Laminated film and package

Abstract

This laminated film is formed by laminating a first resin layer, a third resin layer, and a second resin layer in this order in the thickness direction thereof, wherein: the first resin layer, the second resin layer, and the third resin layer contain the same kind of polyolefin-based resin; the ratio of the thickness T13 of the third resin layer to the thickness T1 of the laminated film is greater than 85%; when a Gelbo flex test is performed on the laminated film under the conditions of a temperature of 23ºC and a twist number of 2,000 times in accordance with ASTM F392, the number of pinholes recognized in the laminated film after the Gelbo flex test is at most 2; and the puncture strength of the laminated film is at least 6 N.

Description

Laminated film and packaging

[0001] This application claims priority from Japanese Patent Application No. 2023-195239, filed on November 16, 2023, the contents of which are incorporated herein by reference.

[0002] Laminated films, which are constructed by laminating multiple resin layers, are widely used as packaging materials. Typical laminated films include at least a sealant layer for heat sealing to an object to be sealed and an outer layer on the side opposite the sealant layer.

[0003] On the other hand, because of their high convenience, such laminated films for packaging applications are produced and consumed in large quantities all over the world every day, and a large amount of waste is generated after use. From the perspective of improving the global environment, the generation of waste is an important issue that needs to be resolved, and in recent years, methods for reducing the amount of waste generated as well as for reusing (recycling) waste have been actively studied.

[0004] For example, if the main constituent materials of the multiple resin layers in a laminate film are the same, there is no need to separate and reuse each resin layer separately, and the entire laminate film can be easily reused, which increases its usefulness. As such a laminate film, for example, a polyethylene laminate for packaging material has been disclosed (see Patent Document 1), which includes at least an oriented polyethylene film, an adhesive layer, and a heat-sealable polyethylene layer, and the adhesive layer contains a solventless adhesive.

[0005] Japanese Patent Application Publication No. 2019-189333

[0006] On the other hand, depending on the application, a package may be required to have higher strength than usual. For example, a package that has excellent pinhole resistance, which suppresses the formation of pinholes in the package when the package is twisted, and puncture strength, which suppresses damage to the package even if a sharp part of the stored item hits the package, is useful when packaging an object while maintaining high hygiene. However, pinhole resistance and puncture strength of a package do not necessarily coexist, and increasing one often results in a decrease in the other. The laminated film described in Patent Document 1 does not achieve both high pinhole resistance and puncture strength for a package.

[0007] An object of the present invention is to provide a laminated film that can be used to produce packaging that has high pinhole resistance and puncture strength, and that is highly suitable for recycling.

[0008] To solve the above problems, the present invention employs the following configurations. [1] A laminate film constructed by laminating a first resin layer, a third resin layer, and a second resin layer in this order in the thickness direction, wherein the first resin layer, the second resin layer, and the third resin layer contain the same type of polyolefin-based resin, the ratio of the thickness of the third resin layer to the thickness of the laminate film is greater than 85%, and when the laminate film is subjected to a Gelbo Flex test in accordance with ASTM F392 at a temperature of 23°C and 2,000 twists, the number of pinholes observed in the laminate film after the Gelbo Flex test is two or less, and the laminate film has a puncture strength of 6 N or more. [2] The laminate film according to [1], wherein the third resin layer contains, as the polyolefin-based resin, either or both of a linear low-density polyethylene having structural units derived from octene and a metallocene-catalyzed linear low-density polyethylene having structural units derived from octene.

[0009] [3] The laminate film according to [1] or [2], wherein the first resin layer is a non-easy peel sealant layer containing, as the polyolefin-based resin, one or more types selected from the group consisting of polyethylene and an ethylene-based copolymer. [4] The laminate film according to [3], wherein the first resin layer contains, as the polyolefin-based resin, one or more types selected from the group consisting of low-density polyethylene, linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, and ethylene-vinyl acetate copolymer. [5] The laminate film according to [4], wherein the second resin layer contains, as the polyolefin-based resin, high-density polyethylene and one or more types selected from the group consisting of low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene.

[0010] [6] The laminate film according to [1] or [2], wherein the first resin layer is an easy-peel layer containing, as the polyolefin-based resin, one or more selected from the group consisting of polyethylene and an ethylene-based copolymer, and one or more selected from the group consisting of homopolypropylene and a propylene-based copolymer. [7] The laminate film according to [6], wherein the first resin layer contains, as the polyolefin-based resin, an ethylene-vinyl acetate copolymer and homopolypropylene. [8] The laminate film according to [7], wherein the second resin layer contains, as the polyolefin-based resin, high-density polyethylene and one or more selected from the group consisting of low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene.

[0011] [9] A packaging body constructed using the laminate film according to any one of [1] to [8].

[0012] According to the present invention, a laminated film that can produce packaging with high pinhole resistance and puncture strength and is highly suitable for recycling is provided.

[0013] 1 is a cross-sectional view schematically showing an example of a laminated film according to an embodiment of the present invention; 2 is a cross-sectional view schematically showing an example of a packaging body according to an embodiment of the present invention;

[0014] <<Laminate Film>> One embodiment of the present invention provides a laminate film comprising a first resin layer, a third resin layer, and a second resin layer laminated in this order in the thickness direction, wherein the first resin layer, the second resin layer, and the third resin layer contain the same type of polyolefin resin, and the ratio of the thickness of the third resin layer to the thickness of the laminate film is greater than 85%, and when the laminate film is subjected to a Gelbo flex test in accordance with ASTM F392 at a temperature of 23°C and 2000 twists, the number of pinholes observed in the laminate film after the Gelbo flex test is 2 or less, and the puncture strength of the laminate film is 6 N or more.

[0015] The laminate film of this embodiment is highly suitable for recycling because the first resin layer, second resin layer, and third resin layer contain the same type of polyolefin resin. After the Gelbo Flex test was performed on the laminate film of this embodiment, the number of pinholes found in the laminate film was two or less, indicating that the laminate film has high pinhole resistance and can be used to produce packages with high pinhole resistance. The laminate film of this embodiment has a high puncture strength of 6 N or more, indicating that the laminate film can be used to produce packages with high puncture strength. In the laminate film of this embodiment, the ratio of the thickness of the third resin layer to the thickness of the laminate film is greater than 85% (85 < [thickness of the third resin layer] / [thickness of the laminate film] × 100), indicating that the puncture strength and pinhole resistance of the laminate film are high.

[0016] Previous resin films used to manufacture packaging have not necessarily been able to achieve both high pinhole resistance and high puncture strength. In contrast, the laminate film of the present embodiment, having the above-described configuration, has both high pinhole resistance and high puncture strength, making it possible to manufacture packaging that has both high pinhole resistance and high puncture strength.

[0017] The first resin layer does not have to be the outermost layer of the laminate film of this embodiment, but is preferably the outermost layer, and the first resin layer serving as the outermost layer is suitable, for example, as a sealant layer. The second resin layer does not have to be the outermost layer of the laminate film of this embodiment, but is preferably the outermost layer, and the second resin layer serving as the outermost layer is suitable, for example, as an outer layer. The third resin layer corresponds to an intermediate layer. The overall structure and characteristics of the laminate film of this embodiment will be described below.

[0018] <Pinhole Resistance> When the laminate film of this embodiment is subjected to a Gelbo Flex test in accordance with ASTM F392 at a temperature of 23°C and 2,000 twists, the number of pinholes observed in the laminate film after the Gelbo Flex test is 2 or less (0 to 2), preferably 0 to 1, and more preferably 0. The laminate film exhibits such Gelbo Flex test results and has high pinhole resistance. In other words, even when a torsional force is applied to the laminate film, the occurrence of pinholes (breakage) is suppressed, and the laminate film has high torsional resistance.

[0019] Not only in the case of the laminated film of this embodiment, but also in any other film used in the Gelbo Flex test, the size of the film is preferably A4 size (210 mm × 297 mm). In this specification, a film of this size may be referred to as a "first test piece."

[0020] The pinhole resistance (torsion resistance) of the laminate film of this embodiment can be adjusted, for example, by adjusting the type or content of components contained in each layer, such as the first resin layer, the second resin layer, or the third resin layer, constituting the laminate film, or the thickness of each of these layers. In particular, the pinhole resistance of the laminate film can be easily adjusted by adjusting the type or content of components contained in the second resin layer and the third resin layer, or the thickness of the second resin layer and the third resin layer. In particular, the pinhole resistance of the laminate film can be more easily adjusted by adjusting the type or content of components contained in the second resin layer, or the thickness of the second resin layer.

[0021] <Puncture Strength> The puncture strength of the laminate film of this embodiment is 6 N or more, preferably 8.5 N or more, and more preferably 10 N or more. The higher the puncture strength of the laminate film, the higher the strength of the laminate film. Furthermore, when the puncture strength of the laminate film is equal to or greater than the above-mentioned lower limit, even if a sharp portion is present on the stored item in a package obtained by packaging an object using the laminate film and such a portion hits the package (more specifically, the region formed by the laminate film of this embodiment), damage to the package is suppressed.

[0022] The upper limit of the puncture strength of the laminated film of this embodiment is not particularly limited. For example, a laminated film having a puncture strength of 14 N or less can be more easily produced. In one embodiment, the puncture strength may be, for example, any one of 6 to 14 N, 8.5 to 14 N, and 10 to 14 N. However, these are just examples of the puncture strength.

[0023] In this embodiment, the tip of a needle having a radius of curvature of 0.5 mm is pressed perpendicularly into the laminate film from the second resin layer side at a speed of 50 mm / min, and the load applied to the needle at the moment the needle penetrates the laminate film is used as the puncture strength of the laminate film.

[0024] The puncture strength of the laminate film of this embodiment can be adjusted, for example, by adjusting the type or content of components contained in each layer, such as the first resin layer, the second resin layer, or the third resin layer, constituting the laminate film, or the thickness of each of these layers. In particular, the puncture strength of the laminate film can be more easily adjusted by adjusting the type or content of components contained in the third resin layer or the thickness of the third resin layer.

[0025] <Thickness Ratio of Each Layer> The ratio of the thickness of the third resin layer to the thickness of the laminate film ([Thickness of Third Resin Layer]) / [Thickness of Laminate Film] × 100) is preferably greater than 85%. In order to enhance the above-described effects, this ratio is preferably 87% or greater, and more preferably 89% or greater. On the other hand, the ratio of the thickness of the third resin layer to the thickness of the laminate film is preferably less than 100% and 95% or less. When this ratio is within this range, the effects obtained by the laminate film including the first resin layer and the second resin layer are enhanced. In one embodiment, the ratio of the thickness of the third resin layer to the thickness of the laminate film may be, for example, greater than 85% but not greater than 95%, 87 to 95%, or 89 to 95%. However, these are just examples of the ratios.

[0026] Regardless of whether the first resin layer is a sealant layer (whether it is a non-easy-peel sealant layer or an easy-peel layer, as described below), the ratio of the thickness of the first resin layer to the thickness of the laminate film ([thickness of the first resin layer]) / [thickness of the laminate film] × 100) is preferably 7.5% or less, more preferably 6.5% or less, and even more preferably 5.5% or less. When this ratio is equal to or less than the upper limit, the effects obtained by the laminate film including the second resin layer and the third resin layer are enhanced. On the other hand, the ratio of the thickness of the first resin layer to the thickness of the laminate film is preferably greater than 0% and 1% or more. When this ratio is 1% or more, the effects obtained by the laminate film including the first resin layer are enhanced. For example, when the first resin layer is a sealant layer, the seal strength of a package obtained by heat-sealing the laminate film or a molded product thereof with another resin film or a molded product thereof is enhanced.

