Recycled polyolefin film, resin laminate and packaging material

Abstract

To provide a regenerated polyolefin film relatively excellent in strength, a laminate thereof and a packaging material thereof.SOLUTION: The recycled polyolefin film is obtained by using a recycled material obtained by pelletizing a polyolefin resin laminate having at least a polyolefin stretched substrate and a polyolefin sealant, wherein the content of the recycled material is 10 mass% or more (the total mass of the recycled polyolefin film is 100 mass%).

Description

[Technical Field]

[0001] The present invention relates to a recycled polyolefin film, a resin laminate containing at least one layer made of the film, and a packaging material. [Background technology]

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

[0003] In material recycling, the two most common methods are global recycling, in which waste plastics used in films, sheets, containers, and other products with large markets are exported overseas for recycling, and cascade recycling, in which the quality is reduced and the plastics are used as raw materials for other products with smaller markets. However, in recent years, due to import restrictions on waste plastics in Asian countries, recycled raw materials (recycled materials) have been concentrated in products with smaller markets, and there is an urgent need to expand the range of products to which recycled raw materials can be applied. In particular, horizontal recycling, in which waste plastics are used 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 used for horizontal recycling.

[0004] As a method for reusing waste plastics through horizontal recycling, for example, Patent Document 1 discloses a method in which used plastic shopping bags that are no longer needed are collected, and if any colored parts are present, the colored parts are removed, and then the bags are crushed and melted to form re-pellets, thereby obtaining recycled raw materials, and further this recycled raw materials are mixed with new raw materials to produce new plastic shopping bags. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-148938 Summary of the Invention [Problem to be solved by the invention]

[0006] It is desirable that recycled polyolefin films obtained using recycled materials in horizontal recycling have performance equivalent to that of polyolefin films (virgin polyolefin films) obtained using unused resin (virgin resin). However, recycled polyolefin films obtained using conventional recycled materials have the problem of being inferior in strength due to the inclusion of resins other than polyolefin. The present invention has been made in light of these current circumstances, and aims to provide a recycled polyolefin film having relatively excellent strength, a laminate thereof, and a packaging material thereof. Another aim of the present invention is to provide a monomaterial laminate using the recycled polyolefin film, and a packaging material thereof. [Means for solving the problem]

[0007] As a result of extensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using a recycled material obtained by pelletizing a polyolefin resin laminate having a polyolefin oriented substrate and a polyolefin sealant. Based on these findings, the present invention has been completed. That is, according to the first aspect of the present invention, there is provided a recycled polyolefin film obtained using recycled material obtained by pelletizing a polyolefin resin laminate having at least a polyolefin oriented base material and a polyolefin sealant, characterized in that the recycled material content is 10% by mass or more (the total mass of the recycled polyolefin film is 100% by mass). According to the second invention, there is provided a recycled polyolefin film according to the first invention, characterized in that the ratio of the Elmendorf tear strength of the recycled polyolefin film to the Elmendorf tear strength of a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin in the same content as the recycled material (wherein the virgin resin has a composition corresponding to that of a polyolefin resin laminate) is 0.7 or more in the direction perpendicular to the machine direction (the Elmendorf tear strength is measured in accordance with JIS K7128-2). According to the third invention, there is provided a recycled polyolefin film according to the first or second invention (film impact is measured with reference to JIS K7128-2), characterized in that the ratio of the film impact of the recycled polyolefin film to the film impact of a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin in the same content as the recycled material (wherein the virgin resin has a composition corresponding to that of a polyolefin resin laminate) is 0.7 or more. According to the fourth invention, there is provided a recycled polyolefin film according to any one of the first to third inventions (the tensile test is measured in accordance with JIS K7127), characterized in that in a tensile test of a recycled polyolefin film and a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin in the same content as the recycled material (wherein the virgin resin has a composition corresponding to that of a polyolefin resin laminate), the ratio of the breaking strength in the machine direction to the direction perpendicular to the machine direction is 0.7 or more. According to the fifth invention, there is provided a recycled polyolefin film according to any one of the first to fourth inventions (the dirt drop impact test is measured with reference to JIS K7124), characterized in that the ratio between the dirt drop impact test result of the recycled polyolefin film and the dirt drop impact test result of a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin in the same content as the recycled material (wherein the virgin resin has a composition corresponding to that of a polyolefin resin laminate) is 0.7 or more. According to a sixth aspect of the present invention, there is provided a recycled polyolefin film according to any one of the first to fifth aspects of the present invention, characterized in that it contains, in addition to recycled materials, a polyethylene resin composition that satisfies the following requirements: 1) Density: 0.900~0.930g / cm3 2) Melt flow rate (MFR) at 190°C under a load of 2.16 kg is 0.1 to 20 g / 10 min. 3) The molecular weight distribution (Mw / Mn), which is the ratio of number average molecular weight (Mn) to weight average molecular weight (Mw) determined by GPC, is 1.8 to 3.5.

[0008] According to a seventh aspect of the present invention, there is provided a resin laminate comprising at least one layer made of the recycled polyolefin film according to any one of the first to sixth aspects of the present invention. According to the eighth invention, there is provided the resin laminate according to the seventh invention, which is a polyolefin monomaterial resin laminate in which all layers constituting the resin laminate are made of the same polyolefin resin composition.

