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
  • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
• • 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
  • 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
  • B32B7/02—Physical, chemical or physicochemical properties
  • B32B7/027—Thermal properties
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/048—Forming gas barrier coatings

Definitions

• the present invention relates to a multilayer film, a vapor-deposited multilayer film, and a multilayer structure, as well as a packaging material, a recovery composition, and a recovery method using the same.
• Packaging materials for long-term storage of foods and the like are often required to have gas barrier properties, including oxygen barrier properties.
• gas barrier properties including oxygen barrier properties.
• Metal foils or metal deposition layers such as aluminum, 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 exhibit gas barrier properties by crystallizing and densifying due to hydrogen bonding between hydroxyl groups in the molecules.
• EVOH ethylene-vinyl alcohol copolymers
• recycling post-consumer recycling
• a process is generally adopted in which the recovered packaging materials are 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 resin.
• barrier films made mainly of polyolefins, which are widely used as packaging materials.
• a vapor-deposited multilayer film has been proposed in which an inorganic vapor-deposited layer is laminated on the surface of the EVOH layer of a polyolefin-based multilayer film, the outermost layer of which is an EVOH layer, in order to achieve extremely high gas barrier properties (Patent Document 2).
• the EVOH experiences large shear stress with the metal wall surface in the extrusion flow path, which can adversely affect the appearance of the resulting multilayer film.
• the resin at the ends of the film spends a long time in the extrusion flow path, which causes the EVOH to remain inside the die, leading to viscosity changes and degradation, which can lead to more noticeable defects in the appearance of the multilayer film.
• the first object of the present invention is to provide a multilayer film and a manufacturing method thereof that are excellent in appearance characteristics, gas barrier properties, and recyclability even when the film width is 500 mm or more.
• the second object of the present invention is to provide, using the multilayer film, a vapor-deposited multilayer film, a multilayer structure, and a packaging material containing the multilayer structure, that are excellent in appearance characteristics, gas barrier properties, and recyclability.
• the third object of the present invention is to provide a recovered composition containing a recovered material of the multilayer structure, and a recovery method thereof.
• the object is to [1] A multilayer film having a layer (X) as an outermost layer, and a layer (X), a layer (Y) and a layer (Z) laminated adjacent to each other in this order, wherein the layer (X) is a layer made only of a resin composition (A) containing an ethylene-vinyl alcohol copolymer (a1) (hereinafter sometimes abbreviated as "EVOH (a1)”) having an ethylene unit content of 20 to 50 mol% and a saponification degree of 90 mol% or more and a polyvalent metal ion (a2), the layer (Y) contains an adhesive resin (B) having a melting point of less than 170°C as a main component, the layer (Z) contains a polyolefin resin (C) having a melting point of less than 170°C as a main component, the resin composition (A) contains 350 to 2000 ppm of the polyvalent metal ion (a2), and the polyvalent metal ion (a)
• [14] The multilayer film of any one of [1] to [13], in which the ratio of the total average thickness of layers mainly composed of a polyethylene-based resin or a polypropylene-based resin is 75% or more;
• [15] The multilayer film of any of [1] to [14], wherein the image clarity CMD when the longitudinal direction of the multilayer film is the vertical direction and the image clarity CTD when the width direction is the vertical direction at an optical comb width of 2.0 mm, which are measured in accordance with JIS K7374 (2007, transmission method) centered on 10%, 50% and 90% positions when the position of one end of the multilayer film in the width direction is 0% and the position of the other end is 100%, are all 60% or more, and the standard deviation of the image clarity CMD and the standard deviation of the image clarity CTD measured at the measurement positions are both 10% or less; [16] The multilayer film of any of [1] to [15], wherein the image clarity of the multilayer film at an optical comb width of 2.0 mm, measured in accordance
• a multilayer film having excellent appearance characteristics, gas barrier properties, and recyclability can be provided.
• a vapor-deposited multilayer film, a multilayer structure, and a packaging material using the same having excellent appearance characteristics, gas barrier properties, and recyclability 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.
• the "appearance characteristics" can be evaluated by visually observing the appearance of the multilayer film, particularly the state of streaks in the multilayer film, and can be specifically evaluated by the method 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, gelation of the resin is suppressed, and a recovered composition having excellent appearance can be efficiently produced, and can be specifically evaluated by the method described in the Examples.
• the 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, layer (X) is a layer consisting of only a resin composition (A) containing EVOH (a1) having an ethylene unit content of 20 to 50 mol% and a saponification degree of 90 mol% or more and polyvalent metal ions (a2), layer (Y) contains adhesive resin (B) having a melting point of less than 170°C as a main component, layer (Z) contains polyolefin resin (C) having a melting point of less than 170°C as a main component, resin composition (A) contains 350 to 2000 ppm of polyvalent metal ions (a2), and the polyvalent metal ions (a2) are at least one selected from the group consisting of magnesium ions, calcium ions, zinc ions, cobalt ions and manganese ions, and has a width of 500 mm or more.
• EVOH (a1) has excellent gas barrier properties, and the multilayer film of the present invention having layer (X) as the outermost layer can achieve high gas barrier properties.
• EVOH (a1) of the outermost layer has high affinity with the inorganic vapor deposition layer (I) described later, when it is made into a vapor deposition film of the present invention, it tends to stably exhibit high gas barrier properties.
• EVOH (a1) has high affinity with the metal surface of an extruder, etc., so that the appearance characteristics are easily deteriorated during the production of a multilayer film.
• the present inventors have found that by using a resin composition (A) containing EVOH (a1) and polyvalent metal ions (a2), in which the resin composition (A) contains 350 to 2000 ppm of polyvalent metal ions (a2), the slipperiness between the metal surface of an extruder or the like and the molten resin during the production of a multilayer film is improved, and the interfacial stress between the EVOH layer (layer (X)) and the adhesive resin layer (layer (Y)) is reduced, resulting in reduced unevenness in the thickness of the EVOH layer (layer (X)) and reduced disturbance at the layer interface, and as a result, reduced deterioration in appearance characteristics during production.
• the layer (X), the layer (Y), and the layer (Z) are stacked adjacent to each other in this order means that adjacent layers are directly stacked, and specifically means that the layer (X), the layer (Y), and the layer (Z) are stacked in this order, the layer (X) and the layer (Y) are directly stacked, and the layer (Y) and the 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, etc. refers to the average value of thicknesses measured at any five points, unless otherwise specified.
• 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 groups contain atoms other than carbon, oxygen, and hydrogen atoms.
• Polypropylene refers to a homopolymer of propylene, a copolymer of 80 mol % or more of propylene and 20 mol % or less of an ⁇ -olefin monomer, and a copolymer of 90 mol % or more of propylene and less than 10 mol % of a non-olefin monomer whose functional groups 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.
• the term "acid-modified polypropylene” refers to a polymer obtained by modifying polypropylene with an acid.
• the acid-modified polypropylene may be a polymer in which at least one of an acidic group and an acid anhydride group is introduced into polypropylene.
• polyethylene resin refers to polyethylene and modified polyethylene (such as acid-modified polyethylene).
