WO2015186808A1

WO2015186808A1 - Moisture permeable film

Info

Publication number: WO2015186808A1
Application number: PCT/JP2015/066261
Authority: WO
Inventors: 信之山形; 豊川合; 滋充間野
Original assignee: 三菱樹脂株式会社
Priority date: 2014-06-04
Filing date: 2015-06-04
Publication date: 2015-12-10

Abstract

This moisture permeable film has an air permeability of 50-5000 s/100 mL, and comprises a resin composition which contains: a resin component containing (A) 30-85 parts by mass of a straight-chain low-density polyethylene having a density of 0.910-0.940 g/cm³, (B) 5-20 parts by mass of a high-pressure polymerized low-density polyethylene and having a density of 0.910-0.930 g/cm³, and (C) 10-50 parts by mass of a metallocene-based ethylene-α olefin copolymer having a density of 0.875 g/cm³ or greater and less than 0.910 g/cm³; 100-200 parts by mass of (D) an inorganic filler per 100 parts by mass of the resin component; and 1-20 parts by mass of (E) a plasticizer per 100 parts by mass of the resin component. Thus it is possible to provide a moisture permeable film which, while having excellent flexibility, breathability and moisture permeability, has satisfactory heat shrinkage resistance and liquid leakage resistance. Further, it is possible to provide a moisture permeable film which has an excellent appearance, has ample shielding properties, and which further, while having excellent moisture permeability, is not prone to liquid leakage.

Description

Breathable film

The present invention relates to a moisture permeable film.

A moisture-permeable film made of a polyolefin resin and calcium carbonate is generally used for sanitary materials such as disposable diapers and sanitary treatment products, and is particularly used as a moisture-permeable and waterproof back sheet. The moisture-permeable film used for such sanitary materials is required to have the following properties.
First, in order to prevent stuffiness when wearing a paper diaper, it is required to have good air permeability and moisture permeability. Next, it is required to have a good texture and feel, and to be flexible so as not to hinder infant activities. Furthermore, it is required that the waterproof sheet is a film having high water resistance and liquid leakage resistance, and that troubles such as blocking and squeezing are not caused when a roll-like sample of a moisture permeable film is stored over time.
Therefore, it is desired that the moisture permeable film has a heat shrinkage rate as small as possible in the machine flow direction (direction in which the moisture permeable film is stretched).

In response to such a request, Patent Document 1 employs an orientable thermoplastic resin having a low elastic modulus and a hydrophobic surface as a base resin. An example of such a matrix resin is ethylene / propylene / 1,4-hexadiene terpolymer. Rich in texture and flexibility.

In response to such a request, Patent Document 2 discloses that an ethylene- (α-olefin) copolymer having a density of 0.86 to 0.90 g / cm ³ and a melting point of 60 to 100 ° C. and a thermoplastic elastomer are resin components. A porous film is disclosed.

Moreover, the porous film shown by patent document 3 uses the mixture of liquid polyester comprised from hardened castor oil, a C4-C4 or more polyhydric alcohol, and a fatty acid as a plasticizer of a 3rd component. Have gained texture, feel and flexibility.

Japanese Examined Patent Publication No. 4-58824 JP-A-7-228719 JP 2001-226506 A

However, in the method shown in Patent Document 1, the film is stretched at room temperature, and since the melting point of the base resin is low, it is not suitable for practical use because it is too soft and does not have an appropriate rigidity. The porous film described in Patent Document 2 is rich in flexibility, but has poor shrinkage resistance and dimensional stability due to heat, and is particularly unsuitable for uses other than sanitary materials. Thus, if the resin used as the base material is softened or has a low melting point, the problems of heat resistance, heat shrinkage, and productivity are not satisfied. Also, depending on the chemical structure, type, etc. of the liquid polyester constituting the porous film shown in Patent Document 3, water resistance and liquid leakage resistance are greatly reduced due to the hydrophilicity of the film surface, which is not suitable for a waterproof sheet of a disposable diaper. There is a fear. In addition, the liquid plasticizer has problems that cause production troubles such as foaming, jetting, bleed out, and blocking between films during film formation from a raw material blend.

The problem to be solved by the present invention is to provide a moisture permeable film that is excellent in flexibility, breathability and moisture permeability, yet satisfies heat shrinkage resistance and liquid leakage resistance.

As a result of intensive studies by the inventor in order to solve the above problems, linear low-density polyethylene having a specific density, high-pressure polymerization low-density polyethylene, metallocene ethylene-α olefin copolymer, inorganic having a specific particle size It was found that a moisture permeable film having an air permeability of 50 to 5,000 seconds / 100 mL can be obtained by using a resin composition containing a predetermined amount of a filler and a plasticizer. That is, this invention provides the following moisture-permeable films.
(A) 30 ~ 85 parts by weight linear low density polyethylene having a density of ^{0.910 ~ 0.940g / cm 3, (} B) High-pressure polymerization processes density 0.910 ~ 0.930g / cm ³ low-density A resin component comprising 5 to 20 parts by mass of polyethylene and (C) a metallocene ethylene-α-olefin copolymer having a density of 0.875 g / cm ³ or more and less than 0.910 g / cm ³ The resin composition comprises 100 to 200 parts by weight of (D) inorganic filler with respect to 100 parts by weight of the resin component, and 1 to 20 parts by weight of (E) plasticizer with respect to 100 parts by weight of the resin component. A moisture-permeable film having an air permeability of 50 to 5,000 seconds / 100 mL.

According to the present invention, it is possible to provide a moisture permeable film that is excellent in flexibility, air permeability and moisture permeability, yet satisfies heat shrinkage resistance and liquid leakage resistance.

