JP3325376B2 - Porous film or sheet and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a porous film or sheet and a method for producing the same. Specifically, due to the synergistic action between the modification by the radical generator and the plasticizer, the surface strength and tearing degree are high, and there is no stretching unevenness of the film.
The present invention relates to a porous film or sheet and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, a porous synthetic resin film, which does not allow water droplets to pass through but has fine pores enough to allow a gas such as water vapor to pass, has been used in the field of clothing and the medical field. This has the effect of preventing stuffiness and preventing the liquid from leaking out. More specifically, it is often used in diapers, raincoats, sheets and the like.

A typical method for producing this porous film or sheet having air permeability is to add an inorganic filler to a synthetic resin,
For example, there is a method in which calcium carbonate, talc, clay, or the like is mixed, formed into a film, and then stretched to generate fine cracks in the film. The porous film or sheet thus obtained is anisotropic, especially in the longitudinal direction (stretching direction).
There was a problem in physical properties such as balance of tensile strength in the lateral direction and surface strength.

[0004] Some of the present inventors have solved the above problem by first forming and stretching a composition comprising a specific amount of linear polyethylene, branched low-density polyethylene, a radical generator and a filler. (USP 5,015,52).
1).

[0005]

DISCLOSURE OF THE INVENTION The present inventors have made intensive studies to provide a film or sheet having further improved tear strength, uneven stretching and unevenness in film thickness.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted various studies on the composition, molding method, etc. in order to solve the above-mentioned problems. As a result, it has been found that a special plasticizer is added and a radical generator is used. As a result, they have found that the problem can be solved, and have completed the present invention. That is, the gist of the present invention is:
Density 0.930 g / cm ³ or less, melt index 2
g / 10 minutes or less, 100 parts by weight of a polyolefin resin (A), 100 to 400 parts by weight of a filler (B), 0.1 to 100 parts by weight of a plasticizer (C) represented by the following general formula (1),

[0007]

(Equation 4)

Wherein A, B or B ′ is a divalent or higher polyvalent carboxylic acid residue or polyhydric alcohol residue (provided that A
Is a polyhydric alcohol residue, B and B ′ are polyvalent carboxylic acid residues, and when A is a polyvalent carboxylic acid residue,
B and B 'are polyhydric alcohol residues. ), C,
C ', D or D' represents an aliphatic carboxylic acid residue or aliphatic alcohol residue, e, e 'is 0~6, m _1, m ₂
Represents a number of 1 to 7, and n represents a number of 1 to 8. However, each group is connected by an ester bond. That is, when A is a polyhydric alcohol residue, B and B 'are polyvalent carboxylic acid residues, and D is an aliphatic carboxylic acid residue. When A is a polycarboxylic acid residue, B and B 'are polyhydric alcohol residues, and D is an aliphatic alcohol residue. further,
When B and B 'are polyvalent carboxylic acid residues, C, C' and D '
Is an aliphatic alcohol residue, and when B and B 'are polyhydric alcohol residues, C, C' and D 'are aliphatic carboxylic acid residues. ) And radical generator (D) 0.0001-
A porous film or sheet obtained by inflation molding a composition consisting of 0.1 part by weight, and uniaxially stretching the obtained film or sheet in a take-off direction, and a method for producing the same.

Hereinafter, the present invention will be described in more detail. The polyolefin resin (A) is made of a homopolymer of ethylene or propylene or a copolymer of ethylene or propylene and another comonomer (a compound having at least one double bond having 4 or more carbon atoms in the molecule).
930 g / cm ³ or less, melt index (MI) 2
g / 10 min or less polyolefin-based thermoplastic resin, for example, low density polyethylene, linear low density polyethylene, ethylene-vinyl acetate copolymer, ultra-low density polyethylene having a density of 0.910 or less, polypropylene, ethylene-propylene copolymer , Ethylene-propylene-diene copolymer, ethylene-methacrylic acid ester or a mixture thereof, but preferably has a density of 0.91.
Linear low density polyethylene -0.95g / cm ³ 50-
100 parts by weight and density 0.91 g / cm ³ less than the ethylene -α- olefin copolymer 50-0 density 0.930 g / cm ³ consisting of parts by weight or less, in particular, from 0.900 to 0.
925 g / cm ³ , MI 2 or less, especially 0.1 to 1.5
Is a polyolefin-based thermoplastic resin.

