JP2001261868A - Porous film and process for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous film which causes no defects even when it is wound up at a high speed, and a process for producing the same. SOLUTION: The porous film comprises 100 pts.wt. of a resin comprising 20-98 wt.% of an ethylene/α-olefin copolymer which has an MI of 0.5-10 g/10 min. and a density of 0.905-0.945 g/cm3 and is produced by using a metallocene catalyst, 1-79 wt.% of an ethylene/α-olefin copolymer which has an MI of 0.5-10 g/10 min. and a density of 0.905-0.945 g/cm3 and is produced by using a Ziegler catalyst and 1-8 wt.% of a branched low-density polyethylene which has an MI of 0.1-10 g/10 min. and a density of 0.91-0.935 g/cm3, and 50-500 pts.wt. of an inorganic filler, and has a melt tension of 0.5-4 g and a melt ductility (elongation) of at least 800%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a porous film and a method for producing the same. Specifically, a porous film molded from a resin composition containing a specific mixed resin and a method for producing the same, wherein the porous film has extremely few defects such as tears even when wound at a high speed after molding. It relates to the manufacturing method.

[0002]

2. Description of the Related Art Heretofore, a film in which an inorganic filler, various oils, waxes, etc. are added to a polyolefin resin is stretched in at least one axial direction, and voids are generated by causing interfacial peeling between the inorganic filler and the polyolefin. Many methods for producing a porous film to be generated have been proposed (for example, Japanese Patent Application Laid-Open Nos. 7-26076 and 9-2).
No. 5372). Since these porous films have a large number of minute voids inside, they do not transmit liquid while having high moisture permeability. Taking advantage of this property, it has been widely used in various fields such as sanitary materials such as disposable paper diapers, building materials, reflective films, and battery separators.

[0003] However, a problem in forming such a film containing a large amount of inorganic filler is that high-speed film formation is difficult. That is, the drawdown property is deteriorated due to the inclusion of the inorganic filler, and the film is broken or broken at the time of high-speed film formation. For these reasons, in the prior art, the winding speed at a line speed of about 160 m / min was the limit. Therefore, productivity was low. This tendency is remarkable when the thickness is thin, for example, the basis weight is 20 g /
In the case of about m ^2, it has been conventionally difficult to form a porous film having uniform characteristics at high speed.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a conventional product which is free from defects such as tears even when it is wound at a high speed, and which has the original characteristics such as moisture permeability. Another object of the present invention is to provide a porous film maintained at the same level as above, and a method for producing the same.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that ethylene-α-olefin copolymer (A) produced using a metallocene catalyst and ethylene-α-olefin copolymer produced using a Ziegler catalyst. The above problem is solved by using as a raw material a resin composition in which a predetermined amount of an inorganic filler is added to a mixed resin containing a specific amount of each of the α-olefin copolymer (B) and the branched low-density polyethylene (C). They have found that they can do this and have reached the present invention.

That is, the present invention provides a melt index of 0.5 to 10 g / 10 min and a density of 0.905 to 0.945.
g / cm ³ , 20 to 98% by weight of an ethylene-α-olefin copolymer (A) produced using a metallocene catalyst, a melt index of 0.5 to 10 g / 10 min, and a density of 0.905 to 0.5. 945 g / cm ³ , 1 to 79% by weight of an ethylene-α-olefin copolymer (B) produced using a Ziegler catalyst, a melt index of 0.1 to 10 g / 10 min, and a density of 0.91 to 0.935
g / cm ³ branched low density polyethylene (C)
A porous film formed from a resin composition containing 50 to 500 parts by weight of an inorganic filler (D) with respect to 100 parts by weight of a resin containing 8% by weight, at a temperature of 190 ° C. and a take-up speed of 200 m / min. Melt tension is 0.5-4
g, a porous film having a melt elongation of at least 800%.

As a preferred resin composition used in the present invention, the resin composition contains 0.1 to 12 parts by weight of at least one compound selected from hardened castor oil and dehydrated castor oil based on 100 parts by weight of the mixed resin. Things.

The above-mentioned porous film according to the present invention is obtained by kneading and melting the resin composition at 180 to 280 ° C. to form a film, and then forming the film at least in one axial direction within a temperature range from room temperature to the softening point of the resin. Stretched 1-4 times,
Then, after cooling to a temperature near room temperature, the maximum speed 30
It is manufactured by winding at 0 m / min. Preferably, it is manufactured by heat-treating for 0.1 to 100 seconds after stretching in a temperature range from the softening temperature of the resin to the melting point.

[0009] The porous film of the present invention comprises the above (A)
It is characterized in that a mixed resin containing the three resins (B) and (C) at a specific weight ratio is used as a main raw material. Therefore, even if the film is wound at a maximum speed of 300 m / min after the film is formed, there is no defect such as tear, and the original characteristics such as the moisture permeability are maintained at the same level or higher than the conventional product. It is a porous film.

