Recycled resin manufacturing method

Abstract

There is a demand for an improved method for producing a regenerated resin. Provided is a method for producing a regenerated resin, the method comprising steps (A) and (B).　Step (A) is for producing a resin A having a weight-average molecular weight of 19,000 or greater by heating a composition containing a waste resin and an aryl alcohol at a weight ratio of 1:0.1 to 1:4, to a temperature that is 140℃ or higher but below the boiling point of the aryl alcohol. Step (B) is for removing the aryl alcohol from the composition obtained by step (A).

Description

[Technical field]

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

[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 increased movement to reuse and recycle plastic products with the aim of realizing 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. When the above-mentioned parts and components are manufactured and after they are used, a large amount of synthetic resin waste is generated, and this waste is reused. In particular, after molding a resin product, waste resin such as spools, runners, and molded defectives is usually generated in addition to the product. Efforts are being made to recycle this waste resin and reuse it in products without discarding it.

[0004] Among the synthetic resin recycling methods, material recycling and chemical recycling are known as methods for recycling waste materials. Material recycling is a method in which discarded synthetic resins are crushed, dissolved, and otherwise treated, and then reused as raw materials for recycled resins. However, when material recycled products are remolded, problems such as molecular weight reduction, deterioration of physical properties, and coloring tend to occur. In contrast, chemical recycling is a method in which discarded synthetic resins are chemically decomposed and reused as raw materials for products, and is a recycling method that can also be reused in high-quality products. For example, Patent Documents 1 to 3 disclose a method of recovering raw material monomers by depolymerizing polycarbonate resin. In addition, a method is disclosed in which resin is decomposed to the oligocarbonate stage, rather than completely decomposing it to the raw material monomer, and these oligocarbonates are polycondensed to produce resin (Patent Document 4). However, depolymerization into such monomers and oligomers requires a large amount of energy and multiple processing steps, and a polycondensation reaction is required to recover the molecular weight reduced in the depolymerization step. In addition, in the polycondensation reaction, it may be difficult to control the ratio of reactive groups. In addition, in the case of a resin having an aliphatic terminal structure, the terminal group may be thermally denatured during oligomerization, which may result in a change in the resin structure or a decrease in physical properties due to thermal history. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-96596 A [Patent Document 2] Patent No. 5721300 [Patent Document 3] Japanese Patent Application Publication No. 6-287295 [Patent Document 4] Japanese Patent Application Publication No. 6-220184 [Patent Document 5] Japanese Patent Application Publication No. 11-152371 [Patent Document 6] JP 2004-189887 A Summary of the Invention

[0006] Under these circumstances, there is a need for improved methods for producing recycled resins.

[0007] The present invention is, for example, as follows. [1] A method for producing recycled resin, comprising the following steps (A) and (B): (A) A step of heating a composition containing waste resin and aryl alcohol in a weight ratio of 1:0.1 to 1:4 to a temperature of 140° C. or higher but lower than the boiling point of the aryl alcohol to produce a resin A having a weight average molecular weight of 19,000 or higher. (B) A step of removing the aryl alcohol from the composition obtained in the step (A). [2] The method according to [1], wherein the waste resin contains an antioxidant. [3] The method according to [1] or [2], wherein the molecular weight retention rate of the resin A in step (A) is 50% or more. [4] The method according to any one of [1] to [3], wherein the waste resin contains at least one selected from a polycarbonate resin, a polyester resin, and a polyester carbonate resin. [5] The method according to any one of [1] to [4], wherein the waste resin has an aliphatic terminal structure.

[0008] [6] The method according to any one of [1] to [5], wherein the waste resin contains a structural unit represented by any one of the following general formulas (1) to (5): [ka] [During the ceremony, X a , X b , X c , X d , X e , and X f each independently represents an alkylene group having 1 to 4 carbon atoms, R a , R b , R c , R d , R e , and Rf each independently represents a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 5 to 20 carbon atoms, a cycloalkoxy group having 5 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heteroaryl group having 6 to 20 carbon atoms containing one or more hetero ring atoms selected from O, N, and S, an aryloxy group having 6 to 20 carbon atoms, and -C≡CR i is selected from R i represents an aryl group having 6 to 20 carbon atoms or a heteroaryl group having 6 to 20 carbon atoms containing one or more hetero ring atoms selected from O, N, and S, a, b, c, d, e, and f each independently represent an integer of 0 to 10; h, i, j, k, m, and n each independently represent an integer of 0 to 4; R g and R h each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. [6a] The method according to any one of [1] to [6], wherein in the formulas (1) to (3), a, b, c, d, e, and f each independently represent an integer of 1 to 10. [7] The method according to any one of [1] to [6], wherein the waste resin is a spool and / or a runner generated during resin molding. [8] The method according to any one of [1] to [7], wherein in the step (A), the weight ratio of the waste resin to the aryl alcohol is in the range of 1:0.8 to 1:1.4. [9] The method according to any one of [1] to [8], wherein no catalyst is added in the step (A).

[10] The method according to any one of [1] to [8], further comprising adding an alkali metal catalyst (i) in the step (A) and / or (ii) after the step (A) and before the step (B).

[0009]

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

[10] , wherein the step (B) is carried out in the presence of an alkali metal catalyst.

[12] The method according to

[10] or

[11] , wherein the amount of the alkali metal catalyst added is 10 to 1000 μmol / kg based on the waste resin.

[13] The method comprises: (i) adding a carbonic acid diester and / or a dihydroxy compound in the step (A) and / or (ii) adding a carbonic acid diester and / or a dihydroxy compound after the step (A) and before the step (B); The method according to any one of [1] to

[12] , wherein the total amount of the carbonic acid diester and / or dihydroxy compound added is 0.01 to 100 g / kg based on the waste resin.

[14] The weight average molecular weight of the resin A obtained in the step (A) is equal to or smaller than the weight average molecular weight of the waste resin; The method according to any one of [1] to

[13] , wherein the weight average molecular weight of the resin obtained in the step (B) is equal to or larger than the weight average molecular weight of the waste resin.

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

[14] , further comprising the following step (C): (C) A step of removing unmelted material from the composition obtained in the step (A) prior to the step (B).

[0010]

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

[15] , further comprising the following step (D): (D) After the step (B), a step of pelletizing the resin obtained in the step (B)

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

[16] , comprising crushing the waste resin to a size having a maximum diameter of 5 cm or less before the step (A).

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

[17] , wherein the recycled resin is for use in optical materials.

[19] The method according to

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

[20] The method according to any of [1] to

[19] , wherein the step (A) is carried out in the absence of a strong alkali.

[0011]

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

[20] , which does not contain a catalyst selected from a nitrogen-containing compound or a phosphorus-containing compound.

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

[21] , wherein the content of the antioxidant in the waste resin is in the range of 1 to 3,000 ppm by weight.

[23] A recycled resin produced by the method according to any one of [1] to

[22] .

