Method for recycling material including polyester

Abstract

To provide a method for recycling a material including polyester by a novel means.SOLUTION: A method for recycling a material including polyester includes: subjecting a material including polyester to alcoholysis in a solvent in the presence of a catalyst and alcohol; and separating an alcoholysis product obtained in the previous step. Specifically, the method is implemented using an apparatus that includes a tank for storing the material including polyester, and a tank and / or a path for separating the alcoholysis product of polyester.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for recycling materials containing polyester. [Background technology]

[0002] Plastics are inexpensive and durable materials. In particular, polyethylene terephthalate (PET) is used in a wide range of fields, including fibers, films, and bottles, due to its convenience, and its production and consumption have increased dramatically over the past few decades. However, while it is durable, it is not easily decomposable, which has led to the filling of landfills around the world and the destruction of the global environment, including marine pollution caused by microplastics. In light of this, there is a need to develop recycling technology for PET and other plastic waste. In Japan, compared to Europe and the United States, the proportion of thermal recycling, which utilizes the thermal energy generated during incineration, is high, but there are concerns about global warming due to carbon dioxide emissions. Therefore, much research has been conducted on chemical recycling of polyester waste, that is, methods of chemically converting polyester waste into monomers, recovering them, and reusing these monomers.

[0003] Patent Document 1 discloses a method for continuously producing aromatic dimethyl dicarboxylate and dihydric alcohol, which are monomer components of aromatic polyester such as PET, by using supercritical alcohol, but requires high temperatures of 300°C or higher. Patent Document 2 discloses a method for producing dimethyl terephthalate by depolymerizing polyester with alkylene glycol and then transesterifying it with methanol, but the alkylene glycol needs to be distilled off at 150° C. or higher. Patent Document 3 discloses a method for recycling a multilayer film including a plastic layer mainly composed of polyester (PET), polypropylene (PP) and polyethylene (PE) and an aluminum layer. In this invention, aluminum in the multilayer film waste is selectively dissolved to induce layer separation, and the layer is separated into a mixture layer of PP and PE and a PET layer using the difference in specific gravity. In addition, in order to increase the purity of the PET separated by the difference in specific gravity, an organic solvent is used to extract the PP and PE contained in the PET layer, thereby separating the main components of the multilayer film into PET, a mixture of PP and PE, and an aluminum component. However, since aluminum is dissolved, energy is required for recycling. Patent Document 4 discloses a catalyst composition for depolymerizing polyesters, which contains a base catalyst, a monohydric alcohol, and a diester carbonate or tetraalkoxysilane as a glycol scavenger, and a method for depolymerizing polyesters using the catalyst composition. However, because ethylene glycol, a component of PET, is stably captured, it becomes necessary to decompose the generated ethylene carbonate into ethylene glycol in order to reuse it as a raw material for PET. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-039908 A [Patent Document 2] JP 2012-131729 A [Patent Document 3] JP 2006-205160 A [Patent Document 4] JP 2022-126617 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in order to overcome the above-mentioned problems of the conventional technology, and an object of the present invention is to provide a method for recycling polyester-containing materials by a new means. [Means for solving the problem]

[0006] As a result of intensive research to solve the above problems, the present inventors have found a method for recycling a polyester-containing material, which comprises the steps of alcoholyzing a polyester-containing material in a solvent in the presence of a catalyst and an alcohol, and separating the alcoholysis product obtained in the above step. More specifically, the present inventors have found a method for recycling a polyester-containing material, which is characterized by using an apparatus having a tank for storing the polyester-containing material and a tank and / or a path for separating the alcoholysis product of the polyester, and have completed the present invention.

[0007] The polyester-containing substance (a) may be a polyester resin product as described below, may contain a polyester component, or may be in the form of a laminate in which multiple films are laminated. The present invention can be applied to various polyesters as described below, and is not particularly limited. One example is polyethylene terephthalate. As the catalyst (b), various metal salts and nitrogen-containing organic base compounds can be used as described later, and are not particularly limited, but for example, at least one selected from the group consisting of alkali metal alkoxides and nitrogen-containing organic base compounds can be selected for implementation. More specifically, sodium methoxide and / or 1,5,7-triazabicyclo[4.4.0]dec-5-ene can be mentioned as an example. As for the alcohol (c), at least one of various types can be selected as described later, and there is no particular limitation. However, it is preferably a monohydric alcohol having 1 to 8 carbon atoms, and methanol can be given as a simple example. As described later, the solvent (d) is not particularly limited, but from the viewpoint of recycling, those which react with the alcoholysis product in the reaction system are excluded. For example, at least one can be selected from the group of compounds that do not react with the alcoholysis product in the alcoholysis reaction system, and toluene can be given as a specific example.

