Method for producing recycled resin

Abstract

A method for producing a recycled resin is provided in which an efficient filtration is possible and the production energy is inhibited from increasing. A method for producing a recycled resin according to one embodiment of the present invention comprises the following steps (A) to (C): (A) a step in which a waste-resin composition comprising a waste resin, an aryl alcohol, and a diol compound, wherein the weight ratio of the waste resin to the aryl alcohol is in the range of 1:0.1 to 1:6 and the weight ratio of the waste resin to the diol compound is in the range of 1:0.1 to 1:20, is heated to prepare a liquid reaction mixture; (B) a step in which the liquid reaction mixture obtained in the step (A) is filtered with a filter; and (C) a step in which the aryl alcohol is removed from a liquid reaction mixture obtained in the step (B).

Description

Recycled resin manufacturing method

[0001] The present invention relates to a method for producing recycled resin.

[0002] In recent years, concerns have grown over the deterioration of the natural environment and the increase in waste emissions, and there has been an increasing movement to reuse and recycle plastic products in an effort to realize a recycling-oriented society.

[0003] Synthetic resins such as polycarbonate resins and polyester resins are widely used in a variety of applications, including home appliances, electronic and electrical equipment, office automation equipment, optical media, automotive parts, and building materials. Large amounts of synthetic resin waste are generated during the manufacturing of these parts and components, and after their use, and efforts are being made to reuse these waste materials. In particular, after molding a resin product, waste resins such as sprues, runners, and defective molded products are typically generated in addition to the product itself. Efforts are being made to recycle these waste resins and reuse them in products rather than discarding them.

[0004] Among the methods for recycling synthetic resins, material recycling and chemical recycling are well-known as methods for reusing waste materials. Material recycling involves crushing and dissolving discarded synthetic resins and then reusing them as raw materials for recycled resins. However, remolding recycled materials often leads to problems such as a decrease in molecular weight, deterioration in physical properties, and discoloration. In contrast, chemical recycling involves chemically decomposing discarded synthetic resins and reusing them as raw materials for products, which can also be reused for high-quality products. For example, Patent Documents 1 to 3 disclose methods for recovering raw material monomers by depolymerizing polycarbonate resin. Furthermore, methods for producing resins by decomposing the resin to the oligocarbonate stage and polycondensing these oligocarbonates, rather than completely decomposing it to the raw material monomers, have also been disclosed (Patent Documents 4 to 6). However, depolymerization into such monomers and oligomers requires a large amount of energy and multiple processing steps, and also requires a polycondensation reaction to restore the molecular weight lost in the depolymerization step. Furthermore, in polycondensation reactions, it may be difficult to control the ratio of reactive groups in quantity, and in the case of resins having an aliphatic terminal structure, thermal denaturation of the terminal groups may occur during oligomerization, resulting in structural changes in the resin and a decrease in physical properties due to thermal history.Patent Document 7 discloses a method of adding a predetermined amount of aryl alcohol to waste resin and heating the resulting resin as a recycling method that reduces the thermal history of resins.

[0005] JP 2015-96596, JP 5721300, JP 6-287295, JP 6-220184, JP 11-152371, JP 2004-189887, International Publication WO 2021 / 132419

[0006] In the production process of recycled resin, the quality of the recycled resin can be improved by removing foreign matter contained in the reaction solution of waste resin through filtration using a filter. However, when recycled resin is produced by adding aryl alcohol to waste resin, as in the method described in Patent Document 7, the resulting reaction solution generally has high viscosity. As a result, if the reaction solution is directly filtered, the filtration process cannot be performed, or even if it can be performed, the process takes a long time, resulting in reduced productivity. On the other hand, if a large amount of aryl alcohol is added to reduce the viscosity of the reaction solution, the final aryl alcohol removal process requires a large amount of energy, resulting in an increase in production energy. Therefore, the present invention provides a method for producing recycled resin that enables efficient filtration while suppressing an increase in production energy.

[0007] The present invention is, for example, as follows.

[0008] [1] A method for producing recycled resin, comprising the following steps (A) to (C): (A) preparing a reaction liquid by heating a waste resin composition containing a waste resin, an aryl alcohol, and a diol compound, wherein the weight ratio of the waste resin to the aryl alcohol is in the range of 1:0.1 to 1:6 and the weight ratio of the waste resin to the diol compound is in the range of 1:0.1 to 1:20; (B) filtering the reaction liquid obtained in step (A) through a filter; and (C) removing the aryl alcohol from the reaction liquid obtained in step (B). [2] The method according to [1], wherein the intrinsic viscosity of the reaction liquid obtained in step (A) is 0.070 dL / g or less. [3] The method according to [1] or [2], wherein the pore size of the filter is 30 μm or less. [4] The method according to any one of [1] to [3], wherein the filtration rate in step (B) is 30 kg / min to 600 kg / min. [5] The manufacturing method according to any one of [1] to [4], wherein in the step (A), the waste resin composition further contains a carbonate compound, and the molar ratio of the diol compound to the carbonate compound (diol compound:carbonate compound) is in the range of 1:0.9 to 1:1.3. [5a] The manufacturing method according to [5], wherein the waste resin contains at least one selected from a polycarbonate resin and a polyester carbonate resin.

[0009] [6] The manufacturing method according to any one of [1] to [5], wherein in step (A), the waste resin composition further contains an alkali metal catalyst. [7] The manufacturing method according to any one of [1] to [6], wherein the heating temperature in step (A) is 140°C or higher and 280°C or lower. [8] The manufacturing method according to [7], wherein step (A) includes a step of heating to a temperature of 140°C or higher but lower than the boiling point of the aryl alcohol and a step of heating to a temperature of the boiling point of the aryl alcohol but lower than 230°C. [8a] The method according to [8], wherein the step of heating to a temperature of 140°C or higher but lower than the boiling point of the aryl alcohol includes heating to a temperature of the boiling point of the aryl alcohol but lower than 230°C (more preferably, the boiling point of the aryl alcohol but lower than 200°C) to dissolve the waste resin in the aryl alcohol and a diol compound. [9] The method according to any one of [1] to [8], wherein the waste resin includes at least one selected from polycarbonate resin, polyester resin, and polyestercarbonate resin.

[10] The method according to any one of [1] to [9], wherein the waste resin has an aliphatic terminal structure.

[0010]

[11] The method according to any one of [1] to

[10] , wherein the waste resin contains at least one selected from the group consisting of a structural unit (A) derived from a monomer represented by the following general formula (1), a structural unit (B) derived from a monomer represented by the following general formula (2), a structural unit (C) derived from a monomer represented by the following general formula (3), a structural unit (D) derived from a monomer represented by the following general formula (4), and a structural unit (E) derived from a monomer represented by the following general formula (5): [In formula (1), R ａ and R ｂeach independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent, an aryloxy group having 6 to 20 carbon atoms which may have a substituent, and -C≡C-R ｈ R is selected from the group consisting of ｈ represents an aryl group having 6 to 20 carbon atoms which may have a substituent, or a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N, and S and which may have a substituent; X represents a single bond or an optionally substituted fluorene group; A and B each independently represent an optionally substituted alkylene group having 1 to 5 carbon atoms; m and n each independently represent an integer of 0 to 6; and a and b each independently represent an integer of 0 to 10. [In formula (2), R ｃ and R ｄ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, and an aryl group having 6 to 20 carbon atoms which may have a substituent, and Y is a single bond, a fluorene group which may have a substituent, -CR ２１ R ２２ -, -S-, -S(=O)-, -(CH ２ ) ｒ -, -O-, -(CH ２ ) ｒ -(SiR ２３ R ２４ -O) ｓ -SiR ２３ R ２４ - (CH ２ ) ｒ - and -CR ２５ R ２６-Ph-CR ２５ R ２６ - is selected from the group consisting of R ２１ , R ２２ , R ２３ , R ２４ , R ２５ and R ２６ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, or an aryl group having 6 to 30 carbon atoms which may have a substituent, or R ２１ and R ２２ , or R ２３ and R ２４ are bonded to each other to form a carbocyclic or heterocyclic ring having 1 to 20 carbon atoms, which may have a substituent; Ph represents a phenyl group; r and s each independently represent an integer of 0 to 5,000; A and B each independently represent an alkylene group having 1 to 5 carbon atoms, which may have a substituent; p and q each independently represent an integer of 0 to 4; and a and b each independently represent an integer of 0 to 10. [In formula (3), R ｇ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. [In formula (4), R ａ and R ｂ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent, an aryloxy group having 6 to 20 carbon atoms which may have a substituent, and -C≡C-R ｈ R is selected from the group consisting of ｈrepresents an aryl group having 6 to 20 carbon atoms which may have a substituent, or a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N, and S and which may have a substituent; X represents a single bond or a fluorene group which may have a substituent; A and B each independently represent an alkylene group having 1 to 5 carbon atoms which may have a substituent; m and n each independently represent an integer of 0 to 6; a and b each independently represent an integer of 0 to 10; R' and R'' each independently are selected from the group consisting of a hydroxy group, a halogen atom, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, and an aryloxy group having 6 to 20 carbon atoms which may have a substituent. [In formula (5), G １ and G ２ each independently represents an alkylene group having 1 to 8 carbon atoms which may have a substituent, １ and K. ２ each independently represents a hydroxy group, an alkoxy group, or a halogen atom; R ｐ１ and R ｐ２ each independently represents a halogen atom, a cyano group, or an alkyl group having 1 to 8 carbon atoms which may have a substituent, １ and Ar ２ each independently represents a phenyl group or a naphthyl group which may have a substituent; １ and r ２ each independently represents an integer of 0 to 2; ３ and r ４ each independently represents an integer of 0 to 1.

[0011]

[12] The method according to any one of [1] to

[11] , wherein the waste resin is a sprue and / or a runner generated during resin molding.

