Method for producing plastic film

Abstract

Provided are: a method for producing a plastic film using recycled plastic as a raw material, the content of polyolefin resin in the recycled plastic being 80 mass% or more, the nitrogen concentration being in the range of 0.01-2.0 mass%, and the film being molded by any of a T-die method, an inflation method, or a calender molding method; and a method for producing a laminate, a packaging material, and a lid using the method for producing a plastic film. The recycled plastic is preferably a recycled plastic obtained by crushing, then melting and kneading a plastic laminate having at least a first resin layer, an adhesive layer and / or a printing layer, and a second resin layer.

Description

Plastic film manufacturing method

[0001] The present invention relates to a method for producing a plastic film using recycled plastic as a raw material.

[0002] In recent years, environmental pollution caused by the disposal and dumping of plastic products has become a problem, and there has been an increasing demand for the recycling of plastic products and the reuse of recycled plastics. Accordingly, studies have begun on methods for recycling plastic laminates for packaging materials, which are considered difficult to recycle, and on the utilization of recycled plastics obtained after recycling.

[0003] One reason why recycling plastic laminates for packaging materials is considered difficult is that many plastic laminates have complex multilayer structures that must meet different performance requirements for each application. For example, in the case of food packaging, a laminated laminate is often used in which a first substrate layer, a printed layer, and a second substrate layer are firmly bonded together with a cross-linkable adhesive to protect the food contents. Furthermore, the resins used in each substrate layer are often polyester resin, nylon resin, polystyrene resin, polypropylene resin, polyethylene resin, or other resins, and are often used alone or in combination depending on the required characteristics. In other words, the method of separating the individual components to obtain a plastic made of a single resin, which is considered to be high-quality recycled plastic, has been extremely difficult in the case of plastic laminates for packaging materials.

[0004] Furthermore, when recycling materials such as nylon and polyester resins, which are more hygroscopic than olefin-based resins and are prone to decomposition and thermal degradation, especially in environments where moisture and heat coexist, a quality defect known as "eye gunk" often occurs during extrusion molding using a die. This occurs when thermoplastic resin degradation products, some of the additives, or their oxides and decomposition products adhere to the open-air surface like "eye gunk." These accumulate on the open-air surface during sheet molding and further deteriorate thermally. When these deposits come into contact with the sheet material extruded from the die, they create convex or concave streaks on the surface. In the early stages of this "eye gunk" development, the "eye gunk" itself tends to create concave streaks on the surface of the sheet material. However, as the "eye gunk" develops, it tends to act as a nucleus, drawing in the adjacent thermoplastic resin and forming convex streaks. Furthermore, if extrusion molding is continued for a long period of time, the "eye gunk" gradually accumulates at the die outlet, and if left in this state, the "eye gunk" will adhere to the molded body such as a strand or sheet and become a foreign object that may become mixed into the final product, reducing its quality. It may also clog the die outlet, making it impossible to perform extrusion molding at all.

[0005] On the other hand, even when recycled plastics are primarily made from a single type of resin, their applications remain limited. This is due to the fact that recycled plastics are often subjected to excessive heat during processes such as melting and extrusion, resulting in brittleness and poor stretchability compared to virgin resins (obtained from virgin raw materials). Packaging films are produced using molding methods such as the T-die method, inflation method, and calendar molding, as well as the co-extrusion multilayer T-die method used for multilayer molding. The raw resin is melted and extruded, then cooled on a cooling roll and wound up, resulting in films with thicknesses ranging from several micrometers to several hundred micrometers. However, when brittle, difficult-to-stretch recycled plastics are used as raw materials, there is a risk of holes and tears occurring during the entire process. Furthermore, when the resulting film is stretched, significant thickness non-uniformity in the molded product, which is not noticeable in the unstretched state, may occur.

[0006] Monomaterialization, which involves unifying the main resin material of the original plastic laminate into a single type, has been considered as a method for obtaining high-quality recycled plastic from plastic laminates used for packaging materials. For example, Patent Document 1 discloses recycled plastics made from a laminate film containing first and second substrates made of a thermoplastic resin primarily composed of an olefin resin, and an adhesive between the first and second substrates, the laminate film including an olefin resin having acid groups, acid anhydride groups, and / or hydroxyl groups, and a crosslinking agent. Patent Document 2 also discloses a method for producing recycled plastics, which includes at least a first resin layer, an adhesive layer and / or a printed layer, and a second resin layer, and in which the polyolefin resin content is 80% by mass or more based on the total mass of the plastic laminate, and the plastic laminate has not undergone a process of separating or detaching the adhesive layer or the printed layer. In the future, there is a demand for a method for stably producing plastic films using these recycled plastics as raw materials for packaging films by molding methods such as the T-die method, inflation method, calendar molding method, or coextrusion multilayer T-die method.

[0007] JP 2023-106376 A Patent No. 7425948 A

[0008] An object of the present invention is to provide a method for stably producing a plastic film using recycled plastic as a raw material for a packaging film by a molding method such as the T-die method, inflation method, calendar molding method, or coextrusion multilayer T-die method.

[0009] As a result of extensive research, the present inventors have found that by using recycled plastic as a raw material, which has a polyolefin resin content of 80% by mass or more and a nitrogen concentration in the range of 0.01 to 2.0% by mass, a film-molded plastic film can be stably produced by the T-die method, inflation method, calendar molding method, or co-extrusion multilayer T-die method.

[0010] By ensuring that the polyolefin resin content is 80% by mass or more and the nitrogen concentration is in the range of 0.01 to 2.0% by mass, a stable melt flow rate can be obtained. In addition, because the film has excellent elongation during melting, there is little risk of holes or tears occurring during the film forming process, making it possible to obtain a film worthy of practical use.

[0011] That is, the present invention provides a method for producing a plastic film using recycled plastic as a raw material, wherein the recycled plastic has a polyolefin resin content of 80% by mass or more and a nitrogen concentration in the range of 0.01 to 2.0% by mass, and the method is formed into a film by any of a T-die method, an inflation method, or a calendar molding method.

[0012] The present invention also provides a method for producing a laminate using the plastic film obtained by the above-described production method.

[0013] The present invention also provides a method for producing a packaging material using the plastic film obtained by the above-described production method.

[0014] The present invention also provides a method for producing a lid material using the plastic film obtained by the above-described production method.

[0015] According to the present invention, plastic films can be stably produced using recycled plastics as the raw material for packaging films by molding methods such as the T-die method, inflation method, calendar molding method, or co-extrusion multilayer T-die method, and these films can be used to develop a variety of packaging components such as laminates, packaging materials, and lid materials.

[0016] (Recycled Plastic) The recycled plastic used in the present invention is characterized in that the content of polyolefin resin in the recycled plastic is 80% by mass or more and the nitrogen concentration is in the range of 0.01 to 2.0% by mass.

[0017] (Polyolefin Resin Content) The polyolefin resin content in recycled plastics can be determined by, for example, infrared spectroscopy (IR), differential scanning calorimetry (DSC), or nuclear magnetic resonance (NMR). In addition, when the main raw material of recycled plastics is a plastic laminate, it can also be calculated by converting from the mass% of the polyolefin resin layer constituting the plastic laminate. For example, when a plastic laminate has a multilayer structure including a layer such as a substrate using a polyolefin resin, and the total mass of the plastic laminate is used as the basis, the polyolefin resin content is calculated by formula (1).

[0018] (Mass of polyolefin resin in plastic laminate) / (Mass of plastic laminate) × 100 (1)

[0019] The content of polyolefin resin in the recycled plastic is 80% by mass or more, preferably 85% by mass or more, with the upper limit being 100% by mass.

[0020] (Nitrogen Concentration in Recycled Plastics) The nitrogen concentration in recycled plastics can be determined, for example, by CHN measurement using an organic elemental analyzer. Furthermore, when the main raw material of the recycled plastic is a plastic laminate, the nitrogen concentration can also be calculated by converting it from the nitrogen mass % of the nitrogen-containing raw materials that make up the plastic laminate, such as urethane resin, amino resin, melamine resin, etc. For example, when a plastic laminate has a multilayer structure including a layer such as a substrate using a polyolefin resin, and the total mass of the plastic laminate is used as the basis, the nitrogen concentration content can be calculated using formula (2).

[0021] (Mass of nitrogen in plastic laminate) / (Mass of plastic laminate)×100 (2)

[0022] The nitrogen concentration in the recycled plastic is in the range of 0.01 to 2.0% by mass, and preferably 0.03 to 1.2% by mass. By keeping it in this range, the effects of the present invention can be maximized.

[0023] (Plastic laminate as raw material for recycled plastic) In the present invention, a plastic laminate can be used as a raw material for recycled plastic. Currently, plastic laminates having various configurations are available in the market for a variety of uses. For example, there are laminates having a laminate structure in which a printed layer is simply provided on a resin layer serving as a base material, as well as laminate structures in which multiple resin layers, printed layers, and functional layers are bonded and laminated with an adhesive. Here, as an example, we will describe the most commonly available plastic laminate, which has at least a first resin layer, an adhesive layer and / or a printed layer, and a second resin layer.

[0024] (First and / or second resin layer) The first and / or second resin layer can be any film or sheet (unless otherwise specified below, film is a general term for film and sheet) that has excellent chemical and physical strength. Since these resin layers determine the content of polyolefin resin in the recycled plastic of the present invention, it is preferable that both the first and / or second resin layers are composed of polyolefin resin so that the content of polyolefin resin in the recycled plastic is 80% by mass or more. On the other hand, other resin layers may be present as long as the content is less than 20% by mass. Hereinafter, in the present invention, the resin layer may be referred to as a resin film layer.

[0025] Specific examples of the polyolefin resin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear (linear) low-density polyethylene; polypropylene; ethylene-propylene copolymers; α-olefin polymers; ethylene-vinyl acetate copolymers; ethylene-vinyl alcohol copolymers; ethylene-acrylic acid copolymers; ethylene-methyl methacrylate copolymers; ethylene-ethyl acrylate copolymers; cyclic olefin resins; ionomer resins; and modified polyolefin resins obtained by modifying olefin resins with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, or other unsaturated carboxylic acids.

[0026] It is also preferable to use a film formed from a material containing biomass-derived components as the resin film layer. Biomass films are commercially available from various companies, and for example, sheets such as those listed in the list of biomass-certified products listed by the Japan Organics Recycling Association can be used.

[0027] Specifically, well-known films are made from biomass-derived ethylene glycol. Biomass-derived ethylene glycol is made from ethanol (biomass ethanol) produced from biomass as a raw material. For example, biomass-derived ethylene glycol can be obtained by converting biomass ethanol into ethylene oxide by a conventionally known method to produce ethylene glycol. Alternatively, commercially available biomass ethylene glycol may be used; for example, biomass ethylene glycol commercially available from India Glycoal Limited can be suitably used.

[0028] Alternatively, products using biomass raw materials classified by the biomass plastic content specified in ISO 16620 or ASTM D6866 are also on the market. Radioactive carbon-14C exists in the atmosphere at a rate of 1 in 1012 particles, and this rate is the same for atmospheric carbon dioxide, so this rate remains the same even in plants that fix this carbon dioxide through photosynthesis. Therefore, the carbon in plant-derived resins contains radioactive carbon-14C. In contrast, the carbon in fossil fuel-derived resins contains almost no radioactive carbon-14C. Therefore, by measuring the concentration of radioactive carbon-14C in the resin using an accelerator mass spectrometer, the plant-derived resin content in the resin, i.e., the biomass plastic content, can be determined. Examples of plant-derived low-density polyethylene, which is a biomass plastic having a biomass plastic content of 80% or more, preferably 90% or more as specified by ISO 16620 or ASTM D6866, include products manufactured by Braskem under the trade names "SBC818," "SPB608," "SBF0323HC," "STN7006," "SEB853," and "SPB681," and films using these as raw materials can be suitably used.

[0029] For example, biomass polyolefin films, such as biomass polyethylene films and biomass polyethylene-polypropylene films, containing polyethylene resins made from biomass-derived ethylene glycol are known as alternatives to conventional polyolefin films made from petroleum-based raw materials. The polyethylene resin is not particularly limited except that biomass-derived ethylene glycol is used as part of the raw material. Examples of the polyethylene resin include ethylene homopolymers and copolymers of ethylene and α-olefins containing ethylene as the main component (ethylene-α-olefin copolymers containing 90% by mass or more of ethylene units). These can be used alone or in combination of two or more. The α-olefin constituting the copolymer of ethylene and 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 resins, medium-density polyethylene resins, and linear low-density polyethylene resins, can be used. Among these, from the viewpoint of making it more difficult for damage such as holes or tears to occur even when films are rubbed 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 preferred, and a density of 0.900 to 0.950 g / cm ３ More preferred is a linear low density polyethylene resin in which

[0030] The biomass film may be a laminate of multiple biomass films, or may be a laminate of a conventional petroleum-based film and a biomass film.

[0031] The resin film layer may be subjected to any surface treatment, such as a physical treatment such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, or flame treatment, or a chemical treatment such as oxidation treatment using chemicals, or other treatments.

