Multilayer film

Abstract

To provide a laminated film having higher heat resistance and high reusability than conventional films. [Solution] A laminated film (1) comprising a first resin layer (11) and a second resin layer (12), the first resin layer (11) and the second resin layer (12) containing the same type of polyolefin resin, and when dynamic viscoelasticity measurement is performed on the second resin layer (12) to measure the elastic modulus E'(100) at 100°C and the elastic modulus E'(110) at 110°C at a vibration frequency of 1 Hz, the value of E'(110) / E'(100) is 0.2 or more.

Description

Technical Field

[0001] The present invention relates to a laminated film. This application claims priority based on Japanese Patent Application No. 2020-060062 filed in Japan on March 30, 2020, and Japanese Patent Application No. 2020-209113 filed in Japan on December 17, 2020, the contents of which are incorporated herein by reference.

Background Art

[0002] A laminated film formed by laminating a plurality of resin layers is widely used as a material for packages. Typical laminated films include at least a sealant layer provided for heat-sealing with an object to be sealed, and an outer layer provided on the side opposite to the sealant layer side.

[0003] On the other hand, such laminated films for packaging applications are produced and consumed in large quantities every day around the world due to their high convenience, and a large amount of waste is generated after use. The generation of waste is an important issue to be solved from the perspective of improving the global environment, and in recent years, in addition to reducing the amount of waste generated, methods for recycling waste have been actively studied.

[0004] For example, if the main constituent materials of the plurality of resin layers in the laminated film are of the same type, there is no need to separate each resin layer and recycle them separately, and the entire laminated film can be easily recycled, so the usefulness is increased. As such a laminated film, for example, a polyethylene laminate for packaging materials including at least a stretched polyethylene film, an adhesive layer, and a heat-sealable polyethylene layer, wherein the adhesive layer contains a solventless adhesive, is disclosed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Generally, when heat-sealing a resin film, it is often a problem that the resin film easily adheres to the heating plate in the heat-sealing apparatus. This is because the heat resistance of the resin film is insufficient. In contrast, it is not certain whether the laminated film described in Patent Document 1 has sufficient heat resistance.

[0007] In view of the above circumstances, the present invention has been made, and an object thereof is to provide a laminated film having higher heat resistance and higher recyclability than conventional ones.

Means for Solving the Problems

[0008] To solve the above problems, the present invention adopts the following configuration. [1]. A laminated film comprising a first resin layer and a second resin layer, wherein the first resin layer and the second resin layer contain the same type of polyolefin-based resin, and for the second resin layer, when dynamic viscoelastic measurement is performed and the elastic modulus E'(100) at 100 °C and the elastic modulus E'(110) at 110 °C are measured when the vibration frequency is 1 Hz, the value of E'(110) / E'(100) is 0.2 or more. [2]. The laminated film according to [1], wherein the gel fraction of the laminated film is 30% or more. [3]. The laminated film according to [1] or [2], wherein the laminated film is irradiated with an electron beam under the condition of an absorbed dose of 20 to 300 kGy. [4]. The laminated film according to any one of [1] to [3], wherein when thermomechanical analysis is performed on the laminated film, the temperature at which a displacement of 2000 μm is shown is 120 °C or higher.

[0009] [5]. The laminated film further includes a third resin layer between the first resin layer and the second resin layer, and the first resin layer, the second resin layer, and the third resin layer contain the same type of polyolefin resin. The laminated film according to any one of [1] to [4]. [6]. The third resin layer is composed of three or more layers, and at least one of them contains the polyolefin resin, ethylene-vinyl alcohol copolymer, and ethylene-vinyl alcohol-vinyl acetate copolymer. The polyolefin resin does not correspond to any of ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol-vinyl acetate copolymer. The laminated film according to [5]. [7]. The polyolefin resin is a polyethylene resin. The laminated film according to any one of [1] to [6]. [8]. When the tip of a needle with a tip curvature radius of 0.5 mm is pushed vertically into the laminated film at a speed of 500 mm / min, the load applied to the needle at the moment the needle penetrates the laminated film is 7 N or more. The laminated film according to any one of [1] to [7]. [9]. The value of E’(110) / E’(100) is 0.5 or more. The laminated film according to [1].

[10] . The second resin layer contains high-density polyethylene. The laminated film according to [1] or [9]. [Effect of the Invention]

[0010] According to the present invention, a laminated film having higher heat resistance and higher recyclability than conventional ones is provided. [Brief Description of the Drawings]

[0011]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0012] <<Laminated Film>> In a laminated film according to an embodiment of the present invention, it includes a first resin layer and a second resin layer. The first resin layer and the second resin layer contain the same type of polyolefin resin. For the second resin layer, when performing dynamic viscoelasticity measurement (DMA) and measuring the elastic modulus E’(100) at 100 °C and the elastic modulus E’(110) at 110 °C when the vibration frequency is 1 Hz, the value of E’(110) / E’(100) (in this specification, it may be abbreviated as "E’(110) / E’(100) value") is 0.2 or more. In this specification, "elastic modulus" means "storage elastic modulus" unless otherwise specified.

[0013] In the laminated film of this embodiment, since the first resin layer and the second resin layer contain the same type of polyolefin resin, the recyclability is high. Also, in the laminated film of this embodiment, since the E’(110) / E’(100) value of the second resin layer is 0.2 or more, the heat resistance of the second resin layer is high, so it has higher heat resistance than a laminated film containing a normal polyolefin resin. When heat-sealing such a laminated film with high heat resistance, the adhesion of the laminated film (especially the second resin layer) to the heating plate in the heat-sealing device is suppressed.

[0014] <First Resin Layer> The first resin layer contains a polyolefin resin. The polyolefin resin contained in the first resin layer is not particularly limited as long as it has a structural unit derived from an olefin, and it may be a homopolymer of one type of olefin or a copolymer of two or more types of olefins.

[0015] Examples of the homopolymer of the olefin include polyethylene such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), metallocene-catalyzed linear low density polyethylene (mLLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE); and polypropylene (homopolypropylene). Both linear low density polyethylene (LLDPE) and metallocene-catalyzed linear low density polyethylene (mLLDPE) are types of low density polyethylene (LDPE).

[0016] The classification of polyethylene by its density was defined, for example, in the former JIS K 6748:1995. In this specification, polyethylene is classified by its density according to this definition. That is, in this specification, low density polyethylene (LDPE) means polyethylene having a density of 0.91 g / cm 3 or more and less than 0.93 g / cm 3 Further, medium density polyethylene (MDPE) means polyethylene having a density of 0.93 g / cm 3 or more and less than 0.942 g / cm 3 Further, high density polyethylene (HDPE) means polyethylene having a density of 0.942 g / cm 3 or more.

[0017] Examples of the copolymer of the olefin include an ethylene copolymer having at least a structural unit derived from ethylene and a propylene copolymer having at least a structural unit derived from propylene.

[0018] ​​The ethylene-based copolymer has a structural unit derived from ethylene and a structural unit derived from a monomer other than ethylene. However, among the olefin copolymers having a structural unit derived from ethylene and a structural unit derived from propylene, a copolymer in which the number of structural units derived from propylene is larger than the number of structural units derived from ethylene is classified as a propylene-based copolymer for convenience.

[0019] Examples of the ethylene-based copolymer include ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol copolymer (EVOH), ethylene-vinyl alcohol-vinyl acetate copolymer (also known as: partially saponified ethylene-vinyl acetate copolymer, may be referred to as "partially saponified EVA" in this specification), ethylene-methyl acrylate copolymer (EMA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ionomer (ION), and the like. Examples of the ionomer include a resin in which a copolymer of ethylene and a small amount of acrylic acid or methacrylic acid has an ion crosslinked structure by salt formation between the acid part therein and a metal ion.

[0020] The propylene-based copolymer has a structural unit derived from propylene and a structural unit derived from a monomer other than propylene. Examples of the propylene-based copolymer include propylene-ethylene random copolymer (also known as: polypropylene random copolymer (rPP)), propylene-ethylene block copolymer (also known as: polypropylene block copolymer (bPP)), and the like.

[0021] The polyolefin resin contained in the first resin layer may be only one kind or two or more kinds. When there are two or more kinds, their combinations and ratios can be arbitrarily selected according to the purpose.

[0022] The polyolefin resin contained in the first resin layer is preferably a polyethylene resin, and more preferably a low-density polyethylene resin.

[0023] The first resin layer may contain other components in addition to the polyolefin resin as long as the effects of the present invention are not impaired. The other components may be either a resin component (which may be referred to as "other resin component" in this specification) or a non-resin component (which may be referred to as "other non-resin component" in this specification).

[0024] The other resin component is not particularly limited as long as it is a resin other than the polyolefin resin.

[0025] Examples of the other non-resin components include additives known in the art. Examples of the additives include an anti-fogging agent, an anti-blocking agent, an antioxidant, an antistatic agent, a nucleating agent, inorganic particles, a viscosity reducer, a thickener, a heat stabilizer, a lubricant, an infrared absorber, an ultraviolet absorber, and the like.

[0026] The other components contained in the first resin layer may be only one kind or two or more kinds. In the case of two or more kinds, their combinations and ratios can be arbitrarily selected according to the purpose.

[0027] In the first resin layer, the ratio of the content of the polyolefin resin (the total content of the polyolefin resin of the same type as the polyolefin resin contained in the second resin layer and the polyolefin resin of a different type from the polyolefin resin contained in the second resin layer) to the total mass of the first resin layer is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, and may be, for example, either 97 to 100% by mass or 99 to 100% by mass. When the ratio is equal to or higher than the lower limit value, the effects of the first resin layer containing the polyolefin resin can be obtained more significantly. The ratio is usually the same as the ratio of the content (parts by mass) of the polyolefin resin to the total content (parts by mass) of the components that do not vaporize at room temperature in the first resin composition described later (the total content of the polyolefin resin of the same type as the polyolefin resin contained in the second resin layer and the polyolefin resin not of the same type as the polyolefin resin contained in the second resin layer).

