JP2015123642A - Multilayer film, and packaging material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film and a packaging material which have excellent transparency, chemical resistance and moisture-proof performance, can be easily cut off linearly, whose cut surface becomes linear, and which have excellent mechanical properties, such as tensile strength and piercing strength.SOLUTION: There is provided a multilayer film in which a base material, an adhesion layer and a sealant layer are laminated in this order, in which the sealant layer has a layer containing cyclic olefin resin and low-density polyethylene resin, content of the cyclic olefin resin in the layer containing the cyclic olefin resin and polyethylene resin is 30 mass% or more and less than 70 mass% with respect to the total mass of the layer, and the sealant layer contains the low-density polyethylene resin.

Description

  The present invention relates to a multilayer film containing a low density polyethylene resin and a cyclic olefin resin, and a packaging material using the same.

  In recent years, cellopoly and glassine paper obtained by laminating cellophane and polyethylene have been used as materials for packaging pharmaceuticals, food and drinks, and the like. Although the packaging material using these can be opened easily by tearing by hand, it does not cut linearly and further has a drawback that the opening surface (cut surface) becomes corrugated. Moreover, there exists a fault that it is inferior to tensile strength and the intensity | strength at the time of piercing the surface. Cellophane used for cellopoly is not suitable for long-term storage of contents because of its poor moisture resistance, and is not normally used for packaging materials that are stored for a long time such as OTC drugs (general drugs). In addition, the shape may change due to moisture absorption, and there is a problem in dimensional stability.

  On the other hand, since the cyclic olefin resin is excellent in transparency, chemical resistance, moisture resistance, mechanical properties, and the like, it is used as a material for optical use, medicine or medical equipment use. Moreover, since cyclic olefin resin is excellent also in melt processability, fluidity | liquidity, heat-shrinkability, and printing characteristics, it is utilized also as a film-shaped or sheet-shaped molded product, and a packaging material. As described above, the cyclic olefin resin is used in various fields.

  Incidentally, it is common practice to add additives to the cyclic olefin resin to improve the physical properties of the molded body. It is known that the physical properties to be improved are not determined depending on the kind of the additive, and the physical properties to be improved are different depending on the blending amount of the additive and the physical properties of the additive itself. For example, Patent Document 1 proposes a multilayer film in which a resin layer containing low-density polyethylene as a main component and a layer containing low-density polyethylene and a cyclic olefin resin in a specific ratio are laminated. In the said multilayer film, characteristics, such as easy openability, are provided by making content of cyclic olefin resin into 10-30 mass%. Patent Document 2 proposes a film containing low-density polyethylene and a cyclic olefin copolymer. In the film, characteristics such as easy tearability are imparted by adding 2% by weight or more of the cyclic olefin copolymer.

JP 2007-55234 A JP 2012-72210 A

  However, the conventional film as described above has a problem that the opening surface (cut surface) when it is opened by tearing by hand, and there are problems such as insufficient tensile strength and piercing strength.

  The present invention has been made in view of the problems in the conventional film as described above, and its purpose has excellent transparency, chemical resistance and moisture resistance, and can be easily cut linearly, An object of the present invention is to provide a film having a cut surface that is linear and excellent in mechanical properties such as tensile strength and piercing strength, and a packaging material using the film.

The present invention for solving the above problems is as follows.
(1) A multilayer film in which a base material, an adhesive layer and a sealant layer are laminated in this order, wherein the sealant layer has a layer containing a cyclic olefin resin and a polyethylene resin, and the layer contains the cyclic olefin resin and the polyethylene resin. A multilayer film in which the content of the cyclic olefin resin is 30% by mass or more and less than 70% by mass with respect to the total mass of the layer, and the sealant layer contains a low-density polyethylene resin.
(2) The sealant layer includes a layer containing a cyclic olefin resin and a polyethylene resin and two or more layers including a layer made of a low density polyethylene resin, and the layer disposed at the position farthest from the adhesive layer is directly The multilayer film according to (1), which is a layer not containing a chain-like low density polyethylene.
(3) The sealant layer is composed of a layer (A) mainly composed of a low density polyethylene resin or a linear low density polyethylene resin, a layer (B) containing a cyclic olefin resin and a polyethylene resin, and a low density polyethylene resin. The multilayer film as described in (1) or (2) which is a layer which laminated | stacked the layer (C) which becomes this in order of (A) / (B) / (C).
(4) The content of the cyclic olefin resin in the cyclic olefin resin and the polyethylene resin is 40% by mass or more and less than 60% by mass with respect to the total mass of the layer containing the cyclic olefin resin and the polyethylene resin. The multilayer film according to any one of (3) to (3).
(5) The multilayer film according to any one of (1) to (4), wherein the total thickness of the film is 100 μm or less.
(6) A packaging material formed by molding the multilayer film according to any one of (1) to (5).