[24] An optical lens or optical film using the recycled resin according to

[23] .

[0012] The present invention has one or more of the following advantages. (1) The regeneration process of the present invention does not involve decomposition of the resin into low molecular weight or monomer level, so that the resin can be recycled efficiently without consuming extra heat energy to restore the molecular weight. (2) The regeneration process of the present invention does not subject the resin to excessive heat history, prevents resin denaturation, and makes it possible to obtain a high-quality regenerated resin. (3) It is possible to obtain a high-quality regenerated resin even from resins that have an aliphatic terminal structure that is easily denatured by heat. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram showing the temperature and pressure profiles used in the production of recycled resin in Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The meanings of the terms used in this specification will be explained below, and the present invention will be described in detail. "Alkyl" means a straight-chain or branched saturated aliphatic hydrocarbon group having the specified number of carbon atoms. "Cycloalkyl" means a cyclic saturated aliphatic hydrocarbon group having the specified number of carbon atoms. "Alkylene" means a divalent linear or branched hydrocarbon radical having the specified number of carbon atoms. "Cycloalkylene" means a divalent cyclic hydrocarbon group having the 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. An "alkoxy" is an alkyl group having the specified number of carbon atoms having an oxygen atom (O) attached to the end of the alkyl group. "Aryloxy" refers to an aryl group having a specified number of carbon atoms with an oxygen atom (O) attached to the end of the aryl. A "halogen" is a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br), or an iodine atom (I).

[0015] One aspect of the present invention relates to a method for producing a recycled resin from a waste resin, the method for producing a recycled resin includes the following steps: Step (C) and Step (D) are optional steps that are carried out as necessary. Step (A) A step of heating a composition containing waste resin and aryl alcohol in a weight ratio of 1:0.1 to 1:4 to a temperature of 140° C. or higher and lower than the boiling point of the aryl alcohol to produce a resin A having a weight average molecular weight of 19,000 or higher. Step (B) A step of removing the aryl alcohol from the composition obtained in step (A). Step (C) A step of removing unmelted material from the composition obtained in step (A) prior to step (B). Step (D) After step (B), a step of pelletizing the resin obtained in step (B) Each step will be described below.

[0016] (1) Process (A) In step (A), waste resin is dissolved in aryl alcohol and heated. By heating the composition containing waste resin and aryl alcohol, resin A having a weight average molecular weight of 19,000 or more is produced.

[0017] In step (A), the waste resin is dissolved while suppressing the progress of excessive depolymerization reaction. In step (A), a certain degree of molecular weight reduction of the waste resin may occur due to heating. In particular, when the waste resin contains a catalyst or when a catalyst is added in step (A), a certain degree of depolymerization reaction of the waste resin may occur in step (A). For this reason, the weight average molecular weight of the resin A obtained in step (A) is usually the same as or smaller than the weight average molecular weight of the waste resin. The present invention is characterized in that the weight average molecular weight of resin A obtained in step (A) is 19,000 or more. By completing step (A) in the high molecular weight region and proceeding to step (B), it is possible to prevent the resin from degenerating without giving the resin an excessive thermal history, and to obtain a high-quality recycled resin. Furthermore, since the decrease in molecular weight is suppressed, it is possible to efficiently recycle the resin without consuming excessive thermal energy to restore the molecular weight.

[0018] In the present invention, the weight average molecular weight (Mw) of a resin means the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC), and is measured by the method described in the examples below. The weight average molecular weight of Resin A is preferably 19,400 or more, more preferably 20,000 or more, even more preferably 29,000 or more, still more preferably 30,000 or more, and particularly preferably 35,000 or more.

[0019] In the present invention, the molecular weight retention rate of resin A is preferably 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 of resin A is calculated from the weight average molecular weight (MW1) of the waste resin and the weight average molecular weight (MW2) of resin A according to the following formula. Molecular weight retention rate of resin A (%) = (MW2) / (MW1) x 100

[0020] The heating temperature is 140°C or higher and lower than the boiling point of the aryl alcohol. If the temperature is lower than 140°C, the temperature may be similar to or lower than the glass transition temperature (Tg) of the resin, resulting in poor solubility of the resin. The heating temperature of the composition is preferably 140 to 250°C, more preferably 140 to 200°C, and even more preferably 160 to 200°C. Within this temperature range, the solubility of the resin in the aryl alcohol is excellent, and the viscosity of the composition is reduced, reducing the stirring power.

[0021] Heating is preferably carried out in two or more stages. In one embodiment, it is preferable to heat to 140 to 200°C (preferably 145 to 180°C, more preferably 160 to 180°C), and then to a temperature of 180°C or higher and lower than the boiling point of the aryl alcohol (preferably 180 to 200°C, more preferably 185 to 195°C). By heating in multiple stages, the solubility of the resin in the aryl alcohol can be increased while suppressing the progress of excessive depolymerization. Heating may be carried out in three or more stages.

[0022] 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 105 kPa, and even more preferably 95 to 102 kPa. In one embodiment, from the viewpoint of energy saving, step (A) is carried out at around atmospheric pressure.

[0023] In step (A), the weight ratio of the waste resin and the aryl alcohol (waste resin:aryl alcohol) is 1:0.1 to 1:4. If it is less than 1:0.1 (i.e., the amount of aryl alcohol is small), it takes a long time to reach a dissolved state or dissolution itself tends to be impossible, which is not preferable. If it is more than 1:4 (i.e., the amount of aryl alcohol is large), the depolymerization reaction is promoted, monomers and low molecular weight oligomers are generated, and the molecular weight of the resin may decrease, or the aryl alcohol may not be removed in the subsequent step (B) or it may take a long time to remove the aryl alcohol. The weight ratio of the waste resin to the aryl alcohol is more preferably in the range of 1:0.8 to 1:1.4, and even more preferably in the range of 1:0.9 to 1:1.2, from the viewpoints of enabling recycling without the use of excessively large equipment, of excellent solubility of the waste resin, and / or of efficient removal of the aryl alcohol.

[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 that the resin can be uniformly dissolved without being subjected to excessive thermal history. The longer the heating time, the higher the solubility of the waste resin in aryl alcohol can be. The shorter the heating time, the smaller the thermal history of the resin can be obtained, which is preferable.

[0025] In step (A), a catalyst may be added. However, as described above, when the waste resin and aryl alcohol are heated in the presence of a catalyst, a depolymerization reaction of the waste resin may occur, so the catalyst is added and the heat treatment is performed within a range that does not cause an excessive decrease in molecular weight. From the viewpoint of suppressing an excessive depolymerization reaction and from the viewpoint of being cost-effective and easily available, the catalyst is preferably an alkali metal catalyst. By including the catalyst, the molecular weight of the resin can be increased in step (B) described later. In one embodiment, the catalyst added in step (A) is preferably the same as the catalyst used in producing the waste resin. By using the same catalyst as the catalyst contained in the waste resin, it is possible to avoid the inclusion 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.

