Laminate, packaging material, and method for manufacturing a laminate

Abstract

To provide a laminate with excellent adhesion and resistance to contents, a packaging material comprising the laminate, and a method for manufacturing the laminate. [Solution] The laminate 1 comprises a barrier layer 2, a surface modification layer 3 disposed on one side of the barrier layer 2 in the thickness direction, and an adhesive layer 4 disposed on one side of the surface modification layer 3 in the thickness direction. The barrier layer 2 comprises an inorganic layer 11 containing inorganic material. The inorganic layer 11 is in contact with the surface modification layer 3. The surface modification layer 3 is a coating of a surface modification composition. The surface modification composition contains a metal compound and a (meth)acrylic resin. The (meth)acrylic resin has carboxyl groups. The adhesive layer 4 is a coating of an adhesive composition. The adhesive composition contains an unsaturated carboxylic acid-modified polyolefin resin and an epoxy compound. The equivalent ratio of the epoxy groups of the epoxy compound to the carboxyl groups of the unsaturated carboxylic acid-modified polyolefin resin is greater than 0 and 1.0 or less.

Description

Technical Field

[0001] The present invention relates to a laminate, a packaging material, and a method for manufacturing a laminate. More specifically, the present invention relates to a laminate, a packaging material including the laminate, and a method for manufacturing the laminate.

Background Art

[0002] Conventionally, a laminate film is known as a packaging material. The laminate film is prepared by bonding two base materials with an adhesive.

[0003] As such an adhesive, for example, a dry lamination adhesive composition containing an aqueous dispersion containing an unsaturated carboxylic acid-modified polyolefin resin (A), an epoxy compound (B), a silane coupling agent (C), and an aqueous solvent (D) has been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] On the other hand, from the perspective of resistance to contents, a film having an inorganic layer is employed as the base material. Therefore, improvement in adhesion to the film having an inorganic layer is required.

[0006] In addition, improvement in resistance to contents is required for the laminate film.

[0007] The present invention provides a laminate excellent in adhesion and resistance to contents, a packaging material including the laminate, and a method for manufacturing the laminate.

Means for Solving the Problems

[0008] The present invention [1] is a laminate comprising a barrier layer, a surface modification layer disposed on one side in the thickness direction of the barrier layer, and an adhesive layer disposed on one side in the thickness direction of the surface modification layer, wherein the barrier layer comprises an inorganic layer containing inorganic material, the inorganic layer is in contact with the surface modification layer, the surface modification layer is a coating of a surface modification composition, the surface modification composition comprises a metal compound and a (meth)acrylic resin, the (meth)acrylic resin has carboxyl groups, the adhesive layer is a coating of an adhesive composition, the adhesive composition comprises an unsaturated carboxylic acid-modified polyolefin resin and an epoxy compound, the equivalent ratio of epoxy groups of the epoxy compound to carboxyl groups of the unsaturated carboxylic acid-modified polyolefin resin is greater than 0 and 1.0 or less.

[0009] The present invention [2] comprises the laminate described in [1] above, wherein the epoxy compound has two or more epoxy groups in one molecule, heteroatoms other than oxygen atoms contained in the epoxy groups, a single cyclic hydrocarbon group, and / or a tetrasubstituted carbon group.

[0010] The present invention [3] includes the laminate described in [1] or [2] above, wherein the unsaturated carboxylic acid-modified polyolefin resin is a polymer of raw material monomer components, the raw material monomer components include an olefin and an unsaturated carboxylic acid, and the content of constituent units derived from the unsaturated carboxylic acid is 2% by mass or more and 10% by mass or less with respect to the unsaturated carboxylic acid-modified polyolefin resin.

[0011] The present invention [4] comprises a laminate according to any one of the above [1] to [3], wherein the adhesive composition contains a silane coupling agent.

[0012] The present invention [5] includes a laminate according to any one of the above [1] to [4], wherein the metal compound is a zirconium compound and the mass ratio of zirconium in the zirconium compound to the (meth)acrylic resin (zirconium / (meth)acrylic resin) is 0.30 or more and 4.00 or less, or the metal compound is a trivalent chromium compound and the mass ratio of trivalent chromium in the trivalent chromium compound to the (meth)acrylic resin (trivalent chromium / (meth)acrylic resin) is 0.15 or more and 0.50 or less.

[0013] The present invention [6] includes a laminate according to any one of the above [1] to [5], wherein the acid value of the (meth)acrylic resin is 150 mg KOH / g or more and 780 mg KOH / g or less.

[0014] The present invention [7] includes a laminate according to any one of the above [1] to [6], wherein the ratio of the thickness of the adhesive layer to the thickness of the surface modified layer is 2 or more and 350 or less.

[0015] The present invention [8] further includes a laminate according to any one of the above [1] to [7], comprising a base layer disposed on one side in the thickness direction of the adhesive layer.

[0016] The present invention [9] includes a packaging material comprising a laminate as described in any one of the above [1] to [8].

[0017] The present invention

[10] is a method for manufacturing a laminate, comprising: a first step of preparing a barrier layer; a second step of arranging a surface modified layer by applying a surface modification composition to one side in the thickness direction of the barrier layer and drying it; and a third step of arranging an adhesive layer by applying an adhesive composition to one side in the thickness direction of the surface modified layer and drying it, wherein the barrier layer comprises an inorganic layer containing inorganic material, the inorganic layer is in contact with the surface modified layer, the surface modified composition comprises a metal compound and a (meth)acrylic resin, the (meth)acrylic resin has carboxyl groups, the adhesive composition comprises an unsaturated carboxylic acid modified polyolefin resin and an epoxy compound, and the equivalent ratio of epoxy groups of the epoxy compound to carboxyl groups of the unsaturated carboxylic acid modified polyolefin resin is greater than 0 and 1.0 or less. [Effects of the Invention]

[0018] In the laminate of the present invention, the equivalent ratio of epoxy groups of the epoxy compound to carboxyl groups of the unsaturated carboxylic acid-modified polyolefin resin is greater than 0 and 1.0 or less. Therefore, adhesion and resistance to contents can be improved.

[0019] The packaging material of the present invention comprises the laminate of the present invention. Therefore, it has excellent adhesion and resistance to contents.

[0020] In the method for producing the laminate of the present invention, the equivalent ratio of epoxy groups of the epoxy compound to carboxyl groups of the unsaturated carboxylic acid-modified polyolefin resin is greater than 0 and 1.0 or less. Therefore, a laminate with excellent adhesion and resistance to contents can be produced. [Brief explanation of the drawing]

[0021] [Figure 1] Figure 1 is a schematic cross-sectional view of one embodiment of the laminate of the present invention. [Figure 2]Figures 2A to 2D show an embodiment of a method for manufacturing the laminate of the present invention. Figure 2A shows the first step of preparing a barrier layer. Figure 2B shows the second step of disposing a surface modification layer by applying a surface modification composition to one side in the thickness direction of the barrier layer and drying it. Figure 2C shows the third step of disposing an adhesive layer by applying an adhesive composition to one side in the thickness direction of the surface modification layer and drying it. Figure 2D shows the fourth step of disposing a base material layer on one side in the thickness direction of the adhesive layer.

Mode for Carrying Out the Invention

[0022] Referring to FIG. 1, an embodiment of the laminate of the present invention will be described.

[0023] In FIG. 1, the vertical direction on the paper surface is the vertical direction (thickness direction). Also, the upper side of the paper surface is the upper side (one side in the thickness direction). Also, the lower side of the paper surface is the lower side (the other side in the thickness direction). Also, the left-right direction and the depth direction on the paper surface are plane directions orthogonal to the vertical direction. Specifically, it conforms to the direction arrows in each figure.

[0024] 1. Laminate As shown in FIG. 1, the laminate 1 has a film shape (including a sheet shape) having a predetermined thickness. The laminate 1 extends in a plane direction orthogonal to the thickness direction. The laminate 1 has a flat upper surface and a flat lower surface.

[0025] The laminate 1 includes a barrier layer 2, a surface modification layer 3 disposed on one side in the thickness direction of the barrier layer 2, an adhesive layer 4 disposed on one side in the thickness direction of the surface modification layer 3, and a base material layer 5 disposed on one side in the thickness direction of the adhesive layer 4. Specifically, the laminate 1 includes a barrier layer 2, a surface modification layer 3 disposed directly on the upper surface (one side in the thickness direction) of the barrier layer 2, an adhesive layer 4 disposed directly on the upper surface (one side in the thickness direction) of the surface modification layer 3, and a base material layer 5 disposed directly on the upper surface (one side in the thickness direction) of the adhesive layer 4.

[0026] The thickness of the laminate 1 is, from the viewpoint of handleability, for example, 10 μm to 500 μm, preferably 20 μm to 200 μm.

[0027] <Barrier layer> Barrier layer 2 has resistance to the contents. Barrier layer 2 has a film shape. Barrier layer 2 is the bottom layer of laminate 1.

[0028] The barrier layer 2 comprises a support layer 10 and an inorganic layer 11 in order in the thickness direction.

[0029] The thickness of barrier layer 2 is, for example, 5 μm to 50 μm, preferably 10 μm to 30 μm.

