Gas barrier laminate, packaging container, and packaging product

Abstract

This gas barrier laminate is provided with: a gas barrier film having a gas barrier layer on at least one surface side of a substrate comprising a first polypropylene film; and at least one second polypropylene film laminated on the gas barrier film. The gas barrier layer is obtained using a gas barrier layer-forming composition containing a resin and a first silicon compound. The first silicon compound is at least one of a siloxy compound represented by formula (1) and a hydrolysis product thereof, and the chlorine amount measured by combustion ion chromatography based on the total amount of the gas barrier laminate is more than 0.0008 mass% but 0.0080 mass% or less. Si (OR1) 4 (1) (In formula (1), OR1 represents a hydrolyzable group).

Description

Technical Field

[0001] The present disclosure relates to a gas barrier laminate, a packaging container, and a packaging product. Background Art

[0002] In recent years, the world has recognized that environmental and waste issues, such as marine pollution caused by plastic waste, are intensifying worldwide and becoming a global threat. In May 2019, Japan's Ministry of the Environment formulated the "Plastic Resource Recycling Strategy" to comprehensively promote the recycling of plastic resources. This strategy explicitly mandates the effective utilization of used plastics through 100% reuse and recycling by 2035.

[0003] To address this social situation, demand for packaging materials suitable for recycling is increasing. Packaging materials composed of multiple layers of resins, such as nylon, polyethylene terephthalate, and polyolefins, present difficulties in separating and recycling each layer. Consequently, the shift toward single-material packaging (single-source material) has recently accelerated. For example, packaging materials with a base layer and a sealant layer made of polypropylene film are already being used.

[0004] When such packaging materials are recycled, for example, the recovered packaging materials are pulverized, the pulverized materials are fed into an extruder to melt the packaging materials, and the melted materials are pelletized and reused.

[0005] However, polypropylene resin is easily thermally oxidized and sometimes undergoes oxidative decomposition when melted at high temperatures. This carbonization causes the polypropylene resin to become brown or black. This colored polypropylene resin is difficult to recycle.

[0006] Therefore, a proposal has been proposed to suppress coloration during recycling and thereby improve recyclability by using the following laminate: the laminate comprises two or more resin films containing polyolefin, and when the individual resin films are peeled off from the laminate and both surfaces of all the resin films are analyzed using a fluorescent X-ray analyzer, the value obtained by dividing the sum of the fluorescent X-ray intensities of chlorine detected from all surfaces of all the resin films by the thickness of the laminate (sum of the fluorescent X-ray intensities of chlorine / thickness of the laminate) is 0.015 kcps / μm or less.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: International Publication No. 2022 / 181549 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] However, the laminate described in Patent Document 1 has room for improvement in terms of improving recyclability.

[0012] Furthermore, the above-mentioned laminates are sometimes used to manufacture packaging containers that require high-temperature sterilization at temperatures above 121°C (hereinafter also referred to as "high retort"). Therefore, even when the laminate described in Patent Document 1 is melted to obtain a non-colored recycled product, the laminate is required to have excellent interlayer adhesion after high-temperature sterilization.

[0013] The present disclosure has been made in view of the above-mentioned problems, and an object of the present disclosure is to provide a gas barrier laminate, a packaging container, and a packaging product that are excellent in recyclability and can have excellent interlayer adhesion even after a high-temperature retort treatment.

[0014] Means for solving problems

[0015] The inventors of the present disclosure have conducted intensive research to solve the above-mentioned problems and have found that setting the amount of chlorine in the entire gas barrier layered product, as measured by combustion ion chromatography, to a specific range is effective for solving the above-mentioned problems, thereby completing the present disclosure.

[0016] That is, one aspect of the present disclosure provides a gas barrier laminate comprising: a gas barrier film having a gas barrier layer on at least one side of a substrate comprising a first polypropylene film; and at least one second polypropylene film laminated on the gas barrier film, wherein the gas barrier layer is obtained using a gas barrier layer-forming composition containing a resin and a first silicon compound, the first silicon compound being a hydrolyzate of a silicon compound represented by the following general formula (1), and a chlorine content, as measured by combustion ion chromatography, based on the total amount of the gas barrier laminate is greater than 0.0008% by mass and not more than 0.0080% by mass.

[0017] Si(OR 1 )4···(1)

[0018] (In the above general formula (1), OR 1 represents a hydrolyzable group.)

[0019] According to the gas barrier laminate, by setting the chlorine content of the gas barrier laminate as a whole to 0.0080% by mass or less, as measured by combustion ion chromatography, chlorine is less likely to act as a catalyst for the oxidative decomposition reaction of the polypropylene resin from the first polypropylene film or the second polypropylene film when the gas barrier laminate is melted for recycling, making the polypropylene resin less susceptible to oxidative decomposition. Consequently, the polypropylene resin is less likely to carbonize and discolor. As a result, the gas barrier laminate can exhibit excellent recyclability. Furthermore, by setting the chlorine content of the gas barrier laminate as a whole to greater than 0.0008% by mass, as measured by combustion ion chromatography, excellent interlayer adhesion can be achieved even after high-temperature retorting.

[0020] In the gas barrier laminate, the chlorine content, as measured by combustion ion chromatography, may be 0.0010% by mass or more and 0.0060% by mass or less based on the total amount of the gas barrier laminate.

[0021] When the chlorine content is within the above range, the gas barrier properties and interlayer adhesion of the gas barrier layered product after high-temperature retorting are further improved, and the recyclability is further improved.

[0022] In the gas barrier laminate, the chlorine content, as measured by combustion ion chromatography, may be 0.0010% by mass or more and 0.0050% by mass or less based on the total amount of the gas barrier laminate.

[0023] In the above-mentioned gas barrier laminate, in the gas barrier layer-forming composition, when the total mass of the resin and the first silicon compound is set to 100, the product of the mass ratio of the first silicon compound to the total mass and the ratio of the thickness of the gas barrier layer to the thickness of the gas barrier laminate can be 0.35 or less.

[0024] In this case, the recyclability of the gas barrier laminate is likely to be improved.

[0025] In the above-mentioned gas barrier laminate, in the gas barrier layer-forming composition, when the total mass of the resin and the first silicon compound is set to 100, the product of the mass ratio of the first silicon compound to the total mass and the ratio of the thickness of the gas barrier layer to the thickness of the gas barrier laminate can be greater than 0.04.

[0026] When the product is larger than 0.04, the gas barrier properties and interlayer adhesion of the gas barrier layered product after retorting tend to be further improved.

[0027] In the gas barrier laminate, the gas barrier film may further include an inorganic oxide layer between the substrate and the gas barrier layer.

[0028] In this case, the gas barrier properties of the gas barrier laminate can be further improved.

[0029] In the above-mentioned gas barrier laminate, the resin in the gas barrier layer-forming composition may be a water-soluble polymer, and the gas barrier layer-forming composition may further contain a second silicon compound, which may be at least one of a silane coupling agent represented by the following general formula (2) and a hydrolyzate thereof.

[0030] (R 2 Si(OR 3 )3) n ···(2)

[0031] (In the above general formula (2), OR 3 Represents a hydrolyzable group, R 2 represents a monovalent organic group. n is an integer greater than 1.)

[0032] In this case, the interlayer adhesion of the gas barrier laminate can be further improved.

[0033] In the gas barrier laminate, the gas barrier layer may have a thickness of 0.1 to 1.0 μm.

[0034] In this case, the gas barrier properties of the gas barrier layered product can be further improved even after high-temperature retorting, compared to a case where the gas barrier layer has a thickness of less than 0.1 μm. Furthermore, compared to a case where the gas barrier layer has a thickness exceeding 1.0 μm, the gas barrier layered product is less likely to curl, making it easier to use as a gas barrier layered product in packaging containers.

[0035] In the gas barrier laminate, the gas barrier film may further include an anchor coating layer between the substrate and the inorganic oxide layer.

[0036] In the gas barrier laminate, the second polypropylene film may be a sealant layer.

[0037] Another aspect of the present disclosure provides a packaging container obtained using the gas barrier laminate.

[0038] This packaging container, obtained using the aforementioned gas barrier laminate, exhibits excellent recyclability and maintains excellent interlayer adhesion even after high-temperature retorting. Therefore, even after high-temperature retorting of a packaged product containing contents within the container, delamination of the layers within the gas barrier laminate can be suppressed. Furthermore, after the contents are removed from the packaged product, the packaging container exhibits excellent recyclability.