[0026] Examples of the alkali metal catalyst include organic acid salts, inorganic salts, oxides, hydroxides, hydrides, and alkoxides of alkali metals.Specifically, sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium hydroxide, sodium hydrogen carbonate, 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 phenyl borohydride, sodium benzoate, potassium benzoate, cesium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium phenyl phosphate, disodium salt, dipotassium salt, dicesium salt, or dilithium salt of bisphenol A, and sodium salt, potassium salt, cesium salt, or lithium salt of phenol are used.Of the above alkali metal catalysts, strongly alkaline compounds tend to promote depolymerization reaction. From the viewpoint of suppressing the depolymerization reaction, preferred are sodium hydrogen carbonate, sodium carbonate, cesium carbonate, and potassium carbonate, and more preferred are sodium hydrogen carbonate, sodium carbonate, and cesium carbonate. One type of catalyst may be used, or multiple types may be used in combination.

[0027] In order to suppress a decrease in molecular weight, step (A) is preferably carried out in the absence of a strong alkali.

[0028] As the catalyst, in addition to an alkali metal catalyst, a nitrogen-containing compound such as tetramethylammonium hydroxide, a phosphorus-containing compound, or an ester exchange catalyst such as titanium tetraisopropoxide or titanium tetrabutoxide may be used. In certain embodiments, the catalyst comprises an alkali metal catalyst and a nitrogen-containing compound as a promoter.

[0029] In addition, in a specific embodiment, 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 in the subsequent step (B), and it is difficult to recover the molecular weight reduced in step (A) in step (B). In addition, these catalysts tend to cause coloring of the resin compared to alkali metal catalysts. In a specific embodiment, the catalyst preferably does not include an ester exchange catalyst, which tends to cause the resin to become discolored as compared with an alkali metal catalyst.

[0030] The amount of the alkali metal catalyst added is not particularly limited as long as it is within a range that does not cause an excessive decrease in molecular weight, but for example, it is preferably 10 to 1000 μmol / kg, more preferably 10 to 500 μmol / kg, and even more preferably 10 to 200 μmol / kg relative to the waste resin.

[0031] It is also preferable not to add a catalyst in step (A). This makes it possible to suppress the decrease in molecular weight in step (A) and to obtain a resin with little thermal history.

[0032] The waste resin may contain a catalyst used in the production of the resin. 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 the above step (A).

[0033] 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, relative to the total weight (100% by weight) of the waste resin. The content of the catalyst contained in the waste resin can be measured by, for example, ICP emission spectrometry, X-ray fluorescence analysis, atomic absorption spectrometry, etc. A specific example of a measurement method using ICP mass spectrometry (ICP-MS) is as follows. After carbonizing the sample with sulfuric acid, 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 the sample is heated on a hot plate while adding 0.1 mL of sulfuric acid just before carbonization. The sample is then covered with a quartz dish and heated in an electric furnace at 500°C for 10 hours to carbonize. Furthermore, sulfuric acid is added and heated to dryness, and nitric acid is added and heated to dryness to perform thermal acid decomposition. An aqueous nitric acid solution is added to make 50 mL, heated to 50°C, and quantitative analysis is performed by ICP-MS. ICP-MS equipment: Shimadzu Corporation: ICPE-9000

[0034] In the step (A), a carbonic acid diester and / or a dihydroxy compound may be further added to the composition containing the waste resin and the aryl alcohol. When a carbonic acid diester and / or a dihydroxy compound are present in the reaction system, a polymerization reaction proceeds in the subsequent step (B), making it possible to increase the molecular weight and to adjust the molecular weight.

[0035] Examples of the carbonic acid diester include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, etc. Among these, diphenyl carbonate is particularly preferable.

[0036] The dihydroxy compound is preferably a dihydroxy compound corresponding to the structural unit constituting the waste resin, but may be a compound other than the dihydroxy compound. Examples of the compound include bisphenol-type dihydroxy compounds (e.g., bisphenol A, bisphenol AP, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol PH, bisphenol Z, bisphenol TMC, etc.).

[0037] The total amount of the carbonic acid diester and / or dihydroxy compound added is preferably 0.01 to 100 g / kg, more preferably 0.1 to 50 g / kg, and further preferably 1.0 to 10 g / kg, based on the waste resin.

[0038] (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 one type of resin alone, or may be composed of two or more types of resins. In particular, the waste resin preferably contains at least one selected from polycarbonate resin, polyester resin, and polyester carbonate resin, and more preferably contains polycarbonate resin, from the viewpoint of excellent compatibility with aryl alcohol and / or relatively high price and expected profitability of recycling. In one embodiment, the waste resin contains aromatic polycarbonate resin.

[0039] 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 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.

[0040] The waste resin may contain, in addition to the above 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).

[0041] In one embodiment, the waste resin has an aliphatic end structure. The resin having an aliphatic end is generally more susceptible to thermal denaturation than the resin having an aryl end structure. In the method of the present invention, the denaturation of the resin can be suppressed without giving the resin an excessive thermal history, so that the present invention is advantageous for regenerating the waste resin of this embodiment.

[0042] Examples of waste resin include those derived from molded products that have been used in the market as part of a product and then recovered, defective products generated in the molding process, molded products (such as spools and runners) generated as an incidental part of the molding process, defective products generated in the manufacturing process, unused molded products that are no longer needed, etc. The form of waste resin is not limited to powder, pellets, sheets, films, molded products, etc., and examples of waste resin include discarded lenses, sheets, films, defective products and burrs generated during manufacturing and / or molding processing, manufacturing waste, solids recovered from waste products using resin, and crushed products thereof.

[0043] In particular, it is preferable that the waste resin contains 5% by weight or more (more preferably 10% by weight or more, and even more preferably 20% by weight or more) of defective products generated during the molding process and molded products (such as spools and runners) generated during the molding process. Furthermore, it is preferable that the waste resin contains 80% by weight or more (more preferably 90% by weight or more, even more preferably 95% by weight or more, and especially preferably the total amount (100% by weight)) of spools and / or runners generated during resin molding. In a preferred embodiment, the waste resin is a spool and / or a runner generated in an injection molding process of polycarbonate resin for optical materials. Since the method of the present invention can obtain a recycled resin with little thermal history, it is possible to regenerate high-quality optical materials that are easily affected by thermal history using the waste resin, and to reproduce high-quality recycled resin.

