Gas barrier laminate

Abstract

To provide a gas barrier laminate having good processability and unlikely to cause wrinkles.SOLUTION: A gas barrier laminate includes: a substrate layer composed of a 15-50 μm thick polyethylene film and having a first face and a second face; an inorganic vapor-deposited layer disposed on the second face side of the substrate layer; and a gas-barrier coating film layer. An arithmetic average roughness a is 3-10 μm on the first side of the substrate layer. The inorganic vapor-deposited layer is 10-50 nm thick. The gas barrier coating layer is 50-1000 nm thick. A basecoat layer is further disposed between the substrate layer and the inorganic vapor-deposited layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a gas barrier laminate.

Background Art

[0002] Conventionally, as a gas barrier laminate, a laminate including a biaxially stretched polyethylene terephthalate film excellent in heat resistance and toughness as a base film and a sealant layer is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in recent years, due to the increasing environmental awareness triggered by problems such as marine plastic waste, higher efficiency in the separation, collection, and recycling of plastic materials has been demanded. That is, also in the case of laminates for packaging that have conventionally been made to have high performance by combining various different materials, mono-materialization has come to be demanded.

[0005] In order to achieve monomerization in a laminate, it is necessary to use the same material for the constituent films. For example, a polyethylene film, which is a type of polyolefin film, is widely used as a packaging material, so monomerization with a polyethylene film is expected. However, as a basic physical property of a polyethylene film, it has a low melting point, and the film is likely to stretch and deform even at low temperatures. Therefore, in the process of forming a barrier layer on a polyethylene film by a method such as vapor deposition to impart high gas barrier properties, when tension is applied to the polyethylene film and it is wound up, the roll transportability deteriorates, wrinkles occur in the film, and in post-processing, problems such as being unable to be processed appropriately often occur.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a gas barrier laminate that is useful for achieving monomerization, has good processing suitability, and is less likely to wrinkle.

Means for Solving the Problems

[0007] The present invention provides a gas barrier laminate including a base material layer containing polyethylene and a barrier layer, wherein the arithmetic mean roughness a of the surface of the base material layer containing polyethylene on the side opposite to the barrier layer is 3 μm or more. With such a gas barrier laminate, the film transportability is good when performing roll processing, and wrinkles are less likely to occur.

[0008] When the arithmetic mean roughness of the surface of the base material layer containing polyethylene in contact with the barrier layer is b, a / b may be 3 or more.

[0009] The base material layer containing polyethylene may contain unstretched polyethylene.

[0010] The barrier layer may include a gas barrier coating layer and may also include an inorganic vapor deposition layer.

[0011] The barrier layer may include, in this order from the substrate layer side containing polyethylene, an undercoat layer, an inorganic vapor deposition layer, and a gas barrier coating layer.

Advantages of the Invention

[0012] The present invention can provide a gas barrier laminate with good processing suitability and low wrinkle formation.

Brief Description of the Drawings

[0013]

Figure 1

Modes for Carrying Out the Invention

[0014] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicate descriptions are omitted. Also, the dimensional ratios in the drawings are not limited to the ratios shown.

[0015] <Gas Barrier Laminate> FIG. 1 is a schematic cross-sectional view showing a gas barrier laminate according to an embodiment. The gas barrier laminate 10 shown in FIG. 1 includes a substrate layer 1 and a barrier layer 2. The substrate layer 1 contains polyethylene, and the arithmetic mean roughness a of the surface of the substrate layer on the side opposite to the barrier layer is 3 μm or more.

[0016] [Substrate Layer] The substrate layer 1 is a film serving as a support and contains polyethylene. The content of polyethylene in the substrate layer 1 may be 50% by mass or more, may be 80% by mass or more, or may be 100% by mass based on the total amount of the substrate layer 1. The substrate layer 1 may include a polyethylene film or may be composed of a polyethylene film. Further, as the polyethylene, acid-modified polyethylene obtained by graft-modifying polyethylene with an unsaturated carboxylic acid, an acid anhydride of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or the like may be used.

[0017] The polyethylene contained in the base material layer 1 is preferably high-density polyethylene (HDPE). When the polyethylene contained in the base material layer 1 is HDPE, it is preferable because it has excellent heat resistance, is less likely to stretch compared to other polyethylenes, and is easily suppressed from wrinkling. The density of the polyethylene contained in the base material layer 1 may be, for example, 0.94 g / cm 2 or more, and may be 0.95 g / cm 2 or more.

[0018] The polyethylene contained in the base material layer 1 may be stretched or unstretched, but it is preferably unstretched. When it is a base material layer containing unstretched polyethylene, the rigidity as a packaging material can be ensured, and it is easy to prevent bag dropping and bag breakage.

[0019] The arithmetic mean roughness a of the surface of the base material layer 1 on the side opposite to the barrier layer 2 is 3 μm or more. When the arithmetic mean roughness a is 3 μm or more, when the polyethylene film is tensioned and wound, the roll transportability is excellent, so it is possible to suppress the occurrence of wrinkles in the film. From such a viewpoint, the arithmetic mean roughness a of the surface of the base material layer 1 on the side opposite to the barrier layer 2 is preferably 4 μm or more, and more preferably 5 μm or more. The upper limit of the arithmetic mean roughness a is not particularly limited, and may be, for example, 10 μm or less.

