Classifications

• • 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
  • B32B27/06—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
  • 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
  • B32B2255/205—Metallic 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
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/30—Properties of the layers or laminate having particular 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
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/514—Oriented
  • B32B2307/516—Oriented mono-axially
• • 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
  • B32B2307/518—Oriented bi-axially
• • 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
  • B32B2307/70—Other properties
  • B32B2307/724—Permeability to gases, adsorption
  • B32B2307/7242—Non-permeable
  • B32B2307/7244—Oxygen barrier
• • 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
  • B32B2307/70—Other properties
  • B32B2307/732—Dimensional properties
  • B32B2307/737—Dimensions, e.g. volume or area
  • B32B2307/7375—Linear, e.g. length, distance or width
  • B32B2307/7376—Thickness
• • 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

Definitions

• the present invention relates to a composite multilayer film, a multilayer structure containing the composite multilayer film, a packaging material containing the multilayer structure, a method for recovering the multilayer structure, and a recovered composition containing the recovered multilayer structure.
• Packaging materials for long-term food storage often require gas barrier properties, including oxygen barrier properties.
• gas barrier properties including oxygen barrier properties.
• Metal foils such as aluminum, metal deposition, and inorganic oxide deposition layers such as silicon oxide and aluminum oxide are widely used as layers that improve gas barrier properties.
• resin layers with gas barrier properties such as vinyl alcohol polymers and polyvinylidene chloride are also widely used. Vinyl alcohol polymers have the characteristic that they crystallize and become highly densified by hydrogen bonding between hydroxyl groups in the molecules, thereby exhibiting gas barrier properties.
• EVOH ethylene-vinyl alcohol copolymers
• Patent Document 1 ethylene-vinyl alcohol copolymers
• recycling post-consumer recycling
• the collected packaging materials are generally cut, separated and washed as necessary, and then melt-mixed using an extruder.
• Various molded products are manufactured using the pellets obtained in this way.
• the packaging material be composed of a single material as much as possible (mono-materialization), which allows for the production of high-purity, high-quality recycled resins.
• the first object of the present invention is to provide a composite multilayer film that has high gas barrier properties and that maintains stable gas barrier properties even after lamination, while being based on a polyolefin such as polyethylene that has low heat resistance and a low melting point.
• the second object of the present invention is to provide, using the composite multilayer film, a multilayer structure that is excellent in appearance, gas barrier properties and recyclability, a packaging material that includes the multilayer structure, a recovered composition that includes recovered material of the multilayer structure, and a recovery method thereof.
• the present inventors have intensively studied combinations of various resin compositions and laminate structures, and have found that by laminating an inorganic vapor deposition layer on the surface of the EVOH layer of a polyethylene-based multilayer film in which the EVOH layer is the outermost layer, and then laminating a specific protective layer, a composite multilayer film having high gas barrier properties and which stably exhibits this gas barrier property even after lamination can be obtained. Furthermore, they have found that by specifying the materials and lamination structure used for the composite multilayer film and other layers to be laminated therewith, a multilayer structure which combines appearance, gas barrier properties and recyclability can be obtained, and have completed the present invention.
• R 1 and R 2 each independently represent a single bond, an alkylene group having 1 to 9 carbon atoms, or an alkyleneoxy group having 1 to 9 carbon atoms, and the alkylene group and the alkyleneoxy group may contain a hydroxyl group, an alkoxy group, or a halogen atom.
• R 1 in the general formula (I) is a methylmethyleneoxy group and X is a hydrogen atom
• X is a hydrogen atom
• a composite multilayer film can be provided that has high gas barrier properties and that can be stably expressed even after lamination, even though it is mainly made of a polyolefin such as polyethylene that has low heat resistance and a low melting point.
• a multilayer structure that has excellent appearance and is compatible with gas barrier properties and recyclability, and a packaging material using the same can be provided.
• the multilayer structure has good recyclability, a recovered composition containing the recovered multilayer structure and a recovery method thereof can be provided.
• recyclability in this specification means that when the recovered multilayer structure or packaging material of the present invention is melt-kneaded to produce a recovered composition, gelation of the resin is suppressed, and a recovered composition with excellent appearance can be efficiently produced, and can be evaluated by a recovery test described in the examples.
• the composite multilayer film of the present invention has a layer (X) as the outermost layer, and has a structure in which layers (X), (Y), and (Z) are laminated adjacent to each other in this order.
• the composite multilayer film of the present invention has an inorganic layer (I) and a protective layer (P) on the exposed surface side of layer (X), and layer (X) is made of a resin composition (A) (hereinafter referred to as "resin composition (A)”) containing, as a main component, an ethylene-vinyl alcohol copolymer (a) (hereinafter sometimes referred to as "EVOH (a)”) having an ethylene unit content of 20 to 50 mol% and a saponification degree of 90 mol% or more.
• resin composition (A) herein composition (A)"
• EVOH (a) ethylene-vinyl alcohol copolymer having an ethylene unit content of 20 to 50 mol% and a saponification degree of 90 mol% or more.
• layer (Y) contains adhesive resin (B) (hereinafter may be referred to as “adhesive resin (B)”) having a melting point of less than 150°C as a main component
• layer (Z) contains polyolefin resin (C) (hereinafter may be referred to as “polyolefin resin (C)”) having a melting point of less than 150°C as a main component
• the resin composition (A) contains 40 to 500 ppm of alkali metal ions (b) and does not have a layer containing a resin having a melting point of 200°C or more as a main component and a metal layer having an average thickness of 1 ⁇ m or more.
• EVOH (a) has good affinity with inorganic layer (I), so by providing inorganic layer (I) on the exposed surface side of layer (X) of a multilayer film having layer (X) as the outermost layer, the composite multilayer film of the present invention can achieve high gas barrier properties. Furthermore, by providing protective layer (P) on inorganic layer (I) of such a configuration, stable gas barrier properties are exhibited even after lamination.
• the deterioration of gas barrier properties after lamination is an issue caused by layers (Y) and (Z) necessary for exhibiting good recyclability, and is an issue specific to the layer configuration of the composite multilayer film of the present invention, since layers (Y) and (Z) using materials with low melting points undergo dimensional changes due to the heat history during lamination, resulting in cracks in inorganic layer (I) and deterioration of gas barrier properties.
• both layers (Y) and (Z) contain a resin having a melting point of less than 150°C as a main component, and the polyolefin resin (C) and EVOH (a) contained in layer (Z) can be easily melt-mixed, so the composite multilayer film of the present invention having layers (X), (Y), and (Z) laminated adjacent to each other in this order is easy to recycle.
• good recyclability can be achieved by the resin composition (A) containing 40 to 500 ppm of alkali metal ions (b).
• layer (X), layer (Y), and layer (Z) are stacked adjacent to each other in this order
• layer (X), layer (Y), and layer (Z) are stacked adjacent layers are directly stacked, and specifically means that layer (X), layer (Y), and layer (Z) are stacked in this order, layer (X) and layer (Y) are directly stacked, and layer (Y) and layer (Z) are directly stacked.
• major component means a component that is contained in an amount of more than 50% by mass.
• the "average thickness" of each layer other than the inorganic layer (I) refers to the average value of thicknesses measured at any five positions.
• ppm means the content based on mass (ppm by mass).
• Polyethylene refers to a homopolymer of ethylene, a copolymer of 80 mol % or more ethylene and 20 mol % or less of an ⁇ -olefin monomer, and a copolymer of 90 mol % or more ethylene and less than 10 mol % of a non-olefin monomer whose functional group does not contain atoms other than carbon, oxygen, and hydrogen atoms.
• the term "acid-modified polyethylene” refers to a polymer obtained by modifying polyethylene with an acid.
• the acid-modified polyethylene may be a polymer in which at least one of an acid group and an acid anhydride group is introduced into polyethylene.
• polyethylene resin refers to polyethylene and modified polyethylene (such as acid-modified polyethylene).
• Modified polyethylene refers to a polymer obtained by modifying polyethylene.
• surface (or surface layer) in a multilayer structure does not mean to distinguish between the front and back, but refers to the exposed surface. In other words, a multilayer structure has two surfaces. Similarly, a multilayer structure has two outermost layers.
• the multilayer film constituting the composite multilayer film of the present invention has a layer (X) made of a resin composition (A) containing, as a main component, EVOH (a) having an ethylene unit content of 20 to 50 mol% and a saponification degree of 90 mol% or more, and containing 40 to 500 ppm of alkali metal ions (b) in an outermost layer.
• the content of EVOH (a) in the resin composition (A) is more than 50 mass%.
• the resin composition (A) may contain at least one polyvalent metal ion (c) selected from the group consisting of magnesium ions, calcium ions, and zinc ions, higher aliphatic carboxylic acid (d) having 8 to 30 carbon atoms, and other components described later. The details will be described below.
• EVOH (a) is usually obtained by saponifying an ethylene-vinyl ester copolymer obtained by polymerizing ethylene and a vinyl ester.
• the ethylene unit content of EVOH (a) is 20 to 50 mol%. When the ethylene unit content is 20 mol% or more, the melt moldability of EVOH (a) and the pulverized composite multilayer film containing EVOH (a) is improved.
• the ethylene unit content is preferably 23 mol% or more, more preferably 26 mol% or more, and may be 29 mol% or more. On the other hand, when the ethylene unit content is 50 mol% or less, the gas barrier property of the composite multilayer film of the present invention is improved.
• the ethylene unit content is preferably 46 mol% or less, more preferably 42 mol% or less, and may be 38 mol% or less.
• the saponification degree of EVOH (a) is 90 mol% or more.
• the saponification degree means the ratio of the number of vinyl alcohol units to the total number of vinyl alcohol units and vinyl ester units in EVOH (a).
• the degree of saponification is preferably 95 mol % or more, more preferably 99 mol % or more, and even more preferably 99.9 mol % or more.
• the ethylene unit content and degree of saponification of EVOH (a) are determined by 1 H-NMR measurement.
• EVOH (a) may be a mixture of two or more types of EVOH having different ethylene unit contents.
• the difference in ethylene unit content between the EVOHs having the most different ethylene unit contents is preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 15 mol% or less, and may be 3 mol% or more.
• EVOH (a) may be a mixture of two or more types of EVOH having different degrees of saponification.
• the difference in saponification degree between the EVOHs having the most different degrees of saponification is preferably 7% or less, more preferably 5% or less, and may be 0.5 mol% or more.
