JP6680586B2 - Porous elastic film, method for producing the same, and composite sheet - Google Patents

Description

  The present invention relates to a porous stretchable film having a plurality of through holes, a method for producing the same, and a composite sheet having a layer made of a porous stretchable film and a layer made of a nonwoven fabric.

  In the hygiene field (sanitary products, incontinence products, etc.), the medical field (surgical drapes, etc.), etc., elastic composite sheets obtained by laminating an elastic film containing a thermoplastic elastomer and a nonwoven fabric are widely used. .

Since the thermoplastic elastomer has strong adhesiveness, the stretch films and the composite sheets may come into close contact with each other and may be difficult to peel off, so-called blocking may occur.
As the stretchable film in which the occurrence of blocking is suppressed, for example, the following have been proposed.
(1) An elastic film having an elastomer layer containing a thermoplastic elastomer and a surface layer containing a thermoplastic resin provided on both the first surface and the second surface of the elastomer layer (Patent Document 1).

In addition, since the stretchable film easily fits into the body without any gaps, it may cause stuffiness or heat rash. Therefore, a porous stretchable film having good air permeability is desired. As a method for opening the film, generally, slitting, punching, hot needle punching, hot roll calendering, ultrasonic perforation and the like can be mentioned.
As the porous stretchable film, for example, the following have been proposed.
(2) A reticulated stretchable film in which openings such as slits and holes are formed in a stretchable film containing a thermoplastic elastomer (Patent Document 2).

International Publication No. 2016/013577 JP 2002-155460 A

When the technique for producing the reticulated stretchable film of (2) is applied to the stretchable film of (1), it is possible to obtain a porous stretchable film in which the occurrence of blocking is suppressed and which has good air permeability.
However, since the elastic film (1) has a surface layer having no elasticity, the elasticity is slightly insufficient. Therefore, in the porous stretchable film in which the opening is formed in the stretchable film of (1) by a general method such as slitting, stress is concentrated in the opening when the film is stretched, and is easily broken from the opening. As a result, the stretchability of the porous stretchable film is further reduced.

  The present invention provides a porous stretchable film in which the occurrence of blocking is suppressed, air permeability is good, and it is difficult to break when stretched and the stretchability is not lowered, a method for producing the same, and a composite sheet.

The present invention has the following aspects.
<1> A surface containing an elastomer layer containing a thermoplastic elastomer and a thermoplastic resin (excluding the thermoplastic elastomer) provided on one or both of the first surface and the second surface of the elastomer layer. A porous stretchable film having a layer and a plurality of through-holes formed therein; the porous stretchable film has a strip-shaped first region extending along a surface direction of the porous stretchable film and the first region. A porous stretchable film, which is adjacent to and alternate with band-shaped second regions extending along the surface direction of the porous stretchable film that are less likely to stretch than the first regions.
<2> The porous stretchable film according to <1>, wherein the average opening area of the through holes is 0.1 to 1.5 mm ² .
<3> The porous stretchable film according to <1> or <2>, wherein the number of the through holes is 1 to 20 per 1 cm ² of the porous stretchable film.
<4> The porous stretchable film according to any one of <1> to <3>, wherein the surface layer further contains an inorganic filler.
<5> A method for producing the porous stretchable film according to any one of the above <1> to <4>; an elastomer layer containing a thermoplastic elastomer, and one of a first surface and a second surface of the elastomer layer. By embossing a non-porous stretchable film having a surface layer containing a thermoplastic resin (excluding the thermoplastic elastomer) provided on one or both sides, a plurality of depressions scattered in the non-porous stretchable film Forming a part; a first shaping roll having a plurality of ridges extending in the circumferential direction or the axial direction, and a plurality of ridges extending in the same direction as the ridges of the first shaping roll. While the second shaping roll is arranged and rotated so as to face each other so that the ridges of one shaping roll and the grooves between the ridges of the other shaping roll engage with each other, With the second shaping roll The first region stretched between the ridges of the first shaping roll and the ridges of the second shaping roll by passing the embossed non-porous stretchable film in between. And a step of forming the unstretched second region and simultaneously stretching the recess to form the through hole.
<6> The method for producing a porous stretchable film according to <5>, wherein the following permanent set of the non-porous stretchable film is 15% or more.
(Permanent strain of non-porous stretchable film)
A strip test piece of 50 mm in the machine direction (MD) and 200 mm in the width direction (TD) is cut out from the non-porous stretchable film. The test piece is fixed to the grip of the test apparatus so that the distance between the grips is 100 mm. The test piece is stretched in TD at a speed of 100 mm / min so that the elongation calculated by the following formula (I) is 80%, and then the test piece is immediately contracted at the same speed. Permanent strain (%) is calculated from the following formula (II).
Elongation = (L1-L0) / L0 × 100 (I)
Permanent strain = (L2-L0) / (L1-L0) × 100 (II)
However, L0 is the distance between grips (mm) before extension, L1 is the distance between grips (mm) after extension, and L2 is the load (N / It is the distance (mm) between the grips when 50 mm) becomes zero.
<7> A composite sheet having a layer made of the porous stretchable film according to any one of the above <1> to <4> and a layer made of a nonwoven fabric.

In the porous stretchable film of the present invention, the occurrence of blocking is suppressed, the air permeability is good, and the stretchable stretchable film is unlikely to break when stretched.
According to the method for producing a porous stretchable film of the present invention, it is possible to produce a porous stretchable film in which the occurrence of blocking is suppressed, the breathability is good, and the stretchable stretch film is unlikely to break when stretched.
In the composite sheet of the present invention, the occurrence of blocking due to the layer made of the porous stretchable film is suppressed, the air permeability is good, and the layer made of the porous stretchable film is unlikely to break when stretched, and the stretchability is less likely to decrease.

It is the photograph which looked at an example of the porous expansion-contraction film of the present invention from the upper surface. It is an enlarged photograph of the porous expansion-contraction film of FIG. It is an enlarged photograph of the state which expanded the porous expansion-contraction film of FIG. 1 so that elongation might become 80% in TD. It is sectional drawing which shows an example of the non-porous elastic film used for manufacture of the porous elastic film of this invention. It is an enlarged view showing an example of a pair of shaping rolls. It is an enlarged view showing other examples of a pair of shaping rolls.