Incidentally, the melt tension and the melt elongation in the present invention mean values measured by the method described in Examples described later.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The porous film of the present invention is a resin composition containing a mixed resin containing three types of polyolefin resins (A), (B) and (C) at a specific weight ratio, and an inorganic filler, preferably a third component. Hardened castor oil, dehydrated castor oil, or a compound containing a resin composition containing a mixture thereof in a biaxial or uniaxial kneader, and then formed into a film by melt molding, the resulting film uniaxial or biaxial It is manufactured by stretching at a predetermined magnification in the direction.

The ethylene-α-olefin copolymer (A) polymerized using a metallocene catalyst used in the present invention is an ethylene-α-olefin copolymer containing 0.5 to 10 mol% of α-olefin units. Coalescence. Among them, the melt index is 0.5 to 10 g / 10
And those having a density of 0.905 to 0.945 g / cm ³ are preferable. More preferably, the melt index is 1 to 10 g / 10 min, and the density is 0.905 to 0.93 g / min.
cm ³ . If the density exceeds the above range, the film becomes hard, which is not preferable. If the density is lower than the above range, the air permeability deteriorates, and the possibility of blocking before and during molding increases. In addition, the relative intensity peak of the elution curve obtained by the temperature rise elution fractionation test showed an elution temperature of 70-9
One in the range of 0 ° C, one in the range over 90 ° C,
In addition, the ratio of the weight average molecular weight to the number average molecular weight is 1.
An ethylene-α-olefin copolymer having a ratio of 5 to 5.5 is preferred.

The α-olefin of the ethylene-α-olefin copolymer
As the olefin unit, 1-butene, 1-pentene,
Examples include 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, and 1-nonene. 1-hexene, 4-methyl-1-pentene and 1-octene are more preferred. As commercially available products, manufactured by Mitsui Chemicals, Inc., trade names: Evolu SP1540 and Evolu SP204
0 and the same Evolution SP2520. Less than,
The above copolymer (A) is referred to as metallocene-catalyzed polyethylene.

Examples of the ethylene-α-olefin copolymer (B) polymerized using a Ziegler catalyst include ethylene-α-olefin copolymers containing 0.5 to 10 mol% of α-olefin units. Among them, the melt index is 0.5 to 10 g / 10 min, and the density is 0.905 to
It is preferably 0.945 g / cm ³ . More preferably, it has a melt index of 1 to 10 g / 10 min and a density of 0.91 to 0.93 g / cm ³ . If the density exceeds the above range, the film becomes hard and the tactile sensation is unfavorable. If the density below the above is added, the air permeability deteriorates, which is not preferable as the air permeable film. Further, the possibility of blocking during molding increases.
The ratio of the weight average molecular weight to the number average molecular weight is 2.
An ethylene-α-olefin copolymer having a ratio of 5 to 5.5 is preferred. As commercially available products, manufactured by Mitsui Chemicals, Inc., trade names: Ultzex 2021L, 20100J, 2100
520F and the like. Hereinafter, the copolymer (B) is referred to as Ziegler-catalyzed polyethylene.

Further, a branched low-density polyethylene (C)
Is a resin synthesized by a high pressure method, and may be an autoclave method or a tubular method. Among them, the melt index is 0.1 to 10 g /
Those having a density of 0.91 to 0.935 g / cm ³ for 10 minutes are preferred. More preferably, the melt index is 0.3 to 8 g / 10 min, and the density is 0.915 to 0.93 g.
/ Cm ³ . Further, a copolymer containing 6% by weight or less of vinyl acetate units may be used as the copolymer. Commercial products manufactured by Mitsui Chemicals, Inc., trade names: Mirason 14, F9
67 and 102. Hereinafter, the polyethylene (C) is referred to as a branched low-density polyethylene.

The resin forming the porous film of the present invention is composed of a mixture of the metallocene-catalyzed polyethylene (A), the Ziegler-catalyzed polyethylene (B), and the branched low-density polyethylene (C). In the present invention, it is particularly important that the metallocene-catalyzed polyethylene and the Ziegler-catalyzed polyethylene are mixed. Ziegler-catalyzed polyethylene (B) is very useful as a base material for a porous film, but generally has poorer high-speed film-forming properties than metallocene-catalyzed polyethylene (A). Therefore, the metallocene-catalyzed polyethylene (A) is used. However, this polyethylene has poor compatibility with a molding machine and causes problems in thickness unevenness and uniform stretchability. The present invention solves such problems relating to moldability by using a Ziegler-catalyzed polyethylene (B) in combination. Further, it is necessary to add a small amount of branched low-density polyethylene (C) in order to ensure uniform stretchability and thickness accuracy. However, if the added amount of (C) is too large, defects such as breakage and breakage of the film occur at the time of high-speed film formation.