[0032] The resin film layer can be produced from the above-mentioned resin by a conventionally known film-forming method such as extrusion, cast molding, T-die molding, cutting, inflation molding, calendar molding, etc. The film may be an unstretched film, or may be one that has been stretched uniaxially or biaxially using a tenter system, a tubular system, or the like from the viewpoint of film strength, dimensional stability, and heat resistance.

[0033] The resin film layer may contain additives as needed. Specifically, plastic compounding agents and additives such as elastomers, lubricants, crosslinking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, and pigments may be added for the purpose of improving or modifying processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slipperiness, mold releasability, flame retardancy, mildew resistance, electrical properties, strength, etc. The amount of additive added is adjusted within a range that does not affect other properties or recyclability.

[0034] The thickness of the resin film layer is not particularly limited and may be appropriately selected from the range of 0.1 to 300 μm in terms of formability and transparency. It is preferably in the range of 0.3 to 100 μm. If the thickness is less than 0.1 μm, the strength may be insufficient, and if it exceeds 300 μm, the rigidity may be too high, making processing difficult.

[0035] (Barrier Layer) The resin film layer may optionally be provided with a barrier layer for the purpose of providing barrier properties against water vapor, oxygen, alcohol, inert gases, volatile organic compounds (aromas), etc. Resin films containing 80% or more by mass of polyolefin resin, particularly polyethylene resins, tend to have poor gas barrier properties when used, for example, for food packaging. Therefore, the provision of a barrier layer is preferable. Typical barrier layers include a vapor-deposited layer formed by vapor-depositing a metal or inorganic compound, or a gas barrier coating layer made primarily from a material known to have gas barrier properties, such as an inorganic compound or a vinyl alcohol-based polymer. On the other hand, when recycled plastic is used as the raw material for a packaging film, which is the subject of the present invention, it is preferable to provide a vapor-deposited layer formed by vapor-depositing a metal oxide or inorganic compound, a gas barrier coating layer coated and dried with a gas barrier coating agent made primarily from a material known to have gas barrier properties, such as an inorganic compound or a water-soluble polymer having a hydroxyl group, or a combination thereof, rather than a metal vapor-deposited layer.

[0036] (Vapor-deposited layer) As the vapor-deposited layer of a metal oxide or an inorganic compound, for example, aluminum oxide (AlOx), silicon oxide (SiOx), silicon oxide (SiOx), zinc oxide, magnesium oxide, calcium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, etc. These metals or inorganic compounds may be used alone or in combination of two or more.

[0037] (Gas Barrier Coating Layer) Examples of gas barrier coating agents primarily composed of a water-soluble polymer having a hydroxyl group include aqueous coating agents containing a vinyl alcohol polymer, polyvinylpyrrolidone, starch, methylcellulose, carboxymethylcellulose, sodium alginate, etc., and, if necessary, additives such as a layered inorganic compound, a crosslinking agent reactive with the functional group of the vinyl alcohol polymer, an adhesion improver, an inorganic filler, an antifoaming agent, a stabilizer (antioxidant, heat stabilizer, UV absorber, etc.), a plasticizer, an antistatic agent, a lubricant, an antiblocking agent, a colorant, and a leveling agent. Specific examples of vinyl alcohol polymers that can best impart gas barrier properties include polyvinyl alcohol, ethylene vinyl alcohol, and polyvinyl butyral. The vinyl alcohol polymer may have a reactive functional group other than a hydroxyl group, such as an acetoacetyl group, a carboxyl group, an anionic carboxyl group, a sulfonic acid group, or an anionic sulfonic acid group. These may be used alone or in combination of two or more. These may be commercially available products, and examples thereof include EXEVIA (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., the SunBar (registered trademark) series manufactured by Sun Chemical Co., Ltd., the Takelac WPB (registered trademark) series manufactured by Mitsui Chemicals, Inc., and LG-OX manufactured by Tokyo Ink Co., Ltd.

[0038] As a solvent-based gas barrier coating agent, for example, SB-504 / SA-201 series manufactured by DIC Corporation can also be used.

[0039] Alternatively, silicon compounds or hydrolysates of the silicon compounds, for example, tetraalkoxysilanes such as tetraethylsilicate (Si(OC2H5)4) (hereinafter sometimes referred to as TEOS) and tetramethylsilicate; trialkoxysilanes such as trimethoxymethylsilane, triethoxymethylsilane, and trimethoxyvinylsilane; dialkoxysilanes such as dimethoxydimethylsilane and diethoxydimethylsilane; monoalkoxysilanes such as methoxytrimethylsilane and ethoxytrimethylsilane, or hydrolysates or partial hydrolysates thereof, are also known to be used in the gas barrier coat layer, and a combination of these may also be used to form the gas barrier coat layer.

[0040] The resin film layer may further be provided with a coating layer, if necessary, for the purpose of improving ink receptivity when a printing layer, which will be described later, is provided, or a coating layer that imparts functionality, such as heat resistance or heat sealability, may be provided.

[0041] (Adhesive Layer) The adhesive layer may be a layer obtained by drying and solidifying or crosslinking and curing an adhesive used in a general-purpose lamination method. Examples of the lamination method include dry lamination, wet lamination, non-solvent lamination, and extrusion lamination. The adhesive becomes an adhesive layer after curing or drying.

[0042] Examples of adhesives used in the dry lamination include one-component or two-component curing or non-curing vinyl, (meth)acrylic, polyamide, polyester, polyether, polyurethane, epoxy, rubber, and other solvent-based, water-based, or emulsion-based adhesives. Examples of two-component curing adhesives include two-component curing adhesives made of a polyol composition and an isocyanate composition. Various pressure-sensitive adhesives, such as pressure-sensitive adhesives, may also be used. Examples of pressure-sensitive adhesives include rubber-based adhesives obtained by dissolving polyisobutylene rubber, butyl rubber, or mixtures thereof in an organic solvent such as benzene, toluene, xylene, or hexane; or these rubber-based adhesives blended with a tackifier such as abiethylene acid rosin ester, terpene-phenol copolymer, or terpene-indene copolymer; and acrylic-based adhesives obtained by dissolving an acrylic copolymer having a glass transition point of −20° C. or less, such as a 2-ethylhexyl acrylate-n-butyl acrylate copolymer or a 2-ethylhexyl acrylate-ethyl acrylate-methyl methacrylate copolymer, in an organic solvent.

[0043] In the present invention, it has been found that the effects of the present invention can be maximized when a two-component curing adhesive of a polyol composition and an isocyanate composition is used as the adhesive for the plastic laminate so that the nitrogen concentration in the recycled plastic is at least 0.03 to 1 mass %.

[0044] The polyol composition contains polyols such as polyester polyols, polyether polyols, vegetable oil polyols, polyurethane polyols, sugar alcohols, etc. These polyols may be used in combination of two or more kinds.

[0045] Examples of polyester polyols include polyester polyols which are reaction products of polyhydric alcohols and polycarboxylic acids, and lactone-based polyester polyols obtained by polycondensation reaction of aliphatic polyols with various lactones such as ε-caprolactone. It is preferable to use polyester polyols which are reaction products of polyhydric alcohols and polycarboxylic acids.

[0046] Examples of polyhydric alcohols include aliphatic diols such as ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,2,2-trimethyl-1,3-propanediol, 2,2-dimethyl-3-isopropyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,4-bis(hydroxymethyl)cyclohexane, and 2,2,4-trimethyl-1,3-pentanediol;

[0047] aliphatic polyols having three or more functional groups, such as trimethylolethane, trimethylolpropane, glycerin, hexanetriol, and pentaerythritol;

[0048] Bisphenols such as bisphenol A and bisphenol F; alkylene oxide adducts of bisphenols obtained by adding ethylene oxide, propylene oxide, or the like to bisphenols such as bisphenol A and bisphenol F;

[0049] Examples of such polyether polyols include polyether polyols obtained by ring-opening polymerization of an aliphatic diol or polyol with various cyclic ether bond-containing compounds such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, and allyl glycidyl ether. These polyether polyols may be used alone or in combination of two or more.

[0050] Examples of polycarboxylic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as orthophthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, and 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid; and anhydrides or ester-forming derivatives of these aliphatic or dicarboxylic acids; and polybasic acids such as p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids, and dimer acid, and these may be used alone or in combination of two or more.

[0051] The molecular weight of the polyester polyol is not particularly limited, but an example is a number average molecular weight of from 250 to 20000. The hydroxyl value of the polyester polyol is not particularly limited, but an example is 5 mgKOH / g to 500 mgKOH / g.

[0052] Examples of polyether polyols include those obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, and cyclohexylene in the presence of a polymerization initiator.

[0053] Examples of the polymerization initiator include glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and triethylene glycol;

[0054] trifunctional or tetrafunctional aliphatic alcohols such as glycerin, trimethylolpropane, pentaerythritol, and triols of polypropylene glycol;

[0055] Examples thereof include primary or secondary alkylamines such as ethylamine and diethylamine, amine compounds having a plurality of amino groups such as methylenediamine and ethylenediamine, and amine compounds having an active hydrogen group such as primary or secondary alkanolamines such as monoethanolamine and diethanolamine.

[0056] The molecular weight of the polyether polyol can be adjusted appropriately, but is, for example, 100 g / mol to 8000 g / mol. The hydroxyl value of the polyether polyol can be adjusted appropriately, but is, for example, 10 mgKOH / g to 1200 mgKOH / g.

[0057] Examples of the vegetable oil polyol include castor oil, dehydrated castor oil, hardened castor oil which is a hydrogenated castor oil, and an alkylene oxide 5 to 50 mole adduct of castor oil.

[0058] Polyurethane polyol is a reaction product of a low-molecular-weight or high-molecular-weight polyol and a polyisocyanate compound. The low-molecular-weight or high-molecular-weight polyol may be the same as the polyhydric alcohol exemplified as the raw material for polyester polyol. The polyisocyanate compound may be the same as the polyisocyanate that can be contained in the isocyanate composition described below.

[0059] Examples of sugar alcohols include pentaerythritol, sucrose, xylitol, sorbitol, isomalt, lactitol, maltitol, and mannitol.

[0060] The polyisocyanate composition contains a polyisocyanate compound having multiple isocyanate groups. The polyisocyanate compound is not particularly limited, and examples thereof include aromatic diisocyanates, araliphatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and biuret, nurate, adduct, allophanate, carbodiimide-modified, and uretdione-modified products of these diisocyanates, as well as urethane prepolymers obtained by reacting these polyisocyanates with polyols, and these can be used alone or in combination.

[0061] Examples of aromatic diisocyanates include, but are not limited to, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate (also referred to as polymeric MDI or crude MDI), 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4',4"-triphenylmethane triisocyanate.

[0062] The araliphatic diisocyanate means an aliphatic isocyanate having one or more aromatic rings in the molecule, and examples thereof include, but are not limited to, m- or p-xylylene diisocyanate (also known as XDI), α,α,α',α'-tetramethylxylylene diisocyanate (also known as TMXDI), and the like.

[0063] Examples of aliphatic diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate, but are not limited to these.

[0064] Examples of alicyclic diisocyanates include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, isophorone diisocyanate (also known as IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,4-bis(isocyanatomethyl)cyclohexane, but are not limited to these.

[0065] The polyol used in the synthesis of the urethane prepolymer may be the same as the polyhydric alcohols exemplified as raw materials for the polyester polyols described above, and may be used alone or in combination of two or more. It is preferable to use at least one polyalkylene glycol or polyester polyol having a molecular weight of 200 to 3000 g / mol.

[0066] The adhesive may be solvent-based or solventless. In this specification, a solvent-based adhesive refers to a polyol composition and a polyisocyanate composition containing esters such as ethyl acetate, butyl acetate, and cellosolve acetate; ketones such as acetone, methyl ethyl ketone, isobutyl ketone, and cyclohexanone; ethers such as tetrahydrofuran and dioxane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; and highly soluble organic solvents such as dimethyl sulfoxide and dimethyl sulfamide. A solventless adhesive refers to a composition that is substantially free of these organic solvents. When the organic solvents used as reaction media in the production of the components of the polyol composition and polyisocyanate composition or their raw materials are not completely removed, leaving trace amounts of organic solvent remaining in the polyol composition and polyisocyanate composition, the adhesive is considered to be substantially free of organic solvent. Furthermore, when the polyol composition contains a low-molecular-weight alcohol, the low-molecular-weight alcohol reacts with the polyisocyanate composition to become part of the coating film, and therefore does not need to be volatilized after coating. Therefore, such a form is also treated as a solventless adhesive, and the low molecular weight alcohol is not considered an organic solvent.

[0067] The adhesive may contain components other than the above-mentioned components, such as a urethanization catalyst, an acid anhydride, a coupling agent, a pigment, a plasticizer, a phosphoric acid derivative, etc. These components may be contained in either or both of the polyol composition and the polyisocyanate composition, or may be prepared separately from these and then mixed with the polyol composition and the polyisocyanate composition immediately before application of the adhesive.

[0068] The adhesive is preferably used by blending so that the ratio [NCO] / [OH] of the number of moles of isocyanate groups contained in the polyisocyanate composition [NCO] to the number of moles of hydroxyl groups contained in the polyol composition [OH] is 0.5 to 5.0.

