JP6350222B2 - Moisture permeable film and moisture permeable film laminate - Google Patents

Description

  The present invention relates to a moisture permeable film and a moisture permeable film laminate, and in particular, work clothes for preventing oil stains, protective clothes for preventing chemicals, protective clothes for preventing infectious diseases, protective clothes for emergency medical care, and surgical use. It can be suitably used as clothing such as clothing.

  Conventionally, a moisture-permeable film made of a resin composition containing a polyolefin-based resin and an inorganic filler is peeled at the interface between the resin and the inorganic filler by stretching, and the innumerable voids that are generated form communication holes. Therefore, the liquid does not permeate while having high air permeability and moisture permeability. From the point of satisfying this conflicting performance, it is used for sanitary materials such as paper diapers, back sheets for feminine hygiene products, waterproof films, etc., and prevents stuffiness, skin irritation and liquid leakage when worn.

  However, in recent years, in addition to sanitary materials, the use of clothing as work clothes for preventing oil stains, protective clothing for preventing chemicals, protective clothing for preventing infectious diseases, protective clothing for emergency medical care, and clothing for surgical operations has increased. However, it is required to have appropriate moisture permeability, mechanical strength, and extremely high water resistance and liquid permeability (artificial blood barrier property, virus barrier property).

  However, in order to satisfy moisture permeability, mechanical strength, and water resistance performance, the moisture permeable film for these applications uses a special thermoplastic elastomer, fluorine resin, etc. in addition to making the basis weight larger and thicker than necessary. There are many cases where a special coating is applied to a moisture permeable film or a non-woven fabric, or a non-porous film not using an inorganic filler is used. However, the use of a special resin may cause a decrease in production efficiency such as burns in an extruder or a die, and the cost becomes very expensive, making it difficult to use as clothing. There was a problem.

  In response to the above problems, by changing from low-density polyethylene (LDPE), which has been mainly used so far, to high-density polyethylene (HDPE), polypropylene (PP), etc., an excellent machine without reducing production efficiency A method has been devised in which strength and water-resistant strength are obtained, and the basis weight and cost are reduced. However, since the texture of the moisture permeable film is reduced, or a large number of huge holes or pinhole defects are generated due to an increase in stretching unevenness, the water resistance and the liquid resistance may be lowered.

  In order to improve this, a high-strength polyolefin resin such as high-density polyethylene and polypropylene is used, but raw material selection, compounding design, and manufacturing method that do not cause huge voids and pinhole defects due to stretching unevenness etc. I had to consider.

  As a technique for improving these, Japanese Patent Application Laid-Open No. 2002-249622 (Patent Document 1) discloses a moisture-permeable film excellent in high mechanical strength, constant pitch printability and flexibility.

JP 2002-249622 A

  However, the porous film disclosed in the above-mentioned patent document 1 includes, as clothing, work clothes for preventing oil stains, protective clothing for preventing chemicals, protective clothing for preventing infectious diseases, protective clothing for emergency medical care, and clothing for surgical operations. When it is used, the moisture permeation performance is insufficient, and the water resistance and liquid permeation resistance which are contradictory are also insufficient.

  This invention is made | formed in view of the said subject, and it aims at providing the moisture-permeable film which is excellent in the water pressure which opposes and has sufficient mechanical strength, while having the outstanding moisture permeability.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the problem can be solved by the following invention. That is, the present invention provides the following moisture-permeable films.

The present invention is a moisture permeable film comprising a resin composition comprising at least (A) a high-density polyethylene, (B) a linear low-density polyethylene resin component, (C) an inorganic filler, and (D) a plasticizer. ,
The (A) high-density polyethylene has a density of 0.940 to 0.970 g / cm ³ , a melt flow rate (MFR) of 0.1 to 5 g / 10 min,
The (B) linear low-density polyethylene has a density of 0.900 to 0.939 g / cm ³ and a melt flow rate (MFR) of 0.1 to 5 g / 10 min.
The content of (A) high-density polyethylene in 100 parts by mass of the resin component is 20 to 60 parts by mass, and the content of (B) linear low-density polyethylene is 40 to 80 parts by mass.
The resin composition contains 100 to 200 parts by mass of the (C) inorganic filler and 1 to 20 parts by mass of the plasticizer (D) with respect to 100 parts by mass of the resin component.
A moisture-permeable film characterized by having a water pressure resistance of 20 kPa or more and a oozing area of less than 10% with a test solution having an air permeability of 100 to 5,000 seconds / 100 mL, a surface tension of 35 mN / m.

