JP6442876B2 - Breathable film - Google Patents

Description

  The present invention relates to a moisture permeable film.

  Conventionally, a moisture permeable film made of a resin composition containing a polyolefin resin and an inorganic filler is generally suitably used for sanitary materials such as paper diapers and back sheets for moisture permeable waterproofing such as physiological treatment articles. This moisture-proof film has moisture permeability and breathability by stretching the above resin composition and causing interfacial peeling between the resin and the inorganic filler to form innumerable voids (micropores). It is. When the moisture-proof film is used as a sanitary material, for example, a back sheet of a paper diaper, the following performance is required. First, moisture permeation and air permeability, and water resistance and liquid leakage resistance which are opposite to each other are required as performance for preventing stuffiness when wearing a paper diaper and preventing leakage of urine.

In addition, from the viewpoint of the manufacturing process, mechanical properties such as moderate strength in the machine flow direction, tensile elastic modulus, and tensile elongation are required for the moisture permeable film as important physical properties. The moisture-permeable film has the mechanical properties in the appropriate machine flow direction, that is, the appropriate rigidity and tensile strength, so that there is no elongation or distortion of the film during printing, slitting and winding, and excellent mechanical suitability in the production line is obtained. Because it is.
Furthermore, it is required as a very important performance that it is excellent in heat resistance to a hot melt adhesive sprayed at a high temperature and that the film is not broken and does not develop into a trouble in the production process. The moisture permeable and waterproof back sheet is generally manufactured by hot melt lamination between the nonwoven fabric and the moisture permeable film, but the hot melt adhesive is used by heating and melting at 100 to 200 ° C. is there.

  As a porous film having voids (micropores), at least one resin selected from high density polyethylene and polypropylene having a density of 0.930 to 0.975, linear low density polyethylene having a density of 0.905 to 0.930, and The thing containing a branched low density polyethylene in a predetermined ratio is proposed (for example, patent documents 1).

JP 2002-249622 A

  However, although this porous film has mechanical properties such as moderate moisture permeability, strength in the machine direction, and bending resistance, there is no description of it, so examinations regarding heat resistance and liquid leakage resistance are made. Is not at all. That is, this porous film could not be said to fully satisfy all the performances of air permeability, moisture permeability, liquid leakage resistance, mechanical properties in the machine flow direction, and heat resistance in a well-balanced manner.

  Moreover, when using a moisture-permeable film for sanitary materials, such as a paper diaper and a moisture-permeable waterproof back sheet, such as a sanitary treatment product, in addition to the above performance, it is required to be thin and lightweight. However, it is a performance that is contradictory to the thinning and light weight of the moisture-permeable film, and excellent liquid leakage resistance and mechanical properties in the machine flow direction. There is no situation.

  Therefore, the present invention has an object to provide a moisture-permeable film that is extremely thin and lightweight, and has excellent breathability and moisture permeability, and further has excellent mechanical properties in the machine direction flow, liquid leakage resistance, and heat resistance. And

  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, this invention provides the following moisture-permeable films and its manufacturing method.

1. (A) 20 to 80 parts by weight of a linear polyethylene resin of density 0.910~0.929g / cm ^3, (B) a density 0.930~0.965g / cm 10~40 parts by weight of polyethylene resin ³ , (C) 5 to 20 parts by mass of low-density polyethylene having a density of 0.910 to 0.929 g / cm ³ , and (D) 5 to 15 parts by mass of a propylene homopolymer, and 100 parts by mass of a resin component The resin component comprises (E) 100 to 200 parts by mass of an inorganic filler and (F) 1 to 20 parts by mass of a plasticizer, and has an air permeability of 50 to 5,000 seconds / A moisture-permeable film having 100 mL, a tensile elastic modulus in the machine flow direction of 60 to 150 MPa, a oozing area of less than 30%, and a heat resistant temperature of 160 ° C. or higher.
2. 2. A moisture-permeable film laminate having at least one layer comprising the moisture-permeable film as described in 1 above.

  ADVANTAGE OF THE INVENTION According to this invention, although it is very thin and lightweight, it can obtain the moisture permeability film excellent in air permeability and moisture permeability, and also in the mechanical characteristics of the machine direction flow, liquid leakage resistance, and heat resistance.

