Laminated film, packaging material and package

Abstract

To provide a laminated film having improved interlayer peel strength when compared with films having the same configuration except for a core layer and a skin layer.SOLUTION: There is provided a laminated film comprising a core layer containing high-density polyethylene, a skin layer containing linear low-density polyethylene, and a barrier resin layer in this order, in which when a content of linear low-density polyethylene in the core layer relative to an entire core layer is defined as W1 and a content of linear low-density polyethylene in the skin layer relative to the entire skin layer is defined as W2, a relationship W2>W1 is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Polyethylene films are known as films used for packaging materials and the like.

[0003] Patent Document 1 describes a laminated film having a surface layer (A), an intermediate layer (B), and a heat seal layer (C) laminated together, with the objective of providing a laminated film having suitable retort resistance even at a retort sterilization temperature of 125°C and excellent impact resistance even at a low temperature below 0°C, wherein the surface layer (A), the intermediate layer (B), and the heat seal layer (C) contain an ethylene-based resin as a main resin component, and the average density of the resin component in each layer is 0.933 g / cm. 3 The present invention describes a laminated film characterized in that at least one of the surface layer (A) and the intermediate layer (B) contains an olefin-based thermoplastic elastomer, and the content of the olefin-based thermoplastic elastomer is 15 mass% or more of the total amount of resin components in the entire laminated film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 215538 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a laminated film having improved interlayer peel strength when compared with films having the same configuration except for the core layer and skin layer. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems, and as a result have found that in a laminate film having a core layer containing high-density polyethylene and a barrier resin layer, the peel strength between the layers can be improved by providing a skin layer containing linear low-density polyethylene between the core layer and the barrier resin layer, thereby completing the present invention.

[0007] That is, according to the present invention, there are provided the following laminated film, packaging material, and packaging body.

[0008] [1] a core layer comprising high density polyethylene; a skin layer comprising linear low density polyethylene; a barrier resin layer; In this order, the content of the linear low-density polyethylene in the core layer relative to the entire core layer is designated as W1, When the content of the linear low-density polyethylene in the skin layer relative to the entire skin layer is W2, A laminated film that satisfies the relationship W2>W1. [2] The density of the skin layer is 0.910 g / cm 3 More than 0.942g / cm 3 The laminated film according to [1], wherein the thickness is less than 1 / 2 mm. [3] The density of the core layer minus the density of the skin layer is 0.005 g / cm 3 The laminated film according to [1] or [2] above. [4] The density of the core layer is 0.942 g / cm 3 The laminated film according to any one of [1] to [3] above. [5] The laminated film according to any one of [1] to [4], wherein the content (W2) of linear low-density polyethylene in the skin layer relative to the entire skin layer is 50% by mass or more and 100% by mass or less. [6] The laminated film according to any one of [1] to [5], wherein the content (W1) of linear low-density polyethylene in the core layer relative to the entire core layer is 0% by mass or more and less than 50% by mass. [7] The laminated film according to any one of [1] to [6], wherein the thickness of the skin layer is 0.1 μm or more and 10 μm or less. [8] The laminated film according to any one of [1] to [7], wherein the ratio of the thickness of the skin layer to the total thickness of the core layer and the skin layer is 0.5% or more and 50% or less. [9] The laminated film according to any one of [1] to [8], wherein the content of the high-density polyethylene in the core layer is 50% by mass or more and 100% by mass or less based on the total mass of the core layer.

[10] The laminated film according to any one of [1] to [9], wherein the thickness of the core layer is 5 μm or more and 100 μm or less.

[11] The laminated film according to any one of [1] to

[10] , wherein the ratio of the thickness of the core layer to the total thickness of the core layer and the skin layer is 50% or more and less than 100%.

[12] The laminate film according to any one of [1] to

[11] , wherein the barrier resin layer comprises one or more resin layers selected from the group consisting of a cured product layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound, a polyvinylidene chloride resin layer, a polyurethane resin layer, and a polyvinyl alcohol resin layer.

[13] The laminated film according to any one of [1] to

[12] , wherein at least one of the core layer and the skin layer includes a stretched film layer.

[14] The laminated film according to any one of [1] to

[13] , wherein the skin layer and the core layer are in direct contact with each other.

[15] The laminated film according to any one of [1] to

[14] , wherein the skin layer and the barrier resin layer are in direct contact with each other.

[16] The laminated film according to any one of [1] to

[14] , wherein the barrier resin layer is provided on the skin layer via an anchor coat layer.

[17] The laminate film according to any one of [1] to

[16] , wherein the developed area ratio Sdr of the surface of the skin layer on the barrier resin layer side, measured in accordance with ISO 25178, is less than 3.10%.

[18] The laminate film according to any one of [1] to

[17] , wherein the 180° peel strength between the laminate film and the LLDPE film, measured by the following method, exceeds 2.2 N / 15 mm. (method) An adhesive is applied to one side of a 50 μm-thick LLDPE film. The laminated film and the LLDPE film are then laminated together so that the surface of the laminated film facing the barrier resin layer is in contact with the adhesive-coated surface of the LLDPE film. The peel strength between the laminated film and the LLDPE film is measured at 25°C and a pulling rate of 300 mm / min.

[19] The laminate film according to any one of [1] to

[18] , wherein the 180° peel strength between the laminate film and the LLDPE film, measured by the following method, exceeds 0.8 N / 15 mm. (method) An adhesive is applied to one side of a 50 μm-thick LLDPE film. The laminated film and the LLDPE film are then laminated together so that the barrier resin layer side of the laminated film is in contact with the adhesive-coated side of the LLDPE film, yielding a multilayer film. The resulting multilayer film is then boiled at 85°C for 30 minutes. The peel strength between the laminated film and the LLDPE film after the boiling treatment is measured at 25°C and a pulling rate of 300 mm / min.

[20] The laminated film according to any one of [1] to

[19] , which is a packaging film. [twenty one] A packaging material comprising the laminated film according to any one of [1] to

[20] . [twenty two] The packaging material according to

[21] , further comprising a heat seal layer on at least one outermost layer. [twenty three] The packaging material according to

[22] , comprising the core layer, the skin layer, the barrier resin layer, and the heat seal layer in this order. [twenty four] The packaging material according to

[22] or

[23] , wherein the heat seal layer contains polyethylene. [twenty five] The packaging material according to any one of

[21] to

[24] , further comprising a coating layer on at least one surface of the laminated film.

[26]

[21] to

[25] , and a packaging material according to any one of

[21] to

[25] . and an item within the packaging material. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a laminated film having improved interlayer peel strength when compared between films having the same configuration except for the core layer and skin layer. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of a laminated film according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view schematically illustrating an example of a laminated film according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are schematic diagrams and do not correspond to actual dimensional proportions. In this specification, "A to B" indicating a numerical range means A or more and B or less unless otherwise specified.

[0012] In this embodiment, low-density polyethylene (LDPE) has a density of 0.910 g / cm 3More than 0.930g / cm 3 Medium density polyethylene (MDPE) refers to polyethylene having a density less than 0.930 g / cm 3 More than 0.942g / cm 3 High density polyethylene (HDPE) refers to polyethylene having a density less than 0.942 g / cm 3 It refers to polyethylene with a density equal to or greater than 100%. Low-density polyethylene and medium-density polyethylene with little branching are referred to as linear low-density polyethylene (LLDPE).

[0013] (Laminated film) 1 and 2 are cross-sectional views schematically illustrating an example of a laminate film according to the present embodiment. As shown in FIGS. 1 and 2, the laminate film 100 of the present embodiment includes, in this order, a core layer 11 containing high-density polyethylene, a skin layer 13 containing linear low-density polyethylene, and a barrier resin layer 30. When the content of linear low-density polyethylene in the core layer 11 relative to the entire core layer 11 is defined as W1 and the content of linear low-density polyethylene in the skin layer 13 relative to the entire skin layer 13 is defined as W2, the laminate film 100 of the present embodiment satisfies the relationship W2 > W1. That is, when the contents (mass %) of linear low-density polyethylene in the layers are compared, the content in the skin layer 13 is greater than the content in the core layer 11.