[0044] The waste resin is preferably high quality and high cost, such as a resin for optical lenses, from the viewpoint of recycling profitability and obtaining a high quality recycled product. In addition, the waste resin is preferably one that has high compatibility with aryl alcohol. From this viewpoint, the waste resin preferably contains any one of the structural units represented by the following general formulas (1) to (5), and more preferably substantially consists of any one of the structural units represented by the following general formulas (1) to (5). In this specification, "substantially consists of" means, for example, that preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more of the structural units of the resin are composed of structural units represented by the general formulas (1) to (5). When the waste resin contains at least one of the structural units represented by the general formulas (1) to (5), there is no particular limitation 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 represented by the general formulas (1) to (5), a copolymer composed of a plurality of structural units represented by the general formulas (1) to (5) (for example, a binary resin, a ternary resin, etc.), or a copolymer composed of at least one of the structural units represented by the general formulas (1) to (5) and other structural units other than the formulas (1) to (5). Alternatively, it may be a blend of these homopolymers, or a blend of a homopolymer and a copolymer. In addition, the resin may have any of a random, block, and alternating copolymer structure.

[0045] [ka]

[0046] In the above formulas (1) to (3), X a , Xb , X c , X d , X e , and X f each independently represents an alkylene group having 1 to 4 carbon atoms. In the above formulas (1) to (3), R a , R b , R c , R d , R e , and R f each independently represents a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 5 to 20 carbon atoms, a cycloalkoxy group having 5 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heteroaryl group having 6 to 20 carbon atoms containing one or more hetero ring atoms selected from O, N, and S, an aryloxy group having 6 to 20 carbon atoms, and -C≡CR i In one embodiment, R a , R b , R c , R d , R e , and R f are each independently selected from a hydrogen atom, a phenyl group, a 1-naphthyl group, and a 2-naphthyl group. R i represents an aryl group having 6 to 20 carbon atoms or a heteroaryl group having 6 to 20 carbon atoms containing one or more hetero ring atoms selected from O, N, and S. In one embodiment, R i is selected from a hydrogen atom, a phenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0047] In the above formulas (1) to (3), a, b, c, d, e, and f each independently represent an integer of 0 to 10 (for example, 0 to 5, 0 to 3, or 0 or 1). In one embodiment, a, b, c, d, e, and f each independently represent an integer of 1 to 10 (for example, 1 to 5, 1 to 3, 1 to 2, or 1). Resins having such an aliphatic terminal structure are generally more susceptible to thermal denaturation than resins having an aryl terminal structure. In the method of the present invention, the denaturation of the resin can be suppressed without giving the resin an excessive thermal history, so that the present invention is advantageous for regenerating the waste resin of the embodiment.

[0048] In the above formulas (1) to (3), h, i, j, k, m, and n each independently represent an integer of 0 to 4.

[0049] In the above formulas (4) to (5), R g and R h each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms (preferably a hydrogen atom).

[0050] Specific examples of the structural unit represented by formula (1) include structural units derived from 2,2'-bis(1-hydroxymethoxy)-1,1'-binaphthalene, 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene, 2,2'-bis(3-hydroxypropyloxy)-1,1'-binaphthalene, 2,2'-bis(4-hydroxybutoxy)-1,1'-binaphthalene, etc. In one embodiment, the structural unit represented by formula (1) is a structural unit derived from 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene (also referred to as "BHEBN"). These may be used alone or in combination of two or more.

[0051] Specific examples of the structural unit represented by formula (2) include structural units derived from 9,9-bis[4-(2-hydroxyethoxy)phenyl]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, and 9,9-bis[4-(2-hydroxyethoxy)-3-phenylphenyl]fluorene (hereinafter sometimes abbreviated as "BPPEF")). In one embodiment, the constitutional unit represented by formula (2) is a constitutional unit derived from a compound selected from 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene and 9,9-bis[4-(2-hydroxyethoxy)-3-phenylphenyl]fluorene. These may be used alone or in combination of two or more kinds.

[0052] Specific examples of the structural unit represented by formula (3) include structural units derived from 9,9-bis(hydroxy(poly)alkoxynaphthyl)fluorenes. For example, structural units derived from a compound selected from 9,9-bis[6-(1-hydroxymethoxy)naphthalene-2-yl]fluorene, 9,9-bis[6-(2-hydroxyethoxy)naphthalene-2-yl]fluorene, 9,9-bis[6-(3-hydroxypropoxy)naphthalene-2-yl]fluorene, and 9,9-bis[6-(4-hydroxybutoxy)naphthalene-2-yl]fluorene are included. In one embodiment, the structural unit represented by formula (3) is a structural unit derived from 9,9-bis[6-(2-hydroxyethoxy)naphthalene-2-yl]fluorene. These may be used alone or in combination of two or more.

[0053] Specific examples of the structural unit represented by formula (4) include structural units derived from decahydro-1,4:5,8-dimethano naphthalene diols (also referred to as "D-NDM"). For example, structural units derived from compounds selected from (decahydro-1,4:5,8-dimethano naphthalene-2,6-diyl) dimethanol, (decahydro-1,4:5,8-dimethano naphthalene-2,7-diyl) dimethanol, (2-methyldecahydro-1,4:5,8-dimethano naphthalene-2,6-diyl) dimethanol, (2-methyldecahydro-1,4:5,8-dimethano naphthalene-2,7-diyl) dimethanol, (2-ethyldecahydro-1,4:5,8-dimethano naphthalene-2,6-diyl) dimethanol, and (2-ethyldecahydro-1,4:5,8-dimethano naphthalene-2,7-diyl) dimethanol.

[0054] Specific examples of the constitutional unit represented by formula (5) include constitutional units derived from decahydro-1,4:5,8-dimethanonaphthalene-2-methoxycarbonyl-6(7)-methanols. For example, a structural unit derived from a compound selected from decahydro-1,4:5,8-dimethanonaphthalene-2-methoxycarbonyl-6-methanol, decahydro-1,4:5,8-dimethanonaphthalene-2-methoxycarbonyl-7-methanol, 2-methyl-decahydro-1,4:5,8-dimethanonaphthalene-2-methoxycarbonyl-6-methanol, 2-methyl-decahydro-1,4:5,8-dimethanonaphthalene-2-methoxycarbonyl-7-methanol, 2-ethyl-decahydro-1,4:5,8-dimethanonaphthalene-2-methoxycarbonyl-6-methanol, and 2-ethyl-decahydro-1,4:5,8-dimethanonaphthalene-2-methoxycarbonyl-7-methanol can be mentioned.

