Method for processing synthetic resin waste containing non-ferrous metal and use thereof

Abstract

The present invention addresses the problem of providing a method for processing synthetic resin waste, excellent in separation between non-ferrous metals and synthetic resins. The method for processing synthetic resin waste comprises an anti-adhesion step, comprising charging a mixer having a rotating body with synthetic resin waste containing a non-ferrous metal and a synthetic resin, along with an anti-readhesion agent, and rotating the rotating body.

Description

Method for treating synthetic resin waste containing non-ferrous metals and its use

[0001] The present invention relates to a method for treating synthetic resin waste containing non-ferrous metals and its use.

[0002] Composite materials made of non-ferrous metals and synthetic resins are used in many fields. For example, resin sashes (composite sashes) made of a composite of non-ferrous metals and synthetic resins are known as sashes with excellent thermal insulation properties.

[0003] In the manufacturing process of a composite material (e.g., a resin sash) made of a non-ferrous metal and a synthetic resin, the composite material may be processed (e.g., cut) into a desired shape and size. When such processing is performed, synthetic resin waste containing the non-ferrous metal and the synthetic resin may be generated as scrap material.

[0004] In the past, synthetic resin waste containing non-ferrous metals and synthetic resins was almost always discarded as is due to the difficulty of separating the two. However, in recent years, there has been an increasing demand for recycling synthetic resins from the perspective of environmental considerations, and there is a need to establish a technology for separating non-ferrous metals and synthetic resins from synthetic resin waste.

[0005] For example, Patent Documents 1, 2, 3 and 4 disclose techniques relating to the separation of non-ferrous metals and synthetic resins.

[0006] JP 2011-207151, JP 2009-172534, JP 10-156211, JP 11-099364

[0007] However, the above-mentioned conventional techniques have room for further improvement in terms of the ability to separate non-ferrous metals from synthetic resins.

[0008] One embodiment of the present invention has been made in consideration of the above-mentioned problems, and its object is to provide a method for treating synthetic resin waste containing non-ferrous metals, which has excellent separation ability between non-ferrous metals and synthetic resins.

[0009] The present inventors have conducted extensive research to solve the above problems, and as a result have completed the present invention. That is, a method for treating synthetic resin waste according to one embodiment of the present invention includes the following components.

[0010] A method for treating synthetic resin waste, comprising an adhesion prevention step of feeding synthetic resin waste containing non-ferrous metals and synthetic resins and a redeposition prevention agent into a mixer having a rotor and rotating the rotor.

[0011] According to one embodiment of the present invention, it is possible to provide a method for treating synthetic resin waste containing non-ferrous metals, which is excellent in the ability to separate non-ferrous metals from synthetic resins.

[0012] An embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the respective configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic and patent literature described in this specification is incorporated herein by reference.

[0013] In this specification, a "structural unit derived from an X monomer" contained in a polymer, copolymer, or resin may be referred to as an "X unit."

[0014] Unless otherwise specified in this specification, the structural unit is X １ Units and X ２ Units, ... and X ｎ A copolymer containing units (n is an integer of 2 or more) is referred to as "X １ / X ２ / ・・・ / X ｎ Also referred to as "copolymer". X １ / X ２ / ・・・ / X ｎ Unless otherwise specified, the copolymer is not particularly limited in polymerization mode, and may be a random copolymer, a block copolymer, an alternating copolymer, or a graft copolymer.

[0015] [1. First Embodiment] [1-1. Technical Concept of the First Embodiment of the Present Invention] In synthetic resin waste containing non-ferrous metals, the non-ferrous metals are often attached to the synthetic resin. If the synthetic resin is recycled while still containing the non-ferrous metals, the non-ferrous metals may become foreign matter, potentially resulting in problems such as poor appearance. Therefore, when recycling the synthetic resin contained in the synthetic resin waste, it is necessary to separate the non-ferrous metals from the synthetic resin. However, while iron mixed in the synthetic resin waste can be easily separated from the synthetic resin using magnetic force, non-ferrous metals often do not react to magnetic force, making it difficult to separate only the non-ferrous metals from the synthetic resin waste containing non-ferrous metals. Due to these circumstances, there is a growing demand for technology to separate the non-ferrous metals from the synthetic resin in synthetic resin waste containing non-ferrous metals.

[0016] Conventional methods for separating non-ferrous metals and synthetic resins contained in synthetic resin waste containing non-ferrous metals include a method using a sieve with a mesh, a method using an air gun, a method using heat, a method using a gravity separator, etc. However, all of these methods tend to leave non-ferrous metals in the synthetic resins even after separation, meaning that they are not sufficient in terms of the ability to separate non-ferrous metals and synthetic resins.

[0017] In light of the above-mentioned circumstances, the present inventors have investigated a method for treating synthetic resin waste that is excellent in the ability to separate non-ferrous metals and synthetic resins contained in synthetic resin waste containing non-ferrous metals. As a result, they have independently discovered a novel finding that a method for treating synthetic resin waste that includes an anti-adhesion step of feeding synthetic resin waste containing non-ferrous metals and synthetic resin and a redeposition inhibitor into a mixer having a rotor and rotating the rotor surprisingly enables good separation of non-ferrous metals and synthetic resins, leading to the completion of the present invention.

[0018] [1-2. Method for Treating Synthetic Resin Waste (First Treatment Method)] A method for treating synthetic resin waste according to one embodiment of the present invention includes an adhesion prevention step of feeding synthetic resin waste containing non-ferrous metals and synthetic resin, and a redeposition inhibitor, into a mixer having a rotor, and rotating the rotor. A treatment method having this configuration may also be referred to as the "first treatment method." The first treatment method is a method for treating synthetic resin waste according to one embodiment of the present invention. The adhesion prevention step can also be said to be rotation for stirring and mixing the synthetic resin waste and the redeposition inhibitor.

[0019] In this specification, the "method for treating synthetic resin waste" may be referred to as the "treatment method," and the "method for treating synthetic resin waste according to one embodiment of the present invention" may be referred to as the "present treatment method."

[0020] This treatment method (first treatment method) has the above-mentioned configuration, and therefore can separate non-ferrous metals and synthetic resins with good separability. In this specification, "separability" is an index of the degree of adhesion of non-ferrous metals to synthetic resins separated from non-ferrous metals in the separation process, and the less non-ferrous metals adhered, the higher the separability can be evaluated. Specific evaluation of "separability" is performed using the method described in the Examples.

[0021] Furthermore, this treatment method (first treatment method) not only has excellent sorting capabilities, but also allows for easy and inexpensive separation of non-ferrous metals and synthetic resins without the need for expensive sorting equipment (separation equipment). Furthermore, because no water is required for sorting, it is also possible to reduce the environmental impact. Because this treatment method (first treatment method) has excellent sorting capabilities, it can promote the recycling of synthetic resins, and in addition, it has the above-mentioned effects. Therefore, it can also contribute to the achievement of Sustainable Development Goals (SDGs), such as Goal 12 "Ensure sustainable consumption and production patterns."

[0022] (1-2-1. Synthetic Resin Waste) This treatment method (first treatment method) is a method for treating synthetic resin waste containing non-ferrous metals, and can also be said to be a method for providing synthetic resin that is substantially free of non-ferrous metals by using synthetic resin waste containing non-ferrous metals as a raw material. In this specification, "synthetic resin that is substantially free of non-ferrous metals" refers to "synthetic resin that, when observed visually, has no non-ferrous metals on its surface." In the first treatment method (first embodiment), "synthetic resin waste" refers to a mixture containing non-ferrous metals and synthetic resin, which is typically discarded.

[0023] In the first treatment method (first embodiment), the term "synthetic resin waste" refers to a mixture containing non-ferrous metals and synthetic resins, which would have been discarded in the past because it would be difficult to recycle. In this treatment method (first treatment method), synthetic resins that are substantially free of non-ferrous metals can be obtained using synthetic resin waste that would have been discarded in the past.

[0024] Examples of such synthetic resin waste include, but are not limited to, the following (i), (ii), and (iii): (i) mixtures of non-ferrous metals (including swarf (non-ferrous metal powder)) and synthetic resins (including synthetic resin swarf (synthetic resin powder)) generated in the manufacturing process of composite materials of non-ferrous metals and synthetic resins (for example, sashes, electric wires, wire harnesses, CCL, and components obtained by insert-molding synthetic resin and metal); (ii) used synthetic resin products with non-ferrous metal foil attached (for example, PTP (press-through package) sheets used to package tablets or capsules, food containers, packaging containers (for example, packaging containers for disposable soft contact lenses), moisture-proof packaging containers, etc.) that would have been discarded in the past; (iii) waste materials that are removed from product use and generated in the manufacturing process of composite materials of non-ferrous metals and synthetic resins or synthetic resin products with non-ferrous metal foil attached, that would have been discarded in the past.

[0025] (1-2-2. Synthetic Resins) Examples of synthetic resins contained in the synthetic resin waste include thermoplastic resins such as polyvinyl chloride resins, vinylidene chloride resins, styrene resins, and olefin resins, as well as thermosetting resins such as phenolic resins, epoxy resins, unsaturated polyesters, polyol resins, urea resins, melamine resins, guanamine resins, silicone resins, polyimide resins, polyamideimide resins, silicon resins, and diallyl phthalate resins, but are not limited to these. The synthetic resin contained in the synthetic resin waste may be a composite (e.g., a laminated sheet and a resin sash) made of two or more synthetic resins. For example, the resin sash may be a multilayer molded product of polyvinyl chloride resin and methyl methacrylate, or a multilayer molded product of polyvinyl chloride resin and acrylonitrile / acrylic rubber / styrene copolymer (ASA).

[0026] Thermoplastic Resins Representative thermoplastic resins are described in detail below.

[0027] The polyvinyl chloride resin is the same as the polyvinyl chloride resin described in detail in the section (1-2-4. Anti-redeposition agent) below, so the description therein is incorporated by reference and a detailed description thereof will be omitted here.

[0028] In this specification, the term "vinylidene chloride resin" refers to a resin having the highest content of vinylidene chloride units among all structural units constituting the resin. For example, the vinylidene chloride resin contains 50 mol % or more of vinylidene chloride units out of 100 mol % of all structural units.

[0029] Examples of vinylidene chloride resins include (a) homopolymers of vinylidene chloride and (b) copolymers of (i) vinylidene chloride and (ii) other monomers copolymerizable with vinylidene chloride. Examples of other monomers copolymerizable with vinylidene chloride include vinyl chloride, methyl acrylate, acrylic acid esters, methyl methacrylate, propylene, vinyl acetate, allyl chloride, allyl glycidyl ether, and vinyl ether.

[0030] The vinylidene chloride resin preferably contains vinylidene chloride units in an amount of 50% by weight or more, more preferably 70% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more, based on 100% by weight of the resin. The vinylidene chloride resin may contain 100% by weight of vinylidene chloride units based on 100% by weight of the resin. In other words, the vinylidene chloride resin may be a homopolymer of vinyl chloride composed only of vinylidene chloride units.

[0031] In this specification, the term "styrene-based resin" refers to a resin having the highest content of styrene units among all structural units constituting the resin. For example, the styrene-based resin contains 50 mol % or more of styrene units out of 100 mol % of all structural units.

[0032] Examples of styrene-based resins include (a) homopolymers of styrene and (b) copolymers of (i) styrene and (ii) other monomers copolymerizable with styrene, such as acrylic acid and methacrylic acid.

[0033] The styrene-based resin preferably contains 50% by weight or more of styrene units, more preferably 70% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more, based on 100% by weight of the resin. The styrene-based resin may contain 100% by weight of styrene units, based on 100% by weight of the resin. In other words, the styrene-based resin may be a vinyl chloride homopolymer composed only of styrene units.

[0034] Specific examples of styrene-based resins include polystyrene, styrene / maleic anhydride copolymers, and styrene / ethylene copolymers.

[0035] In this specification, the term "olefin-based resin" refers to a resin having the highest content of olefin units among all structural units constituting the resin. For example, the olefin-based resin contains 50 mol % or more of olefin units out of 100 mol % of all structural units.

[0036] Examples of olefin-based resins include (a) olefin homopolymers and (b) copolymers of (i) olefins and (ii) other monomers copolymerizable with olefins. Examples of olefin-based resins include polyethylene-based resins and polypropylene-based resins. Examples of polyolefin-based resins include cyclic polyolefins (sometimes referred to as cyclic olefin copolymers, COCs, or COPs).

[0037] The olefin-based resin preferably contains 50% by weight or more of olefin units, more preferably 70% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more, based on 100% by weight of the resin. The olefin-based resin may contain 100% by weight of olefin-based units, based on 100% by weight of the resin. In other words, the olefin-based resin may be an olefin homopolymer composed only of olefin-based units.

[0038] In this specification, the term "ethylene-based resin" refers to a resin having the highest content of ethylene units among all structural units constituting the resin. For example, the ethylene-based resin contains 50 mol % or more of ethylene units in 100 mol % of all structural units.

[0039] Examples of ethylene-based resins include (a) homopolymers of ethylene, and (b) copolymers of (i) ethylene and (ii) other monomers copolymerizable with ethylene.

[0040] The ethylene-based resin preferably contains 50% by weight or more of ethylene units, more preferably 70% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more, based on 100% by weight of the resin. The ethylene-based resin may contain 100% by weight of ethylene units, based on 100% by weight of the resin. In other words, the ethylene-based resin may be an ethylene homopolymer composed only of ethylene units.

[0041] Specific examples of ethylene-based resins include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, linear very low-density polyethylene, styrene-modified polyethylene-based resins, ethylene / vinyl acetate copolymers, ethylene / propylene copolymers, ethylene / 1-butene copolymers, ethylene / 1-butene / propylene copolymers, ethylene / hexene copolymers, ethylene / 4-methyl-1-pentene copolymers, ethylene / acrylic acid copolymers, and ethylene / methacrylic acid copolymers.

[0042] In this specification, the term "propylene-based resin" refers to a resin having the highest content of propylene units among all structural units constituting the resin. For example, the propylene-based resin contains 50 mol % or more of propylene units in 100 mol % of all structural units.

[0043] Examples of the propylene-based resin include (a) a homopolymer of propylene, and (b) a copolymer of (i) propylene and (ii) another monomer copolymerizable with propylene.

[0044] The propylene-based resin preferably contains 50% by weight or more of propylene units, more preferably 70% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more, based on 100% by weight of the resin. The propylene-based resin may contain 100% by weight of propylene units, based on 100% by weight of the resin. In other words, the propylene-based resin may be a propylene homopolymer composed only of propylene units.

[0045] Specific examples of the propylene-based resin include polypropylene homopolymer, ethylene / propylene random copolymer, 1-butene / propylene random copolymer, ethylene / 1-butene / propylene random copolymer, ethylene / propylene block copolymer, 1-butene / propylene block copolymer, propylene / chlorinated vinyl copolymer, propylene / maleic anhydride copolymer, etc. Further examples of the propylene-based resin include unstretched polypropylene (sometimes referred to as cast polypropylene, CPP, or CP).

[0046] Thermosetting Resins Representative thermosetting resins are described in detail below.

[0047] In this specification, the term "phenolic resin" refers to a resin obtained by reacting a phenol with an aldehyde. Phenols are not particularly limited, but examples thereof include phenol, orthocresol, meta-cresol, para-cresol, xylenol, para-tertiary butylphenol, para-octylphenol, paraphenylphenol, bisphenol A, bisphenol F, and resorcinol. Aldehydes are not particularly limited, but examples thereof include formaldehyde, acetaldehyde, butylaldehyde, acrolein, and mixtures thereof. The aldehydes may be the aforementioned substances that generate aldehydes, or solutions of these aldehydes.

[0048] In this specification, the term "epoxy resin" refers to a resin having at least one epoxy group in the molecule. Specific examples of epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol AD ​​epoxy resins, bisphenol S epoxy resins, glycidyl ester epoxy resins, glycidylamine epoxy resins, novolac epoxy resins, glycidyl ether epoxy resins of bisphenol A propylene oxide adducts, hydrogenated bisphenol A (or F) epoxy resins, fluorinated epoxy resins, rubber-modified epoxy resins containing polybutadiene or NBR, flame-retardant epoxy resins such as glycidyl ether of tetrabromobisphenol A, p-oxybenzoic acid glycidyl ether ester epoxy resins, m-aminophenol epoxy resins, diaminodiphenylmethane epoxy resins, urethane-modified epoxy resins having a urethane bond, various alicyclic epoxy resins, glycidyl ethers of polyhydric alcohols, hydantoin epoxy resins, epoxidized products of unsaturated polymers such as petroleum resins, and amino-containing glycidyl ether resins. The epoxy resin may also be a modified epoxy resin obtained by subjecting the above-mentioned epoxy resin to an addition reaction with bisphenol A (or F), polybasic acids, or the like.

