Laminated film, and bag

Abstract

The present invention addresses the problem of providing: a laminate film that includes a recycled resin, and that has a comparatively exceptional external appearance and comparatively low damage properties; and a bag that includes the laminate film.　The laminate film according to the present invention is configured from three or more resin layers, including at least one inner layer and two surface layers, the at least one inner layer containing a recycled resin composition that includes a recycled resin and an antioxidant, the antioxidant content being 100-2,000 mass ppm with respect to the recycled resin composition, and the two surface layers containing an unused resin.

Description

[Technical Field]

[0001] The present invention relates to a laminated film and a bag containing the laminated film. [Background technology]

[0002] Traditionally, the primary method of plastic recycling has been thermal recycling, which involves recovering and reusing the heat generated when burning waste plastic. However, in May 2019, the Ministry of the Environment formulated the "Plastic Resource Recycling Strategy," which explicitly states that 100% of used plastics will be effectively utilized through reduction and recycling by 2035. In this social context, the demand for material recycling, which reuses waste plastics as raw materials for plastic products, is expected to increase even further.

[0003] In material recycling, the mainstream methods are global recycling, where waste plastics used in films, sheets, containers, etc., which have large market shares, are exported overseas for recycling, and cascade recycling, where the quality is reduced and the waste plastics are used as raw materials for other products with smaller market shares. However, in recent years, due to import restrictions on waste plastics in Asian countries, recycled raw materials are currently concentrated in products with small market shares, and there is an urgent need to expand the range of products to which recycled raw materials can be applied. In particular, horizontal recycling, which uses waste plastics as raw materials for the same product, is the most efficient recycling method, and there is a growing need for high-quality recycled raw materials that can be applied to horizontal recycling.

[0004] As a method for reusing waste plastics through horizontal recycling, for example, Patent Document 1 discloses a method for forming a plastic molded product with a sandwich structure having a core layer of recycled resin and a surface layer of unused resin by introducing recycled resin obtained from used containers and other plastic molded products and unused resin in a predetermined ratio. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2004-160817 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In horizontal recycling, it is desirable that products obtained using recycled materials have performance equivalent to those obtained using unused materials (virgin materials). However, laminated films containing recycled resin have the problem of being inferior in appearance and more easily damaged compared to laminated films made from unused resin.

[0007] This invention has been made in view of the current situation, and aims to provide a laminated film that contains recycled resin, has a relatively good appearance, and is relatively resistant to damage, as well as a bag containing the laminated film. [Means for solving the problem]

[0008] The laminated film according to the present invention is a laminated film composed of three or more resin layers, each including at least one inner layer and two surface layers, wherein the at least one inner layer contains a recycled resin composition comprising recycled resin and an antioxidant, the antioxidant content being 100 ppm to 2000 ppm by mass relative to the recycled resin composition, and the two surface layers contain unused resin.

[0009] The bag according to the present invention includes the laminated film described above. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a laminated film that contains recycled resin, has a relatively good appearance, and is relatively resistant to damage, as well as a bag containing the laminated film. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0012] 1. Laminated Film The laminated film according to this embodiment is composed of three or more resin layers including at least one inner layer and two surface layers, and preferably composed of three resin layers.

[0013] [Inner Layer] In the laminated film according to this embodiment, at least one inner layer contains a recycled resin composition containing a recycled resin and an antioxidant. The recycled resin composition may further contain an antistatic agent. Also, the recycled resin composition may further contain a neutralizing agent. The recycled resin composition may contain, as other additives, weathering agents, lubricants, antiblocking agents, antifogging agents, drip-proof agents, pigments, fillers, etc. The content of the recycled resin is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more, based on the recycled resin composition.

[0014] Examples of the resin constituting the recycled resin include, for example, polyolefin resins, (meth)acrylic resins, polycarbonate resins, polyetherimide resins, polyester resins, polystyrene resins, polyethersulfone resins, fluorine resins, ABS (acrylonitrile-butadiene-styrene) resins, AS (acrylonitrile-styrene) resins, polyvinyl chloride resins, and the like. The resin constituting the recycled resin is preferably a polyolefin resin. Note that the recycled resin may be a mixture of two or more resins.

[0015] [Polyolefin Resin] The polyolefin resin is a resin containing an olefin polymer. Examples of the polyolefin resin include, for example, polyethylene resins, polypropylene resins, poly-α-olefin resins, and the like.

[0016] [Polyethylene Resin] Polyethylene resins are resins containing ethylene polymers. Ethylene polymers are polymers containing more than 50% by mass of monomer units derived from ethylene, that is, ethylene homopolymers or ethylene copolymers containing more than 50% by mass of monomer units derived from ethylene. Preferably, the ethylene polymer is an ethylene homopolymer or an ethylene copolymer containing 90% by mass or more of monomer units derived from ethylene. Note that one type of ethylene polymer may be used alone, or two or more types may be used in combination.

[0017] In this specification, the term "monomer unit" in phrases such as "monomer unit derived from ethylene" means the polymerization unit of a monomer. Therefore, for example, "monomer unit derived from ethylene" means the monomer unit -CH2CH2-.

[0018] As an example of an ethylene homopolymer, a repeating ethylene unit is randomly linked in a branched structure by high-pressure radical polymerization using a radical initiator, and has a density of 910 kg / m³. 3 ~935 kg / m 3 High-pressure low-density polyethylene (LDPE) is one example.

[0019] Examples of ethylene copolymers include copolymers of ethylene and α-olefins, and copolymers of α-olefins substituted with alicyclic compounds and ethylene.

