JPH05163392A - Polypropylene film - Google Patents

Abstract

PURPOSE:To prepare a polypropylene film which is excellent in clarity and impact strength and gives an easily openable bag by compounding a crystalline propylene polymer, an ethylene-propylene copolymer, a fine powder of calcium sodium aluminosilicate, and an ethylenebis(fatty acid amide). CONSTITUTION:100 pts.wt. compsn. comprising 100 pts.wt. crystalline propylene polymer having a melt flow rate of 3-20g/10min and 3-50 pts.wt. ethylene- propylene copolymer having an ethylene content of 50-90% and a Mooney viscosity ML1+4 (100 deg.C) of 5-50 is compounded with 0.01-1.0 pt.wt. fine powder of calcium sodium aluminosilicate comprising 53-56wt.% SiO2, 25-28wt.% Al2O3, 8-11wt.% Cab, and 4-8wt.% Na2O and having an ignition loss of 4wt.% or lower, a mean particle diameter of 1.0-9.0mum. and a sphericity of 0.85 or higher, and 0.01-0.50 pt.wt. ethylenebis(fatty acid amide) of the formula (wherein R is 17C or lower alkyl).

Description

Detailed Description of the Invention

[0001]

This invention relates to polypropylene films. More specifically, the present invention relates to a polypropylene film having excellent transparency, impact strength, and bag opening property, which is suitable for packaging heavy goods.

[0002]

2. Description of the Related Art Conventionally, various polypropylene resin films have been produced and widely used for various packaging. However, when polypropylene products are used to package heavy items such as potatoes, there is a problem of bag breakage due to insufficient impact strength. There was a defect such as occurrence of. In order to improve this drawback, there are a method of blending a polypropylene resin with a low-density polyethylene resin or a linear low-density polyethylene resin to improve impact strength, and a method of blending an ethylene-propylene block copolymer resin. However, both methods have the drawback of significantly impairing transparency. Further, a method of blending a polypropylene resin with an ethylene-propylene copolymer to improve impact strength is also generally used. This method can improve transparency and impact strength, but has a drawback that when the film is processed into a bag and stored, the opening of the bag is blocked and the bag cannot function as a bag.

[0003]

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive studies to solve the problems of the polypropylene film containing the above-mentioned ethylene-propylene copolymer. As a result, a specific calcium-sodium-alumino-silicate fine powder and a specific ethylene were added to a composition prepared by mixing a crystalline propylene polymer, a specific ethylene composition and an ethylene-propylene copolymer having a Mooney intrinsic viscosity in a predetermined amount. A film obtained from a composition obtained by blending a predetermined amount of bis fatty acid amide, without impairing transparency,
It was found that a polypropylene film having excellent bag opening property and impact strength was provided, and the present invention was completed based on this finding. As is clear from the above description, an object of the present invention is to provide a polypropylene film which is excellent in transparency and impact strength, and is excellent in bag opening property.

[0004]

The present invention has the following constitution. (1) 100 parts by weight of crystalline propylene polymer and ethylene-
A composition prepared by mixing 0.01 to 1.0 part by weight of calcium, sodium, alumino, silicate fine powder and 0.01 to 0.50 part by weight of ethylenebis fatty acid amide with 100 parts by weight of a composition comprising 3 to 50 parts by weight of a propylene copolymer. A polypropylene film characterized by being used. (2) Ethylene content as ethylene-propylene copolymer is 50 to 90% by weight, Mooney intrinsic viscosity is 5 to 50 ML
_{1 + 4} (100 ° C) is preferred. (3) Calcium-sodium-alumino-silicate fine powder with an average particle size of 1.0 to 9.0 µ and sphericity (Fx)
Is preferably 0.85 or more. (4) As the ethylenebis fatty acid amide, a fatty acid amide having a fatty acid having 18 or more carbon atoms is preferable.

The crystalline propylene polymers used in the present invention include crystalline propylene homopolymers and crystalline ethylene-propylene random copolymers, propylene and butene-1, pentene-1, hexene-1, heptene-1. ,
Contains 70% by weight or more of a propylene component such as a crystalline random copolymer with one or more α-olefins such as octene-1 and decene-1, and contains propylene, ethylene and /
Alternatively, it is a crystalline random copolymer with an α-olefin having 4 or more carbon atoms, or a mixture of two or more thereof. The melt flow rate of the crystalline propylene polymer (based on JIS K 7210, the discharge amount of the molten resin for 10 minutes when a temperature of 230 ° C. and a load of 2.16 kg is added) is not particularly limited, but preferably 3 to 20 g / It's 10 minutes.