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

[Moisture permeable film]
Moisture-permeable film of the present invention, (A) 20 to 80 parts by weight of a linear polyethylene resin of density 0.910~0.929g / cm ^3, the (B) Density 0.930~0.965g / cm ³ 10 to 40 parts by mass of polyethylene resin, (C) 5 to 20 parts by mass of low-density polyethylene having a density of 0.910 to 0.929 g / cm ³ , and (D) 5 to 20 parts by mass of propylene homopolymer The resin component comprising 100 parts by mass of resin, and (E) 100 to 200 parts by mass of an inorganic filler and (F) 1 to 20 parts by mass of a plasticizer with respect to the resin component. Is 50 to 5,000 seconds / 100 mL, the tensile elastic modulus in the machine flow direction is 60 to 150 MPa, the oozing area is less than 30%, and the heat resistant temperature is 160 ° C. or higher.

((A) linear polyethylene resin)
The linear polyethylene resin (A) is a resin component that serves as a base material for the moisture-permeable sheet of the present invention, has a density of 0.910 to 0.929 g / cm ³ , and is particularly limited as long as it is linear. There is no. 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.
As the linear polyethylene resin of component (A), for example, ethylene homopolymer or ethylene- (propylene), ethylene- (1-butene), ethylene- (1-hexene), ethylene- (4-methyl-1) -Pentene) and ethylene- (α-olefin) copolymers 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 polyethylene resin as the component (A) is preferably 110 to 140 ° C. from the viewpoint of reducing the film thickness and weight 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, holding at 200 ° C. for 1 minute, and then cooling rate of 10 mg. The crystal melting peak temperature (Tm) (° C.) obtained from the thermogram measured when the temperature was lowered to −40 ° C. at a rate of ° C / min and again raised to 200 ° C. at a heating rate of 10 ° C./min. The method for measuring the melting point of the resin is the same.

  The melt flow rate (MFR) of the linear polyethylene resin (A) is preferably 0.1 to 20 g / 10 min, and more preferably 0.5 to 5 g / 10 min. If the MFR is 0.1 g / 10 min or more, the film can be made thinner and lighter, and if it is 20 g / 10 min or less, excellent mechanical properties can be obtained. 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.

As the linear polyethylene resin of component (A), one having a density of 0.910 to 0.929 g / cm ³ can be appropriately selected from commercially available products. Examples of commercially available products include “Novatech LL”, “Novatech C6” (manufactured by Nippon Polyethylene Co., Ltd.), “Neozex”, “Ultzex”, “Moretech”, “Evolue” (above, Prime Corporation). Polymer)).

  The content of the linear polyethylene resin (A) in 100 parts by mass of the resin component in the resin composition is 20 to 80 parts by mass from the viewpoint of reducing the film thickness and weight and obtaining excellent mechanical properties. 30 to 80 parts by mass is preferable, and 40 to 70 parts by mass is more preferable.

((B) polyethylene resin)
The component (B) polyethylene resin is a component that imparts excellent mechanical properties while reducing the thickness and weight of the moisture-permeable film of the present invention, and has a density of 0.930 to 0.965 g / cm ³ . Either linear or branched can be used.

(B) The resin material which comprises the polyethylene resin of a component can be suitably selected from what was illustrated as a resin material of the said (A) component.
The melting point of the polyethylene resin as the component (B) is preferably 110 to 140 ° C. from the viewpoint of reducing the film thickness and weight and obtaining excellent mechanical properties. The melt flow rate (MFR) is preferably from 0.1 to 20 g / 10 min, and from 0.5 to 5 g / 10 min, from the viewpoint of reducing the film thickness and weight and obtaining excellent mechanical properties. It is more preferable.
In addition, as the polyethylene resin as the component (B), a resin having a density of 0.930 to 0.965 g / cm ³ can be appropriately selected from commercially available products. It can select suitably from having illustrated as a commercial item of a component.

  The content of the (B) polyethylene resin in 100 parts by mass of the resin component in the resin composition is 10 to 40 parts by mass from the viewpoint of reducing the film thickness and weight, and obtaining excellent mechanical properties. 40 parts by mass is preferred.

((C) High pressure polymerization low density polyethylene)
(C) The high-pressure polymerization method low-density polyethylene of the component provides effects such as securing melt tension, thickness stability, and lowering of resin pressure when the resin composition is formed into a film, resulting in a thin film of the film. It is a component that contributes to weight reduction. The high-pressure polymerization method low-density polyethylene (C) is not particularly limited as long as it has a density of 0.910 to 0.929 g / cm ³ and is a polyethylene resin obtained by a high-pressure polymerization method.

