bonded to each other by an adhesive at the bonded portion.
<8>
The composite sheet according to <7>, wherein the adhesive contains synthetic rubber.
<9>
The composite sheet according to any one of <1> to <8>, wherein the moisture permeable film has, in addition to the micropores, pores with a larger opening diameter than the micropores.
<10>
The composite sheet according to <9> above, wherein the pores have an opening diameter of preferably 0.5 mm or more, more preferably 0.6 mm or more, and preferably 10 mm or less, more preferably 8 mm or less.
<11>
Any one of <1> to <10> above, wherein the opening diameter of the micropores is preferably 0.001 μm or more, more preferably 0.005 μm or more, and preferably 500 μm or less, more preferably 300 μm or less. Composite sheet as described in Section.

<12>
The composite sheet according to any one of <1> to <11>, wherein the moisture-permeable film is evaluated to have leak-proof properties in a natural state in the leak-proof evaluation test.
<13>
The degree of flexibility deformation of the moisture permeable film in the stretching direction (machine direction) is preferably 0.060 N/mm or less, more preferably 0.057 N/(mm·(g/m ² )) or less, and even more preferably 0.060 N/mm or less, more preferably 0.057 N/(mm·(g/m 2 )) or less. 0.055 N/mm or less, and preferably 0.005 N/mm or more, the composite sheet according to any one of <1> to <12> above.
<14>
The residual strain of the moisture permeable film after 30% elongation is preferably 11% or less, more preferably 10% or less, even more preferably 9% or less, and preferably 0%. The composite sheet according to any one of Item 1.
<15>
The air permeability of the moisture permeable film in its natural state measured by the method is preferably 3000 seconds or less, more preferably 2500 seconds as the time required for 25 cc of air to pass through the moisture permeable film in the thickness direction. The composite sheet according to any one of <1> to <14> below, and preferably 1 second or more.
<16>
The basis weight of the moisture permeable film is preferably 5 g/m ² or more, more preferably 6 g/m ² or more, and preferably 100 g/m ² or less, more preferably 90 g/m ² or less, The composite sheet according to any one of items ＞ to <15>.
<17>
The basis weight of the nonwoven fabric is preferably 5 g/m ² or more, more preferably 6 g/m ² or more, and preferably 100 g/m ² or less, more preferably 90 g/m ² or less, <1> to The composite sheet according to any one of <16>.

<18>
The moisture permeable film contains a resin and an inorganic filler,
Any one of <1> to <17> above, wherein the content of the inorganic filler in the moisture permeable film is 50 parts by mass or more and 400 parts by mass or less based on 100 parts by mass of the resin in the moisture permeable film. The composite sheet according to item 1.
<19>
The composite sheet according to <18>, wherein the resin includes an olefin resin composition having a density of 0.840 g/cm ³ or more and less than 0.900 g/cm ³ .
<20>
The density of the olefin resin composition is preferably 0.850 g/cm ³ or more and 0.895 g/cm ³ or less, more preferably 0.860 g/cm ³ or more and 0.885 g/cm ³ or less, and <19 ＞The composite sheet described in ＞.
<21>
The composite sheet according to <19> or <20>, wherein the olefin resin composition contains a low melting point olefin resin having a melting point of less than 90°C and a high melting point olefin resin having a melting point of 95°C or higher. .
<22>
The moisture permeable film contains a pore opening promoter of 0.1 parts by mass or more and 20 parts by mass or less based on 100 parts by mass of the resin in the moisture permeable film, and the pore opening promoter is a metal soap. The composite sheet according to any one of <18> to <21>.