The crystalline ethylene-propylene random copolymer preferably has an ethylene content of 0.1 to 10% by weight, particularly preferably 1 to 8% by weight. In the crystalline propylene-butene-1 random copolymer, the content of butene-1 is preferably 0.3 to 30% by weight, particularly preferably 1.5 to 20% by weight. Further, in the crystalline propylene-α-olefin (excluding butene-1) random copolymer, the content of α-olefin is 0.
It is preferably 3 to 20% by weight.

The crystalline propylene polymer is, for example, homopolymerization of propylene in the presence of a Ziegler-Natta type catalyst, copolymerization of propylene and ethylene, propylene and butene-1, pentene-1, hexene-1, heptene. −
It can be obtained by copolymerization with one or more α-olefins such as 1, 1, octene-1, and decene-1, and random copolymerization with propylene and ethylene and one or more of the above-mentioned α-olefins.

The ethylene-propylene copolymer used in the present invention has an ethylene content of 50 to 90% by weight and has a JI
The Mooney intrinsic viscosity measured based on SK 6300 is 5 to
It is 50 ML _{1 + 4} (100 ° C). The ethylene-propylene copolymer is, for example, (a) a complex containing at least magnesium, titanium and halogen, and (b) a first group of the periodic table.
It is obtained by random copolymerization of ethylene and propylene using a catalyst formed from an organometallic compound of a Group 3 to Group 3 metal and (c) an electron donor.

The ethylene content of the ethylene-propylene copolymer used in the present invention is 50 to 90% by weight. When the ethylene content is less than 50% by weight, the effect of improving the impact strength is not sufficiently exhibited in the film using the obtained composition, and when it exceeds 90% by weight, the obtained composition is used. Wrinkles are generated in the long wound film, which is not preferable.

The Mooney intrinsic viscosity of the ethylene-propylene copolymer used in the present invention is 5 to 50 ML _{1 + 4} (100
℃). The Mooney intrinsic viscosity is 5ML _{1 + 4} (100 ℃)
If it is less than 50%, the effect of improving the impact strength is not sufficiently exerted in the film using the obtained composition,
_When it exceeds _{1 + 4} (100 ° C.), the transparency of the film using the composition obtained is lowered, which is not preferable.

The mixing ratio of the ethylene-propylene copolymer used in the present invention is 3 to 50 parts by weight based on 100 parts by weight of the crystalline propylene polymer. When the compounding ratio is less than 3 parts by weight, the effect of improving the impact strength is not sufficiently exerted in the film using the obtained composition, and when it exceeds 50 parts by weight, long winding using the obtained composition. Wrinkles are generated in the film, which is not preferable.

The calcium-sodium-alumino-silicate fine powder used in the present invention is obtained by ion-exchange of natural or synthetic zeolite with a divalent metal and then heat-treating it to make it amorphous. Unlike zeolite, the amorphized fine powder is completely amorphous and does not show a crystal structure by X-ray diffractometry, but the primary particles constituting the particles show a cubic to spherical shape with almost uniform size. It contains silicon dioxide (SiO ₂ ) and aluminum oxide (Al ₂ O ₃ ) as main components, and contains sodium oxide (Na ₂ O) and calcium oxide (CaO).

In the present invention, calcium, sodium,
The alumino-silicate fine powder preferably has a chemical composition within the following composition range. SiO _2: 53 ~ 56 wt% Al ₂ O _3: 25 ~28 wt% CaO: 8 to 11 wt% Na ₂ O: 4 to 8% by weight ignition loss: 4 wt% or less It should be noted that the chemical composition of the present invention Of the analyzes, the loss on ignition (Ig-LOSS), silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), and sodium oxide (Na ₂ O) are described in JI.
Measured according to SM 8852. Atomic absorption method was used for CaO.

The calcium, sodium, alumino, silicate fine powder has a sphericity (Fx) in the range of 0.85 or more. Here, the sphericity (Fx) indicates a coefficient represented by the following formula, and in the case of a sphere, the coefficient Fx is 1.0. (Fx) ² = R ₁ × R ₂ / (R ₁ ) ² (where Fx is a coefficient of sphericity of fine powder, and R ₁ ,
R ₂ shows the circumscribed radius (R ₁ ) and the inner diameter radius (R ₂ ) of the particle photograph contour of a single particle when the fine powder is magnified and photographed with an electron microscope. ) When the coefficient of sphericity Fx is less than 0.85, the impact strength of the film decreases, which is not preferable.

