Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
  • B65D81/34—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging foodstuffs or other articles intended to be cooked or heated within the package
  • B65D81/3446—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging foodstuffs or other articles intended to be cooked or heated within the package specially adapted to be heated by microwaves
  • B65D81/3461—Flexible containers, e.g. bags, pouches, envelopes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
  • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/34—Layered products comprising a layer of synthetic resin comprising polyamides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/02—Physical, chemical or physicochemical properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/02—Physical, chemical or physicochemical properties
  • B32B7/022—Mechanical properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/02—Physical, chemical or physicochemical properties
  • B32B7/027—Thermal properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/04—Interconnection of layers
  • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D33/00—Details of, or accessories for, sacks or bags
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
  • B65D65/38—Packaging materials of special type or form
  • B65D65/40—Applications of laminates for particular packaging purposes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D77/00—Packages formed by enclosing articles or materials in preformed containers, e.g. boxes, cartons, sacks or bags
  • B65D77/22—Details
  • B65D77/225—Pressure relief-valves incorporated in a container wall, e.g. valves comprising at least one elastic element
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2255/00—Coating on the layer surface
  • B32B2255/10—Coating on the layer surface on synthetic resin layer or on natural or synthetic rubber layer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2255/00—Coating on the layer surface
  • B32B2255/20—Inorganic coating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2255/00—Coating on the layer surface
  • B32B2255/26—Polymeric coating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2255/00—Coating on the layer surface
  • B32B2255/28—Multiple coating on one surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/514—Oriented
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2323/00—Polyalkenes
  • B32B2323/10—Polypropylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2439/00—Containers; Receptacles
  • B32B2439/40—Closed containers
  • B32B2439/46—Bags
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2439/00—Containers; Receptacles
  • B32B2439/70—Food packaging
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D75/00—Packages comprising articles or materials partially or wholly enclosed in strips, sheets, blanks, tubes or webs of flexible sheet material, e.g. in folded wrappers
  • B65D75/008—Standing pouches, i.e. "Standbeutel"

Definitions

• This disclosure relates to a laminate and a packaging bag.
• Polyester films are excellent in mechanical properties, chemical stability, heat resistance, and transparency, and are inexpensive. For this reason, polyester films have traditionally been used as substrates for constructing laminates used to produce packaging bags. Depending on the contents filled in the packaging bag, the packaging bag is required to have gas barrier properties such as oxygen barrier properties. To meet this requirement, an inorganic oxide layer containing alumina or silica is formed on the surface of the polyester film (see, for example, Patent Document 1). In recent years, substrates to replace polyester films have been sought.
• the present inventors have considered using a stretched substrate containing polypropylene as a main component, instead of a conventional polyester film, as the substrate constituting the laminate. Specifically, from the standpoint of recyclability and gas barrier properties, the present inventors have considered using a laminate comprising a barrier substrate comprising the above stretched substrate and an inorganic oxide layer, and a sealant layer containing polypropylene as a main component. As a result of their consideration, the present inventors have found that packaging bags made using such a laminate may not have sufficient gas barrier properties after retort treatment.
• One of the problems to be solved by this disclosure is to suppress the deterioration of the gas barrier properties after retort treatment of a packaging bag made using a laminate comprising a barrier substrate having an inorganic oxide layer and an oriented substrate containing polypropylene as a main component, and a sealant layer containing polypropylene as a main component.
• the laminate of the present disclosure comprises a first substrate, a first adhesive layer, a second substrate, a second adhesive layer, and a sealant layer in this order in the thickness direction
• the first substrate comprises an oriented substrate containing polypropylene as a main component
• the second substrate comprises an oriented substrate containing polypropylene as a main component
• at least one selected from the first substrate and the second substrate is a barrier substrate further comprising an inorganic oxide layer
• the sealant layer contains polypropylene as a main component
• the elastic modulus measured on a cross section of the first adhesive layer using an atomic force microscope (AFM) is 35.0 MPa or less
• the softening point measured on a cross section of the first adhesive layer by local thermal analysis using a thermal probe is 200°C or more and 330°C or less
• the thickness of the first adhesive layer is 1.0 ⁇ m or more.
• the present disclosure it is possible to suppress the deterioration of the gas barrier properties of a packaging bag produced using a laminate comprising a stretched substrate containing polypropylene as a main component, a barrier substrate comprising an inorganic oxide layer, and a sealant layer containing polypropylene as a main component, after retort treatment.
• FIG. 1 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 2 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 3 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 4 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 5 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 6 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 7 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 8 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 9 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 10 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 11 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 12 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 13 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 14 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 15 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 16 is a schematic cross-sectional view showing one embodiment of a laminate.
• FIG. 17 is a front view showing one embodiment of a packaging bag.
• FIG. 18 is a perspective view showing an embodiment of a packaging bag.
• FIG. 19 is a schematic diagram showing a method for measuring laminate strength.
• FIG. 20 is a diagram showing the measurement results of laminate strength.
• the numerical range of the parameter may be constructed by combining any one of the upper limit candidates and any one of the lower limit candidates.
• the numerical range of parameter B may be A1 or more and A4 or less, A1 or more and A5 or less, A1 or more and A6 or less, A2 or more and A4 or less, A2 or more and A5 or less, A2 or more and A6 or less, A3 or more and A4 or less, A3 or more and A5 or less, or A3 or more and A6 or less.
• the "main component" of a layer or substrate refers to a component whose content in the layer or substrate is greater than 50% by mass, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.
• each of the components e.g., polypropylene, ⁇ -olefin, resin material, additive, gas barrier resin, adhesive resin, inorganic oxide
• each of the components may be used alone or in combination of two or more types.
• the laminate of the present disclosure comprises a first substrate, a first adhesive layer, a second substrate, a second adhesive layer, and a sealant layer, in this order in the thickness direction (hereinafter also referred to as "in this order").
• the first substrate comprises a stretched substrate containing polypropylene as a main component.
• the second substrate comprises a stretched substrate containing polypropylene as a main component.
• the stretched substrate of the first substrate and the stretched substrate of the second substrate may be the same or different.
• At least one selected from the first substrate and the second substrate is a barrier substrate comprising the stretched substrate and an inorganic oxide layer.
• the stretched substrate containing polypropylene as a main component is also referred to as a "polypropylene stretched substrate”.
• the sealant layer contains polypropylene as a main component.
• the first substrate is an oriented polypropylene substrate
• the second substrate is a barrier substrate.
• the laminate comprises, in this order, an oriented polypropylene substrate, and optionally a printing layer, a first adhesive layer, a barrier substrate, a second adhesive layer, and a sealant layer.
• the barrier substrate is arranged so that the inorganic oxide layer faces the first adhesive layer, and the oriented polypropylene substrate faces the second adhesive layer. With such an arrangement, for example, deterioration of the inorganic oxide layer can be further suppressed.
• the first substrate is a barrier substrate
• the second substrate is an oriented polypropylene substrate. That is, the laminate comprises, in this order, a barrier substrate, an optional printing layer, a first adhesive layer, an oriented polypropylene substrate, a second adhesive layer, and a sealant layer.
• the barrier substrate is preferably arranged so that the inorganic oxide layer faces the first adhesive layer and the oriented polypropylene substrate faces outward.
• the laminate of the present disclosure exhibits excellent gas barrier properties (e.g., oxygen barrier properties and water vapor barrier properties, particularly oxygen barrier properties).
• a packaging bag made using the laminate of the present disclosure can suppress deterioration of gas barrier properties even after heat treatment such as retort treatment and boiling treatment. From the viewpoint of more adequate protection of the inorganic oxide layer during heat treatment and stable gas barrier properties, a laminate in which the first substrate is an oriented polypropylene substrate and the second substrate is a barrier substrate is preferred.
• 1 to 16 are schematic cross-sectional views showing one embodiment of a laminate according to the present disclosure.
• 1 includes, in this order, a stretched polypropylene substrate 10 as a first substrate, a first adhesive layer 40A, a barrier substrate 20 as a second substrate, a second adhesive layer 40B, and a sealant layer 30.
• the barrier substrate 20 includes a stretched polypropylene substrate 22 and an inorganic oxide layer 24.
• the barrier substrate 20 is disposed such that the stretched polypropylene substrate 22 faces the second adhesive layer 40B, and the inorganic oxide layer 24 faces the first adhesive layer 40A.
• FIG. 2 is similar to FIG. 1 except that the barrier substrate 20 includes a surface coat layer 23 between a stretched polypropylene substrate 22 and an inorganic oxide layer 24 .
• FIG. 3 is similar to FIG. 1 except that a stretched polypropylene substrate 22 includes a polypropylene layer 21 and a surface resin layer 26 .
• FIG. 4 is similar to FIG. 3 except that the stretched polypropylene substrate 22 includes an adhesive resin layer 27 between the polypropylene layer 21 and the surface resin layer 26 .
• FIG. 5 is similar to FIG. 1 except that the barrier substrate 20 comprises an oriented polypropylene substrate 22, an inorganic oxide layer 24, and a coating layer 25 in this order.
• FIG. 6 is similar to FIG.
• FIG. 7 is similar to FIG. 5 except that the stretched polypropylene substrate 22 includes a polypropylene layer 21 and a surface resin layer 26 .
• FIG. 8 is similar to FIG. 7 except that the stretched polypropylene substrate 22 includes an adhesive resin layer 27 between the polypropylene layer 21 and the surface resin layer 26 .
• the laminate 1 shown in FIG. 9 comprises, in this order, a barrier substrate 20 as a first substrate, a first adhesive layer 40A, an oriented polypropylene substrate 10 as a second substrate, a second adhesive layer 40B, and a sealant layer 30.
• the barrier substrate 20 comprises an oriented polypropylene substrate 22 and an inorganic oxide layer 24.
• the oriented polypropylene substrate 22 constitutes the outermost layer of the laminate 1, and the barrier substrate 20 is arranged so that the inorganic oxide layer 24 faces the first adhesive layer 40A.
• FIG. 10 is similar to FIG. 9 except that the barrier substrate 20 includes a surface coating layer 23 between a stretched polypropylene substrate 22 and an inorganic oxide layer 24 .
• FIG. 11 is similar to FIG. 9 except that a stretched polypropylene substrate 22 includes a polypropylene layer 21 and a surface resin layer 26 .
• FIG. 12 is similar to FIG. 11 except that the stretched polypropylene substrate 22 includes an adhesive resin layer 27 between the polypropylene layer 21 and the surface resin layer 26 .
• FIG. 13 is similar to FIG. 9 except that the barrier substrate 20 comprises an oriented polypropylene substrate 22, an inorganic oxide layer 24, and a coating layer 25 in this order.
• FIG. 14 is similar to FIG.
• FIG. 15 is similar to FIG. 13 except that the stretched polypropylene substrate 22 includes a polypropylene layer 21 and a surface resin layer 26 .
• FIG. 16 is similar to FIG. 15 except that the stretched polypropylene substrate 22 includes an adhesive resin layer 27 between the polypropylene layer 21 and the surface resin layer 26 .
• the polypropylene content relative to the total amount of resin material contained in the laminate of the present disclosure is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 88% by mass or more, and particularly preferably 90% by mass or more.
• a packaging bag produced using such a laminate has, for example, excellent recyclability.
• the upper limit of the polypropylene content relative to the total amount of resin material contained in the laminate of the present disclosure is not particularly limited, but may be, for example, 99% by mass, 98% by mass, 97% by mass, 96% by mass, 95% by mass, or 94% by mass.
• the oriented polypropylene substrate contains polypropylene as a major component.
