JPH06184371A - Stretched propylene polymer film - Google Patents

Abstract

PURPOSE:To obtain a polymer composition excellent in see-through, transparency and blocking resistance and suitable as the material of a stretched film by mixing a propylene polymer with a metal salt of an aryl phosphate, fine inorganic articles coated with an organic compound, and a specified wax. CONSTITUTION:This polymer film is made from a composition prepared by mixing 100 pts.wt. propylene polymer with 0.005-0.5 pt.wt. metal salt of an aryl phosphate, 0.01-0.8 pt. wt. fine inorganic particles coated with an organic compound and 0.1-10 pts.wt. olefin polymer wax having an intrinsic viscosity [eta]of 0.1-0.6dl/g. This film has the following properties: (a) the formation of voids due to the antiblocking agent used during stretching can be inhibited, (b) the formation of large-diameter voids due to the see-through improver used can be inhibited, and (c) it is desirable as a material in the fields of packaging and print lamination on printed matter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a propylene polymer stretched film having excellent properties such as transparency, blocking resistance and slipperiness (sliding property).

[0002]

BACKGROUND OF THE INVENTION Stretched films made of olefin polymers are widely used for various packaging films, etc. because they have excellent optical properties such as transparency and gloss, and good mechanical properties such as rigidity and tensile strength. Has been done.

However, depending on the application, these characteristics still do not satisfy the required level sufficiently,
Above all, in applications requiring transparency, optical unevenness peculiar to a propylene polymer film becomes a problem, resulting in a situation in which the field of use is significantly limited.

Further, when propylene polymer films are superposed, a small amount of inorganic fine particles such as silicon dioxide, calcium carbonate and magnesium oxide is blended in order to prevent blocking which occurs between layers. Although blocking is reduced by this measure, voids (voids) having the inorganic fine particles as nuclei are generated by stretching. As a result, the transparency and transparency, which are great advantages of the propylene polymer film, are impaired. Therefore, attempts have been proposed to improve the optical properties of the stretched propylene polymer film.

Regarding the improvement of the transparency, for example, a method of blending a nucleating agent such as a benzylidene sorbitol derivative (JP-A-54-77654 and JP-A-58-87024).
Japanese Patent Laid-Open No. 60-139428), a polypropylene stretched film containing a 3-position branched α-olefin polymer having 6 or more carbon atoms or a polymer of vinylcycloalkane (JP-A-60-139428) is proposed.

On the other hand, measures for preventing the decrease in transparency due to the incorporation of an anti-blocking agent such as inorganic fine particles have already been disclosed in the following publications. Polypropylene resin containing silica (silicon dioxide) having a primary particle size of 800 nm or less and a surfactant having a polyoxyethylene group, both on a composition basis.
A method for producing a stretched polypropylene film having excellent transparency and blocking resistance, which comprises 1 to 2% by weight (JP-A-51-288798), and 2% by weight or more of the inorganic fine particles of a terpene resin. Stretched by surface treatment with a hydrocarbon-based resin selected from petroleum resin and rosin, and blending the inorganic fine particles in a proportion of 0.02 to 1 part by weight with respect to 100 parts by weight of the resin component in the polypropylene-based resin layer. Polypropylene film (Japanese Patent Laid-Open No. 63-295640), 0.5 parts by weight or less of an anti-blocking agent based on 100 parts by weight of a specific polypropylene, and a main chain having at least one hydroxyl group at the end is saturated or partially saturated. Hydrocarbon Polymer 0.0
A polypropylene resin composition for a biaxially stretched film, containing 1 to 2 parts by weight (JP-A-64-38458 and JP-A-64-40547).

[0007]

However, the measures for increasing the transparency of the stretched film made of a propylene polymer and the measures for preventing the decrease in transparency due to the incorporation of an antiblocking agent, which are disclosed by the above-mentioned prior invention, are superior to those in the prior art. If the effect is improved. However, achieving high levels of both of these at the same time remains unresolved. In other words,
Due to the effect of the transparency improving agent that is added to improve the transparency, voids due to the antiblocking agent are likely to occur during stretching. As a result, the improvement in transparency remained insufficient.