The linear low-density polyethylene is a copolymer of ethylene and another α-olefin, for example, ethylene and about 4 to 17% by weight, preferably about 5 to 15% by weight of 1-butene, 1-hexene, 1-octene, 1
It is produced by copolymerizing with other α-olefins such as -decene, 4-methyl-1-pentene and the like using a Ziegler type catalyst or a Phillips type catalyst used for the production of high-density polyethylene at medium and low pressures.

The above-mentioned ethylene-α-olefin copolymer is usually a copolymer of ethylene and an α-olefin having 3 or more carbon atoms, and has a density of 0.91 g / cm 3.
Preferably less than ³ , more preferably 0.85
0.90 g / cm ³ . Examples of the α-olefin having 3 or more carbon atoms to be copolymerized with ethylene include propylene, 1-butene, 1-pentene, 1-hexene, and 4-methyl-1-pentene.
Non-conjugated dienes such as hexadiene, dicyclopentadiene, ethylidene norbornene can also be used.

The ethylene-α-olefin copolymer is prepared by using a Ziegler-type catalyst, particularly a catalyst comprising a vanadium compound such as vanadium oxytrichloride or vanadium tetrachloride and an organoaluminum compound.
-The copolymer can be produced by copolymerizing an olefin, the ethylene content in the copolymer is in the range of 40 to 90 mol%, and the α-olefin content is 10 to 60 mol%.
It is desirably in the range of mol%. The above ethylene-α-
Commercially available olefin copolymers include, for example, CdF
Chimie E. P. NORSOFLEX (FW
1600, FW1900, MW1920, SMW244
0, LW2220, LW2500, LW2550); Nippon Unicar Flex Resin (DFDA1137,
DFDA1138, DEFD1210, DEFD904
2); Tuffmer (A4085, A40) of Mitsui Petrochemical Company
90, P0180, P0480), Nippon Synthetic Rubber J
SR-EP (EP02P, EP07P, EP57P) and the like.

When the density (ρ) of the polyolefin resin (A) alone or as a mixture is larger than 0.930 g / cm ³ , the synergistic effect of the plasticizer and the radical generator is small and the tear strength is not improved. If the MI is more than 2 g / 10 minutes, the tear strength of the film decreases, and the molding stability decreases.

In the method of the present invention, the melt index (MI) is J which is a reference standard of JIS K 6760.
It is a value measured based on the condition 4 of Table 1 of IS K7210. In addition, a heat stabilizer, an ultraviolet stabilizer, a pigment, an antistatic agent, a fluorescent agent, and the like may be added to the polyolefin resin according to a conventional method.

Next, inorganic and organic fillers are used as the filler of the component (B). Inorganic fillers include calcium carbonate, talc, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, aluminum hydroxide, zinc oxide, magnesium hydroxide, calcium oxide, magnesium oxide , Titanium oxide, alumina, mica, asbestos powder, glass powder, shirasu balloon, zeolite, silicate clay, etc., and calcium carbonate, talc, clay, silica, diatomaceous earth, barium sulfate and the like are particularly preferable.

As the organic filler, a cellulosic powder such as wood powder and pulp powder is used. These may be used alone or as a mixture. The average particle size of the filler is 30
μm or less, more preferably 10 μm or less, and most preferably 0.7 to 5 μm. If the particle size is too large, the denseness of the pores of the stretched product will be poor. If the particle size is too small, dispersibility in the resin will be poor and moldability will be poor.

