JPH0977893A - Air-permeable film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an air-permeable film comprising a composition containing a polyolefin resin consisting essentially of a specific polyethylene/α olefin copolymer, excellent in air permeability, having proper elasticity, useful as a paper diaper, etc. SOLUTION: This air-permeable film comprises a resin composition containing a polyolefin resin (A) consisting of an ethylene/α-olefin copolymer having 5-25g/10 minutes melt flow rate(MFR), 0.88-0.92g/cm<3> density (d) and 1.5-3.5 molecular-weight distribution (Mw/Mn) measured by GPC, a relation between an n-decane-soluble amount (W(wt.%)) at 23 deg.C and a density (d) satisfying formula I when MFR<=10g/10 minutes and formula II when MFR>10g/10 minutes and B1>=B2 when the average value of the number of branches of a high- molecular weight side in chromatography measured by GPC-1R is B1 and that of a low-molecular weight side is B2 and a filler (B) in the ratio of the component A/B=30/70 to 80/20 by weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breathable film, and in particular, it has excellent breathability and moderate elasticity, so that it has excellent texture and mechanical strength such as tensile strength and tear strength, and is a disposable diaper. The present invention relates to a breathable film suitable for use as a back sheet, sanitary materials such as sanitary products, medical applications, various filters, agricultural material applications, and the like.

[0002]

2. Description of the Related Art In recent years, disposable diaper back sheets,
Sanitary materials such as sanitary products, MRSA (nosocomial infection) countermeasure film, apron, sheet for clothes, antibacterial film such as protective clothing, film or sheet for building materials such as house wrap material,
Agricultural sheets such as heat shield sheets, rain wraps, film or sheets for clothing such as various protective clothing, concrete curing sheets, films or sheets for civil engineering materials such as asphalt overlay, synthetic paper, posters, industrial materials such as envelopes, etc.
BACKGROUND ART Breathable films are used in a wide range of applications such as battery separators, industrial wastewater treatment, and filter media used for mist removal. These breathable films are required to have various properties depending on their use. For example, a breathable sheet used as a bank sheet for a disposable diaper is required to have excellent characteristics such as texture, touch and fit.

[0003]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a breathable film which is excellent in breathability and has appropriate elasticity so that it has excellent texture and mechanical strength such as tensile strength and tear strength. To do.

[0004]

In order to solve the above problems, the present invention provides a polyolefin resin (A) containing an ethylene / α-olefin copolymer as a main component, and a filler (B).
And (A) / (B) weight ratio is 30/70 to 80/2.
A breathable film obtained by stretching a film or sheet made of a resin composition containing 0 ratio, wherein the ethylene / α-olefin copolymer has (1) a melt flow rate (MFR) of 5 to 25 g. / 10 minutes, and (2) the density (d) is 0.88 to 0.92 g / cm ^3.
And (3) the molecular weight distribution (Mw / Mn) measured by GPC is in the range of 1.5 to 3.5, and (4)
Amount of n-decane-soluble component at 23 ° C (W (% by weight))
And the density (d) is MFR ≦ 10 g / 10 minutes, W <80 × exp [−100 (d−0.88)] + 0.
When 1 MFR> 10 g / 10 minutes, W <80 × (MFR-9) ^0.26 × exp [−100 (d
-0.88)] + 0.1, and (5) the average value of the number of branches on the high molecular weight side in the chromatogram measured by GPC-IR is B1, and the average of the number of branches on the low molecular weight side. When the value is B2, a breathable film having B1 ≧ B2 is provided.

The breathable film of the present invention will be described in detail below.

The breathable film of the present invention comprises ethylene / α
-A film or sheet made of a resin composition containing a polyolefin resin (A) containing an olefin copolymer as a main component and a filler (B) is stretched.

The polyolefin resin which is the component (A) of the resin composition which is the material of the breathable film of the present invention is mainly composed of an ethylene / α-olefin copolymer. It contains at least 80% or more of a copolymer as a main component. Examples of components other than the ethylene / α-olefin copolymer as the main component include thermoplastic resins such as ethylene-based polymers and propylene-based polymers. Among these, high-pressure low-density polyethylene is hygienic. It is preferable in that the air-permeable film of the present invention, such as a material, can have properties suitable for use. In the present invention, the ethylene / α-olefin copolymer is a copolymer composed of ethylene and an α-olefin having 4 to 12 carbon atoms. Examples of the α-olefin having 4 to 12 carbon atoms used for copolymerization with ethylene include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and 1-decene. , 1-dodecene and the like. The ethylene / α-olefin copolymer is an α-olefin having 4 to 12 carbon atoms.
-The olefin may contain one kind alone or two or more kinds in combination. Among these α-olefins, α-olefins having 4 to 10 carbon atoms, particularly 4 to 6 carbon atoms
.Alpha.-olefins are preferred.