[0014] The present inventors have discovered that in a laminate film 100 comprising a core layer 11 containing high-density polyethylene and a barrier resin layer 30, the interlayer peel strength can be improved by providing a skin layer 13 containing linear low-density polyethylene between the core layer 11 and the barrier resin layer 30, and have completed the present invention. More specifically, when the content of linear low-density polyethylene in the core layer 11 relative to the entire core layer 11 is defined as W1 and the content of linear low-density polyethylene in the skin layer 13 relative to the entire skin layer 13 is defined as W2, the inventors have discovered that by satisfying the relationship W2 > W1, the interlayer peel strength can be improved when compared between films having the same configuration except for the core layer 11 and the skin layer 13.

[0015] The mechanism by which the interlayer peel strength can be improved by satisfying the relationship W2>W1 is not entirely clear, but according to the investigations of the present inventors, it is presumed as follows.

[0016] First, it is believed that satisfying the relationship W2>W1 makes it possible to obtain a film (a film in which the core layer 11 and the skin layer 13 are laminated) with smaller surface roughness on the side of the skin layer 13 opposite to the core layer 11 (the surface of the skin layer 13 on the barrier resin layer 30 side). The mechanism behind this is not entirely clear, but one possible factor is the difference in softening point or glass transition temperature between the core layer 11 and the skin layer 13, for example.

[0017] Next, it is believed that the smaller surface roughness of the surface can improve the bonding between the skin layer 13 and a layer laminated on the surface (for example, the barrier resin layer 30 or the anchor coat layer 50 described below). In this way, it is believed that the bonding between the barrier resin layer 30 and a layer adjacent to the barrier resin layer 30 (for example, the skin layer 13 or the anchor coat layer 50) can be improved in the laminate film 100. Therefore, when compared between films having the same configuration except for the core layer 11 and the skin layer 13, it is believed that a laminate film 100 with improved interlayer peel strength can be obtained.

[0018] In this embodiment, the term "interlayer peel strength" refers to the peel strength between the barrier resin layer 30 and a layer adjacent to the barrier resin layer 30. That is, in this embodiment, the term "interlayer peel strength" includes the peel strength between the barrier resin layer 30 and the skin layer 13, and the peel strength between the barrier resin layer 30 and the anchor coat layer 50. In addition, when the barrier resin layer 30 is the outermost layer of the laminate film 100 and the laminate film 100 is laminated with another film to form a multilayer film, the term "interlayer peel strength" also includes the peel strength between the barrier resin layer 30 and another film.

[0019] It is preferable that the skin layer 13 and the core layer 11 are in direct contact with each other, which simplifies the manufacturing process of the laminated film 100.

[0020] At least one of the core layer 11 and the skin layer 13 preferably comprises a stretched film layer, more preferably a uniaxially stretched film layer or a biaxially stretched film layer, and even more preferably a biaxially stretched film layer. It is also preferable that both the core layer 11 and the skin layer 13 comprise stretched film layers, more preferably a uniaxially stretched film layer or a biaxially stretched film layer, and even more preferably a biaxially stretched film layer. This allows the laminate film 100 to achieve a good balance of various performance characteristics, such as thermal dimensional stability, film formability, heat resistance, barrier properties, mechanical properties, and rigidity.

[0021] The density of the core layer 11, measured in accordance with JIS K 7112:1999, is preferably 0.942 g / cm 3 More than 0.970g / cm 3 or less, more preferably 0.945 g / cm 3 More than 0.965g / cm 3 or less, more preferably 0.950 g / cm 3 More than 0.960g / cm 3 The interlayer peel strength can be further improved by setting the density of the core layer 11 within the above range. Furthermore, by setting the density of the core layer 11 within the above range, the laminated film 100 can achieve a good balance of various performance characteristics such as thermal dimensional stability, film formability, heat resistance, mechanical properties, and rigidity.

[0022] The density of the skin layer 13, measured in accordance with JIS K 7112:1999, is preferably 0.910 g / cm 3 More than 0.942g / cm 3 less than 0.920 g / cm 3 More than 0.942g / cm 3 less than 0.930 g / cm 3 More than 0.942g / cm 3 By setting the density of the skin layer 13 within the above range, the peel strength between layers can be further improved. Furthermore, by setting the density of the skin layer 13 within the above range, the laminated film 100 can achieve a good balance of various performance characteristics such as thermal dimensional stability, film formability, heat resistance, mechanical properties, and rigidity.

[0023] The density of the core layer 11 minus the density of the skin layer 13 is preferably 0.005 g / cm 3 More preferably, 0.010 g / cm 3 More preferably, 0.013 g / cm 3 That's all. By setting the value obtained by subtracting the density of the skin layer 13 from the density of the core layer 11 to be equal to or greater than the above-mentioned lower limit, the peel strength between the layers can be further improved. Furthermore, by setting the value obtained by subtracting the density of the skin layer 13 from the density of the core layer 11 to be equal to or greater than the above-mentioned lower limit, the laminate film 100 can achieve a good balance among various performances such as thermal dimensional stability, film formability, heat resistance, mechanical properties, and rigidity. The upper limit of the value obtained by subtracting the density of the skin layer 13 from the density of the core layer 11 is not particularly limited, but is, for example, 0.100 g / cm 3 It may be less than 0.050 g / cm 3 It may be less than 0.030 g / cm 3 It may be 0.020 g / cm or less. 3 It may be the following:

[0024] Each layer constituting the laminated film 100 will be described in more detail below.

[0025] (core layer) The core layer 11 contains high-density polyethylene. The core layer 11 may contain other polyethylene polymers in addition to high-density polyethylene. The core layer 11 may further contain, for example, one or more selected from the group consisting of medium-density polyethylene (MDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE), or may further contain linear low-density polyethylene (LLDPE).

[0026] The content of the polyethylene polymer in the core layer 11 relative to the entire core layer 11 is preferably 75% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, even more preferably 85% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, even more preferably 95% by mass or more and 100% by mass or less, and even more preferably 98% by mass or more and 100% by mass or less. By setting the content of the polyethylene polymer in the core layer 11 relative to the entire core layer 11 to be equal to or greater than the above-mentioned lower limit, the laminate film 100 can be well balanced in various performance characteristics such as thermal dimensional stability, film formability, heat resistance, mechanical properties, and rigidity. Furthermore, by setting the content of the polyethylene polymer in the core layer 11 relative to the entire core layer 11 to be equal to or less than the above-mentioned upper limit, the laminate film 100 can be improved in performance balance between processability and continuous productivity.

[0027] The content of high-density polyethylene in core layer 11 relative to the entire core layer 11 is preferably 50% by mass to 100% by mass, more preferably 55% by mass to 99% by mass, even more preferably 60% by mass to 98% by mass, even more preferably 65% ​​by mass to 95% by mass, and even more preferably 70% by mass to 90% by mass. By setting the content of high-density polyethylene in core layer 11 relative to the entire core layer 11 within the above range, the laminate film 100 can achieve a good balance of various performance characteristics such as thermal dimensional stability, film formability, heat resistance, mechanical properties, and rigidity.

[0028] The content (W1) of linear low-density polyethylene in core layer 11 relative to the entire core layer 11 is preferably 0% by mass or more and less than 50% by mass, more preferably 5% by mass or more and 40% by mass or less, even more preferably 10% by mass or more and 30% by mass or less, and still more preferably 15% by mass or more and 25% by mass or less. By setting the content (W1) of linear low-density polyethylene in core layer 11 relative to the entire core layer 11 within the above range, the peel strength between layers can be further improved.

[0029] The melting point of the core layer 11 measured by a differential scanning calorimeter (DSC) is preferably 90° C. or higher and 150° C. or lower, more preferably 110° C. or higher and 145° C. or lower, and even more preferably 120° C. or higher and 140° C. By setting the melting point of the core layer 11 within the above range, the performance balance of the laminate film 100 can be improved, including film-forming properties, thermal dimensional stability, heat resistance, water vapor barrier properties, mechanical properties, rigidity, bag-forming properties, and flowability.