The surface treatment of the filler is preferably carried out in view of the dispersibility in the resin and the stretchability, and the treatment with a fatty acid or a metal salt thereof gives a preferable result. Further, the component (C) having a specific structure used in the present invention.
The plasticizer of the general formula (1)

[0018]

(Equation 5)

(Wherein A, B or B 'is a divalent or higher polyvalent carboxylic acid residue or polyhydric alcohol residue (provided that A
Is a polyhydric alcohol residue, B and B 'are polyvalent carboxylic acid residues. ) Indicates, C, C ', D or D' is the end portion represents an aliphatic carboxylic acid residue or aliphatic alcohol residue, e, e 'is 0~6, m _1, m ₂ is 1 7,
n shows the number of 1-8. However, each group is connected by an ester bond. That is, when A is a polyhydric alcohol residue, B and B 'are polyvalent carboxylic acid residues, and D is an aliphatic carboxylic acid residue. When A is a polycarboxylic acid residue, B and B 'are polyhydric alcohol residues,
D is an aliphatic alcohol residue. Further, when B and B 'are polyhydric carboxylic acid residues, C, C' and D 'are aliphatic alcohol residues, and when B and B' are polyhydric alcohol residues, C, C 'and D 'is an aliphatic carboxylic acid residue. ) Is used.

Examples of the starting compound for introducing a divalent or higher polycarboxylic acid residue unit include phthalic acid (including its anhydride), isophthalic acid, terephthalic acid, and trimellitic acid (including its anhydride). ), Aromatic carboxylic acids such as pyromellitic acid (including its anhydride), succinic acid (including its anhydride), glutaric acid, adipic acid, azelaic acid, aliphatic carboxylic acids such as sebacic acid, citric acid, A mixed carboxylic acid such as malic acid is exemplified. Further, as a raw material compound for introducing a dihydric or higher polyhydric alcohol residue unit, for example, ethylene glycol, diethylene glycol, propylene glycol (1,2-, 1,3
-), Dipropylene glycol, butylene glycol (1,2-, 1,3-, 1,4-), pentanediol (1,5-, 3-methyl-1,5-, 2,2,4-trimethyl) -1,3-), hexanediol, neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, diglycerin and the like.

Further, C, C ',
D or D 'represents an aliphatic carboxylic acid residue or an aliphatic alcohol residue at the terminal. As the aliphatic carboxylic acid residue, a monovalent one is suitably used, and as a raw material compound for introducing the carboxylic acid residue unit, for example,
Examples include acetic acid, propionic acid, butyric acid, valeric acid, caprylic acid, enanthic acid, caproic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, stearic acid, and the like. On the other hand, as the aliphatic alcohol residue, a monovalent one is suitably used, and as a raw material compound for introducing the alcohol residue unit,
For example, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isobutyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, 2-ethylhexanol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, ministil alcohol , Cetyl alcohol, stearyl alcohol and the like. In addition, even a dihydric or higher alcohol such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate has one free hydroxyl group and the other is an ester of carboxylic acid. Those can also be used. Further, a divalent or higher polyvalent carboxylic acid such as adipic acid or trimellitic acid, wherein one free carboxyl group is contained.
Those in which the other is an ester of alcohol can be suitably used.

In addition, D and D 'are the same as those of the aliphatic carboxylic acid or the alcohol, and
For example, those substituted with aromatic carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid, and aliphatic carboxylic acids such as glutaric acid, adipic acid, azelaic acid, and sebacic acid are also used. . The compounds represented by the general formula (1) can be used alone or in combination of two or more.

Next, as the radical generator of the component (D) used in the present invention, a decomposition temperature having a half-life of 1 minute is 1
Those having a temperature in the range of 30 to 300 ° C., preferably 160 to 260 ° C. are preferable, for example, dicumyl peroxide, 2,
5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-bis (t-butylperoxy) -3-hexyne, α, α′-bis (t-butylperoxy) Isopropyl) benzene, dibenzoyl peroxide, di-t-butyl peroxide, 2,5-
And peroxides such as dimethylhexane-2,5-dihydroperoxide. Most preferably, 2,5-dimethyl-2,5-bis (t-butylperoxy) -3-
Hexin.

