JPH1016115A - Water vapor permeable sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water vapor permeable sheet, which is excellent in water vapor permeation, water resistance and further has a high ply separation strength by the method wherein an air permeable film and a nonwoven fabric made of resin-containing fiber are laminated to each other and heat-fused through the embossing having a cornerless embossing pattern, which has the specified embossing specific area. SOLUTION: This water vapor permeable sheet suitable for the back sheet of an absorbable commodity such as a paper diaper is produced by laminating an air permeable film and a nonwoven fabric made of fibers containing resin, the melting point of which is the same as or lower than that of the resin, of which the air permeable film is made, and heat-fusing them through the embossing having a cornerless embossing pattern, which has the embossing specific area of 5-20%. This air permeable film has water vapor permeation to permeate water vapor and, at the same time, fine bores each of which is too small to permeable liquid such as the water or the like and water resistance. As the stock of the air permeable film, polyolefin resin or a resin composition mainly made of polyolefin resin is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture-permeable sheet, and more particularly, to a moisture-permeable sheet having excellent flexibility, hand and water resistance and having high delamination strength.

[0002]

2. Description of the Related Art Generally, an absorbent article such as a disposable diaper wraps an absorbent for absorbing and retaining body fluid with a facing material disposed inside the absorbent article and a back sheet disposed outside the absorbent article. It has a structure that includes it. The facing material disposed on the inside is required to have a function of contacting the skin, allowing the discharged body fluid to permeate and being absorbed by the internal absorbent, and preventing the body fluid from returning from the absorbent. On the other hand, the back sheet is required to have a function of preventing the body fluid absorbed by the internal absorbent from leaking to the outside and preventing the liquid from permeating the inside from the outside. Further, in order to prevent stuffiness due to moisture generated inside during use of the absorbent article, the absorbent article is required to have appropriate moisture permeability in order to allow moisture inside the absorbent article to permeate and escape to the outside. Further, since this back sheet constitutes the outer surface of the absorbent article, it is required that the back sheet has an excellent texture and a good tactile sensation.

Conventionally, in order to obtain a good touch, a nonwoven fabric is used as an outer surface, a porous polyethylene film is used as an inner layer in contact with an absorbent, and a nonwoven fabric and a porous polyethylene film are used as the backsheet. A multi-layer sheet obtained by adhering with a hot melt adhesive is known.

[0004]

However, the conventional multi-layer sheet impairs the flexibility and texture of the nonwoven fabric,
It was inferior in flexibility, so-called stiff and hard feeling, or caused paper noise, and the touch feeling was still insufficient.

[0005] In order to improve this hard feel and obtain a multilayer sheet having an excellent feel, it is conceivable to make a film or a nonwoven fabric thinner. However, since there is a limit to thinning the film, the nonwoven fabric must be thinned. When a thin non-woven fabric is used, when the film and the non-woven fabric are bonded together using a hot melt adhesive, a phenomenon in which the hot melt adhesive permeates the non-woven fabric and oozes outward, a so-called adhesive seepage occurs. However, there is a problem that the tactile sensation of the outer surface is impaired.

Accordingly, an object of the present invention is to provide a moisture-permeable sheet having excellent flexibility and surface feel, excellent moisture permeability and water resistance, and high delamination strength without impairing the flexibility and texture of the nonwoven fabric. Is to do.

[0007]

In order to solve the above-mentioned problems, the present invention comprises a breathable film and a resin having a melting point which is the same as or lower than the melting point of the resin constituting the breathable film. Laminated with a non-woven fabric made of fiber,
An object of the present invention is to provide a moisture-permeable sheet which is heat-sealed by embossing an emboss pattern having an emboss area ratio of 5 to 20% and no corners.

Hereinafter, the moisture-permeable sheet of the present invention (hereinafter, referred to as “sheet of the present invention”) will be described in detail.

[0009] The sheet of the present invention is a sheet having a multilayer structure in which a breathable film and a nonwoven fabric are laminated.