• EVOH (a-1) having an ethylene unit content of 24 mol% or more and less than 34 mol% and a degree of saponification of 99 mol% or more
• EVOH (a-2) having an ethylene unit content of 34 mol% or more and less than 50 mol% and a degree of saponification of 99 mol% or more in a blending mass ratio (a-1/a-2) of 60/40 to 90/10 and use the mixture as EVOH (a).
• EVOH (a) may be EVOH (a') having a melting point of less than 150°C.
• the melting point of EVOH (a') is less than 150°C, the appearance and interlayer adhesion of a multilayer film having a layer (X) mainly composed of EVOH (a') as the outermost layer can be improved.
• the reason for this is that the melting point of EVOH (a') is less than 150°C, which improves the fluidity of the polymer chain, and therefore stress can be effectively relieved even at a relatively low temperature during secondary processing such as melt molding and stretching, and the adhesive reaction activity with adjacent layers can be maintained.
• the melting point of EVOH (a') is preferably less than 140°C, more preferably less than 130°C, and may be less than 125°C or less than 120°C.
• the melting point of EVOH (a') is preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher.
• the melting point of EVOH (a') can be controlled by any one of the following methods or by a combination of two or more of them. In the present invention, the following method (3) can be preferably used.
• the primary hydroxyl group-containing modifying group used in (3) is preferably a primary hydroxyl group-containing modifying group represented by the following general formula (I).
• the degree of melting point reduction per introduction rate of the modifying group varies depending on the structure of the primary hydroxyl group-containing modifying group to be introduced, but the melting point generally decreases by about 6 to 9°C when 1 mol% of the primary hydroxyl group-containing modifying group represented by the following general formula (I) is introduced.
• the melting point When the melting point is controlled by this method, the melting point can be reduced while relatively maintaining the gas barrier property and thermal stability, and the decrease in interlayer adhesion with the layer (Y) and inorganic layer (I) described later is also suppressed, so that a composite multilayer film with particularly excellent quality and performance can be provided.
• the reason for this is thought to be that the melting point can be reduced while maintaining the amount of hydroxyl groups, and that the primary hydroxyl group has high adhesive reaction activity with the layer (Y) and inorganic layer (I) described later.
• the content of the primary hydroxyl-containing modifying group in EVOH (a') may be appropriately adjusted in consideration of the balance between the melting point and various physical properties, but in many cases, the balance of physical properties is good when the content is 2 mol% or more and less than 20 mol%.
• the lower limit of the content of the primary hydroxyl-containing modifying group in EVOH (a') is more preferably 4 mol%, and even more preferably 6 mol%.
• the upper limit of the content of the primary hydroxyl-containing modifying group in EVOH (a') is more preferably 15 mol%, and even more preferably 10 mol%.
• the primary hydroxyl-containing modifying group can be introduced by copolymerization or polymer reaction.
• X represents a hydrogen atom, a methyl group, or a group represented by R 2 -OH.
• R 1 and R 2 each independently represent a single bond, an alkylene group having 1 to 9 carbon atoms, or an alkyleneoxy group having 1 to 9 carbon atoms, and the alkylene group and the alkyleneoxy group may contain a hydroxyl group, an alkoxy group, or a halogen atom.
• X is preferably a hydrogen atom or a group represented by R 2 -OH, more preferably a hydrogen atom.
• R 1 is preferably a single bond, an alkylene group having 1 to 5 carbon atoms, or an alkyleneoxy group having 1 to 5 carbon atoms, more preferably a methylmethyleneoxy group.
• a unit in which X is a hydrogen atom and R 1 is a methylmethyleneoxy group can be obtained, for example, by post-modification, in which EVOH is reacted with epoxypropane.
• EVOH (a) may contain other monomer units other than ethylene units, vinyl ester units, vinyl alcohol units, and the modifying group containing the primary hydroxyl group, so long as the effect of the present invention is not impaired.
• the content of other monomer units is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and particularly preferably substantially none.
• Examples of such other monomers include ⁇ -olefins such as propylene, n-butene, isobutylene, and 1-hexene; acrylic acid and its salts; unsaturated monomers having an acrylic acid ester group; methacrylic acid and its salts; unsaturated monomers having a methacrylic acid ester group; acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidopropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts (e.g., quaternary salts); methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidopropanesulfonic acid and its salts, methacrylamidopropyldimethylamine and its salts (e.g., quaternary salts); methyl vinyl ether, ethyl vinyl
• vinyl ethers such as n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, and 2,3-diacetoxy-1-vinyloxypropane; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene halides such as vinylidene chloride and vinylidene fluoride; allyl compounds such as allyl acetate, 2,3-diacetoxy-1-allyloxypropane, and allyl chloride; unsaturated dicarboxylic acids and their salts or esters such as maleic acid, itaconic acid, and fumaric acid; vinyl silane compounds such as vinyltrimethoxysilane; isopropenyl acetate, 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-
• the MFR (190°C, under a load of 2.16 kg) of EVOH(a) measured in accordance with JIS K7210 (2014) is preferably 0.2 to 20 g/10 min.
• the MFR of EVOH(a) is more preferably 0.5 g/10 min or more, and even more preferably 0.8 g/10 min or more.
• the MFR of EVOH(a) is more preferably 15 g/10 min or less, even more preferably 10 g/10 min or less, even more preferably 5 g/10 min or less, and particularly preferably 3 g/10 min or less.
• the resin composition (A) contains 40 to 500 ppm of alkali metal ions (b).
• the resin composition (A) contains the alkali metal ions (b) in the above range, the interlayer adhesion with the layer (Y) described later tends to be significantly improved. If the alkali metal ions (b) are less than 40 ppm, the resin composition (A) is likely to thicken during melt molding, causing poor appearance such as gels and bumps, and the interlayer adhesion with the layer (Y) described later may decrease.
• the resin composition (A) may decompose excessively during melt molding, or coloring may become a problem.
• the content of the alkali metal ions (b) is less than 40 ppm, gelation of the resin cannot be suppressed when the multilayer structure or the recovered packaging material is melt-kneaded to produce the recovered composition, and the recyclability is deteriorated.
• the lower limit of the content of the alkali metal ion (b) is preferably 80 ppm, more preferably 120 ppm.
• the upper limit of the content of the alkali metal ion (b) is preferably 400 ppm, more preferably 300 ppm.
• alkali metal ion (b) examples include lithium, sodium, potassium, rubidium, and cesium ions, but sodium or potassium ions are preferred from the viewpoint of industrial availability.
• potassium ions may make it possible to achieve a high level of both the hue of the resin composition (A) and the interlayer adhesion with layer (Y), which will be described later. These ions may be used alone or in combination of two or more.
• alkali metal compounds that provide the alkali metal ion (b) include aliphatic carboxylates, aromatic carboxylates, carbonates, hydrochlorides, nitrates, sulfates, phosphates, hydroxides, and metal complexes of alkali metals such as lithium, sodium, and potassium.
• aliphatic carboxylates and phosphates are more preferred because they are easy to obtain and handle.
• aliphatic carboxylates acetates, caprylates, and stearates are preferred.
• the resin composition (A) preferably contains 10 to 300 ppm of at least one polyvalent metal ion (c) selected from the group consisting of magnesium ions, calcium ions, and zinc ions.
• the polyvalent metal ion (c) is contained in an amount of 10 ppm or more, the resin composition (A) tends to be able to suppress appearance defects such as thickening and the generation of gels or bumps during melt molding.
• the content of the polyvalent metal ion (c) is 300 ppm or less, the resin composition (A) tends to be able to suppress excessive decomposition and coloration during melt molding.
• the crosslinking reaction of the resin may progress during recycling, causing thickening and gelation, but by containing 10 ppm or more of the polyvalent metal ion (c), thickening, gelation, and adhesion of the resin to the screw are suppressed.
• the content of the polyvalent metal ion (c) is 300 ppm or less, the resin composition (A) tends to suppress the occurrence of defects during recycling while suppressing the deterioration of the hue during recycling.
• the content of the polyvalent metal ion (c) is preferably 20 to 200 ppm, more preferably 30 to 150 ppm.
• the resin composition (A) preferably contains magnesium ions or calcium ions as the polyvalent metal ion (c), more preferably magnesium ions.
• the melt moldability and coloring resistance of the obtained resin composition (A) can be further improved.
• polyvalent metal compounds that provide the polyvalent metal ion (c) include aliphatic carboxylates, aromatic carboxylates, carbonates, hydrochlorides, nitrates, sulfates, phosphates, hydroxides, and metal complexes of magnesium, calcium, and zinc.
• aliphatic carboxylates and hydroxides are more preferred because they are easy to obtain and handle.
• aliphatic carboxylates acetates, caprylates, and stearates are preferred.
• the resin composition (A) preferably contains 100 to 4000 ppm of a higher aliphatic carboxylic acid (d) having 8 to 30 carbon atoms.
• the higher aliphatic carboxylic acid (d) may be contained in part or in whole in the form of a salt, or may be contained as a salt of an alkali metal ion (b) or a polyvalent metal ion (c).
• the higher aliphatic carboxylic acid (d) is preferably caprylic acid or stearic acid.
• the multilayer film constituting the composite multilayer film of the present invention has a layer (X) made of the resin composition (A) as the outermost layer, and it is considered that the higher aliphatic carboxylic acid (d) acts as a lubricant with the die metal surface in the die, thereby suppressing the occurrence of poor appearance due to uneven thickness of the multilayer film and gels and bumps due to retained resin.
• the resin composition (A) preferably contains 100 ppm or more of the higher aliphatic carboxylic acid (d).
• the content of the higher aliphatic carboxylic acid (d) is 4000 ppm or less, thickening during melt molding of the resin composition (A) tends to be suppressed, and interlayer adhesion with the layer (Y) described below tends to be maintained. From these viewpoints, the content of the higher aliphatic carboxylic acid (d) is more preferably 200 to 3000 ppm, and even more preferably 300 to 2500 ppm.
• the resin composition (A) may contain other components other than EVOH (a), alkali metal ions (b), polyvalent metal ions (c) and higher aliphatic carboxylic acids (d) as long as the effects of the present invention are not impaired.
