JPH10193533A - Polyolefin multilayer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve impact resistance by laminating a layer constituted of polyethylene resin and a layer constituted mainly of an ethylene-α-olefin copolymer having specific characteristics. SOLUTION: A polyolefin multilayer film is formed by laminating a layer A constituted of polyethylene resin and a layer B constituted mainly of an ethylene-α-olefin copolymer. Herein the density of the layer B is made 0.880-0.915(g/cm<3> ) and the melt flow rate thereof at a temperature of 190 deg.C and under a load of 2.16kg is made 0.0-200 (g/10min.), while the ratio between the melt flow rate at 190' C and under the load of 2.16kg and that at 190 deg.C and under a load of 21.6kg is made 10-20 and the molecular-weight distribution is made 2.0-4.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin multilayer film having optimum impact resistance.

[0002]

2. Description of the Related Art As a polyolefin-based multilayer film, a polyolefin-based multilayer film comprising an ethylene-α-olefin copolymer is described in JP-A-4-310735 and JP-A-8-25594.

For example, JP-A-8-25594 discloses that the inner layer contains an antiblocking agent and has a density of 0.94.
High-density polyethylene composition of 5 g / cm 3 or more, intermediate layer having a nucleating agent, linear low-density polyethylene composition having a density of 0.935 g / cm 3 or more, and three-layer outer layer of polyethylene resin A sealant film is disclosed.

JP-A-4-310735 discloses a laminate comprising an ethylene-α-olefin copolymer layer having a specific range of melt index and another ethylene-α-olefin copolymer layer having a specific range of melt index. A polyethylene-based multilayer film obtained by stretching a film is disclosed.

[0005]

Conventionally known polyolefin-based multilayer films include surface substrates, for example, biaxially oriented nylon (ONY), polyethylene terephthalate (PET), polyvinylidene chloride-coated biaxially oriented polypropylene ( KOP), biaxially oriented polypropylene (OP
P), polyvinylidene chloride coated biaxially stretched nylon (K
ONY), polyethylene (PE), other plastic films, etc., laminated with paper, aluminum foil, etc., but the impact resistance of the surface material is often low, so when the product falls or when the contents are filled at high speed. For example, the laminated film may be broken at or near the seal portion of the product, and improvement has been required.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a polyolefin resin comprising a layer A composed of a polyethylene resin and a layer B composed mainly of an ethylene-α-olefin copolymer, having the following characteristics. It is intended to provide a multilayer film.

Layer B: ethylene-α-olefin copolymer; (B-1) density (d) = 0.880 to 0.915 (g /
cm3) (B-2) Melt flow rate at 190 DEG C., 2.16 kg load (MFR2.16) = 0.01 to 200 (g / 10 min) (B-3) Melt flow rate at 190 DEG C., 2.16 kg load Ratio of (MFR2.16) to melt flow rate (MFR21.6) at 190 ° C. under a load of 21.6 kg (MFR2.16) / (MFR21.6) = 10 to 20 (B-4) Molecular weight distribution (Mw /Mn)=2.0-4.0

[0008] More preferably, the number of falling balls is 3.5 or more, preferably 4.0 or more, and more preferably 4.5.
This is a polyolefin-based multi-layered film.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The ethylene-α-olefin copolymer which is the main component of the layer B of the present invention has the following specific range.

Layer B: ethylene-α-olefin copolymer; (B-1) density (d) = 0.880 to 0.915 (g /
cm3), preferably 0.890 to 0.915 (g / c).
m3) (B-2) Melt flow rate (MFR2.16) at 190 DEG C. and 2.16 kg load = 0.01 to 200 (g / 10 min), preferably 0.1 to 30 (g / 10 min) (B- 3) Ratio of melt flow rate (MFR2.16) at 190 ° C and 2.16 kg load to melt flow rate (MFR21.6) at 190 ° C and 21.6 kg load (MFR2.16)
/(MFR21.6)=10-20 (B-4) Molecular weight distribution (Mw / Mn) = 2.0-4.
0, preferably 2.0 to 3.7

Among the above properties, (1) if the density is smaller than the above range, the minimum required rigidity cannot be obtained at the time of molding, and if the density is larger than the above range, the impact resistance becomes poor.