The breathable film of the sheet of the present invention is a water-permeable film that has moisture permeability that allows water vapor to pass therethrough, has pores small enough not to allow the passage of liquid such as water, and has water resistance. This breathable film has a moisture permeability of 100.
0 g / m ² · 24 hr or more, preferably 2000 to 60
It is a film having a moisture permeability of 00 g / m ² · 24 hr. Here, in the present invention, the moisture permeability is defined as JIS P
It refers to a measured value determined in a moisture permeability test according to 0208.

As a material of the breathable film, a polyolefin resin or a resin composition containing a polyolefin resin as a main component is used. Examples of the polyolefin resin include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene / α-olefin copolymer, polypropylene, propylene / α-olefin copolymer, and one or more or two or more of these. Those composed of the above mixtures and the like can be mentioned. In the present invention, the breathable film may be composed of one kind of material, or may be composed of a mixture of two or more kinds.

In the present invention, the ethylene / α-olefin copolymer used as the polyolefin resin is a copolymer of ethylene and an α-olefin having 4 to 12 carbon atoms, and a propylene / α-olefin The copolymer is a copolymer composed of propylene and α-olefin. Examples of the α-olefin having 4 to 12 carbon atoms used for copolymerization with ethylene or propylene include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and 1-octene. -Decene, 1-dodecene and the like. Ethylene / α-olefin copolymers are those α-olefins having 4 to 12 carbon atoms.
-The olefin may contain one kind alone or two or more kinds in combination. Among these α-olefins,
Α-olefins having 4 to 6 carbon atoms are preferred.

In the ethylene / α-olefin copolymer, a repeating structural unit derived from ethylene (hereinafter, referred to as “the repeating unit”)
"Ethylene unit") and an α-
Recurring structural units derived from olefins (hereinafter referred to as “α-
Olefin unit) is 50% by weight of ethylene unit
Α-olefin unit 5
0% by weight or less, preferably 55 to 9 ethylene units
1 to 45% by weight of α-olefin unit based on 9% by weight
More preferably, the proportion of α-olefin units is 2 to 35% by weight based on 65 to 98% by weight of ethylene units, particularly preferably 70 to 96% by weight of ethylene units and 4 to 30% of α-olefin units. It is desirable to include it in a proportion of% by weight.

The polyolefin resin may contain, as a component other than the above-mentioned main components, for example, a thermoplastic resin such as an ethylene polymer or a propylene polymer.

Further, in the present invention, the polyolefin resin can be stably formed into a film having excellent mechanical strength such as tear strength by a casting method. Melt flow rate (MFR) is 1 to 25 g in that it can be made microporous by workability and can be excellent in air permeability.
/ 10 min, and more preferably in the range of 2 to 15 g / 10 min. In the present invention, the melt flow rate (M
FR) is measured in accordance with ASTM D 1238-65T.

Further, the polyolefin resin has an Olsen stiffness in an appropriate range, and a stiff film can be obtained, and a film which does not stick to the skin, has no stickiness, and has excellent mechanical strength can be obtained. , Density 0.88 ~
0.93 g / cm ³ , preferably 0.90 to 0.92 g
/ Cm ³ is desirable.

Furthermore, additives such as conventionally known slip agents, hydrophilic agents, inorganic fillers, and heat stabilizers are added to the polyolefin resin by a method such as kneading.
It can be blended within a range that does not impair the purpose of the present invention.

Further, a resin composition containing a polyolefin resin as a main component used as a material of a breathable film includes:
It contains a filler (B) in addition to the polyolefin resin (A). The filler is not particularly limited, and may be either an inorganic filler or an organic filler, or a combination of both. Specific examples of the filler include inorganic fillers such as alkaline earth metals, and
Group III element oxides, hydroxides, carbonates, sulfates, silicates and the like.Examples of the organic filler include wood powder, cellulose powder such as pulp, and crosslinked products such as silicone and phenol. And the like. These may be used alone or in combination of two or more. Among these, calcium carbonate, barium sulfate and the like are preferable in consideration of cost and stability of quality.

The particle size of the filler is usually 0.1 to 10
It is about μm, preferably about 0.5 to 5 μm.

