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
  • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
  • B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
  • B29C55/10—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial
  • B29C55/12—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial
• • 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
  • B32B27/32—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
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/04—Interconnection of layers
  • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
  • B65D65/38—Packaging materials of special type or form
  • B65D65/40—Applications of laminates for particular packaging purposes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/04—Disintegrating plastics, e.g. by milling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/04—Disintegrating plastics, e.g. by milling
  • B29B2017/042—Mixing disintegrated particles or powders with other materials, e.g. with virgin materials
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/62—Plastics recycling; Rubber recycling

Definitions

• the present invention provides a multilayer film having an epoxy compound-modified ethylene-vinyl alcohol copolymer having a melting point of 110° C. or more and less than 150° C. as the outermost layer, a multilayer structure using the same, and a method for recovering the multilayer structure. and a recovered composition comprising the recovered multi-layered structure.
• Packaging materials for long-term storage of food are often required to have oxygen barrier properties and other gas barrier properties.
• a packaging material with a high gas barrier property it is possible to suppress oxidative degradation of food and breeding of microorganisms due to infiltration of oxygen.
• metal foils such as aluminum foils and inorganic deposition layers such as silicon oxide and aluminum oxide are widely used.
• resin layers having gas barrier properties such as vinyl alcohol-based polymers and polyvinylidene chloride, are also widely used.
• Vinyl alcohol-based polymers have the characteristic of exhibiting gas barrier properties by crystallizing and densifying due to hydrogen bonding between hydroxyl groups in the molecule.
• ethylene-vinyl alcohol copolymer hereinafter sometimes abbreviated as "EVOH" is suitable for melt molding due to its excellent thermal stability.
• Multilayer films having layers are widely used as gas barrier packaging materials (Patent Document 1).
• recycling post-consumer recycling
• the number of cases where the EVOH layer is used as the outermost layer of a multilayer film is increasing due to the diversification of the layer structure and the synergistic effect of improving barrier properties by lamination with an inorganic deposition layer.
• the EVOH layer in direct contact with the die wall, and the EVOH layer extruded from the die is rapidly cooled. Delamination can be a problem.
• a multilayer film is uniaxially or biaxially stretched in anticipation of improvement in mechanical properties and the like, problems such as poor appearance and delamination tend to become apparent, and improvements have been desired.
• the EVOH located in the outermost layer has a melting point of less than 150°C and has certain metal ions, thereby providing a multilayer film having excellent appearance and interlayer adhesion. Found it. However, it has been found that blocking during stretching becomes a problem when the melting point of EVOH located in the outermost layer is too low. In addition, when producing EVOH having a low melting point (less than 150°C), it was found that modification with an epoxy compound is optimal from the viewpoint of minimizing the deterioration of oxygen barrier properties and reducing production costs. Found it.
• a first object of the present invention is to provide a multilayer film having, as the outermost layer, a modified EVOH modified with an epoxy compound and having excellent appearance, interlayer adhesion, gas barrier properties and blocking resistance. That is.
• a second object of the present invention is to provide a multi-layer structure that achieves both gas barrier properties and recyclability by using the multi-layer film, a packaging material containing the multi-layer structure, and a recovered composition containing the collected material of the multi-layer structure. It is to provide a product and its recovery method.
• the above purpose is [1] Having a layer (X) as the outermost layer, having a structure in which at least the layer (X), the layer (Y), and the layer (Z) are laminated adjacent to each other in this order, and the layer (X) is an epoxy compound A modified ethylene-vinyl alcohol copolymer (a) having a melting point of 110° C. or more and less than 150° C.
• modified EVOH (a) modified with A
• the layer (Y) contains an adhesive resin (B) having a melting point of less than 150°C as a main component
• the layer (Z) contains a polyethylene resin (C) having a melting point of less than 150°C as a main component
• thermoplastic resin (D) contains polyethylene resin as a main component
• thermoplastic resin (D) contains polyethylene resin as a main component
• ratio of the total thickness of the layers containing polyethylene resin as a main component to the total thickness of the multilayer structure is 0.75 or more
• a recovered composition comprising the recovered multilayer structure of any one of [11] to [14];
• a method for recovering a multilayer structure comprising crushing the multilayer structure according to any one of [11] to [14] and then melt-molding the multilayer structure; This is achieved by providing
• the multilayer film of the present invention is suitable for use as a gas barrier film because it has excellent appearance, interlayer adhesion, gas barrier properties and anti-blocking properties while having an epoxy-modified EVOH as the outermost layer.
• the multilayer structure of the present invention containing the multilayer film is excellent in appearance and is suitably used as a packaging material that has both gas barrier properties and recyclability.
• the multilayer structure since the multilayer structure has good recyclability, it is possible to provide a recovered composition containing a recovered product of the multilayer structure and a method for recovering the same.
• interlayer adhesion means adhesion between the layer (X) and a layer adjacent to the layer (X), specifically, adhesion with the layer (Y), which will be mainly described later.
• Interlayer adhesion can be evaluated by T-peel strength as described in the Examples.
• recyclability means that when the recovered multilayer structure or packaging material of the present invention is melt-kneaded to produce a recovered composition, coloration and gelation of the resin are suppressed, and the appearance and mechanical properties are excellent. It means that the recovered composition can be efficiently produced, and can be evaluated by the recovery test described in the Examples. Further, “appearance” means the appearance after stretching treatment, and can be specifically evaluated by the stretchability evaluation described in Examples.
• the multilayer film of the present invention has a layer (X) as the outermost layer, and has a structure in which at least the layer (X), the layer (Y), and the layer (Z) are laminated adjacent to each other in this order, and the layer (X) ) is composed of a resin composition (A) containing, as a main component, a modified EVOH (a) modified with an epoxy compound and having a melting point of 110° C. or more and less than 150° C., and a layer (Y) is an adhesive resin having a melting point of less than 150° C. ( B) as a main component, the layer (Z) contains a polyethylene resin (C) having a melting point of less than 150° C.
• the resin composition (A) contains 20 to 1500 ppm of alkali metal ions (b).
• the layer (X), the layer (Y), and the layer (Z) are laminated adjacent to each other in this order means that the adjacent layers are directly laminated, and specifically, The layer (X), the layer (Y) and the layer (Z) are laminated in this order, the layer (X) and the layer (Y) are directly laminated, and the layer (Y) and the layer (Z) are directly laminated It means that it is laminated.
• “main component” means a component contained in an amount of more than 50% by mass.
• the multilayer film of the present invention contains a modified EVOH (a) having a melting point of 110° C. or more and less than 150° C. as a main component, and a layer (X ) in the outermost layer.