(2) If MFR2.16 is smaller than the above range, the fluidity is poor and molding is difficult, and if it is larger than the above range, mechanical strength is poor.

(3) If (MFR21.6) / (MFR2.16) is larger than the above range, the stretchability decreases and the moldability deteriorates.

(4) If the molecular weight distribution (Mw / Mn) is larger than the above range, the stretchability decreases and the moldability deteriorates.

Ethylene-α which is the main component of the layer B of the present invention
Examples of the olefin copolymer include a copolymer of ethylene and an α-olefin. For example, ethylene and α
-Polymerization using a catalyst such as a Philips ethylene-α-olefin copolymer obtained by polymerizing an olefin with a catalyst such as chromium oxide supported on alumina or silica-alumina, and molybdenum oxide supported on alumina. And an ethylene-α-olefin copolymer obtained by polymerization using a Ziegler-based catalyst comprising a transition metal compound and an organometallic compound. Further, a copolymer of ethylene and an α-olefin obtained by polymerization in the presence of a so-called single-site catalyst such as a metallocene catalyst system may be mentioned.

Examples of the α-olefin of the copolymer of ethylene and α-olefin include propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, and octene-1.
And α-olefins having 3 to 10 carbon atoms such as

The repeating unit derived from the α-olefin in the copolymer of ethylene and α-olefin is usually contained in an amount of not more than 30% by weight, preferably not more than 25% by weight, more preferably not more than 20% by weight. I have. The α-olefin may be used alone or in combination of two or more in the ethylene-α-olefin copolymer.

As the single-site catalyst, a combination of a metallocene compound of a transition metal of Group IV or V of the periodic table with an organoaluminum compound and / or an ionic compound is used.

The transition metals of Groups IV or V of the Periodic Table include:
Titanium (Ti), zirconium (Zr), hafnium (H
f) and vanadium (V) are preferred.

The metallocene compound is a compound which is cross-linked by at least one cyclopentadienyl group, substituted cyclopentadienyl group, hydrocarbyl silicon, or the like, and which is obtained by cross-linking a cyclopentadienyl group to oxygen, nitrogen and phosphorus atoms. Any known metallocene compound having a compound as a ligand can be used.

Specific examples of these metallocene compounds include dimethylsilyl (2,4-dimethylcyclopentadienyl) (3 ', 5'-dimethylcyclopentadienyl) zirconium dichloride, dimethylsilyl (2,4-dimethyl Cyclopentadienyl) (3 ', 5'-dimethylcyclopentadienyl) silicon-bridged metallocene compounds such as hafnium dichloride, ethylenebisindenyl zirconium dichloride, ethylenebisindenyl hafnium dichloride, ethylenebis (methylindenyl) zirconium Examples include indenyl crosslinked metallocene compounds such as dichloride and ethylenebis (methylindenyl) hafnium dichloride.

The organoaluminum compound used in combination with the metallocene compound in the present invention includes a compound represented by the following general formula:
A linear or cyclic polymer represented by Al (R) O-) n (R is a hydrocarbon group having 1 to 10 carbon atoms, including those partially substituted by halogen atoms and / or RO groups; .N
Is the degree of polymerization and is 5 or more, preferably 10 or more)
And specific examples include methylalumoxane, ethylalumoxane, isobutylethylalumoxane, wherein R is a methyl, ethyl, or isobutyl group, respectively.

Further, examples of other organoaluminum compounds include trialkylaluminum, dialkylhalogenoaluminum, sesquialkylhalogenoaluminum, alkenylaluminum, dialkylhydroaluminum, and sesquialkylhydroaluminum.

The ionic compound is represented by the general formula: A + C
A + is an oxidizing cation of an organic compound, an organometallic compound, or an inorganic compound, or a Bronsted acid composed of a Lewis base and a proton, and reacts with an anion of a metallocene ligand to form a metallocene cation. Can be generated. C- is an anionic component of the ionic compound. Specific examples thereof are described in JP-A-Hei4-2
No. 53711, JP-A-4-305585, JP-A-5-507756, JP-A-5-50290.
No. 6 can be used.