The content ratio of the polyolefin resin (A) / filler (B) in the resin composition is such that the weight ratio of (A) / (B) is 30/70 to 80/20.

When the resin composition contains an antioxidant, the content is usually 0.1 to 100 parts by weight of the total of the polyolefin resin and the filler in the resin composition.
It is about 1 to 2.0 parts by weight, preferably about 0.5 to 1.8 parts by weight.

Further, in addition to the above-described antioxidant, the resin composition may further contain additives such as an ultraviolet absorber, an antibacterial agent, a fungicide, a rust inhibitor, a lubricant, a pigment, and a heat stabilizer. May be included in a range that does not impair the object of the present invention.

The resin composition has improved moldability,
Alternatively, in order to adjust various physical properties, an olefin-based elastomer such as polyethylene and polystyrene may be contained within a range that does not impair the object of the present invention. When these olefin-based elastomers are contained, the content thereof is usually 20 parts by weight or less based on 100 parts by weight of the ethylene / α-olefin copolymer.

The resin composition is prepared by mixing the polyolefin resin or the polyolefin resin with a filler and various compounding agents, if necessary, in a conventional manner such as a Henschel mixer, a tumbler mixer or a V mixer. Can be performed according to a method of mixing using a mixer.

In the present invention, the polyolefin resin or the resin composition is formed into a film. The film may be formed by a method in which a polyolefin resin or a resin composition is melt-kneaded and formed into a film or a sheet, and may be performed according to any method. For example, a polyolefin resin or a resin composition,
After melt-kneading using a conventional device such as a single-screw or twin-screw extruder or a twin-screw kneader, it can be formed into a film or sheet by inflation molding, extrusion molding using a T-die, or the like. The temperature during melt kneading is
Usually, it is in the range of 200 to 280 ° C.

In the inflation molding, a uniaxially or biaxially stretched film is drawn out of a circular die into a cylindrical shape, and further uniaxially stretched by roll stretching. Further, in the molding using a T-die, after forming an unoriented sheet or film, uniaxial stretching by roll stretching or biaxial stretching by a tenter method can be performed.

Next, the polyolefin resin or resin composition formed into a film or sheet is subjected to a stretching treatment to obtain a breathable film. This stretching treatment may be uniaxial stretching or biaxial stretching, and is appropriately selected. For example, in the case of uniaxial stretching, there is an advantage that the stretching treatment can be easily performed, and when the anisotropy of strength is not a problem, uniaxial stretching is advantageous. Further, in the case of biaxial stretching, it is possible to further reduce the film thickness, which is effective for the purpose of improving the softness due to the reduction in rigidity and eliminating the anisotropy in strength.

In the case of uniaxial stretching, roll stretching is usually used, and the stretching may be performed in one stage or in two or more stages. At this time, the stretching temperature is adjusted to a range from room temperature to the melting point of the resin raw material, and the stretching is performed at a stretching ratio of 1.2 to 8 times, preferably 2 to 6 times, so that the porosity is 50% or more and the rigidity is increased. It is possible to obtain a breathable film that is low and has good texture.

In the case of biaxial stretching, simultaneous or sequential stretching is performed. At this time, the stretching temperature is adjusted in the range of room temperature to the melting point of the resin raw material, the stretching ratio is 1.2 to 8 times, preferably 2 to 6 times, the porosity is 50% or more, the rigidity is low, and the skin feels good. A breathable film can be obtained.

Heat treatment after uniaxial stretching or biaxial stretching is effective because a breathable film having excellent dimensional stability can be obtained. The heat treatment can be performed at a temperature ranging from 80 ° C. to the melting point of the film,
Usually, it is performed at high temperature for a short time.

In the present invention, it is preferable that the permeable film has a porosity of 50% or more in terms of good air permeability and moisture permeability and excellent texture, and furthermore, a porosity of 60 to 80%. Is preferred. The breathable film preferably has a Young's modulus of 60 to 300 MPa, and has a tear strength of 40 in the MD direction (longitudinal direction).
Those having N / cm or more are preferable.