The following definitions of terms apply throughout the specification and claims.
"Thermoplastic elastomer" has properties similar to those of vulcanized rubber at the operating temperature, disappears at the processing temperature, can be easily processed, and returns to the operating temperature at its original properties. Means a coalesced or polymer blend.
The term "thermoplastic resin" means a synthetic resin that can be molded into a thermoplastic resin by heating. However, in the present invention, the thermoplastic resin does not include a thermoplastic elastomer.
"The second region is less likely to be stretched than the first region (the first region is more likely to be stretched than the second region)" means that the porous stretchable film is longer than the first region and the second region. When extended in the direction orthogonal to the direction, the elongation (%) of the second region is smaller than the elongation (%) of the first region (the first region is larger than the elongation (%) of the second region). Elongation (%) is large).

<Porous stretch film>
The porous stretchable film of the present invention is a stretchable film having a plurality of through holes formed therein.
INDUSTRIAL APPLICABILITY The porous stretchable film of the present invention includes a thermoplastic resin (excluding the thermoplastic elastomer) provided on one or both of the elastomer layer containing the thermoplastic elastomer and the first surface and the second surface of the elastomer layer. And a surface layer containing.
The porous stretchable film of the present invention has a strip-shaped first region extending along the surface direction of the porous stretchable film, and a surface direction of the porous stretchable film that is adjacent to the first region and is less likely to stretch than the first region. Alternating with strip-shaped second regions extending along.

FIG. 1 is a photograph of an example of the porous stretchable film of the present invention seen from above, and FIG. 2 is an enlarged photograph of the porous stretchable film of FIG.
The porous stretchable film 10 includes an elastomer layer, a first surface layer provided on the first surface of the elastomer layer, and a second surface layer provided on the second surface of the elastomer layer (hereinafter referred to as “first surface layer”). The surface layer and the second surface layer are collectively referred to simply as the surface layer.). Illustration of the cross section of the porous stretchable film 10 is omitted.

In the porous stretchable film 10, strip-shaped first regions 11 extending in MD and strip-shaped second regions 12 extending in MD are alternately formed in TD to form a striped pattern.
The through holes 13 are formed at equal intervals in the length direction of each first region 11, and are arranged in a staggered manner in the entire porous stretchable film 10.
In FIGS. 1 and 2, since the background is black, the first area 11 is seen as an opaque white portion, the second area 12 is seen as a transparent gray portion, and the through hole 13 is shown as a black portion. appear.

(Elastomer layer)
The elastomer layer is a layer that imparts stretchability to the porous stretchable film.
The elastomer layer may be a single layer or multiple layers.

The elastomer layer includes a thermoplastic elastomer.
The elastomer layer may contain other components, if necessary, within a range that does not impair the effects of the present invention.

Thermoplastic elastomer:
Examples of the thermoplastic elastomer include olefin-based thermoplastic elastomer, styrene-based thermoplastic elastomer, urethane-based thermoplastic elastomer, and polyester-based thermoplastic elastomer. When the thermoplastic resin in the surface layer is an olefin resin, an olefin thermoplastic elastomer is preferable from the viewpoint of compatibility.

The thermoplastic elastomer is composed of hard segments and soft segments.
Examples of the hard segment of the olefinic thermoplastic elastomer include polyethylene and polypropylene. Examples of the soft segment of the olefin thermoplastic elastomer include ethylene propylene rubber (EPDM, EPM, EEM), hydrogenated (styrene) butadiene rubber, polyoctene, and the like.
Examples of the hard segment of the styrene-based thermoplastic elastomer include polystyrene. Examples of the soft segment of the styrene-based thermoplastic elastomer include polybutadiene, polyisoprene, polyethylene, and hydrogenated products thereof.

Examples of commercially available olefin-based thermoplastic elastomers include the following.
Vistamaxx (registered trademark) 6102 (manufactured by ExxonMobil, propylene-ethylene copolymer, glass transition temperature: -32 ° C, ethylene unit content: 16% by mass),
Vistamaxx (registered trademark) 3020 (manufactured by ExxonMobil, propylene-ethylene copolymer, glass transition temperature: -26 ° C, ethylene unit content: 11% by mass),
Infuse (registered trademark) 9107 (manufactured by Dow Chemical Co., ethylene-octene copolymer, glass transition temperature: -62 ° C),
Infuse (registered trademark) 9507 (manufactured by Dow Chemical Company, ethylene-octene copolymer, glass transition temperature: -62 ° C) and the like.
The thermoplastic elastomer may be used alone or in combination of two or more.

Other ingredients:
Other components include thermoplastic resins (excluding thermoplastic elastomers), inorganic fillers, amide-based antiblocking agents (stearic acid amide, etc.), antioxidants, weather resistance stabilizers, antistatic agents, antifogging agents, Examples include metal soaps, waxes, fungicides, antibacterial agents, nucleating agents, flame retardants, lubricants and the like.

Examples of the thermoplastic resin include olefin resins such as polyethylene and polypropylene.
Examples of the inorganic filler include calcium carbonate, zeolite, silica and the like.
Other components may be masterbatched and added to the material for forming an elastomer layer.
As the other components, one type may be used alone, or two or more types may be used in combination.

Ratio of each component in the elastomer layer:
The proportion of the thermoplastic elastomer is preferably 70% by mass or more and more preferably 80% by mass or more based on 100% by mass of the elastomer layer. When the proportion of the thermoplastic elastomer is at least the lower limit value of the above range, excellent stretchability can be easily obtained. The upper limit of the proportion of the thermoplastic elastomer is 100% by mass.

  The proportion of the thermoplastic resin (excluding the thermoplastic elastomer) is preferably 0 to 20 mass% in the total 100 mass% of the resin components in the elastomer layer. When the proportion of the thermoplastic resin is at most the upper limit value of the above range, excellent stretchability is easily obtained.

Elastomer layer thickness:
The thickness of the elastomer layer is preferably 5 to 50 μm, more preferably 10 to 45 μm, still more preferably 15 to 40 μm. When the thickness of the elastomer layer is not less than the lower limit of the above range, the expansion / contraction force of the porous stretchable film is sufficiently obtained, so that the shrinkage force when the porous stretchable film is applied to a product is sufficiently obtained. When the thickness of the elastomer layer is not more than the upper limit of the above range, it is possible to prevent the stretching force of the porous stretchable film from becoming excessive and the shrinkage force when applied to a product becoming too strong.
When the elastomer layer is a multilayer, the thickness of the elastomer layer is the thickness of the entire multilayer.

(Surface layer)
The surface layer is a layer that suppresses blocking of the porous stretchable film.
The surface layer is provided on either or both of the first surface and the second surface of the elastomer layer. From the viewpoint that the occurrence of blocking of the porous stretchable film is sufficiently suppressed, it is preferably provided on both the first surface and the second surface of the elastomer layer. The first surface layer provided on the first surface and the second surface layer provided on the second surface of the elastomer layer may be the same kind of surface layer or different kinds of surface layers. May be.