• the melting point of the modified EVOH (a) is less than 150°C, the appearance and interlayer adhesion of the multilayer film having the layer (X) containing the modified EVOH (a) as the main component as the outermost layer can be improved.
• the modified EVOH (a) has a melting point of less than 150° C., which improves the fluidity of the polymer chain, so that it can be melt-molded or subjected to secondary processing such as stretching at relatively low temperatures. It is considered that the stress can be effectively relieved even if there is such a layer, and the adhesive reaction activity with the adjacent layer can be maintained. Further, by setting the melting point of the modified EVOH (a) to 110° C. or higher, the blocking resistance can be improved.
• Modified EVOH (a) can usually be obtained by post-modifying EVOH obtained by saponifying an ethylene-vinyl ester polymer with an epoxy compound. Production and saponification of the ethylene-vinyl ester polymer can be carried out by known methods.
• the vinyl alcohol unit content of the modified EVOH (a) is preferably 20 mol% or more, more preferably 30 mol% or more, even more preferably 40 mol% or more, and particularly preferably 50 mol% or more.
• the melting point of the modified EVOH (a) is preferably less than 140°C, more preferably less than 130°C, and even more preferably less than 125°C.
• the modified EVOH (a) may have a melting point of 115° C. or higher or 120° C. or higher.
• the melting point of modified EVOH (a) is controlled by one or more of the following items.
• the ethylene unit content of the modified EVOH (a) is preferably 20 mol% or more, more preferably 25 mol% or more, and even more preferably 30 mol% or more.
• the ethylene unit content of the modified EVOH (a) is preferably 60 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less.
• the ethylene unit content of modified EVOH (a) is determined by NMR measurement.
• the modified EVOH (a) may consist of two or more types of EVOH having different ethylene unit contents.
• the ethylene unit content can be controlled by various methods, and can be controlled by the ethylene pressure used in the polymerization step, the ratio of the vinyl ester to the solvent, and the like.
• the melting point can be lowered by lowering the degree of saponification of modified EVOH (a).
• the degree of saponification is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, particularly preferably 90 mol% or more, particularly preferably 99 mol% or more, or 99 mol% or more. .9 mol % or more.
• the degree of saponification means the ratio of the number of vinyl alcohol units to the total number of vinyl alcohol units and vinyl ester units in the modified EVOH (a).
• the degree of saponification of modified EVOH (a) is determined by NMR measurement.
• Modified EVOH (a) may consist of two or more types of EVOH with different degrees of saponification.
• the degree of saponification can be controlled by various methods, and can be controlled by adjusting the amount of alkali catalyst, water content, reaction temperature, reaction time, etc. in the saponification step.
• the hydroxyl group generated in the saponification step can be controlled by esterification with a carboxylic acid such as acetic acid or an anhydride thereof.
• the melting point of the modified EVOH (a) can be lowered by modifying with an epoxy compound to introduce a modifying group containing a primary hydroxyl group represented by the following general formula (I).
• the degree of melting point reduction per introduction rate varies depending on the structure of the modifying group containing a primary hydroxyl group to be introduced.
• the temperature drops by about 8 to 11°C.
• the reason for this is thought to be that the melting point can be lowered while maintaining the amount of hydroxyl groups, and that the primary hydroxyl groups have high adhesion reaction activity with the layer (Y) and the inorganic deposition layer (I), which will be described later.
• the content of the modifying group containing the primary hydroxyl group in the modified EVOH (a) may be appropriately adjusted in consideration of the balance between the melting point and various physical properties. is often good.
• the lower limit of the content of modifying groups containing primary hydroxyl groups in modified EVOH (a) is more preferably 2.0 mol %, still more preferably 2.5 mol %, and particularly preferably 3.5 mol %.
• the upper limit of the content of modifying groups containing primary hydroxyl groups in the modified EVOH (a) is more preferably 10 mol %, and even more preferably 5 mol %.
• R 1 , R 2 , R 3 and R 4 are each independently a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, or Represents an aromatic hydrocarbon group having 6 to 10 carbon atoms, R 3 and R 4 may be bonded, hydrogen possessed by the above-mentioned aliphatic hydrocarbon group, alicyclic hydrocarbon group and aromatic hydrocarbon group Some or all of the atoms may be substituted with hydroxyl groups, carboxyl groups or halogen atoms.
• Examples of the aliphatic hydrocarbon groups used as R 1 , R 2 , R 3 or R 4 include alkyl groups and alkenyl groups, and examples of the alicyclic hydrocarbon groups include cycloalkyl groups and cycloalkenyl groups.
• Examples of the aromatic hydrocarbon group include a phenyl group.
• both R 1 and R 2 are preferably hydrogen atoms. More preferably, both R 1 and R 2 are hydrogen atoms, one of R 3 and R 4 is the above-mentioned aliphatic hydrocarbon group, and the other is a hydrogen atom.
• This aliphatic hydrocarbon group is preferably an alkyl group or an alkenyl group. From the viewpoint of placing particular importance on the gas barrier properties of various molded articles such as multilayer structures to be obtained, it is more preferable that one of R 3 and R 4 is a methyl group or an ethyl group, and the other is a hydrogen atom.
• R 3 and R 4 is a substituent represented by (CH 2 ) h OH (where h is an integer of 1 to 8) and the other is a hydrogen atom.
• h is preferably an integer of 1 to 4, more preferably 1 or 2, even more preferably 1.
• the method for incorporating the modifying group represented by the general formula (I) into EVOH is not particularly limited. Used.
• Examples of monovalent epoxy compounds include epoxyethane (ethylene oxide), epoxypropane, 1,2-epoxybutane, 2,3-epoxybutane, 3-methyl-1,2-epoxybutane, 1,2-epoxypentane, 3-methyl-1,2-epoxypentane, 1,2-epoxyhexane, 2,3-epoxyhexane, 3,4-epoxyhexane, 3-methyl-1,2-epoxyhexane, 3-methyl-1,2 - epoxyheptane, 4-methyl-1,2-epoxyheptane, 1,2-epoxyoctane, 2,3-epoxyoctane, 1,2-epoxynonane, 2,3-epoxynonane, 1,2-epoxydecane, 1,2-epoxidedecane, epoxyethylbenzene, 1-phenyl-1,2-epoxypropane, 3-phenyl-1,2-epoxypropane, various alkyl glycidy
• the number of carbon atoms in the above monovalent epoxy compound is preferably 2 to 8.
• the number of carbon atoms in the monovalent epoxy compound is more preferably 2-6, more preferably 2-4.
• the monovalent epoxy compounds are 1,2-epoxybutane and 2,3-epoxybutane.
