JP2013159749A - Polypropylene resin composition and porous film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene resin composition which has excellent processability when stretched, high porosity, and excellent heat resistance when processed into a porous film, and to provide a porous film.SOLUTION: A polypropylene resin composition includes a polypropylene resin (component (A)) which meets all of the following requirement (1) and requirement (2), and 0.01-5 pts.wt. of beta crystal nucleating agent (component (B)) based on 100 pts.wt. of the component (A): requirement (1): a butene propylene random copolymer has 1-15 wt.% of a structural unit derived from butene (provided that the total weight of the butene propylene random copolymer is 100 wt.%) and requirement (2): total content of aluminum, magnesium, titanium, silicon and iron as measured with inductively coupled plasma emission spectrophotometer is 200 ppm or less.

Description

  The present invention relates to a polypropylene resin composition and a porous film that are excellent in workability during stretching and have a high porosity and excellent heat resistance when formed into a porous film.

  Porous polypropylene films are used for various filters and the like because of their characteristics such as high permeability, high porosity, and low cost, and their uses are diverse.

  As such a porous polypropylene film, for example, in Patent Document 1, a polypropylene sheet obtained by melt-molding a composition comprising polypropylene and a β-nucleating agent is stretched in one direction at a specific temperature, A porous polypropylene film produced by stretching in one direction at different specific temperatures is described.

Japanese Patent Laid-Open No. 7-118429

  However, the porous polypropylene film described in Patent Document 1 is not yet satisfactory in terms of porosity, workability during stretching, and heat resistance, and further improvements have been desired. An object of the present invention is to provide a polypropylene-based resin composition and a porous film that are excellent in workability at the time of stretching and have a high porosity and excellent heat resistance when formed into a porous film.

In order to solve the above-mentioned problems, the present inventors have intensively studied and found that the present invention can solve the above-mentioned problems, and have completed the present invention.
That is, the present invention relates to a polypropylene-based resin (component (A)) that satisfies all of the following requirements (1) and (2) and 100 parts by weight of the component (A) with a β crystal nucleating agent ( The component (B)) relates to a polypropylene resin composition containing 0.01 to 5 parts by weight.
Requirement (1): A butene-propylene random copolymer having a structural unit derived from butene of 1 to 15% by weight (provided that the total weight of the butene-propylene random copolymer is 100% by weight).
Requirement (2): The total content of aluminum, magnesium, titanium, silicon and iron measured with an inductively coupled plasma optical emission spectrometer is 200 ppm or less

  The present invention also relates to a porous film obtained by stretching the polypropylene resin composition.

  According to the present invention, it is possible to obtain a porous film that is excellent in workability during stretching, has a high porosity, and is excellent in heat resistance.

Hereinafter, embodiments of the present invention will be described in detail.
The polypropylene resin composition of the present invention comprises a polypropylene resin that satisfies all of the following requirements (1) and (2) (hereinafter sometimes referred to as “component (A)”), and the above components. (A) A beta crystal nucleating agent (it may be described as "component (B)" below) 0.01-5 weight part with respect to 100 weight part.
Requirement (1): A butene-propylene random copolymer having a structural unit derived from butene of 1 to 15% by weight (provided that the total weight of the butene-propylene random copolymer is 100% by weight).
Requirement (2): The total content of aluminum, magnesium, titanium, silicon and iron measured with an inductively coupled plasma optical emission spectrometer is 200 ppm or less

The polypropylene-based resin (component (A)) used in the present invention is a butene-propylene random copolymer whose structural unit derived from butene is 1 to 15% by weight (however, the total weight of the butene-propylene random copolymer is 100 wt%).
The structural unit derived from butene of component (A) is 1 to 15% by weight, the structural unit derived from propylene is 85 to 99% by weight, and preferably the structural unit derived from butene is 1 to 13% by weight. The structural unit derived from propylene is 87 to 99% by weight, more preferably the structural unit derived from butene is 1 to 11% by weight, and the structural unit derived from propylene is 89 to 99% by weight. is there.

  The component (A) is preferably a butene-propylene random copolymer having a structural unit derived from butene of 1 to 15% by weight.

  The polypropylene resin (component (A)) used in the present invention has a total content of aluminum, magnesium, titanium, silicon and iron as measured by an inductively coupled plasma emission spectrometer of 200 ppm or less, preferably 150 ppm or less. Yes, more preferably 100 ppm or less.