[0030] [Support layer] Examples of materials for the support layer 10 include resin materials. Examples of resin materials include olefin resins (e.g., polyethylene, polypropylene), acrylic resins, polyester resins (e.g., polyethylene terephthalate and polybutylene terephthalate), polycarbonate resins, acrylonitrile-styrene-butadiene copolymer resins (ABS resins), polyamide resins (e.g., nylon), and polyphenylene sulfide resins.

[0031] Preferably, the material for the support layer 10 is an olefin resin, a polyester resin, or a polyamide resin. More preferably, the support layer 10 is a polyamide resin or polyethylene terephthalate.

[0032] The thickness of the support layer 10 is, for example, 1 μm to 20 μm, preferably 10 μm to 15 μm.

[0033] [Inorganic layer] The inorganic layer 11 is placed on the upper surface (one side in the thickness direction) of the support layer 10. The inorganic layer 11 is in contact with the surface modification layer 3. The inorganic layer 11 contains inorganic material.

[0034] Examples of inorganic materials include metals. In other words, the inorganic layer 11 is, for example, a metal film.

[0035] Examples of metals include aluminum, stainless steel, gold, silver, copper, iron, lead, nickel, zinc, titanium, cobalt, indium, and chromium. Aluminum is preferred as the metal. In other words, the inorganic layer 11 is a metal film (metal foil), preferably an aluminum film (aluminum foil).

[0036] Metals can be used individually or in combination of two or more types.

[0037] Furthermore, the support layer 10 and the inorganic layer 11 are bonded together with a known adhesive (two-component adhesive) as needed. In such cases, the barrier layer 2 comprises the support layer 10, an adhesive layer (not shown) consisting of a known adhesive or primer, and the inorganic layer 11, arranged sequentially on one side in the thickness direction. Examples of primers include at least one selected from polyester resins, polyurethane resins, polyacrylic resins, epoxy resins, polyvinyl alcohol resins, melamine resins, and polyolefin resins, and a mixture thereof.

[0038] Alternatively, an inorganic layer 11 can be formed on the support layer 10 by a dry process to prepare the barrier layer 2. Examples of dry processes include sputtering and vacuum deposition. Vacuum deposition is preferred as the dry process. In other words, such an inorganic layer 11 is a metal deposition layer, and such a barrier layer 2 is a metal deposition resin film.

[0039] Furthermore, depending on the application, the support layer 10 may be multi-layered. For example, if the support layer 10 consists of two layers, the barrier layer 2 comprises the support layer 10, an adhesive layer (not shown) which may be provided as needed, the support layer 10, an adhesive layer (not shown) which may be provided as needed, and an inorganic layer 11, in that order toward one side in the thickness direction.

[0040] The thickness of the inorganic layer 11 is, for example, 0.001 μm to 20 μm, preferably 1 μm to 20 μm, and more preferably 7 μm to 10 μm. In particular, when the inorganic layer 11 is a metal film, the thickness of the inorganic layer 11 is, for example, 1 μm to 20 μm, preferably 7 μm to 10 μm. Also, when the inorganic layer 11 is formed by a dry process (preferably when the inorganic layer 11 is a metal vapor-deposited layer), the thickness of the inorganic layer 11 is not particularly limited, but is, for example, 0.001 μm to 1 μm, preferably 0.002 μm to 0.1 μm, and more preferably 0.003 μm to 0.05 μm.

[0041] <Surface modification layer> The surface modification layer 3 improves the adhesion between the barrier layer 2 and the adhesive layer 4, and protects the inorganic layer 11 (corrosion resistance), thereby improving the resistance of the contents of the laminate 1.

[0042] The surface modification layer 3 is positioned on the upper surface of the barrier layer 2 so as to be in contact with the upper surface of the barrier layer 2.

[0043] The surface modification layer 3 is a coated surface of the surface modification composition.

[0044] The surface modification composition includes a metal compound and a (meth)acrylic resin.

[0045] [Metal compounds] Examples of metal compounds include zirconium compounds, titanium compounds, and trivalent chromium compounds.

[0046] Examples of zirconium compounds include hydrozirconate fluoride (H2ZrF6), ammonium zirconate hexafluoride ((NH4)2ZrF6), ammonium zirconium carbonate ((NH4)2ZrO(CO3)2), tetraalkylammonium-modified zirconium, zirconium monoacetyl acetate, and zirconium tetraacetyl acetate. Preferably, the zirconium compound is ammonium zirconium carbonate ((NH4)2ZrO(CO3)2).

[0047] Examples of titanium compounds include titanium hydrofluoric acid, titanium ammonium fluoride salts, alkoxytitanium, and titanium lactate ammonium salts.

[0048] Examples of trivalent chromium compounds include chromium(III) fluoride, chromium(III) nitrate, chromium(III) phosphate, chromium(III) acetate, chromium(III) chloride, chromium(III) sulfate, chromium(III) oxalate, chromium(III) formate, chromium(III) hydroxide, chromium(III) oxide, chromium(III) bromide, and chromium(III) iodide. Chromium(III) nitrate is a preferred trivalent chromium compound.

[0049] Metal compounds are either water-soluble or water-dispersible.

[0050] Preferably, the metal compound is a zirconium compound or a trivalent chromium compound. More preferably, the metal compound is a zirconium compound.

[0051] Metal compounds can be used alone or in combination of two or more types.

[0052] The content ratio of the metal compound is, for example, 20 to 90 parts by mass, preferably 30 to 80 parts by mass, and more preferably 40 to 70 parts by mass, per 100 parts by mass of the total amount of the metal compound and (meth)acrylic resin. The total mass of the (meth)acrylic resin can be calculated from the amount of polymerization components (described later) added.

[0053] More specifically, the content ratio of the metal compound is, from the viewpoint of improving adhesion, for example, 20 parts by mass or more, preferably 30 parts by mass or more, and more preferably 40 parts by mass or more, relative to 100 parts by mass of the total amount of the metal compound and (meth)acrylic resin. Also, from the viewpoint of improving adhesion, for example, 90 parts by mass or less, preferably 80 parts by mass or less, and more preferably 70 parts by mass or less.

[0054] Furthermore, the metal compound content is, for example, 20% to 90% by mass, preferably 30% to 80% by mass, and more preferably 40% to 70% by mass, relative to the total amount of solids contained in the surface modification composition. The solids contained in the surface modification composition refer to the mass ratio (%) of the residue after heating the surface modification composition at 150°C for 1 hour, relative to the total mass of the surface modification composition before heating.

[0055] [(meth)acrylic resin] (Meth)acrylic resin is a polymer of polymerization components containing carboxyl group-containing vinyl monomers. In other words, (meth)acrylic resin has carboxyl groups derived from carboxyl group-containing vinyl monomers. Note that (meth)acrylic is methacrylic and / or acrylic.

[0056] Examples of carboxyl group-containing vinyl monomers include (meth)acrylic acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, and crotonic acid. Preferably, (meth)acrylic acid is used as the carboxyl group-containing vinyl monomer. More preferably, acrylic acid is used as the carboxyl group-containing vinyl monomer.

[0057] Carboxylic acid-containing vinyl monomers can be used alone or in combination of two or more types.

[0058] The content of carboxyl group-containing vinyl monomer is 30% to 90% by mass, preferably 50% to 70% by mass, relative to the total amount of polymerized components at the time of preparation, when the polymerized components include copolymerizable monomers as described later.

[0059] The polymerization component may include copolymerizable monomers that can copolymerize with carboxyl group-containing vinyl monomers.

[0060] Examples of copolymerizable monomers include alkyl (meth)acrylates, functional group-containing vinyl monomers (excluding carboxyl group-containing vinyl monomers), aromatic vinyl monomers, N-substituted unsaturated carboxylic acid amides, heterocyclic vinyl compounds, vinylidene halides, α-olefins, and dienes.

[0061] Examples of alkyl (meth)acrylates include alkyl (meth)acrylates having an alkyl moiety with 1 to 12 carbon atoms. Examples of alkyl (meth)acrylates having an alkyl moiety with 1 to 12 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate.

[0062] Examples of functional group-containing vinyl monomers include hydroxyl group-containing vinyl monomers, amino group-containing vinyl monomers, glycidyl group-containing vinyl monomers, cyano group-containing vinyl monomers, sulfonic acid group-containing vinyl monomers and their salts, acetoacetoxy group-containing vinyl monomers, phosphate group-containing compounds, and amide group-containing vinyl monomers.

[0063] Examples of hydroxyl group-containing vinyl monomers include hydroxyalkyl (meth)acrylate. Examples of hydroxyalkyl (meth)acrylates include 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate. Preferably, 2-hydroxyethyl (meth)acrylate is used as the hydroxyl group-containing vinyl monomer. More preferably, 2-hydroxyethyl methacrylate is used as the hydroxyl group-containing vinyl monomer.

[0064] Examples of amino group-containing vinyl monomers include 2-aminoethyl (meth)acrylate, 2-(N-methylamino)ethyl (meth)acrylate, and 2-(N,N-dimethylamino)ethyl (meth)acrylate.

[0065] Examples of vinyl monomers containing a glycidyl group include glycidyl (meth)acrylate.

[0066] Examples of cyano group-containing vinyl monomers include (meth)acrylonitrile.