In the sheet of the present invention, the thickness of the breathable film is usually about 10 to 30 μm, preferably 10 to 25 μm. Moreover, the moisture permeability is 2000 to
Those having a weight of 6000 g / m ² · 24 hr are preferred.

In the sheet of the present invention, the nonwoven fabric laminated on the breathable film is made of a resin having a melting point equal to or lower than the melting point of the resin constituting the breathable film (hereinafter referred to as “low melting point resin component”). ). This nonwoven fabric may be formed of only fibers made of a low-melting resin component (hereinafter, referred to as “low-melting fibers”), or may be made of a low-melting fiber and a resin having a higher melting point than the low-melting resin component. Fibers (hereinafter, referred to as “high melting point fibers”) may be mixed.

As the nonwoven fabric having a structure in which the low-melting fiber and the high-melting fiber are mixed, for example, the core portion is made of a resin having a melting point higher than that of the low-melting resin component, the sheath portion is made of the low-melting resin component, and the core portion is made of a resin. A non-woven fabric made of a fiber having a core-sheath structure in which a sheath portion has a cross-sectional shape that concentrically surrounds a core portion in a state of being eccentric or non-eccentric with respect to an axis; And a portion made of a resin having a higher melting point than the low-melting resin component coexist in parallel, and both the portion made of the low-melting resin component and the portion made of a resin having a higher melting point than the low-melting resin component have the outer peripheral surface of the fiber, respectively. Non-woven fabric composed of fibers having a form such as a fiber having a side-by-side structure forming a part of the non-woven fabric; Non-woven fabric having a structure in which a fiber composed of a low-melting resin component is fused to a part of the outer peripheral surface of the high-melting fiber may be mixed, or a non-woven fabric having a structure in which these structures are laminated and mixed. Good. In the core / sheath type fiber, the core / sheath area ratio in the fiber cross section is usually 5/5 to 1 to 9 (sheath portion: low melting point resin component).
It is about. In the fiber of the side-by-side type structure,
The area ratio of (low-melting resin component) / (resin having a higher melting point than low-melting resin component) in the fiber cross section is as follows:
Usually, it is about 5/5.

In the sheet of the present invention, the nonwoven fabric may be a single nonwoven fabric having any of the above structures, or may have a multi-layer structure composed of a plurality of nonwoven fabrics. In particular, a nonwoven fabric having a multilayer structure including a fusible nonwoven layer made of a resin having a melting point lower than the melting point of the resin constituting the permeable film on the side in contact with the permeable film is a nonwoven fabric other than the fusible nonwoven layer. This is effective in that the degree of freedom in selecting a layer, for example, a nonwoven fabric used as a nonwoven fabric layer constituting the sheet surface is increased. When the sheet of the present invention has a nonwoven fabric having a multilayer structure, the basis weight of the nonwoven fabric having the multilayer structure is usually about 15 to 30 g / m ² , and the basis weight of the fusible nonwoven layer is 3 to 10 g / m
^{About 2} .

The low-melting-point resin component constituting the nonwoven fabric is made of a resin having the same or a lower melting point than the resin constituting the breathable film. As the low melting point resin component, for example, polyolefin resin such as polypropylene, polyethylene, propylene / ethylene random copolymer and the like, and one or two kinds of resins having the same or lower melting point as the material resin of the breathable film Combinations of the above can be used.

The propylene / ethylene random copolymer is a random copolymer of propylene and ethylene, and preferably has an ethylene content of 0.5 to 5 mol.
%, Particularly preferably 2.0 to 5 mol%.

In the present invention, as a resin forming the constituent fibers of the non-woven fabric, in particular, the eccentric core-sheath type bicomponent fibers, a propylene / ethylene random copolymer having an MFR of 20 g / 10 minutes and a resin having an MFR of 35 g / 10 minutes The use of a mixed resin raw material composed of a combination of the above with polypropylene makes it possible to obtain a nonwoven fabric made of crimped fibers, which is effective in improving flexibility and tactile sensation. When a combination of a propylene / ethylene random copolymer and polypropylene is used, the proportion used is
The weight ratio of ethylene random copolymer / polypropylene is 1/9 to 9/1, preferably 1/9 to 4/6.

