Method for producing bisphenol, method for producing recycled polycarbonate resin, method for producing epoxy resin, and method for producing cured epoxy resin

Abstract

To provide a method for producing bisphenol, in which polycarbonate resin is decomposed with high reactivity and bisphenol is produced, even under such a mild condition with small environmental loads, and a method for producing a recycled polycarbonate resin using the obtained bisphenol, and a method for producing an epoxy resin.SOLUTION: A method for producing bisphenol is provided in which polycarbonate resin is decomposed in the presence of alkyl ester, aliphatic alcohol and a catalyst. A method for producing recycled polycarbonate resin is provided in which recycled polycarbonate resin is produced using bisphenol raw material including bisphenol obtained by the method for producing the bisphenol. A method for producing epoxy resin is provided in which epoxy resin is produced using epoxy resin raw material including bisphenol obtained by the method for producing the bisphenol.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing bisphenol. Specifically, the present invention relates to a method for producing bisphenol by utilizing the decomposition of polycarbonate resin. The present invention also relates to a method for producing recycled polycarbonate resin and an epoxy resin using bisphenol obtained by the bisphenol production method. The present invention also relates to a method for producing a cured epoxy resin using the epoxy resin obtained by the epoxy resin production method. [Background technology]

[0002] Plastic is easily accessible, durable, and inexpensive, leading to its widespread production not only in Japan but around the world. Because much of this plastic is "disposable," it is not properly disposed of and some ends up in the environment. Specifically, plastic waste flows from rivers into the ocean, where it degrades due to waves and ultraviolet light, becoming smaller than 5 mm. These tiny pieces of plastic waste are called microplastics. Animals and fish accidentally ingest these microplastics. Plastic waste has a significant impact on ecosystems, and in recent years, the marine plastic problem has become a global concern. Polycarbonate resin is used in a wide range of applications due to its transparency, mechanical properties, flame retardancy, dimensional stability, and electrical properties, and polycarbonate resin is no exception.

[0003] One method of recycling polycarbonate resin is chemical recycling, in which polycarbonate resin is chemically decomposed and returned to bisphenol, which can then be reused.Alcoholysis is also known as a method of decomposing polycarbonate resin.

[0004] For example, Patent Document 1 discloses a method for continuously ring-opening an aromatic polycarbonate into a dihydroxy compound and dimethyl carbonate by catalytically transesterifying the aromatic polycarbonate dissolved in a monohydroxy compound other than methanol with methanol in a distillation column.

[0005] Furthermore, Patent Document 2 discloses a method for recovering useful substances from waste plastics, which comprises the steps of adding a specific tertiary amine as a catalyst to a solution containing waste plastics and monohydric alcohols or monohydric phenols to chemically decompose the polycarbonate resin in the waste plastics, and recovering the decomposition products as useful substances.

[0006] Non-Patent Document 1 discloses the methanolysis of polylactic acid using ethyl acetate as a solvent and methyl carbonate (tetramethylammonium) as a catalyst, and also discloses the methanolysis of polycarbonate resin using 2-methyltetrahydrofuran or dimethyl carbonate as a solvent and methyl carbonate (tetramethylammonium) as a catalyst. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 6-340591 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-51620 [Non-patent literature]

[0008] [Non-Patent Document 1] Green Chemistry,2020,vol22,Issue12,p3721-3726. Summary of the Invention [Problem to be solved by the invention]

[0009] In the decomposition method using alcoholysis of polycarbonate resin, an aliphatic monoalcohol is usually used. However, in order to dissolve the polycarbonate resin and to improve the decomposition rate, the reaction must be carried out under high pressure conditions at a high decomposition temperature, and since aliphatic monoalcohols with a small number of carbon atoms have a low boiling point, a pressure-resistant vessel must be used.

[0010] Furthermore, according to Example 1 of Patent Document 1, polycarbonate resin is dissolved in phenol at 150°C and decomposed by countercurrent contact with vapors consisting of methanol and dimethyl carbonate. However, carrying out this process at normal pressure poses problems such as complicated device control and difficulty in controlling the decomposition of the polycarbonate resin.

