Laminate, recycled plastic and production method thereof

Abstract

To provide a laminate with which quality of a recycled plastic is not lowered and interlaminar adhesive strength etc. are maintained.SOLUTION: A laminate comprises a first base material film, a second base material film, and an adhesive layer placed between them. The first and second base material films are formed of a thermoplastic resin of which the main component is an olefin-based resin, and the adhesive layer is formed of adhesives satisfying (1), (2) or (3). (1) A polypropylene-based resin modified with maleic acid anhydride of which the content of polypropylene is 70-99 mol% and the modification rate of maleic acid anhydride is 0.1 mol% or more. (2) A polyethylene-based resin modified with maleic acid anhydride of which the content of polyethylene is 70-99 mol% and the modification rate of maleic acid anhydride is 0.1 mol% or more. (3) A polyethylene-based resin modified with vinyl acetate of which the modification rate of vinyl acetate is 5-20 mol% or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a laminate excellent in recyclability and recycled plastic using the same.

Background Art

[0002] Conventionally, laminated films manufactured by a lamination method using an adhesive have been developed and evolved to meet the demand for achieving various high functions such as barrier properties, moisture resistance, and retort resistance with a single packaging material, not only for simple packaging purposes. (See, for example, Patent Document 1). However, in recent years, there have been voices saying that these laminated films of different resin types deteriorate the quality of recycled plastics, and it is desired that they be not only highly functional but also recyclable packaging materials.

[0003] Laminated films of the same resin type are expected as recyclable packaging materials. As laminated films of the same resin type, for example, packaging materials composed only of olefin resins (also referred to as monomaterials) are already known. (See, for example, Patent Document 2). However, many of these are manufactured by a coextrusion method in which all the constituent films are melted and laminated in a desired order in a molten state by a method such as a melt coextrusion multilayer die method or a feed block method and then formed into a film shape. This requires a large-scale manufacturing apparatus, and there may be limitations in interlayer adhesion strength and the like compared to a laminate using an adhesive.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a laminate or a packaging material that does not reduce the quality of recycled plastic, is easy to manufacture, and can maintain functionality such as interlayer adhesion strength.

Means for Solving the Problems

[0006] That is, the present invention includes a first base film, a second base film, and an adhesive layer disposed between the first base film and the second base film, wherein the first and second base films are made of a thermoplastic resin mainly composed of an olefin resin, and the adhesive layer is composed of an adhesive satisfying any one of (1), (2), or (3), and provides a laminate. (1) A polypropylene resin modified with maleic anhydride, having a polypropylene content of 70 to 99 mol% and a modification rate of maleic anhydride of 0.1 mol% or more. (2) A polyethylene resin modified with maleic anhydride, having a polyethylene content of 70 to 99 mol% and a modification rate of maleic anhydride of 0.1 mol% or more. (3) A polyethylene resin modified with vinyl acetate, having a modification rate of vinyl acetate of 5 to 20 mol% or more.

[0007] The present invention also provides recycled plastic using the laminate described above as a raw material.

[0008] The present invention also provides a method for producing recycled plastic using the laminate described above as a raw material, the method including a step of crushing the laminate according to claim 1, a step of immersing the laminate in a peeling liquid to separate the laminate into layers, a step of recovering the separated layers, a step of melt-kneading the recovered crushed pieces, and a step of pelletizing the melt-kneaded kneaded product.

Effects of the Invention

[0009] According to the present invention, it is possible to provide a laminate or a packaging material that does not reduce the quality of recycled plastic, is easy to manufacture, and can maintain functionality such as interlayer adhesion strength.

Mode for Carrying Out the Invention

[0010] (First base film) The first base film used in the present invention can be used without particular limitation as long as it is a film made of a thermoplastic resin mainly composed of an olefin resin (which may sometimes be referred to as a sheet, but in the present invention, it is referred to as a film. Note that the first base material may also be referred to as film (1)). Specific examples of the olefin resin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear (linear) low-density polyethylene, polypropylene, ethylene-propylene copolymer, α-olefin polymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, cyclic olefin resin, ionomer resin, olefin resins such as polymethylpentene; and modified olefin resins obtained by modifying olefin resins with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, and other unsaturated carboxylic acids.

[0011] Also, as the film base material, it is also preferable to use a film formed of a material containing a biomass-derived component. Biomass films are sold by various companies, and for example, sheets such as those listed in the list of biomass-certified products described by the Japan Organic Resources Association, a general incorporated foundation, can be used.

[0012] Specifically well-known films are made from ethylene glycol derived from biomass. Ethylene glycol derived from biomass is made from ethanol (biomass ethanol) produced from biomass as a raw material. For example, biomass-derived ethylene glycol can be obtained by a method of producing ethylene glycol via ethylene oxide from biomass ethanol by a conventionally known method or the like. Also, commercially available biomass ethylene glycol may be used, and for example, biomass ethylene glycol commercially available from Indiaglycol Co., Ltd. can be preferably used.

[0013] Alternatively, those using biomass raw materials distinguished by the biomass plastic degree defined in ISO 16620 or ASTM D6866 are also on the market. Radioactive carbon 14C exists in the atmosphere at a ratio of 1 in 1012, and this ratio does not change even in carbon dioxide in the atmosphere. Therefore, this ratio does not change even in plants that have fixed this carbon dioxide by photosynthesis. For this reason, the carbon of plant-derived resins contains radioactive carbon 14C. In contrast, the carbon of fossil fuel-derived resins contains almost no radioactive carbon 14C. Therefore, by measuring the concentration of radioactive carbon 14C in the resin with an accelerator mass spectrometer, the content ratio of plant-derived resins in the resin, that is, the biomass plastic degree can be determined. Examples of plant-derived low-density polyethylene that is a biomass plastic with a biomass plastic degree of 80% or more, preferably 90% or more, defined in ISO 16620 or ASTM D6866 include products named "SBC818", "SPB608", "SBF0323HC", "STN7006", "SEB853", "SPB681", etc. manufactured by Braskem Co., Ltd., and films using these as raw materials can be preferably used.

[0014] For example, as an alternative to polyolefin films using conventional petroleum-based raw materials, biomass polyethylene-based films containing polyethylene resins made from ethylene glycol derived from biomass, biomass polyolefin-based films such as biomass polyethylene-polypropylene-based films are also known. The polyethylene resin is not particularly limited except that a part of the raw material uses the ethylene glycol derived from the biomass, and examples include a homopolymer of ethylene, a copolymer of ethylene and an α-olefin having ethylene as a main component (ethylene-α-olefin copolymer containing 90% by mass or more of ethylene units), and the like. These can be used alone or in combination of two or more. The α-olefin constituting the copolymer of ethylene and an α-olefin is not particularly limited, and examples include α-olefins having 4 to 8 carbon atoms such as 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. Known polyethylene resins such as low-density polyethylene resin, medium-density polyethylene resin, and linear low-density polyethylene resin can be used. Among them, from the viewpoint of making it less likely to cause damage such as perforation or breakage even when the films rub against each other, linear low-density polyethylene resin (LLDPE) (a copolymer of ethylene and 1-hexene, or a copolymer of ethylene and 1-octene) is preferable, and a linear low-density polyethylene resin having a density of 0.910 to 0.925 g / cm3 is more preferable.

[0015] The biomass film may be a laminate in which a plurality of biomass films are laminated, or may be a laminate of a conventional petroleum-based film and a biomass film.

[0016] The film (1) may be subjected to some surface treatment, for example, physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, flame treatment, or chemical treatments such as oxidation treatment using chemicals, or other treatments.

[0017] The film (1) can be manufactured by a conventionally known film-forming method such as an extrusion method, a casting method, a T-die method, a cutting method, an inflation method, etc. for the above-described resin. It may be an unstretched film, or may be stretched in one or two axial directions using a tenter method, a tubular method, etc. from the viewpoints of the strength, dimensional stability, and heat resistance of the film (1).