• the polypropylene may be any of a homopolymer, a random copolymer, and a block copolymer, and may be a mixture of two or more selected from these.
• biomass-derived polypropylene and/or recycled polypropylene may be used as the polypropylene.
• a propylene homopolymer is a polymer of only propylene.
• a propylene random copolymer is a random copolymer of propylene and an ⁇ -olefin other than propylene.
• a propylene block copolymer is a copolymer having a polymer block of propylene and a polymer block of at least an ⁇ -olefin other than propylene.
• the polymer block of at least an ⁇ -olefin other than propylene may be a polymer block of propylene and an ⁇ -olefin other than propylene.
• ⁇ -olefins examples include ⁇ -olefins other than propylene that have 2 to 20 carbon atoms, specifically ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene.
• random copolymers are preferred from the viewpoint of transparency, homopolymers are preferred when emphasis is placed on the rigidity and heat resistance of the packaging bag, and block copolymers are preferred when emphasis is placed on the impact resistance of the packaging bag.
• the melt flow rate (MFR) of polypropylene is preferably 0.1 g/10 min or more, more preferably 0.3 g/10 min or more, and is preferably 50 g/10 min or less, more preferably 30 g/10 min or less, for example, 0.1 g/10 min or more and 50 g/10 min or less.
• the MFR of polypropylene is measured in accordance with JIS K7210-1:2014, Method A, at a temperature of 230°C and a load of 2.16 kg.
• the polypropylene content in the polypropylene oriented substrate is preferably greater than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 85% by mass or more, 90% by mass or more, or 95% by mass or more.
• the stretched polypropylene substrate may contain a resin material other than polypropylene, such as, for example, a polyolefin other than polypropylene, such as polyethylene, an acrylic resin, a vinyl resin, a cellulose resin, a polyamide, a polyester, or an ionomer resin.
• the stretched polypropylene substrate may contain additives, such as crosslinkers, antioxidants, antiblocking agents, lubricants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.
• the stretched polypropylene substrate is a polypropylene substrate that has been subjected to a stretching treatment.
• a laminate including the stretched polypropylene substrate is excellent in, for example, heat resistance, impact resistance, water resistance, and dimensional stability, and is suitable as a packaging material for forming a packaging bag that is to be subjected to, for example, a retort treatment or a boiling treatment.
• the stretching process may be uniaxial stretching or biaxial stretching.
• the stretching ratio in the case of stretching in the machine direction (flow direction of the substrate, MD direction) is preferably 2 times or more, more preferably 3 times or more, and even more preferably 3.5 times or more, and also preferably 15 times or less, more preferably 8 times or less, and even more preferably 7 times or less.
• the stretching ratio in the case of stretching in the width direction is preferably 4 times or more, more preferably 5 times or more, and even more preferably 6 times or more, and also preferably 20 times or less, more preferably 17 times or less, and even more preferably 15 times or less.
• the stretching ratio is a certain level or less.
• the stretching ratio in the MD direction is smaller than the stretching ratio in the TD direction.
• the oriented polypropylene substrate is, for example, a biaxially oriented substrate.
• the oriented polypropylene substrate may be surface-treated. This can improve the adhesion between the oriented polypropylene substrate and other layers, for example.
• surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and/or nitrogen gas, and glow discharge treatment; and chemical treatments such as oxidation treatment using chemicals.
• An easy-adhesion layer may be provided on the surface of the stretched polypropylene substrate.
• the oriented polypropylene substrate may have a single layer structure or a multi-layer structure.
• the thickness of the polypropylene stretched substrate is preferably 10 ⁇ m or more, more preferably 15 ⁇ m or more, and also preferably 100 ⁇ m or less, more preferably 50 ⁇ m or less, for example, 10 ⁇ m or more and 100 ⁇ m or less.
• a laminate having a stretched substrate with a thickness equal to or greater than the lower limit has, for example, excellent strength and heat resistance.
• a laminate having a stretched substrate with a thickness equal to or less than the upper limit has, for example, excellent processability.
• the thickness of the substrate and each layer is measured as follows.
• the laminate is embedded in an embedding resin to prepare a block, and the block is cut at room temperature (25°C) using a commercially available rotary microtome to prepare a cross section of the laminate.
• the cross section is obtained by cutting the laminate in the thickness direction perpendicular to the main surface. Finishing is performed with a diamond knife.
• the thickness of the substrate and each layer is the arithmetic average value of the thicknesses measured at five points by observing the cross section using a scanning electron microscope (SEM, Hitachi, Ltd., SU8000).
• the barrier substrate comprises a stretched polypropylene substrate and an inorganic oxide layer.
• the barrier substrate comprises, for example, a stretched polypropylene substrate and an inorganic oxide layer provided on one surface of the stretched substrate.
• the barrier substrate may comprise a surface coating layer between the stretched polypropylene substrate and the inorganic oxide layer.
• the barrier substrate may comprise a coating layer on the inorganic oxide layer.
• the barrier substrate may have transparency.
• polypropylene oriented substrate examples include the oriented polypropylene substrates described in the section ⁇ oriented polypropylene substrate>.
• the oriented polypropylene substrate of the first substrate and the oriented polypropylene substrate of the second substrate may be the same or different.
• the stretched polypropylene substrate provided in the barrier substrate may be, for example, a stretched substrate of another embodiment that includes a polypropylene layer, an optional adhesive resin layer, and a surface resin layer described below, in this order.
• the barrier substrate includes a stretched substrate of another embodiment and an inorganic oxide layer provided on the surface resin layer of the stretched substrate.
• the barrier substrate includes a polypropylene layer, an optional adhesive resin layer, a surface resin layer, and an inorganic oxide layer, in this order.
• the stretched substrate of another embodiment is a coextruded stretched resin film.
• the coextruded stretched resin film can be produced, for example, by forming a film using a T-die method or an inflation method to obtain a laminated film, and then stretching the laminated film.
• the stretching treatment of the stretched substrate may be uniaxial stretching or biaxial stretching.
• the stretching ratio in the MD direction is preferably 2 times or more, more preferably 3 times or more, and even more preferably 3.5 times or more, and is preferably 15 times or less, more preferably 8 times or less, and even more preferably 7 times or less.
• the stretching ratio in the TD direction is preferably 4 times or more, more preferably 5 times or more, and even more preferably 6 times or more, and is preferably 20 times or less, more preferably 17 times or less, and even more preferably 15 times or less.
• the stretching ratio in the MD direction is preferably smaller than the stretching ratio in the TD direction.
• the barrier substrate may include a surface coating layer containing a resin material having a polar group between the stretched polypropylene substrate and the inorganic oxide layer.
• a barrier substrate has excellent adhesion to the inorganic oxide layer and also has excellent gas barrier properties.
• Such a barrier substrate includes, in this order, a stretched polypropylene substrate, a surface coating layer, and an inorganic oxide layer.
• the polar group refers to a group containing one or more heteroatoms, and examples thereof include ester groups, epoxy groups, hydroxyl groups, amino groups, amide groups, urethane groups, carboxy groups, carbonyl groups, carboxylic anhydride groups, sulfo groups, thiol groups, and halogen groups.
• carboxy groups, carbonyl groups, ester groups, hydroxyl groups, amino groups, amide groups, and urethane groups are preferred, and carboxy groups, hydroxyl groups, amide groups, and urethane groups are more preferred.
• resin materials having polar groups include ethylene-vinyl alcohol copolymers (EVOH), polyvinyl alcohol (PVA), polyester, polyethyleneimine, hydroxyl-containing acrylic resins, polyamides such as nylon 6, nylon 6,6, MXD nylon and amorphous nylon, and polyurethane.
• EVOH ethylene-vinyl alcohol copolymers
• PVA polyvinyl alcohol
• polyester polyethyleneimine
• hydroxyl-containing acrylic resins polyamides
• polyamides such as nylon 6, nylon 6,6, MXD nylon and amorphous nylon
• polyurethane polyurethane.
• ethylene-vinyl alcohol copolymers, polyvinyl alcohol, hydroxyl-containing acrylic resins, polyamides and polyurethanes are more preferred.
• the surface coating layer can be formed, for example, using a water-based emulsion or a solvent-based emulsion.
• water-based emulsions include polyamide-based emulsions, polyethylene-based emulsions, and polyurethane-based emulsions.
• solvent-based emulsions include acrylic resin-based emulsions and polyester-based emulsions.
• the content of the resin material having a polar group in the surface coating layer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.
• the surface coating layer may contain the above-mentioned resin materials other than the resin material having a polar group.
• the surface coating layer may contain the above-mentioned additives.
• the ratio of the thickness of the surface coat layer to the total thickness of the polypropylene oriented substrate and the surface coat layer is preferably 0.08% or more, more preferably 0.2% or more, even more preferably 1% or more, and also preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, even more preferably 5% or less, for example, 0.08% or more and 20% or less.
• the thickness of the surface coat layer is preferably 0.02 ⁇ m or more, more preferably 0.05 ⁇ m or more, even more preferably 0.1 ⁇ m or more, even more preferably 0.2 ⁇ m or more, and also preferably 10 ⁇ m or less, more preferably 5 ⁇ m or less, for example, 0.02 ⁇ m or more and 10 ⁇ m or less.
• the adhesion of the inorganic oxide layer can be improved, the deterioration of the gas barrier property can be suppressed, and the laminate strength of the laminate can be improved.
• the above ratio or thickness is equal to or less than the upper limit, for example, the processability of the barrier substrate and the recyclability of the laminate can be improved.
• a polypropylene substrate is obtained by forming a film from polypropylene or a resin composition containing polypropylene using a T-die method or an inflation method, and then the substrate is stretched. A coating liquid for forming a surface coating layer is applied to the stretched substrate, and the substrate is dried, thereby producing a polypropylene stretched substrate and a resin substrate having a surface coating layer.
• the polypropylene layer contains polypropylene as a main component.
• the details of polypropylene are as described above, and will not be described in this section.
• the content of polypropylene in the polypropylene layer is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 85% by mass or more, 90% by mass or more, or 95% by mass or more.
• the polypropylene layer may contain the above-mentioned resin materials other than polypropylene.
• the polypropylene layer may contain the additives described above.
• the polypropylene layer may have a single-layer structure or a multi-layer structure.
• the thickness of the polypropylene layer is preferably 10 ⁇ m or more, more preferably 15 ⁇ m or more, and is preferably 100 ⁇ m or less, more preferably 50 ⁇ m or less, for example, 10 ⁇ m or more and 100 ⁇ m or less.
• the surface resin layer contains a resin material having a melting point of 180° C. or higher (hereinafter also referred to as a “high melting point resin material”).
• a resin material having a melting point of 180° C. or higher hereinafter also referred to as a “high melting point resin material”.
• the adhesive resin layer when the stretched substrate of another aspect has an adhesive resin layer between the polypropylene layer and the surface resin layer, the adhesive resin layer may be provided on the polypropylene layer, and the surface resin layer may be provided on the adhesive resin layer, i.e., the adhesive resin layer may be adjacent to the polypropylene layer, and the surface resin layer may be adjacent to the adhesive resin layer.
• the melting point of the high melting point resin material is preferably 185°C or higher, more preferably 190°C or higher, and even more preferably 205°C or higher. If the melting point is equal to or higher than the lower limit, for example, the adhesion of the inorganic oxide layer can be improved, the deterioration of the gas barrier property can be suppressed, and the laminate strength of the laminate can be improved.
• the melting point of the high melting point resin material is preferably 265°C or lower, more preferably 260°C or lower, and even more preferably 250°C or lower. This can improve, for example, the film-forming properties of the stretched substrate.