[0055] The proportion of the structural unit of the above formula (1) in the waste resin is preferably 1 to 100% by weight, more preferably 20 to 90% by mass, and even more preferably 30 to 80% by mass, based on the total weight of the resin components in the waste resin, because the waste resin has a high market value as a resin having a high refractive index and a high total light transmittance. The proportion of the structural unit of the above formula (2) in the waste resin is preferably 1 to 100% by weight, more preferably 20 to 100% by mass, and even more preferably 30 to 100% by mass, based on the total weight of the resin components in the waste resin, because the waste resin has a high market value as a resin having a high refractive index and a high total light transmittance. The proportion of the structural unit of the above formula (3) in the waste resin is preferably 1 to 100% by weight, more preferably 19 to 90% by mass, and even more preferably 20 to 80% by mass, based on the total weight of the resin components of the waste resin, because the waste resin has a high market value as a resin having a high refractive index and a high total light transmittance. The proportion of the constituent unit of the above formula (4) in the waste resin is preferably 1 to 100% by weight, more preferably 20 to 100% by mass, and even more preferably 30 to 100% by mass, based on the total weight of the resin components in the waste resin, because the waste resin has a well-balanced refractive index and Abbe number for use in optical lenses and has high market value as a resin with a high total light transmittance. The proportion of the constituent unit of the above formula (5) in the waste resin is preferably 1 to 100% by weight, more preferably 20 to 100% by mass, and even more preferably 30 to 100% by mass, based on the total weight of the resin components in the waste resin, because the waste resin has a well-balanced refractive index and Abbe number for use in optical lenses and has high market value as a resin with a high total light transmittance. The total proportion of the structural units of the above formulas (1) to (5) in the waste resin is preferably 0.01 to 100% by weight, more preferably 0.1 to 100% by mass, and even more preferably 1 to 100% by mass, based on the total weight of the resin components in the waste resin, in view of the high market value of the resin as a resin with excellent optical properties.

[0056] Examples of resins having structural units of the above formulas (1) to (5) are described in, for example, International Publication WO2014 / 073496, JP2010-248445, JP2008-111047, International Publication WO2016 / 052370, International Publication WO2018 / 016516, and PCT / JP2019 / 042232.

[0057] 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, it is preferably 19,000 to 70,000, more preferably 25,000 to 60,000, and even more preferably 30,000 to 60,000.

[0058] 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, reinforcing agents, and deactivators in addition to the resin components.

[0059] In a preferred embodiment, the waste resin contains an antioxidant. By containing the antioxidant, the depolymerization reaction in step (A) can be suppressed, and the decrease in the molecular weight of the resin (particularly, the decrease to a low molecular weight range or to a monomer level) can be suppressed. The antioxidant is not particularly limited, and examples thereof include triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,3,5-trimethyl-2,4,6-tris(3,5- di-tert-butyl-4-hydroxybenzyl)benzene, N,N-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 3,5-di-tert-butyl-4-hydroxy-benzylphosphonate-diethyl ester, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, and 3,9-bis{1,1-dimethyl-2-[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane. The antioxidant may be used alone or in combination of two or more.

[0060] The content of the antioxidant in the waste resin is preferably in the range of 1 to 3000 ppm by weight, more preferably in the range of 300 to 2800 ppm by weight, still more preferably in the range of 500 to 2500 ppm by weight, and particularly preferably in the range of 500 to 2000 ppm by weight, relative to the total weight (100% by weight) of the waste resin. The content of the antioxidant contained in the waste resin can be measured by using, for example, NMR or liquid chromatography mass spectrometry (LC-MS). For example, one example of a measurement method using LC-MS is to prepare standard solutions of antioxidants with different concentrations, analyze them by LC-MS, create a calibration curve, and perform quantitative analysis of the analytical sample using the created calibration curve. Alternatively, a calibration curve can be created using a standard solution of a highly pure compound such as bisphenol A, and quantitative analysis can be performed using the bisphenol A equivalent value.

[0061] In one embodiment, the waste resin contains a deactivator. When the waste resin contains a deactivator, the content of the deactivator in the waste resin is preferably in the range of 1 to 3000 ppm by weight, more preferably in the range of 300 to 2800 ppm by weight, further preferably in the range of 500 to 2500 ppm by weight, and particularly preferably in the range of 500 to 2000 ppm by weight, based on the total weight (100% by weight) of the waste resin. Even when the waste resin contains a deactivator, a certain degree of depolymerization reaction of the waste resin may occur in step (A) due to the influence of a catalyst contained in the waste resin, or the molecular weight of the resin may increase in step (B) described later. The content of the deactivator in the waste resin can be measured, for example, by NMR or liquid chromatography mass spectrometry (LC-MS), in the same manner as the content of the antioxidant.

[0062] In step (A), an antioxidant may be added. Step (A) may be a step of heating a composition containing a waste resin, an aryl alcohol, and an antioxidant. For example, the content of the antioxidant in the composition is preferably 0.001 to 0.3 wt % relative to the total weight (100 wt %) of the waste resin, more preferably 0.030 to 0.28 wt %, further preferably 0.050 to 0.25 wt %, and particularly preferably 0.0500 to 0.20 wt %.

[0063] Since waste resin generally has environmental substances such as dust and oil attached thereto, 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 prior to the regeneration treatment.

[0064] The waste resin may be crushed to a size of 5 cm or less (preferably 0.001 to 3 cm, more preferably 0.01 to 2 cm, and even more preferably 0.1 to 1 cm) in the longest diameter before step (A). Crushing 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 uniform.

[0065] (aryl alcohol) The aryl alcohol is a compound in which the hydrogen atom of an aryl group is replaced with a hydroxyl group. The aryl alcohol is not particularly limited as long as it has excellent compatibility with waste resin and has a boiling point equal to or higher than the glass transition temperature of the resin component contained in the waste resin, and examples of the aryl alcohol include substituted or unsubstituted phenols. The substituent of the phenol can be selected from a wide range of organic groups, and examples of the substituent include alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, and halogen atoms. Among them, the aryl alcohol is preferably selected from unsubstituted phenol or mono-, di- or tri-substituted phenol (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 more preferably unsubstituted phenol, because the treatment in step (B) is easy to carry out, is inexpensive, and high-purity aryl alcohols are available on the market. Unsubstituted phenol is often contained in small amounts in the waste resin, and this can prevent the inclusion of new impurities and reduce the effect on the resin properties. The aryl alcohols may be used alone or in combination of two or more kinds.

[0066] (2) Process (B) In step (B), the aryl alcohol is removed from the composition obtained in step (A), thereby obtaining a regenerated resin.

[0067] The means for removing the aryl alcohol is not particularly limited, but for example, the aryl alcohol is 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 a temperature of 0.1 to 105 kPa, more preferably a temperature of 0.1 to 102 kPa). Preferably, after the end of step (A), the aryl alcohol is removed by gradually heating the mixture to a temperature of approximately 260°C (preferably 250°C) at a maximum in accordance with the removal rate of the aryl alcohol while lowering the pressure (for example, while lowering the pressure from a range of 90 to 105 kPa to a pressure of 0.01 to 5 kPa).

[0068] The treatment time in step (B) is not particularly limited, but is preferably 1 to 7 hours, more preferably 1.5 to 5 hours, and even more preferably 2 to 4 hours, in terms of suppressing the progress of thermal deterioration of the resin.

[0069] A catalyst may be further added after step (A) and before step (B). As the catalyst, the alkali metal catalysts described as the catalyst that can be added to step (A) are preferably used. By including a catalyst, the molecular weight of the resin can be increased in step (B). In addition, the molecular weight of the resin is likely to decrease during molding, but when a catalyst is contained, there is an advantage that the molecular weight decreased during molding can be restored to the original molecular weight of the resin in step (B). In one embodiment, step (B) is carried out in the presence of an alkali metal catalyst.