[0067] Examples of sulfonic acid group-containing vinyl monomers include allyl sulfonic acid and methallyl sulfonic acid. Examples of salts thereof include alkali metal salts (e.g., sodium salts and potassium salts) of the above sulfonic acid group-containing vinyl monomers, such as ammonium salts. Specifically, examples include sodium allyl sulfonate, sodium methallyl sulfonate, and ammonium methallyl sulfonate.

[0068] Examples of vinyl monomers containing an acetoacetoxy group include acetoacetoxyethyl (meth)acrylate.

[0069] Examples of phosphate group-containing compounds include 2-methachlorooxyethyl acid phosphate.

[0070] Examples of amide group-containing vinyl monomers include (meth)acrylamide.

[0071] Examples of vinyl esters include vinyl propionate.

[0072] Examples of aromatic vinyl monomers include styrene, α-methylstyrene, and divinylbenzene.

[0073] An example of an N-substituted unsaturated carboxylic acid amide is N-methylol(meth)acrylamide.

[0074] Examples of heterocyclic vinyl compounds include vinylpyrrolidone.

[0075] Examples of vinylidene halogen compounds include vinylidene chloride and vinylidene fluoride.

[0076] Examples of α-olefins include ethylene and propylene.

[0077] Examples of dienes include butadiene.

[0078] Furthermore, crosslinkable vinyl monomers can be cited as copolymerizable monomers.

[0079] Examples of crosslinkable vinyl monomers include compounds containing two or more vinyl groups. Examples of compounds containing two or more vinyl groups include methylenebis(meth)acrylamide, divinylbenzene, and polyethylene glycol chain-containing di(meth)acrylates.

[0080] Preferably, copolymerizable monomers include hydroxyl group-containing vinyl monomers.

[0081] The content of copolymerizable monomers is, for example, 10% to 70% by mass, preferably 30% to 50% by mass, relative to the total amount of polymerized components at the time of preparation.

[0082] Copolymerizable monomers can be used individually or in combination of two or more types.

[0083] Furthermore, the polymerization components mainly consist of monomers having an acryloyl group (for example, (meth)acrylic acid, alkyl (meth)acrylate, and hydroxyalkyl (meth)acrylate) from among the above monomers. Specifically, the content of monomers having an acryloyl group is, for example, 50% by mass or more of the total amount of polymerization components at the time of preparation.

[0084] The polymerization method for the polymerization components is not particularly limited, and known polymerization methods can be used.

[0085] Preferably, the polymerization component is subjected to radical polymerization in an aqueous solvent, as described later. In this method, for example, the polymerization component and a polymerization initiator are mixed in an aqueous solvent and polymerized in the aqueous solvent.

[0086] The polymerization initiator is not particularly limited. Examples of polymerization initiators include persulfates, organic peroxides, and azo compounds. Preferably, an azo compound is used as the polymerization initiator. An example of an azo compound is 4,4'-azobis(4-cyanovaleric acid) (ACVA).

[0087] Furthermore, the proportion of polymerization initiators is set appropriately according to the purpose and application.

[0088] Polymerization initiators can be used alone or in combination of two or more types.

[0089] The polymerization conditions are as follows: under atmospheric pressure, the polymerization temperature is, for example, 30°C or higher, preferably 50°C or higher, and for example, 150°C or lower, preferably 120°C or lower. The polymerization time is, for example, 1 hour or more, preferably 2 hours or more, and for example, 30 hours or less, preferably 20 hours or less.

[0090] Furthermore, in the polymerization described above, a neutralizing agent (e.g., aqueous ammonia) may be added in an appropriate proportion. When a neutralizing agent is used, the amount corresponding to the functional groups neutralized by the neutralizing agent shall be included in the mass of the (meth)acrylic resin.

[0091] This yields (meth)acrylic resin.

[0092] (Meth)acrylic resins are water-soluble or water-dispersible.

[0093] The weight-average molecular weight of (meth)acrylic resin is, for example, 15,000 to 500,000, calculated on a standard polystyrene basis by gel permeation chromatography (GPC).

[0094] The acid value of the (meth)acrylic resin (more specifically, the acid value of the solid content of the (meth)acrylic resin) is, for example, 150 mg KOH / g to 780 mg KOH / g, preferably 180 mg KOH / g to 700 mg KOH / g, more preferably 200 mg KOH / g to 600 mg KOH / g, and even more preferably 300 mg KOH / g to 500 mg KOH / g.

[0095] The acid value of the (meth)acrylic resin is, from the viewpoint of adhesion and corrosion resistance, for example, 150 mg KOH / g or more, preferably 180 mg KOH / g or more, more preferably 200 mg KOH / g or more, and even more preferably 300 mg KOH / g or more. Also, from the viewpoint of adhesion and corrosion resistance, it is 780 mg KOH / g or less, preferably 700 mg KOH / g or less, more preferably 600 mg KOH / g or less, and even more preferably 500 mg KOH / g or less.

[0096] Furthermore, the acid value of (meth)acrylic resin can be calculated by determining the amount of potassium hydroxide (in mg) required to neutralize the acid groups contained in 1 g of the solid content of the acrylic resin, based on the mixing ratio of polymerization components and neutralizing agents.

[0097] The content of (meth)acrylic resin is, for example, 10 to 80 parts by mass, preferably 20 to 70 parts by mass, and more preferably 30 to 60 parts by mass, per 100 parts by mass of the total amount of metal compound and (meth)acrylic resin.

[0098] More specifically, the content of (meth)acrylic resin is, from the viewpoint of improving adhesion, for example, 10 parts by mass or more, preferably 20 parts by mass or more, and more preferably 30 parts by mass or more, relative to 100 parts by mass of the total amount of metal compound and (meth)acrylic resin. Also, from the viewpoint of improving adhesion, for example, 80 parts by mass or less, preferably 70 parts by mass or less, and more preferably 60 parts by mass or less.

[0099] Furthermore, the content of (meth)acrylic resin is, for example, 10% to 80% by mass, preferably 20% to 70% by mass, and more preferably 30% to 60% by mass, relative to the total amount of solids contained in the surface modification composition.

[0100] Furthermore, when the metal compound is a zirconium compound, the mass ratio of zirconium in the zirconium compound to the (meth)acrylic resin (zirconium / (meth)acrylic resin) is, for example, 0.30 to 4.00, preferably 1.00 to 2.00.

[0101] More specifically, the above mass ratio (zirconium / (meth)acrylic resin) is, for example, 0.30 or higher, preferably 0.60 or higher, and more preferably 1.00 or higher, from the viewpoint of improving the resistance to internal materials, and for example, 4.00 or lower, preferably 2.00 or lower, from the viewpoint of suppressing a decrease in peel strength.

[0102] Furthermore, when the metal compound is a trivalent chromium compound, the mass ratio of trivalent chromium in the trivalent chromium compound to (meth)acrylic resin (trivalent chromium / (meth)acrylic resin) is, for example, 0.15 to 0.50, preferably 0.18 to 0.30.

[0103] More specifically, the above mass ratio (trivalent chromium / (meth)acrylic resin) is, for example, 0.15 or more, preferably 0.18 or more, from the viewpoint of improving the resistance to internal materials, and, for example, 0.50 or less, preferably 0.30 or less, from the viewpoint of suppressing a decrease in peel strength.

[0104] [Other resins] The surface modification composition may also contain other resins as needed.

[0105] Other resins include, for example, polyester resins, alkyd resins, epoxy resins, and urethane resins.

[0106] Other resins can be used individually or in combination of two or more types.

[0107] The content of other resins is, for example, 5% by mass or less, preferably 1% by mass or less, and more preferably 0% by mass, relative to the total amount of solids contained in the surface modification composition. In other words, the surface modification composition preferably does not contain other resins.

[0108] [Additives] The surface modification composition may also contain additives in appropriate proportions, if necessary.

[0109] Examples of additives include stabilizers (water-soluble phosphorus compounds), antioxidants, surface modifiers, defoamers, and antibacterial agents.

[0110] Additives can be used individually or in combination of two or more types.

[0111] [Preparation of surface modification composition] The surface modification composition is prepared by mixing a metal compound, a (meth)acrylic resin, other resins as needed, and additives as needed.

[0112] Furthermore, the surface modification composition may be diluted with an aqueous solvent if necessary.

[0113] Examples of aqueous solvents include water, alcohol, ether, and ether alcohol.

[0114] Examples of alcohols include monohydric and dihydric alcohols having 1 to 4 carbon atoms. Examples of monohydric and dihydric alcohols having 1 to 4 carbon atoms include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, ethylene glycol, and propylene glycol. Examples of ethers include ethers having 2 to 5 carbon atoms. Examples of ethers having 2 to 4 carbon atoms include dimethoxyethane and tetrahydrofuran. Examples of ether alcohols include ether alcohols having 2 to 4 carbon atoms. An example of an ether alcohol having 2 to 4 carbon atoms is methyl cellosolve.

[0115] Preferably, an alcohol is used as the aqueous solvent. More preferably, isopropyl alcohol is used as the aqueous solvent.

[0116] Water-based solvents can be used alone or in combination of two or more types.

[0117] This prepares a solution (or aqueous solution) of the surface modification composition, or a dispersion of the surface modification composition.

[0118] The solid content concentration of the solution (or aqueous solution) of the surface modification composition, or the dispersion of the surface modification composition, is, for example, 0.1% by mass to 10% by mass.