[0020] Examples of copolymers of ethylene and α-olefins include crystalline linear low-density polyethylene and elastomers of copolymers of ethylene and α-olefins that have low crystallinity and rubbery elastic properties.

[0021] The density of linear low-density polyethylene is preferably 900 kg / m³. 3 ~940 kg / m 3 Furthermore, the density of the ethylene-α-olefin copolymer elastomer is preferably 860 kg / m³. 3 ~900kg / m 3That is the case.

[0022] The α-olefin is preferably an α-olefin having 3 to 12 carbon atoms. Examples of α-olefins having 3 to 10 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, and 3-methyl-1-butene. The α-olefin having 3 to 10 carbon atoms is preferably an α-olefin having 4 to 10 carbon atoms, and more preferably 1-butene, 1-hexene, or 1-octene.

[0023] Examples of α-olefins substituted with alicyclic compounds include vinylcyclohexane.

[0024] The content of monomer units derived from α-olefins in the ethylene copolymer is preferably 4% to 20% by mass.

[0025] Specific examples of copolymers of ethylene and α-olefins include ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer, ethylene-1-decene copolymer, and ethylene-(3-methyl-1-butene) copolymer. Note that one type of copolymer of ethylene and α-olefin may be used alone, or two or more types may be used in combination. Furthermore, the ethylene-based polymer may be a mixture of an ethylene homopolymer and a copolymer of ethylene and α-olefin.

[0026] The ethylene-based polymer has a melt flow rate (MFR) measured at a temperature of 190°C and a load of 2.16 kg, preferably 0.5 g / 10 min to 50 g / 10 min, more preferably 1 g / 10 min to 30 g / 10 min, and even more preferably 1 g / 10 min to 20 g / 10 min. The MFR is measured according to Method A specified in JIS K7210-1.

[0027] (Polypropylene resin) Polypropylene resins are resins containing propylene polymers. Propylene polymers are polymers containing more than 50% by mass of monomer units derived from propylene, that is, propylene homopolymers or propylene copolymers containing more than 50% by mass of monomer units derived from propylene. The propylene copolymer is preferably a copolymer of ethylene and / or α-olefins having 4 to 12 carbon atoms and propylene.

[0028] For propylene homopolymers, the melt flow rate (MFR), measured at a temperature of 230°C and a load of 2.16 kg, is preferably 0.1 g / 10 min to 50 g / 10 min. For copolymers of ethylene and / or α-olefins having 4 to 12 carbon atoms and propylene, the melt flow rate (MFR), measured at a temperature of 230°C and a load of 2.16 kg, is preferably 10 g / 10 min to 200 g / 10 min. The MFR is measured according to Method A as specified in JIS K7210-1.

[0029] When the total mass of the copolymer of ethylene and / or α-olefins having 4 to 12 carbon atoms and propylene is taken as 100% by mass, the content of monomer units derived from ethylene and / or α-olefins having 4 to 12 carbon atoms is preferably 0.1% to 40% by mass, and the content of monomer units derived from propylene is preferably 60% to 99.9% by mass.

[0030] Examples of α-olefins having 4 to 12 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-decene. The α-olefin having 4 to 12 carbon atoms is preferably 1-butene, 1-hexene, or 1-octene.

[0031] Specific examples of copolymers of ethylene and / or α-olefins having 4 to 12 carbon atoms with propylene include copolymers of propylene and ethylene, copolymers of propylene and α-olefins having 4 to 12 carbon atoms, and copolymers of propylene, ethylene and α-olefins having 4 to 12 carbon atoms. Note that the copolymer of ethylene and / or α-olefins having 4 to 12 carbon atoms with propylene may be used alone or in combination of two or more types. Furthermore, the propylene-based polymer may be a mixture of a propylene homopolymer and a copolymer of ethylene and / or α-olefins having 4 to 12 carbon atoms with propylene.

[0032] Examples of copolymers of propylene and α-olefins having 4 to 12 carbon atoms include propylene-1-butene copolymer, propylene-1-hexene copolymer, propylene-1-octene copolymer, and propylene-1-decene copolymer.

[0033] Examples of copolymers of propylene, ethylene, and α-olefins having 4 to 12 carbon atoms include propylene-ethylene-1-butene copolymer, propylene-ethylene-1-hexene copolymer, propylene-ethylene-1-octene copolymer, and propylene-ethylene-1-decene copolymer.

[0034] (Poly-alpha-olefin resin) Poly-α-olefin resins are resins containing α-olefin polymers. α-olefin polymers are polymers containing more than 50% by mass of monomer units derived from α-olefins; that is, α-olefin homopolymers or α-olefin copolymers containing more than 50% by mass of monomer units derived from α-olefins. Examples of α-olefin copolymers include copolymers of α-olefin and ethylene, and copolymers of α-olefin and propylene.

[0035] The α-olefin is preferably an α-olefin having 4 to 12 carbon atoms. Examples of the α-olefin having 4 to 12 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 4-methyl-1-pentene, 4-methyl-1-hexene, and the like. The α-olefin having 4 to 12 carbon atoms is preferably 1-butene, 1-hexene or 1-octene.

[0036] The density of the α-olefin polymer is preferably 850 kg / m 3 ~950 kg / m 3 and more preferably 850 kg / m 3 ~930 kg / m 3 and even more preferably 880 kg / m 3 ~930 kg / m 3 is.

[0037] The melt flow rate (MFR) of the α-olefin polymer measured at a temperature of 190 °C and a load of 2.16 kg is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.1 g / 10 min to 10 g / 10 min, and even more preferably 1 g / 10 min to 5 g / 10 min. The MFR is measured according to Method A specified in JIS K7210-1.