[0011] Furthermore, in the method of Patent Document 2, since polycarbonate resin is poorly soluble in methanol, an amine is used as a solvent and a catalyst. However, when the amount of amine is small, there is a problem that the reactivity is low and the reaction time is long.

[0012] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing bisphenols by utilizing a decomposition method that can decompose polycarbonate resins with high reactivity even under mild conditions that impose little environmental burden. Another object of the present invention is to provide a method for producing recycled polycarbonate resins and epoxy resins using the obtained bisphenols. Another object of the present invention is to provide a method for producing cured epoxy resins using epoxy resins obtained by the method for producing epoxy resins. [Means for solving the problem]

[0013] As a result of intensive research aimed at solving the above problems, the present inventors have discovered a method for decomposing polycarbonate resin using a combination of an alkyl ester and an aliphatic alcohol. They have also discovered a method for producing bisphenols using the polycarbonate resin decomposition method. Furthermore, they have discovered methods for producing recycled polycarbonate resins and epoxy resins using the resulting bisphenols. That is, the present invention relates to the following inventions.

[0014] <1> A method for producing bisphenols by decomposing polycarbonate resin in the presence of alkyl esters, aliphatic alcohols and a catalyst. <2> the catalyst is any one selected from the group consisting of alkali metal hydroxides, alkali metal alkoxides, alkali metal carbonates, alkali metal oxides, alkylamines, and pyridines; <1> 1. A method for producing bisphenol according to claim 1. <3> The alkali metal hydroxide is sodium hydroxide or potassium hydroxide, the alkali metal carbonate is sodium carbonate, potassium carbonate, sodium hydrogen carbonate or potassium hydrogen carbonate, the alkali metal alkoxide is sodium phenoxide or sodium methoxide, and the alkali metal oxide is sodium oxide or potassium oxide, <2> 1. A method for producing bisphenol according to claim 1. <4> The alkylamine is represented by the following formula (I) or the following formula (II): <2> 1. A method for producing bisphenol according to claim 1. [ka] In formula (I), R A represents an alkyl group having 1 to 3 carbon atoms, and R B ~R C each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. [ka] In formula (II), R D ~R G each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and m represents an integer of 1 to 6. <5> The alkyl ester is a methyl ester, an ethyl ester, a butyl ester, or a glycol ester. <1> from <4> 1. The method for producing bisphenol according to claim 1, <6> The bisphenol is 2,2-bis(4-hydroxyphenyl)propane. <1> from <5> 1. The method for producing bisphenol according to claim 1, <7> The decomposition temperature of the polycarbonate resin is 150°C or less. <1> from <6> 1. The method for producing bisphenol according to claim 1, <8> The alkyl ester has 2 or more and 6 or less carbon atoms. <1> from <7> 1. The method for producing bisphenol according to claim 1, <9> The aliphatic alcohol is any one selected from the group consisting of methanol, ethanol, butanol, and ethylene glycol. <1> from <8> 1. The method for producing bisphenol according to claim 1, <10> The method comprises the following steps A, B1, and C1: <1> from <9> 1. The method for producing bisphenol according to claim 1, Step A: A step of decomposing the polycarbonate resin in the presence of the alkyl ester, the aliphatic alcohol, and the catalyst to obtain a polycarbonate decomposition liquid containing bisphenol. Step B1: A step of concentrating the polycarbonate decomposition liquid obtained in Step A to obtain a concentrated liquid Step C1: A step of supplying an aromatic hydrocarbon to the concentrated liquid obtained in Step B1 to cause crystallization to precipitate bisphenol, obtaining a slurry containing bisphenol, and subjecting the obtained slurry to solid-liquid separation to obtain bisphenol. <11> The method comprises the following steps A, B2, and C2: <1> from <9> 1. The method for producing bisphenol according to claim 1, Step A: A step of decomposing the polycarbonate resin in the presence of the alkyl ester, the aliphatic alcohol, and the catalyst to obtain a polycarbonate decomposition liquid containing bisphenol. Step B2: A step of removing the alkyl ester and the aliphatic alcohol from the solution containing the polycarbonate decomposition liquid and the aromatic monoalcohol obtained in Step A to obtain a solution containing the bisphenol and the aromatic monoalcohol. Step C2: A step of recovering bisphenol from the solution containing bisphenol and aromatic monoalcohol <12> The aforementioned <1> from <11> 1. A method for producing a recycled polycarbonate resin, comprising obtaining bisphenol through the method for producing bisphenol according to any one of the above items 1 to 5, and then using a bisphenol raw material containing the bisphenol to produce a recycled polycarbonate resin. <13> The aforementioned <1> from <11> 1. A method for producing an epoxy resin, comprising obtaining bisphenol through the method for producing bisphenol according to any one of the above items 1 to 5, and then producing an epoxy resin using a polyhydric hydroxy compound raw material containing the bisphenol. <14> The aforementioned <13> 1. A method for producing an epoxy resin, comprising: obtaining an epoxy resin through the method for producing an epoxy resin described in 1. above; and then further reacting an epoxy resin raw material containing the epoxy resin with a polyvalent hydroxy compound raw material to produce an epoxy resin. <15> The aforementioned <13> or <14> 1. A method for producing a cured epoxy resin product, comprising: obtaining an epoxy resin through the method for producing an epoxy resin described in 1. above; obtaining an epoxy resin composition containing the epoxy resin and a curing agent; and curing the epoxy resin composition to obtain a cured epoxy resin product. [Effects of the Invention]