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) 30 to 85 parts by mass of linear low density polyethylene having a density of 0.910 to 0.940 g / cm ³ , and (B) a density of 0.910 to 0.930 g / cm ^3. 5 to 20 parts by mass of cm ³ high-pressure polymerization low-density polyethylene, and 10 to 10 parts of (C) a metallocene ethylene-α-olefin copolymer having a density of 0.875 g / cm ³ or more and less than 0.910 g / cm ^3. A resin component containing 50 parts by weight, 100 to 200 parts by weight of (D) inorganic filler with respect to 100 parts by weight of the resin component, and 1 to 20 parts by weight of (E) plasticizer with respect to 100 parts by weight of the resin component, The air permeability is 50 to 5,000 seconds / 100 mL.
The resin composition having the above structure may be referred to as a resin composition of the present invention.
The resin composition of the present invention may further contain components other than the components (A) to (E).
Hereinafter, the following terms may be referred to as follows.
Linear low density polyethylene: LLDPE (Linear Low Density Polyethylene)
High pressure polymerization low density polyethylene: LDPE (Low Density Polyethylene)
Metallocene ethylene-α olefin copolymer: m-EOC
Machine flow direction: MD (Machine Direction)
Direction perpendicular to the machine flow direction (including a substantially vertical range): TD (Transverse Direction)

[(A) linear low density polyethylene (LLDPE)]
The linear low density polyethylene (A) has a density of 0.910 to 0.940 g / cm ³ . Here, the density is a density measured by a pycnometer method (JIS K7112 B method). The densities of other resins are values measured in the same manner. (A) The linear low density polyethylene (LLDPE) has a density of 0.910 to 0.940 g / cm ³ and is not particularly limited as long as it is a linear polyethylene. It is a copolymer with an α-olefin other than ethylene. Specifically, ethylene- (α such as ethylene-propylene, ethylene- (1-butene), ethylene- (1-hexene), ethylene- (4-methyl-1-pentene), ethylene- (1-octene), etc. -Olefin) copolymers. (A) As the linear low density polyethylene, any of the linear low density polyethylene (except metallocene linear low density polyethylene) polymerized by a known multi-site catalyst such as Ziegler type or Philips type can be used. It is.

The linear low-density polyethylene as the component (A) has a density of 0.910 from the viewpoints of flexibility, breathability, moisture permeability, heat shrinkage resistance, liquid leakage resistance, appearance, hiding property, and the like of the moisture permeable film. ~ 0.940 g / cm ³ . In particular, from the viewpoints of the flexibility, breathability, moisture permeability, heat shrinkage resistance, and liquid leakage resistance of the moisture permeable film, it is preferably 0.914 to 0.937 g / cm ³ , and preferably 0.918 to 0.8. More preferably, it is 935 g / cm ³ .
Further, from the viewpoint of the appearance, concealability, moisture permeability, and liquid leakage resistance of the moisture permeable film, the density is preferably 0.913 to 0.933 g / cm ³ , and 0.915 to 0.927 g / cm ^3. More preferably, it is cm ³ .
From the same viewpoint, the melting point of the linear low density polyethylene (A) is preferably 110 to 135 ° C., more preferably 115 to 135 ° C., and further preferably 115 to 130 ° C. Preferably, it is 117 to 130 ° C, more preferably 120 to 127 ° C.
Here, the melting point was about 10 mg of resin was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min using a differential scanning calorimeter (DSC), held at 200 ° C. for 1 minute, and then cooled at a rate of 10 This is 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 melting points of other resins are values measured in the same manner.

Further, (A) the linear low density polyethylene preferably has a melt flow rate (MFR) of 0.5 to 10 g / 10 min. Here, MFR is a value measured according to JIS K7219, and the measurement conditions are 190 ° C. and 2.16 kg load. The MFRs of other resins are values measured in the same manner.
The content of (A) linear low density polyethylene in 100 parts by mass of the resin component is 30 to 85 parts by mass, and the flexibility, breathability, moisture permeability, heat shrinkage resistance, and liquid leakage resistance of the moisture permeable film. From the viewpoint of properties, it is preferably 30 to 80 parts by mass, more preferably 35 to 70 parts by mass, and further preferably 40 to 65 parts by mass.
Further, from the viewpoint of the appearance, concealability, moisture permeability, and liquid leakage resistance of the moisture permeable film, it is preferably 40 to 85 parts by mass, more preferably 45 to 80 parts by mass, and 50 to 70 parts by mass. More preferably, it is a part.

(A) As the linear low density polyethylene, a commercially available product may be used. As long as the linear low-density polyethylene satisfying the above-described density and melting point, there are no limitations on the manufacturer, trade name, and grade of the commercial product. Examples of commercially available products include “NOVATEC LL”, “NOVATECH C6” (manufactured by Nippon Polyethylene Co., Ltd.), “Neozex”, “Ultzex”, “Moretech”, “Evolue” [above, Prime Co., Ltd. Polymer] and the like.

[(B) High pressure polymerization low density polyethylene (LDPE)]
(B) High-pressure polymerization method Low-density polyethylene (LDPE) is a branched polyethylene, and in the present invention, a resin having a density of 0.910 to 0.930 g / cm ³ is used. If it is polyethylene which has this characteristic, it will not restrict | limit in particular, A commercial item may be used and there is no limitation in the manufacturer, brand name, and grade of a commercial item. Examples of commercially available products include “Novatech LD” (manufactured by Nippon Polyethylene Co., Ltd.), “Sumikasen EP”, “Sumikasen GMH” (manufactured by Sumitomo Chemical Co., Ltd.), “Suntech LD” (Asahi Kasei Chemicals Corporation). Manufactured] and the like.

The (B) component high-pressure polymerization method low density polyethylene has a density of 0.910 to 0 from the viewpoint of the flexibility, breathability, appearance, concealability, moisture permeability, heat shrinkage resistance and liquid leakage resistance of the moisture permeable film. 0.930 g / cm ³ , preferably 0.913 to 0.927 g / cm ³ , and more preferably 0.915 to 0.923 g / cm ³ .
From the same viewpoint, the melting point of the (B) high-pressure polymerization method low-density polyethylene is preferably 100 to 120 ° C, more preferably 105 to 118 ° C, and further preferably 107 to 116 ° C. preferable.