• epoxypropane, epoxyethane or glycidol are preferred, among which 1,2-epoxybutane, epoxypropane or glycidol is more preferred, 1,2-epoxybutane or epoxypropane is more preferred, and epoxypropane is particularly preferred.
• Modified EVOH (a) contains monomer units other than ethylene units, vinyl ester units, vinyl alcohol units, and modifying groups containing primary hydroxyl groups, as long as they do not impair the effects of the present invention. good too.
• the content of other monomer units is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, and particularly preferably not substantially contained.
• 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; Acids and their salts; Unsaturated monomers having a methacrylic acid ester group; Acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidopropanesulfonic acid and its salts, acrylamidopropyl Dimethylamine and its salts (eg quaternary salts); methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidopropanesulfonic acid and its salts, methacrylamidopropyldimethylamine and its salts (eg quaternary salts) ; methyl vinyl ether, ethyl vinyl ether, n-propy
• the resin composition (A) may contain less than 50% by mass of EVOH (a') having a melting point of 150°C or higher.
• the contents described for modified EVOH (a) can be applied to EVOH (a') as they are, except that the melting point is controlled to be high. That is, it is preferable to use non-denatured EVOH as EVOH (a').
• EVOH (a') EVOH having an ethylene unit content of 15 to 60 mol% and a degree of saponification of 90 mol% or more is preferable.
• the lower limit of the ethylene unit content is more preferably 20 mol%, still more preferably 23 mol%.
• the upper limit of the ethylene unit content is more preferably 55 mol%, still more preferably 50 mol%.
• the lower limit of the degree of saponification is preferably 95 mol%, more preferably 99 mol%.
• the upper limit of the degree of saponification is preferably 100 mol%, more preferably 99.99 mol%.
• the lower limit of the content of EVOH (a') is preferably 5% by mass, more preferably 20% by mass, and even more preferably 35% by mass.
• EVOH ethylene glycol dimethacrylate copolymer
• EVAL trademark of Kuraray Co., Ltd.
• the resin composition (A) contains 20 to 1500 ppm of alkali metal ions (b).
• the resin composition (A) contains the alkali metal ion (b) within the above range, the interlayer adhesion with the layer (Y), which will be described later, tends to be remarkably improved.
• the melting point of the modified EVOH (a), which is the main component of the resin composition (A) is less than 150°C, the fluidity of the polymer chains is improved.
• the interlayer adhesion is remarkably improved as compared with the case where the alkali metal ion (b) is contained. If the amount of alkali metal ions (b) is too small, the resin composition (A) tends to thicken during melt-molding, resulting in appearance defects such as gels and lumps, and also the layer (Y) to be described later. Interlayer adhesion may deteriorate. On the other hand, when the alkali metal ion (b) is too much, the resin composition (A) may be excessively decomposed during melt-molding or coloration may become a problem.
• the lower limit of the content of alkali metal ions (b) is preferably 25 ppm, more preferably 30 ppm, even more preferably 35 ppm, and may be 40 ppm.
• the upper limit of the alkali metal ion (b) content is preferably 1000 ppm, more preferably 750 ppm, still more preferably 500 ppm, and may be 300 ppm, 200 ppm or 100 ppm. Further, by controlling the content ratio of the alkali metal ion (b) and the carboxylic acid described later, the melt moldability and coloration resistance of the resulting resin composition (A) can be further improved.
• Alkali metal ions (b) include, for example, lithium, sodium, potassium, rubidium, and cesium ions, but sodium or potassium ions are preferred from the standpoint of industrial availability.
• potassium ions it may be possible to achieve both the hue of the resin composition (A) and the interlayer adhesion with the layer (Y) to be described later at a high level. These may be used alone or in combination of two or more, but it is preferable to use two or more in combination. tend to improve.
• Alkali metal compounds that give alkali metal ions (b) include, for example, aliphatic carboxylates, aromatic carboxylates, carbonates, hydrochlorides, nitrates, sulfates, and phosphoric acids of alkali metals such as lithium, sodium, and potassium. Salts, hydroxides, metal complexes can be mentioned. Among them, aliphatic carboxylates and phosphates are more preferable because they are readily available and easy to handle. Preferred aliphatic carboxylates are acetate, caprylate and stearate.
• the resin composition (A) may contain components other than the modified EVOH (a), the EVOH (a') and the alkali metal ion (b) as long as the effects of the present invention are not impaired.
• Other components include, for example, alkaline earth metal ions and transition metal ions, carboxylic acids (monocarboxylic acids, polyvalent carboxylic acids), modified EVOH (a) and thermoplastic resins other than EVOH (a'), and phosphoric acid compounds.
• the pulverized product of the multilayer structure containing the resin composition (A) is melt-molded, it preferably contains a carboxylic acid and/or a phosphoric acid compound. Further, by including a boron compound, the melt viscosity of the resin composition (A) and the pulverized product of the multilayer structure containing the resin composition (A) can be controlled.
• Alkaline earth metal ions and transition metal ions are not particularly limited, but magnesium ions, calcium ions or zinc ions are suitable.
• the alkaline earth metal ions and transition metal ions are preferably alkaline earth metal salts and transition metal salts, and the anions of the alkaline earth metal salts and transition metal salts are not particularly limited.
• the resin composition (A) contains alkaline earth metal ions and transition metal ions, the content thereof is preferably 20 ppm or more and 300 ppm or less.
• the resin composition (A) preferably contains carboxylic acid.
• 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 color resistance tends to be good.
• the content of the carboxylic acid is 400 ppm or less, it tends to be possible to maintain the interlayer adhesion and suppress the generation of odor.
• the pKa of carboxylic acid is preferably 3.5 to 5.5.
• the resulting resin composition (A) has an increased pH buffering ability, further improving melt moldability and further improving coloration due to acidic substances and basic substances.
• the carboxylic acid may be a monovalent carboxylic acid. These may be used individually by 1 type, and may use 2 or more types together.
• a monovalent carboxylic acid is a compound having one carboxyl group in the molecule.
• These carboxylic acids may further have substituents such as hydroxyl groups, amino groups and halogen atoms. Among them, acetic acid is preferred because it is highly safe and easy to obtain and handle.
• the carboxylic acid may be a polyvalent carboxylic acid.
• the carboxylic acid is a polyvalent carboxylic acid, it may be possible to further improve the coloration resistance of the resin composition (A) at high temperatures and the coloration resistance of the obtained melt-molded product of the crushed multilayer structure.
• the polyvalent carboxylic acid compound preferably has 3 or more carboxyl groups. In this case, it may be possible to improve the coloring resistance more effectively.
• a polyvalent carboxylic acid is a compound having two or more carboxyl groups in the molecule. In this case, the pKa of at least one carboxyl group is preferably 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 phosphate root.