[0028] The first resin layer and the second resin layer contain the same type of polyolefin resin. In this embodiment, not limited to the case of polyolefin resins, "resins of the same type" means that when comparing resins having a common structural unit, in either resin, the ratio of the amount (moles) of the common structural unit to the total amount (moles) of the structural units is 20 mol% or more. For example, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene-catalyzed linear low-density polyethylene (mLLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene-methyl acrylate copolymer (EMA resin), ethylene-methyl methacrylate copolymer (EMMA resin), ethylene-vinyl alcohol copolymer (EVOH), ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol-vinyl acetate copolymer (partially saponified EVA), etc. are all considered to be of the same type because the ratio of the amount (moles) of the structural unit derived from ethylene to the total amount (moles) of the structural units is 20 mol% or more. On the other hand, for example, among propylene-ethylene random copolymers and propylene-ethylene block copolymers, those in which the ratio of the amount (moles) of the structural unit derived from ethylene to the total amount (moles) of the structural units is less than 20 mol% are considered not to be of the same type as the above-mentioned low-density polyethylene, etc. In this embodiment, for resins of the same type, in either resin, the ratio of the amount (moles) of the common structural unit to the total amount (moles) of the structural units is preferably 30 mol% or more, more preferably 40 mol% or more, still more preferably 50 mol% or more, and may be any of, for example, 60 mol% or more, 70 mol% or more, and 80 mol% or more.

[0029] In the first resin layer, the ratio of the content of the polyolefin resin of the same type as the polyolefin resin contained in the second resin layer to the total mass of the first resin layer is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and may be, for example, either 95 to 100% by mass or 99 to 100% by mass. When the ratio is at least the lower limit value, the recyclability of the laminated film becomes higher.

[0030] When the first resin layer contains low-density polyethylene, in the first resin layer, the ratio of the content of low-density polyethylene to the total mass of the first resin layer is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass. When the ratio is at least the lower limit value, the effect obtained by the first resin layer containing low-density polyethylene becomes higher.

[0031] In this specification, "normal temperature" means a temperature that is not particularly cooled or heated, that is, an ordinary temperature, and examples thereof include a temperature of 15 to 25°C.

[0032] The first resin layer may be composed of one layer (single layer) or may be composed of two or more layers. When the first resin layer is composed of a plurality of layers, these plurality of layers may be the same as or different from each other, and the combination of these plurality of layers is not particularly limited as long as the effects of the present invention are not impaired.

[0033] In this specification, not only in the case of the first resin layer, "the plurality of layers may be the same as or different from each other" means that "all the layers may be the same, all the layers may be different, or only some of the layers may be the same", and further, "the plurality of layers are different from each other" means that "at least one of the constituent materials and thicknesses of each layer is different from each other".

[0034] The thickness of the first resin layer can be arbitrarily set according to the use of the laminated film and is not particularly limited. The thickness of the first resin layer is usually preferably 5 to 100 μm, more preferably 10 to 80 μm, and even more preferably 20 to 60 μm. When the thickness of the first resin layer is at least the lower limit value, the strength of the first resin layer is further improved, and the effect of the laminated film having the first resin layer is more significantly obtained. When the thickness of the first resin layer is at most the upper limit value, it is possible to suppress an excessive thickness. When the first resin layer is composed of a plurality of layers, the total thickness of these plurality of layers may be set to the thickness of the above-described preferred first resin layer.

[0035] The first resin layer is preferably an unstretched layer (film). When the first resin layer is an unstretched layer, the moldability of the laminated film is improved.

[0036] The first resin layer is suitable as, for example, a sealant layer.

[0037] <The second resin layer> The second resin layer contains a polyolefin resin of the same type as the polyolefin resin contained in the first resin layer. The polyolefin resin of the same type contained in the second resin layer may be only one type or two or more types. When there are two or more types, their combinations and ratios can be arbitrarily selected according to the purpose.

[0038] The polyolefin resin of the same type contained in the second resin layer is preferably a polyethylene resin, and more preferably high-density polyethylene. For the second resin layer containing a polyethylene resin, particularly high-density polyethylene, it is easier to make its E’(110) / E’(100) value 0.2 or more. That is, it is preferable that both the first resin layer and the second resin layer contain a polyethylene resin, and it is more preferable that the second resin layer contains high-density polyethylene.

[0039] The second resin layer may contain other components in addition to the polyolefin resin of the same type as the polyolefin resin contained in the first resin layer, as long as the effects of the present invention are not impaired. The other components in the second resin layer may be either a resin component (which may be referred to as "other resin component" in this specification) or a non-resin component (which may be referred to as "other non-resin component" in this specification).

[0040] The other resin component in the second resin layer is not particularly limited as long as it is a resin other than the polyolefin resin of the same type as the polyolefin resin contained in the first resin layer. Examples of the other resin component in the second resin layer include a polyolefin resin that is not of the same type as the polyolefin resin contained in the first resin layer and a resin other than the polyolefin resin. Examples of the polyolefin resin that is not of the same type as the polyolefin resin contained in the first resin layer are the same as those listed above as the polyolefin resin contained in the first resin layer.

[0041] Examples of the non-resin component in the second resin layer are the same as those in the first resin layer.

[0042] The other components contained in the second resin layer may be only one type or two or more types. When there are two or more types, their combinations and ratios can be arbitrarily selected according to the purpose.

[0043] In the second resin layer, the proportion of the content of the polyolefin resin (the total content of the polyolefin resin of the same type as the polyolefin resin contained in the first resin layer and the polyolefin resin that is not of the same type as the polyolefin resin contained in the first resin layer) with respect to the total mass of the second resin layer is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, and may be, for example, either 97 to 100% by mass or 99 to 100% by mass. When the proportion is equal to or higher than the lower limit value, the effect due to the second resin layer containing the polyolefin resin can be obtained more significantly. The ratio is usually the same as the ratio of the content (parts by mass) of the polyolefin resin (the total content of the polyolefin resin of the same type as the polyolefin resin contained in the first resin layer and the polyolefin resin not of the same type as the polyolefin resin contained in the first resin layer) to the total content (parts by mass) of the components that do not vaporize at room temperature in the second resin composition described later.

[0044] In the second resin layer, the ratio of the content of the polyolefin resin of the same type as the polyolefin resin contained in the first resin layer to the total mass of the second resin layer is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and may be, for example, either 95 to 100% by mass or 99 to 100% by mass. When the ratio is at least the lower limit value, the recyclability of the laminated film is higher.

[0045] When the second resin layer contains high-density polyethylene, in the second resin layer, the ratio of the content of high-density polyethylene to the total mass of the second resin layer is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass. When the ratio is at least the lower limit value, the heat resistance of the second resin layer is significantly improved.

[0046] The second resin layer may be irradiated with an electron beam. That is, the laminated film may be irradiated with an electron beam, and it is preferably irradiated with an electron beam from the second resin layer side. For example, even if the second resin layer does not contain high-density polyethylene, by irradiating the second resin layer with an electron beam, its E’(110) / E’(100) value can be easily made 0.2 or more. The reason is presumably that the crosslink density of the resin in the second resin layer increases due to the electron beam irradiation.

[0047] As a preferred example of the second resin layer irradiated with an electron beam, there is, for example, a second resin layer not irradiated with an electron beam containing low-density polyethylene (in this specification, in order to distinguish the second resin layer in this case from that after electron beam irradiation, it may be referred to as the "unirradiated second resin layer") that has been irradiated with an electron beam. That is, as a preferred example of the laminated film irradiated with an electron beam, there is, for example, the laminated film provided with a second resin layer containing low-density polyethylene as the unirradiated second resin layer (in this specification, in order to distinguish the laminated film in this case from that after electron beam irradiation, it may be referred to as the "unirradiated laminated film") that has been irradiated with an electron beam.

[0048] In the unirradiated second resin layer, the ratio of the content of low-density polyethylene to the total mass of the unirradiated second resin layer is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass. When the ratio is at least the lower limit value, the effect of electron beam irradiation can be obtained more significantly.

[0049] The electron beam irradiation on the unirradiated second resin layer or the unirradiated laminated film is preferably performed under the condition of an absorbed dose of 20 to 300 kGy. When the absorbed dose is at least the lower limit value, the effect of electron beam irradiation can be obtained more significantly. When the absorbed dose is at most the upper limit value, excessive crosslinking of the resin in the second resin layer is suppressed. That is, as a preferred example of the laminated film irradiated with an electron beam, there is one irradiated with an electron beam under the condition of an absorbed dose of 20 to 300 kGy.

[0050] The acceleration voltage during the electron beam irradiation on the unirradiated second resin layer or the unirradiated laminated film is preferably 100 to 300 kV, more preferably 120 to 280 kV, and even more preferably 140 to 260 kV. When the acceleration voltage is at least the lower limit value, the effect of electron beam irradiation can be obtained more significantly. When the acceleration voltage is at most the upper limit value, excessive crosslinking of the resin in the second resin layer is suppressed.

[0051] The laminated film increases, for example, the gel fraction by electron beam irradiation. That is, the gel fraction of the laminated film is larger than that of the non-irradiated laminated film. The gel fraction of the laminated film is preferably 30% or more, and may be, for example, any of 30 to 90%, 32 to 78%, and 34 to 76%. Such a laminated film has more preferable heat resistance as a laminated film including the second resin layer having the above-described E’(110) / E’(100) value.