  (C) Component High Pressure Polymerization Low-density polyethylene usually has a branched structure, and the constituent resin material can be appropriately selected from those exemplified as the resin material for component (A).

  The melting point of the high-pressure polymerization method low-density polyethylene (C) is preferably 100 to 120 ° C. from the viewpoint of reducing the film thickness and weight and obtaining excellent mechanical properties. The melt flow rate (MFR) is preferably 0.5 to 10 g / 10 min from the viewpoint of reducing the film thickness and weight and obtaining excellent mechanical properties.

As the component (C), the high-pressure polymerization method low-density polyethylene, a commercially available product having a density of 0.910 to 0.929 g / cm ³ can be appropriately selected and used. Commercially available products include, for example, “NOVATEC LD” (manufactured by Nippon Polyethylene Co., Ltd.), “Sumikasen EP”, “Sumikasen GMH” (manufactured by Sumitomo Chemical Co., Ltd.), “Suntech LD” (Asahi Kasei Chemicals Corporation). Manufactured).

  The content of (C) high-pressure polymerization low-density polyethylene in 100 parts by mass of the resin component in the resin composition is 5 to 20 from the viewpoint of reducing the film thickness and weight, and obtaining excellent moisture permeability and mechanical properties. It is a mass part, and 5-15 mass parts is preferable.

((D) propylene homopolymer)
The propylene homopolymer (D) is a component that imparts excellent mechanical properties and heat resistance to the moisture-permeable film.
As a propylene homopolymer, what was polymerized with multi-site catalysts, such as a Ziegler type and a Philips type, can be used, for example. That the resin to be used is a propylene homopolymer can be confirmed by measuring ¹³ C-NMR using a nuclear magnetic resonance apparatus (NMR) and detecting no monomer other than propylene.

The density of the propylene homopolymer (D) is preferably 0.890 to 0.910 g / cm ³ from the viewpoint of obtaining excellent mechanical properties and heat resistance. From the same viewpoint, the melting point is preferably 155 to 170 ° C., and the MFR is preferably 10 to 50 g / 10 min.

  The propylene homopolymer of component (D) can be appropriately selected from commercially available products. Commercially available products include, for example, “Novatech PP” (manufactured by Nippon Polypro Co., Ltd.), “Prime Polypro” (manufactured by Prime Polymer Co., Ltd.), “Sumitomo Noblen” (manufactured by Sumitomo Chemical Co., Ltd.), and Sun Allomer Co., Ltd. Examples thereof include polypropylene made by the method.

  Content of (D) propylene homopolymer in 100 mass parts of resin components in a resin composition is 5-20 mass parts. When the content of the propylene homopolymer of the component (D) is less than 5 parts by mass, excellent mechanical properties and heat resistance cannot be obtained, and when it exceeds 20 parts by mass, the polyethylene resin of the component (A) Excellent compatibility and dispersibility cannot be obtained, uniform stretching cannot be achieved, appearance defects occur, and productivity is lowered. From the same viewpoint, the content of the propylene homopolymer of component (D) is preferably 5 to 15 parts by mass.

The content of all resin components in the resin composition of the present invention is such that the wet film is very thin and lightweight, and has excellent air permeability, moisture permeability, mechanical characteristics of machine direction flow, liquid leakage resistance, and heat resistance. From the viewpoint of obtaining properties, it is preferably 20 to 60% by mass, more preferably 25 to 50% by mass, and further preferably 30 to 45% by mass.
Furthermore, the total amount of the components (A) to (D) in all resin components makes the wet film very thin and lightweight, and has excellent air permeability, moisture permeability, mechanical characteristics of machine direction flow, and liquid leakage resistance. From the viewpoint of obtaining properties and heat resistance, it is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and particularly preferably 100% by mass. preferable.

((E) inorganic filler)
(E) The inorganic filler is a component that contributes to the formation of voids (micropores), and is a component that imparts breathability, moisture permeability, and liquid leakage resistance to the moisture permeable film.
(E) As an inorganic filler, for example, calcium carbonate, calcium sulfate, barium carbonate, barium sulfate, titanium oxide, magnesium hydroxide, silicon oxide, aluminum oxide, talc, clay, kaolinite, montmorillonite, hydrotalcite, etc. Fine particles and minerals can be mentioned, and these can be used alone or in combination. Among these, calcium carbonate and barium sulfate are preferable because they are excellent in the expression of voids (micropores), high versatility, low price, and abundant brands.