[0030] The thickness of the core layer 11 is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm, and even more preferably 15 μm to 25 μm. By setting the thickness of the core layer 11 within the above range, the performance balance of the laminated film 100 can be improved, including thermal dimensional stability, film-forming properties, water vapor barrier properties, cost, mechanical properties, transparency, bag-forming properties, handleability, appearance, and light weight.

[0031] The ratio of the thickness of core layer 11 to the total thickness of core layer 11 and skin layer 13 is preferably 50% or more and less than 100%, more preferably 60% or more and 99.5% or less, even more preferably 70% or more and 99% or less, and even more preferably 80% or more and 95% or less. By setting the ratio of the thickness of core layer 11 to the total thickness of core layer 11 and skin layer 13 within the above range, the performance balance of laminated film 100 can be improved, including thermal dimensional stability, film-formability, water vapor barrier property, cost, mechanical properties, transparency, bag-formability, handleability, appearance, and light weight.

[0032] The core layer 11 may contain various additives, such as tackifiers, heat stabilizers, weather stabilizers, antioxidants, ultraviolet absorbers, lubricants, slip agents, nucleating agents, antiblocking agents, antistatic agents, antifogging agents, pigments, dyes, and inorganic or organic fillers, as needed, within the scope of the present embodiment.

[0033] (skin layer) The skin layer 13 contains linear low-density polyethylene. The skin layer 13 may contain other polyethylene polymers in addition to linear low-density polyethylene. The skin layer 13 may further contain, for example, one or more selected from the group consisting of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), and low-density polyethylene (LDPE).

[0034] The content of the polyethylene polymer in the skin layer 13 relative to the entire skin layer 13 is preferably 75% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, even more preferably 85% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, even more preferably 95% by mass or more and 100% by mass or less, and even more preferably 98% by mass or more and 100% by mass or less. By setting the content of the polyethylene polymer in the skin layer 13 relative to the entire skin layer 13 to be equal to or greater than the above-mentioned lower limit, the laminate film 100 can be well balanced in various performance characteristics such as thermal dimensional stability, film formability, heat resistance, mechanical properties, and rigidity. Furthermore, by setting the content of the polyethylene polymer in the skin layer 13 relative to the entire skin layer 13 to be equal to or less than the above-mentioned upper limit, the laminate film 100 can be improved in performance balance between processability and continuous productivity.

[0035] The content (W2) of linear low-density polyethylene in the skin layer 13 relative to the entire skin layer 13 is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, even more preferably 70% by mass to 100% by mass, even more preferably 80% by mass to 100% by mass, even more preferably 90% by mass to 100% by mass, even more preferably 95% by mass to 100% by mass, and even more preferably 99% by mass to 100% by mass. By setting the content (W2) of linear low-density polyethylene in the skin layer 13 relative to the entire skin layer 13 within the above range, the peel strength between layers can be further improved.

[0036] The melting point of the skin layer 13 measured by a differential scanning calorimeter (DSC) is preferably 90° C. or higher and 150° C. or lower, more preferably 100° C. or higher and 140° C. or lower, and even more preferably 110° C. or higher and 130° C. By setting the melting point of the skin layer 13 within the above range, the performance balance of the laminated film 100 can be improved, including film-forming properties, thermal dimensional stability, heat resistance, water vapor barrier properties, mechanical properties, rigidity, bag-forming properties, and flowability.

[0037] The thickness of the skin layer 13 is preferably 0.1 μm to 10 μm, more preferably 0.2 μm to 9 μm, and even more preferably 0.3 μm to 8 μm. By setting the thickness of the skin layer 13 within this range, the performance balance of the laminated film 100 can be improved, including thermal dimensional stability, film-forming properties, water vapor barrier properties, cost, mechanical properties, transparency, bag-forming properties, handleability, appearance, and light weight.

[0038] The ratio of the thickness of the skin layer 13 to the total thickness of the core layer 11 and the skin layer 13 is preferably 0.5% to 50%, more preferably 1% to 40%, even more preferably 3% to 30%, and still more preferably 5% to 20%. By setting the ratio of the thickness of the skin layer 13 to the total thickness of the core layer 11 and the skin layer 13 within the above range, the performance balance of the laminated film 100 can be improved, including thermal dimensional stability, film-formability, water vapor barrier properties, cost, mechanical properties, transparency, bag-formability, handleability, appearance, and light weight.

[0039] The developed area ratio Sdr of the surface of the skin layer 13 facing the barrier resin layer 30, as measured in accordance with ISO 25178, is preferably less than 3.10%, more preferably 3.05% or less, and even more preferably 3.00% or less. By setting the developed area ratio Sdr to be less than the above upper limit or equal to or less than the above upper limit, better bonding can be achieved between the skin layer 13 and a layer laminated on the surface of the skin layer 13 facing the barrier resin layer 30 (e.g., the barrier resin layer 30 or the anchor coat layer 50 described below). Therefore, when compared between films having the same configuration except for the core layer 11 and the skin layer 13, a laminate film 100 with improved interlayer peel strength can be obtained. The lower limit of the developed area ratio Sdr is not particularly limited, but may be, for example, 0.01% or more, 0.05% or more, or 0.10% or more.

[0040] If necessary, the skin layer 13 may contain various additives such as tackifiers, heat stabilizers, weather stabilizers, antioxidants, UV absorbers, lubricants, slip agents, nucleating agents, antiblocking agents, antistatic agents, antifogging agents, pigments, dyes, inorganic or organic fillers, etc., within the scope that does not impair the purpose of this embodiment.

[0041] (Barrier resin layer) The barrier resin layer 30 preferably comprises one or more resins selected from the group consisting of a cured product layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound, a polyvinylidene chloride resin layer, a polyurethane resin layer, and a polyvinyl alcohol resin layer, and more preferably comprises one or more resins selected from the group consisting of a cured product layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound, a polyvinylidene chloride resin layer, and a polyurethane resin layer, and from the viewpoint of further improving the performance balance between barrier property and peel strength, it further preferably comprises one or more resins selected from the group consisting of a cured product layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound, and a polyurethane resin layer, and even more preferably comprises a cured product layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound.

[0042] (Cured layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound) The mixture of the present embodiment contains a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound.

[0043] The polycarboxylic acid resin has two or more carboxy groups in the molecule, and examples thereof include polymers of α,β-unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, fumaric acid, crotonic acid, cinnamic acid, 3-hexenoic acid, and 3-hexenedioic acid, or copolymers thereof. Furthermore, copolymers of the above α,β-unsaturated carboxylic acids with esters such as ethyl esters, or olefins such as ethylene, may also be used. From the viewpoint of improving the barrier property, the polycarboxylic acid resin preferably contains one or more selected from the group consisting of acrylic acid polymers, methacrylic acid polymers, itaconic acid polymers, fumaric acid polymers, crotonic acid polymers, cinnamic acid polymers, and copolymers thereof, more preferably contains one or more selected from the group consisting of polyacrylic acid, polymethacrylic acid, and copolymers of acrylic acid and methacrylic acid, and even more preferably contains at least one selected from polyacrylic acid and polymethacrylic acid.

[0044] In this embodiment, polyacrylic acid includes both a homopolymer of acrylic acid and a copolymer of acrylic acid and another monomer. In the case of a copolymer of acrylic acid and another monomer, the polyacrylic acid contains, for example, 90% by mass or more, preferably 95% by mass or more, and more preferably 99% by mass or more of structural units derived from acrylic acid, based on 100% by mass of the polymer. In this embodiment, polymethacrylic acid includes both a homopolymer of methacrylic acid and a copolymer of methacrylic acid and another monomer. In the case of a copolymer of methacrylic acid and another monomer, the polymethacrylic acid contains, for example, 90% by mass or more, preferably 95% by mass or more, and more preferably 99% by mass or more of structural units derived from methacrylic acid in 100% by mass of the polymer.