  According to the present invention, it has excellent transparency, chemical resistance and moisture resistance, can be easily cut linearly, the cut surface is linear, and has mechanical properties such as tensile strength and piercing strength. An excellent film and packaging material can be provided.

The multilayer film of the present invention is obtained by laminating a base material, an adhesive layer and a sealant layer in this order, and the sealant layer contains a cyclic olefin resin and a low density polyethylene resin.
The multilayer film of the present invention is characterized by containing a predetermined amount of cyclic olefin resin in the sealant layer, thereby having excellent transparency, chemical resistance and moisture resistance, and can be easily cut linearly and cut. The effect is that the cut surface at the time is straight and excellent in mechanical properties such as tensile strength and piercing strength.
Hereinafter, each layer of the multilayer film and components constituting each layer will be described in detail.

[Base material]
Examples of the base material used include polyester resins such as polyethylene terephthalate resin (PET), polyethylene naphthalate resin (PEN), and polybutylene terephthalate resin (PBT), high-density polyethylene resin (HDPE), and polypropylene resin (PP). Olefin resin such as nylon-6, nylon-66, polyamide resin (PA), polycarbonate resin (PC), polyacrylonitrile resin (PAN), polyimide resin (PI), polyvinyl alcohol resin (PVA), polyvinylidene chloride resin (PVDC), ethylene-vinyl alcohol copolymer resin (EVOH), and other uniaxially stretched, biaxially stretched, and unstretched films can be used. Among these, polyethylene terephthalate resin (PET) is preferably used in that it is excellent in easy cutting properties and piercing strength.
In order to obtain easy cutability in a desired direction at the time of opening, it is desirable that the stretching ratio in the opening direction is larger than the stretching ratio in the direction orthogonal to the opening direction.

[Adhesive layer]
As an adhesive layer, in the case of extrusion lamination, for example, low density polyethylene resin (LDPE), linear low density polyethylene resin (LLDPE), ethylene-vinyl acetate copolymer resin (EVA), ethylene-methyl acrylate copolymer Resin (EMA), ethylene-ethyl acrylate copolymer resin (EEA), ethylene-acrylic acid copolymer resin (EEA), ethylene-methacrylic acid copolymer resin (EMAA) or ethylene-methyl methacrylate copolymer resin Resins such as (EMMA) can be used. Moreover, when using these resin, it is desirable to use together an anchor coat agent, such as organic titanium type, an isocyanate type, a polyethyleneimine type, or a polybutadiene type, for the reason of improving adhesiveness.