[0038] <Acrylic resin> The acrylic resin is a resin containing an acrylic polymer. Examples of the acrylic polymer include polymers of acrylic acid derivatives such as acrylic acid and its esters, polymers of methacrylic acid derivatives such as methacrylic acid and its esters, and copolymers of acrylic acid derivatives and methacrylic acid derivatives.

[0039] Examples of acrylic polymers include methacrylic homopolymers containing only monomer units derived from alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms; and methacrylic copolymers having 50% by mass or more and less than 100% by mass of monomer units derived from alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms, and more than 0% by mass and 50% by mass or less of monomer units derived from other vinyl monomers copolymerizable with monomer units derived from alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms.

[0040] The above-mentioned "alkyl methacrylate having an alkyl group with 1 to 4 carbon atoms" refers to a compound represented as CH2=CH(CH3)COOR (where R is an alkyl group with 1 to 4 carbon atoms). A vinyl monomer copolymerizable with alkyl methacrylate having an alkyl group with 1 to 4 carbon atoms is a monomer that is copolymerizable with alkyl methacrylate having an alkyl group with 1 to 4 carbon atoms and also has a vinyl group.

[0041] Examples of alkyl methacrylates having an alkyl group with 1 to 4 carbon atoms include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, sec-butyl methacrylate, and isobutyl methacrylate. The alkyl methacrylate having an alkyl group with 1 to 4 carbon atoms is preferably methyl methacrylate. The alkyl methacrylates may be used individually or in combination of two or more types.

[0042] Examples of vinyl monomers copolymerizable with alkyl methacrylates having an alkyl group with 1 to 4 carbon atoms include methacrylic acid esters such as cyclohexyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, and monoglycerol methacrylate (excluding alkyl methacrylates having an alkyl group with 1 to 4 carbon atoms); methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, and Examples include acrylic acid esters such as 2-hydroxypropyl acrylic acid and monoglycerol acrylate; unsaturated carboxylic acids or their acid anhydrides such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, maleic anhydride, and itaconic anhydride; nitrogen-containing monomers such as acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, diacetone acrylamide, and dimethylaminoethyl methacrylate; epoxy group-containing monomers such as allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate; and styrene monomers such as styrene and α-methylstyrene.

[0043] <Polycarbonate resin> Polycarbonate resins are resins that contain polymers having monomer units derived from dihydroxy compounds. Examples of such polymers include those obtained by reacting dihydroxy compounds such as divalent phenols and isosorbides with carbonylating agents using methods such as interfacial polycondensation or molten transesterification; those obtained by polymerizing carbonate prepolymers using methods such as solid-phase transesterification; and those obtained by polymerizing cyclic carbonate compounds using ring-opening polymerization.

[0044] Examples of divalent phenols include hydroquinone, resorcinol, 4,4'-dihydroxydiphenyl, bis(4-hydroxyphenyl)methane, bis{(4-hydroxy-3,5-dimethyl)phenyl}methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A), 2,2-bis{(4-hydroxy-3-methyl)phenyl}propane, 2,2-bis{(4-hydroxy-3,5- dimethyl(phenyl)propane, 2,2-bis{(4-hydroxy-3,5-dibromo)phenyl}propane, 2,2-bis{(3-isopropyl-4-hydroxy)phenyl}propane, 2,2-bis{(4-hydroxy-3-phenyl)phenyl}propane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)-3-methylbutane, 2,2-bis(4-hydroxyphenyl)-3,3-dimethylbutane, 2,4-bis(4-hydroxyphenyl)-2-methylbutane, 2,2-bis(4- Hydroxyphenyl)pentane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-4-isopropylcyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis{(4-hydroxy-3-methyl)phenyl}fluorene, α,α'-bis(4-hydroxyphenyl)-o-diisopropylbenzene, Examples include α,α'-bis(4-hydroxyphenyl)-m-diisopropylbenzene, α,α'-bis(4-hydroxyphenyl)-p-diisopropylbenzene, 1,3-bis(4-hydroxyphenyl)-5,7-dimethyladamantane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl ether, and 4,4'-dihydroxydiphenyl ester. Furthermore, divalent phenols may be used individually or in combination of two or more types.

[0045] The divalent phenol is preferably bisphenol A, 2,2-bis{(4-hydroxy-3-methyl)phenyl}propane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)-3-methylbutane, 2,2-bis(4-hydroxyphenyl)-3,3-dimethylbutane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, or α,α'-bis(4-hydroxyphenyl)-m-diisopropylbenzene. In particular, it is preferable to use bisphenol A alone as the divalent phenol, or to use bisphenol A in combination with at least one selected from the group consisting of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 2,2-bis{(4-hydroxy-3-methyl)phenyl}propane, and α,α'-bis(4-hydroxyphenyl)-m-diisopropylbenzene.

[0046] Examples of carbonylating agents include carbonyl halides (such as phosgene), carbonate esters (such as diphenyl carbonate), and haloformates (such as dihaloformates of divalent phenols). One type of carbonylating agent may be used alone, or two or more types may be used in combination.

[0047] Recycled resin compositions can be obtained by known methods described in, for example, Japanese Patent Publication No. 2010-234812, Japanese Patent Publication No. 2009-214398, Japanese Patent Publication No. 2008-55845, Japanese Patent Publication No. 2007-22061, Japanese Patent Publication No. 2007-15340, etc. The recycled resin composition is preferably used in the form of granulated pellets. The pellets of the recycled resin composition can be obtained, for example, by washing the recovered film with a solvent such as alcohol, drying it, crushing and melting the film, adding an antioxidant and, if necessary, other additives, and then pelletizing it. Alternatively, the recycled resin composition may be obtained by mixing the pellets thus obtained with a masterbatch containing additives.