• Modified polyethylene refers to a polymer obtained by modifying polyethylene.
• polypropylene resin refers to polypropylene and modified polypropylene (such as acid-modified polypropylene).
• Modified polypropylene refers to a polymer obtained by modifying polypropylene.
• a multilayer film or a multilayer structure does not mean to distinguish between the front and back, but refers to the exposed surface.
• a multilayer film or a multilayer structure has two surfaces.
• a multilayer film or a multilayer structure has two outermost layers.
• "consists essentially of” means that optional components may be contained within a range that does not affect the effects of the present invention, and “consists only of” means that optional components other than impurities that are inevitably contained are excluded.
• a numerical range described using “to” means that the numerical range includes the numerical values before and after "to” as the lower limit and upper limit.
• the multilayer film constituting the multilayer film of the present invention has, as an outermost layer, a layer (X) made of a resin composition (A) containing EVOH (a1) having an ethylene unit content of 20 to 50 mol% and a saponification degree of 90 mol% or more and a polyvalent metal ion (a2).
• EVOH(a1) is usually obtained by saponifying an ethylene-vinyl ester copolymer obtained by polymerizing ethylene and a vinyl ester.
• the ethylene unit content of EVOH (a1) is 20 to 50 mol%. When the ethylene unit content is 20 mol % or more, the melt moldability of the EVOH (a1) and the pulverized product of the multilayer film or multilayer structure containing the EVOH (a1) is improved.
• the ethylene unit content is The ethylene unit content is preferably 23 mol% or more, more preferably 26 mol% or more, and may be 29 mol% or more.
• the gas barrier property of the 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 ethylene unit content is the ratio of the ethylene unit content to the total monomer units constituting the EVOH. The content (mol %) of ethylene units.
• the saponification degree of EVOH (a1) 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 (a1).
• the saponification degree is preferably 95 mol% or more, more preferably 99 mol% or more, and even more preferably 99.9 mol% or more.
• the upper limit of the saponification degree of EVOH (a1) may be 100 mol%.
• the ethylene unit content and saponification degree of EVOH (a1) are determined by 1 H-NMR measurement.
• EVOH (a1) 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 (a1) may be a mixture of two or more types of EVOH having different saponification degrees.
• the difference in saponification degree between the EVOHs having the most different ethylene unit contents is preferably 7 mol% or less, more preferably 5 mol% or less, and may be 0.5 mol% or more.
• EVOH low ethylene
• high ethylene 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 (low ethylene/high ethylene) of 60/40 to 90/10 and use the mixture as EVOH (a1).
• EVOH (a1) may be EVOH (a'1) having a melting point of less than 150°C.
• the melting point of EVOH (a'1) is less than 150°C, the appearance and interlayer adhesion of a multilayer film having a layer (X) mainly composed of EVOH (a'1) as the outermost layer may be improved.
• the reason for this is that the melting point of EVOH (a'1) is less than 150°C, which improves the fluidity of the polymer chain, and therefore stress can be effectively relaxed even at a relatively low temperature during melt molding or secondary processing such as stretching, and the adhesive reaction activity with adjacent layers can be maintained.
• the melting point of EVOH (a'1) 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'1) is preferably not less than 80° C., more preferably not less than 90° C., and even more preferably not less than 100° C.
• the melting point of EVOH (a'1) is controlled by one or a combination of the following items, and in the present invention, the following method (3) can be preferably used.
• the primary hydroxyl group-containing modifying group used in (3) above 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 when 1 mol% of the primary hydroxyl group-containing modifying group represented by the following general formula (I) is introduced, the melting point generally decreases by about 6 to 9°C.
• the melting point When the melting point is controlled in this way, the melting point can be reduced while relatively maintaining the gas barrier properties and thermal stability, and the decrease in interlayer adhesion with the layer (Y) and inorganic vapor deposition layer (I) described later is also suppressed, so that a multilayer film with particularly excellent quality and performance can be provided.
• the reasons for this are 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 vapor deposition layer (I) described later.
• the content of the primary hydroxyl-containing modifying group in EVOH (a'1) may be adjusted appropriately in consideration of the balance between the melting point and various physical properties, but in many cases, a content of 2 mol% or more and less than 20 mol% will provide a good balance of physical properties.
• the lower limit of the content of the primary hydroxyl-containing modifying group in EVOH (a'1) is more preferably 3 mol%.
• the upper limit of the content of the primary hydroxyl-containing modifying group in EVOH (a'1) is more preferably 10 mol%, and even more preferably 8 mol%.
• the primary hydroxyl-containing modifying group can be introduced by copolymerization or polymer reaction.
• the "content of the primary hydroxyl-containing modifying group in EVOH (a'1)" may be the content (mol%) of the primary hydroxyl-containing monomer unit relative to the total monomer units constituting EVOH (a'1).
• 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 (-O-C(CH 3 )H)-).
• R 1 is an alkyleneoxy group, the oxygen atom of the alkyleneoxy group is usually bonded to a carbon atom of the main chain.
• EVOH (a1) 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-
• EVOH (a1) may be post-modified by methods such as urethanization, acetalization, cyanoethylation, and oxyalkylenation.
• the MFR (190°C, under a load of 2.16 kg) of EVOH (a1) measured in accordance with JIS K7210 (2014) is preferably 0.2 to 20 g/10 min.
• the MFR of EVOH (a1) 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 (a1) 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 content of polyvalent metal ion (a2) contained in the resin composition (A) is 350 ppm or more and 2000 ppm or less. If the content of polyvalent metal ion (a2) is less than 350 ppm, the stress that layer (X) receives from the wall surface of the extrusion flow path and the stress acting between layer (X) and layer (Y) during molding of the multilayer structure increase, and the appearance of the multilayer film deteriorates.
• the content of polyvalent metal ion (a2) is more preferably 380 ppm or more, more preferably 450 ppm or more, particularly preferably 550 ppm or more, and may be 650 ppm or more.
• the content of polyvalent metal ion (a2) exceeds 2000 ppm, the viscosity is significantly reduced when melt-kneaded for a long time, and the stable moldability may deteriorate, or the interlayer adhesion between layer (X) and layer (Y) may be insufficient.
• the content of polyvalent metal ion (a2) is more preferably 1500 ppm or less, and even more preferably 1250 ppm or less.
• the polyvalent metal ion (a2) is at least one selected from the group consisting of magnesium ions, calcium ions, zinc ions, cobalt ions, and manganese ions.
• the polyvalent metal ion (a2) is more preferred in terms of the reduced occurrence of coloration in the resulting multilayer structure, and calcium ions and magnesium ions are even more preferred in terms of the appearance of the resulting multilayer structure, with calcium ions being particularly preferred.
• polyvalent metal compounds that provide the polyvalent metal ions (a2) include aliphatic carboxylates, aromatic carboxylates, carbonates, hydrochlorides, nitrates, sulfates, phosphates, hydroxides, metal complexes, etc.
• aliphatic carboxylates and hydroxides are more preferred because they are easy to obtain and handle, and aliphatic carboxylates are even more preferred because they tend to maintain the viscosity stability of the resin composition (A).
