JPH0639975A - Biaxially oriented multi-layer film - Google Patents

Abstract

PURPOSE:To obtain a good antistatic property of a biaxially oriented multi-layer film which is excellent in both of stiffness and heat shrinkage resistance by a method wherein a base material layer is prepared by mixing a specific amount of highly crystalline polypropylene compound, and a front surface layer prepared by mixing a polyolefin wax and a blocking-inhibitor in crystalline polypropylene is provided to at least its one side face. CONSTITUTION:A base material layer is prepared by mixing a specific amount of a compound obtained by allowing polyoxyethylenealkylamine or polyoxyethylenealkenylamine obtained by adding ethylene oxide to diethanol amine of the formula (1) and amine of the formula R1NH2 (R, R1 is a 12-22C alkyl group or alkenyl group) to react with a 12-22C higher fatty acid, in a highly crystalline polypropylene wherein a relation between a melt flow rate (MRH) and an isotactic pentad fraction (P) becomes a formula 1.00<=P0.015log MER+0.955. A front surface layer is prepared by mixing a polyolefin wax and a blocking inhibitor in the crystalline polypropylene on its one side surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene biaxially stretched multilayer film having excellent rigidity and heat shrinkage resistance and good antistatic properties.

[0002]

2. Description of the Related Art Polypropylene biaxially stretched films are used in a wide variety of fields such as food packaging, fiber packaging and industrial applications, by taking advantage of their excellent mechanical properties and good transparency.
However, in recent years, with the speeding up of secondary processing steps such as printing, laminating or automatic packaging, the rigidity and heat shrinkage resistance of conventional polypropylene biaxially stretched films are no longer satisfied. Therefore, as a measure for improving the rigidity and the heat shrinkage resistance of the polypropylene biaxially stretched film, the use of highly crystalline polypropylene has been studied.

[0003]

The biaxially oriented polypropylene film using highly crystalline polypropylene has a high degree of molecular orientation and crystallization of the raw material polypropylene, resulting in improved rigidity and heat shrinkage resistance. Even if the conventionally used antistatic agent is mixed with crystalline polypropylene, the antistatic effect is not sufficiently exhibited. As a result, problems such as defective transfer of the printing ink to the film surface and adhesion of dust occur in the secondary processing step, which causes problems such as static electricity, and solving this problem becomes a new problem.

[0004]

[Means for Solving the Problems] The present inventors have conducted extensive studies on imparting antistatic properties to a biaxially stretched film using a highly crystalline polypropylene. As a result, a composition in which a specific amount of Compound A and a specific compound of Compound B were blended with a specific highly crystalline polypropylene was used as a base layer, and the isotactic pentad fraction (P) was 0 on at least one surface of the base layer. .90
A biaxially stretched multilayer film in which a composition in which a specific amount of a polyolefin wax and an antiblocking agent is mixed with crystalline polypropylene in the range of 0 to 0.945 is laminated as a surface layer is a film having excellent antistatic properties. Based on this finding, the present invention has been completed.

That is, the present invention provides a highly crystalline polypropylene in which the relationship between the melt flow rate (MFR) and the isotactic pentad fraction (P) satisfies the equation 1.00 ≧ P ≧ 0.015 log MFR + 0.955. , The general formula

[Chemical 2] Alkyldiethanolamine or alkenyldiethanolamine represented by (hereinafter referred to as compound A)
0.05 to 0.20% by weight with respect to the composition, an alkylamine represented by the general formula R ₁ NH ₂ (wherein R ₁ is an alkyl group or an alkenyl group having 12 to 22 carbon atoms), or At least one selected from polyoxyethylene alkylamines or polyoxyethylene alkenylamines obtained by adding 2-3 mols of ethylene oxide to 1 mol of alkenylamines and higher fatty acids having 12 to 22 carbon atoms.
A compound obtained by reacting with a higher fatty acid of a species (hereinafter,
It is called compound B. Is used as a base material layer, and the isotactic pentad fraction (P) is 0.900 to at least one surface of the base material layer. Composition of crystalline polypropylene in the range of 0.945 with 0.1 to 3.0% by weight of polyolefin wax having a softening point of 140 ° C. or less, and an average particle size of 5 μm or less with respect to the composition. The composition is a biaxially stretched multi-layered film, wherein a composition in which 0.05 to 0.5% by weight is blended is laminated as a surface layer.