[0048] In the laminated film according to this embodiment, the recycled resin preferably contains a resin comprising a polymer consisting of monomer units selected from the group consisting of ethylene, propylene, and α-olefins having 4 to 12 carbon atoms. The content of the resin containing the polymer is preferably 99.5% by mass or more relative to the recycled resin. Furthermore, the resin constituting the recycled resin is more preferably a resin comprising an ethylene homopolymer or an ethylene-based copolymer containing more than 50% by mass of monomer units derived from ethylene. The ethylene-based copolymer preferably contains 90% by mass or more of monomer units derived from ethylene.

[0049] Examples of antioxidants include phenolic antioxidants and phosphorus-based antioxidants. Preferably, the antioxidant is a phosphorus-based antioxidant. Note that one type of antioxidant may be used alone, or two or more types may be used in combination.

[0050] Examples of phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol (BHT), n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (trade name: Irganox 1076, manufactured by Ciba Specialty Chemicals), pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (trade name: Irganox 1010, manufactured by Ciba Specialty Chemicals), and 1,3,5-tris(3, Examples include 5-di-tert-butyl-4-hydroxybenzyl) isocyanurate (trade name: Irganox3114, manufactured by Ciba Specialty Chemicals), 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and 3,9-bis[2-{3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5·5]undecane (trade name: Sumilizer GA80, manufactured by Sumitomo Chemical Co., Ltd.).

[0051] Examples of phosphorus-based antioxidants include distearyl pentaerythritol diphosphite (trade name: Adekastab PEP8), tris(2,4-di-t-butylphenyl) phosphite (trade name: Irgafos168, manufactured by Ciba Specialty Chemicals), bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite, and tetrakis(2,4-di-t-butylphenyl)4,4'-biphenylenediphosphonate (trade name: Sandostab). Examples include P-EPQ (manufactured by Clariant Japan), bis(2-t-butyl-4-methylphenyl)pentaerythritol diphosphite, and 2,4,8,10-tetra-t-butyl-6-[3-(3-methyl-4-hydroxy-5-t-butylphenyl)propoxy]dibenzo[d,f][1,3,2]dioxaphosfepine (trade name: Sumirizer GP, manufactured by Sumitomo Chemical Co., Ltd.).

[0052] The antioxidant content is 100 ppm to 2000 ppm by mass, preferably 200 ppm to 1500 ppm by mass, and more preferably 500 ppm to 1000 ppm by mass, relative to the recycled resin composition, from the viewpoint of improving appearance and minimizing damage.

[0053] Examples of antistatic agents include glycerol esters and sorbitanic acid esters of fatty acids having 8 to 22 carbon atoms, alkyldialkanolamides of fatty acids having 8 to 22 carbon atoms, polyethylene glycol esters, and alkyldiethanolamines. The antistatic agent is preferably diethanolamide. One type of antistatic agent may be used alone, or two or more types may be used in combination.

[0054] From the viewpoint of minimizing damage, the content of the antistatic agent is preferably 100 ppm to 2000 ppm by mass, more preferably 200 ppm to 1000 ppm by mass, and even more preferably 300 ppm to 500 ppm by mass, relative to the recycled resin composition. Furthermore, from the viewpoint of improving the hue, the content of the antistatic agent is preferably 100 ppm to 8000 ppm by mass, relative to the recycled resin composition.

[0055] Examples of neutralizing agents include calcium stearate, hydrotalcite, alkaline earth metal oxides, and alkaline earth metal hydroxides. Calcium stearate is preferred as the neutralizing agent. Note that one type of neutralizing agent may be used alone, or two or more types may be used in combination.

[0056] From the viewpoint of improving the appearance, the content of the neutralizing agent is preferably 100 ppm to 2000 ppm by mass, and more preferably 100 ppm to 500 ppm by mass, relative to the recycled resin composition.

[0057] In the laminated film according to this embodiment, at least one inner layer may contain an unused resin, as described later. The content of the unused resin is preferably 50% by mass or less, and more preferably 25% by mass or less, per one inner layer.

[0058] [surface] In the laminated film according to this embodiment, the two surface layers contain unused resin. The surface layers may contain additives such as antioxidants, antistatic agents, neutralizing agents, weathering agents, lubricants, antiblocking agents, antifogging agents, anti-drip agents, pigments, fillers, etc.

[0059] Examples of resins constituting unused resins include those similar to those constituting recycled resins. Preferably, the resin constituting the unused resin is a polymer comprising monomer units derived from at least one selected from the group consisting of ethylene, propylene, and α-olefins having 4 to 12 carbon atoms, and more preferably, a resin comprising an ethylene homopolymer or an ethylene copolymer containing 50% by mass or more monomer units derived from ethylene. The ethylene copolymer preferably contains 90% by mass or more monomer units derived from ethylene.

[0060] When the resin constituting the unused resin is a polyethylene-based resin, the ethylene-based polymer contained in the resin can be produced using a known polymerization catalyst and a known polymerization method.