[0052] The gel fraction of the laminated film can be measured in accordance with JIS K 6769. That is, the laminated film is immersed in an organic solvent such as xylene, and after drying the insoluble matter remaining without dissolution, its mass is determined, and the gel fraction can be calculated from the mass of the laminated film before dissolution and the mass of the insoluble matter derived from the laminated film after drying. More specifically, for example, X g of the laminated film is wrapped with a stainless steel wire mesh of Y g, immersed in a heated organic solvent, and the insoluble matter derived from the laminated film is taken out of the organic solvent together with the stainless steel wire mesh. Next, the stainless steel wire mesh wrapping the insoluble matter is vacuum dried, and the total mass (Z g) of the insoluble matter and the stainless steel wire mesh after drying is measured. The gel fraction of the laminated film is calculated from the following formula (1). Gel fraction of laminated film (mass %) = (Z - Y) / X × 100 (1)

[0053] The laminated film changes, for example, characteristics during thermomechanical analysis by electron beam irradiation. For example, when thermomechanical analysis is performed on the laminated film, the temperature at which a displacement of 2000 μm is shown (which may be abbreviated as “2000 μm displacement temperature” in this specification) is preferably 120°C or higher, and may be, for example, any of 125 to 200°C and 130 to 195°C. Such a laminated film has more preferable heat resistance as a laminated film including the second resin layer having the above-described E’(110) / E’(100) value.

[0054] For example, when performing thermomechanical analysis on a laminated film, it is preferable that the displacement at a temperature of 100°C is 500 μm or less. For example, it may be either 50 to 490 μm or 100 to 480 μm or less. Such a laminated film, as a laminated film provided with the second resin layer having the above-described E’(110) / E’(100) value, has more preferable heat resistance.

[0055] The thermomechanical analysis of the laminated film can be performed, for example, in accordance with JIS K 7196, by a method of measuring the thermal expansion amount of the sample from the difference in the thermal expansion amounts of a standard sample and the target sample when the temperature is raised at a constant rate.

[0056] The second resin layer may be composed of one layer (single layer) or may be composed of two or more layers. When the second resin layer is composed of a plurality of layers, these plurality of layers may be the same as or different from each other, and the combination of these plurality of layers is not particularly limited as long as the effects of the present invention are not impaired.

[0057] The thickness of the second resin layer can be arbitrarily set according to the use of the laminated film and is not particularly limited. The thickness of the second resin layer is usually preferably 5 to 100 μm, more preferably 10 to 80 μm, and even more preferably 20 to 60 μm. When the thickness of the second resin layer is equal to or greater than the lower limit value, the strength of the second resin layer is further improved, and the effect due to the laminated film being provided with the second resin layer can be obtained more significantly. When the thickness of the second resin layer is equal to or less than the upper limit value, it is possible to suppress an excessive thickness. When the second resin layer is composed of a plurality of layers, it is preferable that the total thickness of these plurality of layers is the same as the preferable thickness of the second resin layer described above.

[0058] In the laminated film, the ratio of [thickness of the first resin layer] / [thickness of the second resin layer] (thickness ratio) is not particularly limited, but it is preferably 0.7 to 1.3 regardless of the presence or absence of the third resin layer described later. When the thickness ratio is within such a range, the effects obtained by the laminated film having the first resin layer and the effects obtained by having the second resin layer can be obtained in a more balanced manner.

[0059] Regarding the second resin layer, dynamic viscoelasticity measurement (DMA: Dynamic Mechanical Analysis) was performed. When measuring the elastic modulus E'(100) at 100°C when the vibration frequency is 1 Hz and the elastic modulus E'(110) at 110°C when the vibration frequency is 1 Hz, the E'(110) / E'(100) value is 0.2 or more. At this time, as the second resin layer for which dynamic viscoelasticity measurement is performed, that is, as a test piece of the second resin layer, those having a width of 1 cm and a length of 5 cm or more can be mentioned. Using such a test piece, the test piece is installed so that the length of the measurement target part for performing the dynamic viscoelasticity measurement becomes 2 cm, and it is preferable to perform the dynamic viscoelasticity measurement by heating the test piece at a heating rate of 5°C / min. By setting such conditions, the elastic modulus E'(100) and the elastic modulus E'(110) can be measured with higher accuracy.

[0060] In terms of the heat resistance of the second resin layer and the laminated film being higher, the E'(110) / E'(100) value of the second resin layer is preferably 0.24 or more, and for example, it may be any of 0.3 or more, 0.4 or more, 0.5 or more, and 0.6 or more.

[0061] The upper limit value of the E'(110) / E'(100) value of the second resin layer is not particularly limited. For example, a second resin layer with an E'(110) / E'(100) value of 0.9 or less can be more easily realized.

[0062] The E’(110) / E’(100) value of the second resin layer can be appropriately adjusted within a range set by arbitrarily combining any of the above lower limit values and upper limit values. For example, in one embodiment, the E’(110) / E’(100) value of the second resin layer is preferably 0.2 to 0.9, more preferably 0.24 to 0.9, and may be, for example, any of 0.3 to 0.9, 0.4 to 0.9, 0.5 to 0.9, and 0.6 to 0.9.

[0063] The E’(110) / E’(100) value of the second resin layer containing high-density polyethylene tends to be larger. For example, a second resin layer with an E’(110) / E’(100) value of 0.5 or more can be more easily realized by the second resin layer containing high-density polyethylene.

[0064] The E’(100) of the second resin layer is not particularly limited as long as the conditions of the above E’(110) / E’(100) value are satisfied. For example, the E’(100) of the second resin layer may be 1.6×10 7 ~2×10 8 Pa.

[0065] The E’(110) of the second resin layer is not particularly limited as long as the conditions of the above E’(110) / E’(100) value are satisfied. For example, the E’(110) of the second resin layer may be 1.5×10 7 ~2.2×10 8 Pa.

[0066] The second resin layer is preferably an unstretched layer (film). When the second resin layer is an unstretched layer, the moldability of the laminated film is improved.

[0067] Since the second resin layer has heat resistance, it is suitable, for example, as an outer layer (the outermost layer on the side opposite to the sealant layer side).

[0068] <The third resin layer> The laminated film may further include a third resin layer other than these between the first resin layer and the second resin layer. The third resin layer contains a polyolefin resin included in the first resin layer and the second resin layer, and the same type of polyolefin resin. That is, in the laminated film provided with the third resin layer, the first resin layer, the second resin layer, and the third resin layer contain the same type of polyolefin resin.

[0069] In the present embodiment, not limited to the case of polyolefin resins, the "same type of resin" means that when comparing resins having a common structural unit, in both resins, the ratio of the amount (mol) of the common structural unit to the total amount (mol) of the structural units is 20 mol% or more. For example, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene-catalyzed linear low-density polyethylene (mLLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene-methyl acrylate copolymer (EMA resin), ethylene-methyl methacrylate copolymer (EMMA resin), ethylene-vinyl alcohol copolymer (EVOH), ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol-vinyl acetate copolymer (partially saponified EVA), etc. are all considered to be of the same type because the ratio of the amount (mol) of the structural unit derived from ethylene to the total amount (mol) of the structural units is 20 mol% or more. On the other hand, for example, among propylene-ethylene random copolymers and propylene-ethylene block copolymers, those in which the ratio of the amount (mol) of the structural unit derived from ethylene to the total amount (mol) of the structural units is less than 20 mol% are considered not to be of the same type as the above-mentioned low-density polyethylene, etc. In the present embodiment, for the same type of resin, in both resins, the ratio of the amount (mol) of the common structural unit to the total amount (mol) of the structural units is preferably 30 mol% or more, more preferably 40 mol% or more, still more preferably 50 mol% or more, and may be any one of, for example, 60 mol% or more, 70 mol% or more, and 80 mol% or more. The laminated film provided with the third resin layer has the effects due to the presence of the third resin layer and has high reusability.

[0070] The same polyolefin resin contained in the third resin layer may be only one kind or two or more kinds. When there are two or more kinds, their combinations and ratios can be arbitrarily selected according to the purpose.

[0071] The same polyolefin resin contained in the third resin layer is preferably a polyethylene resin. That is, it is preferable that the first resin layer, the second resin layer, and the third resin layer all contain a polyethylene resin.

[0072] The third resin layer may contain other components in addition to the same polyolefin resin as the polyolefin resin contained in the first resin layer and the second resin layer, as long as the effects of the present invention are not impaired. The other components in the third resin layer may be either a resin component (which may be referred to as "other resin component" in this specification) or a non-resin component (which may be referred to as "other non-resin component" in this specification).

[0073] The other resin component in the third resin layer is not particularly limited as long as it is a resin other than the same polyolefin resin as the polyolefin resin contained in the first resin layer and the second resin layer. Examples of the other resin component in the third resin layer include a polyolefin resin that is not of the same type as the polyolefin resin contained in the first resin layer and the second resin layer, and a resin other than the polyolefin resin.

[0074] Examples of the polyolefin resin used in the third resin layer (contained in the third resin layer) include elastomer components such as α-olefin copolymers; ethylene-vinyl alcohol copolymers (EVOH); ethylene-vinyl alcohol-vinyl acetate copolymers (partially saponified EVA). A laminated film provided with a third resin layer containing an elastomer has high pinhole resistance and high strength even if it does not contain a polyamide such as nylon. A laminated film provided with a third resin layer containing EVOH has oxygen barrier properties.

[0075] Examples of polyolefin resins that are not of the same type as the polyolefin resins contained in the first resin layer and the second resin layer include those similar to the polyolefin resins listed above as the polyolefin resins contained in the first resin layer; and elastomers such as α-olefin copolymers. A laminated film provided with a third resin layer containing the elastomer has high pinhole resistance and high strength even if it does not contain a polyamide such as nylon.