In the present invention, taking into account such points, the metallocene-catalyzed polyethylene (A) is 20 to 98% by weight, the Ziegler-catalyzed polyethylene (B) is 1 to 79% by weight, and the branched low-density polyethylene (C) is 1 to 8%. A mixed resin containing a weight percentage of weight% is employed. More preferably,
It is a mixed resin containing 20 to 95% by weight of (A), 3 to 79% by weight of (B), and 1 to 4% by weight of (C).

The inorganic filler contained in the porous film of the present invention includes calcium carbonate, barium sulfate, calcium sulfate, barium carbonate, magnesium hydroxide, aluminum hydroxide, zinc oxide, magnesium oxide, titanium oxide, silica, talc. And the like. Among them, calcium carbonate and barium sulfate are preferred, and calcium carbonate is most preferred. These inorganic fillers may be used alone or as a mixture of two or more. The composition ratio of the polyethylene-based mixed resin and the inorganic filler is preferably 50 to 500 parts by weight based on 100 parts by weight of the resin. More preferably, the amount of the inorganic filler is 100 to 250 parts by weight based on 100 parts by weight of the resin part.

These inorganic fillers may be surface-treated to improve dispersibility in polyethylene, promote separation at the interface with the resin, and prevent absorption of moisture from the outside. As the surface treatment agent, those capable of making the surface hydrophobic by coating the surface of the inorganic filler are preferable, and examples thereof include higher fatty acids such as stearic acid and lauric acid, and metal salts thereof.

The porous film of the present invention contains the above three kinds of polyethylene-based mixed resins and an inorganic filler.
If necessary, a stretching aid may include hardened castor oil, dehydrated castor oil, or a mixture thereof. Commercial products of hardened castor oil include Ito Oil Co., Ltd., trade name: Custer Wax and the like. Examples of commercially available dehydrated castor oil include Ito Oil Co., Ltd., trade name: DCO, and the like. If the amount of the stretching aid is too large, there is a problem that the stretching aid bleeds out of the film over time. From such a viewpoint, the amount of these additives is 1
It is preferably 0.1 to 12 parts by weight with respect to 00 parts by weight. More preferably, it is 1 to 8 parts by weight.

The porous film of the present invention contains a stabilizer, an antioxidant, a coloring agent, a light stabilizer, a flame retardant, an antistatic agent, an antiblocking agent, a deodorant, as long as the object of the present invention is not hindered. Other additives such as antibacterial agents may be added.

Next, a method for producing the porous film of the present invention will be described. The above-mentioned polyethylene-based mixed resin, inorganic filler, and other additives as necessary are mixed using a mixer such as a Henschel mixer, a super mixer, a tumbler mixer, and the like, and then mixed using a normal single-screw or twin-screw extruder. Kneaded and pelletized. The pellets are then placed at 200-280 ° C, preferably at 22 ° C.
Melting and film formation are performed at 0 to 260 ° C. by using a known molding machine such as an extrusion molding machine equipped with a T-die or the like, or an inflation molding machine equipped with a circular die. The raw material can be directly formed without being pelletized.

The formed film is stretched in a uniaxial direction or a biaxial direction by 1.1 to 4 times by a known method such as a roll method or a tenter method to separate the interface between the polyethylene resin and the inorganic filler. To produce a porous film. Stretching may be performed in one step or in multiple steps. The stretching ratio has a great influence on the physical properties of the film. When the ratio is less than 1.1 times, interfacial separation between the resin and the inorganic filler is not sufficient, and satisfactory air permeability cannot be obtained. When the stretching ratio exceeds 4 times, the tensile elongation at break of the film decreases. Considering the above reasons, the stretching ratio is preferably 1.1 to 4 times. More preferably, it is 1.2 to 2.7 times. The stretching temperature is preferably in the range of room temperature to the softening point of the resin. After stretching, if necessary, a heat setting treatment may be performed to stabilize the form of the obtained film. The heat setting treatment is preferably performed in a temperature range from the softening point of the resin to the melting point but lower than the melting point for 0.1 to 100 seconds. Here, the softening point of the resin refers to JIS K-676.
This is a value measured by the method defined as 0.

After the film is stretched as described above or, if necessary, is subjected to a heat setting treatment, the film is cooled to a temperature near room temperature using a cooling roll or the like. After that, it is wound at high speed. In the present invention, the maximum speed 3
It is possible to wind at 00 m / min. Conventionally, in order to suppress the occurrence of film tearing, etc., at most 160 m /
Minutes were the limit. By employing the resin composition according to the present invention, even when the film is wound at a maximum speed of 300 m / min, occurrence of defects such as tearing of the film can be suppressed.

The physical properties of the porous film produced according to the present invention are as follows: the filling ratio of the inorganic filler, the kind, the particle size, the compounding ratio of the hardened castor oil and the dehydrated castor oil, the stretching conditions (stretching method,
Magnification, stretching temperature, etc.). When the thickness of the film is in the range of 10 to 100 μm, ASTM-E-96 (temperature 40 ° C., relative humidity 6
0%, conditions of the pure water method) are in the range of 500 to 8000 g / m ² · 24 hours. The thickness of the porous film that can be produced by the method of the present invention is not particularly limited, but is usually about 5 to 500 μm, preferably about 10 to 100 μm.