In the present invention, the filler (B) is used in an amount of 100 to 40 parts by weight based on 100 parts by weight of the polyolefin resin (A).
0 parts by weight, preferably 120 to 300 parts by weight, in particular,
130 to 250 parts by weight, 1 to 100 parts by weight of plasticizer (C), preferably 2 to 50 parts by weight, particularly 2 to 30 parts by weight, and 0.0001 to 0.1 part by weight of radical generator (D) It is preferably used in the range of 0.0005 to 0.07 parts by weight, particularly 0.005 to 0.05 parts by weight.

If the proportion of the filler (B) is less than 100 parts by weight, pores are not sufficiently formed in the stretched film, and the degree of porosity becomes low. On the other hand, when the proportion of the filler exceeds 400 parts by weight, kneading properties, dispersibility, film or sheet formability are inferior, and the surface strength of the stretched product is further reduced. When the amount of the plasticizer (C) is less than 0.1 part by weight, there is no effect of improving the tear strength, and when the amount is more than 100 parts by weight, kneadability and dispersibility are deteriorated, film formability is reduced, and stretchability is secured. Can not.

The radical generator (D) is 0.0001 to
It is selected from the range of 0.1 parts by weight, and if less than this range, improvement in tear strength due to a synergistic effect with a plasticizer cannot be obtained, and if it is more than this range, the melt index is too low, It is not preferable because the film is likely to be cut during the film formation and the surface of the film becomes rough.

In the present invention, the polyolefin resin (A), the filler (B), the plasticizer (C), and the radical generator (D) are usually used in the above-mentioned amounts by, for example, the following 1 or 2 methods. After mixing at a ratio and then kneading to form a pellet, inflation molding is performed to obtain an unstretched film.
Method 1: A polyolefin resin, a filler, a plasticizer, and a radical generator are mixed and kneaded using a kneader such as an extruder or a Banbury mixer, and then pelletized, and the pellets are used for inflation molding. Method 2: a large amount of a radical generator 0.3 to 2% in a polyolefin resin
(3000 to 20000 ppm), and a radical batch is melt-kneaded at a temperature at which the radical generator hardly reacts with the polyolefin, and at a temperature higher than the melting point of the polyolefin to prepare a pelletized master batch in advance. The mixture is mixed with a polyolefin resin, a filler and a plasticizer, kneaded and then pelletized, and the pellets are used for inflation molding.

When the polyolefin resin is kneaded with the radical generator under heating (preferably at a temperature not lower than the temperature at which the half-life of the radical generator is 10 minutes) according to the method described in 1 or 2, crosslinking by the radical generator is performed. A reaction occurs, and polyolefins are intermolecularly coupled to increase the high molecular weight component, thereby obtaining a modified polymer having a reduced melt index. This modified polymer is more likely to be oriented in the transverse direction at the time of inflation molding than the polymer before modification, and the film thus obtained, when subjected to a stretching treatment, has significantly improved tensile strength and impact strength. .

To mix the polyolefin resin, the plasticizer, the radical generator and the filler, a drum, a tumbler type mixer, a ribbon blender, a Henschel mixer, a super mixer, etc. are used. A mixer of a mold is desirable, and the polyethylene is preferably supplied in the form of a powder of usually 10 to 150 mesh, especially 20 to 60 mesh. The kneading of the obtained mixture is carried out using a well-known kneading device such as a screw extruder, a twin-screw extruder, a mixing roll, a Banbury mixer, a twin-screw kneader and the like.

In the present invention, an unstretched film having a thickness of 10 to 200 μm or an unstretched sheet having a thickness of 200 to 400 μm is usually formed from the composition obtained above by an inflation method. Is stretched. Inflation molding is usually performed at a blow-up ratio (BUR) of 2 to 8.

Preferably, the blow-up ratio is 3 to 6, and the height of the frost line is 2 to 5 times the diameter of the annular slit of the die.
Make it 0 times. More preferably, it is carried out under the condition that the height of the frost line is in the range of 5 to 20 times the diameter of the annular slit of the die. When the blow-up ratio is lower than the above range, the tensile strength and impact strength of the film are reduced, and when the blow-up ratio is higher than the above range, the molding stability of the bubble is lowered. When the height of the frost line is lower than the above range, the tensile strength of the film decreases, and when the height is higher than the above range, the molding stability of the bubble decreases.