[0049] In this specification, the term "unsaturated polyester" refers to a resin obtained by polymerizing a monomer having at least one ethylenically unsaturated bond in the molecule (ethylenically unsaturated monomer). Examples of ethylenically unsaturated monomers include acrylic acid, α-alkylacrylic acid, α-alkylacrylic acid esters, β-alkylacrylic acid, β-alkylacrylic acid esters, methacrylic acid, acrylic acid esters, methacrylic acid esters, vinyl acetate, vinyl esters, unsaturated esters, polyunsaturated carboxylic acids, polyunsaturated esters, maleic acid, maleic acid esters, maleic anhydride, and acetoxystyrene. The unsaturated polyester may contain only one of these monomers, or may contain two or more of these monomers.

[0050] In this specification, the term "polyol resin" refers to a resin having two or more active hydrogen atoms at its terminals. Examples of polyol resins include aliphatic alcohols, aromatic alcohols, polyether polyols, polyester polyols, polyolefin polyols, and acrylic polyols.

[0051] The synthetic resin contained in the synthetic resin waste may be one type of resin selected from the group consisting of the various synthetic resins described above, or a combination of two or more types of resins. Also, it may be a combination of a thermoplastic resin and a thermosetting resin.

[0052] (1-2-3. Non-ferrous Metals) In this specification, the term "non-ferrous metals" refers to all metals other than iron and metals containing iron as the primary component (e.g., steel) (iron content of 90% or more). Examples include aluminum, zinc, lead, tin, nickel, and magnesium. Also included in the term "non-ferrous metals" are alloys combining multiple non-ferrous metals, such as brass, and alloys combining iron and non-ferrous metals that do not contain iron as the primary component (iron content less than 90%) (e.g., stainless steel). The non-ferrous metal contained in the synthetic resin waste may be one or more of the above types. In one embodiment of this treatment method (first treatment method), the non-ferrous metal contained in the synthetic resin waste is preferably a non-ferrous metal other than aluminum. In this specification, the term "stainless steel" refers to an alloy containing 50% or more iron, 10.5% or more chromium, and a carbon content of 1.2% or less.

[0053] In one embodiment of this treatment method (first treatment method), the non-ferrous metals contained in the synthetic resin waste preferably contain aluminum, and may be composed only of aluminum.

[0054] The form of the non-ferrous metal contained in the synthetic resin waste is not particularly limited, but may be, for example, in the form of flakes. That is, in one embodiment of the present invention, the synthetic resin waste may include flake-shaped non-ferrous metals (non-ferrous metal flakes).

[0055] Non-ferrous metal pieces In this specification, the term "non-ferrous metal pieces" refers to relatively small (e.g., diameter of 5.00 mm or less) non-ferrous metal scraps generated by cutting or milling a composite material of a non-ferrous metal and a synthetic resin or a non-ferrous metal. In one embodiment, the non-ferrous metal pieces may be non-ferrous metal cuttings.

[0056] In one embodiment of this treatment method (first treatment method), the non-ferrous metals contained in the synthetic resin waste preferably include aluminum flakes as flake-shaped non-ferrous metals (non-ferrous metal flakes), and may be composed solely of aluminum flakes. In this specification, "aluminum flakes" may also be referred to as "aluminum flakes."

[0057] In a composite material of a non-ferrous metal and a synthetic resin, the non-ferrous metal may be coated with another component (e.g., a resin), etc. Therefore, a part or all of the non-ferrous metal piece may be coated with another component (e.g., a resin).

[0058] In this specification, the "diameter of a non-ferrous metal piece" refers to the diameter of the smallest sphere among those spheres that contain the entire non-ferrous metal piece inside and that contact the non-ferrous metal piece at at least two points. The diameter of the non-ferrous metal piece is not particularly limited, but is preferably 0.63 mm or more, more preferably 0.80 mm or more, even more preferably 0.90 mm or more, and particularly preferably 1.10 mm or more. The upper limit of the diameter of the non-ferrous metal is preferably 5.00 mm or less or 3.00 mm or less. If the diameter of the non-ferrous metal piece is within the above range, the non-ferrous metal piece and the synthetic resin can be well separated in the first separation step described below.

[0059] The shape of the non-ferrous metal pieces is not particularly limited, and may be, for example, particulate, powder, triangular or rectangular flakes, or foil.

[0060] In this specification, among non-ferrous metal pieces, foil-shaped non-ferrous metal pieces having a thickness of 6 μm to 200 μm may be referred to as "non-ferrous metal foil." In other words, the non-ferrous metal pieces related to this processing method (first processing method) may include non-ferrous metal foil. In this specification, the term "foil" also includes sheet, film, and membrane. That is, "non-ferrous metal foil" includes not only non-ferrous metal foil having a thickness of 6 μm to 200 μm, but also non-ferrous metal sheets, non-ferrous metal films, and non-ferrous metal membranes.

[0061] An example of synthetic resin waste containing non-ferrous metal foil is a PTP sheet. The non-ferrous metal foil to be treated by this treatment method (first treatment method) is, for example, a non-ferrous metal foil derived from such a PTP sheet.

[0062] In this specification, "non-ferrous metal foil" includes non-ferrous metal foil adhered to a synthetic resin. "Non-ferrous metal foil adhered to a synthetic resin" includes not only non-ferrous metal foil directly adhered to a synthetic resin, but also non-ferrous metal foil indirectly adhered to a synthetic resin. For example, in the case of packaging containers containing non-ferrous metal foil, such as PTP sheets and disposable soft contact lenses, the non-ferrous metal foil may form a laminate with an adhesive layer composed of a sealing agent (adhesive), and the laminate may adhere to the synthetic resin via the adhesive layer (sealing agent), thereby adhering the non-ferrous metal foil to the synthetic resin. Such non-ferrous metal foil adhered to a synthetic resin via an adhesive layer (sealing agent) is also included in "non-ferrous metal foil adhered to a synthetic resin."

[0063] In one embodiment of this treatment method (first treatment method), the non-ferrous metal contained in the synthetic resin waste preferably includes aluminum foil as a non-ferrous metal foil, or may be composed solely of aluminum foil. In this specification, "aluminum foil" may also be referred to as "aluminum foil."

[0064] The thickness of the non-ferrous metal pieces is not particularly limited, and depends on (i) the thickness of the synthetic resin product containing non-ferrous metal before cutting (slicing), and (ii) the rotation speed and cutting speed of the blade used to cut (slice) the synthetic resin product containing non-ferrous metal. The thickness of the non-ferrous metal pieces is, for example, preferably 0.05 mm or more and 1.00 mm or less, more preferably 0.10 mm or more and 0.95 mm or less, and even more preferably 0.15 mm or more and 0.90 mm or less. If the thickness of the non-ferrous metal pieces is within the above range, the non-ferrous metal pieces and the synthetic resin can be well separated in the first separation step described below.

[0065] The width of the non-ferrous metal pieces is not particularly limited, and depends on the width of the saw blade used to cut (slice) the synthetic resin product containing the non-ferrous metal. The width of the non-ferrous metal pieces is, for example, preferably 0.50 mm to 2.00 mm, more preferably 0.55 mm to 1.95 mm, and even more preferably 0.60 mm to 1.90 mm. If the width of the non-ferrous metal pieces is within the above range, the non-ferrous metal pieces and the synthetic resin can be well separated in the first separation step described below.

[0066] The length of the non-ferrous metal pieces is not particularly limited, but is preferably 0.50 mm to 5.00 mm, more preferably 0.55 mm to 4.95 mm, and even more preferably 0.60 mm to 4.90 mm. If the length of the non-ferrous metal pieces is within the above range, non-ferrous metals and synthetic resins can be well separated in the first separation step described below.

[0067] (1-2-4. Anti-redeposition agent) In this treatment method (first treatment method), an anti-redeposition agent is used. In the first treatment method (first embodiment), the term "anti-redeposition agent" refers to a substance that can prevent adhesion (redeposition) between non-ferrous metal pieces and synthetic resin. In this specification, "prevent" refers to both "completely eliminate" and "reduce."

[0068] As mentioned above, in synthetic resin waste containing non-ferrous metals, the non-ferrous metals are often attached to the synthetic resin due to, for example, static electricity or an adhesive layer. When only synthetic resin waste is introduced into a mixer having a rotor and the rotor is rotated, the following (phenomenon a) and (phenomenon b) may be repeated: (phenomenon a) A phenomenon in which non-ferrous metals that have been attached to the synthetic resin due to the action of static electricity or an adhesive layer are separated from the synthetic resin; (phenomenon b) A phenomenon in which non-ferrous metals that have been separated from the synthetic resin are again attached to the synthetic resin due to the action of static electricity or an adhesive layer. Alternatively, when only synthetic resin waste is introduced into a mixer having a rotor and the rotor is rotated, the following (phenomenon c) occurs, and then the above (phenomenon a) and (phenomenon b) may be repeated: (phenomenon c) A phenomenon in which non-ferrous metals that were not attached to the synthetic resin before introduction are attached to the synthetic resin due to the action of static electricity or an adhesive layer. Here, as in this treatment method (first treatment method), when synthetic resin waste and a redeposition prevention agent are put into a mixer having a rotor and the rotor is rotated (i.e., when the adhesion prevention step described below is carried out), (i) non-ferrous metals that were not attached to the synthetic resin before the introduction can be prevented from adhering to the synthetic resin due to static electricity or an adhesive layer, and (ii) non-ferrous metals that have separated from the synthetic resin after the rotor has rotated can be prevented from adhering to the synthetic resin due to static electricity or an adhesive layer, etc.

[0069] In this specification, with regard to adhesion and redeposition between synthetic resin and non-ferrous metal, the terms "adhesion" and "redeposition" are synonymous and can be substituted for each other. In this specification, the term "redeposition inhibitor" can also be referred to as "anti-adhesion agent" and is synonymous with "anti-adhesion agent." In this specification, the "adhesion prevention step" described below can also be referred to as "redeposition prevention step" and is synonymous with "redeposition prevention step."

[0070] Examples of anti-redeposition agents include organic substances (polyvinyl chloride resins, copolymers containing α-methylstyrene units, acrylic polymers, styrene / acrylonitrile copolymers, acrylonitrile / butadiene / styrene copolymers, wheat flour, potato starch, starch, etc.) and inorganic substances (inorganic fillers, metal soaps, wax, etc.). These anti-redeposition agents may be used alone or in combination of two or more. Polyvinyl chloride resins are sometimes abbreviated as "PVC." "Copolymers containing α-methylstyrene units" are sometimes referred to as "α-MS-based polymers." Styrene / acrylonitrile copolymers are sometimes abbreviated as "SAN," "SAN (based) resin," or "AS (based) resin." Acrylonitrile / butadiene / styrene copolymers are sometimes abbreviated as "ABS" or "ABS (based) resin."

[0071] The anti-redeposition agent preferably contains one or more selected from the group consisting of polyvinyl chloride resins, copolymers containing α-methylstyrene units, acrylic polymers, styrene / acrylonitrile copolymers, acrylonitrile / butadiene / styrene copolymers, inorganic fillers, metal soaps, waxes, and the like, and may be composed of only one or more selected from this group.

[0072] In this specification, the term "polyvinyl chloride resin" refers to a resin containing 50% by weight or more of structural units derived from a vinyl chloride monomer (preferably vinyl chloride) per 100% by weight of the resin. The content of structural units derived from a vinyl chloride monomer (preferably vinyl chloride) contained in the polyvinyl chloride resin is not particularly limited as long as it is 50% by weight or more, but is preferably 60% by weight or more, more preferably 70% by weight or more, even more preferably 80% by weight or more, and particularly preferably 90% by weight or more. In other words, as long as the polyvinyl chloride resin contains the structural units derived from the vinyl chloride monomer in the above-mentioned amount, the other structural units are not particularly limited. The polyvinyl chloride resin may be a homopolymer of vinyl chloride composed only of structural units derived from a vinyl chloride monomer.

[0073] Specific examples of polyvinyl chloride resins include (a) homopolymers of vinyl chloride and (b) copolymers of (i) vinyl chloride and (ii) other monomers copolymerizable with vinyl chloride. Examples of other monomers copolymerizable with vinyl chloride include ethylene, propylene, vinyl acetate, allyl chloride, allyl glycidyl ether, acrylic esters, vinyl ethers, etc. Polyvinyl chloride resins also include chlorinated polyvinyl chloride resins obtained by further chlorinating the above-mentioned various polyvinyl chloride resins by known methods.

[0074] Chlorinated polyvinyl chloride resins are usually produced using the various polyvinyl chloride resins described above as raw materials by the following methods (a) and (b): (a) a method of chlorination in an aqueous medium, in which a polyvinyl chloride resin is dispersed in an aqueous medium and chlorine is supplied to the aqueous medium, and the resulting mixture is (i) irradiated with a mercury lamp to perform photochlorination, or (ii) chlorinated by heating the resulting mixture; and (b) a method of chlorination in a gas phase, in which the polyvinyl chloride resin is chlorinated in a gas phase under irradiation with a mercury lamp.

[0075] The chlorine content of the chlorinated polyvinyl chloride resin is preferably 60% by weight or more and 75% by weight or less, and more preferably 64% by weight or more and 70% by weight or less. The chlorine content of the chlorinated polyvinyl chloride resin and the polyvinyl chloride resin is a value measured in accordance with JIS K7385 Method B.

[0076] In this specification, the term "α-MS polymer" refers to a (co)polymer containing structural units (α-methylstyrene units) derived from α-methylstyrene. The content of α-methylstyrene units in the α-MS polymer is not particularly limited, but is preferably 20% by weight or more and 85% by weight or less, more preferably 25% by weight or more and 80% by weight or less, even more preferably 30% by weight or more and 80% by weight or less, and particularly preferably 35% by weight or more and 75% by weight or less, based on 100% by weight of the α-MS polymer. When the α-MS polymer contains 20% by weight or more of α-methylstyrene units based on 100% by weight of the α-MS polymer, the α-MS polymer has good compatibility (easy compatibility) with polyvinyl chloride resins, which is advantageous in that it is easy to exhibit an anti-redeposition effect. Furthermore, when the α-MS polymer contains 20% by weight or more of α-methylstyrene units relative to 100% by weight of the α-MS polymer, the heat resistance is increased, and there is no risk of the polymer melting when heated or melting due to shear heat during mixing. Therefore, the anti-redeposition agent is more likely to remain in a powder state, which is advantageous in that it is more likely to exhibit its anti-redeposition effect.

[0077] The α-MS polymer may contain, as a structural unit other than the α-methylstyrene unit, a structural unit derived from a monomer other than α-methylstyrene that is copolymerizable with α-methylstyrene. Examples of the monomer other than α-methylstyrene that is copolymerizable with α-methylstyrene include aromatic vinyl monomers other than α-methylstyrene, conjugated diene monomers, unsaturated nitrile monomers, and (meth)acrylic monomers.

[0078] The weight-average molecular weight of the α-MS polymer is not particularly limited, but from the viewpoint of reusing the used α-MS polymer as a polyvinyl chloride resin, it is preferably from 50,000 to 1,000,000, more preferably from 50,000 to 800,000, and even more preferably from 65,000 to 130,000. The α-MS polymer has high compatibility with polyvinyl chloride resins and can also be used as a heat resistance improver for polyvinyl chloride resins. When the weight-average molecular weight of the α-MS polymer used as a redeposition inhibitor is within the above-mentioned range, it is preferable from the viewpoint of reusing the used α-MS polymer as a heat resistance improver for polyvinyl chloride resins.

[0079] The inorganic filler serving as a redeposition inhibitor is not particularly limited, but examples thereof include calcium carbonate, talc, mica, clay, silica, titanium oxide, hydrotalcite, and magnesium hydroxide.

