Laminated film and package

Abstract

To provide a laminated film which can constitute a package that is excellent in both transparency and impact resistance before and after retort treatment.SOLUTION: A laminated film 1 is constituted by laminating a sealant layer 11, an oxygen barrier layer 12 and an outer layer 13 in this order, wherein the sealant layer 11 and the outer layer 13 contain a propylene-ethylene random copolymer, the oxygen barrier layer 12 contains a retort-resistant oxygen barrier resin, and the retort-resistant oxygen barrier resin contains a modified ethylene-vinyl alcohol copolymer obtained by copolymerizing ethylene and vinyl acetate and subjecting the reactant to saponification treatment, under the coexistence of one or both of polyamide and a crosslinking accelerator, and one or two kinds selected from the group consisting of an ethylene-vinyl alcohol copolymer, polyamide, a partially dehydrated substance of hydrated carboxylate and a completely dehydrated substance of hydrated carboxylate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminated film and a packaging material. [Background technology]

[0002] Laminated films formed by laminating multiple resin layers are widely used as packaging materials. A typical laminated film includes at least a sealant layer for heat-sealing to an object to be sealed, an outer layer on the opposite side of the sealant layer, and an oxygen barrier layer between the sealant layer and the outer layer. By hot-forming such a laminated film, a base material for a package can be obtained, which can be used in the same way as a cup-shaped container, for example.

[0003] More specifically, an example of such a laminate film is a laminate film in which the outermost layer contains a propylene-ethylene block copolymer and the oxygen barrier layer contains an ethylene-vinyl alcohol copolymer (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-41517 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the packaging body produced using the laminated film disclosed in Patent Document 1, there was room for further improvement in the transparency, impact resistance, or transparency after retort treatment in the area where the laminated film was used.

[0006] An object of the present invention is to provide a laminated film that can be used to form a package that is excellent in both transparency before and after retort treatment and impact resistance, and a package formed using the laminated film. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following configuration. [1] A laminated film constructed by laminating a sealant layer, an oxygen barrier layer, and an outer layer in this order in the thickness direction, wherein the sealant layer and the outer layer comprise a propylene-ethylene random copolymer, the oxygen barrier layer comprises a retort-resistant oxygen barrier resin, and the retort-resistant oxygen barrier resin is one or both of: a modified ethylene-vinyl alcohol copolymer obtained by copolymerizing ethylene and vinyl acetate in the presence of either or both of a polyamide and a crosslinking accelerator, followed by saponification; and a composition comprising an ethylene-vinyl alcohol copolymer and one or more members selected from the group consisting of polyamides, partial dehydrated carboxylate hydrates, and completely dehydrated carboxylate hydrates.

[0008] [2] The laminated film according to [1], wherein the sealant layer and the outer layer further contain homopolypropylene. [3] The laminated film according to [1] or [2], wherein the sealant layer and the outer layer further contain an elastomer. [4] The laminated film according to [3], wherein the sealant layer and the outer layer contain a hydrogenated styrene-based elastomer as the elastomer. [5] A packaging body constructed using the laminated film according to any one of [1] to [4]. [Effects of the Invention]

[0009] According to the present invention, there are provided a laminated film capable of forming a package that is excellent in both transparency before and after retort treatment and impact resistance, and a package formed using the laminated film. [Brief explanation of the drawings]

[0010] [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

[0011] <<Laminated film>> A laminate film according to one embodiment of the present invention is constructed by laminating a sealant layer, an oxygen barrier layer, and an outer layer in this order in the thickness direction, wherein the sealant layer and the outer layer comprise a propylene-ethylene random copolymer (also known as a polypropylene random copolymer, also referred to as "rPP"). The oxygen barrier layer comprises a retort-resistant oxygen barrier resin. The retort-resistant oxygen barrier resin is either one or both of: a modified ethylene-vinyl alcohol copolymer (herein sometimes referred to as "modified EVOH") obtained by copolymerizing ethylene and vinyl acetate in the presence of either or both of a polyamide and a crosslinking accelerator, followed by saponification; and a composition comprising an ethylene-vinyl alcohol copolymer (EVOH, also known as a saponified ethylene-vinyl acetate copolymer) and one or more members selected from the group consisting of polyamides, partial dehydrated carboxylate hydrates, and completely dehydrated carboxylate hydrates.

[0012] The laminated film of this embodiment has high transparency (transparency before retort treatment) and impact resistance because the outer layer and sealant layer contain rPP, and has high transparency after retort treatment because the oxygen barrier layer contains the retort-resistant oxygen barrier resin.

[0013] In this specification, "retort treatment" refers to a heat treatment carried out under pressure at a temperature exceeding 100°C for about 4 to 60 minutes, and is preferably a retort sterilization treatment.

[0014] [Transparency of laminated film (haze)] The degree of transparency of the laminated film of this embodiment can be evaluated by the haze of the laminated film. The haze of the laminate film of this embodiment, measured from the outside on the outer layer side, is not particularly limited as long as the laminate film is transparent, but is preferably 43% or less, more preferably 35% or less, and may be, for example, either 30% or less or 23% or less. The smaller the haze of the laminate film, the higher the transparency of the laminate film, and the more suitable it is for producing packaging materials that also have high transparency. On the other hand, the lower limit of the haze of the laminated film is not particularly limited. For example, a laminated film having a haze of 10% or more can be more easily achieved.

[0015] The haze measured from the outside of the outer layer side of the laminate film and the transparency of the laminate film can be adjusted by, for example, adjusting the type and content of components contained in any of the layers constituting the laminate film, such as the sealant layer, oxygen barrier layer, and outer layer. In particular, the transparency of the laminate film can be more easily adjusted by adjusting the type and content of components contained in the outer layer and sealant layer. In particular, the transparency of the laminate film can be more easily increased (the haze of the laminate film can be easily reduced) by increasing the rPP content of the outer layer and sealant layer. However, the method for adjusting the transparency (haze) of the laminated film is not limited to these.

[0016] In this specification, the term "haze" refers to a value measured in accordance with JIS K 7136:2000, unless otherwise specified, not only in the case of the above-mentioned laminated film but also in the case of, for example, a laminated film after retort treatment as described below.

[0017] In this specification, unless otherwise specified, the term "haze of a laminated film" refers to the haze of a laminated film before retort treatment.

[0018] [Transparency (haze) of laminated film after retort processing] The degree of transparency of the laminated film of this embodiment after retort treatment can be evaluated by the haze of the laminated film after retort treatment. The laminate film of this embodiment is retorted for 30 minutes at 121°C, and the haze of the laminate film after this retort treatment, measured from the outside of the outer layer side thereof, is preferably 43% or less, more preferably 38% or less, and may be, for example, 33% or less. The smaller the haze of the laminate film after retort treatment, the higher the transparency of the laminate film after retort treatment, for example, the more suppressed cloudiness, and similarly, the laminate film is suitable for producing a package having high transparency after retort treatment, for example, with suppressed cloudiness. On the other hand, there is no particular limitation on the lower limit of the haze of the laminated film after retort treatment. For example, a laminated film having a haze of 20% or more can be more easily achieved.