The blending ratio of the calcium / sodium / alumino / silicate fine powder used in the present invention is such that the crystalline propylene polymer and the ethylene-propylene copolymer 3 to 3 are mixed.
0.01 to 1.0 per 100 parts by weight of a composition consisting of 50 parts by weight
Parts by weight. If the blending ratio is less than 0.01 parts by weight, the effect of blocking the opening of the bag is not sufficiently exhibited in the film using the obtained composition, and if it exceeds 1.0 parts by weight, the obtained composition is used. Poor dispersion of the calcium, sodium, alumino, silicate fine powder in the film causes a decrease in transparency, which is not preferable.

The average particle size (measured by the Coulter counter method) of the calcium, sodium, alumino, silicate fine powder used in the present invention is preferably 1.0 to 9.0 μ,
If it is less than 1.0 μm, the opening of the bag is blocked in the film using the obtained composition, which is not preferable. If the average particle size exceeds 9.0 μ, the impact strength of the film using the composition obtained is lowered, which is not preferable.

The ethylene bis fatty acid amides used in the present invention are generally

[0018]

[Chemical 1]

(R represents an alkyl group having 17 or more carbon atoms)
It is represented by. Such ethylenebis fatty acid amides include, for example, ethylenebisstearic acid amide, ethylenebisoleic acid amide, ethylenebisbehenic acid amide,
Examples thereof include ethylenebiserucic acid amide.
The blending ratio of the ethylene bis fatty acid amide used in the present invention is 100 parts by weight of a composition comprising a crystalline propylene polymer and 3 to 50 parts by weight of an ethylene-propylene copolymer.
0.01 to 0.50 parts by weight. If the blending ratio is less than 0.01 parts by weight, the opening of the bag will be blocked in the film using the obtained composition, which is not preferable. Also, 0.50
If it exceeds the weight part, the impact strength decreases, which is not preferable.

In the composition used for the polypropylene film of the present invention, various additives usually added to the propylene polymer, such as antioxidants (phosphorus antioxidants, sulfur antioxidants and phenolic antioxidants) Etc.), neutralizing agents (such as metal salts of higher fatty acids and hydrotalcite), slip agents (such as monofatty acid amide and silicone oil), etc. can be used within a range that does not impair the object of the present invention.

The composition used for the polypropylene film of the present invention comprises a composition comprising a crystalline propylene polymer and an ethylene-propylene copolymer, a predetermined calcium / sodium / alumino / silicate fine powder and a predetermined ethylenebisfatty acid amide, Furthermore, it is obtained by stirring and mixing the above-mentioned various additives with a usual stirring mixer, for example, a Henschel mixer (trade name), etc., and the mixture is a usual single-screw extruder or twin-screw extruder. It is also possible to obtain pellets by melt-kneading with and pelletizing. The polypropylene film of the present invention can be obtained by forming such a composition into a film by an ordinary inflation method, T-die method or the like. In particular, a method of melt-kneading with a T-die method at a melt-kneading temperature of 180 to 260 ° C., extruding, and rapidly cooling to 60 ° C. or less to form a film, and subjecting the surface to a surface treatment such as corona treatment, It is desirable because a film excellent in impact resistance and bag opening property can be obtained without impairing transparency.

[0022]

EFFECT OF THE INVENTION The polypropylene film of the present invention has excellent transparency, excellent impact strength suitable for packaging heavy goods, and opening property of the opening after the film is processed into a bag and stored. It is an excellent film. Furthermore, since the blocking property between films is improved, when a polypropylene film is produced and wound in a long roll, the film at the core does not block and the yield is not reduced. It can be used in a wide range of films.

[0023]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the scope of the present invention is not limited thereby. The performance evaluation of the films carried out in Examples and Comparative Examples was carried out by the following method. 1) Transparency: ASTM D 1
Transparency was shown by the haze value (unit:%) measured by the method according to 003. The smaller this value is, the better the transparency is. 2) Openability of bag: A film kept at 40 ° C and 50% RH for 48 hours is used as a sample, the corona-treated surfaces of the films are overlapped with each other, and a load of 2 kg per 4 cm ^{2 of the} laminated film is applied to 50 ° C. After being kept for 24 hours, the blocking value (unit: kg / 4 cm ² ) obtained by measuring the peel strength of the laminated films at 23 ° C. and 50% RH was shown as the opening property of the bag. The smaller this value is, the better the opening property of the bag is. 3) Impact strength: A film kept at 40 ° C and 50% RH for 48 hours is used as a sample, the film is punched out, mounted in a holder for exclusive use in an impact machine, and a low temperature tank at -15 ° C using a water-ethanol mixture as a refrigerant. Soak in. After soaking for 15 minutes, it was punched out with an impact head (caliber 0.5 inch), and its strength was measured and shown as impact strength (unit: kg-cm). The larger this value is, the better the impact strength is. 4) Crystal melting point (Tm): scanning type perturbation calorimeter (abbreviation: DS)
Using C), set a 10 mg sample and raise the temperature to 20 ° C /
The temperature is raised from room temperature at min, and the peak temperature of the endothermic curve accompanying the melting point of the crystal is Tm (unit: ° C).