The unstretched film or sheet formed by the inflation method is then uniaxially stretched in the machine direction (the direction in which the film is taken off). The uniaxial stretching is usually performed by a roll stretching method, but may be a tubular stretching method in which the uniaxial direction (drawing direction) is emphasized. The stretching may be performed in one stage or in two or more stages.

The stretching treatment is performed at 100 ° C. below the melting point of the resin composition.
It is preferably carried out in a temperature range from a low temperature to 20 ° C. lower than the melting point, particularly in a range from 90 ° C. lower than the melting point of the resin composition to 50 ° C. lower than the melting point. Occurs, and at temperatures above this range the porosity of the film tends to decrease.

The stretching ratio is preferably 1.2 to 8 times. In addition, if heat treatment is performed after uniaxial stretching, the dimensional accuracy of the film can be stabilized, and a known corona treatment,
Surface treatment such as frame treatment can also be performed. The porous film or sheet of the present invention thus obtained has a high surface strength and a high tear strength and has no stretching unevenness, so that it can be suitably used. In particular, in the case of a porous film having a thickness of 100 μm or less, preferably 15 to 50 μm, both the softness in the longitudinal direction and the transverse direction are 50 mm or less, and preferably 10 mm or less.
Up to 35 mm and a moisture permeability of 1500 g / m ² · 24 hr or more, preferably 2500 to 5000 g / m ² · 24 h
r, the tensile strength at break is expressed by the following equation (2)

[0035]

(6) Tensile strength at break [g / cm] ≧ 5500 × film thickness [mm] (2)

Preferably, the formula (2 ')

[0037]

## EQU7 ## Tensile strength at break [g / cm] ≧ 6700 × film thickness [mm] (2 ′)

And satisfying the following formula (3):

[0039]

(8) Tear strength [g / sheet] ≧ 1500 × film thickness [mm] (3)

Preferably, the formula (3 ')

[0041]

(9) Tear strength [g / sheet] ≧ 1800 × film thickness [mm] (3 ′)

It is preferable because a film satisfying the above condition is obtained.

[0043]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, however, are not intended to limit the scope of the present invention. Example 1 (1) Linear low-density polyethylene @ melt index (MI): 1.0 g / 10 min, flow ratio: 19, density (ρ): 0.921 g / cm ³ , copolymerization component: 1-butene, A copolymerization amount: 10% by weight, melting point: 120 ° C., pulverized into 40 mesh powder, and 80 parts by weight of ethylene-propylene copolymer (EPR, manufactured by Nippon Synthetic Rubber Co., Ltd.)
P07P, MI: 0.4 g / 10 min, ρ: 0.86 g /
cm ³ ) was also ground into 40 mesh powder, and 20 parts by weight were stirred and mixed in a Henschel mixer. The MI of the obtained polymer composition was 0.8 g / 10 min, and the density was 0.909 g / cm ³ . Next, 4 parts by weight of a plasticizer A shown in Table 2 below and radical generators 2,5 were added thereto.
-Dimethyl-2,5-bis (t-butylperoxy)-
0.02 parts by weight of 3-hexyne was added and mixed with stirring.

Further, calcium carbonate (average particle size 1.2 μm)
m, fatty acid treatment), and stirred and mixed. The mixture thus obtained is mixed with a twin-screw kneader DSM-6.
5 (Double Screen Mixer, manufactured by Japan Steel Works, Ltd.) and granulated. This is 40m
Inflation molding with mφ extruder, thickness 70μ
m was formed into a film. Extrusion conditions are as follows.

[0045]

Cylinder temperature: 170-190-210-230 ° C. Head and die temperature: 200 ° C. Die diameter: 100 mm Take-off speed: 8 m / min Blow-up ratio: 3 Frost line height: 700 mm Folding diameter: 471 mm

The film thus obtained was slit in the take-off direction and uniaxially stretched by a roll stretching machine. The stretching conditions were as follows.