[0020] When the arithmetic mean roughness of the surface of the base material layer 1 in contact with the barrier layer 2 is b, it is preferable that a / b is 3 or more. When a / b is 3 or more, it becomes easy to laminate the barrier layer 2 without impairing the barrier properties. From such a viewpoint, a / b is more preferably 3.5 or more, and even more preferably 4 or more. The upper limit of a / b is not particularly limited, and may be, for example, 100 or less. In the present specification, the arithmetic mean roughness was measured 3 times for the front surface and / or the back surface using an optical interference type surface measuring machine, and the maximum protrusion height (μm) with the largest value in the 3 measurements was taken as the arithmetic mean roughness of the film.

[0021] Incidentally, the structure of the base material layer 1 can be appropriately made into multiple layers in consideration of, for example, the proper processing of the film constituting the base material layer 1, rigidity, stiffness, heat resistance, powder falling during conveyance, etc. The structure of the base material layer 1 may be, for example, a multilayer structure including a plurality of layers (films) each containing polyethylene with different densities. The film constituting the base material layer 1 can be appropriately selected from high-density polyethylene (HDPE), medium-density polyethylene, low-density polyethylene, etc. When measuring the density of the base material as the base material layer 1, the density is preferably 0.94 g / cm 2 or more. Also, when containing a slip agent, an antistatic agent, etc., their contents may be changed for each layer and laminated. The base material layer 1 having a plurality of layers can be laminated by extrusion coating, coextrusion coating, sheet forming, coextrusion blow molding, etc. to form a film.

[0022] The thickness of the base material layer 1 may be, for example, 10 to 100 μm, and may be 15 to 50 μm.

[0023] The base material layer 1 may be subjected to various pretreatment such as corona treatment, plasma treatment, frame treatment, etc. on its laminated surface within a range that does not impair the barrier performance, or a coating layer such as an easy adhesion layer may be provided.

[0024] [Barrier layer] The barrier layer 2 is a layer that can impart gas barrier properties to the gas barrier laminate, and may include, for example, a gas barrier coating layer, an inorganic vapor deposition layer, etc. As shown in FIG. 1, the barrier layer 2 may include a subbing layer 3, an inorganic vapor deposition layer 4, and a gas barrier coating layer 5 in this order from the side of the base material layer 1. The oxygen permeability of the barrier layer 2 is preferably 20 cc / m 2 ·day·atm or less, more preferably 10 cc / m 2 ·day·atm, still more preferably 5 cc / m 2 ·day·atm or less, particularly preferably 2 cc / m 2 ·day·atm or less. By the oxygen permeability being within the above range, the gas barrier properties of the gas barrier laminate can be sufficiently ensured.

[0025] (Underlying layer) The underlying layer 3 (anchor coat layer) can achieve effects such as improving the adhesion performance between the base material layer 1 and the inorganic vapor deposition layer 4, improving the smoothness of the surface of the base material layer 1, and suppressing the occurrence of cracks in the inorganic vapor deposition layer 4 due to the elongation of the base material layer 1. Note that by improving the smoothness, it becomes easier to uniformly form the inorganic vapor deposition layer 4 without defects, and it is easier to exhibit high barrier properties. The underlying layer 3 can be formed using a composition for forming an underlying layer (anchor coat agent).

[0026] Examples of the anchor coat agent include acrylic resin, epoxy resin, acrylic urethane resin, polyester-based polyurethane resin, polyether-based polyurethane resin, etc. From the viewpoints of heat resistance and interlayer adhesion strength, acrylic urethane resin and polyester-based polyurethane resin are preferable as the anchor coat agent.

[0027] The thickness of the underlying layer 3 is not particularly limited, but for example, it is preferably in the range of 0.01 to 5 μm, more preferably in the range of 0.03 to 3 μm, and even more preferably in the range of 0.05 to 2 μm. When the thickness of the underlying layer 3 is equal to or greater than the above lower limit value, a more sufficient interlayer adhesion strength tends to be obtained. On the other hand, when it is equal to or less than the above upper limit value, the desired gas barrier property is likely to be exhibited.

[0028] As a method for coating the underlying layer 3 on the base material layer 1, known coating methods can be used without particular limitation, such as dipping method; methods using spray, coater, printing machine, brush, etc. In addition, examples of the types of coaters and printing machines used in these methods and their coating methods include gravure coaters such as direct gravure method, reverse gravure method, kiss reverse gravure method, offset gravure method, reverse roll coater, micro gravure coater, chamber doctor combined coater, air knife coater, dip coater, bar coater, comma coater, die coater, etc.

[0029] As the coating amount of the undercoat layer 3, after applying and drying the anchor coating agent, the mass per 1 m 2 is preferably 0.01 to 5 g / m 2 and more preferably 0.03 to 3 g / m 2 When the mass per 1 m after applying and drying the anchor coating agent is at least the above lower limit, film formation tends to be sufficient. On the other hand, when it is at most the above upper limit, it tends to dry sufficiently and the solvent hardly remains. 2 There is no particular limitation on the method for drying the undercoat layer 3, and examples thereof include a method by natural drying, a method of drying in an oven set at a predetermined temperature, and a method using a dryer attached to the coater, such as an arch dryer, a floating dryer, a drum dryer, an infrared dryer, etc. Further, as the drying conditions, they can be appropriately selected according to the drying method. For example, in the method of drying in an oven, it is preferable to dry at a temperature of 60 to 100°C for about 1 second to 2 minutes.

