JPH11291376A - Manufacture of moisture-permeable sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moisture-permeable sheet which is formed of an unwoven fabric and an air-permeable film and shows a high pliability, a good feeling and an unexcelled bulkiness and at the same time, an excellent water resistance and a high interlayer release strength. SOLUTION: This method for manufacturing a moisture-permeable sheet is to stack an air-permeable film on an unwoven fabric consisting of fibers impregnated with a resin having the same melt point as or a lower melt point than that of a resin which constitutes the air-permeable film, and thermally press both film and unwoven fabric using an embossing device structured of an embossing roll with 5-30% embossing area rate and and at least the rounded corner parts of a projecting tip face and a soft flat roll formed of a silicone rubber, a fluororubber or the like. Thus the film and unwoven fabric are laminated monolithically.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a moisture-permeable sheet which is obtained by laminating and integrating a breathable film and a nonwoven fabric, particularly a spunbonded nonwoven fabric, and which is suitable mainly as a backsheet material for absorbent articles such as disposable diapers.

[0002]

BACKGROUND OF THE INVENTION Generally, in an absorbent article such as a disposable diaper, an absorbent for absorbing and retaining bodily fluids is disposed inside the absorbent article (on the side in contact with the human skin when the absorbent article is used). It has a structure in which it is wrapped and contained by a top sheet material (facing material) and a back sheet material arranged outside. The top sheet material placed inside contacts the skin,
There is a need for a function that allows body fluids excreted from the human body to penetrate and be absorbed by the internal absorber, and does not allow the body fluids to return from the absorber.

On the other hand, the back sheet material is required to have a function of preventing the body fluid absorbed by the internal absorber from leaking to the outside and preventing the liquid from penetrating from the outside to the inside. Furthermore, in order to prevent stuffiness due to moisture generated inside during use of the absorbent article, it is required that the absorbent article has an appropriate moisture permeability that can transmit moisture inside the absorbent article and release it to the outside. .

[0004] Further, since this back sheet material constitutes the outer surface of the absorbent article, it is required that the back sheet material has an excellent texture and a good tactile sensation (feel of touch). Conventionally, in order to obtain a good tactile sensation as this back sheet material,
The backsheet material has a two-layer structure, a porous polyethylene film is used as an inner layer in contact with the absorber, a nonwoven fabric is used as an outer surface layer in contact with the outside air, and the porous polyethylene film and the nonwoven fabric are hot-melt adhesive. Are known.

However, the above-mentioned multilayer sheet impairs the flexibility and texture of the nonwoven fabric, is inferior in flexibility, produces a so-called stiff and hard touch, or produces paper noise, and the touch is still insufficient. .

[0006] 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, there is a limit in making the film thinner, so the nonwoven fabric must be made thinner. 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 penetrates the non-woven fabric and oozes outward, that is, a so-called adhesive bleed-through occurs. However, there is a problem that the tactile sensation on the outer surface is impaired.

[0007] Japanese Patent Application Laid-Open No. 10-1 related to the present applicant.
No. 6115 discloses a moisture-permeable sheet that does not impair the flexibility and texture of a nonwoven fabric, has excellent flexibility and surface feel, has excellent moisture permeability and water resistance, and has high delamination strength. This moisture-permeable sheet is formed by laminating a breathable film and a nonwoven fabric made of a composite fiber containing a resin having the same or lower melting point than the resin constituting the breathable film, and having an emboss area ratio of 5 to 5. 20%, heat-sealed by embossing which can give an embossed pattern with an R at the corner.

However, when a spunbonded nonwoven fabric formed of a conjugate fiber composed of a sheath made of polyethylene and a core made of polypropylene and a breathable polyethylene film are laminated and integrated by hot embossing, conventionally, embossing is performed. A mirror roll made of stainless steel was used as a flat roll (a roll having no unevenness on the surface for embossing) forming a pair with the roll. When this mirror roll is used as a flat roll, if the speed of hot embossing is increased, even if the upper end face of the embossed protrusion formed on the surface of the embossing roll is rounded, the moisture permeability formed by hot embossing is Since a large load is applied to the bottom surface of the concave portion of the sheet, micro holes may be formed in the bottom surface of the concave portion of the nonwoven fabric, and the water resistance may be reduced.