[0069] The adhesive layer is formed by applying an adhesive to either the first resin layer or the second substrate directly or via the first resin layer or any other layer provided, and then bonding it to the other substrate and performing an aging treatment. For example, the aging temperature is room temperature to 70°C, and the aging time is 6 to 240 hours. The amount of adhesive applied is adjusted as appropriate, but for example, it is 1 g / m ２ 5g / m or more ２ The following is the result.

[0070] (Gas barrier adhesive layer) When recycled plastics are used as the raw material for packaging films, which is an object of the present invention, as described above, it is preferable to provide a vapor deposition layer formed by vapor-depositing a metal oxide or an inorganic compound, a gas barrier coating layer formed by coating and drying a gas barrier coating agent whose main ingredient is a material known to have gas barrier properties, such as an inorganic compound or a water-soluble polymer having a hydroxyl group, or a layer formed by combining these, rather than using a vapor-deposited metal layer. On the other hand, because vapor-deposited metal layers have the best barrier properties, it is preferable in some cases to combine them with an adhesive having gas barrier properties as the adhesive.

[0071] Examples of gas barrier adhesives include two-component adhesives comprising a polyol composition (X) containing at least one polyester polyol (A) selected from the following (A1) to (A3), and a polyisocyanate composition (Y) containing a compound having at least two isocyanate groups in one molecule (hereinafter also simply referred to as an isocyanate compound (B)).

[0072] (1) Polyester polyol (A1) obtained by polycondensation of a polycarboxylic acid including an ortho-oriented polycarboxylic acid with a polyhydric alcohol; (2) Polyester polyol (A2) having an isocyanuric ring; and (3) Polyester polyol (A3) having a polymerizable carbon-carbon double bond.

[0073] Examples of ortho-oriented polycarboxylic acids used in the synthesis of polyester polyol (A1) include orthophthalic acid or its acid anhydride, naphthalene 2,3-dicarboxylic acid or its acid anhydride, naphthalene 1,2-dicarboxylic acid or its acid anhydride, anthraquinone 2,3-dicarboxylic acid or its acid anhydride, and 2,3-anthracenecarboxylic acid or its acid anhydride. These compounds may have a substituent on any carbon atom of the aromatic ring. Examples of such substituents include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, and a naphthyl group.

[0074] The polycarboxylic acid used in the synthesis of the polyester polyol (A1) may contain a polycarboxylic acid other than the ortho-orientated polycarboxylic acid. Examples of polycarboxylic acids other than ortho-oriented polycarboxylic acids include aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid; unsaturated bond-containing polycarboxylic acids such as maleic anhydride, maleic acid, and fumaric acid; alicyclic polycarboxylic acids such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; terephthalic acid, isophthalic acid, pyromellitic acid, trimellitic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, and anhydrides or ester-forming derivatives of these dicarboxylic acids, p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and aromatic polycarboxylic acids such as ester-forming derivatives of these dihydroxycarboxylic acids, and the like, and these can be used alone or in combination. Of these, succinic acid, 1,3-cyclopentanedicarboxylic acid, isophthalic acid and acid anhydrides thereof are preferred.

[0075] When the polycarboxylic acid contains a polycarboxylic acid other than an ortho-oriented polycarboxylic acid, the proportion of the ortho-oriented polycarboxylic acid in the total amount of polycarboxylic acids is preferably 40 to 100% by mass.

[0076] The polyhydric alcohol used in the synthesis of the polyester polyol (A1) preferably contains at least one selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanedimethanol, and more preferably contains ethylene glycol.

[0077] The polyhydric alcohol may be used in combination with polyhydric alcohols other than those mentioned above. Examples of the polyhydric alcohol include aliphatic diols such as 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol; trihydric or higher polyhydric alcohols such as glycerin, trimethylolpropane, trimethylolethane, tris(2-hydroxyethyl)isocyanurate, 1,2,4-butanetriol, pentaerythritol, and dipentaerythritol; hydroquinone, resorcinol, catechol, naphthalenediol, biphenol, bisphenol A, bisphenol F, and tetramethylbiphenol; ethylene oxide-extended products thereof; and aromatic polyhydric phenols such as hydrogenated alicyclic phenols.

[0078] When the polyester polyol (A1) has three or more hydroxyl groups (referred to as polyester polyol (a1) for convenience), some of the hydroxyl groups may be modified with acid groups. Such polyester polyols are hereinafter also referred to as polyester polyol (A1'). The polyester polyol (A1') is obtained by reacting the polyester polyol (a1) with a polycarboxylic acid or its acid anhydride. The proportion of hydroxyl groups modified with the polycarboxylic acid is preferably ⅓ or less of the hydroxyl groups in the polyester polyol (a1). Examples of polycarboxylic acids used for modification include, but are not limited to, succinic anhydride, maleic acid, fumaric acid, 1,2-cyclohexanedicarboxylic anhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, phthalic anhydride, 2,3-naphthalenedicarboxylic anhydride, trimellitic anhydride, oleic acid, and sorbic acid.

[0079] The polyester polyol (A2) can be obtained, for example, by reacting a triol having an isocyanuric ring with a polycarboxylic acid including an ortho-oriented aromatic polycarboxylic acid and a polyhydric alcohol. Examples of the triol having an isocyanuric ring include alkylene oxide adducts of isocyanuric acid such as 1,3,5-tris(2-hydroxyethyl)isocyanuric acid and 1,3,5-tris(2-hydroxypropyl)isocyanuric acid. The ortho-oriented aromatic polycarboxylic acid, polycarboxylic acid, and polyhydric alcohol can be the same as those used for the polyester polyol (A1).

[0080] As the triol compound having an isocyanuric ring, 1,3,5-tris(2-hydroxyethyl)isocyanuric acid or 1,3,5-tris(2-hydroxypropyl)isocyanuric acid is preferably used. As the ortho-oriented aromatic polycarboxylic acid, orthophthalic anhydride is preferably used. As the polyhydric alcohol, ethylene glycol is preferably used.

[0081] The polyester polyol (A3) can be obtained by using a component having a polymerizable carbon-carbon double bond as a polycarboxylic acid or a polyhydric alcohol.

[0082] Examples of polycarboxylic acids having a polymerizable carbon-carbon double bond include maleic anhydride, maleic acid, fumaric acid, 4-cyclohexene-1,2-dicarboxylic acid and its acid anhydride, and 3-methyl-4-cyclohexene-1,2-dicarboxylic acid and its acid anhydride. It is believed that the fewer the number of carbon atoms, the less flexible the molecular chain and the less oxygen permeates, so maleic anhydride, maleic acid, and fumaric acid are preferred. Examples of polyhydric alcohols having a polymerizable carbon-carbon double bond include 2-butene-1,4-diol.

[0083] In addition to the above, polycarboxylic acids and polyhydric alcohols not having a polymerizable carbon-carbon double bond may be used in combination. Examples of such polycarboxylic acids and polyhydric alcohols include those similar to those used in polyester polyols (A1) and (A2). The polycarboxylic acid is preferably at least one selected from the group consisting of succinic acid, 1,3-cyclopentanedicarboxylic acid, orthophthalic acid, orthophthalic acid anhydride, and isophthalic acid, and more preferably at least one of orthophthalic acid and its acid anhydride. The polyhydric alcohol is preferably at least one selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanedimethanol, and more preferably ethylene glycol.

[0084] The hydroxyl value of the polyester polyol (A) is preferably 20 mgKOH / g or more and 400 mgKOH / g or less, and preferably 100 mgKOH / g or more and 400 mgKOH / g or less. When the polyester polyol (A) has an acid group, the acid value is preferably 200 mgKOH / g or less. The hydroxyl value of the polyester polyol (A) can be measured by the hydroxyl value measurement method described in JIS-K0070, and the acid value can be measured by the acid value measurement method described in JIS-K0070.

[0085] The number average molecular weight of the polyester polyol (A) is, for example, 300 to 5000. The number average molecular weight can be calculated from the obtained hydroxyl value and the designed number of functional hydroxyl groups.

[0086] The glass transition temperature of the polyester polyol (A) is preferably −30° C. or higher and 80° C. or lower, more preferably 0° C. or higher and 60° C. or lower, and even more preferably 25° C. or higher and 60° C. or lower, in view of the balance between adhesion to the substrate and gas barrier property.

[0087] The polyester polyol (A) may be a polyester polyurethane polyol obtained by urethane elongating the polyester polyols (A1) to (A3) through a reaction with a diisocyanate compound to give a number average molecular weight of 1,000 to 15,000. The urethane-elongated polyester polyol contains components with molecular weights equal to or greater than a certain level and urethane bonds, and therefore has excellent gas barrier properties, excellent initial cohesion, and is an excellent adhesive for lamination.

[0088] The polyisocyanate composition (Y), which is one component of the two-component adhesive having gas barrier properties, contains an isocyanate compound (B). The isocyanate compound (B) can be any known compound without any particular limitation, and examples thereof include tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, or trimers of these isocyanate compounds, and adducts obtained by reacting an excess amount of these isocyanate compounds with low-molecular-weight active hydrogen compounds such as ethylene glycol, propylene glycol, meta-xylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, and meta-xylylenediamine, and alkylene oxide adducts thereof, various polyester resins, polyether polyols, and polymeric active hydrogen compounds of polyamides. Polyester polyisocyanates obtained by reacting polyester polyols (A1) to (A3) with a diisocyanate compound in an isocyanate excess ratio relative to hydroxyl groups may also be used. These may be used alone or in combination of two or more.

[0089] In addition, blocked isocyanates may be used as the isocyanate compound. Examples of the isocyanate blocking agent include phenols such as phenol, thiophenol, methylthiophenol, ethylthiophenol, cresol, xylenol, resorcinol, nitrophenol, and chlorophenol, oximes thereof such as acetoxime, methylethylketoxime, and cyclohexanone oxime, alcohols such as methanol, ethanol, propanol, and butanol, halogen-substituted alcohols such as ethylene chlorohydrin and 1,3-dichloro-2-propanol, tertiary alcohols such as t-butanol and t-pentanol, and lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propylolactam. In addition, aromatic amines, imides, active methylene compounds such as acetylacetone, acetoacetic ester, and ethyl malonate, mercaptans, imines, ureas, diaryl compounds, and sodium bisulfite may also be used. The blocked isocyanate can be obtained by subjecting the above isocyanate compound to an addition reaction with an isocyanate blocking agent by a known, conventional, appropriate method.

[0090] Among these, it is more preferable to use an isocyanate compound having a skeleton derived from xylylene diisocyanate, hydrogenated xylylene diisocyanate, toluene diisocyanate, or diphenylmethane diisocyanate, since good gas barrier properties can be obtained.

[0091] Examples of such isocyanate compounds include a diisocyanate trimer, a biuret compound synthesized by reaction with an amine, and an adduct compound formed by reaction with an alcohol. Compared to trimers and biuret compounds, adduct compounds have better solubility in organic solvents used in solvent-based adhesives, so they are preferably used when the adhesive is solvent-based. As the adduct compound, an adduct compound formed by reaction with an alcohol appropriately selected from the above-mentioned low-molecular-weight active hydrogen compounds can be used, but among them, adduct compounds with ethylene oxide adducts of trimethylolpropane, glycerol, triethanolamine, and metaxylenediamine are preferred.

[0092] Furthermore, when a composition containing a polyester polyol having residual carboxylic acid groups, such as the polyester polyol (A1′), is used as the polyol composition (X), the polyisocyanate composition (Y) may contain an epoxy compound. Examples of the epoxy compound include diglycidyl ether of bisphenol A and its oligomer, diglycidyl ether of hydrogenated bisphenol A and its oligomer, orthophthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, p-oxybenzoic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, succinic acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, ethylene glycol diglycidyl ether, and propylene glycol diglycidyl. ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polyalkylene glycol diglycidyl ethers, trimellitic acid triglycidyl ester, triglycidyl isocyanurate, 1,4-diglycidyloxybenzene, diglycidyl propylene urea, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, triglycidyl ether of glycerol alkylene oxide adduct, and the like.

[0093] When an epoxy compound is used, a commonly known epoxy curing accelerator may be added as needed to accelerate curing, provided that the object of the present invention is not impaired.

[0094] When a composition containing a polyol having a polymerizable carbon-carbon double bond, such as polyester polyol (A3), is used as the polyol composition (X), a known polymerization catalyst can be used in combination to promote the polymerization of the carbon-carbon double bond. Examples of such catalysts include transition metal complexes. The transition metal complexes are not particularly limited as long as they are compounds capable of oxidatively polymerizing the polymerizable double bonds. For example, salts of metals such as cobalt, manganese, lead, calcium, cerium, zirconium, zinc, iron, and copper with octylic acid, naphthenic acid, neodecanoic acid, stearic acid, resin acids, tall oil fatty acids, tung oil fatty acids, linseed oil fatty acids, and soybean oil fatty acids can be used. The amount of the transition metal complex is preferably 0 to 10 parts by mass, more preferably 0 to 3 parts by mass, based on the resin solids content of the polyol composition (X).

[0095] In the present invention, it has been discovered that when a plastic laminate using the gas barrier adhesive is used as the raw material for recycled plastic, the generation of gel in the recycled plastic can be more effectively suppressed. Therefore, the gas barrier adhesive can be more effectively used to form plastic films using the recycled plastic as the raw material.