[0018] The film (1) may contain additives as necessary. Specifically, for the purpose of improving and modifying processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slipperiness, mold release properties, flame retardancy, antifungal properties, electrical properties, strength, etc., plastic compounding agents and additives such as elastomers, lubricants, crosslinking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, etc. can be added. The addition amount of the additive is adjusted within a range that does not affect other performances and recyclability.

[0019] The film thickness of the film (1) is not particularly limited, and may be appropriately selected within the range of 0.1 to 300 μm from the viewpoints of moldability and transparency. Preferably, it is in the range of 0.3 to 100 μm. If it is less than 0.1 μm, the strength is insufficient, and if it exceeds 300 μm, the rigidity becomes too high and processing may become difficult.

[0020] The film (1) may be provided with a barrier layer as necessary for the purpose of providing barrier properties against water vapor, oxygen, alcohol, inert gas, volatile organic substances (scent), etc. Specifically, coating layers such as polyvinylidene chloride coating (K-coating), metal vapor deposition layers such as aluminum, and inorganic vapor deposition layers such as silica and alumina can be mentioned.

[0021] The film (1) may be provided with a coating layer for the purpose of improving ink receptivity when providing a printing layer described later, etc. as necessary.

[0022] (Second base film) The second base film used in the present invention can be used without particular limitation as long as it is a film (which may sometimes be referred to as a sheet, but is referred to as a film in the present invention) made of a thermoplastic resin mainly composed of an olefin resin, similar to the first base film (film (1)). For the olefin resin which is the raw material of film (2), the same ones as those of the first base material can be used, such as the type of olefin resin, the manufacturing method of film (2), the type of additive, the film thickness, etc.

[0023] The first base material, i.e., film (1), and the second base material, i.e., film (2), can be combined with exactly the same film within the above range, or different films can also be combined.

[0024] (Adhesive layer) The adhesive layer used in the present invention is characterized by being composed of an adhesive mainly composed of an olefin resin (A) modified with an acid, an acid anhydride, and / or vinyl acetate. Here, an acid-modified olefin resin which is a copolymer of an olefin monomer and an ethylenically unsaturated carboxylic acid or an ethylenically unsaturated carboxylic acid anhydride is referred to as "acid-modified olefin resin (A-1)", and an acid-modified olefin resin which is a resin obtained by graft-modifying a polyolefin with an ethylenically unsaturated carboxylic acid or an ethylenically unsaturated carboxylic acid anhydride is referred to as "acid-modified olefin resin (A-2)", and an olefin resin modified with vinyl acetate is referred to as "olefin resin having vinyl acetate (A-3)".

[0025] (Acid-modified olefin resin (A-1), acid-modified olefin resin (A-2)) Examples of the olefin resin having an acid group and / or an acid anhydride group include an acid-modified olefin resin (A-1) which is a copolymer of an olefin monomer and an ethylenically unsaturated carboxylic acid or an ethylenically unsaturated carboxylic acid anhydride, and an acid-modified olefin resin (A-2) which is a resin obtained by graft-modifying a polyolefin with an ethylenically unsaturated carboxylic acid or an ethylenically unsaturated carboxylic acid anhydride.

[0026] As the olefin monomer used for the preparation of the acid-modified olefin resin (A-1), olefins having 2 to 8 carbon atoms, such as ethylene, propylene, isobutylene, 1-butene, 4-methyl-1-pentene, hexene, vinylcyclohexane, etc. can be mentioned. Among these, olefins having 2 to 8 carbon atoms are preferred because they have particularly good adhesion strength, ethylene, propylene, and 1-butene are more preferred, and it is particularly preferable to use them in combination.

[0027] Examples of the ethylenically unsaturated carboxylic acid or ethylenically unsaturated carboxylic anhydride used for copolymerization with the olefin monomer include acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid, maleic anhydride, 4-methylcyclohexene-4-ene-1,2-dicarboxylic anhydride, bicyclo[2.2.2]oct-5-ene-2,3-dicarboxylic anhydride, 1,2,3,4,5,8,9,10-octahydronaphthalene-2,3-dicarboxylic anhydride, 2-octa-1,3-diketospiro[4.4]non-7-ene, bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride, maleopimaric acid, tetrahydrophthalic anhydride, methyl-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride, methyl-norbornene-5-ene-2,3-dicarboxylic anhydride, norbornene-5-ene-2,3-dicarboxylic anhydride, etc. Among these, maleic anhydride is preferred because it is particularly excellent in reactivity with the olefin monomer, reactivity of the acid anhydride after copolymerization, and has a small molecular weight of the compound itself and a high functional group concentration when made into a copolymer. These can be used alone or in combination of two or more.

[0028] For the preparation of the acid-modified olefin resin (A-1), in addition to the olefin monomer, ethylenically unsaturated carboxylic acid or ethylenically unsaturated carboxylic anhydride, compounds having other ethylenically unsaturated groups, such as styrene, butadiene, isoprene, etc. may be used in combination.

[0029] Examples of the polyolefin used for preparing the acid-modified olefin resin (A-2) include homopolymers and copolymers of olefins having 2 to 8 carbon atoms, and copolymers of olefins having 2 to 8 carbon atoms and other monomers. Specifically, for example, polyethylene such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene resin, polypropylene, polyisobutylene, poly(1-butene), poly(4-methyl-1-pentene), polyvinylcyclohexane, ethylene-propylene block copolymer, ethylene-propylene random copolymer, ethylene-1-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-hexene copolymer and other α-olefin copolymers, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-vinyl acetate-methyl methacrylate copolymer, propylene-1-butene copolymer, ethylene-propylene-1-butene copolymer and the like. Among these, homopolymers of olefins having 2 to 8 carbon atoms and copolymers of two or more olefins having 2 to 8 carbon atoms are preferred because of their particularly good adhesion strength, and polyethylene, polypropylene, or ethylene-propylene copolymer is particularly preferred.

[0030] Examples of the ethylenically unsaturated carboxylic acid or ethylenically unsaturated carboxylic anhydride used for graft modification with polyolefin are the same as those used for copolymerization with olefin monomers in the preparation of the acid-modified olefin resin (A-1) described above. Maleic anhydride is preferred because of its high reactivity of functional groups after graft modification and high functional group concentration of the graft-modified polyolefin. These can be used alone or in combination of two or more.

[0031] To react an ethylenically unsaturated carboxylic acid or an ethylenically unsaturated carboxylic anhydride with a polyolefin by graft modification, specifically, there are methods such as melting the polyolefin, adding the ethylenically unsaturated carboxylic acid or the ethylenically unsaturated carboxylic anhydride (graft monomer) thereto and conducting a graft reaction; dissolving the polyolefin in a solvent to form a solution, adding the ethylenically unsaturated carboxylic acid or the ethylenically unsaturated carboxylic anhydride thereto and conducting a graft reaction; mixing the polyolefin dissolved in an organic solvent with the ethylenically unsaturated carboxylic acid or the ethylenically unsaturated carboxylic anhydride, and heating at a temperature equal to or higher than the softening temperature or melting point of the polyolefin to simultaneously conduct a radical polymerization and a hydrogen abstraction reaction in a molten state, and the like.

[0032] In any case, in order to efficiently graft-copolymerize the graft monomer, it is preferable to conduct the graft reaction in the presence of a radical initiator. The graft reaction is usually carried out under the conditions of 60 to 350 °C. The usage ratio of the radical initiator is usually in the range of 0.001 to 1 part by weight with respect to 100 parts by weight of the polyolefin before modification.

[0033] As the radical initiator, an organic peroxide is preferable, for example, benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(peroxide benzoate) hexyne-3, 1,4-bis(tert-butylperoxyisopropyl) benzene, lauroyl peroxide, tert-butyl peracetate, 2,5-dimethyl-2,5-di(tert-butylperoxy) hexyne-3, 2,5-dimethyl-2,5-di(tert-butylperoxy) hexane, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl perisobutyrate, tert-butyl per-sec-octoate, tert-butyl perpivalate, cumyl perpivalate, and tert-butyl perdiaethylacetate, etc. can be mentioned. Other azo compounds, for example, azobisisobutyronitrile, dimethyl azoisobutyrate, etc. can also be used.