[0015] According to the present invention, there is provided a method for producing bisphenols using a decomposition method that can decompose polycarbonate resins with high reactivity even under mild conditions that impose little environmental burden. Furthermore, there are also provided a method for producing recycled polycarbonate resins and epoxy resins using the obtained bisphenols. Furthermore, there are also provided a method for producing cured epoxy resins using the epoxy resins obtained by the method for producing epoxy resins. DETAILED DESCRIPTION OF THE INVENTION

[0016] The following describes in detail an embodiment of the present invention, but the description of the constituent elements described below is one example of an embodiment of the present invention, and the present invention is not limited to the following description as long as it does not deviate from the gist of the present invention. Note that when the expression "to" is used in this specification, it is used as an expression that includes the numerical values ​​or physical property values ​​before and after it.

[0017] <Bisphenol manufacturing method> The present invention relates to a method for producing bisphenols (hereinafter, sometimes referred to as the "method for producing bisphenols of the present invention"), in which a polycarbonate resin is decomposed in the presence of an alkyl ester, an aliphatic alcohol, and a catalyst.

[0018] The method for producing bisphenols of the present invention involves decomposing polycarbonate resin in the presence of alkyl esters, aliphatic alcohols, and a catalyst. As mentioned above, Non-Patent Document 1 discloses the methanolysis of polylactic acid in ethyl acetate. The OH groups of methyllactic acid produced by the decomposition of polylactic acid exhibit weak interactions with the oxygen atoms of the ester, resulting in a chemically stable structure. Therefore, transesterification between the OH groups of methyllactic acid and ethyl acetate is unlikely to occur. On the other hand, if polycarbonate resin is decomposed in a similar manner, the highly acidic OH groups of bisphenols are likely to undergo transesterification with ethyl acetate. This can easily be imagined as producing not only the desired bisphenol but also esterified bisphenols, resulting in a reduced bisphenol recovery rate. For this reason, the use of alkyl esters as a solvent for alcoholyzing polycarbonate resins has been considered undesirable. However, the present inventors have discovered that bisphenols can be obtained with a high recovery rate by alcoholyzing polycarbonate resins using alkyl esters as a solvent. They also discovered that even when using common catalysts such as alkali metal hydroxides, alkali metal alkoxides, alkali metal carbonates, alkylamines, and pyridines, the combined use of alkyl esters and aliphatic alcohols allows for a high recovery rate of bisphenols. The combined use of alkyl esters and aliphatic alcohols not only causes alcoholysis of polycarbonate resin by the aliphatic alcohol, but also simultaneously causes ester decomposition by the alkyl ester, which is thought to facilitate decomposition of polycarbonate resin even under mild conditions.