[0045] The polyamine resin is a compound having two or more amino groups in the main chain, side chain, or terminal, and is preferably a polymer, and examples thereof include aliphatic polyamines such as polyallylamine, polyvinylamine, polyethyleneimine, and poly(trimethyleneimine); polyamides having amino groups in the side chain, such as polylysine and polyarginine; etc. Polyamines in which some of the amino groups have been modified may also be used. From the viewpoint of improving the barrier properties, the polyamine resin preferably contains one or more selected from the group consisting of polyallylamine, polyvinylamine, polyethyleneimine, and poly(trimethyleneimine), and more preferably contains polyethyleneimine.

[0046] In the mixture of this embodiment, the ratio (the number of moles of amino groups contained in the polyamine resin) / (the number of moles of -COO- groups contained in the polycarboxylic acid resin) is preferably 0.40 or more and 0.70 or less, more preferably 0.45 or more and 0.65 or less, and even more preferably 0.50 or more and 0.60 or less, from the viewpoint of improving the barrier property.

[0047] The polyvalent metal compounds contained in the mixture of this embodiment are, for example, metals and metal compounds belonging to groups 2 to 13 of the periodic table. The polyvalent metal compound preferably contains one or more selected from the group consisting of divalent or higher metals such as magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and aluminum (Al), and oxides, hydroxides, halides, carbonates, phosphates, phosphites, hypophosphites, sulfates, and sulfites of these metals; more preferably contains one or more selected from the group consisting of magnesium oxide, calcium oxide, barium oxide, zinc oxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, and zinc hydroxide; even more preferably contains one or more selected from the group consisting of zinc oxide and zinc hydroxide; and even more preferably contains zinc oxide.

[0048] In the mixture of this embodiment, the ratio (number of moles of polyvalent metal compound) / (number of moles of -COO- groups contained in the polycarboxylic acid resin) is preferably 0.20 or more and 0.80 or less, more preferably 0.30 or more and 0.70 or less, even more preferably 0.35 or more and 0.60 or less, and even more preferably 0.40 or more and 0.55 or less, from the viewpoint of improving the barrier property. In the mixture of this embodiment, the ratio (number of moles of polyvalent metal compound) / (number of moles of amino groups contained in the polyamine resin) is preferably 0.50 or more and 1.00 or less, more preferably 0.60 or more and 0.95 or less, and even more preferably 0.70 or more and 0.90 or less, from the viewpoint of improving the barrier property.

[0049] The mixture of this embodiment may contain components other than the polycarboxylic acid resin, polyamine resin, and polyvalent metal compound. Examples of other components include polyphosphate compounds or salts thereof, ammonium carbonate salts, surfactants, crosslinking agents, lubricants, slip agents, antiblocking agents, antistatic agents, antifogging agents, pigments, dyes, inorganic or organic fillers, etc. Examples of crosslinking agents include epoxysilane compounds, carbodiimide compounds, and isocyanate compounds.

[0050] (Polyvinylidene chloride resin layer) The polyvinylidene chloride resin layer is a layer containing polyvinylidene chloride resin as a main component. Here, containing a polyvinylidene chloride resin as a main component means that the polyvinylidene chloride resin layer contains 50% by mass or more of the polyvinylidene chloride resin. From the viewpoint of improving barrier properties, the polyvinylidene chloride resin layer contains preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more of the polyvinylidene chloride resin.

[0051] The polyvinylidene chloride resin of the present embodiment is not particularly limited as long as it contains vinylidene chloride monomers as a constituent unit, and may be polyvinylidene chloride (PVDC) or a copolymer of vinylidene chloride and a monomer copolymerizable with vinylidene chloride.

[0052] The polyvinylidene chloride resin used in the polyvinylidene chloride resin layer can be produced by a conventionally known method, but various commercially available products can also be used. As a commercially available product, the Saran Resin series manufactured by Asahi Kasei Corporation can be preferably used.

[0053] The polyvinylidene chloride resin layer may contain a silane coupling agent.

[0054] (Polyurethane resin layer) The polyurethane-based resin layer is a layer containing a polyurethane-based resin as a main component. Here, containing a polyurethane-based resin as a main component means that the polyurethane-based resin layer contains 50% by mass or more of the polyurethane-based resin. From the viewpoint of improving the barrier property, the polyurethane-based resin layer contains preferably 60% by mass or more of the polyurethane-based resin, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0055] The polyurethane resin can be obtained, for example, by subjecting a polyol having two or more alcoholic hydroxyl groups in one molecule to a polyaddition reaction with a polyisocyanate. The polyol preferably includes one or more polyols selected from the group consisting of polyether polyols, polycarbonate polyols, and polyester polyols, and more preferably includes one or more polyols selected from the group consisting of polycarbonate polyols and polyester polyols. That is, the polyurethane-based resin preferably contains one or more polyurethane-based resins selected from the group consisting of polyether-type polyurethane-based resins, polycarbonate-type polyurethane-based resins, and polyester-type polyurethane-based resins, and more preferably contains one or more polyurethane-based resins selected from the group consisting of polycarbonate-type polyurethane-based resins and polyester-type polyurethane-based resins.

[0056] Examples of polyether polyols include polymers obtained by ring-opening polymerization of one or more cyclic ether compounds such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin, etc., using a compound having an active hydrogen atom as a catalyst, etc. Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.

[0057] The polycarbonate polyol can be obtained by reacting a carbonate compound with a diol. Examples of carbonate compounds include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, and diethylene carbonate. Examples of diols include aliphatic diols which may be substituted with a lower alcohol; alicyclic diols such as cyclohexanediol and hydrogenated xylylene glycol; and aromatic diols such as xylylene glycol. Aliphatic diols are preferred, and aliphatic diols having a carbon chain length of 4 to 9, such as 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, heptanediol, octanediol, and nonanediol, are more preferred.

[0058] The polyester polyol can be obtained by condensing a low molecular weight diol with a dicarboxylic acid. Examples of low molecular weight diols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, and 1,4-butanediol, and examples thereof include ethylene glycol, propylene glycol, and 1,4-butanediol. Examples of dicarboxylic acids include aliphatic dibasic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and brassylic acid; and aromatic dibasic acids such as isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid. Among these, aliphatic dibasic acids are preferred, including dibasic acids with a methylene chain length of 4 to 8, such as adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

[0059] Examples of polyisocyanates include chain aliphatic diisocyanates such as tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate; aliphatic diisocyanates having a cyclic structure such as isophorone diisocyanate, hydrogenated xylylene diisocyanate, and dicyclohexylmethane 4,4'-diisocyanate; aliphatic diisocyanates having an aromatic ring such as xylylene diisocyanate and tetramethylxylylene diisocyanate; aromatic diisocyanates such as tolylene diisocyanate and diphenylmethane diisocyanate; and modified products of these diisocyanates (carbodiimide-, uretdione-, and uretoimine-containing modified products, etc.), with aliphatic diisocyanates and aromatic diisocyanates being preferred.

[0060] Examples of reaction solvents for the polyaddition reaction include acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, ethyl acetate, toluene, and xylene. In the polyaddition reaction, a chain extender or a reaction terminator may be used in combination, if necessary. The use of a chain extender can increase the molecular weight. Examples of chain extenders include polyols and polyamines, and examples of reaction terminators include monoalcohols and monoamines. The polyurethane resin is preferably used as an emulsion, and the emulsion may contain a dispersant such as a surfactant, if necessary. That is, the polyurethane resin is preferably a water-dispersible polyurethane resin.

[0061] The water-dispersible polyurethane resin is preferably a self-emulsifying polyurethane resin in which a hydrophilic group such as a carboxylate (-COONa, etc.) or a sulfonate (-SO3Na, etc.) is introduced into the main chain or side chain of the polyurethane resin. As the polyurethane resin, commercially available water-dispersible polyurethane resins can also be used.

[0062] Examples of commercially available water-dispersible polyurethane resins include those manufactured by Mitsui Chemicals, Inc., which are available under the trade names of TAKELAC WPB-341, TAKELAC WS4000, TAKELAC WS5100, TAKELAC WS4022, TAKELAC WBP341A, and TAKELAC W6010.