The content of (B) high-pressure polymerization low-density polyethylene in 100 parts by mass of the resin component is 5 to 20 parts by mass. By being in the said range, the effect on a manufacture surface, such as ensuring of melt tension at the time of carrying out the high-speed extrusion molding of the resin composition of this invention, thickness stability, and the fall of a resin pressure, can be anticipated. From the viewpoint of further improving the effect, the content of the (B) high-pressure polymerization low-density polyethylene in 100 parts by mass of the resin component is preferably 7 to 17 parts by mass, and more preferably 9 to 15 parts by mass. More preferred.

[(C) Metallocene ethylene-α olefin copolymer (m-EOC)]
(C) Metallocene-based ethylene-α olefin copolymer (m-EOC) is a highly active such as Kaminsky catalyst represented by zirconocene, titanocene and hafnocene (collectively, metallocene), and a stoke metallocene catalyst. An ethylene- (α-olefin) copolymer polymerized with at least one catalyst selected from the group consisting of single-site catalysts. At present, a variety of polyethylene resins having an ultra-low density or ultra-low melting point and a very narrow molecular weight distribution are on the market.
(C) Metallocene-based ethylene-α-olefin copolymer (m-EOC) improves kneadability and uniform dispersibility when kneaded with an inorganic filler, m-EOC has a low density, and has a low melting point. It is used for the purpose of lowering the elastic modulus and suppressing unevenness of stretching due to the fact that it is, and the features are greatly different from the component (A). In the present invention, a resin having a density of 0.875 g / cm ³ or more and less than 0.910 g / cm ³ is used, and preferably a density of 0.880 g / cm ³ or more and 0.910 g / cm ³ for the above-described features and purposes. Less than ³ resins are used.

In the present invention, the melting point of the (C) component metallocene ethylene-α-olefin copolymer is preferably 70 to 110 ° C., more preferably 70 to 100 ° C. When the density and melting point are within the numerical ranges, it is easy to obtain effects such as the texture and flexibility of the moisture-permeable film, and suppresses troubles such as film tensile strength reduction, film blocking, and fusion during molding. can do.
From the viewpoint of further improving the texture and flexibility of the moisture-permeable film, and the moldability of the film, the density of the (C) metallocene ethylene-α-olefin copolymer is 0.883 to 0.908 g / cm ^3. Is more preferable, and 0.887 to 0.905 g / cm ³ is more preferable. From the same viewpoint, the melting point of the (C) metallocene ethylene-α-olefin copolymer is more preferably 75 to 97 ° C, and further preferably 80 to 95 ° C.

In the present invention, it is preferable to use a resin having a molecular weight distribution of 1.0 to 3.0 as the (C) metallocene ethylene-α-olefin copolymer. The molecular weight distribution is more preferably from 1.1 to 2.8, and even more preferably from 1.2 to 2.5. When the molecular weight distribution is within this range, it is possible to suppress a decrease in elastic modulus and stretching unevenness.

The MFR of the (C) metallocene ethylene-α olefin copolymer is preferably 0.5 to 10 g / 10 min.
The content of the (C) metallocene ethylene-α olefin copolymer in 100 parts by mass of the resin component is 10 to 50 parts by mass. When it is 10 parts by mass or more, more preferably 15 parts by mass or more, the moisture-permeable film has a sufficient texture and flexibility, and when it is 50 parts by mass or less, more preferably 40 parts by mass or less. Therefore, the moisture-permeable film has sufficient mechanical properties and heat resistance, which is advantageous in terms of production cost.
From the viewpoint of flexibility, breathability, appearance, concealability, moisture permeability, heat shrinkage resistance, and liquid leakage resistance of the moisture permeable film, (C) the metallocene ethylene-α olefin copolymer in 100 parts by mass of the resin component The content is preferably 17 to 47 parts by mass, more preferably 22 to 45 parts by mass.

(C) The metallocene ethylene-α olefin copolymer may be a commercially available product as long as it has the above-mentioned density and melting point, and the commercially available product / grade is not particularly limited. Polyethylene Co., Ltd. “Kernel”, “Harmolex”, Prime Polymer Co., Ltd. “Evolue”, Sumitomo Chemical Co., Ltd. “Sumikasen E”, “Exelen FX”, Dow Chemical Company “ELITE”, “ENGAGE”, Exxon Mobile Chemical "Enable", "Exceed", etc. are mentioned.

The content of all resin components in the resin composition of the present invention is 20 to 60% by mass from the viewpoints of flexibility, breathability, moisture permeability, heat shrinkage resistance, and liquid leakage resistance of the moisture permeable film. It is preferably 25 to 50% by mass, more preferably 30 to 45% by mass.
Further, the total amount of the components (A) to (C) in all the resin components is 70% by mass or more from the viewpoint of the flexibility, breathability, moisture permeability, heat shrinkage resistance, and liquid leakage resistance of the moisture permeable film. It is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass.

[(D) inorganic filler]
(D) The inorganic filler is contained in the resin composition in the range of 100 to 200 parts by mass with respect to 100 parts by mass of the resin component.
(D) The inorganic filler (Filler) is a component that contributes to the formation of voids (micropores) in the moisture permeable film, and is a component that imparts breathability, moisture permeability and liquid leakage resistance to the moisture permeable film. is there.
Examples of the inorganic filler (D) include calcium carbonate, calcium sulfate, barium carbonate, barium sulfate, titanium oxide, magnesium hydroxide, silicon oxide, aluminum oxide, talc, clay, kaolinite, montmorillonite, and hydrotalcite. Fine particles and minerals can be mentioned, and these can be used alone or in combination. Among these, calcium carbonate and barium sulfate are preferred because they are excellent in the expression of voids (micropores), high versatility, low price, and abundant brands.