[0027] The ratio of the thickness of the second resin layer to the thickness of the laminate film ([thickness of the second resin layer]) / [thickness of the laminate film] × 100) is preferably 7.5% or less, more preferably 6.5% or less, and even more preferably 5.5% or less. When this ratio is equal to or less than the upper limit, the effects obtained by the laminate film including the first resin layer and the third resin layer are enhanced. On the other hand, the ratio of the thickness of the second resin layer to the thickness of the laminate film is preferably greater than 0% and greater than or equal to 1%. When this ratio is within this range, the effects obtained by the laminate film including the second resin layer are enhanced. For example, when the second resin layer is an outer layer, the pinhole resistance of the laminate film and the package obtained using the same is enhanced. Furthermore, adjusting the type and content of the components contained in the second resin layer also improves the moldability of the laminate film. In this case, the package obtained by molding the laminate film can achieve a desired shape with high precision, for example, by preventing excessive thickness at the corners. Furthermore, by adjusting the types and amounts of the components contained in the second resin layer, the heat resistance thereof can be improved, and the heat resistance of the package obtained using the laminated film can also be improved.

[0028] In the laminate film, the sum of the ratio of the thickness of the first resin layer to the thickness of the laminate film, the ratio of the thickness of the second resin layer to the thickness of the laminate film, and the ratio of the thickness of the third resin layer to the thickness of the laminate film does not exceed 100%.

[0029] In the laminate film, the ratio of [thickness of the first resin layer]:[thickness of the second resin layer] (ratio of the thicknesses of the first resin layer and the second resin layer) is preferably 7:3 to 3:7, and more preferably 6:4 to 4:6. When the ratio is in this range, the effects obtained by the laminate film including the first resin layer and the second resin layer are further enhanced.

[0030] The present invention will be described in detail below with reference to the drawings. Note that the drawings used in the following description may show essential parts enlarged for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional proportions of each component may not necessarily be the same as in reality.

[0031] 1 is a cross-sectional view schematically illustrating an example of a laminate film according to the present embodiment. The laminate film 1 shown here is configured to include a first resin layer 11 and a second resin layer 12 provided on one surface 11a (sometimes referred to as the "first surface" in this specification) of the first resin layer 11. The laminate film 1 further includes a third resin layer 13 between the first resin layer 11 and the second resin layer 12. That is, the laminate 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 the thickness direction.

[0032] The first resin layer 11 is one of the outermost layers of the laminate film 1. The other surface 11b of the first resin layer 11 (the surface opposite to the second resin layer 12; sometimes referred to as the "second surface" in this specification) is the exposed surface (one of the outermost surfaces). For example, when the first resin layer 11 is a sealant layer, the second surface 11b of the first resin layer 11 is a sealing surface with another resin film or a molded product thereof. As will be described later, in a package formed by sealing the first resin layer 11 with the other resin film or a molded product thereof, the non-sealed region of the second surface 11b of the first resin layer 11 forms a storage section in the package.

[0033] In the laminate film of this embodiment, the outermost layer means the outermost layer in the stacking direction of each layer constituting the laminate film, and the outermost surface means the outermost surface (i.e., the exposed surface) in the stacking direction of each layer constituting the laminate film.

[0034] The second resin layer 12 is the other outermost layer of the laminate film 1. One surface 12a of the second resin layer 12 (the surface opposite to the first resin layer 11 side; in this specification, this surface may be referred to as the "first surface") is the exposed surface (the other outermost surface). For example, when the second resin layer 12 is the outer layer, the first surface 12a of the second resin layer 12 is the exposed surface (the other outermost surface) even in the package configured as described above.

[0035] The first resin layer 11, the second resin layer 12, and the third resin layer 13 contain the same type of polyolefin resin.

[0036] Thickness T of the laminated film 1 １ The thickness T of the third resin layer 13 １３ The ratio (T １３ / T １ × 100) is more than 85%. When the Gelbo Flex test is performed on the laminate film 1 or the first test piece thereof, the number of pinholes observed in the laminate film 1 or the first test piece thereof after the Gelbo Flex test is 2 or less. The puncture strength of the laminate film 1 is 6 N or more. Next, the details of each layer of the laminate film of this embodiment will be described.

[0037] <First Resin Layer> The first resin layer contains a polyolefin-based resin. In this specification, the polyolefin-based resin means a resin having structural units derived from an olefin, not limited to the first resin layer.

[0038] In the first resin layer, the ratio of the total content of one or more later-described components contained in the first resin layer to the total mass of the first resin layer does not exceed 100 mass%. Similarly, in the later-described composition for forming the first resin layer, the ratio of the total content of one or more later-described components contained in the composition for forming the first resin layer to the total mass of the composition for forming the first resin layer does not exceed 100 mass%.

[0039] The polyolefin resin contained in the first resin layer may be a homopolymer of one type of olefin or a copolymer of two or more types of olefins.

[0040] Examples of the polyolefin-based resin contained in the first resin layer include polyethylene-based resins (in this specification, the polyethylene-based resin contained in the first resin layer may be particularly referred to as "polyethylene-based resin (e1)"), polypropylene-based resins (in this specification, the polypropylene-based resin contained in the first resin layer may be particularly referred to as "polypropylene-based resin (p1)"), and the like.

[0041] The polyethylene-based resin (polyethylene-based resin (e1)) contained in the first resin layer is a polymer (resin component) having structural units derived from ethylene, and may be polyethylene (PE, for example, a homopolymer of ethylene) or an ethylene-based copolymer having structural units derived from ethylene and structural units derived from a monomer other than ethylene.

[0042] However, not only in the case of the first resin layer, among polyolefin-based resins (olefin-based copolymers) having structural units derived from ethylene and structural units derived from propylene, copolymers in which the number of structural units derived from propylene is greater than the number of structural units derived from ethylene are classified as propylene-based copolymers.

[0043] Among the polyethylene-based resins (e1) contained in the first resin layer, examples of the polyethylene (PE) include 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 low-density polyethylene, linear low-density polyethylene, or metallocene-catalyzed linear low-density polyethylene is preferred.

[0044] In this specification, the density of low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and metallocene-catalyzed linear low density polyethylene (mLLDPE) is 0.910 g / cm ３ Above, 0.945g / cm ３ The density of medium density polyethylene (MDPE) is less than 0.945 g / cm ３ Above, 0.955g / cm ３The density of high density polyethylene (HDPE) is less than 0.955 g / cm ３ That's all.

[0045] More preferred examples of the polyethylene contained in the first resin layer include octene (C ８ H １６ linear low density polyethylene having structural units derived from octene (C8-LLDPE) (sometimes referred to herein as "C8-LLDPE"); ８ H １６ and polyethylenes having structural units derived from octene, such as metallocene-catalyzed linear low-density polyethylene having structural units derived from octene (sometimes referred to herein as "C8-mLLDPE").

[0046] In this specification, C8-LLDPE is a subordinate concept of LLDPE (linear low-density polyethylene), and linear low-density polyethylene is a concept that encompasses linear low-density polyethylene having structural units derived from octene and other linear low-density polyethylenes. Similarly, C8-mLLDPE is a subordinate concept of mLLDPE (metallocene-catalyzed linear low-density polyethylene), and metallocene-catalyzed linear low-density polyethylene is a concept that encompasses metallocene-catalyzed linear low-density polyethylene having structural units derived from octene and other metallocene-catalyzed linear low-density polyethylenes.

[0047] The ethylene-based copolymer contained in the first resin layer is preferably a resin other than ethylene-vinyl alcohol copolymer (EVOH). Examples of the ethylene-based copolymer contained in the first resin layer include ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol-vinyl acetate copolymer (also known as partially saponified ethylene-vinyl acetate copolymer, sometimes referred to herein as "partially saponified EVA"), ethylene-vinyl alcohol copolymer (EVOH, also known as saponified ethylene-vinyl acetate copolymer, sometimes referred to herein as "saponified EVA"), 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), and ionomer (ION). The ionomer may be, for example, a resin in which a copolymer of ethylene and a small amount of acrylic acid or methacrylic acid has an ionic crosslinking structure due to salt formation between the acid moiety in the copolymer and a metal ion.

[0048] The polypropylene-based resin (polypropylene-based resin (p1)) contained in the first resin layer is a polymer (resin component) having structural units derived from propylene, and may be a homopolymer of propylene (homopolypropylene, hPP), or a propylene-based copolymer having structural units derived from propylene and structural units derived from a monomer other than propylene.

[0049] Examples of the propylene-based copolymer contained in the first resin layer include propylene-ethylene random copolymers (also known as polypropylene random copolymers (rPP)), propylene-ethylene block copolymers (also known as polypropylene block copolymers (bPP)), and the like.

[0050] The polyolefin resin contained in the first resin layer may be one kind or two or more kinds, and when two or more kinds are contained, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0051] The melting point of the polyolefin resin contained in the first resin layer is preferably 75 to 130°C, more preferably 80 to 128°C, and even more preferably 85 to 126°C. When the melting point of the polyolefin resin is in this range, the properties of the first resin layer are improved. For example, when the first resin layer is a sealant layer, when the melting point of the polyolefin resin is equal to or higher than the lower limit, the seal strength of the laminate film to the object to be heat-sealed is increased within an appropriate range. When the melting point of the polyolefin resin is equal to or lower than the upper limit, the effect of suppressing melting of the object to be heat-sealed when the laminate film is heat-sealed is enhanced.

[0052] In this specification, the term "melting point" refers to a value measured in accordance with JIS K 7121 unless otherwise specified.

[0053] The melt flow rate (sometimes referred to as "MFR" herein) of the polyolefin resin contained in the first resin layer is preferably 2 to 20 g / 10 min, more preferably 2.5 to 16 g / 10 min, and even more preferably 3 to 14 g / 10 min. When the MFR of the polyolefin resin is within this range, the properties of the first resin layer are improved. For example, when the MFR of the polyolefin resin is equal to or greater than the lower limit, the thickness variation of the first resin layer is highly suppressed. On the other hand, when the MFR of the polyolefin resin is equal to or less than the upper limit, adhesion of foreign matter originating from the laminate film to the hot plate used for molding is suppressed during heat molding of the laminate film, and contamination of the molding equipment is highly suppressed.

[0054] In this specification, unless otherwise specified, "MFR" refers to a value measured in accordance with JIS K 6922-1.

[0055] The first resin layer may or may not contain other components that do not fall under the category of polyolefin-based resins, as long as the effects of the present invention are not impaired. The other components contained in the first resin layer may be either resin components (sometimes referred to as "other resin components" in this specification) or non-resin components (sometimes referred to as "other non-resin components" in this specification).

[0056] The other resin component contained in the first resin layer is not particularly limited as long as it is a resin other than the polyolefin-based resin.

[0057] Examples of the other non-resin components contained in the first resin layer include additives known in the art, such as antifogging agents, antiblocking agents, antioxidants, antistatic agents, crystal nucleating agents, inorganic particles, viscosity reducers, thickeners, heat stabilizers, lubricants, infrared absorbers, and ultraviolet absorbers.

[0058] The other component contained in the first resin layer may be one kind or two or more kinds, and when there are two or more kinds, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0059] The first resin layer contains the same type of polyolefin-based resin as the polyolefin-based resin contained in the second resin layer and the third resin layer described below. In this embodiment, the term "same type of resin" is not limited to the case of polyolefin-based resins, and means that when resins having common structural units are compared, the proportion of the amount (mol) of the common structural units to the total amount (mol) of the structural units in both resins 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, saponified EVA), 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 structural units derived from ethylene to the total amount (moles) of structural units is 20 mol% or more. On the other hand, for example, propylene-ethylene random copolymer (rPP) and propylene-ethylene block copolymer (bPP), etc., in which the ratio of the amount (moles) of structural units derived from ethylene to the total amount (moles) of structural units is less than 20 mol%, are not considered to be of the same type as the low-density polyethylene, etc. In this embodiment, the ratio of the amount (moles) of common structural units to the total amount (moles) of structural units in both resins of the same type is preferably 30 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more, and may be, for example, 60 mol% or more, 70 mol% or more, or 80 mol% or more, while the ratio may be less than 100 mol%.