• aliphatic carboxylates acetates, caprylates, and stearates are preferred.
• the resin composition (A) preferably contains 40 to 500 ppm of alkali metal ion (a3).
• the resin composition (A) contains the alkali metal ion (a3) in the above range, the interlayer adhesion with the layer (Y) described later tends to be significantly improved.
• the alkali metal ion (a3) is 40 ppm or more, the recyclability tends to be improved.
• the content of the alkali metal ion (b) is 500 ppm or less, the recyclability and the hue of the recovered composition tend to be good.
• the lower limit of the content of the alkali metal ion (a3) is more preferably 80 ppm, and more preferably 120 ppm.
• the upper limit of the content of the alkali metal ion (a3) is more preferably 400 ppm, and more preferably 300 ppm.
• the melt moldability and coloring resistance of the obtained resin composition (A) can be further improved.
• alkali metal ion (a3) examples include ions of lithium, sodium, potassium, rubidium, cesium, etc., but from the viewpoint of industrial availability, sodium or potassium ions are preferred. These ions may be used alone or in combination of two or more.
• alkali metal compounds that provide the alkali metal ion (a3) include aliphatic carboxylates, aromatic carboxylates, carbonates, hydrochlorides, nitrates, sulfates, phosphates, hydroxides, metal complexes, etc. of alkali metals.
• 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 100 to 4000 ppm of a higher aliphatic carboxylic acid (a4) having 8 to 30 carbon atoms.
• the higher aliphatic carboxylic acid (a4) may be contained in part or in whole in the form of a salt, or may be contained as a salt of a polyvalent metal ion (a2) or an alkali metal ion (a3).
• the higher aliphatic carboxylic acid (a4) is preferably caprylic acid or stearic acid.
• the 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 (a4) 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 (a4).
• the content of the higher aliphatic carboxylic acid (a4) 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 (a4) 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 (a1), polyvalent metal ions (a2), alkali metal ions (a3) and higher aliphatic carboxylic acids (a4) 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 (a2), carboxylic acids (monocarboxylic acids, polyvalent carboxylic acids) other than higher aliphatic carboxylic acids (a4), thermoplastic resins other than EVOH (a1), 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, desiccants, bulking agents, pigments, dyes, processing aids, flame retardants, antifogging agents, etc.
• the melt viscosity of the pulverized resin composition (A) and 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 (a4).
• 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 pKa of the carboxylic acid is preferably 3.5 to 5.5.
• the pH buffering ability of the resulting resin composition (A) is increased, further improving the melt moldability and further improving the coloring caused by acidic or basic substances.
• 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. Among them, sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate are preferred as the phosphate compound.
• 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 presumed that these effects are due to the occurrence of a chelate interaction between the EVOH (a1) 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.
• tertiary esters examples include 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 (a1).
• thermoplastic resins other than EVOH (a1) include various polyolefins (polyethylene, polypropylene, poly(1-butene), poly(4-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 derivatives thereof, 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,
• 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 (a1) 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, from the viewpoint of more prominently exhibiting the effects of the present invention, and the resin constituting the resin composition (A) may be substantially only EVOH (a1), or the resin constituting the resin composition (A) may consist only of EVOH (a1).
• the proportion of EVOH (a1) in the resin composition (A) is usually more than 50% by mass.
• the proportion of EVOH (a1) 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, particularly preferably 95% by mass or more, and may be 98% by mass or more or 99% by mass or more, from the viewpoint of more prominently exhibiting the effects of the present invention.
• the resin composition (A) may consist essentially of EVOH (a1) and polyvalent metal ions (a2).
• the resin composition (A) preferably has a weight loss W of 0.01 to 0.3% when held at 200°C for 30 minutes in a nitrogen atmosphere. This reflects the low molecular weight components present in the resin composition (A) and the decomposition characteristics of EVOH (a1) due to heat, and since layer (X) is made of resin composition (A) that satisfies the specific TG conditions, a multilayer film with excellent appearance characteristics can be stably produced over a long period of time.
• the weight loss W when held at 200°C for 30 minutes in a nitrogen atmosphere is preferably 0.02 to 0.15%, more preferably 0.03 to 0.10%, and even more preferably 0.04 to 0.08%.
• W1 can be controlled by the ethylene unit content and saponification degree of EVOH (a1), the type and content of polyvalent metal ions (a2), alkali metal ions (a3), higher aliphatic carboxylic acids (a4) and other components, and the production conditions (particularly thermal history such as temperature and time) when producing resin composition (A).
• the weight loss W tends to be small by performing melt kneading while removing gas components using a vent device or the like.
• the resin composition (A) satisfies the following formula (a), where the ethylene unit content of the EVOH (a1) is S (mol %) and the amount of the polyvalent metal ion (a2) is T (ppm). -4.17S+560 ⁇ T ⁇ -29.2S+2600 (I)
• T is equal to or greater than the lower limit of the formula (a)
• the appearance properties of the multilayer film tend to be improved, and the viscosity stability during melt molding tends to be excellent.
• T is equal to or less than the upper limit of the formula, the interlayer adhesion between the layer (X) and the layer (Y) tends to be excellent.
• the lower limit of the formula (a) is more preferably -6.26S + 760, and even more preferably -8.33S + 920.
• the upper limit of the formula is more preferably -19.4S + 1920, and even more preferably -16.7S + 1580.
• the formula (a) means that the more suitable content of the polyvalent metal ion (a2) varies depending on the ethylene unit content of the EVOH (a1).
• the method for producing the resin composition (A) is not particularly limited, but it can be produced by melt-kneading EVOH (a1) and polyvalent metal ions (a2), and if necessary, other components such as alkali metal ions (a3) and higher aliphatic carboxylic acids (a4).
• 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 (a1) used and the melting points of each component, and is usually 150 to 250°C.
• some components may be added to EVOH (a1) in advance, and then other additional components required are melt-kneaded as described above.
• An example of a method for adding some components to EVOH (a1) in advance is a method in which EVOH (a1) is immersed as pellets or powder in a solution in which the added components are dissolved.
• an aqueous solution is preferable as the solution.
• the layer (X) is a layer formed by melt molding pellets consisting of only the resin composition (A).
• the multilayer film of the present invention has a layer (Y) containing an adhesive resin (B) having a melting point of less than 170° C. as a main component.
• a layer (Y) containing an adhesive resin (B) having a melting point of less than 170° C. As a main component.
• the adhesive resin (B) may be an acid-modified polyolefin obtained by using an acid to obtain a polyolefin, and more specifically, an acid-modified polyolefin resin obtained by graft-polymerizing an unsaturated carboxylic acid such as maleic anhydride or a derivative thereof to a polyolefin resin.
• the melting point of the adhesive resin (B) mainly depends on the polyolefin resin before the acid modification.
• the contents described for the unmodified polyolefin resin (C) described later can be applied as is to the polyolefin resin, but the adhesive resin (B) is preferably an acid-modified polyethylene or an acid-modified polypropylene.