[0009] According to a ninth aspect of the present invention, there is provided a packaging material using the resin laminate according to the seventh or eighth aspect of the present invention. [Effects of the Invention]

[0010] The recycled polyolefin film of the present invention can provide a recycled polyolefin film with reduced environmental impact that has strength similar to that of virgin polyolefin films made from virgin resin.The use of this recycled polyolefin film can provide laminates and packaging materials with reduced environmental impact, particularly mono-material laminates and packaging materials that are made from a single material, from recycled materials to laminates and packaging materials. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention relates to a recycled polyolefin film, a laminate having a layer thereof, and a packaging material constructed therefrom.

[0012] 1. Recycled polyolefin film One embodiment of the present invention is a recycled polyolefin film obtained using recycled material obtained by pelletizing a polyolefin resin laminate having at least a polyolefin oriented substrate and a polyolefin sealant, characterized in that the recycled material content is 10% by mass or more (the total mass of the recycled polyolefin film is taken as 100% by mass) (hereinafter also referred to as the "recycled polyolefin film of the present invention"). The present invention will be described in detail below for each item.

[0013] (1) Polyolefin resin laminate The polyolefin resin laminate used in the recycled polyolefin film of the present invention comprises a stretched polyolefin substrate and a polyolefin sealant. By using polyolefin for both the stretched substrate and the sealant layer, the recyclability of the packaging laminate can be improved. Furthermore, by using the same polyolefin for the stretched substrate and the sealant layer, the recyclability of the packaging laminate can be further improved.

[0014] (1-1) Polyolefin oriented substrate In this specification, the term "stretched polyolefin substrate" refers to a film obtained by stretching a film obtained by inflation molding or T-die molding of a polyolefin resin composition, and is a stretched film used as a substrate for a resin laminate.

[0015] The stretched polyolefin substrate is obtained by stretching a raw film made of a polyolefin resin composition. Examples of methods for producing the raw film include inflation molding, T-die molding, and calender molding, with inflation molding and T-die molding being preferred from the viewpoints of production speed and ease of production. The substrate may be a single-layer film made of a single polyolefin resin composition, or a multi-layer film made of multiple polyolefin resin compositions.

[0016] The stretched substrate may be a uniaxially stretched film or a biaxially stretched film, and the stretching method may be any of longitudinal uniaxial stretching, transverse uniaxial stretching, sequential biaxial stretching, and simultaneous biaxial stretching.

[0017] (1-2) Polyolefin sealant In this specification, a polyolefin sealant is a film that contains at least one layer made of a polyolefin resin composition and is characterized by being able to seal by fusing these layers.

[0018] The sealant film can be produced by known techniques. Specific examples include inflation molding, T-die molding, and calendar molding, with inflation molding and T-die molding being preferred. The thickness of the sealant film is not particularly limited, but is preferably 10 to 200 μm, and more preferably 30 to 180 μm. The sealant may be of single layer or multi-layer construction.

[0019] (1-3) Polyolefin resin composition The polyolefin resin composition used as a raw material for the oriented polyolefin substrate and polyolefin sealant in the present invention refers to either a single resin or a mixture of resins such as polyethylene resin, polypropylene resins such as propylene homopolymer, propylene-ethylene random copolymer, and propylene-ethylene block copolymer, polybutene resin, and poly-4-methyl-pentene-1 resin, to which necessary additives may be added.

[0020] (Polyethylene resin composition) The polyethylene resin for constituting the polyethylene resin composition is produced using either or both of ethylene derived from petroleum feedstocks and ethylene derived from biomass feedstocks as raw materials, using a conventionally known catalyst such as a metal catalyst such as a Ziegler-Natta catalyst, a Phillips catalyst, or a metallocene catalyst. Generally, these catalysts are in the form of a complex composed of an organometallic compound supported on a carrier such as silica or a Mg compound. Polymerization methods include high-pressure, solution, slurry, and gas-phase polymerization. High-pressure polymerization uses a radical-generating source such as oxygen or peroxide, or a catalyst composed of a metal complex, as an initiator. Ethylene, comonomer, and initiator are introduced into a reactor under high-temperature and high-pressure conditions. Depending on the reactor shape, this can be further divided into tubular and autoclave processes. Solution polymerization is carried out in a state where the polymer is dissolved in a hydrocarbon solvent at a temperature above the melting point of the polymer. Slurry polymerization uses a hydrocarbon compound such as hexane or isobutane as the solvent, and the resulting polyethylene exists in the solvent as a slurry. Depending on the reactor shape, it can be broadly divided into autoclave and loop-pipe processes. Gas-phase polymerization is a polymerization method in which ethylene, an α-olefin as a comonomer, and hydrogen as a chain transfer agent are fed in gaseous form into the bottom of a vertical reactor, followed by the addition of a polymerization catalyst (edited by Kazuo Matsuura and Hisataka Mikami, Polyethylene Technology Reader). The polyethylene resin composition of the present invention is preferably one polymerized using a metal catalyst. The polyethylene resin compositions obtained by these production methods have a wide range of combinations of density, melt flow rate (MFR), and other resin physical properties in order to meet the various applications known so far. The polyethylene resin composition may be an ethylene homopolymer or a copolymer of ethylene and one or more α-olefins selected from α-olefins having 3 to 18 carbon atoms. The α-olefins having 3 to 18 carbon atoms are preferably those having 3 to 12 carbon atoms, and specific examples include propylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene. The total content of these α-olefins is preferably selected within a range of usually 30 mol% or less, and preferably 20 mol% or less. Within this range, films and the like will have good flexibility and heat resistance. Here, the content of α-olefin is a value measured by 13C-NMR under the following conditions. Equipment: JEOL-GSX270 manufactured by JEOL Concentration: 300mg / 2mL Solvent: orthodichlorobenzene