In this ethylene / α-olefin copolymer, repeating structural units derived from ethylene (hereinafter,
“Ethylene unit”) and α with 4 to 12 carbon atoms
-Repeating structural unit derived from olefin (hereinafter referred to as "α
-Referred to as "olefin unit") is a proportion of 50% by weight or more and less than 100% by weight of ethylene unit, 50% by weight or less of α-olefin unit, preferably 55 to 50% by weight of ethylene unit.
Ratio of 1 to 45% by weight of α-olefin unit to 99% by weight, more preferably ratio of 2 to 35% by weight of α-olefin unit to 65 to 98% by weight of ethylene unit, particularly preferably ethylene unit It is desirable to contain the α-olefin unit in an amount of 4 to 30% by weight with respect to 70 to 96% by weight.

In the present invention, the content of each ethylene unit and α-olefin unit in the ethylene / α-olefin copolymer is about 200 mg of ethylene / α-olefin copolymer and 1 m of hexachlorobutadiene.
The sample prepared by uniformly dissolving in 1 was measured using a 10 mmφ sample tube at a measurement temperature of 120 ° C. and a measurement frequency of 25.0.
Under the measurement conditions of 5 MHz, spectrum width 1500 Hz, pulse repetition time 4.2 sec, pulse width 6 μsec,
It can be determined by measuring the ¹³ C-NMR spectrum.

Further, the ethylene / α-olefin copolymer can be stably formed into a film having excellent mechanical strength such as tear strength by a casting method or the like,
Further, when the formed film is voided by a treatment such as stretching, the melt flow rate (MFR) is 5 to 25 g / 10 minutes, preferably 8 to 15 g /, in that good processability can be obtained. It is in the range of 10 minutes.
In the present invention, the melt flow rate (MFR) is A
According to STM D 1238-65T, temperature 190
It is measured at a temperature of 2.16 kg and a load of 2.16 kg.

Further, the ethylene / α-olefin copolymer has an Orzen rigidity within a suitable range, and a film having elasticity can be obtained, which does not stick to the skin, has no sticky feeling, and is excellent in mechanical strength. In terms of obtaining surface material,
The density is 0.88 to 0.92 g / cm ³ , preferably 0.
It is in the range of 90 to 0.92 g / cm ³ . In the present invention, the density of the ethylene / α-olefin copolymer is 1 hour after heat treatment of the strand obtained at the time of measuring the melt flow rate (MFR) at 190 ° C. under a load of 2.16 kg at 120 ° C. for 1 hour. It is a value measured with a density gradient tube after slowly cooling to room temperature over time.

Further, the ethylene / α-olefin copolymer has a molecular weight distribution (Mw / Mn, Mw; weight average molecular weight, Mn; number average molecular weight) measured by GPC of 1.5 to 3.5, It is preferably in the range of 2.0 to 3.0. In the present invention, the molecular weight distribution (Mw / Mn) is measured under the following measurement conditions. GPC device: Millipore GPC-150 Separation column: TSK GNH HT (diameter 72 mm, length 600 mm) Column temperature: 140 ° C. Mobile phase: o-dichlorobenzene (Wako Pure Chemical Industries) and BHT (Takeda Yakuhin) as an antioxidant ) 0.025 wt% Migration speed: 1.0 ml / min Sample concentration: 0.1 wt% Sample injection amount: 500 μl Detector: Differential refractometer Standard polystyrene: Molecular weight Mw <1000 and Mw
> 4 × 10 ⁶ is manufactured by Tosoh Corporation, and 1000 <
For Mw <4 × 10 ⁶ , a product manufactured by Pressure Chemical Co. was used.

The ethylene / α-olefin copolymer has an n-decane-soluble component amount (W (% by weight)) and a density (d (g / cm ³ )) at 23 ° C. shown below. The relationship is satisfied. MFR ≦ 10g /
At 10 minutes, W <80 × exp [−100 (d−0.88)] + 0.
When 1 MFR> 10 g / 10 minutes, W <80 × (MFR-9) ^0.26 × exp [−100 (d
-0.88)] +0.1

The amount of the n-decane-soluble component is ethylene.
It is an index showing the breadth of the composition distribution of the α-olefin copolymer, and the smaller the amount of n-decane-soluble component, the narrower the composition distribution. In the present invention, the amount of the n-decane-soluble component is measured by measuring about 3 g of the ethylene / α-olefin copolymer as n.
-Add to 450 ml of decane, melt at 145 ° C and then 2
Cool to 3 ° C., remove the insoluble part of n-decane by filtration,
It can be determined by recovering the n-decane-soluble portion from the filtrate.

Further, the ethylene / α-olefin copolymer has a temperature [Tm (° C.)] and a density [d (g / cm) at the maximum peak position of the endothermic curve measured by a differential scanning calorimeter (DSC). ³ )] has a relationship represented by Tm <400 × d-250, preferably Tm <450 × d-297, more preferably Tm <500 × d-344, and particularly preferably Tm <550 × d-391. Those that meet the requirements are desirable.