[0080] The calcium carbonate as a redeposition inhibitor is not particularly limited, but examples thereof include colloidal calcium carbonate, light calcium carbonate, heavy calcium carbonate, etc. Furthermore, the calcium carbonate may be surface-treated (e.g., hydrophobized) or may not be surface-treated (surface-untreated).

[0081] The metal soap that serves as the anti-redeposition agent is not particularly limited, but examples thereof include calcium stearate.

[0082] The wax used as the anti-redeposition agent is not particularly limited, but examples thereof include ethylene bisamide, polyethylene wax, and paraffin wax.

[0083] From the viewpoint of excellent anti-redeposition effect, the anti-redeposition agent is preferably a substance that adheres more easily to non-ferrous metals than synthetic resin (for example, a substance that is more easily charged than the synthetic resin contained in synthetic resin waste, or a substance that can remove static electricity from synthetic resin).Furthermore, from the viewpoint of ease of recycling the synthetic resin, the anti-redeposition agent is preferably a resin that may be mixed into the synthetic resin (for example, a resin that has little effect on the physical properties of the synthetic resin).

[0084] From the above-mentioned viewpoints, when the synthetic resin contained in the synthetic resin waste to be treated is a polyvinyl chloride resin, the anti-redeposition agent preferably contains (i) one or more selected from the group consisting of polyvinyl chloride resin, α-MS polymer, acrylic polymer, styrene / acrylonitrile copolymer, inorganic filler, metal soap, and wax, and more preferably consists of only one or more selected from this group; and (ii) more preferably contains one or more selected from the group consisting of polyvinyl chloride resin, α-MS polymer, acrylic polymer, styrene / acrylonitrile copolymer, calcium carbonate, talc, calcium stearate, ethylene bisamide, polyethylene wax, and paraffin wax, and more preferably consists of only one or more selected from this group.

[0085] From the above-mentioned viewpoints, when the synthetic resin contained in the synthetic resin waste to be treated is a styrene-based resin, the anti-redeposition agent preferably contains (i) one or more selected from the group consisting of an α-MS-based polymer, an acrylic-based polymer, a styrene / acrylonitrile copolymer, and an inorganic filler, and more preferably consists of only one or more selected from this group, and more preferably contains (ii) one or more selected from the group consisting of an α-MS-based polymer, an acrylic-based polymer, a styrene / acrylonitrile copolymer, calcium carbonate, and talc, and more preferably consists of only one or more selected from this group.

[0086] From the above-mentioned viewpoint, when the synthetic resin contained in the synthetic resin waste to be treated is an olefin-based resin, the anti-redeposition agent preferably contains (i) one or more types selected from the group consisting of inorganic fillers, and more preferably consists of only one or more types selected from said group, and more preferably contains (ii) one or more types selected from the group consisting of calcium carbonate and talc, and more preferably consists of only one or more types selected from said group.

[0087] When the anti-redeposition agent is a polymer, copolymer, or resin (e.g., polyvinyl chloride resin, α-MS polymer, acrylic polymer, styrene / acrylonitrile copolymer, acrylonitrile / butadiene / styrene copolymer, etc.), the anti-redeposition agent is preferably in powder form. In other words, when the anti-redeposition agent is a polymer, copolymer, or resin, the anti-redeposition agent is preferably in powder form. This configuration has the advantage that it can easily coat the synthetic resin surface, thereby further enhancing the anti-redeposition effect. Inorganic fillers such as calcium carbonate and talc also easily coat the synthetic resin surface. Therefore, even when the anti-redeposition agent is an inorganic filler such as calcium carbonate or talc, it has the advantage that it can further enhance the anti-redeposition effect for the reasons described above. Metal soaps such as calcium stearate also easily coat the synthetic resin surface. Therefore, even when the anti-redeposition agent is a metal soap such as calcium stearate, it has the advantage that it can further enhance the anti-redeposition effect for the reasons described above. Waxes such as ethylene bisamide, PEWAX, and paraffin wax also easily coat synthetic resin surfaces, so even when the anti-redeposition agent is a wax such as ethylene bisamide, PEWAX, or paraffin wax, there is the advantage that the anti-redeposition effect is further enhanced for the reasons described above.

[0088] The volume average particle diameter of the anti-redeposition agent is not particularly limited, but is preferably 1 μm or more and 1000 μm or less, more preferably 20 μm or more and 800 μm or less, even more preferably 30 μm or more and 500 μm or less, even more preferably 80 μm or more and 300 μm or less, and particularly preferably 50 μm or more and 200 μm or less. When the volume average particle diameter of the anti-redeposition agent is within the above range, the anti-redeposition agent easily adheres to non-ferrous metals, thereby effectively preventing the adhesion (redeposition) of non-ferrous metals to synthetic resins. Furthermore, when the volume average particle diameter of the anti-redeposition agent is 1 μm or more, there is also the advantage that the anti-redeposition agent does not become airborne during, for example, the first fractionation step and the second fractionation step, thereby improving workability. When the anti-redeposition agent is a polymer, copolymer, or resin, the term "volume average particle diameter of the anti-redeposition agent" refers to the volume average particle diameter of the polymer, copolymer, or resin powder. The method for measuring the volume average particle size of the anti-redeposition agent will be described in detail in the Examples below.

[0089] (1-2-5. Other Additives) In this treatment method (first treatment method), additives other than the anti-redeposition agent (other additives) may be used. Examples of such other additives include external lubricants (e.g., special fatty acid esters), internal lubricants (e.g., fatty acid esters), and fatty acids (e.g., stearic acid). In this treatment method (first treatment method), only one of the above other additives may be used, or two or more may be used in combination.

[0090] (1-2-6. Adhesion prevention step) This treatment method (first treatment method) includes an adhesion prevention step. In this adhesion prevention step, synthetic resin waste containing non-ferrous metals and synthetic resins and a redeposition prevention agent are placed in a mixer having a rotor, and the rotor is rotated. By including the adhesion prevention step in this treatment method (first treatment method), the non-ferrous metals and the redeposition prevention agent can be sufficiently mixed, and the non-ferrous metals can be separated from the synthetic resins with good separability.

[0091] (Mixer) The mixer used in this treatment method (first treatment method) is not particularly limited as long as it has a rotating body. Examples of the mixer include (a) mixers such as a Super Mixer, Nauta Mixer, Universal Mixer, Proshare Mixer, Apex Mixer, Henschel Mixer, and Loedige Mixer; and (b) blenders such as a ribbon blender and a tumbler blender.

[0092] In the adhesion prevention step, the synthetic resin waste to be treated may be charged all at once, or may be charged in several batches, or may be charged in fixed amounts continuously. For example, after a portion of the synthetic resin waste and the redeposition inhibitor are charged into a mixer, the remaining synthetic resin waste may be charged into the mixer again.

[0093] The amount of the anti-redeposition agent used in the adhesion prevention step is not particularly limited, but is preferably from 1 to 50 parts by weight, more preferably from 3 to 40 parts by weight, even more preferably from 5 to 30 parts by weight, and particularly preferably from 15 to 25 parts by weight, relative to 100 parts by weight of the synthetic resin waste. By setting the amount of the anti-redeposition agent within the above range, it is possible to further prevent redeposition of the non-ferrous metal and the synthetic resin.

[0094] The anti-redeposition agent may be (a) added to the mixer before the synthetic resin waste is added to the mixer (Case 1), (b) added to the mixer simultaneously with the synthetic resin waste when the synthetic resin waste is added to the mixer (Case 2), or (c) added to the mixer after the synthetic resin waste has been added to the mixer (Case 3). From the viewpoint of improving treatment efficiency, it is preferable to add the anti-redeposition agent to the mixer simultaneously with the synthetic resin waste at the timing of (b). Furthermore, the anti-redeposition agent may be added to the mixer in its entirety at once, in multiple installments, or continuously in fixed amounts. For example, (i) in case 1, a portion of the anti-redeposition agent to be used may be charged into a mixer, then the synthetic resin waste may be charged into the mixer, and then the remaining anti-redeposition agent may be charged into the mixer; (ii) in case 2, the synthetic resin waste and a portion of the anti-redeposition agent may be charged into the mixer, and then the remaining anti-redeposition agent may be charged into the mixer; and (iii) in case 3, the synthetic resin waste may be charged into a mixer, then a portion of the anti-redeposition agent may be charged into the mixer, and then the remaining anti-redeposition agent may be charged into the mixer.

[0095] The temperature in the adhesion prevention step is not particularly limited, and may be 0°C or higher and 120°C or lower, 10°C or higher and 110°C or lower, 15°C or higher and 105°C or lower, 20°C or higher and 100°C or lower, or 25°C or higher and 90°C or lower. The "temperature in the adhesion prevention step" refers to the temperature inside the mixer and / or the temperatures of the non-ferrous metal, synthetic resin, and anti-redeposition agent. During the adhesion prevention step, it is preferable that at least a portion of the period during which the rotor of the mixer is rotating (rotation time) be performed within the above-mentioned temperature range, and it is even more preferable that the entire period be performed within the above-mentioned temperature range.

[0096] The time for which the rotor of the mixer is rotated in the adhesion prevention step (rotation time) is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less in the above case 1, preferably 10 minutes or more and 15 minutes or less in the above case 2, and preferably 10 minutes or more and 15 minutes or less in the above case 3. The rotation time in this treatment method (first treatment method) refers to the time from the time when mixing of the synthetic resin waste and the anti-redeposition agent by rotation of the rotor begins to the time when mixing of the synthetic resin waste and the anti-redeposition agent by rotation of the rotor is completed.

[0097] The rotation speed of the mixer rotor in the adhesion prevention step is not particularly limited and may be adjusted appropriately taking into consideration (a) the mixing capacity of the mixer; and (b) the type and amount of synthetic resin waste. The rotation speed of the mixer rotor in the adhesion prevention step is, for example, preferably 100 rpm or more and 3000 rpm or less, more preferably 150 rpm or more and 2500 rpm or less, and even more preferably 500 rpm or more and 2000 rpm or less. In the adhesion prevention step, it is preferable that the rotation speed of the rotor is within the above-mentioned range for at least a portion of the rotation time, and it is particularly preferable that the rotation speed of the rotor is within the above-mentioned range for the entire time.

[0098] As described above, this treatment method (first treatment method) does not require water. More specifically, in one embodiment of the present invention, water is not used in the adhesion prevention step. This configuration has the advantage of reducing the environmental load.

[0099] (1-2-7. Thermal Separation Step) In one embodiment of the present invention, in the synthetic resin waste to be treated, non-ferrous metals and synthetic resins may be adhered (bonded) to each other via an adhesive layer made of, for example, a sealant (adhesive). In such cases, the present treatment method (first treatment method) preferably includes a thermal separation step of separating the adhered non-ferrous metals and synthetic resins by heating.

[0100] In this treatment method (first treatment method), the thermal separation step can be carried out before or simultaneously with the adhesion prevention step, and is preferably carried out before the adhesion prevention step.

[0101] In the thermal separation step, the method for separating the adhered non-ferrous metals and synthetic resins by heating is not particularly limited, but a preferred method is to put the materials into a mixer having a rotor and rotate the rotor at a specific heating temperature. Note that the mixer having a rotor can be suitably made of the same equipment as the mixer described in Section 1-2-6. Adhesion prevention step.

[0102] The heating temperature in the thermal separation step is preferably 65° C. or higher and 130° C. or lower, more preferably 75° C. or higher and 120° C. or lower, even more preferably 80° C. or higher and 115° C. or lower, even more preferably 85° C. or higher and 105° C. or lower, and particularly preferably 90° C. or higher and 100° C. By setting the heating temperature in the thermal separation step within the above range, the adhesion between the non-ferrous metal and the synthetic resin via the adhesive layer can be loosened, and as a result, it becomes possible to separate the non-ferrous metal and the synthetic resin that are adhered together.

[0103] In the thermal separation step, it is sufficient to adjust either the temperature inside the mixer or the temperature of the synthetic resin waste to be treated to the above heating temperature. Alternatively, it is also possible to adjust both the temperature inside the mixer and the temperature of the synthetic resin waste to be treated to the above heating temperature. In the thermal separation step, it is sufficient that the temperature is at the above heating temperature for at least a portion of the time that the rotor of the mixer is rotating; it is not necessary that the temperature be at the above heating temperature for the entire rotation time. However, since this further improves the separation of the adhered non-ferrous metals and synthetic resins, it is particularly preferable that the temperature be at the above heating temperature for the entire time that the rotor is rotating.

[0104] In the thermal separation step, the method for adjusting the temperature inside the mixer is not particularly limited, but examples thereof include a method of blowing hot air into the mixer and a method of directly heating the mixer body with steam and / or a heater or the like.

[0105] In addition, the method for adjusting the temperature of the synthetic resin waste itself in the thermal separation process is not particularly limited, but examples include a method in which the temperature of the synthetic resin waste itself is increased by causing the synthetic resin waste to self-heat due to shear caused by the rotation of the rotor of the mixer, a method in which the temperature of the synthetic resin waste itself is increased by blowing hot air into the mixer, and a method in which the temperature of the synthetic resin waste itself is increased by directly heating the mixer body with steam and / or a heater, etc.

[0106] (1-2-8. First Separation Step) It is preferable that the present treatment method (first treatment method) further includes a first separation step after the adhesion prevention step. The first separation step that the present treatment method (first treatment method) may have is a step of separating the mixture of the synthetic resin, the non-ferrous metal, and the anti-redeposition agent obtained in the adhesion prevention step into the synthetic resin and a mixture of the non-ferrous metal and the anti-redeposition agent. By including the first separation step in the present treatment method (first treatment method), it is possible to obtain a synthetic resin that is free of non-ferrous metals or has only a very small amount of non-ferrous metals attached. The synthetic resin obtained in the first separation step can also be recycled.

[0107] In the first fractionation step, the method for separating the mixture of synthetic resin, non-ferrous metal, and anti-redeposition agent into the synthetic resin and the mixture of non-ferrous metal and anti-redeposition agent is not particularly limited. Examples of such a method include a method using a separator.

[0108] (Sorter) The sorter is not particularly limited, but examples thereof include a sieve equipped with a plastic or metal mesh, a sieving device that applies vibration to a sieve, and a vibrating sieve machine equipped with a sieve having a plurality of mesh sizes arranged in succession.

[0109] Generally, the synthetic resin is larger than the non-ferrous metal and the anti-redeposition agent. Therefore, by placing a mixture of the synthetic resin, the non-ferrous metal, and the anti-redeposition agent on a sieve with meshes smaller than the synthetic resin and larger than the non-ferrous metal and the anti-redeposition agent, and sieving the sieve, the mixture can be separated into the synthetic resin on the sieve and the mixture of the non-ferrous metal and the anti-redeposition agent that has passed through the sieve.

[0110] The size of the mesh of the sieve is not particularly limited and may be adjusted taking into consideration the diameter of the non-ferrous metal and the volume average particle size of the anti-redeposition agent, etc. From the viewpoint of the separability of the synthetic resin from the mixture of the non-ferrous metal and the anti-redeposition agent, the size of the mesh of the sieve is preferably 0.3 mm or more and 3.0 mm or less, more preferably 0.5 mm or more and 2.0 mm or less, and even more preferably 0.8 mm or more and 1.7 mm or less.

[0111] When the present treatment method (first treatment method) includes the first fractionation step, the first fractionation step needs to be carried out at least once, but may be carried out multiple times.

[0112] (1-2-9. Second Separation Step) When the first separation step is carried out in the present treatment method (first treatment method), it is preferable that the present treatment method (first treatment method) further includes a second separation step after the first separation step. The second separation step that the present treatment method (first treatment method) may have is a step of separating the mixture of the non-ferrous metal and the anti-redeposition agent obtained in the first separation step into the non-ferrous metal and the anti-redeposition agent. Including the second separation step in the present treatment method (first treatment method) has the advantage that the separated anti-redeposition agent can be recycled.

[0113] In the second fractionation step, the method for separating the mixture of non-ferrous metals and the anti-redeposition agent into the non-ferrous metals and the anti-redeposition agent is not particularly limited. Examples of such a method include a method using a separator.

[0114] Specific examples of the separator used in the second separation step are the same as those described in the (Separator) section of the above section (1-2-8. First Separation Step), so the description is incorporated herein and the description is omitted here.