[0096] (Printed Layer) When the laminate has a printed layer, it is printed with printing ink between the first resin layer and the adhesive layer or on the surface of the first resin layer opposite to the adhesive layer. For example, letters, figures, symbols, or other desired patterns or information are formed.

[0097] The printing method and printing ink are not particularly limited, and known printing methods and printing inks can be used. Printing inks using methods such as gravure printing, flexographic printing, lithographic offset printing, and inkjet recording printing are often used for the films used as the substrate. Printing inks that combine these printing methods with methods of curing using active energy rays such as ultraviolet (UV), LED, and electron beam (EB), or methods of curing using heat, are also used. Depending on the solvent used, inks may be referred to as aqueous inks or organic solvent-based inks.

[0098] Specific examples include gravure printing ink, flexographic printing ink (in some industries, gravure printing ink and flexographic printing ink are sometimes called liquid ink), ultraviolet-curable ink for lithographic offset printing, electron beam-curable ink for lithographic offset printing, ultraviolet-curable ink for inkjet recording and printing, electron beam-curable ink for inkjet recording and printing, etc. Biomass inks made from biomass raw materials are also used as appropriate.

[0099] The printing ink may contain a resin, a colorant, and a solvent as essential components, or may be a so-called clear ink that contains a resin and a solvent but does not substantially contain a colorant. The printing layer may be provided on the entire surface of the first resin layer, or may be provided only on a part of the first resin layer.

[0100] In the present invention, it has been found that the effects of the present invention can be maximized when an ink containing a urethane resin as a raw material is used as the ink for the printing layer of the plastic laminate so that the nitrogen concentration in the recycled plastic is at least 0.2% by mass or less.Furthermore, when a two-component curing adhesive consisting of the polyol composition and the isocyanate composition is used as the adhesive for the adhesive layer, it has been found that the effects of the present invention can be maximized when the sum of the two components is used so that the nitrogen concentration in the recycled plastic is at least 0.03 to 1% by mass.

[0101] Taking the case where the printing ink is a gravure printing ink or a flexographic printing ink as an example, the resin used in the printing ink is not particularly limited, and examples thereof include 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 acetal obtained by reacting vinyl acetate resin with an aldehyde such as butyl aldehyde under acidic conditions, 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., and one or more of these can be used in combination. Preferably, at least one or two or more selected from polyurethane resin and polyvinyl acetal are used. Furthermore, the resins used in the printing ink preferably contain 0.8 mass % or less of chlorine-containing resins such as vinyl chloride-vinyl acetate copolymer resins and resins having nitro groups such as nitrocellulose resins.It is also preferable that the printing ink does not contain chlorine-containing resins such as vinyl chloride-vinyl acetate copolymer resins or resins having nitro groups such as nitrocellulose resins.

[0102] Colorants used in printing inks include inorganic pigments such as titanium oxide, red iron oxide, antimony red, cadmium red, cadmium yellow, cobalt blue, Prussian blue, ultramarine, carbon black, and graphite; organic pigments such as soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments; and extender pigments such as calcium carbonate, kaolin clay, barium sulfate, aluminum hydroxide, and talc.

[0103] The organic solvent used in the printing ink preferably does not contain an aromatic hydrocarbon organic solvent. More specific examples include alcohol organic solvents such as methanol, ethanol, n-propanol, isopropanol, and butanol, ketone organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ester organic solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate, aliphatic hydrocarbon organic solvents such as n-hexane, n-heptane, and n-octane, and alicyclic hydrocarbon organic solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, and cyclooctane, and these can be used alone or in combination of two or more.

[0104] In consideration of the establishment of a recycling-oriented society that should continue to develop (sustainability), it is also preferable that the liquid printing ink used in the present invention is a gravure printing ink or a flexographic printing ink that uses plant-derived raw materials.

[0105] Examples of plant-derived raw materials include cellulose resins such as cellulose acetate propionate resin and nitrocellulose; polyamide resins using dimer acids or polymerized fatty acids derived from natural oils such as soybean oil, palm oil, and rice bran oil; biomass polyurethanes synthesized from plant-derived raw materials such as polycarboxylic acids such as succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dimer acid, glutaric acid, and malic acid; polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, pentylene glycol, 1,10-dodecanediol, dimer diol, and isosorbide; and polyisocyanates such as 1,5-pentamethylene diisocyanate and dimer diisocyanate; and rosin resins.

[0106] As the biomass gravure printing ink or flexographic printing ink, commercially available products listed by the Japan Organics Recycling Association can also be used.

[0107] The area of ​​the printed layer occupies preferably 50% or less of the area of ​​the laminate or packaging material. The printed layer is preferably provided so as to have a light color. Specifically, the density measured using a densitometer with ISO status T, a viewing angle of 2°, and a light source D50 as the density standard is preferably 0.8 or less, more preferably 0.5 or less. For example, an eXactAdvance manufactured by X-rite Corporation can be used as the densitometer.

[0108] As an example of a specific embodiment, a plastic laminate having at least a first resin layer, an adhesive layer and / or a printed layer, and a second resin layer has been described above as an example of the most commonly distributed plastic laminate. However, the plastic laminate that serves as the raw material for the recycled plastic used in the present invention is not limited to this, and any plastic laminate that satisfies the requirements that the polyolefin resin content in the resulting recycled plastic is 80% by mass or more and the nitrogen concentration is in the range of 0.01 to 2.0% by mass can be used.

[0109] Examples include plastic laminates in which a printed layer is directly laminated on a first resin layer, and plastic laminates having a first resin layer, an adhesive layer and / or a printed layer, a second resin layer, and in addition, a metal vapor deposition layer, an inorganic vapor deposition layer, various coating layers, a third resin layer, etc. Packaging materials using the plastic laminates can also be used. Furthermore, if the process for producing recycled plastic includes a step of impregnating the substrates with a desorption treatment solution or the like to separate them into respective substrates, a primer layer that facilitates desorption and separation may be laminated.

[0110] (Method for producing recycled plastic) The recycled plastic can be obtained by crushing (pulverizing) the plastic laminate or packaging material using the plastic laminate, etc., and then melt-kneading the crushed film pieces. As an example of a specific embodiment, recycled plastic can be obtained by a production method including the steps of: impregnating the plastic laminate or packaging material using the plastic laminate with a desorption treatment liquid, for example, to separate and separate the recovered material into each substrate; or directly crushing the plastic laminate or packaging material using the plastic laminate itself; melt-kneading the crushed film pieces; and pelletizing the melt-kneaded mixture.

[0111] (Crushing Step) In the crushing step, the laminate or packaging material is crushed (including cutting) into small rectangular pieces with sides of about 1 to 50 mm, preferably about 3 to 30 mm, and more preferably about 3 to 15 mm. The crushing method may be a so-called wet crushing method in which crushing is performed in water or a cleaning solution, or a dry crushing method in which crushing is performed in an air atmosphere in the absence of a liquid such as a solvent.

[0112] The wet crusher is not particularly limited, but is preferably a wet crusher that can crush, disperse, mix, and pump solids in a liquid simultaneously. Specifically, it is preferably a crusher that has a mechanism for crushing solids in a liquid by shear force and / or friction force, and also has a mechanism for crushing and pumping plastic films. Examples of such wet crushers include a wet crushing pump, a colloid mill, and an attritor.

[0113] The dry crusher is not particularly limited, but examples of the dry crusher that can be used include a mycoloider, a mass colloider, a ball mill, a power mill, a pin mill, an airflow crusher (jet mill), a shear friction crusher, a cutter crusher, an impact crusher (hammer mill, ball mill), a roll crusher, a homogenizer, and an ultrasonic crusher.

[0114] (Separation / Desorption Process) The separation / desorption process may be performed before the laminate or packaging material is crushed, but it is more efficient and preferable to perform it after crushing. The separation / desorption process is a process in which the laminate or packaging material before or after crushing is impregnated with a desorption treatment liquid to obtain recovered materials separated into each substrate. Specifically, for example, the laminate or packaging material is immersed in a desorption treatment liquid to desorb other layers provided on the substrate from the substrate. Note that desorption refers to the separation of the substrate from other layers by the desorption layer being dissolved or swelled by the desorption treatment liquid and peeled off.

[0115] (Removal Treatment Liquid) The release treatment liquid can be appropriately selected as long as it swells and dissolves the adhesive layer, printed layer, etc. in the laminate or packaging material. Examples of such release liquids include water, an alkaline solution, and an acidic aqueous solution. From the viewpoint of releasing the materials of the adhesive layer and printed layer that are commonly used in packaging materials, the release treatment liquid is preferably an alkaline solution containing an inorganic base.

[0116] (Inorganic Base) Specific examples of the inorganic base include sodium hydroxide, potassium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium dihydrogen carbonate, and potassium dihydrogen carbonate. These inorganic bases are contained in a concentration of 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, based on the total weight of the aqueous solution. The pH is preferably 9 or higher, and more preferably 10 or higher.

[0117] (Surfactant) The desorption treatment solution may contain a surfactant. The surfactant is not particularly limited, and known surfactants can be used, such as anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Among these, anionic surfactants, nonionic surfactants, and amphoteric surfactants are preferred.

[0118] Examples of anionic surfactants include alkylbenzenesulfonates, alkylphenylsulfonates, alkylnaphthalenesulfonates, higher fatty acid salts, sulfate ester salts of higher fatty acid esters, sulfonates of higher fatty acid esters, sulfate ester salts and sulfonates of higher alcohol ethers, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, and polyoxyethylene alkyl ether phosphates. Specific examples of these include dodecylbenzenesulfonate, isopropylnaphthalenesulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, and dibutylphenylphenol disulfonate.

[0119] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl 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 alkylamines, polyoxyethylene fatty acid amides, fatty acid alkylolamides, alkylalkanolamides, acetylene glycol, oxyethylene adducts of acetylene glycol, and polyethylene glycol polypropylene glycol block copolymers. Of these, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkylolamides, acetylene glycol, oxyethylene adducts of acetylene glycol, and polyethylene glycol polypropylene glycol block copolymers are preferred.

[0120] Other surfactants that can be used include silicone surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers; and biosurfactants such as spiculisporic acid, rhamnolipid, and lysolecithin.

[0121] These surfactants can be used alone or in combination of two or more. When a surfactant is added, the amount added is preferably in the range of 0.001 to 2 mass %, more preferably 0.001 to 1.5 mass %, and even more preferably 0.01 to 1 mass %, based on the total amount of the desorption treatment solution.

[0122] (Water-soluble organic solvent) The desorption treatment liquid may contain a water-soluble organic solvent. Examples of the water-soluble organic solvent include water-soluble alcohol and water-soluble glycol ether-based organic solvents. Specific examples include 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 (methyl carbitol), diethylene glycol mono ...methyl carbitol), diethylene glycol monoethyl ether (diethyl carbitol), diethylene glycol monobutyl ether (butyl carbitol), diethylene glycol dibutyl ether, triethylene glycol monomethyl ether (methyl carbitol), diethylene glycol monoethyl ether (methyl carbitol), diethylene glycol monoethyl ether (diethyl carbitol), diethylene glycol monoethyl ether (butyl carbitol), diethylene glycol dibutyl ether, triethylene glycol monoethyl ether (butyl carbitol), diethylene glycol monoethyl ether (butyl carbitol), diethylene glycol monoethyl ether (butyl carbitol), diethylene glycol monoethyl ether (butyl carbitol), diethylene glycol monoethyl ether (butyl carbitol Examples include methyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, methylene dimethyl ether (methylal), propylene glycol monobutyl ether, tetrahydrofuran, acetone, diacetone alcohol, acetonyl acetone, acetyl acetone, 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, which can be used alone or in combination of two or more.

[0123] The content of the water-soluble organic solvent in the desorption treatment liquid is preferably 0.1% by mass to 20% by mass, and more preferably 1% by mass to 10% by mass.

[0124] (Non-Water-Soluble Organic Solvent) The desorption treatment liquid may contain a non-water-soluble organic solvent. Specific examples of the non-water-soluble organic solvent include alcohol-based solvents such as n-butanol, 2-butanol, isobutanol, and octanol; aliphatic hydrocarbon-based solvents such as hexane, heptane, and normal paraffin; aromatic hydrocarbon-based solvents such as benzene, toluene, xylene, and alkylbenzene; halogenated hydrocarbon-based solvents such as methylene chloride, 1-chlorobutane, 2-chlorobutane, 3-chlorobutane, and carbon tetrachloride; ester-based solvents such as methyl acetate, ethyl acetate, and butyl acetate; ketone-based solvents such as methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone; and ether-based solvents such as ethyl ether and butyl ether. These may be used alone or in combination of two or more.

[0125] (Antifoaming Agent) The desorption treatment liquid may contain an antifoaming agent. When stirring or crushing the substrate during immersion, a large amount of foam may be generated, and if the foam remains, the foam may overflow during the plastic film recovery process. Furthermore, if a large amount of foam is entrained in the desorption treatment liquid during crushing of the substrate, the substrate may not be crushed to the desired size.

[0126] Compounds commonly used as defoaming agents include water-soluble organic solvents and nonionic surfactants with low HLB values ​​in the range of 1 to 3, but silicone compounds are particularly preferred because of their high defoaming ability, with emulsion-type and self-emulsifying silicone compounds being particularly preferred.