  The moisture-permeable film according to the present invention is lightweight and has excellent moisture permeability, water resistance, liquid resistance, and mechanical strength, so that not only sanitary materials such as disposable diapers, feminine sanitary products, moisture-permeable waterproof sheets, As clothing, it can be suitably used for work clothes for preventing oil stains, protective clothing for preventing chemicals, protective clothing for preventing infectious diseases, protective clothing for emergency medical care, clothing for surgical operations, and the like.

It is explanatory drawing of the evaluation method of a oozing area.

[Moisture permeable film]
The moisture-permeable film of the present invention comprises a resin composition comprising at least (A) a high-density polyethylene, (B) a resin component comprising linear low-density polyethylene, (C) an inorganic filler, and (D) a plasticizer. The (A) high-density polyethylene has a density of 0.940 to 0.970 g / cm ³ , a melt flow rate (MFR) of 0.1 to 5 g / 10 min, and the (B) linear low The density polyethylene has a density of 0.900 to 0.939 g / cm ³ , a melt flow rate (MFR) of 0.1 to 5 g / 10 min, and the (A) high-density polyethylene in 100 parts by mass of the resin component. The content is 20 to 60 parts by mass, the content of the (B) linear low density polyethylene is 40 to 80 parts by mass, and the resin composition is based on 100 parts by mass of the resin component. (C) 100 to 200 parts by mass of an inorganic filler, 1 to 20 parts by mass of the (D) plasticizer, a test solution having an air permeability of 100 to 5,000 seconds / 100 mL and a surface tension of 35 mN / m. The water pressure resistance is 20 kPa or more and the oozing area is less than 10%.

((A) high density polyethylene)
(A) High-density polyethylene is a component that imparts excellent mechanical properties while reducing the thickness and weight of the moisture-permeable film of the present invention, and the density is 0.940 to 0.970 g / cm ³ . 0.945 g / cm ³ or more or 0.965 g / cm ³ or less is preferable. Here, the density is a density measured by a pycnometer method (JIS K7112 B method), and the methods for measuring the density of other resins are the same.

(A) As high density polyethylene, for example, ethylene homopolymer, or ethylene- (propylene), ethylene- (1-butene), ethylene- (1-hexene), ethylene- (4-methyl-1-pentene), And an ethylene- (α-olefin) copolymer such as ethylene- (1-octene) can be used.
Examples of the polymerization catalyst used for polymerization of these polymers include known Ziegler-type and Philips-type multisite catalysts, zirconocene, titanocene, hafnocene (generally called metallocene) and other Kaminsky catalysts, and post-metallocene catalysts. And highly active single site catalysts.

  (A) The melting point of the high-density polyethylene is preferably 125 to 150 ° C, more preferably 130 ° C or higher or 140 ° C or lower, from the viewpoints of making the film thinner and lighter and obtaining excellent mechanical properties. Here, the melting point was determined by using a differential scanning calorimeter (DSC) to heat about 10 mg of a sample from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min and holding at 200 ° C. for 1 minute, and then cooling rate The crystal melting peak temperature (Tm) obtained from the thermogram measured when the temperature was lowered to −40 ° C. at 10 ° C./min and again raised to 200 ° C. at a heating rate of 10 ° C./min. The method for measuring the melting point is the same.

  (A) The melt flow rate (MFR) of the high-density polyethylene is 0.1 to 5 g / 10 min from the viewpoint of reducing the film thickness and weight, and obtaining excellent mechanical properties, and 0.5 g / 10 min or more or 3 g / 10 min or less is preferable. By setting the MFR to 0.1 g / 10 min or more, the moldability of the moisture-permeable film can be sufficiently maintained, and by setting the MFR to 5 g / 10 min or less, the occurrence of stretching unevenness is suppressed, and sufficient water resistance and It can have liquid permeation resistance. Here, MFR is a value measured according to JIS K7219, the measurement conditions are 190 ° C. and 2.16 kg load, and the MFR measurement methods for other resins are the same.