[13] The method according to any one of [1] to

[12] , wherein the diol compound contains at least one diol compound that is a monomer represented by the following general formulas (1) to (3): [In formula (1), R ａ and R ｂeach independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent, an aryloxy group having 6 to 20 carbon atoms which may have a substituent, and -C≡C-R ｈ R is selected from the group consisting of ｈ represents an aryl group having 6 to 20 carbon atoms which may have a substituent, or a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N, and S and which may have a substituent; X represents a single bond or an optionally substituted fluorene group; A and B each independently represent an optionally substituted alkylene group having 1 to 5 carbon atoms; m and n each independently represent an integer of 0 to 6; and a and b each independently represent an integer of 0 to 10. [In formula (2), R ｃ and R ｄ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, and an aryl group having 6 to 20 carbon atoms which may have a substituent, and Y is a single bond, a fluorene group which may have a substituent, -CR ２１ R ２２ -, -S-, -S(=O)-, -(CH ２ ) ｒ -, -O-, -(CH ２ ) ｒ -(SiR ２３ R ２４ -O) ｓ -SiR ２３ R ２４ - (CH ２ ) ｒ - and -CR ２５ R ２６-Ph-CR ２５ R ２６ - is selected from the group consisting of R ２１ , R ２２ , R ２３ , R ２４ , R ２５ and R ２６ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, or an aryl group having 6 to 30 carbon atoms which may have a substituent, or R ２１ and R ２２ , or R ２３ and R ２４ are bonded to each other to form a carbocyclic or heterocyclic ring having 1 to 20 carbon atoms, which may have a substituent; Ph represents a phenyl group; r and s each independently represent an integer of 0 to 5,000; A and B each independently represent an alkylene group having 1 to 5 carbon atoms, which may have a substituent; p and q each independently represent an integer of 0 to 4; and a and b each independently represent an integer of 0 to 10. [In formula (3), R ｇ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.]

[14] The method according to any one of [1] to

[13] , wherein a structural unit derived from the diol compound is contained in a structural unit of the waste resin.

[15] The method according to any one of [1] to

[14] , further comprising the following step (D): (D) a step of pelletizing the resin obtained in step (C) after step (C).

[16] The method according to any one of [1] to

[15] , comprising, before step (A), pulverizing the waste resin to a size having a longest diameter of 5 cm or less.

[0012]

[17] The method according to any one of [1] to

[16] , wherein the recycled resin is for use in an optical material.

[18] The method according to

[17] , wherein the optical material is an optical lens or an optical film.

[19] The recycled resin produced by the method according to any one of [1] to

[18] .

[0013] According to the production method of the present invention, by adding specific amounts of an aryl alcohol and a diol compound to the waste resin, the viscosity of the reaction solution can be reduced without adding an excessive amount of aryl alcohol, and efficient filtration can be performed without consuming excessive heat energy. Therefore, the production method of the present invention makes it possible to efficiently recycle resins in a highly productive manner. Furthermore, the production method of the present invention removes foreign matter from the reaction solution by filtration, making it possible to obtain high-quality recycled resin (e.g., with excellent color).

[0014] The meanings of the terms used in this specification are explained below, and the present invention is described in detail. "Alkyl" refers to a linear or branched saturated aliphatic hydrocarbon group having a specified number of carbon atoms. "Cycloalkyl" refers to a cyclic saturated aliphatic hydrocarbon group having a specified number of carbon atoms. "Alkylene" refers to a divalent linear or branched hydrocarbon group having a specified number of carbon atoms. "Cycloalkylene" refers to a divalent cyclic hydrocarbon group having a specified number of carbon atoms. "Aryl" refers to an aromatic hydrocarbon cyclic ring system. "Heteroaryl" refers to an aromatic monocyclic ring system having at least one ring heteroatom or a polycyclic ring system in which at least one ring in the ring system is aromatic and has at least one ring heteroatom. "Alkoxy" refers to an alkyl group having a specified number of carbon atoms to which an oxygen atom (O) is attached at the end. "Cycloalkoxy" refers to a cycloalkyl group having a specified number of carbon atoms to which an oxygen atom (O) is attached at the end. "Aryloxy" refers to an aryl group having a specified number of carbon atoms to which an oxygen atom (O) is attached at the end. A "halogen atom" is a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br), or an iodine atom (I).

[0015] <Method for Producing Recycled Resin> One aspect of the present invention relates to a method for producing recycled resin from waste resin. The production method includes the following steps. Step (D) is an optional step that is performed as needed. Step (A) is a step of preparing a reaction liquid by heating a waste resin composition containing a waste resin, an aryl alcohol, and a diol compound, wherein the weight ratio of the waste resin to the aryl alcohol is in the range of 1:0.1 to 1:6 and the weight ratio of the waste resin to the diol compound is in the range of 1:0.1 to 1:20; Step (B) is a step of filtering the reaction liquid obtained in Step (A) with a filter; Step (C) is a step of removing the aryl alcohol from the reaction liquid obtained in Step (B); and Step (D) is a step of pelletizing the resin obtained in Step (C) after Step (C). Each step will be described below.

[0016] (1) Step (A) Step (A) is a step of preparing a reaction liquid by heating a waste resin composition that contains a waste resin, an aryl alcohol, and a diol compound, wherein the weight ratio of the waste resin to the aryl alcohol is in the range of 1:0.1 to 1:6 and the weight ratio of the waste resin to the diol compound is in the range of 1:0.1 to 1:20.

[0017] In step (A), a waste resin composition containing waste resin, aryl alcohol, and a diol compound is heated and dissolved to prepare a reaction solution. When aryl alcohol is added to waste resin to produce recycled resin, as in the method described in Patent Document 7, the resulting reaction solution is generally highly viscous. Therefore, filtering the reaction solution directly is either impossible, or even if possible, requires a long processing time, resulting in reduced productivity. In the method of the present invention, the viscosity of the reaction solution can be reduced by adding not only aryl alcohol but also a diol compound. As a result, efficient filtration can be achieved in the subsequent step (B) without adding a large amount of aryl alcohol. Furthermore, since the diol compound is a raw material monomer for thermoplastic resins, a polymerization reaction proceeds via a transesterification reaction in the aryl alcohol removal step (C), which can contribute to the high molecular weight of the recycled resin, molecular weight adjustment, and composition adjustment.

[0018] (Weight Ratio) In step (A), the weight ratio of the waste resin to the aryl alcohol (waste resin:aryl alcohol) is in the range of 1:0.1 to 1:6. A ratio of less than 1:0.1 (when the amount of aryl alcohol is less than 0.1 times the amount of the waste resin) is undesirable because it takes a long time to reach a dissolved state or dissolution itself tends to become impossible. A ratio of more than 1:6 (when the amount of aryl alcohol is more than 6 times the amount of the waste resin) is undesirable because it makes it impossible to remove the aryl alcohol in step (C) or tends to take a long time to remove the aryl alcohol, accelerates the depolymerization reaction, produces monomers and low-molecular-weight oligomers, and may reduce the molecular weight of the resulting resin, and / or requires a large amount of energy to remove the aryl alcohol, resulting in a large environmental load. The weight ratio of the waste resin to the aryl alcohol (waste resin:aryl alcohol) is more preferably in the range of 1:0.5 to 1:5, and even more preferably in the range of 1:0.8 to 1:4, from the viewpoints of improving the solubility of the waste resin, efficient removal of the aryl alcohol in step (C), suppressing a decrease in molecular weight, and energy efficiency.

[0019] In step (A), the weight ratio of the waste resin to the diol compound (waste resin:diol compound) is in the range of 1:0.1 to 1:20. A ratio of less than 1:0.1 (when the amount of diol compound is less than 0.1 times the amount of waste resin) is undesirable because the viscosity of the reaction solution obtained by dissolving the waste resin is high, resulting in poor filtration efficiency in the subsequent step (B) and / or shortening the life of the filter when a reaction solution with an excessively high viscosity is used. A ratio of more than 1:20 (when the amount of diol compound is more than 20 times the amount of waste resin) is undesirable because the depolymerization reaction is accelerated, resulting in the production of monomers and low-molecular-weight oligomers, which may result in a decrease in the molecular weight of the resulting resin. Furthermore, when a carbonate compound is contained, aryl alcohol is produced by the reaction of the diol compound with the carbonate compound in the subsequent step (C). However, if the amount of diol compound is too high, the amount of aryl alcohol produced by the reaction increases, and energy is required to remove the aryl alcohol in the subsequent step, which is undesirable. The weight ratio of the waste resin to the diol compound (amount of waste resin:amount of diol compound) is more preferably in the range of 1:0.1 to 1:10, and even more preferably in the range of 1:1 to 1:5, from the viewpoints of improving the solubility of the waste resin, improving the efficiency of the filtration treatment in step (B), and suppressing a decrease in molecular weight.

[0020] In step (A), the weight ratio of the waste resin to the total amount of the aryl alcohol and the diol compound [waste resin:(aryl alcohol+diol compound)] is preferably in the range of 1:0.2 to 1:25, more preferably in the range of 1:0.2 to 1:15, and even more preferably in the range of 1:0.2 to 1:10. Such a range is preferable in that the depolymerization of the waste resin is not excessively advanced.

[0021] The heating temperature is not particularly limited as long as it is a temperature at which the waste resin composition dissolves in the aryl alcohol and diol compound, but a temperature of 140°C or higher and 280°C or lower is preferred. At 140°C or higher, the temperature is often above the glass transition temperature (Tg) of the resin, resulting in excellent resin solubility. At 280°C or lower, this is preferred in that reactions that produce coloring components, such as thermal transition reactions, can be suppressed. The heating temperature of the composition is preferably 140 to 250°C, more preferably 140 to 230°C, and even more preferably 160 to 200°C. Within this temperature range, the resin exhibits excellent solubility in the aryl alcohol and diol compound, and the viscosity of the composition is reduced, reducing the stirring power.

[0022] Heating is preferably carried out in two or more stages. Heating in multiple stages prevents a sudden temperature rise, allowing a uniform reaction solution to be obtained in stages, thereby reducing the denaturation of monomers such as diol compounds and the thermal history of the resin. Heating may be carried out in three or more stages. In some embodiments, step (A) includes step (A1) of heating to a temperature of 140°C or higher but lower than the boiling point of the aryl alcohol, and step (A2) of heating to a temperature of the boiling point of the aryl alcohol but lower than 230°C (more preferably, the boiling point of the aryl alcohol but lower than 200°C). After dissolving the waste resin in the aryl alcohol and diol compound in step (A1), the process proceeds to step (A2). Such multi-stage heating prevents denaturation of monomers such as diol compounds and improves the quality of the resulting resin. In some embodiments, step (A1) includes heating to a temperature of the boiling point of the aryl alcohol but lower than 230°C (more preferably, the boiling point of the aryl alcohol but lower than 200°C) to dissolve the waste resin in the aryl alcohol and diol compound.

[0023] The pressure in step (A) is not particularly limited, but from the viewpoint of preventing the aryl alcohol from distilling off or volatilizing from the system, it is preferably 90 to 105 kPa, more preferably 95 to 104 kPa, and even more preferably 95 to 103 kPa. In one embodiment, from the viewpoint of energy saving, step (A) is carried out at around atmospheric pressure.