[0060] The first resin layer may contain only one type of polyolefin resin or two or more types of polyolefin resins of the same type. When two or more types are contained, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0061] In the first resin layer, the ratio of the content of the polyolefin-based resin to the total mass of the first resin layer ([content of polyolefin-based resin in first resin layer (parts by mass)] / [total mass of first resin layer (parts by mass)]×100) 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 this ratio is equal to or greater than the lower limit, the effect obtained by containing the polyolefin-based resin in the first resin layer is further enhanced. This ratio is usually the same as the ratio of the content of the polyolefin-based resin to the total content (parts by mass) of components that do not vaporize at room temperature in the composition for forming the first resin layer described below ([content of polyolefin-based resin in composition for forming first resin layer (parts by mass)] / [total content (parts by mass) of components that do not vaporize at room temperature in the composition for forming the first resin layer]×100).

[0062] In this specification, unless otherwise specified, the content of polyolefin-based resin in the first resin layer means the total content of polyolefin-based resin in the first resin layer that is the same type as the polyolefin-based resin contained in the second resin layer and the third resin layer, and other polyolefin-based resins.

[0063] In this specification, "room temperature" means a temperature that is neither particularly cold nor hot, that is, an ordinary temperature, and examples thereof include temperatures of 15 to 25°C.

[0064] In the first resin layer, the ratio of the total content of the polyethylene resin (e1) and the polypropylene resin (p1) to the total content of the polyolefin resin (([content (parts by mass) of the polyethylene resin (e1) in the first resin layer] + [content (parts by mass) of the polypropylene resin (p1) in the first resin layer]) / [content (parts by mass) of the polyolefin resin in the first resin layer] × 100) is preferably 80% by mass or more, more preferably 90% by mass or more, and may be, for example, any of 95% by mass or more, 97% by mass or more, and 99% by mass or more. When the ratio is equal to or greater than the lower limit, the effect obtained by the first resin layer containing the polyethylene resin (e1) or the polypropylene resin (p1) is further enhanced. For example, such a first resin layer is suitable as a sealant layer. In this case, the sealing properties of a package obtained by heat-sealing the laminate film or a molded product thereof with another resin film or a molded product thereof are improved. On the other hand, the ratio is 100% by mass or less. The ratio is usually the ratio of the total content (parts by mass) of the polyethylene resin (e1) and the polypropylene resin (p1) to the content (parts by mass) of the polyolefin resin in the composition for forming the first resin layer described below ((([content (parts by mass) of the polyethylene resin (e1) in the composition for forming the first resin layer] + [content (parts by mass) of the polypropylene resin (p1) in the composition for forming the first resin layer]) / [content (parts by mass) of the polyolefin resin in the composition for forming the first resin layer] × 100). Here, when the first resin layer or the composition for forming the first resin layer does not contain the polyethylene resin (e1), the content of the polyethylene resin (e1) in the composition for forming the first resin layer is 0 parts by mass. When the first resin layer or the composition for forming the first resin layer does not contain the polypropylene resin (p1), the content of the polypropylene resin (p1) in the composition for forming the first resin layer is 0 parts by mass.

[0065] In the first resin layer, the ratio of the content of the same type of polyolefin-based resin as the polyolefin-based resin contained in the second resin layer and the third resin layer to the total mass of the first resin layer ([content (parts by mass) of the same type of polyolefin-based resin in the first resin layer as the polyolefin-based resin contained in the second resin layer and the third resin layer] / [total mass (parts by mass) of the first resin layer] × 100) is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, and may be, for example, either 95 to 100 mass% or 99 to 100 mass%. When this ratio is equal to or greater than the lower limit, the recyclability of the laminate film is further improved. The ratio is usually the same as the ratio of the content (parts by mass) of the polyolefin-based resin of the same type as the polyolefin-based resin contained in the second resin layer and the third resin layer to the total content (parts by mass) of components that do not vaporize at room temperature in the composition for forming the first resin layer described below ([content (parts by mass) of the polyolefin-based resin of the same type as the polyolefin-based resin contained in the second resin layer and the third resin layer in the composition for forming the first resin layer] / [total content (parts by mass) of components that do not vaporize at room temperature in the composition for forming the first resin layer] × 100).

[0066] When the first resin layer is a sealant layer, this sealant layer may be a non-easy peel type sealant layer (complete seal type sealant layer) or an easy peel type sealant layer (easy peel layer).

[0067] The first resin layer, which is the non-easy peel type sealant layer, is preferably a non-easy peel type sealant layer containing, as the polyolefin-based resin, one or more kinds selected from the group consisting of polyethylene and ethylene-based copolymers (i.e., polyethylene-based resin (e1)).

[0068] The first resin layer, which is a non-easy peel sealant layer, preferably contains, as the polyolefin resin, one or more selected from the group consisting of low-density polyethylene, linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, and ethylene-vinyl acetate copolymer.

[0069] The linear low-density polyethylene (LLDPE) contained in the first resin layer, which is a non-easy peel sealant layer, is preferably a linear low-density polyethylene (C8-LLDPE) having structural units derived from octene. The metallocene-catalyzed linear low-density polyethylene (mLLDPE) contained in the first resin layer, which is a non-easy peel sealant layer, is preferably a metallocene-catalyzed linear low-density polyethylene (C8-mLLDPE) having structural units derived from octene. That is, it is more preferable that the first resin layer, which is a non-easy peel sealant layer, contains, as the polyolefin resin, one or more selected from the group consisting of low-density polyethylene, linear low-density polyethylene having structural units derived from octene, metallocene-catalyzed linear low-density polyethylene having structural units derived from octene, and ethylene-vinyl acetate copolymer.

[0070] When the first resin layer, which is a non-easy peel sealant layer, contains a polyethylene resin (e1) as the polyolefin resin, the ratio of the content of the polyethylene resin (e1) to the content of the polyolefin resin in the first resin layer ([content of polyethylene resin (e1) in the first resin layer (parts by mass)] / [content of polyolefin resin in the first resin layer (parts by mass)] × 100) is preferably 80% by mass or more, more preferably 90% by mass or more, and may be, for example, any one of 95% by mass or more, 97% by mass or more, and 99% by mass or more. When this ratio is equal to or greater than the lower limit, the first resin layer becomes a superior layer as a non-easy peel sealant layer. On the other hand, when this ratio is equal to or less than 100% by mass. The ratio is usually the same as the ratio of the content of polyethylene-based resin (e1) to the content (parts by mass) of polyolefin-based resin in the composition for forming the first resin layer described below ([content (parts by mass) of polyethylene-based resin (e1) in the composition for forming the first resin layer] / [content (parts by mass) of polyolefin-based resin in the composition for forming the first resin layer] × 100).

[0071] When the first resin layer, which is a non-easy peel type sealant layer, contains one or more polyolefin-based resins selected from the group consisting of low-density polyethylene, linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, and ethylene-vinyl acetate copolymer, the ratio of the total content of low-density polyethylene, linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, and ethylene-vinyl acetate copolymer to the content of polyolefin-based resin in the first resin layer (([low-density of the first resin layer [polyethylene content (parts by mass)] + [linear low-density polyethylene content (parts by mass) in the first resin layer] + [metallocene-catalyzed linear low-density polyethylene content (parts by mass) in the first resin layer] + [ethylene-vinyl acetate copolymer content (parts by mass) in the first resin layer] / [polyolefin resin content (parts by mass) in the first resin layer] × 100) is preferably 80% by mass or more, more preferably 90% by mass or more, and may be, for example, 95% by mass or more, 97% by mass or more, or 99% by mass or more. When this proportion is equal to or greater than the lower limit, the first resin layer becomes a superior layer as a non-easy-peel sealant layer. On the other hand, this proportion is equal to or less than 100% by mass. The ratio is usually the same as the ratio of the total content of low-density polyethylene, linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, and ethylene-vinyl acetate copolymer to the content (parts by mass) of polyolefin resin in the composition for forming a first resin layer described below (([content (parts by mass) of low-density polyethylene in composition for forming a first resin layer] + [content (parts by mass) of linear low-density polyethylene in composition for forming a first resin layer]) + [content (parts by mass) of metallocene-catalyzed linear low-density polyethylene in composition for forming a first resin layer]) + [content (parts by mass) of ethylene-vinyl acetate copolymer in composition for forming a first resin layer]) / [content (parts by mass) of polyolefin resin in composition for forming a first resin layer] × 100).Here, when the first resin layer or the composition for forming the first resin layer does not contain any component selected from the group consisting of low-density polyethylene, linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, and ethylene-vinyl acetate copolymer, the content of that component in the first resin layer or the composition for forming the first resin layer is 0 parts by mass.

[0072] As described above, the first resin layer, which is a non-easy peel sealant layer, may or may not contain other components that do not fall under the category of polyolefin-based resins, as long as the effects of the present invention are not impaired.

[0073] When the first resin layer is an easy-peel layer, it preferably contains two incompatible polyolefin resins, and is suitable as an easy-peel layer that exhibits peelability by cohesive failure.

[0074] The first resin layer, which is an easy-peel layer, is preferably an easy-peel layer containing, as two incompatible polyolefin-based resins, one or more types selected from the group consisting of polyethylene and ethylene-based copolymers (i.e., polyethylene-based resin (e1)) and one or more types selected from the group consisting of homopolypropylene and propylene-based copolymers (i.e., polypropylene-based resin (p1)).

[0075] In the first resin layer (easy peel layer) containing these two incompatible polyolefin resins, the ratio of the content of the polyethylene resin (e1) to the total content of the polyethylene resin (e1) and the polypropylene resin (p1) ([content (parts by mass) of the polyethylene resin (e1) in the first resin layer] / ([content (parts by mass) of the polyethylene resin (e1) in the first resin layer]+[content (parts by mass) of the polypropylene resin (p1) in the first resin layer])×100) is preferably 60 to 90% by mass, and may be, for example, any of 70 to 90% by mass and 80 to 90% by mass, 60 to 80% by mass and 60 to 70% by mass, or 70 to 80% by mass.

[0076] When the first resin layer, which is an easy-peel layer, contains a polyethylene resin (e1) and a polypropylene resin (p1) as the polyolefin resin, the ratio of the total content of the polyethylene resin (e1) and the polypropylene resin (p1) to the total content of the polyolefin resin in the first resin layer (([content (parts by mass) of the polyethylene resin (e1) in the first resin layer] + [content (parts by mass) of the polypropylene resin (p1) in the first resin layer]) / [content (parts by mass) of the polyolefin resin in the first resin layer] × 100) is the same as the ratio of the total content of the polyethylene resin (e1) and the polypropylene resin (p1) to the total content of the polyolefin resin in the first resin layer, as described above. When this ratio is equal to or greater than the lower limit, the first resin layer becomes a superior layer as an easy-peel layer. Furthermore, even when the first resin layer is an easy-peel layer, this ratio is equal to or less than 100% by mass.

[0077] The first resin layer, which is an easy-peel layer, preferably contains an ethylene-vinyl acetate copolymer and homopolypropylene as the polyolefin-based resin.