  Content of (A) high density polyethylene in 100 mass parts of resin components is 20-60 mass parts, and 25 mass parts or more or 50 mass parts or less are preferable. This suppresses the occurrence of stretching unevenness and necking while ensuring excellent moisture permeability, water resistance, liquid resistance and mechanical strength.

((B) linear low density polyethylene)
(B) a linear low density polyethylene is a resin component as a base material of the moisture-permeable film of the present invention, the density is ^{0.900~0.939g / cm 3, 0.905g / cm} 3 or more, or 0.929 g / cm ³ or less is preferable.

(B) As the linear low density polyethylene, for example, ethylene homopolymer or ethylene- (propylene), ethylene- (1-butene), ethylene- (1-hexene), ethylene- (4-methyl-1- A pentene) and an ethylene- (α-olefin) copolymer such as ethylene- (1-octene) can be used.
Examples of the polymerization catalyst used for polymerization of these polymers include known Ziegler-type and Philips-type multisite catalysts, zirconocene, titanocene, hafnocene (generally called metallocene) and other Kaminsky catalysts, and post-metallocene catalysts. And highly active single site catalysts.

  The melting point of the linear low density polyethylene (B) is preferably 100 to 125 ° C from the viewpoint of reducing the film thickness and weight and obtaining excellent mechanical properties, and is 105 ° C or higher or 123 ° C or lower. Is more preferable.

  (B) The melt flow rate (MFR) of the linear low density polyethylene is 0.1 to 5 g / 10 min from the viewpoint of reducing the film thickness and weight and obtaining excellent mechanical properties, and 0.5 g / 10 min or more or 3 g / 10 min or less is preferable. When the MFR is 0.1 g / 10 min or more, the moldability of the moisture-permeable film can be sufficiently maintained, and when the MFR is 5 g / 10 min or less, sufficient strength can be obtained.

  Content of (B) linear low density polyethylene resin in 100 mass parts of resin components is 40-80 mass parts, and 50 mass parts or more or 75 mass parts or less are preferable. This suppresses the occurrence of stretching unevenness and necking while ensuring excellent moisture permeability, water resistance, liquid resistance and mechanical strength.

  In addition to the resin component, other resins may be added depending on the purpose of use. For example, high-pressure low-density polyethylene (LDPE) may be added to improve moldability. The content of the LDPE is preferably 2 to 30 parts by mass with respect to 100 parts by mass of the resin component.

((C) inorganic filler)
(C) The inorganic filler is a component that contributes to the formation of pores, and is a component that imparts breathability, moisture permeability, and liquid resistance to the moisture permeable film.
(C) As inorganic filler, fine particles such as calcium carbonate, calcium sulfate, barium carbonate, barium sulfate, titanium oxide, magnesium hydroxide, silicon oxide, aluminum oxide, talc, clay, kaolinite, montmorillonite, hydrotalcite, And minerals, and these can be used alone or in combination. Among these, calcium carbonate and barium sulfate are preferable because they are excellent in pore development, high versatility, low price, and abundant brands.

  (C) The average particle diameter of the inorganic filler is preferably 0.5 to 5 μm, more preferably 0.7 μm or more or 3 μm or less. By setting the average particle size to 0.5 μm or more, it is preferable because poor dispersion and secondary aggregation of the inorganic filler are suppressed, and stretching unevenness and defects due to the generation of pinholes and blisters are reduced. On the other hand, when the average particle diameter is 5 μm or less, the generation of huge pores is suppressed during the production of the moisture-permeable film, and sufficient mechanical strength, water resistance, and liquid resistance can be obtained.

Further, (C) the inorganic filler is preferably surface-treated with a fatty acid. By subjecting the surface treatment with a fatty acid, the (C) inorganic filler can easily become familiar with the resin component, and can sufficiently have dispersibility and mixing properties.
The type of the fatty acid is not particularly limited, but higher fatty acids such as stearic acid and palmitic acid are preferable because they can be obtained at low cost.

  Content of (C) inorganic filler with respect to 100 mass parts of resin components is 100-200 mass parts, 110 mass parts or more or 170 mass parts or less are preferable, 120 mass parts or more or 150 mass parts or less are more preferable. (C) When content with an inorganic filler exists in the said range, it can have sufficient mechanical strength, water resistance, and liquid permeability.