<23>
The moisture-permeable film contains 0.1 parts by mass or more and 30 parts by mass or less of triglyceride based on 100 parts by mass of the resin in the moisture-permeable film, and the triglyceride contains a fatty acid having 16 to 22 carbon atoms. The composite sheet according to any one of <18> to <22>, wherein the composite sheet contains a group derived from the above-mentioned group, and the group is a hydrocarbon group having no unsaturated bond and no substituent.
<24>
The triglyceride contains at least a group derived from a fatty acid having 18 carbon atoms in one molecule and a group derived from a fatty acid having 16 to 22 carbon atoms (excluding fatty acids having 18 carbon atoms) in one molecule. The composite sheet according to <23> above, which is a mixture of at least triglyceride.
<25>
The triglyceride contains in one molecule at least one group derived from a saturated fatty acid having 18 carbon atoms, and at least one group derived from a saturated fatty acid having 16 to 22 carbon atoms (excluding fatty acids having 18 carbon atoms). The composite sheet according to <23> above, which contains at least one triglyceride.
<26>
Preferably from 28% by mass to 96% by mass, more preferably from 28% by mass to 70% by mass, even more preferably from 29% by mass to the total amount of groups derived from fatty acids contained in all triglycerides in the moisture permeable film. <23> to <25 above, wherein 67% by mass or less is a group derived from a fatty acid having 18 carbon atoms (the group is a hydrocarbon group having no unsaturated bond or substituent). ＞The composite sheet according to any one of ＞.
<27>
Based on the total amount of groups derived from fatty acids contained in all triglycerides in the moisture permeable film, 28% by mass or more and 68% by mass or less are groups derived from fatty acids having 18 carbon atoms, and 26% by mass The composite sheet according to any one of <23> to <26>, wherein 70% by mass or less is a group derived from a fatty acid having 16 carbon atoms.
<28>
Of the total amount of groups derived from fatty acids contained in all the triglycerides in the moisture-permeable film, 28% by mass or more and 47% by mass or less are groups derived from fatty acids having 18 carbon atoms (the groups are unsaturated It is a hydrocarbon group that has no bonds or substituents), and 40% by mass or more and 60% by mass or less is a group derived from a fatty acid having 22 carbon atoms (the group has an unsaturated bond and a substituent). The composite sheet according to any one of <23> to <26> above, wherein the composite sheet is a hydrocarbon group that does not contain a hydrocarbon group.
<29>
The composite sheet according to any one of <23> to <28>, wherein the groups derived from fatty acids contained in all the triglycerides in the moisture permeable film are hydrocarbon groups having no unsaturated bonds. .
<30>
The composite sheet according to any one of <23> to <29>, wherein the groups derived from fatty acids contained in all triglycerides in the moisture permeable film are hydrocarbon groups having no substituents.
<31>
An absorbent article comprising the composite sheet according to any one of <1> to <30>.
<32>
The absorbent article has a vertical direction extending from the ventral side of the wearer through the crotch region to the back side, and a horizontal direction perpendicular to the vertical direction,
The absorbent article according to <31>, wherein the composite sheet has stretchability in the longitudinal direction or the lateral direction.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples.

[Manufacture of moisture permeable films A to E]
The ingredients listed in the "Raw Materials" column of Table 1 below were weighed to the amounts shown in the table. These were mixed using a Henschel mixer (manufactured by Kawata Co., Ltd.). The resulting mixture was kneaded using a twin-screw extruder (manufactured by Toyo Seiki) at a set temperature of 180° C. and a screw rotation speed of 180 rpm to obtain a pelletized compound.
A moisture permeable film was manufactured using the obtained compound. Specifically, first, using a compound as a raw material, a resin sheet was made from the compound melted under conditions of a blow ratio of 2.5 using an inflation molding machine with a slit diameter of 100 mm at the die discharge part and a gap of 0.9 mm. Molded. The temperature setting of the die was 200° C., and the take-up speed was 10 m/min. Next, the molded resin sheet was uniaxially stretched in the machine direction using a roll stretching machine to obtain moisture permeable films A to E having the basis weights shown in Table 1. The stretching ratio and stretching temperature are as shown in the same table. All of the moisture permeable films A to D have micropores and are stretchable in the stretching direction (machine direction). On the other hand, the moisture-permeable film E has micropores but does not have stretchability.

Details of the raw materials used in the production of moisture permeable films A to E are as follows.
- Olefin resin A (corresponding to the low melting point olefin resin): Ethylene-α olefin copolymer produced with a metallocene catalyst, melting point 44°C, resin density 0.864 g/cm ³
- Olefin resin B (equivalent to the high melting point olefin resin): linear low density polyethylene produced with a metallocene catalyst, melting point 116°C, resin density 0.924 g/cm ³
・Inorganic filler: calcium carbonate, average particle size D50: 1.8 μm
・Dispersant: Stearic acid ・Specific triglyceride: Extremely hardened palm oil (C14: 1%, C16: 42%, C18: 57%)
・Pore opening accelerator (metallic soap): Zinc stearate, precipitation temperature 102°C, melting point 124°C