[0024] The treatment time (heating time) in step (A) is not particularly limited, but is preferably 1 to 13 hours, more preferably 1 to 8 hours, and even more preferably 1 to 7 hours, in order to achieve uniform dissolution without excessive thermal history in the resin. The longer the heating time, the higher the solubility of the waste resin in the aryl alcohol and diol compound. The shorter the heating time, the more preferable the resin obtained, as it has a smaller thermal history. When heating is performed in multiple stages in step (A), heating is preferably performed at a temperature of 140°C or higher but lower than the boiling point of the aryl alcohol for 0.3 to 4 hours (preferably 0.4 to 3 hours, more preferably 0.5 to 2 hours) and at a temperature of the boiling point of the aryl alcohol or higher but 230°C or lower (more preferably the boiling point of the aryl alcohol or higher but 200°C or lower) for 0.5 to 9 hours (preferably 0.6 to 6 hours, more preferably 1 to 5 hours).

[0025] (Waste Resin) The type of waste resin used in the method of the present invention is not particularly limited, and examples thereof include thermoplastic resins (e.g., polycarbonate resin, polyester resin, polyester carbonate resin, acrylic resin, polyolefin resin, etc.). The waste resin may be composed of a single resin or two or more resins. The waste resin preferably contains at least one selected from polycarbonate resin, polyester resin, and polyester carbonate resin, from the viewpoints of excellent compatibility with aryl alcohols and diol compounds, and / or relatively high price and expected profitability of recycling. Among these, the waste resin more preferably contains at least one selected from polycarbonate resin and polyester carbonate resin, and even more preferably contains polycarbonate resin. The method of the present invention involves the addition of aryl alcohol. However, in the case of polycarbonate resin and polyester carbonate resin made from diaryl carbonate as a raw material, aryl alcohol is also generated as a reaction by-product in the recycled resin production process (step (A)). These resins are advantageous in terms of compatibility with waste resins and improving the quality of recycled resins, since they do not contain compounds (aryl alcohols) that would not be contained in the resins in the first place.

[0026] In addition, the waste resin preferably contains a thermoplastic resin (preferably at least one of polycarbonate resin, polyester resin, and polyester carbonate resin, more preferably polycarbonate resin) in an amount of preferably 50% by weight or more, more preferably 70% by weight or more, and even more preferably 80% by weight or more, based on the total weight of the waste resin.

[0027] The waste resin may contain, in addition to the above-mentioned thermoplastic resin, other resin components (for example, at least one of synthetic resins such as polyamide, polystyrene, amorphous polyolefin, ABS, and AS, and biodegradable resins such as polylactic acid and polybutylene succinate).

[0028] In one embodiment, the waste resin has an aliphatic terminal structure. Resins with aliphatic terminals are generally more susceptible to thermal denaturation than resins with aryl terminal structures. The method of the present invention reduces the thermal history of the resin and suppresses resin denaturation, making the present invention advantageous for recycling the waste resin of this embodiment. In particular, by heating in multiple stages to prevent a sudden temperature rise, resin denaturation is further suppressed, resulting in a recycled resin of good quality (e.g., excellent color).

[0029] Examples of waste resins include molded products recovered after being used on the market as part of a product, defective products generated in the molding process, molded products incidental to the molding process (e.g., sprues and runners), defective products generated in the manufacturing process, and unused molded products that are no longer needed (molding waste). The form of the waste resin is not limited to powder, pellets, sheets, films, molded products, etc., and examples include discarded lenses, sheets, and films; defective products and burrs generated during manufacturing and / or molding; manufacturing waste; solids recovered from waste products using resin, and pulverized products thereof.

[0030] In particular, it is preferable that the waste resin contains 5 wt % or more (more preferably 10 wt % or more, even more preferably 20 wt % or more) of defective products generated during the molding process and molded products incidental to the molding process (e.g., sprues and runners) relative to the total weight of the waste resin. Furthermore, it is preferable that the waste resin contains 80 wt % or more (more preferably 90 wt % or more, even more preferably 95 wt % or more, and particularly preferably the entire amount (100 wt %)) of sprues and / or runners generated during resin molding relative to the total weight of the waste resin. In a preferred embodiment, the waste resin is sprues and / or runners generated during the injection molding process of polycarbonate resin for optical materials. The method of the present invention can obtain recycled resin with little thermal history, making it possible to recycle high-quality optical materials that are susceptible to thermal history as waste resin and reproduce high-quality recycled resin.

[0031] High-quality, high-cost waste resins, such as those used for optical lenses, are preferred from the perspective of recycling profitability and obtaining high-quality recycled products. Furthermore, waste resins with high compatibility with aryl alcohols and diol compounds are preferred. From this perspective, the waste resin preferably contains at least one structural unit selected from the group consisting of structural units (A) derived from a monomer represented by the following general formula (1), structural units (B) derived from a monomer represented by the following general formula (2), structural units (C) derived from a monomer represented by the following general formula (3), structural units (D) derived from a monomer represented by the following general formula (4), and structural units (E) derived from a monomer represented by the following general formula (5). It is more preferred that the waste resin essentially consists of structural units selected from the structural units (A) to (E). In this specification, the phrase "essentially consisting of" means, for example, that, of the total (100 mol%) of the structural units of the waste resin, preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 98 mol% or more are selected from the structural units (A) to (E).

[0032] When the waste resin contains at least one of the structural units (A) to (E), there are no particular limitations on how these structural units are contained in the resin. In one embodiment of the present invention, the waste resin may be a homopolymer composed of each of the structural units (A) to (E), a copolymer composed of a plurality of the structural units (A) to (E) (e.g., a binary resin, a ternary resin, etc.), or a copolymer composed of at least one of the structural units (A) to (E) and a structural unit other than the structural units (A) to (E). Alternatively, the waste resin may be a blend of these homopolymers, or a blend of a homopolymer and a copolymer. The resin may have a random, block, or alternating copolymer structure.

[0033] (i) Structural Unit (A) In some embodiments, the thermoplastic resin contains a structural unit (A) derived from a monomer (diol compound) represented by the following general formula (1): The structural unit (A) may be contained alone, or two or more types may be contained in combination.

[0034] In formula (1), R ａ and R ｂ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent, an aryloxy group having 6 to 20 carbon atoms which may have a substituent, and -C≡C-R ｈ R ｈ represents an aryl group having 6 to 20 carbon atoms which may have a substituent, or a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent. ａ and R ｂis preferably a hydrogen atom, an aryl group having 6 to 20 carbon atoms which may have a substituent, or a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent, more preferably a hydrogen atom, or an aryl group having 6 to 20 carbon atoms which may have a substituent, and even more preferably a hydrogen atom, or an aryl group having 6 to 12 carbon atoms which may have a substituent.

[0035] In formula (1), X represents a single bond or an optionally substituted fluorene group, preferably a single bond or an optionally substituted fluorene group having a total of 12 to 20 carbon atoms.

[0036] In formula (1), A and B each independently represent an alkylene group having 1 to 5 carbon atoms, which may have a substituent, and preferably an alkylene group having 2 or 3 carbon atoms.

[0037] In formula (1), m and n each independently represent an integer of 0 to 6, preferably an integer of 0 to 3, and more preferably 0 or 1.

[0038] In formula (1), a and b each independently represent an integer of 0 to 10, preferably an integer of 1 to 3, and more preferably 1 or 2.

[0039] In the formula (1), the substituent "may have a substituent" is not particularly limited, and examples thereof include a halogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkoxy group having 5 to 10 carbon atoms, an alkyloxycarbonyl group having 2 to 10 carbon atoms, a cycloalkyloxycarbonyl group having 5 to 10 carbon atoms, an aryloxycarbonyl group having 7 to 15 carbon atoms, an alkylcarbonyloxy group having 2 to 10 carbon atoms, a cycloalkylcarbonyloxy group having 5 to 10 carbon atoms, an arylcarbonyloxy group having 7 to 15 carbon atoms, a hydroxyalkylcarbonyl group having 2 to 10 carbon atoms, a glycidyloxycarbonyl group, a hydroxy group, a carboxy group, a cyano group, and an amide group having 1 to 10 carbon atoms.

[0040] Specific examples of the structural unit (A) include structural units derived from 2,2'-bis(1-hydroxymethoxy)-1,1'-binaphthalene, 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene (also referred to as "BNE"), 2,2'-bis(2-hydroxyethoxy)-6,6'-diphenyl-1,1'-binaphthalene (also referred to as "DP"), 9,9-bis[6-(2-hydroxyethoxy)naphthalen-2-yl]fluorene (also referred to as "BNEF"), 2,2'-bis(3-hydroxypropyloxy)-1,1'-binaphthalene, 2,2'-bis(4-hydroxybutoxy)-1,1'-binaphthalene, etc. In one embodiment, the structural unit (A) includes at least one structural unit derived from BNE, DP, and BNEF.

[0041] (ii) Structural Unit (B) In some embodiments, the thermoplastic resin contains a structural unit (B) derived from a monomer (diol compound) represented by the following general formula (2): The structural unit (B) may be contained alone or in combination of two or more types.

[0042] In formula (2), R ｃ and R ｄ are each independently selected from the group consisting of a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, and an aryl group having 6 to 20 carbon atoms which may have a substituent. ｃ and R ｄ is preferably a hydrogen atom, an aryl group having 6 to 20 carbon atoms which may have a substituent, or a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent, more preferably a hydrogen atom, or an aryl group having 6 to 20 carbon atoms which may have a substituent, and even more preferably a hydrogen atom, or an aryl group having 6 to 12 carbon atoms which may have a substituent.

[0043] In formula (2), Y represents a single bond, a fluorene group which may have a substituent, or —CR ２１ R ２２ -, -S-, -S(=O)-, -(CH ２ ) ｒ -, -O-, -(CH ２ ) ｒ -(SiR ２３ R ２４ -O) ｓ -SiR ２３ R ２４ - (CH ２ ) ｒ - and -CR ２５ R ２６ -Ph-CR ２５ R ２６ Y is preferably a single bond or -CR ２１ R ２２ - is. R ２１ , R ２２ , R ２３ , R ２４ , R ２５ and R ２６ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, or an aryl group having 6 to 30 carbon atoms which may have a substituent, or R ２１ and R ２２ , or R ２３ and R ２４ are bonded to each other to form a carbon ring or hetero ring having 1 to 20 carbon atoms, which may have a substituent. Ph represents a phenyl group. r and s each independently represent an integer of 0 to 5,000.

[0044] In formula (2), A and B each independently represent an alkylene group having 1 to 5 carbon atoms which may have a substituent. A and B each independently represent an alkylene group having 1 to 5 carbon atoms which may have a substituent, and preferably an alkylene group having 2 or 3 carbon atoms.