[0019] (Polycarbonate resin) The polycarbonate resin used in the method for producing bisphenol of the present invention comprises a polymer composition containing a carbonate bond (-O-C(=O)-O-). Specifically, the polycarbonate resin used in the method for producing bisphenol of the present invention comprises a polymer containing a repeating unit (sometimes simply referred to as a "repeating unit") derived from bisphenol, represented by general formula (1).

[0020] [ka]

[0021] R 1 ~R 4 The substituents of each independently include a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, etc. Examples thereof include a hydrogen atom, a fluoro group, a chloro group, a bromo group, an iodo group, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, an n-pentyl group, an i-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, and a t-butoxy group. Examples of such groups include an n-pentyloxy group, an i-pentyloxy group, an n-hexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, an n-decyloxy group, an n-undecyloxy group, an n-dodecyloxy group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclododecyl group, a benzyl group, a phenyl group, a tolyl group, and a 2,6-dimethylphenyl group.

[0022] R 5 and R 6The substituents of each independently include a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, etc. Examples thereof include a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, an n-pentyl group, an i-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, a t-butoxy ... i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, an i-pentyl group, Examples of such an alkyl group include an n-butyloxy group, an i-pentyloxy group, an n-hexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, an n-decyloxy group, an n-undecyloxy group, an n-dodecyloxy group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclododecyl group, a benzyl group, a phenyl group, a tolyl group, and a 2,6-dimethylphenyl group.

[0023] R 5 and R 6 may be bonded or bridged to each other to form a cycloalkylidene group, such as cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclohexylidene, 3,3,5-trimethylcyclohexylidene, cycloheptylidene, cyclooctylidene, cyclononylidene, cyclodecylidene, cycloundecylidene, cyclododecylidene, fluorenylidene, xanthonylidene, and thioxanthonylidene.

[0024] The method for producing bisphenol of the present invention is, among others, to produce a bisphenol represented by the general formula (1) R 1 ~R 4 is a hydrogen atom, and R 5 , R 6 It is preferable to use a polycarbonate resin in which the alkyl group is a methyl group (bisphenol A polycarbonate resin) as a raw material.

[0025] In the general formula (1), n ​​is not particularly limited, but is, for example, 2 to 1,000.

[0026] The polycarbonate resin used as the raw material in the method for producing bisphenols of the present invention may be not only a polycarbonate resin alone, but also a composition containing a resin other than polycarbonate resin, such as a copolymer or polymer alloy. Examples of compositions containing a resin other than polycarbonate resin include polycarbonate / polyester copolymers, polycarbonate / polyester alloys, polycarbonate / polyarylate copolymers, and polycarbonate / polyarylate alloys. When using a composition containing a resin other than polycarbonate resin, it is preferable to use one in which polycarbonate resin is the main component (the composition contains 50% by mass or more of polycarbonate resin).

[0027] Furthermore, the polycarbonate resin may be a mixture of two or more different polycarbonate resins, and a single polycarbonate resin may simply be called polycarbonate.

[0028] From the viewpoint of chemical recycling, the polycarbonate resin is preferably a polycarbonate resin contained in waste plastics. Polycarbonate resins are molded and used into various molded products such as optical components such as headlamps and optical recording media such as optical disks. As waste plastics containing polycarbonate resins, offcuts, defective products, used molded products, etc., generated when molding polycarbonate resins into these molded products can be used.

