JP2000302926A - Polypropylene composition for drawn film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene composition for a drawn film having excellent appearance, blocking resistance and scratch resistance and causing little falling off of antiblocking agent in the processing of the film. SOLUTION: The objective polypropylene composition is composed of 100 pts.wt. of a crystalline polypropylene resin and 0.01-0.5 pt.wt. in total of (A) polyhedral inorganic particles having an average particle diameter of 0.1-4 μm and (B) spherical organic or inorganic particles having an average particle diameter of 0.1-3 μm. The weight ratio (A/B) of the polyhedral inorganic particle to the spherical organic or inorganic particle is adjusted to 1-9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel polypropylene composition for a stretched film (hereinafter, also referred to as a resin composition for a film). Specifically, for a film capable of obtaining a stretched polypropylene film (hereinafter, also referred to simply as a stretched PP film) which has good appearance, blocking resistance, and scratch resistance, and has a small amount of a blocking agent generated during film processing, which is less likely to fall off. The present invention provides a resin composition.

[0002]

2. Description of the Related Art Stretched PP films have excellent mechanical properties,
Although it is a film having both high gloss and transparency, since the film surface is smooth, a so-called blocking phenomenon that the films stick to each other occurs, and various improvements have been made to prevent such a phenomenon.

For example, Japanese Patent Application Laid-Open No. 56-30855 discloses a method of improving the blocking property of a co-extruded multilayer composite stretched film by using a polypropylene resin containing a blocking resistance agent.

[0004] A composition using cubic calcium carbonate as the anti-blocking agent is known. The polyhedral inorganic particles such as the cubic calcium carbonate exhibit optimum slip properties such that phenomena such as unwinding do not occur at the time of winding on a roll in film production, as well as scratch resistance and falling resistance. It has excellent properties and is expected to be further applied to a stretched PP film.

[0005]

However, in a stretched PP film containing polyhedral inorganic fine particles, peeling voids are easily generated at the interface between the inorganic fine particles and the polypropylene resin, and as a result, the appearance of the film is deteriorated. Have a problem. The present inventors have confirmed that this problem is more significant when crystalline polypropylene having relatively high crystallinity is used, and in particular, as the draw ratio increases.

Accordingly, an object of the present invention is to provide a resin composition for a film in which polyhedral inorganic fine particles are blended with an antiblocking agent, to produce voids caused by the polyhedral inorganic fine particles when a stretched PP film is produced. It is an object of the present invention to provide a polypropylene composition for a stretched film having an excellent appearance in which the content is suppressed.

[0007]

Means for Solving the Problems The present inventors have intensively studied to achieve the above object. As a result, a crystalline polypropylene resin, as a blocking agent, a resin composition for a film using a specific spherical organic or inorganic particles in combination with polyhedral inorganic particles (hereinafter, also simply referred to as spherical particles) in a specific ratio, When this is formed into a stretched film, the problems caused by the generation of voids can be prevented very effectively, and a stretched PP film having an excellent appearance can be obtained. Good blocking resistance, scratch resistance,
The inventors have found that they exhibit excellent characteristics without impairing the falling-off resistance, and have completed the present invention.

That is, the present invention relates to polyhedral inorganic particles (A) having an average particle size of 0.1 to 4 μm and an average particle size of 0.1 to 3 μm per 100 parts by weight of crystalline polypropylene.
m) in a total amount of 0.01 to 0.5 part by weight, and the polyhedral inorganic particles (A) and the spherical organic or inorganic particles (B). A weight ratio ((A) / (B)) with respect to B) is in the range of 1 to 9, which is a polypropylene composition for a stretched film.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the resin composition for a film of the present invention, known crystalline polypropylene is used without any particular limitation. As the polypropylene,
Examples thereof include a propylene homopolymer, a propylene-α-olefin copolymer of propylene and an α-olefin other than propylene, and a mixture thereof.