• the acid-modified polyolefin resin may be a carboxylic acid-modified polyolefin resin.
• the acid-modified polyethylene may be a carboxylic acid-modified polyethylene
• the acid-modified polypropylene may be a carboxylic acid-modified polypropylene.
• the proportion of the 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 acid-modified polyolefin resin, or may be substantially composed of only the 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), or may be substantially composed of only the adhesive resin (B).
• the multilayer film of the present invention has a layer (Z) containing, as a main component, a polyolefin resin (C) having a melting point of less than 170° C.
• the polyolefin resin (C) is not particularly limited as long as it is a polyolefin having a melting point of less than 170° C., and examples thereof include polyethylene-based resins such as linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, and high-density polyethylene; polypropylene-based resins such as homopolypropylene, random polypropylene, and block polypropylene; 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.
• the lower limit of the content of olefin units relative to all monomer units in polyolefin resin (C) is preferably 60 mol%, more preferably 70 mol%, even more preferably 80 mol%, even more preferably 90 mol%, and may be 95 mol%, 98 mol%, 99 mol% or 99.9 mol%.
• the upper limit of the content of olefin units relative to all monomer units in polyolefin resin (C) may be 100 mol%.
• Polyolefin resin (C) may be modified, such as by acid modification, or may be unmodified, but is preferably unmodified.
• polyolefin resin (C) preferably contains a polyethylene-based resin or a polypropylene-based resin as a main component, more preferably polyethylene or polypropylene, and even more preferably polyethylene.
• Polyethylene-based resins and polypropylene-based resins are widely used in packaging materials regardless of whether they have gas barrier properties, and therefore recycling infrastructures for them are widely established in various countries.
• polyethylene 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 160°C, more preferably less than 150°C, and may be less than 140°C or 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 content of the polyethylene resin or the polypropylene 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 the polyethylene resin or the polypropylene resin, or the polyolefin resin (C) may be substantially composed of only the polyethylene resin or the polypropylene 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 layer (Z) may be substantially composed of only the polyolefin resin (C), or the layer (Z) may be substantially composed of only the 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 of the present invention has a structure in which the layer (X) is the outermost layer, and at least the layer (X), the layer (Y) and the layer (Z) are laminated adjacent to each other in this order.
• the multilayer film may have a plurality of layers of each of the layers (X), (Y) and (Z). When there are a plurality of layers (X), it is sufficient that at least one layer (X) located at the outermost layer is present. That is, when there are a plurality of layers (X), it is sufficient that there is a layer (X) that is not located at the outermost layer.
• the multilayer film of the present invention may have layers other than the layer (X), the layer (Y) and the layer (Z). However, as one embodiment of the present invention, the multilayer film of the present invention may not have layers other than the layer (X), the layer (Y) and the layer (Z).
• the layer structure of the multilayer film of the present invention may be X/Y/Z, X/Y/Z/Y/X, X/Y/Z/Y/X/Y/Z, X/Y/Z/Y/X/Y/Z, X/Y/Z/Y/X/Y/Z/Y/X, etc., where X represents layer (X), Y represents layer (Y), and Z represents layer (Z), with "/" indicating that the layers are directly laminated.
• the average thickness of the 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 the layer (X) to the average thickness of the multilayer film is less than 25%.
• the average thickness of the 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 the layer (X) to the average thickness of the multilayer film is more preferably less than 20%, and even more preferably less than 15%.
• the ratio of the average thickness of the layer (X) to the total average thickness of the multilayer film may be 1% or more.
• the average thickness of the layer (X) is the sum of the average thicknesses of the layers (X).
• the average thickness of the multilayer film is equal to the sum of the average thicknesses of each layer of the multilayer film.
• the average thickness of layer (Y) in the multilayer film is preferably 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 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 average thickness of the multilayer film is more preferably less than 20%, and even more preferably less than 15%.
• the ratio of the average thickness of layer (Y) to the average thickness of the multilayer film may be 1% or more. When multiple layers (Y) are present, the average thickness of layer (Y) is the sum of the average thicknesses of the layers (Y).
• the average thickness of the layer (Z) in 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 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 average thickness of the multilayer film is more preferably more than 60%, and even more preferably more than 70%.
• the ratio of the average thickness of the layer (Z) to the average thickness of the multilayer film may be 98% or less.
• the average thickness of the layer (Z) is the sum of the average thicknesses of the layers (Y).
• 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 10 ⁇ m or more and less than 40 ⁇ m.
• the multilayer film may be an unstretched multilayer film, or may be a stretched multilayer film stretched uniaxially or biaxially (at least uniaxially).
• An unstretched multilayer film means a multilayer film that is not stretched, but some orientation during film formation (for example, orientation as if stretched 1.01 times) is considered to be unstretched.
• a uniaxially stretched multilayer film that is stretched only in a uniaxial direction is considered to be uniaxially stretched, ignoring some orientation in the other axial direction during film formation (for example, orientation as if stretched 1.01 times).
• an unstretched multilayer film it has excellent impact resistance and can be suitably used as a heat-sealed film.
• the multilayer film is preferably a uniaxially stretched multilayer film, and from the viewpoint of obtaining a film with little anisotropy in mechanical properties and a strong film, the multilayer film is preferably a biaxially stretched multilayer film. From the viewpoint of uniformity of thickness and mechanical strength of the obtained multilayer film, it is preferable that the multilayer film is stretched at least 3 times and less than 12 times in one axial direction.
• the multilayer film is stretched 3 times and less than 12 times in one axial direction, and more preferably that the multilayer film is stretched 4 times and less than 10 times.
• the stretching axis is preferably the flow direction (longitudinal direction, MD direction) or a direction perpendicular to the flow direction, i.e., the width direction (TD direction), and more preferably the longitudinal direction (MD direction).
• MD direction flow direction
• TD direction width direction
• MD direction longitudinal direction
• MD direction longitudinal direction
• MD direction longitudinal direction
• MD direction longitudinal direction
• MD direction longitudinal direction
• the multilayer film is stretched 3 times and less than 12 times in each of the two axial directions, and more preferably that the multilayer film is stretched 4 times and less than 10 times.
• the lower limit of the ratio of the total average thickness of layers mainly composed of polyethylene resin or polypropylene resin in the multilayer film of the present invention is preferably 75%, more preferably 80%, even more preferably 85%, and even more preferably 88%.
• the upper limit of the ratio of the total average thickness of layers mainly composed of polyethylene resin or polypropylene resin in the multilayer film is preferably 99.5%, more preferably 99%, and may be 98%.
• total average thickness of layers mainly composed of polyethylene resin or polypropylene resin refers to the average thickness of the total of layers mainly composed of polyethylene resin and layers mainly composed of polypropylene resin.
• layers mainly composed of polyethylene-based resin or polypropylene-based resin include layer (Y) in which adhesive resin (B) is, for example, acid-modified polyethylene or acid-modified polypropylene, and layer (Z) in which polyolefin resin (C) is polyethylene or polypropylene.
• Adhesive resin (B) and polyolefin resin (C) may be the same type of resin or different types of resin.