• other components include alkaline earth metal ions and transition metal ions other than polyvalent metal ions (c), carboxylic acids (monocarboxylic acids, polyvalent carboxylic acids) other than higher aliphatic carboxylic acids (d), thermoplastic resins other than EVOH (a), phosphoric acid compounds, boron compounds, oxidation promoters, antioxidants (hindered phenol compounds, etc.), plasticizers, heat stabilizers (melt stabilizers), photoinitiators, deodorants, ultraviolet absorbers, antistatic agents, lubricants, colorants, fillers, drying agents, bulking agents, pigments, dyes, processing aids, flame retardants, antifogging agents, etc.
• the melt viscosity of the resin composition (A) and the pulverized product of the multilayer structure containing the resin composition (A) can be controlled.
• the resin composition (A) preferably contains a carboxylic acid other than the higher aliphatic carboxylic acid (d).
• the lower limit of the carboxylic acid content is preferably 50 ppm, more preferably 100 ppm.
• the upper limit of the carboxylic acid content is preferably 400 ppm, more preferably 350 ppm.
• the carboxylic acid content is 50 ppm or more, the coloring resistance tends to be good.
• the carboxylic acid content is 400 ppm or less, the interlayer adhesion tends to be maintained and the generation of odor tends to be suppressed.
• the carboxylic acid may be a monocarboxylic acid. These may be used alone or in combination of two or more.
• These carboxylic acids may further have a substituent such as a hydroxyl group, an amino group, or a halogen atom. Among these, acetic acid is preferred because of its high safety and ease of availability and handling.
• the carboxylic acid may be a polycarboxylic acid.
• the carboxylic acid is a polycarboxylic acid
• the color resistance of the resin composition (A) at high temperatures and the color resistance of the melt-molded product of the crushed product of the resulting multilayer structure may be further improved.
• the polycarboxylic acid compound has three or more carboxyl groups. In this case, color resistance may be more effectively improved.
• a polycarboxylic acid is a compound having two or more carboxyl groups in the molecule.
• the pKa of at least one carboxyl group is in the range of 3.5 to 5.5
• the resin composition (A) may further contain a phosphoric acid compound.
• the lower limit of the content of the phosphoric acid compound is preferably 5 ppm in terms of phosphoric acid radicals.
• the upper limit of the content of the phosphoric acid compound is preferably 100 ppm in terms of phosphoric acid radicals.
• the phosphate compound various acids such as phosphoric acid and phosphorous acid and their salts can be used.
• the phosphate may be any of primary phosphate, secondary phosphate, and tertiary phosphate.
• the cationic species of the phosphate is not particularly limited, but the cationic species is preferably an alkali metal or an alkaline earth metal.
• the phosphate compound is preferably sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate.
• the resin composition (A) may further contain a boron compound.
• the lower limit of the content in the resin composition (A) is preferably 50 ppm, more preferably 100 ppm, in terms of boron element.
• the upper limit of the content of the boron compound in the resin composition (A) is preferably 400 ppm, more preferably 200 ppm, in terms of boron element.
• drawdown resistance and neck-in resistance during film formation may be improved, and the mechanical properties of the resulting molded product may be improved. It is speculated that these effects are due to the occurrence of a chelate interaction between the EVOH (a) and the boron compound.
• boron compounds include boric acid, boric acid esters, borate salts, and boron hydrides.
• Specific examples include boric acids such as orthoboric acid ( H3BO3 ), metaboric acid, and tetraboric acid; boric acid esters such as trimethyl borate and triethyl borate; alkali metal salts or alkaline earth metal salts of the boric acid, and borate salts such as borax.Of these, orthoboric acid is preferred.
• the resin composition (A) may further contain a hindered phenol-based compound as an antioxidant.
• a hindered phenol-based compound as an antioxidant.
• the content of the hindered phenol-based compound in the resin composition (A) is preferably 1000 to 10000 ppm.
• the content of the hindered phenol-based compound is more preferably 2000 ppm or more.
• the content of the hindered phenol-based compound is 10000 ppm or less, coloring and bleed-out derived from the hindered phenol-based compound can be suppressed.
• the content of the hindered phenol-based compound is more preferably 8000 ppm or less.
• Hindered phenol compounds have at least one hindered phenol group.
• a hindered phenol group is one in which a bulky substituent is bonded to at least one of the carbons adjacent to the carbon to which the phenol hydroxyl group is bonded.
• the bulky substituent an alkyl group having 1 to 10 carbon atoms is preferred, and a t-butyl group is more preferred.
• the hindered phenol compound is in a solid state near room temperature.
• the melting point or softening temperature of the hindered phenol compound is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher.
• the molecular weight of the hindered phenol compound is preferably 200 or higher, more preferably 400 or higher, and even more preferably 600 or higher. Meanwhile, the molecular weight is usually 2000 or lower.
• the melting point or softening temperature of the hindered phenol compound is preferably 200°C or lower, more preferably 190°C or lower, and even more preferably 180°C or lower.
• the hindered phenol compound preferably has an ester bond or an amide bond.
• Examples of hindered phenol compounds having an ester bond include esters of aliphatic carboxylic acids having a hindered phenol group and aliphatic alcohols, and examples of hindered phenol compounds having an amide bond include amides of aliphatic carboxylic acids having a hindered phenol group and aliphatic amines. Of these, it is preferable that the hindered phenol compound has an amide bond.
• hindered phenol compounds having an ester bond or an amide bond include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] available commercially as Irganox 1010 from BASF, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)stearyl propionate available commercially as Irganox 1076, 2,2'-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] available commercially as Irganox 1035, and 2,2'-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] available commercially as Irganox 1135.
• octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate available commercially under the trade name Irganox 245; ethylene bis(oxyethylene) bis(3-tert-butyl-4-hydroxy-5-methylbenzenepropanoate), available commercially under the trade name Irganox 245; 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], available commercially under the trade name Irganox 259; and N,N'-hexamethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], available commercially under the trade name Irganox 1098.
• the resin composition (A) may further contain a thermoplastic resin other than EVOH (a).
• thermoplastic resins other than EVOH (a) include various polyolefins (polyethylene, polypropylene, poly1-butene, poly4-methyl-1-pentene, ethylene-propylene copolymers, copolymers of ethylene and ⁇ -olefins having 4 or more carbon atoms, copolymers of polyolefins and maleic anhydride, ethylene-vinyl ester copolymers, ethylene-acrylic acid ester copolymers, or modified polyolefins obtained by graft-modifying these with unsaturated carboxylic acids or their derivatives, etc.), various polyamides (nylon 6, nylon 6.6, nylon 6/66 copolymer, nylon 11, nylon 12, polymetaxylylene adipamide, etc.), various polyesters (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc
• the content of the thermoplastic resin in the resin composition (A) is usually less than 40% by mass, preferably less than 30% by mass, more preferably less than 20% by mass, even more preferably less than 10% by mass, and may be less than 5% by mass or even less than 1% by mass, and it is particularly preferable that the resin composition is substantially free of the thermoplastic resin.
• the proportion of EVOH (a) in the resin constituting the resin composition (A) is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, and the resin constituting the resin composition (A) may be substantially EVOH (a) alone.
• the proportion of EVOH (a) in the resin composition (A) is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, and may be 98% by mass or more or 99% by mass or more, and the resin composition (A) may be substantially composed of only EVOH (a) and alkali metal ions (b).
• the method for producing the resin composition (A) is not particularly limited, but it can be produced by melt-kneading EVOH (a) and alkali metal ions (b), and other components such as polyvalent metal ions (c) and higher aliphatic carboxylic acids (d) as necessary.
• Each component may be blended in a solid state such as powder, or as a melt, or may be blended as a solute contained in a solution or a dispersoid contained in a dispersion.
• As the solution and dispersion an aqueous solution and an aqueous dispersion are preferable, respectively.
• melt-kneading a known mixing or kneading device such as a kneader-ruder, an extruder, a mixing roll, or a Banbury mixer can be used.
• the temperature range during melt-kneading can be appropriately adjusted depending on the EVOH (a) used and the melting points of each component, and is usually 150 to 250°C.
• it may be produced by adding some components to EVOH (a) in advance and then melt-kneading other components that are required as additional components as described above.
• An example of a method for adding some components to EVOH (a) in advance is a method in which EVOH (a) is immersed as pellets or powder in a solution in which the added components are dissolved.
• An aqueous solution is preferred as the solution.
• the composite multilayer film of the present invention has a layer (Y) containing an adhesive resin (B) having a melting point of less than 150° C. as a main component.
• a composite multilayer film having excellent appearance and interlayer adhesion tends to be obtained.
• the composite multilayer film of the present invention contains the layer (Y)
• the compatibility between the layer (X) and the layer (Z) is improved during recycling, so that the recyclability tends to be improved.
• Examples of the adhesive resin (B) include a carboxylic acid-modified polyolefin resin obtained by graft-polymerizing an unsaturated carboxylic acid or its derivative such as maleic anhydride to a polyolefin resin.
• the melting point of the adhesive resin (B) mainly depends on the polyolefin resin before the carboxylic acid modification.
• the contents described for the polyolefin resin (C) described later can be applied as they are to the polyolefin resin.
• the proportion of the carboxylic acid-modified polyolefin resin in the adhesive resin (B) is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 95% by mass or more, and may be substantially composed of only the carboxylic acid-modified polyolefin resin.
• the proportion of the adhesive resin (B) in the layer (Y) is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 95% by mass or more, and may be substantially composed of only the adhesive resin (B).
• the composite multilayer film of the present invention has a layer (Z) containing a polyolefin resin (C) having a melting point of less than 150° C. as a main component.
• the polyolefin resin (C) is not particularly limited as long as it is a polyolefin having a melting point of less than 150° C., and examples thereof include polyethylene-based resins such as linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, and high-density polyethylene; vinyl ester resins; ethylene-propylene copolymers; propylene- ⁇ -olefin copolymers ( ⁇ -olefins having 4 to 20 carbon atoms); olefins such as polybutene and polypentene, or copolymers thereof; and chlorinated polyethylene.
• polyethylene-based resins such as linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, and high-density polyethylene
• vinyl ester resins ethylene-propylene copolymers
• propylene- ⁇ -olefin copolymers ⁇ -olefins having 4 to 20 carbon
• the polyolefin resin (C) preferably contains a polyethylene-based resin as a main component, and more preferably is a polyethylene-based resin.
• Polyethylene-based resins are widely used in packaging materials regardless of whether they have gas barrier properties, and therefore recycling infrastructures for them have been widely established in various countries.