• the melting point of high melting point resin materials and the like is measured in accordance with JIS K7121:2012 (Method for measuring transition temperature of plastics). Specifically, a differential scanning calorimetry (DSC) device is used to measure the DSC curve at a heating rate of 10°C/min, and the melting peak temperature is determined as the melting point.
• DSC differential scanning calorimetry
• the high melting point resin material contained in the surface resin layer has a melting point TA
• the polypropylene contained in the polypropylene layer has a melting point TB
• the difference between the melting points TA and TB is preferably 20° C. or more.
• the difference between the melting points TA and TB is preferably 80° C. or less, and more preferably 60° C. or less.
• the difference between the melting point TA and the melting point TB is equal to or greater than the lower limit, the adhesion between the surface resin layer and the inorganic oxide layer can be improved, the gas barrier property can be improved, and the laminate strength of the packaging bag can be improved.
• the difference between the melting point TA and the melting point TB is equal to or less than the upper limit, the film formability of the stretched polypropylene substrate can be further improved.
• the high melting point resin material preferably has a polar group.
• a polar group refers to a group containing one or more heteroatoms, and examples thereof include ester groups, epoxy groups, hydroxyl groups, amino groups, amide groups, urethane groups, carboxy groups, carbonyl groups, carboxylic anhydride groups, sulfo groups, thiol groups, and halogen groups. Among these, hydroxyl groups, ester groups, amino groups, amide groups, carboxy groups, and carbonyl groups are preferred, and amide groups are more preferred.
• the high melting point resin material may have a melting point of 180° C. or higher, and examples of the high melting point resin material include polyolefin, vinyl resin, acrylic resin, polyamide, polyimide, polyester, cellulose resin, and ionomer resin.
• a resin material having a melting point of 180° C. or higher and a polar group is preferable, and ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyester, and polyamides such as nylon 6, nylon 6,6, MXD nylon, and amorphous nylon are more preferable.
• the high melting point resin material is preferably polyamide.
• polyamide As the high melting point resin material, the deterioration of the gas barrier property can be suppressed even after the laminate is bent, and the heat resistance of the laminate can be improved. In addition, the deterioration of the gas barrier property can be suppressed even after the laminate is subjected to the retort treatment and boiling treatment described below.
• Nylon 6 is more preferable as the high melting point resin material.
• the content of the high melting point resin material in the surface resin layer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.
• the surface resin layer may contain the above-mentioned resin materials other than the high melting point resin material.
• the surface resin layer may contain the above-mentioned additives.
• the surface resin layer may be subjected to the above-mentioned surface treatment.
• the ratio of the thickness of the surface resin layer to the total thickness of the stretched substrate of another embodiment having a polypropylene layer and a surface resin layer is preferably 1% or more, more preferably 1.5% or more, and also preferably 10% or less, more preferably 5% or less, for example 1% or more and 10% or less.
• the thickness of the surface resin layer is preferably 0.1 ⁇ m or more, more preferably 0.2 ⁇ m or more, and also preferably 5 ⁇ m or less, more preferably 4 ⁇ m or less, for example 0.1 ⁇ m or more and 5 ⁇ m or less.
• the adhesion of the inorganic oxide layer can be improved, the deterioration of the gas barrier property can be suppressed, and the laminate strength of the laminate can be improved.
• the above ratio or thickness is equal to or less than the upper limit, for example, the film-forming property and processability of the stretched substrate of another embodiment, and the recyclability of the laminate can be improved.
• the stretched substrate of another embodiment may have an adhesive resin layer between the polypropylene layer and the surface resin layer. This can improve the adhesion between these layers.
• the thickness of the adhesive resin layer is, for example, 1 ⁇ m or more and 15 ⁇ m or less. By making the thickness of the adhesive resin layer equal to or more than the lower limit, the adhesion between the polypropylene layer and the surface resin layer can be further improved. By making the thickness of the adhesive resin layer equal to or less than the upper limit, the processability of the barrier substrate can be improved.
• the adhesive resin layer can be formed, for example, by an adhesive resin. Examples of adhesive resins include polyether, polyester, polyurethane, silicone resin, epoxy resin, vinyl resin, phenol resin, polyolefin, and acid-modified polyolefin.
• polyolefin and its acid-modified polyolefin are preferred from the viewpoint of recyclability of the laminate, and polypropylene and its acid-modified polyolefin are more preferred.
• polypropylene used for the adhesive resin layer commercially available products can be used, for example, the Admer series manufactured by Mitsui Chemicals, Inc. can be used.
• the barrier substrate comprises an inorganic oxide layer.
• the inorganic oxide layer contains one or more inorganic oxides, for example, a vapor-deposited film of an inorganic oxide.
• a laminate comprising the barrier substrate has excellent gas barrier properties, specifically, oxygen barrier properties and water vapor barrier properties.
• a packaging bag produced using such a laminate can suppress oxidation deterioration of the contents filled in the packaging bag, and suppress the mass loss of the contents.
• the barrier substrate may, for example, comprise an inorganic oxide layer on a surface coat layer, or may comprise an inorganic oxide layer on a surface resin layer.
• inorganic oxides include aluminum oxide (alumina), silicon oxide (silica), magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, barium oxide, and silicon carbide oxide (carbon-containing silicon oxide).
• aluminum oxide alumina
• silicon oxide silicon oxide
• magnesium oxide magnesium oxide
• calcium oxide zirconium oxide
• titanium oxide titanium oxide
• boron oxide hafnium oxide
• barium oxide silicon carbide oxide
• silicon carbide oxide carbon-containing silicon oxide
• silica is more preferable as the inorganic oxide because no aging treatment is required after the formation of the inorganic oxide layer.
• carbon-containing silicon oxide is more preferable as the inorganic oxide because it can suppress the deterioration of the gas barrier property even when the laminate is bent.
• the thickness of the inorganic oxide layer is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, and is preferably 150 nm or less, more preferably 60 nm or less, even more preferably 40 nm or less, for example, 1 nm or more and 150 nm or less.
• a laminate having an inorganic oxide layer whose thickness is equal to or greater than the lower limit has, for example, excellent oxygen barrier properties and water vapor barrier properties.
• a laminate having an inorganic oxide layer whose thickness is equal to or less than the upper limit can, for example, suppress the occurrence of cracks in the inorganic oxide layer, and has excellent recyclability.
• the surface of the inorganic oxide layer may be subjected to the above-mentioned surface treatment.
• Methods for forming inorganic oxide layers, particularly inorganic oxide vapor deposition films include, for example, physical vapor deposition methods (PVD methods) such as vacuum deposition, sputtering, and ion plating, as well as chemical vapor deposition methods (CVD methods) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.
• PVD methods physical vapor deposition methods
• CVD methods chemical vapor deposition methods
• plasma chemical vapor deposition thermal chemical vapor deposition
• photochemical vapor deposition photochemical vapor deposition
• the inorganic oxide layer may be a single layer formed by a single deposition process, or may be a multilayer formed by multiple deposition processes.
• each layer may be composed of the same inorganic oxide or different inorganic oxides.
• Each layer may be formed by the same method or different methods.
• the inorganic oxide layer is preferably a vapor deposition film formed by a CVD method, and more preferably a carbon-containing silicon oxide vapor deposition film formed by a CVD method.
• a laminate including such an inorganic oxide layer has, for example, excellent bending resistance.
• the carbon-containing silicon oxide vapor deposition film contains silicon, oxygen and carbon.
• the carbon ratio C is preferably 3% or more, more preferably 5% or more, even more preferably 10% or more, and is preferably 50% or less, more preferably 40% or less, even more preferably 35% or less, for example, 3% or more and 50% or less, relative to 100% in total of the three elements silicon, oxygen, and carbon.
• the ratio of each element is on a molar basis.
• the silicon ratio Si is preferably 1% or more, more preferably 3% or more, and even more preferably 8% or more, and is preferably 45% or less, more preferably 38% or less, and even more preferably 33% or less, for example 1% or more and 45% or less, relative to 100% of the total of the three elements silicon, oxygen, and carbon.
• the oxygen ratio O is preferably 10% or more, more preferably 20% or more, and even more preferably 25% or more, and is preferably 70% or less, more preferably 65% or less, and even more preferably 60% or less, for example 10% or more and 70% or less, relative to 100% of the total of the three elements silicon, oxygen, and carbon.
• the oxygen percentage O is preferably higher than the carbon percentage C, and the silicon percentage Si is preferably lower than the carbon percentage C.
• the oxygen percentage O is preferably higher than the silicon percentage Si, that is, the percentages are preferably in the order of O, C, and Si. This makes it possible to further suppress the deterioration of the gas barrier properties, for example, even when the laminate is bent.
• the percentages C, Si, and O in the carbon-containing silicon oxide vapor deposition film are measured by narrow scan analysis using X-ray photoelectron spectroscopy (XPS) under the following measurement conditions.
• XPS X-ray photoelectron spectroscopy
• the barrier substrate may further include a coating layer on the inorganic oxide layer. That is, the barrier substrate may further include a coating layer on the surface of the inorganic oxide layer opposite to the surface facing the stretched polypropylene substrate.
• a laminate including such a barrier substrate has, for example, excellent oxygen barrier properties and water vapor barrier properties.
• the coating layer may be adjacent to the first adhesive layer or the second adhesive layer.
• the coating layer contains a resin component.
• the resin component include polyolefins such as polyethylene, polypropylene, polybutene, and polymethylpentene, vinyl resins, acrylic resins, polyesters, urethane resins, melamine resins, and epoxy resins.
• the content of the resin component in the coating layer is preferably more than 50% by mass, more preferably 75% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, for example, more than 50% by mass and 95% by mass or less.
• the coating layer may contain the above-mentioned additives.
• the thickness of the coating layer is preferably 0.01 ⁇ m or more, more preferably 0.05 ⁇ m or more, even more preferably 0.1 ⁇ m or more, and is preferably 5 ⁇ m or less, more preferably 3 ⁇ m or less, even more preferably 1 ⁇ m or less, for example, 0.01 ⁇ m or more and 5 ⁇ m or less.
• Such a coating layer has, for example, excellent scratch resistance.
• the coating layer can be formed, for example, by applying a coating liquid for the coating layer to the surface of the inorganic oxide layer and drying it.
• the coating liquid for the coating layer can be prepared, for example, by mixing the above-mentioned resin components and, if necessary, additives and a solvent. Details of these components are as described above.
• Methods for applying the coating liquid for the coating layer include known coating methods.
• Methods for drying the applied coating liquid for the coating layer include, for example, hot air drying, heat roll drying, and methods that apply heat such as infrared irradiation.
• the drying temperature may be 50°C or higher, or 150°C or lower.
• the coating layer may be a barrier coat layer containing a gas barrier resin.
• gas barrier resin include ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyacrylonitrile, polyester, polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide, polyurethane, and acrylic resin.
• polyvinyl alcohol is preferred from the viewpoints of oxygen barrier property and water vapor barrier property.
• polyvinyl alcohol in the barrier coat layer the occurrence of cracks in the inorganic oxide layer can be effectively prevented.
• the content of the gas barrier resin in the barrier coat layer is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and still more preferably 75% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, for example, 50% by mass or more and 95% by mass or less.
• a barrier coat layer has, for example, excellent gas barrier properties.
• the barrier coat layer may contain the above-mentioned additives.
• the thickness of the barrier coat layer containing the gas barrier resin is preferably 0.01 ⁇ m or more, more preferably 0.1 ⁇ m or more, and also preferably 10 ⁇ m or less, more preferably 5 ⁇ m or less, for example, 0.01 ⁇ m or more and 10 ⁇ m or less.