Therefore, the present invention relates to a method for producing a moisture-permeable sheet comprising a nonwoven fabric and a breathable film, which is excellent in flexibility, texture and bulkiness without deteriorating the water resistance as described above. There is a demand for a method for producing a moisture-permeable sheet having excellent and high delamination strength with high productivity.

[0010]

An object of the present invention is to solve the problems associated with the prior art as described above, and comprises a nonwoven fabric and an air-permeable film, which is excellent in flexibility, texture and bulkiness, and is water-resistant. It is an object of the present invention to provide a method for producing a moisture permeable sheet having excellent delamination and high delamination strength with high productivity.

[0011]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for producing a moisture-permeable sheet, comprising a non-woven fabric comprising a breathable film and a fiber containing a resin having a melting point equal to or lower than the melting point of the resin constituting the breathable film. And a soft flat roll having an embossed area ratio of 5 to 30% and at least a corner of the front end surface of the convex portion being rounded, and a soft flat roll. It is characterized in that it is pressure-treated and laminated and integrated.

[0012] As the soft flat roll, JIS
A hardness (JIS K 6301) is 45 to 90, the upper limit of usable temperature is in the range of 280 to 300 ° C, and
A roll made of silicone rubber having a specific gravity (JIS L-1096) of 1.4 to 2.0, or a JIS A hardness (JIS K63
01) is 45 to 90, and the upper limit of usable temperature is 28.
Within the range of 0 to 300 ° C and specific gravity (JIS L-1096)
Is preferably a roll made of fluororubber having a ratio of 1.4 to 2.0.

[0013]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the method for producing a transparent sheet according to the present invention will be specifically described. In the method for manufacturing a moisture-permeable sheet according to the present invention, the air-permeable film and the nonwoven fabric are superimposed, and heated and pressurized by using an embossing device including an embossing roll and a soft flat roll to be laminated and integrated. Thereby, a moisture-permeable sheet is obtained.

The breathable film used in the present invention is a film that has moisture permeability that allows the passage of water vapor, has micropores that are impermeable to liquids such as water, and has water resistance. This breathable film has a moisture permeability of 1000 g / m ^2.
24 hours or more, preferably 2000 to 6000 g / m
It is a film having a moisture permeability of ² · 24hr. Here, in the present invention, the moisture permeability is defined as JIS P 0208.
Refers to a measurement value required in a moisture permeability test in accordance with

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, or a mixture of two or more of these. Resins.

In the present invention, the ethylene / α-olefin copolymer used as the polyolefin resin is
It is a copolymer comprising ethylene and an α-olefin having 4 to 12 carbon atoms, and the propylene / α-olefin copolymer comprises propylene and ethylene or 4 carbon atoms.
And α-olefins of No. 12 to No. 12.

Examples of the α-olefin having 4 to 12 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-hexene,
Methyl-1-pentene, 1-octene, 1-decene, 1-dodecene and the like. The ethylene / α-olefin copolymer may contain one type of these α-olefins having 4 to 12 carbon atoms or a combination of two or more types. Among these α-olefins, α-olefins having 4 to 6 carbon atoms are particularly preferred.

In the ethylene / α-olefin copolymer, a repeating structural unit derived from ethylene (hereinafter referred to as “ethylene unit”) has 4 to 12 carbon atoms.
The repeating structural unit derived from α-olefin of the formula (hereinafter referred to as “α-olefin unit”) is a proportion of 50% by weight or less of α-olefin unit to 50% by weight or less and less than 100% by weight of ethylene unit, preferably Α-olefin units 1 to 4 per 55 to 99% by weight of ethylene units
5% by weight, more preferably 65 to 65 ethylene units
It is desirable that the content of the α-olefin unit be 2 to 35% by weight with respect to 98% by weight, particularly preferably the content of the α-olefin unit is 4 to 30% by weight with respect to the ethylene unit of 70 to 96% by weight.