The average fiber diameter of the fibers constituting the nonwoven fabric is usually about 10 to 35 μm, and is preferably 10 to 20 μm in that the feeling of snagging when touched with a fingertip is reduced and a good tactile sensation is obtained. is there.

The basis weight or thickness of this nonwoven fabric is appropriately selected according to the use of the moisture-permeable sheet of the present invention, particularly, the required flexibility and the like, and is not particularly limited. Usually, the basis weight is about 10 to 30 g / m ² , and preferably 10 to 25 g / m ^{2 in} that a thin moisture-permeable sheet can be obtained.
It is. This thickness is usually 0.1 to 0.5 mm
It is about.

The production of this nonwoven fabric can be carried out according to a conventional method, and is not particularly limited. For example, in the case of producing a non-woven fabric composed of only low-melting fibers, a low-melting resin is used in accordance with a method of melting or dissolving a raw resin such as a spun bond method, a melt blown method, or a flash spinning method, followed by fibrillation and molding into a non-woven fabric. The components can be formed into a nonwoven. When producing a core / sheath type nonwoven fabric, it can be produced according to a spunbonding method using a core / sheath type spinning nozzle. Further, when producing a nonwoven fabric having a side-by-side structure, the nonwoven fabric can be produced according to a spunbonding method using a side-by-side spinning nozzle. Furthermore, in the case of manufacturing a nonwoven fabric in which low-melting fibers and high-melting fibers are mixed, one of the low-melting fibers and the high-melting fibers is formed by a spunbond method, a flash spinning method, or a melt-blowing method. When the obtained fiber is dispersed on a web former, the fiber can be mixed with another fiber and deposited to be produced. Further, a multilayer structure having a multilayer structure composed of a plurality of nonwoven fabrics, and including, on the side in contact with the breathable film, a fusible nonwoven fabric layer composed of a resin having a melting point lower than the melting point of the resin constituting the breathable film. Can be manufactured according to a method such as a spun bond method, a flash spinning method, or a melt blow method using an apparatus having two or more rows of spinning nozzles.

In the production of the sheet of the present invention, the air-permeable film having the above-mentioned structure and a nonwoven fabric are laminated, and then heated and pressurized with an embossing roll, so that the air-permeable film and the nonwoven fabric have a low melting point. The method can be performed according to a method in which the resin component is partially melted by an embossing roll, pressed, and bonded by heat fusion. The temperature and pressure of the heating and pressurizing treatment depend on the constituent fibers, structure, basis weight, and thickness of the nonwoven fabric used, and the material, basis weight, and thickness of the permeable film, as well as the desired water resistance and peel strength. Although it is appropriately selected according to the processing speed (laminating speed) and the like, it is usually about 80 to 150 ° C., preferably 100 to
The reaction can be performed at a temperature of about 130 ° C. and a pressure (linear pressure) of about 10 to 50 kg / cm, preferably a pressure of about 20 to 40 kg / cm (linear pressure).

The embossing roll used in the heating and pressurizing treatment has an embossing pattern, that is, the shape of the tip surface of the embossed portion (projection) has no corner. In the present invention, the shape without a corner is a shape composed of a curve such as a circle and an ellipse, or a shape in which a straight line is smoothly connected to a circle and an ellipse, and a corner is formed into an arc shape. And the radius of curvature of the arc is at least 0.15 m
m or more, such as a rectangular shape. In particular, it is preferable to use an embossing roll having an embossing pattern having the shape shown in FIG. 1 in that a moisture-permeable sheet having a texture close to that of quilting can be obtained. The embossed area ratio of the embossed portion in the embossed roll is 5 to 20%, preferably 5 to 15%. In particular, when a sheet with a soft touch is required, it is preferable to use an embossing roll having an embossed shape of a wide lattice pattern having an embossed area ratio of 7 to 15% as shown in FIGS.