The characteristic properties of the porous film of the present invention include a melt tension of 0.5 to 4 g and a melt elongation of at least 8
That is, it is 00%. The method for measuring the melt tension and the melt elongation will be described in detail in Examples described later. A sample obtained by finely cutting the porous film according to the present invention is melt-extruded at 190 ° C. from a nozzle having a specific diameter, and a take-up speed of 200 m
Per minute, the filamentary melt does not break, the melt tension at this time is 0.5 to 4 g, and the melt elongation is 800% or more. According to the findings of the present inventors, if the melt tension is lower than the above range, stretching unevenness and draw resonance occur, and a good film cannot be formed. On the other hand, if it is higher than the above range, defects such as breakage or breakage of the film occur at the time of high-speed film formation.

The porous film produced according to the present invention has few defects such as tears even when wound at a high speed. In addition, the original properties of the porous film such as air permeability, moisture permeability, texture, and the like are maintained at conventional or higher levels. Therefore, it helps to improve productivity. Backsheets of sanitary materials such as disposable paper diapers and sanitary napkins, medical materials such as surgical gowns, jumpers,
Extremely suitable as medical materials such as rain gear, building materials such as roof waterproofing materials, desiccants, moisture proof materials, deoxidizing materials, disposable warmers, freshness preserving packaging, packaging materials such as food packaging, and materials such as battery separators. Can be used.

[0028]

Embodiments of the present invention will be described below in detail. The melt index (hereinafter referred to as MI), melt tension, moisture permeability, and high-speed film-forming property shown in the examples are values measured by the following methods.

(1) MI (g / 10 min) Measured at a temperature of 190 ° C. and a load of 2160 g by the method specified in ASTM D-1238-57T (E).

(2) Melt tension (g) and melt elongation (%) Capillograph 1C manufactured by Toyo Seiki Co., Ltd. is used. 9.55 in diameter
A finely ground porous film is placed in a cylinder having a length of 350 mm and a length of 350 mm and melted at 190 ° C. 15m
The molten resin is extruded at a rate of m / min, and a filament coming out of a capillary having a nozzle diameter of 2.098 mm and a length of 8 mm attached to the lower portion of the cylinder is wound at room temperature. The tension at a winding speed of 200 m / min is measured and defined as a melt tension (melt tension, unit: g). In the case of breakage, the fact shall be specified. Further, the diameter of the filament wound at 200 m / min is measured, and the cross-sectional area ratio to the capillary diameter is defined as melt elongation (melt elongation, unit:%). The melt elongation is calculated by the following equation. Melt elongation (%) = (capillary diameter / filament diameter)
² .

(3) Moisture permeability (g / m ² · 24 hours) Porous film sample [MD: 10 cm, TD: 10c]
m] are sampled and measured under the conditions of a temperature of 40 ° C., a relative humidity of 60% and a pure water method based on a method prescribed in ASTM E-96, and an average value thereof is calculated. Measurement time is 24
Time.

(4) Evaluation of high-speed film-forming property One hour when extruding from a T-die and setting the peripheral speed of the casting roll to 150 m / min, winding speed to 300 m / min, film width to 0.6 m, and film thickness to 20 μm. The number of defects detected at the same time is counted using a defect detector. The defect detector is a product of Kowa Spinning Co., Ltd., focal length 50 mm, F =
CCD camera with 1.4 lens (2048bi)
(t, 20 MHz) is used to detect a defect. If the number of defects per hour is 10 or less, it is determined that the high-speed film forming property is “excellent”, if 11 to 100, it is “poor”, and if it is 101 or more, “very poor”. Here, a defect means a defect such as a tear having a length of 1 mm or more.