[0045] In formula (2), p and q each independently represent an integer of 0 to 4, preferably 0 or 1.

[0046] In formula (2), a and b each independently represent an integer of 0 to 10, preferably an integer of 0 to 5, more preferably an integer of 0 to 2, for example, 0 or 1.

[0047] In the formula (2), the substituent "may have a substituent" is not particularly limited, and examples thereof include a halogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkoxy group having 5 to 10 carbon atoms, an alkyloxycarbonyl group having 2 to 10 carbon atoms, a cycloalkyloxycarbonyl group having 5 to 10 carbon atoms, an aryloxycarbonyl group having 7 to 15 carbon atoms, an alkylcarbonyloxy group having 2 to 10 carbon atoms, a cycloalkylcarbonyloxy group having 5 to 10 carbon atoms, an arylcarbonyloxy group having 7 to 15 carbon atoms, a hydroxyalkylcarbonyl group having 2 to 10 carbon atoms, a glycidyloxycarbonyl group, a hydroxy group, a carboxy group, a cyano group, and an amide group having 1 to 10 carbon atoms.

[0048] Specific examples of the structural unit (B) include 9,9-bis(4-hydroxy-3-methylphenyl)fluorene (also referred to as "BCFL"), 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene (also referred to as "BPEF"), 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene (also referred to as "BPPEF" or "PG"), 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis[4-(2-hydroxyethoxy)-3-methylphenyl]fluorene, 9,9-bis[4-(2-hydroxyethoxy)-3-methylphenyl]fluorene, 9,9-bis[4-(2-hydroxyethoxy)-3-tert-butylphenyl]fluorene, 9,9-bis[4-(2-hydroxyethoxy)-3-isopropylphenyl]fluorene, 9,9-bis[4-(2-hydroxyethoxy)-3-cyclohexylphenyl]fluorene, bisphenol A (also referred to as "BPA"), bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bis(4-hydroxyphenyl)-2,2-dichloroethylene, bisphenol E, bisphenol F, bisphenol G, bisphenol Bisphenol M (also referred to as "BPM"), bisphenol S, bisphenol P, bisphenol PH, bisphenol TMC, bisphenol P-AP (4,4'-(1-phenylethylidene)bisphenol), bisphenol P-CDE (4,4'-cyclododecylidenebisphenol), bisphenol P-HTG (4,4'-(3,3,5-trimethylcyclohexylidene)bisphenol), bisphenol P-MIBK (4,4'-(1,3-dimethylbutylidene)bisphenol), bisphenol PEO-FL (bisphenoxyethanol), ethanolfluorene), bisphenol P-3MZ (4-[1-(4-hydroxyphenyl)-3-methylcyclohexyl]phenol), bisphenol OC-FL (4,4'-[1-[4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl]ethylidene]bisphenol), bisphenol Z, BP-2EO (2,2'-[1,1'-biphenyl]-4,4'-diylbis(oxy)bisethanol), S-BOC (4,4'-(1-methylethylidene)bis(2-methylphenol), TrisP-HAP (4,4',In one embodiment, the structural unit (B) includes at least one structural unit derived from BPEF, BPPEF, BPA, BPM, and BCFL.

[0049] (iii) Structural Unit (C) In some embodiments, the thermoplastic resin contains a structural unit (C) derived from a monomer (diol compound) represented by the following general formula (3): The structural unit (C) may be contained alone, or two or more types may be contained in combination.

[0050] In formula (3), R ｇ Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, a propyl group, and an isopropyl group. ｇ are each preferably independently a hydrogen atom.

[0051] Specific examples of the structural unit (C) include structural units derived from decahydro-1,4:5,8-dimethanonaphthalene diols (also referred to as "D-NDM"). Examples include those derived from (decahydro-1,4:5,8-dimethanonaphthalene-2,6-diyl)dimethanol, (decahydro-1,4:5,8-dimethanonaphthalene-2,7-diyl)dimethanol, (2-methyldecahydro-1,4:5,8-dimethanonaphthalene-2,6-diyl)dimethanol, (2-methyldecahydro-1,4:5,8-dimethanonaphthalene-2,7-diyl)dimethanol, (2-ethyldecahydro-1,4:5,8-dimethanonaphthalene-2,6-diyl)dimethanol, and (2-ethyldecahydro-1,4:5,8-dimethanonaphthalene-2,7-diyl)dimethanol. In one embodiment, the structural unit (C) comprises at least one structural unit derived from D-NDM.

[0052] (iv) Structural Unit (D) In ​​some embodiments, the thermoplastic resin contains a structural unit derived from a monomer represented by the following general formula (4): The structural unit (D) may be contained alone, or two or more types may be contained in combination.

[0053]

[0054] In formula (4), R ａ and R ｂ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent, an aryloxy group having 6 to 20 carbon atoms which may have a substituent, and -C≡C-R ｈ R ｈ represents an aryl group having 6 to 20 carbon atoms which may have a substituent, or a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent. ａ and R ｂ is preferably a hydrogen atom, an aryl group having 6 to 20 carbon atoms which may have a substituent, or a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent, more preferably a hydrogen atom, or an aryl group having 6 to 20 carbon atoms which may have a substituent, and even more preferably a hydrogen atom, or an aryl group having 6 to 12 carbon atoms which may have a substituent.

[0055] In formula (4), X represents a single bond or an optionally substituted fluorene group, preferably a single bond or an optionally substituted fluorene group having a total of 12 to 20 carbon atoms.

[0056] In formula (4), A and B each independently represent an alkylene group having 1 to 5 carbon atoms, which may have a substituent, and preferably an alkylene group having 2 or 3 carbon atoms.

[0057] In formula (4), m and n each independently represent an integer of 0 to 6, preferably an integer of 0 to 3, and more preferably 0 or 1.

[0058] In formula (4), a and b each independently represent an integer of 0 to 10, preferably an integer of 1 to 3, and more preferably 1 or 2.

[0059] In formula (4), R' and R'' are each independently selected from the group consisting of a hydroxy group, a halogen atom, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, and an aryloxy group having 6 to 20 carbon atoms which may have a substituent. R' and R'' are preferably a hydroxy group, a linear alkoxy group having 1 to 5 carbon atoms, or an aryloxy group having 6 to 10 carbon atoms, and more preferably a hydroxy group, a methoxy group, an ethoxy group, or a phenyloxy group.

[0060] In the formula (4), the substituent "may have a substituent" is not particularly limited, and examples thereof include a halogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkoxy group having 5 to 10 carbon atoms, an alkyloxycarbonyl group having 2 to 10 carbon atoms, a cycloalkyloxycarbonyl group having 5 to 10 carbon atoms, an aryloxycarbonyl group having 7 to 15 carbon atoms, an alkylcarbonyloxy group having 2 to 10 carbon atoms, a cycloalkylcarbonyloxy group having 5 to 10 carbon atoms, an arylcarbonyloxy group having 7 to 15 carbon atoms, a hydroxyalkylcarbonyl group having 2 to 10 carbon atoms, a glycidyloxycarbonyl group, a hydroxy group, a carboxy group, a cyano group, and an amide group having 1 to 10 carbon atoms.

[0061] Specific examples of the structural unit (D) include those derived from 2,2'-([1,1'-binaphthalene]-2,2'-diylbis(oxy))acetoacetic acid (BINOL-DC) and its methyl ester, ethyl ester, phenyl ester, etc. In one embodiment, the structural unit (D) includes at least one structural unit derived from BINOL-DC and its methyl ester, ethyl ester, or phenyl ester.

[0062] (v) Structural Unit (E) In some embodiments, the thermoplastic resin contains a structural unit (E) derived from a monomer represented by the following general formula (5): The structural unit (E) may be contained alone, or two or more types may be contained in combination.

[0063] In formula (5), G １ and G ２ Each of the groups independently represents an alkylene group having 1 to 8 carbon atoms, which may have a substituent. Examples of the alkylene group having 1 to 8 carbon atoms include methylene, ethylene, propylene, isopropylene, butylene, isobutylene, sec-butylene, tert-butylene, and pentylene. Among these, G １ and G ２ is preferably methylene, ethylene, propylene, butylene, isobutylene, or sec-butylene, more preferably methylene, ethylene, or propylene, even more preferably methylene or ethylene, and particularly preferably ethylene.

[0064] In formula (5), K １ and K. ２ each independently represents a hydroxy group, an alkoxy group, or a halogen atom. １ and K. ２ When is an alkoxy group, the number of carbon atoms therein is not particularly limited, and it is, for example, an alkoxy group having 1 to 20 carbon atoms.

[0065] In formula (5), R ｐ１ and R ｐ２Each of Ar and Ar independently represents a halogen atom, a cyano group, or an alkyl group having 1 to 8 carbon atoms which may have a substituent. １ and Ar ２ Each of r independently represents a phenyl group or a naphthyl group which may have a substituent. １ and r ２ Each independently represents an integer of 0 to 2, preferably 0 to 1. In formula (5), r ３ and r ４ each independently represents an integer of 0 to 1.

[0066] In the formula (5), the substituent "may have a substituent" is not particularly limited, and examples thereof include a halogen atom, a hydroxy group, a carboxy group, a cyano group, etc. These substituents may be present alone or in combination of two or more.

[0067] (vi) Other Structural Units The waste resin may further contain, in addition to the above-mentioned structural units, structural units of other polycarbonate resins, or structural units of other resins (polyester resins, polyester carbonate resins, polyolefin resins), etc.

[0068] For example, other structural units of polycarbonate resins include structural units derived from diol compounds such as 2,2'-[1,4-phenylenebis(methyleneoxy[1,1'-binaphthalene]-2',2-diyloxy)]di(ethan-1-ol) (DBHBNABHP) represented by the following formula; spiroglycol (3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, SPG); bisphenol TMC; bisphenol A; and alkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, neopentyl glycol, and octylene glycol.

[0069] Further, examples of the structural units of polyester resins or polyester carbonate resins include structural units derived from dicarboxylic acids or ester derivatives thereof, such as terephthalic acid, naphthalenedicarboxylic acid, 9H-fluorene 9,9-dipropionic acid or its monoalkyl (methyl, ethyl, propyl, isopropyl, butyl) ester derivatives or dialkyl ester derivatives (for example, 9,9-di(2-methoxycarbonylethyl)fluorene, 9,9-di(2-carboxyethyl)fluorene), 2,2′-bis(carboxymethoxy)-1,1′-binaphthyl, 2,2′-bis(carboxyethoxy)-1,1′-binaphthyl, 2,2′-bis(carboxyphenoxy)-1,1′-binaphthyl, and compounds represented by the following formula: Furthermore, examples of structural units derived from dihydroxy compounds (diols) that constitute polyester resins or polyester carbonate resins include structural units derived from dihydroxy compounds (diols) such as 2,2'-[1,4-phenylenebis(methyleneoxy[1,1'-binaphthalene]-2',2-diyloxy)]di(ethan-1-ol) (DBHBNABHP); spiroglycol (3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, SPG); bisphenol TMC; bisphenol A; and alkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, neopentyl glycol, and octylene glycol.