[0019] The haze of the laminate film after retort treatment, measured from the outside on the outer layer side, and the transparency of the laminate film after retort treatment can be adjusted by, for example, adjusting the type and content of components contained in any of the layers constituting the laminate film, such as the sealant layer, oxygen barrier layer, or outer layer. In particular, the transparency of the laminate film after retort treatment can be more easily adjusted by adjusting the type and content of components contained in the oxygen barrier layer. In particular, by increasing the content of the retort-resistant oxygen barrier resin in the oxygen barrier layer, the transparency of the laminate film after retort treatment can be more easily increased (the haze of the laminate film after retort treatment can be easily reduced). However, the method for adjusting the transparency (haze) of the laminated film after retort treatment is not limited to these. The retort-resistant oxygen barrier resin will be described in detail later.

[0020] [Impact resistance of laminated film (tensile impact strength)] The impact resistance of the laminated film of this embodiment can be evaluated by the tensile impact strength of the laminated film. The laminated film of this embodiment has a tensile impact strength in the resin flow direction (machine direction, sometimes referred to as "MD" in this specification) of 330 kJ / m 2 It is preferable that the concentration is 360 kJ / m or more. 2 More preferably, it is 390 kJ / m or more, for example. 2 When the MD tensile impact strength of the laminate film is equal to or greater than the lower limit, the impact resistance of the laminate film is further increased. On the other hand, there is no particular upper limit to the MD tensile impact strength of the laminate film. For example, in order to more easily realize the desired laminate film, the MD tensile impact strength of the laminate film is preferably 800 kJ / m 2 It is preferable that:

[0021] The laminated film of this embodiment has a tensile impact strength of 260 kJ / m in the direction perpendicular to the resin flow direction (MD) (transverse direction, sometimes referred to as "TD" in this specification). 2 It is preferable that the value is equal to or greater than 290 kJ / m 2 When the TD tensile impact strength of the laminate film is equal to or greater than the lower limit, the impact resistance of the laminate film is further increased. On the other hand, there is no particular upper limit to the TD tensile impact strength of the laminate film. For example, in order to more easily realize the desired laminate film, the TD tensile impact strength of the laminate film is preferably 800 kJ / m 2 It is preferable that:

[0022] In this specification, the tensile impact strength of a resin film, not limited to the laminate film of this embodiment, in both MD and TD, means a value measured in accordance with JIS K 7160A unless otherwise specified.

[0023] In the laminate film of this embodiment, it is preferable that the MD tensile impact strength is in one of the above-mentioned ranges and the TD tensile impact strength is in one of the above-mentioned ranges, and the impact resistance of such a laminate film is particularly high.

[0024] The impact resistance of a laminate film, such as its tensile impact strength, can be adjusted by, for example, adjusting the type and content of components contained in any of the layers constituting the laminate film, such as the sealant layer, oxygen barrier layer, or outer layer, as well as their thickness. In particular, the impact resistance of a laminate film can be more easily adjusted by adjusting the type and content of components contained in the outer layer and sealant layer. In particular, the impact resistance (tensile impact strength) of a laminate film can be more easily increased by increasing the rPP content of the outer layer and sealant layer. Furthermore, the impact resistance (tensile impact strength) of a laminate film can be more easily increased by including an elastomer, as described below, in the outer layer and sealant layer and increasing the elastomer content in the outer layer and sealant layer within an appropriate range. However, the method for adjusting the impact resistance (tensile impact strength) of the laminated film is not limited to these.

[0025] [Example of laminated film] 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 the components may not necessarily be the same as in reality.

[0026] FIG. 1 is a cross-sectional view schematically showing an example of the laminated film of the present embodiment. 1 is configured by laminating a sealant layer 11, an oxygen barrier layer 12, and an outer layer 13 in this order in the thickness direction. That is, in the laminated film 1, the outer layer 13 is provided on one surface of the sealant layer 11, and the oxygen barrier layer 12 is provided between the sealant layer 11 and the outer layer 13.

[0027] The laminated film 1 further includes adhesive layers 14 provided between the sealant layer 11 and the oxygen barrier layer 12, and between the outer layer 13 and the oxygen barrier layer 12. In this specification, to distinguish between these adhesive layers 14, the adhesive layer 14 provided between the sealant layer 11 and the oxygen barrier layer 12 may be referred to as a first adhesive layer 141, and the adhesive layer 14 provided between the outer layer 13 and the oxygen barrier layer 12 may be referred to as a second adhesive layer 142.

[0028] That is, the laminated film 1 is constructed by laminating a sealant layer 11, a first adhesive layer 141, an oxygen barrier layer 12, a second adhesive layer 142, and an outer layer 13 in this order in the thickness direction. The adhesive layer 14 (first adhesive layer 141 and second adhesive layer 142) is of any configuration, and the laminated film 1 does not have to have these adhesive layers, but the presence of these adhesive layers improves the peel (adhesion) strength of the sealant layer 11 and the oxygen barrier layer 12, and improves the peel (adhesion) strength of the outer layer 13 and the oxygen barrier layer 12.

[0029] In the laminated film 1, the sealant layer 11 is one outermost layer, and the outer layer 13 is the other outermost layer. One side 11b of the sealant layer 11 (the side opposite the outer layer 13, sometimes referred to as the "second side" in this specification) is the exposed surface (one of the outermost surfaces) and is the same as one side 1b of the laminated film 1. One side 13a of the outer layer 13 (the side opposite the sealant layer 11, sometimes referred to as the "first side" in this specification) is the exposed surface (the other outermost surface) and is the same as the other side 1a of the laminated film 1.

[0030] In the laminated film 1, the sealant layer 11 and the outer layer 13 contain rPP, and the oxygen barrier layer 12 contains the retort-resistant oxygen barrier resin.

[0031] Each layer of the laminated film of this embodiment will be described in more detail below.

[0032] <Outer layer> The outer layer imparts rigidity and heat resistance to the laminated film, improves the appearance of the laminated film, and also protects the other layers constituting the laminated film. The outer layer is preferably transparent.

[0033] In the outer layer, the proportion of the total content of one or more components contained in the outer layer, which will be described later, relative to the total mass of the outer layer does not exceed 100 mass %. Similarly, in the resin composition for forming the outer layer described below, the ratio of the total content of one or more of the components contained in the resin composition for forming the outer layer described below to the total mass of the resin composition for forming the outer layer does not exceed 100 mass%.

[0034] The outer layer comprises rPP (propylene-ethylene random copolymer). The melt flow rate of the rPP contained in the outer layer (sometimes referred to as "MFR" in this specification, not limited to rPP) is not particularly limited, but is preferably 0.1 to 6 g / 10 min, and more preferably 0.2 to 5 g / 10 min. When the melt flow rate of the rPP is equal to or greater than the lower limit, the film-formability of the outer layer is improved. When the melt flow rate of the rPP is equal to or less than the upper limit, the heat resistance of the laminated film is improved.