[0070] After step (A), a carbonic acid diester and / or a dihydroxy compound may be further added before the step (B). As the catalyst, the alkali metal catalyst described as the catalyst that can be added to step (A) is preferably used. When a carbonic acid diester and / or a dihydroxy compound is present in step (B), a polymerization reaction proceeds in the following step (B), and it is possible to increase the molecular weight and adjust the molecular weight.

[0071] The total amount of the carbonic acid diester and / or dihydroxy compound added is preferably 0.01 to 100 g / kg, more preferably 0.1 to 50 g / kg, and even more preferably 1.0 to 10 g / kg of the waste resin. When the carbonic acid diester and / or dihydroxy compound are added in both steps (A) and (B), it is preferable that the total amount of the carbonic acid diester and / or dihydroxy compound added in steps (A) and (B) is within the above range.

[0072] Generally, since the molecular weight of a resin tends to decrease during molding, it is preferable to increase the molecular weight in step (B) to the same level as that of the waste resin or to the molecular weight of the original product. The weight average molecular weight of the recycled resin obtained in step (B) is preferably the same as or larger than that of the waste resin. The molecular weight retention rate of the recycled resin is preferably 95% or more, more preferably 100% or more, and even more preferably 120% or more. The molecular weight retention rate of the recycled resin is calculated from the weight average molecular weight (MW1) of the waste resin and the weight average molecular weight (MW3) of the recycled resin according to the following formula. Molecular weight retention rate of recycled resin (%) = (MW3) / (MW1) x 100

[0073] The amount of the alkali metal catalyst added is not particularly limited as long as it is within a range that does not cause an excessive decrease in molecular weight, but for example, it is preferably 10 to 1000 μmol / kg, more preferably 10 to 500 μmol / kg, and even more preferably 10 to 200 μmol / kg relative to the waste resin. When the catalyst is added in both steps (A) and (B), it is preferable that the total amount of the catalyst added in steps (A) and (B) is within the above range.

[0074] (3) Process (C) The method of the present invention may include, prior to step (B), a step of removing unmelted material from the composition obtained in step (A).

[0075] The waste resin may contain multiple resins or may contain different materials such as metal materials or foreign matter such as dust that is mixed in from the surroundings during molding. However, by removing the unmelted material from the composition obtained in step (A) before step (B), a resin component that dissolves in aryl alcohol can be obtained. In particular, polycarbonate resin has high solubility in aryl alcohol, but olefin resin (e.g., cycloolefin polymer (COP) resin and cycloolefin copolymer (COC) resin) generally has low solubility in aryl alcohol. When the waste resin contains polycarbonate resin, the resin component containing polycarbonate resin can be separated from resin components with low solubility such as olefin resin.

[0076] The removal means is not particularly limited, and for example, removal can be achieved by filtration using a polymer filter or the like, or by adsorption and removal using activated carbon.

[0077] (4) Process (D) After step (B), a step of pelletizing the resin obtained in step (B) may be included. The recycled resin obtained above can be used as a molded product either as it is or after being pelletized.

[0078] (Recycled resin) By the above method, a recycled resin can be obtained. 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.

[0079] The recycled resin obtained by the above method has a reduced thermal history and is of good quality, and therefore can be used as an optical material.

[0080] Another embodiment of the present invention is a molded article containing recycled resin. There are no limitations on the shape, pattern, color, size, etc. of the molded article, and they may be arbitrarily set according to the application. The molded articles are useful for various applications, such as optical materials (members), machine part materials, electric / electronic part materials, automobile part materials, civil engineering and construction materials, molding materials, as well as paint and adhesive materials. The molded article may be, among others, an optical material, for example, an optical lens or an optical film.Furthermore, it may be advantageously used as an optical molded article suitable for structural or functional material applications of optical components such as transparent conductive substrates used in liquid crystal displays, organic EL displays, solar cells, etc., optical disks, liquid crystal panels, optical cards, sheets, films, optical fibers, connectors, vapor-deposited plastic reflectors, and displays. EXAMPLES

[0081] 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 mass" and "% by mass", respectively.

[0082] In the examples and comparative examples, the physical properties of the waste resin, resin A and recycled resin were measured by the following methods.

[0083] <Weight average molecular weight (Mw)> A calibration curve was prepared using gel permeation chromatography (GPC) with tetrahydrofuran as a 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] Equipment: Tosoh Corporation, HLC-8320GPC column: Guard column: TSK guardcolumn SuperMPHZ-M 1 piece Analytical column: 3 TSKgel SuperMultiporeHZ-M Solvent: Tetrahydrofuran Injection volume: 10μL Sample concentration: 0.2 w / v% tetrahydrofuran solution Solvent flow rate: 0.35ml / min Measurement temperature: 40℃ Detector: RI

[0084] <Molecular weight retention rate> The molecular weight retention rate was calculated from the weight average molecular weight of the waste resin (MW1), the weight average molecular weight of resin A (MW2), and the weight average molecular weight of the recycled resin (MW3) according to the following formula. Molecular weight retention rate of recycled resin (%) = (MW3) / (MW1) x 100 Molecular weight retention rate of resin A (%) = (MW2) / (MW1) x 100

[0085] [Production Example 1] Production of waste resin a As raw materials, 4.53 kg (12.1 mol) of 9,9-bis[6-(2-hydroxyethoxy)naphthalene-2-yl]fluorene (BNEF), 7.5 kg (20.03 mol) of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene (BHEBN), 8.72 kg (14.8 mol) of 9,9-bis[4-(2-hydroxyethoxy)-3-phenylphenyl]fluorene (BPPEF), 5.99 kg (27.9 mol) of diphenyl carbonate (DPC), and 2.5 × 10 -2 16 mL of sodium bicarbonate (NaHCO3) solution (4.0 x 10 moles / L) -4 mole, i.e., 8.4 × 10 per mole of dihydroxy compounds in total. -6 mol) was placed in a 50L reactor equipped with a stirrer and a distillation device, and heated from 25°C to 180°C over 30 minutes under a nitrogen atmosphere of 760mmHg. Complete dissolution of the raw materials was confirmed 30 minutes after the start of heating. Then, stirring was performed for 120 minutes at 180°C. Subsequently, the degree of vacuum was adjusted to 200mmHg, 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. Then, the reaction was performed by holding at 200°C for 20 minutes. Furthermore, the temperature was raised to 230°C at a rate of 75°C / hr, and 10 minutes after the end of the temperature rise, the degree of vacuum was reduced to 1mmHg or less over 2 hours while maintaining the temperature. Then, the temperature was raised to 245°C at a rate of 60°C / hr, and stirring was performed for another 40 minutes. After the reaction was completed, nitrogen was introduced into the reactor to return to normal pressure, and the produced thermoplastic resin was pelletized and taken out.