The surface layer contains a thermoplastic resin (excluding the thermoplastic elastomer).
The surface layer preferably further contains an inorganic filler.
The surface layer may contain other components, if necessary, within a range that does not impair the effects of the present invention.

Thermoplastic resin:
As the thermoplastic resin, those having compatibility with the thermoplastic elastomer in the elastomer layer are preferable. When the thermoplastic elastomer in the elastomer layer is an olefinic thermoplastic elastomer, an olefinic resin such as polyethylene or polypropylene is preferable from the viewpoint of compatibility.
The thermoplastic resins may be used alone or in combination of two or more.

Inorganic filler:
The inorganic filler is a component that imparts slipperiness to the surface of the surface layer and further suppresses blocking of the porous stretchable film.
Examples of the inorganic filler include calcium carbonate, zeolite, silica and the like.
The inorganic filler may be used alone or in combination of two or more.

The average particle diameter of the inorganic filler is preferably 2 to 10 μm. When the average particle size of the inorganic filler is at least the lower limit value of the above range, the slipperiness is improved. When the average particle diameter of the inorganic filler is not more than the upper limit value of the above range, the touch will be good.
The average particle diameter of the inorganic filler is an average value of particle diameters of 10 particles randomly selected in the scanning electron microscope image.

  The inorganic filler may be masterbatched and added to the surface layer forming material. Further, the masterbatch of the inorganic filler may be directly used as the surface layer forming material. Examples of the base resin of the masterbatch include olefin resins such as polyethylene and polypropylene, and polyethylene is preferable from the viewpoint of versatility.

Examples of commercially available inorganic batch masterbatches include the following.
TEP 1HC783 WHT (manufactured by HANIL TOYO, calcium carbonate (average particle diameter: 5 μm, content rate: 50% by mass), base resin: polyethylene),
PE180NLD2 (Samplac Industry Co., Ltd., calcium carbonate (average particle diameter: 5 μm, content rate: 50 mass%), base resin: polyethylene),
Quinoplus EMB-7A2806AC (manufactured by Sumika Color Co., Ltd., zeolite (average particle diameter: 2 μm, content rate: 20 mass%), base resin: polyethylene),
Smooth Master S (manufactured by Dainichiseika Kogyo Co., Ltd., silica (average particle diameter 10 μm, content rate: 20 mass%), base resin: polyethylene) and the like.
The masterbatch may be used alone or in combination of two or more.

Other ingredients:
Other components include amide-based antiblocking agents (stearic acid amide, etc.), antioxidants, weathering stabilizers, antistatic agents, antifogging agents, metal soaps, waxes, fungicides, antibacterial agents, nucleating agents, Examples include flame retardants and lubricants.

Other components may be masterbatched and added to the surface layer forming material.
Examples of the masterbatch of the amide-based antiblocking agent include Rikemaster EXR-040 (manufactured by Riken Vitamin Co., masterbatch containing stearic acid amide (stearic acid amide content: 15% by mass), base resin: polyethylene).
As the other components, one type may be used alone, or two or more types may be used in combination.

Ratio of each component in the surface layer:
The proportion of the thermoplastic resin is preferably 10 to 90% by mass, and more preferably 15 to 85% by mass, based on 100% by mass of the surface layer. If the ratio of the thermoplastic resin is at least the lower limit value of the above range, the surface layer can be formed.
The thermoplastic resin also includes a masterbatch base resin.

  The proportion of the inorganic filler is preferably 10 to 90% by mass and more preferably 15 to 85% by mass based on 100% by mass of the surface layer. When the proportion of the inorganic filler is at least the lower limit value of the above range, the blocking of the porous stretchable film can be sufficiently suppressed. Further, the surface layer is easily broken during the gear stretching described later. When the proportion of the inorganic filler is at most the upper limit value of the above range, the surface layer can be formed.

Surface layer thickness:
The thickness of the surface layer is preferably 0.5 to 10 μm, more preferably 2 to 9 μm, and further preferably 3 to 8 μm. When the thickness of the surface layer is at least the lower limit value of the above range, the occurrence of blocking of the porous stretchable film can be sufficiently suppressed. When the thickness of the surface layer is not more than the upper limit value of the above range, the stretchability of the porous stretchable film can be sufficiently obtained. The first surface layer provided on the first surface of the elastomer layer and the second surface layer provided on the second surface may have the same thickness or different thicknesses.

(First area and second area)
The first region is a portion where the surface layer is stretched and broken when the non-porous stretchable film is stretched in a stripe shape by gear stretching described later.
The second region is a portion in which the surface layer was not stretched and broken when the non-porous stretchable film was stretched in a stripe shape by gear stretching described later.

In the first region, although the surface layer remains, the surface layer is stretched and broken, and therefore the stretchability is close to that of the elastomer layer alone.
In the second region, the surface layer is not stretch-broken, that is, the non-stretchable surface layer remains on the surface of the elastomer layer, and thus the stretchability is somewhat insufficient.
Therefore, the second region is less likely to expand than the first region, and the first region is easier to expand than the second region.

The following average elongation ratio of the first region is preferably 1.51 to 5.00 times, more preferably 1.60 to 4.50 times.
The following average elongation ratio of the second region is preferably 1.01 to 1.50 times, and more preferably 1.01 to 1.48 times.

Average elongation ratio:
A strip-shaped test piece of 50 mm in the longitudinal direction of the first region and the second region and 100 mm in the direction orthogonal to the longitudinal direction is cut out from the porous stretchable film. The test piece is fixed to the grip of the test apparatus so that the distance between the grips is 30 mm. The test piece is elongated in a direction orthogonal to the longitudinal direction of the first region and the second region at a speed of 100 mm / min so that the elongation calculated by the following formula (I) is 80%. The extension ratio (fold) is calculated from the following formula (III). The expansion ratios of twelve randomly selected areas in both the first area and the second area are calculated, and the average value is obtained.
Elongation = (L1-L0) / L0 × 100 (I)
Expansion ratio = R1 / R0 (III)
However, L0 is the distance between grips (mm) before extending, L1 is the distance between grips (mm) after extending, and R0 is the first region or the second before extending. Is a length (μm) in the direction orthogonal to the longitudinal direction of the region (1), and R1 is a length (μm) in the direction orthogonal to the longitudinal direction of the expanded first region or the second region ( However, R0 and R1 are measured at the same location in the same region).