[0021] (Polypropylene resin) The polypropylene resin is a resin containing a propylene polymer. The propylene polymer is a polymer containing more than 50% by mass of monomer units derived from propylene, i.e., a propylene homopolymer or a propylene copolymer containing more than 50% by mass of monomer units derived from propylene. The propylene copolymer is preferably a copolymer of propylene and ethylene and / or an α-olefin having 4 to 10 carbon atoms. The melt flow rate (MFR) of the propylene homopolymer measured at a temperature of 230°C under a load of 2.16 kg is preferably 0.1 g / 10 min to 50 g / 10 min. The melt flow rate (MFR) of the copolymer of propylene with ethylene and / or an α-olefin having 4 to 10 carbon atoms measured at a temperature of 230°C under 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 specified in JIS K7210-1. When the total mass of the copolymer of ethylene and / or an α-olefin having 4 to 10 carbon atoms and propylene is taken as 100 mass%, the content of monomer units derived from ethylene and / or an α-olefin having 4 to 10 carbon atoms is preferably 0.1 mass% to 40 mass%, and the content of monomer units derived from propylene is preferably 60 mass% to 99.9 mass%. Examples of the α-olefin having 4 to 10 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, etc. The α-olefin having 4 to 10 carbon atoms is preferably 1-butene, 1-hexene, or 1-octene. Specific examples of the copolymer of propylene with ethylene and / or an α-olefin having 4 to 10 carbon atoms include a copolymer of propylene and ethylene, a copolymer of propylene and an α-olefin having 4 to 10 carbon atoms, and a copolymer of propylene, ethylene and an α-olefin having 4 to 10 carbon atoms. The copolymer of propylene with ethylene and / or an α-olefin having 4 to 10 carbon atoms may be used alone or in combination of two or more. The propylene polymer may also be a mixture of a propylene homopolymer and a copolymer of propylene with ethylene and / or an α-olefin having 4 to 10 carbon atoms. Examples of copolymers of propylene and an α-olefin having 4 to 10 carbon atoms include a propylene-1-butene copolymer, a propylene-1-hexene copolymer, a propylene-1-octene copolymer, and a propylene-1-decene copolymer. Examples of copolymers of propylene, ethylene, and an α-olefin having 4 to 10 carbon atoms include propylene-ethylene-1-butene copolymer, propylene-ethylene-1-hexene copolymer, propylene-ethylene-1-octene copolymer, and propylene-ethylene-1-decene copolymer.

[0022] (1-4) Structure and manufacturing method of polyolefin resin laminate The polyolefin resin laminate is a resin laminate including a layer made of a oriented polyolefin substrate and a sealant layer made of a polyolefin sealant, and is obtained by laminating the oriented polyolefin substrate and the polyolefin sealant. Here, the ratio (mass ratio) of the content of the layer made of the oriented polyolefin base material to the content of the polyolefin sealant in the polyolefin resin laminate is preferably 1 / 1 or less, more preferably 1 / 4 or less.

[0023] (1-5) Adhesive layer The polyolefin resin laminate may include an adhesive layer between the oriented polyolefin substrate and the sealant layer. Examples of the adhesive layer include an extruded resin layer containing polyethylene as a main component and an adhesive layer composed of an adhesive.

[0024] In one embodiment, the polyolefin resin laminate includes an extruded resin layer containing polyethylene as a main component between the oriented polyolefin substrate and the sealant layer, and the extruded resin layer functions as an adhesive layer between the two. By providing the polyolefin resin laminate with an extruded resin layer containing polyethylene as the adhesive layer, the polyolefin content in the laminate can be made higher than when a conventional non-polyethylene adhesive (e.g., a two-component curing polyurethane adhesive) is used, thereby further improving the recyclability of the laminate.

[0025] The extruded resin layer contains polyethylene as a main component. Details of the polyethylene are as described above in the section on the polyethylene resin composition. The polyethylene in the extruded resin layer and the polyethylene in the sealant layer may be the same or different. The polyethylene contained in the extruded resin layer is preferably at least one selected from low-density polyethylene, linear low-density polyethylene, and very low-density polyethylene from the viewpoint of adhesiveness, and more preferably low-density polyethylene or linear low-density polyethylene. As the polyethylene, recycled polyethylene may be used from the viewpoint of reducing the environmental load.

