JPH09254341A - Multi-layer film for packaging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low costed packaging multi-layer film used for packaging such as prepack of food or the like wherein moderate elasticity and tackiness are provided, and well balanced performances such as being excellent in transparency, cut properties, heat sealing properties, fog resistance, etc., are provided. SOLUTION: In the packaging multi-layer film, an inner layer consisting of the following inner layer resin or resin composition is laminated between outer layers consisting of the following outer layer resin composition. The outer layer composition is formed of (A)59.5-99.5wt.% ethylene and α-olefin copolymer of 0.1-10g/min melt flow rate and 0.850-under 0.910g/cm<3> density, (B) 0-40wt.% high pressure method low density polyethylene, and (C) 0.5-10wt.% fog resistance agent. The inner layer resin is formed of an ethylene and α-olefin copolymer wherein (D) melt flow rate is 0.1-10g/min, and density is 0.900-0.950g/cm<3> and larger than the density of the composition (A). The inner layer composition is a composition containing (E) butene polymer and (F) propylene polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin-based multilayer film for packaging, which is used for various packaging applications such as pre-packing in supermarkets and heat-sealing packaging. The present invention relates to a multi-layer film for packaging which is excellent not only in performance but also in cuttability.

[0002]

2. Description of the Related Art Conventionally, in supermarkets and the like, plastic films have been used as commercial packaging films for prepacking foods such as vegetables. This pre-packed film is a film for covering and wrapping foods that are subdivided and stored in plastic trays or the like, or foods that are still naked, and are transparent and have appropriate elongation elasticity and adhesiveness. It is required that the film be easily cut, the inside of the film should not fog when packaged, and that the heat sealing performance should be excellent. Conventionally, a film made of a polyvinyl chloride polymer or an ethylene / vinyl acetate copolymer has been used as such a packaging film. Of these, polyvinyl chloride-based polymers have excellent performance, but chlorine-free materials are required due to recent environmental problems. Further, the ethylene / vinyl acetate copolymer film is expensive and the packaging cost is high, and there are problems such as the problem of odor and the rust of the roll of the packaging machine.

As a packaging film for improving such a point, JP-A-4-246536 discloses a linear low-density ethylene / α-olefin copolymer and a low-density polyethylene and / or ethylene / vinyl acetate copolymer. A multilayer film in which an intermediate layer made of butene-based resin is laminated between outer layers made of and is disclosed as a stretch film. However, although such a multilayer film is excellent in transparency, elongation elasticity, cuttability, etc., it has a problem that adhesiveness and heat sealability are not always sufficient. When the temperature is lowered, there is a problem that a hole is formed in the film during high temperature sealing.

[0004]

DISCLOSURE OF THE INVENTION The present inventor has examined the use of a polyolefin resin as a material for a packaging multi-layer film, and has a lower cost and strength as compared with a conventional ethylene / vinyl acetate copolymer film. Excellent, further having properties comparable to the performance of polyvinyl chloride-based film, as a result of studying a multilayer film that can withstand practical use, by having a specific multilayer structure, transparency, excellent cutability,
It was found that a multilayer film for packaging made of a polyolefin-based polymer having a balanced performance can be obtained, and the present invention has been completed. An object of the present invention is to provide a packaging multilayer film having a balanced performance such as having appropriate elongation elasticity and tackiness, and having excellent transparency, cuttability, heat sealability, antifogging property, etc. is there.

[0005]