[0063] From the viewpoint of improving the barrier property, the polyurethane-based resin layer preferably further contains an inorganic layered compound. Examples of inorganic layered compounds include smectite-based layered clay minerals such as montmorillonite, bentonite, saponite, hectorite, paidellite, stevensite, and nontronite; mica such as vermiculite, halloysite, and tetrasilicic mica; and fluorine compounds thereof. The mass ratio (A / B) of the content (A) of the polyurethane resin in the polyurethane resin layer to the content (B) of the inorganic layered compound is preferably 50 / 50 or more and 99 / 1 or less, more preferably 70 / 30 or more and 98 / 2 or less, and even more preferably 90 / 10 or more and 97 / 3 or less, from the viewpoint of improving the barrier property.

[0064] (Polyvinyl alcohol resin layer) The polyvinyl alcohol-based resin layer is a layer containing a polyvinyl alcohol-based resin. The polyvinyl alcohol-based resin layer contains polyvinyl alcohol-based resin in an amount of preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 30% by mass or more, even more preferably 50% by mass or more, even more preferably 70% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0065] The polyvinyl alcohol resin of this embodiment is a polymer obtained by saponifying a polyvinyl acetate polymer, which has a hydroxyl group in the molecule and is preferably soluble in water. The polyvinyl acetate polymer used as the raw material may be a homopolymer of vinyl acetate, or may be copolymerized with, for example, up to 30 mol% of another copolymerizable monomer, such as an α-olefin such as ethylene, propylene, or 1-butene. When the copolymerization monomer is 30 mol% or less, the barrier properties can be improved.

[0066] From the viewpoint of improving the barrier property, the polyvinyl alcohol-based resin layer preferably further contains one or more compounds selected from the group consisting of inorganic layered compounds and organosilicon compounds.

[0067] Examples of inorganic layered compounds include smectite-based layered clay minerals such as montmorillonite, bentonite, saponite, hectorite, paidellite, stevensite, and nontronite; mica such as vermiculite, halloysite, and tetrasilicic mica; and fluorine compounds thereof. The mass ratio (A / B) of the content (A) of the polyvinyl alcohol-based resin in the polyvinyl alcohol-based resin layer to the content (B) of the inorganic layered compound is preferably 50 / 50 or more and 99 / 1 or less, more preferably 70 / 30 or more and 98 / 2 or less, and even more preferably 90 / 10 or more and 97 / 3 or less, from the viewpoint of improving the barrier property.

[0068] The organosilicon compound may be, for example, a compound represented by the formula (1): Si(OR 1 ) 4 and its hydrolysis products. 1is CH3, C2H5, or C2H4OCH3. Formula (1): Si(OR 1 Among the silicon alkoxide compounds represented by formula (4), tetraethoxysilane is preferred from the viewpoint of its relative stability in aqueous solvents. In this embodiment, the hydrolysis product of the silicon alkoxide compound also includes a partial hydrolysis product of the silicon alkoxide compound. Furthermore, when the polyvinyl alcohol-based resin layer contains a silicon alkoxide compound, the content of the polyvinyl alcohol-based resin in the polyvinyl alcohol-based resin layer is preferably 10% by mass or more and 50% by mass or less, and more preferably 15% by mass or more and 40% by mass or less, when the entire polyvinyl alcohol-based resin layer is taken as 100% by mass, from the viewpoint of improving barrier properties. Also, Si(OR 1 )4 is converted to SiO2, the Si(OR 1 From the viewpoint of improving the barrier property, the content of SiO2 derived from 4 is preferably 40% by mass or more and 85% by mass or less, and more preferably 50% by mass or more and 85% by mass or less, when the entire polyvinyl alcohol-based resin layer is taken as 100% by mass.

[0069] The thickness of the barrier resin layer 30 is preferably 0.01 μm or more and 5.0 μm or less, more preferably 0.05 μm or more and 2.0 μm or less, and even more preferably 0.10 μm or more and 1.0 μm or less. By setting the thickness of the barrier resin layer 30 within the above range, the barrier properties of the laminated film 100 can be improved.

[0070] From the viewpoint of simplifying the manufacturing process of the laminated film 100, it is preferable that the skin layer 13 and the barrier resin layer 30 are in direct contact with each other as shown in FIG.

[0071] (Anchor coat layer) From the viewpoint of achieving good bonding between the skin layer 13 and the barrier resin layer 30, it is preferable that the barrier resin layer 30 is provided on the skin layer 13 via an anchor coat layer 50, as shown in FIG. 2. The anchor coating layer 50 contains, for example, an anchor coating agent. The anchor coating agent may include one or more selected from the group consisting of an isocyanate-based anchor coating agent, a urethane-based anchor coating agent, polyethyleneimine, an epoxy resin, a silane coupling agent, polyvinyl acetate, and an ethylene-vinyl acetate copolymer, preferably one or more selected from the group consisting of an isocyanate-based anchor coating agent and a urethane-based anchor coating agent, and more preferably an isocyanate-based anchor coating agent. This allows good bonding between the skin layer 13 and the barrier resin layer 30 to be maintained even under high humidity conditions. Examples of isocyanate-based anchor coating agents include aqueous isocyanates. As the anchor coating agent, commercially available agents can be used as appropriate.

[0072] The content of the anchor coating agent in the anchor coating layer 50 relative to the entire anchor coating layer 50 is preferably 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and even more preferably 95% by mass or more and 100% by mass or less. By setting the content of the anchor coating agent in the anchor coating layer 50 relative to the entire anchor coating layer 50 within the above range, good bonding between the skin layer 13 and the barrier resin layer 30 can be achieved.

[0073] The coating amount of the anchor coat layer 50 is preferably 0.01 g / m 2 More than 3g / m 2 or less, more preferably 0.05 g / m 2 More than 1g / m 2 or less, more preferably 0.05 g / m 2 More than 0.5g / m 2 By setting the coating amount of the anchor coat layer 50 within the above range, the bonding between the skin layer 13 and the barrier resin layer 30 can be made good.

[0074] (Physical properties of laminated film) The 180° peel strength between the laminate film 100 and the LLDPE film is preferably greater than 2.2 N / 15 mm, more preferably 2.3 N / 15 mm or more, and even more preferably 2.4 N / 15 mm or more. By ensuring that the 180° peel strength between the laminate film 100 and the LLDPE film is equal to or greater than the above lower limit, when the laminate film 100 is laminated with another film to form a multilayer film, a multilayer film with improved peel strength between the laminate film 100 and the other film can be obtained. The upper limit of the 180° peel strength between the laminated film 100 and the LLDPE film is not particularly limited, but may be, for example, 10.0 N / 15 mm or less, 7.5 N / 15 mm or less, or 5.0 N / 15 mm or less.

[0075] The 90° peel strength between the laminate film 100 and the LLDPE film is preferably greater than 1.0 N / 15 mm, more preferably greater than 1.1 N / 15 mm, and even more preferably greater than 1.5 N / 15 mm. By ensuring that the 90° peel strength between the laminate film 100 and the LLDPE film is equal to or greater than the above lower limit, when the laminate film 100 is laminated with another film to form a multilayer film, a multilayer film with improved peel strength between the laminate film 100 and the other film can be obtained. The upper limit of the 90° peel strength between the laminated film 100 and the LLDPE film is not particularly limited, but may be, for example, 10.0 N / 15 mm or less, 7.5 N / 15 mm or less, or 5.0 N / 15 mm or less.

[0076] In this embodiment, the 180° peel strength and 90° peel strength between the laminated film 100 and the LLDPE film are measured by the following method. An adhesive is applied to one side of a 50 μm-thick LLDPE film. Next, the laminate film 100 and the LLDPE film are laminated together so that the surface of the laminate film 100 facing the barrier resin layer 30 comes into contact with the adhesive-coated surface of the LLDPE film. Next, the 180° peel strength and 90° peel strength between the laminate film 100 and the LLDPE film are measured at 25°C and a pulling rate of 300 mm / min.