• the upper limit of the content of the phosphate compound is preferably 100 ppm in terms of phosphate root.
• the phosphoric acid compound for example, various acids such as phosphoric acid and phosphorous acid, and salts thereof are used.
• the phosphate may be a primary phosphate, a secondary phosphate, or a tertiary phosphate.
• the cationic species of the phosphate is not particularly limited, the cationic species is preferably an alkali metal or an alkaline earth metal. Among them, sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate are preferable as the phosphoric acid compound.
• the resin composition (A) may further contain a boron compound.
• a boron compound When a boron compound is contained, 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.
• the drawdown resistance and the neck-in resistance during film formation may be improved, and the mechanical properties of the obtained molded article may be improved. These effects are presumed to be due to the occurrence of chelate interaction between the modified EVOH (a) and the boron compound.
• Boron compounds include, for example, boric acid, borate esters, borates, and borohydride.
• boric acids such as orthoboric acid (H 3 BO 3 ), metaboric acid and tetraboric acid; borate esters such as trimethyl borate and triethyl borate; alkali metal salts or alkaline earth metals of the above boric acids Examples include salts, borate salts such as borax, and the like. Among them, orthoboric acid is preferred.
• the resin composition (A) may further contain a hindered phenolic compound.
• a hindered phenolic compound is contained, the content of the hindered phenolic compound in the resin composition (A) is preferably 1000 to 10000 ppm. When the content is 1000 ppm or more, coloration, thickening and gelation of the resin can be suppressed when the pulverized product of the multilayer structure is melt-molded. More preferably, the hindered phenolic compound content is 2000 ppm or more. On the other hand, when the content of the hindered phenol compound is 10000 ppm or less, coloring and bleeding out due to the hindered phenol compound can be suppressed. More preferably, the hindered phenolic compound content is 8000 ppm or less.
• a hindered phenolic compound has at least one hindered phenol group.
• a hindered phenol group is one in which a bulky substituent is attached to at least one of the carbons adjacent to the carbon to which the phenolic hydroxyl group is attached.
• the bulky substituent is preferably an alkyl group having 1 to 10 carbon atoms, more preferably a t-butyl group.
• the hindered phenol compound is preferably in a solid state around 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 more, more preferably 400 or more, and even more preferably 600 or more. On the other hand, the molecular weight is usually 2000 or less.
• 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 phenolic compound preferably has an ester bond or an amide bond.
• Hindered phenol compounds having an ester bond include esters of aliphatic carboxylic acids having a hindered phenol group and aliphatic alcohols, and hindered phenol compounds having an amide bond include hindered phenol groups. and amides of aliphatic carboxylic acids with aliphatic amines. Among them, it is preferable that the hindered phenol-based compound has an amide bond.
• Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] is preferred, the former being more preferred.
• the resin composition (A) may further contain thermoplastic resins other than modified EVOH (a) and EVOH (a').
• thermoplastic resins other than modified EVOH (a) and EVOH (a′) include various polyolefins (polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene and Copolymers with ⁇ -olefins having 4 or more carbon atoms, copolymers of polyolefins and maleic anhydride, ethylene-vinyl ester copolymers, ethylene-acrylic acid ester copolymers, or unsaturated carboxylic acids or Modified polyolefin graft-modified with its derivatives, etc.), various polyamides (nylon 6, nylon 6.6, nylon 6/66 copolymer, nylon 11, nylon 12, poly-metaxylylene adipamide, etc.), various polyesters (polyethylene terephthalate) , poly
• 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. It may be less than mass % or less than 1 mass %, and it is particularly preferably substantially free.
• the ratio of the modified EVOH (a) in the resin constituting the resin composition (A) is preferably 60% by mass or more, more preferably 70% by mass or more, and more preferably 90% by mass or more, particularly preferably 95% by mass or more, may be 98% by mass or more, may be 99% by mass or more, and the resin composition (A)
• the constituent resin may be substantially only the modified EVOH (a).
• the proportion of the modified EVOH (a) in the resin composition (A) is preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass, from the viewpoint that the effects of the present invention are exhibited more remarkably.
• the resin composition (A) is substantially Alternatively, it may consist of modified EVOH (a) and alkali metal ion (b) only.
• the total content of the modified EVOH (a) and EVOH (a′) in the resin constituting the resin composition (A) is preferably 70% by mass or more, and 90% by mass. % or more, more preferably 95% by mass or more, particularly preferably 99% by mass or more, and the resins constituting the resin composition (A) are substantially only modified EVOH (a) and EVOH (a′).
• the total content of the modified EVOH (a) and EVOH (a′) in the resin composition (A) is preferably 70% by mass or more, and 90% by mass or more. More preferably 95% by mass or more, particularly preferably 99% by mass or more, the resin composition (A) consists essentially of modified EVOH (a), EVOH (a') and alkali metal ions (b). can be anything.
• melt flow rate (MFR) of the resin composition (A) measured according to the method described in JIS K7210 (2014) (210°C, under 2160g load) is 0.1 to 30g. /10 min, more preferably 0.3 to 25 g/10 min, even more preferably 0.5 to 20 g/10 min.
• the method for producing the resin composition (A) is not particularly limited, but it can be produced by melt-kneading the modified EVOH (a), the alkali metal ion (b), and optionally other components such as the EVOH (a').
• 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 as a dispersoid contained in a dispersion.
• Aqueous solutions and aqueous dispersions are suitable as solutions and dispersions, respectively.
• melt-kneading For melt-kneading, known mixing or kneading devices such as a kneader ruder, an extruder, a mixing roll, and a Banbury mixer can be used.
• the temperature range during melt-kneading can be appropriately adjusted according to the modified EVOH (a) to be used and the melting point of each component. Further, it may be produced by previously adding some components to the modified EVOH (a), and then melt-kneading additional necessary components as described above.
• Examples of the method of adding some components to the modified EVOH (a) in advance include a method of immersing the modified EVOH (a) as pellets or powder in a solution in which the added components are dissolved. An aqueous solution is suitable as the solution.
• the multilayer film of the present invention has a layer (Y) containing, as a main component, an adhesive resin (B) having a melting point of less than 150°C. Including the layer (Y) in the multilayer film of the present invention tends to provide a multilayer film having excellent appearance and interlayer adhesion.
• the adhesive resin (B) include carboxylic acid-modified polyolefin resins obtained by graft-polymerizing unsaturated carboxylic acids such as maleic anhydride or derivatives thereof to polyolefin resins.
• the melting point of the adhesive resin (B) mainly depends on the polyolefin resin before carboxylic acid modification.