(E) The inorganic filler may be either a heavy product obtained by grinding raw ore minerals or a light product obtained by chemical synthesis.
(E) As for D50 average particle diameter of an inorganic filler, 0.5-3 micrometers is preferable and 0.8-2 micrometers is more preferable. When the average particle size is 0.5 μm or more, there is no poor distribution and distribution of the inorganic filler and secondary aggregation, and the particles can be more uniformly dispersed. On the other hand, by setting the thickness to 3 μm or less, the size of voids (micropores) becomes appropriate when the film is thinned, and the mechanical characteristics, water resistance, and liquid leakage resistance are provided along with excellent air permeability and moisture permeability. can get.

  Further, it is preferable to use an inorganic filler whose surface is coated with a metal soap such as fatty acid, fatty acid ester or fatty acid salt in advance, or an inorganic filler whose surface is coated with a silane coupling agent. Since such inorganic fillers are easily compatible with the resin component, the dispersibility and mixing with the resin component can be improved, and homogeneous voids (micropores) can be formed. Properties, water resistance, and liquid leakage resistance are obtained.

  Content of the (E) inorganic filler with respect to 100 mass parts of resin components is 100-200 mass parts, 120-180 mass parts is preferable and 130-160 mass parts is more preferable. (E) When the content of the inorganic filler is within the above range, mechanical properties, water resistance, and liquid leakage resistance are obtained as well as excellent air permeability and moisture permeability.

((F) Plasticizer)
(F) 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. (F) Examples of the plasticizer include castor oil such as castor oil, hydrogenated castor oil, hydrogenated 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. Examples include low molecular weight polymers (oligomers) such as esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, aromatic esters, aromatic amides and polyethers, and polyesters. These are used alone or in combination. be able to.

  In the present invention, castor oils such as castor oil, hydrogenated castor oil, hydrogenated castor oil, and dehydrated castor oil are preferable, and among these, hydrogenated castor oil mainly composed of triglyceride composed of 12-hydroxyoctadecanoic acid and glycerin is 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. Processability, and water resistance and liquid leakage resistance are obtained.

  Hardened castor oil can be appropriately selected from commercially available products. Commercially available products include, for example, “castor hydrogenated oil”, “castor hydrogenated oil A” (above, made by Ito Oil Co., Ltd.), “castor hard”, “HCO-I” (above, made by KEF Trading Co., Ltd.) ), “Caster Wax” (manufactured by Toyokuni Oil Co., Ltd.).

  Content of the plasticizer (F) with respect to 100 mass parts of resin components is 1-20 mass parts, 1-15 mass parts is preferable, and 3-15 mass parts is more preferable. (F) 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 the liquid leakage resistance are obtained.

  Depending on the purpose of use, resins other than the above components (A) to (D), compatibilizers, processing aids, antioxidants, thermal stabilizers, light stabilizers, ultraviolet absorbers, antiblocking agents, antiblocking agents An appropriate amount of a clouding agent, a matting agent, an antibacterial agent, a deodorant, an antistatic agent, a flame retardant, a colorant, a pigment, and the like may be added to the resin composition to such an extent that the effects of the present invention are not impaired.

(Performance of moisture-permeable film)
The moisture-permeable film of the present invention has excellent air permeability with an air permeability of 50 to 5,000 seconds / 100 mL. When the air permeability is 50 seconds / 100 mL or more, excellent mechanical properties, water resistance, and liquid leakage resistance are obtained, and when it is 5,000 seconds / 100 mL or less, excellent air permeability and moisture permeability are obtained. The comfortability which was obtained when using the moisture-permeable film of this invention for sanitary materials, such as a back sheet for moisture-permeable waterproofing, such as a paper diaper and a physiological treatment article, is acquired. From the same viewpoint, the air permeability is preferably 100 to 2,000 seconds / 100 mL, more preferably 200 to 1,000 seconds / 100 mL. 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. Seiko Co., Ltd. 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.