[0008] The present invention can also be practiced as a recycling method comprising step (A) of alcoholysing a polyester-containing substance (a) in a solvent (d) in the presence of a catalyst (b) and an alcohol (c), and, in addition to step (B) of separating the alcoholysis product obtained in step (A), adding a step (C) of separating substances other than the alcoholysis product obtained in step (A).

[0009] The present invention provides a new means for recycling materials containing polyester. Furthermore, by carrying out the present invention, materials containing polyester can be recycled without being incinerated or otherwise disposed of, which can contribute to reducing carbon dioxide emissions. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a structural diagram of an apparatus for implementing the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The method of recycling the polyester-containing material (a) by alcoholysis in the present invention is carried out in a solvent (d) containing a catalyst (b) and an alcohol (c). The blending ratio of these components can be appropriately changed within the range in which the alcoholysis proceeds well. Each component used in the present invention will be described in detail below. Note that the raw materials exemplified in the following description do not limit the configuration of the present invention, and may be modified within the scope of the present invention.

[0012] Substances containing polyester (a) The polyester-containing material (a) of the present invention includes, as one embodiment, a polyester resin product. Representative polyester resin products include polyethylene terephthalate (PET), amorphous polyethylene terephthalate (A-PET), glycol-modified polyethylene terephthalate (G-PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polyarylate (PAR), polycaprolactone (PCL), polylactic acid (PLA), polyethylene adipate (PEA), and the like. These polyester resin products may be used alone or in combination of two or more.

[0013] The polyester-containing material (a) of the present invention may, in another embodiment, contain a polyester component, and includes food trays, fibers, adhesives, pressure sensitive adhesives, inks, coatings, etc. For example, it may be a mixture of a polyester component and other components such as cotton, acrylic, rayon, etc., such as a blended fiber, or it may be a mixture of dyes, pigments, etc. In addition, some of the components may be chemically modified. Examples of polyester-based adhesives for lamination include polyester polyurethane, polyester polyether, polyester polyether polyurethane, etc.

[0014] The polyester-containing material (a) of the present invention also includes, as another embodiment, a laminate in which a plurality of films are laminated. There is no particular limitation on the films that can be used, and examples of the films that can be used include polyester films such as PET; olefin films such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), biaxially oriented polypropylene (OPP), and non-oriented polypropylene (CPP); metal films such as aluminum foil; nylon films; polyvinyl alcohol (PVA) films; cellulose films; acrylic films; polyphenylsulfide (PPS) films; polyimide (PI) films; vinyl chloride films; fluororesin films such as PTFE; and paper films. These may be films on which a vapor deposition layer is formed. Also, they may be colored films. In the case where the polyester-containing substance (a) of the present invention is a laminate containing a polyester film, the polyester film is separated from other laminate films by alcoholysis, and thus recycling can be promoted. Even in the case of a laminate not containing a polyester film, if the laminate is bonded with a polyester-based adhesive, the adhesive component is alcoholysed, and thus the films bonded with the adhesive are separated, and thus recycling can be promoted.

[0015] The polyester-containing substance (a) can take various forms depending on the embodiment. For example, it can be used in a solid state such as a lump, fiber, film, pellet, etc. It can also be used in a liquid state.

[0016] Catalyst (b) As the catalyst (b) of the present invention, a metal salt or a nitrogen-containing organic base compound can be used.

[0017] As the metal salt, hydroxides, carbonates, fatty acid salts, and alkoxides of alkali metals; hydroxides, carbonates, fatty acid salts, alkoxides, and oxides of alkaline earth metals; and hydroxides, carbonates, fatty acid salts, and alkoxides of transition metals can be used. In particular, it is preferable to use alkali metal alkoxides. These catalysts may be used alone or in combination of two or more.