Various physical properties of moisture permeable films A to E were measured. In addition, various physical properties of a moisture-permeable film F (urethane elastomer film, manufactured by Okura Kogyo Co., Ltd., Silkron ES85), which does not have micropores and has elasticity, were also measured. The results are shown in Table 1.
Air permeability was measured by the method for measuring air permeability described above. The state of the evaluation target (moisture permeable film) during measurement was in two types: a natural state and a state where it was stretched 1.3 times in one direction (machine direction) where it could be stretched (30% stretched state). Note that the air permeability of the moisture permeable film F could not be measured because the air permeability was too low. Furthermore, since the moisture permeable film E does not have stretchability, the air permeability in the stretched state was not evaluated.
The leak-proof property was evaluated by the above-mentioned leak-proof property evaluation test. However, the moisture permeable film to be evaluated was in a natural state or in a 30% stretched state. In addition to the test liquid having a surface tension of 44 mN/m at 25°C, a test liquid having a surface tension of 35 mN/m at 25°C was used as a more severe condition. As these test liquids, a mixed liquid for wet tension test manufactured by Kanto Kagaku Co., Ltd. was used. In the "Leakproof" column of Table 1, "A" means leakproof, and "B" means no leakproof. In addition, since the moisture-permeable film E does not have elasticity, leak-proofing properties in the stretched state were not evaluated.

[Examples 1-2, Comparative Example 1: Production of composite sheet]
By using the moisture-permeable film C or F and the non-stretchable nonwoven fabric, a composite sheet is produced by the above-mentioned manufacturing method A or B. A part or all of a plurality of pleated convex portions protruding to the opposite side and extending in one direction are formed, and between the adjacent convex portions, the joint portion of the film and the nonwoven fabric is formed at the bottom. A "composite sheet" in which concave portions and convex portions extend in the same direction as the convex portions was manufactured.
In the method for manufacturing a composite sheet according to manufacturing method A, the moisture permeable film is stretched by 60% in the machine direction, and 10 g/m ² of adhesive is applied in advance to one side of the stretched moisture permeable film in a summit shape. After the one side of the intermittently applied non-stretchable nonwoven fabric was overlapped and bonded together, the moisture permeable film was released from the stretched state to produce the desired composite sheet.
In the method for manufacturing a composite sheet according to manufacturing method B, the moisture permeable film is in an unstretched state, and one surface of a non-stretchable nonwoven fabric is coated with an adhesive of 4 g/m ² intermittently in a summit shape on one surface. By superimposing them to obtain a composite sheet precursor, and subjecting the composite sheet precursor to tooth groove stretching using a pair of tooth groove rolls at a pushing depth of 3.7 mm and a conveyance speed after the tooth groove of 10 m/min. The desired composite sheet was manufactured.
In the manufacturing method A, a spunbond nonwoven fabric whose constituent fibers were made of olefin resin and had a basis weight of 17 g/m ² was used as the non-stretchable nonwoven fabric. In the manufacturing method B, an air-through nonwoven fabric with a basis weight of 29 g/m ² whose constituent fibers are made of olefin resin was used as the non-stretchable nonwoven fabric. As the adhesive, a hot melt adhesive containing synthetic rubber was used.

[Performance evaluation of composite sheet]
The composite sheets of each Example and Comparative Example were evaluated for air permeability, moisture permeability, leak resistance, and elasticity by the following methods. The results are shown in Table 2 below.

(Method for evaluating breathability of composite sheet)
The air permeability (time required for 25 cc of air to permeate the composite sheet in the thickness direction) of the composite sheet was measured according to the method for measuring air permeability described above. However, the state of the composite sheet at the time of measurement was a state in which it was stretched 1.3 times in one direction (stretched by 30%). The case where the air permeability was 3000 seconds or less was rated A (highest evaluation of air permeability), and the other cases were rated B.

(Evaluation method of moisture permeability of composite sheet)
The moisture permeability of the composite sheet was measured according to the method for measuring moisture permeability described above. That is, in the method for measuring moisture permeability, a composite sheet was used as a test piece. The case where the moisture permeability was 0.4 g/(100 cm ² ·h) or more was rated A (highest evaluation of moisture permeability), and the other cases were rated B.

(Method for evaluating leakproof properties of composite sheet)
The leak-proof property of the composite sheet was evaluated according to the leak-proof property evaluation test described above. That is, in the leak-proofing evaluation test, a composite sheet was used as the evaluation object, and the test was conducted with the composite sheet stretched 1.3 times in one stretchable direction (machine direction) (30% stretched state). . The test is conducted three times for one type of evaluation target, and the case where no seepage of the test liquid is observed on the filter paper in any of the three tests is rated A (highest rating for leak-proofing), and the other cases are rated B. did.

(Evaluation method of elasticity of composite sheet)
The residual strain of the composite sheet after 30% elongation was measured according to the cycle test in the tensile test. That is, in the cycle test, a composite sheet was used as the evaluation object. For one type of evaluation object, the residual strain after 30% elongation in two directions: "machine direction" (flow direction during manufacture of the evaluation object) and "direction orthogonal to the machine direction" is measured, and A case where either one of the residual strains after 30% elongation was 11% or less was rated A (highest evaluation of stretchability), and other cases were rated B.