[0030] As the undercoat layer 3, instead of the resin described above, a polyvinyl alcohol-based resin can be used. The polyvinyl alcohol-based resin may be any one having a vinyl alcohol unit obtained by saponifying a vinyl ester unit, and examples thereof include polyvinyl alcohol (PVA) and ethylene-vinyl alcohol copolymer (EVOH).

[0031]

[0032] ​Examples of PVA include resins obtained by polymerizing vinyl esters such as vinyl acetate, vinyl formate, vinyl propionate, vinyl valerate, vinyl caprylate, vinyl laurate, vinyl stearate, vinyl pivalate, and vinyl versatate alone and then saponifying them. PVA may be a modified PVA that has been copolymerization-modified or post-modified. The modified PVA can be obtained, for example, by copolymerizing a vinyl ester with an unsaturated monomer copolymerizable with the vinyl ester and then saponifying the resulting copolymer. Examples of unsaturated monomers copolymerizable with vinyl esters include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; hydroxy group-containing α-olefins such as 3-buten-1-ol, 4-penten-1-ol, and 5-hexen-1-ol; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, and undecylenic acid; nitriles such as acrylonitrile and methacrylonitrile; amides such as diacetoneacrylamide, acrylamide, and methacrylamide; olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid; vinyl compounds such as alkyl vinyl ether, dimethylallyl vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinyl ethylene carbonate, 2,2-dialkyl-4-vinyl-1,3-dioxolane, glycerin monoallyl ether, and 3,4-diacetoxy-1-butene; vinylidene chloride, 1,4-diacetoxy-2-butene, and vinylene carbonate.

[0033] The degree of polymerization of PVA is preferably from 300 to 3000. If the degree of polymerization is less than 300, the barrier property tends to decrease, and if it exceeds 3000, the viscosity is too high and the coating suitability tends to decrease. The saponification degree of PVA is preferably 90 mol% or more, more preferably 95 mol% or more, and still more preferably 99 mol% or more. Also, the saponification degree of PVA may be 100 mol% or less or 99.9 mol% or less. The degree of polymerization and saponification degree of PVA can be measured in accordance with the methods described in JIS K 6726 (1994).

[0034] EVOH is generally obtained by saponifying a copolymer of ethylene and a vinyl ester such as vinyl acetate, vinyl formate, vinyl propionate, vinyl valerate, vinyl caprylate, vinyl laurate, vinyl stearate, vinyl pivalate, vinyl versatate, etc.

[0035] The degree of polymerization of EVOH is preferably 300 to 3000. When the degree of polymerization is less than 300, the barrier property is likely to decrease, and when it exceeds 3000, the viscosity is too high and the coating applicability is likely to decrease. The saponification degree of the vinyl ester component of EVOH is preferably 90 mol% or more, more preferably 95 mol% or more, and still more preferably 99 mol% or more. Also, the saponification degree of EVOH may be 100 mol% or less, or 99.9 mol% or less. The saponification degree of EVOH is determined from the peak area of the hydrogen atoms contained in the vinyl ester structure and the peak area of the hydrogen atoms contained in the vinyl alcohol structure by performing nuclear magnetic resonance ( 1 1H-NMR) measurement.

[0036] The ethylene unit content of EVOH is preferably 10 mol% or more, more preferably 15 mol% or more, still more preferably 20 mol% or more, and particularly preferably 25 mol% or more. Also, the ethylene unit content of EVOH is preferably 65 mol% or less, more preferably 55 mol% or less, and still more preferably 50 mol% or less. When the ethylene unit content is 10 mol% or more, the gas barrier property or dimensional stability under high humidity can be maintained well. On the other hand, when the ethylene unit content is 65 mol% or less, the gas barrier property can be enhanced. The ethylene unit content of EVOH can be determined by the NMR method.

[0037] When using a polyvinyl alcohol-based resin as the undercoat layer 3, examples of the formation method of the undercoat layer 3 include coating using a polyvinyl alcohol-based resin solution and multilayer extrusion.

[0038] (Inorganic vapor deposition layer) Examples of the constituent materials of the inorganic vapor deposition layer 4 include inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, and tin oxide. From the viewpoints of transparency and barrier properties, the inorganic oxide may be selected from the group consisting of aluminum oxide, silicon oxide, and magnesium oxide. Further, from the viewpoint of excellent tensile stretchability during processing, it is preferable that the inorganic vapor deposition layer 4 is a layer using silicon oxide. By using the inorganic vapor deposition layer 4, a very thin layer within a range that does not affect the recyclability of the gas barrier laminate can provide high barrier properties.

[0039] It is desirable that the O / Si ratio of the inorganic vapor deposition layer 4 is 1.7 or more. When the O / Si ratio is 1.7 or more, the content ratio of metallic Si is suppressed, and good transparency is easily obtained. Further, the O / Si ratio is preferably 2.0 or less. When the O / Si ratio is 2.0 or less, the crystallinity of SiO becomes high, preventing the inorganic vapor deposition layer from becoming too hard, and good tensile resistance can be obtained. Thereby, it is possible to suppress the occurrence of cracks in the inorganic vapor deposition layer 4 when the gas barrier coating layer 5 is laminated. Also, although the base material layer 1 may shrink due to heat during the boiling treatment even after being formed into a packaging bag, when the O / Si ratio is 2.0 or less, the inorganic vapor deposition layer easily follows the above shrinkage, suppressing a decrease in barrier properties. From the viewpoint of obtaining these effects more sufficiently, the O / Si ratio of the inorganic vapor deposition layer 4 is preferably 1.75 or more and 1.9 or less, and more preferably 1.8 or more and 1.85 or less.