• the content described for the polyethylene resin (C) described later can be applied as it is. That is, the adhesive resin (B) preferably contains a carboxylic acid-modified polyethylene resin as a main component, more preferably a carboxylic acid-modified polyethylene 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 still more preferably 95% by mass or more, and substantially consists of only the carboxylic acid-modified polyolefin resin. may be configured.
• 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, even more preferably 95% by mass or more, and substantially the adhesive resin (B) It may be composed only of
• the multilayer film of the present invention has a layer (Z) containing a polyethylene resin (C) having a melting point of less than 150°C as a main component.
• the polyethylene resin (C) is not particularly limited as long as it has a melting point of less than 150° C., and examples thereof include polyethylene resins such as linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, and high-density polyethylene. Because polyethylene resins are widely used in packaging materials regardless of whether they have gas barrier properties, the recycling infrastructure for them is widely developed in each country.
• Polyethylene resin (C) is preferably at least one selected from linear low density polyethylene, low density polyethylene, medium density polyethylene and high density polyethylene, and is selected from linear low density polyethylene and low density polyethylene. More preferably, it is at least one kind, or a mixture of at least one kind selected from linear low-density polyethylene and low-density polyethylene and high-density polyethylene.
• the polyethylene resin (C) is preferably not modified with carboxylic acid.
• the melting point of the polyethylene resin (C) is preferably less than 140°C, more preferably less than 130°C.
• the melting point of the polyethylene resin (C) is preferably 80° C. or higher, more preferably 90° C. or higher, from the viewpoint of process passability during melt molding and secondary processing such as stretching, and from the viewpoint of heat resistance as a packaging material.
• the melt flow rate (MFR) (210° C., under a load of 2160 g) measured according to the method described in JIS K7210 (2014) of the polyethylene resin (C) is 0.1 to 0.1. 30 g/10 min is preferred, 0.3 to 25 g/10 min is more preferred, and 0.5 to 20 g/10 min is even more preferred.
• the proportion of the polyethylene 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 substantially consists of only the polyethylene resin (C).
• Layer (Y) and layer (Z) contain adhesive resin (B) and polyethylene resin (C) as main components, respectively.
• the total amount for each layer is less than 50% by mass, 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.
• the multilayer film of the present invention has the layer (X) as the outermost layer, and has a structure in which at least the layer (X), the layer (Y) and the layer (Z) are laminated adjacently in this order.
• Each layer (X), layer (Y), and layer (Z) may have a plurality of layers.
• X represents layer (X)
• Y represents layer (Y)
• Z represents layer (Z). Examples include Y/Z, X/Y/Z/Y/X, X/Y/Z/Y/X/Y/Z/Y/X.
• the thickness of the layer (X) of the multilayer film of the present invention is preferably 0.2 ⁇ m or more and less than 20 ⁇ m. It is also preferable that the ratio of the thickness of layer (X) to the total thickness of all layers in the multilayer film is less than 25%.
• the thickness of the layer (X) is more preferably 0.4 ⁇ m or more and less than 16 ⁇ m, still more preferably 0.6 ⁇ m or more and less than 12 ⁇ m.
• the ratio of the thickness of the layer (X) to the total thickness of all layers in the multilayer film is more preferably less than 20%, more preferably less than 15%.
• the thickness of all layers of the multilayer film is usually 10 ⁇ m or more and less than 200 ⁇ m, preferably 10 ⁇ m or more and less than 150 ⁇ m. In the case of the stretched multilayer film described later, the thickness of all layers is preferably 10 ⁇ m or more and less than 50 ⁇ m, more preferably less than 40 ⁇ m.
• the multilayer film of the present invention may be an unstretched multilayer film, or may be a stretched multilayer film stretched uniaxially or biaxially (at least uniaxially). Uniaxial or biaxial stretching can improve the mechanical properties and gas barrier properties of the resulting multilayer film.
• the multilayer film is preferably a uniaxially stretched multilayer film from the viewpoint of economy and ease of tearing the multilayer film (easy to open the packaging material when used as a packaging material), and is anisotropic in mechanical properties.
• the multilayer film is preferably a biaxially stretched multilayer film from the viewpoint of obtaining a tough film with a small amount of .
• the film is stretched 3 times or more and less than 12 times in at least one axial direction.
• a uniaxially stretched multilayer film it is preferably uniaxially stretched 3 times or more and less than 12 times, more preferably 4 times or more and less than 10 times.
• a biaxially stretched multilayer film it is preferably stretched 3 times or more and less than 12 times, more preferably 4 times or more and less than 10 times, in each of the biaxial directions.
• the method for producing the multilayer film of the present invention is not particularly limited, but in general, a conventional coextrusion method in which each resin is extruded from separate dies or a common die and laminated can be used.
• a conventional coextrusion method in which each resin is extruded from separate dies or a common die and laminated can be used.
• the die either an annular die or a T-die can be used.
• the method of stretching uniaxially or biaxially is also not particularly limited, and by a conventionally known stretching method such as roll uniaxial stretching, tubular simultaneous biaxial stretching, tenter successive biaxial stretching, and tenter simultaneous biaxial stretching.
• the film can be produced by stretching in the machine direction and/or in the direction perpendicular to the machine direction, that is, in the width direction.
• the effect of the present invention is particularly remarkable 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, from the standpoint of workability.
• the multilayer film of the present invention has the advantage that even when the stretching temperature is relatively low such as 120° C., problems such as poor appearance after stretching and deterioration of interlaminar adhesion are less likely to occur.
• heat treatment is preferably performed at a temperature above the glass transition point and below the melting point to increase the degree of crystallinity and to fix the orientation of the molecular chains, so-called heat setting operation is preferably performed.
• the above object can also be achieved by a vapor-deposited multilayer film comprising an inorganic vapor-deposited layer (I) on the exposed surface side of the layer (X) of the multilayer film of the present invention.
• the inorganic deposition layer (I) is a layer made of inorganic substances such as metals and inorganic oxides and having gas barrier properties against oxygen and water vapor.
• the layer (X) has a higher affinity for metals and inorganic oxides than ordinary thermoplastic resins, and can form a dense and defect-free inorganic vapor deposition layer (I). The interlayer adhesion between the layer (X) and the inorganic deposition layer (I) becomes good.
• the thickness of the inorganic vapor deposition layer (I) is generally less than 500 nm. When the thickness is less than 500 nm, the pulverized multilayer structure containing the inorganic vapor deposition layer (I) is melt-molded with excellent viscosity stability, and the generation of gels and lumps can be suppressed.
• the inorganic vapor deposition layer (I) 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 imparting a light-shielding property, but from the viewpoint of the visibility of the contents as a packaging material, the range suitability, and the ability to suppress the generation of gels and lumps when melting and molding the pulverized material, inorganic oxidation A vapor deposited layer is preferred.