[0039] Yet another aspect of the present disclosure provides a packaging product comprising the above-mentioned packaging container and contents contained in the packaging container.

[0040] This packaging product comprises a packaging container obtained using the aforementioned gas barrier layered product. The gas barrier layered product exhibits excellent recyclability and maintains excellent interlayer adhesion even after high-temperature retorting. Therefore, even after high-temperature retorting, delamination between layers in the gas barrier layered product can be suppressed. Furthermore, the packaging container remaining after the contents are removed from the packaging product exhibits excellent recyclability.

[0041] Effects of the Invention

[0042] According to the present disclosure, a gas barrier laminate, a packaging container, and a packaging product are provided that are excellent in recyclability and can have excellent interlayer adhesion even after a high-temperature retort treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] [ Figure 1 ] is a schematic cross-sectional view showing one embodiment of the gas barrier laminate disclosed herein.

[0044] [ Figure 2 ] is a schematic cross-sectional view showing one embodiment of the packaging product disclosed herein.

[0045] [ Figure 3 ] is a schematic cross-sectional view showing another embodiment of the gas barrier laminate disclosed herein.

[0046] [ Figure 4 ] is a schematic cross-sectional view showing another embodiment of the gas barrier laminate disclosed herein. DETAILED DESCRIPTION

[0047] Hereinafter, embodiments of the present disclosure will be described in detail.

[0048] <Gas Barrier Laminate>

[0049] First, refer to Figure 1 One embodiment of the gas barrier laminate of the present disclosure will be described. Figure 1 This is a schematic cross-sectional view showing one embodiment of the gas barrier laminate of the present disclosure.

[0050] Figure 1 The gas barrier laminate 20 shown includes a gas barrier film 10 having a gas barrier layer 4 on one side of a substrate 1 composed of a first polypropylene film, and a sealant layer 21 as a second polypropylene film laminated on the gas barrier film 10. In the gas barrier film 10, the gas barrier layer 4 is arranged on the sealant layer 21 side of the substrate 1.

[0051] The gas barrier layer 4 is obtained using a gas barrier layer-forming composition containing a resin and a first silicon compound, wherein the first silicon compound is at least one of a silane alkoxy compound represented by the following general formula (1) and a hydrolyzate thereof.

[0052] Si(OR 1 )4···(1)

[0053] (In the above general formula (1), OR 1 represents a hydrolyzable group.)

[0054] In the gas barrier laminate 20 , the chlorine content measured by combustion ion chromatography is greater than 0.0008 mass % and not more than 0.0080 mass % based on the total amount of the gas barrier laminate 20 .

[0055] It should be noted that the gas barrier film 10 may further include an inorganic oxide layer 3 between the substrate 1 and the gas barrier layer 4. Furthermore, the gas barrier film 10 may further include an anchor coating layer 2 between the substrate 1 and the inorganic oxide layer 3. Furthermore, the gas barrier laminate 20 may further include an adhesive layer 22 between the gas barrier layer 4 and the sealant layer 21.

[0056] In the gas barrier laminate 20, since the chlorine content of the entire gas barrier laminate 20, as measured by combustion ion chromatography, is less than 0.0080 mass%, when the gas barrier laminate 20 is melted for recycling, chlorine is less likely to act as a catalyst for the oxidative decomposition reaction of the polypropylene resin from the first polypropylene film contained in the substrate 1 or from the sealant layer 21, which is the second polypropylene film. Consequently, the polypropylene resin is less likely to carbonize and discolor. As a result, the gas barrier laminate 20 can exhibit excellent recyclability. Furthermore, since the chlorine content of the entire gas barrier laminate, as measured by combustion ion chromatography, is greater than 0.0008 mass%, excellent interlayer adhesion can be achieved even after high-temperature retorting.

[0057] Hereinafter, the substrate 1 , the anchor coating layer 2 , the inorganic oxide layer 3 , the gas barrier layer 4 , the adhesive layer 22 , and the sealing layer 21 will be described in detail.

[0058] (Base material)

[0059] The substrate 1 includes a first polypropylene film. The first polypropylene film contains a polypropylene resin. Homopolypropylene, which is a homopolymer of propylene, is preferably used as the polypropylene resin. However, as long as heat resistance is not impaired, the polypropylene resin may also be a propylene-α-olefin copolymer, which is a copolymer of propylene and an α-olefin, or a mixture of a propylene-α-olefin copolymer and homopolypropylene. Furthermore, to improve adhesion between the substrate 1 and the anchor coating 2, a layer containing a propylene-α-olefin copolymer or a mixture of a propylene-α-olefin copolymer and homopolypropylene may be further provided on the surface of the first polypropylene film on the side facing the anchor coating 2.

[0060] The polypropylene resin contained in the first polypropylene film may be a recycled polypropylene resin or a polypropylene resin obtained by homopolymerizing propylene derived from biomass such as plants or copolymerizing it with other monomers. These polypropylene resins may be used alone or in combination with a polypropylene resin obtained by homopolymerizing propylene derived from common fossil fuels or copolymerizing it with other monomers.

[0061] The first polypropylene film contained in the substrate 1 may be a stretched film or an unstretched film. The stretched film can be obtained by forming the above-mentioned polypropylene resin into a sheet and stretching the sheet by a conventional method. The stretched film may be a uniaxially oriented film or a biaxially oriented film.

[0062] The substrate 1 may further contain additives as needed. Examples of additives include antioxidants, stabilizers, lubricants such as calcium stearate, fatty acid amide, and erucamide, organic additives such as antistatic agents, and particulate lubricants such as silica, zeolite, syloid, hydrotalcite, and silicon particles.

[0063] In order to strengthen the adhesion between the substrate 1 and the anchor coating layer 2 , the surface of the substrate 1 may be subjected to a surface treatment such as plasma treatment or corona treatment.

[0064] The thickness of the substrate 1 is not particularly limited, and may be, for example, 15 to 100 μm.

[0065] (Anchor coating)

[0066] The anchor coating layer 2 is a layer that improves the adhesion between the substrate 1 and the inorganic oxide layer 3 after heat sterilization and the gas barrier properties of the gas barrier film 10 .

[0067] The material constituting the anchor coating layer 2 is not particularly limited as long as it can improve the adhesion between the substrate 1 and the inorganic oxide layer 3. Examples of such materials include reaction products of organosilanes or organometallic compounds, polyol compounds, and isocyanate compounds. Specifically, the anchor coating layer 2 can also be referred to as a urethane adhesive layer.

[0068] Examples of the organosilane include trifunctional organosilanes or hydrolysis products of trifunctional organosilanes. Examples of the organometallic compound include metal alkoxides or hydrolysis products of metal alkoxides. Examples of the metal element contained in the organometallic compound include Al, Ti, and Zr. The hydrolysis product of the organosilane and the hydrolysis product of the metal alkoxide each may contain at least one hydroxyl group.

[0069] From the perspective of transparency, the polyol compound is preferably an acrylic polyol. The isocyanate compound mainly functions as a crosslinking agent or a curing agent. The polyol compound and the isocyanate compound may be monomers or polymers.

[0070] The thickness of the anchor coating 2 is not particularly limited as long as it can improve the adhesion between the substrate 1 and the inorganic oxide layer 3, but is preferably greater than 50 nm. In this case, compared with the case where the thickness of the anchor coating 2 is 50 nm or less, the gas barrier properties can be further improved even after high-temperature boiling treatment. In addition, the durability of the gas barrier laminate 20 can also be further improved. The thickness of the anchor coating 2 is more preferably 70 nm or more, and more preferably 80 nm or more. By increasing the thickness of the anchor coating 2, the reduction in water vapor barrier properties when external forces such as stretching are applied can be further suppressed. The thickness of the anchor coating 2 is preferably less than 300 nm. In this case, compared with the case where the thickness of the anchor coating 2 is 300 nm or more, the durability of the gas barrier laminate 20 can be further improved, and the gas barrier properties can be further improved even after high-temperature boiling treatment. The thickness of the anchor coating 2 is more preferably 200 nm or less.

[0071] (Inorganic oxide layer)

[0072] The inorganic oxide layer 3 is a layer containing an inorganic oxide, and can further improve the gas barrier properties of the gas barrier layered body 20. The inorganic oxide layer 3 may have transparency.