Examples 1-5, Comparative Examples 1-9 As crystalline propylene polymer, melt flow rate 6.
100 parts by weight of a powdery crystalline ethylene-propylene random copolymer having an ethylene content of 4.0 g by weight, a crystalline melting point (Tm) measured by a DSC method of 140 ° C. of 0 g / 10 minutes, and an ethylene-propylene copolymer (Mitsui 100 parts by weight of a composition consisting of 20 parts by weight of Tuffmer P0280 manufactured by Petrochemical Co., Ltd., 0.10 parts by weight of an antioxidant (tris (2,4-di-t-butylphenyl) phosphite), and an antioxidant ( Tetrakis [methylene-3- (3 ', 5'-di-t-butyl-4'
-Hydroxyphenyl) propionate] methane) 0.05
Parts by weight, neutralizing agent (calcium stearate) 0.05 parts by weight, slip agent (erucic acid amide) 0.12 parts by weight, and ethylene bisstearic acid amide in which fatty acid has 18 carbon atoms
0.10 parts by weight and calcium / sodium / alumino /
Silicate fine powder (Silton JC series manufactured by Mizusawa Chemical Co., Ltd.) was added at the sphericity, the average particle size and the blending amount described in Table 1 below, and the mixture was placed in a Henschel mixer (trade name),
After stirring and mixing for 2 minutes, the mixture was melt-kneaded and extruded at a melt-kneading temperature of 200 ° C. using a single-screw extruder having a diameter of 40 mm to form pellets.

The pellets thus obtained were mixed with a molding machine equipped with a T-die 15
Using a chill roll with a 0-mesh satin finish, the T-die has a melting temperature of 230 ° C and a chill roll temperature of 30 ° C.
A film of μ was molded. Corona discharge treatment was applied to one surface of the film to obtain a single-side processed film. Using the obtained single-sided processed film, the film performance was evaluated by the above evaluation method. The results are shown in Tables 2 and 4.

As can be seen from Table 2, all of Examples 1 to 5 are compositions of the crystalline propylene polymer according to the present invention and an ethylene-propylene copolymer, and the predetermined calcium-sodium-alumino-silicate fine powder is added to the composition. It is understood that these films are obtained by using a composition prepared by blending, but these are excellent in transparency, impact strength and antiblocking property.

Similarly, from Table 2, Comparative Example 1 is a case where a composition containing less than 0.01 parts by weight of calcium, sodium, alumino, silicate fine powder was used, and the obtained film had an anti-blocking property. It turns out that is inferior. Comparative Example 2 is a case where the calcium, sodium, alumino, silicate fine powder was blended in an amount of more than 1.0 part by weight, and it is found that the obtained film has remarkably lowered transparency and impact strength. In Comparative Example 3, the calcium, sodium, alumino, and silicate fine powders have an average particle size of less than 1.0 μ, and it can be seen that the obtained film is inferior in antiblocking property. Comparative Example 4
Is the case where the average particle size of the calcium-sodium-alumino-silicate fine powder exceeds 9.0 μ, and it is understood that the transparency and impact strength of the obtained film are remarkably lowered.

Comparative Example 5 is a case in which calcium-sodium-alumino-silicate fine powder having a sphericity (Fx) of less than 0.85 was blended, and it can be seen that the obtained film is inferior in antiblocking property. Comparative Examples 6 and 7 are cases in which an anti-blocking agent other than the calcium-sodium-alumino-silicate fine powder was added, and it can be seen that all the obtained films have poor anti-blocking properties. Comparative Example 8 is a case where ethylene bis fatty acid amide is not added, but it is understood that the obtained film is inferior in antiblocking property.

Comparative Examples 9-10 As can be seen from Table 4, among the compositions used for the film shown in Example 1, ethylene-propylene copolymers having an ethylene content of less than 50% by weight were used. When used (Comparative Example 9), the impact strength of the obtained film decreases.
Further, in the composition used for the film shown in Example 1,
The Mooney intrinsic viscosity of ethylene-propylene copolymer is 50
When using a material that exceeds ML _{1 + 4} (100 ° C) (Comparative Example 10)
Reduces the transparency of the obtained film.