[0047]

[Table 2] Stretching temperature: 60 ° C Stretching ratio: 2.0 times Speed after stretching: 11.0 m / min Film thickness after stretching: 30 μm

The physical properties were evaluated as follows, and the results are shown in Table 1.
It was shown to. 1) Moisture permeability: according to ASTM E26-66 (E). 2) Tear strength: The tearing direction of the film is measured according to JIS P 8116, and the strength per sheet is obtained in g. 3) Tensile strength at break: Measured at a tensile speed of 300 mm / min using a test piece of 10 mm (width) x 100 mm (length) according to JIS L1085-1977. 4) Moldability: Visually determined according to the following criteria.

◎: bubble stable, no die line ○: bubble stable, die line present △: film width fluctuation ×: molding impossible

5) Flexibility: The feeling was evaluated by the following criteria. ◎: extremely soft ○: soft △: slightly hard ×: hard

6) Stretchability ：: No cutting, uniform stretching, no stretching unevenness: No cutting, stretching unevenness, almost none △: No cutting, stretching unevenness, slightly present ×: Large cutting or stretching unevenness

Example 2 80 parts by weight of the linear low-density polyethylene used in Example 1
Ethylene-butene-rubber (manufactured by Mitsui Petrochemical Co., Ltd., Toughmer A4085, MI: 3.6 g / 10 min, ρ: 0.88
g / cm ³ ) (tuffmer is a trade name) and 20 parts by weight (the density of the composition when these are mixed is 0.913 g / cm ³ ).
^{At 3} , MI is 1.3 g / 10 min. ), 6 parts by weight of a plasticizer B shown in Table 2 below, and 2,5 as a radical generator.
-Dimethyl-2,5-bis (t-butylperoxy)-
0.03 parts by weight of 3-hexyne and 20 parts of calcium carbonate
0 parts by weight were used. A film was obtained in the same manner as in Example 1 except that the frost line height was 800 mm among the molding conditions. Table 1 shows the evaluation results.

Example 3 80 parts by weight of the linear low-density polyethylene used in Example 1 was mixed with ultra-low-density polyethylene (CDF Chemie).
E. FIG. P. FW1900, MI: 1.0 g / 10
Ρ: 0.900 g / cm ³ ) and 20 parts by weight (the density of the composition when these are mixed is 0.917 g / cm ^3).
And MI is 1.0 g / 10 min. 3), 3 parts by weight of a plasticizer C shown in Table 2 below, 0.02 parts by weight of the same radical generator as in Example 1, and 200 parts by weight of calcium carbonate. Of the molding conditions, the frost line height is 1000m
m and the draw ratio were 2.1 times, and a film was obtained in the same manner as in Example 1. Table 1 shows the evaluation results.

Example 4 As a linear low-density polyethylene (MI: 0.5 g / 10
Min, flow ratio: 20, density: 0.921 g / cm ³ , copolymerization component: 1-butene, copolymerization amount: 10% by weight, melting point: 1
20 parts by weight) and 20 parts by weight of ethylene-butene-rubber used in Example 2 (the density of the composition when these were mixed was 0.909 g / cm ³ and MI was 0.5%).
g / 10 minutes. ), 4 parts by weight of plasticizer C, Example 1
0.03 parts by weight of the same radical generator and 200 parts by weight of calcium carbonate were used. A film was obtained in the same manner as in Example 1, except that the frost line height was 800 mm and the stretching ratio was 2.5 times. Table 1 shows the evaluation results.

Example 5 80 parts by weight of the linear low-density polyethylene used in Example 4 and 20 parts by weight of the ethylene-butene rubber used in Example 2 (the density of the composition when these were mixed) Is 0.913 g / cm ³ and MI is 0.7 g / 10 min.), 4 parts by weight of a plasticizer D shown in Table 2 below, Example 1
0.02 parts by weight of the same radical generator and 200 parts by weight of calcium carbonate were used. The molding conditions were a draw ratio of 2.2.
A film was obtained in the same manner as in Example 1, except that Table 1 shows the evaluation results.