• a metal vapor deposition layer is generally a layer containing aluminum as a main component.
• the content of aluminum atoms in the metal deposition layer is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, and particularly preferably 95 mol% or more.
• the average thickness of the vapor-deposited metal layer is preferably 120 nm or less, more preferably 100 nm or less, and even more preferably 90 nm or less. Also, the average thickness of the metal 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 vapor deposited metal layer is the average value of the thickness at arbitrary 10 points on the cross section of the vapor deposited metal layer measured with an electron microscope.
• the light transmittance at a wavelength of 600 nm can be 10% or less, and the film has excellent light shielding properties.
• the inorganic oxide deposited layer is an inorganic oxide such as oxides of silicon, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, yttrium, preferably alumina or silica. mentioned.
• the average thickness of the inorganic oxide deposition layer is preferably 60 nm or less, more preferably 50 nm or less, and even more preferably 40 nm or less.
• the average thickness of the inorganic oxide deposition layer is preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more.
• the average thickness of the deposited inorganic oxide layer is the average value of the thickness at arbitrary 10 points on the cross section of the deposited inorganic oxide layer measured with 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 the thickness unevenness of the multilayer film of the present invention used for producing the vapor-deposited multilayer film.
• the layer (X) which is the outermost layer, contains the modified EVOH (a) having a melting point of less than 150°C as a main component, the thickness unevenness is suppressed, so that it tends to exhibit a high light transmittance.
• Examples of means for further suppressing the thickness unevenness of the multilayer film of the present invention include stretching in at least one axial direction.
• the light transmittance of the multilayer film of the present invention at a wavelength of 600 nm is preferably 80% or more, more preferably 90% or more.
• the inorganic vapor deposition layer (I) can be formed by a known physical vapor deposition method or chemical vapor deposition method. Specific examples include vacuum vapor deposition, sputtering, ion plating, ion beam mixing, plasma CVD, laser CVD, MO-CVD, and thermal CVD, but physical vapor deposition is used. Among them, it is particularly preferable to use a vacuum deposition method. If necessary, a protective layer (topcoat layer) may be provided on the inorganic deposition layer (I) as long as the effects of the present invention are not hindered.
• the upper limit of the surface temperature of the layer (X) during formation of the inorganic deposition 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 formation of the inorganic deposition 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 layer (X) may be plasma-treated prior to film formation.
• a known method can be used for the plasma treatment, and atmospheric pressure plasma treatment is preferred.
• nitrogen, helium, neon, argon, krypton, xenon, radon, etc. are used as discharge gas. Among them, nitrogen, helium, and argon are preferably used, and nitrogen is particularly preferable because it can reduce costs.
• the multilayer film or vapor-deposited multilayer film of the present invention has an oxygen transmission rate of 60 cc/(m 2 ⁇ day ⁇ atm), more preferably less than 40 cc/(m 2 ⁇ day ⁇ atm), even more preferably less than 20 cc/(m 2 ⁇ day ⁇ atm), and 5 cc /(m 2 ⁇ day ⁇ atm) is even more preferable, and less than 1 cc/(m 2 ⁇ day ⁇ atm) is particularly preferable.
• a multilayer film and a vapor-deposited multilayer film having an oxygen transmission rate within the above range have excellent gas barrier properties.
• the multilayer film of the present invention or the deposited multilayer film itself can be used as a packaging material having gas barrier properties, but it is laminated with at least one resin layer (R) containing a thermoplastic resin (D) as a main component.
• R resin layer
• D thermoplastic resin
• the thermoplastic resin (D) is not particularly limited, and linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, vinyl ester resin, ethylene-propylene copolymer, polypropylene, propylene- ⁇ -olefin Copolymers ( ⁇ -olefins with 4 to 20 carbon atoms), olefins such as polybutene and polypentene, or their copolymers, polyamides such as nylon 6 and nylon 6,6, polyethylene terephthalate, polybutylene terephthalate, polyethylene nano Polyester such as phthalate, polystyrene, polyvinyl chloride, polyvinylidene chloride, acrylic resin, polycarbonate, chlorinated polyethylene, chlorinated polypropylene and the like can be mentioned.
• the thermoplastic resin (D) is preferably of the same type as the polyethylene resin (C) described above, that is, a polyethylene resin having a melting point of less than 150°C. Therefore, in order to obtain a multilayer structure with excellent recyclability, it is preferable that the polyethylene resin (C) and the thermoplastic resin (D) are polyethylene resins.
• a resin layer (R) may be unstretched, or stretched or rolled uniaxially or biaxially. From the viewpoint of improving mechanical strength, it is preferably a biaxially stretched layer, and from the viewpoint of improving heat sealability, it is preferably a non-stretched layer.
• the method of forming the resin layer (R) is not particularly limited, it is generally formed by melt extrusion using an extruder.
• the die either an annular die or a T-die can be used.
• the method of stretching uniaxially or biaxially is also not particularly limited, and by a conventionally known stretching method such as roll uniaxial stretching, tubular simultaneous biaxial stretching, tenter successive biaxial stretching, and tenter simultaneous biaxial stretching.
• the film can be produced by stretching in the machine direction and/or in the direction perpendicular to the machine direction, that is, in the width direction.
• the draw ratio is preferably 8 to 60 times the area from the viewpoint of the uniformity of the thickness of the layer to be obtained and the mechanical strength.
• the area magnification is more preferably 55 times or less, more preferably 50 times or less. Further, the area magnification 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 thickness of the resin layer (R) is preferably 10-200 ⁇ m from the viewpoint of industrial productivity. Specifically, the thickness of the non-stretched layer is more preferably 10 to 150 ⁇ m, and the thickness of the biaxially stretched layer is more preferably 10 to 50 ⁇ m.
• the total thickness of the multilayer structure of the present invention is preferably 300 ⁇ m or less.
• the multilayer structure of the present invention is lightweight and flexible, and is preferably used for flexible packaging. Moreover, the amount of resin used in the multilayer structure is small, and the environmental load is suppressed.
• each layer in the multilayer structure of the present invention may be appropriately adjusted according to the application, but when the pulverized product is melt-molded, coloration can be suppressed, the thermal stability during melt-molding is improved, and the occurrence of pimples. is suppressed, the ratio of the total thickness of the layers containing polyethylene resin as a main component to the total thickness of the multilayer structure is preferably 0.75 or more, more preferably 0.85 or more. On the other hand, from the viewpoint of improving gas barrier properties, the ratio is preferably 0.98 or less.