Moisture permeability of moisture-permeable film of the present invention is more it is preferably ^{1,000~20,000g / (m 2 · 24h)} , a 5,000~15,000g / (m ² · 24h) preferable. If the moisture permeability is 1,000 g / (m ² · 24h) or more, moisture can be sufficiently released. Therefore, the moisture-permeable film of the present invention can be used as a back sheet for moisture-permeable waterproofing such as paper diapers and sanitary treatment products. When used as a sanitary material, it can be worn comfortably without moisture stuffiness and skin irritation. Moreover, the outstanding water resistance and liquid leakage resistance are ensured as it is 20,000 g / (m < ² > * 24h) or less. Here, in accordance with the conditions of JIS Z0208 (moisture-proof packaging material moisture permeability test method (cup method)), the moisture permeability is 15 g of anhydrous calcium chloride as a hygroscopic agent, constant temperature and constant at 40 ° C. and a relative humidity of 90%. In a humid environment, the sample was randomly measured at three points, and the arithmetic average value was obtained.

The tensile elastic modulus in the machine flow direction (MD direction) of the moisture-permeable film of the present invention is 60 to 150 MPa. When the tensile modulus is 60 MPa or more, it has moderate rigidity and tensile strength, excellent mechanical properties, no elongation and distortion of the film during printing, slitting and winding, and excellent mechanical suitability in the production line can be obtained. . Moreover, when it is 150 MPa or less, when the moisture-permeable film of the present invention is used for hygienic materials such as a moisture-permeable waterproof backsheet such as a paper diaper and a sanitary treatment article, there is no hardness, a sharp feeling, and an unpleasant feeling. Good and excellent wearing comfort. From the same viewpoint, the tensile elastic modulus is preferably 60 to 100 MPa. Here, the tensile elastic modulus in the machine flow direction is a sample having a width of 25 mm in accordance with JIS K7127, a tensile speed of 200 mm / min and a distance between chucks of 50 mm in an environment of 23 ° C. and a relative humidity of 50%. It is E (tensile modulus) calculated by the following formula from the first direct part of the tensile stress-strain curve obtained by measurement using a tensile tester under conditions. In the present invention, the arithmetic average value of E (tensile modulus) calculated by performing the measurement three times was used.
Tensile modulus = Δρ / Δε
Δρ: Stress difference due to the original average cross-sectional area between two points on a straight line Δε: Strain difference between the same two points

  The tensile strength at break in the machine flow direction (MD direction) of the moisture-permeable film of the present invention is preferably 5 to 15 N / 25 mm, and more preferably 8 to 12 N / 25 mm. When the tensile strength at break is 5 N / 25 mm or more, it has moderate rigidity and tensile strength, excellent mechanical properties, no elongation and distortion of the film during printing, slitting and winding, and excellent mechanical suitability in the production line. can get. Moreover, when it is 15N / 25mm or less, when using the moisture-permeable film of this invention for hygiene materials, such as a back sheet for moisture-permeable waterproofing, such as a paper diaper and a sanitary treatment article, there is no hardness, a sharp feeling, and an irritating feeling. It feels good and gives an excellent feel. Here, the tensile elastic modulus in the machine flow direction is a sample having a width of 25 mm in accordance with JIS K7127, a tensile speed of 200 mm / min and a distance between chucks of 50 mm in an environment of 23 ° C. and a relative humidity of 50%. It is the tensile strength at the time of breaking using a tensile tester under conditions. In the present invention, the arithmetic average value of the tensile strength at break calculated by measuring three times was used.

  The tensile elongation in the machine flow direction (MD direction) of the moisture-permeable film of the present invention is preferably 100 to 400%, and more preferably 150 to 300%. When the tensile elongation is 100% or more, when the moisture-permeable film of the present invention is used for sanitary materials such as moisture-permeable and waterproof backsheets such as disposable diapers and sanitary treatment articles, there is no hardness, sharpness, and tingling. It feels good and gives an excellent feel. Also, if the tensile elongation is 300% or less, it has moderate rigidity and tensile strength, excellent mechanical properties, no elongation and distortion of the film during printing, slitting and winding, and excellent mechanical suitability in the production line. can get. Here, the tensile elongation in the machine flow direction is a condition in which a sample having a width of 25 mm is prepared in accordance with JIS K7127, the tensile speed is 200 mm / min, and the chuck distance is 50 mm in an environment of 23 ° C. and a relative humidity of 50%. It is the elongation when it breaks using a tensile tester. In the present invention, the arithmetic average value of the tensile elongation calculated by measuring three times was used.