[0086] The resin obtained above was melt-kneaded with 15 ppm by weight of tetrabutyl phosphonium dodecylbenzenesulfonate (MGA-614, Takemoto Oil Co., Ltd.) as a deactivator, 300 ppm by weight of 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (PEP-36, ADEKA Corporation) as a mold release agent, and 1000 ppm by weight of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (AO-60, ADEKA Corporation) as an antioxidant, and pelletized. The obtained pellets were used to mold an optical lens in an injection molding machine. The runners and spools obtained as the lenses were molded were collected and designated waste resin a. The physical properties of waste resin a are shown in Table 1. In Table 1, the amounts (ppm by weight) of antioxidant and catalyst in the waste resin are values ​​calculated from the amounts (charged amounts) of antioxidant and catalyst used in Production Example 1, respectively.

[0087] [Example 1] Process (A) 100 g of the waste resin a obtained in Production Example 1 and 100 g of phenol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as aryl alcohol (ArOH) were placed in a 500 mL separable flask equipped with a turbine blade, the pressure was set to 100 kPa, and the temperature was raised from 30°C to 170°C over 1 hour (step i). During this time, it was visually confirmed that the resin had melted. Furthermore, the mixture was held at 170°C for 1 hour while stirring with a turbine blade at 200 rpm (step ii). Subsequently, the pressure was set to 100 kPa, and the temperature was raised to 190° C. while stirring at 200 rpm, and then heating and stirring were carried out at 190° C. for 3 hours (step iii). A part of the resin was sampled and designated as resin A, and the weight average molecular weight (Mw) was measured. Process (B) The pressure in the reaction system was then reduced to 250°C and 0.13 kPa over a period of 3 hours at 190°C, while removing phenol, to obtain a regenerated resin. The physical properties of Resin A and the regenerated resin are shown in Table 1.

[0088] [Example 2] A recycled resin was obtained in the same manner as in Example 1, except that in step (A), after raising the temperature to 170°C in step i, the temperature was maintained at 170°C for 3 hours in step ii, and then the temperature was raised to 190°C in step iii.

[0089] [Example 3] A recycled resin was obtained in the same manner as in Example 1, except that in step (A), after raising the temperature to 170° C. in step i, the temperature was raised to 190° C. in step iii immediately without carrying out step ii.

[0090] [Example 4] A regenerated resin was obtained in the same manner as in Example 1, except that 100 g of the waste resin a obtained in Production Example 1, 100 g of phenol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as an aryl alcohol (ArOH), and 115 μL of an aqueous sodium hydrogen carbonate solution (concentration: 0.10 mol / L, sodium hydrogen carbonate: 115 μmol / kg relative to the waste resin a) as a catalyst were charged into a 500 mL separable flask equipped with a turbine blade. The physical properties of the resin A and the regenerated resin are shown in Table 1.

[0091] [Example 5] A portion of the resin was sampled to measure the weight average molecular weight (Mw) of resin A, and then 115 μL of an aqueous sodium bicarbonate solution (concentration: 0.10 mol / L, sodium bicarbonate: 115 μmol / kg relative to the waste resin a) was added as a catalyst before the pressure was reduced, to obtain a regenerated resin in the same manner as in Example 2. The physical properties of resin A and the regenerated resin are shown in Table 1.

[0092] [Example 6] A regenerated resin was obtained in the same manner as in Example 4, except that the catalyst added together with waste resin A to a 500 mL separable flask equipped with a turbine blade was changed to 34.5 μL of sodium bicarbonate aqueous solution (concentration 0.10 mol / L, 34.5 μmol / kg of sodium bicarbonate relative to waste resin A). The physical properties of resin A and the regenerated resin are shown in Table 1.

[0093] [Example 7] A regenerated resin was obtained in the same manner as in Example 3, except that 100 g of the waste resin a obtained in Production Example 1, 100 g of phenol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as an aryl alcohol (ArOH), 115 μL of sodium bicarbonate aqueous solution (concentration 0.10 mol / L, 115 μmol / kg of sodium bicarbonate relative to the waste resin a) as a catalyst, and 0.2053 g of diphenyl carbonate (DPC) as a carbonic acid diester were placed in a 500 mL separable flask equipped with a turbine blade. The physical properties of resin A and the regenerated resin are shown in Table 1.

[0094] [Example 8] The weight ratio of waste resin a to aryl alcohol (ArOH) was changed to 1:0.8. In step (A), after the temperature was raised to 170°C in step i, the temperature was held at 170°C for 1 hour in step ii, and some of the resin remained undissolved. When the time in step ii was extended and the temperature was held at 170°C for another 3 hours, the resin was able to be dissolved (total time in step ii: 4 hours). Then, the temperature was raised to 190°C in step iii. Apart from this, a recycled resin was obtained in the same manner as in Example 1.

[0095] [Example 9] The weight ratio of waste resin a to aryl alcohol (ArOH) was changed to 1:1.5. In step (B), the pressure in the reaction system was reduced to 0.13 kPa over 3 hours at 190°C, with the set temperature set to 180-250°C, and phenol was removed while the pressure was reduced to 0.13 kPa. However, the amount of phenol was large, and the liquid temperature (internal temperature) was in the range of 185-240°C, and the set temperature could not be followed. Therefore, the time of step (B) was extended and the reaction system was held for an additional hour, which caused the liquid temperature to rise and allowed the production of a regenerated resin.

[0096] [Comparative Example 1] Step (A) was carried out in the same manner as in Example 1, except that the weight ratio of waste resin a to aryl alcohol (ArOH) was changed to 1:0.08. However, the waste resin could not be dissolved in step (A), and the treatment could not be continued.

[0097] [Comparative Example 2] The same treatment as in Example 9 was carried out except that the weight ratio of waste resin a to aryl alcohol (ArOH) was changed to 1:5. However, since a large amount of phenol was present in step (B), phenol could not be removed and a regenerated resin could not be obtained.

[0098] [Example 10] The same procedure as in Example 1 was carried out, except that 20 kg of the waste resin a obtained in Production Example 1 and 20 kg of phenol (phenol distilled in Production Example 1) as aryl alcohol (ArOH) were charged into a 50 L double helical ribbon blade-equipped reactor. The regenerated resin was withdrawn in the form of strands from an outlet at the bottom of the reactor via a gear pump, cooled by passing through a water tank, and cut into pellets using a pelletizer.