The measurement of the content of aluminum, magnesium, titanium, silicon and iron in the component (A) is a value measured under the following conditions using an inductively coupled plasma emission spectrometer (VISTA-PRO manufactured by Agilent Technologies). At this time, only the polypropylene resin may be measured, or a polypropylene resin added with an additive not containing aluminum, magnesium, titanium, silicon and iron may be measured.
1) 0.5 g of polypropylene resin was placed in a platinum dish, 1 mL of 96% sulfuric acid was added, carbonized with a hot plate, and then incinerated at 550 ° C. with an electric furnace.
2) For concentration measurement of aluminum, magnesium, titanium and iron, add 1 mL of 96% sulfuric acid and 1-10 mL of 50% hydrofluoric acid to the residue after ashing on the platinum plate, heat on a hot plate and evaporate to dryness I let you. Thereafter, 0.4 mL of 36% hydrochloric acid and 20 mL of ultrapure water were added and heated and dissolved at 100 ° C. to obtain a test solution. Aluminum, magnesium, titanium, and iron were detected at wavelengths of 396.2 nm, 280.3 nm, 336.1 nm, and 259.9 nm, respectively, when measured with an inductively coupled plasma emission spectrometer (VISTA-PRO manufactured by Agilent Technologies). Is done.
3) In the measurement of the concentration of silicon, 0.5 g of sodium carbonate after ashing on the measurement platinum dish was added and melted with a burner. 20 mL of ultrapure water and 2 mL of 36% hydrochloric acid were added and dissolved by heating at 100 ° C. as a measurement test solution. Silicon is detected at a wavelength of 251.6 nm when measured with an inductively coupled plasma optical emission spectrometer (VISTA-PRO manufactured by Agilent Technologies).

  The means for adjusting the total content of aluminum, magnesium, titanium, silicon and iron measured by an inductively coupled plasma emission spectrometer to 200 ppm or less is not particularly limited, but preferably, by increasing the polymerization time of propylene, A method for reducing the catalyst residue, a method for reducing the amount of ash contained by passing polypropylene through a relatively fine mesh screen in an extruder, or a method for appropriately washing polypropylene powder.

  As a method for extending the polymerization time of propylene, for example, a solid catalyst component containing magnesium, titanium and halogen as essential components is combined with an organoaluminum compound and, if necessary, a third component such as an electron donating compound. In the bulk polymerization of the catalyst system, the catalyst residue in polypropylene can be reduced by polymerizing at 20 to 150 ° C for 45 minutes or more, more preferably at 35 to 95 ° C for 50 minutes or more. At this time, even when the polymerization time is less than 45 minutes, the catalyst residue in polypropylene can be reduced by continuously performing polymerization in another polymerization tank.

  As a method for washing the polypropylene powder with a solvent, after polymerization, water or a lower alcohol such as methanol, ethanol, i-propanol, n-butanol, i-butanol, sec-butanol or t-butanol is polymerized as a polymerization inhibitor. A method of reducing the amount of ash in polypropylene by adding to a vessel to deactivate the catalyst, washing the resulting polypropylene with an appropriate solvent, and drying the resulting polypropylene is then used.

  As the washing solvent, n-pentane, n-hexane, n-heptane, n-octane, i-octane, toluene, mixed xylene, p-xylene and the like can be generally used, and the washing temperature is usually from room temperature to 100 ° C. Temperature. The pressure during drying may be from reduced pressure to pressurized conditions.

  In addition, as a method of reducing the amount of ash contained by passing a polypropylene obtained by polymerization through a mesh screen having a relatively small opening in an extruder, the opening is 60 to 70 μm, preferably An example is a method in which a screen mesh of 20 to 40 μm is set in the vicinity of the screw tip of the extruder or the entrance of a die and the polypropylene is passed through the mesh screen. In particular, a method of reducing the amount of ash contained by passing the polypropylene through a relatively fine mesh screen in an extruder is suitable as a method for easily removing ash, for example, melt-pelletizing polypropylene. It is carried out at the time of melting or extruding at the time of film production.

As a manufacturing method of a component (A), the method of manufacturing with a well-known polymerization method using the well-known polymerization catalyst is mentioned.
As a known polymerization catalyst, for example,
(1) Ti—Mg-based catalyst comprising a solid catalyst component containing magnesium, titanium and halogen as essential components,
(2) a catalyst system in which a solid catalyst component containing magnesium, titanium and halogen as essential components is combined with an organoaluminum compound and a third component such as an electron donating compound as required (3) a metallocene catalyst,
Etc.
Preferably, the catalyst system is a combination of a solid catalyst component containing magnesium, titanium and halogen as essential components with an organoaluminum compound and an electron donating compound.

