JP2002316359A - Porous film/nonwoven fabric composite sheet and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous film/nonwoven fabric composite sheet which exhibits high moisture permeability, high tear strength, ample bulkiness, superior pliability and excellent feel as well as a method for manufacturing a porous film/nonwoven fabric composite sheet. SOLUTION: The method for manufacturing the porous film/nonwoven fabric composite sheet comprises the steps to stretch a composite sheet obtained by laminating a non-elastic nonwoven fabric on one side or both sides of a film formed of a resin composition containing 25 to 70 wt.% of a polyolefin resin and 75 to 30 wt.% of an inorganic filler, in an orthogonal direction with a mechanical axial direction by a gear stretching process and make the composite sheet porous. The porous film/nonwoven fabric composite sheet has 400 kg/mm or above of tear strength in the mechanical axial direction, 3,000 g/m<2> /24 hr or above of moisture permeability, 500"/100 cc or below of air permeability and 1,700 mmAq or above of hydraulic pressure resistance. In addition, the porous film/nonwoven fabric composite sheet has a thickness of 150 to 250 μm and an amount added of 30 to 60 g/m<2> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a porous film / nonwoven fabric composite sheet and a method for producing the same. For more information,
The present invention relates to a porous film / nonwoven fabric composite sheet having high moisture permeability, exhibiting good tear strength, having a bulky feel, being flexible and having excellent touch, and a method for producing the same.

[0002]

2. Description of the Related Art Hitherto, many methods have been proposed for producing a porous film by stretching a film containing a polyolefin resin and an inorganic filler in a uniaxial or biaxial direction to generate voids communicating with the film. The porous film is used for various purposes such as a sanitary material, a medical material, a clothing material, a building material, a battery separator, and the like.

[0003] For example, Japanese Patent Application Laid-Open No. 57-47334 is characterized in that a film or sheet obtained by melt-molding a composition comprising a polyolefin resin and a filler and a liquid rubber is subjected to a stretching treatment. A method for producing a porous film or sheet is disclosed, and examples of a stretching method include roll stretching and tube stretching. Uniaxial stretching such as roll stretching has the advantage of causing porosity even at a low stretching ratio, but cannot achieve high moisture permeability. If an attempt is made to increase the stretching ratio in order to achieve high moisture permeability, the tear strength will decrease, and practical problems such as film tearing will occur.

[0004] Therefore, biaxial stretching methods such as tube stretching and tenter stretching have been proposed for the purpose of improving tear strength. However, these methods are not preferable for use in disposable products such as disposable diapers and sanitary napkins, because the apparatus becomes large-scale and the production cost increases.

[0005] As a solution to the problems of these general stretching methods, Japanese Patent Application Laid-Open No. 52-36166 discloses (1)
A thermoplastic orientable polymer film, or (2) a thermoplastic comprising an incompatible second phase selected from the group consisting of an incompatible polymer, an inorganic substance, and an inorganic filler-containing polymer matrix Disclosed is a method of stretching a film of an orientable polymer mixture in the longitudinal direction, and further to compensate for the stretching.
A process is described for introducing a membrane into the intermeshing portion of a second intermeshing pair of rollers having a groove perpendicular to the roller axis. This step is combined with the step of extending in the longitudinal direction, and biaxial stretching is realized as a whole.

[0006] However, according to the knowledge of the present inventors, in the method in which such an interlocking step using rollers that are orthogonal to each other is performed twice, a film tear or a pinhole is likely to occur during the second interlocking. In order to solve this problem, there is a method of increasing the film strength by increasing the thickness of the film, but the cost of the raw materials is increased and the texture of the film is deteriorated (feeling rugged). It is not a preferred method for sanitary material applications such as napkins.

Japanese Patent Application Laid-Open No. 9-3227 discloses that a sheet formed from a resin composition containing a polyolefin resin and a filler as essential components has a convex portion of one roll corresponding to a concave portion of the other roll. A porous sheet obtained by engraving a pattern, passing the pattern through a pair of embossing rolls, which are striped in the direction perpendicular to the roll axis, stretching in the horizontal direction, and stretching in the vertical direction Is disclosed. Here, the stretching process in the transverse direction is performed for the purpose of improving the mechanical properties of the sheet, and there is no mention of the technical idea of making the film porous.