[0040] The O / Si ratio of the inorganic vapor deposition layer 4 can be determined by X-ray photoelectron spectroscopy (XPS). For example, the measuring apparatus can be an X-ray photoelectron spectrometer (manufactured by JEOL Ltd., trade name: JPS-90MXV), the X-ray source can use non-monochromatized MgKα (1253.6 eV), and the measurement can be performed with an X-ray output of 100 W (10 kV - 10 mA). For quantitative analysis to obtain the O / Si ratio, relative sensitivity factors of 2.28 for O1s and 0.9 for Si2p can be used.

[0041] The film thickness of the inorganic vapor deposition layer 4 is preferably 10 nm or more and 50 nm or less. When the film thickness is 10 nm or more, sufficient gas barrier properties can be obtained. Also, when the film thickness is 50 nm or less, it is possible to suppress the generation of cracks due to deformation caused by the internal stress of the thin film and suppress the deterioration of the gas barrier properties. Note that when the film thickness exceeds 50 nm, the cost tends to increase due to an increase in the amount of material used and a lengthening of the film formation time, etc., so it is not preferable from an economic point of view. From the same viewpoint as above, the film thickness of the inorganic vapor deposition layer is more preferably 20 nm or more and 40 nm or less.

[0042] The inorganic vapor deposition layer 4 can be formed, for example, by vacuum film formation. In vacuum film formation, a physical vapor deposition method or a chemical vapor deposition method can be used. Examples of the physical vapor deposition method include, but are not limited to, vacuum evaporation, sputtering, ion plating, etc. Examples of the chemical vapor deposition method include, but are not limited to, thermal CVD, plasma CVD, photo CVD, etc.

[0043] In the above vacuum film formation, a resistance heating type vacuum evaporation method, an EB (Electron Beam) heating type vacuum evaporation method, an induction heating type vacuum evaporation method, sputtering, reactive sputtering, dual magnetron sputtering, plasma chemical vapor deposition (PECVD method), etc. are particularly preferably used. However, considering productivity, at present, the vacuum evaporation method is the most excellent. As the heating means of the vacuum evaporation method, it is preferable to use any one of an electron beam heating method, a resistance heating method, and an induction heating method.

[0044] (Gas barrier coating layer) The gas barrier coating layer 5 protects the inorganic vapor deposition layer 4 and has the effect of preventing cracks in the inorganic oxide layer during bending.

[0045] Also, the gas barrier coating layer 5 is a layer having gas barrier properties. By providing the gas barrier coating layer, the gas barrier properties of the gas barrier laminate can be improved.

[0046] The gas barrier coating layer 5 may be formed using a composition for forming a gas barrier coating layer (hereinafter also referred to as a coating agent) mainly composed of an aqueous solution or a water / alcohol mixed solution containing at least one selected from the group consisting of a hydroxyl group-containing polymer compound, a metal alkoxide, a silane coupling agent, and their hydrolyzates.

[0047] Specific examples of the hydroxyl group-containing polymer compound include water-soluble polymers such as ethylene vinyl alcohol, polyvinyl alcohol, polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, and sodium alginate. Among them, polyvinyl alcohol (PVA) is particularly preferred because of its excellent barrier properties.

[0048] The metal alkoxide is preferably formed from a composition containing at least one selected from the group consisting of a metal alkoxide represented by the following general formula (1), its hydrolyzate, or a polymer. M(OR 1 ) m (R 2 ) n-m ···(1) In the above general formula (1), R 1 and R 2 are each independently a monovalent organic group having 1 to 8 carbon atoms, preferably an alkyl group such as a methyl group or an ethyl group. M represents an n-valent metal atom such as Si, Ti, Al, or Zr. m is an integer from 1 to n. When there are a plurality of R 1 or R 2 , R 1 may be the same or different from each other, and R 2 may also be the same or different from each other.

[0049] Specific examples of the metal alkoxide include tetraethoxysilane [Si(OC2H5)4], triisopropoxyaluminum [Al(O-2'-C3H7)3], and the like. Since the metal alkoxide is relatively stable in an aqueous solvent after hydrolysis, tetraethoxysilane or triisopropoxyaluminum is preferred. Examples of the hydrolysis product of the metal alkoxide include silicic acid (Si(OH)4), which is a hydrolysis product of tetraethoxysilane, and aluminum hydroxide (Al(OH)3), which is a hydrolysis product of tripropoxyaluminum. These can be used alone or in combination of two or more.

[0050] Examples of the silane coupling agent include compounds represented by the following general formula (2). Si(OR 11 ) p (R 12 ) 3-p R 13 ···(2) In the general formula (2) above, R 11 represents an alkyl group such as a methyl group or an ethyl group, R 12 represents a monovalent organic group such as an alkyl group, an aralkyl group, an aryl group, an alkenyl group, an alkyl group substituted with an acryloxy group, or an alkyl group substituted with a methacryloxy group, and R 13 represents a monovalent organic functional group, and p represents an integer of 1 to 3. When there are a plurality of R 11 or R 12 , R 11 's or R 12 's may be the same or different from each other. Examples of the monovalent organic functional group represented by R 13 include a glycidyloxy group, an epoxy group, a mercapto group, a hydroxyl group, an amino group, an alkyl group substituted with a halogen atom, or a monovalent organic functional group containing an isocyanate group.