• a barrier substrate having a barrier coat layer whose thickness is equal to or greater than the lower limit has, for example, excellent gas barrier properties.
• a barrier substrate having a barrier coat layer whose thickness is equal to or less than the upper limit can improve, for example, the processability and recyclability of the laminate. Furthermore, so long as the thickness of the barrier coat layer is within the above range, the recyclability is not impaired even if the gas barrier resin is a resin material other than polypropylene.
• the barrier coat layer can be formed, for example, by dissolving or dispersing a material such as a gas barrier resin in water or an appropriate organic solvent, applying the resulting coating liquid to the surface of the inorganic oxide layer, and drying it.
• the barrier coat layer can also be formed, for example, by applying a commercially available barrier coating agent and drying it.
• the coating layer may be a gas barrier coating film formed by polycondensing a composition containing a metal alkoxide and a water-soluble polymer by the sol-gel method in the presence of a sol-gel catalyst, water, an organic solvent, and the like.
• a barrier substrate having a gas barrier coating film on an inorganic oxide layer has, for example, excellent gas barrier properties.
• the gas barrier coating film contains a hydrolysis polycondensate in which the metal alkoxide and the like are hydrolyzed and polycondensed by the sol-gel method.
• the metal alkoxide is represented, for example, by the formula (1).
• R 1 n M (OR 2 ) m (1)
• R 1 and R 2 each independently represent an organic group having 1 to 8 carbon atoms
• M represents a metal atom
• n represents an integer of 0 or more
• m represents an integer of 1 or more
• n+m represents the atomic valence of M.
• Examples of the organic group in R 1 and R 2 include alkyl groups having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, an n-hexyl group, and an n-octyl group.
• the metal atom M is, for example, silicon, zirconium, titanium, or aluminum.
• Examples of the metal alkoxide include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.
• water-soluble polymers examples include hydroxyl group-containing polymers such as polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Depending on the desired physical properties such as oxygen barrier properties, water vapor barrier properties, water resistance, and weather resistance, either polyvinyl alcohol or ethylene-vinyl alcohol copolymer may be used, or both may be used in combination. Also, a gas barrier coating film obtained using polyvinyl alcohol and a gas barrier coating film obtained using ethylene-vinyl alcohol copolymer may be laminated. The amount of water-soluble polymer used is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and preferably 500 parts by mass or less, relative to 100 parts by mass of metal alkoxide.
• the oxygen barrier properties and water vapor barrier properties of the laminate can be further improved.
• the content of the water-soluble polymer in the gas barrier coating film can be set to the upper limit or less.
• a silane coupling agent may be used together with the metal alkoxide.
• a known organoalkoxysilane containing an organic reactive group can be used, and organoalkoxysilanes having an epoxy group are preferred, such as ⁇ -glycidoxypropyltrimethoxysilane, ⁇ -glycidoxypropylmethyldiethoxysilane, and ⁇ -(3,4-epoxycyclohexyl)ethyltrimethoxysilane.
• the amount of the silane coupling agent used is preferably 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the metal alkoxide.
• the ratio of the metal alkoxide to the water-soluble polymer is, on a mass basis, preferably 4.5 or less, more preferably 3.5 or less, and also preferably 1.0 or more, more preferably 1.7 or more, for example, 1.0 or more and 4.5 or less.
• the ratio of the metal alkoxide to the water-soluble polymer By setting the ratio of the metal alkoxide to the water-soluble polymer to be equal to or greater than the lower limit, the heat resistance of the laminate can be improved, and the deterioration of the gas barrier properties of the laminate can be suppressed even after the laminate is subjected to retort treatment and boiling treatment.
• the above ratio is a solid content ratio.
• the ratio of silicon atoms to carbon atoms (Si/C) measured by X-ray photoelectron spectroscopy (XPS) is preferably 1.60 or less, more preferably 1.35 or less, and is preferably 0.50 or more, more preferably 0.90 or more.
• the ratio of silicon atoms to carbon atoms By setting the ratio of silicon atoms to carbon atoms to the lower limit or more, the heat resistance of the laminate can be improved, and the deterioration of the gas barrier properties of the laminate can be suppressed even after the laminate is subjected to retort treatment and boiling treatment.
• the above range of the ratio of silicon atoms to carbon atoms can be achieved by appropriately adjusting the ratio of the metal alkoxide to the water-soluble polymer. In this specification, the ratio of silicon atoms to carbon atoms is based on moles.
• XPS X-ray photoelectron spectroscopy
• the gas barrier composition may contain water in an amount of preferably 0.1 mol or more, more preferably 0.5 mol or more, even more preferably 0.8 mol or more, and preferably 100 mol or less, more preferably 60 mol or less, even more preferably 2 mol or less, per mol of metal alkoxide.
• water content By setting the water content to the lower limit or more, for example, the oxygen barrier property and water vapor barrier property of the laminate can be improved.
• the hydrolysis reaction can be carried out quickly.
• the gas barrier composition may contain an organic solvent.
• organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and n-butyl alcohol.
• the sol-gel process catalyst is preferably an acid or an amine compound.
• the acid include mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid; and organic acids such as acetic acid and tartaric acid.
• the amount of the acid used is preferably 0.001 mol or more and 0.05 mol or less per mol of the total amount of the metal alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent.
• the amount of the acid used equal to or more than the lower limit, the catalytic effect can be improved.
• the amount of the acid used equal to or less than the upper limit, the thickness of the gas barrier coating film formed can be made uniform.
• a tertiary amine that is substantially insoluble in water and soluble in an organic solvent is suitable, such as N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine.
• N,N-dimethylbenzylamine is preferred.
• the amount of the amine compound used is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and also preferably 1.0 parts by mass or less, more preferably 0.3 parts by mass or less, based on 100 parts by mass of the total amount of the metal alkoxide and the silane coupling agent.By making the amount of the amine compound used to be the lower limit or more, the catalytic effect can be improved.By making the amount of the amine compound used to be the upper limit or less, the thickness of the gas barrier coating film formed can be made uniform.
• Methods for applying the gas barrier composition include, for example, application means such as roll coating using a gravure roll coater, spray coating, spin coating, dipping, brush coating, bar coating, and applicator.
• a gas barrier composition is prepared by mixing a metal alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and, if necessary, a silane coupling agent.
• a polycondensation reaction gradually proceeds.
• the composition is applied on an inorganic oxide layer by a conventional method and dried. This drying causes the polycondensation of the metal alkoxide and the water-soluble polymer (and the silane coupling agent if the composition contains a silane coupling agent) to proceed further, forming a composite polymer layer.
• the above operation may be repeated to laminate a plurality of composite polymer layers.
• the applied composition is heated at a temperature of preferably 20° C. or higher, more preferably 50° C. or higher, and even more preferably 70° C. or higher, and also preferably 250° C. or lower, more preferably 220° C. or lower, even more preferably 150° C. or lower, even more preferably 120° C. or lower, and particularly preferably 100° C. or lower, for 1 second to 10 minutes.
• a temperature of preferably 20° C. or higher more preferably 50° C. or higher, and even more preferably 70° C. or higher, and also preferably 250° C. or lower, more preferably 220° C. or lower, even more preferably 150° C. or lower, even more preferably 120° C. or lower, and particularly preferably 100° C. or lower, for 1 second to 10 minutes.
• This allows the formation of a gas barrier coating film.
• the thickness of the gas barrier coating film is preferably 0.01 ⁇ m or more, more preferably 0.1 ⁇ m or more, and is also preferably 100 ⁇ m or less, more preferably 10 ⁇ m or less, even more preferably 2 ⁇ m or less, even more preferably 1 ⁇ m or less, and particularly preferably 0.5 ⁇ m or less, for example, 0.01 ⁇ m or more and 100 ⁇ m or less. This makes it possible, for example, to suppress a decrease in gas barrier properties, suppress the occurrence of cracks in the inorganic oxide layer, and improve the recyclability of the packaging bag.
• the laminate of the present disclosure may include a printed layer on the surface of a substrate such as a first substrate and a second substrate.
• the image formed on the printed layer is not particularly limited, and may be a character, a pattern, a symbol, or a combination thereof.
• the printed layer may be formed using an ink derived from biomass. This can further reduce the environmental load.
• Examples of methods for forming the printed layer include conventionally known printing methods such as gravure printing, offset printing, and flexographic printing. Among these, flexographic printing is preferred from the viewpoint of reducing the environmental load.
• the thickness of the printing layer is, for example, not less than 0.5 ⁇ m and not more than 3 ⁇ m.
• the laminate of the present disclosure includes a sealant layer.
• the sealant layer contains polypropylene as a main component.
• the sealant layer contains the same type of resin material as the oriented polypropylene substrate, i.e., polypropylene as a main component. This allows the laminate to be made into a mono-material. In other words, after collecting used packaging bags, there is no need to separate the substrate and the sealant layer, improving the recyclability of the packaging bags.
• the polypropylene content in the sealant layer is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 85% by mass or more, 90% by mass or more, or 95% by mass or more.
• a laminate having such a sealant layer has, for example, excellent recyclability.
• polypropylene examples include propylene homopolymers, propylene random copolymers such as propylene- ⁇ -olefin random copolymers, and propylene block copolymers such as propylene- ⁇ -olefin block copolymers. Details of the ⁇ -olefins are as described above. From the viewpoint of heat sealability, the density of the polypropylene is, for example, 0.88 g/cm 3 or more and 0.92 g/cm 3 or less. The density is measured in accordance with JIS K7112:1999 D method (density gradient tube method, 23° C.). From the viewpoint of reducing the environmental load, biomass-derived polypropylene and/or recycled polypropylene may be used.
• the sealant layer may contain the above-mentioned additives.
• the sealant layer may have a single-layer structure or a multi-layer structure.
• the thickness of the sealant layer is preferably 10 ⁇ m or more, more preferably 20 ⁇ m or more, and also preferably 200 ⁇ m or less, more preferably 150 ⁇ m or less, for example 10 ⁇ m or more and 200 ⁇ m or less.
• a laminate having a sealant layer whose thickness is equal to or greater than the lower limit has, for example, excellent seal strength.
• a laminate having a sealant layer whose thickness is equal to or less than the upper limit has, for example, excellent processability.
• the thickness of the sealant layer is preferably 30 ⁇ m or more, and also preferably 100 ⁇ m or less.
• the sealant layer is preferably an unstretched polypropylene film, and the unstretched polypropylene film can be produced by utilizing, for example, a cast method, a T-die method, an inflation method, or the like.
• the sealant layer may be subjected to the above-mentioned surface treatment.
• the laminate of the present disclosure includes a first adhesive layer between a first substrate and a second substrate.
• the laminate of the present disclosure includes a second adhesive layer between the second substrate and a sealant layer.
• Such a laminate has, for example, excellent lamination strength between the first substrate and the second substrate and between the second substrate and the sealant layer.
• the elastic modulus measured by atomic force microscope (AFM) for the cross section of the first adhesive layer is 35.0 MPa or less, preferably 33.0 MPa or less, more preferably 30.0 MPa or less, even more preferably 28.0 MPa or less, and particularly preferably 26.0 MPa or less.
• a packaging bag made using a laminate having a first adhesive layer with an elastic modulus of less than the upper limit can suppress the deterioration of gas barrier properties (e.g., oxygen barrier properties and water vapor barrier properties, especially oxygen barrier properties) even after heat treatment such as retort treatment, and tends to have excellent appearance.
• gas barrier properties e.g., oxygen barrier properties and water vapor barrier properties, especially oxygen barrier properties
• the first adhesive layer with an elastic modulus of less than the upper limit tends to have excellent adhesion to the printing layer.