The MFR is a melt flow index of polypropylene measured under JIS K 7210, condition 14 (230 ° C., 2.16 kgf), and its unit is g / 10 min. Also, the isotactic pentad fraction (P)
And A. Zambelli et al., Macromolecules Vol. 6, No. 6, 925-926 (197).
3 years) [Macromolecules, Vol.6, No.6, 925-926 (197
3)], that is, an isotactic chain in a pentad unit in a polypropylene molecular chain measured using ¹³ C-NMR, in other words, 5 consecutive propylene monomer units are meso-bonded. Is the fraction of propylene monomer units in the chain formed. Where ¹³ C-N
The attribution of the MR spectrum can be found in MacroMolecules 8
Volume, No. 5, 687-689 (1975) [Macromol
ecules, Vol.8, No.5, 687-689 (1975)]. Incidentally, the measurement of (P) in the examples described later was carried out by using a 270 MHz FT-NMR apparatus at 27,000.
The signal detection limit was calculated as a fraction of 0.
The test was carried out after improving it to 001.

The highly crystalline polypropylene used in the present invention is a highly crystalline polypropylene in which the relationship between the isotactic pentad fraction (P) and MFR satisfies the following formula: 1.00 ≧ P ≧ 0.015log MFR + 0.955. Is. There is no particular limitation on the MFR of this highly crystalline polypropylene, and it is usually 0.5 to 0.5 which is usually used for polypropylene biaxially stretched films.
The range of 10 g / 10 min is used.

The meaning of the relational expression between the isotactic pentad fraction (P) and MFR is such that (P) generally shows a low value in polypropylene having a low MFR.
It defines the lower limit of (P) corresponding to the MFR of the highly crystalline polypropylene to be used. Further, since (P) is a fraction, the upper limit value is 1.00.

Such highly crystalline polypropylene can be produced, for example, by the method described in JP-A-58-104907. That is, as the organoaluminum compound (I), for example, triethylaluminum, diethylaluminum monochloride or the like or a reaction product (VI) of the organoaluminum compound (I) with an electron donor such as diisoamyl ether or ethylene glycol monomethyl ether is used. The solid product (II) obtained by reacting with titanium tetrachloride, further, an electron donor and an electron acceptor, for example, anhydrous aluminum chloride, titanium tetrachloride, vanadium tetrachloride obtained by reacting a solid product ( III) is an organoaluminum compound (IV) such as triethylaluminum or diethylaluminum monochloride, and an aromatic carboxylic acid ester (V) such as alkyl benzoate, methyl p-toluate, ethyl p-toluate or p-toluyl. Acid-2- Hexyl and the like and combinations, 0.1 and aromatic carboxylic acid ester (V) solid product (III) molar ratio of (V / III)
It is obtained by polymerizing propylene in one or more steps in the presence of a catalyst set to 10.0. 1 in this case
By stage is meant a segment of continuous or temporary feeding of these monomers.

In the present invention, the above highly crystalline polypropylene is mixed with another polyolefin within a range satisfying the relationship between the isotactic pentad fraction (P) and the MFR. You can also Other polyolefins include propylene homopolymer, propylene as a main component, and propylene and α-such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-octene. A crystalline random copolymer or a crystalline block copolymer obtained by copolymerizing one or more kinds of olefins, ultra low density polyethylene, low density polyethylene, linear low density polyethylene, medium density polyethylene, Polyethylenes such as high density polyethylene, poly-1-butene, poly-4-methyl-1
Examples thereof include polyolefins such as pentene, synthetic rubbers such as ethylene / propylene copolymer rubber and ethylene / propylene / non-conjugated diene copolymer rubber.

Examples of the compound (A) used in the present invention include beef tallow fatty acid diethanolamine, stearyldiethanolamine, oleyldiethanolamine, behenyldiethanolamine, palmityldiethanolamine, and the like. The compound (A) is a composition for the highly crystalline polypropylene. 0.05 to 0.20% by weight is compounded on the basis. When the compounding amount of the compound (A) is less than 0.05% by weight, the antistatic effect is extremely slow to develop and it is difficult to put it to practical use. On the other hand, if the blending amount exceeds 0.20% by weight, the surface of the biaxially stretched multilayer film becomes sticky, and the films are likely to block each other.