[0035] In this specification, the melt flow rate (also referred to as melt mass flow rate) refers to the value measured in accordance with JIS K 7210-1:2014, regardless of whether the outer layer contains rPP, unless otherwise specified.

[0036] The outer layer may or may not contain other components that do not fall under the category of rPP (sometimes referred to herein as "other components (3)"). Examples of the other component (3) contained in the outer layer include resins other than rPP, additives, and the like.

[0037] Examples of the resin other than rPP that is the other component (3) include homopolypropylene (hPP) and elastomers. The inclusion of hPP in the outer layer improves the heat resistance of the laminate film. More specifically, for example, during heat molding of the laminate film, the desired shape can be achieved with higher precision, and the heat-molded body becomes appropriately hard, improving its shape stability. The outer layer containing the elastomer provides the laminated film with higher impact resistance.

[0038] The melt flow rate (MFR) of the hPP contained in the outer layer is preferably 0.1 to 6 g / 10 min, more preferably 0.2 to 5 g / 10 min. When the melt flow rate of the hPP is equal to or higher than the lower limit, the film-formability of the outer layer is improved. When the melt flow rate of the hPP is equal to or lower than the upper limit, the heat resistance of the laminated film is improved.

[0039] Examples of the elastomer contained in the outer layer include styrene-based elastomers (elastomers having structural units derived from styrene and structural units derived from a monomer other than styrene). The elastomer is preferably a hydrogenated styrene-based elastomer (hydrogenated styrene-based elastomer), and more preferably a hydrogenated styrene-butadiene rubber (hydrogenated styrene-butadiene rubber).

[0040] Examples of the additives that are the other components (3) include various additives known in the art, such as pigments, antifogging agents, antiblocking agents, antioxidants, antistatic agents, crystal nucleating agents, inorganic particles, viscosity reducers, thickeners, heat stabilizers, lubricants, infrared absorbers, and ultraviolet absorbers.

[0041] The outer layer may contain only one type of other component (3), 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.

[0042] The outer layer preferably contains rPP and further contains either or both of hPP and the elastomer.

[0043] In the outer layer, the ratio of the rPP content to the total mass of the outer layer ([rPP content in outer layer (parts by mass)] / [total mass of outer layer (parts by mass)] × 100) is preferably 40% by mass or more, more preferably 50% by mass or more, and may be, for example, 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more. When this ratio is equal to or greater than the lower limit, the transparency and impact resistance of the laminated film and the packaging obtained using it are improved. On the other hand, the proportion may be 100% by mass or less, for example, 98% by mass or less. The ratio is usually the same as the ratio of the rPP content to the total content (parts by mass) of components that do not vaporize at room temperature in the resin composition for forming the outer layer, as described below ([rPP content (parts by mass) in the resin composition for forming the outer layer)] / [total content (parts by mass) of components that do not vaporize at room temperature in the resin composition for forming the outer layer]×100). The relationship between the content of the components contained in any layer constituting the laminate film and the content of the components contained in the resin composition for forming that layer is also the same for layers other than the outer layer described below.

[0044] 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.

[0045] The content of the other component (3) in the outer layer can be adjusted appropriately depending on the type of the other component (3).

[0046] When the outer layer contains hPP, the hPP content in the outer layer relative to the total mass of the outer layer is preferably 15% by mass or more, more preferably 25% by mass or more, and may be, for example, 35% by mass or more. When this proportion is equal to or greater than the lower limit, the heat resistance of the laminated film and the package obtained using it is further improved. On the other hand, the ratio is preferably 60% by mass or less, more preferably 50% by mass or less. When the ratio is equal to or less than the upper limit, the transparency, impact resistance, and heat resistance of the laminated film and the package obtained using the same are all improved in a balanced manner.

[0047] When the outer layer contains the elastomer, the proportion of the elastomer in the outer layer relative to the total mass of the outer layer is preferably 2% by mass or more, more preferably 3.5% by mass or more. When the proportion is equal to or greater than the lower limit, the impact resistance of the laminated film and the package obtained using the same is increased. On the other hand, the ratio is preferably 15% by mass or less, and more preferably 10% by mass or less. When the ratio is equal to or less than the upper limit, the laminated film has sufficient hardness, which is more advantageous for maintaining the shape of the molded product.

[0048] In the outer layer, the content of other component (3) that is neither hPP nor the elastomer is preferably 10% by mass or less, and may be, for example, 6% by mass or less or 3% by mass or less, relative to the total mass of the outer layer. When this content is equal to or less than the upper limit, the effects obtained by including components other than the other component (3) in the outer layer are enhanced. On the other hand, the proportion may be 0% by mass or more, for example, 1% by mass or more.

[0049] In the outer layer, the ratio of the total content of rPP, hPP, and the elastomer to the total mass of the outer layer (([rPP content in outer layer (parts by mass)] + [hPP content in outer layer (parts by mass)] + [elastomer content in outer layer (parts by mass)]) / [total mass of outer layer (parts by mass)] × 100) is preferably 80% by mass or more, more preferably 90% by mass or more, and may be, for example, 94% by mass or more or 97% by mass or more. When this ratio is equal to or greater than the lower limit, the effects obtained by containing these components in the laminated film and the packaging obtained using it are further enhanced. On the other hand, the proportion is 100% by mass or less. Here, if the outer layer does not contain hPP, the content of hPP in the outer layer is 0 parts by mass, and if the outer layer does not contain elastomer, the content of elastomer in the outer layer is 0 parts by mass. This also applies to the sealant layer described below.

[0050] The outer layer may consist of one layer (single layer) or two or more layers. When the outer layer consists of multiple layers, these multiple layers may be the same or different, 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 outer layer preferably consists of one layer (single layer).

[0051] In this specification, not only in the case of the outer 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."

[0052] The thickness of the outer layer is preferably 200 to 600 μm, and may be, for example, any of 200 to 500 μm and 200 to 400 μm, any of 300 to 600 μm and 400 to 600 μm, or 300 to 500 μm. When the thickness of the outer layer is equal to or greater than the lower limit, the effect obtained by providing the outer layer in the laminated film is enhanced. When the thickness of the outer layer is equal to or less than the upper limit, the outer layer is prevented from becoming excessively thick. When the outer layer is made up of multiple layers, it is preferable that the total thickness of these multiple layers be within the above-mentioned numerical range. This is not limited to the outer layer, but also applies to layers other than the outer layer described below.

[0053] The ratio of the thickness of the outer layer to the thickness of the laminated film is preferably 20 to 60%, for the same reasons as in the case of the thickness described above, and may be, for example, 30 to 50%. When the outer layer is made up of multiple layers, it is preferable that the ratio of the total thickness of these multiple layers to the thickness of the laminated film is within the above-mentioned range, which is not limited to the outer layer but also applies to layers other than the outer layer described below.