• the layer containing polyethylene resin as the main component means the layer (Z) and layer (Y) containing carboxylic acid-modified polyethylene resin as the main component, and the resin layer (R) containing polyethylene as the main component. It means one containing resin as a main component.
• the multilayer structure of the present invention preferably does not have a layer containing resin having a melting point of 240°C or higher as a main component and a metal layer having a thickness of 1 ⁇ m or more.
• a layer containing a resin having a melting point of 240° C. or more as a main component and a metal layer having a thickness of 1 ⁇ m or more mixing with other components is uneven when the pulverized product of the multilayer structure is melt-molded. can be prevented from becoming
• a metal layer is a layer which has a continuous and discontinuous surface which consists of metals, such as an aluminum foil, here.
• the multilayer structure of the present invention does not have a layer containing a resin having a melting point of 220° C. or higher as a main component, and does not have a layer containing a resin having a melting point of 200° C. or higher as a main component. is more preferred.
• the method of laminating the resin layer (R) on the multilayer film of the present invention is not particularly limited, and examples thereof include extrusion lamination, co-extrusion lamination, and dry lamination.
• An adhesive layer may be provided when the resin layer (R) is laminated on the multilayer film. That is, each layer constituting the multilayer structure of the present invention may be laminated via an adhesive layer, if necessary. However, the multilayer film does not have an adhesive layer between the layer (X) and the layer (Y) and between the layer (Y) and the layer (Z).
• the adhesive layer can be formed by applying a known adhesive and drying it.
• the adhesive is preferably a two-liquid reactive polyurethane adhesive in which a polyisocyanate component and a polyol component are mixed and reacted.
• the thickness of the adhesive layer is not particularly limited, it is preferably 1 to 5 ⁇ m, more preferably 2 to 4 ⁇ m.
• the multilayer structure of the present invention is not particularly limited, and for example, the following layer structure is preferable from the viewpoint of obtaining a multilayer structure excellent in recyclability.
• the layer (X) is expressed as X, the layer (Y) as Y, the layer (Z) as Z, the inorganic deposition layer (I) as I, and the layer (R) as R. means that it is laminated directly, and "//" means that it is laminated via an adhesive layer.
• the layer (X), the layer (Y) and the layer (Z) are preferably stretched in at least one direction, more preferably biaxially stretched.
• Layer (Z) and layer (R) are preferably polyethylene resins, and layer (Y) is preferably maleic anhydride-modified polyethylene resin.
• 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.
• Examples of other layers include collection layers.
• Other examples of other layers include, for example, printing layers.
• the printed layer may be included anywhere in the multilayer structure of the present invention.
• Examples of the printed layer include a film obtained by applying a solution containing a pigment or dye and, if necessary, a binder resin, followed by drying.
• Examples of coating methods for the printed layer include gravure printing, as well as various coating methods using a wire bar, a spin coater, a die coater, and the like.
• the thickness of the ink layer is not particularly limited, it is preferably 0.5 to 10 ⁇ m, more preferably 1 to 4 ⁇ m.
• a method for recovering a multilayer structure in which the multilayer structure of the present invention is pulverized 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 pulverized.
• the recovered pulverized material may be directly melt-molded 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 polyethylene resin.
• the polyethylene resin the same kind of polyethylene resin (C) as used in the multilayer film of the present invention is used.
• the recovered pulverized material may be used directly for manufacturing molded articles such as multilayer structures, or the recovered pulverized material may be melt-molded to obtain pellets made of the recovered composition, and then the pellets may be used as molded articles. may be used for the production of
• the mass ratio of the resin composition (A) to the polyethylene resin [resin composition (A)/polyethylene resin] in the recovered composition is preferably 0.01/99.99 to 20/80. If the mass ratio is less than 0.01/99.99, there is a risk that the usage rate of the recovered material will decrease. On the other hand, if the mass ratio exceeds 20/80, the melt moldability and mechanical properties of the recovered composition may deteriorate. From the viewpoint of improving the melt moldability and mechanical properties of the obtained recovered composition, the mass ratio is more preferably 15/85 or less, 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, it can be suitably used as a material for various packaging such as food packaging, pharmaceutical packaging, industrial chemical packaging, and agricultural chemical packaging.
• a packaging material having a structure can be suitably used as a packaging material with excellent recyclability.
• Example 1 (1) Production of Resin Composition (A) Containing Modified EVOH (a) 28 parts by mass of zinc acetylacetonate monohydrate was mixed with 957 parts by mass of 1,2-dimethoxyethane to obtain a mixed solution. 15 parts by mass of trifluoromethanesulfonic acid was added to the obtained mixed solution while stirring to obtain a catalyst solution. Next, EVOH having an ethylene unit content of 44.0 mol% and a degree of saponification of 99.9 mol% or more (but not including alkali metal ions) was extruded by a TEM-35BS extruder manufactured by Toshiba Machine Co., Ltd.
• the obtained resin composition (A1) pellets were dissolved in dimethyl sulfoxide (DMSO)-d6 containing tetramethylsilane as an internal standard substance, and 500 MHz 1 H-NMR (manufactured by JEOL Ltd. “GX-500”). was measured at 80°C using As a result of analyzing the obtained spectrum, it was found that the epoxy-modified unit (represented by the above general formula (I), R 1 and R 2 are hydrogen atoms, one of R 3 and R 4 is a hydrogen atom and the other is a methyl group) A certain modifying group), the content was 4.6 mol %.
• DMSO dimethyl sulfoxide
• GX-500 500 MHz 1 H-NMR
• the content of the alkali metal ion (b) was quantified by measuring this solution with an ICP emission spectrometer ("Optima 4300DV" manufactured by Perkin Elmer).
• the content of alkali metal ions (b) was 30 ppm for sodium ions and 15 ppm for potassium ions.
• the yellowness (YI) of the resin composition (A1) pellets obtained in (1) above was measured using a spectrophotometer ("LabScan XE Sensor" manufactured by HunterLab). and determined according to the following criteria.
• the YI value is an index representing the yellowness of an object, and the higher the YI value, the stronger the yellowness, while the lower the YI value, the weaker the yellowness and less coloring.
• the temperature conditions of the extruder were set as follows according to the melting point of the modified EVOH.
• Cylinder temperature Supply unit: 160°C Compressed part: Melting point of modified EVOH +4 to 80°C
• Weighing part Melting point of modified EVOH +40 to 80°C
• Die temperature Melting point of modified EVOH +40 to 80°C
• Oxygen permeability of single layer film of resin composition (A1) For the single layer film of resin composition (A1) obtained in (6) above, JIS K 7126-2 (isobaric method; 2006) The oxygen transmission rate was measured according to the method described. Specifically, using an oxygen permeation measurement device ("MOCON OX-TRAN2/21" manufactured by Modern Control Co., Ltd.), the temperature was 20 ° C., the humidity on the oxygen supply side was 65% RH, the humidity on the carrier gas side was 65% RH, oxygen The oxygen permeation rate (unit: cc/(m 2 ⁇ day ⁇ atm)) was measured under the conditions of 1 atm pressure and 1 atm carrier gas pressure, and judged according to the following criteria.