[0034] The radical initiator may be selected as the optimal one through the process of the graft reaction. Usually, dialkyl peroxides such as dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,4-bis(tert-butylperoxyisopropyl)benzene are preferably used.

[0035] When using an acid-modified olefin resin (A-1) or an acid-modified olefin resin (A-2) as the olefin resin (A), it is preferable to use one having an acid value of 1 to 200 mgKOH / g.

[0036] (Olefin resin (A-3) having vinyl acetate) Examples of the olefin resin (A-3) having vinyl acetate include copolymers of polyolefin and vinyl acetate. The polyolefin can be the same as that used in the preparation of the olefin resin (A-2). As the modification method, the same method as that for the preparation of the acid-modified olefin resin (A-1) can be used. The polyolefin is preferably polyethylene, polypropylene, or an ethylene-propylene copolymer in particular.

[0037] When using an olefin resin (A-3) having a hydroxyl group as the olefin resin (A), it is preferable to use one containing 5 to 20 mol% of vinyl acetate.

[0038] As the olefin resin (A), the polyolefin used for the preparation of the above-mentioned acid-modified olefin resin (A-2) or olefin resin (A-3) having vinyl acetate may be used as it is without modification.

[0039] In order to obtain good adhesiveness, the weight average molecular weight of the olefin resin (A) is preferably 40,000 or more. Also, in order to ensure appropriate fluidity, the weight average molecular weight of the olefin resin (A) is preferably 300,000 or less.

[0040] In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values measured by gel permeation chromatography (GPC) under the following conditions.

[0041] Measuring device: HLC-8320GPC manufactured by Tosoh Corporation Column: TSKgel 4000HXL, TSKgel 3000HXL, TSKgel 2000HXL, TSKgel 1000HXL manufactured by Tosoh Corporation Detector: RI (differential refractometer) Data processing: Multi-station GPC-8020 model II manufactured by Tosoh Corporation Measurement conditions: Column temperature 40°C Solvent: Tetrahydrofuran Flow rate: 0.35 ml / min Standard: Monodisperse polystyrene Sample: A 0.2 mass% tetrahydrofuran solution in terms of resin solid content, filtered through a microfilter (100 μl)

[0042] The melting point of the olefin resin (A) is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher. The melting point of the olefin resin (A) is preferably 120°C or lower, more preferably 90°C or lower, and even more preferably 85°C or lower.

[0043] The melting point of the olefin resin is measured by DSC (differential scanning calorimetry). Specifically, after heating from the temperature reached during cooling to the temperature reached during heating at a rate of 10°C / min, cooling to the temperature reached during cooling at a rate of 10°C / min to remove the thermal history, and then heating again to the temperature reached during heating at a rate of 10°C / min. The peak temperature during the second heating is taken as the melting point. Also, the temperature reached during cooling is set to a temperature 50°C or more lower than the crystallization temperature, and the temperature reached during heating is set to a temperature about 30°C or more higher than the melting point temperature. The temperature reached during cooling and the temperature reached during heating are determined by trial measurement.

[0044] Among them, (1) It is preferable that the olefin resin (A) is a polypropylene resin modified with maleic anhydride, the content of polypropylene is 70 to 99 mol%, and the modification rate of maleic anhydride is 0.1 mol% or more. Also, (2) it is preferable that the olefin resin (A) is a polyethylene resin modified with maleic anhydride, the content of polyethylene is 70 to 99 mol%, and the modification rate of maleic anhydride is 0.1 mol% or more. Also, (3) it is preferable that the olefin resin (A) is a polyethylene resin modified with vinyl acetate, and the modification rate of vinyl acetate is 5 to 20 mol% or more.

[0045] (Hardening agent (B)) The adhesive used in the present invention may use a hardening agent (B). Specifically, metal compounds and the like can be mentioned.

[0046] (Metal compound) The metal compound can be used without particular limitation as long as it forms an ionic crosslinking bond with the olefin resin (A). Specifically, it is a compound containing metal ions, and examples thereof include metal oxides, hydroxides, carbonates, bicarbonates, acetates, formates, methoxides, ethoxides, etc. Examples of metal ions include monovalent ions such as Li + , Na + , K + , Ag + , Cu + , etc., and divalent ions such as Cu 2+ , Ba 2+ , Zn 2+ , Fe 2+ , etc. These metal ions can be mixed and contained in two or more kinds as necessary.

[0047] In addition, aziridine group-containing compounds, oxazolines, amino resins, etc. can also be used. Examples of aziridine group-containing compounds include N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinylpropionate), N,N'-toluene-2,4-bis(1-aziridinecarboxamide), triethylenemelamine, trimethylolpropane-tri-β(2-methylaziridine)propionate, bisisophthaloyl-1-2-methylaziridine, tri-1-aziridinylphosphine oxide, tris-1-2-methylaziridinephosphine oxide, and the like.

[0048] Examples of oxazolines include monooxazoline compounds such as 2-oxazoline, 2-methyl-2-oxazoline, 2-phenyl-2-oxazoline, 2,5-dimethyl-2-oxazoline, 2,4-diphenyl-2-oxazoline, 2,2'-(1,3-phenylene)-bis(2-oxazoline), 2,2'-(1,2-ethylene)-bis(2-oxazoline), 2,2'-(1,4-butylene)-bis(2-oxazoline), 2,2'-(1,4-phenylene)-bis(2-oxazoline), and the like.

[0049] Examples of amino resins include melamine resins, benzoguanamine resins, urea resins, and the like.

[0050] The blending amount of the curing agent (B) is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, and even more preferably 0.5 part by mass or more with respect to 100 parts by mass of the olefin resin (A). Also, the blending amount of the curing agent (B) is preferably 50 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 25 parts by mass or less with respect to 100 parts by mass of the olefin resin (A). Thereby, excellent adhesiveness can be exhibited.

[0051] The adhesive used in the present invention, in addition to the above components, can further contain an organic solvent to ensure fluidity and exhibit proper coatability. Such an organic solvent is not particularly limited as long as it can be volatilized and removed by heating in the drying step during adhesive coating. Examples include aromatic organic solvents such as toluene and xylene; aliphatic organic solvents such as n-hexane and n-heptane; alicyclic organic solvents such as cyclohexane and methylcyclohexane; halogenated organic solvents such as trichloroethylene, dichloroethylene, chlorobenzene, and chloroform; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; alcohol solvents such as ethanol, methanol, n-propanol, 2-propanol (isopropyl alcohol), butanol, and hexanol; ether solvents such as diisopropyl ether, butyl cellosolve, tetrahydrofuran, dioxane, and butyl carbitol; glycol ether solvents such as diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, and propylene glycol monomethyl ether; glycol ester solvents such as ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, and diethylene glycol monoethyl ether acetate. These can be used alone or in combination of two or more.

[0052] When using an olefin resin (A) having an acid group or acid anhydride group or an olefin resin having vinyl acetate, since its solubility is excellent, it is preferable to use a mixed solvent of an alicyclic organic solvent and an ester solvent. In particular, when using an olefin resin having an acid group, acid anhydride group and / or vinyl acetate, since its solubility is excellent, it is preferable to use a mixed solvent of methylcyclohexane, ethyl acetate and 2-propanol.

[0053] The amount of the organic solvent used is preferably such that the proportion of the olefin resin (A) is 5 to 20% by mass based on the total mass of the olefin resin (A) and the organic solvent. Thereby, an adhesive excellent in coatability and wettability to the substrate can be obtained.