Example 1 Metallocene catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Evolue SP2040, density: 0.920 g / c)
m ³ , MI = 4.0 g / 10 min) 67 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 20100J, density: 0.920 g / c)
m ³ , MI = 8.5 g / 10 min) 29 parts by weight, branched low density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason 14, density 0.919 g / cm ³ , MI = 5.1 g /
10 minutes) 4 parts by weight, 180 parts by weight of calcium carbonate (trade name: SST-40-5, manufactured by Dowa Calfine Co., Ltd.)
5 parts by weight of hardened castor oil (manufactured by Ito Oil Co., Ltd., trade name: Custer Wax) and 2.5 parts by weight of dehydrated castor oil (manufactured by Ito Oil Co., Ltd., trade name: DCO) are mixed with a tumbler mixer. After mixing, the mixture was uniformly kneaded at 230 ° C. using a tandem type extruder and processed into pellets. The film was formed by melt extrusion at 240 ° C. using an extruder equipped with a T-die. Casting roll speed 150m / min, 8
After preheating the film at 0 ° C., it was uniaxially stretched twice in the machine direction. After cooling to a temperature near room temperature, it is taken off at a line speed of 300 m / min to form a roll.
A porous film having a width of 0.6 m and a thickness of 20 μm was obtained. The melt tension, moisture permeability, and high-speed film forming property of the obtained porous film were evaluated by the above methods. The moisture permeability is 3500 g / m ²
-It was 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Example 2 Metallocene catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Evolue SP2040, density: 0.920 g / c)
m ³ , MI = 4.0 g / 10 min) 93 parts by weight, Ziegler catalyst polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultoxex 2021L, density: 0.920 g / cm ³ ,
MI = 2.0 g / 10 min) 5 parts by weight, branched low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason 10)
2, density 0.921 g / cm ³ , MI = 0.35 g / 1
0 minutes) 2 parts by weight, 180 parts by weight of calcium carbonate (trade name: SST-40-5, manufactured by Dowa Calfine Co., Ltd.)
Except for using 5 parts by weight of hydrogenated castor oil and 2 parts by weight of dehydrated castor oil, the method of producing and evaluating the film was the same as in Example 1.
The same as above. The moisture permeability was 3100 g / m ² · 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Example 3 Metallocene-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Evolue SP1540, density: 0.915 g / c)
m ³ , MI = 4.0 g / 10 min), 86 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L, density: 0.920 g / cm ³⁾
MI = 2.0 g / 10 min) 11 parts by weight, ridged low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason F96)
7, density 0.918 g / cm ³ , MI = 1.0 g / 10
Min) 3 parts by weight, 180 parts by weight of calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5)
4.5 parts by weight of hydrogenated castor oil and 2.5 parts of dehydrated castor oil
Except that parts by weight were used, the production and evaluation methods for the film were the same as in Example 1. Moisture permeability 3100g / m ² · ²
4 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Example 4 Metallocene-catalyzed polyethylene (trade name: Evolue SP1540, manufactured by Mitsui Chemicals, Inc., density: 0.915 g / c)
m ³ , MI = 4.0 g / 10 min), 72 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L, density: 0.920 g / cm ³⁾
MI = 2.0 g / 10 min) 25 parts by weight, branched low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason F9)
67, density 0.918 g / cm ³ , MI = 1.0 g / 1
0 minutes) 3 parts by weight, 180 parts by weight of calcium carbonate (trade name: SST-40-5, manufactured by Dowa Calfine Co., Ltd.)
4.5 parts by weight of hydrogenated castor oil and 2.5 parts of dehydrated castor oil
Except that parts by weight were used, the production and evaluation methods for the film were the same as in Example 1. Moisture permeability 3200g / m ² · ²
4 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Example 5 Metallocene catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Evolue SP1540, density: 0.915 g / c)
m ³ , MI = 4.0 g / 10 min), 48 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultrazex 2021L, density: 0.920 g / cm ³⁾
MI = 2.0 g / 10 min) 48 parts by weight, branched low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason F9)
67, density 0.918 g / cm ³ , MI = 1.0 g / 1
0 minutes) 4 parts by weight, 180 parts by weight of calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5)
4.5 parts by weight of hydrogenated castor oil and 2.5 parts of dehydrated castor oil
Except that parts by weight were used, the production and evaluation methods for the film were the same as in Example 1. Moisture permeability 3300g / m ² · ²
4 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Example 6 Metallocene-catalyzed polyethylene (trade name: Evolue SP1540, manufactured by Mitsui Chemicals, Inc., density: 0.915 g / c)
m ³ , MI = 4.0 g / 10 min), 25 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L, density: 0.920 g / cm ³ ,
MI = 2.0 g / 10 min) 72 parts by weight, branched low density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason F9)
67, density 0.918 g / cm ³ , MI = 1.0 g / 1
0 minutes) 3 parts by weight, 180 parts by weight of calcium carbonate (trade name: SST-40-5, manufactured by Dowa Calfine Co., Ltd.)
4.5 parts by weight of hydrogenated castor oil and 2.5 parts of dehydrated castor oil
Except that parts by weight were used, the production and evaluation methods for the film were the same as in Example 1. Moisture permeability 2600g / m ² · ²
4 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Example 7 Metallocene-catalyzed polyethylene (trade name: Evolue SP2040, manufactured by Mitsui Chemicals, Inc., density: 0.920 g / c)
m ³ , MI = 4.0 g / 10 min), 40 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L, density: 0.920 g / cm ³ ,
MI = 2.0 g / 10 min) 56 parts by weight, branched low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason 2)
7, density 0.918 g / cm ³ , MI = 2.0 g / 10
Min) 4 parts by weight, 180 parts by weight of calcium carbonate (trade name: SST-40-5, manufactured by Dowa Calfine Co., Ltd.)
Except that 3.8 parts by weight of hydrogenated castor oil was used, the method of producing and evaluating the film was the same as in Example 1. Moisture permeability is 2
700 g / m ² · 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Example 8 Metallocene catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Evolue SP1540, density: 0.915 g / c)
m ³ , MI = 4.0 g / 10 min), 22 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L, density: 0.920 g / cm ³⁾
(MI = 2.0 g / 10 min) 77 parts by weight, branched low density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason 10)
2, density 0.921 g / cm ³ , MI = 0.35 g / 1
0 minutes) 1 part by weight, 180 parts by weight of calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5)
Hardened castor oil 2.5 parts by weight and dehydrated castor oil 4.5
Except that parts by weight were used, the production and evaluation methods for the film were the same as in Example 1. Moisture permeability 2600g / m ² · ²
4 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Example 9 Metallocene-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Evolue SP0510, density: 0.905 g / c)
m ³ , MI = 1.0 g / 10 min), 40 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: ULTOZEX 1030L, density: 0.91 g / cm ³ , M)
56 parts by weight, branched low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason 10)
2, density 0.921 g / cm ³ , MI = 0.35 g / 1
0 minutes) 4 parts by weight, 180 parts by weight of calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5)
Except that 7 parts by weight of hydrogenated castor oil was used, the method of producing and evaluating the film was the same as in Example 1. Water vapor permeability is 240
0 g / m ² · 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Comparative Example 1 (Evolu SP154, trade name, manufactured by Mitsui Chemicals, Inc.)
0, density: 0.915 g / cm ³ , MI = 4.0 g / 1
0 minutes) 70 parts by weight, Ziegler-catalyzed polyethylene (trade name: Ultzex 2021L, manufactured by Mitsui Chemicals, Inc., density: 0.920 g / cm ³ , MI = 2.0 g / 10 minutes)
20 parts by weight, branched low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason F967, density 0.918)
g / cm ³ , MI = 1.0 g / 10 min), 10 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: S)
ST-40-5) Except for using 180 parts by weight, 5 parts by weight of hydrogenated castor oil, and 2.5 parts by weight of dehydrated castor oil,
The method for producing and evaluating the film was the same as in Example 1.
The water vapor transmission rate was 2800 g / m ² · 24 hours. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2]. High melt tension and many disadvantages during high-speed film formation.