In the present invention, the differential scanning calorimeter (DS
The temperature (Tm) at the maximum peak position of the endothermic curve measured by C) was 20% at a heating rate of 10 ° C./min by packing about 5 mg of an ethylene / α-olefin copolymer sample in an aluminum pan.
The temperature is raised to 0 ° C. and kept at 200 ° C. for 5 minutes. Next, after the temperature was lowered to room temperature at a temperature lowering rate of 20 ° C./min, the temperature rising rate was 10
It is determined from the endothermic curve measured when the temperature is raised at ° C / min.

In the present invention, the relationship between the amount (W) of n-decane-soluble component and the density (d), and the temperature (Tm) at the maximum peak position in the endothermic curve measured by a differential scanning calorimeter (DSC). The relationship between the density and the density (d) shows that the ethylene / α-olefin copolymer having the above relationship has a narrow composition distribution.

In this ethylene / α-olefin copolymer, when the average value of the number of branches on the high molecular weight side by GPC-IR is B1 and the average value of the number of branches on the low molecular weight side is B2, B1 ≧ B2. It is a thing. Here, the average value of the number of branches on the high molecular weight side (B1) measured by GPC-IR means GP
The cumulative weight fraction of the polymer elution amount that was molecular weight fractionated by C was measured for each fraction within the range of 15 to 85% (that is, the polymer elution component excluding the low molecular weight region 15% and the high molecular weight region 15%). The measured value group of the number of branches
It is the average value of the values on the high molecular weight side of the two divided by the molecular weight at the peak position of the elution curve. On the other hand, the average value of the number of branches on the low molecular weight side (B2) is the average value on the low molecular weight side of the two divided ones.

B1 and B2 are measured under the following measurement conditions. Measuring device: Perkin-Elmer 1760X Column: Tosoh Corp. TS gel GMH-HT (7.5
mml. D. X600 mm) x1 Eluent: o-dichlorobenzene (ODCB) containing 0.05% MP-J [manufactured by Wako Pure Chemical Industries, extra p
ure grade] Column temperature: 140 ° C. Sample concentration: 0.1% (w / v) Injection volume: 100 μl Detector: MCT Resolution: 8 cm ⁻¹ Ethylene / α where B1 and B2 have the above relationship
Since the olefin copolymer has a narrow composition distribution and a small amount of low molecular weight components, it is less sticky.
Therefore, when the ethylene / α-olefin copolymer as described above is used, for example, in a backsheet of a disposable paper diaper, it is possible to obtain a breathable film having a good texture, rich flexibility, and excellent tear strength. .

As the main component of the polyolefin resin (A) of the resin composition for forming the breathable film of the present invention, the ethylene / α-olefin copolymer is used alone or 2
It can be used in combination of more than one kind.

The ethylene / α-olefin copolymer used in the present invention contains ethylene and α-olefin having 4 to 12 carbon atoms in the presence of a so-called metallocene olefin polymerization catalyst containing a metallocene catalyst component. It can be produced by a method of copolymerization so that the density of the obtained copolymer is 0.88 to 0.98 g / cm ³ . For example, Japanese Patent Application Laid-Open Nos. 6-9724 and 6-1.
It can be manufactured according to the methods described in JP-A-36195, JP-A-6-136196 and JP-A-6-207057.

The metallocene olefin polymerization catalyst used for the copolymerization of ethylene with an α-olefin having 4 to 12 carbon atoms usually has at least one ligand having a cyclopentadienyl skeleton in the molecule. Periodic Table I
Metallocene catalyst component (a) consisting of VB group transition metal compound, organoaluminum oxy compound catalyst component (b)
And a particulate carrier (c), and optionally an organoaluminum compound catalyst component (d) and an ionizable ionic compound catalyst component (e).

The metallocene catalyst component (a) is a transition metal compound of Group IV of the periodic table having at least one ligand having a cyclopentadienyl skeleton in the molecule. Examples of the transition metal compound include transition metal compounds represented by the following general formula [1]. ML ¹ _x ... [1] (where x is the valence of the transition metal atom M) M is a transition metal atom selected from Group IVB of the Periodic Table, for example, zirconium, titanium, hafnium, etc. Among these, zirconium is preferable.

L ¹ is a ligand which coordinates to the transition metal atom M and has a cyclopentadienyl skeleton,
A hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, a trialkylsilyl group, a formula: SO ₃ R (wherein R is 1 to 8 carbon atoms which may have a substituent such as halogen)
Is a group represented by the hydrocarbon group of, a halogen atom or a hydrogen atom, and at least one of the ligands L ¹ is a group having a cyclopentadienyl skeleton.

Specific examples of the group having a cyclopentadienyl skeleton include a cyclopentadienyl group, a methylcyclopentadienyl group, a dimethylcyclopentadienyl group,
Alkyl-substituted cyclopentadienyl groups such as trimethylcyclopentadienyl group, tetotelamethylcyclopentadienyl group, pentamethylcyclopentadienyl group, methylethylcyclopentadienyl group, hexylcyclopentadienyl group, or indenyl Base, 4, 5, 6, 7
-Tetrahydroindenyl group, fluorenyl group and the like can be mentioned. Further, these groups may be substituted with a halogen atom, trialkylsilyl or the like.