The moisture-permeable sheet of the present invention has a water resistance of at least 1000 mmH ₂ O and a moisture permeability of 3000 g / m ² ···
24hr or more, MD direction flexibility (Clark method)
Is 50 mm or less, and the delamination strength is 50 g / 2.
What is 5 mm or more is suitable as a backsheet for a disposable diaper. The backsheet for a disposable diaper made of this moisture-permeable sheet is used such that a moisture-permeable film layer is arranged on the inner side in contact with the absorbent material of the disposable diaper, and a surface layer made of a nonwoven fabric is arranged on the outer side in contact with the outside air. It is. In the present invention, the MD direction refers to the longitudinal direction of the moisture-permeable sheet. Also, the flexibility is based on JIS L109
6 is a numerical value measured by the Clark method described as the C method.

[0045]

EXAMPLES Hereinafter, Examples and Comparative Examples of the present invention will be described.
The present invention will be described more specifically. The evaluation or measurement of flexibility, texture, water resistance, peel strength and moisture permeability in the following Examples and Comparative Examples were performed according to the following methods.

Flexibility (Clark method) Determined in accordance with the C method (Clark method) described in JIS L1096.

Texture The surface of the nonwoven fabric of the moisture-permeable sheet was stroked by hand, and a test was conducted to determine the tactile sensation at that time. ○ ‥‥ There is no roughness and there is no feeling of being caught. × ‥‥ There is roughness and there is a feeling of being caught.

The water resistance was determined in accordance with JIS L1092 in accordance with the hydrostatic pressure method of the water resistance test method.

Peel Strength A test piece cut from a moisture-permeable sheet or a laminated sheet to a width of 25 mm and a length of 200 mm was subjected to JIS L1096.
According to the above, the film was subjected to a peeling test at a tensile speed of 200 mm / min, and the peeling strength between the film and the nonwoven fabric was measured.

The moisture permeability was determined according to the moisture permeability test method (cup method) described in JIS Z0208.

(Example 1) Polyethylene (melting point: 120)
° C) spunbonded nonwoven fabric (basis weight: 23 g / m
² , fineness: 4.0d) and polyethylene (raw material: LLD)
An air-permeable film (thickness: 23 μm) made of PE, melting point: 122 ° C.) is overlaid, and an embossing roll (emboss pattern: lattice pattern shown in FIG. 1, engraved length: 6.36 mm, width) is placed on the nonwoven fabric. : 0.5 mm, both ends: semicircular part, pitch: 15 mm, emboss area ratio: 7.2%)
30kg / cm pressure (linear pressure) at 110 ° C using
Then, it was pressurized and thermally fused to obtain a moisture-permeable sheet. The obtained moisture-permeable sheet was evaluated or measured for flexibility, hand, water resistance and moisture permeability. Table 1 shows the results.

Example 2 Polyethylene (melting point: 120)
° C) and polypropylene (melting point: 160
° C) and a core / sheath type crimped fiber having a core / sheath ratio of 4/6 in the fiber cross-sectional area of the sheath / core (fineness: 2.6 d, basis weight: 23 g / m ² )
Polyethylene (raw material: LLDPE, melting point: 122
C)), and the same embossing roll as that used in Example 1 is applied on the nonwoven fabric at 115 ° C. under a pressure (linear pressure) of 30 kg / cm. Then, heat fusion was performed under pressure to obtain a moisture-permeable sheet. The obtained moisture-permeable sheet was evaluated or measured for flexibility, hand, water resistance and moisture permeability. Table 1 shows the results.

Example 3 Propylene / ethylene copolymer (ethylene content: 3.8 mol%, melting point: 150
° C.) consisting surface nonwoven layer (basis weight 15 g / m ^2, fineness: a 2.5d), nonwoven fabric layer comprising an ethylene · alpha-olefin copolymer (basis weight: 10 g / m ^2, fineness: 0.
5d) Polyethylene (raw material: LLDPE, melting point: 122) on the surface nonwoven fabric layer of the laminated nonwoven fabric having two layers of 5d)
° C) (amount per unit area: 25 g / m ²⁾
An embossing roll (emboss pattern: lattice pattern shown in FIG. 2, engraved length: 6.36 mm, width: 0.5 mm, both ends: semicircular part, pitch: 15 mm, emboss area ratio: 7.2%)
30kg / cm pressure (linear pressure) at 110 ° C using
Then, it was pressurized and thermally fused to obtain a moisture-permeable sheet. The obtained moisture-permeable sheet was evaluated or measured for flexibility, hand, water resistance and moisture permeability. Table 1 shows the results.