Comparative Example 2 Metallocene-catalyzed polyethylene (trade name: Evolue SP2040, manufactured by Mitsui Chemicals, Inc., density: 0.920 g / c)
m ³ , MI = 4.0 g / 10 min), 40 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 20205J, density: 0.920 g / c)
m ³ , MI = 20 g / 10 min) 57 parts by weight, branched low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason 27, density 0.918 g / cm ³ , MI = 2.0 g / 1)
0 minutes) 3 parts by weight, 180 parts by weight of calcium carbonate (trade name: SST-40-5, manufactured by Dowa Calfine Co., Ltd.)
Except for using 2.5 parts by weight of hydrogenated castor oil and 5 parts by weight of dehydrated castor oil, the method of producing and evaluating the film was the same as in Example 1. Draw resonance occurred between the T-die and the casting roll, and it was not possible to form a film having a uniform thickness and moisture permeability. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Comparative Example 3 Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L, density: 0.920 g /
cm ³ , MI = 2.0 g / 10 min) 96 parts by weight, branched low density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason F967, density 0.918 g / cm ³ , MI = 1.
Production and evaluation of the film except that 4 parts by weight of 0 g / 10 min), 180 parts by weight of calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5), and 5 parts by weight of hydrogenated castor oil were used. The method was the same as in Example 1. The water vapor transmission rate was 2700 g / m ² · 24 hours. The melt tension of the film was as high as 4.5 g, and many defects occurred during high-speed film formation. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Comparative Example 4 Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L, density: 0.920 g /
cm ³ , MI = 2.0 g / 10 min) 97 parts by weight, branched low-density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason 102, density 0.921 g / cm ³ , MI = 0.3)
5 g / 10 min) 3 parts by weight, 180 parts by weight of calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-40-5), 3 parts by weight of hydrogenated castor oil, 3 parts by weight of dehydrated castor oil The method for producing and evaluating the film is described in Example 1.
The same as above. The moisture permeability was 2600 g / m ² · 24 hours. The melt tension of the film was measured.
At a take-off speed of m / min, the melt tension could not be measured due to rupture. Many defects occurred during high-speed film formation. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Comparative Example 5 Metallocene-catalyzed polyethylene (manufactured by Dow Chemical Company, trade name: Affinity EG8100, density 0.87 g /
cm ³ , MI = 1.0 g / 10 min), 25 parts by weight, Ziegler catalyst polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultrazex 2021L, density: 0.920 g / c)
m ³ , MI = 2.0 g / 10 min) 68 parts by weight, branched low density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason 14, density 0.919 g / cm ³ , MI = 5.1 g /
The production and evaluation methods for the film were the same as in Example 1 except that 7 parts by weight for 10 minutes) and 180 parts by weight of calcium carbonate (trade name: SST-40-5, manufactured by Dowa Calfine Co., Ltd.) were used. The moisture permeability was 1500 g / m ² · 24 hours. The film is soft and has a good texture but low moisture permeability. The melt tension of the film was 4.3 g at a take-up speed of 200 m / min, and many defects occurred during high-speed film formation. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Comparative Example 6 Metallocene-catalyzed polyethylene (trade name: Evolue SP1540, manufactured by Mitsui Chemicals, Inc., density: 0.915 g / c)
m ³ , MI = 4.0 g / 10 min) 98 parts by weight, branched low density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason 14, density 0.919 g / cm ³ , MI = 5.1 g /
10 minutes) 2 parts by weight, 180 parts by weight of calcium carbonate (trade name: SST-40-5, manufactured by Dowa Calfine Co., Ltd.)
Except for using 12 parts by weight of dehydrated castor oil, the method of producing and evaluating the film was the same as in Example 1. When the film was formed at a high speed, draw resonance occurred between the T-die and the casting roll, and a film having a uniform thickness and moisture permeability could not be formed. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Comparative Example 7 Metallocene-catalyzed polyethylene (trade name: Evolue SP2040, manufactured by Mitsui Chemicals, Inc., density: 0.920 g / c)
m ³ , MI = 4.0 g / 10 min), 7 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 2021L, density: 0.920 g / cm ³ , M
I = 2.0 g / 10 min) 85 parts by weight, branched low density polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Mirason 10)
2, density 0.921 g / cm ³ , MI = 0.35 g / 1
0 minutes) 8 parts by weight, 180 parts by weight of calcium carbonate (trade name: SST-40-5, manufactured by Dowa Calfine Co., Ltd.)
Except that 8 parts by weight of hydrogenated castor oil and 3 parts by weight of dehydrated castor oil were used, the method for producing and evaluating the film was the same as in Example 1.
The same as above. The water vapor transmission rate was 2700 g / m ² · 24 hours. The melt tension of the film was as high as 4.8 g, and many defects at high speed occurred. Table 1 shows the composition of the resin composition,
The results obtained are shown in [Table 2].