Examples of the solid catalyst component containing magnesium, titanium and halogen as essential components include solid catalysts described in JP-A-61-218606, JP-A-61-287904, JP-A-7-216017 and the like. Ingredients.
Examples of the organoaluminum compound include triethylaluminum, triisobutylaluminum, a mixture of triethylaluminum and diethylaluminum chloride, and tetraethyldialumoxane.
Examples of the electron donating compound include tert-butyl-n-propyldimethoxysilane, tert-butylethyldimethoxysilane, dicyclopentyldimethoxysilane, and cyclohexylethyldimethoxysilane.

  Known polymerization methods include solvent polymerization using an inert solvent typified by hydrocarbons such as hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, and bulk using a liquid monomer as a solvent. Examples thereof include a polymerization method and a gas phase polymerization method performed in a gaseous monomer. The bulk polymerization method and the gas phase polymerization method are preferable because post-treatment is easy.

  The polymerization temperature is preferably 20 to 150 ° C., and more preferably 35 to 95 ° C. from the viewpoint of increasing productivity.

  The component (A) may be subjected to treatments such as catalyst deactivation, solvent removal, monomer removal, drying, and granulation as post-treatment of polymerization, if necessary.

  The melt flow rate (MFR) of the component (A) is preferably 0.1 to 100 g / 10 minutes, more preferably 0.2 to 50 g / 10 minutes.

The β crystal nucleating agent (component (B)) used in the present invention is a crystallization nucleating agent that forms a β crystal by being added to a molten polypropylene resin. For example, JP-A-5-262936. Examples include amide compounds, organic dibasic acid metal salts, quinacridone compounds, tetraoxaspiro compounds, imido acid metal salts, hexahydrophthalic acid metal salts and the like described in the publication, and preferably the following general formula (I Is an amide compound.

R ² —NHCO—R ¹ —CONH—R ³ (I)
(In the formula, R ¹ represents a divalent aromatic group. R ² and R ³ are the same or different and represent a monovalent aromatic group or a monovalent alicyclic group.)

Examples of the substituent R ¹ in the formula (I) include a p-phenylene group, a 2,6-naphthylene group, and a biphenylene group. Examples of the substituents R ² and R ³ in the formula (I) include a cyclohexyl group, a p-methylphenyl group, a p-ethylphenyl group, and a 4-cyclohexylphenyl group. Examples of the amide compound represented by the formula (I) include N, N′-dicyclohexyl terephthalamide, N, N′-dicyclohexyl-2,6-naphthalenedicarboxyamide, N, N′-dicyclohexyl-4,4. Examples include '-biphenyldicarboxamide.

  The polypropylene resin composition of the present invention contains component (A) and 0.01 to 5 parts by weight of component (B) with respect to 100 parts by weight of component (A). If the component (B) is less than 0.01 parts by weight, the effect of generating β crystals is insufficient, and even if added in excess of 5 parts by weight, no significant difference in effect is observed, which is economically disadvantageous. is there. Preferably, it is 0.03 to 3 parts by weight of component (B) with respect to 100 parts by weight of component (A), more preferably 0.05 to 0.05 parts of component (B) with respect to 100 parts by weight of component (A). -1 part by weight.

  In addition to the component (A) and the component (B), the polypropylene resin composition of the present invention may contain additives and other resins as necessary.

  Examples of the additive include an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a nucleating agent, an antifogging agent, and an antiblocking agent.

  Examples of the antioxidant include calcium stearate, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris (3,5- Di-t-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, dimyristyl-3,3′-thiodipropionate, tris (2 , 4-di-t-butylphenyl) phosphite, basic aluminum magnesium carbonate, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, 3,9-bis [2 {3 ( 3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} 1,1-dimethylethyl] 2,4,8,10-tetraoxa Pyro - [5.5] undecane, and the like.

  Examples of the ultraviolet absorber include 2,4-di-t-butylphenyl-3 ′, 5′-di-t-butyl-4′-hydroxybenzoate, bis (2,2,6,6-tetramethyl- 4-piperidine) sebacate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate and the like.