[0076] Examples of resins other than polyolefin resins in the third resin layer include elastomers such as styrene-ethylene·butylene-ethylene block copolymers. A laminated film provided with a third resin layer containing the elastomer has high pinhole resistance and high strength even if it does not contain a polyamide such as nylon.

[0077] Examples of the non-resin components in the third resin layer include those similar to the non-resin components in the first resin layer.

[0078] The other components contained in the third resin layer may be only one type or two or more types. When there are two or more types, their combinations and ratios can be arbitrarily selected according to the purpose.

[0079] In the third resin layer, the proportion of the content of the polyolefin resin (the total content of the polyolefin resin of the same type as the polyolefin resin contained in the first resin layer and the second resin layer and the polyolefin resin not of the same type as the polyolefin resin contained in the first resin layer and the second resin layer) with respect to the total mass of the third resin layer is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, and may be, for example, either 97 to 100% by mass or 99 to 100% by mass. When the proportion is equal to or higher than the lower limit value, the effect due to the third resin layer containing the polyolefin resin can be obtained more remarkably. The ratio is usually the same as the ratio of the content (parts by mass) of the polyolefin resin (the total content of the polyolefin resin of the same type as the polyolefin resin contained in the first resin layer and the second resin layer and the polyolefin resin not of the same type as the polyolefin resin contained in the first resin layer and the second resin layer) to the total content (parts by mass) of the components that do not vaporize at room temperature in the third resin composition described later.

[0080] In the third resin layer, the ratio of the content of the polyolefin resin of the same type as the polyolefin resin contained in the first resin layer and the second resin layer to the total mass of the third resin layer is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and may be, for example, either 95 to 100% by mass or 99 to 100% by mass. When the ratio is equal to or higher than the lower limit value, the recyclability of the laminated film becomes higher.

[0081] The third resin layer may be composed of one layer (single layer) or may be composed of two or more layers. When the third resin layer is composed of a plurality of layers, these plurality of layers may be the same as or different from each other, and the combination of these plurality of layers is not particularly limited as long as the effects of the present invention are not impaired. In the third resin layer composed of a plurality of layers, all layers contain a polyolefin resin of the same type as the polyolefin resin contained in the first resin layer and the second resin layer.

[0082] The thickness of the third resin layer can be arbitrarily set according to the use of the laminated film and is not particularly limited. The thickness of the third resin layer is usually preferably 15 to 200 μm, more preferably 30 to 160 μm, and even more preferably 50 to 120 μm. When the thickness of the third resin layer is equal to or higher than the lower limit value, the strength of the third resin layer is further improved, and the effect of the laminated film having the third resin layer is more significantly obtained. When the thickness of the third resin layer is equal to or lower than the upper limit value, it is possible to suppress an excessive thickness. When the third resin layer is composed of a plurality of layers, the total thickness of these plurality of layers may be set to be the thickness of the above-mentioned preferable third resin layer.

[0083] When the laminated film includes a third resin layer, the ratio of the thickness of the third resin layer to the thickness of the laminated film is not particularly limited, but is preferably 50 to 70%. When the ratio is equal to or greater than the lower limit value, the effect obtained by the laminated film including the third resin layer becomes higher. When the ratio is equal to or less than the upper limit value, the effect obtained by the laminated film including the first resin layer and the second resin layer becomes higher.

[0084] When the laminated film includes a third resin layer, the ratio of the total thickness of the first resin layer and the second resin layer to the thickness of the laminated film is not particularly limited, but is preferably 30 to 50%. When the ratio is equal to or greater than the lower limit value, the effect obtained by the laminated film including the first resin layer and the second resin layer becomes higher. When the ratio is equal to or less than the upper limit value, the effect obtained by the laminated film including the third resin layer becomes higher.

[0085] The third resin layer is preferably an unstretched layer (film). When the third resin layer is an unstretched layer, the moldability of the laminated film is improved.

[0086] The third resin layer is suitable as an intermediate layer such as a pinhole resistant layer or an oxygen barrier layer, for example.

[0087] Even if the laminated film does not contain a polyamide such as nylon, it has high pinhole resistance and high strength. For example, when the tip of a needle with a tip curvature radius of 0.5 mm is pushed vertically into the laminated film at a speed of 500 mm / min, and the load applied to the needle at the moment when the needle penetrates the laminated film is defined as the piercing strength (N), it can be said that the higher this piercing strength, the higher the pinhole resistance of the laminated film. Examples of the needle include those made of stainless steel.

[0088] The puncture strength of the laminated film is preferably 7 N or more, and may be, for example, either 8 N or more and 10 N or more. The upper limit value of the puncture strength is not particularly limited. For example, a laminated film having a puncture strength of 12 N or less can be more easily realized.

[0089] A laminated film having a high puncture strength as described above can be more easily realized, for example, by including a third resin layer. The puncture strength of the laminated film can be adjusted by adjusting the types and contents of the resins contained in the first resin layer, the second resin layer, and, optionally, the third resin layer.

[0090] A resin layer containing an ethylene-vinyl alcohol copolymer (EVOH) has high oxygen barrier properties. Therefore, for example, the laminated film provided with a third resin layer containing an ethylene-vinyl alcohol copolymer has oxygen barrier properties.

[0091] On the one hand, ethylene-vinyl alcohol copolymers generally have low compatibility with polyolefin resins that do not fall into either ethylene-vinyl acetate copolymers or ethylene-vinyl alcohol-vinyl acetate copolymers (in other words, ethylene-vinyl acetate copolymers and their partial saponification products). Ethylene-vinyl alcohol-vinyl acetate copolymers (partial saponification products of ethylene-vinyl acetate copolymers) generally have compatibility with ethylene-vinyl alcohol copolymers and further have compatibility with polyolefin resins that do not fall into any of ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, and ethylene-vinyl alcohol-vinyl acetate copolymers (which may be referred to as "non-vinyl polyolefin resins" in this specification). Therefore, when the third resin layer contains the non-vinyl polyolefin resin and the ethylene-vinyl alcohol copolymer, it is preferable that this third resin layer is a resin layer (which may be referred to as "resin layer (I)" in this specification) that further contains an ethylene-vinyl alcohol-vinyl acetate copolymer in addition to these resins. The third resin layer that is the resin layer (I) has high oxygen barrier properties.

[0092] In the resin layer (I), the non-vinyl polyolefin resin is preferably a polyolefin resin of the same type as the polyolefin resin contained in the first resin layer and the second resin layer, and is preferably a polyethylene resin. In the resin layer (I), both the ethylene-vinyl alcohol copolymer and the ethylene-vinyl alcohol-vinyl acetate copolymer are preferably polyolefin resins of the same type as the polyolefin resin contained in the first resin layer and the second resin layer.

[0093] In the resin layer (I) (the third resin layer containing an ethylene-vinyl alcohol copolymer, the non-vinyl polyolefin resin, and an ethylene-vinyl alcohol-vinyl acetate copolymer), in the ethylene-vinyl alcohol copolymer, the ratio of the amount (mol) of the structural unit derived from ethylene to the total amount (mol) of the structural units is preferably 20 mol% or more, more preferably 20 to 80 mol%, and may be any of, for example, 20 to 70 mol%, 20 to 60 mol%, and 20 to 50 mol%, or may be any of 30 to 80 mol%, 40 to 80 mol%, and 50 to 80 mol%, or may be any of 30 to 70 mol% and 40 to 60 mol%.

[0094] In the resin layer (I), the ratio of the content of the ethylene-vinyl alcohol copolymer to the total mass of the resin layer (I) may be, for example, 25 to 70% by mass. However, in terms of higher uniformity and oxygen barrier properties of the resin layer (I), the ratio is preferably 40 to 70% by mass, more preferably 50 to 70% by mass, and may be, for example, 55 to 65% by mass. The ratio is usually the same as the ratio of the content (parts by mass) of the ethylene-vinyl alcohol copolymer to the total content (parts by mass) of the components that do not vaporize at room temperature in the resin composition (the third resin composition described later) for forming the resin layer (I).

[0095] In the resin layer (I), the ratio of the content of the non-vinyl polyolefin resin to the total mass of the resin layer (I) may be, for example, 5 to 50% by mass. However, in terms of higher uniformity and oxygen barrier properties of the resin layer (I), the ratio is preferably 5 to 35% by mass, more preferably 5 to 20% by mass, and may be, for example, 5 to 15% by mass. The ratio is usually the same as the ratio of the content (parts by mass) of the non-vinyl polyolefin resin to the total content (parts by mass) of the components that do not vaporize at room temperature in the resin composition (the third resin composition described later) for forming the resin layer (I).

[0096] In the resin layer (I), the proportion of the content of the ethylene-vinyl alcohol-vinyl acetate copolymer to the total mass of the resin layer (I) is preferably 20 to 40% by mass, and may be, for example, 25 to 35% by mass. When the proportion is within such a range, the effect of using the ethylene-vinyl alcohol-vinyl acetate copolymer can be obtained more remarkably. The proportion is usually the same as the proportion of the content (parts by mass) of the ethylene-vinyl alcohol-vinyl acetate copolymer to the total content (parts by mass) of the components that do not vaporize at room temperature in the resin composition (the third resin composition described later) for forming the resin layer (I).

[0097] In the resin layer (I), the proportion of the total content of the ethylene-vinyl alcohol copolymer, the non-vinyl polyolefin resin, and the ethylene-vinyl alcohol-vinyl acetate copolymer to the total mass of the resin layer (I) is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, and may be, for example, either 97 to 100% by mass or 99 to 100% by mass. When the proportion is at least the lower limit value, the oxygen barrier property of the resin layer (I) becomes higher. The proportion is usually the same as the proportion of the total content (parts by mass) of the ethylene-vinyl alcohol copolymer, the non-vinyl polyolefin resin, and the ethylene-vinyl alcohol-vinyl acetate copolymer to the total content (parts by mass) of the components that do not vaporize at room temperature in the resin composition (the third resin composition described later) for forming the resin layer (I).