[0077] The 180° peel strength between the laminate film 100 and the LLDPE film after boiling treatment is preferably greater than 0.8 N / 15 mm, more preferably 1.0 N / 15 mm or more, and even more preferably 1.2 N / 15 mm or more. By ensuring that the 180° peel strength between the laminate film 100 and the LLDPE film after boiling treatment is equal to or greater than the above lower limit, when the laminate film 100 is laminated with another film to form a multilayer film, a multilayer film with improved peel strength between the laminate film 100 and the other film can be obtained. The upper limit of the 180° peel strength between the laminated film 100 and the LLDPE film after the boiling treatment is not particularly limited, but may be, for example, 10.0 N / 15 mm or less, 7.5 N / 15 mm or less, or 5.0 N / 15 mm or less.

[0078] The 90° peel strength between the laminate film 100 and the LLDPE film after boiling treatment is preferably greater than 0.4 N / 15 mm, more preferably greater than 0.5 N / 15 mm, and even more preferably greater than 0.6 N / 15 mm. By ensuring that the 90° peel strength between the laminate film 100 and the LLDPE film after boiling treatment is equal to or greater than the above-mentioned lower limit, when the laminate film 100 is laminated with another film to form a multilayer film, a multilayer film with improved peel strength between the laminate film 100 and the other film can be obtained. The upper limit of the 90° peel strength between the laminated film 100 and the LLDPE film after boiling treatment is not particularly limited, but may be, for example, 10.0 N / 15 mm or less, 7.5 N / 15 mm or less, or 5.0 N / 15 mm or less.

[0079] In this embodiment, the 180° peel strength and 90° peel strength between the laminated film 100 and the LLDPE film after boiling treatment are measured by the following method. An adhesive is applied to one side of a 50 μm-thick LLDPE film. The laminated film 100 and the LLDPE film are then laminated together so that the surface of the laminated film 100 facing the barrier resin layer 30 comes into contact with the adhesive-coated surface of the LLDPE film, yielding a multilayer film. The resulting multilayer film is then boiled at 85°C for 30 minutes. The 180° peel strength and 90° peel strength of the multilayer film between the laminated film 100 and the LLDPE film are measured at 25°C and a pulling speed of 300 mm / min using the boiled multilayer film.

[0080] (Laminated film manufacturing method) The laminated film 100 can be obtained, for example, by the following method. First, a resin composition containing high density polyethylene and a resin composition containing linear low density polyethylene are co-extruded and then stretched to obtain a laminate of the core layer 11 and the skin layer 13 . The molding apparatus and molding conditions are not particularly limited, and conventionally known molding apparatus and molding conditions can be used. Examples of molding apparatus that can be used include a T-die extruder, a multilayer T-die extruder, an inflation molding machine, and a multilayer inflation molding machine. The conditions for the stretching treatment can be those used for producing known polyethylene films. For example, in the sequential biaxial stretching method, the MD stretching temperature is preferably set to a range of 100°C to 145°C, more preferably 110°C to 140°C, and even more preferably 120°C to 135°C, and the TD stretching temperature is preferably set to a range of 110°C to 190°C, more preferably 120°C to 170°C. The MD stretch ratio is set to a range of 4.5 to 7 times, and the TD stretch ratio is set to a range of 9 to 11 times. Here, the stretching temperature must be set at three stages: preheating temperature (temperature at which the raw film is heated before stretching), stretching temperature (temperature at which stretching is performed), and heat setting temperature (temperature at which heat setting (annealing) is performed after stretching). The temperatures from preheating to heat setting can be within the above range. In other words, the temperatures from the preheating stage onward can be set to approximately the same as those for stretching and heat setting.

[0081] Next, if necessary, an anchor coat layer 50 is formed on the skin layer 13. The method for forming the anchor coat layer 50 is not particularly limited, and examples thereof include a method in which an anchor coat agent is applied to the skin layer 13 and then dried. The method for applying the anchor coat agent is not particularly limited, and examples thereof include a method in which the anchor coat agent is applied using a known coater such as an air knife coater, kiss roll coater, metaling bar coater, gravure roll coater, reverse roll coater, dip coater, or die coater.

[0082] Next, the barrier resin layer 30 is formed on the skin layer 13 or the anchor coat layer 50. There are no particular limitations on the method for forming the barrier resin layer 30, but for example, it can be formed by applying a composition for the barrier resin layer onto the skin layer 13 or the anchor coat layer 50 and then heating it.

[0083] (Laminated film applications / packaging materials / packaging bodies) Specifically, the laminated film 100 of this embodiment can be suitably used as a packaging film. The laminated film 100 of this embodiment can be suitably used as a packaging material. That is, the packaging material of this embodiment includes the laminated film 100. When used as a packaging material, the laminate film 100 of this embodiment may be used alone, or other layers may be laminated on at least one surface of the laminate film 100 to form the packaging material. The other layers preferably include one or more selected from the group consisting of a coating layer, a substrate layer, and an inorganic layer, and more preferably include a coating layer. From the viewpoint of ease of recycling, the other layers are preferably formed from a polyethylene-based resin. When a packaging material including the laminate film 100 of this embodiment is used, it is preferable that at least one outermost layer of the packaging material further includes a heat seal layer, and it is more preferable that the packaging material includes a core layer 11, a skin layer 13, a barrier resin layer 30, and a heat seal layer in this order. From the viewpoint of ease of recycling, it is preferable that the heat seal layer contains polyethylene. Furthermore, the packaging material of this embodiment can be suitably used for a package. The package is used, for example, for packaging an item. Specifically, the package of this embodiment includes the packaging material of this embodiment and an item inside the packaging material. In particular, the packaging of this embodiment can be suitably used as a food package, and is used for packaging food. Specifically, the packaging of this embodiment includes the packaging material of this embodiment and food inside the packaging material. The food to be packaged in the food packaging is not particularly limited, but examples thereof include baked goods, rice crackers, snacks, rice seasonings, grain powders, and the like. Depending on the application, only a portion of the package may be made of the packaging material of this embodiment, or substantially the entire package may be made of the packaging material of this embodiment.

[0084] The content of the ethylene polymer in the packaging material of this embodiment, when the entire packaging material is taken as 100% by mass, is preferably 50% by mass or more and less than 100% by mass, more preferably 70% by mass or more and less than 100% by mass, even more preferably 80% by mass or more and 99.9% by mass or less, even more preferably 90% by mass or more and 99.9% by mass or less, even more preferably 95% by mass or more and 99.5% by mass or less, and even more preferably 99.0% by mass or more and 99.5% by mass or less. This means that the packaging material is composed of almost a single material (monomaterial), which reduces the work of separating the materials that make up the packaging material and improves the recyclability of the packaging material.

[0085] The polyethylene content in the packaging material of this embodiment, when the entire packaging material is taken as 100% by mass, is preferably 50% by mass or more and less than 100% by mass, more preferably 70% by mass or more and less than 100% by mass, even more preferably 80% by mass or more and less than 99.9% by mass, even more preferably 90% by mass or more and less than 99.9% by mass, even more preferably 95% by mass or more and less than 99.8% by mass, and even more preferably 99.0% by mass or more and less than 99.8% by mass. This means that the packaging material is composed of almost a single material (monomaterial), which reduces the work of separating the materials that make up the packaging material and improves the recyclability of the packaging material.

[0086] There are no particular limitations on the method for producing a package from the laminate film 100 or packaging material, and any method known in the field of packaging materials / packages, such as heat sealing or fusing, can be used as appropriate.

[0087] The laminated film 100 according to this embodiment is preferably used for packaging that requires good barrier properties. The form of the packaging can be, for example, a two-sided bag or a standing pouch (pouch packaging).

[0088] When a package (such as a food packaging bag) is constructed using the laminate film 100 of this embodiment or a packaging material, it is preferable that the corona-treated surface is the inner surface and the non-corona-treated surface is the outer surface. Furthermore, as described above, when another layer is laminated on the laminate film 100, it is preferable that the layer is laminated on the corona-treated surface. In other words, when a laminate using the laminate film 100 of this embodiment is used for a package (such as a food packaging bag), it is preferable that the laminate film 100 of this embodiment is the outermost layer of the package.

[0089] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0090] The present embodiment will be described in detail below with reference to examples and comparative examples, but the present embodiment is not limited to the descriptions of these examples.