[0008] By the way, there is known a moisture-permeable composite sheet having a cloth-like tactile feel obtained by laminating a nonwoven fabric on the above-mentioned porous film, and is used as a backsheet for disposable diapers. This is obtained by laminating a porous film that has been stretched and porous, and a nonwoven fabric with an adhesive such as a hot-melt adhesive. While bulkiness and flexibility are desired, high moisture permeability is also expected.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a porous film / nonwoven fabric composite sheet having high moisture permeability, good tear strength, bulkiness, flexibility and excellent touch, and a method for producing the same. Is to do.

[0010]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that an inelastic nonwoven fabric is formed on one or both sides of a film obtained from a resin composition containing a specific polyolefin resin and a specific inorganic filler. The present inventors have found that the above object can be achieved by stretching the bonded composite sheet by a gear stretching method in a direction orthogonal to the machine axis direction to make the porous sheet porous, and arrived at the present invention.

That is, the present invention provides a composite sheet comprising a resin composition containing 25 to 70% by weight of a polyolefin resin and 75 to 30% by weight of an inorganic filler, and a non-elastic nonwoven fabric bonded to one or both sides of a film. This is a method for producing a porous film / nonwoven fabric composite sheet, characterized in that it is stretched in a direction perpendicular to the machine axis direction by a gear stretching method to be porous.

In a preferred aspect of the present invention, it is preferable that the gear stretching method is a method in which the composite sheet is meshed by at least a pair of gear rolls in which a concave portion and a convex portion are meshed in a gear shape.

In a preferred aspect of the present invention, the gear roll preferably satisfies the following equation (1) as a relationship between a gear pitch (W) and a gear depth (H). H / W ≧ 1 (1) (W is 1 to 5 mm)

In a preferred aspect of the present invention, the degree of engagement (V) and the gear pitch (W) of the pair of gear rolls satisfy the following expression (2), and the degree of engagement (V) of the pair of gear rolls is as follows. ) And the gear depth (H) preferably satisfy the following expression (3). V ≦ 1.5W (2) V ≦ H (3) (W is 1 to 5 mm)

In a preferred aspect of the present invention, the stretching of the composite sheet by the gear stretching method is preferably performed at a temperature from room temperature to 80 ° C. of the gear roll.

In a preferred aspect of the present invention, the stretching ratio (T) of the composite sheet by the gear stretching method is as follows:
It is preferably 1.3 to 3 times.

In a preferred aspect of the present invention, the film made of the resin composition is preferably a stretched film stretched in the machine axis direction at a draw ratio (M) satisfying the following mathematical formula (4). . M ≦ 4 / T (4) (where T is 1.3 to 3 times the stretching ratio of the composite sheet by the gear stretching method)

In a preferred embodiment of the present invention, the polyolefin resin forming the resin composition is preferably at least one selected from linear low-density polyethylene and low-density polyethylene.

In a preferred aspect of the present invention, the inorganic filler is preferably at least one compound selected from calcium carbonate and barium sulfate.

In a preferred aspect of the present invention, the inelastic nonwoven fabric is preferably a spunbonded nonwoven fabric made of an olefin polymer.

According to the present invention, tear strength machine axis direction 400 kg / mm or more, moisture permeability 3000g ^{/ m} 2 · 2
4 hours or more, air permeability is 500 seconds / 100 cc or less, water pressure resistance is 1700 mmAq or more, and the film has a thickness of 1
A method for producing the porous film / nonwoven fabric composite sheet having a thickness of 50 to 250 μm and a basis weight of 30 to 60 g / m ² is provided.

In another aspect of the present invention, the tear strength in the machine axis direction obtained by the above manufacturing method is 400 kg /
mm or more, moisture permeability of 3000g ^/ m 2 · 24hr or more,
Air permeability is 500 seconds / 100 cc or less, water pressure resistance is 1700
It is a porous film / nonwoven fabric composite sheet having a thickness of 150 to 250 μm and a basis weight of 30 to 60 g / m ² which is not less than mmAq.

According to the present invention, it is possible to obtain a porous film / nonwoven fabric composite sheet having high moisture permeability, good tear strength, bulkiness, flexibility and excellent touch. for that reason,
It can be suitably used in the fields of sanitary materials, medical materials, clothing materials, building materials, packaging materials and the like. In particular, it can be suitably used as a material for sanitary materials such as disposable diapers, sanitary napkins, and medical gowns.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The porous film / nonwoven fabric composite sheet of the present invention is a composite sheet obtained by laminating an inelastic nonwoven fabric on one or both sides of a film obtained from a resin composition containing a specific amount of a polyolefin resin and an inorganic filler by a gear stretching method. It is manufactured by stretching in the direction perpendicular to the machine axis direction to make it porous. As a preferable method of the gear stretching method according to the present invention, at least a pair of gear rolls in which a concave portion and a convex portion are engaged in a gear shape are engaged with a film and stretched in a direction orthogonal to a machine axis direction (hereinafter, referred to as a TD direction). Method.