• the polyethylene-based resin is preferably at least one selected from linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, and high-density polyethylene, and more preferably at least one selected from linear low-density polyethylene and low-density polyethylene, or a mixture of at least one selected from linear low-density polyethylene and low-density polyethylene and high-density polyethylene.
• the melting point of the polyolefin resin (C) is preferably less than 140°C, more preferably less than 130°C.
• the melting point of the polyolefin resin (C) is preferably 80°C or higher, more preferably 90°C or higher.
• melt flow rate (MFR) (190°C, under a load of 2160 g) of the polyolefin resin (C) measured in accordance with the method described in JIS K7210 (2014) is preferably 0.1 to 30 g/10 min, more preferably 0.3 to 25 g/10 min, and even more preferably 0.5 to 20 g/10 min.
• the polyolefin resin (C) preferably contains a polyethylene resin as a main component, and the content of the polyethylene resin in the polyolefin resin (C) is more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 95% by mass or more, and the polyolefin resin (C) may be substantially composed of only polyethylene resin.
• the proportion of the polyolefin resin (C) in the layer (Z) is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 95% by mass or more, and the polyolefin resin (C) may be substantially composed of only polyolefin resin (C).
• Layer (Y) and layer (Z) contain adhesive resin (B) and polyolefin resin (C) as main components, respectively, but these layers may contain other components such as antioxidants, plasticizers, heat stabilizers (melt stabilizers), photoinitiators, deodorants, UV absorbers, antistatic agents, lubricants, colorants, fillers, desiccants, bulking agents, pigments, dyes, processing aids, flame retardants, and antifogging agents, so long as the effects of the present invention are not impaired.
• additive resin (B) and polyolefin resin (C) as main components, respectively, but these layers may contain other components such as antioxidants, plasticizers, heat stabilizers (melt stabilizers), photoinitiators, deodorants, UV absorbers, antistatic agents, lubricants, colorants, fillers, desiccants, bulking agents, pigments, dyes, processing aids, flame retardants, and antifogging agents, so long as the effects of the present invention are not impaired.
• the total amount of these components is less than 50% by mass for each layer, preferably less than 40% by mass, more preferably less than 30% by mass, even more preferably less than 20% by mass, and particularly preferably less than 10% by mass, and may be less than 5% by mass, less than 3% by mass, or less than 1% by mass.
• the multilayer film constituting the composite multilayer film of the present invention has a structure in which at least layer (X), layer (Y) and layer (Z) are laminated adjacent to each other in this order, with layer (X) being the outermost layer.
• the multilayer film may have a plurality of layers each of layer (X), layer (Y) and layer (Z).
• Examples of the layer structure of the multilayer film of the present invention include X/Y/Z, X/Y/Z/Y/X, X/Y/Z/Y/X/Y/Z/Y/X/Y/X, etc., where layer (X) is represented by X, layer (Y) is represented by Y and layer (Z) is represented by Z, and "/" indicates that the layers are directly laminated.
• the average thickness of layer (X) in the multilayer film is 0.2 ⁇ m or more and less than 20 ⁇ m. It is also preferable that the ratio of the average thickness of layer (X) to the total average thickness of the multilayer film is less than 25%.
• the average thickness of layer (X) is more preferably 0.4 ⁇ m or more and less than 16 ⁇ m, and even more preferably 0.6 ⁇ m or more and less than 12 ⁇ m.
• the ratio of the average thickness of layer (X) to the total average thickness of the multilayer film is more preferably less than 20%, and even more preferably less than 15%.
• the average thickness of layer (Y) in the multilayer film is 0.2 ⁇ m or more and less than 20 ⁇ m. It is also preferable that the ratio of the average thickness of layer (Y) to the total average thickness of the multilayer film is less than 25%.
• the average thickness of layer (Y) is more preferably 0.4 ⁇ m or more and less than 16 ⁇ m, and even more preferably 0.6 ⁇ m or more and less than 12 ⁇ m.
• the ratio of the average thickness of layer (Y) to the total average thickness of the multilayer film is more preferably less than 20%, and even more preferably less than 15%.
• the average thickness of the layer (Z) of the multilayer film is preferably 1 ⁇ m or more and less than 200 ⁇ m. It is also preferable that the ratio of the average thickness of the layer (Z) to the total average thickness of the multilayer film is more than 55%.
• the average thickness of the layer (Z) is more preferably 5 ⁇ m or more, even more preferably 10 ⁇ m or more, and may be 20 ⁇ m or more.
• the average thickness of the layer (Z) is more preferably 100 ⁇ m or less, and may be 50 ⁇ m or less.
• the ratio of the average thickness of the layer (Z) to the total average thickness of the multilayer film is more preferably more than 60%, and even more preferably more than 70%.
• the average thickness of the multilayer film is usually 10 ⁇ m or more and less than 200 ⁇ m, and preferably 10 ⁇ m or more and less than 150 ⁇ m.
• the average thickness of the stretched multilayer film is preferably 10 ⁇ m or more and less than 50 ⁇ m, and more preferably less than 40 ⁇ m.
• the multilayer film may be a non-stretched multilayer film, or may be a stretched multilayer film stretched uniaxially or biaxially (at least uniaxially).
• a non-stretched multilayer film it has excellent impact resistance and can be suitably used as a heat-sealed film.
• stretching in a uniaxial or biaxial direction can improve the mechanical properties and gas barrier properties of the resulting multilayer film.
• the multilayer film is preferably a uniaxially stretched multilayer film, and from the viewpoint of obtaining a film with little anisotropy in the mechanical properties and a strong film, the multilayer film is preferably a biaxially stretched multilayer film.
• the multilayer film is stretched at least 3 times and less than 12 times in a uniaxial direction.
• the multilayer film is stretched uniaxially by 3 times and less than 12 times, and more preferably by 4 times and less than 10 times.
• a biaxially stretched multilayer film it is preferably stretched 3 times or more but less than 12 times in each of the two axial directions, and more preferably 4 times or more but less than 10 times.
• the method for producing the multilayer film is not particularly limited, but generally, a conventional coextrusion method can be used in which each resin is extruded from a separate die or a common die and laminated.
• a circular die or a T-die can be used as the die.
• the method for stretching in the uniaxial or biaxial direction is also not particularly limited, and the film can be produced by stretching in the flow direction of the film and/or the direction perpendicular to the flow direction, i.e., the width direction, using a conventionally known stretching method such as roll-type uniaxial stretching, tubular-type simultaneous biaxial stretching, tenter-type sequential biaxial stretching, and tenter-type simultaneous biaxial stretching.
• the effects of the present invention are particularly pronounced in the case of a multilayer film produced by tenter-type sequential biaxial stretching.
• the temperature during stretching is usually 40 to 150°C, more preferably 50 to 140°C, and may be 60 to 130°C.
• the multilayer film constituting the composite multilayer film of the present invention has the advantage that problems such as poor appearance and reduced interlayer adhesion after stretching are unlikely to occur even when the stretching temperature is relatively low, such as 120°C. If necessary, after the stretching process, it is preferable to carry out a heat treatment at a temperature equal to or higher than the glass transition point and lower than the melting point to increase the crystallinity and fix the orientation of the molecular chains, which is called a heat setting operation.
• the composite multilayer film of the present invention includes an inorganic layer (I) and a protective layer (P) on the exposed surface side of the layer (X) of the multilayer film.
• the inorganic layer (I) is preferably laminated directly or via another layer such as an adhesive layer on the exposed surface side of the layer (X) of the multilayer film, and more preferably laminated directly on the exposed surface side of the layer (X).
• the inorganic layer (I) means a layer made of an inorganic substance such as a metal or an inorganic oxide and having gas barrier properties against oxygen and water vapor.
• the layer (X) has a higher affinity with metals and inorganic oxides than ordinary thermoplastic resins, and can form a dense and defect-free inorganic layer (I), and the interlayer adhesion between the layer (X) and the inorganic layer (I) in the obtained composite multilayer film is good.
• the layer (X) has gas barrier properties, even when defects occur in the inorganic layer (I) due to bending or the like, the deterioration of the gas barrier properties can be suppressed.
• the average thickness of the inorganic layer (I) is generally less than 500 nm. When the average thickness is less than 500 nm, the viscosity is stable when the pulverized product of the multilayer structure including the inorganic layer (I) is melt-molded, and the generation of gels or lumps can be suppressed.
• the inorganic layer (I) is preferably an inorganic vapor deposition layer, and is preferably either a metal vapor deposition layer containing aluminum as a main component or an inorganic oxide vapor deposition layer containing alumina or silica as a main component.
• a metal vapor deposition layer is preferable when light blocking properties are to be imparted, but an inorganic oxide vapor deposition layer is preferable from the viewpoints of visibility of the contents as a packaging material, microwave suitability, and suppression of the generation of gels and bumps when pulverized materials are melt-molded.
• an inorganic oxide vapor deposition layer is preferable from the viewpoint of suppressing coloring during recycling of the multilayer structure of the present invention.
• the decrease in gas barrier properties after lamination is more significant with an inorganic oxide vapor deposition layer than with a metal vapor deposition layer when the protective layer (P) is not provided, while when the protective layer (P) is used, there is no significant difference in gas barrier properties after lamination between a metal vapor deposition layer and an inorganic oxide vapor deposition layer. Therefore, it can be said that the effect of applying the present invention is more significant when an inorganic oxide vapor deposition layer is used.
• the metal vapor deposition layer is a layer containing aluminum as the main component.
• the content of aluminum atoms in the metal vapor deposition layer is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more.
• the average thickness of the metal vapor deposition layer is preferably 120 nm or less, more preferably 100 nm or less, and even more preferably 90 nm or less.
• the average thickness of the metal vapor deposition layer is preferably 25 nm or more, more preferably 35 nm or more, and even more preferably 45 nm or more.
• the average thickness of the metal vapor deposition layer is the average thickness at any 10 points on the cross section of the metal vapor deposition layer measured by an electron microscope.
• the light transmittance at a wavelength of 600 nm can be 10% or less, and the film has excellent light blocking properties.
• oxidation occurs irreversibly and aluminum oxide may be partially contained.
• the molar ratio of the oxygen atom content to the aluminum atom content is preferably 0.5 or less, more preferably 0.3 or less, and even more preferably 0.1 or less.
• the inorganic oxide deposition layer is an inorganic oxide, such as an oxide of silicon, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, yttrium, etc., preferably alumina or silica.