The oozing area of the moisture-permeable film of the present invention is less than 30%. When the oozing area is less than 30%, excellent water resistance and liquid leakage resistance are obtained, and the moisture permeable film of the present invention is used for hygienic materials such as back sheets for moisture permeable waterproofing such as paper diapers and sanitary treatment products. In some cases, bleeding and leakage of urine do not occur. From the same viewpoint, the oozing area is preferably less than 20%, more preferably less than 10%.
Here, the oozing area is a value obtained as follows.
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. 102 pigment (Wako Pure Chemical Industries, Ltd.) )) 0.30 parts 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 overlaid on the moisture retaining sheet, 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 heat-resistant temperature of the moisture-permeable film of the present invention is 160 ° C. or higher. When the heat-resistant temperature is 160 ° C. or higher, the moisture-permeable film of the present invention is sprayed at a high temperature used in the production process when used for sanitary materials such as paper diapers and backsheets for moisture-permeable waterproofing such as sanitary treatment products. It has excellent heat resistance to hot melt adhesives and does not develop into production process troubles such as film tearing. Here, the heat-resistant temperature is obtained by sandwiching a sample (100 mm × 100 mm) with two stainless steel plates (100 mm × 100 mm × 2 mm (thickness)) whose center is punched into a circular shape of φ50 mm, fixing four sides with clips, After standing for 2 minutes in a convection oven with a temperature of 160 ° C in the bath and heating, the sample of the circular punched out part of the stainless steel plate is melted, and it is visually judged whether or not there is a hole. The heat resistance temperature is 160 ° C. or higher.

The basis weight of the moisture-permeable film of the present invention is preferably from 5 to 50 g / m ^2, and more preferably 10 to 25 g / m ^2. When the basis weight is 5 g / m ² or more, excellent mechanical properties can be obtained. Further, when it is 50 g / m ² or less, the weight can be reduced, and excellent flexibility can be obtained. Here, the basic weight measured the mass of the sample (Mechanical flow direction (MD direction): 250 mm, vertical direction (TD direction): 200 mm) with the electronic balance, and made the value 20 times the numerical value into the basic weight.

  The thickness of the moisture-permeable film of the present invention is preferably 5 to 50 μm, and more preferably 10 to 25 μm. Excellent mechanical properties are obtained when the thickness is 5 μm or more. Moreover, when it is 50 μm or less, it is possible to reduce the thickness and weight and to obtain excellent flexibility. Here, the thickness is measured with respect to a sample (machine flow direction (MD direction): 100 mm, vertical direction (TD direction): 100 mm) using a constant pressure thickness meter at any nine points, and its arithmetic The average value was the thickness.

  The moisture-permeable film of the present invention is preferably stretched. By stretching, voids (micropores) are formed, so that excellent air permeability and moisture permeability can be obtained. From the viewpoint of uniformly stretching without stretching unevenness and obtaining a good balance of moisture permeability, water resistance, and liquid leakage resistance, the stretching ratio in the machine flow direction (MD direction) is 1.5 to 4.0 times. It is preferable that it is 2.0 to 3.5 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, depending on the application, 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 or non-woven fabric.

[Method for producing moisture-permeable film]
The moisture-permeable film of the present invention includes, for example, step (1) (A) 20 to 80 parts by mass of a linear polyethylene resin having a density of 0.910 to 0.929 g / cm ³ , and (B) a density of 0.930 to 0. 10 to 40 parts by mass of 965 g / cm ³ of polyethylene resin, (C) 5 to 20 parts by mass of high-pressure low-density polyethylene having a density of 0.910 to 0.929 g / cm ³ , and (D) propylene homopolymer 5 A resin composition containing ~ 20 parts by mass, a resin composition containing (E) 100 to 200 parts by mass of an inorganic filler and (F) 1 to 20 parts by mass of a plasticizer with respect to 100 parts by mass of the resin component And a step (2) of producing a resin composition in the form of a film by a production method having at least a stretching step of stretching 1.5 to 4.0 times at 0 to 100 ° C. in the machine flow direction. can do.

(Process (1))
Step (1) is a step of forming a predetermined resin composition into a film. The resin composition is the same as the resin composition forming the moisture-permeable film of the present invention.
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 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.