[0054] (Additive) The adhesive used in the present invention can use various additives such as silane coupling agents, tackifiers, plasticizers, thermoplastic elastomers, reactive elastomers, phosphate compounds, silane coupling agents, adhesion promoters, metal-based catalysts, amine-based catalysts, aliphatic cyclic amide compounds, titanium chelate complexes, and esterification catalysts as needed. The content of these additives may be appropriately adjusted within a range that does not impair the function of the adhesive of the present invention.

[0055] (Silane coupling agent) Examples of the silane coupling agent include aminosilanes such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethyldimethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane; epoxysilanes such as β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxypropyltriethoxysilane; vinylsilanes such as vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane; and hexamethyldisilazane, γ-mercaptopropyltrimethoxysilane, etc.

[0056] Examples of the tackifier include rosin-based or rosin ester-based tackifiers, terpene-based or terpene phenol-based tackifiers, saturated hydrocarbon resins, coumarone-based tackifiers, coumarone indene-based tackifiers, styrene resin-based tackifiers, xylene resin-based tackifiers, phenol resin-based tackifiers, petroleum resin-based tackifiers, etc. These may be used alone or in combination of two or more kinds.

[0057] Examples of the plasticizer include polyisoprene, polybutene, process oil, etc. Examples of the thermoplastic elastomer include styrene-butadiene copolymer (SBS), hydrogenated product of styrene-butadiene copolymer (SEBS), SBBS, hydrogenated product of styrene-isoprene copolymer (SEPS), styrene block copolymer (TPS), olefin-based elastomer (TPO), etc. Examples of the reactive elastomer include those obtained by acid-modifying these elastomers.

[0058] Examples of the phosphoric acid compound include phosphoric acids such as hypophosphorous acid, phosphorous acid, orthophosphoric acid, metaphosphoric acid, etc., condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, ultraphosphoric acid, etc., mono- and diesterified products such as monomethyl orthophosphate, monoethyl orthophosphate, monopropyl orthophosphate, monobutyl orthophosphate, mono-2-ethylhexyl orthophosphate, monophenyl orthophosphate, monomethyl phosphite, monoethyl phosphite, monopropyl phosphite, monobutyl phosphite, mono-2-ethylhexyl phosphite, monophenyl phosphite, di-2-ethylhexyl orthophosphate, diphenyl orthophosphate, dimethyl phosphite, diethyl phosphite, dipropyl phosphite, dibutyl phosphite, di-2-ethylhexyl phosphite, diphenyl phosphite, etc., mono- and diesterified products of condensed phosphoric acids and alcohols, products obtained by adding epoxy compounds such as ethylene oxide, propylene oxide, etc. to the above-mentioned phosphoric acids, epoxy phosphoric esters obtained by adding the above-mentioned phosphoric acids to aliphatic or aromatic diglycidyl ethers, etc.

[0059] As accelerators, imidazole compounds such as 2-methylimidazole, 1,2-dimethylimidazole, 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole; tertiary amines such as triethylamine, triethylenediamine, N'-methyl-N-(2-dimethylaminoethyl)piperazine, 1,8-diazabicyclo[5.4.0]undecene (DBU), 1,5-diazabicyclo[4.3.0]nonene, 6-dibutylamino-1,8-diazabicyclo[5.4.0]undecene; compounds obtained by converting these tertiary amines into amine salts with phenol, octylic acid, quaternized tetraphenylborate salts, etc.; cationic catalysts such as triallylsulfonium hexafluoroantimonate, diallyliodonium hexafluoroantimonate; and organophosphine compounds such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, tris(4-methylphenyl)phosphine, tris(4-butylphenyl)phosphine, diphenylphosphine, phenylphosphine, etc. These may be used alone or in combination of two or more.

[0060] Examples of metal-based catalysts include metal complex-based, inorganic metal-based, and organometallic-based catalysts. Examples of metal complex-based catalysts include acetylacetonate salts of metals selected from the group consisting of Fe (iron), Mn (manganese), Cu (copper), Zr (zirconium), Th (thorium), Ti (titanium), Al (aluminum), Co (cobalt), such as iron acetylacetonate, manganese acetylacetonate, copper acetylacetonate, zirconia acetylacetonate, etc. From the viewpoints of toxicity and catalytic activity, iron acetylacetonate (Fe(acac)3) or manganese acetylacetonate (Mn(acac)2) is preferred. These may be used alone or in combination of two or more.

[0061] Examples of inorganic metal-based catalysts include those selected from Sn, Fe, Mn, Cu, Zr, Th, Ti, Al, Co, etc. These may be used alone or in combination of two or more.

[0062] Examples of the organometallic catalysts include organozinc compounds such as zinc octylate, zinc neodecanoate, and zinc naphthenate; organotin compounds such as stannous diacetate, stannous dioctoate, stannous dioleate, stannous dilaurate, dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin oxide, and dibutyltin dichloride; organonickel compounds such as nickel octylate and nickel naphthenate; organocobalt compounds such as cobalt octylate and cobalt naphthenate; organobismuth compounds such as bismuth octylate, bismuth neodecanoate, and bismuth naphthenate; and titanium compounds such as tetraisopropyl titanate, dibutyltitanium dichloride, tetrabutyl titanate, and butoxytitanium trichloride. These may be used alone or in combination of two or more.

[0063] Examples of amine catalysts include triethylenediamine, 2-methyltriethylenediamine, quinuclidine, 2-methylquinuclidine, N,N,N’,N’-tetramethylethylenediamine, N,N,N’,N’-tetramethylpropylenediamine, N,N,N’,N”,N”-pentamethyldiethylenetriamine, N,N,N’,N”,N”-pentamethyl-(3-aminopropyl)ethylenediamine, N,N,N’,N”,N”-pentamethyldipropylenetriamine, N,N,N’,N’-tetramethylhexamethylenediamine, bis(2-dimethylaminoethyl)ether, dimethylethanolamine, dimethylisopropanolamine, dimethylaminoethoxyethanol, N,N-dimethyl-N’-(2-hydroxyethyl)ethylenediamine, N,N-dimethyl-N’-(2-hydroxyethyl)propylenediamine, bis(dimethylaminopropyl)amine, bis(dimethylaminopropyl)isopropanolamine, 3-quinuclidinol, N,N,N’,N’-tetramethylguanidine, 1,3,5-tris(N,N-dimethylaminopropyl)hexahydro-S-triazine, 1,8-diazabicyclo[5.4.0]undecene-7, N-methyl-N’-(2-dimethylaminoethyl)piperazine, N,N’-dimethylpiperazine, dimethylcyclohexylamine, N-methylmorpholine, N-ethylmorpholine, 1-methylimidazole, 1,2-dimethylimidazole, 1-isobutyl-2-methylimidazole, 1-dimethylaminopropylimidazole, N,N-dimethylhexanolamine, N-methyl-N’-(2-hydroxyethyl)piperazine, 1-(2-hydroxyethyl)imidazole, 1-(2-hydroxypropyl)imidazole, 1-(2-hydroxyethyl)-2-methylimidazole, 1-(2-hydroxypropyl)-2-methylimidazole, etc. These may be used alone or in combination of two or more.

[0064] Aliphatic cyclic amide compounds include, for example, δ-valerolactam, ε-caprolactam, ω-enantholactam, η-capryllactam, β-propiolactam, etc. Among these, ε-caprolactam is effective for promoting curing. These may be used alone or in combination of two or more.

[0065] The titanium chelate complex is a compound whose catalytic activity is enhanced by ultraviolet irradiation, and a titanium chelate complex having an aliphatic or aromatic diketone as a ligand is preferable from the viewpoint of excellent curing promotion effect. Further, in the present invention, in addition to an aromatic or aliphatic diketone as a ligand, those having an alcohol having 2 to 10 carbon atoms are preferable from the viewpoint that the effect of the present invention becomes more remarkable. These may be used alone or in combination of two or more.

