Laminated film and packaging

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

[Technical Field]

[0001] The present invention relates to a laminated film and a packaging material. This application claims priority based on Japanese Patent Application No. 2023-195239, filed on November 16, 2023, the contents of which are incorporated herein by reference. [Background technology]

[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, generating large amounts of waste after use. From the perspective of improving the global environment, waste generation 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 laminated film are of the same type, there is no need to separate and reuse each resin layer separately, and the entire laminated film can be easily reused, making it more useful. As such a laminated film, for example, a polyethylene laminate for packaging materials has been disclosed, which comprises at least an oriented polyethylene film, an adhesive layer, and a heat-sealable polyethylene layer, and the adhesive layer contains a solventless adhesive (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-189333 Summary of the Invention [Problem to be solved by the invention]

[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 occurrence 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 a high level of hygiene. However, pinhole resistance and puncture strength of a packaging material do not necessarily coexist, and it is often the case that increasing one results in a decrease in the other. The laminated film described in Patent Document 1 does not provide both high pinhole resistance and puncture strength for the 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. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention employs the following configuration. [1] A laminated 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 laminated film is more 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 2000 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 6N or more. [2] The laminated film according to [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.

[0009] [3] The laminate film according to [1] or [2], wherein the first resin layer is a non-easy peel sealant layer containing one or more polyolefin resins selected from the group consisting of polyethylene and ethylene copolymers. [4] The laminate film according to [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 laminated film according to [4], wherein the second resin layer contains, 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.

[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 ethylene-based copolymers, and one or more selected from the group consisting of homopolypropylene and propylene-based copolymers. [7] The laminated film according to [6], wherein the first resin layer contains an ethylene-vinyl acetate copolymer and a homopolypropylene as the polyolefin-based resin. [8] The laminated film according to [7], wherein 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.

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

[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. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of a laminated film according to one embodiment of the present invention. [Figure 2] 1 is a cross-sectional view schematically illustrating an example of a packaging body according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] <<Laminated 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 comprise 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%. 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.

[0015] The laminated film of the present embodiment has high recyclability because the first resin layer, the second resin layer, and the third resin layer contain the same type of polyolefin resin. After the Gelbo Flex test is performed on the laminated film of this embodiment, the number of pinholes found in the laminated film is two or less, meaning that the laminated film has high pinhole resistance and can be used to produce packaging that is highly pinhole resistant. The laminated film of this embodiment has a high puncture strength of 6 N or more, and the laminated film can be used to produce packaging 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 third resin layer] / [thickness of laminate film] × 100), so the puncture strength and pinhole resistance of the laminate film are high.

[0016] Resin films used to date for producing packaging bodies have not necessarily been able to achieve both high pinhole resistance and high puncture strength. In contrast, the laminated film of this embodiment has the above-described configuration, and therefore has high pinhole resistance and puncture strength, making it possible to produce a package having both high pinhole resistance and puncture strength.

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

[0018] <Pinhole resistance> When the laminated film of this embodiment 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 laminated film after the Gelbo flex test is 2 or less (0 to 2), preferably 0 to 1, and more preferably 0. The laminated film exhibits the results of the Gelbo Flex test and has high pinhole resistance. That is, even when a torsional force is applied to the laminated film, the occurrence of pinholes (breakage) is suppressed, and the laminated 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, second resin layer, or 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 stronger the laminate film. When the puncture strength of the laminate film is equal to or greater than the above-mentioned lower limit, even if a sharp part is present on the packaged item and such a part hits the packaged item (more specifically, the area made up of the laminate film of this embodiment), damage to the packaged item 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 piercing 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 piercing strength.

[0023] In this embodiment, the tip of a needle having a radius of curvature of 0.5 mm is pushed vertically 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. The needle may be, for example, a stainless steel needle.

[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 laminated film ([thickness of the third resin layer]) / [thickness of the laminated film]×100) is greater than 85%, and in order to enhance the above-mentioned effects, the ratio is preferably 87% or more, and more preferably 89% or more. 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 not more than 95%. When the ratio is in this range, the effect obtained by providing the laminate film with the first resin layer and the second resin layer is further 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, any one of more than 85% and not more than 95%, 87 to 95%, and 89 to 95%, although 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 described below), the ratio of the thickness of the first resin layer to the thickness of the laminate film ([thickness of first resin layer] / [thickness of 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 effect obtained by providing the laminate film with the second resin layer and the third resin layer is further 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 greater. Having this ratio of 1% or greater enhances the effects achieved by the laminate film having the first resin layer. 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 the ratio is equal to or less than the upper limit, the effect obtained by providing the laminate film with the first resin layer and the third resin layer is further 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 1% or greater. This ratio range enhances the effects of the laminate film having the second resin layer. For example, when the second resin layer is an outer layer, the laminate film and the package obtained using it have higher pinhole resistance. Furthermore, adjusting the type and content of the components contained in the second resin layer also improves the formability of the laminate film. In this case, the package obtained by molding the laminate film can achieve the desired shape with high precision, for example, by preventing excessive thinning at the corners. Furthermore, adjusting the type and content of the components contained in the second resin layer also improves its heat resistance, thereby improving the heat resistance of the package obtained using the laminate film.