When a benzylidene sorbitol derivative is blended as a see-through improver, the benzylidene sorbitol derivative bleeds from the resin to cause roll fouling during film formation or strong odor during processing, which limits the use. ing. In particular, when a transparency improving agent having a melting point of 300 ° C. or higher is blended, when the obtained propylene polymer film is stretched, large-diameter (large-grain) voids resulting from the transparency improving agent are generated, and the resulting film is obtained. The appearance of is not practically usable.

[0009]

Means for Solving the Problems As a result of intensive studies for solving the problems associated with the prior art, the present inventors have found that a specific aryl ester metal salt of phosphoric acid is added to a propylene polymer,
Good transparency is obtained by using a propylene polymer composition in which inorganic particles with an organic compound coating and a specific olefin polymer wax are blended in specific amounts, respectively.
The inventors have found that a stretched film having both transparency and blocking resistance can be obtained, and completed the present invention.

The present invention comprises the following constitutions: (1) 0.005-0.5 parts by weight of a metal salt of an aryl phosphate ester and 100 parts by weight of inorganic fine particles coated with an organic compound per 100 parts by weight of a propylene polymer. A stretched film made of a propylene polymer, which is obtained by blending 01 to 0.8 part by weight and 0.1 to 10 parts by weight of an olefin polymer wax having an intrinsic viscosity [η] of 0.1 to 0.6 dl / g. (2) The stretched film made of a propylene polymer as described in (1) above, wherein the inorganic fine particles coated with an organic compound have an average particle size of 1 to 7 μm. (3) The stretched film made of a propylene polymer as described in the above item (1), wherein the olefin polymer wax has a melting point of 90 to 140 ° C.

The above configuration of the present invention will be specifically described below. [Propylene Polymer] As the base crystalline propylene polymer constituting the composition of the present invention, melt flow rate [MFR (230 ° C .; 2.16 kgf)] 0.5-10 g / 10 min, preferably 1-7 g / Stereoregularity index (II) 90-9 at 10 min
9, preferably 95-99 crystalline propylene homopolymer, crystalline random copolymer or crystalline block of propylene having a propylene unit content of 95 mol% or more and ethylene or one or more α-olefin having 4 or more carbon atoms. Copolymers can be used. Α with 4 or more carbon atoms
-Examples of olefins include 1-butene and 4-methyl-1-
Pentene, 1-hexene, 1-octene, 1-decene and the like can be mentioned. As long as the polymer has the above composition, two or more kinds of crystalline polymers can be mixed and used.

In particular, when the film is required to have rigidity, a crystalline propylene homopolymer, and when it is required to have transparency and heat sealability, the propylene unit content is 95 to 98.
A crystalline copolymer of mol% propylene and one or more kinds of ethylene or α-olefin having 4 or more carbon atoms is preferable.

[Metal salt of phosphoric acid aryl ester] The metal salt of phosphoric acid bisaryl ester is preferred as the above-mentioned aryl metal ester of phosphoric acid constituting the propylene polymer composition which is the material for the stretched film of the present invention. And the following can be exemplified: sodium-2,2-
Methylenebis (4,6-di-t-butylphenyl) phosphate, sodium-2,2-methylenebis (4,6-di-t-butylphenyl) phosphate sodium-2,2-ethylidenebis (4,6-di-) t-Butylphenyl) phosphate, lithium-
2,2-Methylenebis (4,6-di-t-butylphenyl) phosphate, lithium-2,2-ethylidenebis (4,6-di-t-butylphenyl) phosphate, sodium-2,2-ethylidenebis ( 4-i-propyl-6-t-butylphenyl) phosphate, calcium-bis [2,2-thiobis (4-methyl-6-t)
-Butylphenyl) phosphate], magnesium-bis [2,2-thiobis (4,6-di-t-butylphenyl) phosphate], sodium-diphenylphosphate and sodium-bis (pt-butylphenyl) phosphate.

Among the above-mentioned phosphoric acid diaryl ester metal salts, preferred is phosphoric acid-2,2-alkylidene bis (4,6-di-t-alkylphenyl) ester metal salt, specifically sodium- 2,2-methylenebis (4,6-di-
t-butylphenyl) phosphate.