(D) The inorganic filler may be either a heavy product obtained by grinding raw ore minerals or a light product obtained by chemical synthesis.
(D) The average particle diameter (D50) of the inorganic filler is preferably 0.5 to 3 μm, more preferably 0.8 to 2 μm. 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 average particle size to 3 μm or less, the size of the voids (micropores) becomes appropriate when the resin composition of the present invention is thinned, and the machine has excellent air permeability and moisture permeability. Characteristics, water resistance and liquid leakage resistance can be obtained.
(D) When calcium carbonate is used as the inorganic filler, whiteness W = 85% or more, hue L = 90% or more, a = −0.5 to 0.5, b = −1.0 to 2.0 Preferably there is.

In addition, 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, a silane coupling agent, an inorganic filler whose surface is coated with fine particles such as silica and alumina. . Since such inorganic fillers are easily compatible with the resin component, the dispersibility and mixing with the resin component is improved, and uniform voids (micropores) can be formed in the moisture-permeable film. Mechanical properties, water resistance, and liquid leakage resistance are obtained along with wetness.

The content of the (D) inorganic filler in the resin composition with respect to 100 parts by mass of the resin component is 100 to 200 parts by mass from the viewpoints of film appearance, concealability, moisture permeability, mechanical properties and water resistance.
Furthermore, from the viewpoint of flexibility, breathability, moisture permeability, heat shrinkage resistance, and liquid leakage resistance of the moisture permeable film, the content of the (D) inorganic filler with respect to 100 parts by mass of the resin component is 120 to 190 parts by mass. Preferably, it is 140 to 180 parts by mass.

[(E) Plasticizer]
(E) The plasticizer is contained in the resin composition in the range of 1 to 20 parts by mass with respect to 100 parts by mass of the resin component. By being in this range, it is excellent in the balance of the stretch workability at the time of shape | molding the resin composition of this invention, and the handling at the time of production.
(E) A plasticizer is a component which contributes to the improvement of the stretch workability of a resin composition composition.
(E) As a plasticizer, higher fatty acid, higher fatty acid ester, higher fatty acid amide, metal soap, higher alcohol, petrolatum, paraffin wax, glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, castor oil, Low molecular weight polymers (oligomers) such as hydrogenated castor oil, hydrogenated castor oil, dehydrated castor oil, aromatic esters, aromatic amides, polyethers and polyesters are used.

Among them, in the present invention, at least one castor oil selected from the group consisting of castor oil, hydrogenated castor oil, hydrogenated castor oil, and dehydrated castor oil is preferable, hydrogenated castor oil is more preferable, and triglyceride consisting of 12-hydroxyoctadecanoic acid and glycerin is used. More preferred is hardened castor oil as the main component.
The hardened castor oil is in the form of a powder having a melting point of 80 to 90 ° C., so that it can be easily handled during production of a moisture permeable film, has an excellent plasticizing and spreading effect on the resin composition of the present invention, and has water resistance. In addition, it exhibits liquid leakage resistance.

(E) A commercial item may be used as the plasticizer, and the grade of the commercial item is not particularly limited. For example, as an example of a commercial item of hydrogenated castor oil, Ito Oil Co., Ltd. Products such as castor hydrogenated oil A, KEF Trading “Hima Hard”, “HCO-I”, Toyokuni Oil Co., Ltd. “Caster Wax”, and the like.

From the viewpoint of the flexibility, breathability, moisture permeability, heat shrinkage resistance, and liquid leakage resistance of the moisture permeable film, the content of the (E) plasticizer with respect to 100 parts by mass of the resin component is 2 to 15 parts by mass. Is preferably 4 to 10 parts by mass.

[Other ingredients]
The resin composition of the present invention further comprises a compatibilizer, a processing aid, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antiblocking agent, an antiblocking agent, depending on the intended use of the moisture permeable film. It may contain a clouding agent, a matting agent, an antibacterial agent, a deodorant, an antistatic agent, a flame retardant, a colorant, a pigment, and the like.

(Physical properties of moisture-permeable film)
The moisture-permeable film of the present invention has an air permeability of 50 to 5,000 seconds / 100 mL.

[Air permeability]
The air permeability of the moisture permeable film is 50 to 5,000 seconds / 100 mL, preferably 200 to 1,000 seconds / 100 mL. When the air permeability is 50 seconds / 100 mL or more, sufficient mechanical properties, water resistance and liquid leakage resistance of the moisture-permeable film can be secured, and when the air permeability is 5,000 seconds / 100 mL or less, ventilation is achieved. Comfort when a moisture-permeable film is made into a paper diaper, such as property and moisture permeability, is ensured.
The air permeability of the moisture permeable film is measured according to a method defined in JIS P8117 (Gurley test machine method) [for example, manufactured by Asahi Seiko Co., Ltd., Oken air permeability tester, EGO1. -55 type], and measured at 10 locations of the moisture-permeable film, and the arithmetic average value is measured.

[Heat shrinkage in the machine flow direction after heating at 60 ° C. for 1 hour]
The heat shrinkage rate of the moisture permeable film in the machine flow direction after heating the moisture permeable film at 60 ° C. for 1 hour is preferably less than 5.0%, more preferably less than 3.0%. When it is less than 5.0%, there is little blocking or squeezing when a roll-shaped sample of a moisture-permeable film is stored over time, which is suitable for practical use.
The heat shrinkage rate of the moisture permeable film is determined as follows.
A test piece (MD: 200 mm, TD: 10 mm) is collected from the moisture permeable film, and is statically heated in a convection oven set at a bath temperature of 60 ° C. for 1.0 hour. Thereafter, the length L (mm) in the machine flow direction (MD) is measured. Randomly select and measure three locations on the moisture-permeable film, obtain the respective heat shrinkage rate by the formula “(L-200) / 200 × 100 (%)”, and calculate the arithmetic average value of the heat-permeable film. Shrinkage rate.