The present invention relates to the following multilayer film for packaging. (1) A multilayer film for packaging, wherein an inner layer made of the following inner layer resin or resin composition is laminated between outer layers made of the following outer layer resin composition. Outer layer resin composition: (A) a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, having a melt flow rate (MFR) at 190 ° C. and a load of 2.16 kg of 0.1 to 10 g / 1.
0 min, density of 0.850 g / cm ³ or more and 0.910 g / cm ³
An ethylene / α-olefin copolymer having a molecular weight of less than ³ cm ³ .
5 to 99.5% by weight, (B) density is 0.915 to 0.9
High-pressure low density polyethylene of 30 g / cm ³ 0-40% by weight, and (C) antifogging agent 0.5-10% by weight. Inner layer resin: (D) a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, having a melt flow rate (MFR) of 0.1 to 10 g / 1 at 190 ° C. and a load of 2.16 kg.
0 minutes, the density is 0.900 to 0.950 g / cm ³ , and ethylene.α which is the component (A) of the outer layer resin composition.
An ethylene / α-olefin copolymer, which is relatively higher than the density of the olefin copolymer. Inner layer resin composition: (E) a butene-based polymer having a melt flow rate (MFR) of 0.1 to 5 g / 10 minutes at 190 ° C. and a load of 2.16 kg and a density of 0.890 to 0.930 g / cm ³ , and (F) Melt flow rate (MFR) at 230 ° C. and 2.16 kg load is 0.1 to 100 g / 1.
A resin composition containing a propylene-based polymer having a density of 0.880 to 0.920 g / cm ³ for 0 minutes. (2) The ethylene / α-olefin copolymer of component (A) and / or the ethylene / α-olefin copolymer of component (D) is a copolymer produced by a metallocene catalyst. The multilayer film for packaging according to (1) above. (3) The multilayer film for packaging as described in (1) or (2) above, wherein the component (A) is not a single component but is composed of a plurality of components having different densities and / or melt flow rates (MFR). (4) The inner layer resin composition is a composition containing 80 to 20% by weight of a butene-based polymer as the component (E) and 20 to 80% by weight of a propylene-based polymer as the component (F). The multilayer film for packaging according to any one of (1) to (3). (5) The multilayer film for packaging according to any one of (1) to (4) above, wherein the multilayer film is a film for prepacking or heat sealing packaging.

<< Outer Layer Resin Composition >> Ethylene.α-used as the component (A) of the outer layer resin composition in the present invention.
The olefin copolymer is a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, preferably 3 to 16 carbon atoms, and has a melt flow rate at 190 ° C. and a load of 2.16 kg of 0.1 to 10 g /. 10 minutes, preferably 0.3-
8 g / 10 min, more preferably 0.5 to ⁴ g / 10 min, and a density of 0.850 g / cm ³ or more and 0.910 g /
less than cm ³ , preferably 0.880 to 0.907 g / c
m ³ , more preferably 0.885 to 0.905 g / cm ³
Is an ethylene / α-olefin copolymer. As the component (A), one type of ethylene / α-olefin copolymer having the above-mentioned physical properties may be used alone, or two or more types of ethylene / α-olefin copolymers may be used so as to fall within the above physical properties. They can be used in combination. In the latter case, ethylene / α-olefin copolymers within the above range may be used in combination, or ethylene / α-olefin copolymers outside the above range may be partially contained.

Ethylene / α used as component (A)
The olefin copolymer has a crystallinity of about 0 to 50%, preferably 5 to 45%, more preferably 10 to 40% by X-ray diffraction, and ethylene units as a main component;
For example, 80 to 99 mol%, preferably 85 to 97 mol%, and more preferably 88 to 95 mol% is desirable.

As the α-olefin copolymerizable with ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1
-Decene, 3-methyl-1-butene, 4-methyl-1-
Penten and the like are exemplified. The α-olefin as a comonomer is not limited to one type, and two or more types can be used like a terpolymer.

Ethylene / α used as component (A)
The olefin copolymer can be obtained usually by copolymerizing ethylene and an α-olefin in a gas phase or a liquid phase in the presence of a transition metal catalyst. The catalyst for production is not particularly limited and, for example, a Ziegler type catalyst, a Phillips type catalyst, a metallocene type catalyst and the like can be used, but a metallocene type catalyst is preferable. Also, the polymerization method is not particularly limited, and the polymerization can be carried out by a gas phase method, a solution method, a bulk polymerization method or the like. As the component (A), a commercially available product may be used.

The ethylene / α-olefin copolymer as the component (A) is 59.5 to 99.5% by weight in the outer layer resin composition,
Preferably 70-98% by weight, more preferably 85-9%
7% by weight is blended. When the compounding ratio of the component (A) is less than 59.5% by weight, the transparency and strength are poor, and when it is more than 99.5% by weight, the antifogging property is poor.