[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 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] FIG. 1 is a cross-sectional view schematically showing an example of the laminated film of the present embodiment. The laminated film 1 shown here is composed of a first resin layer 11 and a second resin layer 12 provided on one surface 11a of the first resin layer 11 (sometimes referred to as the "first surface" in this specification). The laminated film 1 further includes a third resin layer 13 between the first resin layer 11 and the second resin layer 12. That is, the laminated film 1 is configured by laminating a first resin layer 11, a third resin layer 13, and a 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 laminated film 1 . The other surface 11b of the first resin layer 11 (the surface opposite to the second resin layer 12 side; sometimes referred to as the "second surface" in this specification) is an 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 laminated film of this embodiment, the outermost layer means the outermost layer in the stacking direction of each layer constituting the laminated film, and the outermost surface means the outermost surface (i.e., the exposed surface) in the stacking direction of each layer constituting the laminated film.

[0034] The second resin layer 12 is the other outermost layer of the laminated film 1 . One surface 12a (the surface opposite to the first resin layer 11 side; sometimes referred to as the "first surface" in this specification) of the second resin layer 12 is an exposed surface (the other outermost surface). For example, when the second resin layer 12 is an outer layer, the first surface 12a of the second resin layer 12 is also an exposed surface (the other outermost surface) 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] The thickness T of the third resin layer 13 relative to the thickness T1 of the laminated film 1 13 The ratio (T 13 / T1×100) is over 85%. When the Gelbo flex test is performed on the laminate film 1 or the first test piece thereof, the number of pinholes found in the laminate film 1 or the first test piece thereof after the Gelbo flex test is two or less. The puncture strength of the laminated film 1 is 6N or more. Next, each layer of the laminated film of this embodiment will be described in detail.

[0037] <First resin layer> The first resin layer includes a polyolefin resin. In this specification, the term "polyolefin resin" refers to 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 components contained in the first resin layer, which will be described later, to the total mass of the first resin layer does not exceed 100% by mass. Similarly, in the composition for forming the first resin layer described below, the ratio of the total content of one or more of the components contained in the composition for forming the first resin layer described below 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)") and 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)").

[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 More than 0.945g / cm 3 is less than. The density of medium density polyethylene (MDPE) is 0.945 g / cm 3 More than 0.955g / cm 3 is less than. The density of high density polyethylene (HDPE) is 0.955 g / cm 3 That's all.

[0045] More preferred examples of the polyethylene contained in the first resin layer include octene (CH 16 ), linear low-density polyethylene (sometimes referred to herein as "C8-LLDPE") having structural units derived from octene (C8H 16 and polyethylenes having structural units derived from octene, such as metallocene-catalyzed linear low-density polyethylene (sometimes referred to herein as "C8-mLLDPE") having structural units derived from octene.

[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 sub-concept of mLLDPE (metallocene-catalyzed linear low-density polyethylene), which 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 copolymer contained in the first resin layer is preferably a resin other than an 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 copolymer (also known as polypropylene random copolymer (rPP)), propylene-ethylene block copolymer (also known as polypropylene block copolymer (bPP)), etc.

[0050] The first resin layer may contain only one type of polyolefin resin, 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.

[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 from the laminate film to the hot plate used for molding during heat molding of the laminate film is suppressed, 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 the polyolefin 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 in this specification as "other resin components") or non-resin components (sometimes referred to in this specification as "other non-resin components").

[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. Examples of the additives include 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" refers not only to polyolefin resins but also to resins having common structural units, in which the ratio of the amount (moles) of the common structural units to the total amount (moles) of the structural units is 20 mol% or more in both resins. 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), and ethylene-vinyl alcohol-vinyl acetate copolymer (partially saponified EVA) 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 the structural units is 20 mol% or more. On the other hand, for example, among propylene-ethylene random copolymers (rPP) and propylene-ethylene block copolymers (bPP), those 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 above-mentioned 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. 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 the ratio is equal to or greater than the lower limit, the effect obtained by the first resin layer containing the polyolefin-based resin is further enhanced. The ratio is usually the same as the ratio of the polyolefin resin content 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 polyolefin resin 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).