[0098] When the laminated film includes the resin layer (I) as the third resin layer, the laminated film may include only one layer of the resin layer (I) or may include two or more layers of the resin layer (I). When the laminated film includes two or more layers of the resin layer (I), these two or more resin layers (I) may be the same as or different from each other, and the combination of these resin layers (I) is not particularly limited as long as the effects of the present invention are not impaired.

[0099] Examples of the laminated film provided with the resin layer (I) as the third resin layer include, for example, a laminated film having one resin layer (I) and one or both of the first resin layer side and the second resin layer side of the resin layer (I), and one or two third resin layers other than the resin layer (I). More specifically, examples of such a laminated film include, for example, a laminated film in which a first resin layer, one resin layer (I) (the third resin layer), one or two third resin layers other than the resin layer (I), and a second resin layer are laminated in this order in their thickness directions, and the total number of the third resin layers is two or three; a laminated film in which a first resin layer, one or two third resin layers other than the resin layer (I), one resin layer (I) (the third resin layer), and a second resin layer are laminated in this order in their thickness directions, and the total number of the third resin layers is two or three; a laminated film in which a first resin layer, one or two third resin layers other than the resin layer (I), one resin layer (I) (the third resin layer), one or two third resin layers other than the resin layer (I), and a second resin layer are laminated in this order in their thickness directions, and the total number of the third resin layers is three to five. In the laminated film exemplified herein, the first resin layer, the resin layer (I), the third resin layer other than the resin layer (I), and the second resin layer all contain the same kind of polyolefin resin. In the laminated film exemplified herein, both the first resin layer and the second resin layer may each be only one layer or two or more layers.

[0100] Preferred examples of the laminated film include, for example, in terms of having oxygen barrier properties, those in which the third resin layer is composed of a plurality of three or more layers, and at least one of them contains the non-vinyl polyolefin resin, ethylene-vinyl alcohol copolymer, and ethylene-vinyl alcohol-vinyl acetate copolymer (i.e., the resin layer (I)). In the case of the third resin layer which is the resin layer (I) as described above, one or more selected from the group consisting of the non-vinyl polyolefin resin, ethylene-vinyl alcohol copolymer, and ethylene-vinyl alcohol-vinyl acetate copolymer may be the same polyolefin resin as the polyolefin resin contained in the first resin layer and the second resin layer. For example, when the non-vinyl polyolefin resin is the same polyolefin resin, either one or both of the ethylene-vinyl alcohol copolymer and the ethylene-vinyl alcohol-vinyl acetate copolymer may be the same polyolefin resin, or both of the ethylene-vinyl alcohol copolymer and the ethylene-vinyl alcohol-vinyl acetate copolymer may not be the same polyolefin resin.

[0101] In the laminated film provided with the resin layer (I) as the third resin layer, the ratio of the thickness of the resin layer (I) to the thickness of the laminated film is not particularly limited, but is preferably 4 to 15%. The resin layer (I) having the ratio above the lower limit value has higher thickness uniformity. By having the ratio below the upper limit value, the recyclability of the laminated film becomes higher.

[0102] When the laminated film is provided with the resin layer (I) as the third resin layer, the oxygen transmission rate of the laminated film under the conditions of a temperature of 23 °C and a relative humidity (RH) of 50% measured in accordance with JIS K 7126-2:2006 may be 500 ml / (m 2 ·24h·atm) or less, but is preferably 100 ml / (m 2 ·24h·atm) or less, more preferably 50 ml / (m 2 ·24h·atm) or less, still more preferably 25 ml / (m 2 ·24h·atm) or less, and for example, may be 10 ml / (m 2 ·24h·atm) or less. On the other hand, the oxygen transmission rate of the laminated film is 0 ml / (m 2 ·24h·atm) or more.

[0103] When the laminated film includes the resin layer (I) as the third resin layer, the haze of the laminated film measured from the outside on the second resin layer side thereof may be either 35% or less or 30% or less, but is preferably 20% or less. The oxygen barrier property of the laminated film with the haze below the upper limit value is higher. This is because the resin layer (I) has high uniformity and high oxygen barrier property. In this specification, "haze" means that measured in accordance with JIS K 7136:2000.

[0104] Since each layer (the first resin layer, the second resin layer, and optionally the third resin layer) constituting the laminated film contains the same type of polyolefin resin, the laminated film not only has high recyclability but also the layers can be adhered to each other without an adhesive layer. That is, the laminated film has high adhesion between the layers even without an adhesive layer. Further, the laminated film without such an adhesive layer can be manufactured at low cost.

[0105] In the laminated film, the ratio of the content of the same type of polyolefin resin to the total mass of the laminated film is preferably 90% or more, more preferably 92% or more, and even more preferably 95% or more. By the ratio being above the lower limit value, the monomaterialization of the laminated film can be achieved, and the entire laminated film can be easily recycled.

[0106] FIG. 1 is a cross-sectional view schematically showing an example of the laminated film of the present embodiment. The laminated film 1 shown here includes a first resin layer 11 and a second resin layer 12, and further includes a third resin layer 13 between the first resin layer 11 and the second resin layer 12. That is, the laminated film 1 is configured by laminating the first resin layer 11, the third resin layer 13, and the second resin layer 12 in this order in their thickness directions. The first resin layer 11, the second resin layer 12, and the third resin layer 13 are all as described above. The third resin layer 13 has an arbitrary configuration, and the laminated film 1 may not include the third resin layer 13.

[0107] One surface of the first resin layer 11 (the surface opposite to the second resin layer 12 side, which may be referred to as the "second surface" in this specification) 11b is an exposed surface. One surface of the second resin layer 12 (the surface opposite to the first resin layer 11 side, which may be referred to as the "first surface" in this specification) 12a is an exposed surface.

[0108] The ratio of the thickness of the third resin layer 13 to the thickness of the laminated film 1 is not particularly limited as described above, but is preferably 50 to 70%. The ratio of the total thickness of the first resin layer 11 and the second resin layer 12 to the thickness of the laminated film 1 is not particularly limited as described above, but is preferably 30 to 50%. In the laminated film 1, the ratio (thickness ratio) of [the thickness of the first resin layer 11] / [the thickness of the second resin layer 12] is not particularly limited as described above, but is preferably 0.7 to 1.3.

[0109] FIG. 2 is a cross-sectional view schematically showing another example of the laminated film of the present embodiment. The laminated film 2 shown here includes, as the third resin layer 23, a five-layer laminated resin layer in which a third-1 resin layer 231, a third-2 resin layer 232, a third-3 resin layer 233, a third-4 resin layer 234, and a third-5 resin layer 235 are laminated in this order in the thickness direction from the first resin layer 11 side to the second resin layer 12 side. That is, the laminated film 2 is formed by laminating the first resin layer 11, the third-1 resin layer 231, the third-2 resin layer 232, the third-3 resin layer 233, the third-4 resin layer 234, the third-5 resin layer 235, and the second resin layer 12 in this order in the thickness direction.

[0110] The laminated film 2 is the same as the laminated film 1 except that it includes the third resin layer 23 instead of the third resin layer 13.

[0111] In the third resin layer 23, it is preferable that both the third-1 resin layer 231 and the third-5 resin layer 235 are resin layers other than the resin layer (I). Any one or two or more of the third-2 resin layer 232, the third-3 resin layer 233, and the third-4 resin layer 234 are preferably the resin layer (I), that is, a resin layer having oxygen barrier properties. As a more preferable example of such a third resin layer 23, for example, the third-1 resin layer 231, the third-2 resin layer 232, the third-4 resin layer 234, and the third-5 resin layer 235 are all resin layers other than the resin layer (I), and the third-3 resin layer 233 is the resin layer (I), and a third resin layer having oxygen barrier properties can be mentioned.

[0112] In the laminated film 2 provided with the resin layer (I) as the third resin layer, the ratio of the thickness of the resin layer (I) to the thickness of the laminated film 2 is not particularly limited as described above, but is preferably 4 to 15%. For example, when the third-3 resin layer 233 is the resin layer (I) among the third resin layers 23, in the laminated film 2, the ratio of the thickness of the third-3 resin layer 233 to the thickness of the laminated film 2 is preferably 4 to 15%.

[0113] The ratio of the thickness of the third resin layer 23 to the thickness of the laminated film 2 is not particularly limited as described above, but is preferably 50 to 70%. The ratio of the total thickness of the first resin layer 11 and the second resin layer 12 to the thickness of the laminated film 2 is not particularly limited as described above, but is preferably 30 to 50%. In the laminated film 2, the ratio (thickness ratio) of [the thickness of the first resin layer 11] / [the thickness of the second resin layer 12] is not particularly limited as described above, but is preferably 0.7 to 1.3.

[0114] In the laminated film 2, the third resin layer 23 may be a laminated resin layer other than the five-layer structure. For example, the third resin layer 23 may have a three-layer structure that does not include the third-1 resin layer 231 and the third-2 resin layer 232, and the third-3 resin layer 233 may be the resin layer (I). For example, the third resin layer 23 may have a two-layer structure that does not include the third-1 resin layer 231, the third-2 resin layer 232, and the third-4 resin layer 234, and the third-3 resin layer 233 may be the resin layer (I). For example, the third resin layer 23 may have a three-layer structure that does not include the third-4 resin layer 234 and the third-5 resin layer 235, and the third-3 resin layer 233 may be the resin layer (I). For example, the third resin layer 23 may have a two-layer structure that does not include the third-2 resin layer 232, the third-4 resin layer 234, and the third-5 resin layer 235, and the third-3 resin layer 233 may be the resin layer (I). For example, the third resin layer 23 may have a four-layer structure that does not include the third-2 resin layer 232, and the third-3 resin layer 233 may be the resin layer (I). For example, the third resin layer 23 may have a four-layer structure that does not include the third-4 resin layer 234, and the third-3 resin layer 233 may be the resin layer (I). For example, the third resin layer 23 may have a three-layer structure that does not include the third-2 resin layer 232 and the third-4 resin layer 234, and the third-3 resin layer 233 may be the resin layer (I).