[0061] Examples of polymerization catalysts include homogeneous catalyst systems, such as metallocene catalysts, Ziegler-type catalyst systems, and Ziegler-Natta-type catalyst systems. Examples of homogeneous catalyst systems include catalyst systems consisting of a transition metal compound of Group 4 of the periodic table having a cyclopentadienyl ring and an alkylaluminoxane, or catalyst systems consisting of a transition metal compound of Group 4 of the periodic table having a cyclopentadienyl ring, a compound that reacts with it to form an ionic complex, and an organoaluminum compound, or catalyst systems in which catalyst components such as a transition metal compound of Group 4 of the periodic table having a cyclopentadienyl ring, a compound that forms an ionic complex, and an organoaluminum compound are supported and modified on inorganic particles such as silica and clay minerals, and also prepolymerization catalyst systems prepared by prepolymerizing ethylene or α-olefins in the presence of the above catalyst systems.

[0062] Furthermore, high-pressure low-density polyethylene (LDPE) can be produced using a radical initiator as a polymerization catalyst.

[0063] When the resin constituting the unused resin is a polypropylene-based resin, the propylene-based polymer contained in the resin can be produced by a known polymerization method using a known olefin polymerization catalyst.

[0064] Examples of polymerization catalysts include Ziegler-type catalyst systems, Ziegler-Natta-type catalyst systems, catalyst systems consisting of a transition metal compound of Group 4 of the periodic table having a cyclopentadienyl ring and an alkylaluminoxane, or catalyst systems consisting of a transition metal compound of Group 4 of the periodic table having a cyclopentadienyl ring, a compound that reacts with it to form an ionic complex, and an organoaluminum compound, or catalyst systems in which catalytic components such as a transition metal compound of Group 4 of the periodic table having a cyclopentadienyl ring, a compound that forms an ionic complex, and an organoaluminum compound are supported on inorganic particles such as silica and clay minerals and modified. Alternatively, a prepolymerization catalyst system prepared by prepolymerizing ethylene or α-olefins in the presence of the above catalyst systems may also be used.

[0065] Also, from the perspective of improving productivity, the propylene-based polymer may be produced by a method of performing a plurality of polymerization steps in multiple stages (multi-stage polymerization method). The multi-stage polymer obtained by such a multi-stage polymerization method may contain at least two types of propylene-based polymers, or may contain one type of propylene-based polymer.

[0066] When the resin constituting the unused resin is a poly-α-olefin resin, the α-olefin polymer contained in the resin can be produced, for example, using a metallocene catalyst. As the metallocene catalyst, for example, an olefin polymerization catalyst using a transition metal compound having a group with a cyclopentadiene-shaped anion skeleton (hereinafter sometimes referred to as a "metallocene-based transition metal compound").

[0067] Examples of the metallocene-based transition metal compound include compounds represented by the formula MLaXn-a (where M is a transition metal atom of Group 4 of the periodic table of elements or a lanthanide series, L is a group having a cyclopentadiene-shaped anion skeleton or a group containing a hetero atom, at least one of which is a group having a cyclopentadiene-shaped anion skeleton, and a plurality of Ls may be cross-linked with each other, X is a halogen atom, a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, n represents the valence of the transition metal atom, and a is an integer satisfying 0 < a ≦ n).

[0068] Examples of the metallocene-based transition metal compound represented by the above formula include bis(1,3-n-butylmethylcyclopentadienyl)zirconium dichloride, bis(1,3-n-propylmethylcyclopentadienyl)zirconium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride, bis(1,3-dimethylcyclopentadienyl)zirconium dichloride, bis(1,3-diethylcyclopentadienyl)zirconium dichloride, ethylenebis(indenyl)zirconium dichloride, ethylenebis(4-methyl-1-indenyl)zirconium dichloride, ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride, and the like.

[0069] The metallocene transition metal compounds described above are preferably used in contact with an activation co-catalyst. Examples of activation co-catalysts include almoxane compounds and activation co-catalysts obtained by using organoaluminum compounds in combination with boron compounds such as trityl borate and anilinium borate. They may also be used in combination with particulate supports containing inorganic supports such as SiO2 and Al2O3, or organic supports such as polymers such as ethylene and styrene.

[0070] When the resin constituting the unused resin is an acrylic resin, the acrylic polymer contained in the resin can be polymerized by methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization, using an alkyl methacrylate having an alkyl group with 1 to 4 carbon atoms, and optionally a vinyl monomer copolymerizable with an alkyl methacrylate having an alkyl group with 1 to 4 carbon atoms.

[0071] When the resin constituting the unused resin is a polycarbonate-based resin, polymers having monomer units derived from dihydroxy compounds contained in the resin can be produced by reacting dihydroxy compounds such as divalent phenols and isosorbides with carbonylating agents using methods such as interfacial polycondensation or melt transesterification, polymerizing carbonate prepolymers using methods such as solid-phase transesterification, or polymerizing cyclic carbonate compounds using methods such as ring-opening polymerization.

[0072] In the laminated film according to this embodiment, the two surface layers may contain the recycled resin described above. The recycled resin content is preferably 50% by mass or less, and more preferably 25% by mass or less, per surface layer.

[0073] The thickness of the laminated film according to this embodiment is preferably 10 μm to 300 μm, and more preferably 100 μm to 150 μm. In the laminated film according to this embodiment, the thickness of one inner layer is preferably 30 μm to 50 μm, and the thickness of one surface layer is preferably 30 μm to 50 μm.

[0074] The laminated film according to this embodiment can be manufactured using known methods. Examples of known methods include the inflation method and the T-die method, with the inflation method being preferred.

[0075] Methods for laminating each layer include using a feed block type die, in which molten recycled or unused resin flowing into the die from multiple extruders is combined in layers within the die, and using a multi-manifold type die, in which molten recycled or unused resin flowing into the die from multiple extruders is sent to separate manifolds and combined in layers just before the lip of the die.

[0076] Laminated films can be suitably used, for example, as packaging bags for storing food, textiles, general merchandise, and as packaging containers.