As shown in Table 2, the composite sheet of each example is a moisture permeable film that is non-porous and does not exhibit any air permeability because the moisture permeable film constituting the composite sheet is a moisture permeable film C having micropores. Compared to Comparative Example 1, which is Film F, it had excellent air permeability. In addition, in each of the composite sheets of Examples and Comparative Examples, convex portions and concave portions (non-bonded portions of the nonwoven fabric) are regularly arranged on the nonwoven fabric side surface, similar to the composite sheet 1 shown in FIG. 1. As a result, the surface had a good feel and appearance.

1, 1A, 1B Composite sheet 2 Moisture-permeable film 3 Non-woven fabric 31 Non-bonded part of non-woven fabric 4 Joint part 5 Convex part 6 Concave part 7 Hollow part 10 Disposable diaper (absorbent article)
11 Absorbent main body 20 Exterior body 21 Outer layer sheet 21A Ventral outer layer sheet 21B Inseam outer layer sheet 21C Dorsal outer layer sheet 22 Inner layer sheet

Claims (16)

A stretchable moisture-permeable film having micropores and a non-stretchable nonwoven fabric are overlapped and bonded to each other at a plurality of joints scattered between the mutually overlapping surfaces,
The composite sheet wherein the moisture permeable film is expandable and contractible, and as the moisture permeable film expands and contracts, the non-bonded portion of the nonwoven fabric with the moisture permeable film expands and contracts. 2. The method according to claim 1, wherein in the natural state of the moisture permeable film, the moisture permeable film has a convex portion protruding on a side opposite to the moisture permeable film side, and a portion or the entire of the convex portion is the non-bonded portion of the nonwoven fabric. Composite sheet as described. In the natural state of the moisture-permeable film, the plurality of pleated convex portions extend in a direction intersecting the stretching direction of the moisture-permeable film, and the joint portions are formed between adjacent convex portions. The composite sheet according to claim 2, wherein the concave portion at the bottom extends in the same direction as the convex portion. 3. The convex portion is formed by the non-bonded portion of the nonwoven fabric protruding in a direction away from the moisture permeable film, and has a hollow portion formed by a gap between the non-bonded portion and the moisture permeable film. 3. The composite sheet described in 3. The composite sheet according to claim 2 or 3, wherein the convex portion has a solid structure in which the convex portion is filled with constituent fibers of the nonwoven fabric. The composite sheet according to any one of claims 1 to 5, wherein the nonwoven fabric contains an olefin resin. The composite sheet according to any one of claims 1 to 6, wherein the moisture permeable film and the nonwoven fabric are bonded to each other by an adhesive at the bonded portion. The composite sheet according to claim 7, wherein the adhesive includes synthetic rubber. The composite sheet according to any one of claims 1 to 8, wherein the moisture permeable film has, in addition to the micropores, pores with a larger opening diameter than the micropores. The moisture permeable film contains a resin and an inorganic filler,
According to any one of claims 1 to 9, the content of the inorganic filler in the moisture permeable film is 50 parts by mass or more and 400 parts by mass or less based on 100 parts by mass of the resin in the moisture permeable film. Composite sheet as described. The composite sheet according to claim 10, wherein the resin includes an olefin resin composition having a density of 0.840 g/cm ³ or more and less than 0.900 g/cm ³ . The composite sheet according to claim 11, wherein the olefin resin composition contains a low melting point olefin resin having a melting point of less than 90°C and a high melting point olefin resin having a melting point of 95°C or higher. The moisture permeable film contains a pore opening promoter of 0.1 parts by mass or more and 20 parts by mass or less based on 100 parts by mass of the resin in the moisture permeable film, and the pore opening promoter is a metal soap. The composite sheet according to any one of items 10 to 12. The moisture-permeable film contains 0.1 parts by mass or more and 30 parts by mass or less of triglyceride based on 100 parts by mass of the resin in the moisture-permeable film, and the triglyceride contains a fatty acid having 16 to 22 carbon atoms. The composite sheet according to any one of claims 10 to 13, wherein the composite sheet contains a group derived from the above-mentioned group, and the group is a hydrocarbon group having no unsaturated bond and no substituent. An absorbent article comprising the composite sheet according to any one of claims 1 to 14. The absorbent article has a vertical direction extending from the ventral side of the wearer through the crotch region to the back side, and a horizontal direction perpendicular to the vertical direction,
The absorbent article according to claim 15, wherein the composite sheet has stretchability in the longitudinal direction or the transverse direction.

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