Particularly, an ionic compound of a tetrakis (pentafluorophenyl) borate anion and a triphenylcarbonium cation or a dialkylanilinium cation is preferred. These ionic compounds can be used in combination with the aforementioned organic aluminum compounds.

Ethylene and α by single-site catalyst
-Various well-known methods can be adopted as a method of copolymerizing with olefin, and fluidized bed gas phase polymerization or stirring gas phase polymerization in an inert gas, slurry polymerization in an inert solvent, Examples include bulk polymerization using a solvent.

In the layer B of the present invention, another polyethylene may be mixed with the ethylene-α-olefin copolymer in an amount of 50% by weight or less, preferably 40% by weight or less, more preferably 30% by weight or less.

As other polyethylene, copolymers with other monomers such as high-density, medium-density, high-pressure low-density polyethylene and ethylene-vinyl acetate copolymer can be used. The other polyethylene to be mixed may be used alone or in combination of two or more.

The polyethylene resin of the layer A according to the present invention includes ethylene-α-olefin resin, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and other monomers. Coalescence and the like. When an ethylene-vinyl acetate copolymer is used, the amount of the repeating unit derived from vinyl acetate in the copolymer is usually preferably 20% by weight or less.

As the polyethylene resin for the layer A of the present invention, an ethylene-α-olefin resin having the following physical properties can be preferably used for the purpose of improving rigidity.

Layer A: ethylene-α-olefin resin; (A-1) density (d) = 0.915 to 0.960
(G / cm ³ ), preferably above 0.920.
960 (g / cm ³ ) (A-2) Melt flow rate (MFR2.16) at 190 ° C. and 2.16 kg load = 0.01 to 200 (g / 10 m)
in), preferably 0.1 to 30 (g / 10 min). (A-3) The melt flow rate (MFR2.16) at 190 ° C. and a load of 2.16 kg, and the melt flow rate at 190 ° C. and a load of 21.6 kg ( (MFR21.6)
/(MFR2.16)=10-20 (A-4) Molecular weight distribution (Mw / Mn) = 2.0-
4.0, preferably 2.0 to 3.7

The compositions used in the layers A and B of the present invention are as follows:
A mixture obtained by mixing and kneading the components using various kneaders such as a Banbury mixer, a roll mixer, a kneader, a high-speed rotary mixer, and an extruder, preferably a single-screw or twin-screw extruder can be used. Further, a material kneaded during inflation molding or T-die molding can be used.

The polyolefin-based multilayer film of the present invention includes a layer composed of an A layer and a B layer.
There is no particular limitation as long as the layer and the layer B are in this order.

As a typical layer constitution of the polyolefin-based multilayer film of the present invention, the following constitutions can be exemplified. A layer / B layer, A layer / B layer / surface substrate, A layer / B
Layer / adhesive layer / surface substrate, innermost layer / A layer / B layer, innermost layer /
A layer / B layer / surface substrate, innermost layer / A layer / B layer / adhesive layer /
Surface base material, innermost layer / A layer / B layer / adhesive layer, A layer / B layer /
Adhesive layer

In the polyolefin-based multilayer film of the present invention, an innermost layer may be provided further inside the layer A if necessary.

As the innermost layer, maleic acid, itaconic acid or an anhydride thereof, an olefin resin modified with acrylic acid or methacrylic acid, an ionomer resin, B
The resin component used for the layer can be used.

As the innermost layer, a layer mainly composed of an ethylene-α-olefin copolymer having the following characteristics can be preferably used for the purpose of improving the low-temperature heat sealability.

Innermost layer: ethylene α-olefin copolymer; (1) density (d) = 0.880 to 0.915 (g / cm)
3), preferably 0.890 to 0.915 (g / cm3
(2) Melt flow rate (MFR2.16) at 190 ° C. and 2.16 kg load = 0.01 to 200 (g / 10 min), preferably 0.1 to 30 (g / 10 min) (3) 190 ° C. 2. Ratio of melt flow rate (MFR2.16) at a load of 16 kg to melt flow rate (MFR21.6) at a load of 190 ° C. and a load of 21.6 kg (MFR2.16) / (MFR21.6) = 10 to 20 molecular weight Distribution (Mw / Mn) = 2.0-4.0, preferably 2.0-3.7

In the polyolefin-based multilayer film of the present invention, an adhesive layer can be provided outside the layer B if necessary.