[0119] Furthermore, the content of the metal compound is, for example, 10 ppm to 60,000 ppm by mass, preferably 50 ppm to 50,000 ppm by mass, more preferably 100 ppm to 40,000 ppm by mass, even more preferably 250 ppm to 30,000 ppm by mass, and particularly preferably 500 ppm to 15,000 ppm by mass, relative to the solution (or aqueous solution) or dispersion of the surface modification composition.

[0120] More specifically, the content of the metal compound in the solution (or aqueous solution) or dispersion of the surface modification composition is, from the viewpoint of adhesion and corrosion resistance, for example, 10 ppm by mass or more, preferably 50 ppm by mass or more, more preferably 100 ppm by mass or more, even more preferably 250 ppm by mass or more, and particularly preferably 500 ppm by mass or more. Furthermore, from the viewpoint of adhesion, it is, for example, 60,000 ppm by mass or less, preferably 50,000 ppm by mass or less, more preferably 40,000 ppm by mass or less, even more preferably 30,000 ppm by mass or less, and particularly preferably 15,000 ppm by mass or less.

[0121] Furthermore, the content of (meth)acrylic resin is, for example, 10 ppm to 60,000 ppm by mass, preferably 100 ppm to 50,000 ppm by mass, more preferably 500 ppm to 40,000 ppm by mass, even more preferably 1,000 ppm to 30,000 ppm by mass, and particularly preferably 2,000 ppm to 15,000 ppm by mass, relative to the solution (or aqueous solution) or dispersion of the surface modification composition.

[0122] More specifically, the content of (meth)acrylic resin in the solution (or aqueous solution) or dispersion of the surface modification composition is, from the viewpoint of adhesion and corrosion resistance, for example, 10 ppm by mass or more, preferably 100 ppm by mass or more, more preferably 500 ppm by mass or more, even more preferably 1000 ppm by mass or more, and particularly preferably 2000 ppm by mass or more. Furthermore, from the viewpoint of suppressing increased viscosity, for example, 60000 ppm by mass or less, preferably 50000 ppm by mass or less, more preferably 40000 ppm by mass or less, even more preferably 30000 ppm by mass or less, and particularly preferably 15000 ppm by mass or less.

[0123] As will be explained in more detail later, the surface modification layer 3 is obtained by applying a surface modification composition (specifically, a solution (or aqueous solution) of the surface modification composition, or a dispersion of the surface modification composition) to one side in the thickness direction of the barrier layer 2 and drying it. In other words, the surface modification layer 3 is a coating of the surface modification composition.

[0124] The thickness of the surface modification layer 3 is, for example, 0.01 μm to 4.00 μm, preferably 0.02 μm to 1.00 μm, and more preferably 0.03 μm to 0.10 μm.

[0125] <Adhesive layer> The adhesive layer 4 is positioned over the entire upper surface of the surface modification layer 3 so as to be in contact with the upper surface of the surface modification layer 3.

[0126] The adhesive layer 4 is a coated surface of the adhesive composition.

[0127] The adhesive composition comprises an unsaturated carboxylic acid-modified polyolefin resin (A) and an epoxy compound (B).

[0128] [Unsaturated carboxylic acid-modified polyolefin resin (A)] Unsaturated carboxylic acid-modified polyolefin resin (A) is a polymer of raw material monomer components.

[0129] The raw material monomer components include olefins and unsaturated carboxylic acids.

[0130] Examples of olefins include ethylene, propylene, and α-olefins having four or more carbon atoms.

[0131] Examples of α-olefins having 4 or more carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 1-dodecene.

[0132] A preferred example of an olefin is ethylene.

[0133] Olefins can be used alone or in combination of two or more types.

[0134] The olefin content is, for example, 60% to 99% by mass, preferably 65% ​​to 95% by mass, more preferably 70% to 90% by mass, even more preferably 75% to 85% by mass, and particularly preferably 78% to 82% by mass, relative to the total amount of raw material monomer components.

[0135] The proportion of olefins in the raw material monomer components is substantially equivalent to the proportion of constituent units derived from olefins in the unsaturated carboxylic acid-modified polyolefin resin (A).

[0136] In other words, the content of constituent units derived from olefins is, for example, 60% to 99% by mass, preferably 65% ​​to 95% by mass, more preferably 70% to 90% by mass, even more preferably 75% to 85% by mass, and particularly preferably 78% to 82% by mass, relative to the unsaturated carboxylic acid-modified polyolefin resin (A).

[0137] Examples of unsaturated carboxylic acids include unsaturated monocarboxylic acids and unsaturated dicarboxylic acids. Examples of unsaturated monocarboxylic acids include (meth)acrylic acid, crotonic acid, and isocrotonic acid. Examples of unsaturated dicarboxylic acids include maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, and norbornene dicarboxylic acid, and their acid anhydrides.

[0138] Preferably, unsaturated carboxylic acids include (meth)acrylic acid and maleic anhydride. More preferably, (meth)acrylic acid is used as an unsaturated carboxylic acid. Even more preferably, methacrylic acid is used as an unsaturated carboxylic acid.

[0139] Unsaturated carboxylic acids can be used alone or in combination of two or more types.

[0140] The content of unsaturated carboxylic acids is, for example, 2% to 10% by mass, preferably 5% to 10% by mass, more preferably 7% to 10% by mass, and even more preferably 9% to 10% by mass, relative to the total amount of raw material monomer components.

[0141] More specifically, the content of unsaturated carboxylic acid is, from the viewpoint of dispersibility, for example, 2% by mass or more, preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 9% by mass or more, relative to the total amount of raw material monomer components, and from the viewpoint of resistance to contents, for example, 10% by mass or less.

[0142] The proportion of unsaturated carboxylic acids in the raw material monomer components is substantially equivalent to the proportion of constituent units derived from unsaturated carboxylic acids in the unsaturated carboxylic acid-modified polyolefin resin (A).

[0143] In other words, the content of constituent units derived from unsaturated carboxylic acids is, for example, 2% to 10% by mass, preferably 5% to 10% by mass, more preferably 7% to 10% by mass, and even more preferably 9% to 10% by mass, relative to the unsaturated carboxylic acid-modified polyolefin resin (A).

[0144] More specifically, the content of constituent units derived from unsaturated carboxylic acids is, from the viewpoint of dispersibility, for example, 2% by mass or more, preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 9% by mass or more, relative to the unsaturated carboxylic acid-modified polyolefin resin (A), and from the viewpoint of content resistance, for example, 10% by mass or less.

[0145] The raw material monomer components may, if necessary, include copolymerizable monomers that can copolymerize with olefins and unsaturated carboxylic acids.

[0146] Examples of copolymerizable monomers include those similar to the copolymerizable monomers listed above for (meth)acrylic resins. Preferably, alkyl (meth)acrylates are used as copolymerizable monomers. More preferably, ethyl (meth)acrylates and iso-butyl (meth)acrylates are used as copolymerizable monomers. Even more preferably, ethyl acrylates and iso-butyl acrylates are used as copolymerizable monomers. Particularly preferred iso-butyl acrylate is used as a copolymerizable monomer.

[0147] Copolymerizable monomers can be used individually or in combination of two or more types.

[0148] The content of copolymerizable monomers is, for example, 0% to 20% by mass, preferably 1% to 18% by mass, more preferably 5% to 15% by mass, and even more preferably 7% to 13% by mass, relative to the total amount of raw material monomer components.

[0149] The proportion of copolymerizable monomers in the raw material monomer components is substantially equivalent to the proportion of constituent units derived from copolymerizable monomers in the unsaturated carboxylic acid-modified polyolefin resin (A).

[0150] In other words, the content of constituent units derived from copolymerizable monomers is, for example, 0% to 20% by mass, preferably 1% to 18% by mass, more preferably 5% to 15% by mass, and even more preferably 7% to 13% by mass, relative to the unsaturated carboxylic acid-modified polyolefin resin (A).

[0151] The raw material monomer components preferably include copolymerizable monomers along with olefins and unsaturated carboxylic acids. In other words, the unsaturated carboxylic acid-modified polyolefin resin (A) is preferably a copolymer of olefins, unsaturated carboxylic acids, and copolymerizable monomers.

[0152] The polymerization method for the raw material monomer components is not particularly limited, and known polymerization methods can be used.

[0153] Preferably, the raw material monomer component is subjected to radical polymerization in an aqueous solvent (the aqueous solvent mentioned in the surface modification composition). In this method, for example, the raw material monomer component and a polymerization initiator (for example, the polymerization initiator mentioned in the (meth)acrylic resin) are blended in the aqueous solvent and polymerized in the aqueous solvent.

[0154] Furthermore, a neutralizing agent can be added in an appropriate proportion during the polymerization process described above.

[0155] Examples of neutralizing agents include basic compounds. Examples of basic compounds include inorganic basic compounds and organic basic compounds. Examples of inorganic basic compounds include sodium hydroxide and potassium hydroxide. Examples of organic basic compounds include amines. Examples of amines include ammonia, triethylamine (TEA), triethanolamine, dimethylethanolamine, diethanolamine, diethylamine (DEA), and N,N-dimethylethanolamine. Preferably, organic basic compounds are used as neutralizing agents. More preferably, ammonia, triethylamine (TEA), and diethylamine (DEA) are used as neutralizing agents. Even more preferably, ammonia and diethylamine (DEA) are used as neutralizing agents.