[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 of polyethylene resin (e1) in the first resin layer (parts by mass)] + [content of polypropylene resin (p1) 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 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 proportion is 100% by mass or less. The ratio is usually the same as the ratio of the total content (parts by mass) of the polyethylene-based resin (e1) and the polypropylene-based resin (p1) to the content (parts by mass) of the polyolefin-based resin in the composition for forming the first resin layer described below (([content (parts by mass) of the polyethylene-based resin (e1) in the composition for forming the first resin layer)] + [content (parts by mass) of the polypropylene-based resin (p1) in the composition for forming the first resin layer)]) / [content (parts by mass) of the polyolefin-based 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 first resin layer or 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 first resin layer or 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 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 (parts by mass)] / [total mass of the first resin layer (parts by mass)]×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 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 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 a non-easy peel type sealant layer, is preferably a non-easy peel type sealant layer containing one or more polyolefin-based resins 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 having structural units derived from octene (C8-LLDPE). 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 the 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, the proportion is 100% by mass or less. 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 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, the proportion is 100% by mass or less. 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 the first resin layer described below (([content (parts by mass) of low-density polyethylene in the composition for forming the first resin layer)] + [content (parts by mass) of linear low-density polyethylene in the composition for forming the first resin layer)]) + [content (parts by mass) of metallocene-catalyzed linear low-density polyethylene in the composition for forming the first resin layer)]) + [content (parts by mass) of ethylene-vinyl acetate copolymer in the composition for forming the first resin layer)]) / [content (parts by mass) of 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 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 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 cohesive failure-based peelability.

[0074] The first resin layer, which is an easy-peel layer, is preferably an easy-peel layer containing two incompatible polyolefin resins, namely, one or more selected from the group consisting of polyethylene and ethylene copolymers (i.e., polyethylene resin (e1)), and one or more selected from the group consisting of homopolypropylene and propylene copolymers (i.e., polypropylene 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, any of 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 of polyethylene resin (e1) in the first resin layer (parts by mass)] + [content of polypropylene resin (p1) in the first resin layer (parts by mass)]) / [content of polyolefin resin in the first resin layer (parts by mass)] × 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 more excellent layer as an easy-peel layer. Furthermore, 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 these two 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, any of 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 ethylene-vinyl acetate copolymer and homopolypropylene as the polyolefin resin, the ratio of the total content of the ethylene-vinyl acetate copolymer and homopolypropylene to the total content of the polyolefin resin in the first resin layer (([ethylene-vinyl acetate copolymer content in the first resin layer (parts by mass)] + [homopolypropylene content in the first resin layer (parts by mass)]) / [polyolefin resin content 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 the 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, the proportion is 100% by mass or less. 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 explained 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 be a single layer (single layer) or a multi-layer structure (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 is a multi-layer structure, these multi-layer structures may be the same or different from one another, and the combination of these multi-layer structures is not particularly limited as long as it does not impair the effects of the present invention. The first resin layer preferably 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 use of the laminated film and the thickness of the laminated 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. When the thickness of the first resin layer is equal to or less than the upper limit, the thickness of the laminate film can be made thinner. 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 that case, the effect obtained by the laminate film including the second resin layer and the third resin layer is further 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. When the thickness of the first resin layer is equal to or greater than the above-mentioned lower limit, the effect obtained by providing the laminate film with the first resin layer is 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. When the first resin layer is made up of a plurality of layers, the total thickness of these layers preferably falls within the above-mentioned range. The thickness of the first resin layer shown here is particularly suitable when the thickness of the laminated film is 60 to 250 μm, as will be described later.

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

[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 components contained in the second resin layer, which will be described later, to the total mass of the second resin layer does not exceed 100% by mass. Similarly, in the composition for forming the second resin layer described below, the ratio of the total content of one or more of the components contained in the composition for forming the second resin layer described below 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 resins as those contained in the first resin layer described above. For example, the polyolefin 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)"), etc.

[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 copolymer contained in the second resin layer include the same polyethylene (PE) and ethylene copolymer contained in the first resin layer.

[0089] For example, the polypropylene-based resin (polypropylene-based resin (p2)) contained in the second resin layer is the same as the polypropylene-based resin (polypropylene-based resin (p1)) contained in the first resin layer, 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.