[0066] As the esterification catalyst, a polymerization catalyst composed of at least one metal selected from the group consisting of Group 2, Group 4, Group 12, Group 13, Group 14, and Group 15 of the periodic table, or a compound of the metal is preferable. Examples of the polymerization catalyst composed of such a metal or a compound of the metal include metals such as Ti, Sn, Zn, Al, Zr, Mg, Hf, Ge, and compounds of these metals. More specifically, titanium tetraisopropoxide, titanium tetrabutoxide, titanium oxyacetylacetonate, tin octoate, 2-ethylhexyltin, zinc acetylacetonate, zirconium tetrachloride, zirconium tetrachloride tetrahydrofuran complex, hafnium tetrachloride, hafnium tetrachloride tetrahydrofuran complex, germanium oxide, tetraethoxy germanium, etc. These may be used alone or in combination of two or more.

[0067] (Other additives) In addition to the components described above, the adhesive used in the present invention may contain a leveling agent, inorganic fine particles such as colloidal silica and alumina sol, organic fine particles of polymethyl methacrylate, an antifoaming agent, a sagging inhibitor, a wetting dispersant, a viscosity modifier, an ultraviolet absorber, a metal deactivator, a peroxide decomposer, a flame retardant, a reinforcing agent, a plasticizer, a lubricant, a rust inhibitor, a fluorescent brightening agent, an inorganic heat ray absorber, a flameproofing agent, an antistatic agent, a dehydrating agent, etc. The content of these additives may be appropriately adjusted within a range that does not impair the functions of the adhesive of the present invention.

[0068] The adhesive used in the present invention can be adjusted by mixing the above-described components. At this time, the components may be mixed simultaneously to form an adhesive, but it is preferable to prepare a premix by previously mixing the components other than the curing agent (B) and then mixing the curing agent (B) at the time of using the adhesive to form a two-component adhesive, because it is excellent in the stability and workability of the adhesive.

[0069] (Laminate) The laminate of the present invention is a laminated film including the first base film, the second base film, and the adhesive layer disposed between the first base film and the second base film. Specifically, the laminate can be obtained by bonding the first base film and the second base film with the adhesive.

[0070] From the viewpoint of recycling, it is preferable that the layer structure is as simple as possible. However, from the viewpoint of the flowability of the packaging material, which is the use of the laminate of the present invention, printing for displaying the contents of the packaging material, the description, and the name of the product is often necessary. For this printing ink, liquid inks such as gravure printing ink and flexographic printing ink are often used.

[0071] (Printing layer) The printing layer is a layer in which characters, figures, symbols, and other desired patterns are printed using liquid ink or the like. The position where the laminate is provided is arbitrary. In this specification, liquid ink is a general term for solvent-based inks used in gravure printing or flexographic printing. It may contain resin, colorant, and solvent as essential components, or it may be a so-called clear ink that contains resin and solvent and substantially does not contain a colorant.

[0072] The resin used in the liquid ink is not particularly limited. For example, acrylic resin, polyester resin, styrene resin, styrene-maleic acid resin, maleic acid resin, polyamide resin, polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-acrylic copolymer resin, ethylene-vinyl acetate copolymer resin, vinyl acetate resin, polyvinyl chloride resin, chlorinated polypropylene resin, cellulose-based resin, epoxy resin, alkyd resin, rosin-based resin, rosin-modified maleic acid resin, ketone resin, cyclized rubber, chlorinated rubber, butyral, petroleum resin, etc. can be mentioned, and one kind or two or more kinds can be used in combination. Preferably, it is at least one kind selected from polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, and cellulose-based resin, or two or more kinds.

[0073] Examples of the colorant used in the liquid ink include inorganic pigments such as titanium oxide, valve pattern, antimony red, cadmium red, cadmium yellow, cobalt blue, ultramarine blue, ultramarine, carbon black, graphite; soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, condensed polycyclic pigments and other organic pigments; extender pigments such as calcium carbonate, kaolin clay, barium sulfate, aluminum hydroxide, talc.

[0074] The organic solvent used in the liquid ink preferably does not contain aromatic hydrocarbon-based organic solvents. More specifically, alcohol-based organic solvents such as methanol, ethanol, n-propanol, isopropanol, butanol, etc., ketone-based organic solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, etc., ester-based organic solvents such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, etc., aliphatic hydrocarbon-based organic solvents such as n-hexane, n-heptane, n-octane, etc., alicyclic hydrocarbon-based organic solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, cyclooctane, etc. can be mentioned, and one or more of them can be used in combination.

[0075] (Other substrates) As described above, the laminate of the present invention is a laminate, that is, a laminated film including a first base film, a second base film, and an adhesive layer disposed between the first base film and the second base film, but other substrates other than the first base film and the second base film may be further laminated. Specifically, for example, First base film / Adhesive layer / Second base film First base film / Adhesive layer / Second base film / Adhesive layer / Third substrate First base film / Adhesive layer / Third base film / Adhesive layer / Second substrate First base film / Adhesive layer / Second base film / Adhesive layer / Third substrate / Adhesive layer / Fourth substrate First base film / Adhesive layer / Third base film / Adhesive layer / Fourth substrate / Adhesive layer / Second substrate (Here, other substrates are represented as the third substrate and the fourth substrate) etc., and it may be a laminated film having a structure in which a plurality of substrates are laminated.

[0076] Even when other base materials are included, it is preferable that the raw materials of the other base materials are thermoplastic resins mainly composed of olefin-based resins because of their excellent recyclability. The same types as those of the first base material and the second base material can be used for the type of olefin-based resin as the raw material, the film manufacturing method, the type of additive, the film thickness, and the like. Also, when laminating the laminate of the present invention with other base materials, it is preferable to use the adhesive because of its excellent recyclability and adhesiveness.

[0077] (Method for manufacturing a laminate) As described above, the laminate of the present invention is obtained by laminating the first base material film and the second base material film with the adhesive. Even when other base materials are included in the configuration, it is preferable to use the adhesive because of its excellent recyclability and adhesiveness.

[0078] When the adhesive is a solvent type, the adhesive is applied to either the first base material film or the second base material film using a roll such as a gravure roll, and after volatilizing the organic solvent by heating in an oven or the like, the other is laminated to obtain the laminate of the present invention. It is preferable to perform an aging treatment after lamination. The aging temperature is preferably from room temperature to 80°C, and the aging time is preferably from 12 to 240 hours.

[0079] When the adhesive is a solvent-free type, the adhesive pre-heated to about 40°C to 100°C is applied to either the first base material or the second base material using a roll such as a gravure roll, and then the other is immediately laminated to obtain the laminate of the present invention. It is preferable to perform an aging treatment after lamination. The aging temperature is preferably from room temperature to 70°C, and the aging time is preferably from 6 to 240 hours.

[0080] The coating amount of the adhesive is adjusted as appropriate. In the case of a solvent type, as an example, the solid content is 0.1 g / m 2 or more and 10 g / m 2 or less, preferably 0.3 g / m 2 or more and 5 g / m 2Adjust as follows. In the case of the solvent-free type, the coating amount of the adhesive is, for example, 0.1 g / m 2 or more and 10 g / m 2 or less, preferably 0.3 g / m 2 or more and 5 g / m 2 or less.

[0081] (Method for manufacturing recycled plastic) The recycled plastic of the present invention can be obtained by using the laminate of the present invention and recycling known waste plastics by a processing method. An example of the processing method is shown. Of course, in the present invention, it is not limited to this, and various known recycled plastic processing methods can be applied.