[0156] Neutralizing agents can be used alone or in combination of two or more types.

[0157] This polymerizes the raw material monomer components to obtain an unsaturated carboxylic acid-modified polyolefin resin (A) (specifically, a dispersion of the unsaturated carboxylic acid-modified polyolefin resin (A) in which the unsaturated carboxylic acid-modified polyolefin resin (A) is dispersed in an aqueous solvent (the aqueous solvent mentioned in the above surface modification composition)).

[0158] The acid value of the unsaturated carboxylic acid-modified polyolefin resin (A) is, for example, 20 mg KOH / g to 100 mg KOH / g, preferably 30 mg KOH / g to 80 mg KOH / g, and more preferably 50 mg KOH / g to 70 mg KOH / g.

[0159] The acid value of the unsaturated carboxylic acid-modified polyolefin resin (A) can be derived by calculating the amount of potassium hydroxide (in mg) required to neutralize the acid groups contained in 1 g of the solid content of the unsaturated carboxylic acid-modified polyolefin resin, based on the charging ratio of the polymerization component and the neutralizing agent.

[0160] The content of the unsaturated carboxylic acid-modified polyolefin resin (A) is, for example, 50% to 99% by mass, preferably 80% to 98% by mass, relative to the total amount of the unsaturated carboxylic acid-modified polyolefin resin (A), the epoxy compound (B), and the silane coupling agent (C) described later.

[0161] [Epoxy compound (B)] The epoxy compound (B) is a crosslinking agent for crosslinking the unsaturated carboxylic acid-modified polyolefin resin (A).

[0162] From the viewpoint of improving adhesion, the epoxy compound (B) preferably has two or more epoxy groups (b1), a heteroatom other than the oxygen atom contained in the epoxy group (b2), a single cyclic hydrocarbon group (b3), and / or a tetrasubstituted carbon group (b4) in one molecule.

[0163] In other words, epoxy compound (B) has two or more epoxy groups (b1) in one molecule. The number of epoxy groups (b1) is 2 or more, preferably 3 or more, more preferably 4 or more, and for example, 8 or less, preferably 6 or less, per molecule of epoxy compound (B).

[0164] The number of epoxy groups (b1) in one molecule of epoxy compound (B) is preferably four. That is, one molecule of epoxy compound (B) preferably has four epoxy groups (b1).

[0165] Furthermore, epoxy compound (B) has a heteroatom (b2) other than the oxygen atom contained in the epoxy group. That is, one molecule of epoxy compound (B) has an oxygen atom (O) contained in the epoxy group as a heteroatom, and also has a heteroatom (b2) in addition to the oxygen atom (O) contained in the epoxy group. Hereinafter, the heteroatom (b2) other than the oxygen atom contained in the epoxy group may be simply referred to as heteroatom (b2).

[0166] Examples of heteroatoms (b2) include nitrogen atoms (N), oxygen atoms (O), sulfur atoms (S), and phosphorus atoms (P). These can be used individually or in combination of two or more. From the viewpoint of adhesive strength and resistance to contents, nitrogen atoms (N) and oxygen atoms (O) are preferred as heteroatoms (b2), and nitrogen atoms (N) are more preferred.

[0167] The number of heteroatoms (b2) is not particularly limited, but for one molecule of epoxy compound (B), it is, for example, 1 to 8, preferably 2 to 6, and more preferably 2 to 4.

[0168] The number of heteroatoms (b2) is particularly preferably 2 per molecule of epoxy compound (B). That is, one molecule of epoxy compound (B) particularly preferably has 2 heteroatoms (b2).

[0169] Furthermore, epoxy compound (B) has a single cyclic hydrocarbon group (b3) and / or a tetrasubstituted carbon group (b4). That is, epoxy compound (B) has the above epoxy group (b1) and a heteroatom (b2), and also has a cyclic hydrocarbon group (b3) and / or a tetrasubstituted carbon group (b4).

[0170] Examples of cyclic hydrocarbon groups (b3) include aromatic and alicyclic groups.

[0171] Examples of aromatic rings include aromatic monocyclic and aromatic polycyclic rings with 6 to 24 carbon atoms. Specifically, these include benzene rings, naphthalene rings, indene rings, azulene rings, fluorene rings, anthracene rings, and phenanthrene rings. Aromatic polycyclic rings are fused rings of multiple aromatic rings. In other words, the entire fused ring forms a single aromatic ring.

[0172] Examples of alicyclic rings include monocyclic and polycyclic alicyclic rings with 3 to 24 carbon atoms. Specifically, these include cyclopropane rings, cyclobutane rings, cyclopentane rings, cyclohexane rings, cyclooctane rings, cyclodecane rings, hydrogenated naphthalene rings, hydrogenated indene rings, hydrogenated azulene rings, hydrogenated fluorene rings, hydrogenated anthracene rings, and hydrogenated phenanthrene rings. Note that polycyclic alicyclic rings are fused rings of multiple alicyclic rings. In other words, the entire fused ring forms a single alicyclic ring.

[0173] Preferably, the cyclic hydrocarbon group (b3) is an aromatic monocycle having 6 to 10 carbon atoms, and an alicyclic monocycle having 3 to 12 carbon atoms. More preferably, the cyclic hydrocarbon group (b3) is a benzene ring and a cyclohexane ring. Even more preferably, the cyclic hydrocarbon group (b3) is a benzene ring.

[0174] The cyclic hydrocarbon group (b3) can be used alone or in combination of two or more types.

[0175] If the epoxy compound (B) has a cyclic hydrocarbon group (b3), the number of cyclic hydrocarbon groups (b3) is one per molecule of epoxy compound (B) from the viewpoint of adhesive strength and resistance to contents. In other words, the epoxy compound (B) preferably does not have two or more cyclic hydrocarbon groups (b3).

[0176] A tetrasubstituted carbon group (b4) is, for example, a quaternary carbon group. That is, a tetrasubstituted carbon group (b4) is formed when four substituents other than the hydrogen atom are each single-bonded to one of the four bonds of the carbon atom. The four substituents single-bonded to the carbon atom may be of the same type or may be of different types.

[0177] When epoxy compound (B) has tetrasubstituted carbon groups (b4), the number of tetrasubstituted carbon groups (b4) is, for example, one or more per molecule of epoxy compound (B). Furthermore, from the viewpoint of adhesive strength and resistance to contents, the number of tetrasubstituted carbon groups (b4) is, for example, four or less, preferably three or less, and more preferably two or less per molecule of epoxy compound (B). When epoxy compound (B) has tetrasubstituted carbon groups (b4), the number of tetrasubstituted carbon groups (b4) is particularly preferably one.

[0178] A single molecule of epoxy compound (B) may have both a cyclic hydrocarbon group (b3) and a tetrasubstituted carbon group (b4), or it may have only one of them. Preferably, a single molecule of epoxy compound (B) has only one of the cyclic hydrocarbon group (b3) and the tetrasubstituted carbon group (b4).

[0179] Preferably, epoxy compounds (B) include epoxy compounds having two or more epoxy groups (b1), heteroatoms other than oxygen atoms contained in the epoxy groups (b2), and a single cyclic hydrocarbon group (b3), but without a tetrasubstituted carbon group (b4).

[0180] More specifically, examples of such epoxy compounds (B) include N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N-[2-methyl-4-(oxyranylmethoxy)phenyl]-N-oxyranylmethyloxiranmethaneamine, and resorcinol glycidyl ether.

[0181] Furthermore, N,N,N',N'-tetraglycidyl-m-xylylenediamine has four epoxy groups, and in addition to the oxygen atoms of these epoxy groups, it has two nitrogen atoms and one benzene ring.

[0182] Furthermore, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane has four epoxy groups, two nitrogen atoms in addition to the oxygen atoms of the epoxy groups, and one cyclohexane ring.

[0183] Furthermore, N-[2-methyl-4-(oxyranylmethoxy)phenyl]-N-oxyranylmethyloxiranmethaneamine has three epoxy groups, one nitrogen atom in addition to the oxygen atoms of the epoxy groups, one oxygen atom in addition to the oxygen atoms of the epoxy groups, and one benzene ring.

[0184] Furthermore, resorcinol glycidyl ether has two epoxy groups, two oxygen atoms in addition to the oxygen atoms on those epoxy groups, and one benzene ring.

[0185] Preferably, the epoxy compound (B) is N,N,N',N'-tetraglycidyl-m-xylylenediamine.

[0186] Epoxy compound (B) can be used alone or in combination of two or more types.

[0187] Furthermore, the equivalent ratio of epoxy groups of the epoxy compound to carboxyl groups of the unsaturated carboxylic acid-modified polyolefin resin (epoxy group / carboxyl group) is greater than 0, preferably 0.1 or more, and 1.0 or less, preferably 0.8 or less, more preferably 0.5 or less, and even more preferably 0.3 or less.

[0188] When the above equivalent ratio (epoxy group / carboxyl group) exceeds the above lower limit, adhesion can be improved.

[0189] On the other hand, if the above equivalent ratio (epoxy group / carboxyl group) is below the above lower limit, the adhesion will decrease.

[0190] Furthermore, if the above equivalent ratio (epoxy group / carboxyl group) is below the above upper limit, adhesion and resistance to contents can be improved.