[0078] In the first resin layer (easy-peel layer) containing two such incompatible polyolefin resins, the ratio of the content of the ethylene-vinyl acetate copolymer to the total content of the ethylene-vinyl acetate copolymer and the homopolypropylene ([Content of ethylene-vinyl acetate copolymer in the first resin layer (parts by mass)] / ([Content of ethylene-vinyl acetate copolymer in the first resin layer (parts by mass)]+[Content of homopolypropylene in the first resin layer (parts by mass)])×100) is preferably 60 to 90% by mass, and may be, for example, any of 70 to 90% by mass and 80 to 90% by mass, 60 to 80% by mass and 60 to 70% by mass, or 70 to 80% by mass.

[0079] When the first resin layer, which is an easy-peel layer, contains an ethylene-vinyl acetate copolymer and a homopolypropylene as the polyolefin resin, the ratio of the total content of the ethylene-vinyl acetate copolymer and the homopolypropylene to the total content of the polyolefin resin in the first resin layer (([ethylene-vinyl acetate copolymer content (parts by mass) in the first resin layer] + [homopolypropylene content (parts by mass) in the first resin layer]) / [polyolefin resin content (parts by mass) in the first resin layer] × 100) is preferably 80% by mass or more, more preferably 90% by mass or more, and may be, for example, any one of 95% by mass or more, 97% by mass or more, and 99% by mass or more. When this ratio is equal to or greater than the lower limit, the first resin layer becomes a superior layer as an easy-peel layer. On the other hand, when this ratio is equal to or less than 100% by mass. The ratio is usually the same as the ratio of the total content of ethylene-vinyl acetate copolymer and homopolypropylene to the content (parts by mass) of polyolefin-based resin in the composition for forming the first resin layer described below (([content (parts by mass) of ethylene-vinyl acetate copolymer in the composition for forming the first resin layer] + [content (parts by mass) of homopolypropylene in the composition for forming the first resin layer]) / [content (parts by mass) of polyolefin-based resin in the composition for forming the first resin layer] × 100).

[0080] As described above, the first resin layer, which is an easy-peel layer, may or may not contain other components that do not fall under the category of polyolefin-based resins, as long as the effects of the present invention are not impaired.

[0081] The first resin layer may consist of one layer (single layer) or two or more layers, regardless of whether it is a non-easy peel sealant layer or an easy peel layer. When the first resin layer consists of multiple layers, these multiple layers may be the same or different from each other, and the combination of these multiple layers is not particularly limited as long as it does not impair the effects of the present invention. It is preferable that the first resin layer consists of one layer (single layer).

[0082] In this specification, not only in the case of the first resin layer, "multiple layers may be the same or different from one another" means "all layers may be the same, all layers may be different, or only some layers may be the same," and further, "multiple layers are different from one another" means "at least one of the constituent materials and thicknesses of each layer is different from one another."

[0083] Regardless of whether the first resin layer is a non-easy-peel sealant layer or an easy-peel layer, the thickness of the first resin layer can be set arbitrarily depending on the application of the laminate film and the thickness of the laminate film, and is not particularly limited. The thickness of the first resin layer is preferably 20 μm or less, and may be, for example, 15 μm or less or 10 μm or less. By having the thickness of the first resin layer equal to or less than the upper limit, the thickness of the laminate film can be made thinner. Furthermore, when the thicknesses of the second resin layer and the third resin layer are within the numerical ranges described below, a thickness of the first resin layer equal to or less than the upper limit is particularly suitable, and in such cases, the effects obtained by the laminate film including the second resin layer and the third resin layer are enhanced. On the other hand, the thickness of the first resin layer is preferably 1 μm or more, and may be, for example, 1.5 μm or more or 2 μm or more. By having the thickness of the first resin layer equal to or greater than the lower limit, the effects obtained by the laminate film including the first resin layer are enhanced. For example, when the first resin layer is a sealant layer, the sealing strength of a package obtained by heat-sealing the laminate film or a molded article thereof with another resin film or a molded article thereof is increased. When the first resin layer is composed of multiple layers, the total thickness of these multiple layers is preferably within the above-mentioned numerical range. The thickness of the first resin layer shown here is particularly suitable when the thickness of the laminate film is 60 to 250 μm, as described below.

[0084] The first resin layer is preferably a non-stretched layer (film). When the first resin layer is a non-stretched layer, the formability of the laminated film is improved.

[0085] <Second Resin Layer> The second resin layer contains the same type of polyolefin-based resin as the polyolefin-based resin contained in the first resin layer and the third resin layer described below.

[0086] In the second resin layer, the ratio of the total content of one or more later-described components of the second resin layer to the total mass of the second resin layer does not exceed 100 mass%. Similarly, in the later-described composition for forming the second resin layer, the ratio of the total content of one or more later-described components of the composition for forming the second resin layer to the total mass of the composition for forming the second resin layer does not exceed 100 mass%.

[0087] Examples of the polyolefin-based resin contained in the second resin layer include the same polyolefin-based resin as the polyolefin-based resin contained in the first resin layer described above. For example, the polyolefin-based resin contained in the second resin layer may be a homopolymer of one type of olefin or a copolymer of two or more types of olefins. For example, examples of the polyolefin-based resin contained in the second resin layer include polyethylene-based resins (in this specification, the polyethylene-based resin contained in the second resin layer may be particularly referred to as "polyethylene-based resin (e2)"), polypropylene-based resins (in this specification, the polypropylene-based resin contained in the second resin layer may be particularly referred to as "polypropylene-based resin (p2)"), and the like.

[0088] For example, the polyethylene-based resin (polyethylene-based resin (e2)) contained in the second resin layer is the same as the polyethylene-based resin (polyethylene-based resin (e1)) contained in the first resin layer, and may be polyethylene (PE, for example, a homopolymer of ethylene) or an ethylene-based copolymer having structural units derived from ethylene and structural units derived from a monomer other than ethylene. Examples of the polyethylene (PE) and ethylene-based copolymer contained in the second resin layer include the same polyethylene (PE) and ethylene-based copolymer contained in the first resin layer, respectively.

[0089] For example, the polypropylene-based resin contained in the second resin layer (polypropylene-based resin (p2)) is the same as the polypropylene-based resin contained in the first resin layer (polypropylene-based resin (p1)), and may be a homopolymer of propylene (homopolypropylene, hPP), or a propylene-based copolymer having a structural unit derived from propylene and a structural unit derived from a monomer other than propylene.

[0090] Examples of the propylene-based copolymer contained in the second resin layer include the same propylene-based copolymers as those contained in the first resin layer.

[0091] The second resin layer may contain only one type of polyolefin resin, or two or more types of polyolefin resins. When two or more types of polyolefin resins are contained, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0092] The second resin layer may or may not contain other components that do not fall under the category of polyolefin-based resins, as long as the effects of the present invention are not impaired. The other components may be either resin components (sometimes referred to as "other resin components" in this specification) or non-resin components (sometimes referred to as "other non-resin components" in this specification).

[0093] The other resin components and other non-resin components contained in the second resin layer may be the same as the other resin components and other non-resin components contained in the first resin layer, respectively.

[0094] The second resin layer may contain only one type of other component, or two or more types. When two or more types are contained, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0095] The second resin layer may contain only one type of polyolefin resin or two or more types of polyolefin resins of the same type. When two or more types are contained, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0096] In the second resin layer, the content of the polyolefin-based resin relative 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 this content is equal to or greater than the lower limit, the effect obtained by containing the polyolefin-based resin in the second resin layer is further enhanced. This content is usually the same as the content of the polyolefin-based resin relative to the total content (parts by mass) of components that do not vaporize at room temperature in the composition for forming the second resin layer, which will be described later.

[0097] In this specification, unless otherwise specified, the content of polyolefin-based resin in the second resin layer means the total content of polyolefin-based resin in the second resin layer that is the same type as the polyolefin-based resin contained in the first resin layer and the third resin layer, and other polyolefin-based resins.

[0098] The polyolefin resin contained in the second resin layer is preferably a polyethylene resin (e2) (either one or both of polyethylene and ethylene copolymer).

[0099] In the second resin layer, the ratio of the content of the polyethylene-based resin (e2) to the content of the polyolefin-based resin is preferably 80% by mass or more, more preferably 90% by mass or more, and may be, for example, any of 95% by mass or more, 97% by mass or more, and 99% by mass or more. When this ratio is equal to or greater than the lower limit, the effect obtained by the second resin layer containing the polyethylene-based resin (e2) is enhanced. For example, the pinhole resistance of such a second resin layer and the laminate film provided with the second resin layer is enhanced. Furthermore, the pinhole resistance of a package obtained using such a laminate film is also enhanced. Meanwhile, this ratio is 100% by mass or less. This ratio is usually the same as the ratio of the content (parts by mass) of the polyethylene-based resin (e2) to the content (parts by mass) of the polyolefin-based resin in the composition for forming the second resin layer described below.

[0100] In the second resin layer, the content of the same polyolefin-based resin as the polyolefin-based resin contained in the first resin layer and the third resin layer relative to the total mass of the second resin layer is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, and may be, for example, 95 to 100 mass% or 99 to 100 mass%. When this content is equal to or greater than the lower limit, the recyclability of the laminate film is further improved. This content is usually the same as the content (parts by mass) of the same polyolefin-based resin as the polyolefin-based resin contained in the first resin layer and the third resin layer relative to the total content (parts by mass) of components that do not vaporize at room temperature in the composition for forming the second resin layer, as described below.

[0101] The polyolefin resin contained in the second resin layer is more preferably polyethylene.

[0102] A more preferred example of the second resin layer is a second resin layer containing, as the polyolefin resin, one or more selected from the group consisting of high-density polyethylene and low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene. A second resin layer containing polyethylenes classified into these two groups is particularly suitable as an outer layer. By containing high-density polyethylene, the second resin layer exhibits higher heat resistance, thereby improving the heat resistance of the laminate film and packaging material comprising such a second resin layer. Meanwhile, by containing one or more selected from the group consisting of low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene, the second resin layer exhibits higher pinhole resistance and moldability. Furthermore, the pinhole resistance and moldability of the laminate film and packaging material comprising such a second resin layer are also improved.

[0103] The linear low-density polyethylene contained in the second resin layer is preferably a linear low-density polyethylene (C8-LLDPE) having structural units derived from octene, and the metallocene-catalyzed linear low-density polyethylene is preferably a metallocene-catalyzed linear low-density polyethylene (C8-mLLDPE) having structural units derived from octene. That is, a more preferred example of the second resin layer is a second resin layer containing, as the polyolefin resin, one or more selected from the group consisting of high-density polyethylene and low-density polyethylene, linear low-density polyethylene having structural units derived from octene, and metallocene-catalyzed linear low-density polyethylene having structural units derived from octene.

[0104] When the second resin layer contains, as the polyolefin resin, high-density polyethylene and one or more selected from the group consisting of low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene, the proportion of the total content of the high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene to the total content of the polyolefin resin in the second resin layer (([content of high-density polyethylene in the second resin layer (parts by mass)] + [content of low-density polyethylene in the second resin layer (parts by mass)] + [content of linear low-density polyethylene in the second resin layer (parts by mass)] + [content of metallocene-catalyzed linear low-density polyethylene in the second resin layer (parts by mass)]) / [content of polyolefin resin in the second resin layer (parts by mass)] × 100) is preferably 80% by mass or more, more preferably 90% by mass or more, and may be, for example, any one of 95% by mass or more, 97% by mass or more, and 99% by mass or more. When the ratio is equal to or greater than the lower limit, the heat resistance, pinhole resistance, and formability of the second resin layer and the laminate film including the second resin layer are improved. Furthermore, the heat resistance and pinhole resistance of a package obtained using such a laminate film are also improved, and the desired shape can be realized with high precision. Meanwhile, the ratio is 100% by mass or less. The ratio is usually the same as the ratio of the total content of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene to the content of polyolefin-based resin in the composition for forming the second resin layer described below (([content of high-density polyethylene (parts by mass) in the composition for forming the second resin layer] + [content of low-density polyethylene (parts by mass) in the composition for forming the second resin layer] + [content of linear low-density polyethylene (parts by mass) in the composition for forming the second resin layer] + [content of metallocene-catalyzed linear low-density polyethylene (parts by mass) in the composition for forming the second resin layer]) / [content of polyolefin-based resin (parts by mass) in the composition for forming the second resin layer] × 100).Here, when the second resin layer or the composition for forming the second resin layer does not contain any component selected from the group consisting of low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene, the content of that component in the second resin layer or the composition for forming the second resin layer is 0 parts by mass.