[0070] In some embodiments, the lower the content of these other structural units, the better; for example, it is preferably 50% by weight or less, more preferably 30% by weight or less, and even more preferably 10% by weight or less, based on the total weight of the thermovisible resin constituting the molding waste.

[0071] Examples of resins having the structural units (A) to (E) are described in, for example, International Publication WO 2014 / 073496, JP 2010-248445, JP 2008-111047, International Publication WO 2016 / 052370, International Publication WO 2018 / 016516, and PCT / JP2019 / 042232.

[0072] In some embodiments, the waste resin preferably contains the structural unit (A) and the structural unit (B). In certain embodiments, the waste resin contains the structural unit (A) and the structural unit (B) in a molar ratio of the structural unit (A) to the structural unit (B) [(A) / (B)] in the range of 5 / 95 to 95 / 5. The molar ratio of the structural unit (A) to the structural unit (B) in the waste resin [(A) / (B)] is more preferably in the range of 25 / 75 to 75 / 25, and even more preferably in the range of 40 / 60 to 50 / 50. In certain embodiments, the structural unit (A) is a structural unit derived from at least one selected from BNE, BNEF, and DP, and the structural unit (B) is a structural unit derived from at least one selected from BPEF and BPPEF(PG). In some embodiments, the structural unit (A) is a structural unit derived from BNE, and the structural unit (B) is a structural unit derived from BPPEF(PG).

[0073] The weight average molecular weight (Mw) of the waste resin is not particularly limited, but from the viewpoint of maintaining an appropriate strength as a resin for optical lenses, for example, it is preferably 19,000 to 70,000, more preferably 25,000 to 60,000, and even more preferably 30,000 to 60,000.

[0074] In the present invention, the weight average molecular weight (Mw) of the resin means the weight average molecular weight calculated as polystyrene by gel permeation chromatography (GPC), and is measured by the method described in the examples below.

[0075] In addition to the resin components, the waste resin may contain additives such as catalysts, antioxidants, processing stabilizers, light stabilizers, release agents, ultraviolet absorbers, flame retardants, lubricants, antistatic agents, surfactants, antibacterial agents, plasticizers, compatibilizers, reinforcers, and deactivators. These additives may also be added in step (A). For example, the content of each additive in the waste resin composition is preferably 0.001 to 0.3 wt %, more preferably 0.030 to 0.28 wt %, even more preferably 0.050 to 0.25 wt %, and particularly preferably 0.0500 to 0.20 wt %, relative to the total weight (100 wt %) of the waste resin.

[0076] Since waste resins generally have environmental substances such as dust and oil attached to them, the surface may be cleaned, if necessary, by a dry cleaning method using air blowing or a wet cleaning method using water, an organic solvent, or a surfactant before the regeneration process.

[0077] Before step (A), the waste resin may be pulverized to a size of 5 cm or less in maximum diameter (preferably 0.001 to 3 cm, more preferably 0.01 to 2 cm, and even more preferably 0.1 to 1 cm). Pulverization is preferable in that (1) solubility in aryl alcohol is increased, (2) transportability is improved, (3) introduction into a reaction vessel is facilitated, and (4) thermal history of the waste resin is made uniform.

[0078] (Aryl Alcohol) An aryl alcohol is a compound in which an aryl hydrogen atom is substituted with a hydroxy group. Aryl alcohols have excellent compatibility with waste resins, and preferably have a boiling point equal to or higher than the glass transition temperature of the resin component contained in the waste resin. Examples of aryl alcohols include substituted or unsubstituted phenols. The substituent on the phenol can be selected from a wide range of organic groups, for example, alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, and halogen atoms. Among these, in terms of ease of carrying out the treatment in step (C), low cost, and availability of high-purity aryl alcohols on the market, it is preferable for the aryl alcohol to be selected from unsubstituted phenol or mono-, di-, or tri-substituted phenols (e.g., o-, m-, or p-cresol, o-, m-, or p-ethylphenol, o-, m-, or p-chlorophenol, o-, m-, or p-methoxyphenol, 2,3-, 2,4-, or 3,4-dimethylphenol, etc.), and unsubstituted phenol is more preferred. Unsubstituted phenols are often contained in small amounts in waste resins, and this can prevent the incorporation of new impurities and reduce the impact on the resin properties. The aryl alcohols may be used alone or in combination of two or more.

[0079] (Diol Compound) The diol compound is not particularly limited, but from the viewpoint of improving the solubility of the waste resin, —CH ２ A diol compound having a —CH—OH terminal is preferred. The diol compounds may be used alone or in combination of two or more. A portion of the added diol compound undergoes a polymerization reaction via transesterification in the aryl alcohol removal step (C), and is incorporated into the resin as a structural unit.

[0080] In some embodiments, the diol compound includes a diol compound corresponding to a structural unit constituting the waste resin. That is, a structural unit derived from the diol compound is contained in the structural unit of the waste resin. By adding a diol compound identical to the diol (monomer) unit contained in the waste resin, a polymerization reaction (transesterification reaction) proceeds in step (C), enabling the resin to have a high molecular weight and the molecular weight to be adjusted.

[0081] In some embodiments, the diol compound preferably includes at least one diol compound that is a monomer represented by any one of the general formulas (1) to (3). In certain embodiments, the diol compound includes at least one selected from the diol compound represented by the general formula (1) (first diol compound) and the diol compound represented by the general formula (2) (second diol compound). In certain embodiments, the diol compound includes the diol compound represented by the general formula (1) (first diol compound) and the diol compound represented by the general formula (2) (second diol compound). In some embodiments, the diol compound includes at least one first diol compound selected from BNE, BNEF, and DP, and at least one second diol compound selected from BPEF and BPPEF (PG).

[0082] The diol compound preferably has a composition similar to or the same as that of the structural units of the waste resin. A similar or identical composition to that of the structural units of the waste resin allows for the production of resins from the same material, which is highly desirable in terms of recycling compared to the production of resins from new materials. In some embodiments, the waste resin includes structural units (A) and (B), and the diol compound includes at least one diol compound selected from the diol compound represented by the general formula (1) above and the diol compound represented by the general formula (2) above. In a specific embodiment, the waste resin includes at least one structural unit (A) selected from BNE, BNEF, and DP, and at least one structural unit (B) selected from BPEF and BPPEF(PG), and the diol compound includes at least one diol compound selected from BNE, BNEF, and DP, and at least one selected from BPEF and BPPEF(PG).

[0083] In some embodiments, the waste resin contains the structural unit (A) and the structural unit (B) in a molar ratio [(A) / (B)] of 5 / 95 to 95 / 5 (preferably 25 / 75 to 75 / 25, more preferably 40 / 60 to 50 / 50), and the diol compound contains a diol compound represented by general formula (1) (first diol compound) and a diol compound represented by general formula (2) (second diol compound) in a molar ratio [(1) / (2)] of 5 / 95 to 95 / 5 (preferably 25 / 75 to 75 / 25, more preferably 40 / 60 to 50 / 50). In certain embodiments, the structural unit (A) is a structural unit derived from at least one selected from BNE, BNEF, and DP, the structural unit (B) is a structural unit derived from at least one selected from BPEF and BPPEF(PG), the first diol compound is at least one selected from BNE, BNEF, and DP, and the second diol compound is at least one selected from BPEF and BPPEF(PG). In some embodiments, the structural unit (A) is a structural unit derived from BNE, the structural unit (B) is a structural unit derived from BPPEF(PG), the first diol compound is BNE, and the second diol compound is BPPEF(PG).

[0084] (Carbonate Compound) In step (A), a carbonate compound may be further added to the waste resin composition. By adding the carbonate compound, the polymerization reaction in step (C) proceeds, and it is possible to increase the molecular weight and adjust the molecular weight. Since the carbonate compound generates a carbonate bond by polymerization reaction with the diol compound in step (C), it is preferable to add the carbonate compound, particularly when the waste resin contains at least one selected from polycarbonate resin and polyester carbonate resin.

[0085] Examples of carbonate compounds include diphenyl carbonate (DPC), ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, etc. Among these, diphenyl carbonate is particularly preferred.

[0086] Although the amount of carbonate compound added is not particularly limited, it is preferable to adjust the molar ratio because the carbonate compound polymerizes with the diol compound to form a resin component. In some embodiments, in step (A), the molar ratio of the diol compound to the carbonate compound (diol compound:carbonate compound) is preferably in the range of 1:0.9 to 1:1.3. A molar ratio of 1:0.9 or more (the amount of the carbonate compound is 0.9 times or more that of the diol compound) is preferable because the polymerization reaction proceeds efficiently and results in a high molecular weight. More preferably, the molar ratio is 1:1 or more (the amount of the carbonate compound is 1 time or more that of the diol compound). On the other hand, if the amount of the carbonate compound is too large relative to the diol compound, the amount of aryl alcohol produced by the reaction between the carbonate compound and the diol compound in the subsequent step (C) increases, increasing the total amount of aryl alcohol. Energy is required to remove the aryl alcohol, which tends to result in a lower molecular weight. From this viewpoint, the molar ratio is preferably 1:1.3 or less (the amount of the carbonate compound is 1.3 times or less that of the diol compound), more preferably 1:1.2 or less (the amount of the carbonate compound is 1.2 times or less that of the diol compound), even more preferably 1:1.1 or less (the amount of the carbonate compound is 1.1 times or less that of the diol compound), even more preferably 1:1.05 or less (the amount of the carbonate compound is 1.05 times or less that of the diol compound), and particularly preferably 1:1.03 or less (the amount of the carbonate compound is 1.03 times or less that of the diol compound).The molar ratio of the diol compound to the carbonate compound is preferably in the range of 1:1.0 to 1:1.2, more preferably 1:1.0 to 1:1.1, even more preferably 1:1.0 to 1:1.05, and particularly preferably 1:1.0 to 1:1.03, because a resin with sufficient strength can be obtained.