• the lower limit of the ratio of the total average thickness of the layers mainly composed of polyethylene resin in the multilayer film of the present invention is preferably 75%, more preferably 80%, even more preferably 85%, and even more preferably 88%.
• the upper limit of the ratio of the total average thickness of the layers mainly composed of polyethylene resin in the multilayer film is preferably 99.5%, more preferably 99%, and may be 98%.
• the lower limit of the ratio of the total average thickness of the layers mainly composed of polypropylene resin in the multilayer film of the present invention is preferably 75%, more preferably 80%, even more preferably 85%, and even more preferably 88%.
• the upper limit of the ratio of the total average thickness of the layers mainly composed of polypropylene resin in the multilayer film is preferably 99.5%, more preferably 99%, and may be 98%.
• the multilayer film of the present invention preferably does not have a layer containing as its main component a resin having a melting point of 200°C or higher, and a metal layer having an average thickness of 1 ⁇ m or higher.
• layer (X) does not contain as its main component a resin having a melting point of 200°C or higher.
• the metal layer here refers to a layer having continuous and discontinuous surfaces made of metal, such as aluminum foil.
• the width is 500 mm or more.
• the width of the multilayer film refers to the distance from one end to the other end in the short length direction of the film.
• the width of the multilayer film means the width of the multilayer film before stretching
• the width of the multilayer film means the width of the multilayer film before trimming.
• the width of the multilayer film is defined as twice the width at the time of winding.
• the actual width of the multilayer film (for example, the width after trimming) may be 500 mm or more.
• the width of the multilayer film is more preferably 1000 mm or more.
• the width of the multilayer film may be 5000 mm or less.
• the image clarity CMD when the longitudinal direction of the multilayer film is the vertical direction and the image clarity CTD when the width direction is the vertical direction at an optical comb width of 2.0 mm, which are measured in accordance with JIS K7374 (2007, transmission method) centered on the positions of 10%, 50% and 90% when the position of one end of the multilayer film in the width direction is 0% and the position of the other end is 100%, are preferably 60% or more, more preferably 70% or more, and even more preferably 75% or more.
• the standard deviation of the image clarity CMD and the standard deviation of the image clarity CTD measured at the measurement positions are both preferably 10% or less, more preferably 5% or less.
• the ratio (average C MD /average C TD ) of the average value of image clarity C MD (average C MD ) to the average value of image clarity C TD (average C TD ) is preferably 0.80 to 1.15, more preferably 0.85 to 1.05, and even more preferably 0.90 to 1.00.
• Such a multilayer film is particularly useful as a film having excellent appearance properties, etc.
• the image clarity C MD and image clarity C TD can be adjusted by the composition of each layer of the multilayer film as well as the production conditions (for example, the take-up speed during film formation, etc.).
• the method for producing the multilayer film is not particularly limited, but generally, a conventional coextrusion method in which each resin is extruded from a separate die or a common die and laminated can be used.
• a 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 and/or the direction perpendicular to the flow direction, i.e., in the width direction, using a conventionally known stretching method such as roll-type uniaxial stretching, tenter-type uniaxial stretching, tubular-type simultaneous biaxial stretching, tenter-type sequential biaxial stretching, and tenter-type simultaneous biaxial stretching.
• the tenter-type sequential biaxial stretching may use a tenter type for both axes, or may be a combination of roll-type stretching and tenter-type stretching.
• the effect of the present invention is particularly remarkable in the case of a multilayer film produced by tenter-type sequential biaxial stretching, which is a combination of roll-type stretching and tenter-type stretching.
• the temperature during stretching is usually 40 to 170° C., and more preferably 50 to 160° C. If necessary, it is preferable to carry out a so-called heat setting operation by heating the film after stretching 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.
• the method for producing a multilayer film preferably includes a step of melt-kneading EVOH (a1) and polyvalent metal ions (a2) to obtain resin composition (A) pellets, and a step of melt-molding the resin composition (A) pellets to form layer (X).
• the specific method for obtaining resin composition (A) pellets is as described above.
• the vapor-deposited multilayer film of the present invention comprises the multilayer film of the present invention and an inorganic vapor-deposited layer (I) laminated on the surface side of the layer (X) in the multilayer film. That is, the multilayer film of the present invention may be used by laminating the inorganic vapor-deposited layer (I) on the surface of the layer (X).
• the inorganic vapor-deposited layer (I) is preferably laminated on the surface side of the layer (X) of the multilayer film directly or via another layer such as an adhesive layer, and is preferably laminated directly on the surface side of the layer (X).
• the inorganic vapor-deposited 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 vapor-deposited layer (I), and the interlayer adhesion between the layer (X) and the inorganic vapor-deposited layer (I) in the obtained vapor-deposited multilayer film is good.
• the layer (X) since the layer (X) has gas barrier properties, even when defects occur in the inorganic vapor-deposited layer (I) due to bending or the like, the deterioration of the gas barrier properties can be suppressed.
• the inorganic vapor deposition layer (I) generally has an average thickness of less than 500 nm.
• the average thickness is less than 500 nm, the viscosity stability is excellent when the pulverized product of the vapor deposition multilayer film or multilayer structure containing the inorganic vapor deposition layer (I) is melt-molded, 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 preferred when light blocking properties are to be imparted, but an inorganic oxide vapor deposition layer is preferred from the viewpoints of visibility of the contents as a packaging material, microwave suitability, and suppression of the generation of gels and lumps when pulverized materials are melt-molded.
• an inorganic oxide vapor deposition layer is preferred from the viewpoint of suppressing discoloration during recycling of the multilayer structure of the present invention.
• 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.
• 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 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 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 is more preferably 90% or more.
• the light transmittance can be increased, for example, by suppressing the thickness unevenness of the multilayer film used in the production of the multilayer film.
• a means for further suppressing the thickness unevenness of the multilayer film for example, a means for stretching at least in one axial direction can be mentioned.
• the light transmittance at a wavelength of 600 nm of the deposition multilayer film is preferably 80% or more, and 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. Specifically, examples 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 more preferably to use a vacuum vapor deposition method.
• the upper limit of the surface temperature of the layer (X) during the formation of the inorganic vapor 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 the formation of the inorganic vapor 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 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, and nitrogen is particularly preferred because it can reduce costs.
• the flex resistance may be improved by providing a known protective layer or the like on the inorganic vapor deposition layer (I).
• the multilayer film or vapor-deposited multilayer film of the present invention preferably has an oxygen transmission rate (under conditions of 20°C and 65% RH) measured in accordance with the method described in JIS K7126-2 (constant pressure method; 2006) of less than 60 cc/( m2 day atm), more preferably less than 10 cc/( m2 day atm), even more preferably less than 3 cc/( m2 day atm), and particularly preferably less than 0.5 cc/( m2 day atm).
• a multilayer film or vapor-deposited multilayer film having an oxygen transmission rate in the above range has excellent gas barrier properties.