[0073] Examples of inorganic substances constituting inorganic oxides include at least one atom selected from the group consisting of Si, Al, Mg, Sn, Ti, and In. Examples of inorganic oxides include aluminum oxide (AlO x ), silicon oxide (SiO x ), tin oxide, and magnesium oxide. These can be used alone or in mixtures of two or more. Among these, aluminum oxide or silicon oxide is preferred from the perspective of various sterilization resistances. Silicon oxide is particularly preferred as an inorganic oxide. In this case, the gas barrier laminate 20 can have even better water vapor barrier properties.

[0074] The inorganic oxide layer 3 may be composed of a single layer or a plurality of layers.

[0075] The inorganic oxide layer 3 may be a vapor-deposited layer.

[0076] The thickness of the inorganic oxide layer 3 varies depending on the type and composition of the inorganic oxide used, but is generally preferably 5 to 300 nm, with the value being appropriately selected within this range. When the thickness of the inorganic oxide layer 3 is 5 nm or greater, the inorganic oxide layer 3 tends to form a uniform film, allowing it to fully function as a gas barrier material. Furthermore, when the thickness of the inorganic oxide layer 3 is 300 nm or less, the inorganic oxide layer 3 tends to maintain its flexibility, and cracks in the inorganic oxide layer 3 caused by external factors such as bending and stretching of the gas barrier layered product 20 tend to be suppressed.

[0077] The thickness of the inorganic oxide layer 3 is more preferably 10 to 150 nm.

[0078] (Gas barrier layer)

[0079] The gas barrier layer 4 is a layer having gas barrier properties and is obtained using a gas barrier layer-forming composition. The gas barrier layer-forming composition contains a resin and a first silicon compound. The first silicon compound is at least one of a silane alkoxy compound represented by the following general formula (1) and a hydrolyzate thereof. The gas barrier layer-forming composition may further contain a second silicon compound. The second silicon compound is at least one of a silane coupling agent represented by the following general formula (2) and a hydrolyzate thereof.

[0080] Si(OR 1 )4···(1)

[0081] (In the above general formula (1), OR 1 represents a hydrolyzable group.)

[0082] (R 2 Si(OR 3 )3) n ···(2)

[0083] (In the above general formula (2), OR 3 Represents a hydrolyzable group, R 2 represents a monovalent organic group. n is an integer greater than 1.)

[0084] As the above-mentioned resin, for example, a water-soluble polymer is used. Examples of water-soluble polymers include polyvinyl alcohol resin, its modified form, and polyacrylic acid. These can be used alone or in combination of two or more. Among them, polyvinyl alcohol resin or its modified form is preferred as the water-soluble polymer. In this case, the composition can impart even better gas barrier properties to the gas barrier film 10 by curing. In addition, even after curing, the composition can impart even better flexibility to the gas barrier film 10, and can suppress the generation of cracks in the gas barrier layer 4 even during processes such as lamination.

[0085] When the water-soluble polymer is composed of polyvinyl alcohol resin or a modified form thereof, the saponification degree of the water-soluble polymer is not particularly limited, but is preferably 95% or more and may be 100% from the viewpoint of improving the gas barrier properties of the gas barrier film 10 .

[0086] The degree of polymerization of the water-soluble polymer is not particularly limited, but is preferably 300 or higher from the viewpoint of improving the gas barrier properties of the gas barrier film 10. The degree of polymerization of the water-soluble polymer is preferably 450 to 2400.

[0087] The content of the water-soluble polymer is not particularly limited, but is preferably 25% by mass or greater, based on the combined mass of the water-soluble polymer and the first silicon compound (100% by mass). In this case, curing further improves the gas barrier properties and interlayer adhesion of the gas barrier laminate 20 even after high-temperature retorting. Based on the combined mass of the water-soluble polymer and the first silicon compound, the content of the water-soluble polymer is preferably 26% by mass or greater, more preferably 27% by mass or greater, and particularly preferably 40% by mass or greater.

[0088] When the total mass of the water-soluble polymer and the first silicon compound is taken as a reference (100 mass%), the content of the water-soluble polymer is preferably 60 mass% or less, more preferably 58 mass% or less, and particularly preferably 55 mass% or less. When the content of the water-soluble polymer is 60 mass% or less, the water resistance of the gas barrier layer 4 is improved, and the gas barrier properties and interlayer adhesion of the gas barrier layered product 20 can be further improved even after high-temperature retorting.

[0089] The first silicon compound is at least one of a silicon alkoxy compound and a hydrolyzate thereof. The silicon alkoxy compound is represented by the following general formula (1). In this case, not only can the gas barrier properties of the gas barrier layer 20 be improved, but also the adhesion between the gas barrier layer 4 and the inorganic oxide layer 3 can be improved, and delamination within the gas barrier layer 20 can be suppressed.

[0090] Si(OR 1 )4···(1)

[0091] In the general formula (1), OR 1 represents a hydrolyzable group. 1 , for example, alkyl and -C2H4OCH3 can be cited. Examples of alkyl groups include methyl and ethyl. Among them, ethyl is preferred. In this case, the silane alkoxy compound is tetraethoxysilane (TEOS), which is relatively stable in aqueous solvents after hydrolysis.

[0092] The content of the first silicon compound is not particularly limited, but is preferably 40% by mass or greater, more preferably 42% by mass or greater, and particularly preferably 45% by mass or greater, based on the total mass of the water-soluble polymer and the first silicon compound (100% by mass). In this case, the gas barrier properties and interlayer adhesion of the gas barrier layered product 20 can be further improved even after high-temperature retorting, compared to a case where the content of the first silicon compound is less than 40% by mass.

[0093] When the total mass of the water-soluble polymer and the first silicon compound is taken as a reference (100 mass%), the content of the first silicon compound is preferably 75 mass% or less, more preferably 74 mass% or less, and particularly preferably 73 mass% or less. When the content of the first silicon compound is 75 mass% or less, the gas barrier layer 4 after curing does not become too hard, cracks in the gas barrier layer 4 are less likely to occur, and deterioration of the gas barrier properties is less likely. In addition, the gas barrier properties and interlayer adhesion of the gas barrier laminate 20 can be further improved even after high-temperature retorting. In addition, the amount of hydrochloric acid required for hydrolysis can be reduced, and the amount of chlorine in the gas barrier laminate 20 is less likely to be excessive, thereby easily improving the recyclability of the gas barrier laminate 20.

[0094] The second silicon compound is at least one of a silane coupling agent and a hydrolyzate thereof. The silane coupling agent is represented by the following general formula (2). In this case, the adhesion between the gas barrier layer 4 and the inorganic oxide layer 3 can be improved, and the interlayer adhesion of the gas barrier laminate 20 can be further improved.

[0095] (R 2 Si(OR 3 )3) n ···(2)

[0096] In the general formula (2), R 2 Represents a monovalent organic group, OR 3 represents a hydrolyzable group, and n represents an integer of 1 or greater.

[0097] As R 2 Examples of the monovalent organic group include those containing a vinyl group, an epoxy group, a mercapto group, an amino group, or an isocyanate group. Among these, the monovalent organic group is preferably a monovalent organic group containing an isocyanate group. In this case, the gas barrier layer-forming composition can exhibit even better hot water resistance upon curing, and can impart even greater lamination strength to the gas barrier layered product 20 even after high-temperature retorting.

[0098] As R 3 , alkyl and -C2H4OCH3 can be cited. Examples of the alkyl group include methyl and ethyl. Among them, methyl is preferred. In this case, the hydrolysis of the silane coupling agent proceeds rapidly.

[0099] It should be noted that R 3 With R 2 They may be the same or different. In addition, when n is an integer greater than 2, R 3 They can be the same or different from each other.

[0100] n represents an integer greater than or equal to 1. When n is 1, the silane coupling agent represents a monomer, while when n is 2 or greater, the silane coupling agent represents a polymer. n is preferably 3. In this case, the hot water resistance of the gas barrier layer 4 can be further improved, and even after high-temperature retorting, greater lamination strength can be imparted to the gas barrier layered product 20.