[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. When two or more types 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 the polyolefin resins, as long as the effects of the present invention are not impaired. The other components may be either resin components (sometimes referred to herein as "other resin components") or non-resin components (sometimes referred to herein as "other non-resin components").

[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 there are two or more types, 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 resin relative to the total mass of the second resin layer is preferably 90 to 100 mass%, more preferably 95 to 100 mass%, and may be, for example, either 97 to 100 mass% or 99 to 100 mass%. When the content is equal to or greater than the lower limit, the effect obtained by containing the polyolefin resin in the second resin layer is further enhanced. The ratio is usually the same as the ratio of the content of the polyolefin resin 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 resin (e2) to the content of the polyolefin 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 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. On the other hand, the proportion is 100% by mass or less. The ratio is usually the same as the ratio of the content (parts by mass) of the polyethylene resin (e2) to the content (parts by mass) of the polyolefin resin in the composition for forming the second resin layer, which will be described later.

[0100] In the second resin layer, the proportion of the polyolefin resin of the same type as the polyolefin 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, either 95 to 100 mass% or 99 to 100 mass%. When the proportion is equal to or greater than the lower limit, the recyclability of the laminated film is further improved. This ratio is usually the same as the ratio of the content (parts by mass) of polyolefin-based resin of the same type as the polyolefin-based resin contained in the first 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 second resin layer 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 polyethylene classified into these two groups is particularly suitable as an outer layer. Because this second resin layer contains high-density polyethylene, its heat resistance is enhanced, and the heat resistance of the laminate film and packaging comprising this second resin layer is also enhanced. Meanwhile, because this second resin layer contains one or more selected from the group consisting of low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene, its pinhole resistance and formability are enhanced. Furthermore, the pinhole resistance and formability of the laminate film and packaging comprising this second resin layer are also enhanced.

[0103] The linear low-density polyethylene contained in the second resin layer is preferably a linear low-density polyethylene having structural units derived from octene (C8-LLDPE), and the metallocene-catalyzed linear low-density polyethylene is preferably a metallocene-catalyzed linear low-density polyethylene having structural units derived from octene (C8-mLLDPE). 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, 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, 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 ratio 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, and the heat resistance and pinhole resistance of a package obtained using such a laminate film are also improved, allowing the desired shape to be achieved with high precision. On the other hand, the proportion 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 in the composition for forming the second resin layer (parts by mass)] + [content of low-density polyethylene in the composition for forming the second resin layer (parts by mass)] + [content of linear low-density polyethylene in the composition for forming the second resin layer (parts by mass)] + [content of metallocene-catalyzed linear low-density polyethylene in the composition for forming the second resin layer (parts by mass)]) / [content of polyolefin-based resin in the composition for forming the second resin layer (parts by mass)] × 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 the second resin layer (parts by mass)] / ([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)])×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 this ratio is equal to or greater than the lower limit, the effect obtained by including high-density polyethylene in the second resin layer is further enhanced. That is, the heat resistance of the second resin layer, the laminate film, and the package is improved. On the other hand, the proportion 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 proportion 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 formability of the second resin layer and the laminate film are improved. Furthermore, the pinhole resistance of the package is also improved, 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 the second resin layer described below ([Content of high-density polyethylene in the composition for forming the second resin layer (parts by mass)] / ([Content of high-density polyethylene in the composition for forming the second resin layer (parts by mass)]+[Content of low-density polyethylene in the composition for forming the second resin layer (parts by mass)]+[Content of linear low-density polyethylene in the composition for forming the second resin layer (parts by mass)]+[Content of metallocene-catalyzed linear low-density polyethylene in the composition for forming the second resin layer (parts by mass)])×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.

[0106] When the second resin layer contains either or both of linear low-density polyethylene and metallocene-catalyzed linear low-density polyethylene as the polyolefin resin, the ratio of the total content of linear low-density polyethylene having structural units derived from octene (C8-LLDPE) and 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 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, for example, be 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 heat resistance, pinhole resistance, and formability of the laminate film having such a second resin layer are improved, and 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. On the other hand, the proportion is 100% by mass or less. The ratio is usually the same as the ratio of the total content of linear low-density polyethylene having structural units derived from octene (C8-LLDPE) and metallocene-catalyzed linear low-density polyethylene having structural units derived from octene (C8-mLLDPE) to the total content of linear low-density polyethylene and 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. The second resin layer preferably consists of one layer (single layer).