[0026] The stretched polyethylene substrate as the base material and the sealant film as the sealant layer can be bonded together by, for example, melt extrusion lamination using a molten resin containing polyethylene as the main component, particularly sand lamination. This method can increase the polyethylene content of the laminate. Furthermore, compared to laminating these materials by dry lamination, the time required for the drying and aging processes can be reduced, thereby improving the production efficiency of the laminate.

[0027] In one embodiment, the polyolefin resin laminate includes an adhesive layer formed of an adhesive between the oriented polyolefin substrate and the sealant layer, which can improve the adhesive strength between the two, for example. The adhesive may be a one-component curing adhesive, a two-component curing adhesive, or a non-curing adhesive. The adhesive may be a solvent-based adhesive or a solventless adhesive. Examples of solvent-based adhesives include rubber-based adhesives, vinyl-based adhesives, olefin-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and urethane-based adhesives. Examples of solventless adhesives include polyether-based adhesives, polyester-based adhesives, silicone-based adhesives, epoxy-based adhesives, and urethane-based adhesives. Among these, urethane-based adhesives are preferred, and two-component curing urethane-based adhesives are more preferred.

[0028] Examples of adhesive coating methods include direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fontaine coating, and transfer roll coating. The thickness of the adhesive layer formed by the above adhesive is preferably 0.1 μm or more, more preferably 0.2 μm or more, even more preferably 0.5 μm or more, and is preferably 10 μm or less, more preferably 8 μm or less, even more preferably 6 μm or less.

[0029] The polyolefin resin laminate can be produced by bonding a stretched polyolefin substrate as the substrate and a sealant film as the sealant layer by a lamination method using the above adhesive. The laminate of the present disclosure may be produced by bonding the two layers by, for example, a dry lamination method using a solvent-based adhesive, or by a non-solvent lamination method using a solvent-free adhesive.

[0030] (2) Recycled material In the recycled polyolefin film of the present invention, it is important to use a recycled material that is a polyolefin resin laminate having a stretched polyolefin substrate and a polyolefin sealant, which has been pelletized. By using this recycled material, polyolefin films, laminates, and packaging materials with reduced environmental impact can be provided.

[0031] The recycled material is obtained by cutting or crushing a polyolefin resin laminate containing a stretched polyolefin substrate and a polyolefin sealant into fragments, heating and melting the resulting material, kneading the resulting material, and extruding the resulting resin composition. The polyolefin resin laminate is preferably washed, dehydrated, and dried.

[0032] (3) Recycled polyolefin film (3-1) Recycled polyolefin film blend The recycled material content in the recycled polyolefin film of the present invention is 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more, with the total mass of the recycled polyolefin film being 100% by mass. If the recycled material content is 10% by mass or more, a reduction in the environmental impact can be expected. The upper limit of the recycled material content is preferably 100% by mass or less, and more preferably 70% by mass or less.

[0033] The recycled polyolefin film of the present invention may also contain polyolefin resins other than recycled materials, such as polyethylene resins, polypropylene resins such as propylene homopolymers, propylene-ethylene random copolymers, and propylene-ethylene block copolymers, polybutene resins, and poly-4-methyl-pentene-1 resins, either alone or in combination.

[0034] The recycled polyolefin film of the present invention may also contain additives, such as antioxidants, weathering agents, lubricants, antiblocking agents, antistatic agents, antifogging agents, anti-dripping agents, pigments, and fillers.

[0035] (3-2) Manufacturing of recycled polyolefin film The recycled polyolefin film can be produced by known techniques using a composition (recycled material composition) containing recycled materials and optional additives. Specific examples include inflation molding, T-die molding, and calendar molding, with inflation molding and T-die molding being preferred. The recycled polyolefin film of the present invention may have a single-layer structure or a multi-layer structure.

[0036] (3-3) Characteristics of recycled polyolefin film The recycled polyolefin film of the present invention can have strength similar to that of a virgin polyolefin film made from virgin resin. In this specification, virgin polyolefin film means a film obtained by inflation molding or T-die molding of a virgin polyolefin resin composition. The recycled polyolefin film may be a monolayer film made from a single polyolefin resin composition, or a multilayer film made from multiple polyolefin resin compositions.

[0037] One preferred embodiment of the recycled polyolefin film of the present invention is a recycled polyolefin film having the following properties: (Characteristic 1) The ratio of the Elmendorf tear strength of the recycled polyolefin film to the Elmendorf tear strength of a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin in the same content as the recycled material is 0.7 or more in the direction perpendicular to the machine direction. Here, the Elmendorf tear strength is measured in accordance with JIS K7128-2.