[0082] As an example of the processing method, there can be mentioned a method for manufacturing recycled plastic having a step of crushing the laminate of the present invention, a step of melt-kneading the crushed pieces, and a step of pelletizing the melt-kneaded kneaded product. The crusher used in the step of crushing the laminate of the present invention may be a known crusher and is not particularly limited. The film pieces after crushing are physically blended by melt-kneading, solvent casting blend, latex blend, polymer complex, etc. In particular, the melt-kneading method is common. Examples of the apparatus for kneading include a tumbler, a Henschel mixer, a rotary mixer, a super mixer, a ribbon tumbler, a V blender, etc. After melt-kneading by such a kneading apparatus, pelletization is performed. For melt-kneading pelletization, a single-screw or multi-screw extruder is generally used, and it may be charged as it is in the form of film pieces, or charged after heat or non-heat compression volume reduction treatment. Further, in addition to these extruders, a Banbury mixer, a roller, a co-kneader, a blast mill, a Brabender plastograph, etc. can also be used, and these are operated batchwise or continuously. Also, a method may be used in which it is used as a molding resin and melt-kneaded in the heating cylinder of a molding machine without melt-kneading.

[0083] Further, as an example of the processing method, there is a method for manufacturing recycled plastic, which includes a step of crushing the laminate of the present invention, a step of immersing the laminate in a release liquid to separate and detach the laminate into each layer, a step of recovering each separated and detached layer, a step of melt-kneading the recovered crushed pieces, and a step of pelletizing the melt-kneaded kneaded product.

[0084] Similar to the above, the crusher used in the step of crushing the laminate of the present invention may be a known crusher and is not particularly limited. The film pieces after crushing are immersed in a release liquid to separate and detach the laminate into each layer. The separation and detachment method (also simply referred to as the detachment method) is a method of immersing the laminate of the present invention in a detachment treatment liquid to detach other layers provided on the substrate from the substrate. Note that detachment means that the detachment layer is dissolved or swollen by the detachment treatment liquid and peeled off, so that the substrate and other layers are separated.

[0085] (Detachment treatment liquid) The detachment treatment liquid may be any liquid that can swell and dissolve the adhesive layer, printing layer, etc. in the laminate of the present invention, and can be appropriately selected in consideration of the ease of detachment of the detachment layer described later. Examples of such a release liquid include water, an alkaline solution, and an acidic aqueous solution. From the viewpoint of detaching the materials of the adhesive layer and printing layer commonly used in packaging materials, the detachment treatment liquid is preferably an alkaline solution containing an inorganic base.

[0086] (Inorganic base) Specific examples of the inorganic base include sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium dihydrogen carbonate, potassium dihydrogen carbonate, etc. These inorganic bases are contained at a concentration of 0.1 to 10% by weight based on the total amount of the aqueous solution, and a concentration of 0.1% to 5% by weight is more preferable. Also, the pH is preferably 9 or more, and more preferably 10 or more.

[0087] (Surfactant) The release treatment liquid may contain a surfactant. The surfactant is not particularly limited, and known surfactants can be used. For example, anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. can be mentioned. Among these, anionic surfactants, nonionic surfactants or amphoteric surfactants are preferred.

[0088] Examples of anionic surfactants include alkylbenzene sulfonates, alkylphenyl sulfonates, alkylnaphthalene sulfonates, higher fatty acid salts, sulfate esters of higher fatty acid esters, sulfonates of higher fatty acid esters, sulfate esters and sulfonates of higher alcohol ethers, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, etc. Specific examples thereof include dodecylbenzene sulfonate, isopropylnaphthalene sulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenyl sulfonate, dibutylphenylphenol disulfonate, etc.

[0089] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyglycerin fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkyl amines, polyoxyethylene fatty acid amides, fatty acid alkanolamides, alkyl alkanolamides, acetylene glycols, oxyethylene adducts of acetylene glycols, polyethylene glycol polypropylene glycol block copolymers, etc. Among these, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkanolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, polyethylene glycol polypropylene glycol block copolymer are preferred.

[0090] As other surfactants, silicone-based surfactants such as polyoxyethylene adducts of polysiloxanes; fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, oxyethylene perfluoroalkyl ethers; biosurfactants such as spiculisporic acid, rhamnolipid, lysophosphatidylcholine, etc. can also be used.

[0091] These surfactants can be used alone or in combination of two or more. When adding a surfactant, the addition amount is preferably in the range of 0.001 to 2% by mass, more preferably 0.001 to 1.5% by mass, and even more preferably in the range of 0.01 to 1% by mass based on the total amount of the desorption treatment liquid.

[0092] (Water-soluble organic solvent) The release treatment liquid may contain a water-soluble organic solvent. Examples of the water-soluble organic solvent include water-soluble alcohols, water-soluble glycol ether-based organic solvents, etc. Specifically, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol dibutyl ether, diethylene glycol monomethyl ether (methyl carbitol), diethylene glycol dimethyl ether, diethylene glycol monoethyl ether (carbitol), diethylene glycol diethyl ether (diethyl carbitol), diethylene glycol monobutyl ether (butyl carbitol), diethylene glycol dibutyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, methylene dimethyl ether (methylal), propylene glycol monobutyl ether, tetrahydrofuran, acetone, diacetone alcohol, acetonylacetone, acetylacetone, ethylene glycol monomethyl ether acetate (methyl cellosolve acetate), diethylene glycol monomethyl ether acetate (methyl carbitol acetate), diethylene glycol monoethyl ether acetate (carbitol acetate), ethyl hydroxyisobutyrate, and ethyl lactate, etc. These can be used alone or in combination of two or more.

[0093] The content ratio of the water-soluble organic solvent in the release treatment liquid is preferably 0.1% by mass to 20% by mass, more preferably 1% by mass to 10% by mass.

[0094] (Non-water-soluble organic solvent) The release treatment liquid may contain a non-water-soluble organic solvent. Specific examples of the water-insoluble organic solvents include alcohol solvents such as n-butanol, 2-butanol, isobutanol, and octanol; aliphatic hydrocarbon solvents such as hexane, heptane, and normal paraffin; aromatic hydrocarbon solvents such as benzene, toluene, xylene, and alkylbenzene; halogenated hydrocarbon solvents such as methylene chloride, 1-chlorobutane, 2-chlorobutane, 3-chlorobutane, and carbon tetrachloride; ester solvents such as methyl acetate, ethyl acetate, and butyl acetate; ketone solvents such as methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone; and ether solvents such as ethyl ether and butyl ether. These can be used alone or in combination of two or more.

[0095] (Defoaming agent) The detachment treatment liquid may contain a defoaming agent. When stirring or crushing the substrate during immersion, a large amount of foam may be generated. If the foam remains, it may overflow in the plastic film recovery process. Also, when a large amount of foam is entrapped in the detachment treatment liquid during crushing of the substrate, the substrate may not be crushed to the desired size.

[0096] As compounds generally used as defoaming agents, water-soluble organic solvents or nonionic surfactants with a low HLB value in the range of 1 to 3 are used. However, silicone-based compounds are particularly preferred as compounds with high defoaming ability. Among them, emulsion-type or self-emulsifying silicone compounds are preferred.

[0097] The defoaming agent may be used alone or in combination of two or more. It is preferably in the range of 0.01 to 5% by weight, more preferably in the range of 0.02 to 4% by weight, and even more preferably in the range of 0.03 to 3% by weight in the cleaning liquid that can be used in Step 1.

[0098] (Liquid temperature) The liquid temperature of the release treatment liquid is not particularly limited as long as the liquid state can be maintained, but usually it is preferably carried out at a liquid temperature of 15 to 90°C. When using a release treatment liquid with a surfactant or the like added to water, it is preferable to adjust the liquid temperature according to the type of surfactant. The optimal temperature with excellent cleaning effect varies depending on the type of surfactant, but for example, 40°C or higher is preferable, 65°C or higher is preferable, and 85°C or higher is preferable. Also, it is preferable to immerse the target printed matter or laminate, for example, in a treatment tank, in a state where the release treatment liquid is heated or ultrasonically vibrated to the above temperature. The heating method is not particularly limited, and a known heating method using heat rays, infrared rays, microwaves, etc. can be adopted. Also, for ultrasonic vibration, for example, a method of attaching an ultrasonic vibrator to the treatment tank and applying ultrasonic vibration to the above warm water or alkaline solution can be adopted.