• the elastic modulus of the cross section of the first adhesive layer measured using an AFM is preferably 5.0 MPa or more, more preferably 10.0 MPa or more, even more preferably 15.0 MPa or more, even more preferably 16.0 MPa or more, and particularly preferably 18.0 MPa or more.
• a packaging bag produced using a laminate including a first adhesive layer having an elastic modulus equal to or greater than the lower limit can suppress deterioration of gas barrier properties even after heat treatment such as retort treatment, and tends to have excellent appearance.
• the elastic modulus of the first adhesive layer is, for example, not less than 5.0 MPa and not more than 35.0 MPa. Details of the conditions for measuring the elastic modulus by AFM are described in the Examples section.
• the first adhesive layer having the above elastic modulus can be formed, for example, by using a solvent-based adhesive as described below, and by appropriately changing the type and molecular weight of the polymer component contained in the base agent, the type of curing agent, the molar ratio (NCO/OH), and the aging conditions, as described below.
• the softening point of the cross section of the first adhesive layer measured by local thermal analysis using a thermal probe is 200°C or higher, preferably 205°C or higher, more preferably 210°C or higher, even more preferably 215°C or higher, even more preferably 220°C or higher, and particularly preferably 225°C or higher.
• a packaging bag made using a laminate having a first adhesive layer with a softening point equal to or higher than the lower limit has excellent heat resistance, can suppress deterioration of gas barrier properties even after heat treatment such as retort treatment, and tends to have excellent appearance and laminate strength.
• the softening point measured by local thermal analysis using a thermal probe is 330°C or less, optionally 320°C or less, optionally 310°C or less, optionally 300°C or less, optionally 290°C or less, optionally 280°C or less, optionally 270°C or less, or optionally 260°C or less.
• the softening point of the first adhesive layer is 200° C. or higher and 330° C. or lower.
• the softening point of the adhesive layer is a value measured by local thermal analysis using a thermal probe.
• the thermal probe In local thermal analysis using a thermal probe, the thermal probe is placed in contact with the cross section of the adhesive layer, and the temperature is raised while measuring the displacement of the cross section of the adhesive layer in the normal direction from before heating the thermal probe to obtain a thermal expansion curve.
• the cross section is obtained by cutting the laminate in the thickness direction perpendicular to the main surface.
• the point where the thermal probe comes into contact is near the center of the adhesive layer in the thickness direction among the exposed parts of the cross section of the adhesive layer. Measurements are performed at five or more points on the same cross section, and the softening point is recorded as the arithmetic average of the values measured at five points with good reproducibility.
• the components in the adhesive layer expand when heated, pushing up the thermal probe.
• the slope of the thermal expansion curve changes due to structural transitions in the components of the adhesive layer.
• the tip of the thermal probe enters the component, causing the thermal probe to descend.
• the point where the displacement of the thermal probe changes from rising to falling corresponds to the peak of the thermal expansion curve, and is called the softening point.
• the softening point of the adhesive layer can be obtained by reading the temperature at the peak of the thermal expansion curve. Details of the measurement conditions are described in the Examples section.
• the elastic modulus of the first adhesive layer is generally an index of the resistance of an object to deformation, and the smaller the elastic modulus, the easier the object is to deform.
• the elastic modulus of the first adhesive layer is a certain value or less (e.g., 35.0 MPa)
• the first adhesive layer becomes easy to deform, and the first adhesive layer easily follows the expansion and contraction of the first substrate and the second substrate, which are layers adjacent to the first adhesive layer.
• the first substrate and the second substrate expand with an increase in temperature, but the first adhesive layer, which is easy to deform, follows the expansion of the first substrate and the second substrate, and cracks and the like are unlikely to occur in the first adhesive layer.
• the first substrate and the second substrate shrink with a decrease in temperature, but the first adhesive layer, which is easy to deform, follows the contraction of the first substrate and the second substrate, and cracks and the like are unlikely to occur in the first adhesive layer.
• the first adhesive layer When the elastic modulus of the first adhesive layer is equal to or less than a certain level, the first adhesive layer is less likely to develop gaps such as cracks through which gas can get in, even when heat treatment is performed, and the packaging bag can be prevented from deteriorating in gas barrier properties even after heat treatment. Furthermore, when the first adhesive layer is adjacent to an inorganic oxide layer, cracks in the inorganic oxide layer can be suppressed, and deterioration in gas barrier properties can be further suppressed. If the softening point of the first adhesive layer is too low, the first adhesive layer is likely to soften when the packaging bag is subjected to heat treatment.
• the adhesive forming the first adhesive layer flows between the first substrate and the second substrate, and the adhesive cannot withstand the increase in the internal pressure of the packaging bag, and the sealed state is likely to be broken.
• the softening point of the first adhesive layer e.g. 200°C or higher
• excessive flow of the adhesive does not occur during heat treatment, making it easier to maintain the sealed state, and the packaging bag can suppress the deterioration of the gas barrier property even after heat treatment. It is also generally known that if the softening point of an adhesive is too high, the adhesiveness decreases and the adhesive strength to the adherend is weakened.
• the softening point of the first adhesive layer is too high, the adhesive strength to the adherend, the first substrate and the second substrate, is weakened, and delamination is likely to occur when the packaging bag is heat-treated.
• a certain level or lower for example, 330°C or lower
• delamination is unlikely to occur between the first adhesive layer and the first substrate and between the first adhesive layer and the second substrate even when heat-treated, and gaps through which gas can enter are unlikely to occur between the layers, so that the packaging bag can suppress the deterioration of gas barrier properties even after heat treatment.
• the adhesive forming the first adhesive layer being less likely to flow even when subjected to heat treatment, and interlayer delamination being less likely to occur even when subjected to heat treatment, it is believed that a packaging bag made using a laminate including a first adhesive layer having an elastic modulus below a certain level and a softening point within a certain range will be able to suppress deterioration in gas barrier properties even after heat treatment such as after retort treatment.
• the thickness of the first adhesive layer is 1.0 ⁇ m or more, preferably 1.5 ⁇ m or more, more preferably 2.0 ⁇ m or more, even more preferably 2.5 ⁇ m or more, particularly preferably 3.5 ⁇ m or more, and preferably 10.0 ⁇ m or less, more preferably 8.0 ⁇ m or less, even more preferably 6.0 ⁇ m or less, particularly preferably 5.0 ⁇ m or less, for example 1.0 ⁇ m or more and 10.0 ⁇ m or less.
• a first adhesive layer having a thickness equal to or greater than the lower limit can effectively cover the step caused by the printed layer, and a packaging bag with a good appearance tends to be obtained.
• a laminate having a first adhesive layer having a thickness equal to or greater than the lower limit tends to have excellent lamination strength even after heat treatment.
• the thickness of the first adhesive layer relative to the total thickness of the laminate is preferably 1.0% or more, more preferably 1.5% or more, even more preferably 2.0% or more, and particularly preferably 2.5% or more, and is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 6.0% or less, and particularly preferably 5.0% or less, for example, 1.0% or more and 10.0% or less.
• the thickness of the second adhesive layer is preferably 0.5 ⁇ m or more, more preferably 0.8 ⁇ m or more, even more preferably 1.0 ⁇ m or more, particularly preferably 3.0 ⁇ m or more, and is preferably 10.0 ⁇ m or less, more preferably 8.0 ⁇ m or less, even more preferably 6.0 ⁇ m or less, particularly preferably 5.0 ⁇ m or less, for example, 0.5 ⁇ m or more and 10.0 ⁇ m or less.
• a laminate having a second adhesive layer whose thickness is equal to or more than the lower limit can suppress elongation of the sealant layer when cut.
• the softening point of the cross section of the second adhesive layer measured by local thermal analysis using a thermal probe is preferably 200°C or higher, more preferably 205°C or higher, even more preferably 210°C or higher, even more preferably 215°C or higher, and particularly preferably 220°C or higher or 225°C or higher, and may be, for example, 330°C or lower, 320°C or lower, 310°C or lower, 300°C or lower, 290°C or lower, 280°C or lower, 270°C or lower, or 260°C or lower, for example, 200°C or higher and 330°C or lower.
• a packaging bag made using a laminate having a second adhesive layer with a softening point equal to or higher than the lower limit has excellent heat resistance, and can suppress deterioration of gas barrier properties even after heat treatment such as retort treatment, and tends to have excellent appearance and laminate strength.
• the elastic modulus measured by AFM for the cross section of the second adhesive layer is preferably 35.0 MPa or less, more preferably 33.0 MPa or less, even more preferably 30.0 MPa or less, even more preferably 28.0 MPa or less, particularly preferably 26.0 MPa or less, and also preferably 5.0 MPa or more, more preferably 10.0 MPa or more, even more preferably 15.0 MPa or more, even more preferably 16.0 MPa or more, particularly preferably 18.0 MPa or more, for example, 5.0 MPa or more and 35.0 MPa or less.
• a packaging bag made using a laminate having a second adhesive layer with such an elastic modulus tends to be able to suppress the deterioration of gas barrier properties even after heat treatment such as retort treatment.
• a second adhesive layer with such an elastic modulus can be formed, for example, by using a solvent-based adhesive described later, and by appropriately changing the type and molecular weight of the polymer component contained in the main agent, the type of curing agent, the molar ratio (NCO/OH), and the aging conditions, each of which will be described later.
• the modulus of elasticity of the second adhesive layer is smaller than the modulus of elasticity of the first adhesive layer.
• a packaging bag made using a laminate of this type tends to have better impact resistance, and therefore better resistance to bag breakage due to dropping, as well as better seal strength. This is presumably because the smaller modulus of elasticity of the second adhesive layer can prevent the surface layer of the second substrate from peeling off, thereby preventing a decrease in the laminate strength between the second substrate and the sealant layer.
• the elastic modulus of the second adhesive layer is greater than the elastic modulus of the first adhesive layer.
• Packaging bags made using a laminate of this type tend to have superior tearability, and therefore superior openability.
• the thickness of the second adhesive layer is, in one embodiment, preferably 1.0 ⁇ m or more, more preferably 1.5 ⁇ m or more, even more preferably 2.0 ⁇ m or more, particularly preferably 2.5 ⁇ m or more, and also preferably 10.0 ⁇ m or less, more preferably 8.0 ⁇ m or less, even more preferably 6.0 ⁇ m or less, particularly preferably 5.0 ⁇ m or less, for example 1.0 ⁇ m or more and 10.0 ⁇ m or less.
• the thickness of the second adhesive layer relative to the thickness of the entire laminate is preferably 1.0% or more, more preferably 1.5% or more, even more preferably 2.0% or more, particularly preferably 2.5% or more, and also preferably 10.0% or less, more preferably 8.0% or less, even more preferably 6.0% or less, particularly preferably 5.0% or less, for example 1.0% or more and 10.0% or less.
• a laminate having a second adhesive layer whose thickness is equal to or greater than the lower limit tends to have excellent laminate strength even after heat treatment.
• the thickness of the first adhesive layer is greater than the thickness of the second adhesive layer in one embodiment.
• the ratio of thickness 1 of the first adhesive layer to thickness 2 of the second adhesive layer may be, for example, 0.4 or more, 0.6 or more, or 0.8 or more, and when the thickness of the first adhesive layer is greater than the thickness of the second adhesive layer, it may be greater than 1.0, and may also be 2.5 or less, 1.8 or less, or 1.2 or less.
• the reason why a packaging bag made using a laminate including the second adhesive layer can suppress deterioration in gas barrier properties even after heat treatment such as retort treatment is thought to be the same as when the modulus of elasticity of the first adhesive layer is below a certain level and the softening point is within a certain range.