[0127] The amount of the defoaming agent in the cleaning solution usable in step 1 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.

[0128] (Liquid Temperature) The liquid temperature of the desorption treatment liquid is not particularly limited as long as it can maintain a liquid state, but it is usually preferable to perform the treatment at a liquid temperature of 15 to 90°C. When using a desorption treatment liquid in which a surfactant or the like has been added to water, it is preferable to adjust the liquid temperature depending on the type of surfactant. The optimal temperature for excellent cleaning effectiveness varies depending on the type of surfactant, but is preferably 40°C or higher, preferably 65°C or higher, and preferably 85°C or higher. It is also preferable to immerse the target laminate in the desorption treatment liquid, for example, in a treatment tank, while the liquid is heated or ultrasonically vibrated to the above temperature. The heating method is not particularly limited, and known heating methods such as heat rays, infrared rays, and microwaves can be used. Ultrasonic vibration can be used, for example, by attaching an ultrasonic vibrator to the treatment tank and applying ultrasonic vibration to the warm water or alkaline solution.

[0129] (Agitation) Agitation during immersion in the desorption treatment solution is not essential and may be optional, but agitation allows for more efficient swelling. It is preferable to keep the agitation speed at a level that does not cause foaming or the like even without adding an antifoaming agent.

[0130] The equipment and method for stirring are not particularly limited, and known methods can be used. Specific examples include an apparatus equipped with a motor with stirring blades that can stir the cleaning solution in a container, an apparatus equipped with a device that generates ultrasonic waves, an apparatus that can shake the entire container, a wet crusher, a water jet stirring method using a water jet pump, and a bubbling method using an inert gas such as nitrogen gas.

[0131] The time for immersion in the detachment treatment solution varies depending on the configuration of the laminate, but is generally in the range of 2 minutes to 48 hours. Note that in the laminate, it is not necessary for 100% of the coating, such as the printing layer, to be completely detached from the substrate, but it is preferable that 60% by mass or more of the 100% by mass of the coating be detached, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[0132] In the detachment step, the immersion in the detachment treatment solution may be performed once or several times. That is, the immersion may be performed once, followed by a step of recovering the separated film substrate, or the immersion may be performed several times, followed by a step of recovering the film substrate. When immersion is performed multiple times in the detachment step, the concentration of the detachment treatment solution may be changed. Furthermore, known steps such as washing with water and drying may be added as appropriate during the detachment step.

[0133] The detachment treatment liquid also promotes detachment of the plastic substrate by contacting the printed layer, primer layer, or the interface between the substrate and another layer from the edge of the printed material or laminate. Therefore, it is preferable that the printed layer, adhesive layer, or primer layer is exposed on the cross section. For this reason, it is more preferable that the laminate is fragmented in advance by a crushing process.

[0134] After the immersion treatment in the release treatment liquid described above, it is preferable to provide a step of stirring the recovered substrate in water or in the release treatment liquid described above. This step increases the rate at which a coating such as a printed layer is detached from the substrate. The equipment and method for stirring are not particularly limited, and known methods can be used, but stirring is preferably performed using a wet crusher.

[0135] Furthermore, it is preferable to agitate the recovered substrate in a rinse solution for finish washing, thereby cleaning away any ink, adhesive, or other detached material that has re-adhered to the substrate film that has been detached in a single layer. Removing even traces of ink remaining on the film surface significantly improves the quality of the recycled pellets. The equipment and method for agitation in the rinse solution are not particularly limited, and known methods can be used. Specific examples include a device equipped with a motor equipped with agitating blades that can agitate the cleaning solution in a container, a device equipped with a device that generates ultrasonic waves, a device that can shake the entire container, a wet crusher, a kneader, and the like.

[0136] (Recovery and reuse of desorption treatment liquid) The desorption treatment liquid used in the desorption treatment step can be recycled after being recovered by supplying it to one or more recycling machines selected from a filter, a centrifuge, and an ultrafilter, and removing solids. Water, a rinse liquid, etc. can also be recycled in the same way. While wet crushing is being performed, the recycling process of water, desorption treatment liquid, rinse liquid, etc. can be continuously operated to separate solids from the water, washing liquid, and rinse liquid.

[0137] (Drying of Separated Plastics) The separated and recovered laminate pieces and packaging material pieces are dried using one or more methods selected from reduced pressure heating drying, hot air drying, pressurized compression drying, etc. to remove residual moisture from the recovered film pieces. As a pre-treatment for producing recycled pellets (described below), briquettes may be produced after or during drying of the recovered film pieces using a pressurized compressor such as a Nippon Seam compression dehydrator, a Oike Iron Works pellet mill, or an Elcom Stella or briquette machine. When the substrate film is pulverized into powder using a wet grinder, the crushed material is crushed to a size of approximately 10 to 500 μm. Since the crushed material has a high density, the pressurized compression step can be omitted. The density varies depending on the material constituting the crushed material, but a higher density is preferable because it is easier to handle when feeding it into a kneader. Specifically, a dry weight of 0.03 kg or more is preferred, 0.05 kg or more is more preferred, 0.2 kg or more is more preferred, and 0.3 kg or more is even more preferred.

[0138] (Melt-Kneading) As described above, the separation and detachment step is performed as necessary, and the crushed and dried laminate pieces and packaging material pieces are melt-kneaded. An example of a melt-kneader is a melt-kneader equipped with a cylinder having a screw disposed therein and a heat source such as an electric heater. A discharge port may be provided at the tip of the cylinder, and the cylinder may be provided with a supply port such as a hopper for supplying materials. In addition, in order to prevent foreign matter from being mixed into the pellets described below, a screen mesh is preferably provided inside the cylinder closer to the tip than the screw.

[0139] In the melt-kneading section, shearing action caused by the rotation of the screw placed inside the cylinder and heating by an electric heater or the like generates shear heat from the material itself, melting and kneading the material. The material melted and kneaded in the melt-kneading section passes through a screen mesh that is installed as needed and is discharged from the discharge section. The discharge section may be provided with a die having a predetermined shape. The material discharged from the discharge section solidifies or loses its fluidity upon cooling, becoming recycled plastic.

[0140] The screw configuration is not particularly limited. For example, it may have a known structure such as a single-screw extruder, a twin-screw extruder, or a rotor-type twin-screw kneader. In one embodiment, the screw diameter is 15 to 400 mm, preferably 50 to 300 mm, and more preferably 100 to 250 mm. In one embodiment, the screw effective length (L / D) is 15 to 150, preferably 20 to 100, and more preferably 25 to 80. In the screw effective length (L / D), L represents the screw length, and D represents the screw diameter.

[0141] In one embodiment, the screw compression ratio is 2 to 5, preferably 2.5 to 4.5, and more preferably 3.4 to 3.7. The screw compression ratio refers to the ratio (V1 / V2) of the volume per pitch of the screw groove near the supply portion of the recycled plastic material (V1) to the volume per pitch of the screw groove near the discharge portion (V2).

[0142] The material constituting the screw is not particularly limited, and known materials can be used. From the viewpoint of preventing the inclusion of foreign matter due to wear, the screw is preferably made of stainless steel. The surface of the screw can be subjected to various treatments. Examples include nitriding, quenching, and powder metal quenching. From the viewpoint of wear prevention, it is preferable to apply powder metal quenching. As a combination of the constituting material and surface treatment of the screw, a form in which stainless steel is subjected to powder metal quenching is more preferable.

[0143] Examples of the screen mesh include plain weave, twill weave, plain tatami weave, and twill tatami weave, as well as punched metal types. Considering the pressure and clogging of the discharge port, the screen mesh size is preferably 40 mesh or larger, more preferably 80 mesh or larger, and even more preferably 120 mesh or larger. In one embodiment, the screen mesh size is 250 mesh or smaller, preferably 200 mesh or smaller.

[0144] The melting temperature during melt-kneading can be adjusted taking into consideration the glass transition temperature and melting temperature of the polyolefin resin contained, the shape during pelletization, the pressure applied during the molding process, etc. For example, it is 120°C to 280°C, preferably 160 to 250°C. For example, the screw rotation speed during kneading is 50 rpm to 1000 rpm, preferably 80 rpm to 800 rpm, and more preferably 100 to 500 rpm. For example, the shear rate of the screw is 200 to 4000 / sec, preferably 300 to 3500 / sec, and more preferably 400 to 3000 / sec.

[0145] The filling rate of the laminate pieces and packaging material pieces in the extrusion device is, for example, 50 to 100% by volume, preferably 60 to 95% by volume, and more preferably 70 to 90% by volume, relative to the void volume in the extrusion device. The void volume in the extrusion device refers to the cylinder volume minus the screw volume.

[0146] (Pelletization) After melt-kneading the laminate pieces and packaging material pieces, they are extruded from an extruder, cooled, and shredded to form recycled plastic pellets. The resin pressure at the tip discharge section of the extruder (hereinafter also referred to as discharge pressure) is preferably 50 MPa or less, more preferably 40 MPa or less, and even more preferably 30 MPa or less. In one embodiment, the resin discharge pressure at the tip discharge section is 0.01 MPa or more, preferably 0.1 MPa or more, and more preferably 0.5 MPa or more.

[0147] Examples of pelletizing methods include, but are not limited to, hot cutting and strand cutting. Examples of cooling methods include air cooling, wind cooling, and water cooling. In the present invention, it is preferable to include a water cooling step. For example, cooling to 20°C to 80°C is preferable, and cooling to 30°C to 60°C is more preferable.

[0148] (Additives, etc.) The recycled plastic may contain known additives, such as antistatic agents, heat stabilizers, nucleating agents, antioxidants, lubricants, antiblocking agents, release agents, UV absorbers, colorants, and biodegradable agents, to the extent that the object of the present invention is not impaired. There are no particular limitations on the additives, and commercially available additives may also be used.

[0149] In addition to the laminates and packaging materials described above, recycled plastics may also contain petroleum- or biomass-derived olefin-based resins, so-called virgin plastics, as raw materials. The petroleum- or biomass-derived olefin-based resin is preferably the same resin type as the first and second resin layers used in the plastic laminate. It is preferable to appropriately select the polyolefin resin content in the recycled plastic, a feature of the present invention, from 80% by mass or more and a nitrogen concentration in the range of 0.01 to 2.0% by mass. Specifically, the resin mixture used in pelletization preferably contains 0.1 to 99% by mass of the recycled plastic and 99.9 to 1% by mass of a petroleum- or biomass-derived olefin-based resin. It is even more preferable that the resin mixture used in pelletization contains 20 to 80% by mass of the recycled plastic and 80 to 20% by mass of a petroleum- or biomass-derived olefin-based resin.

[0150] The additives and virgin plastics may be supplied to a melt kneader and kneaded simultaneously when pellets of the recycled plastic are produced, or may be supplied simultaneously with pellets of the recycled plastic when producing the plastic film of the present invention, as described below.

[0151] (Method for Producing Plastic Film) As a method for obtaining a plastic film using the recycled plastic as a raw material, any of the T-die method, inflation method and calendar molding method can be used.

[0152] (T-die Method) An example of the T-die method or coextrusion T-die method will be described. The recycled plastic pellets, and optionally virgin plastic pellets and additives, are mixed in a predetermined ratio, dried, and then fed into a known melt lamination extruder. Single-screw or twin-screw extruders can be used as the extruder in the production of the present invention. Furthermore, to eliminate the pellet drying process, the extruder may be equipped with a vacuum line, or a vented extruder can also be used. Furthermore, for layer B, which has the largest extrusion volume, a so-called tandem extruder can be used, in which the function of melting the pellets and the function of maintaining the molten pellets at a constant temperature are shared between the extruders.

[0153] The resin melted and extruded in the extruder is filtered through a filter. Even the smallest foreign particles can become large protrusion defects in the film, so it is effective to use a high-precision filter capable of capturing at least 95% of foreign particles 3 μm or larger. The resin is then extruded into a sheet through a slit die and cooled and solidified on a casting roll to produce an unstretched film. If the film has a single-layer structure, a single-layer manifold is used to extrude the sheet through a die. To obtain a laminated film, such as a three-layer laminated film, three extruders and a three-layer manifold or merging block (e.g., a merging block with a rectangular merging section) are used to laminate the three layers, and the sheet is extruded through a die (coextrusion method). Coextrusion is preferred because it allows for relatively flexible adjustment of the thickness ratio of each layer, resulting in a multilayer film with excellent hygiene and cost performance. On the other hand, when laminating resins with a large difference between their melting points and Tg, the film's appearance may deteriorate during coextrusion processing, or it may be difficult to form a uniform layer structure. In order to suppress such deterioration, the T-die / chill roll method, which allows melt extrusion at a relatively high temperature, is preferred.