[Inorganic fine particles coated with organic compound] The following are examples of the above-mentioned inorganic fine particles constituting the raw material propylene polymer composition for the stretched film of the present invention: Silicon dioxide as the raw material inorganic compound, Calcium carbonate, magnesium oxide, kaolin, zeolite, aluminum silicate. .. Examples of the organic compound used for coating the inorganic fine particles include ethylene-based polymer wax, propylene-based polymer wax, fatty acid amide, and organic silane coupling agent. Among them, ethylene-based polymer wax and unsaturated fatty acid amide having 16 or more carbon atoms are preferable.

The coating amount on the inorganic fine particles coated with an organic compound is 1 to 5 relative to the weight of the inorganic fine particles.
0% by weight is preferred. When the coating amount is 0.5% by weight or less, the void suppression effect is insufficient and the transparency of the obtained stretched film becomes unusable for practical use. On the other hand, if the coating amount is 55% by weight or more, the blocking resistance becomes insufficient.

In the present invention, the average particle size of the inorganic fine particles coated with an organic compound is measured by the Coulter counter method. Preferred fine particles have a measured value of 1 to 7 μm. Particularly preferred fine particles have an average particle size of 1.5 to 5 μm.
belongs to. Fine particles with an average particle size of 0.5 μm or less are not sufficient for imparting blocking resistance to a level that can be practically used.
It is difficult for the fine particles of 10 μm or more to give the stretched film a level of transparency that can be practically used.

[Olefin Polymer Wax] The olefin polymer wax constituting the material composition of the stretched film of the present invention has an intrinsic viscosity [η] of 0.1.
An ethylene polymer wax or a propylene polymer wax having an amount of up to 0.6 dl / g, preferably 0.2 to 0.4 dl / g can be exemplified. When the intrinsic viscosity [η] is 0.05 dl / g or less, whitening of the film occurs and the blocking resistance is substantially lost. The reason seems to be that the wax having a low intrinsic viscosity easily migrates to the film surface. On the other hand, when the intrinsic viscosity is 0.8 dl / g or more, the appearance of the stretched film becomes unsuitable. The cause seems to be that large-diameter (large-grain) voids occur frequently in the stretched film.

Further, as the olefin polymer wax constituting the raw material propylene polymer composition of the stretched film of the present invention, one having a melting point (described later) of 90 to 140 ° C., preferably 100 to 125 ° C. is used. When an olefin polymer wax having a melting point of 85 ° C. or less is used, the resulting stretched film has insufficient blocking resistance and slipperiness. On the other hand, when an olefin polymer wax having a melting point of 145 ° C. or higher is used, the resulting stretched film lacks transparency and cannot be put to practical use. It is considered that this is because the wax cannot sufficiently suppress the generation of large-diameter voids due to the aryl phosphate metal salt.

As the above-mentioned olefin polymer wax,
Those containing a small amount of polar groups such as carboxyl groups or acid anhydride groups in the molecular chain, for example, oxidation type ethylene polymer wax (oxide of ethylene polymer wax), acid-modified ethylene polymer wax (of ethylene polymer wax An acid-modified product) or an acid-modified propylene polymer wax (acid-modified propylene polymer wax) or the like may be used.

As the modifier used for the acid modification, maleic acid and maleic anhydride (maleic anhydride) are preferable. [Blending Amount of Each Component] (1) The blending amount of the aryl phosphate metal salt is 0.005 to 100 parts by weight of the base propylene crystalline polymer.
The amount is 0.5 part by weight, preferably 0.01 to 0.1 part by weight. When the amount is less than 0.003 parts by weight, the transparency is insufficient, and when the amount is more than 0.8 parts by weight, large-diameter (large-grain) voids frequently occur. This phenomenon is presumed to be due to poor dispersion of the aryl phosphate metal salt. (2) The compounding amount of the inorganic fine particles with an organic compound coating is 0.1 with respect to 100 parts by weight of the base propylene crystalline polymer.
The amount is 01 to 0.8 part by weight, preferably 0.05 to 0.4 part by weight. If the blending amount is 0.005 parts by weight or less, the antiblocking property becomes insufficient, and if the blending amount is 1 part by weight or more, the transparency is lowered to the extent that it cannot be practically used. (3) The compounding amount of the olefin polymer wax is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the base propylene crystalline polymer. Compounding amount 0.05
When the amount is less than or equal to parts by weight, it becomes difficult to effectively suppress the generation of large-diameter voids due to the alkyl aryl ester phosphate metal salt.
As a result, the appearance of the stretched film becomes unsuitable. On the other hand, if the compounding amount is 15 parts by weight or more, not only the blocking resistance is unacceptably lowered, but also the heat resistance and rigidity originally possessed by the propylene crystalline polymer as a base material are unacceptably lowered.