The high-pressure low-density polyethylene (H) used as the component (B) of the outer layer resin composition in the present invention.
PLD) is a highly branched polyethylene having long chain branches produced by so-called high-pressure radical polymerization, and has a density of 0.915 to 0.930 g / cm ³ , preferably 0.918 to 0.927 g / cm ³ , More preferably, the polyethylene is 0.920 to 0.925 g / cm ³ . The high-pressure low-density polyethylene used as the component (B) in the present invention has a M content of 190 ° C. and a load of 2.16 kg.
FR of 0.01 to 100 g / 10 min, preferably 0.0
5 to 10 g / 10 min, more preferably 0.1 to 8 g / 1
It is desirable to be in the range of 0 minutes.

This high-pressure low-density polyethylene has a swell ratio representing the degree of long-chain branching, that is, an inner diameter (D) of 2.0 m at 190 ° C. using a capillary flow characteristic tester.
The ratio (Ds / D) of the diameter (Ds) of a strand extruded from a nozzle having a length of 15 mm at an extrusion speed of 10 mm / min to the inner diameter D of the nozzle is desirably 1.3 or more.
The high-pressure low-density polyethylene used as the component (B) is 50 mol% or less, preferably 30 mol% or less, and more preferably 2 mol% or less, as long as the object of the present invention is not impaired.
It may be a copolymer with 0 mol% or less of other polymerizable monomers such as α-olefin, vinyl acetate, and acrylate.

The component (B), HPLD, is incorporated in the outer layer resin composition in an amount of 0 to 40% by weight, preferably 5 to 30% by weight, more preferably 10 to 20% by weight. HPLD does not necessarily need to be blended, but blending improves moldability. Further, if the blending ratio of HPLD exceeds 40% by weight, transparency and flexibility are deteriorated.

The antifogging agent used as the component (C) of the resin composition for the outer layer is a chemical agent added to prevent the moisture in the air from condensing on the surface of the film to cause clouding.
There is no particular limitation as long as it makes the surface of the film hydrophilic and spreads generated water droplets, and those generally used as antifoggants can be used as they are. A surfactant is used as such an antifogging agent, and for example, sorbitan monooleate, sorbitan monolaurate,
Sorbitan fatty acid esters such as sorbitan monobehenate and sorbitan monostearate; glycerin fatty acid esters such as glycerin monooleate and glycerin monostearate; diglycerin monooleate, diglycerin sesquilaurate, diglycerin sesquioleate, tetraglycerin monooleate, Tetraglycerin monostearate, hexaglycerin monolaurate, hexaglycerin monooleate, degaglycerin monooleate,
Examples include, but are not limited to, polyglycerin fatty acid esters such as decaglycerin monolaurate; polyoxyalkylene ethers such as polyoxyethylene lauryl ether; fatty acid amines such as lauryl diethanolamine; fatty acid amides such as oleic acid amide. But also they are used alone or as a mixture.

The above-mentioned component (C) antifogging agent is 0.5 to 10% by weight, preferably 0.5 to 8% by weight, in the outer layer resin composition.
More preferably, the content is 1 to 5% by weight. When the compounding ratio of the antifogging agent is less than 0.5% by weight, the antifogging effect cannot be obtained, and when it is more than 10% by weight, transparency is deteriorated due to bleeding of the antifogging agent. The anti-fog agent is previously mixed with either component (A) or (B), preferably a part of component (A), to form a masterbatch, which is then mixed with the remaining components to obtain a resin composition. Is preferred.

In the present invention, since the ethylene / α-olefin copolymer (A) having the above-mentioned density is used as the main component of the outer layer resin composition, such an ethylene / α-olefin copolymer ( Even when an outer layer resin composition comprising only two components in which A) is blended with an antifogging agent (C), a multilayer film as the object of the present invention can be obtained. For example, a low density ethylene-based elastomer is contained in the outer layer resin composition. The purpose can be achieved without blending other components such as.

The outer layer resin composition of the present invention contains a weather resistance stabilizer, a heat resistance stabilizer, an antistatic agent, an antislip agent, an antiblocking agent, a lubricant, a pigment, a dye, within a range that does not impair the object of the present invention. Additives such as a nucleating agent, a plasticizer, an antiaging agent, a hydrochloric acid absorbent, and an antioxidant may be blended as necessary.