[0101] Examples of silane coupling agents include vinyl-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane; epoxy-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropylethyldiethoxysilane; mercapto-containing silane coupling agents such as 3-mercaptopropyltrimethoxysilane and 3-mercaptopropylmethyldimethoxysilane; amino-containing silane coupling agents such as 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; and isocyanate-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane and 1,3,5-tris(3-methoxysilylpropyl)isocyanurate. These silane coupling agents may be used alone or in combination of two or more.

[0102] Among the above silane coupling agents, the most preferred are those having the general formula (NCO-R 4 Si(OR 3 )3)3(where R 4 -(CH2) n -, n is 1 or greater). This 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate has hydrophobicity due to the polarity of the urate moiety, and thus can impart high water resistance to the gas barrier layer 4.

[0103] The content of the second silicon compound is not particularly limited, but is preferably 3% by mass or greater, more preferably 5% by mass or greater, and particularly preferably 7% by mass or greater, based on the total mass of the water-soluble polymer and the first silicon compound (100% by mass). In this case, compared to a case where the content of the second silicon compound is less than 3% by mass, curing can impart greater lamination strength to the gas barrier layer 20 even after high-temperature retorting.

[0104] When the total mass of the water-soluble polymer and the first silicon compound is taken as a reference (100 mass%), the content of the second silicon compound is preferably 20 mass% or less, more preferably 15 mass% or less, and particularly preferably 12 mass% or less. In this case, the content of the water-soluble polymer and the first silicon compound in the gas barrier layer 4 is relatively increased compared to a case where the content of the second silicon compound exceeds 20 mass%, thereby maintaining good gas barrier properties.

[0105] It should be noted that when calculating the content of the water-soluble polymer, the first silicon compound and the second silicon compound, the calculation of the above-mentioned content is performed after converting the mass of the first silicon compound into the mass of SiO2 and converting the mass of the second silicon compound into the mass of R2Si(OH)3.

[0106] The gas barrier layer-forming composition may contain known additives such as an isocyanate compound, a dispersant, a stabilizer, a viscosity modifier, and a colorant as needed, within a range not impairing the gas barrier properties.

[0107] The thickness of the gas barrier layer 4 is preferably 0.1 μm or greater. In this case, the gas barrier properties of the gas barrier layer 20 can be further improved even after high-temperature retorting compared to a case where the thickness of the gas barrier layer 4 is less than 0.1 μm. From the perspective of improving the gas barrier properties of the gas barrier layer 20, the thickness of the gas barrier layer 4 is more preferably 0.15 μm or greater, particularly preferably 0.17 μm or greater.

[0108] On the other hand, the thickness of the gas barrier layer 4 is preferably 1.0 μm or less. Compared to a case where the thickness of the gas barrier layer 4 exceeds 1.0 μm, the gas barrier layer 20 is less likely to curl, making it easier to use as a gas barrier layer 20 for forming a packaging container. To further improve the flexibility of the gas barrier layer 20, the thickness of the gas barrier layer 4 is more preferably 0.7 μm or less, and particularly preferably 0.5 μm or less.

[0109] (Adhesive layer)

[0110] The adhesive layer 22 is a layer that bonds the gas barrier layer 4 of the gas barrier film 10 to the sealing layer 21. As an adhesive forming the adhesive layer 22, for example, a polyurethane resin obtained by using an adhesive containing a main agent such as polyester polyol, polyether polyol, acrylic polyol, carbonate polyol, and a difunctional or higher isocyanate compound can be cited. Various polyols can be used alone or in combination of two or more. From the perspective of heat resistance (resistance to retort treatment) during heat sterilization, a two-component curing type urethane adhesive can be preferably used.

[0111] To promote adhesion, the above-mentioned adhesives may be compounded with carbodiimide compounds, oxazoline compounds, epoxy compounds, phosphorus compounds, silane coupling agents, and the like. From an environmental perspective, the adhesive used to form the adhesive layer 22 may also contain biomass-derived polymers or biodegradable adhesives. Furthermore, the adhesive may have barrier properties.

[0112] From the viewpoint of obtaining the desired adhesive strength, followability, and workability, the coating amount of the adhesive may be, for example, 0.5 to 10 g / m2 .

[0113] As a method for forming and laminating the adhesive layer 22 , known methods such as dry lamination and non-solvent lamination can be mentioned.

[0114] When using the non-solvent lamination method, the amount of adhesive applied can be reduced to 0.5 to 3 g / m2 compared to the dry lamination method. 2 This further increases the polypropylene content in the entire gas barrier laminate 20. Furthermore, when heat-sealing the gas barrier laminate 20, heat conduction from the heat seal bar is improved, reducing the sealing time and temperature, and suppressing the generation of wrinkles associated with heat sealing.

[0115] Furthermore, when a non-solvent lamination method is used, since the adhesive does not contain an organic solvent, the amount of residual solvent in the gas barrier laminate 20 can be reduced. More specifically, the gas barrier laminate 20 includes a polypropylene film as the substrate 1 and a sealant layer 21. Therefore, when a dry lamination method is used to produce the gas barrier laminate 20, in order to prevent thermal shrinkage of the gas barrier laminate 20, the drying temperature needs to be lower than that of a polyester-based laminate. In this case, the solvent in the adhesive is not fully volatilized and remains in the gas barrier laminate 20, and odors generated by the residual solvent may remain. In contrast, when a non-solvent lamination method is used and a solvent-free adhesive is used, the amount of residual solvent in the adhesive layer 2 can be further reduced, and the amount of residual solvent in the gas barrier laminate 20 can be reduced. Such a gas barrier laminate 20 is suitable for producing a single-material packaging container.

[0116] (Sealing layer)

[0117] The sealant layer 21 includes a second polypropylene film. The second polypropylene film includes a polypropylene resin. The polypropylene resin may be a homopolypropylene, which is a homopolymer of propylene, a propylene-α-olefin copolymer, which is a copolymer of propylene and α-olefin, or a mixture thereof.

[0118] The polypropylene resin contained in the second polypropylene film may be a recycled polypropylene resin or a polypropylene resin obtained by homopolymerizing propylene derived from biomass such as plants or copolymerizing it with other monomers. These polypropylene resins may be used alone or mixed with a polypropylene resin obtained by homopolymerizing propylene derived from common fossil fuels or copolymerizing it with other monomers.

[0119] The second polypropylene film included in the sealant layer 21 may be a stretched film or an unstretched film, but is preferably an unstretched film from the viewpoint of lowering the melting point and facilitating heat sealing.

[0120] The sealing layer 21 may further contain additives as needed. Examples of the additives include antioxidants, stabilizers, lubricants such as calcium stearate, fatty acid amide, and erucamide, organic additives such as antistatic agents, and particulate lubricants such as silica, zeolite, syloid, hydrotalcite, and silicon particles.

[0121] The thickness of the sealant layer 21 is not particularly limited and may be, for example, 15 μm or greater, 30 μm or greater, 50 μm or greater, 60 μm or greater, or 70 μm or greater. The thickness of the sealant layer 21 is preferably 50 μm or greater. When the thickness of the sealant layer 21 is 50 μm or greater, the amount of chlorine in the gas barrier layer 20 can be easily reduced, further improving the recyclability of the gas barrier layer 20. Furthermore, when the thickness of the sealant layer 21 is 50 μm or greater, the rigidity of the sealant layer 21 can be increased, and the durability of the packaging bag using the gas barrier layer 20 when dropped can also be improved.

[0122] The thickness of the sealing layer 21 may be 150 μm or less, 130 μm or less, 110 μm or less, or 100 μm or less.

[0123] (Gas Barrier Laminate)

[0124] In the gas barrier laminate 20 , the chlorine content measured by combustion ion chromatography is greater than 0.0008 mass % and not more than 0.0080 mass % based on the total amount of the gas barrier laminate 20 .

[0125] When the chlorine content in the gas barrier laminate 20 is 0.0080% by mass or less, the high-temperature melting of the gas barrier laminate 20 during recycling makes it difficult for the polypropylene resin contained in the gas barrier laminate 20 to undergo oxidative decomposition reactions, resulting in a reduced tendency to discolor and easy use as a recycled product, thereby achieving excellent recyclability. On the other hand, when the chlorine content in the gas barrier laminate 20 exceeds 0.0008% by mass, the gas barrier laminate 20 exhibits excellent interlayer adhesion even after high-temperature retorting.