[0051] Specific examples of the silane coupling agent include silane coupling agents such as vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane.

[0052] Further, the silane coupling agent may be a polymer obtained by polymerizing the compound represented by the general formula (2). As the polymer, a trimer is preferable, and more preferably, 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate. This is a polycondensate of 3-isocyanatealkylalkoxysilane. It is known that in 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate, the isocyanate part loses its chemical reactivity, but the reactivity is ensured due to the polarity of the nurate part. Generally, it is added to adhesives and the like in the same manner as 3-isocyanatealkylalkoxysilane and is known as an adhesion improver. Therefore, by adding 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate to the hydroxyl group-containing polymer compound, the water resistance of the gas barrier coating layer 5 can be improved by hydrogen bonding. 3-Isocyanatealkylalkoxysilane has high reactivity and low liquid stability, whereas 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate, although the nurate part is not water-soluble due to its polarity, is easily dispersed in an aqueous solution and can keep the liquid viscosity stable. Also, the water resistance performance is equivalent to that of 3-isocyanatealkylalkoxysilane and 1,3,5-tris(3-trialkoxysilylalkyl)isocyanurate.

[0053] 1,3,5-Tris(3-trialkoxysilylalkyl)isocyanurate is produced by thermal condensation of 3-isocyanatopropylalkoxysilane. Although the raw material 3-isocyanatopropylalkoxysilane may be included, there are no particular problems. More preferably, it is 1,3,5-tris(3-trialkoxysilylpropyl)isocyanurate, and even more preferably 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate. Since this methoxy group has a high hydrolysis rate and those containing a propyl group can be obtained relatively inexpensively, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate is practically advantageous.

[0054] Also, in the coating agent, within a range that does not impair the gas barrier property, an isocyanate compound or known additives such as a dispersant, stabilizer, viscosity modifier, colorant, etc. may be added.

[0055] The coating agent may contain water-swellable mica. Mica is a type of inorganic layered mineral that forms a single layered particle in which extremely thin unit crystal layers overlap. Mica includes natural mica and synthetic mica. For example, muscovite, phlogopite, biotite, potassium phlogopite, potassium tetrasilicate mica, potassium teniolite, potassium·fluorine tetrasilicate mica sodium, ·fluorine tetrasilicate mica, sodium phlogopite, sodium tetrasilicate mica, sodium hectorite, etc. may be mentioned. One type of mica among these may be used, or two or more different micas may be used in combination.

[0056] As mica, those that swell and exfoliate in water are preferred, and among these, water-swellable mica having particularly good swelling properties in water is preferably used. More specifically, it is a synthetic mica that has the property of coordinating water between extremely thin unit crystal layers and absorbing and swelling. Generally, Si 4+ is coordinated to O 2- to form a tetrahedral structure layer, and Al 3+ , Mg 2+ , Fe 2+ , and Fe 3+ etc. are coordinated to O 2-and OH - A compound in which a layer that coordinates with - to form an octahedral structure and a layer are bonded in a 1:1 or 2:1 ratio and stacked to form a layered structure. For example, sodium fluorotetrasilicon mica is preferable.

[0057] When water-swellable mica is included, it is preferable that the coating agent contains a hydroxyl group-containing polymer compound. When the total mass of the gas barrier coating layer 5 is 100 parts by mass, the content of water-swellable mica may be within an approximate range indicated by, for example, 20 parts by mass to 50 parts by mass. In this case, the gas barrier coating layer 5 can be formed using a coating liquid containing a hydroxyl group-containing polymer compound and water-swellable mica as solid components. The solid content ratio of water-swellable mica in the total solid content of this coating liquid may be within an approximate range indicated by, for example, 20% by mass to 50% by mass.

[0058] The area average diameter of the water-swellable mica is, for example, within an approximate range indicated by 0.5 μm to 5 μm, and may also be within an approximate range indicated by 1.5 μm to 2.5 μm. The aspect ratio of the water-swellable mica is, for example, within an approximate range indicated by 10 or more and 200 or less.

[0059] The thickness of the gas barrier coating layer 5 is preferably 50 to 1000 nm, and more preferably 100 to 500 nm. When the thickness of the gas barrier coating layer 5 is 50 nm or more, there is a tendency to obtain more sufficient gas barrier properties, and when it is 1000 nm or less, there is a tendency to maintain sufficient flexibility.

[0060] The coating agent for forming the gas barrier coating layer 5 can be applied, for example, by dipping method, roll coating method, gravure coating method, reverse gravure coating method, air knife coating method, comma coating method, die coating method, screen printing method, spray coating method, gravure offset method, etc. The coating film formed by applying this coating agent can be dried, for example, by hot air drying method, hot roll drying method, high-frequency irradiation method, infrared irradiation method, UV irradiation method, or a combination thereof. Considering high-speed processability, it is most preferable to perform drying by the hot air drying method for the coating film.

[0061] When drying the above coating film, the temperature and tension can be, for example, a temperature of 30 to 120°C and a tension of 10 to 100 N / m on the surface of the coating film, and it is preferable to set the temperature to 40 to 70°C and the tension to 10 to 70 N / m on the surface of the coating film. By setting the temperature and tension on the surface of the coating film during drying within the above ranges, the occurrence of cracks in the inorganic vapor deposition layer 4 and the gas barrier coating layer 5 can be further suppressed, and excellent barrier properties can be exhibited.