Comparative Example 8 Metallocene-catalyzed polyethylene (trade name: Evolue SP2040, manufactured by Mitsui Chemicals, Inc., density: 0.920 g / c)
m ³ , MI = 4.0 g / 10 min), 40 parts by weight, Ziegler-catalyzed polyethylene (manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 20100J, density: 0.920 g / c)
m ³ , MI = 8.5 g / 10 min) 60 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST-)
40-5) Except for using 180 parts by weight, 6 parts by weight of hydrogenated castor oil, and 6 parts by weight of dehydrated castor oil, the method of producing and evaluating the film was the same as in Example 1. When the film was formed at a high speed, draw resonance occurred between the T-die and the casting roll, and a film having a uniform thickness and moisture permeability could not be formed. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

Comparative Example 9 Metallocene-catalyzed polyethylene (trade name: Evolue SP0510, manufactured by Mitsui Chemicals, Inc., density: 0.905 g / c)
m ³ , MI = 1.0 g / 10 min) 100 parts by weight, calcium carbonate (manufactured by Dowa Calfine Co., Ltd., trade name: SST)
-40-5) The method of producing and evaluating the film was the same as in Example 1, except that 180 parts by weight and 9 parts by weight of hydrogenated castor oil were used. The water vapor transmission rate was 750 g / m ² · 24 hours. The melt tension of the film was as high as 5.2 g, and many defects at high speed occurred. The composition of the resin composition is shown in [Table 1], and the obtained results are shown in [Table 2].

[0051]

[Table 1]

<Explanation of reference numerals in [Table 1]> [Table 1]
The symbols A-1 to C-4 indicate the following resins. A-1: manufactured by Mitsui Chemicals, Inc., trade name: Evolution SP1
540, density: 0.915 g / cm^Three, MI = 4.0 g
/ 10 minutes. A-2: manufactured by Mitsui Chemicals, Inc., trade name: Evolu SP2
040, density: 0.920 g / cm^Three, MI = 4.0 g
/ 10 minutes. A-3: manufactured by Mitsui Chemicals, Inc., trade name: Evolu SP0
510, density: 0.905 g / cm^Three, MI = 1.0 g
/ 10 minutes. A-4: Dow Chemical Company, trade name: Affinity
EG8100, density 0.87 g / cm^Three, MI = 1.0
g / 10 minutes B-1: manufactured by Mitsui Chemicals, Inc., trade name: Ultrazex 2
021L, density: 0.920 g / cm^Three, MI = 2.0
g / 10 minutes. B-2: manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX2
0100J, density: 0.920 g / cm^Three, MI = 8.5
g / 10 minutes. B-3: manufactured by Mitsui Chemicals, Inc., trade name: Ultzex 1
030L, density: 0.91 g / cm^Three, MI = 3.6 g
/ 10 minutes. B-4: manufactured by Mitsui Chemicals, Inc., trade name: ULTZEX2
0205J, density: 0.920 g / cm^Three, MI = 20g
/ 10 minutes. C-1: manufactured by Mitsui Chemicals, Inc., trade name: Mirason 102,
Density: 0.921 g / cm^Three, MI = 0.35 g / 10
Minutes. C-2: manufactured by Mitsui Chemicals, Inc., trade name: Mirason F96
7, Density: 0.918 g / cm^Three, MI = 1.0 g / 1
0 minutes. C-3: manufactured by Mitsui Chemicals, Inc., trade name: Mirason 27, Mitsuki
Degree: 0.918 g / cm ^Three, MI = 2.0 g / 10 min. C-4: manufactured by Mitsui Chemicals, Inc., trade name: Mirason 14, Mitsuki
Degree: 0.919 g / cm ^Three, MI = 5.1 g / 10 min.