The propylene-α-olefin copolymer has a monomer unit content of 2 mol% or less based on one or more α-olefins other than propylene,
Further, it is preferably 1 mol% or less of a propylene-α-olefin copolymer or a mixture thereof.
Examples of the α-olefin include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-
Octene, 1-nonene, 1-decene, 4-methyl-1-
Penten and the like can be mentioned. The propylene-α-olefin copolymer may be any of a random copolymer and a block copolymer, and among them, a random copolymer is preferable.

As the method for producing the above polypropylene resin, in addition to conventionally known titanium-based and vanadium-based catalysts, a polypropylene resin obtained by a method using a metallocene catalyst comprising a metallocene compound and alumoxane is preferably used. can do.

[0013] ¹³ C-
The isotactic pentad fraction by NMR is not particularly limited, but is preferably in the range of 0.90 to 0.99, and more preferably in the range of 0.93 to 0.98. preferable.

The isotactic pentad fraction referred to here is the value of A.D. Five consecutive propylene units quantified based on the peak assignments of the ¹³ C-NMR spectrum published by Macromolecules, ¹³ , 267 (1980) by A. Zambelli et al. Is the fraction taking the same three-dimensional configuration.

[0014] The melt flow rate of the above polypropylene is generally 0.1 to 0.1 in view of the moldability into a film.
Those having a range of 20 g / 10 minutes are preferable.
More preferably, the range is 10 g / 10 minutes. Further, the weight average molecular weight is 200,000 to 800,00.
0, preferably in the range of 250,000 to 450,000.

The above polypropylene has a weight average molecular weight (M
The molecular weight distribution represented by the ratio (Mw / Mn) between w) and the number average molecular weight (Mn) is not particularly limited,
In consideration of the ease of forming the film and the fact that the melt tension is increased and the workability is improved, it is preferably from 2 to 20, and more preferably from 3 to 10. The molecular weight distribution is a value measured by gel permeation chromatography using o-dichlorobenzene as a solvent (hereinafter also referred to as GPC), and the calibration curve is calibrated with standard polystyrene.

The amount of soluble p-xylene at room temperature in the polypropylene is not particularly limited, but is preferably in the range of 8% by weight or less, and more preferably in the range of 5% by weight or less.

The melting point of the polypropylene is preferably 150 ° C. or higher, more preferably 155 ° C. or higher, and further preferably 158 ° C. or higher.

The melting point of polypropylene mentioned here is a peak temperature of a crystal melting curve at the time of temperature rise measured by a differential scanning calorimeter (hereinafter also referred to as DSC).

As described above, when a stretched PP film is produced by blending polyhedral inorganic particles with crystalline polypropylene having relatively high crystallinity, a phenomenon occurs in which the appearance of the film is deteriorated due to generation of voids.

The resin composition for a film of the present invention may be used as a blocking agent to be added to the crystalline polypropylene resin having relatively high crystallinity as described above. Are used together in a specific ratio. That is, in the resin composition for a film, the polyhedral inorganic particles added as a blocking agent to the crystalline polypropylene have advantages such as less falling off during film processing, but the polyhedral organic particles and the polypropylene resin. Has the disadvantage that peel voids, which lead to a decrease in the film appearance, are likely to occur at the interface of the film, but by using specific spherical particles in a specific ratio in combination with this, the occurrence of such peel voids can be prevented very effectively. Has been clarified by the study of the present inventors. Moreover, the combined use of the spherical particles does not impair the properties of the polyhedral inorganic particles, such as falling resistance, blocking resistance, and scratch resistance.

In the present invention, the polyhedral inorganic particles (A)
Is used without particular limitation, having a multi-faceted shape composed of a plurality of planes. For example, a triangular pyramid, a rectangular parallelepiped, a heptahedron, an octahedron, and the like can be given. In particular, a particle observed with a scanning electron microscope (hereinafter abbreviated as SEM) has six to eight corner portions as vertices. Among them, a perfect rectangular parallelepiped having eight corner portions, of which a cube is particularly preferable, is preferable because falling off during film processing is reduced.

Further, it is particularly desirable that the corner portion serving as the vertex of the inorganic particle has a slightly rounded shape and extremely few sharp edge portions, because the scratch resistance is good.