The outer layer resin composition of the present invention can be produced by a known method, for example, the following method. 1) A method of mechanically blending the components (A) to (C) and optionally other components with an extruder, a kneader or the like. 2) Dissolving the components (A) to (C), and optionally other components, in a suitable good solvent (for example, a hydrocarbon solvent such as hexane, heptane, decane, cyclohexane, benzene, toluene and xylene), Then a method of removing the solvent. 3) A method of separately preparing solutions in which the components (A) to (C) and other components to be added, if necessary, are separately dissolved in a suitable good solvent, mixing, and then removing the solvent. 4) A method in which the above methods 1) to 3) are combined.

<< Inner Layer Resin >> The ethylene / α-olefin copolymer used as the component (D) of the inner layer resin in the present invention is ethylene and has 3 to 20 carbon atoms, preferably 3 carbon atoms.
A copolymer of .about.16 .alpha.-olefin,
The melt flow rate at a temperature of 2.16 kg under a temperature of 0.1 to 10 g / 10 minutes, preferably 0.3 to 8 g / 1.
0 minutes, more preferably 0.5 to ⁴ g / 10 minutes, and have a density of 0.900 to 0.950 g / cm ³ , preferably 0.910 to 0.945 g / cm ³ , and more preferably 0.920 to. It is an ethylene / α-olefin copolymer of 0.940 g / cm ³ . As the component (D), an ethylene / α-olefin copolymer having the above physical properties can be used, but in the combination of the outer layer resin composition and the inner layer resin, the ethylene / α-olefin used as the component (A) is used. Ethylene / α-olefin copolymerization having a density relatively higher than that of the copolymer, preferably 0.015 to 0.100 g / cm ³ , more preferably 0.020 to 0.100 g / cm ^3. Use coalescing. By using the inner layer resin having a relatively large density, the sealing start temperature of the film can be lower and the perforation temperature at the time of high temperature sealing can be higher.

Ethylene / α used as component (D)
-The olefin copolymer has a crystallinity of about 40 to 70% by an X-ray diffraction method, an ethylene unit as a main component,
For example, 90 to 99 mol%, preferably 93 to 99 mol%, more preferably 95 to 98 mol% is desirable.

As the α-olefin copolymerizable with ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1
-Decene, 3-methyl-1-butene, 4-methyl-1-
Penten and the like are exemplified. The α-olefin as a comonomer is not limited to one type, and two or more types can be used like a terpolymer.

Ethylene / α used as component (D)
The olefin copolymer can be obtained usually by copolymerizing ethylene and an α-olefin in a gas phase or a liquid phase in the presence of a transition metal catalyst. The catalyst for production is not particularly limited and, for example, a Ziegler type catalyst, a Phillips type catalyst, a metallocene type catalyst and the like can be used, but a metallocene type catalyst is preferable. Also, the polymerization method is not particularly limited, and the polymerization can be carried out by a gas phase method, a solution method, a bulk polymerization method or the like. As the component (D), a commercially available product may be used.

<< Inner Layer Resin Composition >> In the present invention, the butene-based polymer used as the component (E) of the inner layer resin composition is a polymer containing 1-butene as a main monomer.
Melt flow rate (MFR) at 90 ° C. under a load of 2.16 kg is 0.1 to 5 g / 10 minutes, preferably 0.5.
To 5 g / 10 min, more preferably 0.5 to ³ g / 10 min, and the density is 0.890 to 0.930 g / cm ³ , preferably 0.895 to 0.925 g / cm ³ , and more preferably 0. It is a butene-based polymer of 0.895 to 0.920 g / cm ³ . The butene-based polymer used as the component (E) is preferably one having 1-butene of 70 mol% or more and a crystallinity of 65% or less by an X-ray diffraction method. Other monomers to be copolymerized with 1-butene include ethylene, propylene and other α-olefins having 5 to 20 carbon atoms. The method for polymerizing these butene-based polymers is not limited, and the same methods as those described for the component (A) or (D) can be used.