• the average thickness of the inorganic oxide deposition layer is preferably 150 nm or less, more preferably 110 nm or less, and from the viewpoint of recyclability, 80 nm or less or 60 nm or less may be preferable.
• the average thickness of the inorganic oxide deposition layer is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more.
• the average thickness of the inorganic oxide deposition layer is the average thickness at any 10 points on the cross section of the inorganic oxide deposition layer measured by an electron microscope.
• the light transmittance at a wavelength of 600 nm can be 80% or more, and the visibility of the contents when used as a packaging material is excellent. From the viewpoint of further improving visibility, the light transmittance at a wavelength of 600 nm is more preferably 90% or more.
• the light transmittance can be increased, for example, by suppressing unevenness in the thickness of the multilayer film used in the production of the composite multilayer film.
• One way to further suppress unevenness in the thickness of the multilayer film is to stretch it in at least one axial direction.
• the light transmittance of the multilayer film at a wavelength of 600 nm is preferably 80% or more, and more preferably 90% or more.
• the inorganic layer (I) can be formed by a known physical vapor deposition method or chemical vapor deposition method. Specifically, examples of the method include vacuum vapor deposition, sputtering, ion plating, ion beam mixing, plasma CVD, laser CVD, MO-CVD, and thermal CVD. It is preferable to use a physical vapor deposition method, and particularly preferable to use a vacuum vapor deposition method.
• the upper limit of the surface temperature of the layer (X) during the formation of the inorganic layer (I) is preferably 60°C, more preferably 55°C, and even more preferably 50°C.
• the lower limit of the surface temperature of the layer (X) during the formation of the inorganic layer (I) is not particularly limited, but is preferably 0°C, more preferably 10°C, and even more preferably 20°C.
• the exposed surface of the layer (X) may be plasma-treated.
• the plasma treatment can be performed by a known method, and atmospheric pressure plasma treatment is preferable.
• nitrogen, helium, neon, argon, krypton, xenon, radon, etc. are used as a discharge gas.
• nitrogen, helium, and argon are preferably used, with nitrogen being particularly preferred due to its ability to reduce costs.
• the composite multilayer film of the present invention comprises an inorganic layer (I) and a protective layer (P) on the surface side of the layer (X) of the multilayer film.
• the protective layer (P) is preferably directly laminated on the inorganic layer (I). That is, the layer structure is preferably such that the layer (X), the inorganic layer (I) and the protective layer (P) are directly laminated in this order.
• the protective layer (P) has the effect of improving the stability of the gas barrier property of the multilayer structure by suppressing the deterioration of the barrier property in a converting process such as printing or lamination.
• the protective layer (P) itself does not need to have gas barrier property, but it is preferable that it has gas barrier property.
• the protective layer (P) may be made of a resin composition containing at least one metal compound selected from the group consisting of metal alkoxides, hydrolysates of metal alkoxides, and hydrolysis condensates of metal alkoxides, and a water-soluble resin.
• the metal alkoxide is represented by the general formula: R 1 n M(OR 2 ) m (wherein M is a metal atom, R 1 and R 2 are organic groups having 1 to 8 carbon atoms, n is 0 or more, m is an integer of 1 or more, and n+m represents the atomic valence of M), and at least one of the metal alkoxides, partial hydrolysates of metal alkoxides, or hydrolysis condensates of metal alkoxides can be used.
• the metal atom represented by M can be silicon, zirconium, titanium, aluminum, etc., and is preferably silicon.
• organic group R1 examples include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, n-hexyl, and n-octyl.
• organic group R2 examples include methyl, ethyl, n-propyl, i-propyl, n-butyl, and sec-butyl. These alkyl groups may be the same or different in the same molecule.
• alkoxysilanes in which M in the above general formula is silicon (Si) are preferred, and the alkoxysilanes are represented by Si(ORa) 4 , where Ra is a lower alkyl group.
• Ra a methyl group, an ethyl group, an n-propyl group, an n-butyl group, etc.
• specific examples of the alkoxysilane include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.
• alkylalkoxysilanes Rb n Si(ORc) 4-n can be used (n is an integer of 1, 2, or 3).
• Rb and Rc a methyl group, an ethyl group, etc. are used, and specific examples of the alkylalkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane.
• These alkoxysilanes and alkylalkoxysilanes can be used alone or in combination of two or more kinds.
• condensation polymers of alkoxysilanes can also be used, and specific examples include polytetramethoxysilane, polytetraethoxysilane, and the like.
• a silane coupling agent may be used in combination with the above alkoxide.
• a known organoalkoxysilane containing an organic reactive group may be used.
• organoalkoxysilanes having an epoxy group or an amino group are suitable.
• silane coupling agents examples include ⁇ -glycidoxypropyltrimethoxysilane, ⁇ -glycidoxypropylmethyldiethoxysilane, ⁇ -(3,4-epoxycyclohexyl)ethyltrimethoxysilane, ⁇ -aminopropyltrimethoxysilane, and ⁇ -aminopropyltriethoxysilane. Two or more of these silane coupling agents may be mixed and used. The amount of such silane coupling agent used is within the range of 0.1 to 20 parts by mass per 100 parts by mass of the above alkoxysilane.
• water-soluble resins include resins having hydroxyl groups such as polyvinyl alcohol and poly(2-hydroxyethyl methacrylate), resins having carboxyl groups such as polyacrylic acid and carboxymethyl cellulose, resins having amino groups such as polyallylamine and polyethyleneimine, resins having amide groups such as polyacrylamide, poly N,N-dimethylacrylamide and poly N-isopropylacrylamide, resins having sulfonic acid groups such as polystyrene sulfonic acid and polyvinyl sulfonic acid, resins having polyether groups such as polyethylene oxide and polyethylene glycol, and polyvinylpyrrolidone, polyoxazoline, etc.
• resins having hydroxyl groups such as polyvinyl alcohol and poly(2-hydroxyethyl methacrylate)
• resins having carboxyl groups such as polyacrylic acid and carboxymethyl cellulose
• resins having amino groups such as polyallylamine and polyethyleneimine
• resins having amide groups
• resins having hydrogen bond groups are preferred, resins having hydroxyl groups, resins having amide groups, resins having polyether groups, polyvinylpyrrolidone, polyoxazoline, etc. are more preferred, resins having hydroxyl groups are even more preferred, and polyvinyl alcohol is particularly preferred.
• Polyvinyl alcohol may be one or more compounds selected from the group consisting of copolymers containing vinyl alcohol units such as ethylene-vinyl alcohol copolymers. These may be used alone or in combination of two or more.
• Polyvinyl alcohol may be a homopolymer of vinyl alcohol or a copolymer containing other monomer units.
• the number average degree of polymerization is usually 50 or more and 5,000 or less.
• the mass ratio of at least one metal compound selected from the group consisting of metal alkoxides, hydrolysates of metal alkoxides, and hydrolyzed condensates of metal alkoxides to the water-soluble resin is preferably 55/45 to 95/5, more preferably 65/35 to 90/10, and even more preferably 75/25 to 85/15.
• the resin composition contains a hydrolyzed condensate of a silane alkoxide and polyvinyl alcohol.
• the proportion of the total mass of the metal compound and the water-soluble resin in the protective layer (P) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more, and the protective layer (P) may essentially consist of only the metal compound and the water-soluble resin.
• the protective layer (P) made of the above resin composition is specifically laminated, for example, as follows.
• a coating liquid is prepared by mixing a metal alkoxide, a water-soluble resin, a sol-gel catalyst, an acid, water, an organic solvent, etc.
• hydrolysis and polycondensation reactions of the metal alkoxide gradually proceed in the above coating liquid.
• the above coating liquid can be applied and dried by a conventional method on the exposed surface side of the inorganic layer (I) to laminate it.
• the protective layer (P) may be made of a composition containing polyurethane resin as a main component.
• the protective layer (P) containing polyurethane resin as a main component has a small adverse effect on recyclability and tends to produce high-quality recovered resin.
• the polar group of the urethane bond interacts with the inorganic layer (I) and has flexibility due to the presence of amorphous parts, so that damage to the inorganic layer (I) can be suppressed even when dimensional changes or bending loads are applied, which is preferable.
• the acid value of the urethane resin is preferably in the range of 10 to 60 mg KOH/g.
• the glass transition temperature (Tg) of the urethane resin is preferably 80°C or higher, and more preferably 90°C or higher. By setting the Tg at 80°C or higher, it is possible to effectively prevent the deterioration of the gas barrier properties of the composite multilayer film during the converting process.
• a urethane resin that contains an aromatic or araliphatic diisocyanate component as the main component.
• component in relation to urethane resin means the structural unit (constituent) that constitutes the urethane resin.
• a urethane resin that contains a metaxylylene diisocyanate component it is particularly preferable to use a urethane resin that contains a metaxylylene diisocyanate component.
• the proportion of aromatic or araliphatic diisocyanate in the urethane resin is preferably in the range of 50 mol% or more (50 to 100 mol%) out of 100 mol% of the polyisocyanate component.
• the total proportion of aromatic or araliphatic diisocyanate is preferably 60 to 100 mol%, more preferably 70 to 100 mol%, and even more preferably 80 to 100 mol%.
• the "Takelac (registered trademark) WPB" series commercially available from Mitsui Chemicals, Inc. can be suitably used.
• the protective layer (P) itself tends to exhibit good gas barrier properties.
• the urethane resin preferably has a carboxylic acid group (carboxyl group) from the viewpoint of improving affinity with the inorganic layer (I).
• a carboxylic acid (salt) group for example, a polyol compound having a carboxylic acid group, such as dimethylolpropionic acid or dimethylolbutanoic acid, may be introduced as a copolymerization component as a polyol component.
• a urethane resin containing a carboxylic acid group it is possible to obtain a urethane resin in a water dispersion by neutralizing it with a salt-forming agent.
• salt-forming agents include ammonia, trialkylamines such as trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, and tri-n-butylamine, N-alkylmorpholines such as N-methylmorpholine and N-ethylmorpholine, and N-dialkylalkanolamines such as N-dimethylethanolamine and N-diethylethanolamine. These may be used alone or in combination of two or more.
• trialkylamines such as trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, and tri-n-butylamine
• N-alkylmorpholines such as N-methylmorpholine and N-ethylmorpholine
• N-dialkylalkanolamines such as N-dimethylethanolamine and N-diethylethanolamine.