The polyolefin resin used for the film in the present invention is a resin mainly containing a monoolefin polymer such as ethylene, propylene, butene or a copolymer thereof. For example, polyethylene resins such as low-density polyethylene, linear low-density polyethylene (ethylene / α-olefin copolymer), medium-density polyethylene, and high-density polyethylene; polypropylene-based resins such as polypropylene and ethylene-propylene copolymer; -Methyl
Examples thereof include 1-pentene, polybutene, an ethylene / vinyl acetate copolymer, and a mixture thereof.

The polyolefin resin may be a resin produced using a Ziegler catalyst or a resin produced using a single-site catalyst such as a metallocene catalyst. Of these, polyethylene resins are preferred. Further, a linear low-density polyethylene resin, which is an ethylene / α-olefin copolymer, and low-density polyethylene are most preferred. These resins are
They can be used alone or in combination.
In consideration of the moldability and stretchability of the film, the melt flow rate of the polyolefin resin is 0.5 to 5 g.
It is preferably about / 10 minutes.

As the inorganic filler, for example, calcium carbonate, barium sulfate, calcium sulfate, barium carbonate,
Magnesium hydroxide, aluminum hydroxide, zinc oxide,
Examples include magnesium oxide, titanium oxide, silica, and talc. Of these, barium sulfate and calcium carbonate are preferred. These fillers may be used alone or in combination of two or more.

The composition ratio between the polyolefin resin and the inorganic filler affects the moldability and stretchability of the film, the air permeability and the moisture permeability of the obtained film. When the amount of the inorganic filler is small, stretchability is excellent, but adjacent voids obtained by interfacial separation between the polyolefin resin and the inorganic filler are not connected to each other, and a porous film having good air permeability, moisture permeability, etc. I can't get it. On the other hand, when the amount of the inorganic filler is too large, it is not preferable because a molding failure occurs when a film is formed, or the stretchability is lowered and sufficient stretching cannot be performed. From such a viewpoint, the composition ratio of the polyolefin resin and the inorganic filler is preferably 25 to 70% by weight of the polyolefin resin and 75 to 30% by weight of the inorganic filler. More preferably, the polyolefin resin is 30 to 60.
% By weight, and 70 to 40% by weight of the inorganic filler. The average particle size of the inorganic filler is preferably 20 μm or less, more preferably 10 μm or less, and most preferably 0.5 to 5 μm.

The inorganic filler preferably has been subjected to a surface treatment in order to improve the dispersibility with the polyolefin resin. As the surface treatment agent, those capable of rendering the surface hydrophobic by coating the surface of the inorganic filler are preferable, and examples thereof include higher fatty acids such as stearic acid and lauric acid, and metal salts thereof. In the film used in the present invention, a stretching aid, a dispersant, a stabilizer, an antioxidant, a colorant, as long as the object of the present invention is not hindered.
Other additives such as an ultraviolet absorber may be added.

Next, a method for producing a film used in the present invention will be exemplified. For example, after mixing the polyolefin resin, the inorganic filler, and other additives such as a stretching aid and a dispersant, and a stabilizer as necessary using a Henschel mixer, a super mixer, a tumbler type mixer, etc., the mixture is uniaxial or biaxial. The mixture is kneaded using a screw type extruder and pelletized. Here, in order to further improve the dispersibility of the inorganic filler in the resin, a twin-screw extruder is more preferable.

Next, the pellets are melted at a temperature equal to or higher than the melting point of the polyolefin resin, preferably equal to or higher than the melting point + 20 ° C. and lower than the decomposition temperature, by an extruder equipped with a T-die or the like or an inflation machine equipped with a circular die. Melting and film formation using a known molding machine. Considering the thickness accuracy of the film and the strength in the machine axis direction (hereinafter, referred to as the MD direction), a method of melting and forming a film by an extruder equipped with a T die is preferable. In some cases, it is possible to form a film directly with a molding machine without pelletizing. In that case, a method of mounting a T-die on a twin-screw extruder can be mentioned.

The nonwoven fabric used in the present invention is a non-elastic nonwoven fabric. The non-elastic non-woven fabric is a non-elastic non-woven fabric having a maximum elongation in the TD and MD directions of 50% or less. Examples of the material include a thermoplastic resin such as polyester, polyamide, and polyolefin. Among these, olefin polymers having versatility and low cost are preferred.