  Examples of the antistatic agent include glycerin fatty acid ester, polyoxyalkylamine mixed composition, alcohol fatty acid ester, nonionic surfactant, polyoxyethylene alkylamine / higher alcohol mixture, and the like.

  Examples of the lubricant include erucic acid amide, oleic acid amide, ethylene bisstearyl aluminide, erucyl amide, dimethylpolysiloxane and the like.

  Examples of the nucleating agent include bis [4- (1,1-dimethylethyl) benzoate-0] hydroxyaluminum, dibenzylidene sorbitol, 2,2′-methylenebis (4,6-di-t-butylphenyl phosphate). ) Sodium, phosphate ester compounds and the like.

  Examples of the antifogging agent include stearic acid monoglyceride, oleic acid monoglyceride, polyglycerin oleic acid ester, sorbitan monolaurate and sorbitan monostearate.

  Examples of the anti-blocking agent include silicon dioxide, polymethylsilsesquioxane, aluminum silicate salt, and a crosslinked polymethyl methacrylate.

  Examples of the resin other than the component (A) and the component (B) that can be added to the polypropylene resin composition include polyethylene, ethylene-α-olefin copolymer, high melt tension polypropylene, polymethylpentene, polystyrene, polybutylene terephthalate, and the like. Is mentioned.

  The component (B) and additives may be blended in advance when preparing the polypropylene-based resin, or may be blended when mixing into a separately prepared resin.

  The porous film of the present invention can be obtained by uniaxial stretching, simultaneous biaxial stretching, or sequential biaxial stretching of a raw sheet obtained from the polypropylene resin composition of the present invention. It is preferable to do this.

  Examples of the method for producing the raw sheet include the following methods. That is, it is a method of supplying raw materials to a melt extruder, performing melt extrusion at 200 to 300 ° C., and discharging from a T die to a cast drum. At this time, the cast drum preferably has a surface temperature of 80 to 130 ° C. from the viewpoint of increasing the β crystal content of the raw fabric sheet. At this time, particularly, the forming of the end portion of the sheet affects the subsequent stretchability, and therefore it is preferable that the end portion is sprayed with spot air to be in close contact with the drum. Further, air may be blown over the entire surface using an air knife as necessary from the state in which the entire sheet is in close contact with the drum.

  Examples of the method for stretching the original fabric sheet include the following methods. That is, the film is stretched 3 to 10 times at 90 to 150 ° C. in the longitudinal direction of the film (MD direction) and then stretched 3 to 10 times at 130 to 155 ° C. in the width direction (TD direction).

  Applications of the porous film obtained in the present invention include, for example, various separators such as batteries and electrolytic capacitors, various filtration membranes such as filtration membranes for water purification treatment, various separation membranes such as hemodialysis membranes, absorption of diapers, etc. Examples thereof include a printing substrate such as a functional article, a wound dressing, a heat-sensitive receiving paper member, and an ink receiving member.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The measuring methods of physical properties used in Examples and Comparative Examples are shown below.

(1) Content of aluminum, magnesium, titanium, silicon and iron These are values measured under the following conditions using an inductively coupled plasma optical emission spectrometer (VISTA-PRO manufactured by Agilent Technologies). At this time, only the polypropylene-based resin may be measured, or polypropylene obtained by adding an additive not containing aluminum, magnesium, titanium, silicon, and iron may be measured.
1) 0.5 g of polypropylene resin was placed in a platinum dish, 1 mL of 96% sulfuric acid was added, carbonized with a hot plate, and then incinerated at 550 ° C. with an electric furnace.
2) For concentration measurement of aluminum, magnesium, titanium and iron, add 1 mL of 96% sulfuric acid and 1-10 mL of 50% hydrofluoric acid to the residue after ashing on the platinum plate, heat on a hot plate and evaporate to dryness I let you. Thereafter, 0.4 mL of 36% hydrochloric acid and 20 mL of ultrapure water were added and heated and dissolved at 100 ° C. to obtain a test solution. Aluminum, magnesium, titanium, and iron were detected at wavelengths of 396.2 nm, 280.3 nm, 336.1 nm, and 259.9 nm, respectively, when measured with an inductively coupled plasma optical emission spectrometer (VISTA-PRO manufactured by Agilent Technologies). Is done.
3) In the measurement of the concentration of silicon, 0.5 g of sodium carbonate after ashing on the measurement platinum dish was added and melted with a burner. 20 mL of ultrapure water and 2 mL of 36% hydrochloric acid were added and dissolved by heating at 100 ° C. as a measurement test solution. Silicon is detected at a wavelength of 251.6 nm when measured with an inductively coupled plasma optical emission spectrometer (VISTA-PRO manufactured by Agilent Technologies).