• the protective layer (P) made of the above composition can be laminated on the exposed surface of the inorganic layer (I) by applying and drying a coating liquid, which is an aqueous solution or aqueous dispersion of a urethane resin, in a conventional manner.
• a coating liquid which is an aqueous solution or aqueous dispersion of a urethane resin
• the protective layer (P) of the present invention may contain crosslinking agents, other polymers, tackifiers, inorganic particles, pigments, dyes, etc. to further improve performance depending on the purpose.
• Crosslinking agents that can be used include self-crosslinking agents, compounds having multiple reactive functional groups in the molecule, and metals having polyvalent coordination sites. Specific examples include oxazoline group-containing compounds, isocyanate group-containing compounds, epoxy group-containing compounds, carbodiimide group-containing compounds, melamine compounds, urea compounds, zirconium salt compounds, and silane coupling agents, and multiple compounds may be used in combination as necessary. Among these, from the viewpoint of ease of handling, oxazoline group-containing compounds, isocyanate group-containing compounds, and epoxy group-containing compounds are preferred.
• the oxazoline group-containing compound is not particularly limited as long as it has at least two oxazoline groups in the molecule.
• examples include compounds having oxazoline groups such as 2,2'-bis(2-oxazoline), 2,2'-ethylene-bis(4,4'-dimethyl-2-oxazoline), 2,2'-p-phenylene-bis(2-oxazoline), and bis(2-oxazolinylcyclohexane) sulfide, and oxazoline group-containing polymers.
• oxazoline group-containing polymers are preferred because of their ease of handling.
• Oxazoline group-containing polymers can be obtained by polymerizing addition-polymerizable oxazolines such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, and 2-isopropenyl-2-oxazoline. Other monomers may be copolymerized into the oxazoline group-containing polymer as necessary. There are no particular limitations on the polymerization method for the oxazoline group-containing polymer, and any known polymerization method can be used.
• oxazoline group-containing polymers include the Epocross series manufactured by Nippon Shokubai Co., Ltd., such as the water-soluble types “WS-500” and “WS-700” and the emulsion types "K-1010E”, “K-1020E”, “K-1030E”, “K-2010E”, “K-2020E”, and “K-2030E”.
• the isocyanate group-containing compound is not particularly limited as long as it has at least two isocyanate groups in the molecule.
• Polyfunctional isocyanate compounds such as isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane, 4,4'-diisocyanatodicyclohexylmethane, hexahydrotoluene 2,4- or 2,6-diisocyanate, perhydro-2,4'- or 4,4'-diphenylmethane diisocyanate, naphthalene 1,5-diisocyanate, xylylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, and tetramethylxylylene diisocyanate, or modified products thereof, are included.
• the modified product is obtained by modifying a diisocyanate of a polyfunctional isocyanate compound by a known method, and examples thereof include polyfunctional isocyanate compounds having an allophanate group, a biuret group, a carbodiimide group, a uretonimine group, a uretdione group, an isocyanurate group, etc., and further an adduct-type polyfunctional isocyanate compound modified with a polyfunctional alcohol such as trimethylolpropane.
• the above isocyanate group-containing compound may contain monoisocyanate in a range of 20% by mass or less. In addition, one or more of these can be used.
• Isocyanate group-containing compounds can typically be obtained by reacting a polyfunctional isocyanate compound with a monovalent or polyvalent nonionic polyalkylene ether alcohol.
• aqueous polyfunctional isocyanate compounds include Bayhydur 3100, Bayhydur VPLS2150/1, SBU Isocyanate L801, Desmodur N3400, Desmodur VPLS2102, Desmodur VPLS2025/1, SBU Isocyanate 0772, and Desmodur DN, all manufactured by Sumitomo Bayer Urethane Co., Ltd.; Takenate WD720, Takenate WD725, and Takenate WD730, all manufactured by Takeda Pharmaceutical Co., Ltd.; Duranate WB40-100, Duranate WB40-80D, and Duranate WX-1741, all manufactured by Asahi Kasei Corporation; and Basonat HW-100 and Basonat LR-9056, all manufactured by BASF Corporation.
• the epoxy group-containing compound is not particularly limited as long as it has at least two or more epoxy groups in the molecule.
• glycidyl ether types such as bisphenol A diglycidyl ether, bisphenol A ⁇ -dimethylglycidyl ether, bisphenol F diglycidyl ether, tetrahydroxyphenylmethane tetraglycidyl ether, resorcinol diglycidyl ether, brominated bisphenol A diglycidyl ether, chlorinated bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, diglycidyl ether of bisphenol A alkylene oxide adduct, novolac glycidyl ether, polyalkylene glycol diglycidyl ether, glycerin triglycidyl ether, pentaerythritol diglycidyl ether, and epoxy urethane resin; glycidyl ether/ester types
• the melamine compound is not particularly limited as long as it has a melamine skeleton in the molecule.
• alkylolated melamine derivatives compounds partially or completely etherified by reacting an alkylolated melamine derivative with an alcohol, and mixtures of these can be used.
• the alcohol used for etherification methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol, etc. are preferably used.
• the melamine compound may be either a monomer or a polymer of dimer or more, and mixtures of these may also be used.
• melamine compounds include, for example, Cymel 323, Cymel 325, Cymel 327, Cymel 328, and Cymel 370 manufactured by Japan Cytec Industries Co., Ltd.
• the carbodiimide group-containing compound is not particularly limited as long as it has at least two or more carbodiimide groups in the molecule.
• Examples include compounds having carbodiimide groups such as p-phenylene-bis(2,6-xylylcarbodiimide), tetramethylene-bis(t-butylcarbodiimide), and cyclohexane-1,4-bis(methylene-t-butylcarbodiimide), and polycarbodiimide, which is a polymer having a carbodiimide group.
• polycarbodiimide is preferred because of its ease of handling.
• polycarbodiimide products include the Carbodilite series manufactured by Nisshinbo Corporation. Specific products include, for example, water-soluble types “SV-02”, “V-02”, “V-02-L2", and “V-04”, emulsion types "E-01” and "E-02", organic solution types "V-01”, “V-03”, “V-07”, and “V-09”, and solvent-free type "V-05”.
• the content of the crosslinking agent is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.5 to 10 parts by mass, relative to 100 parts by mass of the polyurethane resin. If the content of the crosslinking agent is 0.01 part by mass or more, the coating film performance of the protective layer (P) is improved, and if it is 80 parts by mass or less, the coating stability of the protective layer (P) may be improved. From the viewpoint of the recyclability of the multilayer structure of the present invention, it may be preferable that the protective layer (P) does not contain a crosslinking agent.
• polymers and tackifiers are not particularly limited. Examples include polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester-maleic anhydride copolymer, styrene-maleic acid resin, styrene-butadiene resin, butadiene resin, acrylonitrile-butadiene resin, poly(meth)acrylonitrile resin, (meth)acrylamide resin, chlorinated polyethylene resin, chlorinated polypropylene resin, polyester resin, modified nylon resin, tackifier resin such as rosin, phenol resin, silicone resin, epoxy resin, etc., and a mixture of multiple polymers may be used as necessary. Note that these polymers may be used in the solid form, but from the viewpoint of maintaining stability in the coating liquid, it is preferable to use those processed into an aqueous dis
• inorganic particles examples include metal oxides such as magnesium oxide, zinc oxide, and tin oxide; inorganic particles such as calcium carbonate and silica; and layered inorganic compounds such as vermiculite, montmorillonite, hectorite, hydrotalcite, and synthetic mica. From the standpoint of stability in the coating liquid, the average particle size of these inorganic particles is preferably 0.005 to 10 ⁇ m, and more preferably 0.005 to 5 ⁇ m. Note that a mixture of multiple inorganic particles may be used. Zinc oxide can be used for the purpose of blocking ultraviolet rays, and tin oxide can be used for the purpose of preventing static electricity.
• metal oxides such as magnesium oxide, zinc oxide, and tin oxide
• inorganic particles such as calcium carbonate and silica
• layered inorganic compounds such as vermiculite, montmorillonite, hectorite, hydrotalcite, and synthetic mica.
• the average particle size of these inorganic particles is preferably 0.005 to 10 ⁇
• pigments and dyes examples include titanium oxide, zinc oxide, and carbon black, and any of disperse dyes, acid dyes, cationic dyes, and reactive dyes can be used.
• Various chemicals such as leveling agents, defoamers, anti-popping agents, pigment dispersants, UV absorbers, thickeners, weather resistance agents, and flame retardants can also be added to the protective layer (P) of the present invention as necessary.
• the proportion of the urethane resin in the protective layer (P) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more, and the protective layer (P) may essentially consist of only the urethane resin.
• the proportion of the total mass of the urethane resin and the crosslinking agent in the protective layer (P) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more, and the protective layer (P) may essentially consist of only the urethane resin and the crosslinking agent.
• the average thickness of the protective layer (P) of the composite multilayer film is preferably 0.05 ⁇ m or more and less than 10 ⁇ m.
• the average thickness of the protective layer (P) is more preferably 0.2 ⁇ m or more and less than 4 ⁇ m, and even more preferably 0.6 ⁇ m or more and less than 1.5 ⁇ m.
• the lower limit of the total average thickness ratio of the layers mainly composed of polyethylene-based resin in the composite multilayer film of the present invention is preferably 0.75, more preferably 0.80, even more preferably 0.85, and even more preferably 0.88.
• the upper limit of the total average thickness ratio of the layers mainly composed of polyethylene-based resin in the composite multilayer film is preferably 0.995, more preferably 0.99, and may be 0.98.
• layers mainly composed of polyethylene-based resin include layer (Y) when the adhesive resin (B) is, for example, acid-modified polyethylene, and layer (Z) when the polyolefin resin (C) is polyethylene.
• the lower limit of the total average thickness ratio of the layers mainly composed of a resin having ethylene units in the composite multilayer film of the present invention is preferably 0.95, more preferably 0.97, and even more preferably 0.99.
• the upper limit of the total average thickness ratio of the layers mainly composed of a resin having ethylene units in the composite multilayer film may be, for example, 0.9999.
• layers mainly composed of a resin having ethylene units include layer (X) as well as the layer mainly composed of the polyethylene resin described above.
• the composite multilayer film of the present invention does not have a layer containing as its main component a resin with a melting point of 200°C or higher, or a metal layer with an average thickness of 1 ⁇ m or more.