The material of the polyhedral inorganic particles is not particularly limited. For example, metal carbonates such as calcium carbonate, sodium carbonate and potassium carbonate, zeolites, talc, silica, calcium phosphate and the like are generally used. Calcium carbonate is preferred. As the polyhedral inorganic particles made of these materials, those obtained by a known method are used without any particular limitation.

In particular, Japanese Patent Application Laid-Open Nos.
A metal carbonate such as calcium carbonate manufactured by the method described in US Pat. No. 196316 is suitable because it is a substantially perfect cube.

The surfaces of these polyhedral inorganic particles are subjected to a so-called surface treatment in which a silane coupling agent, silicon oil, aminomethyl treatment, and a chemical and physical treatment of an organic carboxylic acid and an organic carboxylic acid metal salt are applied. It is preferably used because it can further suppress the occurrence of peeling voids in the appearance of the film.

In the present invention, the polyhedral inorganic particles (A) must have an average particle size (in the case of particles having a major axis and a minor axis, an average major axis) in the range of 0.1 to 4 μm. , More than 0.5 μm and preferably 3.5 μm or less, and more preferably more than 1 μm and 3 μm or less. Here, the average particle size is a value obtained by observing 100 or more particles with a SEM and averaging the respective particle sizes. If the average particle size is less than 0.1 μm, no anti-blocking performance is exhibited, while
If it exceeds 0 μm, voids formed by peeling off the interface between the inorganic particles and the polypropylene resin become large, which is not preferable because the appearance of the film is deteriorated.

On the other hand, in the resin composition for a film of the present invention, the spherical organic or inorganic particles (B) having a particle diameter ratio (particle major axis / minor axis) in the range of 1 to 1.5 are as follows: This is necessary for effectively reducing the coefficient of friction, and is more preferably in the range of 1 to 1.3.

The spherical particles (B) must have an average particle size (particles having a major axis and a minor axis having an average major axis) in the range of 0.1 to 3 μm. A range of 5 μm is preferable, and a range of 1 to 2 μm is more preferable. When the average particle diameter of the spherical particles is less than 0.1 μm, the performance of preventing blocking is reduced. On the other hand, when the average particle diameter is more than 3 μm, the effect of preventing peeling voids is not sufficiently exhibited, and the appearance of the film is reduced. Is unfavorable because it decreases.

The material of the spherical particles (B) is not particularly limited. Examples thereof include cross-linked polymethyl methacrylate (hereinafter, referred to as cross-linked PMMA), non-melting type silicone resin powder, melanin resin powder, polyamide resin powder, Silica powder and the like are common. As the spherical particles made of these materials, those obtained by a known method are used without any particular limitation.

It is also preferable that the average particle size (La) of the polyhedral organic particles (A) and the average particle size (Lb) of the spherical particles (B) satisfy (La) ≧ (Lb). This is preferred for improving the properties and more effectively reducing the falling off of the antiblocking agent.

The resin composition for a film according to the present invention comprises:
The polyhedral inorganic particles (A) and the spherical organic or inorganic particles (B) are contained in a total amount of 0.01 to 0.5 part by weight based on 100 parts by weight of the crystalline polypropylene resin. Is required, and the content is preferably in the range of 0.02 to 0.4 part by weight, and more preferably in the range of 0.03 to 0.3 part by weight. When the total amount of addition is less than 0.01 part by weight, anti-blocking performance is not exhibited, and when the addition amount exceeds 0.5 part by weight,
It is not preferable because the appearance and transparency of the film are reduced.

In the stretched PP film obtained by using the resin composition for a film of the present invention, the polyhedral inorganic particles (A) and the spherical particles (B) exhibit an effect by projecting on the film surface. In this case, the polyhedral inorganic particles (A) and the spherical particles (B) projecting on the film surface are:
In addition to the surface of the particles exposed from the film surface,
Particles whose surfaces protrude from the film surface in a state of being covered with a resin thin film also effectively work to develop film characteristics.