[Mechanical properties]
The tensile elastic modulus in the machine flow direction (MD) of the moisture-permeable film is preferably 50 MPa or less, more preferably 5 to 40 MPa. By setting it to 50 MPa or less, the texture and flexibility after processing the moisture-permeable film into a paper diaper are secured, and the comfort is excellent.
The moisture-permeable film of the present invention preferably further has the following mechanical properties.
The tensile strength in the machine flow direction (MD) of the moisture permeable film is preferably 3 to 10 N / 25 mm, and more preferably 5 to 8 N / 25 mm. By setting it to 3N / 25mm or more, it has moderate tensile strength and excellent mechanical suitability, and by setting it to 10N / 25mm or less, texture and flexibility after processing into a paper diaper are ensured, and the comfort is excellent.

The tensile elongation in the machine flow (MD) direction of the moisture permeable film is preferably 100 to 400%, more preferably 150 to 300%. If it is within the above range, it has appropriate flexibility and tensile strength, and therefore, it is excellent in mechanical suitability during processing of a paper diaper.
The tensile strength and tensile elongation of the moisture-permeable film were measured three times at a test width of 25 mm and a tensile speed of 200 m / min according to JIS K7127, and the strength and elongation at the point at which the specimen of the moisture-permeable film was broken. It is calculated as the arithmetic average value of
Further, the tensile elastic modulus of the moisture-permeable film is first measured three times at a test width of 25 mm and a tensile speed of 200 m / min in accordance with JIS K7127, similarly to the measurement of tensile strength and tensile elongation. Next, the tensile elastic modulus is calculated from the strength and elongation behavior in the range where the test piece is extended by 0 to 10%, and is obtained as the arithmetic average value.

[Total light transmittance]
The total light transmittance of the moisture-permeable film is preferably 20 to 60%, more preferably 30 to 50%. When the total light transmittance is 20% or more, it can be identified even if an indicator drug is applied to the moisture-permeable film to notify urination. When the total light transmittance is 60% or less, the film is white and concealed. Rich in nature.
The total light transmittance of the moisture permeable film is determined according to JIS K7361, such as a haze meter (for example, Nippon Denshoku Industries Co., Ltd., haze meter, NDH5000SP) and a constant pressure thickness meter (for example, Mitutoyo Corporation, thickness gauge, 547). -055] is measured at five locations of the moisture-permeable film, and the arithmetic average value is measured.

[Bleed area]
The oozing area of the moisture permeable film is preferably less than 30%, more preferably less than 20%, and even more preferably less than 10%. By being less than 30%, it can be said that the moisture-permeable film has excellent water resistance and liquid leakage resistance, and the moisture-permeable film can be suitably used as a moisture-permeable and water-proof back sheet for disposable diapers and physiological treatment products. .
The oozing area of the moisture permeable film is measured as follows.

First, in a constant temperature and humidity room adjusted to a temperature of 23 ° C. and a relative humidity of 50%, 0.2 parts by mass of a cationic surfactant (manufactured by NOF Corporation, Elegan 264-30) in a 200 mL beaker, Red No. 102 Add 0.3 parts by weight of pigment [manufactured by Wako Pure Chemical Industries, Ltd.] and 99.8 parts by weight of distilled water, stir for 1 hour, uniformly dissolve and disperse to prepare a red test solution. .

In a constant temperature and humidity room adjusted to a temperature of 23 ° C. and a relative humidity of 50%, as shown in FIG. 1, a test liquid is marketed by stacking a moisture permeable film and a commercial kitchen paper on the filter paper. Gently drop 2.0 mL with a dropper on the center of the kitchen paper. After dripping the test solution, a resin plate is placed on a commercially available kitchen paper, and a weight of 2 kg is further placed and left for 30 minutes. Next, the area of the portion 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) is measured, and the proportion of the area in the entire pressurized filter paper is calculated. The value obtained is taken as the oozing area.
Examples of the filter paper include “FILTER PAPER No. 2 (trade name); (diameter: 70 mm)” manufactured by Advantech Co., Ltd.

[Basis weight]
The basis weight of the moisture permeable film is preferably 5 to 50 g / m ² , more preferably 10 to 30 g / m ² , and still more preferably 15 to 25 g / m ² . It is preferable that the basis weight is 5 g / m ² or more because the tensile strength, tear strength, and appropriate rigidity of the moisture-permeable film can be secured. Further, when the basis weight is 50 g / m ² or less, a moisture-permeable film having a sufficient lightweight feeling, texture and flexibility can be obtained.
The basis weight of the moisture-permeable film is a value obtained by taking a test piece (MD: 250 mm, TD: 200 mm) from the moisture-permeable film, measuring the mass (g) with an electronic balance, and multiplying the numerical value by 20 times.

[Thickness]
The thickness of the moisture permeable film is preferably 5 to 50 μm, more preferably 15 to 30 μm. The thickness of 5 μm or more is preferable because the tensile strength and tear strength of the moisture-permeable film can be secured. Moreover, sufficient lightweight feeling, texture, and a softness | flexibility can be acquired because it is 50 micrometers or less.
The thickness of the moisture-permeable film is obtained by taking a test piece (MD: 100 mm, TD: 100 mm) from the moisture-permeable film and then measuring with a constant pressure thickness meter [eg, Mitutoyo Corporation, thickness gauge, model 547-055]. Is measured as 9 points, and is obtained as the arithmetic average value.