[0115] The laminated film may include other layers that do not correspond to any of the first resin layer, the second resin layer, and the third resin layer, as long as the effects of the present invention are not impaired. However, it is preferable that the laminated film does not include such other layers. The other layer is a layer that does not contain a polyolefin-based resin. By not including such other layers, the recyclability of the laminated film becomes higher.

[0116] The total thickness of the laminated film is not particularly limited, but for example, it is preferably 100 to 200 μm.

[0117] In the laminated film, it is preferable that all the layers (for example, the first resin layer to the third resin layer) constituting the laminated film are unstretched layers (films). Such an unstretched laminated film is particularly excellent in moldability and is suitable for forming, for example, a deep-drawn package.

[0118] <<Manufacturing method of laminated film>> The laminated film can be manufactured, for example, by a feed block method in which a resin or a resin composition serving as a forming material for each layer is melt-extruded using several extruders, a coextrusion T-die method such as a multi-manifold method, an air-cooled or water-cooled coextrusion inflation method, or the like.

[0119] Further, for the laminated film, two or more films for constituting two or more of the layers thereof are separately prepared in advance, and without using an adhesive, they are laminated by a thermal (heat) lamination method or the like, and if necessary, they are further laminated so as to have a desired arrangement form for the other layers, whereby the laminated film can also be manufactured.

[0120] The resin composition serving as a forming material for any layer in the laminated film may be manufactured by adjusting the types and contents of the contained components so that the layer to be formed contains the target components in the target contents. For example, the ratio of the contents of the components that do not vaporize at room temperature in the resin composition is usually the same as the ratio of the contents of the components in the layer formed from this resin composition.

[0121] Examples of the resin composition (which may be referred to as the "first resin composition" in this specification) for forming the first resin layer (the first resin layer 11 in the laminated film 1 shown in FIG. 1 and the laminated film 2 shown in FIG. 2) include those containing the polyolefin-based resin and, if necessary, other components. The other components are the components described above.

[0122] As the resin composition (which may be referred to as the "second resin composition" in this specification) for forming the second resin layer (the second resin layer 12 in the laminated film 1 shown in FIG. 1 and the laminated film 2 shown in FIG. 2), for example, those containing the polyolefin resin and, if necessary, other components may be mentioned. The other components are the components described above.

[0123] As the resin composition (which may be referred to as the "third resin composition" in this specification) for forming the third resin layer (the third resin layer 13 in the laminated film 1 shown in FIG. 1; the third - 1 resin layer 231, the third - 2 resin layer 232, the third - 3 resin layer 233, the third - 4 resin layer 234, and the third - 5 resin layer 235 in the laminated film 2 shown in FIG. 2), for example, those containing the polyolefin resin and, if necessary, other components may be mentioned. The other components are the components described above. In particular, as the third resin composition for forming the resin layer (I) among the third - 1 resin layer 231 to the third - 5 resin layer 235, those containing an ethylene - vinyl alcohol copolymer, the non - vinyl - type polyolefin resin, an ethylene - vinyl alcohol - vinyl acetate copolymer, and, if necessary, other components may be mentioned.

[0124] <<Package>> The laminated film is suitable as a material for a package. That is, preferred packages include those provided with the laminated film. The package of the present embodiment can be manufactured by packaging an object to be packaged using the laminated film. When manufacturing the package, it is preferable to arrange the first resin layer in the laminated film on the side of the object to be packaged and the second resin layer on the side opposite to the object to be packaged to package the object to be packaged.

[0125] For example, the laminated film is suitable for constituting either the lid material or the bottom material of a deep - drawn package. In particular, the laminated film with good formability is particularly suitable for constituting the bottom material having a recess for forming a storage portion.

[0126] FIG. 3 is a cross-sectional view schematically showing an example of a package including the laminated film of the present embodiment. The package 101 shown here includes a lid member 8 and a bottom member 10, and is a deep-drawn package obtained by deep-drawing a resin film. Either one or both of the lid member 8 and the bottom member 10 are configured using the laminated film 1 or the laminated film 2 shown in FIG. 1. In the lid member 8 or the bottom member 10 in FIG. 3, the distinction between the respective layers in the laminated film 1 or the laminated film 2 constituting the same is omitted.

[0127] A recess 100 is formed in the bottom member 10. One surface (which may be referred to as the "second surface" in this specification) 10b of the region of the bottom member 10 excluding the recess 100 and one surface (which may be referred to as the "second surface" in this specification) 8b of the lid member 8 are both seal surfaces and face each other. The package 101 is constituted by sealing the lid member 8 and the bottom member 10. More specifically, the second surface 10b of the region of the bottom member 10 excluding the recess 100 and the second surface 8b of the lid member 8 are overlapped and sealed in the region near their peripheral edges. As a result, a storage portion 101a is formed between the second surface 10b of the bottom member 10 and the second surface 8b of the lid member 8 in the region of the recess 100 of the bottom member 10. An article 9 is stored in this storage portion 101a.

[0128] When the bottom member 10 is configured using the laminated film 1 or the laminated film 2, it is preferable that one surface (second surface) 10b of the bottom member 10 is the same as the second surface 11b of the first resin layer 11 in the laminated film 1 or the laminated film 2. It is preferable that the other surface (which may be referred to as the "first surface" in this specification) 10a of the bottom member 10 is the same as the first surface 12a of the second resin layer 12 in the laminated film 1 or the laminated film 2.

[0129] When the lid member 8 is formed using the laminated film 1, it is preferable that one surface (second surface) 8b of the lid member 8 is the same as the second surface 11b of the first resin layer 11 in the laminated film 1 or the laminated film 2. The other surface of the lid member 8 (which may be referred to as the "first surface" in this specification) 8a is preferably the same as the first surface 12a of the second resin layer 12 in the laminated film 1 or the laminated film 2.

[0130] In FIG. 3, in the storage portion 101a of the package 101, a partial gap can be seen between the stored item 9 and the bottom member 10, and between the stored item 9 and the lid member 8. However, the presence of these gaps is not essential in the package 101 in the state where the stored item 9 is stored.

[0131] The thickness of the bottom member 10 at its flat portion and the thickness of the lid member 8 may both be the same as the thickness of the laminated film 1 or the laminated film 2 described above.

[0132] So far, as the package provided with the laminated film, a deep-drawn package has been described as an example. However, the package provided with the laminated film is not limited to a deep-drawn package and may be other packages.

[0133] <<Manufacturing method of the package>> The package can be manufactured, for example, by forming a storage portion for storing a packaging object (in other words, a stored item) while forming the storage portion using the laminated films or the laminated film and another resin film other than the laminated film, and then storing the packaging object, and heat-sealing the regions of these films other than the storage portion. At this time, the adhesion of the laminated film (especially the second resin layer) to the heating plate in the heat-sealing device is suppressed.

Example

[0134] Hereinafter, the present invention will be described in more detail with specific examples. However, the present invention is not limited to the examples shown below.

[0135] [Example 1] <<Manufacture of Laminated Film>> The laminated film having the configuration shown in FIG. 1 was manufactured by the procedure shown below. That is, as the resin constituting the first resin layer, low-density polyethylene (LDPE) (manufactured by Ube Maruzen Polyethylene Co., Ltd., "UBE Polyethylene (registered trademark) F222NH", density 0.922 g / cm 3 ) was prepared. As the resin constituting the second resin layer, high-density polyethylene (HDPE) (manufactured by Tosoh Corporation, "Nipolon Hard (registered trademark) 4010", density 0.964 g / cm 3 , melt mass flow rate 5.4 g / 10 min) was prepared. In this specification, this HDPE may be referred to as "HDPE(1)". As the resin constituting the third resin layer, metallocene-catalyzed linear low-density polyethylene (mLLDPE) (manufactured by Ube Maruzen Polyethylene Co., Ltd., "Yumelite (registered trademark) 1520F", density 0.913 g / cm 3 ) was prepared.

[0136] By co-extruding the LDPE, the mLLDPE, and the HDPE(1) in this order, a first resin layer (thickness 30 μm), a third resin layer (thickness 90 μm), and a second resin layer (thickness 30 μm) were laminated in this order in their thickness directions to obtain a laminated film (thickness 150 μm).

[0137] <<Evaluation of Laminated Film>> <Calculation of E’(110) / E’(100) value of the second resin layer> By extrusion molding the HDPE(1), a test resin film (thickness 30 μm) was obtained. From this test resin film, a test piece (1) having a size of 7 cm × 1 cm was cut out, and this test piece (1) was placed in a sample holder so that the length of the measurement target portion was 2 cm. Next, using a dynamic viscoelasticity measuring device ("DMS6100" manufactured by Seiko Instruments Inc.), in the tensile mode, in the temperature range from 20°C to 130°C, with a displacement of 5 μm, a vibration frequency of 1 Hz, and a heating rate of 5°C / min, E'(100) and E'(110) were measured, and the E'(110) / E'(100) value was calculated. The results are shown in Table 1.

[0138] <Measurement of the puncture strength of the laminated film> The tip of a needle with a tip curvature radius of 0.5 mm was pushed against the laminated film obtained above from the side of its second resin layer, and it was pushed vertically into the laminated film at a speed of 500 mm / min. At the moment the needle penetrated the laminated film, the load applied to the needle was read, and this read value was adopted as the puncture strength of the laminated film. The results are shown in Table 1.