[0115] When a sieve is used as the separator in the second separation step, the size of the mesh provided in the sieve is not particularly limited and may be adjusted in consideration of the diameter of the non-ferrous metals and the volume average particle size of the anti-redeposition agent, etc. In the second separation step, from the viewpoint of the separability between the non-ferrous metals and the anti-redeposition agent, the size of the mesh provided in the sieve is preferably 0.3 mm or more and 3.0 mm or less, more preferably 0.5 mm or more and 2.0 mm or less, and even more preferably 0.8 mm or more and 1.7 mm or less.

[0116] The anti-redeposition agent separated in the second separation step of a certain treatment method (first treatment method) can be reused as an anti-redeposition agent in the anti-redeposition step of another treatment method (first treatment method). Therefore, the anti-redeposition agent separated in the second separation step is sometimes referred to as a "recycled anti-redeposition agent."

[0117] In the anti-redeposition step, the anti-redeposition agent may be a virgin one or a recycled anti-redeposition agent, but from the viewpoint of environmental considerations, a recycled anti-redeposition agent is preferred.

[0118] In the second separation step, the amount of non-ferrous metals contained in the recycled anti-redeposition agent is preferably 2.0% by weight or less, more preferably 1.5% by weight or less, even more preferably 1.0% by weight or less, particularly preferably 0.5% by weight or less, and most preferably 0.0% by weight, based on 100% by weight of the recycled anti-redeposition agent. In other words, it is most preferable that the recycled anti-redeposition agent is an anti-redeposition agent that does not contain non-ferrous metals.

[0119] When the present treatment method (first treatment method) includes the second fractionation step, the second fractionation step needs to be carried out at least once, but may be carried out multiple times.

[0120] [2. Second embodiment] [2-1. Technical concept of the second embodiment of the present invention] Composite materials of aluminum and synthetic resin are used in many fields. For example, resin sashes (composite sashes) made by combining aluminum and synthetic resin are known as sashes with excellent thermal insulation properties. In the manufacturing process of a composite material of aluminum and synthetic resin (e.g., a resin sash), the composite material may be cut to a desired shape and size. During this process, aluminum powder may be generated along with the synthetic resin scraps, and synthetic resin waste containing the synthetic resin and aluminum powder may be generated.

[0121] In synthetic resin waste containing synthetic resin and aluminum powder, the aluminum powder often adheres to the synthetic resin, making it difficult to separate the synthetic resin from the aluminum.

[0122] Synthetic resin waste containing synthetic resin and aluminum powder is sometimes discarded as is due to the difficulty of separating the synthetic resin from the aluminum. However, from the viewpoint of environmental considerations in recent years, there is a demand for the establishment of a technology for separating and recycling the synthetic resin from the synthetic resin waste.

[0123] For example, Patent Document 1 discloses a method for separating aluminum foil and resin.

[0124] Patent Document 2 discloses a method and device for cleaning aluminum chips.

[0125] Patent Document 3 discloses a method for treating scrap aluminum products.

[0126] Patent Document 4 discloses a method and device for recovering aluminum cutting chips.

[0127] However, the above-mentioned conventional techniques have room for further improvement in terms of the ability to separate aluminum pieces from synthetic resins.

[0128] The second embodiment of the present invention has been made in consideration of the above-mentioned problems, and its object is to provide a method for treating synthetic resin waste that is excellent in separating aluminum pieces from synthetic resins.

[0129] The present inventors have conducted extensive research to solve the above-mentioned problems. Specifically, the inventors have investigated methods for treating synthetic resin waste from the perspective of the ease of separating aluminum flakes (aluminum powder) from synthetic resins. During their research, they have discovered the following: (i) when using a sieve with a mesh to separate the waste, the mesh becomes clogged in a short period of time, limiting its use; (ii) when removing the resin with an air gun, the number of steps required is large and the resin is not effectively removed; and (iii) when using a gravity separator to separate the waste, the large capital investment required and the use of water, etc. make this method unrealistic from the standpoints of cost and environmental friendliness.

[0130] Therefore, the present inventors conducted further intensive research to solve the above-mentioned problems, and as a result, the present inventors independently discovered the following novel finding, which led to the completion of a second embodiment of the present invention: a method for treating synthetic resin waste that includes an anti-adhesion step of feeding synthetic resin waste containing aluminum pieces and synthetic resin, and a redeposition inhibitor, into a mixer having a rotor, and rotating the rotor, surprisingly leads to the novel finding that the aluminum pieces and synthetic resin can be easily separated.

[0131] [2-2. Method for Treating Synthetic Resin Waste (Second Treatment Method)] A method for treating synthetic resin waste according to one embodiment of the present invention includes an adhesion prevention step of feeding synthetic resin waste containing aluminum pieces and synthetic resin, and a redeposition prevention agent into a mixer having a rotor, and rotating the rotor. A treatment method having this configuration may also be referred to as a "second treatment method." The second treatment method is also a method for treating synthetic resin waste according to one embodiment of the present invention. The adhesion prevention step can also be said to be rotation for stirring and mixing the synthetic resin waste and the redeposition prevention agent.

[0132] Because of the above-described configuration, this treatment method (second treatment method) has the advantage of excellent separation capabilities between aluminum flakes and synthetic resins. More specifically, because this treatment method (second treatment method) has the above-described configuration, aluminum flakes and synthetic resins can be separated easily and inexpensively without the need for expensive separation equipment (separation equipment). Furthermore, because water is not required for separation, it is also possible to reduce environmental impact. Furthermore, because this treatment method (second treatment method) has excellent separation capabilities between aluminum flakes and synthetic resins, it has the advantage of being able to provide synthetic resins that are, at least visually, free of aluminum flakes or have only minimal aluminum flakes attached. This can promote the recycling of synthetic resins. Therefore, it can also contribute to the achievement of Sustainable Development Goals (SDGs), such as Goal 12, "Ensure sustainable consumption and production patterns."

[0133] The second embodiment is included in the first embodiment. As described above, in one embodiment of the first treatment method (first embodiment), the non-ferrous metals contained in the synthetic resin waste preferably include aluminum. In one embodiment of the first treatment method (first embodiment), the non-ferrous metals contained in the synthetic resin waste preferably include aluminum flakes (aluminum flakes) as flake-shaped non-ferrous metals (non-ferrous metal flakes). In other words, the second embodiment is an aspect in which the non-ferrous metal in the first embodiment includes aluminum (more specifically, aluminum flakes (aluminum flakes)), and can also be said to be a preferred aspect of the first embodiment.

[0134] Each aspect of the second embodiment will be described below, but the description in Section [1. First Embodiment] will be used as appropriate for matters other than those described in detail below. When using the description in Section [1. First Embodiment] for matters other than those described in detail below for the second embodiment, the term "non-ferrous metal" may be replaced with the term "aluminum piece."

[0135] (2-2-1. Synthetic Resin Waste) This treatment method (second treatment method) uses synthetic resin waste. This treatment method (second treatment method) is a method for treating synthetic resin waste containing aluminum flakes. It can also be said that this treatment method (second treatment method) is a method for using synthetic resin waste containing aluminum flakes as a raw material to provide a synthetic resin that is substantially free of aluminum flakes. In this specification, "synthetic resin that is substantially free of aluminum flakes" refers to "synthetic resin that, when observed visually, has no aluminum flakes on its surface." In the second treatment method (second embodiment), "synthetic resin waste" refers to a mixture containing aluminum flakes and synthetic resin that is typically discarded. In the second treatment method (second embodiment), "synthetic resin waste" can also be said to refer to a mixture containing aluminum flakes and synthetic resin that would conventionally be discarded due to the difficulty of recycling. This treatment method (second treatment method) makes it possible to obtain a synthetic resin that is substantially free of aluminum flakes using synthetic resin waste that would conventionally be discarded. Examples of such synthetic resin waste include, but are not limited to, mixtures of aluminum chips (including chips (aluminum powder)) and synthetic resin (including chips of synthetic resin (synthetic resin powder)) generated during the sash manufacturing process.

[0136] (2-2-2. Synthetic Resins) Specific examples of synthetic resins contained in the synthetic resin waste are the same as those explained in the section (1-2-2. Synthetic Resins) above, so that explanation will be incorporated herein by reference and will not be repeated here.

[0137] (2-2-3. Aluminum Pieces) In the second processing method (second embodiment), the term "aluminum pieces" refers to small pieces (e.g., 5.00 mm or less) of aluminum generated by cutting or milling a composite material of aluminum and synthetic resin or aluminum, and can also be called aluminum cuttings. The aluminum pieces can be, for example, aluminum powder.

[0138] The aluminum pieces are one aspect of the non-ferrous metal pieces in the first treatment method (first embodiment), and are one aspect of the non-ferrous metal.

[0139] In a composite material of aluminum and synthetic resin, the aluminum may be coated with other components (e.g., resin), etc. Therefore, a part or all of the aluminum piece may be coated with other components (e.g., resin).

[0140] For one aluminum piece, the diameter of the smallest sphere among those spheres that contain the entire aluminum piece inside and are inscribed with the aluminum piece at at least two points is referred to as the "diameter of the aluminum piece" in this specification. The diameter of the aluminum piece is preferably 0.63 mm or more, more preferably 0.80 mm or more, even more preferably 0.90 mm or more, and particularly preferably 1.10 mm or more. The upper limit of the diameter of the aluminum piece is preferably 5.00 mm or less or 3.00 mm or less. If the diameter of the aluminum piece is within the above range, the aluminum piece and the synthetic resin can be well separated in the first separation step described below.

[0141] The shape of the aluminum pieces is not particularly limited, but may be, for example, triangular or rectangular flakes.

[0142] The thickness of the aluminum pieces is not particularly limited, and depends on (i) the thickness of the aluminum product before cutting (slicing), and (ii) the rotation speed and cutting speed of the blade used to cut (slice) the aluminum product. The thickness of the aluminum pieces is, for example, preferably 0.05 mm or more and 1.00 mm or less, more preferably 0.10 mm or more and 0.95 mm or less, and even more preferably 0.15 mm or more and 0.90 mm or less. If the thickness of the aluminum pieces is within the above range, the aluminum pieces and synthetic resin can be well separated in the first separation step described below.

[0143] The width of the aluminum pieces is not particularly limited, and depends on the width of the saw blade used to cut (sever) the aluminum product. The width of the aluminum pieces is, for example, preferably 0.50 mm or more and 2.00 mm or less, more preferably 0.55 mm or more and 1.95 mm or less, and even more preferably 0.60 mm or more and 1.90 mm or less. If the width of the aluminum pieces is within the above range, the aluminum pieces and the synthetic resin can be well separated in the first separation step described below.

[0144] The length of the aluminum pieces is not particularly limited, but is, for example, preferably 0.50 mm to 5.00 mm, more preferably 0.55 mm to 4.95 mm, and even more preferably 0.60 mm to 4.90 mm. If the length of the aluminum pieces is within the above range, the aluminum pieces and the synthetic resin can be well separated in the first separation step described below.

[0145] (2-2-4. Anti-redeposition agent) This treatment method (second treatment method) uses an anti-redeposition agent. In the second treatment method (second embodiment), the "anti-redeposition agent" refers to a substance that can prevent adhesion (redeposition) between aluminum pieces and synthetic resin.

[0146] In this specification, with regard to the adhesion and re-adhesion between the synthetic resin and the aluminum piece, the terms "adhesion" and "re-adhesion" are synonymous and can be used interchangeably.

[0147] Specific examples of the anti-redeposition agent in the second treatment method (second embodiment) are the same as those described in the above section (1-2-4. Anti-redeposition agent), and therefore, the description therein is incorporated by reference and will not be described here.

[0148] In the second treatment method (second embodiment), the anti-redeposition agent is preferably a substance that adheres more easily to aluminum pieces than synthetic resin (for example, a substance that is more easily charged than the synthetic resin contained in synthetic resin waste, and a substance that can remove static electricity from synthetic resin), from the viewpoint of excellent anti-redeposition effect.

[0149] (2-2-5. Other additives) This treatment method (second treatment method) may use other additives. Specific examples of other additives are the same as those explained in the above section (1-2-4. Anti-redeposition agent), so that description is incorporated herein by reference and further explanation is omitted here. This treatment method (second treatment method) may use only one of the above-mentioned other additives, or may use two or more of them in combination.

[0150] (2-2-6. Adhesion prevention step) This treatment method (second treatment method) includes an adhesion prevention step. In this adhesion prevention step, synthetic resin waste containing aluminum pieces and synthetic resin, and a redeposition prevention agent are placed in a mixer having a rotor, and the rotor is rotated. By including the adhesion prevention step in this treatment method (second treatment method), the aluminum pieces and the redeposition prevention agent can be thoroughly mixed, and the aluminum pieces can be easily separated from the synthetic resin.

[0151] The specific aspects of the adhesion prevention step in the second treatment method (second embodiment) are the same as those described in the above section (1-2-6. Adhesion prevention step), so that description is incorporated herein and the description is omitted here.

[0152] As described above, this treatment method (second treatment method) does not require water. More specifically, in one embodiment of the present invention, water is not used in the adhesion prevention step. This configuration has the advantage of reducing the environmental load.

[0153] (2-2-7. Thermal Separation Step) In one embodiment of the present invention, in the synthetic resin waste to be treated, aluminum pieces and synthetic resin may be attached (adhered) via an adhesive layer made of, for example, a sealant (adhesive). In such cases, this treatment method (second treatment method) preferably includes a thermal separation step of separating the attached aluminum pieces and synthetic resin by heating.

[0154] The specific aspects of the thermal separation step in this treatment method (second treatment method) are the same as those described in the above section (1-2-7. Thermal treatment step), so that the description therein is incorporated by reference and the description will be omitted here.

[0155] (2-2-8. First Separation Step) It is preferable that this treatment method (second treatment method) further includes a first separation step after the adhesion prevention step. The first separation step that this treatment method (second treatment method) can have is a step of separating the mixture of the synthetic resin, the aluminum pieces, and the redeposition prevention agent obtained in the adhesion prevention step into the synthetic resin and the mixture of the aluminum pieces and the redeposition prevention agent. By including the first separation step in this treatment method (second treatment method), it is possible to obtain a synthetic resin that is free of aluminum pieces or has only a very small amount of aluminum pieces attached. The synthetic resin obtained in the first separation step can also be recycled.

[0156] The specific aspects of the first separation step in the second treatment method (second embodiment) are the same as those described in the above section (1-2-8. First separation step), so the description therein is incorporated by reference and the description will be omitted here.

[0157] (2-2-9. Second Separation Step) When the first separation step is carried out in this treatment method (second treatment method), it is preferable that this treatment method (second treatment method) further includes a second separation step after the first separation step. The second separation step that this treatment method (second treatment method) can have is a step of separating the mixture of the aluminum pieces and the anti-redeposition agent obtained in the first separation step into the aluminum pieces and the anti-redeposition agent. Including the second separation step in this treatment method (second treatment method) has the advantage that the separated anti-redeposition agent can be recycled.

[0158] The specific aspects of the second separation step in the second treatment method (second embodiment) are the same as those described in the above section (1-2-9. Second Separation Step), and therefore, the description therein is incorporated by reference and will not be repeated here.

[0159] 3. Third Embodiment 3-1. Technical Concept of One Embodiment of the Invention Packaging containers (e.g., PTP (press through pack) sheets) containing aluminum foil and synthetic resin are generally incinerated as waste (industrial waste) after use because it is difficult to separate the aluminum foil from the synthetic resin and recycling is difficult.

[0160] On the other hand, from the viewpoint of environmental considerations such as CO2 reduction in recent years, there is a demand for the establishment of recycling technology for the packaging containers.

[0161] In other words, there is a need to establish recycling technology for synthetic resin waste, which is synthetic resin waste with aluminum foil attached.

[0162] For example, Patent Document 1 discloses a method for separating aluminum foil and resin.

[0163] However, the above-mentioned aluminum foil / resin separation method has room for further improvement in terms of the separability between the aluminum foil and the resin.

[0164] Specifically, the present inventors have examined the technology disclosed in Patent Document 1 and independently discovered the following novel finding: with the technology disclosed in Patent Document 1, when the aluminum foil and synthetic resin are separated by heating, the aluminum foil and synthetic resin may re-adhere due to adhesive components present on the surface of the synthetic resin, meaning that the separability of the aluminum foil and synthetic resin is poor.