The compound (B) used in the present invention is an alkyl (or alkenyl) represented by the general formula R ₁ NH ₂ (wherein R ₁ is an alkyl group or an alkenyl group having 12 to 22 carbon atoms). ) Polyoxyethylene alkyl (or polyoxyethylene alkenyl) amine obtained by adding 2-3 mol of ethylene oxide to 1 mol of amine and carbon number 12
The compound obtained by reacting with at least one higher fatty acid selected from the higher fatty acids of 22 to 22.

The compounding amount of the compound (B) with respect to the highly crystalline polypropylene is 0.5 to 1.5% by weight based on the composition. If the content is less than 0.5% by weight, a sufficient antistatic effect cannot be obtained, and if it exceeds 1.5% by weight, bleeding of the compound (B) becomes remarkable on the surface of the biaxially stretched multilayer film, The transparency, printability and laminating suitability of the film are impaired.

In the highly crystalline polypropylene used for the base layer of the film of the present invention, in addition to the above-mentioned compounds (A) and (B), for example, antioxidants, light stabilizers, nucleating agents, lubricants, Various additives that are usually added to crystalline polypropylene, such as a neutralizing agent, can be used together within a range that does not impair the object of the present invention.

The crystalline polypropylene used for the surface layer of the film of the present invention is a homopolymer of propylene and has an isotactic pentad fraction (P) of 0.900.
In the range of 0.945 and its MFR is 0.5 to 15
It is in the range of g / 10min. Here, the isotactic pentad fraction (P) of crystalline polypropylene is 0.
When it is less than 900, the heat shrinkage resistance of the obtained biaxially stretched multilayer film is lowered, and it is difficult to prevent blocking. Further, when the (P) exceeds 0.945, the bleed-out of the antistatic agent used on the film surface decreases, and as a result, the obtained film does not exhibit a good antistatic effect.

The polyolefin wax blended with the crystalline polypropylene used for the surface layer is a low molecular weight high density polyethylene, low density polyethylene, polypropylene or the like obtained by polymerization or decomposition, and has a softening point (JI
SK 6758) is 140 ° C. or less. The polyolefin wax may be modified with an unsaturated carboxylic acid or its derivative, an ethylenically unsaturated silane compound, or a special monomer. By blending the polyolefin wax, the time for the antistatic agent present in the base material layer to migrate to the surface of the biaxially stretched multilayer film is shortened, and the antistatic effect can be accelerated. Further, it also has an effect of reducing voids caused by a peeling phenomenon between the anti-blocking agent and the polymer caused by stretching, and has an effect of preventing deterioration of transparency of the film due to incorporation of the anti-blocking agent.

The softening point of the polyolefin wax is 14
When it exceeds 0 ° C, migration of the antistatic agent to the surface layer is slow, and voids are generated due to the antiblocking agent, so that the transparency of the obtained biaxially stretched multilayer film is lowered. The blending amount of the polyolefin wax is 0.1 to 3.0% by weight based on the composition. If the blending amount of the polyolefin wax is less than 0.1% by weight, the antistatic effect is slowly exhibited, and voids are observed due to the antiblocking agent, which impairs the transparency and cannot be put to practical use. If it exceeds 3.0% by weight, the bleeding of the polyolefin wax and the antistatic agent becomes remarkable, and the transparency of the film, the printability and the suitability for lamination are impaired.

The crystalline polypropylene used for the surface layer further has an average particle size of 5 μm for the purpose of preventing the film from blocking and adsorbing an antistatic agent to maintain the antistatic effect.
Anti-blocking agent of m or less 0.05 to
Add 0.5 wt%. Here, the anti-blocking agent is not only inorganic fine particles such as calcium carbonate, silica, aluminum silicate, and zeolites, but also organic fine particles that do not melt at the processing temperature of crystalline polypropylene. Here, the average particle size of the antiblocking agent is a value measured by the Coulter counter method. When the average particle size of the antiblocking agent exceeds 5 μm, the transparency of the obtained biaxially stretched multilayer film is significantly deteriorated. Further, if the blending amount of the antiblocking agent is less than 0.05% by weight, the antiblocking effect is insufficient, and if it exceeds 0.5% by weight, the transparency is deteriorated.