[0029] Waste plastics can be used after being washed, crushed, or pulverized as appropriate. Crushing methods for waste plastics include coarse crushing using a jaw crusher or rotary crusher to crush to 20 cm or less, medium crushing using a rotary crusher, cone crusher, or mill to crush to 1 cm or less, and milling to crush to 1 mm or less. Any method can be used to reduce the size of the plastics to a size that can be fed into the decomposition tank. Thin plastics, such as CDs and DVDs, can be shredded using a shredder or other device and fed into the decomposition tank. Furthermore, parts made of components other than polycarbonate resin, such as other resins in copolymers or polymer alloys, or the front and back layers of optical disks, can be removed in advance before use.

[0030] (Alkyl ester) One of the features of the bisphenol production method of the present invention is the use of alkyl esters, which are reaction products of carboxylic acids and aliphatic alcohols. Examples of alkyl esters include monoalkyl esters, dialkyl esters, and alkylene glycol alkyl esters.

[0031] The alkyl ester is preferably a methyl ester, an ethyl ester, a butyl ester, or a glycol ester. A methyl ester is a compound having a "-(C=O)-O-CH3" structure in the molecule. An ethyl ester is a compound having a "-(C=O)-O-C2H5" structure in the molecule. A butyl ester is a compound having a "-(C=O)-O-C4H9" structure in the molecule. A glycol ester is a compound having a "-(C=O)-O-(CH2)" structure in the molecule. x It is a compound having the structure "-O-(X is 1 to 10)".

[0032] For example, alkyl esters represented by formulae (a1) to (a3) ​​can be used.

[0033] R a -(C=O)-OR b (a1) In formula (a1), R arepresents a hydrogen atom or an alkyl group. b represents an alkyl group, and is preferably a methyl group, an ethyl group, or a butyl group.

[0034] R c -O-(C=O)-R d -(C=O)-OR e (a2) In formula (a2), R c , R e R each independently represents an alkyl group, and is preferably a methyl group, an ethyl group, or a butyl group. d represents an alkylene group.

[0035] R f -(C=O)-OR g -O-(C=O)-R h (a3) In formula (a3), R f , R h R each independently represents a hydrogen atom or an alkyl group. g represents an alkylene group.

[0036] The alkyl ester is preferably an alkyl ester having 2 to 6 carbon atoms, and examples thereof include monoalkyl esters having 2 to 6 carbon atoms, dialkyl esters having 5 or 6 carbon atoms, and alkylene glycol alkyl esters having 4 to 6 carbon atoms.

[0037] Examples of the monoalkyl ester having 2 to 6 carbon atoms include those represented by the formula (a1): a and R b and monopropyl esters such as propyl formate, propyl acetate, propyl propionate, methyl butyrate, and methyl valerate; monoethyl esters such as ethyl formate, ethyl acetate, ethyl propionate, and ethyl butyrate; monopropyl esters such as propyl formate, propyl acetate, and propyl propionate; monobutyl esters such as butyl formate and butyl acetate; and monopentyl esters such as pentyl formate.

[0038] Examples of the dialkyl ester having 5 or 6 carbon atoms include those represented by the formula (a2): c and R d and R e The total number of carbon atoms in the esters may be 3 or 4. Specific examples include dimethyl esters such as dimethyl malonate, dimethyl methylmalonate, and dimethyl succinate; and methyl ethyl esters such as methyl ethyl malonate.

[0039] Examples of alkylene glycol alkyl esters having 4 to 6 carbon atoms include those represented by the formula (a3): f and R g and R h The total number of carbon atoms in the alkyl group may be 2 to 4. Specific examples include glycol esters such as ethylene diformate, methylene diacetate, and ethylene diacetate.

[0040] If the amount of alkyl ester used is small relative to the amount of polycarbonate resin used, the amount of solid (polycarbonate resin) relative to the liquid will be large, resulting in a high slurry concentration and poor mixing. Therefore, the molar ratio of alkyl ester to 1 mole of repeating unit of polycarbonate resin (i.e., repeating unit represented by the above general formula (1)) ((mass [g] of alkyl ester used / molecular weight [g / mol] of alkyl ester) / (mass [g] of polycarbonate resin used / molecular weight [g / mol] of repeating unit)) is preferably 0.01 or more, more preferably 0.03 or more. Furthermore, if the amount of alkyl ester used is large relative to the amount of polycarbonate resin used, production efficiency tends to deteriorate. Therefore, the molar ratio of alkyl ester to 1 mole of repeating unit of polycarbonate resin is preferably 100 or less, more preferably 70 or less, and even more preferably 50 or less.