((D) Plasticizer)
(D) A plasticizer is a component which contributes to the improvement of the workability at the time of making a resin composition into a film shape.
(D) As a plasticizer, for example, castor oil such as castor oil, hydrogenated castor oil, hardened castor oil, dehydrated castor oil, higher fatty acid, higher fatty acid ester, higher fatty acid amide, metal soap, higher alcohol, petroleum jelly, paraffin wax, glycerin fatty acid ester , Polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, aromatic ester, aromatic amide and polyether, low molecular weight polymer (oligomer) such as polyester, etc., and these may be used alone or in combination Can do.

  In the present invention, castor oils such as castor oil, hydrogenated castor oil, hydrogenated castor oil, and dehydrated castor oil are preferred from the viewpoint of obtaining a moisture-permeable film having excellent water repellency, water resistance, and liquid permeability. Hardened castor oil mainly composed of triglyceride composed of octadecanoic acid and glycerin is more preferably used. Hardened castor oil is in the form of powder with a melting point of 80-90 ° C, so it is easy to handle during production, and it gives excellent plasticity and extensibility to the resin component, so the resin composition is formed into a film. The workability at the time of is obtained.

  Content of (D) plasticizer with respect to 100 mass parts of resin components is 1-20 mass parts, 3 mass parts or more or 15 mass parts or less are preferable, and 5 mass parts or more or 12 mass parts or less are more preferable. (D) When the content of the plasticizer is within the above range, handling during production is easy, and since the resin component has excellent plasticity and extensibility, the resin composition is formed into a film shape. In addition, the workability during the process is obtained, and the water resistance and liquid permeation resistance are obtained.

  In addition to the components (A) to (D), a compatibilizer, a processing aid, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antiblocking agent, and an antifogging agent are used depending on the purpose of use. Agents, matting agents, surfactants, antibacterial agents, deodorants, antistatic agents, colorants and pigments may be added to the resin composition. Among these, a heat stabilizer is preferably used, and the content of the heat stabilizer is preferably 0.01 to 3 parts by mass with respect to 100 parts by mass of the resin composition.

[Physical properties of moisture-permeable film]
The moisture-permeable film of the present invention has excellent air permeability and has an air permeability of 100 to 5,000 seconds / 100 mL. When the air permeability is 100 seconds / 100 mL or more, it can have sufficient water resistance and liquid resistance, and when the air permeability is 5,000 seconds / 100 mL or less, sufficient communication can be achieved. Suggests having. The air permeability is preferably 200 seconds / 100 mL or more or 3,000 seconds / 100 mL or less, more preferably 400 seconds / 100 mL or more or 2,000 seconds / 100 mL or less.

  Here, the air permeability is the number of seconds in which 100 mL of air measured according to the method defined in JIS P8117: 2009 (Gurley tester method) passes through a piece of paper. For example, the air permeability measuring device (Asahi Seiko) It is possible to measure using a Oken type air permeability measuring machine EGO1-55 type). In the present invention, the sample was randomly measured at 10 points, and the arithmetic average value was taken as the air permeability.

The moisture-permeable film of the present invention has a water pressure resistance of 20 kPa or more, preferably 30 kPa or more, more preferably 40 kPa or more, with a test liquid having a surface tension of 35 mN / m. Because the water pressure resistance of the test liquid with a surface tension of 35 mN / m is 20 kPa or more, when used as clothing such as protective clothing, the wearer will not be contaminated by liquids containing harmful chemicals, viruses or pathogens. Can protect. Moreover, although it does not specifically limit about an upper limit, 150 kPa or less is preferable from a viewpoint of balance with other physical properties.
In order to set the water pressure resistance to 20 kPa or more, the communication hole is a labyrinth by adjusting the content of (A) high-density polyethylene contained in the resin composition or by making it microporous under specific stretching conditions. This is achieved because the test solution having a low surface tension does not ooze out to the back surface.