[0191] On the other hand, if the above equivalent ratio (epoxy group / carboxyl group) exceeds the above upper limit, adhesion and resistance to contents will decrease.

[0192] The content of epoxy compound (B) is, for example, 0.01 to 10 parts by mass, preferably 0.1 to 5.0 parts by mass, per 100 parts by mass of unsaturated carboxylic acid-modified polyolefin resin (A).

[0193] More specifically, the content ratio of epoxy compound (B) is, from the viewpoint of improving adhesion and content resistance, for example, 0.01 parts by mass or more, preferably 0.1 parts by mass or more, and from the viewpoint of improving content resistance, for example, 10 parts by mass or less, preferably 5.0 parts by mass or less, per 100 parts by mass of unsaturated carboxylic acid-modified polyolefin resin (A).

[0194] Furthermore, the content of epoxy compound (B) is, for example, 0.01% to 10% by mass, preferably 0.1% to 5.0% by mass, relative to the total amount of unsaturated carboxylic acid-modified polyolefin resin (A), epoxy compound (B), and silane coupling agent (C) described later.

[0195] More specifically, the content of epoxy compound (B) is, from the viewpoint of improving adhesion and resistance to contents, for example, 0.01% by mass or more, preferably 0.1% by mass or more, relative to the total amount of unsaturated carboxylic acid-modified polyolefin resin (A), epoxy compound (B), and silane coupling agent (C) described later, and from the viewpoint of improving resistance to contents, for example, 10% by mass or less, preferably 5.0% by mass or less.

[0196] [Silane coupling agent (C)] The adhesive composition may contain a silane coupling agent (C) as needed, from the viewpoint of improving adhesion and resistance to contents.

[0197] Examples of silane coupling agents (C) include epoxysilane, aminosilane, chlorosilane, vinylsilane, and isocyanatosilane.

[0198] Examples of epoxysilanes include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0199] Examples of aminosilanes include N-2-(aminoethyl)-3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane.

[0200] Examples of chlorosilanes include vinyltrichlorosilane. Examples of vinylsilanes include vinyltriethoxysilane.

[0201] An example of an isocyanatosilane is 3-isocyanatopropyltrimethoxysilane.

[0202] Silane coupling agents (C) can be used alone or in combination of two or more types.

[0203] The content of the silane coupling agent (C) is, for example, 0.001% to 20% by mass, preferably 0.005% to 15% by mass, relative to the total amount of the unsaturated carboxylic acid-modified polyolefin resin (A), epoxy compound (B), and silane coupling agent (C).

[0204] [Additives] The adhesive composition may contain additives in appropriate proportions as needed.

[0205] Examples of additives include crosslinking agents (excluding epoxy compound (B) above), adhesion aids, viscosity reducers (viscosity modifiers), sizing agents, antistatic agents, lubricants, smoothing agents, defoaming agents, thickeners (viscosity modifiers), tackifiers, hardening agents, preservatives, antifreeze agents, dispersants, pigments, and dyes.

[0206] Additives can be used individually or in combination of two or more types.

[0207] [Preparation of adhesive composition] The adhesive composition is prepared by mixing an unsaturated carboxylic acid-modified polyolefin resin (A) (a dispersion of the unsaturated carboxylic acid-modified polyolefin resin (A)), an epoxy compound (B), a silane coupling agent (C) which may be added as needed, and additives which may be added as needed. Preferably, the adhesive composition is prepared by diluting the mixture with the aqueous solvent mentioned above, and obtaining a dispersion in which the unsaturated carboxylic acid-modified polyolefin resin (A), the epoxy compound (B), and the silane coupling agent (C) which may be added as needed are dispersed.

[0208] The solid content concentration of the dispersion of the adhesive composition is, for example, 1% to 40% by mass.

[0209] As will be explained in more detail later, the adhesive layer 4 is obtained by applying an adhesive composition (specifically, a dispersion of the adhesive composition) to one side in the thickness direction of the surface modification layer 3 and drying it. In other words, the adhesive layer 4 is a coated object of the adhesive composition.

[0210] The thickness of the adhesive layer 4 is, for example, 0.5 μm to 10.0 μm, preferably 1.5 μm to 5.0 μm.

[0211] Furthermore, the ratio of the thickness of the adhesive layer 4 to the thickness of the surface modification layer 3 (thickness of adhesive layer 4 / thickness of surface modification layer 3) is, for example, 2 to 350, preferably 10 to 250, more preferably 15 to 200, even more preferably 20 to 150, and particularly preferably 25 to 100.

[0212] More specifically, the ratio of the thickness of the adhesive layer 4 to the thickness of the surface modification layer 3 is, from the viewpoint of improving the appearance of the adhesive layer 4 when the adhesive layer 4 is placed (applied) and improving the initial adhesion strength, for example, 2 or more, preferably 10 or more, more preferably 15 or more, even more preferably 20 or more, and particularly preferably 25 or more. Furthermore, from the viewpoint of adhesion between the surface modification layer 3 and the adhesive layer 4, it is, for example, 350 or less, preferably 250 or less, more preferably 200 or less, even more preferably 150 or less, and particularly preferably 100 or less.

[0213] [Base material layer] The material of the base layer 5 is not particularly limited. Examples of materials for the base layer 5 include resin materials (such as the resin materials listed in the support layer 10) and metals (such as the metals listed in the inorganic layer 11). Preferably, the material for the base layer 5 is a resin material. More preferably, the material for the base layer 5 is an olefin resin.

[0214] When the material of the base layer 5 is an olefin resin, the base layer 5 can specifically be a polyethylene film or a polypropylene film. Examples of polyethylene films include low-density polyethylene film (LDPE) and linear low-density polyethylene film (LLDPE). Examples of polypropylene films include stretched polypropylene film (CPP film), uniaxially oriented polypropylene film, and biaxially oriented polypropylene film (OPP film). A polyethylene film is preferred as the base layer 5. More preferably, a linear low-density polyethylene film (LLDPE) is preferred as the base layer 5.

[0215] The thickness of the substrate layer 5 is, for example, 1 μm to 1000 μm, preferably 5 μm to 500 μm, and more preferably 10 μm to 150 μm.

[0216] <Method for manufacturing laminates>

[0217] The manufacturing method of the laminate will be explained with reference to Figures 2A to 2D.

[0218] The method for manufacturing the laminate comprises a first step of preparing a barrier layer 2, a second step of applying a surface modification composition to one side of the barrier layer 2 in the thickness direction and drying it to form a surface modification layer 3, a third step of applying an adhesive composition to one side of the surface modification layer 3 in the thickness direction and drying it to form an adhesive layer 4, and a fourth step of placing a base layer 5 on one side of the adhesive layer 4 in the thickness direction.

[0219] [1st step] In the first step, the barrier layer 2 is prepared as shown in Figure 2A.

[0220] [Second process] In the second step, as shown in Figure 2B, a surface modification composition (a solution (or aqueous solution) of the surface modification composition, or a dispersion of the surface modification composition) is applied to one side of the barrier layer 2 in the thickness direction and dried to form the surface modification layer 3.

[0221] The coating method is not particularly limited. Examples of coating methods include dip coating, spray coating, roll coating, doctor blade coating, screen printing, bar coating, and casting.

[0222] As for the drying conditions, the drying temperature is, for example, 20°C to 200°C, preferably 40°C to 150°C. The drying time is, for example, 2 seconds to 180 seconds, preferably 5 seconds to 120 seconds. Drying is preferably carried out by circulating hot air inside the drying oven. This allows the surface modification composition on the barrier layer 2 to be dried uniformly.

[0223] This arranges a surface modification layer 3, which is a coating of the surface modification composition, on one side in the thickness direction of the barrier layer 2.

[0224] [3rd step] In the third step, as shown in Figure 2C, an adhesive composition (a dispersion of the adhesive composition) is applied to one side in the thickness direction of the surface modification layer 3 and dried to form the adhesive layer 4.

[0225] The application method is not particularly limited. An example of an application method is the same as the application method described in the second step above.

[0226] As for the drying conditions, the drying temperature is, for example, 20°C to 200°C, preferably 40°C to 150°C. The drying time is, for example, 2 seconds to 180 seconds, preferably 5 seconds to 120 seconds.

[0227] This places an adhesive layer 4, which is a coating of the adhesive composition, on one side in the thickness direction of the surface modification layer 3.

[0228] [4th step] In the fourth step, as shown in Figure 2D, the substrate layer 5 is placed (dry laminated) on one side in the thickness direction of the adhesive layer 4.

[0229] The dry lamination conditions are not particularly limited. As dry lamination conditions, the lamination temperature is, for example, 30°C to 200°C, preferably 40°C to 150°C, and more preferably 50°C to 100°C. The lamination pressure (gauge pressure) is, for example, 0.1 MPa to 5.0 MPa, preferably 0.2 MPa to 3.0 MPa. The lamination speed is, for example, 1 m / min to 200 m / min, preferably 10 m / min to 180 m / min, and more preferably 50 m / min to 150 m / min.

[0230] Afterward, aging is performed as necessary. As for the aging conditions, the aging temperature is, for example, 20°C to 90°C, preferably 40°C to 79°C. The aging time is, for example, 1 to 14 days, preferably 3 to 7 days.

[0231] This is used to manufacture the laminate 1.