[0077] 2. Bag The bag according to this embodiment includes the laminated film described above.

[0078] The aforementioned bag is manufactured by known molding methods, such as a method of heat-sealing a tubular film formed by an inflation molding method in a direction perpendicular to the pull direction (MD direction) (TD direction), or a method of stacking two films formed by a T die-cast film molding method and sealing all four sides.

[0079] The laminated film and bag according to this embodiment are not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. Furthermore, configurations and methods from other embodiments may be arbitrarily adopted and combined, and configurations and methods from one embodiment may be applied to configurations and methods from other embodiments. [Examples]

[0080] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0081] The following were used in the examples and comparative examples.

[0082] [Unused resin pellets] Unused resin pellets were prepared by blending the following (1) to (3) in a mass ratio of 68 / 29 / 3. (1) Linear low-density polyethylene (MFR = 1.5 g / 10 min, density = 923 kg / m³) 3 Pellets containing ) and an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass). (2) Linear low-density polyethylene (MFR = 0.9 g / 10 min, density = 914 kg / m³) 3 Pellets containing ) and an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass). (3) Masterbatch containing white pigment (Sumika Color Co., Ltd. "SPEM-7A1155")

[0083] [Recycled resin pellets] (Recycled resin pellet A) Recycled resin pellets were prepared from a raw material film containing the following (1) to (4) in a mass ratio of 70 / 30 / 3 / 3. (1) Linear low-density polyethylene (MFR = 1.5 g / 10 min, density = 923 kg / m³) 3 Pellets containing ) an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass) and a neutralizing agent (calcium stearate, 213 ppm). (2) Linear low-density polyethylene (MFR = 0.9 g / 10 min, density = 914 kg / m³) 3 Pellets containing ) an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass) and a neutralizing agent (calcium stearate, 213 ppm). (3) Masterbatch containing white pigment (Sumika Color Co., Ltd. "SPEM-7A1155") (4) Masterbatch containing antistatic agent (base resin density = 927 kg / m³) 3 , antistatic agent component 10% by mass

[0084] (Recycled resin pellets B) Recycled resin pellets were prepared from a raw material film containing the following (1) to (4) in a mass ratio of 87 / 13 / 3 / 3. (1) Linear low-density polyethylene (MFR = 2.0 g / 10 min, density = 913 kg / m³) 3 ) pellets containing (2) Linear low-density polyethylene (MFR = 0.9 g / 10 min, density = 914 kg / m³) 3 Pellets containing ) an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass) and a neutralizing agent (calcium stearate, 213 ppm). (3) Masterbatch containing white pigment (Sumika Color Co., Ltd. "SPEM-7A1155") (4) Masterbatch containing antistatic agent (base resin density = 927 kg / m³) 3 , antistatic agent component 10% by mass

[0085] (Recycled resin pellets C) Recycled resin pellets were prepared from a raw material film containing the following (1) to (5) in a mass ratio of 70 / 30 / 6.5 / 3 / 3. (1) Linear low-density polyethylene (MFR = 1.5 g / 10 min, density = 923 kg / m³) 3 Pellets containing ) an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass) and a neutralizing agent (calcium stearate, 213 ppm). (2) Linear low-density polyethylene (MFR = 0.9 g / 10 min, density = 914 kg / m³) 3 Pellets containing ) an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass) and a neutralizing agent (calcium stearate, 213 ppm). (3) Antioxidant masterbatch containing 22,000 ppm by mass of antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd.) (4) Masterbatch containing white pigment (Sumika Color Co., Ltd. "SPEM-7A1155") (5) Masterbatch containing antistatic agent (base resin density = 927 kg / m³) 3 , antistatic agent component 10% by mass

[0086] (Recycled resin pellets D) The mass ratio of (1) to (5) in the above recycled resin pellet-C was changed to 87 / 13 / 8 / 3 / 3 to produce recycled resin pellets.

[0087] (Recycled resin pellets E) Recycled resin pellets were prepared from a raw material film containing the following (1) to (5) in a mass ratio of 70 / 30 / 8 / 3 / 3. (1) Linear low-density polyethylene (MFR = 1.5 g / 10 min, density = 923 kg / m³) 3 Pellets containing ) an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass) and a neutralizing agent (calcium stearate, 213 ppm). (2) Linear low-density polyethylene (MFR = 0.9 g / 10 min, density = 914 kg / m³) 3 Pellets containing ) an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass) and a neutralizing agent (calcium stearate, 213 ppm). (3) Antioxidant masterbatch containing 22,000 ppm by mass of antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd.) (4) Masterbatch containing white pigment (Sumika Color Co., Ltd. "SPEM-7A1155") (5) Masterbatch containing antistatic agent (base resin density = 927 kg / m³) 3 , antistatic agent component 10% by mass

[0088] (Recycled resin pellets F) Recycled resin pellets were prepared from a raw material film containing the following (1) to (3) in a mass ratio of 70 / 30 / 3. (1) Linear low-density polyethylene (MFR = 1.5 g / 10 min, density = 923 kg / m³) 3 Pellets containing ) an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass) and a neutralizing agent (calcium stearate, 213 ppm). (2) Linear low-density polyethylene (MFR = 0.9 g / 10 min, density = 914 kg / m³) 3 Pellets containing ) an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass) and a neutralizing agent (calcium stearate, 213 ppm). (3) Masterbatch containing white pigment (Sumika Color Co., Ltd. "SPEM-7A1155")