• the elastic modulus measured by AFM on the cross section of the second adhesive layer is preferably more than 35.0 MPa, and is preferably 120 MPa or less, more preferably 110 MPa or less, even more preferably 100 MPa or less, even more preferably 90.0 MPa or less, particularly preferably 80.0 MPa or less, 70.0 MPa or less, 60.0 MPa or less, or 50.0 MPa or less, for example, more than 35.0 MPa and 120 MPa or less.
• a laminate having a second adhesive layer with an elastic modulus of less than the upper limit tends to have excellent lamination strength.
• a second adhesive layer having such an elastic modulus can be formed, for example, by using a solvent-free adhesive described later, and by appropriately changing the type and molecular weight of the polymer component contained in the base agent, the type of curing agent, the molar ratio (NCO/OH), and the aging conditions, each of which will be described later.
• the thickness of the second adhesive layer is preferably 3.0 ⁇ m or less, more preferably 2.5 ⁇ m or less, even more preferably 2.0 ⁇ m or less, even more preferably 1.5 ⁇ m or less, and also preferably 0.5 ⁇ m or more, more preferably 0.8 ⁇ m or more, even more preferably 1.0 ⁇ m or more, for example 0.5 ⁇ m or more and 3.0 ⁇ m or less.
• the thickness of the second adhesive layer relative to the thickness of the entire laminate is preferably 0.5% or more, more preferably 0.8% or more, even more preferably 1.0% or more, and also preferably 3.0% or less, more preferably 2.5% or less, even more preferably 2.0% or less, even more preferably 1.5% or less, for example 0.5% or more and 3.0% or less.
• the thickness of the second adhesive layer is smaller than the thickness of the first adhesive layer.
• the first adhesive layer and the second adhesive layer are each composed of an adhesive.
• the adhesive forming the first adhesive layer and the adhesive forming the second adhesive layer may be the same or different.
• the adhesive may be any of a one-component curing adhesive, a two-component curing adhesive, and a non-curing adhesive, and a two-component curing adhesive is preferred from the viewpoint of easily adjusting the elastic modulus and softening point to the above-mentioned range.
• One method for obtaining a laminate using an adhesive is to apply the adhesive to an object, then overlay another object on the formed adhesive layer and allow the adhesive layer sandwiched between the two to harden.
• objects include a first substrate, a second substrate, and a sealant film.
• the process of allowing the adhesive layer to harden is hereinafter also referred to as the "aging process.”
• the aging conditions for the adhesive are described below.
• the aging temperature is preferably 25°C or higher, more preferably 30°C or higher, and even more preferably 35°C or higher, and is preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 60°C or lower.
• the aging time is preferably 5 hours or higher, more preferably 10 hours or higher, and even more preferably 20 hours or higher, and is preferably 150 hours or lower, more preferably 135 hours or lower, and even more preferably 120 hours or lower.
• adhesives examples include polyurethane-based adhesives, polyester-based adhesives, polyether-based adhesives, rubber-based adhesives, vinyl-based adhesives, olefin-based adhesives, silicone-based adhesives, epoxy-based adhesives, and phenol-based adhesives.
• polyurethane-based adhesives, polyester-based adhesives, and polyether-based adhesives are preferred, polyurethane-based adhesives and polyester-based adhesives are more preferred, polyurethane-based adhesives are even more preferred, and two-component curing polyurethane-based adhesives are particularly preferred.
• the adhesive may be a solvent-based adhesive or a solventless adhesive.
• a solvent-based adhesive is an adhesive used in a method in which the adhesive is applied to an object, heated in an oven or the like to volatilize the solvent in the adhesive, and then the adhesive is bonded to another object.
• the base agent or the curing agent, or both contain a solvent.
• the solvent examples include organic solvents, specifically, hydrocarbon solvents such as toluene, xylene, n-hexane, and methylcyclohexane; ester solvents such as ethyl acetate, n-propyl acetate, n-butyl acetate, and isobutyl acetate; alcohol solvents such as methanol, ethanol, isopropyl alcohol, n-butyl alcohol, and isobutyl alcohol; and ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.
• organic solvents specifically, hydrocarbon solvents such as toluene, xylene, n-hexane, and methylcyclohexane
• ester solvents such as ethyl acetate, n-propyl acetate, n-butyl acetate, and isobutyl a
• a solvent-free adhesive is an adhesive that is applied to an object and then bonded to another object without necessarily going through a process of heating in an oven or the like to volatilize the solvent.
• both the base agent and the curing agent contain substantially no solvent.
• substantially no solvent includes cases where the solvent used as a reaction medium during the manufacture of the adhesive's components, or the base agent and/or curing agent in the case of a two-component curing adhesive, cannot be completely removed, leaving trace amounts of solvent remaining in the adhesive, or the base agent and/or curing agent in the case of a two-component curing adhesive.
• Two-component curing polyurethane adhesives have a base agent and a curing agent.
• Two-component curing polyurethane adhesives may be solvent-based or solventless. Two-component curing polyurethane adhesives are described below.
• Polyurethane adhesives for example, have a base agent containing a polyol compound and a curing agent containing a polyisocyanate compound.
• Examples of the cured product (reactant) formed by mixing such a base agent and curing agent include polyurethane, and specific examples include polyester polyurethane, polyether polyurethane, polycarbonate polyurethane, and acrylic polyurethane.
• the polyol compound has two or more hydroxy groups in one molecule.
• polyol compounds include polyester polyurethane polyol, polyester polyol, polyether polyol, polycarbonate polyol, and acrylic polyol.
• polyester polyurethane polyol and polyester polyol are preferred from the viewpoint of easily obtaining an adhesive layer having an elastic modulus in the above-mentioned range, polyester polyurethane polyol is more preferred in the case of a solvent-based adhesive, and polyester polyol is more preferred in the case of a solventless adhesive.
• Polyester polyurethane polyol is a compound that has two or more hydroxy groups, ester bonds, and urethane bonds in one molecule, and has, for example, a polyester polyurethane structure as the main backbone.
• Polyester polyol is a compound that has two or more hydroxy groups and ester bonds in one molecule, and has, for example, a polyester structure as the main backbone.
• Polyether polyol is a compound that has two or more hydroxy groups and ether bonds in one molecule.
• Polycarbonate polyol is a compound that has two or more hydroxy groups and carbonate bonds in one molecule.
• the weight average molecular weight (Mw) of the polymer component (e.g., polyol compound) contained in the main agent of the two-component curing and solvent-based adhesive is preferably 11,000 or more, more preferably 13,000 or more, even more preferably 15,000 or more, even more preferably 18,000 or more, particularly preferably 20,000 or more, and is preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 40,000 or less, from the viewpoint of coating suitability.
• Mw weight average molecular weight
• the smaller the Mw the shorter the molecular chain of the polymer component becomes, and the denser the polymer component becomes, and the higher the softening point of the adhesive layer tends to be. Conversely, the larger the Mw, the longer the molecular chain of the polymer component becomes, and the lower the softening point of the adhesive layer tends to be.
• the polydispersity (Mw/Mn) of the polymer component (e.g., polyol compound) contained in the base agent is preferably 5.0 or less, more preferably 4.5 or less, and even more preferably 4.0 or less, and is preferably 1.5 or more, more preferably 2.0 or more, and even more preferably 2.5 or more, where Mn is the number average molecular weight of the polymer component (e.g., polyol compound) contained in the base agent.
• Mn is the number average molecular weight of the polymer component (e.g., polyol compound) contained in the base agent.
• Each average molecular weight is measured by gel permeation chromatography (GPC) in accordance with JIS K7252-1: 2016, and is a value expressed in terms of polystyrene.
• a measuring device HLC-8220GPC manufactured by Tosoh Corporation
• a column in which TSKgel GHM HQ -H and TSK guardcolumn H HQ -H are connected in series and dimethylformamide (DMF) can be used as the eluent.
• DMF dimethylformamide
• the weight average molecular weight (Mw) of the polymer component (e.g., polyol compound) contained in the base agent of the two-component curing and solventless adhesive is preferably 800 or more, more preferably 1,200 or more, and even more preferably 2,000 or more, and is preferably 10,000 or less, more preferably 8,000 or less, and even more preferably 6,000 or less.
• Mw weight average molecular weight
• the polydispersity (Mw/Mn) of the polymer component (e.g., polyol compound) contained in the base agent is preferably 2.8 or less, more preferably 2.7 or less, even more preferably 2.6 or less, particularly preferably 2.5 or less, and is preferably 1.2 or more, more preferably 1.5 or more, and even more preferably 2.0 or more, where Mn is the number average molecular weight of the polymer component (e.g., polyol compound) contained in the base agent.
• a polyisocyanate compound has two or more isocyanate groups in one molecule.
• examples of polyisocyanate compounds include aromatic isocyanates and aliphatic isocyanates.
• the polyisocyanate compound may be a blocked isocyanate compound obtained by addition reaction using a known isocyanate blocking agent by a known, conventional, appropriate method.
• polyisocyanate compounds include aliphatic isocyanate compounds such as tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), norbornene diisocyanate, and isophorone diisocyanate (IPDI); aromatic isocyanate compounds such as diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate (XDI), hydrogenated xylylene diisocyanate, tolylene diisocyanate (TDI), naphthalene diisocyanate, and ⁇ , ⁇ , ⁇ ', ⁇ '-tetramethyl-m-xylylene diisocyanate, dimers and trimers (e.g., isocyanurates) derived from these compounds; and adducts, biurets, and allophanates obtained by reacting these compounds with low-molecular-weight active hydrogen compounds or their alkylene oxide adduct
• Examples of low molecular weight active hydrogen compounds include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexamethylene glycol, 1,8-octamethylene glycol, 1,4-cyclohexanedimethanol, metaxylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine and metaxylylenediamine, with trimethylolpropane being preferred.
• Examples of high molecular weight active hydrogen compounds include polyesters, polyether polyols and polyamides.
• the base agent containing a polyol compound and the curing agent containing a polyisocyanate compound are preferably used in an amount ratio such that the molar ratio (NCO/OH) of the total isocyanate groups of the polyisocyanate compound to the total hydroxyl groups of the polyol compound is as follows: That is, the molar ratio (NCO/OH) is preferably 0.5 or more, more preferably 1.0 or more, even more preferably 1.5 or more, and is preferably 8.0 or less, more preferably 6.0, even more preferably 5.0 or less, and in the case of a solventless adhesive, is even more preferably 4.0 or less, and particularly preferably 3.0 or less.
• the laminate of the present disclosure is preferably used as a packaging material.
• the packaging material is used to produce a packaging bag.
• the packaging bag of the present disclosure includes the laminate.
• a packaging bag can be produced.
• the laminate of the present disclosure is folded in half and stacked so that the first substrate is located on the outside and the sealant layer is located on the inside, and the ends and the like are heat-sealed to produce a packaging bag.
• a plurality of laminates of the present disclosure are stacked so that the sealant layers face each other, and the ends and the like are heat-sealed to produce a packaging bag.
• the entire packaging bag may be composed of the laminate, or a part of the packaging bag may be composed of the laminate.
• Packaging bags include various types of bags, such as standing pouch type, side seal type, two-sided seal type, three-sided seal type, four-sided seal type, envelope seal type, grommet seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, and gusset type.
• Heat sealing methods include bar seal, rotary roll seal, belt seal, impulse seal, high frequency seal, and ultrasonic seal.
• the packaging bag may have an easy-to-open portion.
• easy-to-open portions include a notch portion that serves as the starting point for tearing the packaging bag, and a half-cut line formed by laser processing or a cutter as a path for tearing the packaging bag.