[0018] Examples of alkali metal alkoxides include lithium methoxide, lithium ethoxide, lithium tert-butoxide, sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium methoxide, potassium ethoxide, and potassium tert-butoxide. Of these, it is particularly preferable to use sodium methoxide.

[0019] Examples of the nitrogen-containing organic base compound include trimethylamine, triethylamine, tributylamine, pyrazole, imidazole, N-methylimidazole, benzimidazole, N-methylbenzimidazole, triazoles, benzotriazole, pyridine, quinoline, isoquinoline, triazines, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 1,8-azabicyclo[5.4.0]undec-7-ene (DBU), and 1,3-dimesitylimidazol-2-ylidene. Among these, it is particularly preferable to use TBD.

[0020] The amount of catalyst (b) added is preferably 0.1 parts by weight to 200 parts by weight, more preferably 1 part by weight to 100 parts by weight, and even more preferably 3 parts by weight to 80 parts by weight, relative to 100 parts by weight of the polyester component in polyester-containing substance (a). The amount of catalyst (b) added should be adjusted within the range in which alcoholysis proceeds. If too much is added, not only will costs increase, but purification of the alcoholysis product will become more time-consuming. If too little is added, the catalyst may be deactivated, and alcoholysis may not proceed sufficiently.

[0021] Alcohol (c) The alcohol (c) of the present invention is not particularly limited, but is preferably a monohydric alcohol having 1 to 8 carbon atoms.

[0022] Examples of monohydric alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 2-ethylhexanol, and benzyl alcohol. These may be used alone or in combination of two or more. Among these, primary alcohols are preferred, and methanol is particularly preferred.

[0023] The amount of the alcohol (c) added is preferably 10 parts by weight or more and 1000 parts by weight or less, more preferably 20 parts by weight or more and 800 parts by weight or less, and even more preferably 30 parts by weight or more and 600 parts by weight or less, relative to 100 parts by weight of the polyester component in the polyester-containing substance (a). The amount of alcohol (c) added should be adjusted within the range in which alcoholysis proceeds. If too much is added, costs will increase. If too little is added, alcoholysis will not proceed sufficiently. If too little is added, alcoholysis will proceed again by adding more alcohol (c).

[0024] Solvent (d) The solvent (d) of the present invention excludes those which react with the alcoholysis product in the alcoholysis reaction system. For example, in the alcoholysis of polyethylene terephthalate, if dimethyl carbonate is selected as the solvent, ethylene glycol produced by the alcoholysis of polyethylene terephthalate reacts with dimethyl carbonate to convert to ethylene carbonate, which is not suitable as a solvent from the viewpoint of recycling. In addition, when considering the reuse of the solvent, if the boiling point is too high, a lot of heat energy is required for the distillation operation, so the boiling point is preferably 200°C or less, more preferably 150°C or less, and even more preferably 120°C or less. Examples of such a solvent include toluene, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, n-hexane, cyclohexane, 1,2-dichloromethane, tetrahydrofuran, methyl ethyl ketone, and ethyl acetate. These can be appropriately selected as long as they do not inhibit alcoholysis, and may be used alone or in combination of two or more.

[0025] The ratio of the solvent (d) in the present invention can be adjusted appropriately according to the weight and shape of the polyester-containing substance (a). If the ratio is too high, the reaction apparatus becomes large, and as a result, the processing capacity of the polyester-containing substance (a) decreases. If the ratio is too low, the contact between the catalyst (b), the alcohol (c) and the polyester-containing substance (a) becomes poor, and the alcoholysis does not proceed easily.

[0026] Other ingredients (e) In addition to the above (a) to (d), other components such as a drying agent and a substance not involved in alcoholysis may be included. These do not limit the configuration of the present invention, and may be added appropriately within the scope of the present invention.

[0027] Desiccant Desiccants include physical desiccants and chemical desiccants. These desiccants may be used alone or in combination of two or more.

[0028] Physical desiccants include those that utilize the increased water and / or moisture transfer path due to the matrix structure inside the desiccant, and those that utilize physical interactions with the desiccant, such as adsorption of water and / or moisture. Specific examples include silica gel, molecular sieves, zeolite, activated carbon, etc.