[0038] Property 1 indicates that when the Elmendorf tear strength of a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin in an amount equal to the recycled material content is measured, and the Elmendorf tear strength of a recycled polyolefin film is measured, the ratio of the two (i.e., Elmendorf tear strength of the recycled polyolefin film / Elmendorf tear strength of the virgin polyolefin film) is 0.7 or more in the direction perpendicular to the machine direction. According to Feature 1, recycled polyolefin films obtained using conventional recycled materials have poor tear strength, but it is possible to obtain recycled polyolefin films that have relatively excellent tear strength in the direction perpendicular to the machine direction, even when containing recycled materials, and that are close to that of virgin polyolefin films. Here, the virgin resin has a composition corresponding to that of a polyolefin resin laminate, which is the raw material of the recycled material that constitutes the recycled polyolefin film. The composition corresponding to the polyolefin resin laminate is preferably a composition in which 90 mass % or more of the resin composition of the virgin resin is a polyolefin in the same density range as the polyolefin contained in the polyolefin resin laminate. Here, the term "same density range" means that the densities of the two polyolefins are close, and preferably the difference in density is 0.01 to 0.1 g / cm. 3 is.

[0039] The ratio of the Elmendorf tear strength of the recycled polyolefin film to the Elmendorf tear strength of the virgin polyolefin film in the direction perpendicular to the machine direction is preferably 0.7 or more, more preferably 0.75 or more.

[0040] Another preferred embodiment of the recycled polyolefin film of the present invention is a recycled polyolefin film having the following properties: (Characteristic 2) The ratio of the film impact of the recycled polyolefin film to the film impact of a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin in the same content as the recycled material is 0.7 or more.

[0041] Here, the film impact is measured with reference to JIS K7128-2. Virgin polyolefin film and virgin resin are as explained in Property 1.

[0042] Due to property 2, recycled polyolefin films obtained using conventional recycled materials have poor impact strength, but even when containing recycled materials, it is possible to obtain recycled polyolefin films with relatively excellent impact strength, close to that of virgin polyolefin films.

[0043] The ratio of the film impact of the recycled polyolefin film to the film impact of the virgin polyolefin film is preferably 0.7 or more, more preferably 0.9 or more.

[0044] Another preferred embodiment of the recycled polyolefin film of the present invention is a recycled polyolefin film having the following properties: (Characteristic 3) In a tensile test of a recycled polyolefin film and a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin of the same content as the recycled material, the ratio of the breaking strength in the machine direction to the direction perpendicular to the machine direction is 0.7 or more. Here, the tensile test is carried out in accordance with JIS K7127.

[0045] Virgin polyolefin film and virgin resin are as explained in Property 1. According to Feature 3, recycled polyolefin films obtained using conventional recycled materials have inferior tensile strength, but even when containing recycled materials, recycled polyolefin films can be obtained that have excellent comparative tensile strength, close to that of virgin polyolefin films.

[0046] In a tensile test, the ratio of the breaking strength in the machine direction and the direction perpendicular to the machine direction of the recycled polyolefin film to the breaking strength in the machine direction and the direction perpendicular to the machine direction of the virgin polyolefin film is preferably 0.7 or more, more preferably 0.8 or more.

[0047] Another preferred embodiment of the recycled polyolefin film of the present invention is a recycled polyolefin film having the following properties: (Characteristic 4) The ratio of the dirt drop impact test result of the recycled polyolefin film to the dirt drop impact test result of a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin of the same content as the recycled material is 0.7 or more. Here, the dirt drop impact test is measured with reference to JIS K7124.

[0048] Virgin polyolefin film and virgin resin are as explained in Property 1. According to Feature 4, recycled polyolefin films obtained using conventional recycled materials have poor impact strength, but it is possible to obtain recycled polyolefin films that contain recycled materials and have relatively excellent impact strength, close to that of virgin polyolefin films.

[0049] The ratio of the dirt drop impact test score of the recycled polyolefin film to that of the virgin polyolefin film is preferably 0.7 or more, more preferably 0.9 or more.

[0050] In one preferred embodiment of the recycled polyolefin film of the present invention, it has any one of the properties (1) to (4). In a more preferred embodiment of the recycled polyolefin film of the present invention, the film has any two of the properties (1) to (4). In a more preferred embodiment of the recycled polyolefin film of the present invention, the film has any three of the properties (1) to (4). In a particularly preferred embodiment of the recycled polyolefin film of the present invention, it has all of the properties (1) to (4).

[0051] Another preferred embodiment of the recycled polyolefin film of the present invention contains, in addition to the recycled material, a polyethylene resin composition (hereinafter also referred to as "polyethylene resin composition A") that satisfies the following requirements: 1) Density: 0.900~0.930g / cm 3 2) Melt flow rate (MFR) at 190°C under a load of 2.16 kg is 0.1 to 20 g / 10 min. 3) The molecular weight distribution (Mw / Mn), which is the ratio of number average molecular weight (Mn) to weight average molecular weight (Mw) determined by GPC, is 1.8 to 3.5.

[0052] By including the polyethylene resin composition, it is possible to obtain a recycled polyolefin film that is close to virgin polyolefin films and has relatively excellent tear strength, impact strength, and tensile strength.

[0053] In one embodiment of the recycled polyolefin film of the present invention, the recycled polyolefin film preferably contains 10% by mass or more and 100% by mass or less of recycled material and 0% by mass or more and 90% by mass or less of polyethylene resin composition A, with the total mass of the recycled polyolefin film being 100% by mass, and more preferably contains 30% by mass or more and 70% by mass or less of recycled material and 30% by mass or more and 70% by mass or less of polyethylene resin composition A.