• the packaging bag may be provided with a steam release mechanism.
• the steam release mechanism When the steam pressure inside the packaging bag reaches or exceeds a predetermined value, the steam release mechanism is configured to connect the inside and outside of the packaging bag, allowing steam to escape while preventing steam from escaping at locations other than the steam release mechanism.
• the steam release mechanism includes, for example, a steam release seal portion that protrudes from the side seal portion toward the inside of the packaging bag, and a non-sealed portion that is isolated from the content storage portion by the steam release seal portion. The non-sealed portion is in communication with the outside of the packaging bag.
• the packaging bag is filled with content and the opening is heat-sealed, and is heated using a microwave oven or the like. This increases the internal pressure and causes the steam release seal portion to peel off. Steam passes through the peeled portion of the steam release seal portion and the non-sealed portion to escape to the outside of the packaging bag.
• the contents to be contained in the packaging bag include, for example, liquids, solids, powders, and gels.
• the contents may be food or beverages, or non-food or beverages such as chemicals, cosmetics, medicines, metal parts, and electronic parts.
• the opening of the packaging bag can be heat-sealed to seal the packaging bag.
• the contents may be a retort food or a boiled food.
• the packaging bag of the present disclosure may be a pouch for containing a retort food or a boiled food.
• the sachet is a small packaging bag used to store contents of, for example, 1 g to 200 g.
• contents stored in the sachet include sauces, soy sauce, dressings, ketchup, syrups, cooking alcohol, and other liquid or viscous seasonings; liquid soups, powdered soups, fruit juices; spices; pet food; liquid beverages, jelly-like beverages, instant foods, and other foods and beverages; and non-food items such as chemicals, cosmetics, medicines, metal parts, and electronic parts.
• Standing pouches are used to store contents of, for example, 50 g to 2000 g.
• Contents that can be stored in standing pouches include, for example, shampoo, rinse, conditioner, hand soap, body soap, air freshener, deodorant, insect repellent, detergent; dressing, edible oil, mayonnaise, other liquid or viscous condiments; liquid beverages, jelly-like beverages, instant foods, other food and beverages; pet food; cream; metal parts, and electronic parts.
• the contents of the packaging bag are pet food.
• the packaging bag of the present disclosure is suitable as a retort-treated pouch (hereinafter also referred to as a "retort pouch”) or a boiled pouch (hereinafter also referred to as a "boiled pouch”), or as a microwave-compatible packaging bag, since it can suppress deterioration of gas barrier properties even when subjected to heat treatment.
• the packaging bag of the present disclosure is also suitable as a boiled or retort pouch for use in a microwave oven.
• a microwave-compatible packaging bag means a packaging bag that can be heated using a microwave oven.
• a retort pouch is a packaging bag that is filled with food or beverages or other contents, sealed, and then heat sterilized (retort processing) with water or steam at a temperature exceeding 100°C under pressure.
• a boil pouch is a packaging bag that is filled with food or beverages or other contents, sealed, and then boiled at a temperature below 100°C.
• the packaging bag of the present disclosure is a retort pouch.
• retort treatment there are various conditions for the retort treatment, but any pouch that has undergone general retort treatment is included in the retort pouch.
• a treatment temperature of 105°C or higher and 115°C or lower may be called semi-retort treatment
• a treatment temperature of more than 115°C and 121°C or lower may be called retort treatment
• a treatment temperature of more than 121°C and 140°C or lower may be called high retort treatment.
• the retort treatment time is, for example, from 5 minutes to 60 minutes, and preferably from 15 minutes to 40 minutes.
• the packaging bag of the present disclosure is a retort pouch.
• the oxygen permeability (unit: cc/ m2 ⁇ day ⁇ atm) of the retort pouch of the present disclosure is preferably 2.0 or less, more preferably 1.5 or less, even more preferably 1.3 or less, and particularly preferably 1.0 or less.
• the oxygen permeability is measured in accordance with JIS K7126-2:2006 at a temperature of 23° C. and a relative humidity of 90% RH. The lower the lower limit of the oxygen permeability, the better, but it may be, for example, 0.1.
• Figure 17 shows a packaging bag 50 obtained by bonding two laminates together.
• the shaded areas indicate the heat-sealed areas.
• the packaging bag 50 may have an easy-to-open portion 51.
• Examples of the easy-to-open portion 51 include a notch portion 52 that serves as the starting point for tearing, and a half-cut line 53 formed by laser processing or a cutter as a path for tearing.
• Figure 18 shows a simplified example of the structure of a standing pouch.
• the shaded areas indicate the heat-sealed areas.
• the standing pouch 60 comprises a body portion (side sheets) 61 and a bottom portion (bottom sheet) 62.
• the side sheets 61 and the bottom sheet 62 may be made of the same material, or may be made of different materials.
• the bottom sheet 62 retains the shape of the side sheets 61, which gives the pouch self-supporting properties and allows it to be a standing pouch.
• a storage space for storing contents is formed within the area surrounded by the side sheets 61 and the bottom sheet 62.
• the standing pouch 60 may be provided with a steam release mechanism 63.
• the steam release mechanism 63 includes a steam release seal portion 63a that protrudes from the side seal portion toward the inside of the packaging bag, and a non-sealed portion 63b that is isolated from the content storage portion by the steam release seal portion 63a.
• the non-sealed portion 63b is in communication with the outside of the packaging bag.
• only the body may be made of the laminate of the present disclosure, only the bottom may be made of the laminate, or both the body and bottom may be made of the laminate.
• the side sheet can be formed by making a bag so that the sealant layer of the laminate of the present disclosure is the innermost layer.
• the side sheet can be formed by preparing two laminates of the present disclosure, stacking them together with the sealant layers facing each other, and heat-sealing the side edges on both sides to make a bag.
• the side sheet can be formed by preparing two laminates of the present disclosure, stacking them together with the sealant layers facing each other, inserting two laminates folded in a V-shape with the sealant layers facing outward between the laminates at the side edges on both sides of the stacked laminates, and heat sealing them.
• This manufacturing method produces a standing pouch having a body with side gussets.
• the bottom sheet can be formed by inserting a laminate between the lower parts of the side sheets that have been made into a bag and heat sealing it. More specifically, the bottom sheet can be formed by inserting a laminate folded into a V shape with the sealant layer on the outside between the lower parts of the side sheets that have been made into a bag and heat sealing it.
• two laminates are prepared and stacked together with the sealant layers facing each other.
• another laminate is folded into a V shape with the sealant layer on the outside, and this is sandwiched between the lower part of the laminates that have been faced together and heat sealed to form the bottom.
• the two sides adjacent to the bottom are heat sealed to form the body. In this manner, the standing pouch of one embodiment can be formed.
• a laminate comprising a first substrate, a first adhesive layer, a second substrate, a second adhesive layer, and a sealant layer in this order in the thickness direction, wherein the first substrate comprises an oriented substrate containing polypropylene as a main component, the second substrate comprises an oriented substrate containing polypropylene as a main component, at least one selected from the first substrate and the second substrate is a barrier substrate further comprising an inorganic oxide layer, the sealant layer contains polypropylene as a main component, the first adhesive layer has an elastic modulus of 35.0 MPa or less as measured with an atomic force microscope (AFM) on a cross section thereof, the first adhesive layer has a softening point of 200° C.
• AFM atomic force microscope
• the first adhesive layer has a thickness of 1.0 ⁇ m or more.
• the elastic modulus of the first adhesive layer is 15.0 MPa or more and 30.0 MPa or less.
• the thickness of the first adhesive layer is 2.0 ⁇ m or more and 5.0 ⁇ m or less.
• a hydroxyl-containing acrylic resin (number average molecular weight: 25,000, glass transition temperature: 99°C, hydroxyl value: 80mgKOH/g) was diluted with a mixed solvent of methyl ethyl ketone and ethyl acetate (mixing ratio 1:1) to a solid content concentration of 10% by mass to prepare a base material.
• An ethyl acetate solution containing tolylene diisocyanate (solid content 75% by mass) was added to the base material as a curing agent to obtain a solution for forming a surface coating layer.
• the amount of the curing agent used was 10 parts by mass relative to 100 parts by mass of the base material.
• a 20 ⁇ m-thick biaxially oriented polypropylene film (ME-1, manufactured by Mitsui Chemicals Tohcello Co., Ltd.) was prepared, with one side corona-treated.
• the above-mentioned surface coating layer-forming solution was applied to the corona-treated side of the film and dried to form a surface coating layer with a thickness of 0.5 ⁇ m. In this way, a resin substrate was obtained.
• a carbon-containing silicon oxide (silica) vapor deposition film with a thickness of 12 nm was formed on the surface coating layer of the resin substrate using a low-temperature plasma chemical vapor deposition apparatus (CVD method) in a roll-to-roll manner while applying tension to the resin substrate.
• the conditions for forming the vapor deposition film were as follows:
• the carbon percentage C, silicon percentage Si, and oxygen percentage O in the carbon-containing silicon oxide vapor deposition film were measured.
• the carbon percentage C, silicon percentage Si, and oxygen percentage O were 32.7%, 29.8%, and 37.5%, respectively, based on a total of 100% for the three elements silicon, oxygen, and carbon.
• the percentages of each element were measured by narrow scan analysis using X-ray photoelectron spectroscopy (XPS) under the measurement conditions described above.
• Solution A and solution B were mixed at a mass ratio (solution A:solution B) of 6.5:3.5 to obtain a barrier coating agent.
• the barrier coating agent was coated on the deposition film formed on the resin substrate by spin coating, and the coating was heated in an oven at 80°C for 60 seconds to form a barrier coating layer with a thickness of 300 nm.
• a transparent barrier substrate was obtained that had, in this order, a 20 ⁇ m-thick biaxially oriented polypropylene film, a 0.5 ⁇ m-thick surface coating layer, a 12 nm-thick carbon-containing silicon oxide (silica) vapor deposition film, and a 300 nm-thick barrier coating layer.
• Adhesive A A two-component curing adhesive composed of the following base agent and curing agent was used.
• Adhesive A Base Polyester polyurethane polymer (Mw: 30,000)
• Curing agent a mixture of isophorone diisocyanate (IPDI) trimer and xylylene diisocyanate (XDI) trimethylolpropane (TMP) adduct Molar ratio of base agent to curing agent (NCO/OH): 4
• Adhesive A contains ethyl acetate as a solvent.
• Adhesive B Base: Polyester polymer (Mw: 22,000) Hardener: A mixture of hexamethylene diisocyanate (HDI) in biuret form and HDI in nurate form Molar ratio of base agent to hardener (NCO/OH): 2 Adhesive B contains ethyl acetate as a solvent.
• Adhesive C Base: Polyester polyurethane polymer (Mw: 27,000) Hardener: mixture of XDI and IPDI Adhesive C contains ethyl acetate as a solvent.
• Adhesive D Base Polyester polymer (Mw: 4,000) Hardener: Mixture of HDI and XDI Molar ratio of base agent to hardener (NCO/OH): 2 Adhesive D is substantially free of solvent.
• Adhesive E Base Polyester polymer (Mw: 3,500) Hardener: Mixture of IPDI and HDI (higher HDI content than IPDI) Molar ratio of base agent to curing agent (NCO/OH): 2 Adhesive E is substantially free of solvent.
• Adhesive F Base Polyether polymer (Mw: 4,000) Curing agent: Aromatic curing agent Molar ratio of base agent to curing agent (NCO/OH): 2 Adhesive F is substantially free of solvent.