• a layer containing as its main component a resin with a melting point of 200°C or higher, or a metal layer with an average thickness of 1 ⁇ m or more it is possible to prevent uneven mixing with other components when the crushed composite multilayer film is melt-molded.
• the metal layer here refers to a layer having continuous and discontinuous surfaces made of metal, such as aluminum foil.
• the composite multilayer film of the present invention preferably has an oxygen transmission rate (under conditions of 20°C and 65% RH) of 0.5 cc/( m2 day atm) or less, more preferably 0.3 cc/(m2 day atm) or less, and even more preferably 0.1 cc/( m2 day atm) or less, measured in accordance with the method described in JIS K 7126-2 (constant pressure method; 2006).
• a composite multilayer film having an oxygen transmission rate in the above range has excellent gas barrier properties.
• the composite multilayer film of the present invention itself can be used as a packaging material having gas barrier properties, but by laminating at least one resin layer (R) containing the thermoplastic resin (D) as a main component to form a multilayer structure, various functions as a packaging material such as designability and heat sealability can be imparted.
• the thermoplastic resin (D) is not particularly limited, and examples thereof include linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, vinyl ester resin, ethylene-propylene copolymer, polypropylene, propylene- ⁇ -olefin copolymer ( ⁇ -olefin having 4 to 20 carbon atoms), polybutene, polypentene, and other olefins alone or copolymers thereof, polyamides such as nylon 6 and nylon 6,6, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polystyrene, polyvinyl chloride, polyvinylidene chloride, acrylic resins, polycarbonate, chlorinated polyethylene, and chlorinated polypropylene.
• the melting point is preferably less than 200°C
• the thermoplastic resin (D) is more preferably the same as the polyolefin resin (C) described above, i.e., a polyolefin resin having a melting point of less than 150°C, and more preferably contains a polyethylene-based resin as a main component, and is particularly preferably a polyethylene-based resin.
• the polyolefin resin (C) and the thermoplastic resin (D) preferably contain a polyethylene-based resin as a main component, and are more preferably polyethylene-based resins.
• a resin layer (R) may be unstretched, or may be stretched or rolled in a uniaxial or biaxial direction. From the viewpoint of improving mechanical strength, it is preferable to use a biaxially stretched layer, and from the viewpoint of improving heat sealability, it is preferable to use a non-stretched layer.
• the method for producing the resin layer (R) is not particularly limited, but it is generally produced by melt extrusion using an extruder.
• the die either a circular die or a T-die can be used.
• the method for stretching in the uniaxial or biaxial direction is also not particularly limited, and the film can be produced by stretching in the flow direction of the film and/or the direction perpendicular to the flow direction, i.e., the width direction, using a conventionally known stretching method such as roll-type uniaxial stretching, tubular-type simultaneous biaxial stretching, tenter-type sequential biaxial stretching, and tenter-type simultaneous biaxial stretching.
• the area ratio is preferably 8 to 60 times.
• the area ratio is more preferably 55 times or less, and even more preferably 50 times or less. In addition, the area ratio is more preferably 9 times or more. If the area ratio is less than 8 times, stretching unevenness may remain, and if it exceeds 60 times, the layer may be easily broken during stretching.
• the average thickness of the resin layer (R) is preferably 10 to 200 ⁇ m.
• the average thickness of a non-oriented layer is more preferably 10 to 150 ⁇ m
• the average thickness of a biaxially oriented layer is more preferably 10 to 50 ⁇ m.
• the average thickness of the multilayer structure of the present invention is preferably 300 ⁇ m or less. With an average thickness in the above range, the multilayer structure of the present invention is lightweight and flexible, and is therefore preferably used for flexible packaging applications. In addition, the amount of resin used in the multilayer structure is small, which reduces the environmental impact.
• the average thickness of each layer in the multilayer structure of the present invention may be adjusted as appropriate depending on the application, but from the viewpoints of suppressing coloration during melt molding of the pulverized material, improving thermal stability during melt molding, and suppressing the occurrence of bumps, at least one of the layers (Z) and the resin layer (R) contains a polyethylene resin as a main component, and the ratio of the total average thickness of the layers containing a polyethylene resin as a main component to the average thickness of the multilayer structure is preferably 0.80 or more, more preferably 0.85 or more. On the other hand, from the viewpoint of improving gas barrier properties, the ratio is preferably 0.997 or less, more preferably 0.995 or less, and may be 0.993 or less.
• the method of laminating the resin layer (R) on the composite multilayer film of the present invention is not particularly limited, and examples thereof include extrusion lamination, coextrusion lamination, dry lamination, etc.
• An adhesive layer may be provided when laminating the resin layer (R) on the composite multilayer film.
• each layer constituting the multilayer structure of the present invention may be laminated via an adhesive layer as necessary. However, there is no adhesive layer between layer (X) and layer (Y) of the multilayer film, and between layer (Y) and layer (Z).
• the adhesive layer can be formed by applying a known adhesive and drying it.
• the adhesive is preferably a two-component reactive polyurethane adhesive in which a polyisocyanate component and a polyol component are mixed and reacted.
• the average thickness of the adhesive layer is not particularly limited, but is preferably 1 to 5 ⁇ m, more preferably 2 to 4 ⁇ m.
• the multilayer structure of the present invention is not particularly limited, and from the viewpoint of obtaining a multilayer structure excellent in recyclability, for example, a layer structure as shown below is preferable.
• layer (X) is expressed as X
• layer (Y) as Y
• layer (Z) as Z
• inorganic layer (I) as I
• protective layer (P) as P
• layer (R) as R
• "/" means that they are directly laminated
• “//” means that they are laminated via an adhesive layer or directly laminated, but it is a preferred embodiment that they are laminated via an adhesive layer.
• the layer (X), layer (Y) and layer (Z) are preferably stretched at least uniaxially, and more preferably biaxially.
• the layer (Z) and layer (R) are preferably polyethylene resins, and the layer (Y) is preferably maleic anhydride modified polyethylene resin.
• both outermost layers of the multilayer structure of the present invention have a layer containing a polyethylene resin as a main component so that the pulverized product obtained by pulverizing the packaging material can be recovered as a polyethylene resin.
• the resin layer (R) when the resin layer (R) is arranged on both outermost layers, it is preferable that the resin layer (R) is a layer containing a polyethylene resin as a main component, and when the layer (Z) and the resin layer (R) are arranged on both outermost layers, it is preferable that the layer (Z) and the resin layer (R) are layers containing a polyethylene resin as a main component.
• the multilayer structure of the present invention may have layers other than those described above, as long as the effects of the present invention are not impaired.
• An example of the other layer is a recovery layer.
• Another example of the other layer is a printed layer.
• the printed layer may be included at any position in the multilayer structure of the present invention.
• An example of the printed layer is a film obtained by applying a solution containing a pigment or dye and, if necessary, a binder resin, and drying the solution.
• the application method of the printed layer examples include gravure printing, as well as various application methods using a wire bar, a spin coater, a die coater, etc.
• the average thickness of the printed layer is not particularly limited, but is preferably 0.5 to 10 ⁇ m, and more preferably 1 to 4 ⁇ m. From the viewpoint of recyclability, it is preferable that the multilayer structure of the present invention does not have a layer containing, as a main component, a resin having a melting point of 200° C. or more, and a metal layer having an average thickness of 1 ⁇ m or more.
• a method for recovering a multilayer structure of the present invention in which the multilayer structure is crushed and then melt-molded, and a recovered composition containing the recovered multilayer structure of the present invention are also preferred embodiments of the present invention.
• the recovered multilayer structure of the present invention is first pulverized.
• the pulverized recovered material may be melt-molded as it is to obtain a recovered composition, or may be melt-molded together with other components as necessary to obtain a recovered composition.
• a preferred component to be added to the recovered material is a polyolefin resin, and a polyethylene-based resin is more preferred.
• the polyolefin resin is the same type as the polyolefin resin (C) described above for use in the multilayer film of the present invention.
• the pulverized recovered material may be directly used to manufacture a molded product such as a multilayer structure, or the pulverized recovered material may be melt-molded to obtain pellets of the recovered composition, and the pellets may then be used to manufacture a molded product.
• the mass ratio of the resin composition (A) to the polyolefin resin [resin composition (A)/polyolefin resin] is preferably 0.01/99.99 to 20/80. If the mass ratio is less than 0.01/99.99, the usage ratio of the recovered material may decrease. On the other hand, if the mass ratio exceeds 20/80, the melt moldability and mechanical properties of the recovered composition may decrease. From the viewpoint of improving the melt moldability and mechanical properties of the obtained recovered composition, the above mass ratio is more preferably 15/85 or less, even more preferably 10/90 or less, and may be 5/95 or less.
• the multilayer structure of the present invention has excellent appearance, gas barrier properties, and recyclability, and can therefore be suitably used as a material for various types of packaging, such as food packaging, pharmaceutical packaging, industrial chemical packaging, and agricultural chemical packaging.
• packaging materials comprising the multilayer structure of the present invention can be suitably used as packaging materials with excellent recyclability.
• Example 1 (1) Preparation of EVOH (a)-containing resin composition (A) for layer (X) EVOH (a-1) (ethylene unit content 32 mol%, saponification degree 99.99 mol%, MFR (190 ° C., 2.16 kg load) 1.6 g / 10 min, melting point 183 ° C., sodium acetate 250 ppm in terms of sodium ion, phosphate ion 30 ppm in terms of phosphate radical, boric acid 150 ppm in terms of boron element, no polyvalent metal ion) and magnesium stearate were melt-kneaded so that the magnesium ion content in the resulting resin composition was 50 ppm, and resin composition (A) pellets for layer (X) were obtained.
• EVOH (a)-containing resin composition (A) for layer (X) EVOH (a-1) (ethylene unit content 32 mol%, saponification degree 99.99 mol%, MFR (190 ° C., 2.16 kg load) 1.6 g
• the resin temperature was set to 220 ° C.
• Resin composition containing adhesive resin (B) for layer (Y) A maleic anhydride modified polyethylene "ADMER (trademark) NF518" manufactured by Mitsui Chemicals, Inc. (MFR (190°C, 2.16 kg load) 3.1 g/10 min, melting point 121°C, density 0.91 g/ cm3 , acid value 1.8 mgKOH/g) was used as adhesive resin (B) as resin composition pellets for layer (Y).