[0029] Some chemical desiccants use a chemical reaction to adsorb moisture and / or humidity. Specific examples of chemical desiccants include metal oxides such as calcium oxide, barium oxide, and magnesium oxide; metal salts such as sodium sulfate, calcium sulfate, magnesium sulfate, calcium chloride, and magnesium chloride; diphosphorus pentoxide; silane compounds such as vinyltrimethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, diphenyldimethoxysilane, and phenyltrimethoxysilane; and orthoester compounds such as methyl orthoformate, ethyl orthoformate, methyl orthoacetate, and ethyl orthoacetate. However, those that react with the alcoholysis product are excluded from the viewpoint of recycling.

[0030] Substances not involved in alcoholysis In the present invention, a substance that is not involved in alcoholysis may be contained. For example, olefin films such as low density polyethylene (LDPE), high density polyethylene (HDPE), biaxially oriented polypropylene (OPP), and non-oriented polypropylene (CPP); metal films such as aluminum foil; nylon films; and fluororesin films such as PTFE. These films may be films on which a vapor deposition layer is formed. Also, they may be colored films. Further examples include paper, polystyrene (PS) sheets, table salt, and the like.

[0031] The alcoholysis in the present invention preferably proceeds at a temperature of 20° C. or higher but lower than 100° C., preferably 30° C. or higher but lower than 90° C., and more preferably 40° C. or higher but lower than 80° C. If the temperature is lower than 20° C., the catalytic activity is insufficient. Although the alcoholysis proceeds at a temperature of 100° C. or higher, this is not preferable from the viewpoint of energy costs.

[0032] The alcoholysis of the present invention can be carried out under normal pressure or reduced pressure, but may also be carried out under increased pressure. The reaction time may be the time required for the polyester-containing substance (a) to undergo alcoholysis, and may be, for example, 0.5 to 24 hours. The alcoholysis may not be allowed to proceed completely, and the reaction may be shifted to a product separation step at an intermediate stage.

[0033] Process (A) The process (A) of the present invention in which a polyester-containing substance (a) is subjected to alcoholysis in a solvent (d) in the presence of a catalyst (b) and an alcohol (c) will be described in detail below using a laminate of multiple different films including a PET film as an example. A polyester-containing laminate (a), a catalyst (b), an alcohol (c), and a solvent (d) are placed in a reaction vessel and heated with stirring. At this time, terephthalic acid derivatives and ethylene glycol (hereinafter defined as "alcoholization products") are obtained by alcoholysis. Meanwhile, PET residues, catalyst residues, and films other than PET that have not been alcoholyzed (hereinafter defined as "substances other than alcoholysis products") are also present in the reaction vessel.

[0034] Process (B) Step (B) of separating the alcoholysis product obtained in step (A) will now be described. When the alcoholysis product obtained in the step (A) is in a solid state, it can be separated by normal filtration or hot filtration. The filter used for the filtration operation is not particularly limited, and the size and material can be appropriately selected depending on the target. When the alcoholysis product obtained in the step (A) is in a liquid state, it cannot be separated by a filtration operation, and therefore it can be separated, for example, by a method of concentration and recrystallization or a method of extraction, but is not limited to these methods.

[0035] Process (C) In addition to the step (B), a step of separating substances other than the alcoholysis product may be included. The separation operation can be carried out using known techniques in the same manner as in step (B) above.

[0036] Apparatus embodiment Next, referring to FIG. 1, one embodiment of an apparatus having a tank 1 (X) and a tank 2 and / or a path 10 (Y) will be described, although the apparatus can be implemented in various forms.

[0037] A polyester-containing substance (a) is placed in tank 1 (X) surrounded by a filter or the like that does not allow any solids to pass through, and a catalyst (b), an alcohol (c), and a solvent (d) are placed in tank 2 and / or path 10 (Y), and (a) to (d) are mixed so that they come into contact with each other. Here, the polyester-containing substance (a) in tank 1 cannot pass through the filter surrounding tank 1, but as alcoholysis progresses, the structure is such that only the alcoholysis product dissolved in the reaction solution can pass through tank 1. A heater 4 may be placed in tank 2 as necessary to adjust the reaction temperature.