[0108] The thickness of the second resin layer is not particularly limited and can be set arbitrarily depending on the use of the laminated film and the thickness of the laminated film. 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. When the thickness of the second resin layer is 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 this case, the effect obtained by the laminate film including the first resin layer and the third resin layer is 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 lower limit, the effects obtained by providing the laminate film with the second resin layer are enhanced. For example, the pinhole resistance of the laminate film is enhanced. When the second resin layer is made up of a plurality of layers, the total thickness of these layers preferably falls within the above-mentioned 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), which improves the formability of the laminated film.

[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 components contained in the third resin layer, which will be described later, to the total mass of the third resin layer does not exceed 100% by mass. Similarly, in the composition for forming the third resin layer described below, the ratio of the total content of one or more of the components contained in the composition for forming the third resin layer described below 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 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)"), etc.

[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. The polyethylene (PE) and ethylene copolymer contained in the third resin layer may be the same as the polyethylene (PE) and ethylene copolymer contained in the first resin layer.

[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 structural units derived from propylene and structural units 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. When two or more types 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 the polyolefin resins, as long as the effects of the present invention are not impaired. The other components may be either resin components (sometimes referred to herein as "other resin components") or non-resin components (sometimes referred to herein as "other non-resin components").

[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 third resin layer may contain only one type of other component, or two or more types. When there are two or more types, 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. 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 resin relative to the total mass of the third resin layer is preferably 90 to 100 mass%, more preferably 95 to 100 mass%, and may be, for example, either 97 to 100 mass% or 99 to 100 mass%. When the content is equal to or greater than the lower limit, the effect obtained by including the polyolefin resin in the third resin layer is further enhanced. The above ratio is usually the same as the ratio of the content of the polyolefin resin 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 further enhanced. The adhesive resin may be any known resin, more specifically, for example, a modified polyolefin such as an acid-modified polyolefin having an acidic group. In the third resin layer, the content of the adhesive resin relative to the total mass of the third resin layer is preferably 0 to 5 mass%, more preferably 0 to 3 mass%, and even more preferably 0 to 1 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 resin (e3) to the content of the polyolefin 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 resin (e3) is further enhanced. For example, the puncture strength of such a third resin layer, the laminate film provided with the third resin layer, and a package obtained using the laminate film is further enhanced. On the other hand, the proportion is 100% by mass or less. The ratio is usually the same as the ratio of the content (parts by mass) of the polyethylene resin (e3) to the content (parts by mass) of the polyolefin resin in the composition for forming the third resin layer, which will be described later.

[0126] In the third resin layer, the proportion of the polyolefin resin of the same type as the polyolefin 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, either 95 to 100 mass% or 99 to 100 mass%. When the proportion is equal to or greater than the lower limit, the recyclability of the laminated film is further improved. This ratio is usually the same as the ratio of the content (parts by mass) of polyolefin-based resin of the same type as the polyolefin-based resin contained in the first resin layer and the second resin layer 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 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 having structural units derived from octene (C8-LLDPE), and the metallocene-catalyzed linear low-density polyethylene is preferably a metallocene-catalyzed linear low-density polyethylene having structural units derived from octene (C8-mLLDPE). 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 having structural units derived from octene (C8-LLDPE) and a metallocene-catalyzed linear low-density polyethylene having structural units derived from octene (C8-mLLDPE). The puncture strength of the laminated film having 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 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 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 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 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 puncture strength of such a third resin layer, the laminate film provided with the third resin layer, and a package obtained using the laminate film is further increased. On the other hand, the proportion is 100% by mass or less. The above 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-based 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-based 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 structural units 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 refers to the total content of metallocene-catalyzed linear low-density polyethylene having structural units 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 one or both of a linear low-density polyethylene and a metallocene-catalyzed linear low-density polyethylene as the polyolefin resin, 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 The ratio of the total content of C8-LLDPE in the third resin layer and the C8-mLLDPE ((([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)] + [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 comprising the third resin layer, and a package obtained using the laminate film becomes particularly high. On the other hand, the proportion is 100% by mass or less. The ratio is usually the same as the ratio of the total content of linear low-density polyethylene having structural units derived from octene (C8-LLDPE) and metallocene-catalyzed linear low-density polyethylene having structural units derived from octene (C8-mLLDPE) to the total content of linear low-density polyethylene and metallocene-catalyzed linear low-density polyethylene in the composition for forming the third resin layer described below (([C8-LLDPE content (parts by mass) in the composition for forming the third resin layer)] + [C8-mLLDPE content (parts by mass) in the composition for forming the third resin layer)]) / ([LLDPE content (parts by mass) in the composition for forming the third resin layer)] + [mLLDPE content (parts by mass) in the composition for forming the 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 preferably consists of one layer (single layer).