[0087] (Catalyst) In step (A), a catalyst may be added to the waste resin composition. However, since heating the waste resin, aryl alcohol, and diol compound in the presence of a catalyst may cause a depolymerization reaction of the waste resin, it is preferable to add the catalyst and perform the heat treatment within a range that does not cause an excessive decrease in molecular weight. The catalyst is preferably an alkali metal catalyst from the viewpoint of suppressing excessive depolymerization reaction and from the viewpoint of cost-effectiveness and ease of acquisition. By including a catalyst, the molecular weight of the resin can be increased in step (B), which will be described later. In one embodiment, the catalyst added in step (A) is preferably the same as the catalyst used in producing the waste resin. Using the same catalyst as the catalyst contained in the waste resin can avoid the introduction of new impurities and reduce the impact on the resin properties. In a preferred embodiment, both the catalyst added in step (A) and the catalyst used in producing the waste resin are alkali metal catalysts.

[0088] Examples of alkali metal catalysts include organic acid salts, inorganic salts, oxides, hydroxides, hydrides, and alkoxides of alkali metals. Specific examples include sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium hydroxide, sodium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, sodium acetate, potassium acetate, cesium acetate, lithium acetate, sodium stearate, potassium stearate, cesium stearate, lithium stearate, sodium borohydride, sodium phenylborohydride, sodium benzoate, potassium benzoate, cesium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium phenylphosphate, disodium salt, dipotassium salt, dicesium salt, or dilithium salt of bisphenol A, and sodium salt, potassium salt, cesium salt, or lithium salt of phenol. Among the alkali metal catalysts, strongly alkaline compounds tend to promote the depolymerization reaction. From the viewpoint of suppressing the depolymerization reaction, sodium hydrogen carbonate, sodium carbonate, cesium carbonate, and potassium carbonate are preferred, and sodium hydrogen carbonate, sodium carbonate, and cesium carbonate are more preferred. One type of catalyst may be used, or two or more types may be used in combination.

[0089] In order to prevent a decrease in molecular weight, step (A) is preferably carried out in the absence of a strong alkali.

[0090] As the catalyst, in addition to alkali metal catalysts, alkaline earth metal catalysts, nitrogen-containing compounds such as tetramethylammonium hydroxide, phosphorus-containing compounds, and transesterification catalysts such as titanium tetraisopropoxide and titanium tetrabutoxide may be used. In a specific embodiment, the catalyst comprises an alkali metal catalyst and a nitrogen-containing compound as a co-catalyst.

[0091] In certain embodiments, it is preferable that the catalyst does not contain a nitrogen-containing compound or a phosphorus-containing compound. These catalysts have a relatively low decomposition temperature and are easily decomposed at high temperatures such as in step (C), making it difficult to recover the molecular weight reduced in step (A) in step (C). These catalysts are also more likely to discolor the resin than alkali metal catalysts. In certain embodiments, it is also preferable that the catalyst does not contain a transesterification catalyst. Transesterification catalysts are more likely to discolor the resin than alkali metal catalysts.

[0092] The amount of catalyst added is 1 × 10 per mole of the total of the diol compounds added. －９ ~1 x 10 －３ Molar ratio: 1 x 10 －７ ~1 x 10 －４ It is preferable to use the diol compound in such a molar ratio. By using the diol compound in such a range, the polymerization reaction of the diol compound in the step (C) can be promoted.

[0093] In step (A), it is not necessary to add a catalyst. In such a case, it is possible to suppress the decrease in molecular weight in step (A) and obtain a resin with little thermal history.

[0094] The waste resin may contain a catalyst used in the resin production, and when such a waste resin is heated together with an aryl alcohol, a depolymerization reaction may occur even if no catalyst is added in step (A). From the viewpoint of suppressing excessive depolymerization reaction, when the waste resin contains a catalyst, the catalyst is preferably an alkali metal catalyst. Specific examples of usable alkali metal catalysts are the same as those exemplified as the catalyst that can be added in step (A) above.

[0095] The total content of catalysts (preferably alkali metal catalysts) in the waste resin is preferably in the range of 0.1 to 1000 ppm by weight, more preferably in the range of 0.1 to 100 ppm by weight, and even more preferably in the range of 0.1 to 10 ppm by weight, based on the total weight (100% by weight) of the waste resin. The catalyst content in the resin can be measured, for example, by methods such as ICP atomic emission spectroscopy, X-ray fluorescence analysis, and atomic absorption spectroscopy. A specific example of a measurement method using ICP mass spectrometry (ICP-MS) is as follows. After sulfuric acid carbonization of the sample, the metal concentration is measured by ICP-MS. That is, 2 g of the resin sample is weighed into a synthetic quartz beaker, 2.5 mL of sulfuric acid is added, and immediately before carbonization, 0.1 mL of sulfuric acid is added while heating on a hot plate. The sample is then covered with a quartz dish and heated in an electric furnace at 500°C for 10 hours for carbonization. Further, sulfuric acid is added and heated to dryness, and then nitric acid is added and heated to dryness, whereby thermal acid decomposition is performed. Aqueous nitric acid solution is added to make 50 mL, heated to 50°C, and quantitative analysis is performed by ICP-MS. ICP-MS device: Shimadzu Corporation: ICPE-9000

[0096] (2) Step (B) Step (B) is a step of filtering the reaction liquid obtained in step (A) through a filter. By filtering the reaction liquid in step (B), foreign matter in the reaction liquid is removed. Examples of foreign matter include metal materials, dust mixed in from the surroundings during molding, and unmelted matter. Examples of unmelted matter include unmelted matter that does not dissolve in the reaction liquid when the waste resin contains a resin component that has low solubility in aryl alcohol (for example, an olefin-based resin (e.g., cycloolefin polymer (COP) resin or cycloolefin copolymer (COC) resin)). In the method of this embodiment, by performing a filtration process in step (B), even if unmelted matter occurs, it can be separated and removed from the reaction liquid, resulting in a high-quality recycled resin with little foreign matter contamination.

[0097] In the method of the present invention, the viscosity of the reaction solution is reduced by adding a predetermined amount of an aryl alcohol and a diol compound in the step (A), thereby enabling smooth and rapid filtration.

[0098] The intrinsic viscosity of the reaction solution to be filtered is preferably 0.070 dL / g or less, more preferably 0.065 dL / g or less, and even more preferably 0.060 dL / g or less, from the viewpoint of the performance of the filter used for filtration and productivity (smooth and rapid filtration process). There is no particular lower limit for the intrinsic viscosity of the reaction solution, but from the viewpoint of stable filtration, it is preferably 0.005 dL / g or more, more preferably 0.010 dL / g or more, and even more preferably 0.015 dL / g or more.

[0099] From the viewpoint of productivity, the filtration pressure is preferably 40 kPa or more, more preferably 80 kPa or more, and even more preferably 130 kPa or more. From the viewpoint of equipment protection, the filtration pressure is preferably 220 kPa or less, more preferably 200 kPa or less, and even more preferably 170 kPa or less.

[0100] The pore size of the filter used for filtration is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less, from the viewpoint of removing foreign matter. The smaller the pore size, the higher the filtration accuracy, but the more likely clogging occurs and the lower the productivity. Therefore, the pore size of the filter is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 7 μm or more.

[0101] The filter used for filtration is not particularly limited as long as it has the strength and heat resistance required for filtering the reaction solution, and for example, a filter made of a metal material, ceramic, stainless steel, resin, or a combination thereof can be used. Among these, stainless steel is preferred from the viewpoint of good heat resistance, corrosion resistance, and mechanical properties. As the shape of the filter, known types such as a candle type, pleated type, and leaf disk type can be used, and it is preferable to use a combination of multiple types to ensure a large filtration area.

[0102] From the viewpoints of productivity (smooth and rapid filtration) and removal of foreign matter, the filtration rate is preferably in the range of 30 kg / min to 600 kg / min, more preferably in the range of 50 kg / min to 500 kg / min, still more preferably in the range of 100 kg / min to 450 kg / min, and particularly preferably in the range of 200 kg / min to 450 kg / min. It is preferable to adjust the pressure, the pore size of the filter, and the intrinsic viscosity of the reaction solution so that the filtration rate falls within the range.

[0103] The filtration time (time required for the reaction solution to be sent to the filter) is preferably 100 to 1400 seconds, more preferably 200 to 800 seconds, and even more preferably 300 to 500 seconds, in terms of an efficient production cycle.

[0104] The filtration temperature is not particularly limited, but for the purpose of reducing the thermal history of the monomer modification and the resin and for the purpose of not delaying the batch cycle, it is preferable to perform the filtration in step (B) at the same temperature as step (A). In some embodiments, the filtration temperature is a temperature of the boiling point of the aryl alcohol or higher and 230°C or lower (more preferably, the boiling point of the aryl alcohol or higher and 200°C or lower). The filtration temperature refers to the temperature of the waste resin composition (filtrate) immediately after passing through the filter.

[0105] (3) Step (C) Step (C) is a step of removing aryl alcohol from the reaction solution obtained in step (B). This results in a recycled resin. In step (C), the aryl alcohol removal step involves a polymerization reaction (transesterification) between the diol compound and the optional carbonate compound. Therefore, the recycled resin obtained in step (C) is a mixture of a recycled resin component derived from waste resin and a resin component made from the added diol compound and the optional carbonate compound, or a composition thereof. That is, the recycled resin may be a resin in which a diol compound-derived structural unit is incorporated into a recycled resin derived from waste resin, a blend of a recycled resin and a resin containing a diol compound-derived structural unit, or a composition containing these.

[0106] In addition, when a carbonate compound is contained, an aryl alcohol may be produced by a polymerization reaction (transesterification) between the diol compound and the carbonate compound. For example, when diphenyl carbonate (DPC) is used as the carbonate compound, phenol may be produced by a polymerization reaction with the diol compound. In these cases, in step (C), in addition to the aryl alcohol in the reaction solution obtained in step (B), the aryl alcohol produced by the reaction between the diol compound and the carbonate compound is also removed.

[0107] The means for removing the aryl alcohol is not particularly limited, but for example, the aryl alcohol can be removed by heating to a temperature of 180 to 260°C (preferably a temperature of 190 to 260°C, more preferably a temperature of 190 to 250°C) under a pressure of 0.01 to 105 kPa (preferably 0.1 to 105 kPa, more preferably 0.1 to 102 kPa). Preferably, after completion of step (B), the pressure is reduced (for example, by reducing a pressure in the range of 90 to 105 kPa to a pressure of 0.01 to 5 kPa) and the mixture is gradually heated to a maximum temperature of around 260°C (preferably 250°C) in accordance with the removal rate of the aryl alcohol.

[0108] The treatment time in step (C) is not particularly limited, but is preferably 1 to 7 hours, more preferably 2 to 6.5 hours, and even more preferably 3 to 6 hours, in order to suppress the progress of thermal degradation of the resin.