[Sealant layer]
The sealant layer is composed of a single layer or two or more layers, and contains a cyclic olefin resin and a low density polyethylene resin as essential components. When the sealant layer is a single layer, the sealant layer contains a cyclic olefin resin and a low density polyethylene resin. When the sealant layer is composed of two or more layers, a layer containing a cyclic olefin resin and a low density polyethylene resin and / or a linear low density polyethylene resin and / or a high density polyethylene resin (COC + PE layer), and a low density polyethylene resin A layer made of (LDPE layer) or a layer made of a linear low density polyethylene resin (LLDPE layer). In addition, when there are three or more sealant layers, the layer other than the COC + PE layer and the LDPE layer or the LLDPE layer is not particularly limited, but is a layer mainly composed of a low density polyethylene resin (LDPE layer ') or a linear low layer. It is preferable to include a layer mainly composed of high density polyethylene (LLDPE layer ′). Here, “main component” means that 60% by mass or more of the low density polyethylene resin or the linear low density polyethylene resin is contained with respect to the total mass of the layer.
When a sealant layer consists of two or more layers, arrangement | positioning of each layer which comprises a sealant layer is not specifically limited. However, when the multilayer film of the present invention is used as a packaging material for a product such as pharmaceuticals and foods and drinks, and the sealant layer is in contact with an object to be packaged, the sealant layer is configured. Of the layers to be formed, the layer opposite to the adhesive layer (the position farthest from the adhesive layer) (that is, the innermost layer of the packaging material) is preferably a layer that does not contain LLDPE. This is because LLDPE is produced using a transition metal, which is undesirable when ingested, as a catalyst. The layer constituting the side opposite to the adhesive layer (position farthest from the adhesive layer) is preferably an LDPE layer.

When there are two sealant layers, the preferred sealant layer configuration is substrate / adhesive layer / COC + PE layer / LDPE layer relative to the substrate and adhesive layer.
When the sealant layer has three layers, the preferred sealant layer is composed of a base material / adhesive layer / LDPE layer '/ COC + PE layer / LDEP layer or a base material / adhesive layer / LLDPE layer' / COC layer + PE layer / LDPE layer.

The manufacturing method of a sealant layer includes the shaping | molding process which shape | molds a resin composition into a film using an extruder. In the molding step, according to a generally used extrusion molding method, the above resin composition is melted in an extruder cylinder, and then the melted resin composition is drawn off from the extruder die in the air or The film is formed by cooling in water or the like. Although it does not specifically limit as an extruder used in a formation process, A single screw extruder, a twin screw extruder, or a screw extruder (types, such as a full flight and a double flight) etc. can be used.
In the sealant layer in the present invention, other components usually used as film components may be appropriately blended. Such components include antioxidants, secondary antioxidants, colorants, neutralizers, dispersants, light stabilizers, UV absorbers, lubricants, antistatic agents, antifogging agents, nucleating agents, pigments, Coloring agents, flame retardants, anti-blocking agents, and other various organic / inorganic compounds are exemplified. The compounding amounts of these components in the resin composition are appropriately adjusted according to the intended effect and the like.

  The above-described base material, adhesive layer, and sealant layer are bonded to each other by a general method used for producing a multilayer film to form a multilayer film. For example, methods such as a sand laminating method and a dry laminating method can be used.

The thickness of the substrate is preferably 10 to 50 μm. Moreover, it is preferable that the thickness of an contact bonding layer is 1-20 micrometers. Moreover, it is preferable that the thickness of a sealant layer is 20-80 micrometers.
The total thickness of the multilayer film is preferably 100 μm or less, and more preferably 90 μm or less.

[Cyclic olefin resin]
The cyclic olefin resin is not particularly limited as long as it contains a cyclic olefin component as a copolymerization component and is a polyolefin resin containing a cyclic olefin component in the main chain. For example, an addition polymer of a cyclic olefin or a hydrogenated product thereof, an addition copolymer of a cyclic olefin and an α-olefin, or a hydrogenated product thereof can be used.

  The cyclic olefin resin includes those obtained by grafting and / or copolymerizing an unsaturated compound having a polar group to the above polymer.

  Examples of the polar group include a carboxyl group, an acid anhydride group, an epoxy group, an amino group, an amide group, an ester group, a hydroxyl group, a sulfo group, a phosphono group, and a phosphino group. As unsaturated compounds having a polar group, (meth) acrylic acid, maleic acid, maleic anhydride, itaconic anhydride, glycidyl (meth) acrylate, alkyl (meth) acrylate (1 to 10 carbon atoms) ester, maleic acid Alkyl (C1-C10) ester, (meth) acrylamide, (meth) acrylic acid-2-hydroxyethyl, etc. can be mentioned. Of these, carboxyl group, acid anhydride group, epoxy group, amino group, amide group, ester group, hydroxyl group, sulfo group, phosphono group and phosphino group are preferably used.