[0054] In this specification, the ratio of the thickness of any layer constituting the laminate film, not limited to the outer layer described above, to the thickness of the laminate film is described, but the total value of the ratios described for each layer shall not exceed 100%.

[0055] <Oxygen barrier layer> The oxygen barrier layer provides the laminated film with oxygen barrier properties (in other words, the property of inhibiting the permeation of oxygen gas) and transparency without causing cloudiness even after retort treatment. The oxygen barrier layer is not the outermost layer in the laminated film. The oxygen barrier layer preferably has transparency.

[0056] In the oxygen barrier layer, the ratio of the total content of one or more components contained in the oxygen barrier layer, which will be described later, to the total mass of the oxygen barrier layer does not exceed 100 mass %. Similarly, in the resin composition for forming an oxygen barrier layer described below, the ratio of the total content of one or more of the components contained in the resin composition for forming an oxygen barrier layer described below to the total mass of the resin composition for forming an oxygen barrier layer does not exceed 100 mass%.

[0057] The retort-resistant oxygen barrier resin enables the oxygen barrier layer to have both oxygen barrier properties and transparency without causing cloudiness or the like even after retort treatment. The oxygen barrier layer contains the modified EVOH as the retort-resistant oxygen barrier resin, or contains a composition containing EVOH and one or more members selected from the group consisting of polyamide, partial dehydration products of carboxylate hydrates, and complete dehydration products of carboxylate hydrates, or may contain both the modified EVOH and the composition. For example, if the oxygen barrier layer only contains EVOH, it will become cloudy after retort treatment, and its transparency will be reduced.

[0058] The modified EVOH, which is a retort-resistant oxygen barrier resin, may be obtained by the same method as that for conventional EVOH, except that, for example, the copolymerization reaction of ethylene and vinyl acetate is carried out in the presence of either or both of a polyamide and a crosslinking accelerator. The polyamide may be any known polyamide such as various nylons. The crosslinking accelerator may also be a known one. Modified EVOH can be obtained, for example, by the method described in JP 2019-1100 A. In the modified EVOH, the ratio (mol) of the amount of structural units derived from ethylene to the total amount (mol) of structural units (copolymerization ratio of ethylene) is preferably 45 mol% or less, more preferably 35 mol% or less, and on the other hand, is preferably 25 mol% or more.

[0059] The EVOH in the composition, which is a retort-resistant oxygen barrier resin, is not particularly limited. In the EVOH, the ratio of the amount (moles) of structural units derived from ethylene to the total amount (moles) of structural units (sometimes referred to herein as the "copolymerization ratio of ethylene") is preferably 50 mol% or less, more preferably 40 mol% or less, and on the other hand, is preferably 25 mol% or more. The melting point of the EVOH is preferably 150°C or higher, more preferably 165°C or higher, and is preferably 200°C or lower.

[0060] In the composition which is a retort-resistant oxygen barrier resin, the polyamide which is allowed to coexist with EVOH may be any known polyamide such as various nylons.

[0061] Similarly, examples of the carboxylate hydrate for forming the partially dehydrated product or the completely dehydrated product to be coexisted with EVOH include hydrates of aromatic carboxylates, aliphatic carboxylates, amino acid salts, and the like. The carboxylate salts that form hydrates have the property of incorporating water molecules as crystal water. The carboxylate hydrates include, for example, saturated hydrates of 1 to 15 hydrates. Examples of the carboxylate include metal salts of carboxylic acids and ammonium salts of carboxylic acids. Among these, the carboxylic acid salt is preferably an alkali metal salt such as a sodium salt or potassium salt of a carboxylic acid, or an alkaline earth metal salt such as a magnesium salt or calcium salt of a carboxylic acid, more preferably an alkali metal salt of a carboxylic acid, and even more preferably a sodium salt or potassium salt of a carboxylic acid. The carboxylate preferably has 1 to 12 carbon atoms. The carboxylate is preferably a monovalent to tetravalent salt. Examples of the partially dehydrated and completely dehydrated carboxylate hydrates include those described in JP-A-2010-59418.

[0062] Examples of the composition that is a retort-resistant oxygen barrier resin include those described in JP-A-2010-59418.

[0063] The retort-resistant oxygen barrier resin contained in the oxygen barrier layer is preferably modified EVOH or a composition containing EVOH, polyamide, and either or both of a partial dehydrated product of a carboxylate hydrate and a complete dehydrated product of a carboxylate hydrate, and the oxygen barrier layer may contain both the modified EVOH and the composition.

[0064] The oxygen barrier layer may or may not contain other components that do not fall under the category of retort-resistant oxygen barrier resins (sometimes referred to in this specification as “other components (2)”). Examples of the other component (2) contained in the oxygen barrier layer include resins other than the retort-resistant oxygen barrier resin, additives, and the like.

[0065] Examples of the other component (2), which is a resin other than the retort-resistant oxygen barrier resin, include oxygen barrier resins other than the retort-resistant oxygen barrier resin (sometimes referred to as "other oxygen barrier resins" in this specification).

[0066] Examples of the other oxygen barrier resins include ethylene-vinyl alcohol copolymer (EVOH) and polyvinylidene chloride (PVDC). The EVOH that is the other oxygen barrier resin may be the same as the EVOH in the composition that is the retort-resistant oxygen barrier resin.

[0067] Examples of the additives that are the other component (2) include the same additives as those that are the other component (3).

[0068] The retort-resistant oxygen barrier resin and the other component (2) (e.g., other oxygen barrier resin, additive) contained in the oxygen barrier layer may each be only one type, 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.

[0069] In the oxygen barrier layer, the content of the retort-resistant oxygen barrier resin relative to the total mass of the oxygen barrier layer is preferably 80 mass% or more, more preferably 90 mass% or more, and may be, for example, either 94 mass% or more or 97 mass% or more. When the content is equal to or more than the lower limit, the transparency of the laminate film after retort treatment and the transparency of a package obtained using the laminate film after retort treatment are further improved. On the other hand, the proportion is 100% by mass or less.

[0070] The content of the other component (2) in the oxygen barrier layer can be adjusted appropriately depending on the type of the other component (2).

[0071] In the oxygen barrier layer, the content of the other oxygen barrier resin relative to the total mass of the oxygen barrier layer is preferably 20 mass% or less, more preferably 10 mass% or less. When this proportion is equal to or less than the upper limit, the effect obtained by including components other than the other component (2) in the oxygen barrier layer is enhanced. On the other hand, the proportion is 0% by mass or more.

[0072] In the oxygen barrier layer, the content of the other component (2) other than the other oxygen barrier resin relative to the total mass of the oxygen barrier layer is preferably 10% by mass or less, and may be, for example, 6% by mass or less or 3% by mass or less. When the content is equal to or less than the upper limit, the effect obtained by the oxygen barrier layer containing such a component other than the other component (2) is further enhanced. On the other hand, the proportion is 0% by mass or more.