The polyolefin resin may contain a thermoplastic resin such as an ethylene polymer or a propylene polymer as a component other than the above main components.
The polyolefin resin used in the present invention has a melt flow rate (MFR; ASTM D1238-65T) of 1 to 25 g / 1.
It is desirably in the range of 0 minutes, more preferably 2 to 15 g / 10 minutes. The polyolefin resin having a melt flow rate within the above range can be formed into a film having excellent mechanical strength such as tear strength stably by a casting method, and has good processability by a process such as stretching of the formed film. And a film having excellent air permeability can be obtained.

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

Further, a resin composition containing a polyolefin resin as a main component, which is used as a material of a breathable film, comprises:
It contains a filler in addition to the above polyolefin resin. 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 metal oxides and hydroxides.
Carbonates, sulfates and silicates; oxides, hydroxides, carbonates, sulfates and silicates of Group III elements of the periodic table; and organic fillers such as wood flour and pulp. And the like; cellulose powder such as silicone, phenol and the like. These can 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. Content ratio of polyolefin resin to filler in this resin composition (polyolefin resin / filler)
Is 30/70 to 80/20.

When the resin composition contains an antioxidant, the content of the antioxidant is usually from 0.1 to 2.% based on 100 parts by weight of the total of the polyolefin resin and the filler in the resin composition. About 0 parts by weight, preferably 0.5 to
It is about 1.8 parts by weight.

Further, in addition to the above 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 is usually 20 parts by weight or less based on 100 parts by weight of the ethylene / α-olefin copolymer.

The above resin composition is prepared by mixing the above-mentioned polyolefin resin, or the polyolefin resin and a filler, and various compounding agents, if necessary, with a Henschel mixer, a tumbler type mixer, a V type mixer or the like. It can be performed according to a method of mixing using a conventional mixer.

In the present invention, the polyolefin resin or the resin composition is formed into a film. This 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 sheet shape, and may be performed according to any method. For example, a polyolein resin or a resin composition is melt-kneaded using a conventional apparatus such as a single-screw or twin-screw extruder or a twin-screw kneader, and then blown, formed into a film or sheet by extrusion using a T-die or the like. Can be molded. The resin temperature during melt kneading is usually 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 by a T-die, after forming an unoriented sheet or film, uniaxial stretching by roll stretching or biaxial stretching by a tender 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. In the case of biaxial stretching, it is possible to further reduce the film thickness. If it is desired to improve the softness due to a decrease in rigidity and to eliminate the anisotropy in strength, biaxial stretching is effective.

In the case of uniaxial stretching, roll stretching is usually used, and the stretching may be performed in one stage or 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 touch.

In the case of biaxial stretching, simultaneous or sequential stretching is performed. At this time, the stretching temperature is adjusted to 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,
A breathable film with good touch can be obtained.

Heat treatment after uniaxial stretching or biaxial stretching is effective because a breathable film having excellent dimensional stability can be obtained. Heat treatment at 80 ° C
To the melting point of the film, usually at a 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%. Some are preferred. The breathable film preferably has a Young's modulus of 60 to 300 MPa, and has a tear strength of 4 in the MD direction (longitudinal direction).
Those having 0 N / cm or more are preferable. In the present specification, the "breathable film", after forming a film from a polyolefin resin or a composition thereof as described above,
By applying uniaxial or biaxial stretching, the moisture permeability becomes 10
It indicates that the pressure is not less than 00 g / m ² · 24 hr, but also includes a result of a needle hole processing.

The thickness of the breathable film used in the present invention is usually about 10 to 30 μm, preferably 10 to 30 μm.
２５25 μm. Further, the moisture permeability is from 2000 to 600
Those having 0 g / m ² · 24 hr are preferred.

The nonwoven fabric used in the present invention is made of fibers containing a resin having a melting point that is the same as or lower than the melting point of the resin constituting the breathable film (hereinafter referred to as “low melting point resin component”). .