  As the cyclic olefin resin, an addition copolymer of a cyclic olefin and an α-olefin or a hydrogenated product thereof is preferable.

  A commercially available resin can also be used as the cyclic olefin resin containing a cyclic olefin component as a copolymerization component. Examples of commercially available cyclic olefin-based resins include TOPAS (registered trademark) (Topas Advanced Polymers), Apel (registered trademark) (manufactured by Mitsui Chemicals), Zeonex (registered trademark) (manufactured by Nippon Zeon), Examples include ZEONOR (registered trademark) (manufactured by ZEON Corporation) and ARTON (registered trademark) (manufactured by JSR Corporation).

（式中、Ｒ^１〜Ｒ^１２は、それぞれ同一でも異なっていてもよく、水素原子、ハロゲン原子及び炭化水素基からなる群より選ばれるものであり、
Ｒ^９とＲ^１０、Ｒ^１１とＲ^１２は、一体化して２価の炭化水素基を形成してもよく、
Ｒ^９又はＲ^１０と、Ｒ^１１又はＲ^１２とは、互いに環を形成していてもよい。
また、ｎは０又は正の整数を示し、
ｎが２以上の場合には、Ｒ^５〜Ｒ^８はそれぞれの繰り返し単位の中で、それぞれ同一でも異なっていてもよい。） Particularly preferable examples of the addition copolymer of cyclic olefin and α-olefin include (1) an α-olefin component having 2 to 20 carbon atoms, and (2) a cyclic olefin component represented by the following general formula (I): Can be mentioned.

(Wherein R ^{1 to} R ¹² may be the same as or different from each other, and are selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group,
R ⁹ and R ¹⁰ , R ¹¹ and R ¹² may be integrated to form a divalent hydrocarbon group,
R ⁹ or R ¹⁰ and R ¹¹ or R ¹² may form a ring with each other.
N represents 0 or a positive integer;
When n is 2 or more, R ^{5 to} R ⁸ may be the same or different in each repeating unit. )

  The (1) α-olefin component having 2 to 20 carbon atoms will be described. The α-olefin having 2 to 20 carbon atoms is not particularly limited. For example, the thing similar to what is disclosed by Unexamined-Japanese-Patent No. 2007-302722 can be mentioned. These α-olefin components may be used alone or in combination of two or more. Of these, ethylene is most preferably used alone.

The cyclic olefin component represented by the above (2) general formula (I) will be described. R ^{1 to} R ¹² in the general formula (I) may be the same or different and are selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group.

Specific examples of R ^{1 to} R ⁸ include, for example, hydrogen atoms; halogen atoms such as fluorine, chlorine and bromine; lower alkyl groups such as methyl group, ethyl group, propyl group and butyl group. May be different from each other, may be partially different, or all may be the same.

Specific examples of R ^{9 to} R ¹² include, for example, a hydrogen atom; a halogen atom such as fluorine, chlorine and bromine; a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a hexyl group, and stearyl. Alkyl group such as cyclohexyl group; cycloalkyl group such as cyclohexyl group; substituted or unsubstituted aromatic hydrocarbon group such as phenyl group, tolyl group, ethylphenyl group, isopropylphenyl group, naphthyl group and anthryl group; benzyl group, phenethyl And an aralkyl group in which an aryl group is substituted with an alkyl group, and the like. These may be different from each other, may be partially different, or all may be the same.

Specific examples of the case where R ⁹ and R ¹⁰ or R ¹¹ and R ¹² are integrated to form a divalent hydrocarbon group include, for example, alkylidene groups such as an ethylidene group, a propylidene group, and an isopropylidene group. Can be mentioned.

When R ⁹ or R ¹⁰ and R ¹¹ or R ¹² form a ring with each other, the formed ring may be monocyclic or polycyclic, or may be a polycyclic ring having a bridge. , A ring having a double bond, or a ring composed of a combination of these rings may be used. Moreover, these rings may have a substituent such as a methyl group.