[0232] Furthermore, the laminate 1 exhibits excellent adhesion and resistance to contents. Therefore, the laminate 1 is suitable for use as a packaging material. Note that resistance to contents specifically refers to the laminate 1's resistance to its contents (e.g., solvents).

[0233] 2. Packaging materials The packaging material comprises a laminate 1. Therefore, it exhibits excellent adhesion and resistance to contents. Such packaging materials are suitably used, for example, in the fields of food packaging and pharmaceutical packaging.

[0234] 3. Effects In laminate 1, the equivalent ratio (epoxy group / carboxyl group) of the epoxy compound to the carboxyl groups of the unsaturated carboxylic acid-modified polyolefin resin is greater than 0 and less than or equal to 1.0. Therefore, adhesion and resistance to contents can be improved.

[0235] More specifically, the epoxy groups of the epoxy compound in the adhesive composition react with the carboxyl groups of the acid-modified polyolefin resin in the adhesive composition. This improves the strength of the adhesive layer 4 and enhances adhesion.

[0236] On the other hand, it is presumed that the epoxy groups of the epoxy compound in the adhesive composition also react with the (meth)acrylic resin (a (meth)acrylic resin having a carboxyl group) in the surface modification composition. This is presumed to improve adhesion.

[0237] Furthermore, in laminate 1, the lower limit of the equivalent ratio (epoxy group / carboxyl group) is adjusted to be greater than 0. This allows for improved adhesion through the above reaction.

[0238] On the other hand, it is presumed that adhesion is also improved by the interaction between the carboxyl groups of the (meth)acrylic resin in the surface modification composition and the carboxyl groups of the acid-modified polyolefin resin in the adhesive composition. Therefore, in laminate 1, the upper limit of the equivalent ratio (epoxy group / carboxyl group) is adjusted to 1 or less so that not all of the carboxyl groups of the (meth)acrylic resin in the surface modification composition and the carboxyl groups of the acid-modified polyolefin resin in the adhesive composition react with the epoxy groups, and some unreacted carboxyl groups remain. This allows for improved adhesion through the above interaction.

[0239] Based on the above, the laminate 1 improves adhesion by adjusting the equivalent ratio (epoxy group / carboxyl group) to a predetermined range, thereby adjusting the reaction between the epoxy group of the epoxy compound in the adhesive composition and the carboxyl group of the acid-modified polyolefin resin in the adhesive composition, the reaction between the epoxy group of the epoxy compound in the adhesive composition and the carboxyl group of the (meth)acrylic resin in the surface modification composition, and the interaction between the carboxyl group of the (meth)acrylic resin in the surface modification composition and the carboxyl group of the acid-modified polyolefin resin in the adhesive composition.

[0240] Furthermore, in laminate 1, since the equivalent ratio (epoxy group / carboxyl group) is 1 or less, the resistance to contents can be improved from the viewpoint of the interaction between the carboxyl groups of the (meth)acrylic resin in the surface modification composition and the carboxyl groups of the acid-modified polyolefin resin in the adhesive composition.

[0241] Furthermore, as described above, the material of the base layer 5 is preferably an olefin resin. In other words, the base layer 5 is preferably an olefin film. Specifically, the laminate 1 is preferably manufactured by bonding the inorganic layer 11 (high polarity material) in the barrier layer 2 to an olefin film (low polarity material).

[0242] In such cases, at the interface between the barrier layer 2 and the surface modification layer 3, the interaction between the inorganic material in the inorganic layer 11 of the barrier layer 2 and the metal compound in the surface modification layer 3 can improve the adhesion between the barrier layer 2 and the surface modification layer 3.

[0243] Furthermore, at the interface between the surface modification layer 3 and the adhesive layer 4, as described above, the adhesion between the surface modification layer 3 and the adhesive layer 4 can be improved by the reaction between the epoxy groups of the epoxy compound in the adhesive composition and the carboxyl groups of the acid-modified polyolefin resin in the adhesive composition, the reaction between the epoxy groups of the epoxy compound in the adhesive composition and the carboxyl groups of the (meth)acrylic resin in the surface modification composition, and the interaction between the carboxyl groups of the (meth)acrylic resin in the surface modification composition, the metal compound and the carboxyl groups of the acid-modified polyolefin resin in the adhesive composition.

[0244] Furthermore, at the interface between the adhesive layer 4 and the substrate layer 5 (olefin film), the interaction between the acid-modified polyolefin resin and the olefin film can improve the adhesion between the adhesive layer 4 and the substrate layer 5.

[0245] 4. Variations In the modified examples, the same reference numerals are used for components and processes as in the first embodiment, and their detailed descriptions are omitted. Furthermore, the modified examples can achieve the same effects and advantages as the first embodiment, unless otherwise specified. Moreover, the first embodiment and the modified examples can be combined as appropriate.

[0246] In the above description, the barrier layer 2 comprises a support layer 10 and an inorganic layer 11 in the thickness direction, but the barrier layer 2 may also consist only of the inorganic layer 11 without the support layer 10.

[0247] In the above description, the laminate 1 includes a base layer 5, but the laminate 1 may also include a barrier layer 2, a surface modification layer 3, and an adhesive layer 4 without the base layer 5.

[0248] In the above description, the laminate 1 is manufactured by dry lamination, but the laminate 1 can also be manufactured by known extrusion lamination. [Examples]

[0249] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. Unless otherwise specified, "parts" and "%" are based on mass. Furthermore, specific numerical values ​​such as blending ratios (content), physical properties, and parameters used in the following description may be replaced with the corresponding upper limits (numerical values ​​defined as "less than or equal to" or "less than") or lower limits (numerical values ​​defined as "greater than or equal to" or "greater than") of the blending ratios (content), physical properties, and parameters described in the "Modes for Carrying Out the Invention" above.

[0250] <Details of ingredients> Acrylic resin 2: Polyacrylic acid, Jurimer AC-10L (manufactured by Toagosei), weight-average molecular weight 50000, acid value 780 mgKOH / g Unsaturated carboxylic acid-modified polyolefin resin 1: Ethylene 80.2% by mass, ethyl acrylate 17% by mass, maleic anhydride 2.8% by mass Unsaturated carboxylic acid-modified polyolefin resin 2: Ethylene 75% by mass, ethyl acrylate 17% by mass, maleic anhydride 8% by mass Unsaturated carboxylic acid-modified polyolefin resin 3: Ethylene 80% by mass, Isobutyl acrylate 10% by mass, Methacrylic acid 10% by mass Sc1:3-Glycidoxypropyltrimethoxysilane, trade name KBM-403, manufactured by Shin-Etsu Silicone Co., Ltd. Sol1: Isopropyl alcohol / water mixture (1 / 1) Ep1: N,N,N',N'-tetraglycidyl-m-xylylenediamine, trade name TetradX, manufactured by Mitsubishi Gas Chemical Company, epoxy equivalent 98 g / mol PET; polyethylene terephthalate film, product name "Ester Film E5102", thickness 12 μm, manufactured by Toyobo Co., Ltd. Al: Aluminum foil, product name "Aluminum Foil 1N30", thickness 9μm, manufactured by UACJ Corporation.

[0251] <Preparation of surface modification composition> (Synthesis of (meth)acrylic resin) Synthesis Example 1 (Synthesis of Acrylic Resin 1) 95.13 parts by mass of deionized water were placed in a four-necked vessel equipped with a heating and stirring device, and the contents were heated to 80°C while stirring and refluxing nitrogen. Then, while continuing heating, stirring, and refluxing nitrogen, polymerization components (2.48 parts by mass of acrylic acid and 2.33 parts by mass of 2-hydroxyethyl methacrylate), polymerization initiator (4,4'-azobis(4-cyanovaleric acid) (ACVA)), and 0.02 parts by mass of 25% aqueous ammonia were added dropwise over 3 hours. After that, heating, stirring, and refluxing nitrogen were carried out for 2 hours. After that, heating and refluxing nitrogen were stopped, and the mixture was cooled to 30°C while stirring, neutralized with 25% aqueous ammonia, and filtered through a 200-mesh comb. This yielded acrylic resin 1 (acid value 401 mg KOH / g, colorless, transparent, water-soluble acrylic resin).

[0252] (Preparation of surface modification composition) Manufacturing Examples 1-3 As described in Table 1, (meth)acrylic resin, metal compound, and antioxidant (if necessary) were mixed and prepared with ion-exchanged water and isopropyl alcohol at room temperature to a concentration of 100% by mass. This obtained a solution of the surface modification composition. In Table 1, the values ​​for (meth)acrylic resin, metal compound, and antioxidant represent parts by mass in the solution of the surface modification composition.

[0253] (Preparation of unsaturated carboxylic acid-modified polyolefin resins) Manufacturing Example 4 Unsaturated carboxylic acid-modified polyolefin resin 1, a neutralizing agent, and a diluent (a mixed solvent of n-propyl alcohol and water) were placed in a pressure-resistant stirring vessel with a heating function (autoclave (capacity 1.5 L)). The vessel was then sealed, and the contents were mixed at a rotation speed of 800 rpm and 145°C (dispersion temperature) for 4 hours. After that, the vessel was air-cooled to room temperature, and the contents were removed. This yielded a dispersion of the unsaturated carboxylic acid-modified polyolefin resin.