• Adhesive G Base Polyester polymer (Mw: 30,000) Hardener: A mixture of hexamethylene diisocyanate (HDI) in biuret form and HDI in nurate form Molar ratio of base agent to hardener (NCO/OH): 2 Adhesive B contains ethyl acetate as a solvent.
• Adhesive H Base Polyester polymer (Mw: 2,000) Hardener: Mixture of IPDI and HDI (higher HDI content than IPDI) Molar ratio of base agent to curing agent (NCO/OH): 2 Adhesive H is substantially free of solvent.
• Example 1 As the first substrate, a biaxially stretched polypropylene film having a thickness of 20 ⁇ m (P2171, manufactured by Toyobo Co., Ltd., hereinafter also referred to as "BOPP film") having one surface subjected to corona treatment was prepared. As the second substrate, the above-mentioned transparent barrier substrate was prepared. As the sealant layer, a non-stretched polypropylene film having a thickness of 60 ⁇ m (ET-20, manufactured by Okamoto Co., Ltd., hereinafter also referred to as "CPP film”) having one surface subjected to corona treatment was prepared.
• CPP film non-stretched polypropylene film having a thickness of 60 ⁇ m
• a printed layer with a coating thickness of 1 ⁇ m (when dry) was formed on the corona-treated surface of the BOPP film as the first substrate by the gravure roll coating method.
• Adhesive A was applied onto the printed layer by the gravure roll coating method, and the adhesive layer surface formed on the first substrate and the barrier coat layer surface of the transparent barrier substrate were bonded together, and aged at 40°C for 72 hours.
• a corona treatment was performed on the non-barrier coat layer surface of the transparent barrier substrate, and adhesive A was applied by the gravure roll coating method, and the adhesive layer surface formed on the transparent barrier substrate and the corona-treated surface of the CPP film were bonded together, and aged at 40°C for 72 hours.
• the thickness of each adhesive layer formed was 3.6 ⁇ m.
• the resulting laminate had the following layer structure: BOPP film (20 ⁇ m)/printed layer (1 ⁇ m)/adhesive layer (3.6 ⁇ m)/transparent barrier substrate (21 ⁇ m)/adhesive layer (3.6 ⁇ m)/CPP film (60 ⁇ m).
• the numbers in parentheses indicate the thickness of each layer.
• Laminates were prepared in the same manner as in Example 1, except that the type of adhesive and/or the thickness of the first adhesive layer was changed as described in Table 1.
• the thickness of the second adhesive layer was also changed in the same manner as the thickness of the first adhesive layer.
• Example 6 As the first substrate, a biaxially stretched polypropylene film (P2171, BOPP film, manufactured by Toyobo Co., Ltd.) having a thickness of 20 ⁇ m and having one surface subjected to corona treatment was prepared. As the second substrate, the above-mentioned transparent barrier substrate was prepared. As the sealant layer, a non-stretched polypropylene film (ET-20, CPP film, manufactured by Okamoto Co., Ltd.) having a thickness of 60 ⁇ m and having one surface subjected to corona treatment was prepared.
• E-20 non-stretched polypropylene film
• a printed layer with a coating thickness of 1 ⁇ m (when dry) was formed on the corona-treated surface of the BOPP film used as the first substrate by the gravure roll coating method.
• Adhesive D was applied onto the printed layer by the gravure roll coating method, and the adhesive layer surface formed on the first substrate and the barrier coat layer surface of the transparent barrier substrate were bonded together, and aged at 40°C for 72 hours.
• a corona treatment was performed on the non-barrier coat layer surface of the transparent barrier substrate, and adhesive D was applied by the gravure roll coating method, and the adhesive layer surface formed on the transparent barrier substrate and the corona-treated surface of the CPP film were bonded together, and aged at 40°C for 72 hours.
• the thickness of each adhesive layer formed was 1.35 ⁇ m.
• the resulting laminate had the following layer structure: BOPP film (20 ⁇ m)/printed layer (1 ⁇ m)/adhesive layer (1.35 ⁇ m)/transparent barrier substrate (21 ⁇ m)/adhesive layer (1.35 ⁇ m)/CPP film (60 ⁇ m).
• the numbers in parentheses indicate the thickness of each layer.
• Laminates were prepared in the same manner as in Example 6, except that the type of adhesive and/or the thickness of the first adhesive layer was changed as described in Table 1.
• the thickness of the second adhesive layer was also changed in the same manner as the thickness of the first adhesive layer.
• a transparent barrier substrate was prepared as the first substrate.
• a biaxially oriented polypropylene film (P2171, BOPP film, manufactured by Toyobo Co., Ltd.) having a thickness of 20 ⁇ m and having one surface corona-treated was prepared as the second substrate.
• An unoriented polypropylene film (ET-20, CPP film, manufactured by Okamoto Co., Ltd.) having a thickness of 60 ⁇ m and having one surface corona-treated was prepared as the sealant layer.
• a printed layer with a coating thickness of 1 ⁇ m (when dry) was formed on the barrier coat layer surface of the transparent barrier substrate as the first substrate by the gravure roll coating method.
• Adhesive A was applied onto the printed layer by the gravure roll coating method, and the adhesive layer surface formed on the first substrate and the corona-treated surface of the BOPP film were bonded together, and aged at 40°C for 72 hours.
• corona treatment was performed on the non-corona-treated surface of the BOPP film, and adhesive A was applied by the gravure roll coating method, and the adhesive layer surface formed on the BOPP film and the corona-treated surface of the CPP film were bonded together, and aged at 40°C for 72 hours.
• the thickness of each adhesive layer formed was 3.6 ⁇ m.
• the resulting laminate had the following layer structure: transparent barrier substrate (21 ⁇ m)/printed layer (1 ⁇ m)/adhesive layer (3.6 ⁇ m)/BOPP film (20 ⁇ m)/adhesive layer (3.6 ⁇ m)/CPP film (60 ⁇ m).
• the numbers in parentheses indicate the thickness of each layer.
• Laminates were prepared in the same manner as in Example 1, except that the type of adhesive, the thickness of the first adhesive layer, and/or the thickness of the second adhesive layer were changed as described in Table 1.
• the measurement device used was a nanoTA manufactured by ANASYS INSTRUMENTS, and the thermal probe used was a PR-EX-AN2-300-5 manufactured by ANASYS INSTRUMENTS.
• nanoTA Calibration Samples manufactured by BRUKER were prepared. Polycaprolactone (softening point: 55°C), polyethylene (softening point: 116°C), and polyethylene terephthalate (softening point: 235°C), which have known softening points, were placed on the stand of the standard samples. Each standard sample was heated while being in contact with a thermal probe on its surface. During heating, the thermal expansion directly below the thermal probe was measured, and a graph showing the deflection against the voltage was obtained. The measurement conditions set in the device were as follows. Measurement start temperature: 0.1V Measurement end temperature: 10V Temperature rise rate: 0.5 V/sec
• the softening point of the adhesive layer was measured.
• the softening point was measured near the center of the adhesive layer in the thickness direction, among the exposed cross-sections of the adhesive layer. Measurements were performed at five or more locations on the same cross-section, and the softening point was recorded as the arithmetic mean of the values measured at five locations with good reproducibility. However, the measurement points were spaced at least 50 ⁇ m apart.
• the measurement was performed by bringing a thermal probe into contact with the cross section of the adhesive layer, heating the adhesive layer under the conditions described below while the thermal probe was in contact, and obtaining a graph (thermal expansion curve) showing the displacement of the thermal probe versus temperature.
• Measurement start temperature 40°C
• Measurement end temperature 350°C
• Heating rate 28° C./sec
• mapping measurements were performed on the above cross section at a 2.5 ⁇ m square including the cross section of the adhesive layer.
• 20 force curves that provided an appropriate force curve shape were selected.
• the elastic modulus was calculated by fitting each force curve according to the JKR (Johnson-Kendall-Roberts) theory, and the arithmetic mean value (hereinafter also referred to as the "first arithmetic mean value") of the obtained 20 elastic moduli was calculated.
• the selected part of the force curve was the vicinity of the center in the thickness direction of the adhesive layer among the parts where the cross section of the adhesive layer was exposed.
• the obtained second arithmetic mean value was taken as the elastic modulus of the cross section of the adhesive layer.
• AFM Elastic Modulus Measurement
• Measurement atmosphere Atmospheric air, room temperature (25°C)
• Measurement mode Contact mode
• Calibration method Measure the cantilever sensitivity using glass Number of measurement points: 64 x 64 points (total 4096 points) ⁇ Field of view: 2.5 ⁇ m square
• Cantilever type CONTR (manufactured by Nano World)
• Cantilever tip radius ⁇ 8 nm
• Cantilever spring constant 0.2 N/m
• Contact pressure 0.5V
• Scan speed 3Hz
• Calculation model for elastic modulus JKR (Johnson-Kendall-Roberts) theory Poisson's ratio of sample: 0.4 ⁇ Analysis software: Nano 3D Mapping (Shimadzu Corporation)
• a laminate was cut out, and a strip-shaped test piece 100 was prepared by previously peeling the first substrate and the second substrate by 15 mm in the long side direction so as to separate the laminate into the sealant layer side B and the substrate side A. Then, as shown in FIG. 19, the already peeled parts of the sealant layer side B and the substrate side A were each held by the gripper 110 of the measuring device. The gripper 110 was pulled at a speed of 50 mm/min in opposite directions in a direction perpendicular to the surface direction of the part where the sealant layer side B and the substrate side A are still laminated, and the average value of the tensile stress F in the stable region (see FIG. 20) was measured.
• FIG. 20 is a schematic diagram showing the change in the tensile stress F with respect to the interval S2 between the grippers 110.
• the change in tensile stress F with respect to the spacing S2 passes through a first region R1 and enters a second region R2, which has a smaller rate of change than the first region R1.
• the second region R2 is also called a stable region.
• the average value of the tensile stress F in the stable region R2 was measured for the five test pieces 100, and the average value was determined as the hot lamination strength of the first adhesive layer.
• the hot lamination strength of the second adhesive layer was also measured.
• the method for measuring the hot lamination strength of the second adhesive layer was the same as the method for measuring the hot lamination strength of the first adhesive layer, except that the second substrate and the sealant layer were peeled off from each other. The higher the hot lamination strength, the more the adhesive layer can follow the shrinkage of the first substrate, the second substrate, or the sealant layer during heat treatment, and the less likely delamination occurs due to heat treatment, and the less likely the sealability is to decrease.
• Example 5 For the laminate obtained in Example 5, a pouch was similarly produced and only retort sterilization was carried out under retort conditions of 121° C., 30 minutes, and 0.21 MPa. After retort sterilization, the laminate was cut out from the pouch to obtain a test piece, which was used to measure the oxygen transmission rate (cc/ m2 ⁇ day ⁇ atm) by the following method.
• the test piece was set so that the first substrate side was the oxygen supply side, and the oxygen permeability was measured in accordance with JIS K7126-2:2006 at a temperature of 23°C and a relative humidity of 90%. The results are shown in Table 1.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Food Science & Technology (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Laminated Bodies (AREA)
• Wrappers (AREA)

Priority Applications (3)

Applications Claiming Priority (4)

Publications (1)

Family

ID=92263059

Family Applications (1)

Country Status (4)

Citations (7)

• 2024
  • 2024-02-07 KR KR1020257028337A patent/KR20250148611A/ko active Pending
  • 2024-02-07 JP JP2024576895A patent/JPWO2024166966A1/ja active Pending
  • 2024-02-07 EP EP24753409.2A patent/EP4663407A1/en active Pending
  • 2024-02-07 WO PCT/JP2024/004202 patent/WO2024166966A1/ja not_active Ceased

Patent Citations (7)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events