The propylene-based polymer used as the component (F) of the resin composition for the inner layer in the present invention is a polymer having propylene as a main monomer, and is 230 ° C., 2.1.
Melt flow rate (MFR) under a load of 6 kg is 0.1 to 100 g / 10 min, preferably 0.5 to 20 g
/ 10 minutes, more preferably 1 to 10 g / 10 minutes,
It is a propylene-based polymer having a density of 0.880 to 0.920 g / cm ³ , preferably 0.890 to 0.915 g / cm ³ . The propylene-based polymer used as the component (F) preferably has a propylene content of 80 mol% or more and a crystallinity of 70% or less according to the X-ray diffraction method. Other monomers to be copolymerized with propylene include ethylene and other α-olefins having 4 to 20 carbon atoms.
The method for polymerizing these propylene-based polymers is not limited, and the same methods as those described for the component (A) or (D) can be used.

The blending ratio of the butene polymer which is the component (E) and the propylene polymer which is the component (F) of the resin composition for the inner layer is 80 to 20% by weight of the component (E) and (F).
It is desirable that the amount of the component is 20 to 80% by weight.

As the inner layer resin or resin composition, it is preferable to use a resin or resin composition having a softening temperature relatively higher than that of the outer layer resin composition, preferably 15 ° C. or more. When the softening temperature of the inner layer resin or resin composition is relatively higher than the softening temperature of the outer layer resin composition, when the inner layer resin or resin composition is used, the outer layer is melted but the inner layer is not melted and the shape is maintained. It can be heat-sealed and more excellent heat-sealing property can be obtained.

Further, as the inner layer resin or resin composition,
Melting point (hereinafter referred to as DSC) measured by a differential calorimeter (DSC)
It is preferable to use a resin or resin composition whose melting point) is relatively higher than the DSC melting point of the outer layer resin composition, preferably 15 ° C. or higher. When the inner layer resin or resin composition having a DSC melting point of the inner layer resin or resin composition higher than the DSC melting point of the outer layer resin composition is used, the outer layer is melted but the inner layer is not melted and the shape is maintained. It can be heat-sealed and more excellent heat-sealing property can be obtained.

Further, the inner layer resin or resin composition has a DSC melting point relatively higher than the softening temperature of the outer layer resin composition, preferably 15 ° C. or higher, more preferably 20.
It is preferred to use resins or resin compositions that are ~ 80 ° C higher. When the inner layer resin or resin composition having a DSC melting point of the inner layer resin or resin composition higher than the softening temperature of the outer layer resin composition is used, the outer layer melts but the inner layer does not melt and the shape is maintained. It can be heat-sealed and further excellent heat-sealing property can be obtained.

The inner layer resin or resin composition contains a weather resistance stabilizer, a heat resistance stabilizer, and a heat resistance stabilizer within a range not impairing the object of the present invention.
Antistatic agent, anti-slip agent, anti-blocking agent,
Additives such as a lubricant, a pigment, a dye, a nucleating agent, a plasticizer, an antioxidant, a hydrochloric acid absorbent, and an antioxidant may be added as necessary.

The inner layer resin or resin composition is (D) to
Produced by the same method as described for the outer layer resin composition, such as mechanically blending the component (F) and other components to be added if necessary, or dissolving and mixing in a solvent and then removing the solvent. be able to.

<< Multilayer Film >> The multilayer film of the present invention is an outer layer in which an outer layer made of the outer resin composition is laminated on both sides of an inner layer made of the inner resin or resin composition.
It is a three-layer structure film having a three-layer structure of inner layer / outer layer. The outer layers on both sides of this multilayer film may be surface layers of the same composition, or compositions belonging to the range of the above composition but having different component compositions may be used.

The multilayer film of the present invention has a total thickness of usually 5 to 30 μm, preferably 10 to 20 μm. When the thickness of the film is less than 5 μm, the handleability of the film is significantly reduced due to a decrease in strength and waist of the film,
If it exceeds 30 μm, the stress at the time of stretching the film becomes large, and the tray and the packaged object are easily deformed, which is not preferable. The thickness of the inner layer of the multilayer film of the present invention is preferably 10 to 50% of the total film thickness, specifically 0.5 to
A thickness of 15 μm, preferably 2.0 to 8.0 μm is suitable. If the thickness of the inner layer film is less than 10% of the film thickness, the effect of improving the cuttability cannot be expected,
If it exceeds 50%, the transparency may be impaired. The thickness of the outer layer should be approximately equal on both sides, 1 to 20 μm
m, preferably 2 to 10 μm.