That is, the resin thin film covering the protruding particles is generally very thin, and reflects the shape of the projection surface as it is. Therefore, the anti-blocking performance of these particles exhibits the same effect regardless of the presence or absence of the resin thin film on the protruding surface. Further, as the composition ratio of the anti-blocking agent, the weight ratio of the polyhedral inorganic particles (A) to the spherical organic or inorganic particles (B) ((A) / (B))
Must be in the range of 1 to 9, and 1.2 to 7.
5, preferably 1.5 to 6
More preferably, it is within the range. Weight ratio (A) /
When (B) is less than 1, the anti-blocking agent, particularly the spherical particles (B), which are generated during the processing of the film, tends to fall off. On the other hand, when the weight ratio exceeds 9, the appearance of the film deteriorates. This is not preferable because the coefficient of friction increases and slipperiness decreases. In particular, when a highly crystalline polypropylene resin is used or the stretching ratio is increased for the purpose of improving the mechanical strength of the film, etc., the orientation of the molecular chains in the film is increased, so that the polyhedral inorganic particles (A) and the polypropylene are used. In order to prevent the occurrence of peeling voids at the resin interface and reduce the appearance of the film, the weight ratio ((A) / (B)) of the polyhedral inorganic particles (A) to the spherical particles (B) is 6 The following is preferred.

The resin composition for a film of the present invention may contain other resins in addition to the above polypropylene, as long as the effects of the present invention are not impaired. The resin to be blended is not particularly limited, but is generally ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene,
Polyolefin-based resins such as α-olefin homopolymers such as decene and 4-methyl-1-pentene, copolymers of these α-olefins, or a mixture of two or more of these polymers, and fats And thermoplastic resins such as petroleum resins such as aromatic hydrocarbon resins, alicyclic hydrocarbon resins, rosin derivatives, terpene resins, terpene phenol resins and the like, and hydrogenated resins thereof.

Further, the resin composition for a film of the present invention comprises:
If necessary, crystal nucleating agent, stabilizer, antioxidant, chlorine scavenger, antistatic agent, antifogging agent, ultraviolet absorber, lubricant, surfactant, pigment, filler, foaming agent, foaming auxiliary, Various known additives such as a plasticizer, a cross-linking agent, a cross-linking aid, a flame retardant, a dispersant, a processing aid, and a filler may be blended as long as the effects of the present invention are not impaired.

As a method for producing a stretched PP film using the resin composition for a film of the present invention, a known method can be employed without any particular limitation.

For example, the resin composition for a film is formed into a sheet or a film (hereinafter, abbreviated as an unstretched sheet) by a T-die method or an inflation method. Next, the unstretched sheet is supplied to the MD stretching apparatus, and the heating roll temperature is 100 to 170 ° C., 4 to 15 times, preferably 5 to 15 times.
MD stretching at 13 times, followed by 4 to 15 times at a tenter temperature of 110 to 180 ° C. using a tenter, preferably 5 to
TD stretching at 13 times, and in the above stretching, the area stretching ratio, which is the product of the MD stretching ratio and the TD stretching ratio, is 25 to 1
A method of adjusting the stretching conditions so as to increase the magnification by 20 times may be mentioned.

Furthermore, after biaxial stretching, the MD and TD may be reduced to 80 to 180% while allowing 0 to 15% relaxation.
You may use together the method of heat-processing at ° C. Needless to say, after these stretching, if necessary, the film may be stretched again to MD or TD, and a stretching method such as multi-stage stretching or rolling may be combined in MD stretching.

The layer structure of the stretched PP film obtained from the resin composition for a film of the present invention may be a single layer or a multilayer. In the case of a multilayer, a so-called co-extrusion method in which a film is formed using a multilayer die or an in-line lamination method in which a molten resin is laminated on a formed sheet can be used. In this case, it is preferable that at least the surface layer is constituted by the resin composition for a film of the present invention. In such an embodiment, the center layer is formed by laminating a layer composed of a polypropylene composition in which the amount and type of other additives are changed. can do. Particularly preferred are raw materials in which the above-mentioned polyhedral inorganic particles (A), the above-mentioned spherical particles (B), slit assistants, and lubricants were used for the surface layer, and an antistatic agent, a crystal nucleating agent, and the like were used for the central layer. A three-layer structure is preferable in terms of optical properties and surface properties of the film.