  Specific examples of the cyclic olefin component represented by the general formula (I) include those similar to those disclosed in JP-A-2007-302722.

  These cyclic olefin components may be used singly or in combination of two or more. Among these, it is preferable to use bicyclo [2.2.1] hept-2-ene (common name: norbornene) alone.

  The polymerization method of the above (1) α-olefin component having 2 to 20 carbon atoms and (2) the cyclic olefin component represented by the general formula (I) and the hydrogenation method of the obtained polymer are particularly limited. It can be performed according to a known method. Random copolymerization or block copolymerization may be used, but random copolymerization is preferred.

  The polymerization catalyst used is not particularly limited, and a cyclic olefin resin can be obtained by a known method using a conventionally known catalyst such as a Ziegler-Natta, metathesis, or metallocene catalyst.

  Next, other copolymerization components will be briefly described. In addition to the above (1) α-olefin component having 2 to 20 carbon atoms and (2) the cyclic olefin component represented by the general formula (I), the cyclic olefin-based resin is within a range not impairing the object of the present invention. You may contain the other copolymerizable unsaturated monomer component as needed.

  The unsaturated monomer that may be optionally copolymerized is not particularly limited, and examples thereof include hydrocarbon monomers containing two or more carbon-carbon double bonds in one molecule. Can be mentioned. Specific examples of the hydrocarbon-based monomer containing two or more carbon-carbon double bonds in one molecule include those similar to those disclosed in JP-A-2007-302722.

  When the sealant layer is a single layer, the content of the cyclic olefin resin in the sealant layer is preferably 30% by mass or more and less than 70% by mass with respect to the total mass of the sealant layer, and is 40% by mass or more and 60% by mass or less. More preferably. When the sealant layer includes two or more layers, the content of the cyclic olefin resin in the layer including the cyclic olefin resin and the polyethylene resin is 30% by mass or more and less than 70% by mass with respect to the total mass of the layer. Is preferable, and it is more preferable that it is 40 mass% or more and 60 mass% or less. When the content of the cyclic olefin resin is less than 30% by mass, there is a problem that the opening surface (cut surface) when opening by tearing by hand becomes corrugated and cannot be easily opened. If there is, there is a problem that the film cannot be cut linearly and wrinkles are easily generated during winding because the rigidity of the film is increased.

  The layer containing the cyclic olefin resin may contain components other than the cyclic olefin resin as long as the effects of the present invention are not impaired. Examples of other components include other resins, inorganic fillers, nucleating agents, pigments, antioxidants, stabilizers, plasticizers, lubricants, and mold release agents.

[Polyethylene resin]
As the polyethylene resin, a low density polyethylene resin having a density of 0.900 or more and less than 0.940 or a linear low density polyethylene resin and a high density polyethylene resin having a density of 0.930 or more can be used. When the sealant layer is a single layer, the content of the polyethylene resin in the sealant layer is preferably 30% by mass to 70% by mass, and more preferably 40% by mass to 60% by mass. Moreover, when a sealant layer contains two or more layers, it is preferable that content of the polyethylene resin in the layer containing cyclic olefin resin and polyethylene resin is 30 mass%-70 mass% with respect to the total mass of the said layer. 40 mass% to 60 mass% is more preferable.

Commercially available resins may be used as the low density polyethylene resin and the linear low density polyethylene resin. Examples of commercially available resins include Novatec (registered trademark) series (manufactured by Nippon Polyethylene), Sumikasen (registered trademark) (manufactured by Sumitomo Chemical), and the like.
Examples of the high-density polyethylene resin include Novatec (registered trademark) series (manufactured by Nippon Polyethylene), Hi-Zex (registered trademark) (manufactured by prime polymer), and the like.