The method for producing such a multilayer film is carried out by a conventional molding method using each of the above resin compositions,
Specifically, it can be manufactured by laminating by ordinary inflation molding, air-cooled two-stage inflation molding, T-die film molding, extrusion lamination molding, or the like. Among these, inflation molding having a good balance of vertical and horizontal properties is preferable.

The multi-layer film for packaging of the present invention thus obtained has appropriate elongation elasticity and tackiness, and is excellent in transparency, cuttability, heat sealability, antifogging property, etc. It can be used as a packaging film. When used as a film for pre-packing When a packaged item such as food is placed on a plastic tray or is wrapped with the multilayer film of the present invention while being naked, it does not damage the packaged item due to moderate elongation elasticity and is in a state that matches the shape. It can be stretch-wrapped and can be sealed and adhered with an appropriate heat-sealing property to maintain the packaged state without using other fixing means. In this case, it is possible to cut the film at an arbitrary place and perform packaging by an excellent cut property, and the package body can be visually recognized by the transparency, and the inside of the package is clouded by the anti-fog property. Absent.

The multilayer film of the present invention can be used as a wrap film as it is in the state of a film, and since it is excellent in heat sealability, it is formed into a bag, a bag or other heat seal packaging material to accommodate an object to be packaged, or It can also be used as a lid for containers such as bottles and blister packs. In each case, the excellent characteristics as the packaging film as described above are obtained. By selecting a combination in which the softening temperature of the inner layer is higher than the softening temperature of the outer layer, more excellent heat sealing properties can be obtained.

The multi-layer film for packaging of the present invention is cheaper than conventional ethylene / vinyl acetate films, has no odor problem, is less likely to rust on the roll of the packaging machine, and can be used as a plasticized polyvinyl chloride after use. It is a packaging material that does not have a problem of disposability and has no problem in food hygiene. This film can stretch-package various foods as a stretch film for food packaging, and can be widely used as a film for prepacking or heat-sealing packaging.

[0037]

As described above, since the packaging multilayer film of the present invention comprises a laminate of an outer layer and an inner layer made of a specific composition, it has appropriate elongation elasticity and tackiness, and has transparency and cuttability. It is possible to obtain an inexpensive packaging film having well-balanced performance such as excellent heat sealing property and antifogging property.

By using the above-mentioned multilayer film as a film for prepacking or heat-sealing packaging, it is possible to stretch-wrap the product to be packaged without damaging the product to be packaged, and the self-adhesive property allows the product to be packaged. In addition to maintaining the above, the cut property facilitates packaging, the contents are clearly visible in the packaged state, no fogging occurs, and heat sealing is easy, and an excellent package is obtained.

[0039]

Embodiments of the present invention will be described below. The measurements and evaluations of the physical properties in the description of the present invention and the following examples were performed by the following methods. 1) MFR; ASTM D1238 2) Density; ASTM D1505 3) Haze; ASTM D1003 4) Actual packaging test; Packaging machine (Teraoka Seiko AW-2600)
(Jr.PE), an actual packaging test was performed, and cutability, finger pressure recovery, and seal adhesion at each heater temperature were examined. 5) Measurement of softening temperature: A film having a thickness of 15 μm was prepared by inflation or casting, and heat-sealed under the following conditions. The heat-sealing strength was measured under the following conditions, and the heat-sealing temperature at which the heat-sealing strength was 100 gf or more was obtained. Was taken as the softening temperature. Heat sealing conditions; pressure 2 kgf / cm ² , time 1
sec, width 5 mm Heat seal strength measurement conditions; tension, 23 ° C., crosshead speed 300 mm / min 6) DSC melting point measurement: sample of resin or resin composition was raised from 30 ° C. to 200 ° C. at a rate of 10 ° C./min After the temperature was maintained for 5 minutes, the temperature was lowered to 30 ° C. at a rate of 10 ° C./min, the temperature was maintained for 5 minutes, and the temperature was raised at a rate of 10 ° C./min.