[0126] The amount of chlorine contained in the gas barrier laminate 20 is preferably 0.0010 mass% or more, more preferably 0.0015 mass% or more, even more preferably 0.0020 mass% or more, and particularly preferably 0.0025 mass% or more. When the chlorine content is 0.0010 mass% or more, the gas barrier properties and interlayer adhesion of the gas barrier laminate 20 after high-temperature retorting are further improved.

[0127] The amount of chlorine contained in the gas barrier layered product 20 can be, for example, 0.0070 mass% or less, preferably 0.0060 mass% or less, more preferably 0.0050 mass% or less, still more preferably 0.0040 mass% or less, and particularly preferably 0.0030 mass% or less. When the chlorine content is 0.0060 mass% or less, the gas barrier properties and interlayer adhesion of the gas barrier layered product 20 after high-temperature retorting are further improved. Furthermore, recyclability is further enhanced.

[0128] The melt mass flow rate (MFR, unit: g / 10min) of the melt when the gas barrier laminate 20 is cut into appropriate sizes and melt-extruded can be, for example, 2.0 g / 10min or more and 7.0 g / 10min or less. The MFR is preferably 2.0 g / 10min or more and 6.5 g / 10min or less, more preferably 3.0 g / 10min or more and 6.0 g / 10min or less, and particularly preferably 3.4 g / 10min or more and 5.0 g / 10min or less. When the MFR is 7.0 g / 10min or less, the decomposition of the recycled resin does not progress, which is preferable from the perspective of obtaining a recyclable laminate. When the MFR is 2.0 g / 10min or more, the resin viscosity does not become too high and the film forming properties are stable. The MFR can be measured from a melt during melt extrusion using a melt viscosity meter (MeltIndexer F-F01 manufactured by Toyo Seiki Seisaku-sho, Ltd.) in accordance with the method described in JIS K 7210 under the conditions of a temperature of 230° C. and 2.16 kgf.

[0129] In the gas barrier layer-forming composition, the product of the mass ratio C1 of the first silicon compound to the total mass of the water-soluble polymer and the first silicon compound, with the total mass being taken as a reference (100), and the ratio R1 of the thickness of the gas barrier layer 4 to the thickness of the gas barrier layer 20 (hereinafter also referred to as "SiO2 ratio") P is not particularly limited, but is preferably 0.35 or less, more preferably 0.25 or less, and particularly preferably 0.24 or less. When the SiO2 ratio P is 0.35 or less, the recyclability of the gas barrier layer 20 is easily improved.

[0130] The SiO2 ratio P is preferably greater than 0.04, more preferably greater than 0.10, and particularly preferably greater than 0.15. When the SiO2 ratio P is greater than 0.04, the gas barrier properties and interlayer adhesion of the gas barrier laminate 20 after high-temperature retorting tend to be further improved.

[0131] The thickness of the gas barrier laminate 20 is not particularly limited, but is preferably 200 μm or less. When the thickness of the gas barrier laminate 20 is 200 μm or less, the heat sealability is less likely to decrease when manufacturing a packaging container, and the gas barrier laminate 20 is less likely to warp, making it easier to use as a packaging container.

[0132] The thickness of the gas barrier laminate 20 may be 180 μm or less, 160 μm or less, 140 μm or less, or 120 μm or less.

[0133] The thickness of the gas barrier laminate 20 may be 40 μm or more, 60 μm or more, 80 μm or more, or 100 μm or more.

[0134] <Method for Producing Gas Barrier Laminate>

[0135] Next, a method for producing the gas barrier laminate 20 will be described.

[0136] First, a substrate 1 is prepared.

[0137] Next, the anchor coating layer 2 is formed on the substrate 1. The anchor coating layer 2 can be obtained by applying the anchor coating layer-forming composition on the surface of the substrate 1 and drying it.

[0138] Next, an inorganic oxide layer 3 is formed on the anchor coating layer 2 .

[0139] The inorganic oxide layer 3 can be formed using a vacuum evaporation method, a sputtering method, an ion plating method, a plasma vapor deposition method (CVD), and the like. However, considering productivity, the most preferred method is a vacuum evaporation method. As the heating method used in the vacuum evaporation method, it is preferred to use any one of an electron beam heating method, a resistance heating method, and an induction heating method, but considering the breadth of selectivity of the evaporation material, it is more preferred to use an electron beam heating method. In addition, in order to improve the adhesion between the inorganic oxide layer 3 and the substrate 1 and the compactness of the inorganic oxide layer 3, a plasma-assisted method or an ion beam-assisted method can also be used for evaporation. In addition, in order to improve the transparency of the deposited film, a reactive evaporation method in which various gases such as oxygen are blown into the evaporation film can also be used.

[0140] Next, the gas barrier layer 4 is formed on the inorganic oxide layer 3 to obtain the gas barrier film 10 .

[0141] The gas barrier layer 4 can be obtained by applying a gas barrier layer-forming composition containing a resin and a first silicon compound on the inorganic oxide layer 3 and drying it. The gas barrier layer-forming composition may further contain hydrochloric acid. Hydrochloric acid is added as a catalyst to promote the hydrolysis reaction of the silane alkoxy compound with a low hydrolysis rate. Compared with other acids, hydrochloric acid has a fast reaction rate, is easy to evaporate, and is low in cost, so it is preferably used. When the gas barrier layer-forming composition also contains a second silicon compound, and the silane coupling agent used as the second silicon compound is a silane coupling agent having an epoxy group, hydrochloric acid can open the epoxy group.

[0142] Examples of the coating method include wet film-forming methods such as gravure coating, dip coating, reverse coating, wire bar coating, and die coating.

[0143] The amount of chlorine contained in the gas barrier laminate 20 can be adjusted by adjusting the content of the first silicon compound or hydrochloric acid in the gas barrier layer-forming composition, the film thickness of the gas barrier layer 4, and the coating conditions (heating temperature, heating time) of the gas barrier layer-forming composition when forming the gas barrier layer 4.

[0144] Next, the sealant layer 21 is formed on the gas barrier layer 4 of the gas barrier film 10 via the adhesive layer 22. In this way, the gas barrier laminate 20 is obtained.

[0145] <Packaging products>

[0146] Next, refer to Figure 2 The embodiment of the packaging product disclosed in the present invention is described. It should be noted that, Figure 2 : is a cross-sectional view showing one embodiment of the packaging product disclosed herein. Figure 2 In, with Figure 1 The same components are denoted by the same reference numerals, and redundant descriptions are omitted.

[0147] like Figure 2 As shown, the packaged product 40 includes a packaging container 30 and contents C accommodated in the packaging container 30 . Figure 2 The packaging container 30 shown is obtained by using a pair of gas barrier layered products 20 and heat-sealing the four peripheral edges of the gas barrier layered products 20 with the sealing layers 21 facing each other. Figure 2 In the figure, the adhesive layer 22 of the gas barrier laminate 20 is omitted.

[0148] This packaging product 40 includes a packaging container 30 using a gas barrier laminate 20. The gas barrier laminate 20 has excellent recyclability and maintains excellent interlayer adhesion even after high-temperature retorting. Therefore, even after high-temperature retorting, delamination of the gas barrier laminate 20 is suppressed. Furthermore, after the contents C are discharged from the packaging product 40, the remaining packaging container 30 has excellent recyclability.

[0149] The packaging container 30 can also be obtained by folding one gas barrier layer stack 20 and heat-sealing the three peripheral edges of the gas barrier layer stack 20 with the sealant layers 21 facing each other.

[0150] Examples of the packaging container 30 include packaging bags, laminated tube containers, and liquid paper containers.

[0151] The content C is not particularly limited, and examples of the content C include food, liquids, medicines, and electronic components.

[0152] For example, in the above embodiment, the sealant layer 21 of the gas barrier laminate 20 is bonded to the gas barrier layer 4 of the gas barrier film 10 , but the sealant layer 21 may be bonded to the substrate 1 .

[0153] In the above embodiment, the gas barrier laminate 20 includes the gas barrier film 10 and the sealant layer 21 as a second polypropylene film laminated on the gas barrier film 10. However, in order to improve the rigidity of the packaging container, the gas barrier laminate may further include one or more outer films as the second polypropylene film in addition to the sealant layer. For example, Figure 3 Like the gas barrier laminate 120 shown in FIG. 1 , the gas barrier laminate 120 may include an outer layer film 121, a gas barrier film 10, and a sealant layer 21 in this order. Figure 3 In the embodiment, the outer layer film 121 is bonded to the substrate 1 via the adhesive layer 22. Figure 3 In the figure, the gas barrier layer 4 of the gas barrier film 10 is arranged on the sealant layer 21 side (inner side) relative to the substrate 1 , but the gas barrier layer 4 may be arranged on the outer layer film 121 side (outer side).