[0139] [Example 2] [[Manufacture of the laminated film]] When forming the second resin layer, instead of HDPE(1) ("Nipolon Hard (registered trademark) 4010" manufactured by Tosoh Corporation, density 0.964 g / cm 3 , melt mass flow rate 5.4 g / 10 min), a different type of HDPE ("Nipolon Hard (registered trademark) 1000" manufactured by Tosoh Corporation, density 0.964 g / cm 3 , melt mass flow rate 20 g / 10 min) was used. Otherwise, the laminated film was manufactured in the same manner as in Example 1. In this specification, the HDPE used in this example may be referred to as "HDPE(2)".

[0140] [[Evaluation of the laminated film]] The laminated film obtained above was evaluated in the same manner as in Example 1. The results are shown in Table 1. In Table 1, the description "-" in the column of "Evaluation result" means that the item was not evaluated.

[0141] [Example 3] When forming the third resin layer, a laminated film was produced in the same manner as in Example 1, except that the third resin composition was used instead of mLLDPE (UBE Polyethylene Co., Ltd.'s "Yumelite (registered trademark) 1520F"). This third resin composition was obtained by kneading 90 parts by mass of mLLDPE (UBE Polyethylene Co., Ltd.'s "Yumelite (registered trademark) 1520F") and 10 parts by mass of an elastomer (Mitsui Chemicals, Inc.'s "Tafmer (registered trademark) BL3450M") at 200 °C for 10 minutes.

[0142] <<Evaluation of the laminated film>> The laminated film obtained above was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0143] [Example 4] When forming the second resin layer, a laminated film was produced in the same manner as in Example 1, except that the second resin composition was used instead of HDPE(1) (Toagosei Co., Ltd.'s "Nipolon Hard (registered trademark) 4010", density 0.964 g / cm 3 ). This second resin composition was obtained by kneading 60 parts by mass of HDPE(1) (Toagosei Co., Ltd.'s "Nipolon Hard (registered trademark) 4010") and 40 parts by mass of LDPE (UBE Polyethylene Co., Ltd.'s "UBE Polyethylene (registered trademark) F222NH") at 200 °C for 10 minutes.

[0144] <<Evaluation of the laminated film>> The laminated film obtained above was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0145] [Example 5] <<Manufacture of the laminated film>> When forming the second resin layer, a laminated film (the unirradiated laminated film) was produced in the same manner as in Example 1, except that mLLDPE (UBE Polyethylene Co., Ltd.'s "Yumelite (registered trademark) 1520F") was used instead of HDPE(1) (Toagosei Co., Ltd.'s "Nipolon Hard (registered trademark) 4010", density 0.964 g / cm 3 ). Next, the laminated film was irradiated with an electron beam (EB) from the side of its second resin layer. At this time, the absorbed dose was set to 50 kGy and the acceleration voltage was set to 150 kV. The product thus obtained was used as the laminated film of this example.

[0146] <<Evaluation of the laminated film>> <Calculation of the E’(110) / E’(100) value of the second resin layer> For the laminated film obtained above, E’(100) and E’(110) were measured in the same manner as in Example 1, and the E’(110) / E’(100) value was calculated. The results are shown in Table 2.

[0147] <Measurement of the puncture strength of the laminated film> For the laminated film obtained above, the puncture strength was measured in the same manner as in Example 1. The results are shown in Table 2.

[0148] <Measurement of the gel fraction of the laminated film> The gel fraction of the laminated film obtained above was measured in accordance with JIS K 6769. That is, a test piece (2) with a size of 3 cm × 3 cm was cut out from the laminated film, and this test piece (2) was wrapped with a 400-mesh stainless steel wire mesh (100 g). The test piece (2) wrapped with this stainless steel wire mesh was immersed in xylene (18 mL) at 110°C for 24 hours. Next, the test piece (2) after immersion was taken out from the xylene together with the stainless steel wire mesh, and further vacuum dried at 110°C for 24 hours under a pressure of 1.7 kPa. The mass of the obtained dried product was determined to calculate the gel fraction. The results are shown in Table 2.

[0149] <Measurement of the 2000-μm displacement temperature of the laminated film> Using a thermal analyzer (SII's "EXSTAR6000"), thermomechanical analysis was performed on the laminated film obtained above in accordance with JIS K 7196, and the 2000-μm displacement temperature was determined from the obtained thermomechanical analysis curve. The results are shown in Table 2.

[0150] [Comparative Example 1] [Manufacture of Laminated Film] As the resin constituting the sealant layer, low density polyethylene (LDPE) (UBE Polyethylene Co., Ltd.'s "UBE Polyethylene (registered trademark) F222NH", density 0.922 g / cm 3 ) was prepared. As the resin constituting the intermediate layer, metallocene-catalyzed linear low density polyethylene (mLLDPE) (UBE Polyethylene Co., Ltd.'s "Yumelite (registered trademark) 1520F") was prepared. As the resin constituting the adhesive layer, a modified polyolefin resin ("NF536" manufactured by Mitsui Chemicals, Inc.) was prepared. As the resin constituting the strength retention layer and the outer layer, 6-nylon (Ny) ("1022B" manufactured by Ube Industries, Ltd.) was prepared.

[0151] By co-extruding the LDPE, the mLLDPE, the modified polyolefin resin, the Ny, the modified polyolefin resin, and the Ny in this order, a sealant layer (thickness 20 μm), an intermediate layer (thickness 60 μm), an adhesive layer (thickness 15 μm), a strength retention layer (thickness 30 μm), an adhesive layer (thickness 15 μm), and an outer layer (thickness 10 μm) were laminated in this order in their thickness directions to obtain a laminated film (thickness 150 μm).

[0152] [Evaluation of Laminated Film] [Calculation of E’(110) / E’(100) Value of Outer Layer] For the laminated film obtained above, E’(100) and E’(110) of the outer layer were measured in the same manner as in Example 1, and the E’(110) / E’(100) value was calculated. The results are shown in Table 3.

[0153] [Measurement of Puncture Strength of Laminated Film] For the laminated film obtained above, the puncture strength was measured in the same manner as in Example 1. The results are shown in Table 3.

[0154] [Table 1]

[0155]

Table 2

[0156]

Table 3

[0157] As is clear from the above results, in Examples 1 to 5, the E’(110) / E’(100) value of the second resin layer was 0.25 or more (0.25 to 0.7), and it was sufficiently large to the extent that the heat resistance of the second resin layer could be recognized as being sufficiently high. Among them, in Examples 1 to 4, the E’(110) / E’(100) value of the second resin layer was particularly large, at 0.66 to 0.7, and the effect of the second resin layer containing HDPE was high. The laminated films of Examples 1 to 5 all contained PE in the first resin layer to the third resin layer, and the main components were the same kind of polyolefin resin, and the recyclability was high.

[0158] A resin layer (resin film) that was the same as the second resin layer in Example 5 was separately prepared except that EB irradiation was not performed, and its E’(100) and E’(110) were measured, and the E’(110) / E’(100) value was calculated. As a result, it was 0.11. Thus, in Example 5, due to the effect of EB irradiation, the E’(110) / E’(100) value of the second resin layer had increased. Furthermore, in Example 5, the gel fraction of the laminated film was 42%, and the displacement temperature of the laminated film at 2000 μm was 125°C. Here too, the effect of EB irradiation of the second resin layer was recognized.

[0159] In Examples 1 to 5, the puncture strength of the laminated film was 7.4 N or more (7.4 to 10.8 N), which was sufficiently large. Thus, the laminated films of Examples 1 to 5 had sufficiently high pinhole resistance and high strength even without using polyamides such as Ny.

[0160] In Examples 1 to 5, all of the first resin layer to the third resin layer were unstretched layers (films), and the laminated films of these examples had excellent moldability.

[0161] Since the outer layer of the laminated film of Comparative Example 1 contained Ny, it had sufficient heat resistance, and since the strength retention layer contained Ny, it was sufficiently high-strength. However, the sealant layer and the intermediate layer contained PE, and the adhesive layer contained a modified polyolefin resin. Thus, the laminated film of Comparative Example 1 had layers in which the main components were resins of different types from each other, and the recyclability was low.

[0162] [Example 6] [Manufacture of Laminated Film] A laminated film having the configuration shown in FIG. 2 was manufactured according to the procedure shown below. That is, as the resin constituting the first resin layer, low-density polyethylene (LDPE) ("UBE Polyethylene (Registered Trademark) F222NH" manufactured by Ube Maruzen Polyethylene Co., Ltd., density 0.922 g / cm 3 ) was prepared. As the resin constituting the second resin layer, high-density polyethylene (HDPE) ("Nipolon Hard (Registered Trademark) 4010" manufactured by Tosoh Corporation, density 0.964 g / cm 3 , melt mass flow rate 5.4 g / 10 min, HDPE (1)) was prepared. As the resins constituting the third-1 resin layer, the third-2 resin layer, the third-3 resin layer, the third-4 resin layer, and the third-5 resin layer, metallocene-catalyzed linear low-density polyethylene (mLLDPE) ("Yumelite (Registered Trademark) 1520F" manufactured by Ube Maruzen Polyethylene Co., Ltd., density 0.913 g / cm 3 ) was prepared. As the resin constituting the third-3 resin layer, an ethylene-vinyl alcohol-vinyl acetate copolymer (partially saponified EVA) ("Melsene (Registered Trademark) -H3051R" manufactured by Tosoh Corporation) and an ethylene-vinyl alcohol copolymer (EVOH) ("Eval (Registered Trademark) E105B" manufactured by Kuraray Co., Ltd.) were prepared.

[0163] The third resin composition was produced by kneading the mLLDPE (40 parts by mass), the partially saponified EVA (30 parts by mass), and the EVOH (30 parts by mass) at 200 °C for 10 minutes.