Here, the water pressure resistance is a value obtained by the following measuring method.
For the test solution with a surface tension of 35 mN / m used in this measurement, refer to the surface tension data of 2-propanol / water system in J. Chem. Eng. Data, 40 (1995), 611, Table. 4 by G. Vazquez et al. It was.
As a method for adjusting the test solution, 85.0 parts by mass of distilled water (manufactured by Wako Pure Chemical Industries, Ltd.), 15.0 parts by mass of 2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.), and Blue No. 1 pigment (Wako Pure Chemical Industries, Ltd .; Brilliant Blue FCF) A 15 mass% aqueous alcohol solution obtained by stirring for 5 minutes until uniformly dissolving and dispersing 0.10 parts by mass was used as a test solution. At this time, it was confirmed by a pendant drop type surface tension measuring device that the surface tension was in the range of 35.0 ± 1.0 mN / m.
As a method for measuring the water pressure resistance, the test liquid was filled in a cylinder part of a measuring device based on JIS L1092 B method (high water pressure method). Under an environment of 20.0 ± 3.0 ° C., the device cylinder handle was gradually turned up and raised at a speed of 50 kPa / min, and the pressure when blue water droplets oozed out at three points was taken as the water pressure resistance.

The moisture-permeable film of the present invention has a oozing area of less than 10% and preferably less than 5%. When the oozing area is less than 10%, sufficient protective performance can be obtained when used as clothing.
When a certain load is applied to the test solution, the pores and the communication holes of the moisture permeable film are wetted and penetrated, so that the moisture penetrates to the back surface of the moisture permeable film. Depending on the oozing area, it can be seen that the moisture permeable film does not have huge pores, or the communication holes are bent, and the liquid permeability is high.
In order to make the exudation area less than 10%, it can be achieved by adjusting the content of (A) high-density polyethylene contained in the resin composition or by making it microporous under specific stretching conditions. Can do.

Here, the oozing area is a value obtained by the following measurement method.
To 99.8 parts by weight of distilled water, 0.2 part by weight of a cationic surfactant (“Elegan 263-40 (trade name)”, manufactured by NOF Corporation), Red No. 40 pigment (Wako Pure Chemical Industries, Ltd.) )) 0.30 part by mass was gradually added, stirred for 1 hour, and uniformly dissolved and dispersed to prepare a red test solution.
As shown in FIG. 1, a filter paper (“FILTER PAPER No. 2 (trade name)”, manufactured by Advantech Co., Ltd., diameter: in a constant temperature and humidity room adjusted to a temperature of 23 ° C. and a relative humidity of 50%. 70mm), a breathable film cut into a 100mm x 100mm square, and a commercially available kitchen paper cut into a 70mm x 70mm square are layered, and 2.0mL of the test solution is gently dropped with a dropper on the center of the kitchen paper. did. After dripping, a resin plate (diameter: 60 mm, thickness: 5 mm) was layered on the kitchen paper, and a weight of 2 kg was placed thereon and left for 30 minutes. The area of the filter paper colored in red due to the bleeding of the test liquid (colored portion shown in the filter paper after the test in FIG. 1) was measured, and the ratio of the area in the entire pressurized filter paper was calculated. The value is the exudation area.

The basis weight of the moisture-permeable film of the present invention is preferably ^{10~50g / m 2, 12g / m} 2 or more, or 40 g / m ² or less, and still more preferably 15 g / m ² or more, or 30 g / m ² or less. When the basis weight is within the specified range, comfort can be sufficiently achieved when used as clothing.
Here, the basis weight was determined by measuring the mass of a sample (machine flow direction (MD): 250 mm, vertical direction (TD): 200 mm) with an electronic balance and multiplying the numerical value by 20 as the basis weight.

Moisture permeability 1,000~15,000g / (m ² · 24h) are preferred moisture-permeable film of the present ^{invention, 2,000g / (m 2 · 24h} ) or more or 12,000g / (m ² · 24h) or less Is more preferably 3,000 g / (m ² · 24 h) or more, or 10,000 g / (m ² · 24 h) or less. When the moisture permeability is 15,000 g / (m ² · 24 h) or less, the water resistance is suggested. In addition, the moisture permeability is 1,000 g / (m ² · 24h) or more, which suggests that the pores have sufficient communication.
Here, the moisture permeability conforms to the conditions of JIS Z0208 (moisture-proof packaging material moisture permeability test method (cup method)). 15 g of calcium chloride was used as a hygroscopic agent, and measurement was performed in a constant temperature and humidity environment at a temperature of 40 ° C. and a relative humidity of 90%. Samples were randomly measured at two points, and the arithmetic average value was obtained.