• the multilayer film or vapor-deposited multilayer film of the present invention can itself be used as a packaging material having gas barrier properties, but by laminating at least one resin layer (R) containing a thermoplastic resin (D) as a main component to form a multilayer structure, it is possible to impart various functions as a packaging material, such as designability and heat sealability. That is, the multilayer structure of the present invention is formed by laminating the multilayer film or vapor-deposited multilayer film of the present invention and at least one resin layer (R) containing a thermoplastic resin (D) as a main component.
• 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, polyethylene naphthalate, polystyrene, polyvinyl chloride, polyvinylidene chloride, acrylic resin, polycarbonate, chlorinated polyethylene, chlorinated polypropylene, etc.
• the thermoplastic resin (D) is preferably the same as the polyolefin resin (C) described above, i.e., a polyolefin resin having a melting point of less than 170°C, more preferably a polyethylene-based resin or a polypropylene-based resin as the main component, even more preferably polyethylene or polypropylene, and particularly preferably polyethylene.
• the polyolefin resin (C) and the thermoplastic resin (D) preferably contain a polyethylene-based resin or a polypropylene-based resin as the main component, more preferably polyethylene or polypropylene, and even more preferably polyethylene.
• 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. Either 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. From the viewpoint of the uniformity of the thickness of the obtained layer and the mechanical strength, 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 easily break 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 this 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-based resin or a polypropylene-based resin as a main component, and the ratio of the total average thickness of the layers containing a polyethylene-based resin or a polypropylene-based resin as a main component to the average thickness of the multilayer structure is preferably 80% or more, more preferably 85% or more. On the other hand, from the viewpoint of improving gas barrier properties, the ratio is preferably 99.7% or less, more preferably 99.5% or less, and may be 99.3% or less.
• the lower limit of the ratio of the total average thickness of the layers mainly composed of a polyethylene resin in the multilayer structure of the present invention is preferably 80%, more preferably 85%.
• the upper limit of the ratio of the total average thickness of the layers mainly composed of a polyethylene resin in the multilayer structure is preferably 99.7%, more preferably 99.5%, and may be 99.3%.
• the lower limit of the ratio of the total average thickness of the layers mainly composed of a polypropylene resin in the multilayer structure of the present invention is preferably 80%, more preferably 85%.
• the upper limit of the ratio of the total average thickness of the layers mainly composed of a polypropylene resin in the multilayer structure is preferably 99.7%, more preferably 99.5%, and may be 99.3%.
• the method of laminating the resin layer (R) on the multilayer film or vapor-deposited 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 multilayer film or vapor-deposited multilayer film.
• each layer constituting the multilayer structure of the present invention may be laminated via an adhesive layer as necessary. However, it is preferable that there is no adhesive layer between layer (X) and layer (Y) of the multilayer film or vapor-deposited 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 vapor deposition layer (I) as I
• 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 layers (X), (Y) and (Z) may be uniaxially stretched, biaxially stretched or unstretched.
• the layers (Z) and (R) are preferably polyethylene-based resins or polypropylene-based resins, and the layer (Y) is preferably maleic anhydride-modified polyethylene-based resins or maleic anhydride-modified polypropylene-based resins.
• the outermost layers of the multilayer structure of the present invention have a layer containing a polyethylene-based resin or a polypropylene-based resin as a main component so that the pulverized product obtained by pulverizing the packaging material can be recovered as a composition mainly containing a polyethylene-based resin or a polypropylene-based resin.
• the resin layer (R) is a layer mainly containing a polyethylene resin or a polypropylene resin
• the layer (Z) and the resin layer (R) are layers mainly containing a polyethylene resin or a polypropylene resin.
• the layers arranged on the outermost layer it is preferable that one is a non-stretched layer, and in some cases, the other is a layer that is stretched at least uniaxially, from the viewpoint of obtaining a multilayer structure that has both heat sealability and mechanical properties.
• the multilayer structure of the present invention may have layers other than those described above, provided that 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 printing layer.
• the printing layer may be included at any position in the multilayer structure of the present invention.
• An example of the printing layer is a film obtained by applying a solution containing a pigment or dye, and optionally a binder resin, and drying the solution.
• Examples of the application method of the printing layer 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 ink layer is not particularly limited, but is preferably 0.5 to 10 ⁇ m, and more preferably 1 to 4 ⁇ m.
• a method for recovering a multilayer structure of the present invention which includes a step of crushing the multilayer structure of the present invention and then melt-molding it, 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 or a polypropylene-based resin is more preferred.
• the polyolefin resin the same type of polyolefin resin (C) as described above for use in the multilayer film of the present invention is used.
• 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 is preferably 0.01/99.99 to 20/80.
• the mass ratio is 0.01/99.99 or more, there is less need to use polyolefin resin other than the recovered material of the multilayer structure, and the ratio of the recovered material used increases.
• the mass ratio is 20/80 or less, the melt moldability and mechanical properties of the recovered composition are improved.
• the 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 gas barrier properties and recyclability, and therefore can 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.
• the multilayer film and vapor-deposited multilayer film of the present invention can also be suitably used as packaging materials.
• Et ethylene
• MFR 190°C, 2.16 kg load
• EVOH (a1-1B): EVOH (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, volatile content 0.8%, sodium acetate 100 ppm in terms of sodium ions, phosphate ions 30 ppm in terms of phosphate radicals, boric acid 150 ppm in terms of boron element, no polyvalent metal ions.
• EVOH (a1-1C): EVOH (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, volatile content 0.8%, sodium acetate 250 ppm in terms of sodium ions, phosphate ions 30 ppm in terms of phosphate radicals, boric acid 150 ppm in terms of boron element, no polyvalent metal ions.
• EVOH (a1-1D): EVOH (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, volatile content 0.8%, sodium acetate 550 ppm in terms of sodium ions, phosphate ions 30 ppm in terms of phosphate radicals, boric acid 150 ppm in terms of boron element, no polyvalent metal ions.
• EVOH (a1-2): EVOH (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, volatile content 0.8%, sodium acetate 180 ppm in terms of sodium ions, phosphate ions 30 ppm in terms of phosphate radicals, boric acid 150 ppm in terms of boron element, no polyvalent metal ions.
• EVOH (a1-3): EVOH (ethylene unit content 44 mol%, saponification degree 99.99 mol%, MFR (190°C, 2.16 kg load) 1.9 g/10 min, melting point 165°C, volatile content 0.8%, sodium acetate 180 ppm in terms of sodium ions, phosphate ions 30 ppm in terms of phosphate radicals, boric acid 150 ppm in terms of boron element, no polyvalent metal ions.
• the epoxypropane modification degree is the content of monomer units modified with epoxypropane relative to the total monomer units.
• (Production method of EVOH (a-5)) 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.
• EVOH having an ethylene unit content of 44 mol% and a saponification degree of 99.99 mol% or more was charged into a Toshiba Machine Co., Ltd.
• the extruder was operated under the following conditions: barrel C1 was water-cooled, barrels C2 to C3 were at 200°C, barrels C4 to C15 were at 240°C, and the screw rotation speed was 250 rpm.
• Epoxypropane (1.5 kg/hr) and the catalyst solution were added from the pressure inlet 1 of C8.
• an aqueous sodium acetate solution was added from the pressure inlet 2 of C13.