Examples of the hydrocarbon group having 1 to 12 carbon atoms include alkyl groups such as methyl group, cycloalkyl groups such as cyclopentyl group, aryl groups such as phenyl group, and aralkyl groups such as benzyl group.

Examples of the alkoxy group include a methoxy group, and examples of the aryloxy group include a phenoxy group. Further, examples of the trialkylsilyl group include a trimethylsilyl group and a triphenylsilyl group.

Further, the group represented by the formula: SO ₃ R ¹ (R ¹ is a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent such as halogen) is, for example, p- Examples thereof include a toluenesulfonato group, a methanesulfonato group, and a trifluoromethanesulfonato group.

Furthermore, examples of the halogen atom include chlorine, fluorine, bromine and the like.

The transition metal compound represented by the general formula [1] has a cyclopentadienyl skeleton-containing group 2
In the case of containing at least two, groups having at least two cyclopentadienyl skeletons are alkylene groups such as ethylene and propylene, substituted alkylene groups such as isopropylidenediphenylmethylene, silylene groups or dimethylsilylene groups, diphenylsilylene groups, It may be bonded via a substituted silylene group such as a methylphenylsilylene group.

Aluminoxane is preferably used as the organoaluminum oxy compound catalyst component which is the component (b) of the metallocene olefin polymerization catalyst.
Specifically, the following formula: -Al (R ²⁾ O- (wherein, R ² is an alkyl group) The repeating unit represented by normally closed about 3 to 50,
Examples include methylaluminoxane, ethylaluminoxane, methylethylaluminoxane, and the like. Such aluminoxane can be prepared by a conventionally known production method.

The fine particle carrier (c) is a carrier composed of an inorganic or organic compound and has a particle size of usually 10 to 10.
It is a granular or fine particle solid having a particle size of about 300 μm, preferably 20 to 200 μm. The inorganic carrier is preferably a porous oxide, specifically, SiO ₂ , Al ₂ O.
₃ , MgO, ZrO ₂ , TiO ₂ , B ₂ O ₃ , CaO,
Examples thereof include BaO, SnO _{2 and the} like, or a mixture thereof. This inorganic carrier contains a small amount of Na ₂ C.
Carbonate such as O ₃ ; sulfate such as Al ₂ (SO ₄ ) ₃ ; KN
It may contain a nitrate such as O ₃ or an oxide such as Li ₂ O.

Further, the organic compound used as the particulate carrier (c) is produced mainly with an α-olefin having 2 to 14 carbon atoms such as ethylene and 4-methyl-1-pentene (co). Polymer or vinylcyclohexane, styrene is the main component (co)
The thing which consists of a polymer can be illustrated.

This particulate carrier (c) has a specific surface area of 50 to 100, although its properties vary depending on its type and manufacturing method.
0 m ² / g, preferably 100~700m ² / g, the carrier pore volume is 0.3~2.5cm ³ / g is desirable.

The fine particle carrier (c) is used after firing at 100 to 1000 ° C., preferably 150 to 700 ° C., if necessary.

Further, the organoaluminum compound catalyst component optionally used as the component (d) of the metallocene olefin polymerization catalyst is specifically a trialkylaluminum such as trimethylaluminum or an alkenyl such as isoprenylaluminum. Examples thereof include dialkyl aluminum halides such as aluminum and dimethyl aluminum chloride, alkyl aluminum sesquihalides such as methyl aluminum sesquichloride, alkyl aluminum dihalides such as methyl aluminum dichloride, and arnor aluminum hydrides such as diethyl aluminum hydride.

Further, as the component (e) of the metallocene-based olefin polymerization catalyst, an ionizable ionic compound catalyst component (e) which is optionally used is, for example, triphenylboron, MgCl ₂ , Al ₂ O ₃ , SiO ₂
Lewis acids such as -Al ₂ O ₃ ; ionic compounds such as triphenylcarbenium tetrakis (pentafluorophenyl) borate; carborane compounds such as dodecaborane and bis-n-butylammonium (1-carbedodeca) borate. Specific examples of the ionized ionic compound catalyst component (e) include those described in US Pat. No. 5,477,18.

The ethylene / α-olefin copolymer (A) used in the present invention includes the metallocene catalyst component (a) and the organoaluminum oxy compound catalyst component (b).
In the presence of a catalyst for metallocene-based olefin polymerization, which comprises a catalyst (c) and a fine particle carrier (c), and optionally an organoaluminum compound catalyst component (d) and an ionizable ionic compound catalyst component (e), in a gas phase or slurry Or, under various conditions such as a liquid phase in a solution state, ethylene and the number of carbon atoms are 4 to 1
It can be obtained by copolymerizing 2 with α-olefin.

In slurry polymerization or solution polymerization,
The inert hydrocarbon may be used as the solvent, or the olefin itself may be used as the solvent.