[0054] 2. Resin laminate Another embodiment of the present invention is a resin laminate comprising at least one layer made of the recycled polyolefin film of the present invention (hereinafter also referred to as "resin laminate of the present invention").

[0055] The resin laminate of the present invention may contain, in addition to the recycled polyolefin film of the present invention, a film (other film) composed of at least one polyolefin resin composition and obtained by inflation molding or T-die molding. Furthermore, the method of laminating the recycled polyolefin film of the present invention with another film may involve further stretching the co-extrusion film obtained by co-extrusion molding, or bonding the films together using an adhesive. The resin laminate may include a layer made of a stretched film as a substrate and a polyethylene resin sealant as a sealant layer.

[0056] The resin laminate may be a resin laminate in which all of the layers constituting the resin laminate are made of a polyethylene-based resin or a polypropylene-based resin, and this resin laminate can be treated as a mono-material resin laminate. That is, one preferred embodiment of the present invention is a polyolefin monomaterial resin laminate in which all layers constituting the resin laminate are made of the same polyolefin resin composition. The proportion of the main component in the monomaterial resin laminate is not particularly limited, but is preferably 80% by weight, more preferably 90% by weight.

[0057] (glue) An adhesive can be used to laminate the resin laminate. The adhesive used contains at least one resin composition, but there are no particular limitations. Examples of adhesives that can be used include epoxy, acrylic, and urethane adhesives. The adhesive containing any of the above resin compositions is not particularly limited, and one-component, two-component, or hot melt type may be used as needed. Furthermore, using an adhesive with barrier properties, such as PASLIM (manufactured by DIC) or Maxive (manufactured by Mitsubishi Gas Chemical Company, Inc.), is preferable because it reduces the amount of other barrier materials used and increases the proportion of polyolefin in the resin laminate.

[0058] 3. Packaging materials The laminate of the present invention can be particularly suitably used as a packaging material. That is, another embodiment of the present invention is a packaging material using the resin laminate of the present invention (hereinafter also referred to as "packaging material of the present invention").

[0059] The shape of the packaging material is not particularly limited and may be a packaging bag or a stand-up pouch. In the stand-up pouch, only the body, only the bottom, or both the body and the bottom may be formed of the resin laminate. [Example]

[0060] The present invention will be explained in more detail below by showing examples and comparative examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. The test and evaluation methods and materials used in the examples are as follows.

[0061] 1. Test and evaluation methods <Evaluation method> (1) Density Measurements were carried out in accordance with JIS K6922-1 and 2.

[0062] (2) MFR Measurement was carried out in accordance with JIS K6922-2 at 190°C under a load of 2.16 kg.

[0063] (3)Molecular weight distribution Measurement was carried out by GPC (Gel Permeation Chromatography) under the following conditions. [Measurement conditions] Model used: Polymer Char HT GPC-IR System Detector: IR-6 Measurement temperature: 145℃ Solvent: Orthodichlorobenzene (ODCB) (trimethylphenol 3.6g / 18L added as antioxidant) Column: Showa Denko Shodex HT-806M x 2 Flow rate: 1.0mL / min Injection volume: 20μL Sample preparation 5-8 mg of sample was placed in a vial and set in the autosampler. 8 mL of solvent (room temperature) was injected into the autosampler, and the autosampler was programmed to dissolve the sample at 150 °C for 2 hours. Heptane was used as a flow marker to correct the pump flow rate. -Creating a calibration curve A calibration curve was prepared using standard polystyrenes, including the Showdex Standard SM-105 sample set, n-eicosane, and n-tetracontane, and the values ​​were converted to polyethylene. Molecular weight calculation Measurements were performed under the above conditions, and chromatograms were recorded at sampling intervals of 1 s. Chromatogram recording (data acquisition) and average molecular weight calculation were performed using dedicated software (GPC One, manufactured by Polymer Char) on a PC with Microsoft Windows 10 installed.

[0064] (4)Environmental load The environmental impact was judged based on the following criteria: ○: Recycled materials used ×: No recycled materials used

[0065] (5) Breaking strength Measurements were made with the following equipment and conditions, with reference to JIS K7127. MD is the machine direction, and TD is the value in the transverse direction. Equipment: Tensilon universal testing machine manufactured by Orientec Co., Ltd. Test piece: Test piece type 5 specified in JIS K7127 was used Tensile speed: 500 mm / min Chuck distance: 65mm Measurement environment: temperature 23℃, humidity 50%

[0066] (6) Elmendorf tear strength Measurements were made in accordance with JIS K7128-2 using the following equipment and conditions, where MD is the machine direction and TD is the transverse direction. Equipment: Digital Elmendorf tear tester, model SA (manufactured by Toyo Seiki Seisakusho Co., Ltd.) Measurement environment: temperature 23℃, humidity 50%

[0067] (7) Film Impact A Toyo Seiki Seisakusho film impact tester (hereafter simply referred to as the "testing machine") was used to measure the work required to break the film per unit thickness. Specifically, the test film was stored in an atmosphere of 23°C and 50% humidity, and after conditioning, the test film was fixed to the testing machine with a 50 mm diameter holder, and a 1-inch (25.4 mm) hemispherical metal was struck at the penetration point from the inner surface of the test film, measuring the work required to break the film. The load was then removed, and the maximum scale (work load) was adjusted to 1.5 J. The film impact value was determined by dividing the work load by the film thickness.