(2) Melt flow rate (MFR, unit: g / 10 minutes)
According to JIS K 7210, the temperature was 230 ° C. and the load was 21.18 N.

(3) Porosity of film The density of resin was calculated | required from the following formula using the raw fabric sheet of 9.2 * 9.2cm before extending | stretching.
Density (g / mL) = sheet weight / (9.2 × 9.2 × sheet thickness)
Next, the porosity was calculated from the following formula using the calculated density and the weight and thickness of the film after stretching of 9 × 9 cm.
Porosity (%) = {1- (film weight / density) / (9 × 9 × film thickness)} × 100

(4) Heat Shrinkage Ratio A 9 × 9 cm stretched film was immersed in 120 ° C. silicon oil for 5 seconds, cooled at room temperature for 30 minutes, and calculated for each of the MD direction and the TD direction of the stretched film using the following equations.
Thermal contraction rate (%) = {(9−length in MD direction or TD direction after heating) / 9} × 100

(5) Maximum stress during stretching The maximum stress during stretching was the maximum value of the stress applied during the stretching process in the MD direction or TD direction of the film.

[Example 1]
Obtained by continuously performing bulk polymerization and gas phase polymerization in a catalyst system in which an organic aluminum compound and a third component such as an electron donating compound are combined with a solid catalyst component containing magnesium, titanium and halogen as essential components. Β-crystal nucleating agent (B), TMB-5 (manufactured by SHANXI PROVINCIAL INSTRUCTIVE OF CHEMICAL INDUSTRY, chemical name: N, N′-dicyclohexyl terephthalamide) ) 5 parts by weight, Sumilizer GP (manufactured by Sumitomo Chemical) 0.1 parts by weight, Irgafos 168 (manufactured by Ciba Specialty Chemicals) 0.1 parts by weight, hydrotalcite (manufactured by Kyowa Chemical Industry, DHT-4C) Add 0.01 parts by weight and mix, 40mmΦ single screw extrusion Machine (manufactured by Tanabe Plastic Machine, VS40-28 type extruder), melt kneaded at 220 ° C, extruded into strands, cooled and solidified in a 25 ° C water bath, cut into chips, β-crystal A nucleating agent master batch (C) was obtained.

  Butene-propylene random copolymer (A) having a butene content of 3% by weight, an MFR of 1.9 g / 10 min, and a total content of aluminum, magnesium, titanium, silicon and iron of 95 ppm (manufactured by Sumitomo Chemical Co., Ltd., FSX21E8 ) To 98 parts by weight, 2 parts by weight of master batch (C) was added and mixed, and supplied to a 20 mmφ single-screw extruder (manufactured by Tanabe Plastic Machine, VS20-24 type extruder). It was melt-kneaded at 250 ° C., extruded from a T die at 250 ° C., cooled and solidified with a cast roll at 80 ° C. to obtain a cast sheet having a thickness of 500 μm.

  The obtained cast sheet was finely pulverized, and the resin was melted with a press at 230 ° C. for 5 minutes. Then, a pressure of 11 MPa was applied to the resin, and the resultant was further held for 5 minutes. Next, the resin was crystallized by holding for 10 minutes while applying a pressure of 4 MPa to a 120 ° C. press, and then cooled by holding for 5 minutes while applying a 4 MPa pressure to a 30 ° C. press. In this manner, an original sheet having a thickness of 500 μm was obtained.

  Using a desktop biaxial stretching machine (X10 type, manufactured by Toyo Seiki Seisakusho), the raw sheet was heated with hot air at 150 ° C. for 3 minutes, then stretched 5 times vertically at a speed of 5.0 m / min, and then horizontally A stretched film was obtained by stretching 5 times at a speed of 5.0 m / min.

[Example 2]
[Preactivation of solid catalyst]
In a SUS autoclave with a 3 L internal volume, fully dehydrated and degassed 1.5 L of n-hexane, 30 mmol of triethylaluminum, 3 mmol of cyclohexylethyldimethoxysilane and Comparative Example 1 described in JP-A No. 2003-105018 7.5 g of solid catalyst component was added, 15 g of propylene was continuously supplied over 30 minutes while maintaining the internal temperature of the tank at 5 to 15 ° C., and after preactivation, the obtained solid catalyst slurry was added to the internal volume. It was transferred to a 200 L SUS autoclave equipped with a stirrer, diluted with 140 L of liquid butane, and stored at a temperature of 5 ° C. or lower.