[0109] A catalyst may be further added before step (C). The alkali metal catalysts described as catalysts that can be added to step (A) are similarly preferably used as catalysts. By including a catalyst, the molecular weight of the resin can be increased in step (C). Furthermore, although the molecular weight of a resin is likely to decrease during molding, the inclusion of a catalyst has the advantage that the molecular weight decreased during molding can be restored to the original molecular weight of the resin in step (C). In one embodiment, step (C) is carried out in the presence of an alkali metal catalyst.

[0110] (4) Step (D) After step (C), a step of pelletizing the resin obtained in step (C) may be included. The recycled resin obtained above can be used as a molded product either as is or after being pelletized.

[0111] (Recycled Resin) The above-described manufacturing method allows for the production of recycled resin. The recycled resin obtained by the above-described method is of good quality with little foreign matter contamination. Therefore, the recycled resin obtained by the above-described method can be used as an optical material.

[0112] In particular, the recycled resin obtained by the above method has excellent hue. Here, "excellent hue" means little coloration, i.e., a low yellowness index (YI). The yellowness index (YI) of the recycled resin is preferably 20 or less, more preferably 19 or less, even more preferably 18 or less, and particularly preferably 17 or less. The yellowness index (YI) of the recycled resin can be measured using a commercially available color difference meter, as described in the examples below.

[0113] The weight average molecular weight (Mw) of the recycled resin is not particularly limited, but from the viewpoint of maintaining appropriate strength as a resin for optical lenses, for example, it is preferably 19,000 to 70,000, more preferably 25,000 to 60,000, and even more preferably 30,000 to 60,000.

[0114] In the method of this embodiment, a decrease in molecular weight due to a depolymerization reaction is suppressed in step (A), and molecular weight recovery can be achieved by a polymerization reaction in step (C). In some embodiments, the weight average molecular weight (Mw2) of the recycled resin is preferably such that the molecular weight retention rate relative to the weight average molecular weight (Mw1) of the waste resin is 50% or more, more preferably 75% or more, even more preferably 80% or more, and particularly preferably 90% or more. The molecular weight retention rate is calculated from the weight average molecular weight (MW1) of the waste resin and the weight average molecular weight (MW2) of the recycled resin according to the following formula: Molecular weight retention rate (%) = (MW2) / (MW1) × 100

[0115] The recycled resin may contain additives such as antioxidants, processing stabilizers, light stabilizers, release agents, ultraviolet absorbers, flame retardants, lubricants, antistatic agents, surfactants, antibacterial agents, plasticizers, compatibilizers, reinforcing agents, and deactivators, as long as the additives do not impair the properties of the present invention.

[0116] Another embodiment of the present invention is a molded article containing recycled resin. The shape, pattern, color, dimensions, etc. of the molded article are not limited and may be arbitrarily determined depending on the intended use. Molded articles are useful for a variety of applications, such as optical materials (members), machine part materials, electrical and electronic part materials, automotive part materials, civil engineering and construction materials, molding materials, as well as paints and adhesives. Examples of molded articles include optical materials, such as optical lenses or optical films. Furthermore, the molded articles can be advantageously used as optical molded articles suitable for structural or functional material applications in optical components, such as transparent conductive substrates used in liquid crystal displays, organic electroluminescent displays, solar cells, optical disks, liquid crystal panels, optical cards, sheets, films, optical fibers, connectors, vapor-deposited plastic reflectors, and displays.

[0117] The present invention will be described in detail below with reference to examples, but the technical scope of the present invention is not limited thereto. In the examples, "parts" and "%" represent "parts by weight" and "% by weight", respectively.

[0118] In the examples and comparative examples, the physical properties of the waste resin and the recycled resin, and the intrinsic viscosity of the reaction solution were measured by the following methods.

[0119] <Weight-average molecular weight (Mw)> A calibration curve was prepared using gel permeation chromatography (GPC) with tetrahydrofuran as the developing solvent and standard polystyrene of known molecular weight (molecular weight distribution = 1). Based on this calibration curve, the weight-average molecular weight of the resin was calculated from the GPC retention time. [Measurement conditions] Apparatus: HLC-8320GPC manufactured by Tosoh Corporation Columns: Guard column: 1 TSK guard column Super MPHZ-M Analytical column: 3 TSKgel Super Multipore HZ-M Solvent: Tetrahydrofuran Injection volume: 10 μL Sample concentration: 0.2 w / v% tetrahydrofuran solution Solvent flow rate: 0.35 ml / min Measurement temperature: 40°C Detector: RI

[0120] <Yellowness Index (YI)> Yellowness index (YI) was measured in accordance with ASTM D 1925. (Measurement conditions) Apparatus: Spectrophotometer SE 6000 manufactured by Nippon Denshoku Industries Co., Ltd. Light source: C / 2 light source Measurement method: Reflection method Sample holder: Cylindrical quartz cell with an inner diameter of 30 mm and a height of 15 mm Sample: Pellets were spread flat on the sample holder to a depth of 13 mm.

[0121] <Intrinsic Viscosity> The intrinsic viscosity was measured using the reaction liquid before filtration (transport to reactor). 0.5 g of the reaction liquid was dissolved in methylene chloride to make 100 mL. Using an Ubbelohde viscometer (Ubbelohde SU viscometer manufactured by Shibata Scientific Co., Ltd.), the time t for the liquid to flow down and the time t0 for methylene chloride alone to flow down were measured at 23°C, and the specific viscosity (η sp) was calculated using the following formula (1): Specific Viscosity η sp = (t - t0) / t0 (1) The specific viscosity is related to the concentration c of the sample and is expressed as a power series of the intrinsic viscosity (intrinsic viscosity) η (the following formula (2)): η sp = [η]c + k[η] 2 c 2 +... (2) η sp / c=[η]+ k[η] 2c+... (3) In formula (3), η sp / c represents reduced viscosity. The reduced viscosity was measured by changing the concentration, and the concentration was plotted on the X axis and the reduced viscosity on the Y axis. By extrapolating to a concentration of zero, the intercept on the Y axis was determined, and this was taken as the intrinsic viscosity [η] (dL / g) (formula (4) below). Intrinsic viscosity [η] = lim η sp / c (4)

[0122] 1. Synthesis of Waste Resin (Resin Synthesis Example 1) As raw materials, 689.762 kg (1.84 kmol) of 2,2′-bis(2-hydroxyethoxy)-1,1′-binaphthalene (BNE), 1,330 kg (2.25 kmol) of 9,9-bis(3-phenyl-4-(2-hydroxyethoxy)phenyl)fluorene (PG), 903 kg (4.22 kmol) of diphenyl carbonate (DPC), and 104.5 ml of a 0.47 mol / L aqueous sodium hydrogen carbonate solution (12.0 × 10 relative to 1 mole of the total of the diol compounds) were used. －６ (mol) was placed in a 10-L reactor equipped with a stirrer and a distillation device and heated to 180°C under a nitrogen atmosphere of 760 mmHg. Complete dissolution of the raw materials was confirmed 30 minutes after the start of heating, and stirring was then continued for 120 minutes under the same conditions. The vacuum level was then adjusted to 200 mmHg, and the temperature was raised to 200°C at a rate of 60°C / hr. At this time, the start of distillation of by-produced phenol was confirmed. The reaction was then continued at 200°C for 20 minutes. The temperature was then raised to 230°C at a rate of 75°C / hr, and 10 minutes after the temperature increase, the vacuum level was reduced to 1 mmHg or less over 2 hours while maintaining the temperature. The temperature was then raised to 245°C at a rate of 60°C / hr, and stirring was continued for an additional 30 minutes. After the reaction was completed, nitrogen was introduced into the reactor to pressurize the reaction system, and the produced polycarbonate resin was pelletized and withdrawn to obtain polycarbonate resin pellets (cylindrical pellets, pellet length: 2 to 5 mm, pellet diameter: 2 to 5 mm). The weight average molecular weight (Mw) of the obtained polycarbonate resin was 38,000.

[0123] (Resin Synthesis Examples 2 to 5) Polycarbonate resin pellets were obtained in the same manner as in Resin Synthesis Example 1, except that the raw materials shown in Table 1 were used.

[0124] 2. Production of Recycled Resin [Example 3] 333 kg of the resin obtained in Resin Synthesis Example 1 as waste resin, diol compound (PG: 417 kg, BNE: 216 kg), 283 kg of DPC, 667 kg of phenol (boiling point: 182 ° C.), and 0.47 mol / L of NaHCO as a catalyst were used. ３ The mixture and 33 ml of the aqueous solution were placed in a vessel equipped with a condenser for preparing a reaction solution, and the mixture was left to stand at 103 kPaA and 150°C for 45 minutes. After 45 minutes, stirring was started, and the temperature was raised to 190°C over 15 minutes. After that, stirring was continued for 130 minutes at 103 kPaA (the pressure gradually increased with heating) and 190°C. Dissolution was confirmed visually, and a reaction solution was obtained. The bottom valve of the vessel equipped with a condenser for preparing a reaction solution was opened, and the mixture was filtered at a pressure of 150 kPaG through a filter with a pore size of 10 μm (number of filters: 5, filtration area: 0.19 m per filter). ２ The reaction solution was passed through a filter (material: SUS-316L manufactured by Nippon Seisen Co., Ltd.) and sent to the reactor. After the start of the transfer, pressurization was stopped when the liquid level dropped to a predetermined amount, and the bottom valve was closed when the pressure dropped and the reaction solution disappeared. The time from opening the bottom valve to closing it was recorded as the filter transfer time. After the reaction solution was transferred to the reactor, the pressure inside the reactor was reduced from 103 kPaA to 60 kPaA over 5 minutes at 210°C. While removing (distilling off) phenol from the reaction system via a condenser, the pressure was maintained for an additional 95 minutes, and the pressure was reduced from 60 kPaA to 32 kPaA over 60 minutes. The pressure was then maintained for 40 minutes, and the pressure was reduced from 32 kPaA to 0 kPaA over 155 minutes. During this time, the reactor was gradually heated from 210°C to 250°C. After the reaction was completed, the resin was removed from the reaction vessel by strand cutting and sent to a silo by air transport (pneumatic transport using a suction transporter). The phenol distilled off contained DPC. The composition and physical properties of the resulting resin are shown in Table 3.

[0125] [Examples 1, 2, and 4] Resins were obtained in the same manner as in Example 3, except that the reaction solution was prepared using the resin, aryl alcohol, diol compound, carbonate compound, and catalyst shown in Table 2. The compositions and physical properties of the obtained resins are shown in Table 3.