Further, one or both surfaces of the stretched PP film obtained from the resin composition for a film of the present invention may be subjected to a surface treatment such as a corona discharge treatment if necessary.

The thickness of the obtained stretched PP film is not particularly limited, but a known range of 10 μm to 100 μm is more general than the stretchability, the productivity such as the winding property of the film, and the needs of the market.

[0042]

EFFECTS OF THE INVENTION By using the resin composition for a film of the present invention, a roll which is excellent in appearance, blocking resistance and scratch resistance as compared with a conventionally known polypropylene film and which comes into contact with the film at the time of secondary processing. A stretched PP film having both the quality and the productivity, in which the resistance to falling off of the blocking agent is extremely unlikely to occur on the surface or the like, can be obtained.

[0043]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, the raw materials used in the following Examples and Comparative Examples and the obtained stretched polypropylene films were evaluated by the following methods.

1. Evaluation method of raw material 1-1. Isotactic pentad fraction (mmmm), α
-Olefin content JNM-GSX-270 ( ^13C- nuclear resonance frequency 6 manufactured by JEOL Ltd.)
7.8 MHz) under the following conditions.

Measurement mode: 1H-complete decoupling Pulse width: 7.0 microseconds (C45 degrees) Pulse repetition time: 3 seconds Integration frequency: 10000 times Solvent: mixed solvent of orthocyclohexanesene / deuterated benzene (90/10 Sample concentration: 120 mg / 2.5 ml Solvent Measurement temperature: 120 ° C. In this case, the isotactic pentad fraction is ¹³ C—N
It was determined by measuring the splitting peak in the methyl group region of the MR spectrum. The peak in the methyl group region was assigned according to the method described in A. According to A. Zambelli et al. [Macromolecules, 13, 267 (1980)].

1-2. Melt flow rate (MFR) Measured according to ASTM 1238.

1-3. Weight average molecular weight (Mw), molecular weight distribution (Mw / Mn) High temperature GPC device SSC-7100 manufactured by Senshu Kagaku
Was measured under the following conditions.

Solvent: orthodichlorobenzene Flow rate: 1.0 ml / min Column temperature: 145 ° C. Detector: high-temperature differential refraction detector Column: “SHODEX UT” 807, 806M, 806 manufactured by Showa Denko KK
M, 802.5, connected in series Sample concentration: 0.1% by weight Injection amount: 0.50 ml 1-4. Room temperature p-xylene solubles [p-Xy.sol.] 1 g of raw material polymer was added to 100 ml of p-xylene,
After the temperature was raised to 120 ° C. with stirring, stirring was further continued for 30 minutes to completely dissolve the polymer to prepare a uniform solution. The p-xylene solution was allowed to cool to room temperature (23 ° C.) and then left at room temperature (23 ° C.) for 24 hours. Thereafter, the precipitated gel was separated from the gel, and the amount of soluble matter was determined by completely concentrating the p-xylene solution.

Room temperature p-xylene solubles [p-Xy.sol.]
Is determined by the following equation.

[P-Xy.sol.] (% By weight) = {p-xylene solubles (g) / polymer 1 (g)} × 100 1-5. Melting point Using a DSC device DSC6200 manufactured by Seiko Electronics Co., Ltd.
The measurement was performed under the following conditions.

Sample amount: about 5 mg Atmospheric gas: nitrogen (flow rate: 20 ml / min) Temperature condition: After maintaining at 230 ° C. for 10 minutes, 10 ° C./min.
The temperature was lowered to 30 ° C. per minute, and the endothermic behavior of melting when the temperature was raised at 10 ° C./min was measured.

2. Evaluation method of stretched film 2-1. Film appearance Four-stage evaluation (（, △, Δ, ×) was performed by visual observation.

2-2. Blocking resistance 300 mm, width (T)
D) A sample cut out into a strip of 40 mm in the direction is laminated with a film so as to have a thickness of 3 mm to form a sample. The sample was left under an atmosphere of 30 ° C. and 70% humidity for 24 hours, and then a film sample was applied with a pressure of 20 kg / cm ² for 30 seconds using a press machine. Both ends of the film sample were fixed with jigs, and the bending strength was measured using a tensile tester.