Example 4 Polypropylene (melting point: 16)
0 ° C) spunbonded nonwoven fabric (basis weight: 18 g /
m ² , fineness: 2.1 d) and polypropylene (melting point: 1)
65 [deg.] C.) and a breathable film (thickness: 23 [mu] m) made of 35 kg / 140 [deg.] C. on the nonwoven fabric using the same embossing roll as used in Example 3.
At a pressure (linear pressure) of 1 cm, pressure was applied and heat-sealed to obtain a moisture-permeable sheet. About the obtained moisture-permeable sheet, flexibility,
The texture, water resistance and moisture permeability were evaluated or measured. Table 1 shows the results.

Comparative Example 1 Polypropylene (melting point: 16)
0 ° C) dry nonwoven fabric (fineness: 2.6d, basis weight:
21 g / m ² ) and polyethylene (raw material: LLDPE,
Air-permeable film (thickness: 23)
μm) using a hot melt adhesive to obtain a laminated sheet. About the obtained laminated sheet, flexibility,
The texture, water resistance and moisture permeability were evaluated or measured. Table 1 shows the results.

Comparative Example 2 Polyethylene (melting point: 120)
° C) spunbonded nonwoven fabric (basis weight: 23 g / m
² , fineness: 4.0d) and polyethylene (raw material: LLD)
An air-permeable film (thickness: 23 μm) made of PE, melting point: 122 ° C.) is overlapped, and an emboss roll (emboss pattern: rhombus, engraved length: 1) is placed on the nonwoven fabric.
1.8 mm, width: 11.8 mm, pitch: 20 mm, emboss area ratio: 38.4%) at 110 ° C.
At a pressure (linear pressure) of kg / cm, pressure was applied and heat-sealed to obtain a moisture-permeable sheet. The obtained moisture-permeable sheet was evaluated or measured for flexibility, hand, water resistance and moisture permeability. Table 1 shows the results.

[0057]

[Table 1]

[0058]

The moisture-permeable sheet of the present invention is excellent in flexibility, hand and water resistance, has high delamination strength, and is particularly excellent in the balance of these physical properties. Therefore, the moisture-permeable sheet of the present invention is suitable for uses such as a back sheet for a disposable diaper.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a preferred example of an emboss pattern in an emboss roll used for manufacturing a moisture-permeable sheet of the present invention.

FIG. 2 is a diagram illustrating another preferred example of an emboss pattern in an emboss roll used for manufacturing the moisture-permeable sheet of the present invention.

FIG. 3 is a diagram illustrating another preferred example of an emboss pattern in an emboss roll used for manufacturing the moisture-permeable sheet of the present invention.

Claims (4)

[Claims] 1. An air-permeable film and a non-woven fabric made of a fiber containing a resin having a melting point equal to or lower than the melting point of the resin constituting the air-permeable film are laminated, and the emboss area ratio is 5 to 20%. , A moisture-permeable sheet that is heat-sealed by embossing an embossed pattern without corners. 2. A nonwoven fabric comprising a core-sheath composite fiber having a sheath made of a resin having a melting point equal to or lower than the melting point of the resin constituting the breathable film. 2. The moisture-permeable sheet according to 1. 3. The non-woven fabric according to claim 1, wherein the non-woven fabric is a side-by-side type composite fiber having a fused portion made of a resin having the same or lower melting point than the resin constituting the breathable film. The moisture-permeable sheet as described in the above. 4. A laminate wherein the nonwoven fabric has, on the side in contact with the breathable film, a fusible nonwoven fabric layer made of a resin having a melting point equal to or lower than the melting point of the resin constituting the breathable film. The moisture-permeable sheet according to claim 1, which is a nonwoven fabric.