[0073] When the oxygen barrier layer contains EVOH, the proportion of the EVOH content in the oxygen barrier layer relative to the total mass of the oxygen barrier layer is preferably 50% by mass or more, and may be, for example, 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more, regardless of whether the EVOH is derived from a retort-resistant oxygen barrier resin or another oxygen barrier resin. When the proportion is equal to or greater than the lower limit, the transparency of the laminate film after retort treatment and the transparency of a package obtained using the laminate film after retort treatment are further improved. On the other hand, the proportion is 100% by mass or less.

[0074] The oxygen barrier layer may consist of one layer (single layer) or two or more layers. When the oxygen barrier 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 oxygen barrier layer preferably consists of one layer (single layer).

[0075] The thickness of the oxygen barrier layer is preferably 40 to 140 μm, and may be, for example, any of 40 to 110 μm and 40 to 80 μm, or any of 70 to 140 μm and 10 to 140 μm, or may be 70 to 110 μm. When the thickness of the oxygen barrier layer is equal to or greater than the lower limit, the effect obtained by providing the oxygen barrier layer in the laminated film is enhanced. When the thickness of the oxygen barrier layer is equal to or less than the upper limit, the oxygen barrier layer can be prevented from becoming excessively thick.

[0076] The ratio of the thickness of the oxygen barrier layer to the thickness of the laminated film is preferably 4 to 14%, for the same reasons as in the case of the thickness described above, and may be, for example, 7 to 11%.

[0077] <Sealant layer> The sealant layer provides sealing properties to the laminated film and also has the same function as the outer layer. The exposed surface of the sealant layer becomes the sealing surface with an object to be sealed when a package, which will be described later, is produced using the laminated film. The sealant layer preferably has transparency.

[0078] In the sealant layer, the ratio of the total content of one or more components contained in the sealant layer, which will be described later, to the total mass of the sealant layer does not exceed 100 mass %. Similarly, in the resin composition for forming a sealant layer described later, the ratio of the total content of one or more of the components contained in the resin composition for forming a sealant layer described later to the total mass of the resin composition for forming a sealant layer does not exceed 100 mass%.

[0079] The sealant layer comprises rPP. The rPP contained in the sealant layer may be the same as the rPP contained in the outer layer.

[0080] The sealant layer may or may not contain other components that do not fall under the category of rPP (sometimes referred to herein as "other components (1)"). The other component (1) contained in the sealant layer may be the same as the other component (3) contained in the outer layer (for example, resins other than rPP such as hPP and elastomers; additives, etc.). For example, by including hPP in the sealant layer, the sealant layer has sealing properties while the heat resistance of the laminated film is improved. More specifically, for example, during heat molding of the laminated film, the desired shape can be achieved with higher precision, and the heat-molded body becomes appropriately hard, improving its shape stability. By including an elastomer in the sealant layer, the sealant layer has sealing properties and the impact resistance of the laminated film is improved.

[0081] The sealant layer may contain only one type of other component (1) 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.

[0082] The sealant layer contains rPP, and preferably further contains either or both of hPP and the elastomer.

[0083] The sealant layer may be the same as or different in composition from the outer layer. In other words, the components contained in the sealant layer and the components contained in the outer layer may be the same as or different from each other, and when the sealant layer contains the same component as the component contained in the outer layer, the ratio of the content (parts by mass) of that same component in the sealant layer to the total mass of the sealant layer may be the same as or different from the ratio of the content (parts by mass) of that same component in the outer layer to the total mass of the outer layer. In terms of composition, the sealant layer and the outer layer being the same means that all of the components contained in the sealant layer and all of the components contained in the outer layer are identical, and the ratio of the content (parts by mass) of each component in the sealant layer relative to the total mass of the sealant layer and the ratio of the content (parts by mass) of each component in the outer layer relative to the total mass of the outer layer are identical.

[0084] In the sealant layer, the proportion of the rPP content relative to the total mass of the sealant layer is preferably 40% by mass or more, more preferably 50% by mass or more, and may be, for example, any of 60% by mass or more, 70% by mass or more, 80% by mass or more, and 90% by mass or more. When the proportion is equal to or greater than the lower limit, the sealant layer has sealing properties, and the transparency and impact resistance of the laminated film and the package obtained using it are improved. On the other hand, the proportion may be 100% by mass or less, for example, 98% by mass or less. The ratio of the rPP content in the sealant layer to the total weight of the sealant layer may be the same as or different from the ratio of the rPP content in the outer layer to the total weight of the outer layer, but is preferably the same. If they are the same, the curl suppression effect of such a laminate film will be enhanced.

[0085] The content of the other component (3) in the sealant layer can be adjusted appropriately depending on the type of the other component (3).

[0086] When the sealant layer contains hPP, the content of hPP in the sealant layer relative to the total mass of the sealant layer is preferably 15% by mass or more, more preferably 25% by mass or more, and may be, for example, 35% by mass or more. When this content is equal to or greater than the lower limit, the sealant layer has sealing properties, and the heat resistance of the laminated film and the package obtained using it is improved. On the other hand, the ratio is preferably 55% by mass or less, more preferably 45% by mass or less. When the ratio is equal to or less than the upper limit, the sealant layer has sealing properties, and the laminated film and the package obtained using the same all have high and balanced transparency, impact resistance, and heat resistance. The ratio of the hPP content in the sealant layer to the total weight of the sealant layer may be the same as or different from the ratio of the hPP content in the outer layer to the total weight of the outer layer, but is preferably the same. If they are the same, the curl suppression effect of such a laminate film is enhanced.

[0087] When the sealant layer contains the elastomer, the content of the elastomer in the sealant layer relative to the total mass of the sealant layer is preferably 1% by mass or more, more preferably 3% by mass or more. When the content is equal to or more than the lower limit, the sealant layer has sealing properties, and the impact resistance of the laminated film and the package obtained using the same is increased. On the other hand, the ratio is preferably 10% by mass or less, and more preferably 7% by mass or less. When the ratio is equal to or less than the upper limit, the laminated film has sufficient hardness, which is more advantageous for maintaining the shape of the molded product. The ratio of the elastomer content in the sealant layer to the total mass of the sealant layer may be the same as or different from the ratio of the elastomer content in the outer layer to the total mass of the outer layer, but is preferably the same. If they are the same, the curl suppression effect of such a laminate film is enhanced.

[0088] In the sealant layer, the content of other component (1) that is neither hPP nor the elastomer is preferably 10% by mass or less, and may be, for example, 6% by mass or less or 3% by mass or less, relative to the total mass of the sealant layer. When this content is equal to or less than the upper limit, the sealant layer has sealing properties, and the effects obtained by including components other than the other component (1) in the sealant layer are further enhanced. On the other hand, the proportion may be 0% by mass or more, for example, 1% by mass or more. The ratio of the content of the other component (1) in the sealant layer to the total mass of the sealant layer may be the same as or different from the ratio of the content of the other component (1) in the outer layer to the total mass of the outer layer, but is preferably the same. If they are the same, the curl suppression effect of such a laminate film is enhanced.