In addition to the anti-blocking agent, the crystalline polypropylene used for the surface layer includes, for example, an anti-oxidant, an antistatic agent, a light stabilizer, a nucleating agent, a lubricant, a neutralizing agent and the like. Various additives usually added to the above can be added within a range that does not impair the object of the present invention. The composition used for the base layer and the surface layer of the present invention is a ribbon blender and a Henschel mixer (trade name), respectively.
After mixing with a mixer such as described above, it can be prepared by melt-kneading with a kneader such as an extruder.

As a method of obtaining a biaxially stretched multilayer film, for example, a sheet in which a surface layer is laminated on one side or both sides of a base material layer by melt-coextruding a composition used for the base material layer and a composition for a surface layer And a method of biaxially stretching it, melt-extruding the composition for the surface layer to an unstretched or uniaxially stretched substrate layer sheet, and then laminating it and then biaxially stretching it or uniaxially stretching it in the direction perpendicular to the stretching direction of the substrate layer. There are ways to do it. It is desirable that the surface of the biaxially stretched multilayer film on which the surface layers are laminated is subjected to corona discharge treatment to accelerate the bleeding of the antistatic agent onto the film surface.

The total thickness of the biaxially stretched multilayer film thus obtained is selected according to its purpose and is usually 5-10.
It is in the range of 0 μm, preferably 10 to 60 μm. The thickness of the surface layer is not particularly limited as long as it does not impair the rigidity and heat shrinkage, which are the characteristics of the highly crystalline polypropylene of the base material layer, but it is usually in the range of 1 to 5 μm.
In addition, the thickness ratio (total thickness / surface layer thickness) of both layers is 20 /
It is desirable to set to 0.5 to 20/8, preferably 20/1 to 20/5.

[0022]

EXAMPLES The present invention will be described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The physical properties of the films in Examples and Comparative Examples were measured by the following methods. (1) Haze: According to ASTM D 1003. (2) Young's modulus: in accordance with ASTM D882. A film having a higher Young's modulus indicates a film having higher rigidity. (3) Heat shrinkage ratio: length (L ₀ ) 20 cm × width 1 in each of MD (longitudinal direction) and TD (horizontal direction) measurement directions
Each sample piece was cut out and heated in an oven at 140 ° C. for 15 minutes, and then each length (L ₁ ) cm
And the heat shrinkage rate (S%) in each measuring direction according to the following formula
I asked. S = 100 × (L ₀ −L ₁ ) / L ₀

(4) Attenuation rate of electrified voltage: Measured using a product name "Static Honest Meter" (manufactured by Shishido Shokai Co., Ltd.). A sample film surface (corona discharge treated surface) that has been conditioned for 1 day under the conditions of a temperature of 40 ° C. and a relative humidity of 60% is discharged with an electric discharge voltage of 10 kV from an electrode set at a position 20 mm from the surface to charge the film surface. . After the charged voltage reached saturation, the discharge was stopped, and after 30 seconds, the decay rate (R%) was calculated from the remaining charged voltage (C) and the saturated charged voltage ( _CS ) by the following formula. R = 100 × (C _S −C) / C _S (5) Blooming index: From the haze value (H) of the sample film conditioned for 7 days under the conditions of temperature of 40 ° C. and relative humidity of 60%, the value immediately after film formation The value obtained by subtracting the haze value (H ₀ ) of the film was used as the blooming index. Haze value is measured according to ASTM D 103. (6) Blocking degree: After subjecting one side of the film to corona discharge treatment, a sample piece (length: 7 cm) was conditioned for 7 days at a temperature of 40 ° C. and a relative humidity of 50%.
X 2 cm) is cut out. The end portions of the two sample pieces were overlapped by 2 cm so that the corona discharge treated surfaces of both films contact each other, and a weight (bottom surface 2 cm square; weight 1 kg) was placed on the overlapped part.
Put on. In this state, after leaving it in a constant temperature bath at 40 ° C for 24 hours, the force required for shearing and peeling of the overlapped part (kgf / 4
cm ² ) was measured with a tensile tester. (Gripping interval 50 mm;
Tensile speed 50mm / min; 90 degree peeling method)