[0038] Examples of mixing methods include stirring with a ceramic rotor, mechanical stirring with a stirring blade, mixing by circulation, etc. In the example of Figure 1, an example of stirring with a stirring blade 5 at the tip of a rotating shaft connected to a motor 3 is shown. The liquid in the tank 2 and the liquid in a path 10 connected to the tank 2 are circulated by a pump 9 placed in the middle of the path, and in this example, a valve 6 for adjusting the flow rate, a pressure gauge 7, and a filtration device 8 are placed in parallel in the path 10. The materials of the equipment used for recycling, such as the tank 1 (X), the tank 2 and / or the path 10 (Y), can be appropriately selected as long as they do not impede the recycling.

[0039] The progress of alcoholysis can be evaluated based on the alcoholysis rate A according to the following formula (1). Alcoholization rate A [%] = (1 - weight of (a) after alcoholization / weight of (a) before alcoholization) × 100 (Equation 1)

[0040] In the following examples, the evaluation results are shown according to the following criteria. Alcohololysis rate A is 90% or more: ◎ Alcohololysis rate A is 60% or more but less than 90%: 〇 Alcohololysis rate A is 30% or more but less than 60%: △ Alcohololysis rate A is less than 30%: × EXAMPLES

[0041] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0042] In the examples shown below, the following reagents were used unless otherwise specified. Substances containing polyester (a) ·PET pellets (commercially available) Polyester polyurethane laminating adhesive (manufactured by Rock Paint Co., Ltd., Adlock RU-77 / H-7), hereafter abbreviated as "polyester adhesive" Polyether polyurethane laminating adhesive (manufactured by Rock Paint Co., Ltd., Adlock RN-230 / HN-230), hereafter abbreviated as "polyether adhesive" Catalyst (b) Sodium methoxide (Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1) 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (Tokyo Chemical Industry Co., Ltd.) Alcohol (c) Methanol (Fujifilm Wako Pure Chemical Industries, ultra-dehydrated grade) Solvent (d) Toluene (Kanto Chemical Co., Ltd., special grade) film ·PET film (Toyobo Co., Ltd., Toyobo Ester Film E5102) OPP film (Toyobo Co., Ltd., Pylen Film-OT P2241) CPP film (Toyobo Co., Ltd., Pylen Film-CT P1146) Nylon film (manufactured by Unitika Ltd., Emblem ONBC-RT) Aluminum foil (manufactured by Toyo Aluminum Co., Ltd.) Filters · Mesh size 0.5mm, stainless steel

[0043] [Example 1] Sodium methoxide (1 part by weight) and methanol (2 parts by weight) were added to a reaction vessel containing PET pellets (6 parts by weight). Toluene was added so that the total amount became 100 parts by weight, and the mixture was stirred at 65° C. for 2 hours. After the reaction was completed, the reaction solution was filtered through a filter, and the filtration residue was washed with water. No unreacted PET pellets were obtained as the filtration residue. The alcoholysis rate was 100%.

[0044] [Example 2] The same procedure was carried out under the conditions of Example 1, except that the amount of sodium methoxide was reduced to 0.3 parts by weight. The alcoholysis rate was 100%.

[0045] [Example 3] The same procedure was carried out under the conditions of Example 1, except that the amount of sodium methoxide was increased to 4 parts by weight. The alcoholysis rate was 100%.

[0046] [Example 4] The same procedure was carried out under the conditions of Example 1, except that the amount of methanol was increased to 40 parts by weight. The alcoholysis rate was 84.1%.

[0047] [Example 5] The same experiment was carried out under the conditions of Example 1, except that the PET pellets were replaced with white PET film (manufactured by Toyobo Co., Ltd., Toyobo Ester Film E-5102 printed with white ink). The alcoholysis rate was 95.9%.

[0048] [Example 6] The same experiment was carried out under the conditions of Example 1, except that the PET pellets were replaced with an alumina transparent vapor-deposited PET film (Barrierox 1011SBR2, manufactured by Toray Advanced Film Co., Ltd.) The alcoholysis rate was 100%.

[0049] [Example 7] The same experiment was carried out under the conditions of Example 1, except that the PET pellets were replaced with polyester fiber (King High Span button thread, manufactured by Fujix Co., Ltd.). The alcoholysis rate was 90.0%.

[0050] [Example 8] The same experiment was carried out under the conditions of Example 1, except that the PET pellets were replaced with an aliphatic polyester resin (Adlock RU-10, manufactured by Rock Paint Co., Ltd.). The alcoholysis rate was 100%. In addition, since the polyester resin used here was dissolved in the reaction solution and could not be isolated by filtration, after the reaction was completed, the reaction solution was isolated and characterized by GPC (gel permeation chromatography) to confirm that no unalcoholized polyester resin was found.