[0089] In the sealant layer, the proportion of the combined content of rPP, hPP, and the elastomer relative to the total mass of the sealant layer is preferably 80% by mass or more, more preferably 90% by mass or more, and may be, for example, 94% by mass or more or 97% by mass or more. When this proportion is equal to or greater than the lower limit, the sealant layer has sealing properties, and the effects obtained by containing these components in the laminate film and the package obtained using it are further enhanced. On the other hand, the proportion is 100% by mass or less. The ratio of the total content of rPP, hPP, and the elastomer in the sealant layer to the total weight of the sealant layer may be the same as or different from the ratio of the total content of rPP, hPP, and the elastomer in the outer layer to the total weight of the outer layer, but is preferably the same. If they are the same, the curl suppression effect of such a laminate film will be enhanced.

[0090] The sealant layer may consist of one layer (single layer) or two or more layers. When the sealant layer consists of multiple layers, these multiple layers may be the same or different, 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 sealant layer preferably consists of one layer (single layer).

[0091] The thickness of the sealant layer is preferably 200 to 600 μm, and may be, for example, any of 200 to 500 μm and 200 to 400 μm, any of 300 to 600 μm and 400 to 600 μm, or 300 to 500 μm. When the thickness of the sealant layer is equal to or greater than the lower limit, the effect obtained by providing the sealant layer in the laminated film is enhanced. When the thickness of the sealant layer is equal to or less than the upper limit, excessive thickness of the sealant layer can be avoided.

[0092] The ratio of the thickness of the sealant layer to the thickness of the laminated film is preferably 20 to 60%, for the same reasons as in the case of the thickness described above, and may be, for example, 30 to 50%.

[0093] ◎Relationship between outer layer and sealant layer In the laminated film, the components contained in the outer layer and the components contained in the sealant layer are preferably the same. An example of a preferred laminated film is one in which the sealant layer and the outer layer further contain hPP in addition to rPP. Another example of a preferred laminated film is one in which the sealant layer and the outer layer further contain an elastomer in addition to rPP, and it is more preferable that the sealant layer and the outer layer contain a hydrogenated styrene-based elastomer as the elastomer. A more preferred example of the laminated film is one in which the sealant layer and the outer layer contain hPP and an elastomer in addition to rPP, and it is particularly preferred that the sealant layer and the outer layer contain a hydrogenated styrene-based elastomer as the elastomer.

[0094] In the laminated film, both the outer layer and the sealant layer comprise rPP and either or both of hPP and an elastomer; the ratio of the rPP content in the outer layer to the total mass of the outer layer and the ratio of the rPP content in the sealant layer to the total mass of the sealant layer are both within any of the above-mentioned numerical ranges; When the outer layer and the sealant layer contain hPP, the ratio of the hPP content in the outer layer to the total mass of the outer layer and the ratio of the hPP content in the sealant layer to the total mass of the sealant layer are both within any of the above-mentioned numerical ranges; When the outer layer and the sealant layer contain an elastomer, it is more preferable that the ratio of the elastomer content in the outer layer to the total mass of the outer layer and the ratio of the elastomer content in the sealant layer to the total mass of the sealant layer are both within any of the above-mentioned numerical ranges. In laminated films, it is particularly preferred that the outer layer and the sealant layer are identical in composition. The laminated films described herein have a particularly high curl suppression effect due to the fact that the outer layer and the sealant layer are similar or identical in composition.

[0095] In laminated films, the thickness of the sealant layer may be the same as or different from the thickness of the outer layer. In particular, the thickness of the sealant layer is preferably 0.9 to 1.1 times, more preferably 0.95 to 1.05 times, and even more preferably 0.97 to 1.03 times the thickness of the outer layer. In such a laminated film, the outer layer and the sealant layer have similar or identical thicknesses, thereby providing a higher curl suppression effect.

[0096] <Adhesive layer> The adhesive layer is a layer for adhering two adjacent layers together in the laminated film, and contains a component that exhibits adhesiveness. The adhesive layer preferably has transparency.

[0097] The position of the adhesive layer in the laminated film is not particularly limited as long as it is not the outermost layer of the laminated film. The laminated film preferably has an adhesive layer between the sealant layer and the oxygen barrier layer, and between the outer layer and the oxygen barrier layer.

[0098] The adhesive layer is preferably a resin layer containing an adhesive resin as a component that exhibits the above-mentioned adhesiveness. The adhesive resin may be a known one, preferably a propylene copolymer, more preferably an acid-modified polypropylene, etc. An adhesive layer containing a propylene copolymer as an adhesive resin more strongly bonds the outer layer and the sealant layer to other layers such as the oxygen barrier layer.

[0099] In this specification, the term "propylene-based copolymer" refers to a copolymer having structural units derived from propylene and structural units derived from a monomer other than propylene.

[0100] Examples of the propylene copolymer that is an adhesive resin include a copolymer of propylene and a vinyl group-containing monomer, and modified products thereof (modified copolymers). More specifically, examples include maleic anhydride-grafted modified linear low-density polypropylene and propylene-based thermoplastic elastomers.

[0101] In the adhesive layer, the content of the component that exhibits adhesiveness relative to the total mass of the adhesive layer is preferably 80 mass % or more, more preferably 90 mass % or more. When this proportion is equal to or greater than the lower limit, the adhesiveness of the adhesive layer is further increased. On the other hand, the proportion is 100% by mass or less.

[0102] The adhesive layer may consist of one layer (single layer) or two or more layers, but is preferably made up of one layer (single layer).

[0103] The thickness of the adhesive layer is preferably 10 to 40 μm. When the thickness of the adhesive layer is equal to or greater than the lower limit, the effect obtained by providing the adhesive layer in the laminated film is enhanced. When the thickness of the adhesive layer is equal to or less than the upper limit, the adhesive layer can be prevented from becoming excessively thick. The ratio of the thickness of the adhesive layer to the thickness of the laminated film is preferably 1 to 4% for the same reasons as in the case of the thickness described above.

[0104] <Other layers> The laminated film of this embodiment may or may not have other layers that do not fall under any of the sealant layer, oxygen barrier layer, outer layer, and adhesive layer, as long as the effects of the present invention are not impaired. The type of the other layer is not particularly limited and can be selected arbitrarily depending on the purpose. The thickness of the other layer is not particularly limited, and can be selected arbitrarily depending on the type of the other layer. When the laminated film has the other layers, the positions and number of the other layers in the laminated film are not particularly limited and can be selected arbitrarily depending on the type or purpose of the other layers.

[0105] It is preferable that the laminate film does not include the other layers. Such a laminate film and a package obtained using the same will have higher transparency and impact resistance before and after retort treatment.

[0106] <Thickness of laminated film> The thickness (total thickness) of the laminate film is not particularly limited, but is preferably 800 to 1200 μm, and may be, for example, either 850 to 1150 μm or 900 to 1100 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 and can be more easily formed.