[0154] According to the gas barrier laminate 120, it has excellent recyclability and can have excellent interlayer adhesion even after high-temperature cooking treatment. It can also impart rigidity to the packaging container. Therefore, even after high-temperature cooking treatment, it is difficult to apply excessive stress to the gas barrier layer 4, and the generation of cracks in the gas barrier layer 4 can be suppressed.

[0155] In addition, the gas barrier laminate of the present disclosure may also be Figure 4 The gas barrier laminate 220 shown in FIG. 1 includes a gas barrier film 10, an outer layer film 121, and a sealant layer 21 in this order. Figure 4 In the embodiment, the outer film 121 is bonded to the gas barrier layer 4 via the adhesive layer 22. Figure 4 In the figure, the gas barrier layer 4 of the gas barrier film 10 is arranged on the sealing layer 21 side (inner side) relative to the substrate 1 , but the gas barrier layer 4 may be arranged on the opposite side (outer side) of the sealing layer 21 relative to the substrate 1 .

[0156] The gas barrier laminate 220 has excellent recyclability and can have excellent interlayer adhesion even after high-temperature cooking treatment. It can also impart rigidity to the packaging container. Therefore, even after high-temperature cooking treatment, it is difficult to apply excessive stress to the gas barrier layer 4, thereby suppressing the generation of cracks in the gas barrier layer 4.

[0157] The outer layer film 121 is a layer provided to improve the rigidity of the packaging container. Therefore, the outer layer film 121 can be referred to as a second base material layer.

[0158] The outer layer film 121 is a second polypropylene film. The second polypropylene film comprises a polypropylene resin. A propylene homopolymer, i.e., homopolypropylene, is preferably used as the polypropylene resin. However, as long as heat resistance is not impaired, the polypropylene resin may be a copolymer of propylene and an α-olefin, i.e., a propylene-α-olefin copolymer, or a mixture of a propylene-α-olefin copolymer and homopolypropylene. Furthermore, to improve adhesion between the outer layer film 121 and layers in contact with the outer layer film 121, a layer comprising a propylene-α-olefin copolymer or a mixture of a propylene-α-olefin copolymer and homopolypropylene may be further provided on the surface of the second polypropylene film.

[0159] The polypropylene resin contained in the second polypropylene film may be a recycled polypropylene resin or a polypropylene resin obtained by homopolymerizing propylene from biomass such as plants or copolymerizing it with other monomers. These polypropylene resins may be used alone or mixed with a polypropylene resin obtained by homopolymerizing propylene from conventional fossil fuels or copolymerizing it with other monomers.

[0160] The second polypropylene film included in the outer layer 121 may be a stretched film or an unstretched film. The stretched film can be obtained by forming the above-mentioned polypropylene resin into a sheet and stretching the sheet using a conventional method. The stretched film may be a uniaxially oriented film or a biaxially oriented film.

[0161] The outer layer 121 may further contain additives as needed. Examples of additives include antioxidants, stabilizers, lubricants such as calcium stearate, fatty acid amide, and erucamide, organic additives such as antistatic agents, and particulate lubricants such as silicon dioxide, zeolite, syloid, hydrotalcite, and silicon particles.

[0162] The outer layer film 121 may be the same as or different from the substrate 1 .

[0163] The thickness of the outer layer film 121 is not particularly limited, and may be, for example, 15 to 100 μm.

[0164] <Overview of the present disclosure>

[0165] A summary of the present disclosure is as follows.

[0166] [1] A gas barrier laminate comprising: a gas barrier film having a gas barrier layer on at least one side of a substrate comprising a first polypropylene film; and at least one second polypropylene film laminated on the gas barrier film, wherein the gas barrier layer is obtained using a gas barrier layer-forming composition containing a resin and a first silicon compound, the first silicon compound being at least one of a silane alkoxy compound represented by the following general formula (1) and a hydrolyzate thereof, and wherein the chlorine content, as measured by combustion ion chromatography, based on the total amount of the gas barrier laminate is greater than 0.0008% by mass and not more than 0.0080% by mass.

[0167] Si(OR 1 )4···(1)

[0168] (In the above general formula (1), OR 1 represents a hydrolyzable group.)

[0169] [2] The gas barrier laminate according to claim 1, wherein the chlorine content, as measured by combustion ion chromatography, is from 0.0010% by mass to 0.0060% by mass based on the total amount of the gas barrier laminate.

[0170] [3] The gas barrier laminate according to [2], wherein the chlorine content, as measured by combustion ion chromatography, is 0.0010 mass % or more and 0.0050 mass % or less based on the total amount of the gas barrier laminate.

[0171] [4] The gas barrier laminate according to any one of [1] to [3], wherein in the gas barrier layer-forming composition, when the total mass of the resin and the first silicon compound is 100, the product of the mass ratio of the first silicon compound to the total mass and the ratio of the thickness of the gas barrier layer to the thickness of the gas barrier laminate is 0.35 or less.

[0172] [5] The gas barrier laminate according to any one of [1] to [4], wherein in the gas barrier layer-forming composition, the product of the mass ratio of the first silicon compound to the total mass, when the total mass of the resin and the first silicon compound is set to 100, and the ratio of the thickness of the gas barrier layer to the thickness of the gas barrier laminate is greater than 0.04.

[0173] [6] The gas barrier laminate according to any one of [1] to [5], wherein the gas barrier film includes an inorganic oxide layer between the substrate and the gas barrier layer.

[0174] [7] The gas barrier laminate according to any one of [1] to [6], wherein the resin in the gas barrier layer-forming composition is a water-soluble polymer, and the gas barrier layer-forming composition further contains a second silicon compound, and the second silicon compound is at least one of a silane coupling agent represented by the following general formula (2) and a hydrolyzate thereof.

[0175] (R 2 Si(OR 3 )3) n ···(2)

[0176] (In the above general formula (2), OR 3 Represents a hydrolyzable group, R 2 represents a monovalent organic group. n is an integer greater than 1.)

[0177] [8] The gas barrier laminate according to any one of [1] to [7], wherein the gas barrier layer has a thickness of 0.1 to 1.0 μm.

[0178] [9] The gas barrier laminate according to [6], wherein the gas barrier film further comprises an anchor coating layer between the substrate and the inorganic oxide layer.

[0179]

[10] The gas barrier laminate according to any one of [1] to [9], wherein the second polypropylene film is a sealant layer.

[0180]

[11] A packaging container obtained using the gas barrier laminate according to any one of [1] to

[10] .

[0181]

[12] A packaging product comprising: the packaging container described in

[11] , and contents contained in the packaging container.

[0182] Example

[0183] Hereinafter, the present disclosure will be described in detail with reference to examples, but the present disclosure is not limited to these examples.

[0184] <Preparation of coating solution>

[0185] Coating liquids 1 to 5 as gas barrier layer-forming compositions used in Examples and Comparative Examples were prepared as follows.

[0186] (Coating liquid 1)

[0187] The following liquid A and liquid B are mixed so that the mass ratios of polyvinyl alcohol (also called "PVA") and tetraethoxysilane (also called "TEOS") as a silane oxide compound are 55 and 45, respectively, based on the total mass of PVA and TEOS (converted as SiO2) as a reference (100). Then, liquid C is added to liquid A and liquid B in an amount that is 10% by mass relative to the total of 100% by mass of PVA and TEOS (converted as SiO2) to obtain a coating liquid.

[0188] Liquid A: 5 mass% aqueous solution of PVA (trade name: Kuraray Poval 60-98, manufactured by Kuraray Co., Ltd.)

[0189] Solution B: TEOS (trade name: KBE04, solid content: 100%, manufactured by Shin-Etsu Chemical Co., Ltd.), methanol (manufactured by Kanto Chemical Co., Ltd.), and 0.1N hydrochloric acid (manufactured by Kanto Chemical Co., Ltd.) were mixed at a mass ratio of 17 / 10 / 73, and the resulting mixture was stirred to hydrolyze the TEOS (a 5 mass% (as SiO2) hydrolyzed solution of TEOS).