[0165] The third embodiment of the present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a method for separating aluminum foil and synthetic resin, which has excellent separability between the aluminum foil and synthetic resin.

[0166] The present inventors have conducted extensive research to solve the above problems. Specifically, the present inventors have conducted extensive research to provide a separation method for synthetic resin waste that can satisfactorily separate aluminum foil and synthetic resin, even when the aluminum foil and synthetic resin are separated by heating.

[0167] As a result, the inventors independently discovered the following novel finding, which led to the completion of the present invention: by stirring synthetic resin waste, which is synthetic resin waste with aluminum foil attached, while heating it to a specific temperature, and then adding an anti-redeposition agent and stirring it, it is surprisingly possible to successfully separate the aluminum foil and the synthetic resin.

[0168] 3-2. Method for Separating Aluminum Foil and Synthetic Resin A method for separating aluminum foil and synthetic resin according to one embodiment of the present invention includes a separation step of feeding synthetic resin waste, which is synthetic resin waste with aluminum foil attached, into a mixer having a rotor, rotating the rotor at a temperature of 65°C or higher and 130°C or lower, pulverizing the aluminum foil attached to the synthetic resin into aluminum pieces and separating the aluminum pieces from the synthetic resin, and an adhesion prevention step of feeding a redeposition prevention agent that prevents the aluminum pieces from adhering to the synthetic resin into the mixer and rotating the rotor.

[0169] In this specification, the "method for separating aluminum foil and synthetic resin" may be referred to as the "separation method," and the "method for separating aluminum foil and synthetic resin according to one embodiment of the present invention" may be referred to as the "present separation method."

[0170] Because of the above-described configuration, this separation method has the advantage of excellent separation ability between aluminum foil and synthetic resin. More specifically, because of the above-described configuration, this separation method can easily separate aluminum foil and synthetic resin at low cost without the need for expensive separation equipment. Furthermore, because water is not required for separation, it is also possible to reduce the environmental impact. Furthermore, because this separation method has excellent separation ability between aluminum foil and synthetic resin, it has the advantage of being able to provide synthetic resin that is, at least visually, free of aluminum foil adhesion or has only slight aluminum foil adhesion. This can promote the recycling of synthetic resin. Therefore, it can contribute to the achievement of Sustainable Development Goals (SDGs), such as Goal 12, "Ensure sustainable consumption and production patterns."

[0171] The third embodiment is included in the first embodiment. As described above, in one embodiment of the first treatment method (first embodiment), the non-ferrous metals contained in the synthetic resin waste preferably include aluminum. In one embodiment of the first treatment method (first embodiment), the non-ferrous metals contained in the synthetic resin waste preferably include aluminum flakes as flake-shaped non-ferrous metals (non-ferrous metal flakes). In one embodiment of the first treatment method (first embodiment), the non-ferrous metals contained in the synthetic resin waste preferably include aluminum foil as non-ferrous metal foil. Furthermore, the separation step in the third embodiment is one aspect of the thermal separation step, which is a preferred step in the first embodiment. That is, the third embodiment is one aspect of the first embodiment in which (i) the non-ferrous metals include aluminum (more specifically, aluminum flakes and aluminum foil) and (ii) the thermal separation step is included, and can also be said to be one preferred aspect of the first embodiment.

[0172] Each aspect of the third embodiment will be described below, but the descriptions in Sections [1. First Embodiment] and [2. Second Embodiment] will be used as appropriate for matters other than those described in detail below. When using the descriptions in Section [1. First Embodiment] for matters other than those described in detail below for the third embodiment, the term "non-ferrous metal" may be replaced with the term "aluminum piece."

[0173] (3-2-1. Synthetic Resin Waste) This separation method uses synthetic resin waste. In this separation method, "synthetic resin waste" refers to (i) synthetic resin products with aluminum foil attached (e.g., PTP (press-through package) sheets used to package tablets or capsules, food containers, packaging containers (e.g., packaging containers for disposable soft contact lenses), moisture-proof packaging containers, etc.) that have been used and are normally discarded, or (ii) synthetic resin products with aluminum foil attached that have been discarded and discarded during the manufacturing process. In this separation method, "synthetic resin waste" can also be said to refer to (i) synthetic resin products with aluminum foil attached that have been used and discarded because they would have been difficult to recycle in the past, or (ii) synthetic resin products with aluminum foil attached that have been discarded and discarded during the manufacturing process and have been discarded and discarded due to their difficulty to recycle in the past. This separation method allows synthetic resins that are substantially free of aluminum foil to be obtained using synthetic resin waste that would have been discarded in the past.

[0174] (3-2-2. Aluminum Foil) In this specification, "aluminum foil" refers to aluminum having a thickness of 6 μm or more and 200 μm or less. The term "foil" also includes sheets, films, and membranes. That is, aluminum foil includes aluminum foil, aluminum sheet, aluminum film, aluminum membrane, etc. having a thickness of 6 μm or more and 200 μm or less.

[0175] The aluminum foil is one aspect of the non-ferrous metal foil, one aspect of the non-ferrous metal piece, and one aspect of the non-ferrous metal in the first processing method (first embodiment). The aluminum foil is one aspect of the aluminum piece in the second processing method (second embodiment).

[0176] Examples of aluminum foils used in PTP sheets include aluminum foils for PTP packaging manufactured by UACJ Corporation and aluminum foils for PTP packaging manufactured by Toyo Aluminum K.K.

[0177] As used herein, "synthetic resin with aluminum foil attached" refers to a synthetic resin in which aluminum foil is directly attached to the synthetic resin, as well as a synthetic resin in which aluminum foil is indirectly attached to the synthetic resin. For example, in the case of PTP sheets or packaging containers for disposable soft contact lenses, aluminum foil forms a laminate with an adhesive layer composed of a sealant (adhesive), etc., and the laminate may adhere to the synthetic resin via the adhesive layer (sealant), thereby adhering the aluminum foil to the synthetic resin. More specifically, in PTP sheets or packaging containers for disposable soft contact lenses, a laminate containing aluminum foil may include, in order from the side that is attached to the synthetic resin, an adhesive layer (sealant layer), aluminum foil, and a protective layer. The aluminum foil in the laminate may be printed on one or both sides. In synthetic resin waste, aluminum foil can be said to be attached to the synthetic resin as a laminate, or to exist as a laminate. While the sealant (adhesive) is not particularly limited, heat-sealing agents that exhibit adhesive properties when heated are preferably used. The main components of the heat sealing agent may be, for example, vinyl chloride / vinyl acetate copolymer (vinyl chloride / vinyl acetate resin) and polyester, and the softening point of such a heat sealing agent (the temperature at which it can exhibit adhesive properties) is approximately 60°C.

[0178] (3-2-3. Synthetic Resins) Specific examples of synthetic resins contained in the synthetic resin waste are the same as those explained in the section (1-2-2. Synthetic Resins) above, so that explanation will be incorporated herein by reference and will not be repeated here.

[0179] (3-2-4. Aluminum Pieces) In this separation method, "aluminum pieces" refers to crushed aluminum foil, and can also be called crushed aluminum foil. The aluminum pieces may be an aggregate (lump) of two or more crushed aluminum foil pieces. As mentioned above, when aluminum foil is present as a laminate in the synthetic resin waste, the aluminum pieces may be a crushed laminate or crushed laminate.

[0180] In this separation method, the diameter of the aluminum pieces is preferably 0.63 mm or more, more preferably 0.80 mm or more, even more preferably 0.90 mm or more, and particularly preferably 1.10 mm or more. The upper limit of the diameter of the aluminum pieces is not particularly limited, but is, for example, 5.00 mm or less or 3.00 mm or less. If the diameter of the aluminum pieces is within the above range, the aluminum pieces and the synthetic resin can be well separated in the adhesion prevention step and the first sorting step described below. The diameter of the aluminum pieces can be adjusted by changing the temperature in the mixer in the separation step, the temperature of the synthetic resin waste itself, the rotation speed and rotation time of the rotor, etc.

[0181] (3-2-5. Anti-redeposition agent) This separation method uses an anti-redeposition agent. In this separation method, the term "anti-redeposition agent" refers to a substance that can prevent adhesion (redeposition) between the aluminum pieces and the synthetic resin.

[0182] Specific examples of the anti-redeposition agent in this separation method are the same as those explained in the above section (1-2-4. Anti-redeposition agent), so the explanation therefor is incorporated by reference and will not be repeated here.

[0183] In this separation method, too, the anti-redeposition agent is preferably a substance that adheres more easily to aluminum pieces than synthetic resin, in terms of its excellent anti-redeposition effect (for example, a substance that is more easily charged than the synthetic resin contained in synthetic resin waste, or a substance that can remove static electricity from synthetic resin).

[0184] In this separation method, too, when the anti-redeposition agent is a polymer, copolymer, or resin, the anti-redeposition agent is preferably in the form of a powder. In other words, when the anti-redeposition agent is a polymer, copolymer, or resin, the anti-redeposition agent is preferably in the form of a powder. This configuration has the advantage that it is easy to incorporate adhesive components that melt with heat and to easily coat the synthetic resin surface, thereby further enhancing the anti-redeposition effect. Inorganic fillers such as calcium carbonate and talc also easily incorporate adhesive components that melt with heat and to easily coat the synthetic resin surface. Therefore, in this separation method, even when the anti-redeposition agent is an inorganic filler such as calcium carbonate or talc, it has the advantage that it is even more effective in enhancing the anti-redeposition effect, for the reasons described above.

[0185] (3-2-6. Other Additives) The present separation method may use other additives. Specific examples of other additives are the same as those explained in the above section (1-2-4. Anti-redeposition Agent), and therefore, the explanation therefor is omitted here by citing the above description. The present separation method may use only one of the above-mentioned other additives, or may use two or more of them in combination.

[0186] (3-2-7. Separation Process) This separation method includes a separation process. In this separation process, synthetic resin waste, which is synthetic resin waste with aluminum foil attached, is placed in a mixer having a rotor, and the rotor is rotated at a temperature of 65°C or higher and 130°C or lower. In the separation process, the rotation of the rotor can crush the aluminum foil attached to the synthetic resin into aluminum pieces. Furthermore, by rotating the rotor at a temperature of 65°C or higher and 130°C or lower in the separation process, the adhesion between the aluminum foil and the synthetic resin via the adhesive layer can be loosened. As a result, in the separation process, the aluminum pieces can be separated from the synthetic resin.

[0187] The separation step in this separation method can be said to be one aspect of the thermal separation step, which is an optional step in the first treatment method (first embodiment).

[0188] (Mixer) The mixer used in this separation method is not particularly limited as long as it has a rotor. Examples of the mixer used in this separation method include those described in the (Mixer) section of the (1-2-6. Adhesion prevention step) section. Therefore, the description in the (Mixer) section of the (1-2-6. Adhesion prevention step) section is incorporated herein by reference, and a detailed description thereof will be omitted here.

[0189] The rotation of the rotor in the separation step is carried out at a temperature of 65°C to 130°C, preferably 75°C to 120°C, more preferably 80°C to 115°C, even more preferably 85°C to 105°C, and particularly preferably 90°C to 100°C. If the temperature in the separation step is within the above range, the adhesion between the aluminum foil and the synthetic resin via the adhesive layer can be efficiently loosened. As a result, there is an advantage in that the aluminum foil and the synthetic resin can be more easily separated. Here, "the rotation of the rotor in the separation step is carried out at a temperature of 65°C to 130°C" means that the rotor in the separation step is rotated (i) when the temperature inside the mixer is 65°C to 130°C, and / or (ii) when the temperature of the synthetic resin waste itself is 65°C to 130°C. In the separation step, it is sufficient that at least a portion of the period during which the rotor of the mixer is rotating (rotation time) is carried out at a temperature of 65° C. or higher and 130° C. or lower, and it is not necessary to carry out the entire period at a temperature of 65° C. or higher and 130° C. or lower. In one embodiment of the present invention, it is particularly preferable to carry out the entire period during which the rotor is rotating in the separation step at a temperature of 65° C. or higher and 130° C. or lower, as this further improves the separability of the aluminum foil and the synthetic resin.

[0190] The method for adjusting the temperature inside the mixer is not particularly limited, but examples thereof include a method of blowing hot air into the mixer, and a method of directly heating the mixer body with steam and / or a heater.

[0191] The method for adjusting the temperature of the synthetic resin waste itself is not particularly limited, but examples include a method in which the temperature of the synthetic resin waste itself is increased by causing the synthetic resin waste to self-heat due to shear caused by the rotation of the rotor of the mixer, a method in which the temperature of the synthetic resin waste itself is increased by blowing hot air into the mixer, and a method in which the temperature of the synthetic resin waste itself is increased by directly heating the mixer body with steam and / or a heater, etc.

[0192] The period during which the rotor of the mixer rotates in the separation process, in other words, the rotation time, may be adjusted taking into consideration (a) the mixing capacity of the mixer; (b) the temperature inside the mixer and / or the temperature of the synthetic resin waste itself; and (c) the type and amount of synthetic resin waste. The rotation time is, for example, preferably 5 minutes or more and 30 minutes or less, more preferably 13 minutes or more and 20 minutes or less, and even more preferably 10 minutes or more and 15 minutes or less. The "period during which the rotor of the mixer rotates in the separation process" (rotation time) refers to the period from the time when mixing (shearing) of the synthetic resin waste by rotation of the rotor begins to the time when mixing (shearing) of the synthetic resin waste by rotation of the rotor is completed.

[0193] The rotation speed of the rotor of the mixer in the separation step may be adjusted taking into consideration (a) the mixing capacity of the mixer; (b) the temperature inside the mixer and / or the temperature of the synthetic resin waste itself; and (c) the type and amount of synthetic resin waste. The rotation speed of the rotor of the mixer in the separation step is, for example, preferably 100 rpm or more and 3000 rpm or less, more preferably 150 rpm or more and 2500 rpm or less, and even more preferably 500 rpm or more and 2000 rpm or less. During the period (rotation time) during which the rotor of the mixer is rotating in the separation step, it is preferable that the rotation speed of the rotor is within the above-mentioned range for at least a part of the period, and it is particularly preferable that the rotation speed of the rotor is within the above-mentioned range for the entire period.

[0194] The synthetic resin waste may be charged in the entire amount used in the separation method at once, or may be charged in several divided portions, or may be charged in fixed amounts continuously. For example, in the adhesion prevention step described below, after a redeposition prevention agent is charged into the mixer, the synthetic resin waste may be charged into the mixer again.

[0195] As described above, this separation method does not require water. More specifically, in one embodiment of the present invention, water is not used in the separation step. This configuration has the advantage of reducing the environmental load.

[0196] (3-2-8. Adhesion prevention step) This separation method includes an adhesion prevention step. The adhesion prevention step is a step of adding an anti-redeposition agent that prevents the aluminum pieces and the synthetic resin from re-adhering to the mixer, and rotating the rotor. Including the adhesion prevention step in this separation method has the advantage of preventing the aluminum pieces and synthetic resin separated in the separation step from re-adhering to each other.

[0197] In the adhesion prevention step, the anti-redeposition agent is preferably blended in an amount of 1 part by weight to 50 parts by weight, more preferably 3 parts by weight to 40 parts by weight, even more preferably 5 parts by weight to 30 parts by weight, and particularly preferably 15 parts by weight to 25 parts by weight, per 100 parts by weight of synthetic resin waste. When the anti-redeposition agent is used within the above range, redeposition of the aluminum pieces and the synthetic resin can be sufficiently prevented.

[0198] The anti-redeposition agent may be added to the mixer (a) together with or separately from the synthetic resin waste when the synthetic resin waste is added to the mixer (i.e., at the start of the separation process) (Case 4); (b) while the synthetic resin waste is being added to the mixer and the rotor is being rotated while being heated to separate the aluminum pieces from the synthetic resin (i.e., during the separation process) (Case 5); or (c) after the synthetic resin waste is being added to the mixer and the rotor is being rotated while being heated to separate the aluminum pieces from the synthetic resin (i.e., after the separation process) (Case 6). From the viewpoint of further preventing the re-adhesion of the aluminum pieces and the synthetic resin, it is preferable to add the anti-redeposition agent at the timing of (b). Furthermore, the anti-redeposition agent may be added in the entire amount used in the separation method at once, in multiple installments, or continuously in fixed amounts. For example, in (i) Case 4, the anti-redeposition agent may be added again to the mixer during and / or after the separation step, and in (ii) Case 5, the anti-redeposition material may be added again to the mixer after the separation step.