[0154] The sheet extruded from the die is cooled by a casting roll to produce an unstretched film. When the resulting unstretched film is stretched, the film is cooled while in close contact with the casting roll, and then peeled off from the casting roll using a peeling roll and introduced into the next stretching step. The stretching method may be simultaneous biaxial stretching or sequential biaxial stretching. When producing a film using sequential stretching, the initial longitudinal stretching is important for preventing scratches and thickness unevenness in the longitudinal direction, and the stretching temperature is 45°C or higher and 180°C or lower, preferably 80°C or higher and 170°C or lower. If the stretching temperature is lower than 45°C, the film is prone to breakage, and if the stretching temperature is higher than 180°C, the film surface is prone to heat damage. From the viewpoint of preventing stretching unevenness and scratches, it is preferable to perform stretching in two or more stages, with a total stretching ratio of 1.1 to 5.0, preferably 3.0 to 4.0, in the longitudinal direction, and 1.1 to 7.0, preferably 3.0 to 5.0, in the width direction. When the longitudinal stretching ratio is set to the above-mentioned values, it is desirable to set multiple stretching sections to make it difficult for slippage to occur between the stretching rolls and the film, in order to suppress fluctuations in the stretching tension due to slippage.

[0155] In sequential stretching, during the longitudinal stretching process, the difference between the circumferential speed of the roll and the speed of the film during contact between the film and the roll makes it easy for the film to slip, resulting in scratches and causing thickness unevenness in the longitudinal direction. Therefore, a drive system in which the circumferential speed of the roll can be set individually for each roll is preferred. In the longitudinal stretching process, the material of the transport roll is selected based on whether the unstretched film is heated to or above its glass transition point before stretching, or whether the film is transported to the stretching zone while maintained at a temperature below its glass transition point and then heated all at once during stretching. When the unstretched film is heated to or above its glass transition point before stretching, adhesion due to heating can cause stretching unevenness. To prevent this, it is preferable to select a material from non-adhesive silicone rolls, ceramics, and Teflon (registered trademark). Furthermore, since the stretching rolls are the step that applies the most load to the film and are prone to stretching irregularities that cause scratches and thickness variations in the longitudinal direction, the surface roughness Ra of the stretching rolls is preferably 0.005 μm or more and 1.0 μm or less, more preferably 0.1 μm or more and 0.6 μm or less. If Ra is greater than 1.0 μm, the unevenness of the roll surface is likely to be transferred to the film surface during stretching, while if it is less than 0.005 μm, the roll and the film surface will stick together, making the film more susceptible to heat damage. In order to control the surface roughness, it is effective to appropriately adjust the particle size of the abrasive, the number of times of grinding, etc.

[0156] In the sequential stretching, setting the longitudinal stretching ratio lower than the transverse stretching ratio is a preferable stretching condition in terms of reducing thickness unevenness in the longitudinal direction.

[0157] The unstretched film is then transported to the stretching zone while maintained at a temperature below the glass transition point. When the film is heated all at once during stretching, it is preferable to use metal rolls in the preheating zone that have been surface-treated with hard chrome or tungsten carbide and have a surface roughness Ra of 0.2 μm or more and 0.6 μm or less, in order to suppress adhesion that causes heat wrinkles.

[0158] Next, the uniaxially stretched film stretched in the longitudinal direction is stretched in the transverse direction in a transverse stretching machine to produce a biaxially stretched (biaxially oriented) film. This transverse stretching machine has self-circulation between each oven chamber, blowing hot air onto the film to raise the temperature of the film and perform stretching and heat setting. To prevent oligomers and volatile components precipitated from the heat-treated film in the oven from cooling and adhering to the oven, it is recommended to supply and exhaust air within the oven to replace the air. If the temperature of the air supplied to the oven remains close to that of the outside air when it merges with the circulating air, temperature unevenness will occur in the air after the merger, which may worsen thickness unevenness in the longitudinal and transverse directions. Therefore, it is preferable to heat the supply air to the same temperature as the circulating air or to a temperature appropriate to the capacity of the heat exchanger that heats the circulating air.

[0159] In the stretching process, re-stretching may be performed one or more times in each direction, or simultaneous biaxial re-stretching may be performed. A method for suppressing thickness unevenness in the longitudinal direction includes alleviating bowing that occurred in the previous transverse stretching process during the longitudinal re-stretching process. In this case, the film may be heated using a transport roll before longitudinal re-stretching, or may be transported using unheated rolls. Furthermore, the film may be passed through the longitudinal re-stretching process without applying a stretching ratio. After longitudinal re-stretching, further transverse stretching is performed, and the film is then heat-treated. This heat treatment can be performed by any conventional method, such as in an oven or on heated rolls. The heat treatment temperature can typically be any temperature between 70°C and 180°C, and the heat treatment time is typically preferably between 1 second and 60 seconds. The heat treatment may be performed while relaxing the film in the longitudinal and / or transverse directions.

[0160] The dimensional change rate and flatness of the heat-treated film can be adjusted by, for example, providing an intermediate cooling zone or a cooling zone. In particular, to impart specific heat shrinkability to the film, the film may be relaxed in the longitudinal and / or transverse directions during or after the heat treatment in the intermediate cooling zone or the cooling zone.

[0161] The biaxially stretched film is cooled in a conveying process, then the edges are cut and wound up to obtain an intermediate product. During this conveying process, the film thickness in the width direction is measured, and the data is used as feedback to adjust the film thickness by adjusting the die thickness, etc., and foreign matter can also be detected using a defect detector.

[0162] Regarding the thickness of the resulting film, for example, when a single-layer film is obtained, the thickness of each layer is preferably 5 to 300 μm, and more preferably 10 to 200 μm. Furthermore, when a film having a three-layer laminate structure is obtained by coextrusion, the thickness of each layer is preferably 1 to 200 μm, and more preferably 2 to 150 μm. The total thickness is preferably 5 to 300 μm, and more preferably 10 to 200 μm.

[0163] (Inflation Method) An example of the inflation method will be described below. Regarding the specifications and molding conditions of the inflation molding machine, for example, the diameter of the extruder is 10 to 600 mm, preferably 20 to 300 mm, and more preferably 25 to 200 mm, and the ratio L / D of the diameter D to the length L from the bottom of the hopper to the tip of the cylinder is 8 to 45, and preferably 12 to 36.

[0164] The die has a shape commonly used in inflation molding, such as a spider, spiral, or stacking flow channel, and has an aperture diameter of 1 to 5,000 mm, preferably 5 to 3,000 mm, and more preferably 10 to 1,800 mm. A commonly used air ring is used to cool the bubble, and known cooling gases can be used. The temperature can be cooled using a chiller or heated using a heater. The bubble can also be cooled using known methods, such as applying cooling air from an external air ring or circulating cooling gas inside. The shape and number of the air ring are not limited, and one or more known types, such as a single slit, dual slit, or one with a chamber, can be provided.

[0165] As for molding conditions, the temperature of the resin extruded from the die is in the range of 140 to 270°C, preferably 180 to 250°C, and the average extrusion speed, determined by the extrusion rate and die shape, is 1 mm / min to 10 m / min, preferably 5 mm / min to 5 m / min, and more preferably 10 mm / min to 1 m / min. The bubbles emerging from the die are expanded by the gas inside, and molding can be performed under molding conditions such that the blow ratio, which is the ratio of the bubble diameter to the die diameter, is in the range of 1.0 to 4.5, preferably 1.5 to 3.5, and the TUR, which is the ratio of the take-up speed to the average flow speed when extruded from the die, is in the range of 2.0 to 200, preferably 10 to 100. The bubble is cooled and solidified, and the height of the frost line from the die exit to the solidification of the bubble varies depending on the film production speed and film thickness, but is in the range of 5 to 1800 mm, preferably 10 to 1200 mm, and more preferably 20 to 800 mm. Regarding the film thickness, for example, when a single-layer film is obtained, the layer thickness is preferably 5 to 300 μm, and more preferably 10 to 200 μm. Furthermore, when a film having a three-layer laminate structure is obtained by coextrusion, the thickness of each layer is preferably 1 to 200 μm, and more preferably 2 to 150 μm. The total film thickness is preferably 5 to 300 μm, and more preferably 10 to 200 μm.

[0166] When pre-kneading is necessary to obtain the sheet or film of the present invention, a known apparatus generally used for thermoplastic resins can be used.

[0167] (Calendar molding method) The calendar molding method will now be described. The set temperature of the calendar molding device during molding is preferably 80 to 180°C, and more preferably 90 to 170°C. If the set temperature is less than 80°C, the sheet may harden during processing, making it impossible to obtain a sheet, or even if a sheet is obtained, there may be many flow marks and bank marks, resulting in a poor appearance. On the other hand, if the temperature exceeds 180°C, the viscosity when melted is low and the fluidity is high, making processing difficult and possibly causing thermal degradation.

[0168] The rotation speed of the calender roll is preferably 5 to 60 m / min, more preferably 10 to 50 m / min. If the rotation speed of the calender roll is less than 5 m / min, the air in the molten material is difficult to remove, which results in defects on the surface of the sheet or film. If the rotation speed of the calender roll is faster than 60 m / min, the sheet or film may become unremovable.

[0169] After biaxially stretching recycled plastics using a calendar molding machine or roll molding machine, the next step involves melt-stretching them in at least one direction, enabling the efficient production of thinner sheets or films. Melt-stretching, as used herein, refers to stretching recycled plastics while they are molten. The stretching ratio during melt-stretching is preferably 120 to 500%, more preferably 130 to 400%, and even more preferably 150 to 350%. When sheets or films are produced at a stretching ratio of less than 120%, the improvement in production efficiency achieved by melt-stretching is minimal. When sheets or films are produced at a stretching ratio of 500% or more, uneven stretching can occur, making it difficult to obtain sheets or films with uniform thickness. Here, the stretching ratio during melt-stretching refers to 100 × [thickness of sheet or film before melt-stretching] / [thickness of sheet or film after melt-stretching].

[0170] The obtained plastic film is preferably produced by biaxially stretching the recycled plastic, melt-stretching it as necessary, and then contacting it with a drum or the like to cool it. The set temperature of the cooling drum is preferably 0 to 120°C, more preferably 20 to 100°C. At temperatures higher than 120°C, cooling is insufficient, making it difficult to take the film after molding, and the obtained plastic film may be deformed. Furthermore, temperatures lower than 0°C are uneconomical because they require a refrigerant or the like.

[0171] The thickness of the obtained plastic film is not particularly limited, but is preferably less than 1.0 mm, more preferably 0.50 mm or less, and even more preferably 0.30 mm or less. If the thickness of the sheet or film is 1 mm or more, the surface smoothness of the sheet or film may be poor. To obtain a sheet or film with a thickness of 1.0 mm or more, it is preferable to produce it by laminating multiple sheets or films with a thickness of less than 1.00 mm. On the other hand, the lower limit of the thickness depends on the molding device, but in consideration of processability and thickness uniformity, it is preferably 0.03 mm or more, and more preferably 0.05 mm or more.

[0172] By combining the above methods, it is possible to obtain, for example, a plastic film having the following laminate structure: (1) A plastic film having at least a resin layer (A) and a resin layer (B) made from recycled plastic. In this case, the method preferably includes the steps of heating and melting a resin mixture (A) containing 0.1 to 99% by mass of the recycled plastic and 99.9 to 1% by mass of an olefin resin derived from petroleum or biomass, and a resin mixture (B), respectively, in an extruder, laminating the molten mixtures (A) and (B) in this order, and molding the mixtures into a film by a T-die method, an inflation method, or a calendar molding method. The lamination step preferably uses the co-extrusion method.

[0173] (2) A plastic film having at least a resin layer (A), a resin layer (B), and a resin (C) made from recycled plastics. In this case, the film preferably includes the steps of heating and melting resin mixture (A), resin mixture (B), and resin mixture (C) each containing 0.1 to 99% by mass of the recycled plastic and 99.9 to 1% by mass of an olefin resin derived from petroleum or biomass in separate extruders, laminating (A), (B), and (C) in the molten state, and forming the resulting film by any of a T-die method, an inflation method, and a calendar molding method, and the lamination step preferably uses the co-extrusion method. Furthermore, in the step of laminating (A), (B), and (C) in a molten state, the order of lamination is not particularly limited, and the layers may be laminated in the order of (A) / (B) / (C), or (A) / (C) / (B), or (B) / (A) / (C), or (B) / (C) / (A).

[0174] The resin mixture (B) or the resin mixture (C) may be a resin mixture consisting solely of a petroleum- or biomass-derived olefin-based resin, or may be a resin mixture containing a petroleum- or biomass-derived olefin-based resin and the recycled plastic. In the case of a resin mixture containing a petroleum- or biomass-derived olefin-based resin and the recycled plastic, it preferably contains 0.1 to 99 mass% of the recycled plastic and 99.9 to 1 mass% of the petroleum- or biomass-derived olefin-based resin.

[0175] The resin mixture (B) and the resin mixture (C) may contain known additives, such as antistatic agents, heat stabilizers, nucleating agents, antioxidants, lubricants, antiblocking agents, mold release agents, ultraviolet absorbers, colorants, and biodegradable agents, within the range that does not impair the object of the present invention. There are no particular limitations on the additives, and commercially available additives may also be used.

[0176] In the plastic film (2) having at least a resin layer (A), a resin layer (B), and a resin (C) made from recycled plastics, it is preferable to have at least the resin layer (A) made from recycled plastics on the inside of the laminated structure, since the resulting plastic film has better film physical properties. The plastic film of the present invention is a film worthy of practical use because it is less likely to be perforated or torn even during the series of film forming processes. However, in applications requiring higher strength during distribution, such as lid materials, a plastic film with better strength can be obtained if the layer structure that will be the outermost during distribution is a resin mixture (B) or a resin mixture (C) made of an olefin resin derived from petroleum or biomass.