[0041] (fatty alcohol) One of the features of the method for producing bisphenols of the present invention is the use of an aliphatic alcohol, which may be an aliphatic monoalcohol or a glycol.

[0042] Examples of the aliphatic monoalcohol include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, n-pentanol, i-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, n-undecanol, and n-dodecanol.

[0043] Examples of glycols include ethylene glycol and propylene glycol.

[0044] Among these, the aliphatic alcohol is preferably an alcohol having 1 to 5 carbon atoms, and more preferably any one selected from the group consisting of methanol, ethanol, butanol, and ethylene glycol.

[0045] If the amount of aliphatic alcohol used relative to the polycarbonate resin used is small, the polycarbonate resin becomes difficult to decompose or the decomposition rate decreases, resulting in a longer decomposition time and a decrease in efficiency. Therefore, the molar ratio of OH groups in the aliphatic alcohol to 1 mole of repeating units of the polycarbonate resin ((mass [g] of the aliphatic alcohol used × number of OH groups / molecular weight [g / mol] of the aliphatic alcohol) / (mass [g] of the polycarbonate resin used / molecular weight of the repeating unit [g / mol])) is preferably 0.1 or more, more preferably 0.5 or more, and even more preferably 1.0 or more. Furthermore, if the amount of aliphatic alcohol used relative to the polycarbonate resin used is large, production efficiency tends to decrease. Therefore, the molar ratio of OH groups in the aliphatic alcohol to 1 mole of repeating units of the polycarbonate resin is preferably 6.0 or less, more preferably 5.5 or less, and even more preferably 5.0 or less.

[0046] The decomposition of polycarbonate resin can be controlled by adjusting the amount of aliphatic alcohol and reaction time. When the structure of the decomposition product to be obtained is controlled by the amount of aliphatic alcohol, in order to efficiently produce dialkyl carbonate, the molar ratio of OH in the aliphatic alcohol to 1 mole of repeating units of the polycarbonate resin is preferably 2.0 or more, more preferably 2.1 or more, and even more preferably 2.2 or more.

[0047] Furthermore, the molar ratio of OH groups in the aliphatic alcohol to the alkyl ester (number of moles of aliphatic alcohol to be used × number of OH groups / number of moles of alkyl ester to be used) is preferably 0.01 or more, more preferably 0.05 or more. Furthermore, this molar ratio is preferably 1.0 or less, more preferably 0.95 or less, more preferably 0.90 or less, and more preferably 0.85 or less. If the molar ratio of OH groups in the aliphatic alcohol to the alkyl ester to be used is low, the polycarbonate resin becomes difficult to decompose, or the decomposition rate decreases, resulting in a long decomposition time. Furthermore, if this molar ratio is high, separation of the aliphatic alcohol and the alkyl ester becomes complicated when recovering the alkyl ester.

[0048] (catalyst) One of the features of the method for producing bisphenol of the present invention is the further use of a catalyst. The catalyst may be any catalyst capable of promoting the decomposition of polycarbonate resin, and is preferably any catalyst selected from the group consisting of alkali metal hydroxides, alkali metal alkoxides, alkali metal carbonates, alkali metal oxides, alkylamines, and pyridines.

[0049] [Alkali metal hydroxides] In the present invention, the alkali metal hydroxide is an alkali metal ion (M + ) and hydroxide ions (OH - ) and is a compound represented by MOH (M represents an alkali metal atom). As the alkali metal hydroxide, sodium hydroxide or potassium hydroxide is preferred.