[Mixing Method of Various Components] There is no particular limitation on the mixing method of each of the above components constituting the raw material propylene polymer composition for preparing the stretched film of the present invention. Usually, the base propylene crystalline polymer, the antiblocking agent and the olefin polymer wax are uniformly mixed by a mixing means such as a Henschel mixer (trade name) or a tumbler mixer, and then melt-kneading means, for example, 180 by an extruder.
By melt-mixing and pelletizing at a temperature of ˜300 ° C., a uniformly mixed raw material propylene polymer composition can be obtained. Further, the aryl phosphate metal salt, the masterbatch containing a high concentration of antiblocking agent and the propylene crystalline polymer as a base material may be dry blended.

Further, the propylene polymer composition as a raw material for producing the stretched film of the present invention contains a heat stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, an antistatic agent, if necessary.
As the transparency improving agent and other additives, various additives usually added to the propylene crystalline polymer can be blended.

[Production Method of Stretched Film] The stretched film of the present invention can be produced from a material propylene polymer composition by a known molding method. "Stretching" in the present invention
Includes both uniaxial stretching and biaxial stretching, and biaxial stretching includes both simultaneous biaxial stretching and sequential biaxial stretching. Further, both uniaxial stretching and biaxial stretching also include a multi-stage stretching in the same axis, that is, a treatment in which stretching until a predetermined stretching ratio is achieved is divided into two or more stages.

[0025]

EXAMPLES The following examples are given for specifically explaining the present invention, but the present invention is not limited thereto. In the following examples and comparative examples, the property measurement and evaluation of each component constituting the material propylene polymer composition for forming a stretched film to be used and the property measurement and evaluation of the obtained stretched film are performed by the following methods. It carried out in conformity. -Characteristic value of each component (1) Base material Propylene crystalline polymer melt flow rate (MFR) According to JIS K 6758. (2) Copolymerization Ratio of Base Material Propylene Crystalline Polymer [Method] Calculated from the area of each peak measured by ¹³ C-NMR method. [Apparatus] (Brand name) FT-NMR spectrometer (G
X-270) (manufactured by JEOL Ltd.) [Conditions] Observation width: 12000 Hz; pulse angle: 3.5
Degree; pulse interval: 4.5 sec; temperature: 130 ° C .; solvent: mixed solution of orthodichlorobenzene and deuterated bromobenzene (bromobenzene-d5); cumulative number: 10,000 times or more (3) olefin polymer wax Intrinsic Viscosity [η] [Device] (Brand Name) Automatic Viscosity Measuring Device AVS2 Model (Mitsui Toatsu Co., Ltd.) [Conditions] Temperature: 135 ° C; Solvent: Tetrahydronaphthalene (Tetralin) (4) Melting point of olefin polymer wax [Method] The temperature at which the peak of the endothermic curve obtained by the following measurement is located is determined. When there are two or more peaks, the temperature is the temperature at which the peak with the largest area is located. [Apparatus] Differential scanning calorimeter [Brand name: DSC7 type (manufactured by Perkin-Elmer)] [Conditions] Starting temperature: 0 ° C; Temperature rising rate: 20 ° C / min ・ Characteristic value of stretched film (5) Transparent sample Place the film in front of the naked eye and see through a square (2 mm x 2 mm) object 3 m away from the naked eye. Observation is performed while increasing the number of sample films to be superposed, and the maximum number of superimpositions that allows a square object to be clearly seen is used as a measure of transparency. The larger the number, the better the transparency. (6) Transparency [Measurement method] "Haze value" is measured according to ASTM D-1003. [Evaluation] The smaller the haze value, the better the transparency. (7) Number of voids [Device] Optical microscope with camera (magnification: 100 times) [Method] Photograph 10 points of the sample film, count the number of voids of each point photographed by the camera, and average the value to 1 mm. Convert to ² . (8) Number of large-diameter (large-grain) voids [Apparatus] Optical microscope (magnification: 50 times) [Method] The sample film (10 cm ² ) is observed with the microscope to count the number of large-diameter voids (maximum diameter 100 μm). (9) Blocking resistance [Evaluation] The blocking degree is measured, and the smaller it is, the more
It is evaluated as excellent in blocking resistance. [Method] Use a sample film (7 cm x 2 cm rectangle) with a length of 2
Overlay cm (overlapping area: 4 cm ² ).
A load of 1 kgf is placed on this superposed surface and left to stand (temperature 40 ° C .; humidity 50% RH; 24 h). The maximum force required to shear and separate the contact surfaces of both sample films is measured with a tensile tester. (10) Sliding property [Evaluation] The smaller the dynamic friction coefficient measured according to ASTM D-1894, the better the sliding property.