[0126] Comparative Examples 1, 2, and 4 Reaction solutions were prepared in the same manner as in Example 1, except that the compositions of the reaction solutions were changed to those shown in Tables 2 and 3. However, the intrinsic viscosity was high and the reaction solution could not be filtered using the same filter as in Example 1. Polymerization reaction was carried out using the reaction solution without filtration in the same manner as in Example 1. The compositions and physical properties of the obtained resins are shown in Table 3.

[0127] Comparative Example 3 Using only the waste resin without adding any of phenol, diol compound, and DPC, the same operations as in Comparative Examples 1 and 2 were carried out. The composition and physical properties of the obtained resin are shown in Table 3.

[0128]

[0129] As described above, in the method of the present invention, by adding specific amounts of an aryl alcohol and a diol compound to the waste resin, the reaction solution can be smoothly filtered, and a recycled resin with a low color index (YI) can be obtained. Furthermore, in the method of the present invention, the decrease in molecular weight is suppressed, and a recycled resin with a sufficient molecular weight can be obtained.

[0130] In contrast, in Comparative Example 3, in which the regeneration treatment was carried out without adding an aryl alcohol or a diol compound, in Comparative Examples 1 and 2, in which the regeneration treatment was carried out without adding a diol compound, and in Comparative Example 4, in which a small amount of diol compound was added, the reaction liquid could not be filtered, and the color (YI) of the obtained regenerated resin was also poor.

[0131] In Examples 2 to 4, in which the amount of diol compound was 10 times or less the amount of waste resin and the DPC / diol compound molar ratio was 1.03 or less, molecular weight reduction was further suppressed, and high-molecular-weight recycled resins were obtained. Furthermore, Examples 1 and 2 produced recycled resins with better hue (YI) than Examples 3 and 4. In Examples 1 and 2, the amount of aryl alcohol (Example 2), diol compound, and carbonate compound (Example 1) added to the waste resin was high. Although the amount of aryl alcohol required for removal increased, increasing the energy required for removal, the thermal load on the resin itself was small, resulting in less discoloration and a lower YI. If the molecular weight of Examples 1 and 2 were increased to the same level as Examples 3 and 4 by spending more time and energy, the YI would be expected to increase. Furthermore, hue also depends on the amount of waste resin added; the greater the amount of waste resin, the more likely the resin is to become discolored. The high discoloration in Example 4 is likely due in part to the large amount of waste resin.

[0132] As described above, the manufacturing method of the present invention enables efficient filtration while suppressing increases in production energy, efficiently recycles resins in a highly productive manner, and produces recycled resins of good quality (e.g., hue). The scope of the present invention is not limited to the above description, and modifications other than those exemplified above may be made as appropriate without departing from the spirit of the present invention. All documents and publications described in this specification are incorporated herein by reference in their entirety, regardless of their purpose. This specification also encompasses the claims and disclosures of the specification of Japanese Patent Application No. 2024-023810 (filed February 20, 2024), which is the Japanese patent application on which the present application claims priority.

Claims

1. A method for producing recycled resin, comprising the following steps (A) to (C): (A) preparing a reaction liquid by heating a waste resin composition containing a waste resin, an aryl alcohol, and a diol compound, wherein the weight ratio of the waste resin to the aryl alcohol is in the range of 1:0.1 to 1:6 and the weight ratio of the waste resin to the diol compound is in the range of 1:0.1 to 1:20; (B) filtering the reaction liquid obtained in step (A) with a filter; and (C) removing the aryl alcohol from the reaction liquid obtained in step (B).

2. The method according to claim 1, wherein the reaction solution obtained in step (A) has an intrinsic viscosity of 0.070 dL / g or less.

3. The manufacturing method according to claim 1, wherein the pore size of the filter is 30 μm or less.

4. The method according to claim 1, wherein the filtration rate in step (B) is 30 kg / min to 600 kg / min.

5. The manufacturing method according to claim 1, wherein in step (A), the waste resin composition further contains a carbonate compound, and the molar ratio of the diol compound to the carbonate compound (diol compound:carbonate compound) is in the range of 1:0.9 to 1:1.

3.

6. The manufacturing method according to claim 1, wherein in step (A), the waste resin composition further contains an alkali metal catalyst.

7. The method according to claim 1, wherein the heating temperature in step (A) is 140°C or higher and 280°C or lower.

8. The manufacturing method according to claim 7, wherein step (A) includes a step of heating to a temperature of 140°C or higher but lower than the boiling point of the aryl alcohol, and a step of heating to a temperature of the boiling point of the aryl alcohol or higher but 230°C or lower.

9. The method of claim 1, wherein the waste resin comprises at least one selected from polycarbonate resin, polyester resin, and polyester carbonate resin.

10. The method of claim 1, wherein the waste resin has an aliphatic end structure.

11. The method according to claim 1, wherein the waste resin contains at least one selected from the group consisting of a structural unit (A) derived from a monomer represented by the following general formula (1), a structural unit (B) derived from a monomer represented by the following general formula (2), a structural unit (C) derived from a monomer represented by the following general formula (3), a structural unit (D) derived from a monomer represented by the following general formula (4), and a structural unit (E) derived from a monomer represented by the following general formula (5). [In formula (1), R ａ and R ｂ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent, an aryloxy group having 6 to 20 carbon atoms which may have a substituent, and -C≡C-R ｈ R is selected from the group consisting of ｈ represents an aryl group having 6 to 20 carbon atoms which may have a substituent, or a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N, and S and which may have a substituent; X represents a single bond or an optionally substituted fluorene group; A and B each independently represent an optionally substituted alkylene group having 1 to 5 carbon atoms; m and n each independently represent an integer of 0 to 6; and a and b each independently represent an integer of 0 to 10. [In formula (2), R ｃ and R ｄ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, and an aryl group having 6 to 20 carbon atoms which may have a substituent, and Y is a single bond, a fluorene group which may have a substituent, -CR ２１ R ２２ -, -S-, -S(=O)-, -(CH ２ ) ｒ -, -O-, -(CH ２ ) ｒ -(SiR ２３ R ２４ -O) ｓ -SiR ２３ R ２４ - (CH ２ ) ｒ - and -CR ２５ R ２６ -Ph-CR ２５ R ２６ - is selected from the group consisting of R ２１ , R ２２ , R ２３ , R ２４ , R ２５ and R ２６ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, or an aryl group having 6 to 30 carbon atoms which may have a substituent, or R ２１ and R ２２ , or R ２３ and R ２４ are bonded to each other to form a carbocyclic or heterocyclic ring having 1 to 20 carbon atoms, which may have a substituent; Ph represents a phenyl group; r and s each independently represent an integer of 0 to 5,000; A and B each independently represent an alkylene group having 1 to 5 carbon atoms, which may have a substituent; p and q each independently represent an integer of 0 to 4; and a and b each independently represent an integer of 0 to 10. [In formula (3), R ｇ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. [In formula (4), R ａ and R ｂ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent, an aryloxy group having 6 to 20 carbon atoms which may have a substituent, and -C≡C-R ｈ R is selected from the group consisting of ｈ represents an aryl group having 6 to 20 carbon atoms which may have a substituent, or a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N, and S and which may have a substituent; X represents a single bond or a fluorene group which may have a substituent; A and B each independently represent an alkylene group having 1 to 5 carbon atoms which may have a substituent; m and n each independently represent an integer of 0 to 6; a and b each independently represent an integer of 0 to 10; R' and R'' each independently are selected from the group consisting of a hydroxy group, a halogen atom, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, and an aryloxy group having 6 to 20 carbon atoms which may have a substituent. [In formula (5), G １ and G ２ each independently represents an alkylene group having 1 to 8 carbon atoms which may have a substituent, １ and K. ２ each independently represents a hydroxy group, an alkoxy group, or a halogen atom; R ｐ１ and R ｐ２ each independently represents a halogen atom, a cyano group, or an alkyl group having 1 to 8 carbon atoms which may have a substituent, １ and Ar ２ each independently represents a phenyl group or a naphthyl group which may have a substituent; １ and r ２ each independently represents an integer of 0 to 2; ３ and r ４ each independently represents an integer of 0 to 1.

12. The method according to claim 1, wherein the waste resin is a sprue and / or a runner generated during resin molding.

13. The method according to claim 1, wherein the diol compound comprises at least one diol compound that is a monomer represented by the following general formulas (1) to (3): [In formula (1), R ａ and R ｂ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N and S and which may have a substituent, an aryloxy group having 6 to 20 carbon atoms which may have a substituent, and -C≡C-R ｈ R is selected from the group consisting of ｈ represents an aryl group having 6 to 20 carbon atoms which may have a substituent, or a heteroaryl group having 3 to 20 carbon atoms which contains one or more hetero ring atoms selected from O, N, and S and which may have a substituent; X represents a single bond or an optionally substituted fluorene group; A and B each independently represent an optionally substituted alkylene group having 1 to 5 carbon atoms; m and n each independently represent an integer of 0 to 6; and a and b each independently represent an integer of 0 to 10. [In formula (2), R ｃ and R ｄ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, and an aryl group having 6 to 20 carbon atoms which may have a substituent, and Y is a single bond, a fluorene group which may have a substituent, -CR ２１ R ２２ -, -S-, -S(=O)-, -(CH ２ ) ｒ -, -O-, -(CH ２ ) ｒ -(SiR ２３ R ２４ -O) ｓ -SiR ２３ R ２４ - (CH ２ ) ｒ - and -CR ２５ R ２６ -Ph-CR ２５ R ２６ - is selected from the group consisting of R ２１ , R ２２ , R ２３ , R ２４ , R ２５ and R ２６ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, or an aryl group having 6 to 30 carbon atoms which may have a substituent, or R ２１ and R ２２ , or R ２３ and R ２４ are bonded to each other to form a carbocyclic or heterocyclic ring having 1 to 20 carbon atoms, which may have a substituent; Ph represents a phenyl group; r and s each independently represent an integer of 0 to 5,000; A and B each independently represent an alkylene group having 1 to 5 carbon atoms, which may have a substituent; p and q each independently represent an integer of 0 to 4; and a and b each independently represent an integer of 0 to 10. [In formula (3), R ｇ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

14. The method according to claim 1, wherein the constituent units derived from the diol compound are contained in the constituent units of the waste resin.

15. The method according to claim 1, further comprising the following step (D): (D) a step of pelletizing the resin obtained in step (C) after step (C).

16. The method according to claim 1, further comprising crushing the waste resin to a size having a maximum diameter of 5 cm or less before step (A).

17. The method of claim 1, wherein the recycled resin is for optical materials.

18. The method of claim 17, wherein the optical material is an optical lens or an optical film.

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