• ADMER trademark
• Resin Composition Containing Polyolefin Resin (C) for Layer (Z) A low-density polyethylene "INNATE (trademark) TF80" manufactured by DOW (MFR (190°C, 2.16 kg load) 1.6 g/10 min, melting point 124°C, density 0.926 g/ cm3 ) was used as polyolefin resin (C) as resin composition pellets for layer (Z).
• Oxygen transmission rate of composite multilayer film and multilayer structure The composite multilayer film and multilayer structure obtained in (5) and (6) were measured for oxygen transmission rate according to the method described in JIS K 7126-2 (isobaric method; 2006) with layer (Z) as the oxygen supply side. Specifically, using an oxygen transmission amount measuring device ("MOCON OX-TRAN2/21" manufactured by Modern Control Co., Ltd.), the oxygen transmission rate (unit: cc/( m2 ⁇ day ⁇ atm)) was measured under the conditions of temperature 20°C, humidity 85% RH on the oxygen supply side, humidity 85% RH on the carrier gas side, oxygen pressure 1 atm, and carrier gas pressure 1 atm, and the evaluation was performed according to the following criteria.
• Nitrogen gas containing 2% by volume of hydrogen gas was used as the carrier gas.
• the measurement result of the composite multilayer film obtained in (5) was the oxygen transmission rate before lamination, and the measurement result of the multilayer structure obtained in (6) was the oxygen transmission rate after lamination. Note that when the evaluation was D or E, it was determined that the gas barrier property was low. The results are shown in Table 3.
• a monolayer film having an average thickness of 50 ⁇ m was obtained similarly using only the low-density polyethylene.
• a T-die with a width of 300 mm was used as the die.
• the average thickness of the monolayer film was adjusted by appropriately changing the screw rotation speed and the take-up roll speed.
• Criterion A The amount of lumps was almost the same compared to the control.
• B The amount of small lumps was slightly more than the control.
• C The amount of small lumps was more than the control.
• D The amount of large lumps was more than the control.
• E The amount of large lumps was significantly more than the control.
• Example 2 Except for changing the alumina deposition layer to a silica (SiOx) deposition layer, resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were produced in the same manner as in Example 1, and various measurements and evaluations were carried out. The results are shown in Table 3.
• Example 3 Except for changing the alumina deposition layer to an aluminum metal (Al) deposition layer, resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were produced in the same manner as in Example 1, and various measurements and evaluations were carried out. The results are shown in Table 3.
• Example 4 Except for changing the average thickness of the polyurethane resin layer (protective layer (P-1)) to 0.5 ⁇ m, resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were prepared in the same manner as in Example 1, and various measurements and evaluations were carried out. The results are shown in Table 3.
• Example 5 Except for changing the average thickness of the polyurethane resin layer (protective layer (P-1)) to 2.0 ⁇ m, resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were prepared in the same manner as in Example 1, and various measurements and evaluations were carried out. The results are shown in Table 1.
• Example 6 Resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were produced in the same manner as in Example 1, except that a protective layer (P-2) was laminated using a coating liquid prepared by adding 5 parts by mass of an aliphatic hydrophilic polyisocyanate "Bayhydur (trademark) 3100" manufactured by Sumika Covestro Urethane Co., Ltd. to 100 parts by mass of polyurethane resin solids in the coating liquid used for laminating the polyurethane resin layer (protective layer (P-1)), and various measurements and evaluations were performed. The results are shown in Table 3.
• Example 7 89.6 g of hydrochloric acid (0.1N) was added to 10.4 g of tetraethoxysilane, stirred for 30 minutes, and a coating liquid obtained by mixing a hydrolysis solution having a solid content of 3 mass% (SiO2 equivalent) and a 3 mass% aqueous solution of polyvinyl alcohol in a mass ratio of 80/20 was used instead of the coating liquid used for laminating the protective layer (P-1), and a protective layer (P-3) was laminated.
• Resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were produced in the same manner as in Example 1, and various measurements and evaluations were performed. The results are shown in Table 3.
• Example 8 Except for changing the average thickness of the alumina vapor deposition layer to 100 nm, resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were produced in the same manner as in Example 1, and various measurements and evaluations were carried out. The results are shown in Table 3.
• Example 9 Resin composition pellets, a multilayer film, a composite multilayer film and a multilayer structure were produced in the same manner as in Example 1, except that EVOH (a-2) (ethylene unit content 27 mol%, saponification degree 99.99 mol%, MFR (210°C, 2.16 kg load) 4.0 g/10 min, melting point 191°C, containing 220 ppm of sodium acetate calculated as sodium ions, 30 ppm of phosphate ions calculated as phosphate radicals, 150 ppm of boric acid calculated as boron element, and no polyvalent metal ions) was used instead of EVOH (a-1), and various measurements and evaluations were performed. The results are shown in Table 3.
• EVOH (a-2) ethylene unit content 27 mol%, saponification degree 99.99 mol%, MFR (210°C, 2.16 kg load) 4.0 g/10 min, melting point 191°C, containing 220 ppm of sodium acetate calculated as sodium ions, 30 ppm of
• Example 10 Resin composition pellets, a multilayer film, a composite multilayer film and a multilayer structure were prepared in the same manner as in Example 1, except that EVOH (a-3) (ethylene unit content 44 mol%, saponification degree 99.99 mol%, MFR (190°C, 2.16 kg load) 5.7 g/10 min, melting point 165°C, containing 220 ppm of sodium acetate calculated as sodium ions, 30 ppm of phosphate ions calculated as phosphate radicals, and containing no polyvalent metal ions) was used instead of EVOH (a-1), and various measurements and evaluations were carried out. The results are shown in Table 3.
• EVOH (a-3) ethylene unit content 44 mol%, saponification degree 99.99 mol%, MFR (190°C, 2.16 kg load) 5.7 g/10 min, melting point 165°C, containing 220 ppm of sodium acetate calculated as sodium ions, 30 ppm of phosphate ions calculated as phosphate radicals,
• Example 11 Except for using a mixture (dry blend) of EVOH (a-2) and EVOH (a-3) in a weight ratio of 75/25 instead of EVOH (a-1), resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were prepared in the same manner as in Example 1, and various measurements and evaluations were carried out. The results are shown in Table 3.
• Example 12 Resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were prepared in the same manner as in Example 1, except that EVOH (a-1A), which is equivalent to EVOH (a-1) except that the sodium acetate content was 125 ppm calculated as sodium ion, was used instead of EVOH (a-1), and various measurements and evaluations were performed. The results are shown in Table 3.
• Example 13 Resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were produced in the same manner as in Example 1, except that EVOH (a-1B), which is equivalent to EVOH (a-1) except that the sodium acetate content was 350 ppm calculated as sodium ion, was used instead of EVOH (a-1), and various measurements and evaluations were performed. The results are shown in Table 3.
• Example 14 Resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were prepared in the same manner as in Example 1, except that EVOH (a-1C), which is equivalent to EVOH (a-1) except that it contains potassium acetate instead of sodium acetate, was used instead of EVOH (a-1). Various measurements and evaluations were performed. The results are shown in Table 3.
• Examples 15 to 16 Resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were prepared in the same manner as in Example 1, except that the amount of magnesium stearate kneaded with EVOH (a-1) was changed as shown in Table 1, and various measurements and evaluations were carried out. The results are shown in Table 3.
• Examples 17 to 18 Except for changing the magnesium stearate kneaded with EVOH (a-1) to calcium stearate (Example 17) or zinc stearate (Example 18), resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were produced in the same manner as in Example 1, and various measurements and evaluations were carried out. The results are shown in Table 3.
• Example 19 Resin composition pellets, multilayer films, composite multilayer films, and multilayer structures were prepared in the same manner as in Example 1, except that the average thickness of each layer was changed as shown in Table 1, and various measurements and evaluations were carried out. The results are shown in Table 3.
• Comparative Examples 1 to 5 Except for not laminating the protective layer (P-1), resin composition pellets, composite multilayer films, and multilayer structures were prepared in the same manner as in Examples 1 to 3 and 20 to 21, and various measurements and evaluations were carried out. The results are shown in Table 3.
• Comparative Example 6 A composite multilayer film and a multilayer structure were produced in the same manner as in Example 1, except that a layer (Z) having an average thickness of 40 ⁇ m was used instead of a multilayer film, and various measurements and evaluations were performed.
• the layer (Z) having an average thickness of 40 ⁇ m was produced by extruding only the polyolefin resin (C)-containing resin composition without simultaneously extruding the resin composition (A) and the adhesive resin (B) when producing the multilayer film in Example 1, and adjusting the average thickness. The results are shown in Table 3.
• Comparative Example 7 A composite multilayer film and a multilayer structure were produced in the same manner as in Example 1, except that a layer (Z) having an average thickness of 40 ⁇ m was used instead of a multilayer film, and an alumina vapor deposition layer was not further laminated, and various measurements and evaluations were performed.
• the layer (Z) having an average thickness of 40 ⁇ m was produced by extruding only the polyolefin resin (C)-containing resin composition without simultaneously extruding the resin composition (A) and the adhesive resin (B) when forming the multilayer film in Example 1, and adjusting the average thickness. The results are shown in Table 3.
• Comparative Example 8 Except for not laminating the alumina vapor deposition layer, a resin composition pellet, a composite multilayer film, and a multilayer structure were produced in the same manner as in Example 1, and various measurements and evaluations were carried out. The results are shown in Table 3.
• Comparative Example 9 Resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were prepared in the same manner as in Example 1, except that EVOH (a-1D), which is equivalent to EVOH (a-1) except that the sodium acetate content was 20 ppm calculated as sodium ion, was used instead of EVOH (a-1), and various measurements and evaluations were performed. The results are shown in Table 3.
• Comparative Example 10 Resin composition pellets, a multilayer film, a composite multilayer film, and a multilayer structure were prepared in the same manner as in Example 1, except that EVOH (a-1E), which is equivalent to EVOH (a-1) except that the sodium acetate content was 550 ppm calculated as sodium ion, was used instead of EVOH (a-1), and various measurements and evaluations were performed. The results are shown in Table 3.
• Reference Example 1 A composite multilayer film and a multilayer structure were produced in the same manner as in Example 1, except that a biaxially oriented polyethylene terephthalate (PET) film "Lumirror (trademark) P60" (melting point 256°C, average thickness 12 ⁇ m) manufactured by Toray Industries, Inc. was used instead of the multilayer film, and no protective layer (P-1) was laminated, and various measurements and evaluations were performed. The results are shown in Table 3.
• PET polyethylene terephthalate

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• 2023
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