[0133] The thickness of the third resin layer is not particularly limited and can be set arbitrarily depending on the use of the laminated film and the thickness of the laminated film. 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 above-mentioned lower limit, the effect obtained by providing the laminate film with the third resin layer 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 made thinner. 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 suitable, and in that case, the effect obtained by the laminate film including the first resin layer and the second resin layer is further enhanced. When the third resin layer is made up of a plurality of layers, the total thickness of these layers preferably falls 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 will be described later.

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

[0135] <Other layers> The laminated film of this embodiment may have other layers that do 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, but it is preferable that the laminated film does not have any of the other layers. The other layer is a layer that does not contain the same type of polyolefin resin, and since the laminated film does not have such other layers, its recyclability is improved and its puncture strength and pinhole resistance can be more easily adjusted.

[0136] <Overall structure of laminated film> The thickness (total 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 laminated film, it is preferable that all of the layers constituting it (e.g., the first resin layer, the second resin layer, and the third resin layer) are unstretched layers (films). Such unstretched laminated 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 preferably each contain a polyethylene resin as the same type of polyolefin resin. In this case, for example, it is preferable that the first resin layer contains, as the same type of 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; 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. 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 configured by laminating a first resin layer, a third resin layer, and a second resin layer in this order in the thickness direction, 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 laminated film is more than 85%, the ratio of the thickness of the first resin layer to the thickness of the laminated film is 7.5% or less; the ratio of the thickness of the second resin layer to the thickness of the laminated film is 7.5% or less; When the laminated 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 laminated film after the Gelbo flex test is 2 or less, The puncture strength of the laminated film is 6N or more, the second resin layer and the third resin layer contain a polyethylene-based resin as the polyolefin-based resin, 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, An example of the laminated film is one in which 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 the present embodiment is a laminate film configured by laminating a first resin layer, a third resin layer, and a second resin layer in this order in the thickness direction, 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 laminated film is more than 85%, the ratio of the thickness of the first resin layer to the thickness of the laminated film is 7.5% or less; the ratio of the thickness of the second resin layer to the thickness of the laminated film is 7.5% or less; When the laminated 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 laminated film after the Gelbo flex test is 2 or less, The puncture strength of the laminated film is 6N or more, the second resin layer contains, 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 contains, as the polyolefin-based resin, either or both of a linear low-density polyethylene and a metallocene-catalyzed linear low-density polyethylene; 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 ethylene-based copolymers, or an easy peel layer containing, as the polyolefin-based 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, An example of a laminated film is one 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 preferable example of the laminate film of the present embodiment is a laminate film configured by laminating a first resin layer, a third resin layer, and a second resin layer in this order in the thickness direction, 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 laminated film is more than 85%, the ratio of the thickness of the first resin layer to the thickness of the laminated film is 7.5% or less; the ratio of the thickness of the second resin layer to the thickness of the laminated film is 7.5% or less; When the laminated 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 laminated film after the Gelbo flex test is 2 or less, The puncture strength of the laminated film is 6N or more, the second resin layer contains, 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 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; the first resin layer is a non-easy peel sealant layer containing, 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 containing, 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, part 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 part 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] <<Laminated film manufacturing method>> 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; or an air-cooled or water-cooled coextrusion inflation method.

[0143] When the resin composition is used, for example, a mixture of two or more components (dry blend, non-kneaded mixture) may be directly fed into the extruder as the resin composition, or a pre-kneaded mixture of two or more components may be fed into the extruder as the resin composition. The pre-kneaded mixture can be obtained, for example, by melt-kneading two or more components using a device 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 to constitute any two or more of the layers in advance, and then laminating them together using a thermal lamination method or the like without using an adhesive, and then 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") are each 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 body according to one embodiment of the present invention is constructed using the laminated film according to one embodiment of the present invention described above. The packaging body of this embodiment is made of the laminated film, and therefore has high pinhole resistance, and for example, even if a twisting force is applied to the packaging body, the occurrence of pinholes (breakage) is suppressed, and the packaging body of this embodiment has high puncture strength, and for example, even if a sharp part exists in the stored item and such a part hits the packaging body, the packaging body is suppressed from being broken. Furthermore, by using the laminated film having high formability or heat resistance, it is possible to improve the formability or heat resistance of the packaging body of 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 package of this embodiment is, for example, a package that includes a lid material and a base material, and is constructed by sealing the lid material and the base material, and one or both of the lid material and the base material are constructed using the laminated film. The base material may be, for example, a molded article of a resin film having a recess for forming a storage section in the package. The resin film may be the laminate film or 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 laminated film, the cover material may be the laminated film or a resin film other than the laminated film. On the other hand, when the base material is not a molded product of the laminated film, the cover material is the laminated film.