When carrying out the polymerization, the metallocene olefin polymerization catalyst is usually at a concentration of transition metal atoms in the polymerization reaction system of usually 10 ^-8 to 10 ^-3 g atom / l, preferably 10 ^-7. It is preferably used in an amount of about 10 ⁻⁴ gram atom / l.

In the polymerization, the fine particle carrier (c) is also used.
Organoaluminum oxy compound catalyst component (b) and organoaluminum compound catalyst component (d) supported on
In addition to the above, an unsupported organoaluminum oxy compound catalyst component (b) and / or an organoaluminum compound catalyst component (c) may be used. in this case,
The unsupported organoaluminum oxy compound catalyst component (b) and / or the organoaluminum compound catalyst component (c) is the unsupported organoaluminum oxy compound catalyst component (b) and / or the organoaluminum compound catalyst component (c). Aluminum atom (A
The atomic ratio [Al / M] between 1) and the transition metal atom (M) derived from the metallocene catalyst component (a) is 5 to 300, preferably 10 to 200, more preferably 15 to 150.
It is adjusted to be within the range.

The polymerization temperature in the slurry polymerization method is usually -50 to 100 ° C, preferably 0 to 90 ° C, and the polymerization temperature in the solution polymerization method is usually -50 to 5 ° C.
It is in the range of 00 ° C, preferably 0 to 400 ° C. Also,
The polymerization temperature in the gas phase polymerization method is usually 0 to 120 ° C,
It is preferably in the range of 20 to 100 ° C.

The polymerization pressure is usually from atmospheric pressure to 100 kg / c.
It is under a pressure condition of m ² , preferably ² to 50 kg / cm ² , and the polymerization can be carried out in any of a batch system, a semi-continuous system and a continuous system.

In the production of this ethylene / α-olefin copolymer, (1) multi-stage polymerization, (2) multi-stage polymerization of liquid phase and gas phase, or (3) pre-polymerization in liquid phase is carried out, if necessary. It is possible to employ a method such as carrying out the polymerization in the gas phase after that. Among these methods, the multi-stage polymerization of (1) above is preferable.

Examples of the multistage polymerization method include a multistage polymerization method including the following steps [a] and [b]. [A] In the presence of the metallocene olefin polymerization catalyst, ethylene is copolymerized with an α-olefin having 4 to 12 carbon atoms to produce an ethylene / α-olefin copolymer (A-1). Step [b] In a polymerization vessel different from the polymerization vessel in which the copolymerization reaction is carried out, ethylene is copolymerized with α-olefin having 4 to 12 carbon atoms in the presence of the metallocene-based olefin polymerization catalyst, Process for producing ethylene / α-olefin copolymer (A-2)

The metallocene olefin polymerization catalyst used in this step [a] and / or [b] is
The catalyst may include an organoaluminum compound catalyst component (d) in addition to the metallocene catalyst component (a) and the organoaluminum oxy compound catalyst component (b), and the metallocene catalyst component (a) may be added to the particulate carrier (c). ) And an organoaluminum oxy compound catalyst component (b) are supported. Further, these metallocene-based olefin polymerization catalysts are obtained by prepolymerizing olefins on a solid catalyst component in which a metallocene catalyst component (a) and an organoaluminum oxy compound catalyst component (b) are supported on a particulate carrier (c). It may be a prepolymerization catalyst. Further, these metallocene-based catalysts include the above solid catalyst (solid catalyst component) and the organoaluminum compound catalyst component (d).
Or a catalyst comprising the prepolymerization catalyst (preliminary polymerization catalyst component) and the organoaluminum compound catalyst component (d).

In this multistage polymerization method, the above-mentioned ethylene / α-olefin copolymer (A-1) is first produced by using a plurality of polymerization vessels connected in series, and then ethylene / α-olefin is used.
-The ethylene / α-olefin copolymer (A-1) was introduced into a polymerization vessel different from the polymerization vessel used for the production of the olefin copolymer (A-1), and the ethylene / α-olefin copolymer (A The ethylene / α-olefin copolymer (A-2) can be produced in the presence of -1). Further, first, an ethylene / α-olefin copolymer (A-2) is produced,
Next, ethylene / α-olefin copolymer (A-2)
Ethylene / α in a different polymerization vessel from the one used to manufacture
-Introducing an olefin copolymer (A-2), ethylene
The ethylene / α-olefin (A-1) can also be produced in the presence of the α-olefin copolymer (A-2).

Further, a plurality of polymerization vessels are connected in parallel, and ethylene / α-olefin copolymers (A-1) and (A-2) are produced in each of the polymerization vessels, and then both copolymers are produced. Can also be blended.

The polyolefin resin (A) of the resin composition which is the material of the breathable film of the present invention includes, in addition to the ethylene / α-olefin copolymer, conventionally known slip agents, hydrophilic agents and inorganic fillers. An additive such as a heat stabilizer can be blended by a method such as kneading molding, etc. within a range that does not impair the object of the present invention.