[0062] When forming the gas barrier coating layer 5 by high-speed processing, the temperature and tension when drying the above coating film can be, for example, an oven temperature of 50 to 180°C and a tension of 10 to 100 N / m, and it is preferable to set the oven temperature to 70 to 150°C and the tension to 10 to 70 N / m. By setting the oven temperature and tension during drying within the above ranges, in high-speed processing with a width of 500 mm or more and a speed of 100 m / min or more, the occurrence of cracks in the inorganic vapor deposition layer 4 and the gas barrier coating layer 5 can be further suppressed, and excellent barrier properties can be exhibited.

[0063] From the viewpoint of preventing cracking of the inorganic vapor deposition layer 4, it is preferable that the gas barrier coating layer 5 and the inorganic vapor deposition layer 4 are in direct contact (no other layer intervenes between them). Therefore, it is preferable to form the gas barrier coating layer 5 by applying the above adhesive on the inorganic vapor deposition layer 4 and drying and curing it. Similarly, from the viewpoint of preventing cracking of the inorganic vapor deposition layer 4, it is preferable that the inorganic vapor deposition layer 4 and the underlayer 3 are in direct contact (no other layer intervenes between them).

[0064] The gas barrier laminate according to this embodiment may be provided with a sealant layer or a printing layer on the barrier layer.

[0065] The sealant layer is a layer that imparts heat-sealing properties in the gas barrier laminate. The sealant layer may contain a polyolefin, and the polyolefin may be polyethylene.

[0066] As the material of the sealant layer, polyolefin-based resins among thermoplastic resins are generally used. Specifically, ethylene-based resins such as low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), linear low-density polyethylene resin (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-α-olefin copolymer, ethylene-(meth)acrylic acid copolymer, blend resins of polyethylene and polybutene, homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, propylene-α-olefin copolymer, and other polypropylene-based resins can be used. These thermoplastic resins can be appropriately selected according to the intended use and temperature conditions such as boiling treatment.

[0067] Various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier may be added to the sealant layer.

[0068] The thickness of the sealant layer is determined by the mass of the contents, the shape of the package, etc., but a thickness of generally 30 to 150 μm is preferable.

[0069] As a method for forming the sealant layer, the sealant layer on the film made of the above-mentioned thermoplastic resin can be bonded with the adhesive for forming the above-mentioned gas barrier coating layer 5, the dry lamination method of bonding with an adhesive such as a one-component curable or two-component curable urethane-based adhesive, the non-solvent dry lamination method of bonding the sealant layer on the film using a solvent-free adhesive, the extrusion lamination method of heating and melting the above-mentioned thermoplastic resin, extruding it in a curtain shape, and bonding it, etc. All can be formed by known lamination methods.

[0070] The printing layer is provided at a position visible from the outside of the gas barrier laminate for the purpose of displaying information about the contents, identifying the contents, or improving the design of the packaging bag. The printing method and printing ink are not particularly limited, and are appropriately selected from known printing methods and printing inks in consideration of printability on the film, design properties such as color tone, adhesion, and safety as a food container. As the printing method, for example, a gravure printing method, an offset printing method, a gravure offset printing method, a flexographic printing method, an inkjet printing method, etc. can be used. Among them, the gravure printing method can be preferably used from the viewpoints of productivity and high definition of the pattern.

[0071] In order to enhance the adhesion of the printing layer, various pretreatment such as corona treatment, plasma treatment, and frame treatment can be performed on the surface of the layer forming the printing layer, or a coating layer such as an easy-adhesion layer can be provided.

[0072] As described above, the film constituting the gas barrier laminate according to the present embodiment can be a packaging material (monomaterial) made of a single material with excellent recyclability. The gas barrier laminate can be suitably used for various applications such as packaging products such as containers and bags, sheet molded products such as cosmetic sheets and trays, optical films, resin plates, various label materials, lid materials, and laminated tubes, and particularly can be suitably used for packaging products. Examples of packaging products include pillow bags, standing pouches, three-side seal bags, four-side seal bags, etc.

[0073] <Packaging bag> The packaging bag is formed by making a bag from the gas barrier laminate described above. The packaging bag may be formed into a bag shape by folding a single gas barrier laminate in half with the sealant layers facing each other and then heat-sealing three sides, or by stacking two gas barrier laminates with the sealant layers facing each other and then heat-sealing four sides. The packaging bag can accommodate contents such as food and pharmaceuticals. The packaging bag can be subjected to heat sterilization treatment such as boiling treatment.

[0074] The boiling treatment is a method of moist heat sterilization for preserving food, pharmaceuticals, etc. Usually, although it depends on the contents, the packaging bag containing food, etc. is subjected to moist heat sterilization treatment under the conditions of 60 to 100 °C and atmospheric pressure for 10 to 120 minutes. The boiling treatment is usually carried out at 100 °C or lower using a hot water tank. As methods, there are a batch type in which it is immersed in a hot water tank at a constant temperature, treated for a certain time, and then taken out, and a continuous type in which it is passed through the hot water tank in a tunnel type. The packaging bag of the present embodiment can also be suitably used for applications where boiling treatment is applied.

[0075] Further, the packaging bag may have a shape having a bent portion (folded portion) such as a standing pouch. The packaging bag of the present embodiment can maintain high gas barrier properties even when it has a shape with a bent portion.