2-3. Scratch resistance In order to evaluate the easiness of damage when the films are rubbed, two films were prepared, and one of the films (20 ×
30 cm) was fixed as the lower film. The other film is used as the upper film, and the diameter of the upper film is 10 cm.
The lower film was brought into contact with the circle by applying a load of 4.6 kg on the area of the circle, and the upper film was horizontally rubbed back and forth 5 times for 20 cm. The haze value before and after performing the above operation
Measured according to -K6714, and the difference between the haze value after rubbing and the haze value before rubbing is defined as scratch haze, and when the difference is 0% to less than 1.5%, ◎, 1.5 to 3.
0 is less than 0, 3% to less than 6% is Δ, 6% or more is x,
A four-point evaluation was performed.

2-4. Drop-off resistance Fusing seal bag making machine (manufactured by Kyoei Printing Machinery Co., Ltd .; PP
500 type) at a speed of 25 m / min.
(00 mm). At this time, a black cloth was wound so that the contact area with the film was 5 cm × 60 cm from the upper part of the folded part of the film (near the apex of the triangular plate), and bag making was performed until the unwinding length of the film reached 2000 m. Was. The weight change of the black cloth after bag making was measured. When the amount of the adhered white powder is 0 mg or more and less than 2 mg,
A score of 、 ４ from 6 mg to less than 10 mg was evaluated as 、, a score of 6 mg or more and less than 10 mg was evaluated as △, and a score of 10 mg or more was evaluated as ×.

2-5. Slip property The dynamic friction coefficient and the static friction coefficient were measured according to ASTM-D-1894.

2-6. Transparency (haze value) This was performed according to JIS K 7105.

Example 1 (Preparation of resin pellets) Polypropylene A shown in Table 1
100 parts by weight of a powder of 2,6-
0.1 parts by weight of di-t-butylhydroxytoluene, 0.1 parts by weight of calcium stearate as a chlorine scavenger, and 0.3 parts by weight of stearyl diethanolamide as an antistatic agent were added. After mixing 0.05 parts by weight of polyhedral calcium carbonate having an average particle diameter of 2.1 μm and 0.02 parts by weight of a spherical melanin resin powder having an average particle diameter of 1.9 μm for 5 minutes using a Henschel mixer as shown in FIG. It was extruded at 230 ° C. using a 65 mmφ extrusion granulator, and the pellets were granulated to obtain raw material pellets.

(Production of Biaxially Stretched Film) Using the obtained polypropylene raw material pellets, a biaxially oriented film was produced by the following method. The polypropylene raw material pellets were heated and melted at 280 ° C. using a T-die sheet extruder having a screw diameter of 90 mmφ, extruded, and formed into a raw unstretched sheet having a thickness of about 2 mm with a cooling roll at 30 ° C.
Next, a biaxially stretched film was manufactured from the unstretched sheet using a tenter-type sequential biaxial stretching apparatus as follows. First, the unstretched sheet is subjected to MD by a hot roll stretching machine.
The film was longitudinally stretched 5.5 times. Subsequently, the film was stretched to TD with a mechanical magnification of 10.0 times by a tenter transverse stretching machine, and then 8% in TD.
A heat treatment was performed by relaxing the film, and a biaxially stretched film having a thickness of 30 μm was formed. In addition, the thickness of the biaxially stretched film,
It was adjusted by the extrusion amount of the T-die sheet extruder (the thickness of the raw unstretched sheet).

On one side of the biaxially stretched film, 3
After subjecting to a corona discharge treatment of 0 W min / m ² and winding, the obtained biaxially stretched film was aged at 40 ° C. for 3 days.

Table 3 shows the physical properties of the obtained film.