[Polymerization of propylene copolymer]
(First step)
In a SUS polymerization tank equipped with a stirrer with an internal volume of 40 L, liquid propylene 45 Kg / h, hydrogen 40 NL / h, 1-butene 7.2 Kg / h were supplied, and the preactivated solid catalyst component 0.7 mmol / H, triethylaluminum 41 mmol / h and cyclohexylethyldimethoxysilane 5.7 mmol / h, liquid propylene was used as a medium under the conditions of maintaining the polymerization temperature at 55 ° C. and the substantial amount of slurry retained in the tank at 18 L. The slurry polymerization was continued. The amount of propylene polymer produced at this time was 1.3 kg / hr. The obtained slurry containing the polymer was continuously transferred to the second step polymerization tank without being deactivated.

(Second step)
In a gas phase fluidized bed reactor with a stirrer with an internal volume of 1 m ^3, the amount of polymer retained in the fluidized bed is 75 kg, the polymerization temperature is 70 ° C., the polymerization pressure is 1.4 MPa, the hydrogen concentration in the gas phase is 0.8 vol%, the gas phase The solid catalyst component-containing polymer transferred from the first-stage reactor is supplied and continuously polymerized under the condition that propylene, hydrogen and 1-butene are supplied so as to maintain the 1-butene concentration of 11.1 vol%. The polymer was obtained in a yield of 21.9 Kg / h by continuing.

[Granulation]
0.1 parts by weight of Sumilizer GP (manufactured by Sumitomo Chemical), 0.1 parts by weight of Irgafos 168 (manufactured by Ciba Specialty Chemicals), hydrotalcite (Kyowa Chemical Industry) with respect to 100 parts by weight of the obtained polymer Made by DHT-4C), mixed and added to a 40 mmΦ single-screw extruder (manufactured by Tanabe Plastic Machine, VS40-28 type extruder), melt-kneaded at 220 ° C. to form a strand Extruded, cooled and solidified in a 25 ° C. water bath, cut into chips and pelletized.

  A butene-propylene random copolymer having a butene content of 11.0% by weight, an MFR of 18 g / 10 min and a total content of aluminum, magnesium, titanium, silicon and iron of 91 ppm was obtained as a butene- A stretched film was obtained in the same manner as in Example 1 except that it was used in place of the propylene random copolymer (A) and the temperature at which the film was stretched was 145 ° C.

[Comparative Example 1]
When the raw sheet was stretched in the same manner as in Example 1 except that the master batch (C) was not added, the film was broken and a stretched film was not obtained.

[Comparative Example 2]
Instead of the butene-propylene random copolymer (A), the ethylene content is 0.6% by weight, the MFR is 2.4 g / 10 min, and the total content of aluminum, magnesium, titanium, silicon and iron is 79 ppm. A stretched film was obtained in the same manner as in Example 1 except that an ethylene-propylene random copolymer (Sumitomo Chemical Co., Ltd., FS2011DG3) was used.

[Comparative Example 3]
Instead of the butene-propylene random copolymer (A), the ethylene content is 1.2% by weight, the MFR is 2.4 g / 10 min, and the total content of aluminum, magnesium, titanium, silicon and iron is 84 ppm. A stretched film was obtained in the same manner as in Example 1 except that an ethylene-propylene random copolymer (Sumitomo Chemical Co., Ltd., WF464N) was used.

[Comparative Example 4]
Instead of the butene-propylene random copolymer (A), ethylene having an ethylene content of 3% by weight, an MFR of 2.6 g / 10 min, and a total content of aluminum, magnesium, titanium, silicon and iron of 50 ppm A stretched film was obtained in the same manner as in Example 1 except that a propylene random copolymer (manufactured by Sumitomo Chemical Co., Ltd., FH3315) was used and the temperature at which the film was stretched was 145 ° C.