If the average expansion ratio of the second region is within the range and the average expansion ratio of the first region is not less than the lower limit value of the range, the surface layer is destroyed when the porous stretchable film is expanded. The first region extends preferentially. Therefore, the stress applied to the periphery of the through hole is also reduced, and breakage during expansion is less likely to occur. In addition, the second region where the surface layer is not broken has high rigidity and the amount of deformation when the porous stretchable film is stretched is small, so that the breakage is unlikely to occur.
If the average expansion ratio of the first region is equal to or less than the upper limit value of the above range, appropriate elasticity can be obtained.

  The width of the first region and the width of the second region before stretching are not particularly limited and may be appropriately determined depending on the stretchability, air permeability, flexibility and the like required for the porous stretchable film.

(Through hole)
The through hole may be formed in the first region or may be formed in the second region.
Regardless of whether the through hole is formed in the first region or the second region, breakage caused by the through hole is unlikely to occur when the porous stretchable film is stretched. The first region expands with low stress because the surface layer is destroyed. Therefore, the stress applied to the periphery of the through hole is also reduced, and breakage during expansion is unlikely to occur. On the other hand, in the second region, since the surface layer is not broken, the rigidity is high and the deformation during expansion is unlikely to occur, so that the breakage is unlikely to occur.
When the porous stretchable film is manufactured by the manufacturing method of the present invention described later, most of the through holes are formed in the first region.

0.1-1.5 mm < ² > is preferable and, as for the average value of the opening area of a through-hole, 0.2-1.4 mm < ² > is more preferable. When the average value of the opening areas of the through holes is not less than the lower limit value of the above range, the air permeability of the porous stretchable film is further improved. When the average value of the opening area of the through holes is equal to or less than the upper limit value of the above range, breakage caused by the through holes is further unlikely to occur when the porous stretchable film is stretched.
The average value of the opening areas of the through holes is the average value of the opening areas of the 50 through holes randomly selected.

The number of through holes is preferably 1 to 20 and more preferably 3 to 15 per 1 cm ^{2 of the} porous stretchable film. When the number of through holes is at least the lower limit value of the above range, the air permeability of the porous stretchable film will be further improved. When the number of through holes is not more than the upper limit value of the above range, the stretchability of the porous stretchable film is unlikely to decrease.

(Thickness of porous stretchable film)
The thickness of the porous stretchable film is preferably 6 to 70 μm, more preferably 10 to 60 μm, and further preferably 20 to 55 μm. When the thickness of the porous stretchable film is at least the lower limit value of the above range, the stretchability of the porous stretchable film will be sufficiently high. When the thickness of the porous stretchable film is not more than the upper limit of the above range, the stretchability of the porous stretchable film does not become excessive.

(Action effect)
In the porous stretchable film of the present invention described above, the occurrence of blocking is suppressed because the surface layer is provided on either or both of the first surface and the second surface of the elastomer layer.
Further, in the porous stretchable film of the present invention described above, a plurality of through holes are formed, so that the air permeability is good.
Further, in the porous stretchable film of the present invention described above, a strip-shaped first region extending along the surface direction of the porous stretchable film, adjacent to the first region, and extending more than the first region. Since it has alternating strip-shaped second regions that extend along the plane direction of the porous stretchable film, it is difficult to break when stretched, and the stretchability does not easily deteriorate. That is, as shown in FIG. 3, when the porous stretchable film 10 is stretched in the TD, the first region 11 that is easier to stretch than the second region 12 preferentially stretches. Since the first region 11 expands with low stress, and the second region 12 has high rigidity and is difficult to expand, breakage caused by the through hole 13 is unlikely to occur. Therefore, the stretchability of the porous stretchable film 10 is less likely to decrease. On the other hand, the stretchability is uniform over the entire surface, and the stretchability is somewhat insufficient because it has a non-stretchable surface layer. When a through hole was formed in a conventional stretchable film, the stretchable film was stretched. At this time, stress is concentrated in the through holes due to insufficient elongation of the film, and the film is easily broken from the through holes.

(Other embodiments)
The porous stretchable film of the present invention has an elastomer layer and a surface layer provided on either one or both of the first surface and the second surface of the elastomer layer, and has a plurality of through holes and is the same. It suffices as long as it alternately has band-shaped first regions and band-shaped second regions that are harder to stretch than the first regions, and is not limited to the porous stretchable film 10 of the illustrated example.
For example, the surface layer may be provided on only one of the first surface and the second surface of the elastomer layer.
The through hole may be formed only in the first region or only in the second region, or may be formed in both the first region and the second region.
The arrangement of the through holes is not limited to the staggered arrangement, and may be a lattice arrangement or a random arrangement.

<Method for producing porous stretchable film>
The method for producing a porous stretchable film of the present invention is a method having the following step (c) and step (d). The method for producing a porous stretchable film of the present invention may have the following step (a) and step (b), if necessary.

Step (a): A step of preparing an elastomer layer forming material and a surface layer forming material.
Step (b): a step of producing a non-porous stretchable film having an elastomer layer and a surface layer provided on one or both of the first surface and the second surface of the elastomer layer.
Step (c): A step of forming a plurality of depressions scattered on the non-porous stretchable film by embossing the non-porous stretchable film.
Step (d): a step of obtaining the porous stretchable film of the present invention by subjecting the embossed non-porous stretchable film to gear stretching described later.

(Step (a))
When the material for forming the elastomer layer is composed of only the thermoplastic elastomer, the thermoplastic elastomer is used as the material for forming the elastomer layer.
When the elastomer layer forming material contains a thermoplastic elastomer and other components, the respective components are mixed to prepare the elastomer layer forming material. Other components may be masterbatched and added to the material for forming an elastomer layer.

When the surface layer forming material is composed of only the thermoplastic resin, the thermoplastic resin is used as the surface layer forming material.
When the surface layer forming material contains a thermoplastic resin, an inorganic filler and, if necessary, other components, the respective components are mixed to prepare the surface layer forming material. The inorganic filler and other components may be masterbatched and added to the surface layer forming material. When the masterbatch contains a thermoplastic resin, the masterbatch may be used as the surface layer forming material.

Examples of the method for mixing the respective components include a method using various mixers such as a Henschel mixer, a tumbler mixer, a Banbury mixer, and a kneader.
The order of mixing the components is not particularly limited. For example, all components may be mixed at once.
The first surface layer forming material and the second surface layer forming material may be the same material or different materials.