[0177] Specifically, the resin mixture (B) made of an olefin-based resin derived from petroleum or biomass / resin mixture (A) containing 0.1 to 99% by mass of the recycled plastic and 99.9 to 1% by mass of an olefin-based resin derived from petroleum or biomass / resin mixture (C) made of an olefin-based resin derived from petroleum or biomass; or alternatively, the resin mixture (B) made of 0.1 to 99% by mass of the recycled plastic and 99.9 to 1% by mass of an olefin-based resin derived from petroleum or biomass / resin mixture (A) containing 0.1 to 99% by mass of the recycled plastic and 99.9 to 1% by mass of an olefin-based resin derived from petroleum or biomass / resin mixture (C) made of an olefin-based resin derived from petroleum or biomass are preferred.

[0178] The surface of the obtained plastic film may be subjected to various surface treatments such as flame treatment and corona discharge treatment as required so that an adhesive layer without defects such as film breakage or repellency is formed.

[0179] The plastic film of the present invention can be obtained as a substantially unstretched multilayer film by the above-mentioned production method, and therefore can be subjected to secondary forming such as deep drawing by vacuum forming or embossing. Also, embossing may be performed by bringing the film into contact with a roll having projections and recesses immediately after forming.

[0180] (Laminate, Packaging Material) The plastic film of the present invention can be laminated with a separate substrate film by, for example, bonding it to form a laminate.

[0181] Examples of the structure of the laminate include, but are not limited to, (1) base film / adhesive layer / plastic film of the present invention; (2) base film / adhesive layer / printed layer / plastic film of the present invention; (3) base film / adhesive layer / second base material / printed layer / adhesive layer / plastic film of the present invention; (4) base film / adhesive layer / first printed layer / second printed layer / plastic film of the present invention; (5) base film / adhesive layer / barrier layer / adhesive layer / plastic film of the present invention; (6) base film / adhesive layer / barrier layer / printed layer / adhesive layer / plastic film of the present invention; (7) base film / printed layer / adhesive layer / plastic film of the present invention; (8) base film / first printed layer / second printed layer / adhesive layer / plastic film of the present invention; (9) base film / printed layer / adhesive layer / barrier layer / adhesive layer / plastic film of the present invention; and the laminate may further include an additional base material.

[0182] The plastic film of the present invention can withstand repeated recycling if it is made into a laminate having the same structure as the laminate used for the recycled plastic that is the raw material of the present invention.

[0183] On the other hand, a laminate may be formed depending on the desired application. For example, the second and additional substrates may be unstretched resin films, stretched resin films, metal-deposited films such as metal-deposited unstretched films and metal-deposited stretched films, transparent vapor-deposited films, or papers such as coated paper and fine paper, and are not particularly limited. Furthermore, the multiple adhesive layers may have the same composition or different compositions. Furthermore, an anchor coat layer may be sandwiched between the layers to improve the adhesive strength of the adhesive layers.

[0184] The method for laminating the plastic film of the present invention and the substrate film is not particularly limited, and any of a number of composite techniques, including dry lamination, wet lamination, non-solvent lamination, extrusion lamination, sand lamination, and thermal lamination, may be used. The substrate film used may be the same as the first resin layer used in the recycled plastics described above, and this is preferred because it allows for the production of laminates and packaging materials that can withstand repeated recycling.

[0185] Furthermore, the adhesive layer and printing layer in the laminate may be made of the same adhesive or printing ink as the adhesive layer and / or printing layer used in the recycled plastics described above, which is preferable because it allows for the production of a laminate or packaging material that can withstand repeated recycling.

[0186] The substrate to be laminated on the plastic film of the present invention may be a substrate having a vapor-deposited layer made of an inorganic substance and / or an inorganic oxide provided on the above-mentioned resin film. By using a substrate having such a vapor-deposited layer, barrier properties can be imparted to the plastic laminate or a packaging material using the plastic laminate. The vapor-deposited layer can be formed by a known method using a known inorganic substance or inorganic oxide, and its composition and formation method are not particularly limited. Furthermore, a laminate film made of the plastic film of the present invention may have two or more vapor-deposited layers, which may have the same composition or different compositions.

[0187] The vapor-deposited layer may be, for example, a vapor-deposited film of an inorganic substance or inorganic oxide such as silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), yttrium (Y), etc. Vapor-deposited films of inorganic oxides such as silicon oxide and aluminum oxide are transparent.

[0188] The inorganic oxides are expressed as MOx (where M represents an inorganic element), such as SiOx and AlOx. The value of x can range from 0 to 2 for silicon (Si), 0 to 1.5 for aluminum (Al), 0 to 1.5 for magnesium (Mg), 0 to 1 for calcium (Ca), 0 to 0.5 for potassium (K), 0 to 2 for tin (Sn), 0 to 0.5 for sodium (Na), 0 to 1.5 for boron (B), 0 to 1.5 for titanium (Ti), 0 to 2 for lead (Pb), 0 to 1 for zirconium (Zr), and 0 to 1.5 for yttrium (Y). In the above, when x = 0, the material is a completely inorganic element (pure substance) and is not transparent. When the value of x is at the upper limit of the range, the material is completely oxidized. Silicon (Si) or aluminum (Al) is preferably used as the vapor deposition layer, and silicon (Si) having an x ​​value in the range of 1.0 to 2.0 and aluminum (Al) having an x ​​value in the range of 0.5 to 1.5 can be used.

[0189] The vapor deposition layer can be formed on the surface of the substrate or the like by a physical vapor deposition method (PVD method) such as vacuum deposition, sputtering, or ion plating, or a chemical vapor deposition method (CVD method) such as plasma chemical vapor deposition, thermal chemical vapor deposition, or photochemical vapor deposition.

[0190] The thickness of the vapor-deposited layer is not particularly limited as long as the vapor-deposited layer alone can exhibit a certain level of gas barrier function. The preferred thickness range varies depending on the type of metal or metal oxide to be vapor-deposited, but is preferably 0.05 to 70 nm, more preferably 0.1 to 70 nm, still more preferably 3 to 70 nm, and even more preferably 5 to 60 nm.

[0191] Examples of the metal-deposited film include a VM-CPP film obtained by depositing a metal such as aluminum on a CPP film, and a VM-OPP film obtained by depositing a metal such as aluminum on an OPP film. Examples of the transparent deposited film include films obtained by depositing silica or alumina on an OPP film, PET film, nylon film, or the like. For the purpose of protecting the inorganic deposited layer of silica or alumina, a film with a coating applied to the deposited layer may also be used.

[0192] In addition, in applications where transparency is not required, aluminum foil can be used alone or in combination as a barrier layer.

[0193] Paper can also be used as the substrate. Examples of the substrate that can be used include paperboard such as coated cardboard, cardboard, ivory paper, and manila cardboard used for printing on packaging materials and the like for cosmetics, beverages, pharmaceuticals, toys, and equipment, as well as paper such as milk carton base paper, cup base paper, fine paper, kraft paper, pure white roll paper, glassine paper, parchment paper, manila cardboard, white cardboard, coated paper, art paper, imitation paper, thin paper, thick paper, and polyethylene-coated paper, as well as various synthetic papers and acid-resistant papers.

[0194] When a material having gas barrier properties is used as the adhesive or the anchor coating agent described below, a laminate film having particularly excellent gas barrier properties can be obtained. ２ The oxygen barrier property of the cured coating film of the adhesive applied at (solid content) is 300 cc / m ２ / day / atm or less, or water vapor barrier property of 120 g / m ２ Commercially available products include the "PASLIM" series, such as PASLIM VM001 and PASLIM J350X manufactured by DIC Corporation, and "MAXIEVE" manufactured by Mitsubishi Gas Chemical Company, Inc.

[0195] The adhesive layer can also be formed from a thermoplastic resin, and can be formed by a conventionally known method, such as melt extrusion lamination or sand lamination. When laminating the adhesive layer by extrusion lamination, an anchor coat layer can be formed by applying an anchor coat agent to the surface of the layer to be laminated and drying it. When laminating the plastic film of the present invention and a substrate or the like by extrusion lamination or sand lamination to obtain the plastic laminate or a packaging material using the plastic laminate, the nip roll or chill roll used during lamination can be replaced with an embossing roll to emboss the surface on the seal layer side.

[0196] (Packaging Materials) The uses of the plastic film or laminate of the present invention are not particularly limited, but it can be used as a packaging material for food, medicines, industrial parts, miscellaneous goods, magazines, etc., and can be particularly suitably used as a lid material for packaging containers, etc.

[0197] The packaging bag is preferably one formed by overlapping and sealing the sealing layers of the plastic film or laminate of the present invention, or by overlapping and sealing the outermost layer and the sealing layer. For example, two sheets of the plastic film are cut to the desired size of the packaging bag, overlapped, and sealed on three sides to form a bag, and then the contents are filled in through the unsealed side and sealed. Furthermore, a packaging bag can be formed by sealing the ends of a rolled film into a cylindrical shape using an automatic packaging machine, and then sealing the top and bottom.

[0198] The plastic film or laminate of the present invention can also be used to form a packaging bag or container by overlaying and sealing another sealable film. In this case, a film with relatively low mechanical strength, such as LDPE or EVA, can be used as the other film. A laminate film formed by bonding a film such as LDPE or EVA with a stretched film with relatively good tearability, such as biaxially oriented polyethylene terephthalate film (OPET) or biaxially oriented polypropylene film (OPP), can also be used.

[0199] (Sealing method) The plastic film or laminate of the present invention has sealability and can be sealed to form a package. The seal strength of the plastic film or laminate of the present invention can be adjusted appropriately depending on the mode of use. In addition to heat sealing, ultrasonic sealing can also be applied to the plastic film of the present invention. There are no particular restrictions on the method of ultrasonic sealing, and a known ultrasonic sealing method or a method using a known ultrasonic sealing device can be appropriately selected depending on the purpose.

[0200] In packaging materials using the plastic film or laminate of the present invention, it is preferable to form any tear initiation portion such as a V notch, I notch, perforation, or micropore in the sealed portion in order to weaken the initial tear strength and improve openability.

[0201] The contents to be filled into the packaging material of the present invention include, for example, foods such as rice crackers, bean snacks, nuts, biscuits, cookies, wafer snacks, marshmallows, pies, semi-dried cakes, candy, snacks, and other confectioneries; bread, snack noodles, instant noodles, dried noodles, pasta, aseptically packaged cooked rice, porridge, porridge, packaged rice cakes, and cereal foods, as well as agricultural processed products such as pickles, boiled beans, natto, miso, frozen tofu, tofu, nametake mushrooms, konjac, wild vegetable processed products, jams, peanut cream, salads, frozen vegetables, and potato processed products; livestock processed products such as ham, bacon, sausages, chicken processed products, and corned beef, Examples of such foods include fish ham and sausage, processed seafood products such as kamaboko, nori seaweed, tsukudani (simmered food in soy sauce), bonito flakes, salted fish, smoked salmon, and spicy mentaiko, fruit pulp such as peaches, mandarin oranges, pineapples, apples, pears, and cherries, vegetables such as corn, asparagus, mushrooms, onions, carrots, radishes, and potatoes, prepared foods such as frozen and chilled prepared foods including hamburgers, meatballs, fried seafood, gyoza, and croquettes, dairy products such as butter, margarine, cheese, cream, instant creamy powder, and infant formula, liquid seasonings, retort curry, and pet food.

[0202] In addition, the present invention can also be used as a packaging material for various non-food products, such as cigarettes, disposable body warmers, medicines such as infusion packs, liquid laundry detergent, liquid kitchen detergent, liquid bath detergent, liquid bath soap, liquid shampoo, liquid conditioner, cosmetics such as lotion and emulsion, vacuum insulation materials, batteries, etc.

[0203] (Molded Article) The plastic film of the present invention can also be used as a vacuum-molded molded article. The vacuum molding method is not particularly limited, and the following methods can be used, but are not limited to these. - Heat and pressure molding method: A method in which a battery packaging material is sandwiched between a lower mold having a hole for supplying high-temperature, high-pressure air and an upper mold having a pocket-shaped recess, and air is supplied to form the recess while heating and softening. - Preheater flat-plate pressure molding method: A method in which a battery packaging material is heated and softened, and then sandwiched between a lower mold having a hole for supplying high-pressure air and an upper mold having a pocket-shaped recess, and air is supplied to form the recess. - Drum-type vacuum molding method: A method in which a battery packaging material is partially heated and softened in a heated drum, and then the pocket-shaped recess of a drum is vacuum-suctioned to form the recess. - Pin molding method: A method in which a base material sheet is heated and softened, and then pressure-bonded using a pocket-shaped concave-convex mold. - Preheater plug-assisted compressed air molding method: After heating and softening the battery packaging material, it is sandwiched between a lower mold with a hole through which high-pressure air is supplied and an upper mold with a pocket-shaped recess, and air is supplied to form the recess. During molding, a convex plug is raised and lowered to assist the molding.