[0153] The base material is preferably a deep-drawn product of the laminate film or another resin film, and more preferably a deep-drawn product of the laminate film. That is, the package of this embodiment including the lid material and the deep-drawn package is preferably a deep-drawn package, and more preferably a deep-drawn package whose base material is a deep-drawn product of the laminated film. Such deep-drawn packages have high pinhole resistance and puncture strength, and by using the laminated 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 be improved.

[0154] FIG. 2 is a cross-sectional view schematically showing an example of the packaging body of this 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 packaging body 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 laminated film 1 shown in Fig. 1, and more specifically, is a molded body (heat-molded body) of the laminated film 1. In the base material 10 in FIG. 2, the distinction between the layers in the laminated film 1 that constitutes it is omitted.

[0156] The base material 10 has a recess 100 formed therein. One side 10b of the base material 10 (sometimes referred to as the "second side" in this specification) and one side 8b of the lid material 8 (sometimes referred to as the "second side" in this specification) are both sealing surfaces, and these face each other in the packaging body 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 their peripheral edges are sealed to form the package 101. As a result, in the area of ​​the recess 100 of the base material 10, 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. 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 may be any other 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 when the stored item 9 is stored therein.

[0161] The packaging body of this embodiment is not limited to the packaging body 101 shown in Figure 2, and for example, some of the configuration of the packaging body 101 may be changed, deleted, or added within the scope of 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 other than the laminate film 1 of this embodiment. For example, in the packaging body 101, the base material 10 is made of the laminate film 1 shown in Fig. 1, but may be made of 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] <<Packaging manufacturing method>> The packaging body can be produced by packaging an object to be packaged (in other words, an object to be stored) using the laminated film. The packaging body can be produced in the same manner as conventional packaging bodies, except that the laminated film is used instead of the conventional resin film. When producing a package, the first resin layer in the laminate film or a molded product thereof is placed facing the object to be packaged, and the second resin layer is placed facing the opposite side to the object to be packaged, and the object is packaged.

[0163] In the case of deep-drawn packaging, 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 packaging.

[0164] Not only in the case of deep-draw packaging, but also in the production of any packaging, 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-draw packaging body, 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. [Example]

[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 with octene-derived units (Dow Chemical Company, "ELITE 5220G," density 0.915 g / cm 3 , MFR 3.5g / 10min, melting point 123℃) LDPE: Low-density polyethylene (Sumitomo Chemical Co., Ltd. "Sumikathen (registered trademark) L211", density 0.924 g / cm 3 , MFR 2g / 10min, melting point 112℃) HDPE: High-density polyethylene (Prime Polymer "Hi-Zex 2200J", density 0.964 g / cm 3 , MFR 5.2g / 10min, melting point 133℃) hPP: Homopolypropylene (Prime Polypro F-300SP manufactured by Prime Polymer, melting point 163°C) EVA: Ethylene-vinyl acetate copolymer ("Evaflex (registered trademark) P1007" manufactured by Mitsui Dow Polychemicals, melting point 94°C, MFR 9.0g / 10min) Ny: 6-Nylon (UBE "1022B") Modified PE: Acid-modified polyethylene (adhesive resin, Mitsui Chemicals "NF536")

[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] <<Laminated film manufacturing>> A laminated film having the structure shown in FIG. 1 was produced according to 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 laminated film>> <Evaluation of pinhole resistance> A first test piece having a size corresponding to A4 paper size (210 mm x 297 mm) was cut out from the laminated film obtained above. The first test piece was subjected to a Gelbo Flex test in accordance with ASTM F392 at a temperature of 23°C and 2000 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 laminated film was evaluated according to the following criteria. The results are shown in Table 1 in the column "Pinhole resistance of laminated film (number of pinholes)" along with the number of pinholes. (Evaluation criteria) A: The number of pinholes is 0 to 1, and the laminated film has extremely high pinhole resistance. B: The number of pinholes is 2, and the laminated film has high pinhole resistance. C: The number of pinholes is 3 or more, and the pinhole resistance of the laminated film is low.

[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 "Puncture strength of laminate film (N)" column in Table 1.