The tensile strength at break in the machine direction (MD) of the moisture-permeable film of the present invention is preferably 7 N / 25 mm or more, and more preferably 10 N / 25 mm or more. When the tensile breaking strength is 7 N / 25 mm or more, practically sufficient mechanical strength and flexibility can be ensured. Moreover, although it does not specifically limit about an upper limit, In view of stretchability, it is preferable that it is 30 N / 25mm or less.
Here, the tensile strength at break in the machine direction (MD) was prepared in accordance with JIS K7127 by preparing a sample cut into a length of 100 mm and a width of 25 mm under an environment of 23 ° C. and a relative humidity of 50% at a tensile speed of 200 m / It is the tensile strength at break when ruptured using a triple tensile tester under the conditions of min and the distance between chucks of 50 mm. In this invention, it was set as the arithmetic average value of the tensile fracture strength computed by measuring 3 times.

  Further, the moisture-permeable film of the present invention may have a single-layer structure depending on applications and purposes, and has a multilayer structure of two or more layers having at least one layer composed of the moisture-permeable film of the present invention. You may use as a wet film laminated body. In this case, the moisture permeable film of the present invention may be used in combination with a sheet made of another material such as another resin film, a flat yarn made of a synthetic resin, a textile, or a nonwoven fabric.

[Method for producing moisture-permeable film]
Next, although the manufacturing method of the moisture-permeable film of this invention is demonstrated, this invention is not limited only to the moisture-permeable film manufactured by this manufacturing method, The moisture-permeable film of this invention is the said resin composition. After melt-kneading the product, it is preferably formed into a film by the T-die method or the inflation method, and stretched to make it microporous.

The method for forming the film is not particularly limited, and a known method may be used.
First, it is preferable that components contained in the resin composition, that is, a resin component, an inorganic filler, a plasticizer, and various additives as necessary are mixed in a mixer and melt-kneaded using a kneader. Examples of the mixer include a tumbler mixer, a mixing roll, a Banbury mixer, a ribbon blender, a super mixer, and the like. Usually, the mixing is performed for about 5 minutes to 1 hour.

  As the kneader, a multi-screw kneader such as a different-direction twin-screw extruder or a same-direction twin-screw extruder can be used. By using a kneader, uniform dispersion and distribution of the resin composition can be promoted. Depending on the blending of the resin composition, for example, each component of the resin composition can be directly fed into the kneader without mixing by a mixer. The melting temperature at this time is preferably equal to or higher than the melting point of (A) high-density polyethylene, and more preferably equal to or higher than the temperature of 20 ° C. added to the melting point of (A) high-density polyethylene.

  The obtained resin composition is preferably pelletized once by a method such as strand cutting or die cutting in consideration of the production process, but can be directly formed into a thin film through a die as it is.

  There is no limitation in particular in the method of shape | molding a resin composition in a film form, A well-known method is applicable. For example, from the standpoint of production efficiency and cost, a method of molding the resin composition into a thin film by a molding method such as inflation, tubular, and T-die after melt extrusion is preferable.

The resin composition formed into a film in the step is preferably stretched 2.0 to 3.5 times at least in the temperature direction of 30 to 100 ° C. in the machine direction (MD). Since the pores are formed in the film of the resin composition by the stretching process and become microporous, a moisture-permeable film can be obtained.
As a method for forming pores in a film of the resin composition and making it microporous, a stretch-opening method is common, but the method is not limited. The stretching method may be either a uniaxial stretching method or a biaxial stretching method. For example, a known stretching method such as a biaxial stretching method such as a roll stretching method, a tenter method, a simultaneous method, and a sequential method may be applied. it can. In the present invention, it may be carried out at least once in the machine direction (MD) or twice or more in consideration of stretching unevenness and air permeability.

In the method for producing a moisture-permeable film, the stretching temperature is more preferably from 30 to 100 ° C, further preferably from 50 ° C to 85 ° C. By setting the stretching temperature to 30 ° C. or more, stretching unevenness is reduced, and water resistance and liquid permeation resistance are maintained. On the other hand, when the stretching temperature is 100 ° C. or lower, sufficient moisture permeability can be obtained.
The draw ratio is preferably 2.0 to 3.5 times, more preferably 2.5 times or more or 3.2 times or less. By setting the draw ratio to 2.0 times or more, stretching unevenness can be reduced, and sufficient moisture permeability and strength in the machine direction (MD) can be obtained. On the other hand, when the draw ratio is 3.5 or less, water resistance, liquid resistance, and generation of huge holes or pinhole defects are suppressed.