[0107] <<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.

[0108] 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.

[0109] 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. Alternatively, a laminated film can be produced by laminating two or more films that have been separately prepared in advance with an adhesive.

[0110] 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.

[0111] Examples of the resin compositions for forming the sealant layer and the outer layer include resin compositions containing rPP and the other components described above. Examples of the resin composition for forming the oxygen barrier layer include a resin composition containing a retort-resistant oxygen barrier resin and, if necessary, the other components described above.

[0112] <<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 is therefore suitable for retort treatment, preferably retort sterilization treatment, and the packaging body has high transparency and impact resistance both before and after the retort treatment.

[0113] An example of a preferred package of this embodiment is a package having a lid material and a base material, the package being formed by sealing the lid material and the base material, and the base material being formed using the laminated film.

[0114] FIG. 2 is a cross-sectional view schematically showing an example of the packaging body of this embodiment. 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 of this embodiment, and more specifically, is a molded body (heat-molded body) of the laminated film. However, in the base material 10 in FIG. 2, the distinction between the layers in the laminated film that constitutes it is omitted.

[0115] The base material 10 has a recess 100 formed therein. One surface 10b of the area of ​​the base material 10 excluding the recess 100 (sometimes referred to as the "second surface" in this specification) and one surface 8b of the cover material 8 (sometimes referred to as the "second surface" in this specification) are both sealing surfaces and face each other. The package 101 is formed by sealing the lid material 8 and the base material 10. More specifically, the second surface 10b of the base material 10 in the area excluding the recess 100 and the second surface 8b of the lid material 8 are overlapped and sealed to each other in the area near their peripheral edges. 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.

[0116] When the base material 10 is constructed using the laminated film 1 shown in Figure 1, one second surface 10b of the base material 10 corresponds to the second surface 11b of the sealant layer 11 in the laminated film 1, and the other surface (sometimes referred to as the "first surface" in this specification) 10a of the base material 10 corresponds to the first surface 13a of the outer layer 13 in the laminated film 1.

[0117] The lid material 8 may be, for example, a lid material (resin film) having a layer containing polypropylene such as hPP.

[0118] In Figure 2, some gaps can be seen between the stored item 9 and the packaging body 101 within the storage section 101a of the packaging body 101, but the presence of these gaps is not essential for the packaging body 101 in which the stored item 9 is stored, and the gaps do not have to be present.

[0119] 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 40 to 150 μm, and more preferably 60 to 100 μm.

[0120] The stored items 9 are preferably food items.

[0121] Since the base material 10 is constructed using the laminated film, the transparency and impact resistance of the base material 10 are high before the retort treatment of the packaging body 101, and the transparency and impact resistance of the base material 10 are also high after the retort treatment of the packaging body 101.

[0122] The packaging body of this embodiment is not limited to the above-described aspects, and some of the configuration may be changed, deleted, or added within the scope of the spirit of the present invention. For example, although the packaging body 101 is configured using a molded body of the laminated film, the packaging body of this embodiment may be configured using a non-molded body of the laminated film.

[0123] <<Packaging manufacturing method>> The package can be produced by a known method except for using the laminate film. For example, the package can be produced by heat-sealing the laminate film or a molded product thereof (e.g., a base material) and an object to be sealed (e.g., a lid material) while forming a storage section and storing the object to be packaged in the storage section.

[0124] The laminated film molded article such as the base material can be produced by a known method. For example, the molding temperature is preferably 180 to 500°C.

[0125] When heat sealing the laminated film or its molded body with the object to be sealed, the sealing temperature is preferably 140 to 220° C., the sealing pressure is preferably 0.1 to 0.3 MPa, and the sealing time is preferably 1 to 3 seconds. [Example]

[0126] 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.

[0127] The raw materials used in each example or comparative example are as follows. rPP: Propylene-ethylene random copolymer (Japan Polypropylene Corporation, "Novatec (registered trademark) EG7FTB", MFR 1.3 g / 10 min) hPP: Homopolypropylene (Novatec (registered trademark) FY4, manufactured by Japan Polypropylene Corporation, MFR 5g / 10min) bPP: propylene-ethylene block copolymer (Sumitomo Chemical Co., Ltd. "Sumitomo Noblen (registered trademark) AH1311", MFR 0.5 g / 10 min) ROR: Retort-resistant oxygen barrier resin (the above-mentioned modified ethylene-vinyl alcohol copolymer, copolymerization ratio of ethylene 29 mol%, "Soarnol (registered trademark) RB7204B" manufactured by Mitsubishi Chemical Corporation) EVOH: ethylene-vinyl alcohol copolymer ("Soarnol (registered trademark) BF3203B" manufactured by Mitsubishi Chemical Corporation, copolymerization ratio of ethylene 32 mol%, melting point 183°C) ELA: Hydrogenated styrene-butadiene rubber (JSR "Dynaron 1320P") Modified PP: Acid-modified polypropylene (adhesive resin, Mitsubishi Chemical Corporation's "Modic (registered trademark) ER313E-1")

[0128] [Example 1] <<Laminated film manufacturing>> A laminated film having the structure shown in FIG. 1 was produced according to the following procedure. That is, the rPP (55 parts by mass), the hPP (40 parts by mass), and the ELA (5 parts by mass) were mixed at room temperature to prepare a resin composition (1).

[0129] By co-extruding the resin composition (1), the modified PP, the ROR, the modified PP, and the resin composition (1) in this order, a transparent laminated film (thickness 1000 μm) was obtained, which was composed of a sealant layer (thickness 432 μm), a first adhesive layer (thickness 23 μm), an oxygen barrier layer (thickness 90 μm), a second adhesive layer (thickness 23 μm), and an outer layer (thickness 432 μm) laminated in this order in the thickness direction.

[0130] <<Evaluation of laminated film>> <Measurement of haze and transparency of laminated films> The haze of the laminated film obtained above was measured from the outside of the outer layer side in accordance with JIS K 7136:2000. Furthermore, the transparency of the laminated film was evaluated based on the measured value according to the following criteria. The results are shown in Table 1. [Evaluation criteria] A: The haze is 35% or less, and the transparency of the laminated film is particularly high. B: The haze is more than 35% and not more than 43%, and the transparency of the laminated film is high. C: Haze is more than 43% and 78% or less, and the transparency of the laminated film is standard. D: The haze is more than 78%, and the transparency of the laminated film is low or the laminated film has no transparency.

[0131] <Measurement of tensile impact strength of laminated film> The tensile impact strength of the laminated film obtained above was measured in the direction of flow of the resin (MD) and the direction perpendicular to the direction of flow of the resin (TD) in accordance with JIS K 7160A. The results are shown in Table 1.