[0068] (8) DDI Measurements were performed in accordance with JIS K7124-1. The tester used was a Tester Sangyo IM-302 Dart Impact Tester. The sample film was clamped in a clamp, and a weight holder was attached to a support 66 cm above the film surface. A weight (dart) consisting of a 38 mm diameter aluminum hemisphere and a 150 mm long shaft was set to an arbitrary weight and attached to the weight holder. The weight was allowed to fall freely, and the film surface was visually inspected for rupture. Five measurements were taken for each dart. If no rupture occurred all five times, the dart was made heavier by a fixed amount and remeasured. If no rupture occurred all five times, the dart was made lighter by a fixed amount and remeasured. Measurements were completed once the weights of the darts that did not rupture all five times and the weights of the darts that ruptured all five times were determined. Finally, the 50% fracture mass (M50) and 50% fracture energy (E50) of the film sample were calculated using the following formulas [1][2]. [1] M50=WS(T / 100-1 / 2) [2] E50 = M50 × g × H W: Minimum mass at the time of destruction of all test items (g) S: Mass interval during repeated testing (g) T: Sum of the fracture rates of the five film samples for each test mass (%) H: Distance from the film sample surface to the tip of the dart (m) g: Gravitational acceleration (9.81m / s2)

[0069] <Production of polyolefin laminates as raw materials for recycled materials> The stretched polyolefin substrate was Tokyo Ink's Hibron (thickness 25 μm; longitudinally uniaxially stretched high-density polyethylene film). Resin composition A (Japan Polyethylene Co., Ltd., Harmolex (registered trademark), grade NF366A (linear low-density polyethylene)) was used as the polyolefin sealant. A 120 μm film was molded at 180°C and a blow ratio of 1.9 using an inflation molding machine. Next, a dry laminating adhesive (an ether-based urethane adhesive) was applied to the stretched polyolefin substrate in a thickness of 3 μm, and the polyolefin sealant was then bonded to the substrate layer via this adhesive layer. In this manner, a polyolefin resin laminate was produced as a raw material for the recycled material. In the polyolefin resin laminate, the ratio (mass ratio) of the content of the oriented polyolefin substrate to the content of the polyolefin sealant is 1 / 4.6. The density of resin composition A (polyethylene resin composition A) was 0.919 g / cm 3 The melt flow rate (MFR) at 190°C under a load of 2.16 kg is 1.6 g / 10 min, and the Mw / Mn is 3.19.

[0070] <Production of recycled materials> The polyolefin resin laminate was cut, melted, kneaded, and extruded from the discharge section of an extruder. Then, the cut pieces were immersed in cold water to cool them, and cut into pellets using a pelletizer. In this way, a recycled material was obtained from the polyolefin resin laminate.

[0071] [Example 1-1] Using the recycled material, a 50μm film was blown at 180℃ with a blow ratio of 2.0. The environmental load, Elmendorf tear strength, film impact, breaking strength, and DDI are shown in Table 1.

[0072] [Example 1-2] A film was formed in the same manner as in Example 1-1, except that 70% of the recycled material and 30% of Resin Composition A were dry-blended. The environmental load, Elmendorf tear strength, film impact, breaking strength, and DDI are shown in Table 1.

[0073] [Examples 1-3] A film was formed in the same manner as in Example 1-1, except that 50% of the recycled material and 50% of Resin Composition A were dry-blended. The environmental load, Elmendorf tear strength, film impact, breaking strength, and DDI are shown in Table 1.

[0074] [Examples 1-4] A film was formed in the same manner as in Example 1-1, except that 30% of the recycled material and 70% of Resin Composition A were dry-blended. The environmental load, Elmendorf tear strength, film impact, breaking strength, and DDI are shown in Table 1.

[0075] [Comparative Example 1-1] As a resin for the polyolefin resin laminate, 75% of resin composition A and 25% of resin composition B (manufactured by Japan Polyethylene Co., Ltd., product name Novatec HD, high-density polyethylene, grade name HY430) were dry-blended to prepare a virgin resin. A film was formed in the same manner as in Example 1-1, except that the above virgin resin was used. The environmental load, Elmendorf tear strength, film impact, breaking strength, and DDI are shown in Table 1.

[0076] [Comparative Example 1-2] A film was formed in the same manner as in Example 1-1, except that 70% of the virgin resin was dry-blended with 30% of Resin Composition A. The environmental load, Elmendorf tear strength, film impact, breaking strength, and DDI are shown in Table 1.

[0077] [Comparative Example 1-3] A film was formed in the same manner as in Example 1-1, except that 50% of the virgin resin was dry-blended with 50% of Resin Composition A. The environmental load, Elmendorf tear strength, film impact, breaking strength, and DDI are shown in Table 1.