[0089] (Recycled resin pellets G) Recycled resin pellets were prepared from a raw material film containing the following (1) to (4) in a mass ratio of 70 / 30 / 3 / 12. (1) Linear low-density polyethylene (MFR = 1.5 g / 10 min, density = 923 kg / m³) 3 Pellets containing ) an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass) and a neutralizing agent (calcium stearate, 213 ppm). (2) Linear low-density polyethylene (MFR = 0.9 g / 10 min, density = 914 kg / m³) 3 Pellets containing ) an antioxidant (SumiLizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass) and a neutralizing agent (calcium stearate, 213 ppm). (3) Masterbatch containing white pigment (Sumika Color Co., Ltd. "SPEM-7A1155") (4) Masterbatch containing antistatic agent (base resin density = 927 kg / m³) 3 , antistatic agent component 10% by mass

[0090] [Measurement method] The measured values ​​for each item in the examples and comparative examples were measured according to the following method.

[0091] <Color Tone Evaluation> Using a color computer SM-P45 manufactured by Suga Test Instruments Co., Ltd., the x-value (red color mixing ratio), y-value (green color mixing ratio), and z-value (blue color mixing ratio) of the surface layer 1 of the three-layer film prepared in the examples or comparative examples were determined based on the direct reading method of stimulus values ​​specified in JIS Z 8722. The geometric conditions for illumination and light reception were the same as condition a described in "Measurement Method for Reflective Objects". Measurements were performed three times for each sample, and the standard deviations of the x-value, y-value, and z-value were calculated. A smaller standard deviation is preferable as it indicates less variation in the color of the surface layer 1 of the three-layer film. <Yellowness (YI) Evaluation> Using a color computer SM-P45 manufactured by Suga Test Instruments Co., Ltd., the yellowness (YI) of the surface layer 1 of the three-layer films prepared in the examples and comparative examples was determined based on the reflection method described in JIS K 7103-1977. Three measurements were performed for each sample, and the average value was calculated. A smaller yellowness (YI) value indicates less yellowing of the film, which is preferable.

[0092] <Scratch resistance test> Using a friction coefficient measuring instrument AB-401 manufactured by Tester Industries Co., Ltd., samples for scratch resistance testing were prepared by rubbing the observation film described below against the surface layer 2 of the three-layer film prepared in the example or comparative example. Except for moving a sliding plate to which the observation film was fixed under the conditions of a 700g thread and a sliding speed of 200m / min, the observation film was slid on the top layer 2 of a 3-layer film according to the procedure of JIS K7125-1987. The surface of the observation film was observed using an optical microscope (MicroSupport: AxisPro SS) at 1948.3x magnification and in reflection mode. Observation was performed at 16 locations (4 vertically and 4 horizontally) arbitrarily selected from the scratched area. In each observation area, 5 fields of view x 5 fields of view were observed, and the images of a total of 25 fields of view were combined to form a single image. The number of scratches displayed in the obtained image was measured, and the number of scratches per unit area was calculated using the field of view size of the image, and the average was calculated for all observation areas.

[0093] (Observation film used in scratch resistance test) Ethylene-1-hexene copolymer (Sumitomo Chemical Co., Ltd. "Excellen GMH CB0004", MFR = 0.4 g / 10 min, density = 926 kg / m³) 3 A 100μm thick film made of ).

[0094] [Example 1] A laminated film was fabricated using co-extrusion inflation molding, with surface layer 1, inner layer, and surface layer 2 stacked in that order. Unused resin pellets were used as the resin pellets for surface layer 1 and surface layer 2. Recycled resin pellets were used as the resin pellets for the inner layer. Co-extrusion inflation molding was performed using a Placo three-layer inflation film processing machine with a die temperature of 200°C, a total extrusion rate of 30 kg / h, a blow ratio of 2.0, and a take-up speed of 4.4 m / min to produce a laminated film with surface layer 1 / inner layer / surface layer 2 thicknesses of 40 μm / 40 μm / 40 μm. The resulting laminated film was evaluated for color tone and subjected to scratch resistance tests. The results are shown in Table 1.

[0095] [Comparative Example 1] A multilayer film was prepared in the same manner as in Example 1, except that the above-mentioned unused resin pellets were used as the resin pellets for the surface layer 1 and the resin pellets for the inner layer, and the above-mentioned recycled resin pellet A was used as the resin pellets for the surface layer 2. The obtained multilayer film was subjected to color evaluation and scratch resistance testing. The results are shown in Table 1.

[0096] [Comparative Example 2] A multilayer film was prepared in the same manner as in Example 1, except that the above-mentioned recycled resin pellet A was used as the resin pellet for the surface layer 1, and the above-mentioned unused resin pellet was used as the resin pellet for the inner layer and the resin pellet for the surface layer 2. The obtained multilayer film was subjected to color evaluation and scratch resistance testing. The results are shown in Table 1.

[0097] [Comparative Example 3] A multilayer film was prepared in the same manner as in Example 1, except that the recycled resin pellets A described above were used as the resin pellets for the surface layer 1, the inner layer, and the surface layer 2. The resulting multilayer film was subjected to color evaluation and scratch resistance testing. The results are shown in Table 1.

[0098] [Reference example 1] A multilayer film was prepared in the same manner as in Example 1, except that the above-mentioned unused resin pellets were used as the resin pellets for the surface layer 1, the inner layer, and the surface layer 2. The resulting multilayer film was subjected to color evaluation and scratch resistance testing. The results are shown in Table 1.

[0099] [Example 2] A multilayer film was prepared in the same manner as in Example 1, except that the above-mentioned unused resin pellets were used as the resin pellets for surface layer 1 and surface layer 2, and the above-mentioned recycled resin pellet B was used as the resin pellets for the inner layer. The obtained multilayer film was subjected to color evaluation and scratch resistance testing. The results are shown in Table 2.