[0051] [Example 9] The same procedure was carried out under the conditions of Example 1, except that the PET pellets were replaced with a resin prepared by grinding and mixing an epoxy resin (Mitsubishi Chemical Group Corporation, jER1055K, 35 parts by weight) and a polyester resin (Daicel-Allnex Corporation, CRYLCOAT1713, 65 parts by weight) and thermally crosslinking the resin at 160°C for 20 minutes. The alcoholysis rate was 45.8%.

[0052] [Example 10] The same experiment was carried out under the conditions of Example 1, except that the PET pellets were replaced with Eco A-PET film (a commercially available product). The alcoholysis rate was 100%.

[0053] [Example 11] The same experiment was carried out under the conditions of Example 1, except that the PET pellets were replaced with G-PET flakes (commercially available product). The alcoholysis rate was 83.2%.

[0054] [Example 12] The same procedure was carried out under the conditions of Example 1, except that sodium methoxide was replaced with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (1 part by weight). The alcoholysis rate was 93.3%.

[0055] [Table 1]

[0056] [Table 2]

[0057] [Example 13] The same procedure was carried out under the conditions of Example 1, except that methanol was replaced with benzyl alcohol (Tokyo Chemical Industry Co., Ltd., 6.75 parts by weight). The alcoholysis rate was 93.0%.

[0058] [Example 14] The same procedure was carried out under the conditions of Example 1, except that methanol was replaced with ethanol (Fujifilm Wako Pure Chemical Industries, Ltd., ultra-dehydrated grade, 3 parts by weight) and toluene was replaced with ethyl acetate (Kanto Chemical Industries, Ltd., special grade). The alcoholysis rate was 98.5%.

[0059] [Example 15] The same procedure was carried out under the conditions of Example 1, except that toluene was replaced with acetonitrile (special grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). The alcoholysis rate was 99.7%.

[0060] [Example 16] The same procedure was carried out under the conditions of Example 1, except that toluene was replaced with tetrahydrofuran (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., ultra-dehydrated grade (containing stabilizer)). The alcoholysis rate was 94.0%.

[0061] [Example 17] The same procedure was carried out under the conditions of Example 1, except that OPP film (6 parts by weight) was added. The reaction solution was filtered through a filter, and the unreacted PET pellets and OPP film were separated from the resulting filtration residue, and the unreacted PET pellets were recovered. The alcoholysis rate was 99.7%.

[0062] [Example 18] The same procedure was carried out under the conditions of Example 1, except that nylon film (6 parts by weight) was added. The reaction solution was filtered through a filter, and the unreacted PET pellets and nylon film were separated from the resulting filtration residue, and the unreacted PET pellets were recovered. The alcoholysis rate was 97.9%.

[0063] [Example 19] The same procedure was carried out under the conditions of Example 1, except that aluminum foil (6 parts by weight) was added. The reaction solution was filtered through a filter, and the filtration residue obtained was aluminum foil, and no unreacted PET pellets were obtained. The alcoholysis rate was 100%.

[0064] [Comparative Example 1] The same procedure was carried out under the conditions of Example 1, except that sodium methoxide was replaced with sodium hydroxide (Kanto Chemical Co., Ltd., Grade 1 Sika, 1 part by weight). The alcoholysis rate was 16.2%.

[0065] [Comparative Example 2] The same procedure was carried out under the conditions of Example 1, except that methanol was replaced with ethylene glycol (Fujifilm Wako Pure Chemical Industries, Ltd., dehydrated grade, 4 parts by weight). The alcoholysis rate was 0%.

[0066] [Comparative Example 3] The same procedure was carried out, but without adding methanol, under the conditions of Example 1. The alcoholysis rate was 0%.