The filler used as the component (B) of the resin composition is not particularly limited, and may be either an inorganic filler or an organic filler, or a combination of both. Specific examples of the filler include inorganic earth fillers such as alkaline earth metals, oxides, hydroxides, carbonates, sulfates and silicates of Group III elements of the periodic table. Examples of the organic filler include cellulose powder such as wood powder and pulp, and crosslinked powder such as silicone and phenol. These may be used alone or in combination of two or more. Among these, calcium carbonate, barium sulfate and the like are preferable in consideration of cost and stability of quality.

The particle size of this filler is usually 0.1-10.
It is about μm, preferably about 0.5 to 5 μm.

The content ratio of polyolefin resin (A) / filler (B) in the resin composition is 30/7 by weight.
0 to 80/20.

When the resin composition contains an antioxidant, the content thereof is usually 0. 0 with respect to 100 parts by weight in total of the polyolefin resin and the filler in the resin composition.
It is about 1 to 2.0 parts by weight, preferably about 0.5 to 1.8 parts by weight.

In addition to the antioxidant, the resin composition may further contain additives such as an ultraviolet absorber, an antibacterial agent, a fungicide, an antirust agent, a lubricant, a pigment, and a heat stabilizer, if necessary. It may be included as long as the object of the present invention is not impaired.

The resin composition has improved moldability,
Alternatively, in order to adjust various physical properties, an olefinic elastomer such as polyethylene or polystyrene may be contained within a range not impairing the object of the present invention. When these olefin-based elastomers are contained, the content thereof is usually 20 parts by weight or less with respect to 100 parts by weight of the ethylene / α-olefin copolymer resin.

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

In the present invention, the resin composition is melt-molded into a film or sheet. This melt molding may be performed by any method as long as it can be melt-kneaded to form a film or sheet by melting and kneading the resin composition. For example, a resin composition may be melt-kneaded using a conventional device such as a single-screw or twin-screw extruder or a twin-screw kneader, and then formed into a film or sheet by inflation molding, T-die extrusion molding, or the like. it can.

The temperature at the time of melt-kneading the resin composition is usually
It is adjusted in the range of 200 to 280 ° C.

In inflation molding, a uniaxially stretched or biaxially stretched film in a cylindrical shape can be drawn out from a circular die, and uniaxially stretched by roll stretching. Further, in the molding using a T-die, after forming an unoriented sheet or film, uniaxial stretching by roll stretching or biaxial stretching by a tenter method can be performed.

In the present invention, the thickness of the film or sheet obtained by melt-molding the resin composition is not particularly limited and is appropriately selected according to the application.

Next, the resin composition molded into a film or sheet can be stretched to obtain a breathable film. This stretching treatment may be uniaxial stretching or biaxial stretching, and is appropriately selected depending on the application. For example, in the case of uniaxial stretching, there is an advantage that the stretching treatment can be easily performed, and uniaxial stretching is advantageous for applications where the anisotropy of strength does not matter. Further, in the case of biaxial stretching, it is possible to further reduce the film thickness, which is effective for the purpose of improving the softness due to the reduction in rigidity and eliminating the anisotropy in strength.

In the case of uniaxial stretching, roll stretching is usually used, and it may be carried out in one stage or in multiple stages of two or more stages. At this time, the stretching temperature is adjusted in the range of room temperature to the melting point of the resin,
By stretching at a stretch ratio of 1.2 to 8 times, preferably 2 to 6 times, a breathable film having a porosity of 50% or more, low rigidity and good texture can be obtained.

In the case of biaxial stretching, simultaneous or sequential stretching is carried out. At this time, the stretching temperature is from room temperature to the melting point of the resin, the stretching ratio is 1.2 to 8 times, preferably 2 to 6 times, the porosity is 50% or more, the rigidity is low, a breathable film with a good feel Obtainable.

Further, it is effective to perform heat treatment after the uniaxial or biaxial stretching treatment, since a breathable film having excellent dimensional stability can be obtained. The heat treatment can be performed at a temperature in the range of 80 ° C. to the melting point of the film, and is usually performed at a high temperature for a short time.

Among the breathable films of the present invention, those having a porosity of 50% or more have good air permeability and moisture permeability,
In addition, it is preferable in that it has excellent texture, and the porosity is 6
It is preferably 0 to 80%. The breathable film of the present invention preferably has a Young's modulus of 70 to 300 MPa and a tear strength of 40 in the MD direction (longitudinal direction).
Those having N / cm or more are preferable.

The thickness of the breathable film of the present invention is usually
It is about 20 to 200 μm, and is appropriately determined according to the application and the like.

Further, the breathable film of the present invention can be combined with various non-woven fabrics, split fabrics, woven fabrics and the like to improve its strength.

[0068]

EXAMPLES Hereinafter, according to Examples and Comparative Examples of the present invention,
The present invention will be described more specifically.