[0026]

Example 1 Powdery propylene crystalline homopolymer (MF
R 2.5 g / 10 min) 100 parts by weight of sodium-2,2-methylenebis (4,6-di-t-butylphenyl) phosphate.
03 parts by weight, synthetic silica coated with an ethylene polymer wax (average particle size: 1.8 μm; coating amount: 10)
% By weight) 0.25 part by weight, ethylene polymer wax (intrinsic viscosity [η] 0.31 dl / g; melting point 107 ° C.) 1 part by weight, 2,6
-Di-t-butyl-p-cresol 0.1 part by weight, tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane 0.1 part by weight and hydrotalcite [trade name DHT- 4A (manufactured by Kyowa Chemical Co., Ltd.)] 0.05 parts by weight are mixed, and the mixture is mixed with a Henschel mixer (trade name).
Then, the mixture was charged into the reactor and dry-blended for 3 minutes, and then melt-kneaded at a temperature of 250 ° C. into pellets using a single-screw extruder (cylinder diameter 40 mm).

The obtained propylene polymer composition was used as T
-Melting extrusion (resin temperature 260 ° C) with an extruder with a die,
The unstretched sheet (thickness: 1.0 mm) was molded by winding around a cooling drum (40 ° C.) and solidifying by cooling. Then, the obtained unstretched sheet is heated at a temperature of 158 using a batch type biaxial stretching machine.
Biaxial stretching at ℃ (5.0 times in the extrusion direction, 8.0 times in the transverse direction)
Thus, a biaxially stretched film (thickness: 25 μm) was obtained.

The surface of the obtained biaxially stretched film was corona treated to have a wetting index of 40 dyn / cm. The characteristics of this surface-treated biaxially stretched film are shown in Table 1.

[0029]

Examples 2 to 6 and Comparative Examples 1 and 2 The same operation as in Example 1 was carried out except that the kind and amount of the aryl phosphate metal salt were changed as shown in Table 1.
The properties of the obtained biaxially stretched film are shown in Table 1.

[0030]

Comparative Examples 3 to 5 Similar to Examples except that dibenzylidene sorbitol or aluminum hydroxy-bis (pt-butylbenzoate) was added in the amount shown in Table 1 in place of the aryl phosphate metal salt. The operation was performed. The characteristics of the obtained film are shown in Table 1.

[0031]

Example 7 Powdery propylene-ethylene crystalline binary copolymer (MFR 3.8 g / 10 min; propylene component content 9)
8.8 mol%) to 100 parts by weight of sodium-2,2-methylenebis (4,6-di-t-butylphenyl) phosphate 0.02
Part by weight, synthetic silica with erucamide coating (average particle size: 2.5 μm; coating amount: 5% by weight) 0.2
Parts by weight, oxidized ethylene polymer wax (intrinsic viscosity [η]
0.21 dl / g; melting point 107 ° C .; acid value 2 mg-KOH / g) 0.7 part by weight, 2,6-di-t-butyl-p-cresol 0.1 part by weight and tetrakis [methylene (3,5- Di-t-butyl-4-hydroxyhydrocinnamate)] methane (0.1 part by weight) and calcium stearate (0.1 part by weight) are mixed, the mixture is charged into a Henschel mixer (trade name), and dry blended for 3 minutes, and then uniaxial. The mixture was melt-kneaded (temperature 240 ° C.) with an extruder (cylinder diameter 40 mm) and pelletized.