[0067] Next, alcoholysis was examined when a laminate film having the composition shown in Table 3 was used as the polyester-containing substance (a). Here, the separation rate B was evaluated based on the following formula 2. Separation rate B [%] = (1 - weight of unseparated laminate film after alcoholysis / weight of laminate film before alcoholysis) × 100 (Equation 2) Separation rate B is 90% or more: ◎ Separation rate B is 60% or more but less than 90%: 〇 Separation rate B is 30% or more but less than 60%: △ Separation rate B is less than 30%: ×

[0068] [Example 20] A laminate film (6 parts by weight) consisting of a PET film / polyester adhesive / OPP film was placed in a reaction vessel, and sodium methoxide (1 part by weight) and methanol (2 parts by weight) were added. Toluene was added so that the total amount became 100 parts by weight, and the mixture was shaken at 25°C for 4 hours using a paint shaker (manufactured by Asada Iron Works). After the reaction was completed, the reaction solution was filtered and the filter residue was washed with water, but no unseparated laminate film was recovered. The separation rate was 100%.

[0069] [Example 21] The same experiment was carried out under the conditions of Example 20, except that the laminate film configuration was changed to PET film / polyester adhesive / CPP film. The separation rate was 100%.

[0070] [Example 22] The same experiment was carried out under the conditions of Example 20, except that the laminate film configuration was changed to PET film / polyester adhesive / nylon film. The separation rate was 100%.

[0071] [Example 23] The same procedure was carried out under the conditions of Example 20, except that the laminate film was changed to PET film / polyester adhesive / aluminum foil. The separation rate was 100%. At the end of the reaction, the aluminum foil did not dissolve and the shape of the film was maintained.

[0072] [Example 24] The same experiment was carried out under the conditions of Example 20, except that the laminate film configuration was changed to nylon film / polyester adhesive / aluminum foil. The separation rate was 100%. At the end of the reaction, the aluminum foil was not dissolved and maintained the shape of a film.

[0073] [Example 25] The same experiment was carried out under the conditions of Example 20, except that the laminate film configuration was changed to PET film / polyester adhesive / nylon film / polyester adhesive / aluminum foil. The separation rate was 100%. At the end of the reaction, the aluminum foil was not dissolved and maintained the shape of a film.

[0074] [Example 26] The same experiment was carried out under the conditions of Example 20, except that the laminate film configuration was changed to PET film / polyether adhesive / nylon film. The separation rate was 94.0%.

[0075] [Example 27] The same experiment was carried out under the conditions of Example 20, using a PET egg carton with a paper label instead of the laminate film. The separation rate was 100%.

[0076] [Example 28] The same experiment was carried out under the conditions of Example 20, except that a blend of 65% polyester and 35% cotton was used instead of the laminate film. The separation rate was 34.5%.

[0077] [Comparative Example 4] The same experiment was carried out under the conditions of Example 20, except that the laminate film configuration was changed to OPP film / polyether adhesive / CPP film. The separation rate was 0%.

[0078] [Table 3] [Explanation of symbols]

[0079] 1 tank 2 tanks 3 Motor 4. Heater 5 Mixing blade 6 Valves 7. Pressure Gauge 8. Filtration Equipment 9. Pump

Claims

1. A method for recycling a polyester-containing substance (a), comprising: a step (A) of alcoholysing a polyester-containing substance (a) in a solvent (d) in the presence of a catalyst (b) and an alcohol (c); and a step (B) of separating the alcoholysis product obtained in the step (A).

2. 2. The recycling method according to claim 1, wherein the polyester in the polyester-containing substance (a) is polyethylene terephthalate.

3. 2. The method according to claim 1, wherein the catalyst (b) is at least one selected from the group consisting of alkali metal alkoxides and nitrogen-containing organic base compounds.

4. The method for recycling according to claim 3, characterized in that the catalyst (b) is sodium methoxide or 1,5,7-triazabicyclo[4.4.0]dec-5-ene.

5. 2. The method according to claim 1, wherein the alcohol (c) is methanol.

6. 2. The method for recycling according to claim 1, wherein the solvent (d) does not react with the alcoholysis product in the alcoholysis reaction system.

7. 7. The method for recycling according to claim 6, wherein the solvent (d) is toluene.

8. 2. The method for recycling according to claim 1, further comprising: a step (B) of separating the alcoholysis product obtained in the step (A); and a step (C) of separating substances other than the alcoholysis product.

9. The recycling method according to any one of claims 1 to 8, characterized in that an apparatus having a tank (X) for storing the polyester-containing substance (a) and a tank and / or a path (Y) for separating the alcoholysis product of the polyester is utilized.

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