Example 2 (Preparation of resin pellets) Polypropylene A shown in Table 1
100 parts by weight of a powder of 2,6-
0.1 parts by weight of di-t-butylhydroxytoluene, 0.1 parts by weight of calcium stearate as a chlorine scavenger, and cubic calcium carbonate having an average particle size of 2.1 μm as shown in Table 2 as a blocking inhibitor. 0.0
5 parts by weight and 0.02 parts by weight of a spherical melanin resin powder having an average particle size of 1.9 μm were added, mixed with a Henschel mixer for 5 minutes, and then kneaded using an extrusion granulator having a screw diameter of 65 mmφ to obtain resin pellets S. I got

Also, 100 parts by weight of the powder of polypropylene A shown in Table 1 was added with 2,6-di-
0.1 part by weight of t-butylhydroxytoluene, 0.1 part by weight of calcium stearate as a chlorine scavenger and 0.3 part by weight of stearyldiethanolamide as an antistatic agent were added, and mixed with a Henschel mixer for 5 minutes. The mixture was kneaded using an extrusion granulator having a screw diameter of 65 mm to obtain a resin pellet C.

(Film Formation) Using the obtained polypropylene resin pellets S and C, a biaxially stretched film was formed by the following method. Polypropylene resin pellets,
Using a three-layer sheet extruder with one main extruder and two satellite extruders, the sheet was extruded at 280 ° C., and a 1 mm thick sheet was formed with a cooling roll at 30 ° C. Resin pellets S were supplied to the satellite extruder, and resin pellets C were supplied to the main extruder, and extruded from the T-die at a ratio of the main extruder 8 to the satellite extruder 1 at each extrusion rate. Other than that, it carried out similarly to Example 1.

Table 3 shows the measurement results of various physical properties of the obtained film.

Example 3 The formulation of the anti-blocking agent shown in Example 1 is shown in Table 2.
As shown in the figure, 0.06 parts by weight of polyhedral calcium carbonate having an average particle diameter of 2.1 μm and 0.01 parts by weight of a spherical melanin resin powder having an average particle diameter of 1.9 μm, that is, a weight ratio (A) / (B) ) Was adjusted to 6.0 to perform the same procedure as in Example 1. Table 3 shows the results.

Example 4 The biaxial stretching ratio shown in Example 1 was the same as in Example 1 except that the MD stretching ratio was 8.5 times and the TD stretching ratio was 11.5 times as shown in Table 2. went. Table 3 shows the results.

Example 5 Table 2 shows the composition of the antiblocking agent shown in Example 1.
As shown in Example 1, the same procedure as in Example 1 was carried out except that 0.05 parts by weight of cubic calcium carbonate having an average particle diameter of 2.1 μm and 0.02 parts by weight of spherical crosslinked PMMA having an average particle diameter of 2.0 μm were blended. Was. Table 3 shows the results.

Example 6 Table 2 shows the composition of the antiblocking agent shown in Example 1.
As shown in Example 1, the same procedure was performed as in Example 1 except that 0.05 parts by weight of cubic calcium carbonate having an average particle diameter of 2.1 μm and 0.02 parts by weight of spherical silica powder having an average particle diameter of 2.0 μm were mixed. Was. Table 3 shows the results.

Example 7 Table 2 shows the composition of the antiblocking agent shown in Example 1.
As shown in the figure, 0.05 part by weight of a plate-shaped synthetic talc having an average particle size of 2.5 μm, and a spherical crosslinked PMM having an average particle size of 2.0 μm
The same procedure was performed as in Example 1 except that 0.02 parts by weight of A was blended. Table 3 shows the results.

Comparative Example 1 Table 2 shows the composition of the anti-blocking agent shown in Example 1.
As shown in Example 1, the same procedure as in Example 1 was carried out except that only 0.06 parts by weight of cubic calcium carbonate having an average particle size of 2.1 μm was blended. Table 3 shows the results.

Comparative Example 2 Table 2 shows the composition of the anti-blocking agent shown in Example 1.
As shown in Example 2, the same procedure as in Example 1 was carried out except that only 0.06 parts by weight of a spherical melanin resin powder having an average particle size of 1.9 μm was blended. Table 3 shows the results.

Comparative Example 3 Table 2 shows the composition of the antiblocking agent shown in Example 1.
As shown in Example 1, the same procedure was performed as in Example 1 except that 0.05 parts by weight of spherical silica powder having an average particle diameter of 2.0 μm and 0.01 parts by weight of melanin resin powder having an average particle diameter of 1.9 μm were mixed. . Table 3 shows the results.