The obtained propylene polymer composition was used as T
-Melting extrusion (resin temperature 250 ° C) with an extruder equipped with a die,
The unstretched sheet (thickness: 1.2 mm) was formed by winding around a cooling drum (40 ° C.) and solidifying by cooling. The obtained unstretched sheet was biaxially stretched at a temperature of 155 ° C. (5.0 times in the extrusion direction and 8.0 times in the transverse direction) using a batch type biaxial stretching machine to give a biaxially stretched film (thickness). : 30 μm) was obtained.

The surface of the obtained biaxially stretched film was corona treated to have a wetting index of 40 dyn / cm. The properties of this surface-treated biaxially stretched film are shown in Table 2.

[0034]

Examples 8 to 13 and Comparative Examples 6 to 8 The same operation as in Example 7 was carried out except that the kind and the amount of the inorganic fine particles coated with an organic compound were changed as shown in Table 2. The characteristics of the obtained biaxially stretched film are shown in Table 2.

[0035]

Example 14 Powdery propylene crystalline homopolymer (M
FR 2.5 g / 10 min) 100 parts by weight of sodium-2,2-methylenebis (4,6-di-t-butylphenyl) phosphate 0.03 parts by weight, ethylene polymer wax coated synthetic silica (average particle size: 2 .1 μm; coating amount:
15% by weight) 0.25 parts by weight, propylene polymer wax (intrinsic viscosity [η] 0.35 dl / g; melting point 135 ° C.) 1.5 parts by weight, 2,6-di-t-butyl-p-cresol 0.2. 1 part by weight, tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane 0.1 part by weight and calcium stearate 0.1 part by weight were mixed, and the mixture was mixed with Henschel mixer (trade name). Then, the mixture was charged into the reactor and dry-blended for 3 minutes, and then melt-kneaded at a temperature of 250 ° C. into pellets using a single-screw extruder (cylinder diameter 40 mm).

The obtained raw material propylene polymer composition was treated with T
-Melting extrusion (resin temperature 260 ° C) with an extruder with a die,
The unstretched sheet (thickness: 1.0 mm) was molded by winding around a cooling drum (40 ° C.) and solidifying by cooling. Then, the obtained unstretched sheet is heated at a temperature of 158 using a batch type biaxial stretching machine.
Biaxial stretching at ℃ (5.0 times in the extrusion direction, 8.0 times in the transverse direction)
Thus, a biaxially stretched film (thickness: 25 μm) was obtained.

The surface of the obtained biaxially stretched film was corona treated to have a wetting index of 40 dyn / cm. The characteristics of this surface-treated biaxially stretched film are shown in Table 3.

[0038]

Examples 15 to 19 and Comparative Examples 9 to 12 The same operation as in Example 14 was carried out except that the kind of the olefin polymer wax and the compounding amount thereof were changed as shown in Table 3.
The characteristics of the obtained biaxially stretched film are shown in Table 3.

[0039]

EFFECTS OF THE INVENTION The biaxially stretched film of the present invention has the following features: -It has extremely excellent transparency-It has extremely good transparency and appearance-Stretching due to an antiblocking agent Elimination of generation of voids ・ Elimination of generation of large-diameter voids by transparency improving agent ・ Good blocking resistance ・ Excellent in slipperiness ・ Suitable as a material in the fields of packaging and print lamination of printed materials.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

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Claims (3)

[Claims] 1. A metal salt of an aryl ester of phosphoric acid, 0.005-0.5, based on 100 parts by weight of a propylene polymer.
Part by weight, inorganic fine particles with organic compound coating 0.0
A stretched film made of a propylene polymer, which comprises 1 to 0.8 part by weight and 0.1 to 10 parts by weight of an olefin polymer wax having an intrinsic viscosity [η] of 0.1 to 0.6 dl / g. 2. The stretched film made of a propylene polymer according to claim 1, wherein the inorganic fine particles coated with an organic compound have an average particle diameter of 1 to 7 μm. 3. The olefin polymer wax has a melting point of 90 to 90.
The propylene polymer stretched film according to claim 1 or 2, which is at 140 ° C.