[0199] The temperature in the adhesion prevention step is not particularly limited, and may be 65°C or higher and 130°C or lower, 75°C or higher and 120°C or lower, 80°C or higher and 115°C or lower, 85°C or higher and 105°C or lower, or 90°C or higher and 100°C or lower. The "temperature in the adhesion prevention step" refers to the temperature inside the mixer and / or the temperature of the synthetic resin itself. During the period (rotation time) during which the rotor of the mixer is rotating in the adhesion prevention step, it is preferable to perform the step within the above-mentioned temperature range for at least a portion of the period, and more preferably for the entire period, during which the rotor of the mixer is rotating.

[0200] The method for adjusting the temperature inside the mixer in the adhesion prevention step is the same as the method for adjusting the temperature inside the mixer in the separation step explained in the above section (3-2-7. Separation step), so that description is used by reference and a further explanation is omitted here. Also, the method for adjusting the temperature of the synthetic resin itself in the adhesion prevention step is the same as the description of the method for adjusting the temperature of the synthetic resin waste itself in the separation step explained in the above section (3-2-7. Separation step), except for replacing "synthetic resin waste" with "synthetic resin", so that description is used by reference and a further explanation is omitted here.

[0201] The period during which the mixer rotor rotates in the adhesion prevention process, in other words, the rotation time, may be adjusted taking into consideration (a) the mixing capacity of the mixer; (b) the temperature inside the mixer and / or the temperature of the synthetic resin itself; and (c) the type and amount of synthetic resin waste. For example, the rotation time is preferably 5 to 30 minutes in Case 4 above, 13 to 20 minutes in Case 5 above, and 10 to 15 minutes in Case 6 above. The "period during which the mixer rotor rotates in the adhesion prevention process" (rotation time) refers to the period from the start of mixing the synthetic resin waste and the anti-redeposition agent by the rotation of the rotor to the end of mixing the synthetic resin waste and the anti-redeposition agent by the rotation of the rotor. In Case 4 above, the separation process and the adhesion prevention process start and end simultaneously, so the "period during which the mixer rotor rotates in the separation process" and the "period during which the mixer rotor rotates in the adhesion prevention process" are the same time (value).

[0202] The rotation speed of the mixer rotor in the adhesion prevention step may be adjusted taking into consideration (a) the mixing capacity of the mixer; (b) the temperature inside the mixer and / or the temperature of the synthetic resin itself; and (c) the type and amount of synthetic resin waste. The rotation speed of the mixer rotor in the adhesion prevention step is, for example, preferably 100 rpm or more and 3000 rpm or less, more preferably 150 rpm or more and 2500 rpm or less, and even more preferably 500 rpm or more and 2000 rpm or less. During the period (rotation time) during which the mixer rotor is rotating in the adhesion prevention step, it is preferable that the rotation speed of the rotor is within the above-mentioned range for at least a portion of the period, and it is particularly preferable that the rotation speed of the rotor is within the above-mentioned range for the entire period.

[0203] As described above, this separation method does not require water. More specifically, in one embodiment of the present invention, water is not used in the adhesion prevention step. This configuration has the advantage of reducing the environmental load.

[0204] (3-2-9. First Separation Step) It is preferable that the present separation method further includes a first separation step after the adhesion prevention step. The first separation step that the present separation method may have is a step of separating the mixture of the synthetic resin, the aluminum pieces, and the anti-redeposition agent obtained in the adhesion prevention step into the synthetic resin and the mixture of the aluminum pieces and the anti-redeposition agent. By including the first separation step in the present separation method, it is possible to obtain a synthetic resin that has no aluminum foil attached, or has only a very small amount of aluminum foil attached. The synthetic resin obtained in the first separation step can also be recycled.

[0205] The specific aspects of the first fractionation step in this separation method (third embodiment) are the same as those described in the section (1-2-8. First fractionation step) above, and therefore, the description therein is incorporated by reference and will not be repeated here.

[0206] (3-2-10. Second Separation Step) When the first separation step is carried out in this separation method, it is preferable that this separation method further includes a second separation step after the first separation step. The second separation step that this separation method may have is a step of separating the mixture of the aluminum pieces and the anti-redeposition agent obtained in the first separation step into the aluminum pieces and the anti-redeposition agent. Including the second separation step in this separation method has the advantage that the separated anti-redeposition agent can be recycled.

[0207] The specific aspects of the second fractionation step in this separation method (third embodiment) are the same as those described in the section (1-2-9. Second fractionation step) above, and therefore, the description therein is incorporated by reference and will not be repeated here.

[0208] [4. Method for Producing Recycled Synthetic Resin] One embodiment of the present invention also includes a method for producing a recycled synthetic resin. The method for producing a recycled synthetic resin according to one embodiment of the present invention includes, as one step, one or more methods selected from the group consisting of (i) the present treatment method (first treatment method) described in the above section [1-2. Method for Treating Synthetic Resin Waste (First Treatment Method)], (ii) the present treatment method (second treatment method) described in the above section [2-2. Method for Treating Synthetic Resin Waste (Second Treatment Method)], and (iii) the present separation method described in the above section [3-2. Method for Separating Aluminum Foil and Synthetic Resin].

[0209] In this specification, the term "method for producing recycled synthetic resin" may be referred to as "production method," and the term "method for producing recycled synthetic resin according to one embodiment of the present invention" may be referred to as "this production method."

[0210] (4-1. First Treatment Step, Second Treatment Step, or Separation Step) The present manufacturing method preferably includes a first treatment step of treating synthetic resin waste by the present treatment method (first treatment method). Specific aspects of the first treatment step of the present manufacturing method are similar to those of the present treatment method (first treatment method) (particularly the adhesion prevention step) described in detail in the above section [1-2. Method for Treating Synthetic Resin Waste (First Treatment Method)], so the description therein is incorporated by reference and a detailed description thereof will be omitted here. The present manufacturing method preferably includes a second treatment step of treating synthetic resin waste by the present treatment method (second treatment method). Specific aspects of the second treatment step of the present manufacturing method are similar to those of the present treatment method (second treatment method) (particularly the adhesion prevention step) described in detail in the above section [2-2. Method for Treating Synthetic Resin Waste (Second Treatment Method)], so the description therein is incorporated by reference and a detailed description thereof will be omitted here. The present manufacturing method preferably includes a separation step of separating synthetic resin waste into aluminum foil and synthetic resin by the present separation method. This separation method is the same as the separation method (particularly the separation step and adhesion prevention step) described in detail in the above section [3-2. Method for separating aluminum foil and synthetic resin], so the description therein is incorporated herein and the explanation is omitted here.

[0211] The first treatment step in this manufacturing method may include the adhesion prevention step described in the above section (1-2-6. Adhesion prevention step). The first treatment step in this manufacturing method may further include the heat treatment step described in the above section (1-2-7. Thermal separation step). The first treatment step in this manufacturing method preferably includes the first separation step described in the above section (1-2-8. First separation step) and the second separation step described in the above section (1-2-9. Second separation step). The second treatment step in this manufacturing method may include the adhesion prevention step described in the above section (2-2-6. Adhesion prevention step). The second treatment step in this manufacturing method may further include the heat treatment step described in the above section (2-2-7. Thermal separation step). The second treatment step in this manufacturing method preferably includes the first separation step described in the above section (2-2-8. First separation step) and the second separation step described in the above section (2-2-9. Second separation step). The separation step in this production method may include the separation step described in the above section (3-2-7. Separation step) and the adhesion prevention step described in the above section (3-2-8. Adhesion prevention step). The separation step in this production method preferably includes the first separation step described in the above section (3-2-9. First separation step) and the second separation step described in the above section (3-2-10. Second separation step).

[0212] (Recycled Synthetic Resin) In this specification, the term "recycled synthetic resin" refers to a synthetic resin that is reused or recycled after being used one or more times. In one embodiment of the present invention, the recycled synthetic resin refers to a synthetic resin derived from synthetic resin waste and separated from non-ferrous metals in a first treatment step. The recycled synthetic resin may include the anti-redeposition agent used in the first treatment step. In one embodiment of the present invention, the recycled synthetic resin refers to a synthetic resin derived from synthetic resin waste and separated from aluminum pieces in a second treatment step. The recycled synthetic resin may include the anti-redeposition agent used in the first treatment step. In one embodiment of the present invention, the recycled synthetic resin refers to a synthetic resin separated from aluminum pieces in a separation step. The recycled synthetic resin may include the anti-redeposition agent separated in the separation step.

[0213] In this production method, the amount of the anti-redeposition agent contained in the recycled synthetic resin is preferably 5.0% by weight or less, more preferably 3.0% by weight or less, even more preferably 2.0% by weight or less, particularly preferably 1.5% by weight or less, and most preferably 0.0% by weight, based on 100% by weight of the recycled synthetic resin. In other words, the recycled synthetic resin is most preferably a synthetic resin that does not contain an anti-redeposition agent.

[0214] (4-2. Washing Step) The present production method may include a washing step in which the synthetic resin is washed with an aqueous solvent. The washing step that the present production method may include may be a step in which the synthetic resin obtained in the first treatment step or the second treatment step is washed with an aqueous solvent. The washing step that the present production method may include may be a step in which the synthetic resin obtained in the separation step is washed with an aqueous solvent. The washing step that the present production method may include is preferably a step in which the synthetic resin obtained in the first separation step, which may be included in the first treatment step, the second treatment step, or the separation step, is washed with an aqueous solvent. By including a washing step in the present production method, it is possible to remove non-ferrous metals and / or mixed redeposition inhibitors that may remain in the synthetic resin obtained in the first treatment step, the second treatment step, the separation step, or the first separation step. This has the advantage of allowing for the production of recycled synthetic resin with few (or no) impurities.

[0215] In the washing step, the method for washing the synthetic resin is not particularly limited, and examples of the method for washing the synthetic resin in the washing step include a method of adding an aqueous solvent to the synthetic resin, a method of immersing the synthetic resin in an aqueous solvent, and a method of stirring the synthetic resin while immersing it in an aqueous solvent.

[0216] The aqueous solvent used in the washing step is not particularly limited as long as it is an aqueous liquid that can wash the synthetic resin without causing deterioration, and examples of such aqueous solvents include tap water, distilled water, and deionized water.

[0217] The temperature of the aqueous solvent in the washing step is not particularly limited as long as it is a temperature at which the synthetic resin is not denatured, and may be, for example, room temperature (18° C. or higher and 25° C. or lower). As the aqueous solvent in the washing step, steam of the aqueous solvent may be used.

[0218] The amount of aqueous solvent used in the washing step is not particularly limited as long as it can sufficiently wash the synthetic resin, but it can be, for example, 2,000 parts by weight or more, 10,000 parts by weight or more, or 100,000 parts by weight or more per 100 parts by weight of the synthetic resin.

[0219] When the present production method includes a washing step, the washing step needs to be carried out at least once, but may be carried out multiple times.

[0220] In the present production method, the timing of performing the washing step is not particularly limited. In the present production method, the timing of performing the washing step may be (i) any timing after the first treatment step, the second treatment step, or the separation step, or during the first treatment step, the second treatment step, or the separation step. In the present production method, when the first treatment step, the second treatment step, or the separation step includes a first separation step, the timing of performing the washing step is preferably after the first separation step.

[0221] A recycled synthetic resin obtained by a method for producing a recycled synthetic resin according to one embodiment of the present invention can also be considered to be one embodiment of the present invention. In this specification, the "recycled synthetic resin according to one embodiment of the present invention" may be referred to as the "present recycled synthetic resin."

[0222] The recycled synthetic resin is suitable for use in any synthetic resin product and any composite product of non-ferrous metal and synthetic resin, and can therefore be used in fields such as sashes (e.g., resin sashes (exterior windows), resin sashes (interior windows), resin-non-ferrous metal composite sashes (e.g., resin-aluminum composite sashes), recycled resin sashes, etc.), electric wires, wire harnesses, CCL, components made by insert molding synthetic resin and metal, PTPs, food containers, packaging containers, and moisture-proof packaging containers.

[0223] [5. Applications] One embodiment of the present invention can be suitably used in fields such as composite materials of non-ferrous metals (e.g., aluminum pieces and aluminum foil) and synthetic resins, such as sashes (e.g., resin sashes (exterior windows), resin sashes (interior windows), resin-nonferrous metal composite sashes (e.g., resin-aluminum composite sashes), recycled resin sashes, etc.), electric wires, wire harnesses, CCL, components obtained by insert molding synthetic resins and metals, PTPs, food containers, packaging containers, and moisture-proof packaging containers.

[0224] An embodiment of the present invention may have the following configuration.

[0225] [1] A method for treating synthetic resin waste, comprising an adhesion prevention step of feeding synthetic resin waste containing non-ferrous metals and synthetic resins and a redeposition prevention agent into a mixer having a rotor and rotating the rotor.

[0226] [2] The method for treating synthetic resin waste according to [1], wherein the non-ferrous metals include aluminum.

[0227] [3] The method for treating synthetic resin waste according to [1] or [2], further comprising a thermal separation step of separating the non-ferrous metals and the synthetic resin by heating.

[0228] [4] The method for treating synthetic resin waste according to [3], wherein the heating temperature in the thermal separation step is 65°C or higher and 130°C or lower.

[0229] [5] A method for treating synthetic resin waste according to any one of [1] to [4], further comprising a first separation step of separating the mixture of the synthetic resin, the non-ferrous metal, and the anti-redeposition agent obtained in the anti-adhesion step into the synthetic resin and the mixture of the non-ferrous metal and the anti-redeposition agent.

[0230] [6] The method for treating synthetic resin waste according to [5], further comprising a second separation step of separating the mixture of the non-ferrous metals and the anti-redeposition agent obtained in the first separation step into the non-ferrous metals and the anti-redeposition agent.

[0231] [7] A method for treating synthetic resin waste according to any one of [1] to [6], wherein water is not used in the adhesion prevention step.

[0232] [8] The method for treating synthetic resin waste according to any one of [1] to [7], wherein the anti-redeposition agent comprises one or more selected from the group consisting of polyvinyl chloride resin, a copolymer containing an α-methylstyrene unit, an acrylic polymer, a styrene / acrylonitrile copolymer, an acrylonitrile / butadiene / styrene copolymer, an inorganic filler, a metal soap, and wax.

[0233] [9] A method for treating synthetic resin waste according to any one of [1] to [8], wherein the volume average particle diameter of the anti-redeposition agent is 1 μm or more and 1000 μm or less.

[0234]

[10] A method for treating synthetic resin waste described in any one of [1] to [9], wherein in the adhesion prevention process, the anti-redeposition agent is blended in an amount of 1 part by weight or more and 50 parts by weight or less per 100 parts by weight of synthetic resin waste.

[0235]

[11] A method for treating synthetic resin waste described in any one of [1] to

[10] , wherein the diameter of the non-ferrous metal is 0.63 mm or more and 3.00 mm or less, and the diameter of the non-ferrous metal is the diameter of the smallest sphere among spheres that contain the entire non-ferrous metal inside and are in contact with the non-ferrous metal at at least two points.

[0236]

[12] The method for treating synthetic resin waste according to any one of [1] to

[11] , wherein the anti-redeposition agent is a recycled anti-redeposition agent.

[0237]

[13] A method for producing recycled synthetic resin, comprising the method for treating synthetic resin waste according to any one of [1] to

[12] as one step.

[0238]

[14] A recycled synthetic resin obtained by a method for producing a recycled synthetic resin, which includes, as one step, the method for treating synthetic resin waste according to any one of [1] to

[12] .

[0239] An embodiment of the present invention may have the following configuration.

[0240] [1] A method for treating synthetic resin waste, comprising a redeposition prevention step of feeding synthetic resin waste containing non-ferrous metals and synthetic resins and a redeposition prevention agent into a mixer having a rotor and rotating the rotor.

[0241] [2] The method for treating synthetic resin waste described in [1], further comprising a first separation step of separating the mixture of the synthetic resin, the non-ferrous metal, and the anti-redeposition agent obtained in the anti-redeposition step into the synthetic resin and the mixture of the non-ferrous metal and the anti-redeposition agent.