(Step (b))
The elastomer layer-forming material and the surface layer-forming material are molded by a known molding method to form an elastomer layer and a surface layer provided on one or both of the first surface and the second surface of the elastomer layer. A non-porous stretchable film having
Examples of the molding method include a cast film process method and an inflation method, and the cast film process method is preferable from the viewpoint of productivity.

FIG. 4 is a cross-sectional view showing an example of the non-porous stretchable film.
The non-porous stretchable film 10 ′ includes an elastomer layer 14, a first surface layer 15 provided on the first surface of the elastomer layer 14, and a second surface layer provided on the second surface of the elastomer layer 14. 16 and.

The following permanent set of the non-porous stretchable film is preferably 15% or more, more preferably 20% or more.
Permanent set of non-porous stretchable film:
A strip test piece of 50 mm in the machine direction (MD) and 200 mm in the width direction (TD) is cut out from the non-porous stretchable film. The test piece is fixed to the grip of the test apparatus so that the distance between the grips is 100 mm. The test piece is stretched in TD at a speed of 100 mm / min so that the elongation calculated by the following formula (I) is 80%, and then the test piece is immediately contracted at the same speed. Permanent strain (%) is calculated from the following formula (II).
Elongation = (L1-L0) / L0 × 100 (I)
Permanent strain = (L2-L0) / (L1-L0) × 100 (II)
However, L0 is the distance between grips (mm) before extension, L1 is the distance between grips (mm) after extension, and L2 is the load (N / It is the distance (mm) between the grips when 50 mm) becomes zero.

  If the permanent strain of the non-porous stretchable film is not less than the lower limit value of the above range, the shrinkage force of the porous stretchable film is too large (the permanent strain is too small after the through holes are formed by the gear stretching in the step (d). Therefore, the through-hole is not blocked by the shrinkage of the porous stretchable film, and sufficient air permeability can be ensured.

(Process (c))
By embossing the non-porous stretchable film, a plurality of recesses scattered in the non-porous stretchable film are formed. The recessed portion is a portion that becomes a through hole when the gear is stretched in the step (d).

Examples of the embossing method include a roll pressing method, a differential pressure method, and a high pressure jet method.
The roll pressing method is a method in which a pin embossing roll having a large number of projecting pins provided on the circumferential surface and an anvil roll corresponding thereto are arranged so as to face each other, and a non-porous stretchable film is passed between these rolls.
The differential pressure method is such that the non-porous stretchable film is softened near the softening temperature and is positioned on the upper surface of the support having a large number of apertures, and is sucked from below the support or pneumatically applied from the upper surface of the support. It is a method of applying pressure.
The high-pressure jet method is a method of deforming a non-porous stretchable film by a high-pressure jet of liquid ejected from a large number of high-pressure liquid jet nozzles.

The recess has a depth that does not penetrate the non-porous stretchable film. When a large number of pierced hollow portions are generated, the non-porous stretchable film may be broken during the treatment due to the gear stretching in step (d).
The depth of the recessed portion can be adjusted, for example, by the height of the protruding pin provided on the pin embossing roll.
The shape, the number, the arrangement, etc. of the protruding pins of the pin embossing roll may be appropriately determined according to the shape, the number, the arrangement, etc. of the through holes of the porous stretchable film.

(Process (d))
By stretching the embossed non-porous stretchable film with a gear, the non-porous stretchable film is stretched in a stripe shape to obtain a porous stretchable film of the present invention having alternating first regions and second regions.
The gear stretching is specifically performed as follows.

  A first shaping roll having a plurality of ridges extending in the circumferential direction or the axial direction, and a second shaping roll having a plurality of ridges extending in the same direction as the ridges of the first shaping roll. The ridges on one of the shaping rolls and the grooves between the ridges on the other shaping roll are arranged so as to face each other.

FIG. 5 is an enlarged view showing an example of a pair of shaping rolls.
The first shaping roll 20 having a plurality of circumferentially extending projections 24 on the circumferential surface of the cylindrical roll body 22 and the plurality of circumferentially extending projections 34 on the circumferential surface of the cylindrical roll body 32 are provided. The second shaping roll 30 has the first shaping roll 30 such that the ridges 24 of the first shaping roll 20 and the grooves 36 between the ridges 34 of the second shaping roll 30 mesh with each other. The grooves 26 between the ridges 24 of the shaping roll 20 and the ridges 34 of the second shaping roll 30 are arranged to face each other with a predetermined clearance so as to mesh with each other.

FIG. 6 is an enlarged view showing another example of the pair of shaping rolls.
The first shaping roll 40 having a plurality of projections 44 extending in the axial direction on the circumferential surface of the cylindrical roll body 42, and the plurality of projections 54 extending in the axial direction on the circumferential surface of the cylindrical roll body 52. The second shaping roll 50 has the first shaping roll 40 such that the ridges 44 of the first shaping roll 40 and the grooves 56 between the ridges 54 of the second shaping roll 50 mesh with each other. The grooves 46 between the ridges 44 of the shaping roll 40 and the ridges 54 of the second shaping roll 50 are opposed to each other with a predetermined clearance so as to mesh with each other.

  By rotating the first shaping roll and the second shaping roll while passing the embossed non-porous stretchable film between the first shaping roll and the second shaping roll, Forming a stretched first region and a non-stretched second region between the ridges of the first shaping roll and the ridges of the second shaping roll, and at the same time forming a recess in the non-porous stretchable film. The part is stretched to form a through hole.

According to the pair of shaping rolls of FIG. 5, the non-porous stretchable film passing between them is pushed downward by the ridges 24 of the first shaping roll 20 and the ridges of the second shaping roll 30. Pushed upward by 34. Therefore, the non-porous stretchable film is partially stretched vertically and obliquely by the ridges 24 of the first shaping roll 20 and the ridges 34 of the second shaping roll 30 which are adjacent to each other, and Become. At this time, if a recessed portion exists in the stretched portion of the non-porous stretchable film, the recessed portion has a small thickness and is cleaved by stretching to form a through hole. On the other hand, in the non-porous stretchable film, the portion in contact with the top of the ridge 24 of the first shaping roll 20 or the top of the ridge 34 of the second shaping roll 30 is the second region because it is not stretched. .
Since the direction in which the non-porous elastic film is partially stretched by the pair of shaping rolls in FIG. 5 is TD, the gear stretching by the pair of shaping rolls in FIG. 5 is also called TD gear stretching. According to the TD gear stretching, as shown in FIGS. 1 and 2, the strip-shaped first regions 11 extending in the MD and the strip-shaped second regions 12 extending in the MD are alternately formed in the TD.