[0164] The LDPE, the mLLDPE, the mLLDPE, the third resin composition, the mLLDPE, the mLLDPE, and the HDPE(1) were co-extruded in this order to obtain a laminated film (150 μm in thickness) in which a first resin layer (30 μm in thickness), a third-1 resin layer (15 μm in thickness), a third-2 resin layer (30 μm in thickness), a third-3 resin layer (15 μm in thickness), a third-4 resin layer (15 μm in thickness), a third-5 resin layer (15 μm in thickness), and a second resin layer (30 μm in thickness) were laminated in this order in the thickness direction thereof.

[0165] [[Evaluation of the laminated film]] [Measurement of the puncture strength of the laminated film] The laminated film obtained above was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0166] [Measurement of the haze of the laminated film] For the laminated film obtained above, the haze was measured from the outside on the second resin layer side in accordance with JIS K 7136:2000. The results are shown in Table 4.

[0167] [Measurement of the oxygen permeability of the laminated film] For the laminated film obtained above, the oxygen permeability under the conditions of a temperature of 23 °C and a relative humidity of 50% was measured in accordance with JIS K 7126-2:2006. The results are shown in Table 4.

[0168] [Example 7] [[Production of the laminated film]] When producing the third resin composition, instead of kneading the mLLDPE (40 parts by mass), the partially saponified EVA (30 parts by mass), and the EVOH (30 parts by mass) at 200°C for 10 minutes, a laminated film was produced in the same manner as in Example 6, except that the mLLDPE (25 parts by mass), the partially saponified EVA (30 parts by mass), and the EVOH (45 parts by mass) were kneaded at 200°C for 10 minutes. This laminated film was a laminated film (150 μm thick) in which a first resin layer (30 μm thick), a third - 1 resin layer (15 μm thick), a third - 2 resin layer (30 μm thick), a third - 3 resin layer (15 μm thick), a third - 4 resin layer (15 μm thick), a third - 5 resin layer (15 μm thick), and a second resin layer (30 μm thick) were laminated in this order in the thickness direction thereof.

[0169] <<Evaluation of the laminated film>> The laminated film obtained above was evaluated in the same manner as in Example 6. The results are shown in Table 4.

[0170] [Example 8] <<Production of the laminated film>> When producing the third resin composition, instead of kneading the mLLDPE (40 parts by mass), the partially saponified EVA (30 parts by mass), and the EVOH (30 parts by mass) at 200°C for 10 minutes, a laminated film was produced in the same manner as in Example 6, except that the mLLDPE (10 parts by mass), the partially saponified EVA (30 parts by mass), and the EVOH (60 parts by mass) were kneaded at 200°C for 10 minutes. This laminated film was a laminated film (150 μm thick) in which a first resin layer (30 μm thick), a third - 1 resin layer (15 μm thick), a third - 2 resin layer (30 μm thick), a third - 3 resin layer (15 μm thick), a third - 4 resin layer (15 μm thick), a third - 5 resin layer (15 μm thick), and a second resin layer (30 μm thick) were laminated in this order in the thickness direction thereof.

[0171] <<Evaluation of the laminated film>> The laminated film obtained above was evaluated in the same manner as in the case of Example 6. The results are shown in Table 4.

[0172] [Example 9] [[Manufacture of Laminated Film]] When producing the third resin composition, instead of kneading the mLLDPE (40 parts by mass), the partially saponified EVA (30 parts by mass), and the EVOH (30 parts by mass) at 200°C for 10 minutes, the LDPE (10 parts by mass), the partially saponified EVA (30 parts by mass), and the EVOH (60 parts by mass) were kneaded at 200°C for 10 minutes. A laminated film was produced in the same manner as in the case of Example 6, except for this point. This laminated film was a laminated film (150 μm thick) in which a first resin layer (30 μm thick), a 3-1 resin layer (15 μm thick), a 3-2 resin layer (30 μm thick), a 3-3 resin layer (15 μm thick), a 3-4 resin layer (15 μm thick), a 3-5 resin layer (15 μm thick), and a second resin layer (30 μm thick) were laminated in this order in their thickness directions.

[0173] [[Evaluation of Laminated Film]] The laminated film obtained above was evaluated in the same manner as in the case of Example 6. The results are shown in Table 5.

[0174] [Example 10] [[Manufacture of Laminated Film]] A laminated film was produced in the same manner as in the case of Example 9, except that the extrusion amount of the mLLDPE was increased and the extrusion amount of the third resin composition was reduced. This laminated film was a laminated film (150 μm thick) in which a first resin layer (37.5 μm thick), a 3-1 resin layer (15 μm thick), a 3-2 resin layer (30 μm thick), a 3-3 resin layer (7.5 μm thick), a 3-4 resin layer (15 μm thick), a 3-5 resin layer (15 μm thick), and a second resin layer (30 μm thick) were laminated in this order in their thickness directions.

[0175] [[Evaluation of Laminated Film]] The laminated film obtained above was evaluated in the same manner as in Example 6. The results are shown in Table 5.

[0176] [Example 11] [Manufacture of Laminated Film] A laminated film was produced in the same manner as in Example 6, except that the mLLDPE was used instead of the third resin composition. This laminated film was a laminated film (150 μm in thickness) composed of a first resin layer (30 μm in thickness), a third - 1 resin layer (15 μm in thickness), a third - 2 resin layer (30 μm in thickness), a third - 3 resin layer (15 μm in thickness), a third - 4 resin layer (15 μm in thickness), a third - 5 resin layer (15 μm in thickness), and a second resin layer (30 μm in thickness), laminated in this order in their thickness directions.

[0177] [Evaluation of Laminated Film] The laminated film obtained above was evaluated in the same manner as in Example 6. The results are shown in Table 5.

[0178] [Table 4]

[0179] [Table 5]

[0180] As is clear from the above results, in Examples 6 to 11, the E’(110) / E’(100) value of the second resin layer was 0.7, and it was large enough to recognize that the heat resistance of the second resin layer was sufficiently high.

[0181] The laminated films of Examples 6 to 11 all contained PE in the first resin layer to the third resin layer, and the main components were the same kind of polyolefin - based resin, and had high reusability.

[0182] In Examples 6 to 11, the piercing strength of the laminated film was 7.5 N or more (7.5 to 8.5 N), which was sufficiently large. Thus, the laminated films of Examples 6 to 11 had sufficiently high pinhole resistance and high strength even without using polyamides such as Ny.

[0183] Among Examples 6 to 11, in Examples 6 to 10, the oxygen transmission rate of the laminated film was 452.2 ml / (m 2 ·24 h·atm) or less (9.4 to 452.2 ml / (m 2 ·24 h·atm)), and the laminated films of Examples 6 to 10 had oxygen barrier properties. This was because the third resin layer in these laminated films was the resin layer (I). Among them, the oxygen transmission rate of the laminated films of Examples 7 to 10 was 21.3 ml / (m 2 ·24 h·atm) or less (9.4 to 21.3 ml / (m 2 ·24 h·atm)), and the laminated films of Examples 7 to 10 had high oxygen barrier properties. This was because of the high uniformity and oxygen barrier properties of the third resin layer in these laminated films.

[0184] In Examples 6 to 11, the haze of the laminated film was 25.7% or less (16.5 to 25.7%). Among them, in Examples 8 to 10, the haze of the laminated film was 18.9% or less (16.5 to 18.9%), which was at a low level. This was because of the high uniformity of the third resin layer in these laminated films, which was consistent with the high oxygen barrier properties of these laminated films.

[0185] In Examples 6 to 11, all of the first resin layer to the third resin layer were unstretched layers (films), and the laminated films of these examples had excellent moldability.

Industrial Applicability

[0186] The present invention can be used for manufacturing various packages that can be reused after use.

Explanation of Signs

[0187] 1,2 laminated film 11 First resin layer 11b Second surface of the first resin layer 11 12 Second resin layer 12a First surface of the second resin layer 12 13,23 Third resin layer 231 Third - 1 resin layer 232 Third - 2 resin layer 233 Third - 3 resin layer 234 Third - 4 resin layer 235 Third - 5 resin layer 100 Recess 101 Package (deep - drawing package) 101a Storage part 8 Lid material 8a First surface of the lid material 8 8b Second surface of the lid material 8 9 Stored item 10 Bottom material 10a First surface of the bottom material 10 10b Second surface of the bottom material 10

Claims

1. A laminated film comprising a first resin layer and a second resin layer, wherein the laminated film further comprises a third resin layer between the first resin layer and the second resin layer, the first resin layer, the second resin layer, and the third resin layer contain the same type of polyolefin resin, and the same type of polyolefin resin means that in any polyolefin resin, the ratio of the amount of the common constitutional unit to the total amount of the constitutional units is 80 mol% or more, when dynamic viscoelasticity measurement is performed on the second resin layer and the elastic modulus E'(100) at 100 °C and the elastic modulus E'(110) at 110 °C are measured when the vibration frequency is 1 Hz, the value of E'(110) / E'(100) is 0.2 or more, the second resin layer is the outermost layer, the first resin layer and the second resin layer are composed only of low-density polyethylene, the third resin layer is composed only of low-density polyethylene, the gel fraction of the laminated film measured in accordance with JIS K 6769 is 30% or more, the first resin layer and the second resin layer are non-stretched layers, when the tip of a needle with a tip curvature radius of 0.5 mm is pushed vertically into the laminated film at a speed of 500 mm / min, the load applied to the needle at the moment the needle penetrates the laminated film is 10 N or more, the laminated film is irradiated with an electron beam under the condition of an absorbed dose of 20 to 300 kGy from the second resin layer side of the laminated film.

2. The laminated film according to claim 1, wherein when thermomechanical analysis is performed on the laminated film in accordance with JIS K 7196, the temperature at which a displacement of 2000 μm is exhibited is 120 °C or higher.

Images