[0242] [3] The method for treating synthetic resin waste according to [1] or [2], wherein the anti-redeposition agent comprises one or more selected from the group consisting of polyvinyl chloride resin, a copolymer containing an α-methylstyrene unit, an acrylic polymer, a styrene / acrylonitrile copolymer, an acrylonitrile / butadiene / styrene copolymer, an inorganic filler, a metal soap, and wax.

[0243] [4] The method for treating synthetic resin waste according to any one of [1] to [3], wherein the volume average particle diameter of the anti-redeposition agent is 1 μm or more and 1000 μm or less.

[0244] [5] A method for treating synthetic resin waste according to any one of [1] to [4], further comprising a second separation step of separating the mixture of the non-ferrous metals and the anti-redeposition agent obtained in the first separation step into the non-ferrous metals and the anti-redeposition agent.

[0245] [6] The method for treating synthetic resin waste according to any one of [1] to [5], wherein the anti-redeposition agent is a recycled anti-redeposition agent.

[0246] [7] A method for treating synthetic resin waste described in any one of [1] to [6], wherein in the redeposition prevention step, the anti-redeposition agent is blended in an amount of 1 part by weight or more and 50 parts by weight or less per 100 parts by weight of synthetic resin waste.

[0247] [8] A method for treating synthetic resin waste described in any one of [1] to [7], wherein the diameter of the non-ferrous metal is 0.63 mm or more and 3.00 mm or less, and the diameter of the non-ferrous metal is the diameter of the smallest sphere among spheres that contain the entire non-ferrous metal inside and are in contact with the non-ferrous metal at at least two points.

[0248] [9] A method for producing recycled synthetic resin, comprising the method for treating synthetic resin waste according to any one of [1] to [8] as one step.

[0249] An embodiment of the present invention may have the following configuration.

[0250] [1] A method for treating synthetic resin waste, comprising a redeposition prevention step of feeding synthetic resin waste containing aluminum pieces and synthetic resin, and a redeposition prevention agent into a mixer having a rotor, and rotating the rotor.

[0251] [2] The method for treating synthetic resin waste described in [1], further comprising a first separation step of separating the mixture of the synthetic resin, the aluminum pieces, and the redeposition preventing agent obtained in the redeposition preventing step into the synthetic resin and the mixture of the aluminum pieces and the redeposition preventing agent.

[0252] [3] The method for treating synthetic resin waste according to [1] or [2], wherein the anti-redeposition agent comprises one or more selected from the group consisting of polyvinyl chloride resin, a copolymer containing an α-methylstyrene unit, an acrylic polymer, a styrene / acrylonitrile copolymer, an acrylonitrile / butadiene / styrene copolymer, an inorganic filler, a metal soap, and wax.

[0253] [4] The method for treating synthetic resin waste according to any one of [1] to [3], wherein the volume average particle diameter of the anti-redeposition agent is 1 μm or more and 1000 μm or less.

[0254] [5] The method for treating synthetic resin waste described in any one of [1] to [4], further comprising a second sorting step of separating the mixture of the aluminum pieces and the anti-redeposition agent obtained in the first sorting step into the aluminum pieces and the anti-redeposition agent.

[0255] [6] The method for treating synthetic resin waste according to any one of [1] to [5], wherein the anti-redeposition agent is a recycled anti-redeposition agent.

[0256] [7] A method for treating synthetic resin waste described in any one of [1] to [6], wherein in the redeposition prevention step, the anti-redeposition agent is blended in an amount of 1 part by weight or more and 50 parts by weight or less per 100 parts by weight of synthetic resin waste.

[0257] [8] A method for treating synthetic resin waste described in any one of [1] to [7], wherein the diameter of the aluminum piece is 0.63 mm or more and 3.00 mm or less, and the diameter of the aluminum piece is the diameter of the smallest sphere among spheres that contain the entire aluminum piece inside and are inscribed with the aluminum piece in at least two places.

[0258] [9] A method for producing recycled synthetic resin, comprising the method for treating synthetic resin waste according to any one of [1] to [8] as one step.

[0259] An embodiment of the present invention may have the following configuration.

[0260] [1] A method for separating aluminum foil and synthetic resin, comprising: a separation step of feeding synthetic resin waste, which is synthetic resin waste with aluminum foil attached, into a mixer having a rotor, rotating the rotor at a temperature of 65°C or higher and 130°C or lower, pulverizing the aluminum foil attached to the synthetic resin into aluminum pieces, and separating the aluminum pieces from the synthetic resin; and a redeposition prevention step of feeding a redeposition prevention agent into the mixer to prevent the aluminum pieces from adhering to the synthetic resin, and rotating the rotor.

[0261] [2] The method for separating aluminum foil and synthetic resin according to [1], further comprising a first separation step of separating the mixture of the synthetic resin, the aluminum pieces, and the anti-redeposition agent obtained in the anti-redeposition step into the synthetic resin and the mixture of the aluminum pieces and the anti-redeposition agent.

[0262] [3] The method for separating an aluminum foil from a synthetic resin according to [1] or [2], wherein the anti-redeposition agent comprises one or more selected from the group consisting of polyvinyl chloride resin, a copolymer containing an α-methylstyrene unit, an acrylic polymer, a styrene / acrylonitrile copolymer, an acrylonitrile / butadiene / styrene copolymer, an inorganic filler, a metal soap, and wax.

[0263] [4] The method for separating an aluminum foil from a synthetic resin according to any one of [1] to [3], wherein the volume average particle diameter of the anti-redeposition agent is 1 μm or more and 1000 μm or less.

[0264] [5] The method for separating aluminum foil and synthetic resin according to any one of [1] to [4], further comprising a second separation step of separating the mixture of aluminum pieces and the anti-redeposition agent obtained in the first separation step into the aluminum pieces and the anti-redeposition agent.

[0265] [6] The method for separating an aluminum foil from a synthetic resin according to any one of [1] to [5], wherein the anti-redeposition agent is a recycled anti-redeposition agent.

[0266] [7] In the reattachment prevention step, the reattachment prevention agent is blended in an amount of 1 part by weight or more and 50 parts by weight or less per 100 parts by weight of synthetic resin waste. [1] to [6] A method for separating aluminum foil and synthetic resin according to any one of the above.

[0267] [8] A method for producing recycled synthetic resin, comprising the method for separating aluminum foil and synthetic resin according to any one of [1] to [7] as one step.

[0268] Hereinafter, one embodiment of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited thereto. One embodiment of the present invention can be carried out by appropriately modifying the following examples within the scope that can comply with the above-mentioned and below-mentioned aims. All embodiments carried out by appropriately modifying the following examples are included within the technical scope of the present invention. In the following examples, comparative examples, and tables, "parts" and "%" mean parts by weight and % by weight, respectively.

[0269] Example A (Example According to First Embodiment) Measurement and Evaluation Methods The measurement and evaluation methods for each physical property measured in Example A are shown below.

[0270] <Weight-average molecular weight of copolymer or composite> The copolymer or composite to be measured was dissolved in tetrahydrofuran (THF) to obtain a THF-soluble fraction. The weight-average molecular weight of the THF-soluble fraction was determined using gel permeation chromatography (Tosoh Corporation, HLC-8220GPC) (sample solution: 20 mg sample / 10 mL THF, measurement temperature: 25 ° C, detector: differential refractometer, injection amount: 1 mL). Separately, polystyrene with a known weight-average molecular weight was subjected to gel permeation chromatography under the same conditions as the sample, and a calibration curve was prepared. Using the obtained calibration curve, the weight-average molecular weight of the copolymer or composite was calculated in terms of polystyrene.

[0271] <Volume Average Particle Diameter> The volume average particle diameter (volume average diameter) of the anti-redeposition agent was measured using a laser diffraction particle size distribution analyzer (MICROTRAC MT3300EXII, manufactured by Microtrackbell Co., Ltd.) by inputting the refractive index of each sample (for example, 1.49 for acrylic polymers), measuring for 20 seconds, measuring three times, and adjusting the sample concentration so that the loading index was in the range of 0.1 to 1. A dispersion obtained by dispersing the anti-redeposition agent in water was used as the measurement sample. The specific measurement method followed the instruction manual for the device.

[0272] <Evaluation of Separability> The separability of the treatment method was evaluated by visually checking the synthetic resins separated in the first separation step for adhesion of non-ferrous metals. Regarding separability, if there was no adhesion of non-ferrous metals to the synthetic resin, it was rated as "good", and if there was adhesion of non-ferrous metals, it was rated as "poor".

[0273] [Materials] The materials used in Example A and Comparative Example A are shown below.

[0274] <Synthetic Resin Waste (A)> A1: A mixture of 100 parts by weight of crushed polyvinyl chloride resin and 1 part by weight of non-ferrous metal pieces (copper chips (diameter 1 mm or more and 2 mm or less)).

[0275] A2: A mixture obtained by mixing 100 parts by weight of pulverized polyvinyl chloride resin with 1 part by weight of non-ferrous metal pieces (stainless steel chips (diameter 1 mm or more and 2 mm or less)).

[0276] <Anti-redeposition agents (B)> B1: Calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., Whiten SB, volume average particle diameter 2.5 μm) B2: Talc (manufactured by Nippon Talc Co., Ltd., PA-AB, volume average particle diameter 14 μm) B3: Calcium stearate (manufactured by Sakai Chemical Co., Ltd., SC-100, volume average particle diameter 9.8 μm) B4: ABS resin (manufactured by Nippon A&L Co., Ltd., K-2540A, volume average particle diameter 165 μm, powder) B5: AN-α methylstyrene copolymer (manufactured by Kaneka Corporation, Tellalloy, volume average particle diameter 160 μm, powder) B6: Styrene / acrylonitrile copolymer (manufactured by Galata Chemicals, BLENDEX 869, SAN processing aid, weight average molecular weight (Mw) approximately 3 million, volume average particle diameter 120 μm, powder) B7: Anti-redeposition agent obtained in Production Example A1 below, volume average particle diameter 165 μm, powder B8: Anti-redeposition agent obtained in Production Example A2 below, volume average particle diameter 190 μm, powder.

[0277] [Production Example A] <Production Example A1> (Production of anti-redeposition agent B7) 0.5 parts of sodium dioctyl succinate was dissolved in water to prepare an aqueous solution. The obtained aqueous solution was placed in a reactor equipped with a stirrer, and further water was added to make the total amount of the aqueous solution 140 parts.

[0278] The contents were heated to 60°C, and the gas in the reactor was replaced with nitrogen to remove oxygen from the space and the aqueous solution. Then, 0.0002 parts by weight of potassium persulfate was added to the contents. Next, the contents (aqueous solution) were stirred, and a mixture consisting of 72 parts of methyl methacrylate and 8 parts of butyl acrylate was added to the contents over 30 minutes. After the addition of the mixture, the contents were stirred for 5 hours while maintaining the temperature of the contents at 60°C to complete the polymerization reaction. Through the above operations, a (meth)acrylic polymer was formed.

[0279] After the polymerization of the (meth)acrylic polymer was completed, 0.05 parts by weight of potassium persulfate was added to the contents. Then, while stirring the contents, a mixture of 8 parts methyl methacrylate and 12 parts butyl acrylate was continuously added to the contents over 50 minutes to carry out polymerization. After the addition of the mixture was completed, the contents were kept at a temperature of 60°C and the contents were stirred for at least 1 hour to complete the polymerization. This procedure formed a carrier capable of coating at least a portion of the (meth)acrylic polymer. The contents were then cooled to obtain a composite containing the (meth)acrylic polymer and the carrier, i.e., a latex of anti-redeposition agent B7.

[0280] The resulting composite latex was then added to 5 parts of a 1% by weight aqueous solution of calcium chloride at 65°C to coagulate the composite. The composite was then heat-treated, dehydrated, washed, and dried to obtain a composite powder. The weight-average molecular weight of the composite (i.e., anti-redeposition agent B7) was measured using the method described above and found to be 6,000,000.

[0281] <Production Example A2> (Production of anti-redeposition agent B8) 1.0 part of dioctyl sodium sulfosuccinate, 0.0050 parts of ethylenediaminetetraacetic acid disodium salt, and 0.0025 parts of ferrous sulfate were dissolved in water to prepare an aqueous solution. The obtained aqueous solution was placed in a reactor equipped with a stirrer, and further water was added to make the total amount of the aqueous solution 200 parts.

[0282] The gas in the reactor was replaced with nitrogen to remove oxygen from the space and the aqueous solution. Thereafter, while stirring the contents (aqueous solution), 0.4 parts of sodium formaldehyde sulfoxylate was placed in a reactor equipped with a stirrer, and the contents were heated to 75°C. Thereafter, while continuing to stir the contents, a mixture of 12.6 parts of acrylonitrile, 43.4 parts of styrene, 6.0 parts of butyl acrylate, 18.0 parts of methyl methacrylate, 0.8 parts of t-dodecyl mercaptan, and 1 part of t-butyl hydroperoxide was continuously added to the contents over 200 minutes, thereby carrying out polymerization. During the polymerization, 0.3 parts of dioctyl sodium sulfosuccinate was added to the contents twice at predetermined times. During the polymerization, 0.15 parts of sodium formaldehyde sulfoxylate was added to the contents once at predetermined times. A first polymer (e1-1) was formed by the above operations.

[0283] After the polymerization of the first polymer was completed, a mixture of 4 parts butyl acrylate, 16 parts methyl methacrylate, and 0.3 parts t-butyl hydroperoxide was continuously added to the contents over 50 minutes while stirring the contents, and polymerization was carried out. After the addition of the mixture was completed, 0.2 parts of sodium formaldehyde sulfoxylate was added to the contents. Thereafter, the contents were kept at a temperature of 75°C and the contents were stirred for at least 1 hour, thereby completing the polymerization. By the above operation, a second polymer (e1-2) capable of coating at least a portion of the first polymer (e1-1) was formed. Thereafter, the contents were cooled to obtain a composite containing the first polymer (e1-1) and the second polymer (e1-2), i.e., a latex of anti-redeposition agent B8.

[0284] Next, a powder of the composite (i.e., anti-redeposition agent B8) was obtained from the latex of the composite (i.e., anti-redeposition agent B8) by the same method (operation) as in Production Example A1. The weight-average molecular weight of the composite (i.e., anti-redeposition agent B8) was measured by the method described above, and was found to be 40,000.

[0285] Example A1: 100 parts by weight of synthetic resin waste A1 and 20 parts by weight of anti-redeposition agent B1 were placed in a Kawata Super Mixer, a mixer with a rotor, and mixed by rotating the rotor for 15 seconds (anti-redeposition step). The rotation speed was 500 rpm for the entire 15 seconds. The mixture was then separated into synthetic resin and a mixture of non-ferrous metals and anti-redeposition agent using a 10-mesh sieve (first separation step). Furthermore, the mixture of non-ferrous metals and anti-redeposition agent was separated into the non-ferrous metals and anti-redeposition agent using a 60-mesh sieve with smaller mesh openings than the non-ferrous metals (second separation step).

[0286] The synthetic resin after the first separation step and the state of separation after the second separation step were evaluated for separability in accordance with the description in the section <Evaluation of Separability> above. The results are shown in Tables 1, 2, 3, and 4.

[0287] [Examples A2 to A16] The same procedures and evaluations as in Example A1 were carried out, except that the anti-redeposition agent was changed as shown in Tables 1 and 2. The results are shown in Tables 1 and 2. The units of each value in the tables are parts by weight.

[0288] Comparative Example A1 The same operations and evaluations were carried out as in Example A1, except that no anti-redeposition agent was added. The results are shown in Table 2. Note that, since no anti-redeposition agent was used, the second separation step was not carried out.

[0289] [Examples A17 to A32] The same operations and evaluations as in Example A1 were carried out, except that synthetic resin waste A2 was used as the synthetic resin waste and the anti-redeposition agent was changed as shown in Tables 3 and 4. The results are shown in Tables 3 and 4. The units of each value in the tables are parts by weight.

[0290] Comparative Example A2 The same operations and evaluations as in Example A17 were carried out, except that no anti-redeposition agent was added. The results are shown in Table 4. Note that, since no anti-redeposition agent was used, the second separation step was not carried out.