According to the pair of shaping rolls of FIG. 6, the non-porous stretchable film passing between them is pushed downward by the ridges 44 of the first shaping roll 40 and the ridges of the second shaping roll 50. Pushed upward by 54. Therefore, the non-porous stretchable film is partially stretched in the up and down diagonal direction by the ridges 44 of the first shaping roll 40 and the ridges 54 of the second shaping roll 50 which are adjacent to each other, and the non-porous stretchable film and the first region are formed. Become. At this time, if a recessed portion exists in the stretched portion of the non-porous stretchable film, the recessed portion has a small thickness and is cleaved by stretching to form a through hole. On the other hand, in the non-porous stretchable film, the portion in contact with the top of the ridge 44 of the first shaping roll 40 or the top of the ridge 54 of the second shaping roll 50 is not stretched, and thus becomes the second region. .
Since the direction in which the non-porous stretchable film is partially stretched by the pair of shaping rolls in FIG. 6 is MD, the gear stretching by the pair of shaping rolls in FIG. 6 is also called MD gear stretching. According to the MD gear stretching, band-shaped first regions extending in TD and band-shaped second regions extending in TD are alternately formed in MD.

  When stretching a normal film as a whole, stretching beyond the elastic limit of the film causes irreversible changes in the film. In many cases, the irreversible change of the film is accompanied by a change in color tone (whitening) and a change in dimension (increase or decrease in length or width). This dimensional change is called permanent set. A film in which a permanent strain is generated by stretching which exceeds the elastic limit exhibits elastic behavior within the range of (stretch ratio-permanent strain). For example, when a film having a length of 100 mm is stretched to 200 mm (stretching ratio: 2 times) and a permanent strain of 30% is generated, the length of the stretched film is 130 mm, and 100% -30% = 70%. That is, it has elastic behavior within the range of 130 mm to 200 mm. Here, the elastic behavior refers to the property of returning to the original dimension when the force is removed even if the dimension changes due to the application of force. Since the length of the stretched film has changed from 100 mm before stretching to 130 mm, the stretched film exhibits elastic behavior within the range of 100% to 154% (130 mm / 130 mm to 200 mm / 130 mm) (elasticity). Have).

In gear stretching, the non-porous stretchable film is partially stretched beyond its elastic limit. The non-porous stretchable film stretched partially beyond its elastic limit by gear stretching causes a change in color tone. That is, the first region of the white portion in FIGS. 1 and 2 is a region that has been stretched beyond the elastic limit and generated permanent strain, resulting in elasticity in a certain range. This change in color tone indicates that the structure of the non-porous stretchable film undergoes an irreversible change. For example, when the non-porous stretchable film has a surface layer containing a non-elastomer thermoplastic resin (polyethylene, polypropylene, etc.), the surface layer is stretched and broken by stretching beyond the elastic limit. Voids such as cracks and fine holes are generated inside the stretched and destroyed surface layer. These voids cause diffuse reflection of light that has entered the surface layer, and appear white in appearance. Further, the destroyed surface layer loses its original mechanical strength. Along with this, the first region is released from the constraint of the surface layer, and its original elasticity (stretchability due to the elastomer layer) comes to be expressed.
The color tone does not change in the portion that is not stretched by the gear stretching, that is, the second region.

In the gear stretching, the width W of the top of the ridge of the shaping roll, the height H of the ridge, the interval P between the tops of the adjacent ridges, the ridge of the first shaping roll and the second shaping The draw ratio can be adjusted by adjusting the engagement depth D of the roll with the ridge.
The stretching ratio in gear stretching can be easily calculated from the stretching principle by the Pythagorean theorem. For example, the distance between the tops of the ridges of the adjacent first shaping rolls and the tops of the ridges of the second shaping rolls (width of the stretched portion of the non-porous stretchable film) is 1 mm, and the engagement depth is When it was √3 mm, the width of the stretched portion of the non-porous stretchable film was 2 mm, and the stretch ratio was 2 times. Here, when the permanent set is 30%, the width of the stretched portion changes from 1 mm before stretching to 1.3 mm.

The width of the first region and the width and length of the second region are not particularly limited and may be appropriately determined according to the purpose of use of the porous stretchable film and the like.
The area of the opening of the through hole can be appropriately adjusted depending on the size and shape of the protruding pin of the pin embossing roll and the stretching ratio.

(Action effect)
In the method for producing a porous stretchable film of the present invention described above, the non-porous stretchable film having the surface layer provided on either one or both of the first surface and the second surface of the elastomer layer is embossed. By processing, a plurality of depressions are formed in the non-porous stretchable film, and the embossed non-porous stretchable film is subjected to the above-mentioned gear stretching. Therefore, the width of the first region and the second region It is possible to manufacture a porous stretchable film having the above and having through holes. That is, it is possible to produce a porous stretchable film in which the occurrence of blocking is suppressed, the breathability is good, and the stretchable stretch film is unlikely to be broken when stretched and the stretchability is not easily lowered.

(Other embodiments)
The porous stretchable film of the present invention may be manufactured by a manufacturing method other than the method of combining embossing and gear stretching.
For example, a non-porous stretchable film that has not been embossed is gear-stretched to form a first region and a second region, and then a through hole is formed by a known opening means (slitting, hot pin melt, etc.). Good.

<Composite sheet>
The composite sheet of the present invention has a layer made of the porous stretchable film of the present invention and a layer made of a nonwoven fabric.

(Nonwoven fabric)
Examples of the non-woven fabric include spun bond non-woven fabric, melt blown non-woven fabric, flash spun non-woven fabric, chemical bond non-woven fabric, thermal bond non-woven fabric, wet non-woven fabric and dry non-woven fabric.
Examples of the fibers of the non-woven fabric include synthetic fibers (polypropylene fibers, polyamide fibers, polyester fibers, etc.), natural fibers (cotton, silk), semi-synthetic fibers (rayon fibers, acetate fibers, etc.) and the like.
The non-woven fabric may be subjected to a stretch imparting process (softening process, pleating process, shrinking process, filling process, etc.).

(Method for manufacturing composite sheet)
The composite sheet is produced, for example, by joining the porous stretchable film of the present invention and a nonwoven fabric and laminating them.
Examples of the joining method include a hot pressing method, a hot embossing bonding method, a bonding method using a hot melt adhesive, an ultrasonic bonding method, and a high frequency bonding method.

(Action effect)
In the composite sheet of the present invention described above, since it has a layer made of the porous stretchable film of the present invention, the occurrence of blocking due to the layer made of the porous stretchable film is suppressed, breathability is good, and when stretched. The layer made of the porous stretchable film is less likely to break and the stretchability is less likely to decrease.