Specific examples of the olefin polymer include those having 2 to 2 carbon atoms such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene and 1-octene.
20, preferably an α-olefin homopolymer having 2 to 8 carbon atoms, or a copolymer of these α-olefins. Among them, ethylene-based polymers and propylene-based polymers are preferable. Examples of the ethylene-based polymer include ethylene homopolymers and ethylene-based copolymers containing 10 mol% or less of ethylene and other α-olefins. As the polymer, propylene homopolymer, or propylene and ethylene, 1-butene, 1-hexene, 4-methyl
Copolymers with α-olefins such as 1-pentene and 1-octene are exemplified. The copolymer may be a random copolymer or a block copolymer. Above all,
A propylene / ethylene random copolymer composed of propylene and a small amount of ethylene and having a content of structural units derived from ethylene of 5 mol% or less is particularly preferred. These olefin polymers can be used alone or in combination of two or more.

As a method for producing the nonwoven fabric, any method such as a dry method, a wet method, a spun bond method, and a melt blow method may be used. Bonding is preferred. The spunbonded nonwoven fabric obtained by this method is preferred because it has high strength and excellent friction fastness. In addition, as a fiber constituting the nonwoven fabric, a composite fiber obtained by a composite melt spinning method of molding using a plurality of resins can also be used. For example, a sheath made of the above-mentioned one resin and a resin made of another resin are used. A core-sheath composite fiber composed of a core and a nonwoven fabric composed of a side-by-side composite fiber is preferable in that the flexibility can be improved.

In producing a composite sheet in which the above-mentioned film used for gear stretching and an inelastic nonwoven fabric are laminated, the film is preferably 15 to 70 μm, particularly 20 to 60 μm.
It is preferable to use a nonwoven fabric having a thickness of about μm, and it is preferable to use a nonwoven fabric having a basis weight of about 10 to 100 g / m ² . In order to obtain a composite sheet in which such a film and an inelastic nonwoven fabric are bonded to each other, it is preferable to bond the two with an adhesive such as a hot-melt adhesive or to fuse them by ultrasonic waves. Above all, it is preferable to bond with a hot melt adhesive in terms of productivity and cost. When bonding with a hot-melt adhesive, a rubber-based adhesive, a polyolefin-based adhesive, or the like can be used as the hot-melt adhesive. The amount of adhesive applied is
It is preferably 0.5 to 1.5 g / m ² , and within this range, the adhesive strength is sufficient, the adhesive comes off to the back surface of the nonwoven fabric, and it has a hard texture and does not induce blocking.

The application of the hot melt adhesive is desirably performed by, for example, a curtain spray method, and is performed by a method in which the opening is as small as possible. The film having the adhesive surface coated with the hot melt adhesive is compressed by passing between rolls to obtain a composite sheet.

In the present invention, it is an important requirement that the film and the non-elastic nonwoven fabric are bonded in advance to form a composite sheet before gear stretching. In the case of gear stretching, when joining by heat simultaneously with stretching by meshing with gear rolls, the temperature required for fusing is used, so that the surface of the composite sheet becomes harder, the stretching effect is not obtained and the moisture permeability is low. Mimic In addition, it is not preferable that the film and the non-elastic nonwoven fabric are adhered after being respectively bitten by a gear roll and stretched, since the feeling deteriorates.

In the method for producing a porous film / nonwoven fabric composite sheet according to the present invention, a film is formed from a resin composition containing a polyolefin resin and an inorganic filler as described above, and the resulting film is formed into an inelastic nonwoven fabric. After lamination to form a composite sheet, the film is stretched in the TD direction by a gear stretching method to make the film open and porous.

As a method of gear stretching in the TD direction, a gear stretching method in which a film is meshed with a pair of gear rolls (wave-shaped rolls) in which concave portions and convex portions are meshed in a gear shape in order to perform the production at low cost and with good productivity. preferable. The relationship between the wave (peak) between gear rolls (peak) and the height (referred to as gear depth) of the wave (peak) of the gear roll depends on the uniform stretchability and stretch ratio of the obtained composite sheet. Affect. When the gear pitch is W and the gear depth is H, it is preferable that the following formula (1) is satisfied. H / W ≧ 1 (1) Here, W is preferably 1 to 5 mm. In addition,
FIG. 1 shows the relationship between the gear pitch, the gear depth, and the degree of engagement between the gear rolls.