[0190] Liquid C: A solution obtained by diluting the solid content of a mixed solution of 1,3,5-tris(3-methoxysilylpropyl)isocyanurate (trade name: X-12-965P, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent and water / IPA = 1 / 1 (mass ratio) to 5 mass% (converted to R2Si(OH)3).

[0191] (Coating liquid 2)

[0192] The above-mentioned liquid A and liquid B are mixed so that the mass ratio of PVA and TEOS is 45 and 55 respectively based on the total mass of PVA and TEOS (converted as SiO2) as a reference (100), and then liquid C is added to liquid A and liquid B in such a manner that the amount becomes 10% by mass relative to the total of 100% by mass of PVA and TEOS (converted as SiO2) to obtain a coating liquid.

[0193] (Coating liquid 3)

[0194] The above-mentioned liquid A and liquid B are mixed so that the mass ratio of PVA and TEOS is 28 and 72 respectively based on the total mass of PVA and TEOS (converted as SiO2) as a reference (100), and then liquid C is added to liquid A and liquid B in such a manner that the amount becomes 10% by mass relative to the total 100% by mass of PVA and TEOS (converted as SiO2) to obtain a coating liquid.

[0195] (Coating liquid 4)

[0196] The above-mentioned liquid A and liquid B are mixed so that the mass ratio of PVA and TEOS is 23 and 77 respectively based on the total mass of PVA and TEOS (converted as SiO2) as a reference (100). Then, liquid C is added to liquid A and liquid B in such a manner that the amount becomes 10% by mass relative to the total of 100% by mass of PVA and TEOS (converted as SiO2) to obtain a coating liquid.

[0197] (Coating liquid 5)

[0198] The above-mentioned liquid A and liquid B are mixed so that the mass ratio of PVA and TEOS is 90 and 10 respectively based on the total mass of PVA and TEOS (converted as SiO2) (100), and then liquid C is added to liquid A and liquid B in such a manner that the amount becomes 10% by mass relative to the total of 100% by mass of PVA and TEOS (converted as SiO2) to obtain a coating liquid.

[0199] <Preparation of Anchor Coat Layer-Forming Composition>

[0200] The anchor coating layer-forming composition was prepared as follows.

[0201] Acrylic polyol and toluene diisocyanate were mixed so that the number of NCO groups in toluene diisocyanate was equal to the number of OH groups in acrylic polyol, and then diluted with ethyl acetate so that the solid content (acrylic polyol and toluene diisocyanate) was 5% by mass. β-(3,4-epoxycyclohexyl)trimethoxysilane was further added to the diluted mixture so that the total amount was 5 parts by mass relative to 100 parts by mass of the acrylic polyol and toluene diisocyanate, and the mixture was mixed to prepare an anchor coating layer-forming composition (anchor coating agent).

[0202] <Production of Gas Barrier Laminate>

[0203] (Examples 1, 3, 4, 5 and Comparative Examples 1 and 3)

[0204] First, a biaxially stretched polypropylene film (trade name “ME-1”, OPP, manufactured by Mitsui Chemicals Tohcello, Inc.) having a thickness of 20 μm was prepared as a substrate.

[0205] Next, the anchor coating layer-forming composition prepared above was applied to one surface of the substrate by gravure coating to form a coating film. The coating film was then heated at 60°C for 60 seconds and dried to form an anchor coating layer (AC layer) with a thickness of 100 nm.

[0206] Next, SiO was formed on the anchor coating layer to a thickness of 25 nm. x Film (inorganic oxide layer). At this time, SiO x The film was formed by using a vacuum evaporation apparatus employing electron beam heating to evaporate silicon dioxide by electron beam heating.

[0207] Then, in SiO xThe coating liquids listed in Table 1 were applied to the film to form a coating film. This coating film was then dried by heating at 60°C for 60 seconds to form a gas barrier layer having a thickness after drying (thickness a of the gas barrier layer) shown in Table 1. In this manner, a gas barrier film comprising a substrate, an anchor coating layer, an inorganic oxide layer, and a gas barrier layer was obtained.

[0208] Next, a 60 μm thick unstretched polypropylene film (trade name "TORAYFAN ZK207", manufactured by Toray Industries, Inc.) was adhered to the surface of the gas barrier layer of the gas barrier film by dry lamination using a two-component curable urethane adhesive (trade name "A525 / A52") as a sealant.

[0209] As described above, a gas barrier laminate was obtained in which a substrate, an anchor coating layer, an inorganic oxide layer, a gas barrier layer, an adhesive layer, and a sealant layer were sequentially laminated. In the obtained gas barrier laminate, the SiO2 ratio P expressed by the following formula was determined. The results are shown in Table 1.

[0210] SiO2 to P

[0211] = Mass ratio of TEOS (converted to SiO2) × thickness a (μm) of gas barrier layer / thickness b (μm) of gas barrier laminate (laminate)

[0212] (Example 6)

[0213] A gas barrier laminate was obtained in the same manner as in Example 1, except that a 50 μm thick unstretched polypropylene film (trade name "CPP50") as shown in Table 1 was used as the sealant layer. The SiO2 ratio P of the obtained gas barrier laminate was determined in the same manner as in Example 1. The results are shown in Table 1.

[0214] (Example 7)

[0215] A gas barrier laminate was obtained in the same manner as in Example 1, except that an unstretched polypropylene film (trade name "CPP80") having a thickness of 80 μm as shown in Table 1 was used as the sealant layer. The SiO2 ratio P of the obtained gas barrier laminate was determined in the same manner as in Example 1. The results are shown in Table 1.

[0216] (Example 8)

[0217] A gas barrier laminate was obtained in the same manner as in Example 1, except that a 100 μm thick unstretched polypropylene film (trade name "CPP100") as shown in Table 1 was used as the sealant layer. The SiO2 ratio P of the obtained gas barrier laminate was determined in the same manner as in Example 1. The results are shown in Table 1.

[0218] (Example 9)

[0219] A gas barrier laminate was obtained in the same manner as in Example 1, except that a solvent-free adhesive ("TSN-4864A / TSN-4864B3", manufactured by Toyo-Morton, Ltd.) was used as the adhesive and the sealant layer and gas barrier layer were bonded by a solvent-free lamination method. The SiO2 ratio P of the obtained gas barrier laminate was determined in the same manner as in Example 1. The results are shown in Table 1.

[0220] (Example 2 and Comparative Example 2)

[0221] A gas barrier film was produced in the same manner as in Example 1 except that the mass ratio of PVA and TEOS (calculated as SiO 2 ) in the coating liquid and the thickness a of the gas barrier layer were set to the values shown in Table 1.

[0222] Next, a 20 μm thick biaxially stretched polypropylene film (trade name “ME-1”, OPP, manufactured by Mitsui Chemicals Tohcello, Inc.) was adhered to the surface of the gas barrier layer of the gas barrier film by dry lamination via a two-component curable urethane adhesive as an outer layer.

[0223] Next, a 60 μm thick unstretched polypropylene film was attached as a sealant layer to the surface of the base material of the gas barrier film produced in Example 1 by dry lamination via a two-component curable urethane adhesive.

[0224] As described above, a gas barrier laminate having a thickness b shown in Table 1 and comprising a sealant layer, an adhesive layer, a substrate, an anchor coating layer, an inorganic oxide layer, a gas barrier layer, an adhesive layer, and an outer layer film was obtained. The SiO2 ratio P of the obtained gas barrier laminate was determined in the same manner as in Example 1. The results are shown in Table 1.

[0225] <Determination of Chlorine Amount>

[0226] The amounts of chlorine contained in the gas barrier laminates obtained in Examples and Comparative Examples were measured by combustion ion chromatography.

[0227] Specifically, first, the gas barrier layered product was cut in its thickness direction to obtain a sample, which was collected as a combustion sample, placed on a ceramic plate, and weighed.

[0228] Next, the combustion sample was combusted under the following condition 1 using an automatic sample combustion apparatus (AQF-2100H manufactured by Nittoseiko Analytech Co., Ltd.), and the generated gas was collected in 10 mL of an absorbing liquid.

[0229] After collection, the absorption liquid was adjusted to 15 mL with pure water to obtain an analytical sample. This analytical sample was quantitatively analyzed using ion chromatography (ICS-3000 manufactured by Thermo Fisher Scientific) under the following conditions 2 to measure the chlorine concentration (mass %) in the analytical sample. The results are shown in Table 1.