As the adhesive layer, maleic acid, itaconic acid or an anhydride thereof, an olefin resin modified with acrylic acid or methacrylic acid, an ionomer resin,
An ethylene-vinyl acetate copolymer, a two-part curable adhesive such as a polyether polyurethane, a polyester, or a polyester polyurethane composed of a polyol component and a polyisocyanate component or a polycarboxylic acid component can be used.

In the polyolefin-based multilayer film of the present invention, a surface substrate can be provided outside the layer B if necessary.

As the surface substrate, biaxially stretched nylon (ON
Y), polyethylene terephthalate (PET), polyvinylidene chloride coated biaxially oriented polypropylene (KO)
P), biaxially oriented polypropylene (OPP), polyvinylidene chloride coated biaxially oriented nylon (KONY), polyethylene (PE), other plastic films, etc.
Substrates generally used as a sheet substrate, such as paper and aluminum foil, can be used, and they can also be used as a film / sheet laminated with these substrates.

For lamination of the layer B or the adhesive layer of the present invention and the surface substrate, a lamination method by dry lamination or extrusion lamination can be used.

In the polyolefin-based multilayer film of the present invention, the film thickness is in the range of 10 to 300 μm, preferably in the range of 15 to 200 μm, more preferably 20 μm.
１５０150 mμ.

The thickness of the layer B of the present invention is in the range of 5 to 150 μm, preferably 5 to 100 μm, more preferably 5 to 75 μm. If the thickness of the B layer is less than 5 μm, the impact resistance will be poor.

The method for producing the polyolefin-based multilayer film of the present invention is not particularly limited, and methods conventionally used in the production of multilayer films, for example, an inflation film forming method, a T-die film forming method, and laminating the film of each layer. Can be used.

In the polyolefin-based multilayer film of the present invention, a lubricant, an anti-blocking agent, an antioxidant, an ultraviolet absorber, a heat stabilizer, a heat stabilizer, Flames, inorganic / organic fillers, antistatic agents, coloring agents, and the like can be added.

The polyolefin-based multilayer film of the present invention may be irradiated with an electron beam, if necessary.

[0049]

EXAMPLES Hereinafter, 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. The method for measuring the properties of the components constituting each layer, the method for measuring physical properties, and the resin material used in the present invention are as follows.

The characteristics of the resin material constituting each layer used in the present invention were determined by the following measuring methods. The results are shown in Table 1. (1) Density: 190 according to JIS K7112
Melt flow rate (MFR) at 21.6 kg load at ℃
) The strand obtained at the time of measurement was heat-treated at 100 ° C for 1 hour, and slowly cooled to room temperature over 1 hour, and the sample was measured using a density gradient tube. (2) Melt flow rate (MFR2.16): JIS K
In accordance with 7210, using a melt indexer, 1
It was determined by measuring the weight of the resin extruded in a strand shape at 90 ° C. under a load of 2.16 kg for 10 minutes. (3) Melt flow ratio (MFR21.6) / (MFR2.16): In the same manner as in the above method (2), the weight of the resin obtained under a load of 21.6 kg was obtained by the resin obtained in the above (2). It is the value divided by the weight. (4) Molecular weight distribution: WATERS 15 as a measuring device
The measurement was carried out using 0 CV under the conditions of a column P Mixed B, a temperature of 135 ° C, and a solvent o-dichlorobenzene.

Examples 1 to 6 and Comparative Examples 1 to 3 Using the materials shown in Table 1, under the following film forming conditions, Table 2 was used.
Was produced. The thickness of each layer of the multilayer film was measured with a deflection microscope. [Film forming conditions] (1) Forming machine: T-die multilayer film forming machine (2) Forming temperature: 230 ° C. in die section (3) Cooling method: Use of air chamber and cooling roll (temperature 70 ° C.) (4) Surface treatment : Corona treatment on one side for dry lamination