Examples 1 to 12 and Comparative Examples 1 to 12 Powdery highly crystalline propylene homopolymer (MFR = 3.4)
g / 10min; isotactic pentad fraction (P) 0.
984), 0.10% by weight of 2,6-di-t-butyl-p-cresol, tetrakis [methylene (3,5-di-
t-butyl-4-hydroxy-hydrocinnamate)]
Methane 0.03% by weight, calcium stearate 0.0
5 wt% and stearyldiethanolamine as the compound (A), and as the compound B, reaction products (B) obtained by esterifying 1 mol of stearyldiethanolamine and 1 mol of stearic acid are shown in Tables 1 to 6 below. The ingredients were blended in the proportions shown and then pelletized by a granulator to obtain each composition for the base material layer.

Further, crystalline polypropylene (having an isotactic pentad fraction shown in Tables 1 and 4 described later) is added to 2,6-di-t-butyl-p-cresol 0.1.
3% by weight, tetrakis [methylene (3,5-di-t-butyl-4-hydroxy-hydrocinnamate)] methane 0.03% by weight, calcium stearate 0.1% by weight
Further, a polyolefin wax and an anti-blocking agent (the types and blending amounts of which are shown in Tables 2 and 4) were blended and pelletized by a granulator to obtain a surface layer composition.

Next, the composition for the base material layer was extruded (caliber 65 m).
m) and the composition for the surface layer is extruded (caliber 40 mm)
After being melted at 240 ° C., it was co-extruded from a T die equipped with two manifolds and cooled by a cooling roll at 40 ° C. to obtain a multilayer sheet (thickness 1 mm). At this time,
The surface layer was adjusted to have a thickness of 0.1 mm and coextruded. Next, the multilayer sheet was first preheated at 158 ° C. for 100 seconds using a pantograph type biaxial stretching tester, and then 10
5.0 times in the longitudinal direction and 8. in the transverse direction at a drawing speed of m / min.
Sequentially stretched 5 times, total thickness 20 μm, surface layer thickness 2 μm
A biaxially stretched multilayer film of was obtained. Further, the surface of the surface layer of each of the multilayer films was subjected to corona discharge treatment. Various predetermined test pieces were prepared using each of the multilayer films, and haze, Young's modulus, heat shrinkage ratio were measured using the predetermined test pieces.
Charge voltage decay rate, blooming index (B.
I. ), And the blocking degree was measured. The results are shown in Tables 3 and 6.

Examples 13 and 14 Powdery highly crystalline propylene homopolymer (MFR = 3.4)
g / 10min; isotactic pentad fraction (P) 0.
984), 0.10% by weight of 2,6-di-t-butyl-p-cresol, tetrakis [methylene (3,5-di-
t-butyl-4-hydroxy-hydrocinnamate)]
Methane 0.03% by weight, calcium stearate 0.0
5% by weight and 0.12% by weight of stearyldiethanolamine as the compound (A), 1.0% by weight of a reaction product obtained by esterifying 1 mol of stearyldiethanolamine as the compound (B) and 1 mol of stearic acid. The ingredients were blended and then pelletized by a granulator to obtain each composition for the base material layer.

In addition, crystalline polypropylene (MFR 3.8
g / 10 min, isotactic pentad fraction (P) 0.
932), 0.10% by weight of 2,6-di-t-butyl-p-cresol, tetrakis [methylene (3,5-di-
t-butyl-4-hydroxy-hydrocinnamate)]
Methane 0.03% by weight, calcium stearate 0.1
% By weight and 0.5% by weight of Mitsui Petrochemical Polyethylene Wax (trade name: Mitsui High Wax 320P) and 0.2% by weight of Mizusawa Chemical Industry Co., Ltd. (trade name: Mizukasil P554) as a blocking inhibitor. The ingredients were blended and pelletized by a granulator to obtain a surface layer composition.