[0105] When the second resin layer contains, as the polyolefin resin, high-density polyethylene and one or more selected from the group consisting of low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene, the ratio of the content of high-density polyethylene to the total content of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene in the second resin layer ([Content of high-density polyethylene in second resin layer (parts by mass)] / ([Content of high-density polyethylene in second resin layer (parts by mass)] + [Content of low-density polyethylene in second resin layer (parts by mass)] + [Content of linear low-density polyethylene in second resin layer (parts by mass)] + [Content of metallocene-catalyzed linear low-density polyethylene in second resin layer (parts by mass)]) × 100) is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. When the ratio is equal to or greater than the lower limit, the effect obtained by the second resin layer containing high-density polyethylene is enhanced. That is, the heat resistance of the second resin layer, the laminate film, and the package is enhanced. On the other hand, the ratio is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. When the ratio is equal to or less than the upper limit, the effect obtained by the second resin layer containing low-density polyethylene, linear low-density polyethylene, or metallocene-catalyzed linear low-density polyethylene is enhanced. That is, the pinhole resistance and moldability of the second resin layer and the laminate film are enhanced. Furthermore, the pinhole resistance of the package is also enhanced, allowing the desired shape to be achieved with high precision.The ratio is usually the same as the ratio of the content of high-density polyethylene to the total content of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene in the composition for forming a second resin layer (described below) ([Content of high-density polyethylene in composition for forming a second resin layer (parts by mass)] / ([Content of high-density polyethylene in composition for forming a second resin layer (parts by mass)] + [Content of low-density polyethylene in composition for forming a second resin layer (parts by mass)] + [Content of linear low-density polyethylene in composition for forming a second resin layer (parts by mass)] + [Content of metallocene-catalyzed linear low-density polyethylene in composition for forming a second resin layer (parts by mass)]) × 100). Here, when the second resin layer or the composition for forming a second resin layer does not contain any component selected from the group consisting of low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene, the content of that component in the second resin layer or the composition for forming a second resin layer is 0 part by mass.

[0106] When the second resin layer contains, as the polyolefin resin, either one or both of a linear low-density polyethylene and a metallocene-catalyzed linear low-density polyethylene, the second resin layer may contain a linear low-density polyethylene having structural units derived from octene (C8-LLDPE) and a metallocene-catalyzed linear low-density polyethylene having structural units derived from octene (C8-LLDPE) relative to the total content of the linear low-density polyethylene and the metallocene-catalyzed linear low-density polyethylene. The ratio of the total content of the second resin layer and the second resin layer (([C8-LLDPE content (parts by mass) in the second resin layer] + [C8-mLLDPE content (parts by mass) in the second resin layer]) / ([LLDPE content (parts by mass) in the second resin layer] + [mLLDPE content (parts by mass) in the second resin layer]) × 100) is preferably 80% by mass or more, more preferably 90% by mass or more, and may be, for example, any one of 95% by mass or more, 97% by mass or more, and 99% by mass or more. When this ratio is equal to or greater than the lower limit, the heat resistance, pinhole resistance, and formability of the laminate film including such a second resin layer are further improved. Furthermore, a package obtained using such a laminate film also has further improved heat resistance and pinhole resistance, and can be formed into a desired shape with high precision. On the other hand, the ratio is 100% by mass or less. The above ratio is usually the same as the ratio of the total content of the linear low-density polyethylene having structural units derived from octene (C8-LLDPE) and the metallocene-catalyzed linear low-density polyethylene having structural units derived from octene (C8-mLLDPE) to the total content of the linear low-density polyethylene and the metallocene-catalyzed linear low-density polyethylene in the composition for forming the second resin layer described below (([C8-LLDPE content (parts by mass) in the composition for forming the second resin layer] + [C8-mLLDPE content (parts by mass) in the composition for forming the second resin layer]) / ([LLDPE content (parts by mass) in the composition for forming the second resin layer] + [mLLDPE content (parts by mass) in the composition for forming the second resin layer]) × 100).Here, when the second resin layer or the composition for forming the second resin layer does not contain any component selected from the group consisting of linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, linear low-density polyethylene having structural units derived from octene, and metallocene-catalyzed linear low-density polyethylene having structural units derived from octene, the content of that component in the second resin layer or the composition for forming the second resin layer is 0 parts by mass.

[0107] The second resin layer may consist of one layer (single layer) or two or more layers. When the second resin layer consists of multiple layers, these multiple layers may be the same or different from each other, and the combination of these multiple layers is not particularly limited as long as it does not impair the effects of the present invention. It is preferable that the second resin layer consists of one layer (single layer).

[0108] The thickness of the second resin layer can be set arbitrarily depending on the application of the laminate film and the thickness of the laminate film, and is not particularly limited. The thickness of the second resin layer is preferably 20 μm or less, and may be, for example, 15 μm or less or 10 μm or less. By having the thickness of the second resin layer equal to or less than the upper limit, the thickness of the laminate film can be made thinner. When the thickness of the first resin layer is within the above-mentioned numerical range and the thickness of the third resin layer is within the numerical range described below, a thickness of the second resin layer equal to or less than the upper limit is particularly suitable, and in such cases, the effects obtained by the laminate film including the first resin layer and the third resin layer are further enhanced. On the other hand, the thickness of the second resin layer is preferably 1 μm or more, and may be, for example, 1.5 μm or more or 2 μm or more. When the thickness of the second resin layer is equal to or greater than the above-mentioned lower limit, the effects obtained by the laminate film including the second resin layer are further enhanced. For example, the pinhole resistance of the laminate film is improved. When the second resin layer is composed of multiple layers, it is preferable that the total thickness of these multiple layers is within the above-mentioned numerical range. The thickness of the second resin layer shown here is particularly suitable when the thickness of the laminated film is 60 to 250 μm, as will be described later.

[0109] The second resin layer is preferably a non-stretched layer (film). When the second resin layer is a non-stretched layer, the formability of the laminated film is improved.

[0110] <Third Resin Layer> The third resin layer contains the same type of polyolefin-based resin as the polyolefin-based resin contained in the first resin layer and the second resin layer.

[0111] In the third resin layer, the ratio of the total content of one or more later-described components contained in the third resin layer to the total mass of the third resin layer does not exceed 100 mass%. Similarly, in the later-described composition for forming the third resin layer, the ratio of the total content of one or more later-described components contained in the composition for forming the third resin layer to the total mass of the composition for forming the third resin layer does not exceed 100 mass%.

[0112] Examples of the polyolefin-based resin contained in the third resin layer include the same polyolefin-based resins as those contained in the first resin layer described above. For example, the polyolefin-based resin contained in the third resin layer may be a homopolymer of one type of olefin or a copolymer of two or more types of olefins. For example, examples of the polyolefin-based resin contained in the third resin layer include polyethylene-based resins (in this specification, the polyethylene-based resin contained in the third resin layer may be particularly referred to as "polyethylene-based resin (e3)"), polypropylene-based resins (in this specification, the polypropylene-based resin contained in the third resin layer may be particularly referred to as "polypropylene-based resin (p3)"), and the like.

[0113] For example, the polyethylene-based resin (polyethylene-based resin (e3)) contained in the third resin layer is the same as the polyethylene-based resin (polyethylene-based resin (e1)) contained in the first resin layer, and may be polyethylene (PE, for example, a homopolymer of ethylene) or an ethylene-based copolymer having structural units derived from ethylene and structural units derived from a monomer other than ethylene. Examples of the polyethylene (PE) and ethylene-based copolymer contained in the third resin layer are the same as the polyethylene (PE) and ethylene-based copolymer contained in the first resin layer, respectively.

[0114] For example, the polypropylene-based resin contained in the third resin layer (polypropylene-based resin (p3)) is the same as the polypropylene-based resin contained in the first resin layer (polypropylene-based resin (p1)), and may be a homopolymer of propylene (homopolypropylene, hPP), or a propylene-based copolymer having a structural unit derived from propylene and a structural unit derived from a monomer other than propylene.

[0115] Examples of the propylene-based copolymer contained in the third resin layer include the same propylene-based copolymers as those contained in the first resin layer.

[0116] The third resin layer may contain only one type of polyolefin resin, or two or more types of polyolefin resins. When two or more types of polyolefin resins are contained, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0117] The third resin layer may or may not contain other components that do not fall under the category of polyolefin-based resins, as long as the effects of the present invention are not impaired. The other components may be either resin components (sometimes referred to as "other resin components" in this specification) or non-resin components (sometimes referred to as "other non-resin components" in this specification).

[0118] The other resin components and other non-resin components contained in the third resin layer may be the same as the other resin components and other non-resin components contained in the first resin layer, respectively.

[0119] The other component contained in the third resin layer may be one kind or two or more kinds, and when there are two or more kinds, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0120] The third resin layer may contain only one type of polyolefin resin or two or more types of polyolefin resins of the same type. When two or more types are contained, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0121] In the third resin layer, the content of the polyolefin-based resin relative 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 this content is equal to or greater than the lower limit, the effect obtained by containing the polyolefin-based resin in the third resin layer is further enhanced. This content is usually the same as the content of the polyolefin-based resin relative to the total content (parts by mass) of components that do not vaporize at room temperature in the composition for forming the third resin layer, which will be described later.

[0122] In this specification, unless otherwise specified, the content of polyolefin-based resin in the third resin layer means the total content of polyolefin-based resin in the third resin layer that is the same type as the polyolefin-based resin contained in the first resin layer and the second resin layer, and other polyolefin-based resins.

[0123] The polyolefin resin contained in the third resin layer is preferably a resin other than an adhesive resin (adhesive polyolefin resin). The lower the content of the adhesive resin in the third resin layer, the better, and it is particularly preferable that the third resin layer does not contain the adhesive resin. In such a package, the effects obtained by providing the third resin layer are enhanced. Examples of the adhesive resin include known adhesive resins, and more specifically, examples include modified polyolefins such as acid-modified polyolefins having acidic groups. In the third resin layer, the proportion of the adhesive resin content relative to the total mass of the third resin layer is preferably 0 to 5% by mass, more preferably 0 to 3% by mass, and even more preferably 0 to 1% by mass.

[0124] The polyolefin resin contained in the third resin layer is preferably a polyethylene resin (e3) (either one or both of polyethylene and ethylene copolymer).

[0125] In the third resin layer, the ratio of the content of the polyethylene-based resin (e3) to the content of the polyolefin-based resin is preferably 80% by mass or more, more preferably 90% by mass or more, and may be, for example, any of 95% by mass or more, 97% by mass or more, and 99% by mass or more. When this ratio is equal to or greater than the lower limit, the effect obtained by the third resin layer containing the polyethylene-based resin (e3) is enhanced. For example, the puncture strength of such a third resin layer, the laminate film including the third resin layer, and a package obtained using the laminate film is enhanced. Meanwhile, this ratio is 100% by mass or less. This ratio is usually the same as the ratio of the content (parts by mass) of the polyethylene-based resin (e3) to the content (parts by mass) of the polyolefin-based resin in the composition for forming the third resin layer described below.