[0091] 1.Raw materials The raw materials used to prepare the core layer and the skin layer are shown below. LLDPE1: Linear low-density polyethylene (density: 0.937 g / cm 3 , MFR: 1.8g / 10min, Melting point: 127℃) LLDPE2: Linear low-density polyethylene (density: 0.928 g / cm 3 , MFR: 1.9g / 10min, Melting point: 126℃) HDPE: High density polyethylene (density: 0.958 g / cm 3 , MFR: 1.0g / 10min, Melting point: 133℃) The density was measured in accordance with JIS K 7112:1999. The MFR was measured in accordance with JIS K 7210:1999 under conditions of 190°C and a load of 2160g. The melting point was measured using a differential scanning calorimeter (DSC). Specifically, using a differential scanning calorimeter (product name: Q200DSC manufactured by TA Instruments), a first differential scanning calorimeter measurement was performed under a nitrogen gas flow, consisting of a process of increasing the temperature from -50°C to 230°C at a heating rate of 10°C / min and a process of decreasing the temperature from 230°C to -50°C at a heating rate of 10°C / min, and a second differential scanning calorimeter measurement was performed consecutively, consisting of a process of increasing the temperature from -50°C to 230°C at a heating rate of 10°C / min. The peak temperature of the maximum endothermic peak in the DSC curve in the second measurement was taken as the melting point (°C).

[0092] 2. Preparation of Core and Skin Layers Skin layer 1, core layer, and skin layer 2 were extrusion-molded with the compositions and layer structures shown in Table 1. Stretching treatment was then carried out under the conditions shown in Table 1. Next, corona treatment was carried out on the surface of skin layer 1 to produce HDBOPEs 1 to 3. Each film had a thickness of 25 μm. The extrusion molding conditions and stretching treatment conditions are as follows. Extrusion molding machine: 60 mmφ multi-layer T-die extrusion molding machine (screw: L / D=27, manufactured by Screw Seiki Co., Ltd.) Extrusion temperature setting: 230-250°C, Processing speed: 15m / min (winding speed) In Table 1, the notation "A / B / C" for the stretching temperature means "preheating temperature (temperature at which the raw film is heated before stretching) / stretching temperature (temperature during stretching) / heat setting temperature (temperature during heat setting (annealing) after stretching)." The relaxation ratio refers to the maximum stretching width in the device settings divided by the tenter exit width.

[0093] 3. Skin layer evaluation (surface roughness) The surface roughness of the corona-treated surface of skin layer 1 (the surface of skin layer 1 on the barrier resin layer side) was measured using a laser microscope (manufactured by Olympus Corporation, product name: OLS5000) in accordance with ISO 25178. The measurement conditions are shown below. Objective lens: 50x Digital zoom: 1x Height range: 5 μm up and down Brightness: Automatic setting Next, the measured image was analyzed under the following conditions to calculate the developed area ratio Sdr. Evaluation area: All areas De-skew: Automatic Filter conditions: Shape removal settings, multidimensional surfaces, 2D Roughness parameters: surface area The number of samples was 5, and the average value of the obtained measurements was used. The results are shown in Table 1.

[0094] [Table 1]

[0095] As shown in Table 1, it was confirmed that the deployment area ratio Sdr of HDBOPE1 was smaller than the deployment area ratios Sdr of HDBOPE2 and HDBOPE3.

[0096] 4. Preparation of Laminated Film In each example and comparative example, a barrier resin layer was formed on the corona-treated surface of the skin layer 1, or on the surface of the anchor coat layer if an anchor coat layer was formed, to produce a laminate film. In any of the examples and comparative examples, no curling or film cracking of the barrier resin layer was observed. The methods for forming the anchor coat layer and the barrier resin layer are described below.

[0097] (1) Method for forming anchor coat layer A solvent-based polyisocyanate (manufactured by Mitsui Chemicals, Inc., product name: Takenate D-110N) was coated onto the skin layer 1 using a Mayer bar, and the coating was dried at 100°C for 15 seconds to obtain a coating weight of 0.1 g / m. 2 An anchor coat layer of the above was formed. (2) Method for forming a barrier resin layer (Example 1 and Comparative Examples 1 and 2: Method A) Polyacrylic acid (manufactured by Toagosei Co., Ltd., product name: AC-10H, weight average molecular weight: 800,000), 10 mass% aqueous ammonia (manufactured by Wako Pure Chemical Industries, Ltd.), and purified water were mixed so that the ammonia concentration was 250 equivalent % relative to the carboxyl groups of the polyacrylic acid, thereby obtaining an aqueous solution of ammonium polyacrylate with a concentration of 7.29 mass %. Next, zinc oxide (Kanto Chemical Co., Ltd.) and ammonium carbonate were added to the resulting aqueous ammonium polyacrylate solution, and the mixture was stirred to obtain a mixed solution (1-A). The amount of zinc oxide added was such that the ratio (moles of zinc oxide in coating material A) / (moles of -COO- groups in polyacrylic acid in coating material A) was 0.475. The amount of ammonium carbonate added was such that the ratio (moles of ammonium carbonate in coating material A) / (moles of zinc oxide in coating material A) was 1.5. Next, polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., trade name: SP-200, number average molecular weight: 10,000) was added to the purified water to obtain a 10% by mass aqueous polyethyleneimine solution. Next, purified water was added to low-polymerized ammonium polyphosphate (manufactured by Amada Co., Ltd., product number: water-soluble ammonium polyphosphate flame retardant NNA20, P2O5 content 59%) to obtain a 25% by mass aqueous solution of low-polymerized ammonium polyphosphate. Next, the mixed solution (1-A), the polyethyleneimine aqueous solution, and the low-polymerized ammonium polyphosphate aqueous solution as a phosphorus introduction source were mixed in a ratio such that (the number of moles of amino groups contained in polyethyleneimine in coating material A) / (the number of moles of -COO- groups contained in polyacrylic acid in coating material A) was 0.55, and (the number of moles of P contained in polyphosphate compound or its salt in coating material A) / (the number of moles of -COO- groups contained in polyacrylic acid in coating material A) was 0.025, to obtain mixed solution (2-A). Purified water was then added to the mixture (2-A) so that the solids concentration was 1.5% by mass, and the mixture was stirred until a uniform solution was obtained. A surfactant (polyoxyethylene lauryl ether, manufactured by Kao Corporation, trade name: Emulgen 120) was then added to the mixture (2-A) so that the solids concentration was 0.3% by mass, thereby preparing coating material A. Coating material A was applied to the skin layer 1 or the anchor coat layer with a Mayer bar and heated in an oven at 70°C for 60 seconds to form a 300 nm thick barrier resin layer.

[0098] (Example 2 and Comparative Example 3: Method B) 77 g of water, 13.4 g of isopropyl alcohol, and 1.8 g of 0.5 N hydrochloric acid were mixed to obtain a solution with a pH of 2.2. 35 g of tetraethoxysilane and 1.8 g of a silane coupling agent (manufactured by Shin-Etsu Silicones Co., Ltd., trade name: KBM-403) were mixed with this solution to obtain solution (1-B). Next, 5.9 g of polyvinyl alcohol (manufactured by Nippon Vinegar Vipbal Co., Ltd., trade name: PVA-VI), 129.6 g of water, and 6.8 g of isopropyl alcohol were mixed to obtain a solution (2-B). Solution (1-B) and solution (2-B) were mixed at a weight ratio of 6.5:3.5 to prepare coating material B. Coating material B was coated onto skin layer 1 or the anchor coat layer with a Mayer bar and heated in an oven at 70°C for 60 seconds to form a 300 nm thick barrier resin layer.

[0099] (Example 3 and Comparative Example 4: Method C) Polyvinylidene chloride resin (manufactured by Asahi Kasei Corporation, product name: F216) was dissolved in a mixed organic solvent of toluene and methyl ethyl ketone (weight ratio: toluene / methyl ethyl ketone = 1 / 2) to prepare a polyvinylidene chloride resin solution (solid content 5% by mass), which gave coating material C. Coating material C was coated onto skin layer 1 or the anchor coat layer with a Mayer bar and heated in an oven at 70°C for 60 seconds to form a 500 nm thick barrier resin layer.