[0053]

[Table 2]

[0054]

The porous film of the present invention has a maximum speed of 3
The porous film has no defects such as breakage even when wound at a speed of 00 m / min, and maintains the original characteristics such as moisture permeability at the same level as conventional products. Back sheets of sanitary materials such as disposable diapers and sanitary napkins, medical materials such as surgical gowns, medical materials such as jumpers and rain gear, construction materials such as roof waterproofing materials, desiccants, moisture proof materials, and deoxidizing materials It can be used very suitably as a packaging material such as disposable warmers, freshness preserving packaging, food packaging, etc., and a battery separator material.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 105: 04 B29K 105: 04 105: 16 105: 16 B29L 7:00 B29L 7:00 (72) Inventor Hirobumi Zenko 2-1 Tango-dori, Minami-ku, Nagoya-shi, Aichi, Japan Mitsui Chemicals, Inc. (72) Inventor Shigeru Yano 2-1 Tango-dori, Minami-ku, Nagoya, Aichi, Japan Mitsui Chemicals, Inc. Mitsui Chemicals, Inc. 3 Chikusa Beach, Ichihara City, Chiba Prefecture (72) Inventor Taro Ichikawa 2-1 Tango-dori, Minami-ku, Nagoya-shi, Aichi Mitsui Chemicals, Inc.

Claims (9)

[Claims] 1. Melt index 0.5 to 10 g / 1
0 min, density 0.905 to 0.945 g / cm ³ ,
Ethylene-α-olefin copolymer (A) produced using a metallocene catalyst, 20 to 98% by weight, melt index 0.5 to 10 g / 10 min, density 0.905 to 0.
Ethylene-α-olefin copolymers (B) 1 to 7 produced at 945 g / cm ³ using a Ziegler catalyst
9% by weight and a melt index of 0.1 to 10 g /
10 minutes, 100 to 100 parts by weight of a resin containing 1 to 8% by weight of a branched low-density polyethylene (C) having a density of 0.91 to 0.935 g / cm ³ , and 50 to 500 parts by weight of an inorganic filler (D). A porous film formed from a resin composition containing the same, having a melt tension of 0.5 to 4 g and a melt elongation of at least 800% at a temperature of 190 ° C. and a take-up speed of 200 m / min. 2. The method according to claim 1, wherein the content of the resin is (A) 20 to 95.
%, (B) 3-79% by weight and (C) 1-4% by weight
The porous film according to claim 1, which is: 3. The resin according to claim 1, wherein the resin (A) has a melt index of 1 to 10 g / 10 minutes and a density of 0.905 to 0.93 g / min.
cm ³ , (B) melt index 1 to 10 g / 10
Min, density 0.91 to 0.93 g / cm ³ , (C) melt index 0.3 to 8 g / 10 min, density 0.915 to
The porous film according to claim 1, wherein a 0.93 g / cm ^3. 4. The porous film according to claim 1, further comprising 0.1 to 12 parts by weight of at least one compound selected from hardened castor oil and dehydrated castor oil based on 100 parts by weight of the resin. 5. The porous film according to claim 4, wherein the content of at least one compound selected from hydrogenated castor oil and dehydrated castor oil is 1 to 8 parts by weight. 6. The porous film according to claim 1, wherein the film has a thickness of 5 to 500 μm. 7. After kneading and melting the resin composition according to any one of claims 1 to 5 at 200 to 280 ° C. to form a film, at least one axis in a temperature range from room temperature to a softening point of the resin. After stretching 1.1 to 4 times in the direction, and then cooling to a temperature near room temperature, the maximum speed 300m
A method for producing a porous film, comprising: 8. The method for producing a porous film according to claim 7, wherein after the stretching, a heat treatment is performed for 0.1 to 100 seconds in a temperature range not lower than the softening temperature of the resin and lower than the melting point. 9. The method for producing a porous film according to claim 7, wherein the thickness of the film is 5 to 500 μm.