[0291] As is clear from Tables 1, 2, 3 and 4, by treating synthetic resin waste containing non-ferrous metals and synthetic resins using this treatment method, it was shown that the non-ferrous metals and synthetic resins can be separated with good segregation properties.

[0292] Example B (Example According to Second Embodiment) Measurement and Evaluation Methods The measurement and evaluation methods for each physical property measured in Example B are shown below.

[0293] <Weight-average molecular weight of copolymer or composite> This was carried out using the same method as described in the section <Weight-average molecular weight of copolymer or composite> in the section [Measurement and evaluation methods] in the section [Example A (Example according to the first embodiment)]. Therefore, this description is incorporated herein by reference and will not be described again here.

[0294] <Volume average particle diameter> This was performed using the same method as described in the section <Volume average particle diameter> in the section [Measurement and evaluation methods] in the section [Example A (Example according to the first embodiment)]. Therefore, the description therein is incorporated by reference and will not be repeated here.

[0295] <Evaluation of Separability> The synthetic resins separated in the first separation step were visually inspected for adhesion of aluminum pieces to evaluate the separability of the treatment method. Regarding separability, if no aluminum pieces were attached to the synthetic resin, it was rated as "good," and if aluminum pieces were attached, it was rated as "poor."

[0296] [Materials] The materials used in Example B and Comparative Example B are shown below.

[0297] <Synthetic Resin Waste (A)> A3: A mixture obtained as follows. 100 parts by weight of crushed polyvinyl chloride resin sash and 1 part by weight of powdered aluminum (size: 1 mm to 2 mm square, also referred to as aluminum flakes) generated when cutting aluminum were mixed for 30 seconds in a Kawata 10L Super Mixer to obtain a mixture. The obtained mixture (A3) can be regarded as a model product of synthetic resin waste.

[0298] <Anti-redeposition agents (B)> B1: Calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., Whiten SB, volume average particle diameter 2.5 μm) B2: Talc (manufactured by Nippon Talc Co., Ltd., PA-AB, volume average particle diameter 14 μm) B3: Calcium stearate (manufactured by Sakai Chemical Co., Ltd., SC-100, volume average particle diameter 9.8 μm) B4: ABS resin (manufactured by Nippon A&L Co., Ltd., K-2540A, volume average particle diameter 165 μm, powder) B5: AN-α methylstyrene copolymer (manufactured by Kaneka Corporation, Tellalloy, volume average particle diameter 160 μm, powder) B6: Styrene / acrylonitrile copolymer (manufactured by Galata Chemicals, BLENDEX 869, SAN processing aid, weight average molecular weight (Mw) approximately 3 million, volume average particle diameter 120 μm, powder) B7: The anti-redeposition agent obtained in Production Example A1 described above, volume average particle diameter 165 μm, powder. B8: The anti-redeposition agent obtained in Production Example A2 described above, volume average particle diameter 190 μm, powder.

[0299] [Example B1] 100 parts by weight of synthetic resin waste A3 and 20 parts by weight of anti-redeposition agent B1 were added to a Kawata Super Mixer, a mixer with a rotor, and the rotor was rotated and mixed for 15 seconds (anti-redeposition step). The rotation speed was 500 rpm for 15 seconds. Then, using a 10-mesh sieve, the synthetic resin and a mixture of aluminum pieces and anti-redeposition agent were separated (first separation step). Furthermore, the mixture of aluminum pieces and anti-redeposition agent was separated into aluminum pieces and anti-redeposition agent using a 60-mesh sieve with openings smaller than the aluminum pieces (second separation step).

[0300] The synthetic resin after the first separation step and the state of separation after the second separation step were evaluated for separability in accordance with the description in the section <Evaluation of Separability> above. The results are shown in Tables 5 and 6.

[0301] [Examples B2 to B16] The same procedures and evaluations as in Example B1 were carried out, except that the anti-redeposition agent was changed to one shown in Tables 5 and 6. The results are shown in Tables 5 and 6.

[0302] Comparative Example B1 The same operations and evaluations as in Example B1 were carried out, except that no anti-redeposition agent was added. The results are shown in Tables 5 and 6. Since no anti-redeposition agent was used, the second separation step was not carried out.

[0303] Example C (Example According to Third Embodiment) Measurement and Evaluation Methods The measurement and evaluation methods for each physical property measured in Example C are shown below.

[0304] <Weight-average molecular weight of copolymer or composite> This was carried out using the same method as described in the section <Weight-average molecular weight of copolymer or composite> in the section [Measurement and evaluation methods] in the section [Example A (Example according to the first embodiment)]. Therefore, this description is incorporated herein by reference and will not be described again here.

[0305] <Volume average particle diameter> This was performed using the same method as described in the section <Volume average particle diameter> in the section [Measurement and evaluation methods] in the section [Example A (Example according to the first embodiment)]. Therefore, the description therein is incorporated by reference and will not be repeated here.

[0306] <Evaluation of Separability> The separability of the separation method was evaluated by visually checking the synthetic resin separated in the first separation step for adhesion of aluminum pieces. Regarding the separability, when no aluminum pieces were attached to the synthetic resin, it was rated as "good", and when aluminum pieces were attached, it was rated as "poor".

[0307] <Evaluation of Separability> The anti-redeposition agents separated in the second separation step were visually inspected for the presence of aluminum pieces. Cases where no aluminum pieces were present were rated "good," and cases where aluminum pieces were present were rated "poor."

[0308] [Materials] The materials used in Example C and Comparative Example C are shown below.

[0309] <Synthetic Resin Waste (A)> A4: Used PTP sheets made of polyvinyl chloride.

[0310] <Anti-redeposition agent (B)> B1: Calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., Whiten SB, volume average particle diameter 2.5 μm) B2: Talc (manufactured by Nippon Talc Co., Ltd., PA-AB, volume average particle diameter 14 μm) B9: Anti-redeposition agent obtained in Production Example C1 below, volume average particle diameter 150 μm, powder B10: Anti-redeposition agent obtained in Production Example C2 below, volume average particle diameter 160 μm, powder B6: Styrene / acrylonitrile copolymer (manufactured by Galata Chemicals, BLENDEX 869, SAN processing aid, weight average molecular weight (Mw) approximately 3 million, volume average particle diameter 120 μm, powder) B11: Anti-redeposition agent obtained in Production Example C3 below, volume average particle diameter 160 μm, powder.

[0311] <Other additives> External lubricant: special fatty acid ester (manufactured by Riken Vitamin Co., Ltd., SL-02) Internal lubricant: fatty acid ester (manufactured by EMERY OLEOCHEMICALS, Loxiol G32).

[0312] [Production Example C] <Production Example C1> (Production of Anti-Redeposition Agent B9) 100 parts by weight of polyvinyl chloride resin (PVC) (Kaneka Corporation, S-1008, degree of polymerization 800, polyvinyl chloride resin containing 100% by weight of vinyl chloride units in 100% by weight of resin), 1 part by weight of octyltin mercapto (Nitto Kasei Kogyo Co., Ltd., TVS#8831) as a stabilizer, 0.25 parts by weight of special fatty acid ester (Riken Vitamin Co., Ltd., SL-02) as an external lubricant, and 0.3 parts by weight of fatty acid ester (EMERY OLEOCHEMICALS, Loxiol G32) as an internal lubricant were charged into a super mixer. The charged raw materials were heated to 120°C and mixed to obtain a powder, i.e., anti-redeposition agent B9.

[0313] <Production Example C2> (Production of anti-redeposition agent B10) 3.0 parts of sodium palmitate, 0.01 parts of ethylenediaminetetraacetic acid disodium salt, and 0.0025 parts of ferrous sulfate were dissolved in water to prepare an aqueous solution. The obtained aqueous solution was placed in a reactor equipped with a stirrer, and further water was added to make the total amount of the aqueous solution 250 parts.

[0314] The gas in the reactor was replaced with nitrogen to remove oxygen from the space and the aqueous solution. Thereafter, while stirring the contents (aqueous solution), 0.4 parts of sodium formaldehyde sulfoxylate was placed in a reactor equipped with a stirrer, and the contents were heated to 60°C. Thereafter, 63 parts of α-methylstyrene, 27 parts of acrylonitrile, 0.27 parts of tertiary dodecyl mercaptan, and 0.27 parts of cumene hydroperoxide were continuously added dropwise to the contents over a period of 6 hours. After completion of the dropwise addition, stirring of the contents was continued for 1 hour while maintaining the temperature of the contents at 60°C. Through the above operations, anti-redeposition agent B10 was formed, and anti-redeposition agent B10 in the form of a powder was obtained.

[0315] <Production Example C3> (Production of anti-redeposition agent B11) 0.5 parts of sodium dioctyl succinate was dissolved in water to prepare an aqueous solution. The obtained aqueous solution was placed in a reactor equipped with a stirrer, and further water was added to make the total amount of the aqueous solution 140 parts.

[0316] The contents were heated to 60°C, and the gas in the reactor was replaced with nitrogen to remove oxygen from the space and the aqueous solution. Then, 0.0005 parts by weight of potassium persulfate was added to the contents. Next, the contents (aqueous solution) were stirred, and a mixture consisting of 72 parts of methyl methacrylate and 8 parts of butyl acrylate was added to the contents over 30 minutes. After the addition of the mixture, the contents were stirred for 5 hours while maintaining the temperature of the contents at 60°C to complete the polymerization reaction. Through the above operations, a (meth)acrylic polymer was formed.

[0317] After the polymerization of the (meth)acrylic polymer was completed, 0.05 parts by weight of potassium persulfate was added to the contents. Then, while stirring the contents, a mixture of 8 parts methyl methacrylate and 12 parts butyl acrylate was continuously added to the contents over 50 minutes to carry out polymerization. After the addition of the mixture was completed, the contents were kept at a temperature of 60°C and the contents were stirred for at least 1 hour to complete the polymerization. This procedure formed a carrier capable of coating at least a portion of the (meth)acrylic polymer. The contents were then cooled to obtain a composite containing the (meth)acrylic polymer and the carrier, i.e., a latex of antiredeposition agent B11.

[0318] The resulting composite latex was then added to 5 parts of a calcium chloride aqueous solution diluted to a concentration of 1% by weight at 65°C to coagulate the composite. The composite was then heat-treated, dehydrated, washed, and dried to obtain a composite powder. The weight-average molecular weight of the composite (i.e., anti-redeposition agent B11) was measured by the method described above and found to be 4,500,000.

[0319] [Example C1] Synthetic resin waste A4 was placed in a Kawata Super Mixer, a mixer with a rotor, and the rotor was rotated while the temperature inside the mixer was maintained at 100°C (separation step). The rotor was temporarily stopped during the separation step, and 20 parts by weight of anti-redeposition agent B1 was added per 100 parts by weight of synthetic resin waste A4, and the rotor was rotated for another 3 minutes (anti-adhesion step). Then, using a 10-mesh sieve, the synthetic resin polyvinyl chloride was separated from a mixture of aluminum pieces and anti-redeposition agent (first separation step). Furthermore, the mixture of aluminum pieces and anti-redeposition agent was separated into aluminum pieces and anti-redeposition agent using a 60-mesh sieve with openings smaller than the aluminum pieces (second separation step).

[0320] [Examples C2 to C6] The synthetic resin, aluminum pieces, and anti-redeposition agent were separated in the same manner as in Example C1, except that the anti-redeposition agent was changed to one shown in Table 7.

[0321] [Examples C7 to C12] The synthetic resin, aluminum pieces, and anti-redeposition agent were separated in the same manner as in Example C1, except that the anti-redeposition agent was changed to one shown in Table 8 and 0.2 parts by weight of the external lubricant or internal lubricant was added per 100 parts by weight of the PTP sheet.

[0322] Example C13 The synthetic resin, aluminum pieces, and anti-redeposition agent were separated in the same manner as in Example C4, except that the anti-redeposition agent was introduced into the mixer together with the synthetic resin waste in the separation step.

[0323] Example C14 The synthetic resin, aluminum pieces, and anti-redeposition agent were separated in the same manner as in Example C7, except that the anti-redeposition agent was introduced into the mixer together with the synthetic resin waste in the separation step.

[0324] Example C15 The synthetic resin, aluminum pieces, and anti-redeposition agent were separated in the same manner as in Example C8, except that the anti-redeposition agent was introduced into the mixer together with the synthetic resin waste in the separation step.

[0325] [Example C16] The synthetic resin, aluminum pieces, and anti-redeposition agent were separated in the same manner as in Example C1, except that the anti-redeposition agents were 10 parts by weight of anti-redeposition agent B9 and 10 parts by weight of anti-redeposition agent B11 per 100 parts by weight of synthetic resin waste A4.

[0326] [Comparative Example C1] A polyvinyl chloride PTP sheet with aluminum foil and synthetic resin attached was placed in a Kawata Super Mixer, and the rotor was rotated while the temperature inside the mixer was heated to 100° C. Then, using a 10-mesh sieve, the polyvinyl chloride synthetic resin and aluminum pieces were separated.

[0327] For Examples C1 to C16 and Comparative Example C1, evaluations of separability and separability were carried out in accordance with the descriptions in the sections <Evaluation of Separability> and <Evaluation of Separability> above. The results are shown in Tables 7, 8, and 9.

[0328] According to one embodiment of the present invention, a method for treating synthetic resin waste can be provided that allows for excellent separation of non-ferrous metals and synthetic resins. Therefore, this embodiment of the present invention can be suitably used in fields such as composite materials of non-ferrous metals and synthetic resins, such as sashes or PTPs, food containers, packaging containers, and moisture-proof packaging containers, including resin sashes (exterior windows), resin sashes (interior windows), resin-non-ferrous metal composite sashes, and recycled resin sashes.

Claims

1. A method for treating synthetic resin waste, comprising an anti-redeposition step of feeding synthetic resin waste containing non-ferrous metals and synthetic resins and an anti-redeposition agent into a mixer having a rotor and rotating the rotor.

2. The method for treating synthetic resin waste according to claim 1, wherein the non-ferrous metals include aluminum.

3. The method for treating synthetic resin waste according to claim 1, further comprising a thermal separation step of separating the non-ferrous metals and the synthetic resins by heating.

4. The method for treating synthetic resin waste according to claim 3, wherein the heating temperature in the thermal separation step is 65°C or higher and 130°C or lower.

5. A method for treating synthetic resin waste as described in claim 1, further comprising a first separation step of separating the mixture of the synthetic resin, the non-ferrous metal, and the anti-redeposition agent obtained in the anti-adhesion step into the synthetic resin and the mixture of the non-ferrous metal and the anti-redeposition agent.

6. A method for treating synthetic resin waste as described in claim 5, further comprising a second separation step of separating the mixture of non-ferrous metals and the anti-redeposition agent obtained in the first separation step into the non-ferrous metals and the anti-redeposition agent.

7. The method for treating synthetic resin waste according to claim 1, wherein water is not used in the adhesion prevention step.

8. The method for treating synthetic resin waste according to claim 1, wherein the anti-redeposition agent comprises one or more selected from the group consisting of polyvinyl chloride resin, a copolymer containing an α-methylstyrene unit, an acrylic polymer, a styrene / acrylonitrile copolymer, an acrylonitrile / butadiene / styrene copolymer, an inorganic filler, a metal soap, and wax.

9. A method for treating synthetic resin waste according to claim 1, wherein the volume average particle diameter of the anti-redeposition agent is 1 μm or more and 1000 μm or less.

10. A method for treating synthetic resin waste as described in claim 1, wherein in the adhesion prevention step, the anti-redeposition agent is mixed in an amount of 1 part by weight to 50 parts by weight per 100 parts by weight of synthetic resin waste.

11. A method for treating synthetic resin waste as described in claim 1, wherein the diameter of the non-ferrous metal is 0.63 mm or more and 3.00 mm or less, and the diameter of the non-ferrous metal is the diameter of the smallest sphere among those that contain the entire non-ferrous metal inside and are in contact with the non-ferrous metal at at least two points.

12. The method for treating synthetic resin waste according to claim 1, wherein the anti-redeposition agent is a recycled anti-redeposition agent.

13. A method for producing recycled synthetic resins, comprising the method for treating synthetic resin waste according to any one of claims 1 to 12 as one step.

14. A recycled synthetic resin obtained by a method for producing recycled synthetic resin, which method includes, as one step, the method for treating synthetic resin waste according to any one of claims 1 to 12.

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