COMPARATIVE EXAMPLE 4 The anti-blocking agent shown in Example 1 was replaced with an average particle size of 2.1.
0.05 parts by weight of cubic calcium carbonate having a particle diameter of 0.05 μm, and 0.02 parts by weight of plate-like synthetic talc having an average particle diameter of 2.0 μm, that is, the weight ratio (A) / (B) is 2.5 Except having performed, it carried out similarly to Example 1.

Table 3 shows the measurement results of various physical properties of the obtained film.

Comparative Example 5 Table 2 shows the composition of the anti-blocking agent shown in Example 1.
As shown in Example 1, except that 0.05 parts by weight of cubic calcium carbonate having an average particle diameter of 4.1 μm and 0.02 parts by weight of a spherical melanin resin powder having an average particle diameter of 1.9 μm were blended. went. Table 3 shows the results.

Comparative Example 6 Table 2 shows the composition of the antiblocking agent shown in Example 1.
As shown in Example 1, except that 0.05 parts by weight of cubic calcium carbonate having an average particle diameter of 2.1 μm and 0.02 parts by weight of spherical melanin resin powder having an average particle diameter of 3.5 μm were blended. went. Table 3 shows the results.

Comparative Example 7 Table 2 shows the formulation of the antiblocking agent shown in Example 1.
As shown in the figure, 0.02 parts by weight of cubic calcium carbonate having an average particle diameter of 2.1 μm and 0.04 parts by weight of a spherical melanin resin powder having an average particle diameter of 1.9 μm, that is, a weight ratio (A) / (B) ) Was added in the same manner as in Example 1, except that 0.5 was added. Table 3 shows the results.

Comparative Example 8 Table 2 shows the composition of the anti-blocking agent shown in Example 1.
As shown in Example 1, except that 0.50 part by weight of cubic calcium carbonate having an average particle diameter of 2.1 μm and 0.20 part by weight of a spherical melanin resin powder having an average particle diameter of 1.9 μm were mixed. went. Table 3 shows the results.

Example 8 Example 8 was carried out in the same manner as in Example 1 except that polypropylene B shown in Table 1 was used as a raw material polypropylene. Table 3 shows the results.

Comparative Example 9 Table 2 shows the composition of the antiblocking agent shown in Example 1.
As shown in Example 8, the same procedure as in Example 8 was carried out except that 0.05 parts by weight of a spherical silica powder having an average particle diameter of 2.0 μm and 0.02 parts by weight of a spherical melanin resin powder having an average particle diameter of 1.9 μm were mixed. Was. Table 3 shows the results.

[0082]

[Table 1]

[0083]

[Table 2]

[0084]

[Table 3]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) B29K 105: 16 B29L 7:00 F term (reference) 4F071 AA20 AA41 AB21 AD02 AD06 AF11 AF58 BA01 BB06 BB07 BC01 4F210 AA11 AB06 AB09 AB16 AB19 AB24 AC04 AE01 AG01 AG03 QA02 QA03 QC16 QG01 QG15 QG18 4J002 BB131 BB141 BG062 CC182 CL002 CP032 DE226 DE236 DH046 DJ006 DJ016 DJ017 DJ046 FA006 FA082 FA087 FD202 FD206 FD207 GG02

Claims (3)

[Claims] 1. A polyhedral inorganic particle (A) having an average particle size of 0.1 to 4 μm and a spherical organic or inorganic particle having an average particle size of 0.1 to 3 μm based on 100 parts by weight of crystalline polypropylene. Particles (B) in a total amount of 0.01 to 0.5 parts by weight, and the weight ratio of the polyhedral inorganic particles (A) to the spherical organic or inorganic particles (B) (( (A) / (B)) is in the range of 1 to 9; 2. An average particle diameter (L) of the polyhedral inorganic particles (A).
The polypropylene composition for a stretched film according to claim 1, wherein the average particle diameter (Lb) of a) and the organic or inorganic particles (B) is (La) ≥ (Lb). 3. A stretched polypropylene film comprising the polypropylene composition according to claim 1.