[Packaging materials]
The packaging material of the present invention is formed by molding the multilayer film of the present invention. The molding method is not particularly limited, and a suitable molding method such as extrusion molding, blow molding, and vacuum molding can be appropriately used depending on the shape of the packaging material and the like. Since the multilayer film of the present invention has excellent transparency, it is easy to confirm the packaged object. Moreover, since it is excellent in moisture resistance and mechanical characteristics, the packaging material of this invention is suitable as a packaging material which preserve | saves the product which deteriorates with water vapor | steam etc. Furthermore, since the opening surface (cut surface) at the time of opening does not become corrugated, it is possible to suppress the object to be packaged such as powder and granules from adhering to the opening surface and remaining. Although it does not specifically limit as a to-be-packaged object of the packaging material of this invention, For example, a pharmaceutical, medical supplies, sanitary goods, food-drinks, etc. are mentioned. Moreover, since it is excellent also in heat insulation and heat resistance, it can be used also for the container etc. which contact a high temperature liquid (for example, hot water of 60 degreeC or more).

  When the multilayer film of the present invention is used as a packaging material, it is preferable that the sealant layer is present on the side in contact with the object to be packaged.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not limited to these Examples.

<Cyclic olefin resin>
The cyclic olefin resins used in the examples are as follows.
COC-1: Trade name “TOPAS 7010F-600”, manufactured by TOPAS Advanced Polymers COC-2: Trade name “TOPAS 8007F-500”, manufactured by TOPAS Advanced Polymers

<Polyethylene resin>
The polyethylene resins used in the examples are as follows.
Linear low density polyethylene (LLDPE): trade name “Novatech UF320”, Nippon Polyethylene Corporation low density polyethylene (LDPE): trade name “Novatech LF280”, Japan Polyethylene Corporation high density polyethylene (HDPE): trade name "Novatech HY530", manufactured by Nippon Polyethylene Corporation

<Base material>
The base materials used in the examples are as follows.
Polyethylene terephthalate (PET): Trade name “Toyobo Ester Film ET510”, Toyobo Co., Ltd. polypropylene (PP): Trade name “Noblen ANNM”, Tokyo Ink Co., Ltd.

  Using each of the above materials, each multilayer film having the composition shown in Table 1 was produced by the following method. Unless otherwise specified, the numerical values in Table 1 represent “parts by mass”, and the composition of each of the layers (A) to (C) constituting the sealant layer was 100 parts by mass in total.

(Method for producing sealant layer)
Using a three-layer inflation molding machine (manufactured by Tommy Machinery Co., Ltd.), a three-layer multilayer coextruded film (all layers) having a layer (B), a layer (A) sandwiching the layer (B), and a layer (C) (Thickness: 40 μm) was prepared and used as a sealant layer. The molding conditions of the multilayer coextruded film are as follows.
A multilayer coextruded film was prepared using a die (die diameter: 106 mm, lip clearance: 2.5 mm) and a screw (φ = 40 mm, L / D = 26). The cylinder temperature of the layers (A) and (C) of the multilayer coextruded film was set to 190 ° C., and the cylinder temperature of the layer (B) of the film was set to 210 ° C. Further, the die temperature was set to 190 ° C., the blow ratio was set to 2.0, the take-up speed was set to 12.5 m / min, and the screw rotation speed was set so as to be the thickness of each layer in Table 1.
In addition, when the said sealant layer comprises a packaging material, a packaging material is comprised so that a layer (A) may become an outer layer side and a layer (C) may become an inner layer side.

(Lamination method of sealant layer and substrate)
Using an extrusion laminating apparatus, an isocyanate anchor coating agent (EL-540, manufactured by Toyo Ink Co., Ltd.) is dried on one side of the film-like substrate described in Table 1 so that the thickness when dried is 0.5 μm. Application and drying were performed to form an anchor coat layer. Subsequently, low-density polyethylene (Novatech LC600A, manufactured by Nippon Polyethylene Co., Ltd.) was extruded onto the anchor coat layer at an extrusion temperature of 310 ° C. to form an extruded adhesive layer having a thickness of 17.5 μm. A multilayer film was prepared by laminating the sealant layer (A) on the adhesive layer so as to adhere.

  Each multilayer film manufactured by the above method was referred to as Example 1-8 and Comparative Example 1-3. In addition, a commercially available cellopoly (multilayer film obtained by laminating low-density polyethylene on 20 μm cellophane) was used as Comparative Example 4.