Example

[0076] The present invention will be described in more detail by the following examples, but the present invention is not limited to these examples.

[0077] [Base material layer] Base material A: GAP (manufactured by Charter NEX, thickness: 32 μm, un-stretched HDPE) Base material B: SMUQ (manufactured by Tokyo Ink Co., Ltd., thickness: 25 μm, stretched HDPE) Base material C: UB-3 (manufactured by Tamapoli Co., Ltd., thickness: 40 μm, un-stretched MDPE) Base material D: JINDAL (manufactured by JINDAL, thickness: 25 μm, stretched HDPE)

[0078] <Measurement of the arithmetic mean roughness of the base material layer> Using an optical interference surface measuring machine (manufactured by Rhika Systems Co., Ltd., Vertscan R3300h Lite), with a 5x objective lens, the front and back surfaces were each measured 3 times, and the maximum protrusion height (μm) with the largest value in the 3 measurements was taken as the protrusion height (arithmetic mean roughness) of the film.

[0079] [Preparation of the composition for forming the undercoat layer] Acrylic polyol and tolylene diisocyanate were mixed so that the number of NCO groups of tolylene diisocyanate was equal to the number of OH groups of acrylic polyol, and diluted with ethyl acetate so that the total solid content (total amount of acrylic polyol and tolylene diisocyanate) was 5% by mass. To the diluted mixture, β-(3,4-epoxycyclohexyl)trimethoxysilane was further added in an amount of 5 parts by mass with respect to 100 parts by mass of the total amount of acrylic polyol and tolylene diisocyanate, and these were mixed to prepare a composition for forming the undercoat layer (anchor coating agent).

[0080] [Preparation of the composition for forming the gas barrier coating layer (coating agent)] Composition A for forming the gas barrier coating layer: The following Solution A, Solution B, and Solution C were mixed at a mass ratio of 70 / 20 / 10 to prepare Gas Barrier Coating Layer A. Solution A: A hydrolysis solution with a solid content of 5% by mass (in terms of SiO2) obtained by adding 72.1 g of 0.1N hydrochloric acid to 17.9 g of tetraethoxysilane (Si(OC2H5)4) and 10 g of methanol and stirring for 30 minutes for hydrolysis. Solution B: A 5% by mass aqueous / methanol solution of polyvinyl alcohol (mass ratio of water:methanol is 95:5) Solution C: A hydrolysis solution obtained by diluting 1,3,5-tris(3-trialkoxysilylpropyl)isocyanurate with a mixed solution of water / isopropyl alcohol (mass ratio of water:isopropyl alcohol is 1:1) to a solid content of 5% by mass.

[0081] Composition B for forming the gas barrier coating layer: The polyurethane resin, 5% PVA aqueous solution, and silane coupling agent were mixed so that the solid content ratio was 60:35:5, and diluted with water and isopropanol so that the solid content concentration of the liquid was 5%, to prepare the composition B for forming the gas barrier coating layer. At this time, isopropanol was 10% of the whole composition B for forming the gas barrier coating layer.

[0082] Composition C for forming the gas barrier coating layer: As the hydroxyl group-containing polymer compound, polyvinyl alcohol resin (PVA, Selvol-325 (saponification degree: 98 - 99%, polymerization degree 1700), manufactured by Sekisui Specialty Chemicals America, LLC.) was used. The polyvinyl alcohol resin and water were mixed and heated to 95°C to dissolve the polyvinyl alcohol resin in water. After cooling this mixture to room temperature, it was diluted with water and isopropanol (mass ratio 1:1) so that the final solid content concentration was 5% by mass, to prepare component (A). As the water-swellable mica, water-swellable synthetic mica (Somasif MEB-3, manufactured by Coop Agri Co., Ltd.) was used. The water-swellable synthetic mica was processed using a bead mill so that the area particle size became 2 μm. Then, water was mixed so that the final solid content concentration was 8% by mass, to prepare component (B). Component (A) and (B) were diluted with water and methanol (mass ratio 1:1) so that the content of the water-swellable synthetic mica in the final gas barrier coating layer was 15% by mass, to prepare the composition C for forming the gas barrier coating layer.

[0083] (Example 1) On the surface with a small value of the maximum protrusion height of substrate A, the above-described composition for forming the undercoat layer was applied by the gravure roll coating method, dried and cured at 60°C, and the coating amount was 0.1 g / m 2An undercoat layer was formed. On the above undercoat layer, a transparent inorganic vapor deposition layer (silica vapor deposition film) made of silicon oxide with a thickness of 30 nm was formed by a vacuum vapor deposition apparatus using an electron beam heating method. As the silica vapor deposition film, a vapor deposition film with an O / Si of 1.8 was formed by preparing the vapor deposition material species. A composition A for forming a gas barrier coating layer was coated on the above inorganic vapor deposition layer by a gravure roll coating method, and heated and dried in an oven under a tension of 20 N / n and at a condition where the temperature of the coated film surface was 60 °C to form a gas barrier coating layer with a thickness of 0.3 μm. For the heat drying, a heat label (manufactured by Micron Co., Ltd.) was attached to the surface of the coated film before drying, and the oven temperature was adjusted to reach an arbitrary temperature (60 °C in this example) by checking the temperature after drying. Thus, a gas barrier laminate having a laminated structure of a substrate layer / undercoat layer / inorganic vapor deposition layer / gas barrier coating layer was obtained.