[Moisture permeability]
The moisture permeability of the moisture permeable film is preferably 1,000 to 20,000 g / (m ² · 24 h), more preferably 2,000 to 15,000 g / (m ² · 24 h), and still more preferably 5,000 to 15 000 g / (m ² · 24 h). Moisture permeability is 1,000g / (m ² · 24h) or more, so it can be worn comfortably without stuffiness and skin irritation when used as a paper diaper, and at 20,000g / (m ² · 24h) or less. As a result, sufficient mechanical properties, water resistance, and liquid leakage resistance of the moisture permeable film are ensured.
The moisture permeability of the moisture permeable film is measured by a method based on JIS Z0208 (cup method). Specifically, the measurement was performed in a constant temperature and humidity environment at a temperature of 40 ° C. and a relative humidity of 90%, and in the presence of 15 g of calcium chloride as a hygroscopic agent. It is a value calculated as an arithmetic average value by randomly selecting and measuring three locations of the moisture-permeable film.

The moisture-permeable film of the present invention may be a film having a multilayer structure having two or more moisture-permeable films using the resin composition of the present invention, depending on applications, purposes and the like.

The moisture-permeable film of the present invention can be obtained by forming the resin composition of the present invention into a thin film by a method such as melt extrusion. Therefore, the production method is not limited, and a film can be obtained by applying a known method. However, from the viewpoint of production efficiency, cost, etc., after the resin composition of the present invention is melt-extruded, inflation, tubular, T-die, etc. A method of forming a thin film according to the method is preferable.
Moreover, in order for the moisture-permeable film of this invention to have the above-mentioned physical property, it is preferable that a moisture-permeable film is a stretched film.
The moisture-permeable film of the present invention is preferably produced by the following method for producing a moisture-permeable film of the present invention.

<Method for producing moisture-permeable film>
The moisture-permeable film of the present invention comprises a step (1) (A) 30 to 85 parts by mass of linear low density polyethylene having a density of 0.910 to 0.940 g / cm ³ , and (B) a density of 0.910 to High-pressure polymerization method of 0.930 g / cm ³ 5 to 20 parts by mass of low density polyethylene, and (C) a metallocene ethylene-α-olefin copolymer having a density of 0.875 g / cm ³ or more and less than 0.910 g / cm ³ A resin component containing 10 to 50 parts by weight, 100 to 200 parts by weight of (D) inorganic filler with respect to 100 parts by weight of the resin component, and 1 to 20 parts by weight of (E) plastic with respect to 100 parts by weight of the resin component A molding step of molding the resin composition containing the agent into a film,
Step (2) a stretching step of stretching the resin composition formed into a film;
It is preferable to manufacture by the manufacturing method which has this.

[Process (1)-Molding process-]
In step (1), the above-described resin composition of the present invention is formed into a film.
The resin composition used in the method for producing a moisture-permeable film of the present invention is the resin composition of the present invention described above. Therefore, the structure of the resin composition used in the method for producing the moisture-permeable film of the present invention is the same as the structure of the resin composition of the present invention, and the preferred embodiment is also the same.
In step (1), in addition to the components (A) to (E) contained in the resin composition of the present invention, components that may be included as necessary are mixed in the amounts described above, and then kneaded. It is preferable to melt and knead with a machine (extruder).

Specifically, each component may be mixed by a mixer such as a tumbler mixer, a mixing roll, a Banbury mixer, a ribbon blender, or a super mixer. In addition, the melt kneading of the mixture is preferably performed using a kneader such as a different-direction twin screw extruder or a same-direction twin screw extruder to promote uniform dispersion and distribution of the resin composition. In some cases, it is possible to directly add the component to the kneader without using a mixer such as a mixer.
The resin composition melt-extruded from the kneader is preferably pelletized by a method such as strand cutting or die cutting after cooling. It is also possible to extrude from a kneader die to a cooling roller, a cooling belt or the like and directly form a thin film.

[Step (2)-Drawing step-]
In step (2), the resin composition molded into a film is stretched.
The method of stretching the film obtained in the step (1) is generally a stretch opening method, but the method is not particularly limited as long as the temperature condition and the stretch ratio are in the above ranges. For example, a known stretching method represented by a biaxial stretching method such as a roll stretching method, a tenter method, simultaneous biaxial stretching, or sequential biaxial stretching can be applied.

In the present invention, the resin composition molded into a film shape may be performed at least once in the uniaxial direction or twice or more in consideration of stretching unevenness and air permeability, and the appearance and moisture permeability are improved. Therefore, it may be performed in two stages.
The stretching condition is that the stretching temperature is 0 to 100 ° C., and the stretching ratio is preferably 1.5 to 4.0 times as a total ratio, and more preferably 2.0 to 3.5 times.
By setting the stretching ratio to 1.5 times or more in total, a moisture-permeable film stretched uniformly without stretching unevenness can be obtained. On the other hand, by setting the stretching ratio to 4.0 times or less in total, a moisture permeable film satisfying the balance between moisture permeability, water resistance and liquid leakage resistance can be obtained.

In the production 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 imparted in a well-balanced manner, and the conditions can be appropriately selected according to desired performance.
For example, as the draw ratio is increased, air permeability is improved (air permeability is decreased), while water resistance and liquid leakage resistance tend to decrease, and tensile modulus and tensile strength are increased. While excellent mechanical suitability in the production line can be obtained, hardness tends 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, heat setting may be performed after stretching.
The heat setting refers to preliminarily applying heat to the film and intentionally shrinking the film to suppress shrinkage of the product roll. In the case of the roll stretching method, there is a method in which the draw ratio (ratio of winding side roll speed / unwinding side roll speed) is set to a negative number while heating the stretched film with a heated roll (annealing roll). In the case of the tenter stretching method, the film is contracted by heating the film in the vicinity of the tenter outlet and making the clip width at both ends narrower than the width after stretching.
From the viewpoint of sufficiently heat-setting the film and suppressing the film from being wound or torn around the roll, the heat-setting temperature in the present invention is preferably 60 to 100 ° C, more preferably 60 to 90 ° C. .
Further, the negative draw ratio is preferably −20 to −5% in total, and if it is within the specified range, heat fixation can be performed without any trouble in production, and sufficient thermal dimensional stability can be obtained. Moreover, you may divide | segment and implement several times like the said extending | stretching. Even if the moisture permeable film which passed through this process is stored for a long time as a roll-shaped roll, there is little elastic shrinkage, shrinkage or squeezing due to heat, sticking between films, and blocking. Even when it has further, a film can be processed without a problem.