(Other embodiments)
The composite sheet of the present invention may be one having a layer made of the porous stretchable film of the present invention and a layer made of a non-woven fabric, and may be made of only a layer made of the porous stretchable film of the present invention and a layer made of a non-woven fabric. There is no limitation.
For example, as long as the effect of the composite sheet of the present invention is not impaired, it may have a layer other than the layer made of the porous stretchable film of the present invention and the layer made of the nonwoven fabric.

  Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following description.

<Measurement method, evaluation method>
(Thickness of each layer)
The thickness of the elastomer layer and the surface layer of the non-porous stretchable film was determined by observing the cross section with a microscope.

(Permanent strain of stretch film)
A strip-shaped test piece of 50 mm in the machine direction (MD) and 200 mm in the width direction (TD) was cut from the elastic film. The test piece was fixed to a grip of a precision universal tester (manufactured by Shimadzu Corporation, Autograph, material test operation software: TRAPEZIUM2) so that the distance between the grips was 100 mm. The test piece was stretched in TD at a speed of 100 mm / min so that the elongation calculated by the following formula (I) was 80%, and then the test piece was immediately shrunk at the same speed. The permanent strain (%) at the first cycle was calculated from the following formula (II). The same operation was repeated once again using the test piece used in the first cycle to calculate the permanent set (%) in the second cycle. The test was performed at 23 ° C ± 2 ° C.
Elongation = (L1-L0) / L0 × 100 (I)
Permanent strain = (L2-L0) / (L1-L0) × 100 (II)
However, L0 is the distance between grips (mm) before extension, L1 is the distance between grips (mm) after extension, and L2 is the load (N / It is the distance (mm) between the grips when 50 mm) becomes zero.

(Breathability of stretch film)
Regarding the stretchable film, in accordance with JIS P 8117: 2009 (ISO 5636-5: 2003), a Gurley type densometer (manufactured by Toyo Seiki Seisakusho Ltd., G-B3C type) was used to measure the time taken for 100 mL of air to pass through, The air resistance (second / 100 mL) was used. The air permeability resistance is an index of air permeability. The lower the air resistance, the better the air permeability. The lower detection limit is 1.4 seconds / 100 mL.

(Average expansion ratio of the first area and the second area)
A strip-shaped test piece of 50 mm in the machine direction (MD) and 100 mm in the width direction (TD) was cut from the stretch film. The test piece was fixed to a grip of a precision universal tester (manufactured by Shimadzu Corporation, Autograph, material test operation software: TRAPEZIUM2) so that the distance between the grips was 30 mm. The test piece was stretched in TD at a speed of 100 mm / min so that the elongation calculated by the following formula (I) was 80%. The extension ratio (fold) was calculated from the following formula (III). The extension ratios of 12 randomly selected regions in both the first region and the second region were calculated, and the average value was obtained. The test was performed at 23 ° C ± 2 ° C.
Elongation = (L1-L0) / L0 × 100 (I)
Expansion ratio = R1 / R0 (III)
However, L0 is the distance between grips (mm) before extending, L1 is the distance between grips (mm) after extending, and R0 is the first region or the second before extending. Is a length (μm) in the direction orthogonal to the longitudinal direction of the region (1), and R1 is a length (μm) in the direction orthogonal to the longitudinal direction of the expanded first region or the second region ( However, R0 and R1 are measured at the same location in the same region).

<Raw material>
(Thermoplastic elastomer)
Vistamaxx (registered trademark) 6102 (manufactured by ExxonMobil, propylene-ethylene copolymer, glass transition temperature: -32 ° C, ethylene unit content: 16% by mass).
(Thermoplastic resin)
Sumikasen (registered trademark) CE3506 (polyethylene manufactured by Sumitomo Chemical Co., Ltd.).
(Master Badge)
TEP 1HC783 WHT (manufactured by HANIL TOYO, calcium carbonate (average particle diameter: 5 μm, content rate: 50 mass%), base resin: polyethylene).

(Material for forming elastomer layer)
As the elastomer layer forming material (A-1), a thermoplastic elastomer was used as it was.
(Material for forming surface layer)
As the surface layer-forming material (B-1), a mixture of 85% by mass of polyethylene and 15% by mass of calcium carbonate, which was obtained by mixing a thermoplastic resin and a masterbatch with a tumbler mixer, was used.
The masterbatch was used as it was as the surface layer forming material (B-2).

<Production of non-porous stretchable film>
(Production Example 1)
Using an extruder equipped with a T-die (manufactured by Sumitomo Heavy Industries Modern Co., Ltd.), the elastomer layer forming material (A-1) and the surface layer forming material (B-1) are extrusion-molded at 200 ° C. and cast film process. Non-porous stretchable film having an elastomer layer, a first surface layer provided on the first surface of the elastomer layer, and a second surface layer provided on the second surface of the elastomer layer (F) -1) was obtained. The thickness of each layer is shown in Tables 1 and 2.

(Production Example 2)
The elastomer layer and the first surface of the elastomer layer were provided in the same manner as in Production Example 1 except that the surface layer forming material (B-1) was changed to the surface layer forming material (B-2). A non-porous stretchable film (F-2) having a first surface layer and a second surface layer provided on the second surface of the elastomer layer was obtained. The thickness of each layer is shown in Tables 3 and 4.

<Production of porous stretchable film or stretchable film>
(Example 1)
The non-porous stretchable film (F-1) was embossed by a roll pressing method.
The shape of the protruding pins provided on the pin embossing roll was a cylinder (diameter: 0.5 mm, height: 0.8 mm), and the protruding pins were arranged in a staggered arrangement with an interval of 3 mm.

The embossed non-porous stretchable film was TD gear stretched using a pair of shaping rolls as shown in FIG. 5 to obtain a porous stretchable film. The porous stretchable film was evaluated. The results are shown in Table 1.
In the TD gear stretching, the width of the top of the ridge of the first shaping roll is 0.5 mm, and the width of the top of the ridge of the second shaping roll is 0.5 mm. The distance between the tops of the ridges is 2.5 mm, the distance between the tops of the ridges of the first shaping roll is 2.5 mm, and the ridges of the first shaping roll and the second shaping roll are The depth of engagement with the ridges was set to 2.9 mm (210%).

(Comparative Example 1)
A stretch film was obtained in the same manner as in Example 1 except that TD gear stretching was performed without embossing. The stretchable film was evaluated. The results are shown in Table 1.

(Comparative example 2)
An elastic film was obtained in the same manner as in Example 1 except that embossing was performed and TD gear stretching was not performed. The stretchable film was evaluated. The results are shown in Table 1.