[0084] (Example 2) The same operations as in Example 1 were performed except that composition B for forming a gas barrier coating layer was used instead of composition A for forming a gas barrier coating layer, and a gas barrier laminate was obtained.

[0085] (Example 3) The same operations as in Example 1 were performed except that composition C for forming a gas barrier coating layer was used instead of composition A for forming a gas barrier coating layer, and a gas barrier laminate was obtained.

[0086] (Example 4) The same operations as in Example 1 were performed except that a gas barrier coating layer was not formed, and a gas barrier laminate was obtained.

[0087] (Example 5) The same operations as in Example 3 were performed except that an inorganic vapor deposition layer was not formed on the undercoat layer, and a gas barrier laminate was obtained.

[0088] (Comparative Example 1) Substrate B was used instead of substrate A, and an undercoat layer, an inorganic vapor deposition layer, and a gas barrier coating layer were formed in the same manner as in Example 1 on the surface with the larger value of the maximum protrusion height to obtain a gas barrier laminate.

[0089] (Comparative Example 2) Instead of using substrate A, substrate C was used, and an undercoat layer, an inorganic vapor deposition layer, and a gas barrier coating layer were formed on the surface with the smaller maximum protrusion height value in the same manner as in Example 1 to obtain a gas barrier laminate G.

[0090] (Comparative Example 3) Instead of using substrate A, substrate D was used, and an undercoat layer, an inorganic vapor deposition layer, and a gas barrier coating layer were formed on the surface with the smaller maximum protrusion height value in the same manner as in Example 1 to obtain a gas barrier laminate H.

[0091] (Evaluation of Processing Suitability) For the gas barrier laminates A to H produced in Examples 1 to 5 and Comparative Examples 1 to 3, when laminating by roll-to-roll using a gravure coater, those that could be laminated without problems were marked as "〇", and those with wrinkles in winding and deformed winding shapes were marked as "×". The results are shown in Table 1.

[0092] (Evaluation of Oxygen Barrier Property) The oxygen barrier property of the gas barrier laminate according to the example with good processing suitability was measured by JIS K7126, Method B (isobaric method). The measuring device used was OXTRAN 2 / 20 manufactured by MOCON, and the measurement was carried out at a temperature of 30°C and a relative humidity of 70%. The results are shown in Table 1 (unit: cc / m 2 ·day·atm).

[0093] (Coefficient of Dynamic Friction) Assuming that the gas barrier laminate was wound up with a roll or the like, the coefficient of dynamic friction between the back side of the substrate layer and the surface on the opposite side of the substrate layer of the barrier layer in the gas barrier laminate according to the example with good processing suitability was measured under the following conditions. The coefficient of dynamic friction is shown in Table 1. Measurement speed: 100 mm / min Sliding piece: 63×63 mm Mass of sliding piece: 200 g Dynamic frictional force: Average load from the start of relative displacement movement between the contact surfaces to 60 mm (N = 3 times) Coefficient of dynamic friction: Value obtained by dividing the dynamic frictional force by 1.96

[0094]

Table 1

Explanation of Symbols

[0095] 1…Base material layer, 2…Barrier layer, 3…Undercoat layer, 4…Inorganic vapor deposition layer, 5…Gas barrier coating layer, 10…Gas barrier laminate.

Claims

1. A gas barrier laminate comprising a base material layer made of a polyethylene film with a thickness of 15 μm to 50 μm and having a first surface and a second surface, an inorganic vapor deposition layer provided on the second surface side of the base material layer, a gas barrier coating layer, wherein the arithmetic mean roughness a of the first surface of the base material layer is 3 μm to 10 μm, the thickness of the inorganic vapor deposition layer is 10 nm to 50 nm, the thickness of the gas barrier coating layer is 50 nm to 1000 nm, and further comprising an undercoat layer between the base material layer and the inorganic vapor deposition layer.

2. The gas barrier laminate according to claim 1, wherein the coefficient of kinetic friction of the first surface of the base material layer is 0.31 to 0.

36.

3. The base material layer is made of a polyethylene film having a density of 0.940 g / cm ３ or more, and the gas barrier laminate according to claim 1 or 2.

4. The gas barrier laminate according to any one of claims 1 to 3, wherein the base material layer is made of a polyethylene film having a multilayer structure.

5. The gas barrier laminate according to any one of claims 1 to 4, wherein the undercoat layer contains a polyvinyl alcohol-based resin.

6. The gas barrier laminate according to any one of claims 1 to 5, further comprising a sealant layer containing a polyethylene resin on the second surface side of the base material layer.

7. The gas barrier laminate according to claim 6, wherein the sealant layer is a layer formed by an extrusion lamination method.

8. The gas barrier laminate according to claim 6, wherein the sealant layer is a layer formed by a non-solvent lamination method.

9. The gas barrier laminate according to any one of claims 1 to 8, which is a packaging material.

10. A gas barrier laminate comprising a base material layer made of a polyethylene film with a thickness of 15 μm to 50 μm and having a first surface and a second surface, an inorganic vapor deposition layer provided on the second surface side of the base material layer, wherein the coefficient of kinetic friction of the first surface of the base material layer is 0.31 to 0.36, the thickness of the inorganic vapor deposition layer is 10 nm to 50 nm, and further comprising an undercoat layer between the base material layer and the inorganic vapor deposition layer.

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