[0100] [Example 3] A multilayer film was prepared in the same manner as in Example 1, except that the above-mentioned unused resin pellets were used as the resin pellets for surface layer 1 and surface layer 2, and the above-mentioned recycled resin pellets F were used as the resin pellets for the inner layer. The obtained multilayer film was subjected to color evaluation and scratch resistance testing. The results are shown in Table 2.

[0101] [Example 4] A multilayer film was prepared in the same manner as in Example 1, except that the above-mentioned unused resin pellets were used as the resin pellets for the first and second surface layers, and the above-mentioned recycled resin pellets G were used as the resin pellets for the inner layer. The resulting multilayer film was subjected to color evaluation and scratch resistance testing. The results are shown in Table 2.

[0102] [Comparative Example 4] A multilayer film was prepared in the same manner as in Example 1, except that the above-mentioned unused resin pellets were used as the resin pellets for the first and second surface layers, and the above-mentioned recycled resin pellet C was used as the resin pellets for the inner layer. The resulting multilayer film was subjected to color evaluation and scratch resistance testing. The results are shown in Table 2.

[0103] [Comparative Example 5] A multilayer film was prepared in the same manner as in Example 1, except that the above-mentioned unused resin pellets were used as the resin pellets for the first and second surface layers, and the above-mentioned recycled resin pellets D were used as the resin pellets for the inner layer. The resulting multilayer film was subjected to color evaluation and scratch resistance testing. The results are shown in Table 2.

[0104] [Comparative Example 6] A multilayer film was prepared in the same manner as in Example 1, except that the above-mentioned unused resin pellets were used as the resin pellets for the first and second surface layers, and the above-mentioned recycled resin pellets E were used as the resin pellets for the inner layer. The resulting multilayer film was subjected to color evaluation and scratch resistance testing. The results are shown in Table 2.

[0105] [Table 1]

[0106] [Table 2]

[0107] As can be seen from the results in Tables 1 and 2, the laminated films of each example that satisfy all the constituent requirements of the present invention have smaller standard deviations of x, y, and z values ​​compared to the laminated films of each comparative example, indicating less variation in color, and thus relatively superior appearance. Furthermore, the laminated films of each example that satisfy all the constituent requirements of the present invention have fewer scratches in the scratch resistance test compared to the laminated films of each comparative example, indicating relatively low damage resistance. In addition, the multilayer films of Examples 1 and 2, which have an antistatic agent content of 100 ppm to 8000 ppm by mass, have smaller yellowness (YI) values, indicating relatively superior hue. [Industrial applicability]

[0108] According to the present invention, it is possible to provide a laminated film that contains recycled resin, has a relatively good appearance, and is relatively resistant to damage, as well as a bag containing the laminated film.

Claims

1. A laminated film comprising three or more resin layers, including at least one inner layer and two surface layers, The at least one inner layer contains a recycled resin composition comprising a recycled resin and an antioxidant, wherein the content of the antioxidant is 100 ppm by mass to 2000 ppm by mass relative to the recycled resin composition. The two surface layers mentioned above contain unused resin, The recycled resin contains a polymer comprising monomer units derived from at least one selected from the group consisting of ethylene, propylene, and α-olefins having 4 to 12 carbon atoms. A laminated film in which the content of the resin containing the polymer is 99.5% by mass or more relative to the recycled resin.

2. A laminated film comprising three resin layers, including at least one inner layer and two surface layers, The at least one inner layer contains a recycled resin composition comprising a recycled resin and an antioxidant, wherein the content of the antioxidant is 100 ppm by mass to 2000 ppm by mass relative to the recycled resin composition. The two surface layers mentioned above contain unused resin, A laminated film in which the recycled resin content is 90% by mass or more relative to the recycled resin composition.

3. The laminated film according to claim 1 or 2, wherein the content of the antioxidant is 500 ppm by mass to 1000 ppm by mass with respect to the recycled resin composition.

4. The laminated film according to any one of claims 1 to 3, wherein the recycled resin composition further contains an antistatic agent.

5. The laminated film according to claim 4, wherein the content of the antistatic agent is 100 ppm by mass to 8000 ppm by mass with respect to the recycled resin composition.

6. The laminated film according to claim 5, wherein the content of the antistatic agent is 100 ppm by mass to 2000 ppm by mass relative to the recycled resin composition.

7. The laminated film according to any one of claims 1 to 6, wherein the recycled resin composition further contains a neutralizing agent.

8. The laminated film according to claim 7, wherein the content of the neutralizing agent is 100 ppm by mass to 2000 ppm by mass relative to the recycled resin composition.

9. A laminated film according to claim 1, comprising three resin layers.

10. A laminated film according to any one of claims 1 to 8, having a thickness of 100 μm to 150 μm.

11. The laminated film according to any one of claims 1 to 10, wherein the resin constituting the unused resin is a resin comprising a polymer consisting of monomer units derived from at least one selected from the group consisting of ethylene, propylene, and α-olefins having 4 to 12 carbon atoms.

12. The laminated film according to any one of claims 1 to 11, wherein the resin constituting the recycled resin and the unused resin is an ethylene homopolymer or a resin containing an ethylene copolymer containing more than 50% by mass of monomer units derived from ethylene.

13. The laminated film according to claim 12, wherein the ethylene copolymer contains 90% by mass or more monomer units derived from ethylene.

14. A bag comprising a laminated film according to any one of claims 1 to 13.

Images