Next, the composition for the base material layer was extruded (with a diameter of 65 m).
m) and the composition for the surface layer is extruded (caliber 40 mm)
After being melted at 240 ° C., it was co-extruded from a T die equipped with two manifolds and cooled by a cooling roll at 40 ° C. to obtain a multilayer sheet (thickness 1 mm). At this time,
In Example 13, the thickness of the surface layer was adjusted to 0.05 mm, and in Example 14, the thickness of the surface layer was adjusted to 0.2 mm, and coextrusion was performed.

Next, the sheet was first preheated at 158 ° C. for 100 seconds using a pantograph type biaxial stretching tester, and then,
Two types of biaxially stretched multilayer film (total thickness 20 μm; In the case of 1 μm, in the case of Example 14, it is about 4 μm.)
Got Further, the surface of the surface layer of each of the multilayer films was subjected to corona discharge treatment. Predetermined various test pieces were prepared using each of the multilayer films, and haze, Young's modulus, heat shrinkage rate, electrification voltage decay rate, blooming index (BI), blocking degree were prepared using the predetermined test pieces. Was measured. The results are shown in Table 3.

Example 15 Powdery highly crystalline propylene homopolymer (MFR = 2.5)
g / 10min; isotactic pentad fraction (P) 0.
963), 0.10% by weight of 2,6-di-t-butyl-p-cresol, tetrakis [methylene (3,5-di-
t-butyl-4-hydroxy-hydrocinnamate)]
Methane 0.03% by weight, calcium stearate 0.0
Polyoxyethylene stearylamine 1 obtained by addition reaction of 5% by weight and 0.10% by weight of lauryldiethanolamine as the compound (A) and 1 mol of stearylamine as the compound (B) and 2.5 mol of ethylene oxide.
Mol equivalent, stearic acid 80% by weight, palmitic acid 2
0% by weight and 1.2% by weight of a mixed fatty acid equivalent to 1.2% by weight of a reaction product obtained by the esterification reaction are blended and pelletized by a granulator to form a base layer composition. Got

Further, crystalline polypropylene (MFR2.
8g / 10min, isotactic pentad fraction (P)
0.905), 0.10% by weight of 2,6-di-t-butyl-p-cresol, tetrakis [methylene (3,5-di-t-butyl-4-hydroxy-hydrocinnamate)] methane. 03% by weight, calcium stearate 0.1% by weight, and acid value type polyethylene wax manufactured by Mitsui Petrochemical Co., Ltd. (trade name: Mitsui High Wax 320MP,
Acid value 1.0) 1.0% by weight and Fuji Devison silica (trade name: Syloid 72 average particle size 2.5 μm) 0.15% by weight as a blocking agent are blended and pelletized by a granulator. To obtain a surface layer composition.

Next, the composition for the base layer was fed to one extruder (diameter 65 mm), the composition for the surface layer was fed to another extruder (diameter 40 mm), and melted at 240 ° C. Co-extrusion was carried out from a T-die equipped with two manifolds and cooled with a cooling roll at 40 ° C. to obtain a multilayer sheet (thickness 1 mm). At this time, the surface layer was adjusted so as to have a thickness of 0.1 mm and coextruded.

Next, the multi-layer sheet was first preheated at 158 ° C. for 100 seconds using a pantograph type biaxial stretching tester, and then 5.0 times in the longitudinal direction and 8.times. In the transverse direction at a stretching speed of 10 m / min. The film was sequentially stretched 5 times to obtain a biaxially stretched multilayer film (total thickness 20 μm, surface layer thickness 2 μm). Furthermore, the surface of the surface layer of the multilayer film was subjected to corona discharge treatment.
Various test pieces were prepared using the multilayer film, and the haze, Young's modulus, heat shrinkage rate, charge voltage decay rate, blooming index (BI), and blocking degree were measured using the test pieces. The results are shown in Table 3.

Example 16 Powdery highly crystalline propylene homopolymer (MFR = 5.4)
g / 10min; isotactic pentad fraction (P) 0.
972), 0.10% by weight of 2,6-di-t-butyl-p-cresol, tetrakis [methylene (3,5-di-
t-butyl-4-hydroxy-hydrocinnamate)]
Methane 0.03% by weight, calcium stearate 0.0
5% by weight and 0.10% by weight of tallow fatty acid diethanolamine as the compound (A), 1.2% by weight of a reaction product obtained by esterifying 1 mol of stearyldiethanolamine and 1 mol of palmitic acid as the compound (B). % And blended, and pelletized by a granulator to obtain a composition for base material layer.