When H / W <1, that is, when the gear depth (H) is shallower than the gear pitch (W), it is difficult to sufficiently engage the film with the gear. The resulting composite sheet has insufficient texture improvement and low moisture permeability. Although the upper limit of H / W is not particularly limited, it is practically 100 or less due to gear processing and maintenance constraints.

The stretching of the composite sheet is desirably performed at a gear roll temperature from normal temperature to 80 ° C.

The degree of engagement (V) of a pair of gear rolls is
Although this affects the stretching ratio in the TD direction, if the degree of engagement (V) is too large, pinholes, tears and the like may frequently occur in the film. Considering this point, the degree of engagement (V) and the gear pitch (W) of the pair of gear rolls satisfy the following expression (2), and the degree of engagement (V) and the gear search (H) of the pair of gear rolls are as follows. It is preferable to satisfy Expression (3). V ≦ 1.5W (2) V ≦ H (3) Here, W is preferably 1 to 5 mm, and H is in a range satisfying the expression (1).

The stretching ratio in the TD direction affects the moisture permeability, productivity and strength of the resulting porous film / nonwoven fabric composite sheet. Assuming that the composite sheet width before gear stretching is B0 and the composite sheet width after stretching is B, the stretching ratio (gear stretching ratio) in the TD direction is represented by B / B0. The stretching ratio (expressed as T) of the gear stretching in the present invention is preferably 1.3 to 3 times.

The stretching ratio is to increase the degree of gear engagement.
Alternatively, it can be changed by an operation of reducing. When the stretching ratio is less than 1.3 times, the improvement of the texture is insufficient, and the adjacent voids obtained by the interfacial peeling between the polyolefin resin and the inorganic filler are not sufficiently connected to each other, so that good moisture permeability is obtained. It is not preferable because it cannot be performed. On the other hand, when the stretching ratio is more than 3 times, sufficient improvement of the texture and sufficient moisture permeability can be obtained, but it is not preferable because the film breaks during stretching and pinholes occur. A more preferred stretching ratio is 1.3 to 2.5 times.

The film strength in the TD direction before gear stretching affects film tearing and pinhole generation during gear stretching. Since gear stretching is realized by meshing a film with a gear, the film is usually easily broken or pinholes are generated at the time of meshing, and productivity is reduced. By increasing the tensile strength of the film in the TD direction before gear stretching, breakage and pinholes are solved. Considering this point, in the present invention,
It is preferable to use a film having a tensile strength in the TD direction before gear stretching of 5 N / 25 mm or more.

As long as the film satisfies the above-mentioned tensile strength in the TD direction, the film before the gear stretching may be subjected to a stretching process in the MD direction. The stretching process in the MD direction is preferably performed by a roll stretching method in consideration of productivity.

The roll stretching process in the MD direction in the present invention is not performed mainly for the purpose of making the film porous, but is performed to supplement the mechanical strength in the MD direction of the composite sheet after gear stretching. MD before gear extension
If the stretching ratio in the direction (expressed as M) is too large, the tensile strength in the TD direction before gear stretching is reduced, and pinholes or tears may occur in the film during gear stretching.
Accordingly, it is not preferable to stretch the film in the MD direction before gear stretching at a high magnification. From this perspective,
It is preferable that the stretching ratio (M) of the film in the MD direction and the stretching ratio (T) of the gear stretching in the TD direction are controlled so as to satisfy the following mathematical expression (4). M ≦ 4 / T (4) More preferably, the following formula (4 ′), more preferably, the following formula (4 ″) M ≦ 3.6 / T (4 ′) M ≦ 3.3 / T ... (4 ") [In the formulas (4), (4 ') and (4"), M is 2.5 times or less, and T is 1.3 to 3 times). The stretching ratio (M) in the MD direction, which is performed before gear stretching, is preferably 2.5 times or less, more preferably 2 times or less.

Further, in order to prevent tearing or pinholes during gear stretching, the film may be preheat-treated at room temperature to 80 ° C. After stretching the film, if necessary, a heat setting treatment may be performed in order to stabilize the form of the obtained aperture. As the heat setting treatment, at a temperature equal to or higher than the softening point of the resin and lower than the melting point,
A method of performing heat treatment for 0.1 to 100 seconds may be used.

The porous film / nonwoven fabric composite sheet of the present invention produced as described above has a thickness of 150 to 250 μm.
m, and the basis weight is 30 to 60 g / m ² . In this range, the composite sheet is not easily torn, the raw material cost is appropriate, and the texture is not deteriorated (feeling stiff).