• the discharged strands were cooled and solidified in a cooling tank, cut, and then dried to obtain EVOH (a-5).
• the amount of catalyst solution added was adjusted so that the melting point of the resulting EVOH (a-5) would be 119° C.
• the amount of sodium acetate solution added was appropriately adjusted so that the content of sodium ions in EVOH (a-5) would be as described above.
• Example 1 Preparation of resin composition (A) pellets 100 parts by mass of EVOH (a1-1) pellets and calcium stearate were dry blended so that the calcium ion content in the resulting resin composition was 1000 ppm, and then melt-kneaded to obtain resin composition (A) pellets for layer (X).
• one mixing zone was arranged in which a feed type kneading disk, a neutral type kneading disk, and a return type kneading disk were successively arranged, and one vacuum vent was arranged downstream of the mixing zone. During melt-kneading, the pressure was reduced by the vacuum vent.
• the resin temperature was set to 230°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, density 0.91 g/cm 3 , b-1) was used as adhesive resin (B) as resin composition pellets for layer (Y).
• Admer trademark
• MFR 190°C, 2.16 kg load
• a substance consisting essentially of only one component is also referred to as a composition.
• Resin composition containing polyolefin resin (C) for layer (Z) Low-density polyethylene "INNATE (trademark) TF80" manufactured by Dow Corporation (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).
• MFR 190°C, 2.16 kg load
• the ratio of the total average thickness of the layers mainly composed of polyethylene resin in the multilayer film was 90%.
• Extrusion temperature of resin composition (A): feeding section/compression section/metering section/adapter 175/220/220/220° C.
• Extrusion temperature of adhesive resin (B)-containing resin composition: feeding section/compression section/metering section/adapter 175/220/220/220° C.
• an image clarity tester (“IC-T” manufactured by Suga Test Instruments Co., Ltd.) was used to measure image clarity at the positions of 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, and 90% of the width of the multilayer film, with the position of one end of the multilayer film being 0% and the position of the other end being 100%, and the longitudinal direction (MD direction) of the multilayer film being the vertical direction. The occurrence of streaks was evaluated based on the measured image clarity. In addition, when the evaluation was E, it was determined that the appearance characteristics were poor. The results are shown in Table 3.
• Criteria A Slight streaks were observed in an area of less than 50% of the total width of the film, and the area in which slight to severe streaks were observed was less than 10%.
• B Slight streaks were observed in an area of 50% or more of the total width of the film, and the area in which slight to severe streaks were observed was less than 10%.
• C Not corresponding to B. Slight or mild streaks were observed in an area of 50% or more of the total width of the film, and moderate to severe streaks were observed in less than 10% of the area.
• D Not corresponding to B or C, slight to moderate streaks were observed in an area of 50% or more of the total width of the film, and the area where severe streaks were observed was less than 10%.
• E Not corresponding to B to D, slight to severe streaks were observed in an area of 50% or more of the total film width, or severe streaks were observed in an area of 10% or more of the total film width.
• Image clarity measurement The image clarity of the multilayer film obtained in (5) was measured at an optical comb width of 2.0 mm according to JIS K7374 (2007, transmission method). Specifically, the image clarity was measured at 10%, 50%, and 90% positions, with the position of one end of the multilayer film in the width direction being 0% and the position of the other end being 100%, using an image clarity measuring device ("IC-T" manufactured by Suga Test Instruments Co., Ltd.) to measure the image clarity C MD when the longitudinal direction (MD direction) of the multilayer film is the vertical direction, and the image clarity C TD when the width direction (TD direction) of the multilayer film is the vertical direction to the light source, and the average values of the measured values at each of the three points (average image clarity C MD and average clarity C TD ) were calculated.
• IC-T image clarity measuring device
• the oxygen transmission rate of the multilayer film obtained in (5) was measured in accordance with the method described in JIS K 7126-2 (isobaric method; 2006) with the layer (Z) as the oxygen supply side. Specifically, the oxygen transmission rate (unit: cc/(m2 ⁇ day ⁇ atm)) was measured using an oxygen transmission amount measuring device ("MOCON OX-TRAN2/21" manufactured by Modern Control) under the conditions of temperature 20 °C, humidity 65% RH on the oxygen supply side, humidity 65% RH on the carrier gas side, oxygen pressure 1 atm, and carrier gas pressure 1 atm, and was judged according to the following criteria. Nitrogen gas containing 2% by volume of hydrogen gas was used as the carrier gas.
• control a monolayer film having an average thickness of 100 ⁇ m was obtained similarly using only the low-density polyethylene (hereinafter, sometimes simply referred to as "control").
• the die used was a T-die with a width of 300 mm.
• the average thickness of the single-layer film was adjusted by appropriately changing the screw rotation speed and the take-up roll speed. The temperature conditions at this time are shown below.
• the coloration and defects of the obtained monolayer film (recycled material) were visually compared with the control and judged according to the following criteria.
• the defect rating was E, it was judged that the recyclability was insufficient.
• the results are shown in Table 3.
• Defects (recyclability) evaluation Criterion A: The amount of debris was almost the same as the control. B: The amount of small particles was slightly greater than in the control. C: Compared to the control, there was a greater amount of small particles. D: Compared to the control, there was a greater amount of large bumps. E: There was a significantly greater amount of large bumps compared to the control.
• Example 2 Comparative Examples 2 to 4 Resin composition pellets, multilayer films, and multilayer structures were prepared and evaluated in the same manner as in Example 1, except that the type of EVOH (a1), the type and content of polyvalent metal ions (a2), and the content of alkali metal ions (a3) were as shown in Table 1 or Table 2. The results are shown in Table 3 or Table 4.
• Example 14 magnesium stearate was used instead of calcium stearate, and in Example 15, zinc stearate was used instead of calcium stearate.
• Comparative Example 2 the same operation as in Example 1 was performed, except that calcium stearate was not added during melt-kneading in the preparation of resin composition (A) pellets in Example 1 (1).
• Example 20 A resin composition pellet, a multilayer film, and a multilayer structure were produced and evaluated in the same manner as in Example 1, except that a dry blend obtained by dry blending 100 parts by mass of EVOH (a1-1) pellets and 1.5 parts by mass of calcium stearate (calcium ion content in the dry blend: 1000 ppm) was used as the resin composition for layer (X). The results are shown in Table 3.
• Example 21 In preparing the resin composition (A) pellets for the layer (X), except that an open vent was used instead of a vacuum vent, a resin composition pellet and a multilayer film were prepared in the same manner as in Example 1, and various measurements and evaluations were carried out. The results are shown in Table 4.
• Example 22 In preparing the resin composition (A) pellets for the layer (X), except that a vacuum vent was not used, a resin composition pellet and a multilayer film were prepared in the same manner as in Example 1, and various measurements and evaluations were carried out. The results are shown in Table 4.