The nonwoven fabric used in the present invention includes, for example, a fiber composed of a low-melting-point resin component (hereinafter referred to as “low-melting-point fiber”) and a fiber composed of a high-melting-point resin component (hereinafter, referred to as “low-melting-point fiber”).
Non-woven fabric having a structure in which low-melting fiber is fused to a part of the outer peripheral surface of high-melting fiber, and further, non-woven fabric having such a structure Non-woven fabrics having a structure in which they are laminated and mixed are exemplified.

The above-mentioned conjugate fiber is composed of, for example, a sheath made of a low-melting-point resin component and a core made of a high-melting-point resin component, and has a cross-sectional shape in which the sheath surrounds the core concentrically around the core. Concentric core-sheath type composite fiber, eccentric core-sheath type composite fiber whose core portion is eccentric and whose core portion is not exposed on the fiber surface, and sheath portion having a core portion as an axis Eccentric core-sheath type conjugate fiber whose core is partially exposed on the fiber surface due to eccentricity. Also, by dividing the fiber cross section,
A side-by-side conjugate fiber in which both the high-melting component portion composed of the low-melting resin component and the low-melting component portion composed of the high-melting resin component each form a part of the fiber outer peripheral surface is exemplified.

The core / sheath type composite fiber has a core / sheath area ratio of about 5/5 to 1/9 in the fiber cross section.
In the side-by-side type conjugate fiber, the area ratio of the low-melting resin component to the high-melting resin in the fiber cross section is usually about 5/5.

The nonwoven fabric used in the present invention may be not only a single nonwoven fabric as described above, but also a nonwoven fabric having a multilayer 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 layer other than the fusible nonwoven layer. This is effective, for example, in that the degree of freedom in selecting the nonwoven fabric used as the nonwoven fabric layer constituting the surface of the moisture-permeable sheet is increased. When the moisture-permeable sheet according to the present invention has a nonwoven fabric having a multilayer structure, the basis weight of the entire 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 ² .

The low-melting-point resin component constituting the fibers forming the nonwoven fabric is a resin having the same melting point as the resin constituting the breathable film or having a melting point lower than the melting point of the resin. As the low melting point resin component, for example, polyolefin resin such as polypropylene, polyethylene, propylene / ethylene random copolymer or the like, which is the same as the material resin of the breathable film or has a melting point lower than the melting point of the resin. Species or a mixture of two or more 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%. is there.

In the present invention, the resin constituting the non-woven fabric forming fiber, particularly the eccentric core-sheath type composite fiber, has a melt flow rate (MFR; ASTM D 1238-65T, 230 ° C., load 2.16 kg) of 20 g / 10. Of propylene / ethylene random copolymer and melt flow rate (MFR; ASTM)
D 1238-65T, 230 ° C, load 2.16 kg), using a mixed resin raw material composed of a combination with polypropylene at 35 g / 10 min, it is possible to obtain a non-woven fabric composed of crimped fibers. It is effective for improvement. In the combination of the propylene / ethylene random copolymer and the polypropylene, the weight ratio of the propylene / ethylene random copolymer / polypropylene is from 1/9 to
9/1, preferably 1/9 to 4/6.

The average fiber diameter of the fibers forming the non-woven fabric is usually about 10 to 35 μm, and the feeling of snagging when touching the non-woven fabric with a fingertip is reduced and a good tactile sensation is obtained. Preferably, there is.

The basis weight or thickness of the nonwoven fabric is appropriately selected according to the use of the moisture-permeable sheet according to the present invention, particularly the required flexibility and the like, and is not particularly limited. Usually, the basis weight is 10
A to 30 g / m ² approximately, in that the thin moisture vapor permeable sheet of thickness is obtained is preferably 10 to 25 g / m ^2. The thickness of the nonwoven fabric is usually 0.1 to 0.5 mm
It is about. This thickness is a value measured by an optical microscope.

The production of the nonwoven fabric as described above can be performed according to a conventional method, and is not particularly limited. For example, in the case of producing a nonwoven fabric composed of only low-melting fibers, a nonwoven fabric is formed from a low-melting resin component according to a method of melting or dissolving a raw resin such as a spunbond method, a melt blown method, a flash spinning method, and then forming into a fiber and forming into a nonwoven fabric. Can be molded.