Hereinafter, although the Example and comparative example of this invention are specified, this invention is not limited to these.
In Examples 1 and 2 and Comparative Examples 1 and 2, all the raw materials shown in Table 1 were put into a super mixer, mixed and dispersed for 10 minutes, melt-kneaded at a set extrusion temperature of 180 ° C. with a unidirectional twin screw extruder, and strand cut Compound pellets were obtained in this manner. Then, after forming into a film shape with a single screw extruder and an inflation die, stretching is performed once in the machine flow direction (MD) at a stretching temperature of 65 ° C. and a stretching ratio of 2.50 times using a roll type longitudinal stretching machine. The film was heat fixed at 90 ° C. and relaxed to obtain a moisture permeable film.
Table 1 shows the raw materials and compositions of Examples 1-2 and Comparative Examples 1-2.
(C) m-EOC having a separation amount distribution of 1.8 was used.

In Examples 3 to 4 and Comparative Examples 3 to 4, all the raw materials shown in Table 1 were put into a super mixer, mixed and dispersed for 10 minutes, melt-kneaded at a set extrusion temperature of 180 ° C. with a unidirectional twin screw extruder, and strand cut Compound pellets were obtained in this manner. Thereafter, the film was formed into a film shape using a single-screw extruder and an inflation bracket / die and stretched using a roll-type stretching machine.
In Example 3 and Comparative Examples 3 to 4, the film was stretched once in the machine flow direction (MD) (temperature 65 ° C., magnification 2.60 times), heat fixed at 95 ° C., and relaxed.
In Example 4, the film was stretched once in the machine flow direction (MD) (temperature 65 ° C., magnification 2.80 times), heat fixed at 95 ° C., and relaxed.
The raw materials and compositions of Examples 3 to 4 and Comparative Examples 3 to 4 are shown in Table 1.

(Measurement method and evaluation)
Examples 1 to 4 and Comparative Examples 1 to 4 were evaluated on the following items. The evaluation results are shown in Table 3. For Examples 1 and 2 and Comparative Examples 1 and 2, items (1) to (9) were evaluated, and for Examples 3 and 4 and Comparative Examples 3 and 4, items (1) and (3) , (4), (7) to (10) were evaluated.

(1) Basis weight (g / m ² )
After collecting a test piece (MD: 250 mm, TD: 200 mm) from the obtained moisture-permeable film, the weight (g) was measured with an electronic balance, and the numerical value was multiplied by 20 to obtain a basis weight.

(2) Thickness (μm)
After collecting a test piece (MD: 100 mm, TD: 100 mm) from the obtained moisture-permeable film, the thickness was measured at 9 points with a constant-pressure thickness meter (manufactured by Mitutoyo Corporation, thickness gauge, model 547-055). The arithmetic average value was defined as the thickness.

(3) Air permeability (sec / 100mL)
Using an air permeability measuring device (Asahi Seiko Co., Ltd., Oken air permeability measuring device, EGO1-55 type) according to the method specified in JIS P8117 (Gurley Tester Method), 10 samples Measured and the arithmetic average value was defined as air permeability.

(4) Moisture permeability [g / (m ² · 24h)]
The moisture permeability was measured by a method based on JIS Z0208 (cup method). Specifically, the measurement was performed under conditions of a constant temperature and humidity environment of a temperature of 40 ° C. and a relative humidity of 90% under the condition of 15 g of calcium chloride as a hygroscopic agent. The sample was measured at three points at random, and the arithmetic average value was obtained.

(5) Tensile strength (N / 25 mm) in the machine flow direction and (6) Tensile elongation (%) in the machine flow direction (denoted in the table as MD tensile strength and MD tensile elongation, respectively)
In accordance with JIS K7127, the measurement was performed three times at a test width of 25 mm and a tensile speed of 200 m / min. The arithmetic mean value of the intensity | strength and elongation of the point which the test piece of the moisture-permeable film broke was calculated | required.

(7) Tensile modulus (MPa) in the machine flow direction (described as MD tensile modulus in the table)
In accordance with JIS K7127, the measurement was performed three times at a test width of 25 mm and a tensile speed of 200 m / min. The tensile modulus was calculated from the strength and elongation behavior in the range where the test piece was extended by 0 to 10%, and the arithmetic average value was obtained.

(8) Heat shrinkage rate (%) (heat shrinkage rate in the machine flow direction after heating at 60 ° C. for 1 hour)
A test piece (MD: 200 mm, TD: 10 mm) was taken from the moisture permeable film, and was statically heated for 1.0 hour in a convection oven set at a bath temperature of 60 ° C. Thereafter, the length L (mm) in the machine flow direction (MD) was measured. Randomly select and measure three locations on the moisture-permeable film, obtain the respective heat shrinkage rate by the formula “(L-200) / 200 × 100 (%)”, and calculate the arithmetic average value of the heat-permeable film. It was set as the shrinkage rate.