[0099] (Stirring) Stirring when immersing the printed matter or laminate in the release treatment liquid is not essential and may be optional, but stirring allows for more efficient swelling. It is preferable to keep the stirring speed at a level where foaming or the like is unlikely to occur even without adding an antifoaming agent.

[0100] The equipment and method for stirring when stirring are not particularly limited, and known methods can be used. Specifically, an apparatus equipped with a motor with stirring blades capable of stirring the cleaning liquid in a container, an apparatus equipped with an apparatus for generating ultrasonic waves, an apparatus capable of shaking the entire container, a wet crusher, a method of stirring with a water flow pump, a bubbling method using an inert gas such as nitrogen gas, etc. can be mentioned.

[0101] The time for immersing the printed matter or laminate in the release treatment liquid generally ranges from 2 minutes to 48 hours, although it also depends on the composition of the printed matter or laminate. In the printed matter or laminate, it is not necessary for the film such as the printed layer to be completely detached from the substrate by 100%, but it is preferable that 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more of the film is detached.

[0102] In the detachment process, the number of times of immersion in the detachment treatment liquid may be once or divided into several times. That is, after performing the immersion once, a step of recovering the separated film substrate may be performed, or after performing the immersion several times, a step of recovering the film substrate may be performed. Also, when performing immersion multiple times in the detachment process, the concentration of the detachment treatment liquid may be changed. Further, during the detachment process, known steps such as water washing and drying may be appropriately added.

[0103] In addition, the detachment treatment liquid promotes the detachment of the plastic substrate by contacting the printing layer, the primer layer, or the interface between the substrate and other layers from the end portion of the printed matter or the laminate. Therefore, it is preferable that the printing layer, the adhesive layer, or the primer layer is exposed in the cross section. Therefore, it is more preferable to include a step of fragmenting the printed matter or the laminate by cutting or pulverizing.

[0104] The method for crushing the laminate of the present invention is not particularly limited and can be performed by a known method. Also, the crushing may be performed in an air atmosphere in which no liquid such as a solvent is present, or in water or a cleaning liquid. When performing the crushing in an air atmosphere, a dry crusher can be used. Also, when performing the crushing in water or a cleaning liquid, a wet crusher capable of performing pressure feeding simultaneously with the crushing can be used.

[0105] After performing the immersion treatment in the above-described detachment treatment liquid, it is preferable to provide a step of stirring the recovered substrate in water or in the above-described peeling treatment liquid. By this step, the ratio of the film such as the printing layer detaching from the substrate can be increased. The equipment and method for stirring are not particularly limited, and known methods can be used, but it is preferable to perform the stirring using a wet crusher.

[0106] Furthermore, it is preferable to wash the recovered substrate by stirring in a rinse liquid for finish washing to remove detached substances such as ink and adhesive that reattach and remain on the single-layer detached substrate film. By removing the ink pieces slightly remaining on the film surface, the quality of the recycled pellets can be greatly improved. The rinsing liquid is not particularly limited, and the above-described detachment treatment liquid can be used as it is, but it preferably contains an appropriate amount of an organic solvent. As the organic solvent, for example, it is preferable to contain one or more water-soluble alcohols and water-soluble solvents having a flash point of 21°C or higher. It is preferable that the cleaning liquid contains a large amount of a so-called water-soluble solvent containing alcohols. Specifically, the water-soluble solvent is preferably 30% by mass or more, preferably 40% by mass or more, preferably 50% by mass or more, preferably 60% by mass or more, preferably 70% by mass or more, preferably 80% by mass or more, preferably 90% by mass or more, and preferably 95% by mass or more. The equipment and method for stirring in the rinsing liquid are not particularly limited, and known methods can be used. Specifically, there are a device equipped with a motor with a stirring blade capable of stirring the cleaning liquid in a container, a device equipped with a device for generating ultrasonic waves, a device capable of shaking the entire container, a wet crusher, a kneader, and the like.

[0107] (Recovery and Reuse of Detachment Treatment Liquid) The detachment treatment liquid used in the detachment treatment step is supplied to any one or more recycling machines selected from a filter, a centrifuge, and an ultrafiltration machine to remove solids and then can be reused. The same applies when water, rinsing liquid, etc. are used. While performing wet crushing, on the other hand, the reuse process of water, detachment treatment liquid, rinsing liquid, etc. can be continuously operated, and solids can be separated from water, cleaning liquid, and rinsing liquid.

[0108] (Drying of Plastic Separates) The recovered material of the separated and recovered base material is dried by any one or more methods selected from reduced-pressure heating drying, hot-air drying, pressure compression drying, etc. to remove residual moisture. As a pretreatment for producing the recycled pellets described later, briquettes may be produced using a pressure compressor such as a squeezing dehydrator manufactured by Nippon Seam Co., Ltd., a pellet mill manufactured by Oike Iron Works, Stella manufactured by Elcom Co., Ltd., or a briquetting machine after or during the drying of the film pieces which are the recovered materials. When the base material film is pulverized into a powder using a grinder as a wet crusher, the crushed material is pulverized to about 10 to 500 μm, and since the density of the crushed material is high, the pressure compression step can be omitted. The density varies depending on the material constituting the pulverized material, but a higher density is preferable because it is easier to handle for kneading. Specifically, in the dry state, 0.03 kg or more is preferable, 0.05 kg or more is more preferable, 0.2 kg or more is more preferable, and 0.3 kg or more is even more preferable.

[0109] The pellets mainly made of the recycled plastic of the present invention can maximize their effects especially by recycling them into unstretched polyolefin films or molded products by injection molding or the like. The method of recycling into an unstretched polyolefin film is not particularly limited and can be obtained by a known film manufacturing method. For example, a melt kneading method using a general mixer such as a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, a method of dissolving or dispersing and mixing each component and then heating and removing the solvent, etc. can be used. Considering workability, it is particularly preferable to use a single-screw extruder or a twin-screw extruder. When using a single-screw extruder, a full-flight screw, a screw with a mixing element, a barrier-flight screw, a fluted screw, etc. can be used without particular limitation. Regarding the twin-kneading device, a co-rotating twin-screw extruder, a counter-rotating twin-screw extruder, and the screw shape are not particularly limited to a full-flight screw or a kneading disk type. Also, after melting by a single-screw extruder or a twin-screw extruder, etc., a method of forming a film with a T-die through a feed block or a multi-manifold may be used. It is also possible to perform a surface modification treatment on the film after reproduction to appropriately improve the post-process suitability as needed. For example, it is possible to perform a surface modification treatment on the surface that contacts other base materials in order to improve the printing suitability when using a single film or the lamination suitability when using it in a laminated state. As the surface modification treatment, methods that express functional groups by oxidizing the film surface, such as corona discharge treatment, plasma treatment, and flame treatment, or methods that modify by wet processes such as coating an easy-adhesion layer can be preferably used.

[0110] In addition, in the same manner as pellets mainly made of virgin plastic, it can be molded by known molding methods other than the above film formation, for example, conventional molding methods such as injection molding, extrusion molding, vacuum molding, pressure-air molding, and blow molding, and can be used for various applications as a molded body. For example, in addition to daily necessities, stationery, toys, sports goods, household appliances, and automotive parts used in ordinary households, it can also be used as a film, sheet, or fiber. If there are no problems in terms of hygiene, it can also be used for medical devices, food containers, and food packaging materials.

Examples

[0111] Hereinafter, the present invention will be described in more detail with specific examples, but the present invention is not limited to these examples. In the following examples, "parts" and "%" represent "parts by mass" and "mass%" respectively unless otherwise specified.