[0204] The surface temperature of the plastic film during vacuum forming is usually in the range of 150 to 250° C., preferably in the range of 160 to 220° C., and more preferably in the range of 160 to 200° C. When the surface temperature is in the above range, the drawdown property and shaping property are good, and the wall thickness is uniform.

[0205] The plastic film of the present invention can also be recycled by the above-mentioned method or the like and used as recycled plastic.

[0206] The present invention will be described in more detail below with reference to specific synthesis examples and examples, but the present invention is not limited to these examples. In the following examples, "parts" and "%" represent "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0207] <Preparation of Adhesives> (Preparation of Adhesive 1) (Synthesis of Polyol Composition 1) A polyester reaction vessel equipped with a stirrer, a nitrogen gas inlet tube, a Snyder tube, and a condenser was charged with 20.98 parts of ethylene glycol, 0.12 parts of glycerin, 50.94 parts of 1,3,5-tris(2-hydroxyethyl)isocyanuric acid, and 50.41 parts of phthalic anhydride, and the mixture was gradually heated so that the temperature at the top of the distillation tube did not exceed 100°C, and the internal temperature was maintained at 220°C. When the acid value reached 1 mgKOH / g or less, the esterification reaction was terminated, yielding a polyester polyol having a number average molecular weight of 670. The hydroxyl value was 230.2 mgKOH / g. This was used as Polyol Composition 1.

[0208] (Synthesis of Polyisocyanate Composition 1) 56.53 parts of ethylene glycol, 79.48 parts of phthalic anhydride, and 0.007 parts of titanium tetraisopropoxide were charged into a polyester reaction vessel equipped with a stirrer, a nitrogen gas inlet tube, a Snyder tube, and a condenser, and the mixture was gradually heated so that the temperature at the top of the distillation tube did not exceed 100°C, and the internal temperature was maintained at 220°C. When the acid value reached 1 mgKOH / g or less, the esterification reaction was terminated, and 0.01 parts of phosphoric acid was added to obtain a polyester polyol having a number average molecular weight of 400. The hydroxyl value was 280.0 mgKOH / g.

[0209] 136.00 parts of xylylene diisocyanate was placed in a reaction vessel equipped with a stirrer, a nitrogen gas inlet tube, a Snyder tube, a cooling condenser, and a dropping funnel, and the mixture was stirred while heated to 70°C, to which 99.50 parts of the polyester polyol synthesized above was added dropwise using the dropping funnel over 2 hours, followed by stirring for a further 4 hours to obtain Polyisocyanate Composition 1. The NCO% measured in accordance with JIS-K1603 was 16.0%.

[0210] (Preparation of Adhesive 1) Adhesive 1 was prepared by mixing polyol composition 1 and polyisocyanate composition 1 in a mass ratio of 25:100.

[0211] (Preparation of Adhesive 2) (Synthesis of Polyol Composition 2) 319 parts by mass of diethylene glycol, 121 parts by mass of 2-methyl-propanediol, and 55 parts by mass of trimethylolpropane were charged into a reaction vessel and dissolved by heating to 80°C while stirring under a nitrogen gas stream. Furthermore, 504 parts by mass of adipic acid was charged into the reaction vessel while stirring and heated to 150°C to 240°C to carry out an esterification reaction. When the acid value reached 5 mgKOH / g or less, the pressure in the reaction vessel was gradually reduced, and the reaction was carried out at 1 mmHg or less and 200 to 220°C for 1 hour to obtain a polyester polyol resin having an acid value of 0.8 mgKOH / g and a molecular weight of approximately 660 and hydroxyl groups at both ends. This was used as polyol composition 2.

[0212] (Synthesis of Polyisocyanate Composition 2) A flask equipped with a stirrer, a thermometer, and a nitrogen gas inlet tube was charged with 36 parts of 4,4'-diphenylmethane diisocyanate and 19 parts of 2,4'-diphenylmethane diisocyanate, and heated to 60°C with stirring under a nitrogen gas atmosphere. 11 parts of polypropylene glycol having a number average molecular weight of 400, 22 parts of polypropylene glycol having a number average molecular weight of 1000, and 11 parts of polypropylene glycol having a number average molecular weight of 2000 were added dropwise in several portions, and the mixture was stirred for 5 to 6 hours to complete the urethanization reaction. Polyisocyanate Composition 2 having an NCO group content of 13.5% was obtained.

[0213] (Preparation of Adhesive 2) Polyol composition 2 and polyisocyanate composition 2 were mixed in a mass ratio of 100:60 to prepare adhesive 2.

[0214] <Production of Plastic Laminate> (Plastic Laminate 1) A uniaxially stretched polyethylene film (hereinafter abbreviated as MDOPE film) (PE3K-BT) with a thickness of 25 μm was coated with Adhesive 1 at a rate of 3.5 g / m ２ (solid content), and then laminated to a 60 μm-thick linear low-density polyethylene film (hereinafter abbreviated as LLDPE film) (TUX-MC-S). After aging at 40° C. for 4 days, a plastic laminate 1 for Example 1 was obtained.

[0215] (Plastic laminate 2) A 25 μm thick MDOPE film (PE3K-BT) was coated with adhesive 2 at 2.0 g / m ２ (solid content), and then laminated to a 60 μm-thick LLDPE film (TUX-MC-S). After aging at 40° C. for 2 days, a plastic laminate 2 for Example 2 was obtained.

[0216] (Plastic laminate 3) A uniaxially oriented polyethylene film (hereinafter abbreviated as MDOPE film) (PE3K-BT) with a thickness of 25 μm was printed with white ink “GLX-1012 white” (PVC-free gravure white ink, manufactured by DIC Corporation). Adhesive 1 was applied at a rate of 3.5 g / m ２ (solid content), and then laminated to a 60 μm-thick linear low-density polyethylene film (hereinafter abbreviated as LLDPE film) (TUX-MC-S). After aging at 40° C. for 4 days, a plastic laminate 3 for Example 3 was obtained.

[0217] (Plastic laminate H1) A plastic laminate H1 for Comparative Example 1 was obtained in the same manner as in Example 2, except that a nylon film having a thickness of 15 μm was used instead of the MDOPE film and a CPP film having a thickness of 25 μm was used instead of the LLDPE film.

[0218] (Plastic laminate H2) A plastic laminate H2 for Comparative Example 2 was obtained in the same manner as in Example 2, except that a 15 μm thick polyethylene terephthalate (PET) film was used instead of the MDOPE film and a 25 μm thick CPP film was used instead of the LLDPE film.

[0219] (Recycled Plastics of Examples and Comparative Examples) The plastic laminates of the Examples and Comparative Examples were each pulverized using a pulverizer (Daiko Seiki, DAS-20) to obtain pulverized laminates. The resulting pulverized laminates were fed into the melt-kneading section of a twin-screw extruder (Kobe Steel, KTX-30 twin-screw extruder). The molten and kneaded resin was extruded through a 100 μm filter, immersed in cold water to cool, and then cut with a petalizer to obtain recycled plastic pellets. The extruder had a set screw rotation speed of 300 rpm, a set temperature of 230°C, and a set output rate of 8 kg / h. The recycled plastic of Example 1 is referred to as Recycled Plastic 1, the recycled plastic of Example 2 as Recycled Plastic 2, the recycled plastic of Example 3 as Recycled Plastic 3, the recycled plastic of Comparative Example 1 as Recycled Plastic H1, and the recycled plastic of Comparative Example 2 as Recycled Plastic H2.

[0220] (Method for Evaluating Recycled Plastics) (Polyolefin Resin Content in Recycled Plastics) The polyolefin resin content in recycled plastics was calculated using formula (1) and expressed in mass %: (Mass of polyolefin resin in plastic laminate) / (Mass of plastic laminate)×100 (1)

[0221] (Nitrogen Concentration in Recycled Plastic) The nitrogen concentration in the recycled plastic was calculated by the formula (2) and expressed in mass %: (mass of nitrogen in plastic laminate) / (mass of plastic laminate)×100 (2)

[0222] (Melt flow rate (MFR, unit: g / 10 min)) The melt flow rate was measured according to the method described in JIS K7210-1:2014. The measurement conditions, such as temperature, were set to those for the component with the highest content in the recycled plastic. The nitrogen concentration and melt flow rate (MFR) of each sample are shown in Table 1.

[0223]

[0224] (Film manufacturing method: T-die method) Recycled plastic pellets and DOWLWX2045G pellets as virgin resin were mixed at a ratio of 25:75 and fed into the melting section of a T-die extruder (AIKI Liotech Co., Ltd. T-die type film forming unit ALM-TMF200). The molten resin was extruded from the T-die and cooled and solidified with a cooling roll to obtain a 30 μm recycled film. The set screw rotation speed of the extruder was 30 rpm, and the set temperature was 230°C.

[0225] (Film manufacturing method: inflation method) Pellets of each recycled plastic and pellets of virgin resin were mixed at a ratio of 25:75 and fed into the melting section of an inflation extruder (AIKI Liotech inflation molding unit ALM-IMF30). The molten resin was extruded through an inflation die and cooled and solidified with air to obtain a recycled film with a thickness of 25 μm. The set screw rotation speed of the extruder was 38 rpm, and the set temperature was 230°C.

[0226] (Film manufacturing method: Calender molding) Pellets of each recycled plastic and pellets of virgin olefin resin were mixed in a ratio of 25:75 and molded at 180°C using a calender molding machine (an inverted L-type calender molding machine manufactured by Nippon Roll Co., Ltd.) to produce a 25 μm recycled film.

[0227] (Film manufacturing method: Co-extrusion T-die method, 3 layers) A 25:75 mixture of recycled plastic pellets and virgin resin pellets, and virgin resin pellets were each fed into the melting section using three extruders and a 3-layer manifold. The molten resin was extruded from a T-die and laminated into three layers: virgin olefin resin / a 25:75 mixture of recycled plastic pellets and virgin olefin resin pellets / virgin olefin resin. The layers were cooled and solidified with a cooling roll to produce a recycled film with a thickness of 10 μm for each layer, for a total thickness of 30 μm.

[0228] (Evaluation Method) (Deposits at Die Outlet) Deposits at the die outlet were visually observed.

[0229] (Tensile Properties (Tensile Elongation at Break, Unit: %)) The tensile properties of the recycled film were measured according to the method specified in JIS K7127-1999.

[0230] (Haze unit: %) Measured according to JIS K 7105:1981 using a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd.).

[0231] The results are shown in Tables 2 to 5.

[0232]

[0233]

[0234]

[0235]

[0236] As a result, plastic films made from the recycled plastics of the present invention can be stably produced by molding methods such as the T-die method, inflation method, calendar molding method, or coextrusion multilayer T-die method.

Claims

1. A method for manufacturing plastic films using recycled plastic as a raw material, The recycled plastic contains 80% by mass or more of polyolefin resin, and the nitrogen concentration is in the range of 0.01 to 2.0% by mass. The process comprises the steps of heating and melting a resin mixture (A) containing 0.1 to 99% by mass of the recycled plastic and 99.9 to 1% by mass of an olefin resin derived from petroleum or biomass in an extruder, and forming a film using one of the following methods: T-die method, inflation method, or calendering method. The aforementioned olefin resin derived from petroleum or biomass is polyethylene. A method for manufacturing plastic film.

2. The method for producing a plastic film according to claim 1, wherein the recycled plastic is obtained by crushing and melt-kneading a plastic laminate having at least a first resin layer, an adhesive layer and / or a printing layer, and a second resin layer.

3. The method for producing a plastic film according to claim 2, wherein the plastic laminate is crushed by wet crushing or dry crushing.

4. A method for producing a plastic film according to claim 1, comprising the steps of: heating and melting a resin mixture (A) containing 20 to 80% by mass of recycled plastic and 80 to 20% by mass of an olefin resin derived from petroleum or biomass in an extruder; and forming a film using a T-die method, an inflation method, or a calendering method.

5. The aforementioned plastic film has at least a resin layer (A) and a resin layer (B) made from recycled plastic, A resin mixture (A) containing 0.1 to 99% by mass of the recycled plastic and 99.9 to 1% by mass of an olefin resin derived from petroleum or biomass, and a resin mixture (B) each of which are heated and melted in an extruder. A process of layering in the order of (A) / (B) in a molten state, A method for manufacturing a plastic film according to claim 1, comprising the step of forming a film by one of the following methods: T-die method, inflation method, or calendering method.

6. The aforementioned plastic film has at least a resin layer (A), a resin layer (B), and a resin layer (C) made from recycled plastic, A resin mixture (A) containing 0.1 to 99% by mass of recycled plastic and 99.9 to 1% by mass of olefin resin derived from petroleum or biomass, a resin mixture (B), and a resin mixture (C) each of which are heated and melted in separate extruders. A process of stacking (A), (B), and (C) in a molten state, A method for manufacturing a plastic film according to claim 1, comprising the step of forming a film by one of the following methods: T-die method, inflation method, or calendering method.

7. A method for manufacturing a laminate using a plastic film obtained by the manufacturing method described in any one of claims 1 to 6.

8. A method for manufacturing packaging material using a plastic film obtained by the manufacturing method described in any one of claims 1 to 6.

9. A method for manufacturing a lid material using a plastic film obtained by the manufacturing method described in any one of claims 1 to 6.