Example 6 The same linear low-density polyethylene as used in Example 1 was used.
0 parts by weight, 4 parts by weight of a plasticizer E shown in Table 2 below, 0.03 part by weight of the same radical generator used in Example 1, and 200 parts by weight of calcium carbonate were used. Of the molding conditions,
Example 1 except that the frost line height was 600 mm
A film was obtained in the same manner as described above. Table 1 shows the evaluation results.

Example 7 A film was obtained in the same manner as in Example 1 except that the radical generator was 2,5-dimethyl-2,5 di (t-butylperoxy) hexane. Table 1 shows the evaluation results.

[0058]

[Table 3]

[0059]

[Table 4]

[0060]

The porous film of the present invention is particularly excellent in tear strength and tensile strength at break, has little stretching unevenness, and can be advantageously used in applications such as diapers, raincoats and sheets. .

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08J 9/00 C08L 23/00-23/26

Claims (5)

(57) [Claims] 1. 100 parts by weight of a polyolefin resin (A) having a density of 0.930 g / cm ³ or less and a melt index of 2 g / 10 minutes or less, 100 to 400 parts by weight of a filler (B), represented by the following general formula (1) Plasticizer (C) 0.1-
100 parts by weight, (In the formula, A, B or B 'is a divalent or higher polyvalent carboxylic acid residue or a polyhydric alcohol residue (however, when A is a polyhydric alcohol residue, B, B' is a polyvalent carboxylic acid residue) is a group.) indicates, C, C ', D or D' is the end portion represents an aliphatic carboxylic acid residue or aliphatic alcohol residue, e, e 'is 0~6, m _1, m ₂ is 1 to 7, n is 1 to
8 is shown. However, each group is connected by an ester bond. That is, when A is a polyhydric alcohol residue, B and B 'are polyvalent carboxylic acid residues, and D is an aliphatic carboxylic acid residue. When A is a polycarboxylic acid residue, B and B 'are polyhydric alcohol residues, and D is an aliphatic alcohol residue. Further, when B and B 'are polycarboxylic acid residues, C, C' and D 'are aliphatic alcohol residues, and when B and B' are polyhydric alcohol residues,
C, C 'and D' are aliphatic carboxylic acid residues. ) And a radical generator (D) in an amount of from 0.0001 to 0.1 part by weight, and the resulting film or sheet is uniaxially stretched in the take-off direction. Film or sheet. 2. A porous film having a thickness of not more than 90 μm, having both a softness in the longitudinal direction and a transverse direction of not more than 50 mm, a moisture permeability of not less than 1500 g / m ² · 24 hr, and a tensile strength at break. Satisfies the following formula (2): tensile strength at break [g / cm] ≧ 5500 × film thickness [mm] (2) and a tear strength of the following formula (3): tear The porous film according to claim 1, wherein the strength [g / sheet] ≧ 1500 × film thickness [mm] (3) is satisfied. 3. The porous film or sheet according to claim 1, wherein the decomposition temperature at which the half-life of the radical generator (D) is 1 minute is 130 to 300 ° C. 4. The method according to claim 1, wherein the radical generator (D) is 2,5-dimethyl-2,5-bis (t-butylperoxy) -3-hexyne. A porous film or sheet as described in the above. 5. A polyolefin resin (A) having a density of 0.930 g / cm ³ or less and a melt index of 2 g / 10 minutes or less, 100 parts by weight, a filler (B) 100 to 400 parts by weight, and the general formula (1) ) Plasticizer (C)
0.1 to 100 parts by weight and a radical generator (D)
The composition comprising 0001-0.1 parts by weight is blown-molded at a blow-up ratio of 2 to 8 after or while allowing the radical generator to decompose, and the resulting film or sheet is taken up. A method for producing a porous film or sheet, wherein the film is uniaxially stretched with a stretching ratio of 1.2 to 8 times in the direction.