• MOCON OX-TRAN2/21 manufactured by Modern Control Co., Ltd.
• Polyethylene resin (“Innate (trademark) TF80” manufactured by Dow Chemical Co., Ltd.; low-density polyethylene, melting point 122 ° C.)
• Polyethylene adhesive resin (“Amplify (trademark) TY1353” manufactured by Dow Chemical Co.
• the thickness of the coextruded film was adjusted by appropriately changing the screw rotation speed and take-up roll speed.
• the extruder, extrusion conditions, and the die used were as follows.
• Resin composition (A1) Extruder: Single-screw extruder (Toyo Seiki Co., Ltd. Lab Machine ME type CO-EXT) Screw: caliber 20 mm ⁇ , L/D20, full flight screw
• Polyethylene adhesive resin Extruder: single screw extruder (Technobell Co., Ltd.
• Judgment Standard sequential stretchability (3 ⁇ 3) A: It can be successively stretched at a draw ratio of 3 ⁇ 3, and has a uniform appearance without unevenness B: It can be successively stretched at a draw ratio of 3 ⁇ 3, but unevenness and / or streaks are slightly observed C: Stretch ratio of 3 ⁇ Although it was possible to stretch sequentially in 3, unevenness and / or streaks can be seen D: Successive stretching was possible at a draw ratio of 3 ⁇ 3, but significant unevenness and/or streaks were observed. E: Sequential stretching was not possible at a draw ratio of 3 ⁇ 3, and cracks were observed. A: It can be successively stretched at a draw ratio of 4 ⁇ 4, and has a uniform appearance without unevenness.
• Blocking resistance evaluation A sample obtained by cutting the center of the non-stretched multilayer film obtained in (8) above into a 100 mm square was measured by a biaxially stretched birefringence measuring device (manufactured by Eto Co., Ltd., model: SDR-506WK) (stretch chuck (5 points on one side, 1 point on each corner, 24 points in total, each chuck having a length of 10 mm and a width of 6.5 mm). The number of places where the molten film adhered among all 24 stretching chucks was counted, and the degree of adherence of the molten resin to the chuck, that is, blocking resistance was evaluated. Table 1 shows the results. Note that D is an unacceptable criterion. Judgment: Criteria A: 5 or less B: 6 or more and 10 or less C: 11 or less 15 or less D: 16 or more
• Examples 2 to 18 and Comparative Examples 3, 5, 6 A resin composition was prepared in the same manner as in Example 1, except that the ethylene unit content, the type of modifier, the content of the modifying group, and the content of the alkali metal ion (b) were changed as shown in Table 1. (A2)-(A18), (AC3), (AC5) and (AC6) pellets were produced and evaluated. Table 1 shows the results. The modifying group content and the alkali metal ion content were adjusted by appropriately adjusting the additive amount of the modifier, the additive amount of the catalyst, and the concentration and additive amount of the alkali metal ion-containing aqueous solution.
• Example 19 (1) Production of multilayer film Resin composition (A2) pellets obtained in Example 2, polyethylene resin ("Innate (trademark) TF80” manufactured by Dow Chemical Co.; low density polyethylene, melting point 122°C) and polyethylene adhesion Resin (“Amplify (trademark) TY1353” manufactured by Dow Chemical Co.; maleic anhydride graft-modified linear low-density polyethylene adhesive resin, melting point 124 ° C.) was used, and the extruder type and temperature conditions were the same as those in Example 2.
• polyethylene resin (“Innate (trademark) TF80” manufactured by Dow Chemical Co.; low density polyethylene, melting point 122°C)
• polyethylene adhesion Resin (“Amplify (trademark) TY1353” manufactured by Dow Chemical Co.; maleic anhydride graft-modified linear low-density polyethylene adhesive resin, melting point 124 ° C.) was used, and the extruder type and temperature conditions were the same as those in Example 2.
• the thickness of the coextruded film was adjusted by appropriately changing the screw rotation speed and take-up roll speed.
• the temperature was 20 ° C.
• the humidity on the oxygen supply side was 65% RH
• the humidity on the carrier gas side was 65% RH
• oxygen Oxygen permeability (unit: cc/(m 2 ⁇ day ⁇ atm)) was measured under the conditions of 1 atm pressure and 1 atm carrier gas pressure, and judged according to the following criteria.
• Nitrogen gas containing 2% by volume of hydrogen gas was used as the carrier gas.
• the oxygen permeability after bending treatment was also measured. Specifically, first, the multilayer film was made into a cylinder with a diameter of 3.5 inches, and this was gripped at both ends, with an initial grip interval of 7 inches, a grip interval at maximum bending of 1 inch, and the first 3.5 inches of the stroke. Oxygen permeability was measured in the same manner as above after 10 reciprocating motions at a rate of 30/min consisting of repetitions of a 330° angle twist followed by 2.5 inches of straight horizontal motion. was measured. Table 2 shows the results.
• Example 25 On the surface of the resin composition layer of the three-kind, three-layer biaxially stretched multilayer film produced in Example 23, a 30 nm-thick alumina inorganic oxide vapor deposition was performed by a known vacuum vapor deposition method, followed by inorganic oxide vapor deposition biaxial stretching.
• Table 2 shows the results.
• Resin composition (A2) A polyethylene resin film having a thickness of 20 ⁇ m was produced in the same manner as in Example 23, except that the pellets and the polyethylene adhesive resin were not used, and the extrusion conditions were changed. A polyethylene resin film was produced and evaluated. Table 2 shows the results.
• Novatec (trademark) LD LJ400 manufactured by Japan Polyethylene Co., Ltd.; low density polyethylene, melting point 108 ° C.
• a recovered composition film having a thickness of 50 ⁇ m was obtained by forming a single layer film under the extrusion conditions shown in .
• the thickness of the film was adjusted by appropriately changing the screw rotation speed and take-up roll speed.
• a polyethylene film having a thickness of 50 ⁇ m was similarly obtained using only the polyethylene resin.
• Extrusion temperature: C1/C2/C3/D 160/190/190/190°C
• the extrudability of the recovered composition was stable and good.
• the recovered composition film had almost the same amount of gels and lumps as compared with the polyethylene film, and had a uniform and good appearance except for slight coloration.

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