[0099] [Table 1]

[0100] As shown in Table 1, the method of the present invention made it possible to recycle waste resin while suppressing the decrease in molecular weight. Specifically, the weight average molecular weight of resin A obtained after step (A) was 19,000 or more (molecular weight retention rate of 50% or more), and it was possible to obtain a recycled resin with a molecular weight retention rate of 97% or more after the subsequent step (B). In Examples 1 to 3 and 8 to 10, in which no catalyst was added, the molecular weight retention rate in step (A) was 93% or more, and a recycled resin with a molecular weight retention rate of 100% or more was finally obtained. The waste resin a contains the catalyst (NaHCO3) used during production. It is presumed that the presence of such a catalyst caused an ester exchange reaction in step (B), leading to an increase in molecular weight. In particular, in Example 3, it is presumed that the generation of oligomers and monomers was suppressed in step (A), creating an environment in which the molecular weight is more likely to increase in step (B). In Examples 4 to 7, in which a catalyst was added before step (A) or step (B), a certain degree of molecular weight reduction occurred in step (A), but the molecular weight was increased after the subsequent step (B), and a molecular weight equal to or higher than that of the waste resin was finally achieved. In particular, in Examples 5 and 7, in which a catalyst was added before step (B), a higher molecular weight was obtained.

[0101] In Comparative Example 1, in which the weight ratio of waste resin a to aryl alcohol (ArOH) was less than 1:0.1 (i.e., the amount of aryl alcohol was small), the waste resin could not be dissolved in the aryl alcohol, and the regeneration process could not proceed. In Example 8 (1:0.8), in which the weight ratio of waste resin a to aryl alcohol (ArOH) was smaller (i.e., the amount of aryl alcohol was smaller) than in Example 1 (1:1), recycled resin was obtained, but it was found that the time required to dissolve the aryl alcohol was longer and greater energy consumption was required than in Example 1. In Example 10, in step (B), the recycled resin could be obtained as pellets as it was.

[0102] In Comparative Example 2, in which the weight ratio of waste resin a to aryl alcohol (ArOH) was more than 1:4 (i.e., the amount of aryl alcohol was high), the amount of aryl alcohol was too large, making it difficult to remove the aryl alcohol in step (B). If the process is scaled up at such a ratio, the reaction tank must be made larger in proportion to the amount of regenerated resin obtained, making it difficult to put the process into practical use in terms of production cost and efficiency. In Example 9, in which the weight ratio of waste resin a to aryl alcohol (ArOH) was 1:1.5, a recycled resin was obtained, but compared to Example 1 (weight ratio 1:1), the amount of aryl alcohol was large, making temperature control difficult and requiring additional heat energy to be applied to make the internal temperature of the composition reach the set temperature (excessive energy consumption). Example 1, in which the weight ratio of waste resin a to aryl alcohol (ArOH) was 1:1, is easier to control the temperature and is more suitable for practical production.

[0103] As described above, the present invention makes it possible to efficiently recycle resins while suppressing a decrease in molecular weight.

[0104] The scope of the present invention is not limited to the above description, and may be appropriately modified and implemented without departing from the spirit of the present invention, other than the above examples. All documents and publications described in this specification are incorporated herein by reference in their entirety, regardless of their purpose. This specification also includes the claims and disclosures of the specification of Japanese Patent Application No. 2019-238734 (filed on December 27, 2019), which is a Japanese patent application on which the priority claim of this application is based.

Claims

1. A method for producing a recycled resin, comprising the following steps (A) and (B), wherein the waste resin comprises at least one selected from a polycarbonate resin, a polyester resin, and a polyestercarbonate resin: (A) A step of heating a composition containing waste resin and aryl alcohol in a weight ratio of 1:0.1 to 1:4 to a temperature of 140° C. or higher and lower than the boiling point of the aryl alcohol to dissolve the waste resin in the aryl alcohol and produce a resin A having a weight average molecular weight of 19,000 or higher. (B) A step of removing the aryl alcohol from the composition obtained in the step (A).

2. The method of claim 1 , wherein the waste resin contains an antioxidant.

3. The method according to claim 1 or 2, wherein the molecular weight retention of the resin A in step (A) is 50% or more.

4. The method according to any one of claims 1 to 3, wherein the waste resin has an aliphatic end structure.

5. The method according to any one of claims 1 to 4, wherein the waste resin contains a structural unit represented by any one of the following general formulas (1) to (5). 【Chemistry 3】 [During the ceremony, X ａ , X ｂ , X ｃ , X ｄ , X ｅ , and X ｆ each independently represents an alkylene group having 1 to 4 carbon atoms, R ａ , R ｂ , R ｃ , R ｄ , R ｅ , and R ｆ each independently represents a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 5 to 20 carbon atoms, a cycloalkoxy group having 5 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heteroaryl group having 6 to 20 carbon atoms containing one or more hetero ring atoms selected from O, N, and S, an aryloxy group having 6 to 20 carbon atoms, and -C≡C-R ｉ is selected from R ｉ represents an aryl group having 6 to 20 carbon atoms or a heteroaryl group having 6 to 20 carbon atoms containing one or more hetero ring atoms selected from O, N, and S; a, b, c, d, e, and f each independently represent an integer of 0 to 10; h, i, j, k, m, and n each independently represent an integer of 0 to 4; R ｇ and R ｈ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

6. The method according to any one of claims 1 to 5, wherein the waste resin is a spool and / or a runner generated during resin molding.

7. The method according to any one of claims 1 to 6, wherein in the step (A), the weight ratio of the waste resin and the aryl alcohol is in the range of 1:0.8 to 1:1.

4.

8. The method according to any one of claims 1 to 7, wherein in step (A), no catalyst is added.

9. 8. The process according to any one of claims 1 to 7, further comprising adding an alkali metal catalyst (i) in step (A) and / or (ii) after step (A) and before step (B).

10. The process according to any one of claims 1 to 9, wherein step (B) is carried out in the presence of an alkali metal catalyst.

11. The method according to claim 9 or 10, wherein the amount of the alkali metal catalyst added is 10 to 1000 μmol / kg based on the waste resin.

12. (i) in the step (A) and / or (ii) after the step (A) and before the step (B), further adding a carbonic acid diester and / or a dihydroxy compound, The method according to any one of claims 1 to 11, wherein the total amount of the carbonic acid diester and / or dihydroxy compound added is 0.01 to 100 g / kg of the waste resin.

13. The weight average molecular weight of the resin A obtained in the step (A) is equal to or smaller than the weight average molecular weight of the waste resin, The method according to any one of claims 1 to 12, wherein the weight average molecular weight of the resin obtained in the step (B) is the same as or larger than the weight average molecular weight of the waste resin.

14. The method according to any one of claims 1 to 13, further comprising the following step (C): (C) A step of removing unmelted material from the composition obtained in the step (A) prior to the step (B).

15. The method according to any one of claims 1 to 14, further comprising the following step (D): (D) After the step (B), a step of pelletizing the resin obtained in the step (B).

16. The method according to any one of claims 1 to 15, further comprising crushing the waste resin to a size having a maximum diameter of 5 cm or less prior to the step (A).

17. The method according to any one of claims 1 to 16, 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.

19. The method according to claim 1, wherein step (A) is carried out at a pressure of 90 to 105 kPa.

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