[0126] In the third resin layer, the content of the same polyolefin-based resin as the polyolefin-based resin contained in the first resin layer and the second resin layer relative to the total mass of the third resin layer is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, and may be, for example, 95 to 100 mass% or 99 to 100 mass%. When this content is equal to or greater than the lower limit, the recyclability of the laminate film is further improved. This content is usually the same as the content (parts by mass) of the same polyolefin-based resin as the polyolefin-based resin contained in the first resin layer and the second resin layer relative to the total content (parts by mass) of components that do not vaporize at room temperature in the composition for forming the third resin layer, described below.

[0127] The polyolefin resin contained in the third resin layer is more preferably polyethylene.

[0128] A more preferred example of the third resin layer is a third resin layer containing, as the polyolefin resin, either one or both of linear low-density polyethylene and metallocene-catalyzed linear low-density polyethylene, which further increases the puncture strength of the laminate film including such a third resin layer and the package obtained using the laminate film.

[0129] The linear low-density polyethylene contained in the third resin layer is preferably a linear low-density polyethylene (C8-LLDPE) having structural units derived from octene, and the metallocene-catalyzed linear low-density polyethylene is preferably a metallocene-catalyzed linear low-density polyethylene (C8-mLLDPE) having structural units derived from octene. That is, a more preferred example of the third resin layer is a third resin layer containing, as the polyolefin resin, either or both of a linear low-density polyethylene (C8-LLDPE) having structural units derived from octene and a metallocene-catalyzed linear low-density polyethylene (C8-mLLDPE) having structural units derived from octene. The puncture strength of a laminate film including such a third resin layer is particularly high.

[0130] When the third resin layer contains either or both of linear low-density polyethylene and metallocene-catalyzed linear low-density polyethylene as the polyolefin-based resin, the ratio of the total content of the linear low-density polyethylene and the metallocene-catalyzed linear low-density polyethylene to the total content of the polyolefin-based resin in the third resin layer (([content of linear low-density polyethylene in the third resin layer (parts by mass)] + [content of metallocene-catalyzed linear low-density polyethylene in the third resin layer (parts by mass)]) / [content of polyolefin-based resin in the third resin layer (parts by mass)] × 100) is preferably 80% by mass or more, more preferably 90% by mass or more, and may be, for example, any of 95% by mass or more, 97% by mass or more, and 99% by mass or more. When this ratio is equal to or greater than the lower limit, the puncture strength of such a third resin layer, the laminate film including the third resin layer, and a package obtained using the laminate film is further increased. On the other hand, when this ratio is equal to or less than 100% by mass. The ratio is usually the same as the ratio of the total content of linear low-density polyethylene and metallocene-catalyzed linear low-density polyethylene to the content of polyolefin resin in the composition for forming the third resin layer described below (([content of linear low-density polyethylene in the composition for forming the third resin layer (parts by mass)] + [content of metallocene-catalyzed linear low-density polyethylene in the composition for forming the third resin layer (parts by mass)]) / [content of polyolefin resin in the composition for forming the third resin layer (parts by mass)] × 100). Here, the content of linear low-density polyethylene in the third resin layer and the composition for forming the third resin layer refers to the total content of linear low-density polyethylene having a structural unit derived from octene and other linear low-density polyethylene in the third resin layer and the composition for forming the third resin layer. Similarly, the content of metallocene-catalyzed linear low-density polyethylene in the third resin layer and the composition for forming the third resin layer is the total content of metallocene-catalyzed linear low-density polyethylene having a structural unit derived from octene and other metallocene-catalyzed linear low-density polyethylene in the third resin layer and the composition for forming the third resin layer.Furthermore, when the third resin layer or the composition for forming the third resin layer does not contain any component selected from the group consisting of linear low-density polyethylene having structural units derived from octene, other linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene having structural units derived from octene, and other metallocene-catalyzed linear low-density polyethylene, the content of that component in the third resin layer or the composition for forming the third resin layer is 0 parts by mass.

[0131] When the third resin layer contains, as the polyolefin resin, either one or both of a linear low-density polyethylene and a metallocene-catalyzed linear low-density polyethylene, the third resin layer may contain a linear low-density polyethylene having structural units derived from octene (C8-LLDPE) and a metallocene-catalyzed linear low-density polyethylene having structural units derived from octene (C8-LLDPE) relative to the total content of the linear low-density polyethylene and the metallocene-catalyzed linear low-density polyethylene. The ratio of the total content of the C8-LLDPE in the third resin layer and the C8-mLLDPE (parts by mass) in the third resin layer ((([C8-LLDPE content (parts by mass) in the third resin layer)] + [C8-mLLDPE content (parts by mass) in the third resin layer]) / ([LLDPE content (parts by mass) in the third resin layer] + [mLLDPE content (parts by mass) in the third resin layer]) × 100) is preferably 50% by mass or more, and may be, for example, 75% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, 97% by mass or more, or 99% by mass or more. When this ratio is equal to or greater than the lower limit, the puncture strength of such a third resin layer, the laminate film including the third resin layer, and a package obtained using the laminate film becomes particularly high. On the other hand, the ratio is 100% by mass or less. The ratio is usually the same as the ratio of the total content of the linear low-density polyethylene having structural units derived from octene (C8-LLDPE) and the metallocene-catalyzed linear low-density polyethylene having structural units derived from octene (C8-mLLDPE) to the total content of the linear low-density polyethylene and the metallocene-catalyzed linear low-density polyethylene in the composition for forming a third resin layer described below (([C8-LLDPE content (parts by mass) in the composition for forming a third resin layer] + [C8-mLLDPE content (parts by mass) in the composition for forming a third resin layer]) / ([LLDPE content (parts by mass) in the composition for forming a third resin layer] + [mLLDPE content (parts by mass) in the composition for forming a third resin layer]) × 100).Here, when the third resin layer or the composition for forming the third resin layer does not contain any component selected from the group consisting of linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, linear low-density polyethylene having structural units derived from octene, and metallocene-catalyzed linear low-density polyethylene having structural units derived from octene, the content of that component in the third resin layer or the composition for forming the third resin layer is 0 parts by mass.

[0132] The third resin layer may consist of one layer (single layer) or two or more layers. When the third resin layer consists of multiple layers, these multiple layers may be the same or different from each other, and the combination of these multiple layers is not particularly limited as long as it does not impair the effects of the present invention. The third resin layer is preferably composed of one layer (single layer).

[0133] The thickness of the third resin layer can be set arbitrarily depending on the application of the laminate film and the thickness of the laminate film, and is not particularly limited. The thickness of the third resin layer is preferably 50 μm or more, and may be, for example, 100 μm or more or 150 μm or more. When the thickness of the third resin layer is equal to or greater than the lower limit, the effect obtained by including the third resin layer in the laminate film is enhanced. That is, the puncture strength of the laminate film and the package obtained using the laminate film is enhanced. On the other hand, the thickness of the third resin layer is preferably 240 μm or less, and may be, for example, 185 μm or less or 125 μm or less. When the thickness of the third resin layer is equal to or less than the upper limit, the thickness of the laminate film can be further reduced. When the thicknesses of the first resin layer and the second resin layer are within the above-mentioned numerical ranges, a thickness of the third resin layer equal to or less than the upper limit is particularly preferable, and in that case, the effect obtained by including the first resin layer and the second resin layer in the laminate film is enhanced. When the third resin layer is made up of multiple layers, the total thickness of these multiple layers is preferably within the above-mentioned range. The thickness of the third resin layer shown here is particularly suitable when the thickness of the laminated film is 60 to 250 μm, as described below.

[0134] The third resin layer is preferably a non-stretched layer (film). When the third resin layer is a non-stretched layer, the formability of the laminated film is improved.

[0135] <Other Layers> The laminate film of this embodiment may have another layer that does not fall under 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 laminate film does not have the other layer. The other layer is a layer that does not contain the same type of polyolefin resin. By not having such other layers, the laminate film has higher recyclability and can more easily adjust its puncture strength and pinhole resistance.

[0136] <Overall Structure of Laminate Film> The thickness (overall thickness) of the laminate film is not particularly limited, but is preferably 60 to 250 μm, and may be, for example, any of 60 to 130 μm, 120 to 190 μm, and 180 to 250 μm. When the thickness of the laminate film is equal to or greater than the lower limit, the strength of the laminate film becomes higher. When the thickness of the laminate film is equal to or less than the upper limit, the laminate film can be made thinner.

[0137] In the laminate film, it is preferable that all of the layers constituting the laminate film (e.g., the first resin layer, the second resin layer, and the third resin layer) are unstretched layers (films). Such unstretched laminate films are particularly excellent in formability and are particularly suitable for forming deep-draw packaging products, for example.

[0138] The first resin layer, the second resin layer, and the third resin layer each preferably contain a polyethylene resin as the same type of polyolefin resin. In this case, for example, the first resin layer preferably contains one or more polyolefin resins selected from the group consisting of low-density polyethylene, linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, and ethylene-vinyl acetate copolymer, the second resin layer preferably contains one or more polyolefin resins selected from the group consisting of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene, and the third resin layer preferably contains one or both of linear low-density polyethylene and metallocene-catalyzed linear low-density polyethylene as the same type of polyolefin resin. Furthermore, in this case, part or all of the linear low-density polyethylene in each of the first resin layer, the second resin layer, and the third resin layer may be a linear low-density polyethylene (C8-LLDPE) having structural units derived from octene, or part or all of the metallocene-catalyzed linear low-density polyethylene may be a metallocene-catalyzed linear low-density polyethylene (C8-LLDPE) having structural units derived from octene.

[0139] An example of a preferred laminate film of the present embodiment is a laminate film constructed by laminating a first resin layer, a third resin layer, and a second resin layer in this order in the thickness direction, wherein the first resin layer, the second resin layer, and the third resin layer contain the same type of polyolefin-based resin, the ratio of the thickness of the third resin layer to the thickness of the laminate film is more than 85%, the ratio of the thickness of the first resin layer to the thickness of the laminate film is 7.5% or less, and the ratio of the thickness of the second resin layer to the thickness of the laminate film is 7.5% or less, when the laminate film is subjected to a Gelbo Flex test in accordance with ASTM F392 at a temperature of 23°C and 2000 twists, the number of pinholes observed in the laminate film after the Gelbo Flex test is 2 or less, and the puncture strength of the laminate film is 6N or more, and the second resin layer and the third resin layer contain polyethylene-based resins as the polyolefin-based resins, The laminate film may be such that the first resin layer is a non-easy peel sealant layer containing a polyethylene resin as the polyolefin resin, or an easy peel layer containing a polyethylene resin and a polypropylene resin as the polyolefin resin, and the first resin layer, the second resin layer, and the third resin layer each contain a polyethylene resin as the same type of polyolefin resin.