[0172] <<Packaging Manufacturing>> <Manufacture of soles> The laminated film obtained above was heat-molded using a deep-draw packaging machine (MULTIVAC "R535") and a mold measuring 108 mm in length and 150 mm in width at a molding temperature of 95°C and a drawing depth of 30 mm to produce the base material.

[0173] <Packaging production> 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℃

[0174] <<Packaging evaluation>> <Durability evaluation> The resulting package 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 packaging due to poking by the syringe tip was observed, and the packaging was highly durable. B: The packaging was clearly deformed or perforated by the puncture of the syringe tip, and the packaging had low durability.

[0175] [Example 2] <Production of Resin Composition> The EVA (85 parts by mass) and the hPP (15 parts by mass) were mixed at room temperature to produce a resin composition (2).

[0176] <<Laminated film manufacturing>> A laminated film having the structure shown in FIG. 1 was produced according to 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] <<Packaging production and evaluation>> A package was produced in the same manner as in Example 1, except that the laminated 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] <<Laminated film manufacturing>> The LLDPE, modified PE, and Ny were co-extruded in this order to obtain a laminated film (thickness 150 μm) consisting of a first resin layer (thickness 106.5 μm), a third resin layer (thickness 22.5 μm), and a second resin layer (thickness 21 μm), 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.

[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] <<Packaging production and evaluation>> A package was produced in the same manner as in Example 1, except that the laminated 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 <<Monolayer film manufacturing>> The LDPE was extruded to obtain a monolayer film (thickness: 150 μm) consisting of an unstretched layer.

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

[0184] <<Packaging production and evaluation>> A package was produced in the same manner as in Example 1, except that the monolayer film obtained above was used instead of the laminated 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 single layer film of this comparative example is shown in the column for the first resin layer for convenience.

[0185] Comparative Example 3 <<Laminated film manufacturing>> A laminated film (thickness 150 μm) was obtained by laminating the first resin layer (thickness 7.5 μm), the third resin layer (thickness 124.5 μm), and the 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 thickness of the second resin layer was thicker and the thickness of 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] <<Packaging production and evaluation>> A package was produced in the same manner as in Example 1, except that the laminated 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] [Table 1]

[0189] [Table 2]

[0190] As is clear from the above results, in Examples 1 and 2, the number of pinholes found in the laminated films after the Gelbo Flex test was one, and the pinhole resistance of the laminated films was extremely high. Furthermore, in Examples 1 and 2, the puncture strength of the laminated films was 10.2 N or more (10.2 to 10.3 N), which was sufficiently high. Furthermore, in Examples 1 and 2, the packaging materials had high durability. In Examples 1 and 2, the ratio of the thickness of the third resin layer to the thickness of the laminated 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 had high suitability for recycling.

[0192] In contrast, in Comparative Examples 1 and 3, the number of pinholes found in the laminated films after the Gelbo Flex test was 4 or more (4 to 6), and the pinhole resistance of the laminated films was low. In Comparative Example 1, the ratio of the thickness of the third resin layer to the thickness of the laminated film was 15%, and 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 laminated 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 resin, and the recyclability of the laminated film was low.

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

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

[0196] 1. Laminated film 11...1st resin layer 12...Second resin layer 13...Third resin layer 101...Packaging 8...Lid material 10...Bottom material T1: Thickness of laminated film, T 13 Thickness of the third resin layer

Claims

1. A laminated film configured by laminating a first resin layer, a third resin layer, and a second resin layer in this order in a thickness direction thereof, 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 laminated film is more than 85%, When the laminated 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 laminated film after the Gelbo flex test is 2 or less, The puncture strength of the laminated film is 6N or more, the first resin layer is a sealant layer, The second resin layer contains, as the polyolefin-based resin, High density polyethylene, one or more selected from the group consisting of low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene; The laminated film is an outer layer comprising:

2. A laminated film as described in claim 1, wherein in the second resin layer, the ratio of the content of the high-density polyethylene to the total content of the high-density polyethylene, the low-density polyethylene, the linear low-density polyethylene, and the metallocene-catalyzed linear low-density polyethylene is 10 mass% or more.

3. 3. 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.

4. 3. The laminate film according to claim 1, wherein the first resin layer is a non-easy peel sealant layer containing one or more polyolefin resins selected from the group consisting of polyethylene and ethylene copolymers.

5. 5. The laminate film according to claim 4, 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.

6. 3. The laminate film according to claim 1, 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 ethylene-based copolymers, and one or more selected from the group consisting of homopolypropylene and propylene-based copolymers.

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

8. A packaging body constructed using the laminated film according to claim 1 or 2.

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