[0078] [Comparative Example 1-4] A film was formed in the same manner as in Example 1-1, except that 30% of the virgin resin was dry-blended with 70% of Resin Composition A. The environmental load, Elmendorf tear strength, film impact, breaking strength, and DDI are shown in Table 1.

[0079] Table 2 also shows the ratios of Elmendorf tear strength, film impact, breaking strength, and DDI between the recycled polyolefin films of Examples 1-1 to 1-4 and the virgin polyolefin films of Comparative Examples 1-1 to 1-4 containing the same amount of virgin resin as the recycled material.

[0080] [Example] Multilayer films were molded using a five-layer inflation molding machine at 210°C and a blow ratio of 1.5 using the film configuration shown in Table 3. Table 4 shows the environmental load, Elmendorf tear strength, film impact, breaking strength, and DDI.

[0081] [Comparative Example 2-1] A multilayer film was molded under the same conditions as in Example 2-1, except that the film configuration was changed as shown in Table 3. Table 4 shows the environmental load, Elmendorf tear strength, film impact, breaking strength, and DDI.

[0082] In Example 2-1 and Comparative Example 2-1, resin composition A1 (manufactured by Japan Polyethylene Co., Ltd., HARMOLEX (registered trademark), grade NF396A), resin composition A2 (manufactured by Japan Polyethylene Co., Ltd., HARMOLEX (registered trademark), grade NF396A), resin composition A3 (manufactured by Japan Polyethylene Co., Ltd., trade name Novatec HD, high-density polyethylene, grade HY430), and resin composition A4 (manufactured by Japan Polyethylene Co., Ltd., trade name Novatec LL, linear low-density polyethylene, grade UF421) were used as raw materials.

[0083] Table 5 also shows the ratios of Elmendorf tear strength, film impact, breaking strength, and DDI for the multilayer film containing recycled polyolefin film in Example 2-1 to the multilayer film containing virgin polyolefin film with the same content of virgin resin as the recycled material in Comparison Example 2-1.

[0084] [Table 1]

[0085] [Table 2]

[0086] [Table 3]

[0087] [Table 4]

[0088] [Table 5]

[0089] [Industrial Applicability] According to the present invention, a recycled polyolefin film with reduced environmental impact and strength similar to that of virgin polyolefin films made from virgin resin can be provided. Therefore, the recycled polyolefin film of the present invention can be suitably used for laminates and packaging materials, particularly polyolefin monomaterial laminates and polyolefin monomaterial packaging materials in which all constituent layers are made of the same polyolefin resin composition.

Claims

1. A recycled polyolefin film obtained using recycled material obtained by pelletizing a polyolefin resin laminate having at least a polyolefin oriented substrate and a polyolefin sealant, characterized in that the recycled material content is 10% by mass or more (the total mass of the recycled polyolefin film is 100% by mass).

2. The recycled polyolefin film according to claim 1, characterized in that the ratio of the Elmendorf tear strength of the recycled polyolefin film to the Elmendorf tear strength of a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin in the same content as the recycled material (wherein the virgin resin has a composition corresponding to that of a polyolefin resin laminate) is 0.7 or more in the direction perpendicular to the machine direction (Elmendorf tear strength is measured in accordance with JIS K7128-2).

3. The recycled polyolefin film according to claim 1, characterized in that the ratio of the film impact of the recycled polyolefin film to the film impact of a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin in the same content as the recycled material (wherein the virgin resin has a composition corresponding to that of a polyolefin resin laminate) is 0.7 or more (the film impact is measured with reference to JIS K7128-2).

4. The recycled polyolefin film according to claim 1, characterized in that in a tensile test of a recycled polyolefin film and a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin in the same content as the recycled material (wherein the virgin resin has a composition corresponding to that of a polyolefin resin laminate), the ratio of breaking strength in the machine direction to the direction perpendicular thereto is 0.7 or more (the tensile test is measured in accordance with JIS K7127).

5. The recycled polyolefin film according to claim 1, characterized in that the ratio of the dirt drop impact test result of the recycled polyolefin film to the dirt drop impact test result of a virgin polyolefin film in which the recycled material contained in the recycled polyolefin film has been replaced with virgin resin in the same content as the recycled material (wherein the virgin resin has a composition corresponding to that of the polyolefin resin laminate) is 0.7 or more (the dirt drop impact test is measured with reference to JIS K7124).

6. The recycled polyolefin film according to claim 1, characterized in that in addition to the recycled material, it contains a polyethylene resin composition that satisfies the following requirements. 1) Density is 0.900 to 0.930 g / cm ３ 2) Melt flow rate (MFR) at 190°C under a load of 2.16 kg is 0.1 to 20 g / 10 min. 3) The molecular weight distribution (Mw / Mn), which is the ratio of the number average molecular weight (Mn) to the weight average molecular weight (Mw) determined by GPC, is 1.8 to 3.

5.

7. A resin laminate comprising at least one layer made of the recycled polyolefin film according to any one of claims 1 to 6.

8. 8. The resin laminate according to claim 7, wherein all layers constituting the resin laminate are polyolefin monomaterial resin laminates made of the same polyolefin resin composition.

9. A packaging material using the resin laminate according to claim 7.

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