Further, crystalline polypropylene (MFR4.
1g / 10min, isotactic pentad fraction (P)
0.921), 0.10% by weight of 2,6-di-t-butyl-p-cresol, tetrakis [methylene (3,5-di-t-butyl-4-hydroxy-hydrocinnamate)] methane. 03% by weight, calcium stearate 0.1% by weight, and acid value type polyethylene wax manufactured by Mitsui Petrochemical Co., Ltd. (trade name: Mitsui High Wax 320MP,
Acid value 1.0) 1.0% by weight and Fuji Devison silica (trade name: Syloid 72 average particle size 2.5 μm) 0.15% by weight as a blocking agent are blended and pelletized by a granulator. To obtain a surface layer composition.

Next, the composition for the base layer was fed to one extruder (diameter 65 mm) and the composition for the surface layer was fed to another extruder (diameter 40 mm) and melted at 240 ° C. It was coextruded from a T-die equipped with a manifold and cooled with a cooling roll at 40 ° C. to obtain a multilayer sheet (thickness 1 mm). At this time, the surface layer was adjusted so as to have a thickness of 0.1 mm and coextruded.

Next, the sheet was first preheated at 158 ° C. for 100 seconds using a pantograph type biaxial stretching tester, and then,
The film was sequentially stretched 5.0 times in the longitudinal direction and 8.5 times in the transverse direction at a drawing speed of 10 m / min to obtain a biaxially stretched multilayer film (total thickness 20 μm, surface layer thickness 2 μm). Further, the surface of the multilayer film on the surface layer side was subjected to corona discharge treatment. Various predetermined test pieces were prepared using the multilayer film, and using the predetermined test pieces, haze, Young's modulus, heat shrinkage rate, electrification voltage decay rate, blooming index (B.
I. ), And the blocking degree was measured. The results are shown in Table 3.

Comparative Example 14 Powdery highly crystalline propylene homopolymer (MFR = 3.4)
g / 10min: Isotactic pentad fraction (P) 0.
984), 0.10% by weight of 2,6-di-t-butyl-p-cresol, tetrakis [methylene (3,5-di-
t-butyl-4-hydroxy-hydrocinnamate)]
Methane 0.03% by weight, calcium stearate 0.0
5% by weight and 0.20% by weight of stearyldiethanolamine as the compound (A), 1.3% by weight of a reaction product obtained by esterifying 1 mol of stearyldiethanolamine as the compound (B) and 1 mol of stearic acid. % And silica as a blocking inhibitor manufactured by Mizusawa Chemical Co., Ltd. (trade name: Mizukasil P553A, average particle size 2.
0 μm) 0.10% by weight, and pelletized by a granulator. The composition was supplied to an extruder (diameter 65 mm), melted at 240 ° C., and then extruded from a T die to give 40
A single layer sheet (thickness 1 mm) was obtained by cooling with a cooling roll at ℃.

Next, the monolayer sheet was first preheated at 158 ° C. for 100 seconds using a pantograph type biaxial stretching tester, and then stretched 5.0 times in the longitudinal direction and 8.times. In the transverse direction at a stretching speed of 10 m / min. The film was sequentially stretched 5 times to obtain a biaxially stretched monolayer film (thickness: 20 μm). Furthermore, corona discharge treatment was applied to one surface of the monolayer film. Prepare various predetermined test pieces using the monolayer film, haze using the predetermined test piece,
Young's modulus, heat shrinkage rate, charge voltage decay rate, blooming index (BI), and blocking degree were measured.
The results are shown in Table 6.