[Comparative Example 5]
0.1 part by weight of Sumilizer GP (manufactured by Sumitomo Chemical), 0.1 part by weight of Irgafos 168 (manufactured by Ciba Specialty Chemicals), 100 parts by weight of the polymer after the first step of Example 2 Add 0.01 parts by weight of talcite (manufactured by Kyowa Chemical Industry Co., Ltd., DHT-4C), mix, feed to 40mmΦ single screw extruder (manufactured by Tanabe Plastic Machinery, VS40-28 type extruder), and melt knead at 220 ° C. It was extruded into strands, cooled and solidified in a 25 ° C. water bath, cut into chips and pelletized.

  A butene-propylene random copolymer having a butene content of 5% by weight, an MFR of 3.8 g / 10 min and a total content of aluminum, magnesium, titanium, silicon and iron of 335 ppm was obtained as a butene- When the original fabric sheet was stretched in the same manner as in Example 1 except that it was used in place of the propylene random copolymer (A), the film was broken and no stretched film was obtained.

[Comparative Example 6]
[Preactivation of solid catalyst]
An SUS autoclave with an internal volume of 3 L and sufficiently dehydrated and degassed 1.5 L of n-hexane, 30 mmol of triethylaluminum, 3 mmol of cyclohexylethyldimethoxysilane and Example 1 described in JP-A-2007-277527 7.5 g of solid catalyst component was added, 15 g of propylene was continuously supplied over 30 minutes while maintaining the internal temperature of the tank at 5 to 15 ° C., and after preactivation, the obtained solid catalyst slurry was added to the internal volume. It was transferred to a 200 L SUS autoclave equipped with a stirrer, diluted with 140 L of liquid butane, and stored at a temperature of 5 ° C. or lower.

[Polymerization of propylene copolymer]
In an SUS polymerization tank with an internal volume of 40 L and equipped with a stirrer, 9 kg / h of liquid propylene, 2.2 NL / h of hydrogen, 2.0 kg / h of 1-butene, and a preactivated solid catalyst component of 0. 64 mmol / h was fed, and in addition, triethylaluminum and cyclohexylethyldimethoxysilane were fed so that the concentrations were 35 mmol / L and 5.3 mmol / L, respectively, and the polymerization temperature was 50 ° C. Slurry polymerization using liquid propylene as a medium was continued under the condition of maintaining the pressure at 18 L. The amount of propylene polymer produced at this time was 1.2 kg / hr.

[Granulation]
0.1 parts by weight of Sumilizer GP (manufactured by Sumitomo Chemical), 0.1 parts by weight of Irgafos 168 (manufactured by Ciba Specialty Chemicals), hydrotalcite (Kyowa Chemical Industry) with respect to 100 parts by weight of the obtained polymer Made by DHT-4C), mixed and added to a 40 mmΦ single-screw extruder (manufactured by Tanabe Plastic Machine, VS40-28 type extruder), melt-kneaded at 220 ° C. to form a strand Extruded, cooled and solidified in a 25 ° C. water bath, cut into chips and pelletized.

  A butene-propylene random copolymer having a butene content of 5% by weight, an MFR of 0.3 g / 10 min and a total content of aluminum, magnesium, titanium, silicon and iron of 509 ppm was obtained as a butene- A stretched film was obtained in the same manner as in Example 1 except that it was used in place of the propylene random copolymer (A) and the temperature at which the film was stretched was 145 ° C.

＊金属量はアルミニウム、マグネシウム、チタン、ケイ素および鉄の含量の合計である。

* The amount of metal is the sum of the contents of aluminum, magnesium, titanium, silicon and iron.

Claims (3)

Β-crystal nucleating agent (component (B)) 0 with respect to 100 parts by weight of the polypropylene resin (component (A)) satisfying all of the following requirements (1) and (2) and component (A) Polypropylene resin composition containing 0.01 to 5 parts by weight.
Requirement (1): A butene-propylene random copolymer having a structural unit derived from butene of 1 to 15% by weight (provided that the total weight of the butene-propylene random copolymer is 100% by weight).
Requirement (2): The total content of aluminum, magnesium, titanium, silicon and iron measured with an inductively coupled plasma optical emission spectrometer is 200 ppm or less The polypropylene resin composition according to claim 1 or 2, wherein the β crystal nucleating agent (B) is an amide compound represented by the following general formula (I).

R ² —NHCO—R ¹ —CONH—R ³ (I)
(In the formula, R ¹ represents a divalent aromatic group. R ² and R ³ are the same or different and represent a monovalent aromatic group or a monovalent alicyclic group.)   A porous film obtained by stretching and forming the polypropylene resin composition according to claim 1.