In the manufacturing method, by combining the stretching temperature and the stretching ratio within the above range, the moisture permeable film can be made thinner and lighter, and it has excellent air permeability, moisture permeability, mechanical properties in the machine direction flow, and resistance to permeation. Liquidity and heat resistance can be obtained in a well-balanced manner, and the conditions can be appropriately selected according to desired performance.
For example, as the draw ratio is increased, the air permeability is improved (the air permeability is reduced and the moisture permeability is increased), while the water resistance and the liquid permeability are liable to be lowered. Further, since the tensile elastic modulus and the tensile strength are increased, excellent mechanical properties in the production line can be obtained, while hardness, sharpness, and a feeling of tingling tend to be expressed. Further, as the draw ratio is decreased, water resistance and liquid permeation resistance tend to be improved, while air permeability tends to decrease. Further, since the tensile elastic modulus and the tensile strength are small, the touch is good and excellent wear comfort is obtained, while the mechanical properties tend to be lowered.
Further, the lower the stretching temperature, the easier the formation of pores and the more microporous, so that excellent air permeability is obtained, while water resistance and liquid permeation resistance tend to decrease. In order to obtain extremely excellent breathability, it is only necessary to lower the stretching temperature and increase the stretching ratio. On the other hand, when it is desired to lower the breathability, the stretching temperature is increased and the stretching ratio is decreased. Moreover, it is also possible to adjust by a combination of the stretching temperature and the stretching ratio.

  As a measure against heat shrinkage in the stretching direction of the moisture-permeable film, it is preferable to perform heat setting after the stretching step. Even if the moisture-permeable film that has undergone the heat setting process is stored for a long time as a roll-shaped roll, there is little elastic recovery, shrinkage and squeezing by heat, film sticking and blocking, and it can be processed without problems in the next process. The heat setting refers to suppressing the shrinkage of the product roll by heating the film in advance and causing the film to thermally shrink.

  As a heat setting method, for example, when a roll stretching method is adopted, a draw ratio ([unwinding side roll speed−winding side roll speed] / An example is a method in which the unwinding side roll speed is set to a negative number. Moreover, when employ | adopting the tenter extending | stretching method, the method of shrinking a film by heating a film in the tenter exit vicinity and making the clip width | variety of both ends narrower than the width | variety after extending | stretching is mentioned.

The heat setting temperature is preferably 70 to 120 ° C. If the heat setting temperature is 70 ° C. or higher, the film is sufficiently heat fixed, so that the shrinkage of the product roll can be suppressed, and if it is 120 ° C. or lower, the production trouble such as the film winding around the roll or tearing. Is less likely to occur.
The negative draw ratio is preferably -20 to -10%. When the negative draw ratio is within the above range, heat fixation can be performed without any trouble in production, and sufficient thermal dimensional stability can be obtained. These rolls are preferably made of a metal having a large heat capacity and a smooth chrome plating surface.
Note that, similarly to the stretching process, the heat setting may be divided into a plurality of times.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples.

(1) Air permeability According to said method, the air permeability was measured.
(2) Water pressure resistance According to the above method, the water pressure resistance was measured with a test solution having a surface tension of 35 mN / m.
(3) Exudation area According to the above method, the exudation area was calculated and evaluated according to the following criteria.
A: Exudation area is less than 5% B: Exudation area is 5% or more and less than 10% C: Exudation area is 10% or more and less than 30% D: Exudation area is 30% or more (4) Basis weight The basis weight was measured according to
(5) Moisture permeability The moisture permeability was measured according to the above method.
(6) Tensile breaking strength in the machine direction (MD) The tensile breaking strength was measured according to the above method.

[Examples 1 and 2]
Prepare the components of the resin composition shown in Table 1 below, put them into a Henschel mixer, mix and disperse for 5 minutes, and melt at a set extrusion temperature of 180 ° C using a same-direction twin screw extruder. A resin composition was obtained by kneading, and a compound pellet was obtained by a strand cut method. Using the obtained pellets, it was formed into a film using a single-screw extruder and an inflation die, and using a roll type longitudinal stretching machine at a stretching temperature of 70 ° C. and a stretching ratio of 3.0 times in the machine direction (MD The film was stretched once and then heat fixed and relaxed at 100 ° C. to obtain a moisture permeable film. The evaluation results of the obtained moisture-permeable film are shown in Table 2 below.