Comparative Example 15 Powdery crystalline propylene homopolymer (MFR = 2.3 g
/ 10min: Isotactic pentad fraction (P) 0.9
32) to 2,6-di-t-butyl-p-cresol.
10% by weight, tetrakis [methylene (3,5-di-t-
Butyl-4-hydroxy-hydrocinnamate)] methane 0.03% by weight, calcium stearate 0.05% by weight, and stearyldiethanolamine 1 mol as the compound (B) were obtained by esterification reaction with stearic acid 1 mol. The reaction product was mixed with 1.0% by weight and 0.10% by weight of silica (trade name: Mizukasil P553A, average particle size 2.0 μm) manufactured by Mizusawa Chemical Co., Ltd. as an antiblocking agent, and pelletized by a granulator. did. The composition was supplied to an extruder (diameter 65 mm), melted at 240 ° C., then extruded from a T die and cooled by a cooling roll at 40 ° C. to obtain a single layer sheet (thickness 1 mm).

Next, the single layer sheet was first preheated at 158 ° C. for 100 seconds using a pantograph type biaxial stretching tester, and then 5.0 times in the longitudinal direction and 8.times. In the transverse direction at a stretching speed of 10 m / min. The film was sequentially stretched 5 times to obtain a biaxially stretched monolayer film (thickness: 20 μm). Furthermore, corona discharge treatment was applied to one surface of the monolayer film. Various predetermined test pieces were prepared using the corona discharge-treated single-layer film, and the test pieces were used to measure haze, Young's modulus, heat shrinkage rate, voltage decay rate, blooming index (BI), and blocking degree. Was measured. The results are shown in Table 6.

[0043]

【The invention's effect】

(1) The biaxially stretched multilayer film of the present invention can exhibit an excellent antistatic effect in a short time. That is,
A composition in which a compound (A) is used in combination with a conventional antistatic agent represented by the compound (B) for a highly crystalline polypropylene having a molecular orientation and a crystallinity higher than a specific lower limit value as a base material layer Further, as a surface layer on at least one surface of the base material layer, a specific amount of a polyolefin wax and an antiblocking agent were blended with crystalline polypropylene having a slightly low specific range of isotactic pentad fraction (P). As a result of forming a biaxially stretched multilayer film in which layers of the composition are laminated, the property of exhibiting an antistatic effect in a short time is exhibited.

(2) The biaxially stretched multilayer polypropylene film of the present invention is excellent in high-speed mechanical processing suitability in a printing process, a coating process or a packaging process by utilizing its high rigidity. Further, due to the characteristic that only extremely small heat shrinkage occurs, color shift is unlikely to occur in the multicolor printing process, and the dimensional stability in the drying process in coating and printing is excellent. Furthermore, in order to exert a good antistatic effect,
It is possible to almost completely eliminate various problems related to static electricity in the secondary processing step, such as defective transfer of printing ink and adhesion of dust. Further, it has an advantage in that the transparency is greatly improved as compared with the conventional single-layer film, and it is possible to bring out the high-grade feeling of the contents as a packaging base material.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

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Claims (1)

[Claims] 1. A highly crystalline polypropylene in which the relationship between the melt flow rate (hereinafter referred to as MFR) and the isotactic pentad fraction (P) satisfies the equation: 1.00 ≧ P ≧ 0.015 log MFR + 0.955. , The following general formula: 0.05 to 0.20% by weight of the alkyldiethanolamine or alkenyldiethanolamine represented by the formula (hereinafter referred to as compound A) and the general formula R ₁ NH ₂ (wherein R ₁ has 12 to 12 carbon atoms). 22 alkyl groups or alkenyl groups.) Ethylene oxide 2 to 3 with respect to 1 mol of the alkylamine or alkenylamine represented by
A compound obtained by reacting polyoxyethylene alkylamine or polyoxyethylene alkenylamine obtained by adding moles with at least one higher fatty acid selected from higher fatty acids having 12 to 22 carbon atoms (hereinafter, Compound B) is added to the composition in an amount of 0.5 to 0.5.
A composition containing 1.5% by weight was used as a base material layer, and crystalline polypropylene having an isotactic pentad fraction (P) in the range of 0.900 to 0.945 was formed on at least one surface of the base material layer. A polyolefin wax having a softening point of 140 ° C. or lower in an amount of 0.1 to 3.0% by weight of the composition and an antiblocking agent having an average particle size of 5 μm or less in an amount of 0.05 to 0.5% by weight of the composition. % Of the composition is laminated as a surface layer, a biaxially stretched multilayer film.