Antifog Masterbatch Ethylene / hexene-1 copolymer (A) produced by metallocene type catalyst (ethylene content 93.7 mol%, crystallinity 25%, density 0.901 g / cm ³ , 190 ℃,
MFR at a load of 2.16 kg 3.4 g / 10 minutes) 9
A composition comprising 4% by weight, 5% by weight of diglycerin sesquilaurate, 0.75% by weight of polyoxyethylene lauryl ether and 0.25% by weight of lauryldiethanolamine was subjected to a twin-screw extruder having a diameter of 30 mm and L / D = 26. The resulting mixture was kneaded and granulated at a resin temperature of 200 ° C., and was used as an antifogging agent master batch (C).

Example 1 Ethylene / hexene-1 copolymer (A) (ethylene content 93.7 mol%, crystallinity 25%, density 0.901 g /
cm ^3, 190 ℃, MFR a load of 2.16kg
3.4 g / 10 min) 50% by weight, high-pressure low-density polyethylene (B) (density 0.925 g / cm ³ , 190 ° C., MFR 0.57 g / 10 min at 2.16 kg load) 1
0% by weight and 40% by weight of the antifogging agent master batch (C) are blended to form an outer layer resin composition (softening temperature: 80 ° C.,
DSC melting point 100 ° C.) was obtained.

Butene / propylene copolymer (E) (1-
Butene content 78 mol%, crystallinity 39%, density 0.90
M at 0 g / cm ³ , 190 ° C., 2.16 kg load
FR 1.0 g / 10 min) 50% by weight and propylene
Ethylene / butene copolymer (F) (Propylene content 9
5.2 mol%, butene content 1.6 mol%, crystallinity 55
%, Density 0.910 g / cm ³ , 230 ° C., load 2.1
An inner layer resin composition (softening temperature 118 ° C., DS
C melting point 135 ° C).

The above-mentioned outer layer and inner layer resin compositions were respectively prepared by using three extruders having a diameter of 50 mm and L / D = 26.
At a resin temperature of 200 ° C. and a blow-up ratio of 4.1, the inner layer resin composition was extruded to form an intermediate layer, and each layer had a thickness of 6
A film having a thickness of / 3/6 μm and a total thickness of 15 μm was obtained. Using this film, film physical properties were evaluated by the method described above. The results are shown in Table 1.

Example 2 In Example 1, an ethylene / hexene-1 copolymer (D) (ethylene content 96.6) was used instead of the inner layer resin composition.
Mol%, crystallinity 63%, density 0.931 g / cm ³ ,
MFR 2.0g / at 190 ° C and load 2.16kg
The same procedure as in Example 1 was performed except that the softening temperature was 116 ° C. and the DSC melting point was 125 ° C. for 10 minutes, and the thickness of each layer was changed to 5/5/5 μm. The results are shown in Table 1.

Example 3 In Example 1, as the inner layer resin composition, 80% by weight of butene-propylene copolymer (E) and propylene
Resin composition blended with 20% by weight of ethylene / butene copolymer (F) (softening point 107 ° C., DSC melting point 128
The same procedure as in Example 1 was carried out except that (.degree. The results are shown in Table 1.

Example 4 In Example 2, ethylene / hexene-1 copolymer (D) was used as the inner layer resin (ethylene content 94.5 mol%, crystallinity 38.2%, density 0.910 g / cm ³ , 190
MFR 2.0g / 10 at ℃, load 2.16kg
Min, a softening temperature of 100 ° C. and a melting point of 110 ° C.). The results are shown in Table 1.

Comparative Example 1 In Example 1, without using the resin composition for the inner layer,
Example 1 except that the outer layer resin composition was used to form three layers.
I went the same way. The results are shown in Table 1.