[Comparative Examples 1 and 2]
Prepare the components of the resin composition shown in Table 1 below, put them into a Henschel mixer, mix and disperse for 5 minutes, and melt at a set extrusion temperature of 180 ° C using a same-direction twin screw extruder. A resin composition was obtained by kneading, and a compound pellet was obtained by a strand cut method. Using the obtained pellets, it was formed into a film using a single screw extruder and an inflation die, and using a roll type longitudinal stretching machine at a stretching temperature of 60 ° C. and a stretching ratio of 2.5 times in the machine direction (MD The film was stretched once and then heat fixed and relaxed at 100 ° C. to obtain a moisture permeable film. The evaluation results of the obtained moisture-permeable film are shown in Table 2 below.

In Example 1 and Example 2, (A) High tensile strength can be obtained by stretching a film containing high-density polyethylene, and by making it microporous under specific stretching conditions, reduction in stretching unevenness is high. A moisture permeable film having a balance of moisture permeability, water resistance and liquid resistance was obtained.
On the other hand, in Comparative Example 1, since the resin composition did not contain (A) high-density polyethylene and the content of (C) inorganic filler was excessive, water resistance and liquid permeation resistance deteriorated. Further, a liquid polyester plasticizer was added in order to suppress stretching unevenness, but the water resistance and liquid permeation resistance were further deteriorated. Since Comparative Example 2 contains a large amount of (A) high-density polyethylene resin having an MFR exceeding 5.0 g / 10 min, not only the mechanical strength was inferior, but also stretching unevenness occurred, and the liquid permeation resistance was insufficient. It was.

  The moisture-permeable film of the present invention is lightweight, yet has excellent moisture permeability, water resistance, liquid resistance, and mechanical strength, so that it can be used in addition to sanitary materials such as disposable diapers, feminine hygiene products, and moisture-permeable waterproof sheets. Also, it should be used appropriately for disposable clothes such as work clothes for preventing oil stains, protective clothes for preventing chemicals, protective clothes for preventing infectious diseases, protective clothes for emergency medical care, and clothes for surgical operations. Can do.

Claims (8)

(A) a high-density polyethylene, (B) a resin component comprising a linear low-density polyethylene, (C) an inorganic filler, and (D) a moisture-permeable film comprising a resin composition containing at least a plasticizer,
The (A) high-density polyethylene has a density of 0.940 to 0.970 g / cm ³ , a melt flow rate (MFR) of 0.1 to 5 g / 10 min,
The (B) linear low-density polyethylene has a density of 0.900 to 0.939 g / cm ³ and a melt flow rate (MFR) of 0.1 to 5 g / 10 min.
The content of (A) high-density polyethylene in 100 parts by mass of the resin component is 20 to 60 parts by mass, and the content of (B) linear low-density polyethylene is 40 to 80 parts by mass.
The resin composition contains 100 to 200 parts by mass of the (C) inorganic filler and 1 to 20 parts by mass of the plasticizer (D) with respect to 100 parts by mass of the resin component.
A moisture-permeable film characterized by having an air permeability of 100 to 5,000 seconds / 100 mL, a water pressure resistance of 20 kPa or more with a test solution having a surface tension of 35 mN / m, and an exudation area of less than 10%.   The moisture-permeable film according to claim 1, wherein the inorganic filler (C) is surface-treated with a fatty acid.   The moisture-permeable film according to claim 1 or 2, wherein the (D) plasticizer is castor oil. 4. The moisture-permeable film according to claim 1, wherein the basis weight is 10 to 50 g / m ² and the moisture permeability is 1,000 to 15,000 g / (m ² · 24 h). .   The moisture-permeable film according to any one of claims 1 to 4, wherein the tensile strength at break in the machine direction (MD) is 7 N / 25 mm or more. The moisture-permeable film laminated body which has at least one layer which consists of a moisture-permeable film of any one of Claims 1 thru | or 5 . A garment using the moisture-permeable film laminate according to claim 6 . A method for producing a moisture permeable film according to any one of claims 1 to 5,
The manufacturing method of a moisture-permeable film characterized by including the process of extending | stretching a film-form resin composition 2.0 to 3.5 times within the temperature range of 30-100 degreeC in a machine direction (MD) .

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