In the case of producing a nonwoven fabric composed of a core-sheath type composite fiber, it can be produced according to a spunbonding method using a core-sheath type spinning nozzle. Further, in the case of producing a nonwoven fabric made of a side-by-side type conjugate fiber, it can be produced according to a spunbond method using a side-by-side type spinning nozzle.

Further, in the case of producing a nonwoven fabric in which low-melting fiber and high-melting fiber are mixed, one of the low-melting fiber and the high-melting fiber is formed by a spun bond method, a flash spinning method, or a melt blown method. Then, when the obtained fibers are dispersed on a web former, the fibers can be produced by mixing with the other fibers and depositing them.

Also, a multilayer structure having a multilayer structure composed of a plurality of nonwoven fabrics, and including 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 on the side in contact with the breathable film. The nonwoven fabric having a layered structure can be manufactured according to a method such as a spunbond method, a flash spinning method, and a melt blown method using an apparatus having two or more rows of spinning nozzles.

[0049] In the manufacturing method the manufacturing method of the moisture vapor permeable sheet in accordance with the present invention the moisture-permeable film, and the breathable film, after superposing the nonwoven fabric, and heating and pressing treatment by an embossing roll and a soft flat roll, ventilation The conductive film and the nonwoven fabric are partially melted by the low-melting point resin component of the nonwoven fabric by the embossing roll, pressed, and bonded by heat fusion.

The temperature and pressure of the heating and pressurizing treatment are as follows: the constituent fibers, structure, basis weight and thickness of the nonwoven fabric used;
It is appropriately selected according to the material, the basis weight and the thickness of the breathable film, the desired water resistance, the delamination strength, the processing speed (lamination speed), and the like.
℃, preferably about 100 to 130 ℃, 10
Pressure of about 50 kg / cm (linear pressure), preferably 20
It is performed at a pressure of about ｋｇ40 kg / cm.

The embossing roll used for the heating and pressurizing treatment is an embossing roll in which at least a corner of the front end surface of the convex portion is rounded. For example, when the shape of the front end surface (upper surface) of the convex portion of the embossing roll is a quadrangle, an embossing roll in which the corners of the four corners and the corners of the four sides are rounded is used. The shape of the tip of the convex portion of the embossing roll used in the present invention is a circle, a shape composed of curves such as an ellipse, or a shape in which a straight line is smoothly connected to a circle, an ellipse, and the like. It is formed in an arc shape, and has a shape such as a rectangular shape in which the radius of curvature of the arc portion is at least 0.15 mm or more. In particular, it is preferable to use an embossing roll having an embossing pattern (a pattern at the tip end surface of the embossing roll) 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 four corners of the upper surface of the convex portion of this embossing roll, and the corners of the four sides, are rounded. In addition, the emboss area ratio in the embossing roll (the area ratio of the embossed convex portion)
Is 5 to 30%, preferably 5 to 20%, and more preferably 5 to 15%. In particular, when a soft touch sheet is required, the emboss area ratio 7 shown in FIGS.
It is preferable to use an embossing roll having an embossing pattern of a wide lattice pattern of up to 15%.

The soft flat roll used in the present invention has a JIS A hardness (JIS K 6301) of 45 to 90, a usable upper limit temperature of 280 to 300 ° C., and a specific gravity (JIS L-1096) is a roll made of silicone rubber having 1.4 to 2.0, or JIS A
Fluororubber having a hardness (JIS K 6301) of 45 to 90, an upper limit of usable temperature in a range of 280 to 300 ° C, and a specific gravity (JIS L-1096) of 1.4 to 2.0 Is preferably used. Also, a soft paper roll can be used. By using these soft flat rolls in combination with the above-mentioned embossing rolls, even if the linear pressure of the embossing rolls is increased to 50 kg / cm, micropores are not formed on the bottom surface of the concave portion of the obtained moisture-permeable sheet. In addition, high delamination strength and flexibility can be maintained without lowering water resistance.