Examples 6 to 8 and Comparative Examples 11 to 14 As a crystalline propylene polymer, a melt flow rate of 6.
100 parts by weight of a powdery crystalline ethylene-propylene random copolymer having an ethylene content of 4.0 g by weight, a crystalline melting point (Tm) measured by a DSC method of 140 ° C. of 0 g / 10 minutes, and an ethylene-propylene copolymer (Mitsui 100 parts by weight of a composition consisting of 20 parts by weight of Tuffmer P0280 manufactured by Petrochemical Co., Ltd., 0.10 parts by weight of an antioxidant (tris (2,4-di-t-butylphenyl) phosphite), and an antioxidant ( Tetrakis [methylene-3- (3 ', 5'-di-t-butyl-4'
-Hydroxyphenyl) propionate] methane) 0.05
Parts by weight, neutralizing agent (calcium stearate) 0.05 parts by weight, slip agent (erucic acid amide) 0.12 parts by weight, predetermined calcium-sodium-alumino-silicate fine powder (manufactured by Mizusawa Chemical Co., Ltd., Shilton JC-50: Average particle size 5.0
μ) 0.20 parts by weight and ethylene bis fatty acid amide having 18 or more carbon atoms in fatty acid (manufactured by Nippon Kasei Co., Ltd., Thripax series) were added in a blending amount shown in Table 5 below to obtain a Henschel mixer (trade name). ), The mixture was stirred and mixed for 2 minutes, and then the compound was melt-kneaded and extruded at a melt-kneading temperature of 200 ° C. using a single-screw extruder having a diameter of 40 mm to form pellets.

The pellets thus obtained were combined with a molding machine equipped with a T-die 1
Using a chill roll with a 50-mesh satin finish, the T-die melts at a temperature of 230 ° C and the chill roll at a temperature of 30 ° C.
A 30μ film was molded. Corona discharge treatment was applied to one surface of the film to obtain a single-side processed film. Using the obtained single-sided processed film, the film performance was evaluated by the above evaluation method. The results are shown in Table 6.

As can be seen from Table 6, Examples 6 to 8 are
In each case, a composition comprising a crystalline propylene polymer and an ethylene-propylene copolymer according to the present invention, a predetermined calcium-sodium-alumino-silicate fine powder and a fatty acid having 18 or more carbon atoms of ethylenebisfatty acid amide are blended. It is found that these films are excellent in transparency, impact strength and anti-blocking property.

Comparative Example 11 is a case where less than 0.01 part by weight of ethylene bis fatty acid amide having a fatty acid having 18 or more carbon atoms is blended, and it is understood that the obtained film is inferior in antiblocking property. Comparative Example 12 has a carbon number of fatty acid
This is the case where 18 or more ethylene bis fatty acid amides were blended in an amount of more than 0.50 parts by weight, and it is found that the resulting film has a significantly reduced impact strength. Comparative Example 13 is a case where an ethylene bis fatty acid amide having a fatty acid having a carbon number of less than 18 was blended, and it can be seen that the obtained film is inferior in antiblocking property. Comparative Example 14 is a case where silica was mixed with the anti-blocking agent, and it is found that the anti-blocking property is inferior.

[0034]

[Table 1]

(Note): The following substances were used as the anti-blocking agents in the table. CSAS: calcium, sodium, alumino, silicate Mizusawa Chemical Co., Ltd., Shilton JC series Zeolite: Eishin Kasei Co., Ltd. AM-200 Silica: Fuji Devison Co., Ltd., Cyloid 244

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

[Table 4]

[0039]

[Table 5]

(Note) CSAS: calcium / sodium / alumino / silicate Mizusawa Chemical Co., Ltd., Shilton JC series Silica: Fuji Devison Co., Ltd., Cyloid 244

[0041]

[Table 6]

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area C08L 23:16)

Claims (4)

[Claims] 1. A composition comprising 100 parts by weight of a crystalline propylene polymer and 3 to 50 parts by weight of an ethylene-propylene copolymer is added to 100 parts by weight of calcium-sodium-alumino.
A polypropylene film comprising a composition comprising 0.01 to 1.0 part by weight of silicate fine powder and 0.01 to 0.50 part by weight of ethylene bis fatty acid amide. 2. The polypropylene film according to claim 1, which has an ethylene content of 50 to 90% by weight and an Mooney intrinsic viscosity of 5 to 50 ML _{1 + 4} (100 ° C.) as an ethylene-propylene copolymer. 3. The polypropylene film according to claim 1, which is a calcium-sodium-alumino-silicate fine powder having an average particle size of 1.0 to 9.0 μ and a sphericity (Fx) of 0.85 or more. 4. The polypropylene film according to claim 1, wherein the ethylene bis fatty acid amide is a fatty acid amide having a fatty acid having 18 or more carbon atoms.