Reference Example 1 Preparation of Ethylene / 1-Hexene Copolymer [Preparation of Olefin Polymerization Catalyst] 5.0 kg of silica dried at 250 ° C. for 10 hours was suspended in 80 l of toluene. Cooled to 0 ° C. After that, set the temperature in the system to 0
28.7 l of a toluene solution of methylaluminoxane (Al: 1.33 mol / l) was added dropwise over 1 hour while maintaining the temperature at 0 ° C. After reacting at 0 ° C for 60 minutes,
Raise the temperature to 95 ° C over 1.5 hours and maintain the temperature at 2
The reaction was allowed for 0 hours. Then, the temperature was lowered to 60 ° C., and the supernatant was removed by a decantation method to obtain a solid component.

The obtained solid component was washed twice with toluene and then resuspended with 80 l of toluene. Next, a toluene solution of bis (1,3-butylmethylcyclopentadienyl) zirconium dichloride (Zr: 34.0 mm
ol / l) 7.4 l and bis (1,3-dimethylcyclopentadienyl) zirconium dichloride 1.0 l toluene solution (Zr: 28.1 mmol / l)
The mixture was added dropwise at 30 ° C over 30 minutes, and further reacted at 80 ° C for 2 hours. Thereafter, the supernatant was removed and washed twice with hexane to obtain a solid catalyst containing 3.6 mg of zirconium per gram.

[Preparation of Prepolymerized Catalyst] To 85 liters of hexane containing 1.7 mol of triisobutylaluminum, 0.85 kg of the solid catalyst obtained above and 255 g of 1-hexene were added, and ethylene oxide was added at 35 ° C. for 12 hours. Prepolymerization was performed to obtain a prepolymerized catalyst in which 10 g of polyethylene was prepolymerized per 1 g of the solid catalyst. The intrinsic viscosity [η] of this ethylene polymer is 1.74 dl / g.
Met.

[Polymerization] Copolymerization of ethylene and 1-hexene was carried out in the presence of the above-mentioned prepolymerization catalyst using an apparatus in which two continuous fluidized bed gas phase polymerization apparatuses were connected in series to obtain ethylene / 1. A hexene copolymer was obtained. The obtained ethylene / 1-hexene copolymer has a 1-hexene content of 1
4.9 wt%, density 0.900 g / cm ³ , melt flow rate (MFR: ASTM D 12
38-65T, 190 ° C., load 2.16 kg) 12.
It was 0 g / 10 minutes, and the molecular weight distribution (Mw / Mn) measured by GPC was 2.2.

The ethylene / 1-hexene copolymer had a maximum peak temperature (Tm) of an endothermic curve measured by a differential scanning calorimeter (DSC) of 92.1 ° C.,
The amount of n-decane-soluble component (w) at room temperature was 1.9% by weight. Next, regarding the ethylene / 1-hexene copolymer (hereinafter sometimes abbreviated as “A-1”), G
The average number B1 of branches on the high molecular weight side measured by PC-IR analysis was 25.2 / 1000 C (per 1000 carbon atoms), and the average value B2 of branches on the low molecular weight side was 24.
It was 6 / 1000C.

Reference Example 2 Copolymerization of ethylene and 4-methyl-1-pentene was carried out in the presence of a Ziegler type Ti-based polymerization catalyst (a magnesium-supported Ti-based catalyst and alkylaluminum) to obtain ethylene-4-methyl. -1-Pentene copolymer was obtained. Obtained ethylene 4-methyl-
The 1-pentene copolymer has a 4-methyl-1-pentene content of 15.5% by weight and a density of 0.920 g / c.
m ³ and the melt flow rate (MFR: ASTM
D 1238-65T, 190 ° C, load 2.16kg)
Was 20 g / 10 minutes, and the molecular weight distribution (Mw / Mn) measured by GPC was 2.9.

This ethylene-4-methyl-1-pentene copolymer had a maximum peak temperature (Tm) of 12 on the endothermic curve measured by a differential scanning calorimeter (DSC).
The temperature was 4.1 ° C., and the n-decane-soluble component amount fraction (w) at room temperature was 5.9% by weight. This ethylene 4-
Regarding the methyl-1-pentene copolymer (hereinafter, sometimes abbreviated as "A-2"), B1 measured by GPC-IR analysis is 18.5 / 1000C (per 1000 carbon atoms), and B2 is It was 9.9 / 1000C.

(Example 1) 50 parts by weight of ethylene / 1-hexene copolymer (A-1) and 50 parts of calcium carbonate (manufactured by Takehara Chemical Co., Ltd., WS # 1500, average particle size: 2.5 μm)
The resin composition was prepared by stirring and mixing parts by weight with a tumbler. The obtained resin composition was supplied to a twin-screw extruder (TEX-44, screw diameter: 44 mm, manufactured by Nippon Steel Co., Ltd.) and melt-kneaded at a cylinder temperature of 120/140/190 ° C., and then a die temperature: 220. Extruded from T-die at ℃, take-off speed: 6m / min, thickness 500
A film of μm was obtained. The obtained film was uniaxially stretched at a stretching temperature of 100 ° C., a stretching speed of 15 m / min, and a stretching ratio of 4 times to obtain a breathable film having a thickness of 200 μm. The obtained breathable film was subjected to a tensile test (yield stress, tensile strength at break, elongation at break, Young's modulus measurement), Elmendorf tear test (measurement of tear strength),
It was subjected to a moisture permeability test (measurement of moisture permeability and moisture permeability coefficient), an air permeability test (measurement of air permeability), and the porosity was measured. The tensile test and the Elmendorf tear test were performed in both MD and TD. The results are shown in Table 1.