Moisture- permeable sheet Among the moisture-permeable sheets obtained by the method for producing a moisture-permeable sheet according to the present invention, the water resistance is 1000 m.
mH ₂ O or more, moisture permeability is 3000 g / m ² · 24 hr or more, and flexibility in the MD direction (Clark method) is 50 mm
A moisture-permeable sheet having the following properties and having a delamination strength of 50 g / 25 mm or more is suitable as a back sheet for a disposable diaper. The backsheet for a disposable diaper made of this moisture-permeable sheet has a moisture-absorbent sheet layer disposed on the inner side in contact with the absorbent body of the disposable diaper, and a surface layer (top sheet) composed of a nonwoven fabric disposed on the outer side in contact with the outside air. What is used. In the present invention, the “MD direction” refers to the longitudinal direction of the moisture-permeable sheet. The numerical value of the flexibility is a numerical value measured by the Clark method described as a method C in JIS L 1096.

[0054]

According to the method for producing a moisture-permeable sheet according to the present invention, a soft roll made of silicone rubber or fluororubber is used as a flat roll paired with an embossing roll. The present invention can provide a moisture-permeable sheet comprising a water-permeable film, which is excellent in flexibility, texture, and bulkiness, has excellent water resistance, and has high delamination strength. Further, the productivity of the moisture-permeable sheet is improved as compared with the conventional case.

[0055]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

The evaluation or measurement of the feeling, water resistance, delamination strength, moisture permeability and flexibility in the examples and comparative examples were performed according to the following methods. (1) Texture The texture was evaluated by rubbing the surface of the nonwoven fabric of the moisture-permeable sheet by hand and examining the tactile sensation at that time. In addition, evaluation is the average of panel test of ten persons.

<Evaluation Criteria> ○ · · · · · · · · · · · · · · · · · △ · · · · · · · There is a slight feeling of roughness and catch. × · · · · · · · There is a feeling of roughness and catching. (2) Water Resistance The water resistance was determined in accordance with the hydrostatic method of Method A (low water pressure method) of the water resistance test method described in JIS L 1092.

(3) Interlaminar Peel Strength A 180 ° peel test was performed on a test piece cut from the laminated sheet to a width of 25 mm and a length of 200 mm in accordance with JIS L 1096 at a tensile speed of 300 mm / min. The interlayer peel strength between them was measured. (4) Moisture Permeability The moisture permeability was determined based on the moisture permeability test method (cup method) described in JIS Z 0208. (5) Flexibility (Clark method) Based on the C method (Clark method) described in JIS L 1096, the flexibility in the MD direction (longitudinal direction) and CD direction (lateral direction) of the laminated sheet was determined.

[0059]

Example 1 Concentric core-sheath type composite fiber (polyethylene / polypropylene (weight ratio) = 80/20) formed from a core made of polypropylene having the following physical properties and a sheath made of polyethylene having the following physical properties , Fiber diameter =
22 μm), a spunbonded nonwoven fabric having a basis weight of 23 g / m ² and a breathable polyethylene film having the following physical properties are superimposed, and a steel embossing roll (roll diameter = 20 cm) having a surface temperature of 120 ° C. The nonwoven fabric is passed through a flat roll made of silicone rubber (roll diameter = 20 cm) having a surface temperature of 118 ° C. so that the nonwoven fabric comes to the emboss roll side, and is pressurized at a pressure (linear pressure) of 5 kg / cm and thermally fused. And a laminated sheet was obtained at a production speed of 100 m / min.

The embossing roll has a convex portion of 0.4.
4 × 0.44 mm square, the pitch is 1.7 mm, the emboss area ratio is 6.7%, and the number of stamps is 0.3.
5 pieces / mm ² . The corners of the projections are rounded.

The silicone rubber constituting the above-mentioned silicone rubber flat roll has a JIS A hardness (JIS K 6301) of 60, an upper limit of usable temperature of 280 ° C., and a specific gravity (JIS L). -1096) is 1.6.