The moisture permeability, air permeability and water resistance of the porous film / nonwoven fabric composite sheet are measured, for example, when used in a disposable diaper, a sanitary napkin backsheet, or when used in a medical gown. Affect.
The porous film / nonwoven fabric composite sheet of the present invention has both high moisture permeability (that is, high moisture permeability), high air permeability (that is, high air permeability), and high water pressure (that is, high water resistance). The moisture permeability of the porous film / nonwoven fabric composite sheet of the present invention is 40 ° C. and 60% according to JIS Z0208.
RH (relative humidity), the moisture permeability measured by the method specified in the conditions of the pure water method is at least 3000 g / m ² · 24 hr
It is. As for the air permeability, the air permeability measured by the method specified in JIS P8117 is 500 seconds / 100 cc or less. The water pressure resistance is 1700 mmA, as measured by the method corresponding to JIS L1072A method (low water pressure method).
q or more. Also, the tear strength in the MD direction (JIS K
7128) is at least 400 kg / mm or more;
Has sufficient strength. More preferably at least 500
kg / mm or more.

The porous film / nonwoven fabric composite sheet of the present invention having such characteristics is a composite of a porous film having high moisture permeability and exhibiting good tear strength and a nonwoven fabric which is bulky, flexible and excellent in touch. In addition, the productivity is good. Therefore, disposable diapers, sanitary napkins,
Sanitary materials such as medical gowns, body fluid absorbing pads, bed sheets, medical materials such as surgical gowns, base materials for hot compresses, clothing materials such as jumpers and raincoats, wallpaper, roof waterproof materials, house wraps and other construction materials Material, desiccant, dehumidifier, deoxidizer, insect repellent, disposable warmer, freshness-keeping packaging, food packaging and other packaging materials, and battery separators. In particular, it can be suitably used as a backsheet or medical gown of sanitary materials represented by disposable diapers, sanitary napkins and the like.

[0052]

EXAMPLES The present invention will be described in more detail with reference to the following examples. Note that the present invention is not limited to these examples. The melt flow rate (hereinafter referred to as MFR), moisture permeability, air permeability, tensile strength and tensile elongation, film thickness, MD direction tear strength, gear stretch ratio, water pressure resistance, bristles and softness shown in the examples, The soft feeling was measured or evaluated by the following method.

(1) MFR (g / 10 min) A load 2 was obtained by the method specified in ASTM D1238.
160 g, temperature 19 in case of polyethylene resin
The measurement was performed at 0 ° C. and at a temperature of 230 ° C. for a polypropylene-based resin.

(2) Moisture Permeability (g / m ² · 24 hr) Ten samples were taken from the obtained porous film / nonwoven fabric composite sheet by a method specified in JIS Z0208 (pure water method), and the temperature was 40 ° C. At a relative humidity of 60%, the amount of moisture permeation for 24 hours was measured, and the average value was calculated.

(3) Air permeability (sec / 100 cc) 100 m from the obtained porous film / nonwoven fabric composite sheet
Twenty mx100 mm square samples were sampled at 5 cm intervals, and the air permeability of each sample was measured with an Oken-type air permeability meter, and the average value was calculated and used as the measured value.

(4) Tensile test (tensile strength N / 25 m
m, tensile elongation%) According to JIS P8113, a sample of 25 mm (width) × 150 mm (length) in MD direction and TD direction was used.
Ten pieces were sampled from each of the 0 locations, and using a Tensilon tensile tester, the distance between the chucks was 50 mm and the tensile speed was 200.
The tensile strength and tensile elongation were measured under the condition of mm / min, and the average value of the measured data was calculated. The temperature at the time of measurement was 2
The temperature was 3 ± 2 ° C.

(5) Thickness of Composite Sheet (μm) Ten samples of 10 cm in the MD direction and 10 cm in the TD direction were collected, and five points were measured at intervals of 3 cm per sheet, and a total of 50 measurement points were measured with a thickness measuring machine (PEACOCK). Company, UP
The thickness was measured using RIGHT DIAL GUAGE No. 25), and the average value was calculated.

(6) MD direction tear strength (kg / mm) The obtained porous film / nonwoven fabric composite sheet was collected and
50m in the MD direction based on IS K7128
Ten samples of m (width) × 150 mm (length) are collected from ten locations each, and a cut of 75 mm is made in the MD direction at the position of 25 mm at the center of the width. The two cut ends were measured by pulling each other in the 180 ° direction. 50mm between chucks, 200mm / m tensile speed
The determination was performed under the condition of “in”, and the average value of the measured data was calculated. The temperature during the measurement was 23 ± 2 ° C.