(9) Liquid leakage test The liquid leakage test was evaluated using the area of the moisture-permeable film that had oozed out. The oozing area was determined using a test solution as follows.
First, 0.2 parts by mass of a cationic surfactant (manufactured by NOF Corporation, Elegan 264-30) was placed in a 200 mL beaker in a constant temperature and humidity room adjusted to a temperature of 23 ° C. and a relative humidity of 50%. , Red No. 102 pigment [manufactured by Wako Pure Chemical Industries, Ltd.] 0.3 parts by weight and 99.8 parts by weight of distilled water were gradually added, stirred for 1 hour, and uniformly dissolved and dispersed to give a red test A liquid was prepared.
Next, in a constant temperature and humidity room adjusted to a temperature of 23 ° C. and a relative humidity of 50%, as shown in FIG. 1, filter paper [“FILTER PAPER No. 2 (trade name)”, manufactured by Advantech Co., Ltd., On top of [Diameter: 70 mm], a moisture-permeable film cut into a 100 mm × 100 mm square and a commercial kitchen paper cut into a 70 mm × 70 mm square are layered, and the test solution is gently placed with a dropper on the center of the commercial kitchen paper. 0.0 mL was added dropwise. After dripping the test solution, a resin plate (diameter: 60 mm, thickness: 5 mm) was layered on a commercially available kitchen paper, and a 2 kg weight 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 was defined as the oozing area.
The evaluation criteria are as follows.
A: Exudation area is less than 10% B: Exudation area is 10% or more and less than 20% C: Exudation area is 20% or more and less than 30% D: Exudation area is 30% or more

(10) Total light transmittance (%)
A haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., haze meter, NDH5000SP) and a constant pressure thickness meter [manufactured by Mitutoyo Corporation, thickness gauge, 547-055] in accordance with JIS K7361 were used. Each sample was measured at five points, and the arithmetic average value was obtained.

From Table 2, Example 1 and Example 2 are excellent in air permeability and moisture permeability, but also have a small heat shrinkage rate and good results of the liquid leakage test. Furthermore, since the MD tensile modulus is 50 MPa or less, the flexibility is sufficient.
On the other hand, although Comparative Example 1 is satisfactory in terms of air permeability and moisture permeability, the MD tensile elastic modulus is 80 MPa or more and the flexibility is not sufficient. Since the comparative example 2 uses the liquid plasticizer, the result of the liquid leak test is not sufficient, and the moisture permeability and the heat shrinkage rate are slightly inferior.

From Table 2, Example 1 and Example 2 are excellent in the concealability (total light transmittance), breathability and moisture permeability of the moisture permeable film, but also have good liquid leakage test results. Furthermore, the flexibility and the heat shrinkage ratio are sufficiently suitable for practical use, and are excellent overall. Further, in Example 2, it was considered that the concealability and moisture permeability were improved because the stretching whitening was promoted by dividing the stretching in the MD direction into two. From the above results, it was found that without adding a white pigment, it is possible to produce a moisture permeable film that is highly concealed and excellent in moisture permeability but hardly leaks.
On the other hand, in Comparative Example 1, although flexibility is satisfied, the concealability, air permeability, moisture permeability, and heat shrinkage rate are poor. It is considered that the selection of the physical properties and blending amount of the metallocene ethylene-α olefin copolymer to be used greatly affects the physical properties of the moisture permeable film. Since Comparative Example 2 uses a liquid plasticizer, good results were not obtained in the liquid leakage test.

Since the moisture-permeable film obtained by the present invention is a moisture-permeable film that is excellent in flexibility, breathability and moisture permeability, has a good appearance, has good concealment properties, and is resistant to heat shrinkage and liquid leakage, it is a disposable diaper and sanitary treatment article. It can be suitably used as a moisture permeable and waterproof back sheet for sanitary products such as

1; Weight (2kg)
2; resin plate 3; kitchen paper 4; test solution (2.0 mL)
5; moisture-permeable film 6; filter paper 7; filter paper after the test

Claims

(A) 30 ~ 85 parts by weight linear low density polyethylene having a density of 0.910 ~ 0.940g / cm 3, ( B) High-pressure polymerization processes density 0.910 ~ 0.930g / cm 3 low-density A resin component comprising 5 to 20 parts by mass of polyethylene and (C) a metallocene ethylene-α-olefin copolymer having a density of 0.875 g / cm 3 or more and less than 0.910 g / cm 3 ,
100 to 200 parts by weight of (D) inorganic filler with respect to 100 parts by weight of the resin component;
1 to 20 parts by mass of (E) plasticizer with respect to 100 parts by mass of the resin component;
A resin composition containing
A moisture-permeable film having an air permeability of 50 to 5,000 seconds / 100 mL.
The moisture-permeable film according to claim 1, wherein the (C) metallocene ethylene-α-olefin copolymer has a molecular weight distribution of 1.0 to 3.0.
(A) The melting point of the linear low density polyethylene is 110 to 135 ° C., (B) the melting point of the high pressure polymerization low density polyethylene is 100 to 120 ° C., and (C) the metallocene ethylene-α olefin copolymer The moisture-permeable film according to claim 1 or 2, wherein the melting point of the coalescence is 70 to 110 ° C.
The moisture-permeable film according to any one of claims 1 to 3, wherein the plasticizer (E) is at least one castor oil selected from the group consisting of castor oil, hydrogenated castor oil, hardened castor oil, and dehydrated castor oil.
The moisture permeability according to any one of claims 1 to 4, wherein the heat shrinkage rate in the machine flow direction after heating at 60 ° C for 1 hour is less than 5.0%, and the tensile elastic modulus in the machine flow direction is 50 MPa or less. the film.
The moisture-permeable film according to any one of claims 1 to 5, wherein the total light transmittance is 20 to 60%.
The moisture-permeable film according to any one of claims 1 to 6, wherein the oozing area is less than 30%.
The moisture-permeable film according to any one of claims 1 to 7, wherein the basis weight is 5 to 50 g / m 2 and the moisture permeability is 1,000 to 20,000 g / (m 2 · 24h).
The moisture-permeable film according to any one of claims 1 to 8, which is stretched.
The moisture-permeable film according to any one of claims 1 to 9, which is used for a moisture-permeable and waterproof back sheet for sanitary goods.