[0254] Manufacturing Example 5 A dispersion of unsaturated carboxylic acid-modified polyolefin resin was obtained based on the same procedure as in Production Example 4. However, unsaturated carboxylic acid-modified polyolefin resin 1 was replaced with unsaturated carboxylic acid-modified polyolefin resin 2. The dispersion temperature was also changed to 130°C. Furthermore, the formulation was modified according to Table 2.

[0255] Manufacturing Example 6 A dispersion of unsaturated carboxylic acid-modified polyolefin resin was obtained based on the same procedure as in Production Example 4. However, unsaturated carboxylic acid-modified polyolefin resin 1 was replaced with unsaturated carboxylic acid-modified polyolefin resin 3. The dispersion temperature was also changed to 130°C. Furthermore, the formulation was modified according to Table 2.

[0256] <Manufacturing of laminates> Example 1 [1st step] A barrier layer was prepared. Specifically, polyethylene terephthalate film (PET) and aluminum foil (AL) were laminated using a commercially available adhesive (main component Takelac A-626 (manufactured by Mitsui Chemicals) / hardener Takenate A-50 (manufactured by Mitsui Chemicals)), and then aged. The amount of adhesive applied was 3.3 g / m² based on solid content. 2 The aging conditions were 40°C for 3 days. This prepared the barrier layer.

[0257] [Second process] The surface modification composition from Production Example 1 was applied to one side of the barrier layer in the thickness direction by a bar coater method, and the surface modification layer was formed by drying it in a hot air oven at 80°C for 6 seconds.

[0258] [3rd step] An adhesive layer was formed by applying an adhesive composition to one side in the thickness direction of the surface modification layer and allowing it to dry.

[0259] Specifically, first, an adhesive composition was prepared. In detail, a dispersion of the adhesive composition was prepared by mixing an unsaturated carboxylic acid-modified polyolefin resin, an epoxy compound, Sc1, and Sol1 according to the formulation described in Table 3. The proportion of the silane coupling agent was 1 part by mass relative to the unsaturated carboxylic acid-modified polyolefin resin.

[0260] Then, a dispersion of the adhesive composition was applied to one side in the thickness direction of the surface modification layer using a bar coater method and dried in an oven (90°C, 90 seconds). This resulted in the formation of an adhesive layer on one side in the thickness direction of the surface modification layer.

[0261] [4th step] A heated pressure roll (80°C, gauge pressure 0.4 MPa) was used to bond one side of the adhesive layer in the thickness direction to the substrate layer (LLDPE). This positioned one side of the adhesive layer in the thickness direction and the substrate layer. A laminate was then manufactured.

[0262] Examples 2 to 15 and Comparative Examples 1 to 3 The laminate was manufactured using the same procedure as in Example 1, except that the formulation was modified according to Tables 3 and 4.

[0263] <Rating> (Acid value) The acid value of acrylic resin 1 and acrylic resin 2 (solid content of resin 2) was calculated by determining the amount of potassium hydroxide (in mg) required to neutralize the acid groups contained in 1 g of the solid content of the acrylic resin, based on the mixing ratio of polymerization components and neutralizing agents. The results are shown in Table 1.

[0264] Furthermore, the acid value of the unsaturated carboxylic acid-modified polyolefin resins in Production Examples 4 to 6 was determined by calculating the amount of potassium hydroxide (in mg) required to neutralize the acid groups contained in 1 g of the solid content of the unsaturated carboxylic acid-modified polyolefin resin, based on the charging ratio of the polymerization component and the neutralizing agent. The results are shown in Table 2.

[0265] Furthermore, in the third step, after placing the adhesive layer, visual inspection was performed on all examples, and no defects such as whitening were observed.

[0266] (Adhesion) The laminates of each example and comparative example were cut into 150 mm long x 15 mm wide sections to obtain samples. The peel strength was then measured using a T-type peel test with a universal tensile strength measuring device (crosshead speed 300 mm / min, 24°C). The results are shown in Tables 3 and 4.

[0267] The peeling strength was measured in the region where the peeling behavior of each sample was flat. In cases where the peeling behavior of each sample was not flat and was pulsed, the maximum and minimum values ​​were measured (the same applies below).

[0268] (Resistance to contents) The laminates of each example and comparative example were cut to 150 mm in length and 100 mm in width to obtain samples. Next, the samples were folded in half and both ends were heat-sealed. This created three-sided pouches (75 mm x 100 mm). The contents listed in Tables 3 and 4 were then sealed in the three-sided pouches and stored at 50°C for one week. After that, the three-sided pouches were opened and the samples were washed with water. Subsequently, the peel strength after the content resistance test was measured using a T-type peel test with a universal tensile strength measuring device (crosshead speed 300 mm / min, 24°C).

[0269] The contents are as follows: Acetic acid: 10g of acetic acid Hydrochloric acid: 10% by mass hydrochloric acid, 10g Diethanolamine: 10 g 10% by mass aqueous ammonia: 10 g 80% by mass ethanol: 10 g Limonene: 10 g

[0270] Also, the appearance of the sample before peeling after enclosing the contents and storing was observed and evaluated based on the following criteria. The results are shown in Tables 3 and 4. {Criteria} A: There was no change compared to before enclosing the contents. B: Vacuoles were confirmed. C: Delamination was confirmed.

[0271] In Tables 3 and 4, the abbreviations for the peeling states are as follows. ad / LL: Interfacial peeling between the adhesive layer and the base material layer (LLDPE) LL elongation: The base material layer (LLDPE) elongated. ad aggregation: Cohesive failure of the adhesive layer AL / ad: Interfacial peeling between the barrier layer (AL) and the adhesive layer (interfacial peeling between the surface-modified layer and the adhesive layer) Treatment agent material break: Cohesive failure of the surface-modified layer ad separation: A state where ad / LL and AL / ad are mixed

[0272]

Table 1

[0273]

Table 2

[0274]

Table 3

[0275]

Table 4

Explanation of Symbols

[0276] 1. Laminate 2. Barrier layer 3. Surface modification layer 4 Adhesive layer 5 Base material layer 11 Inorganic layer

Claims

1. Barrier layer, A surface modification layer is disposed on one side in the thickness direction of the barrier layer, The surface modified layer comprises an adhesive layer disposed on one side in the thickness direction of the surface modified layer, The barrier layer comprises an inorganic layer containing inorganic material, The inorganic layer is in contact with the surface modification layer, The aforementioned surface modification layer is a coating of a surface modification composition, The surface modification composition comprises a metal compound and a (meth)acrylic resin. The (meth)acrylic resin has a carboxyl group, The adhesive layer is a coating of the adhesive composition, The adhesive composition comprises an unsaturated carboxylic acid-modified polyolefin resin and an epoxy compound. A laminate in which the equivalent ratio of epoxy groups of the epoxy compound to carboxyl groups of the unsaturated carboxylic acid-modified polyolefin resin is greater than 0 and 1.0 or less.

2. The laminate according to claim 1, wherein the epoxy compound has two or more epoxy groups, heteroatoms other than oxygen atoms contained in the epoxy groups, a single cyclic hydrocarbon group, and / or a tetrasubstituted carbon group in one molecule.

3. The aforementioned unsaturated carboxylic acid-modified polyolefin resin is a polymer of raw material monomer components, The raw material monomer component comprises an olefin and an unsaturated carboxylic acid. The laminate according to claim 1, wherein the content of the constituent units derived from the unsaturated carboxylic acid is 2% by mass or more and 10% by mass or less with respect to the unsaturated carboxylic acid-modified polyolefin resin.

4. The laminate according to claim 1, wherein the adhesive composition comprises a silane coupling agent.

5. The metal compound is a zirconium compound, and the mass ratio of zirconium in the zirconium compound to the (meth)acrylic resin (zirconium / (meth)acrylic resin) is 0.30 or more and 4.00 or less, or The laminate according to claim 1, wherein the metal compound is a trivalent chromium compound, and the mass ratio of trivalent chromium in the trivalent chromium compound to the (meth)acrylic resin (trivalent chromium / (meth)acrylic resin) is 0.15 or more and 0.50 or less.

6. The laminate according to claim 1, wherein the acid value of the (meth)acrylic resin is 150 mg KOH / g or more and 780 mg KOH / g or less.

7. The ratio of the thickness of the adhesive layer to the thickness of the surface modification layer is 2 or more and 350 or less. The laminate according to claim 1.

8. The laminate according to claim 1, further comprising a base material layer disposed on one side in the thickness direction of the adhesive layer.

9. A packaging material comprising a laminate according to any one of claims 1 to 8.

10. The first step is to prepare the barrier layer, A second step involves applying a surface modification composition to one side of the barrier layer in the thickness direction and drying it to form a surface modification layer. The process includes a third step of applying an adhesive composition to one side in the thickness direction of the surface modification layer and drying it to form an adhesive layer. The barrier layer comprises an inorganic layer containing inorganic material, The inorganic layer is in contact with the surface modification layer, The surface modification composition comprises a metal compound and a (meth)acrylic resin. The (meth)acrylic resin has a carboxyl group, The adhesive composition comprises an unsaturated carboxylic acid-modified polyolefin resin and an epoxy compound. A method for producing a laminate, wherein the equivalent ratio of epoxy groups of the epoxy compound to carboxyl groups of the unsaturated carboxylic acid-modified polyolefin resin is greater than 0 and 1.0 or less.

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