[0140] A more preferred example of the laminate film of this embodiment is a laminate film constructed by laminating a first resin layer, a third resin layer, and a second resin layer in this order in the thickness direction, wherein the first resin layer, the second resin layer, and the third resin layer contain the same type of polyolefin resin, the ratio of the thickness of the third resin layer to the thickness of the laminate film is more than 85%, the ratio of the thickness of the first resin layer to the thickness of the laminate film is 7.5% or less, and the ratio of the thickness of the second resin layer to the thickness of the laminate film is 7.5% or less, when the laminate film is subjected to a Gelbo flex test in accordance with ASTM F392 under conditions of a temperature of 23°C and 2000 twists, the number of pinholes observed in the laminate film after the Gelbo flex test is 2 or less, and the puncture strength of the laminate film is 6N or more, the second resin layer comprises, as the polyolefin-based resin, one or more selected from the group consisting of high-density polyethylene and low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene; the third resin layer comprises, as the polyolefin-based resin, either one or both of linear low-density polyethylene and metallocene-catalyzed linear low-density polyethylene; the first resin layer is a non-easy-peel sealant layer comprising, as the polyolefin-based resin, one or more selected from the group consisting of polyethylene and ethylene-based copolymers, or an easy-peel layer comprising, as the polyolefin-based resin, one or more selected from the group consisting of polyethylene and ethylene-based copolymers, and one or more selected from the group consisting of homopolypropylene and propylene-based copolymers;an example of a laminated film in which the first resin layer contains, as the same type of polyolefin-based resin, one or more types selected from the group consisting of polyethylene and ethylene-based copolymers; the second resin layer contains, as the same type of polyolefin-based resin, one or more types selected from the group consisting of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene; and the third resin layer contains, as the same type of polyolefin-based resin, either one or both of linear low-density polyethylene and metallocene-catalyzed linear low-density polyethylene.

[0141] A more preferred example of the laminate film of this embodiment is a laminate film constructed by laminating a first resin layer, a third resin layer, and a second resin layer in this order in the thickness direction, wherein the first resin layer, the second resin layer, and the third resin layer contain the same type of polyolefin resin, the ratio of the thickness of the third resin layer to the thickness of the laminate film is more than 85%, the ratio of the thickness of the first resin layer to the thickness of the laminate film is 7.5% or less, and the ratio of the thickness of the second resin layer to the thickness of the laminate film is 7.5% or less, when the laminate film is subjected to a Gelbo flex test in accordance with ASTM F392 under conditions of a temperature of 23°C and 2000 twists, the number of pinholes observed in the laminate film after the Gelbo flex test is 2 or less, and the puncture strength of the laminate film is 6N or more, the second resin layer comprises, as the polyolefin-based resin, one or more selected from the group consisting of high-density polyethylene and low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene; the third resin layer comprises, as the polyolefin-based resin, either one or both of linear low-density polyethylene having structural units derived from octene and metallocene-catalyzed linear low-density polyethylene having structural units derived from octene; the first resin layer is a non-easy-peel sealant layer comprising, as the polyolefin-based resin, one or more selected from the group consisting of low-density polyethylene, linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, and ethylene-vinyl acetate copolymer, or is an easy-peel layer comprising, as the polyolefin-based resin, ethylene-vinyl acetate copolymer and homopolypropylene;an ethylene-vinyl acetate copolymer, the second resin layer comprising, as the same type of polyolefin-based resin, one or more selected from the group consisting of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene; and the third resin layer comprising, as the same type of polyolefin-based resin, either one or both of the linear low-density polyethylene having structural units derived from octene and the metallocene-catalyzed linear low-density polyethylene having structural units derived from octene. In such a laminate film, some or all of the linear low-density polyethylene contained in the first resin layer may be linear low-density polyethylene having structural units derived from octene, some or all of the metallocene-catalyzed linear low-density polyethylene may be metallocene-catalyzed linear low-density polyethylene having structural units derived from octene, some or all of the linear low-density polyethylene contained in the second resin layer may be linear low-density polyethylene having structural units derived from octene, or some or all of the metallocene-catalyzed linear low-density polyethylene may be metallocene-catalyzed linear low-density polyethylene having structural units derived from octene. Furthermore, in such a laminate film, some or all of the linear low-density polyethylene contained in the first resin layer and the second resin layer as the same type of polyolefin-based resin may be linear low-density polyethylene having structural units derived from octene, or some or all of the metallocene-catalyzed linear low-density polyethylene may be metallocene-catalyzed linear low-density polyethylene having structural units derived from octene.

[0142] <<Method for Producing Laminated Film>> The laminated film can be produced, for example, by a feed block method in which resins or resin compositions, etc., which are materials for forming each layer, are 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.

[0143] When the resin composition is used, for example, a blend (dry blend, non-kneaded product) of two or more components may be directly fed into the extruder as the resin composition, or a pre-kneaded product in which two or more components are kneaded in advance may be fed into the extruder as the resin composition. The pre-kneaded product can be obtained, for example, by melt-kneading two or more components using an apparatus such as a twin-screw extruder or a Banbury mixer.

[0144] The laminated film can also be produced by separately preparing two or more films for constituting any two or more of the layers in advance, laminating them together by a thermal lamination method or the like without using an adhesive, and further laminating other layers as needed to achieve the desired arrangement.

[0145] The resin composition used to form any layer in the laminated film may be produced by adjusting the types and contents of the components contained therein so that the layer to be formed contains the desired components in the desired amounts. 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.

[0146] Examples of the resin composition for forming the first resin layer (first resin layer 11 in the laminate film 1 shown in FIG. 1 ) (sometimes referred to herein as a “first resin layer-forming composition”), the resin composition for forming the second resin layer (second resin layer 12 in the laminate film 1 shown in FIG. 1 ) (sometimes referred to herein as a “second resin layer-forming composition”), and the resin composition for forming the third resin layer (third resin layer 13 in the laminate film 1 shown in FIG. 1 ) (sometimes referred to herein as a “third resin layer-forming composition”) each include a resin composition containing the polyolefin resin and, if necessary, the other components. The other components are the components described above.

[0147] <<Packaging>> A packaging according to one embodiment of the present invention is constructed using the laminate film according to one embodiment of the present invention described above. Because the packaging according to this embodiment is constructed using the laminate film, it has high pinhole resistance. For example, even if a twisting force is applied to the packaging, the occurrence of pinholes (breakage) is suppressed, and the packaging according to this embodiment has high torsion resistance. Furthermore, the packaging according to this embodiment has high puncture strength. For example, even if a sharp part is present on the stored item and such a part hits the packaging, breakage of the packaging is suppressed. Furthermore, by using the laminate film having high formability or heat resistance, it is also possible to enhance the formability or heat resistance of the packaging according to this embodiment.

[0148] Because the packaging body of this embodiment has the above-described properties, it is useful, for example, as a packaging body for packaging objects while maintaining a high level of hygiene, and is particularly useful for packaging medical devices such as catheters and syringes.

[0149] The packaging body of this embodiment may be a known packaging body except that the laminated film is used.

[0150] A preferred example of a package of this embodiment is a package including a lid and a base, which are formed by sealing the lid and base, and one or both of which are formed using the laminate film. The base may be, for example, a molded resin film having a recess for forming a storage section in the package. The resin film may be the laminate film, or may be a resin film other than the laminate film.

[0151] Since the laminated film can have high formability during heat molding, a more preferred package is one in which the base material is a molded product of the laminated film. That is, a more preferred package of this embodiment is one that includes a lid material and a base material, is configured by sealing the lid material and the base material, and the base material is a molded product of the laminated film.

[0152] When the base material is a molded product of the laminate film, the lid material may be the laminate film or a resin film other than the laminate film, whereas when the base material is not a molded product of the laminate film, the lid material is the laminate film.

[0153] The base material is preferably a deep-drawn molded product of the laminate film or another resin film, and more preferably a deep-drawn molded product of the laminate film. That is, the package of this embodiment including the lid material and the packaging material is preferably a deep-drawn package, and more preferably a deep-drawn package in which the base material is a deep-drawn molded product of the laminate film. Such deep-drawn packages have high pinhole resistance and puncture strength, and by using the laminate film, which has high formability, the desired shape can be achieved with high precision in the base material. Furthermore, the heat resistance of the base material can also be improved.

[0154] Fig. 2 is a cross-sectional view schematically showing an example of a packaging body according to the present embodiment. In Fig. 2, the same components as those shown in Fig. 1 are denoted by the same reference numerals as in Fig. 1, and detailed description thereof will be omitted.

[0155] The package 101 shown in Fig. 2 is configured to include a lid material 8 and a base material 10. The base material 10 is configured using the laminate film 1 shown in Fig. 1, and more specifically, is a molded body (heat-molded body) of the laminate film 1. In Fig. 2, the distinction between the layers of the laminate film 1 that constitute the base material 10 is omitted.

[0156] A recess 100 is formed in the base material 10. One surface 10b of the base material 10 (sometimes referred to herein as the "second surface") and one surface 8b of the lid material 8 (sometimes referred to herein as the "second surface") are both sealing surfaces, and they face each other in the package 101. In the package 101, the second surface 10b of the base material 10, excluding the area where the recess 100 is formed, is overlapped with an area of ​​the second surface 8b of the lid material 8 near the peripheral edge. Of the overlapping areas of the base material 10 and the lid material 8, at least the areas near the peripheral edge are sealed to form the package 101. As a result, a storage section 101a is formed between the second surface 10b of the base material 10 and the second surface 8b of the lid material 8 in the area of ​​the recess 100 of the base material 10. An item 9 is stored in this storage section 101a.

[0157] The thickness of the base material 10 at its flat portion may be the same as the thickness of the laminated film described above. The thickness of the lid material 8 is preferably 50 to 300 μm.

[0158] The second surface 10b of the base material 10 is preferably the same as the second surface 11b of the first resin layer 11 in the laminate film 1. The other surface 10a of the base material 10 (sometimes referred to as the "first surface" in this specification) is preferably the same as the first surface 12a of the second resin layer 12 in the laminate film 1.

[0159] The lid material 8 may be the laminate film or a resin film other than the laminate film. When the lid material 8 is the laminate film, the lid material 8 may be the laminate film 1 shown in FIG. 1 or another laminate film.

[0160] In Figure 2, some gaps can be seen between the stored item 9 and the base material 10, and between the stored item 9 and the lid material 8 within the storage section 101a of the packaging body 101, but the presence of these gaps is not essential for the packaging body 101 in which the stored item 9 is stored.

[0161] The packaging body of this embodiment is not limited to the packaging body 101 shown in Fig. 2 , and for example, the packaging body 101 may have some components changed, deleted, or added without departing from the spirit of the present invention. For example, in the packaging body 101, the base material 10 is made using the laminate film 1 shown in Fig. 1 , but may be made using a laminate film of this embodiment other than the laminate film 1. For example, in the packaging body 101, the base material 10 is made using the laminate film 1 shown in Fig. 1 , but may be made using a resin film other than the laminate film of this embodiment. In that case, however, the lid material 8 is the laminate film of this embodiment.

[0162] <<Method for manufacturing a package>> The package can be manufactured by using the laminate film to package an object to be packaged (in other words, a stored item). The package can be manufactured by the same method as for conventional packages, except that the laminate film is used instead of a conventional resin film. When manufacturing the package, the first resin layer in the laminate film or a molded product thereof is arranged to face the object to be packaged, and the second resin layer is arranged to face the opposite side from the object to be packaged, and the object to be packaged is packaged.

[0163] In the case of a deep-drawn package, for example, a deep-drawn molded body of the laminated film (i.e., base material) and the laminated film or another resin film (i.e., lid material) form a storage section for storing the packaged item (in other words, the contents), and the packaged item is stored while the molded body and the film are heat-sealed in areas other than the storage section, thereby producing a deep-drawn package.

[0164] Not only in the case of deep-drawn packages, but also when manufacturing packages, the sealing temperature during heat sealing is preferably 105 to 135°C, and the sealing pressure is preferably 0.3 to 0.6 MPa.

[0165] Not only in the case of a deep-drawn package, but also when the base material is produced by heat-forming the laminated film, the heat-forming can be carried out by a known method. For example, the forming temperature during heat-forming is preferably 90 to 120°C.

[0166] The present invention will be described in more detail below with reference to specific examples, although the present invention is not limited to the examples shown below.