[0230] (Condition 1)

[0231] Inlet temperature: 900℃

[0232] Outlet temperature: 1000℃

[0233] Gas flow rate (O2): 400mL / min

[0234] Gas flow rate (Ar): 200 mL / min

[0235] Flow rate of Ar gas for humidification of the gas absorption unit when the generated gas is absorbed by the water absorption liquid: 100 mL / min

[0236] (Condition 2)

[0237] Separation column: DionexIon Pac AS18 (4mm×150mm)

[0238] Guard column: DionexIon Pac AG18 (4mm×30mm)

[0239] Elimination system (suppressor): Dionex ADRS-600 (external mode)

[0240] Detector: Conductivity detector

[0241] Eluent: KOH aqueous solution (using eluent generator EGCIII)

[0242] Eluent flow rate: 1.2mL / min

[0243] Analysis sample injection volume: 250 μL

[0244] <Evaluation of Gas Barrier Laminate>

[0245] (1) Evaluation of recyclability

[0246] The gas barrier laminates obtained in the Examples and Comparative Examples were cut into appropriate sizes and melt-extruded using a melt viscosity meter (Melt Indexer F-F01, manufactured by Toyo Seiki Seisaku-sho, Ltd.) at a temperature of 230°C and a pressure of 2.16 kgf according to JIS K 7210. The appearance of the resulting extrudates was then visually observed.

[0247] Then, the following evaluation grades were prepared based on the coloration state of the extrudate, and the recyclability was evaluated based on the evaluation grades. The results are shown in Table 2.

[0248] (Evaluation level)

[0249] ◎: Coloring not confirmed

[0250] ○: Slight coloring observed

[0251] ×: Severe coloration

[0252] The gas barrier layered products with evaluation ratings of “⊚” and “◯” were judged to be acceptable in terms of recyclability, and the gas barrier layered products with evaluation ratings of “×” were judged to be unacceptable in terms of recyclability.

[0253] (2) Melt flow rate (MFR)

[0254] The gas barrier laminates obtained in the Examples and Comparative Examples were cut into appropriate sizes and melt-extruded using a melt viscosity meter (Melt Indexer F-F01, manufactured by Toyo Seiki Seisaku-sho, Ltd.) at 230°C and 2.16 kgf according to JIS K 7210. The MFR (unit: g / 10 min) of the melt was then measured. The MFR was measured five times, and the average of the five measurements was calculated. The results are shown in Table 2.

[0255] (3) Gas barrier properties after high-temperature cooking

[0256] (Production of sealing body)

[0257] The gas barrier layered products obtained in the Examples and Comparative Examples were used to produce three-sided bags with openings. These bags were formed by folding the gas barrier layered products so that the unstretched polypropylene films faced each other and then heat-sealing the unstretched polypropylene films. Tap water (city water) was then poured through the opening and the opening of the three-sided bag was sealed to prepare a sealed bag.

[0258] (High temperature cooking treatment)

[0259] The sealed body obtained as described above was subjected to a high-temperature retort treatment at 130° C. for 60 minutes using a hot water storage retort.

[0260] (Determination of oxygen permeability)

[0261] A test sample of 297 mm in length and 210 mm in width was cut out from the gas barrier laminate of the sealed body after the high-temperature retorting treatment. The oxygen permeability (unit: cc / m2) of the test sample was measured using an oxygen permeability measuring apparatus (product name "OX-TRAN2 / 20", manufactured by MOCON) at a temperature of 30°C and a relative humidity of 70%. 2 ·day·atm). At this time, the measurement was carried out in accordance with JIS K-7126, B method (isobaric method) and ASTM3985-81. The results are shown in Table 2.

[0262] (4) Interlayer adhesion after high-temperature cooking

[0263] In order to evaluate the interlayer adhesion of the gas barrier laminate of the sealed body after high-temperature boiling treatment, a test sample of 100 mm in length and 15 mm in width (test width) was cut out from the gas barrier laminate of the sealed body after high-temperature boiling treatment. After removing water from the test sample, the lamination strength between the gas barrier layer and the sealant layer or the outer film (second polypropylene film) was measured. The measurement was carried out in accordance with JIS K6854 at a peeling speed of 300 mm / min and a peeling angle of T. The measured value is expressed in units of [N / 15mm]. The results are shown in Table 2. It should be noted that for test samples with a lamination strength of 2.0 N / 15 mm or more, the interlayer adhesion after high-temperature boiling treatment was judged to be acceptable; for test samples with a lamination strength of less than 2.0 N / 15 mm, the interlayer adhesion after high-temperature boiling treatment was judged to be unacceptable.

[0264] [Table 1]

[0265]

[0266] *P=mass ratio of TEOS×a / b

[0267] [Table 2]

[0268]

[0269] Industrial Applicability

[0270] The gas barrier laminate disclosed herein has excellent recyclability and can maintain excellent interlayer adhesion even after high-temperature retorting. Therefore, it can be used to produce excellent packaging containers. After use, the packaging containers can be reused as recyclable products, thereby contributing to environmental and waste issues.

[0271] Explanation of symbols

[0272] 1…substrate, 2…anchor coating layer, 3…inorganic oxide layer, 4…gas barrier layer, 10…gas barrier film, 20, 120, 220…gas barrier laminate, 30…packaging container, 40…packaging product, 21…sealing layer (second polypropylene film), 22…adhesive layer, 121…outer film (second polypropylene film), C…contents

Claims

1. A gas barrier laminate comprising: A gas barrier film having a gas barrier layer on at least one side of a substrate comprising a first polypropylene film; and at least one second polypropylene film laminated on the gas barrier film, The gas barrier layer is obtained using a gas barrier layer-forming composition containing a resin and a first silicon compound. The first silicon compound is at least one of a silicon alkoxy compound represented by the following general formula (1) and a hydrolyzate thereof, The chlorine content, as measured by combustion ion chromatography, is greater than 0.0008% by mass and less than 0.0080% by mass based on the total amount of the gas barrier laminate. Si(OR 1 )4···(1) In the above general formula (1), OR 1 represents a hydrolyzable group.

2. The gas barrier laminate according to claim 1, wherein The chlorine content, as measured by combustion ion chromatography, is 0.0010 mass % or more and 0.0060 mass % or less based on the total amount of the gas barrier laminate.

3. The gas barrier laminate according to claim 2, wherein The chlorine content, as measured by combustion ion chromatography, is 0.0010 mass % or more and 0.0050 mass % or less based on the total amount of the gas barrier laminate.

4. The gas barrier laminate according to claim 1, wherein in the gas barrier layer-forming composition, when the total mass of the resin and the first silicon compound is 100, the product of the mass ratio of the first silicon compound to the total mass and the ratio of the thickness of the gas barrier layer to the thickness of the gas barrier laminate is 0.35 or less.

5. The gas barrier laminate according to claim 1, wherein in the gas barrier layer-forming composition, when the total mass of the resin and the first silicon compound is 100, the product of the mass ratio of the first silicon compound to the total mass and the ratio of the thickness of the gas barrier layer to the thickness of the gas barrier laminate is greater than 0.

04. The gas barrier laminate according to claim 1 , wherein The gas barrier film further includes an inorganic oxide layer between the substrate and the gas barrier layer.

7. The gas barrier laminate according to claim 1, wherein The resin in the gas barrier layer-forming composition is a water-soluble polymer. The gas barrier layer-forming composition further contains a second silicon compound, which is at least one of a silane coupling agent represented by the following general formula (2) and a hydrolyzate thereof: (R 2 Si(OR 3 )3) n ···(2) In the above general formula (2), OR 3 Represents a hydrolyzable group, R 2 represents a monovalent organic group, and n is an integer of 1 or greater.

8. The gas barrier laminate according to claim 1, wherein The thickness of the gas barrier layer is 0.1 to 1.0 μm.

9. The gas barrier laminate according to claim 6, wherein The gas barrier film further includes an anchor coating layer between the substrate and the inorganic oxide layer.

10. The gas barrier laminate according to claim 1, wherein The second polypropylene film serves as a sealing layer. 11 . A packaging container obtained by using the gas barrier laminate according to claim 1 .

12. A packaged product comprising the packaging container according to claim 11 and contents accommodated in the packaging container.

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