Comparative Example 2 In Example 1, the propylene / ethylene / butene copolymer (F) (softening temperature 120) was used as the inner layer resin composition.
C., DSC melting point 135.degree. C.) was used alone, but in the same manner as in Example 1. The results are shown in Table 1. Since the multilayer film of Comparative Example 2 had poor film flexibility and was too hard, there was a problem that the tray was deformed during the actual packaging test.

[0049]

[Table 1]

The evaluation criteria of Table 1 are as follows. << Cutability >> ：: After tray packaging, the film can be cut without any problem by the film cutting blade of the packaging machine. ×: After the tray packaging, the film cannot be cut by the film cutting blade of the packaging machine. << Shiatsu Acuity Restoration >> A: Almost no trace of the finger remains even if the film on the upper surface of the tray after packaging is lightly pressed with a finger. ×: When the film on the upper surface of the tray after packaging is lightly pressed with a finger, a finger mark is clearly left. << Seal Adhesion >> ：: The adhesion of the seal portion on the bottom surface of the tray after packaging is good, and the packaging state can be maintained. X: The packaging state cannot be maintained due to poor adhesion of the seal portion on the bottom surface of the tray after packaging, or the packaging film cannot be maintained because the film on the bottom surface is melted and a hole is opened. * 1: Since the heater temperature at the time of bonding the seal is higher than the melting point of the inner layer resin, perforation may occur, but at the heater temperature below the melting point, the seal adhesion is good.

From the results shown in Table 1, it can be seen that all the multilayer films of the examples are excellent in transparency, film cutting property, finger pressure restoring property and seal adhesive property. On the other hand, the multi-layer film of Comparative Example 1 has a markedly poor cuttability,
Further, it was found that perforation occurred at the time of high temperature heat sealing, which was not sufficient as a packaging film. In addition, the multilayer film of Comparative Example 2 has good results shown in Table 1, but since the flexibility of the film is poor and it is too hard, there is a problem that the tray is deformed during the actual packaging test. It was insufficient.

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Claims (5)

[Claims] 1. A multi-layer film for packaging, wherein an inner layer made of the following inner layer resin or resin composition is laminated between outer layers made of the following outer layer resin composition. Outer layer resin composition: (A) a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, having a melt flow rate (MFR) at 190 ° C. and a load of 2.16 kg of 0.1 to 10 g / 1.
0 min, density of 0.850 g / cm ³ or more and 0.910 g / cm ³
An ethylene / α-olefin copolymer having a molecular weight of less than ³ cm ³ .
5 to 99.5 wt%, (B) a high pressure process having a density of 0.915~0.930g / cm ³ low-density polyethylene 0-40 wt%, and (C) anti-fogging agent 0.5 to 10 wt%. Inner layer resin: (D) a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, having a melt flow rate (MFR) of 0.1 to 10 g / 1 at 190 ° C. and a load of 2.16 kg.
0 minutes, the density is 0.900 to 0.950 g / cm ³ , and ethylene.α which is the component (A) of the outer layer resin composition.
An ethylene / α-olefin copolymer, which is relatively higher than the density of the olefin copolymer. Inner layer resin composition: (E) a butene-based polymer having a melt flow rate (MFR) of 0.1 to 5 g / 10 minutes at 190 ° C. and a load of 2.16 kg and a density of 0.890 to 0.930 g / cm ³ , and (F) A resin composition containing a propylene-based polymer having a melt flow rate (MFR) at 230 ° C. and a load of 2.16 kg of 0.1 to 100 g / 10 minutes and a density of 0.880 to 0.920 g / cm ³ . 2. The ethylene / α-olefin copolymer of component (A) and / or the ethylene / α-olefin copolymer of component (D) is a copolymer produced by a metallocene catalyst. The multilayer film for packaging according to claim 1, characterized in that: 3. The multilayer film for packaging according to claim 1, wherein the component (A) is not a single component but comprises a plurality of components having different densities and / or melt flow rates (MFR). 4. The inner layer resin composition is a composition containing 80 to 20% by weight of a butene polymer as a component (E) and 20 to 80% by weight of a propylene polymer as a component (F). The multilayer film for packaging according to any one of claims 1 to 3. 5. The multilayer film for packaging according to claim 1, wherein the multilayer film is a film for prepacking or heat sealing packaging.