<Polypropylene Constituting Core of Composite Fiber
> Propylene homopolymer Density = 0.91 g / cm^Three  MFR (230 ° C.) = 60 g / 10 min Mw / Mn = 3.0 Melting point = 145 ° C. <Polyethylene constituting sheath portion of conjugate fiber> Ethylene homopolymer Density = 0.928 g / cm^Three  MFR (190 ° C.) = 30 g / 10 min Mw / Mn = 3.2 Melting point = 125 ° C. <Breathable polyethylene film> Breathable film “ESPOAR” manufactured by Mitsui Chemicals, Inc.^TM(Thickness: 20 μm) For the laminated sheet obtained as described above,
Evaluation of water resistance, delamination strength, moisture permeability and flexibility
Alternatively, the measurement was performed according to the method described above.

Table 1 shows the results.

[0064]

Example 2 In Example 1, the production speed was set to 150 m /
A laminated sheet was obtained in the same manner as in Example 1 except that the thickness was changed to minutes.

The obtained laminated sheet was evaluated or measured for feel, water resistance, delamination strength, moisture permeability and flexibility according to the above-mentioned method. Table 1 shows the results.

[0066]

Comparative Example 1 A hot melt adhesive [trade name: 5P-619, manufactured by NSC Co., Ltd.] was used in Example 1 instead of using the embossing roll to integrate the spunbonded nonwoven fabric and the breathable polyethylene film. Using 2
Laminated sheets were prepared at a production speed of 00 m / min. In addition,
The application amount of the hot melt adhesive was 1.5 g / m ² .

The obtained laminated sheet was evaluated or measured for feel, water resistance, delamination strength, moisture permeability and flexibility according to the above-mentioned method. Table 1 shows the results.

[0068]

Comparative Example 2 In Example 1, a stainless steel mirror roll (roll diameter = 20 cm) was used instead of the silicone rubber flat roll, and the production speed was 60 m.
A laminated sheet was obtained in the same manner as in Example 1 except that the rate was changed to / min. The surface temperatures of the embossing roll and the stainless steel mirror roll were both set to 120 ° C.

The obtained laminated sheet was evaluated or measured for feeling, water resistance, delamination strength, moisture permeability and flexibility according to the above-mentioned methods. Table 1 shows the results.

[0070]

Comparative Example 3 A laminated sheet was obtained in the same manner as in Example 1, except that a stainless steel mirror roll (roll diameter = 20 cm) was used instead of the silicone rubber flat roll.

The obtained laminated sheet was evaluated or measured for feel, water resistance, delamination strength, moisture permeability and flexibility according to the above-mentioned method. Table 1 shows the results.

[0072]

[Table 1]

[Brief description of the drawings]

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

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

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

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification code FI // B29L 9:00 31:48 (72) Inventor Shigeyuki Motomura 1-2-1, Waki, Waki-machi, Kuga-gun, Yamaguchi Prefecture Mitsui Chemicals, Inc.

Claims (4)

[Claims] 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 superposed, and the emboss area ratio is 5 to 30. %, And at the corner of the tip surface of the convex portion is subjected to heat and pressure treatment using a embossing device composed of a soft flat roll and an embossing roll having a rounded corner, and laminated and integrated. For producing a moisture-permeable sheet. 2. A sheath comprising a resin having a melting point equal to or lower than the melting point of the resin constituting the breathable film, and a core comprising a resin having a melting point higher than the melting point of the resin. The method for producing a moisture-permeable sheet according to claim 1, wherein the sheet is formed from a core-in-sheath type conjugate fiber composed of: 3. A highly fusible component comprising a resin having a melting point equal to or lower than the melting point of the resin constituting the breathable film, and a resin having a melting point higher than the melting point of the resin. The method for producing a moisture-permeable sheet according to claim 1, wherein the composite sheet is formed from a side-by-side type conjugate fiber composed of a low-melting component part composed of: 4. The soft flat roll has a JIS A hardness (JIS K 6301) of 45 to 90, a usable upper limit temperature of 280 to 300 ° C., and a specific gravity (JISL-1096). Consisting of a silicone rubber having a JIS hardness of 1.4 to 2.0, or a JISA hardness of 45 to 90, an upper limit of usable temperature in a range of 280 to 300 ° C, and a specific gravity of 1.4 to 2.0. The method for producing a moisture-permeable sheet according to claim 1, wherein the roll is a roll made of fluororubber of 2.0.