(Process (2))
The step (2) is a stretching step in which the resin composition formed into a film in the above step (1) is stretched at 1.5 to 4.0 times at 0 to 100 ° C. at least in the machine flow direction. Since voids (micropores) are formed in the resin composition film and become microporous, a moisture-permeable film can be obtained.
As a method for forming voids (micropores) in the film of the resin composition obtained in the step (1) and making it microporous, the stretch-opening method is general, 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 flow direction 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 0 to 100 ° C., and the stretching ratio is 1.5 to 4.0 times. The stretching temperature is more preferably 30 to 100 ° C, further preferably 50 to 90 ° C. When the stretching temperature is within the above range, excellent air permeability, moisture permeability, and liquid leakage resistance can be obtained in a balanced manner.
By setting the draw ratio to 1.5 times or more, a moisture-permeable film stretched uniformly without any stretch unevenness can be obtained. Further, by setting the draw ratio to 4.0 times or less, excellent moisture permeability, water resistance, and liquid leakage resistance can be obtained in a balanced manner. From the same viewpoint, 2.0 to 3.5 times is preferable.

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 breathability, moisture permeability, mechanical properties of machine direction flow, liquid resistance Leakage 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 decreased and the air permeability is increased), while the water resistance and the liquid leakage resistance tend to decrease, the tensile elastic modulus, and Since the tensile strength is increased, excellent mechanical suitability in the production line can be obtained, while hardness, sharpness, and a feeling of tingling tend to develop. In addition, as the draw ratio is reduced, water resistance and liquid leakage resistance tend to be improved, while air permeability tends to decrease, and the tensile modulus and strength are small, so the touch is good and excellent. While wearing comfort is obtained, mechanical suitability tends to decrease.
Further, as the stretching temperature is lowered, voids (micropores) are more easily formed, and the microporous structure is obtained, so that excellent air permeability is obtained, while water resistance and liquid leakage 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, to lower the breathability, increase the stretching temperature and decrease the stretching ratio. Thus, it is 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 method of heat setting, for example, when a roll stretching method is adopted, a draw ratio (ratio of winding side roll speed / unwinding side roll speed) while heating the stretched film with a heated roll (annealing roll) Is a method of making 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 60 to 120 ° C. If the heat setting temperature is 60 ° 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 -5%. 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.
Further, 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) Measurement of basic weight Basic weight was measured according to said method.
(2) Measurement of thickness According to said method, thickness was measured.
(3) Measurement of air permeability The air permeability was measured according to the method described above. As an air permeability measuring device, an Oken type air permeability measuring machine (“EGO1-55 type (model number)”, manufactured by Asahi Seiko Co., Ltd.) was used.
(4) Measurement of moisture permeability The moisture permeability was measured according to the above method.
(5) Measurement of machine flow direction (MD direction) tensile break strength According to the above method, the machine flow direction (MD direction) tensile break strength was measured.
(6) Measurement of machine flow direction (MD direction) tensile elongation According to the above method, the machine flow direction (MD direction) tensile elongation was measured.
(7) Measurement of machine flow direction (MD direction) tensile elastic modulus According to the method described above, the machine flow direction (MD direction) tensile elastic modulus was measured.
(8) Measurement of oozing area (evaluation of liquid leakage resistance)
In accordance with the above method, the oozing area was calculated and evaluated according to the following criteria.
A: The oozing area was less than 10%.
B: The oozing area was 10% or more and less than 20%.
C: The oozing area was 20% or more and less than 30%.
D: The oozing area was 30% or more.
(9) Evaluation of heat resistance According to the above method, those having no tearing and perforation are regarded as having a heat resistance temperature of 160 ° C. or higher (A evaluation), and those having been confirmed to be tearing and perforation are less than 160 ° C. It was.

Examples 1 and 2
Prepare each component of the resin composition shown in Table 1, put them into a super mixer, mix and disperse for 10 minutes, and melt knead using the same direction twin screw extruder at a set extrusion temperature of 180 ° C. A resin composition was obtained, 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 65 ° C. and a stretching ratio of 2.5 times in the machine flow direction ( The film was stretched once in the MD direction) and then heat-set and relaxed at 90 ° C. to obtain a moisture-permeable film. About the obtained moisture-permeable film, according to the method shown to said (1)-(9), each performance was measured and evaluated. The results are shown in Table 2.

Comparative Examples 1-3
In Example 1, a film was obtained in the same manner as in Example 1 except that the components of the resin composition were changed to those shown in Table 1. About the obtained film, according to the method shown to said (1)-(9), each performance was measured and evaluated. The results are shown in Table 2.