The multilayer film and the surface substrate (KO) shown in Table 2
P: Daicel Chemical Industries Seneshi 6000 Film thickness: 20μ
The polyolefin-based multilayer film laminated with m) was produced under the following lamination conditions. [Lamination conditions] (1) Lamination method: dry lamination (2) Adhesive: DICDRY-LX77 manufactured by Dainippon Ink.
9A / KJ75

The layer A or the innermost layer of the polyolefin-based multilayer film was adhered under the following sealing conditions, and the characteristic values were determined by the following physical property measuring methods. The results are shown in Table 3. [Seal conditions] (1) Seal temperature: 150 ° C (2) Seal time: 1 sec

[Measurement Methods for Physical Properties] (1) Falling Ball Test: A condition in which the temperature is 23 ° C. and the humidity is 50% is fixed such that an iron ball dropped directly from a laminated bag-made product to a PVC cylinder hits a bottom seal portion. Then, an iron ball having a weight of 363 g was dropped from a height of 100 cm at the same position of the bag-made product, and the number of times the film was torn was measured. The measured value indicates the average value of five films. (2) Bottom Seal Impact Strength Measurement Test: Under a condition of a temperature of 23 ° C. and a humidity of 50%, the impact fracture energy of a strip-shaped seal portion was measured with a 25 mm long hammer-shaped hammer. The measured value indicates an average value of three films.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

[Table 3]

[0058]

According to the present invention, a polyolefin-based multilayer film having excellent impact resistance is provided.

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[Procedure amendment]

[Submission date] April 3, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

Layer B: ethylene-α-olefin copolymer; (B-1) density (d) = 0.880 to 0.915 (g /
cm3) (B-2) Melt flow rate at 190 DEG C., 2.16 kg load (MFR2.16) = 0.01 to 200 (g / 10 min) (B-3) Melt flow rate at 190 DEG C., 2.16 kg load Ratio of (MFR2.16) to melt flow rate (MFR21.6) at 190 ° C. under a load of 21.6 kg (MFR21.6) / (MFR2.16) = 10 to 20 (B-4) Molecular weight distribution (Mw /Mn)=2.0-4.0

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

Layer B: ethylene-α-olefin copolymer; (B-1) density (d) = 0.880 to 0.915 (g /
cm3), preferably 0.890 to 0.915 (g / c).
m3) (B-2) Melt flow rate at 190 DEG C. under a load of 2.16 kg (MFR2.16) = 0.01 to 200 (g / 10 min), preferably 0.1 to 30 (g / 10 min). 3) Ratio of melt flow rate (MFR2.16) at 190 ° C. and 2.16 kg load to melt flow rate (MFR 21.6) at 190 ° C. and 21.6 kg load (MFR 21.6) / (MFR 2.16) = 10-20 (B-4) Molecular weight distribution (Mw / Mn) = 2.0-4.
0, preferably 2.0 to 3.7

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction contents]

Innermost layer: ethylene α-olefin copolymer; (1) density (d) = 0.880 to 0.915 (g / cm)
3), preferably 0.890 to 0.915 (g / cm3
(2) Melt flow rate (MFR2.16) at 190 ° C. and 2.16 kg load = 0.01 to 200 (g / 10 min), preferably 0.1 to 30 (g / 10 min) (3) 190 ° C. 2. Ratio of melt flow rate (MFR 2.16) at 16 kg load to melt flow rate (MFR 21.6) at 190 ° C. and 21.6 kg load (MFR 21.6) / (MFR
R2.16) = 10-20 (4) Molecular weight distribution (Mw / Mn) = 2.0-4.0, preferably 2.0-3.7

Claims (1)

[Claims] 1. A polyolefin-α-olefin copolymer comprising a layer A composed of a polyethylene resin and a layer B mainly composed of an ethylene-α-olefin copolymer having the following properties; B-1) Density (d) = 0.880 to 0.915 (g /
cm3) (B-2) Melt flow rate at 190 DEG C., 2.16 kg load (MFR2.16) = 0.01 to 200 (g / 10 min) (B-3) Melt flow rate at 190 DEG C., 2.16 kg load Ratio of (MFR2.16) to melt flow rate (MFR21.6) at 190 ° C. under a load of 21.6 kg (MFR2.16) / (MFR21.6) = 10 to 20 (B-4) Molecular weight distribution (Mw /Mn)=2.0-4.0