  Each of the above Examples and Comparative Examples were evaluated for each of the linear cut property, cut surface shape, piercing strength, tear strength, and haze.

[Linear cut property]
A trouser tear test was performed according to JIS K7128-1, and the distance from the end point of the tear and the center of the film (the distance indicated by the arrow in FIG. 1 below) was determined in four stages.
◎: Less than 1 mm from the center ○: Less than 2 mm from the center △: Less than 3 mm from the center ×: 4 mm or more from the center [Fig. 1]

[Cut surface shape]
An Elmendorf tear test was performed in accordance with JIS K7128-2, and the cut surface was determined in the following four stages.
◎: No waveform on cut surface ○: Slightly waveform on cut surface △: Slightly waveform on cut surface ×: Waveform on cut surface

[Puncture strength]
The puncture strength was measured according to JIS Z1707. The diameter of the needle was 1 mmφ, and the speed was 50 mm / min. The results are shown in Table 1.
The higher the piercing strength, the higher the resistance to piercing of the multilayer film surface. For example, when a multilayer film is used as a packaging material for packaging granular pharmaceutical products, it is necessary to prevent the packaged material from breaking through the packaging material and releasing it to the outside. It is possible to prevent the package from breaking through the packaging material.

[Tear strength]
The Elmendorf tear test was performed according to JIS K7128-2, and the tear strength in the longitudinal direction of the film was measured. The lower the tear strength, the lower the resistance to tearing of the film and the easier it can be torn (easy tearability). For example, when a multilayer film is used as a packaging material, it may be preferable that it can be easily opened, but if the tear strength is 0.5 N / sheet or less, it can be easily torn and opened by hand.

[Haze]
Haze was measured according to ISO 14782. The lower the haze, the higher the transparency of the film. For example, when a multilayer film is used as a packaging material, it may be preferable that the object to be packaged is easily visible. However, if the haze is 20% or less, the object to be packaged can be easily visually recognized.

Table 1 shows the results of the above evaluation items.
From the results of Table 1, in the examples containing the cyclic olefin resin in an amount specified by the present invention, good results were obtained for any of the above evaluation items. On the other hand, in Comparative Examples 1 and 2 in which the amount of the cyclic olefin resin is less than the amount specified in the present invention, the linear cut property and the easy tear property were inferior, and the cut surface was corrugated. Further, in Comparative Example 3 in which the amount of the cyclic olefin resin was larger than the amount specified in the present invention, although no waveform was seen on the cut surface, the result was inferior in the linear cut property.

Claims (6)

  A multilayer film in which a base material, an adhesive layer and a sealant layer are laminated in this order, wherein the sealant layer has a layer containing a cyclic olefin resin and a polyethylene resin, and the cyclic olefin resin in the layer containing the cyclic olefin resin and the polyethylene resin Is a multilayer film in which the sealant layer contains a low-density polyethylene resin.   The sealant layer includes two or more layers including a layer containing a cyclic olefin resin and a polyethylene resin and a layer made of a low density polyethylene resin, and the layer disposed at the position farthest from the adhesive layer is a linear low The multilayer film of Claim 1 which is a layer which does not contain a density polyethylene.   The sealant layer includes a layer (A) mainly composed of a low-density polyethylene resin or a linear low-density polyethylene resin, a layer (B) containing a cyclic olefin resin and a polyethylene resin, and a layer composed of a low-density polyethylene resin ( The multilayer film of Claim 1 or 2 which is a layer which laminated | stacked C) from the said adhesive layer side in order of (A) / (B) / (C).   Content of cyclic olefin resin in the layer containing the said cyclic olefin resin and polyethylene resin is 40 mass% or more and 60 mass% or less with respect to the gross mass of the layer containing the said cyclic olefin resin and polyethylene resin. 4. The multilayer film according to any one of 3.   The multilayer film as described in any one of Claims 1-4 whose total thickness of a film is 100 micrometers or less.   The packaging material formed by shape | molding the multilayer film as described in any one of Claims 1-5.