[0132] <Measurement of haze and transparency of laminated film after retort treatment> The laminated film obtained above was retorted at 121°C for 30 minutes. The haze of the retorted laminated film was measured from the outside of the outer layer side in accordance with JIS K 7136:2000. Furthermore, the transparency of the retorted laminated film was evaluated based on the measured value according to the following criteria. The results are shown in Table 1. [Evaluation criteria] A: The haze is 43% or less, and the transparency of the laminated film after retort treatment is high. B: Haze is more than 43% and 78% or less, and the transparency of the laminated film after retort treatment is standard. C: The haze is more than 78%, and the transparency of the laminated film after retort treatment is low or the laminated film after retort treatment has no transparency.

[0133] <<Laminated Film Manufacturing and Evaluation>> [Example 2] The rPP (95 parts by mass) and the ELA (5 parts by mass) were mixed at room temperature to prepare a resin composition (2).

[0134] A transparent laminated film (thickness 1000 μm) was obtained in the same manner as in Example 1, except that resin composition (2) was used instead of resin composition (1) as the resin constituting the sealant layer and outer layer. The film was constructed by laminating a sealant layer (thickness 432 μm), a first adhesive layer (thickness 23 μm), an oxygen barrier layer (thickness 90 μm), a second adhesive layer (thickness 23 μm), and an outer layer (thickness 432 μm) in this order in the thickness direction.

[0135] The obtained laminated film was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0136] [Comparative Example 1] A transparent laminated film (thickness 800 μm) was obtained in the same manner as in Example 1, except that the resin constituting the sealant layer and outer layer was made of the above-mentioned hPP instead of the resin composition (1), and the conditions for co-extrusion of the resins were changed so that the overall thickness of the resulting laminated film would be thinner than in Example 1. The sealant layer (thickness 364 μm), the first adhesive layer (thickness 20 μm), the oxygen barrier layer (thickness 32 μm), the second adhesive layer (thickness 20 μm), and the outer layer (thickness 364 μm) were laminated in this order in the thickness direction. The obtained laminated film was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0137] Comparative Example 2 A transparent laminated film (thickness 800 μm) was obtained in the same manner as in Example 1, except that the bPP was used instead of the resin composition (1) as the resin constituting the sealant layer and outer layer, and the conditions for co-extrusion of the resins were changed so that the overall thickness of the resulting laminated film would be thinner than in Example 1. The sealant layer (thickness 364 μm), first adhesive layer (thickness 20 μm), oxygen barrier layer (thickness 32 μm), second adhesive layer (thickness 20 μm), and outer layer (thickness 364 μm) were laminated in this order in the thickness direction. The obtained laminated film was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0138] [Table 1]

[0139] As is clear from the above results, in Examples 1 and 2, the haze of the laminated films was 25% or less (20 to 25%), and the transparency of the laminated films was high. In Examples 1 and 2, the tensile impact strength of the laminated film in the machine direction (MD) of the resin was 380 kJ / m 2 or more (380~400kJ / m 2 ) and the tensile impact strength in the direction perpendicular to the resin flow (TD) is 280kJ / m 2 or more (280~300kJ / m 2 ) and the impact resistance of the laminated film was also high. In Examples 1 and 2, the sealant layer and outer layer of the laminated film contained rPP. The MD and TD tensile impact strengths of these laminated films were sufficiently high, and although the sealant layer and outer layer contained ELA in addition to rPP, it was estimated that these tensile impact strengths would be high even if they did not contain ELA.

[0140] Furthermore, in Examples 1 and 2, the haze of the laminated films after the retort treatment was 35% or less (30 to 35%), and the transparency of the laminated films after the retort treatment was also high. In Examples 1 and 2, the oxygen barrier layer of the laminated film contained ROR as a retort-resistant oxygen barrier resin.

[0141] Thus, the laminated films of Examples 1 and 2 were excellent in both transparency and impact resistance before and after retort treatment, and similarly, it was possible to form a package that was excellent in both transparency and impact resistance before and after retort treatment.

[0142] The laminate film of Example 1, whose sealant layer and outer layer contained hPP in addition to rPP, had higher heat resistance than the laminate film of Example 2, whose sealant layer and outer layer did not contain hPP. In this respect, the laminate film of Example 1 was more suitable for producing cup-shaped containers or base materials that could be used in a similar manner by thermoforming.

[0143] In contrast, in Comparative Example 1, the haze of the laminated film before and after retort treatment and the TD tensile impact strength were both inferior to those of Examples 1 and 2, and the laminated film of Comparative Example 1 in particular had inferior impact resistance in terms of its TD tensile impact strength. In Comparative Example 1, the oxygen barrier layer of the laminated film did not contain a retort-resistant oxygen barrier resin, and the sealant layer and outer layer did not contain rPP.

[0144] In Comparative Example 2, the haze of the laminated film before and after retort treatment was inferior to that of Examples 1 and 2, and the laminated film of Comparative Example 2 in particular had inferior transparency in terms of the haze of the laminated film after retort treatment. In Comparative Example 2, the oxygen barrier layer of the laminated film also did not contain a retort-resistant oxygen barrier resin, and the sealant layer and outer layer did not contain rPP. However, the haze of the laminated film of Comparative Example 2 before and after retort treatment was even worse than that of Comparative Example 1, while the impact resistance of the laminated film of Comparative Example 2 was higher than that of Comparative Example 1. This was because the sealant layer and outer layer of the laminated film of Comparative Example 2 contained bPP instead of hPP.

[0145] As described above, the laminate film of Comparative Example 1 was particularly poor in impact resistance, and the laminate film of Comparative Example 2 was particularly poor in transparency after retort treatment. These laminate films were not capable of forming excellent packages in terms of impact resistance or transparency after retort treatment. [Industrial Applicability]

[0146] The present invention can be used to manufacture packages for retort treatment. [Explanation of symbols]

[0147] 1. Laminated film 11. Sealant layer 12. Oxygen barrier layer 13...outer layer 14...adhesive layer, 141...first adhesive layer, 142...second adhesive layer 101...Packaging 8...Lid material 10...Bottom material

Claims

1. A laminated film comprising a sealant layer, an oxygen barrier layer, and an outer layer laminated in this order in a thickness direction, the sealant layer and the outer layer comprise a propylene-ethylene random copolymer; the oxygen barrier layer comprises a retort-resistant oxygen barrier resin, The retort-resistant oxygen barrier resin is either one or both of a modified ethylene-vinyl alcohol copolymer obtained by copolymerizing ethylene and vinyl acetate in the presence of either or both of a polyamide and a crosslinking accelerator, followed by a saponification treatment, and a composition containing an ethylene-vinyl alcohol copolymer and one or more members selected from the group consisting of polyamides, partial dehydrated carboxylate hydrates, and complete dehydrated carboxylate hydrates.

2. The laminate film of claim 1 , wherein the sealant layer and the outer layer further comprise homopolypropylene.

3. The laminated film according to claim 1 or 2, wherein the sealant layer and the outer layer further comprise an elastomer.

4. The laminated film according to claim 3 , wherein the sealant layer and the outer layer contain a hydrogenated styrene-based elastomer as the elastomer.

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

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