(Comparative Example 3)
The non-porous stretchable film (F-1) was evaluated. Table 2 shows the results.

(Comparative example 4)
Slits were formed in the non-porous stretchable film (F-1) by slitting to obtain a porous stretchable film. The porous stretchable film was evaluated. Table 2 shows the results.

(Comparative example 5)
Through holes were formed in the non-porous stretchable film (F-1) by hot pin melt to obtain a porous stretchable film. The porous stretchable film was evaluated. Table 2 shows the results.

(Example 2)
A porous stretchable film was obtained in the same manner as in Example 1 except that the non-porous stretchable film (F-2) was used. The porous stretchable film was evaluated. The results are shown in Table 3.
However, in the TD gear stretching, the engagement depth between the ridges of the first shaping roll and the ridges of the second shaping roll was set to 3.2 mm (240%).

(Comparative example 6)
A stretchable film was obtained in the same manner as in Example 2 except that TD gear stretching was performed without embossing. The stretchable film was evaluated. The results are shown in Table 3.

(Comparative Example 7)
An elastic film was obtained in the same manner as in Example 2 except that embossing was performed and TD gear stretching was not performed. The stretchable film was evaluated. The results are shown in Table 3.

(Comparative Example 8)
The non-porous stretchable film (F-2) was evaluated. The results are shown in Table 4.

(Comparative Example 9)
Slits were formed in the non-porous stretchable film (F-2) by slitting to obtain a porous stretchable film. The porous stretchable film was evaluated. The results are shown in Table 4.

(Comparative Example 10)
Through holes were formed in the non-porous stretchable film (F-2) by hot pin melt to obtain a porous stretchable film. The porous stretchable film was evaluated. The results are shown in Table 4.

From the results of Examples 1 and 2, it can be seen that the non-porous stretchable film is embossed and gear-stretched to form the first region and the second region, and at the same time, the through holes are formed. The porous stretchable film having the first region and the second region and having the through holes formed therein has a small permanent strain (good stretchability) and high air permeability.
From the results of Comparative Examples 1 and 6, it can be seen that the first region and the second region are formed by the gear stretching of the non-porous stretchable film without embossing, but the through holes are not formed.
From the results of Comparative Examples 2 and 7, it can be seen that the first and second regions and the through holes are not formed only by embossing the non-porous stretchable film. Moreover, it is understood that the permanent strain is relatively large and the elasticity is insufficient.
From the results of Comparative Examples 3 and 8, it can be seen that the non-porous stretchable film itself has relatively large permanent strain (insufficient stretchability) and does not have air permeability.
From the results of Comparative Examples 4, 5, 9, and 10, when the slits or through holes were formed only by slitting or hot melt in the non-porous stretchable film, stress was concentrated in the slits or through holes when the stretchable film was stretched. It turns out that it breaks.

  The porous stretchable film and the composite sheet of the present invention are suitably used in the hygiene field and the medical field. For example, it is used for elastic paper diaper tabs, side panels for training pants, leg gathers, sanitary items, swimming pants, incontinence items, veterinary items, bandages, surgical clothes, surgical drapes, sterile covers, wipes, and the like.

10 Porous stretch film,
10 'non-porous stretch film,
11 First area,
12 Second area,
13 through holes,
14 elastomer layer,
15 first surface layer,
16 second surface layer,
20 first shaping roll,
22 roll body,
24 ridges,
26 grooves,
30 second shaping roll,
32 roll body,
34 ridge,
36 grooves,
40 first shaping roll,
42 roll body,
44 ridge,
46 grooves,
50 Second shaping roll,
52 roll body,
54 ridge,
56 groove.

Claims (7)

A film-like elastomer layer comprising a thermoplastic elastomer, elastomer layer provided on both the first and second surfaces of, and a surface layer comprising a thermoplastic resin (. Excluding the thermoplastic elastomer) Having a porous stretchable film having a plurality of through holes,
The porous stretchable film extends along the surface direction of the porous stretchable film, is a strip-shaped first region in which the surface layer is broken, and is adjacent to the first region, and extends more than the first region. A porous stretchable film having alternating strip-shaped second regions extending along the surface direction of the porous stretchable film, which is difficult to do. The porous stretchable film according to claim 1, wherein an average value of the opening areas of the through holes is 0.1 to 1.5 mm ² . The porous stretchable film according to claim 1 or 2, wherein the number of the through holes is 1 to 20 per 1 cm ² of the porous stretchable film.   The porous stretchable film according to claim 1, wherein the surface layer further contains an inorganic filler. A method for producing the porous stretchable film according to any one of claims 1 to 4,
An elastomer layer containing a thermoplastic elastomer, and a surface layer containing a thermoplastic resin (excluding the thermoplastic elastomer) provided on one or both of the first surface and the second surface of the elastomer layer. By embossing the non-porous stretchable film having, a step of forming a plurality of depressions scattered in the non-porous stretchable film,
A first shaping roll having a plurality of ridges extending in the circumferential direction or the axial direction, and a second shaping roll having a plurality of ridges extending in the same direction as the ridges of the first shaping roll. , The first shaping roll and the second shaping roll, while the ridges of one of the shaping rolls and the grooves between the ridges of the other shaping roll are arranged to face each other so as to mesh with each other and are rotated. The first stretched roll between the ridges of the first shaping roll and the ridges of the second shaping roll by passing the embossed non-porous stretchable film between Forming a region and the second region that has not been stretched, and at the same time, stretching the recess to form the through hole. The method for producing a porous stretchable film according to claim 5, wherein the following permanent set of the non-porous stretchable film is 15% or more.
(Permanent strain of non-porous stretchable film)
A strip test piece of 50 mm in the machine direction (MD) and 200 mm in the width direction (TD) is cut out from the non-porous stretchable film. The test piece is fixed to the grip of the test apparatus so that the distance between the grips is 100 mm. The test piece is stretched in TD at a speed of 100 mm / min so that the elongation calculated by the following formula (I) is 80%, and then the test piece is immediately contracted at the same speed. Permanent strain (%) is calculated from the following formula (II).
Elongation = (L1-L0) / L0 × 100 (I)
Permanent strain = (L2-L0) / (L1-L0) × 100 (II)
However, L0 is the distance between grips (mm) before expansion, L1 is the distance between grips (mm) after expansion, and L2 is the load (N / It is the distance (mm) between the grips when 50 mm) becomes zero.   A composite sheet comprising a layer made of the porous stretchable film according to claim 1 and a layer made of a nonwoven fabric.