註)
(A) Component: Novatec LL UF230, manufactured by Nippon Polyethylene Co., Ltd. (B) Component 1: Novatec LL UF961, manufactured by Nippon Polyethylene Co., Ltd. (B) Component 2: Novatec HD HY331, manufactured by Nippon Polyethylene Co., Ltd. (C) Component: Novatec LD LF441, manufactured by Nippon Polyethylene Co., Ltd. (D) Ingredient: Novatec PP SA03, manufactured by Nippon Polypro Co., Ltd. m-EOC: Kernel KF360T, manufactured by Nippon Polyethylene Co., Ltd., linear low density polyethylene resin (E ) Inorganic filler: Ryton 2200, manufactured by Bihoku Flour Industry Co., Ltd., calcium carbonate (F) Plasticizer: HCP-P3, manufactured by KEF Trading Co., Ltd., hardened castor oil

From the results in Table 2, the moisture permeable films obtained in Example 1 and Example 2 are thin and lightweight, yet have excellent breathability and moisture permeability, and have a tensile modulus of 60 MPa or more and appropriate rigidity. Yes, it has excellent heat resistance during heat treatment at 160 ° C. Further, since the liquid oozes out to the back surface, it has been confirmed that the moisture permeable film can be suitably used particularly as a sanitary material such as a paper diaper and a moisture permeable waterproof back sheet such as a physiological treatment article.
On the other hand, the film of Comparative Example 1 which does not contain the component (B) and the component (D) as the resin component and the content of the component (A) is larger than the range specified in the present invention is liquid leakage resistance. Is good, but the tensile modulus in the machine flow direction is outside the range specified in the present invention, and excellent mechanical suitability in the production line cannot be obtained, and the moisture permeability and heat resistance are inferior. confirmed. The film of Comparative Example 2 using a resin composition containing no component (A) and (D) as a resin component and containing two types of components (B) is excellent in air permeability, moisture permeability, and mechanical properties. It was confirmed that the liquid leakage resistance and heat resistance were poor. Moreover, the film of the comparative example 3 using the resin composition which does not contain (B) component and (D) component as a resin component, and contains the low density linear polyethylene resin smaller than the density prescribed | regulated by this invention, It was confirmed that the tensile modulus in the machine flow direction was out of the range specified in the present invention, so that excellent mechanical suitability in the production line was not obtained and the heat resistance was poor.

  The moisture-permeable film obtained by the present invention is very thin and lightweight, and has excellent breathability and moisture permeability, and further has excellent mechanical properties in the machine direction flow, liquid leakage resistance, and heat resistance. The film can be particularly suitably used as a sanitary material such as a paper diaper and a moisture permeable waterproof backsheet such as a sanitary treatment article.

Claims (7)

(A) 20 to 80 parts by weight of a linear polyethylene resin of density 0.910~0.929g / cm ^3, (B) a density 0.930~0.965g / cm 10~40 parts by weight of polyethylene resin ³ , (C) 5 to 20 parts by mass of low-density polyethylene having a density of 0.910 to 0.929 g / cm ³ , and (D) 5 to 15 parts by mass of a propylene homopolymer, and 100 parts by mass of a resin component The resin component comprises (E) 100 to 200 parts by mass of an inorganic filler and (F) 1 to 20 parts by mass of a plasticizer, and has an air permeability of 50 to 5,000 seconds / A moisture-permeable film having 100 mL, a tensile elastic modulus in the machine flow direction of 60 to 150 MPa, a oozing area of less than 30%, and a heat resistant temperature of 160 ° C. or higher.   (A) The melting point of the linear polyethylene resin is 110 to 140 ° C, (B) the melting point of the polyethylene resin is 110 to 140 ° C, and (C) the melting point of the high-pressure polymerization method low-density polyethylene is 100 to 120 ° C. The moisture-permeable film according to claim 1.   (F) The moisture-permeable film according to claim 1 or 2, wherein the plasticizer is at least one kind of castor oil selected from castor oil, hydrogenated castor oil, hardened castor oil, and dehydrated castor oil. The moisture-permeable film according to any one of claims 1 to 3, wherein the basis weight is 5 to 50 g / m ² and the moisture permeability is 1,000 to 20,000 g / (m ² · 24 h).   The moisture-permeable film according to any one of claims 1 to 4, wherein the film is stretched.   The moisture-permeable film according to any one of claims 1 to 5, which is used for a moisture-permeable and waterproof back sheet for sanitary goods.   The moisture-permeable film laminated body which has at least one layer which consists of a moisture-permeable film in any one of Claims 1-6.