(7) Gear Stretching Magnification (times) B / B0 was calculated assuming B0 as the film width before gear stretching and B as the film width after gear working.

(8) Water pressure resistance (mmAq) This was carried out according to JIS L1072A method (low water pressure method).
Four test pieces of about 15 × 15 cm were collected at a time and attached to a water resistance tester (manufactured by Tester Sangyo Co., Ltd.) so that the surface of the test piece was exposed to water. The test piece was raised at a rate of ± 3 cm / min, and water pressure was applied to the test piece. The water level when water leaked from three places on the opposite side of the test piece was measured, and the water pressure resistance was determined from the pressure at that time.

(9) TD Bend / Softness (mm) Ten samples of 25 mm (width, MD direction) × 300 mm (length, TD direction) were collected based on JIS L1018.
It was measured by the 45-degree cantilever method, and the average value was used as the measured value.

(10) Soft Feeling (Tactile Feeling) A touch test was performed by five evaluators in comparison with the composite sheet of Comparative Example 1 and evaluated according to the following criteria. ：: Five out of five persons judged to be soft. Δ: 2 to 4 out of 5 persons judged to be soft. ×: One or less out of five persons judged to be soft.

(11) Pinholes and presence or absence of tears The obtained composite sheet was 300 mm wide and 50 mm long.
The range of m was the observation range. Place the composite sheet in the foreground,
Place the light source behind and visually check the pinhole (1m in size)
m or less) and tearing (thickness exceeding 1 mm) were observed and evaluated according to the following criteria. ：: No pinhole or tear was observed. ×: Pinholes or tears are observed.

(Comparative Example 1) Linear low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L,
Density: 0.920 g / cm ³ , melt flow rate:
2.1 g / 10 min) 38.4 parts by weight, low density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason F967, density: 0.918 g / cm ³ , melt flow rate: 1.
0 g / 10 minutes) 1.6 parts by weight of calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40)
After mixing 60 parts by weight (average particle diameter: 1.0 μm) and 1 part by weight of calcium stearate with a tumbler mixer, the mixture was uniformly kneaded at 200 ° C. using a tandem extruder and processed into pellets. The pellets were melt-formed at 240 ° C. using an extruder equipped with a T-die to form a 30 μm thick film.

On both sides of this film, a polyolefin-based hot melt adhesive (JM-606 manufactured by Nippon Fuller Co., Ltd.) was used.
4) Apply 1.5 g / m coating amount by curtain spray method
² and a spunbond nonwoven fabric having a basis weight of 20 g / m ² formed using a propylene homopolymer having an MFR of 60 g / 10 min was bonded to both surfaces of the film at a processing speed of 100 m / min. Table 1 shows various measurement results of the film / nonwoven fabric composite sheet.

(Example 1) The composite sheet obtained in Comparative Example 1 was subjected to a gear pitch (W) of 2.5 mm and a gear depth (H) of 6
mm (H / W = 2.40) using a gear roll, the degree of meshing (V) was set to 2.5 mm, gear stretching was performed in the TD direction at normal temperature (processing speed: 20 m / min), and the composite sheet thickness was 225 μm. A porous film / nonwoven fabric composite sheet having a basis weight of 49.1 g / m ² was obtained. The gear stretching ratio was 1.4 times. Table 1 shows various measurement results of the obtained porous film / nonwoven fabric composite sheet.

(Example 2) Gear stretching was performed in the same manner as in Example 1 except that the degree of engagement of the gear roll was changed to 3.0 mm, and the composite sheet was 196 µm thick and had a basis weight of 42.8 g / g.
to obtain a porous film, nonwoven fabric composite sheet m ^2. The gear stretching ratio was 1.6 times. Table 1 shows various measurement results of the obtained porous film / nonwoven fabric composite sheet.

Comparative Example 2 Gear stretching was carried out in the same manner as in Example 1 except that the degree of engagement of Kearol was changed to 4.0 mm, and the composite sheet was 185 μm thick and had a basis weight of 40.2 g / g.
to obtain a porous film, nonwoven fabric composite sheet m ^2. The gear stretching ratio was 2.2 times. Table 1 shows various measurement results of the obtained porous film / nonwoven fabric composite sheet.

[0069]

[Table 1]

[0070]

The porous film provided by the present invention
The nonwoven fabric composite sheet is composed of a porous film having high moisture permeability and exhibiting good tear strength, and a nonwoven fabric having a bulky feeling and being flexible and excellent in touch, and has good productivity. Therefore, it is suitably used in the fields of sanitary materials, medical materials, clothing materials, building materials, packaging materials, and the like.
In particular, it can be suitably used for disposable diapers, sanitary napkin backsheets, and medical gowns.