[0100] (Example 4 and Comparative Examples 5 and 6: Method D) A water-dispersible polyurethane resin (manufactured by Mitsui Chemicals, Inc., product name: Takelac WPB-341) was diluted with a solvent (weight ratio: water / isopropyl alcohol = 9 / 1) to prepare a solution with a solids content of 3.5 mass%, yielding Coating Material D. Coating Material D was coated onto the skin layer 1 or anchor coat layer with a Mayer bar and heated in an oven at 70°C for 60 seconds to form a 500 nm thick barrier resin layer.

[0101] 5. Fabrication of Multilayer Films An adhesive (12 parts by mass of a polyester adhesive (Mitsui Chemicals, Inc., product name: Takelac A-310), 1 part by mass of an isocyanate curing agent (Mitsui Chemicals, Inc., product name: Takenate A-3), and 7 parts by mass of ethyl acetate) was applied to one side of a 50 μm-thick unstretched LLDPE film (manufactured by Mitsui Chemicals Tohcello, Inc., product name: TUXMCS). After drying, the laminate film and the LLDPE film were laminated (dry laminated) so that the surface of the barrier resin layer of the laminate film was in contact with the adhesive-coated surface of the LLDPE film, thereby obtaining a multilayer film.

[0102] 6. Evaluation of multilayer films (1) Peel strength Using the resulting multilayer film, the 180° peel strength and 90° peel strength between the laminated film and the LLDPE film were measured at 25°C and a pulling rate of 300 mm / min.

[0103] (2) Moisture permeability The resulting multilayer film was folded over so that the LLDPE film was on the inside, and the two sides were heat-sealed to form a bag. Calcium chloride was then placed inside the resulting bag. The other side of the bag was then heat-sealed to form a bag with a surface area of ​​0.01 m. 2 The bags were then stored at 40°C and 90% RH for 300 hours. The weight of the calcium chloride was measured before and after storage, and the moisture permeability was calculated from the difference.

[0104] (3) Oxygen permeability The oxygen permeability (mL / (m 2·day·MPa) was measured in accordance with JIS K7126:2006 under conditions of 20°C and 90% RH.

[0105] (4) Evaluation of boiling treatment and multilayer film after boiling treatment The obtained multilayer film was subjected to a boiling treatment for 30 minutes at 85° C. The multilayer film after the boiling treatment was used to perform evaluations in the same manner as in (1) to (3). In any of the Examples and Comparative Examples, no delamination between the laminated film and the LLDPE film was observed after the boiling treatment.

[0106] The evaluation results of each of the examples and comparative examples are shown in Tables 2 to 5.

[0107] [Table 2]

[0108] [Table 3]

[0109] [Table 4]

[0110] [Table 5]

[0111] When the barrier resin layer was formed by methods A to C, a multilayer film having improved peel strength in each example compared with that in each comparative example was obtained when compared between films having the same configuration except for the core layer and skin layer. Furthermore, when the barrier resin layer was formed by any of methods A to D, a multilayer film having improved peel strength after boiling treatment in each example compared with that in each comparative example was obtained when compared between films having the same configuration except for the core layer and skin layer. [Explanation of symbols]

[0112] 11 Core layer 13 Skin layer 30 Barrier resin layer 50 Anchor coat layer 100 Laminated Film

Claims

1. a core layer comprising high density polyethylene; a skin layer comprising linear low density polyethylene; a barrier resin layer; In this order, The content of linear low density polyethylene in the core layer relative to the entire core layer is W １ year, The content of linear low density polyethylene in the skin layer relative to the entire skin layer is W ２ When W ２ >W １ Laminated film that satisfies the above requirements.

2. The density of the skin layer is 0.910 g / cm ３ 0.942g / cm or more ３ The laminate film according to claim 1, wherein the thickness is less than 1 / 2 mm.

3. The density of the core layer minus the density of the skin layer is 0.005 g / cm ３ The laminated film according to claim 1 or 2, wherein the above-mentioned

4. The density of the core layer is 0.942 g / cm ３ The laminated film according to any one of claims 1 to 3.

5. The content of linear low density polyethylene in the skin layer relative to the entire skin layer (W ２ 5. The laminate film according to claim 1, wherein the content of the copolymer is 50% by mass or more and 100% by mass or less.

6. The content of linear low density polyethylene in the core layer relative to the entire core layer (W １ 6. The laminate film according to claim 1, wherein the content of the copolymer is 0% by mass or more and less than 50% by mass.

7. The laminated film according to any one of claims 1 to 6, wherein the thickness of the skin layer is 0.1 µm or more and 10 µm or less.

8. The laminated film according to any one of claims 1 to 7, wherein the ratio of the thickness of the skin layer to the total thickness of the core layer and the skin layer is 0.5% or more and 50% or less.

9. 9. The laminated film according to claim 1, wherein the content of the high-density polyethylene in the core layer is 50% by mass or more and 100% by mass or less relative to the entire core layer.

10. The laminated film according to any one of claims 1 to 9, wherein the thickness of the core layer is 5 µm or more and 100 µm or less.

11. The laminated film according to any one of claims 1 to 10, wherein the ratio of the thickness of the core layer to the total thickness of the core layer and the skin layer is 50% or more and less than 100%.

12. The laminate film according to any one of claims 1 to 11, wherein the barrier resin layer comprises one or more resin layers selected from the group consisting of a cured product layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound, a polyvinylidene chloride resin layer, a polyurethane resin layer, and a polyvinyl alcohol resin layer.

13. The laminated film according to any one of claims 1 to 12, wherein at least one of the core layer and the skin layer includes a stretched film layer.

14. The laminated film according to any one of claims 1 to 13, wherein the skin layer and the core layer are in direct contact with each other.

15. The laminated film according to any one of claims 1 to 14, wherein the skin layer and the barrier resin layer are in direct contact with each other.

16. The laminated film according to any one of claims 1 to 14, wherein the barrier resin layer is provided on the skin layer via an anchor coat layer.

17. 17. The laminate film according to claim 1, wherein the developed area ratio Sdr of the surface of the skin layer on the barrier resin layer side, measured in accordance with ISO 25178, is less than 3.10%.

18. 18. The laminate film according to any one of claims 1 to 17, wherein the 180° peel strength between the laminate film and the LLDPE film, measured by the following method, is greater than 2.2 N / 15 mm. (method) An adhesive is applied to one side of a 50 μm-thick LLDPE film. The laminated film and the LLDPE film are then laminated together so that the surface of the laminated film facing the barrier resin layer is in contact with the adhesive-coated surface of the LLDPE film. The peel strength between the laminated film and the LLDPE film is measured at 25° C. and a tensile speed of 300 mm / min.

19. The laminate film according to any one of claims 1 to 18, wherein the 180° peel strength between the laminate film and the LLDPE film, measured by the following method, is greater than 0.8 N / 15 mm. (method) An adhesive is applied to one side of a 50 μm-thick LLDPE film. The laminated film and the LLDPE film are then laminated together so that the barrier resin layer side of the laminated film is in contact with the adhesive-coated side of the LLDPE film, yielding a multilayer film. The resulting multilayer film is then boiled at 85°C for 30 minutes. The peel strength between the laminated film and the LLDPE film after the boiling treatment is measured at 25°C and a tensile speed of 300 mm / min.

20. The laminated film according to any one of claims 1 to 19, which is a packaging film.

21. A packaging material comprising the laminate film according to any one of claims 1 to 20.

22. 22. The packaging material of claim 21, further comprising a heat seal layer on at least one outermost layer.

23. The packaging material according to claim 22, comprising the core layer, the skin layer, the barrier resin layer, and the heat seal layer in this order.

24. 24. The packaging material of claim 22 or 23, wherein the heat seal layer comprises polyethylene.

25. The packaging material according to any one of claims 21 to 24, further comprising a coating layer on at least one surface of the laminated film.

26. The packaging material according to any one of claims 21 to 25, and an item within the packaging material.

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