[0112] (Adjustment of Adhesive) (Adhesive 1 for Examples) 85 parts of PC480A manufactured by Sun Allomer Co., Ltd., 5 parts of SCONA TPPP 8112 GA manufactured by Big Chemie Japan Co., Ltd., and 10 parts of an olefin resin composed of 1520F manufactured by Ube Maruzen Polyethylene Co., Ltd. were melt-kneaded at 230°C using a twin-screw kneader (ULTnano manufactured by Technovel Corporation) to obtain an anhydrous maleic acid-modified polypropylene composition for adhesion with a polypropylene content of 90 mol% and a modification rate of maleic anhydride of 0.1 mol% or more. This was adjusted to a non-volatile content of 12 mass% with a methylcyclohexane and ethyl acetate solution.

[0113] (Adhesive for Example 2) 75 parts of PH943 manufactured by Sun Aroma Co., Ltd., 5 parts of Rikeaid MG-400P manufactured by Riken Vitamin Co., Ltd., and 20 parts of olefin resin composed of 1520F manufactured by Ube Maruzen Polyethylene Co., Ltd. were melt-kneaded at 230 °C using a twin-screw kneader (ULTnano manufactured by Technovel Corporation) to obtain a maleic anhydride-modified polypropylene composition for adhesion with a polypropylene content of 80 mol% and a modification rate of maleic anhydride of 0.1 mol% or more. This was adjusted to a non-volatile content of 12% by mass with a methylcyclohexane and ethyl acetate solution.

[0114] (Adhesive for Example 3) 80 parts of Nipolon-L T240F manufactured by Tosoh Corporation, 5 parts of Rikeaid MG-400P manufactured by Riken Vitamin Co., Ltd., and 15 parts of olefin resin composed of PC480A manufactured by Sun Aroma Co., Ltd. were melt-kneaded at 230 °C using a twin-screw kneader (ULTnano manufactured by Technovel Corporation) to obtain a maleic anhydride-modified polyethylene composition for adhesion with a polyethylene content of 80 mol% and a modification rate of maleic anhydride of 0.1 mol% or more. This was adjusted to a non-volatile content of 12% by mass with a methylcyclohexane and ethyl acetate solution.

[0115] (Adhesive for Example 4) Evaflex EV-45X (a polyethylene-based resin modified with vinyl acetate, and the modification rate of the vinyl acetate is 5 to 20 mol% or more). Manufactured by Mitsui Dow Polychemical Co., Ltd.) was adjusted to a non-volatile content of 12% by mass with a methylcyclohexane and ethyl acetate solution.

[0116] (Adhesive for Comparative Example 1) Dick Dry LX-500 and KW-75, which are urethane-based reactive adhesives manufactured by DIC Corporation, were blended at a ratio of 10 parts to 1 part, and adjusted with ethyl acetate so that the solid content concentration of the coating liquid was 25%.

[0117] (Printing Ink) FINAT R794 White G3 (manufactured by DIC Graphics Corporation) was used.

[0118] (Film) (Film 1) A biaxially oriented polypropylene film (manufactured by Toyobo Co., Ltd., Pyren Film - OT P2161, 20 μm) was used. Hereinafter, it is abbreviated as OPP. (Film 2) An unstretched polypropylene film (manufactured by Toyobo Co., Ltd., Pyren Film - CT P1128, 25 μm) was used. Hereinafter, it is abbreviated as CPP.

[0119] (Preparation of laminated film 1) Using a gravure printing machine manufactured by Orient Corporation, white printing was performed on Film 1 with FINAT R794 White G3 in solid plate. To this, Adhesive 1 was applied using a dry laminator manufactured by Orient Corporation so that the solid content weight was about 1.5 g / m 2 After volatilizing ethyl acetate, it was laminated with Film 2. Aging was carried out at 50 °C for 2 days to produce laminated film 1 (LAM1).

[0120] (Preparation of laminated films 2 to 4) Laminated films 2, 3, and 4 (LAM2, LAM3, HLAM4) were produced in the same manner as laminated film 1, except that any one of Adhesives 2, 3, and 4 was used as the adhesive. Table 1 shows the composition of the laminated films.

[0121]

Table 1

[0122] In Table 1, the abbreviations are as follows. OPP Biaxially oriented polypropylene film (manufactured by Toyobo Co., Ltd., Pyren Film - OT P2161, 20 μm) CPP Unstretched polypropylene film (manufactured by Toyobo Co., Ltd., Pyren Film - CT P1128, 25 μm)

[0123] (Peeling Test of Laminated Film) (Peeling Test 1 of Laminated Film) Ten samples of the laminated film cut into strips with a width of 20 mm and a length of 20 mm were immersed in 80 ml of an alkaline aqueous solution and stirred with a stirrer under the conditions of a hot water bath temperature of 85 °C, a stirring time of 1 hour, and a stirring rotation speed of 1000 rmp. After stirring, the degree of peeling of the samples was confirmed. Any of the following three types was used as the alkaline aqueous solution.

[0124] Alkaline Aqueous Solution 1: 2% Sodium Hydroxide Aqueous Solution Alkaline Aqueous Solution 2: An aqueous solution composed of 2% sodium hydroxide and 1% DKS NL-Dash408 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.). Alkaline Aqueous Solution 3: An aqueous solution composed of 2% sodium hydroxide, 1% DKS NL-Dash408 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and 2% 2-phenoxyethanol.

[0125] (Judgment Criteria for Peeling Test 1) ◎: The laminated film sample was separated into two pieces. 〇: 40% of the area of the laminated film sample was peeled off (peeled off by 5 mm or more from the edge periphery of the sample). △: 20% of the area of the laminated film sample was peeled off (peeled off by 2 mm or more from the edge periphery of the sample). ×: The laminated film sample remained completely unchanged and did not peel off compared with before the test.

[0126] The results of Peeling Test 1 for Examples 1 to 4 and Comparative Example 1 are shown in Table 2.

[0127]

Table 2

[0128] (Peeling Test 2 of Laminated Film) A 5 g sample of the laminated film cut into strips with a width of 20 mm and a length of 20 mm was immersed in 1 L of the alkaline aqueous solution 3, and stirred with a stirrer under stirring conditions of a hot water bath temperature of 85 °C, a stirring time of 1 hour, and a stirring rotation speed of 1000 rmp. After stirring, the laminated film sample was put into a wet crushing system, the sample was crushed, and the degree of separation was confirmed. The following were used as the alkaline aqueous solutions. Alkaline aqueous solution 3 An aqueous solution consisting of 2% sodium hydroxide, 1% DKS NL-Dash408 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and 2% 2-phenoxyethanol.

[0129] (Criteria for the detachment test 2) 〇: More than 80% of the laminated film sample was separated into two sheets. △: More than 50% of the laminated film sample was separated into two sheets. ×: The laminated film sample remained completely unchanged compared to before the test and did not detach.

[0130] (Results of the examples) The results of Examples 5 and 6 are shown in Table 3.

[0131]

Table 3

Claims

1. A laminate comprising a first base film, a second base film, and an adhesive layer disposed between the first base film and the second base film, wherein the first and second base films are made of a thermoplastic resin mainly composed of an olefin resin, and the adhesive layer is made of an adhesive satisfying any one of (1), (2), or (3). (1) A polypropylene resin modified with maleic anhydride, having a polypropylene content of 70 to 99 mol% and a modification rate of maleic anhydride of 0.1 mol% or more. (2) A polyethylene resin modified with maleic anhydride, having a polyethylene content of 70 to 99 mol% and a modification rate of maleic anhydride of 0.1 mol% or more. (3) A polyethylene resin modified with vinyl acetate, having a modification rate of vinyl acetate of 5 to 20 mol% or more.

2. Recycled plastic using the laminate according to Claim 1 as a raw material.

3. A method for producing recycled plastic using the laminate according to Claim 1 as a raw material, the method comprising a step of crushing the laminate according to Claim 1, a step of immersing in a peeling liquid to separate the laminate into each layer, a step of recovering each separated layer, a step of melt-kneading the recovered crushed pieces, and a step of pelletizing the melt-kneaded kneaded product.

Images