[0167] The resins used in each example or comparative example are as follows: LLDPE: Linear low-density polyethylene having structural units derived from octene ("ELITE 5220G" manufactured by The Dow Chemical Company, density 0.915 g / cm ３ , MFR 3.5 g / 10 min, melting point 123 ° C.) LDPE: low-density polyethylene (Sumitomo Chemical Co., Ltd. "Sumikathen (registered trademark) L211", density 0.924 g / cm ３ , MFR 2 g / 10 min, melting point 112 ° C.) HDPE: high-density polyethylene ("Hi-Zex 2200J" manufactured by Prime Polymer Co., Ltd., density 0.964 g / cm ３ , MFR 5.2 g / 10 min, melting point 133°C) hPP: homopolypropylene (Prime Polypro F-300SP manufactured by Prime Polymer Co., Ltd., melting point 163°C) EVA: ethylene-vinyl acetate copolymer (Evaflex (registered trademark) P1007 manufactured by Mitsui-Dow Polychemicals Co., Ltd., melting point 94°C, MFR 9.0 g / 10 min) Ny: 6-nylon (1022B manufactured by UBE) Modified PE: acid-modified polyethylene (adhesive resin, NF536 manufactured by Mitsui Chemicals, Inc.)

[0168] Example 1 Production of Resin Composition The HDPE (50 parts by mass) and the LLDPE (50 parts by mass) were mixed at room temperature to produce a resin composition (1).

[0169] <<Production of Laminated Film>> A laminated film having the configuration shown in Figure 1 was produced by the following procedure. That is, the LLDPE, the LLDPE, and the resin composition (1) were co-extruded in this order to obtain a laminated film (thickness 150 µm) in which a first resin layer (thickness 7.5 µm), a third resin layer (thickness 135 µm), and a second resin layer (thickness 7.5 µm) were laminated in this order in the thickness direction. The first resin layer, the third resin layer, and the second resin layer were all unstretched layers.

[0170] <<Evaluation of Laminate Film>> <Evaluation of Pinhole Resistance> A first test piece measuring the standard A4 size paper (210 mm x 297 mm) was cut out from the laminate film obtained above. A Gelbo Flex test was performed on the first test piece in accordance with ASTM F392 at a temperature of 23°C and 2,000 twists. After the test, the first test piece was visually observed to determine the number of pinholes found in the first test piece (laminated film). The pinhole resistance of the laminate film was evaluated according to the following criteria. The results are shown in Table 1 in the "Pinhole Resistance of Laminate Film (Number of Pinholes)" column, along with the number of pinholes. (Evaluation Criteria) A: The number of pinholes was 0 to 1, indicating that the laminate film had extremely high pinhole resistance. B: The number of pinholes was 2, indicating that the laminate film had high pinhole resistance. C: The number of pinholes was 3 or more, indicating that the laminate film had low pinhole resistance.

[0171] <Measurement of puncture strength> The tip of a stainless steel needle with a tip radius of curvature of 0.5 mm was thrust into the laminate film obtained above from the second resin layer side and pushed perpendicularly into the laminate film at a speed of 50 mm / min. The load applied to the needle was then read at the moment the needle penetrated the laminate film, and this reading was used as the puncture strength of the laminate film. The results are shown in the column "Puncture strength (N) of laminate film" in Table 1.

[0172] <<Manufacturing of Package>> <Manufacturing of Base Material> The laminated film obtained above was hot-formed using a deep-draw packaging machine ("R535" manufactured by MULTIVAC) and a mold measuring 108 mm in length and 150 mm in width at a forming temperature of 95°C and a drawing depth of 30 mm to produce a base material.

[0173] <Production of Package> A medical packaging material (Tyvek (registered trademark) 1073B, manufactured by DuPont) was prepared as a lid material. A needleless plastic syringe (11.8 g) was prepared as a packaged item. The lid material and the base material obtained above were heat-sealed under the following conditions, and the syringe was packaged to produce a package (deep-draw package). (Heat-sealing conditions) Sealing pressure: 0.45 MPa (4.5 kgf / cm ２ ) Sealing time: 3.5 seconds Sealing temperature: 125°C

[0174] <<Evaluation of Package>> <Evaluation of Durability> The package obtained above was shaken back and forth 50 times in the longitudinal direction of the syringe with a swing amplitude of 30 cm and with enough strength to move the syringe in the longitudinal direction within the package. The package was then visually observed, and its durability was evaluated according to the following criteria. The results are shown in the "Durability of Package" column in Table 1. (Evaluation Criteria) A: Little or no deformation of the package due to poking with the syringe tip was observed, and the package had high durability. B: Obvious deformation or holes in the package due to poking with the syringe tip were observed, and the package had low durability.

[0175] Example 2 <Production of Resin Composition> Resin composition (2) was produced by mixing the EVA (85 parts by mass) and the hPP (15 parts by mass) at room temperature.

[0176] <<Production of Laminated Film>> A laminated film having the configuration shown in Figure 1 was produced by the following procedure. That is, the resin composition (2), the LLDPE, and the resin composition (1) were co-extruded in this order to obtain a laminated film (thickness 150 µm) in which a first resin layer (thickness 7.5 µm), a third resin layer (thickness 135 µm), and a second resin layer (thickness 7.5 µm) were laminated in this order in the thickness direction. The first resin layer, the third resin layer, and the second resin layer were all unstretched layers.

[0177] <<Evaluation of Laminated Film>> The laminated film obtained above was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0178] <<Production and Evaluation of Package>> A package was produced in the same manner as in Example 1, except that the laminate film obtained above was used. The resulting package was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0179] [Comparative Example 1] <<Production of Laminated Film>> The LLDPE, the modified PE, and the Ny were co-extruded in this order to obtain a laminated film (thickness 150 μm) configured by laminating a first resin layer (thickness 106.5 μm), a third resin layer (thickness 22.5 μm), and a second resin layer (thickness 21 μm) in this order in the thickness direction. The first resin layer, the third resin layer, and the second resin layer were all unstretched layers.

[0180] <<Evaluation of Laminated Film>> The laminated film obtained above was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0181] <<Production and Evaluation of Package>> A package was produced in the same manner as in Example 1, except that the laminate film obtained above was used. The resulting package was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0182] Comparative Example 2 <<Production of Monolayer Film>> The LDPE was extrusion molded to obtain a monolayer film (thickness: 150 μm) consisting of an unstretched layer.

[0183] <<Evaluation of Monolayer Film>> The monolayer film obtained above was evaluated in the same manner as in the laminate film of Example 1. The results are shown in Table 2.

[0184] <<Production and Evaluation of Package>> A package was produced in the same manner as in Example 1, except that the monolayer film obtained above was used instead of the laminate film. The resulting package was evaluated in the same manner as in Example 1. The results are shown in Table 2. In Table 2, the monolayer film of this comparative example is shown in the column for the first resin layer for convenience.

[0185] Comparative Example 3 <<Production of Laminated Film>> A laminated film (thickness 150 μm) was obtained by laminating a first resin layer (thickness 7.5 μm), a third resin layer (thickness 124.5 μm), and a second resin layer (thickness 18 μm) in this order in the thickness direction in the same manner as in Example 1, except that the conditions for co-extrusion of the resins were changed so that the second resin layer was thicker and the third resin layer was thinner than in Example 1. The first resin layer, the third resin layer, and the second resin layer were all unstretched layers.

[0186] <<Evaluation of Laminated Film>> The laminated film obtained above was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0187] <<Production and Evaluation of Package>> A package was produced in the same manner as in Example 1, except that the laminate film obtained above was used. The resulting package was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0188]

[0189]

[0190] As is clear from the above results, in Examples 1 and 2, the number of pinholes found in the laminate film after the Gelbo Flex test was one, indicating that the pinhole resistance of the laminate film was extremely high. Furthermore, in Examples 1 and 2, the puncture strength of the laminate film was 10.2 N or more (10.2 to 10.3 N), which was sufficiently high. Furthermore, in Examples 1 and 2, the durability of the package was high. In Examples 1 and 2, the ratio of the thickness of the third resin layer to the thickness of the laminate film was 90%.

[0191] Furthermore, in Examples 1 and 2, the first resin layer, the second resin layer, and the third resin layer in the laminated film contained the same type of polyolefin-based resin, and the laminated film was highly suitable for recycling.

[0192] In contrast, in Comparative Examples 1 and 3, the number of pinholes found in the laminate film after the Gelbo Flex test was 4 or more (4 to 6), and the pinhole resistance of the laminate film was low. In Comparative Example 1, the ratio of the thickness of the third resin layer to the thickness of the laminate film was 15%, and further, the third resin layer was an adhesive layer containing an adhesive resin as a main component. In Comparative Example 3, the ratio of the thickness of the third resin layer to the thickness of the laminate film was 83%.

[0193] Furthermore, in Comparative Example 1, the second resin layer in the laminated film did not contain the same type of polyolefin-based resin, and the recyclability of the laminated film was low.

[0194] In Comparative Example 2, the puncture strength of the monolayer film was low at 4.8 N. Furthermore, the durability of the package was low in Comparative Example 2. The monolayer film in Comparative Example 2 was a film made of LDPE.

[0195] The present invention can be used to manufacture various types of packaging that can be reused after use.

[0196] REFERENCE SIGNS LIST 1 laminated film 11 first resin layer 12 second resin layer 13 third resin layer 101 packaging body 8 lid material 10 base material T １ ...Thickness of laminated film, T１３ ...Thickness of the third resin layer

Claims

1. A laminated film comprising a first resin layer, a third resin layer and a second resin layer laminated in this order in the thickness direction, wherein the first resin layer, the second resin layer and the third resin layer comprise the same type of polyolefin resin, the ratio of the thickness of the third resin layer to the thickness of the laminated film is greater than 85%, and when the laminated film is subjected to a Gelbo flex test in accordance with ASTM F392 at a temperature of 23°C and 2,000 twists, the number of pinholes observed in the laminated film after the Gelbo flex test is 2 or less, and the puncture strength of the laminated film is 6 N or more.

2. The laminate film according to claim 1, wherein the third resin layer contains, as the polyolefin resin, either or both of a linear low-density polyethylene having structural units derived from octene and a metallocene-catalyzed linear low-density polyethylene having structural units derived from octene.

3. A laminate film as described in claim 1 or 2, wherein the first resin layer is a non-easy peel type sealant layer containing one or more polyolefin resins selected from the group consisting of polyethylene and ethylene copolymers.

4. The laminate film described in claim 3, wherein the first resin layer contains, as the polyolefin resin, one or more selected from the group consisting of low density polyethylene, linear low density polyethylene, metallocene-catalyzed linear low density polyethylene, and ethylene-vinyl acetate copolymer.

5. The laminate film according to claim 4, wherein the second resin layer contains, as the polyolefin resin, high density polyethylene, and one or more types selected from the group consisting of low density polyethylene, linear low density polyethylene and metallocene-catalyzed linear low density polyethylene.

6. A laminate film according to claim 1 or 2, wherein the first resin layer is an easy-peel layer containing, as the polyolefin resin, one or more types selected from the group consisting of polyethylene and ethylene-based copolymers, and one or more types selected from the group consisting of homopolypropylene and propylene-based copolymers.

7. The laminate film according to claim 6, wherein the first resin layer contains an ethylene-vinyl acetate copolymer and homopolypropylene as the polyolefin resin.

8. The laminate film according to claim 7, wherein the second resin layer contains, as the polyolefin resin, high density polyethylene, and one or more types selected from the group consisting of low density polyethylene, linear low density polyethylene and metallocene-catalyzed linear low density polyethylene.

9. A packaging material constructed using the laminated film according to claim 1 or 2.

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