[Brief description of the drawings]

FIG. 1 is an example of a partial cross-sectional view of a gear roll during gear extension according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 upper gear 2 lower gear 3 porous film / nonwoven fabric composite sheet H gear depth V gear roll engagement degree W gear pitch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) D04H 3/00 A61F 13/18 320 3/16 A41B 13 / 02F // A61F 5/44 (72) Invention Person Haruki Nagaoka 1 Asahi-cho, Yokkaichi-shi, Mie F-term within Mitsui Chemicals Co., Ltd. (reference) QC03 QG01 QG15 QG18 4L047 AA14 BA09 BA23 BB02 CA06 CB08 CC03

Claims (14)

[Claims] 1. A composite sheet comprising a resin composition containing 25 to 70% by weight of a polyolefin resin and 75 to 30% by weight of an inorganic filler and an inelastic nonwoven fabric bonded to one or both sides of a film by a gear stretching method. A method for producing a porous film / nonwoven fabric composite sheet, characterized in that it is stretched in a direction perpendicular to the machine axis direction to be porous. 2. The porous film according to claim 1, wherein the gear stretching method is a method in which the composite sheet is meshed with at least a pair of gear rolls in which a concave portion and a convex portion are geared. -A method for producing a nonwoven fabric composite sheet. 3. The porous film / nonwoven fabric composite sheet according to claim 2, wherein the gear roll satisfies the following equation (1) as a relationship between a gear pitch (W) and a gear depth (H). Production method. H / W ≧ 1 (1) (W is 1 to 5 mm) 4. The degree of engagement (V) of said pair of gear rolls.
And the gear pitch (W) satisfies the following equation (2), and the degree of engagement (V) and the gear depth (H) of the pair of gear rolls satisfies the following equation (3). Item 4. The method for producing a porous film / nonwoven fabric composite sheet according to Item 3. V ≦ 1.5W (2) V ≦ H (3) (W is 1 to 5 mm) 5. The porous film / nonwoven fabric composite sheet according to claim 2, wherein the stretching of the composite sheet by the gear stretching method is performed at a temperature from room temperature to 80 ° C. of the gear roll. Manufacturing method. 6. The porous film / nonwoven fabric composite sheet according to claim 1, wherein a stretching ratio (T) of the composite sheet by the gear stretching method is 1.3 to 3 times. Manufacturing method. 7. The porous film according to claim 6, wherein the film made of the resin composition is a stretched film stretched in a machine axis direction at a stretch ratio (M) satisfying the following equation (4). Manufacturing method of film / nonwoven fabric composite sheet. M ≦ 4 / T (4) (where T is 1.3 to 3 times the stretching ratio of the composite sheet by the gear stretching method) 8. The porous film according to claim 1, wherein the polyolefin resin forming the resin composition is at least one selected from linear low-density polyethylene and low-density polyethylene. -A method for producing a nonwoven fabric composite sheet. 9. The composite film according to claim 1, wherein the inorganic filler is at least one compound selected from calcium carbonate and barium sulfate. Method. 10. The method for producing a porous film / nonwoven fabric composite sheet according to claim 1, wherein the inelastic nonwoven fabric is a spunbonded nonwoven fabric made of an olefin polymer. 11. The tear strength in the machine axial direction is 400 kg / m.
m or more, moisture permeability 3000 g ^/ m 2 · 24 hr or more, air permeability of 500 sec / 100 cc or less, water pressure resistance 1700m
2. The device has a thickness of 150 to 250 μm and a basis weight of 30 to 60 g / m ^2.
11. The method for producing a porous film / nonwoven fabric composite sheet according to any one of items 10 to 10. 12. A tear strength in the machine axis direction of 400 k obtained by the production method according to any one of claims 1 to 11.
g / mm or more, moisture permeability 3000g ^/ m 2 · 24hr or more, air permeability of 500 sec / 100 cc or less, and a water pressure resistance of 17
Not less than 00 mmAq and a thickness of 150 to 250 μ
m, a perforated film / nonwoven fabric composite sheet having a basis weight of 30 to 60 g / m ² . 13. The composite sheet according to claim 12, which is a backsheet of a sanitary material including a disposable diaper and a sanitary napkin. 14. A medical gown comprising the porous film / nonwoven fabric composite sheet according to claim 12.