Tensile Test (Measurement of Stress at Yield, Tensile Strength at Break, Elongation at Break, and Young's Modulus) The test was carried out in accordance with JIS K7113 and JIS K6778.

Elmendorf Tear Test Measured in accordance with JIS P8116.

Moisture Permeability Test It was conducted according to JIS P0208.

Air permeability test It was conducted in accordance with JIS P8117.

Measurement of Porosity The porosity was calculated according to the following formula. Porosity = [(d ₀ −d) / d ₀ ] × 100 d ₀ : Density of resin composition, d: Density of stretched film

(Comparative Example 1) Instead of the ethylene / 1-hexene copolymer (A-1) obtained in Reference Example 1, an ethylene-4-methyl-1-pentene copolymer obtained in Reference Example 2 was used. A breathable film was produced in the same manner as in Example 1 using the combined product (A-2), and a tensile test (measurement of yield stress, tensile strength at break, elongation at break, Young's modulus), Elmendorf tear test ( Tear strength measurement), moisture permeability test (moisture permeability, moisture permeability coefficient measurement), air permeability test (measurement of air permeability), and porosity was measured. The results are shown in Table 1.

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[Table 1]

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INDUSTRIAL APPLICABILITY The breathable film of the present invention is excellent in breathability and has appropriate elasticity, so that it has excellent texture and excellent mechanical strength such as tensile strength and tear strength. Therefore, the breathable film of the present invention is suitable for applications such as sanitary materials such as disposable diapers and sanitary products, medical applications, various filters, and agricultural material applications.

Claims (6)

[Claims] 1. A polyolefin resin (A) containing an ethylene / α-olefin copolymer as a main component and a filler (B) at a weight ratio of (A) / (B) of 30/70 to 80 /. 20
Is a breathable film obtained by stretching a film or sheet made of a resin composition containing the ethylene / α-olefin copolymer (1) having a melt flow rate (MFR) of 5 to 25 g / In the range of 10 minutes,
(2) The density (d) is 0.88 to 0.92 g / cm ³ , and (3) the molecular weight distribution (Mw) measured by GPC.
/ Mn) is in the range of 1.5 to 3.5, and (4) 23 ° C.
When the amount of n-decane-soluble component (W (% by weight)) and the density (d) in MFR are MFR ≦ 10 g / 10 minutes, W <80 × exp [−100 (d−0.88)] + 0.
When 1 MFR> 10 g / 10 minutes, W <80 × (MFR-9) ^0.26 × exp [−100 (d
-0.88)] + 0.1, and (5) the average value of the number of branches on the high molecular weight side in the chromatogram measured by GPC-IR is B1, and the average of the number of branches on the low molecular weight side. When the value is B2, the breathable film satisfies B1 ≧ B2. 2. The ethylene / α-olefin copolymer is obtained by copolymerizing ethylene and an α-olefin having 4 to 12 carbon atoms in the presence of a metallocene catalyst. The breathable film described. 3. The ventilation according to claim 1, wherein the polyolefin resin (A) is a mixed resin containing 100 parts by weight of an ethylene / α-olefin copolymer and 20 parts by weight or less of a high-pressure low-density polyethylene. Sex film. 4. The polyolefin resin (A) comprises (1)
Melt flow rate (MFR) is 5 to 25 g / 10 minutes, and (2) density (d) is 0.88 to 0.92 g / cm.
³ , (3) the molecular weight distribution (Mw / Mn) measured by GPC is in the range of 1.5 to 3.5, and (4)
Amount of n-decane-soluble component at 23 ° C (W (% by weight))
And the density (d) is MFR ≦ 10 g / 10 minutes, W <80 × exp [−100 (d−0.88)] + 0.
When 1 MFR> 10 g / 10 minutes, W <80 × (MFR-9) ^0.26 × exp [−100 (d
-0.88)] + 0.1, and (5) the average value of the number of branches on the high molecular weight side in the chromatogram measured by GPC-IR is B1, and the average of the number of branches on the low molecular weight side. The breathable film according to any one of claims 1 to 3, wherein B1 ≧ B2 when the value is B2. 5. The breathable film according to claim 1, which has a Young's modulus of 70 to 300 MPa. 6. A tear strength of 40 N / in the MD direction (longitudinal direction).
The breathable film according to any one of claims 1 to 5, which has a size of not less than cm.