• Example 23 An alumina (AlOx) vapor-deposited layer (inorganic vapor-deposited layer (I)) having an average thickness of 30 nm was laminated by a known vacuum deposition method on the surface of layer (X) of the multilayer film obtained in (5) above to prepare a vapor-deposited multilayer film, and resin composition pellets, a multilayer film, a vapor-deposited multilayer film, and a multilayer structure were prepared and evaluated in the same manner as in Example 1, except that the vapor-deposited multilayer film was used instead of the multilayer film to prepare the multilayer structure. The results are shown in Table 4. The oxygen transmission rate was measured for the vapor-deposited multilayer film.
• Example 24 Except for changing the alumina vapor-deposited layer to a silica (SiOx) vapor-deposited layer, a resin composition pellet, a multilayer film, a vapor-deposited multilayer film, and a multilayer structure were produced and evaluated in the same manner as in Example 23. The results are shown in Table 4.
• Example 25 Except for changing the alumina vapor-deposited layer to an aluminum (Al) vapor-deposited layer having an average thickness of 50 nm, resin composition pellets, a multilayer film, a vapor-deposited multilayer film, and a multilayer structure were produced and evaluated in the same manner as in Example 23. The results are shown in Table 4.
• Example 26 Resin composition pellets, multilayer films and multilayer structures were prepared in the same manner as in Example 1, except that the average thickness of each layer of the multilayer film was changed as shown in Table 2, and various measurements and evaluations were carried out. The results are shown in Table 4.
• Resin composition pellets, multilayer films and multilayer structures were prepared and evaluated in the same manner as in Example 1 except that the resin composition pellets, multilayer films and multilayer structures were prepared and evaluated in the same manner as in Example 1 except that the resin composition pellets, multilayer films and multilayer structures were used instead of the multilayer film of Example 1.
• the results are shown in Table 4.
• Example 29 As the adhesive resin (B), Mitsui Chemicals Co., Ltd.'s maleic anhydride modified polypropylene "Admer (trademark) QF551" (MFR (230 ° C., 2.16 kg load) 5.7 g / 10 min, density 0.89 g / cm 3 , b-2), polyolefin resin (C), Japan Polypropylene Corporation's polypropylene “Novatec (trademark) PP EA7AD” (MFR (230 ° C., 2.16 kg load) 1.4 g / 10 min, melting point 161 ° C., density 0.90 g / cm 3 ), resin layer (R) was used as a polypropylene film with an average thickness of 50 ⁇ m, except that the conditions during multilayer film production were changed as follows, resin composition pellets, multilayer films and multilayer structures were produced and evaluated in the same manner as in Example 1.
• Extrusion temperature of resin composition (A): feeding section/compression section/metering section/adapter 175/220/220/230° C.
• Extrusion temperature of adhesive resin (B)-containing resin composition: feeding section/compression section/metering section/adapter 175/230/230/230° C.
• Extrusion temperature of polyolefin resin (C)-containing resin composition: feeding section/compression section/metering section/adapter 175/230/230/230° C.
• Example 30 Resin composition pellets, a multilayer film and a multilayer structure were prepared and evaluated in the same manner as in Example 1, except that a maleic anhydride-modified polyethylene "BYNEL (trademark) 41E687" (MFR (190°C, 2.16 kg load) 1.7 g/10 min, density 0.91 g/cm 3 , b-3) manufactured by Dow was used as the adhesive resin (B).
• BYNEL polyethylene
• MFR 190°C, 2.16 kg load
• Example 31 Resin composition pellets, multilayer films and multilayer structures were prepared and evaluated in the same manner as in Example 1, except that a maleic anhydride-modified polyethylene "Admer (trademark) AT1955T" (MFR (190°C, 2.16 kg load) 2.6 g/10 min, density 0.89 g/cm 3 , b-4) manufactured by Mitsui Chemicals, Inc. was used as the adhesive resin (B). The results are shown in Table 4.
• Example 32 As the adhesive resin (B), Mitsui Chemicals Co., Ltd.'s maleic anhydride modified polyethylene "Admer (trademark) AT1955T” (MFR (190 ° C., 2.16 kg load) 2.6 g / 10 min, density 0.89 g / cm 3 , b-4), polyolefin resin (C), Japan Polypropylene Corporation's polypropylene “Novatec (trademark) PP EA7AD” (MFR (230 ° C., 2.16 kg load) 1.4 g / 10 min, melting point 161 ° C., density 0.90 g / cm 3 ), resin layer (R) was used as a polypropylene film with an average thickness of 50 ⁇ m, except that the conditions during multilayer film production were changed as follows, resin composition pellets, multilayer films and multilayer structures were produced and evaluated in the same manner as in Example 1.
• Extrusion temperature of resin composition (A): feeding section/compression section/metering section/adapter 175/220/220/230° C.
• Extrusion temperature of adhesive resin (B)-containing resin composition: feeding section/compression section/metering section/adapter 175/230/230/230° C.
• Extrusion temperature of polyolefin resin (C)-containing resin composition: feeding section/compression section/metering section/adapter 175/230/230/230° C.
• Example 33 Except for changing the take-up speed during the preparation of the multilayer film to 12 m/min, resin composition pellets, a multilayer film and a multilayer structure were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 4.
• Comparative Example 1 A multilayer film (single layer film) and a multilayer structure were produced and evaluated in the same manner as in Example 1, except that a layer (Z) (single layer film) having an average thickness of 40 ⁇ m was used instead of the multilayer film.
• the layer (Z) having an average thickness of 40 ⁇ m was produced by extruding only a polyolefin resin (C)-containing resin composition (low density polyethylene "INNATE (trademark) TF80" manufactured by DOW) 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.
• C polyolefin resin
• Comparative Example 5 Resin composition pellets, a multilayer film, and a multilayer structure were prepared and evaluated in the same manner as in Example 1, except that calcium stearate was not added, and layer (Y) was formed using pellets obtained by dry blending 20 parts by mass of maleic anhydride modified polyethylene "ADMER (trademark) NF518" manufactured by Mitsui Chemicals Inc. (MFR (190°C, 2.16 kg load) 3.1 g/10 min, density 0.91 g/cm 3 , b-1) as adhesive resin (B) with 80 parts by mass of low density polyethylene "INNATE (trademark) TF80" manufactured by Dow. The results are shown in Table 4.
• Comparative Example 6 Resin composition pellets, a multilayer film and a multilayer structure were prepared and evaluated in the same manner as in Comparative Example 5, except that the amount of calcium stearate added was changed so that the content of polyvalent metal ion (a2) was as shown in Table 2. The results are shown in Table 4.
• Reference Example 1 Resin composition pellets, multilayer films, and multilayer structures were produced and evaluated in the same manner as in Comparative Example 3, except that the die used in producing the multilayer film was changed to a 300 mm wide feed block lamination type T die. The results are shown in Table 4. The only difference from Comparative Example 3 was the width, but in Comparative Example 3, where the multilayer film width was 600 mm, deterioration in appearance was observed, while in Reference Example 1, where the multilayer film width was 300 mm, deterioration in appearance was not observed. From this, it can be seen that the problem of deterioration in appearance in the multilayer film of the present invention is a problem that only occurs when the width of the multilayer film is a certain amount or more (500 mm or more).

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