[0050] If the amount of alkali metal hydroxide used relative to the polycarbonate resin used is small, the decomposition rate will be slow, the decomposition time will be long, and efficiency will tend to deteriorate. Therefore, the molar ratio of alkali metal hydroxide to 1 mole of repeating unit of polycarbonate resin ((mass [g] of alkali metal hydroxide used / molecular weight [g / mol] of alkali metal hydroxide) / (mass [g] of polycarbonate resin used / molecular weight of repeating unit [g / mol])) is preferably 0.0001 or more, more preferably 0.0005 or more, and even more preferably 0.0007 or more. For example, it can be 0.001 or more, 0.01 or more, etc. If the amount of alkali metal hydroxide used relative to the polycarbonate resin used is large, the amount of acid required for neutralization after decomposition will increase, and production efficiency will tend to decrease. Therefore, the molar ratio of alkali metal hydroxide to 1 mole of repeating unit of polycarbonate resin is preferably 1 or less, more preferably 0.9 or less, and even more preferably 0.8 or less.

[0051] [Alkali metal alkoxides] In the present invention, the alkali metal alkoxide is an alkali metal ion (M + ) and an aliphatic or aromatic alkoxide, and is a compound represented by the following formula (2). MOR H ··· Equation (2) In formula (2), M represents an alkali metal atom, preferably sodium or potassium. H represents an alkyl group or an aryl group, and is preferably an alkyl group having 1 to 5 carbon atoms or a phenyl group. As the alkali metal alkoxide, sodium phenoxide, sodium methoxide, sodium ethoxide, potassium phenoxide, potassium methoxide, potassium ethoxide, and potassium t-butoxide are more preferred.

[0052] If the amount of alkali metal alkoxide used relative to the polycarbonate resin used is small, the decomposition rate will be slow, the decomposition time will be long, and the efficiency will tend to deteriorate. Therefore, the molar ratio of alkali metal alkoxide to 1 mole of repeating unit of polycarbonate resin ((mass [g] of alkali metal alkoxide used / molecular weight [g / mol] of alkali metal alkoxide) / (mass [g] of polycarbonate resin used / molecular weight of repeating unit [g / mol])) is preferably 0.0001 or more, more preferably 0.0005 or more, and even more preferably 0.001 or more. For example, it can be 0.001 or more, 0.01 or more, etc. If the amount of alkali metal alkoxide used relative to the polycarbonate resin used is large, the amount of acid required for neutralization after decomposition will increase, and production efficiency will tend to decrease. Therefore, the molar ratio of alkali metal alkoxide to 1 mole of repeating unit of polycarbonate resin is preferably 1 or less, more preferably 0.9 or less, and even more preferably 0.8 or less.

[0053] [Alkali metal carbonates] In the present invention, the alkali metal carbonate is an alkali metal ion (M + ) and carbonate ions (CO3 2- ), and is a compound represented by M2CO3 or MHCO3 (M represents an alkali metal atom). As the alkali metal carbonate, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, etc. are preferred, and sodium carbonate or potassium carbonate is more preferred.

[0054] If the amount of alkali metal carbonate used relative to the polycarbonate resin used is small, the decomposition rate will be slow, the decomposition time will be long, and efficiency will tend to deteriorate. Therefore, the molar ratio of alkali metal carbonate to 1 mole of repeating unit of polycarbonate resin ((mass [g] of alkali metal carbonate used / molecular weight [g / mol] of alkali metal carbonate) / (mass [g] of polycarbonate resin used / molecular weight of repeating unit [g / mol])) is preferably 0.0001 or more, more preferably 0.0005 or more, and even more preferably 0.001 or more. For example, it can be 0.001 or more, 0.01 or more, etc. If the amount of alkali metal carbonate used relative to the polycarbonate resin used is large, the amount of acid required for neutralization after decomposition will increase, and production efficiency will tend to decrease. Therefore, the molar ratio of alkali metal carbonate to 1 mole of repeating unit of polycarbonate resin is preferably 1 or less, more preferably 0.9 or less, and even more preferably 0.8 or less.

[0055] [Alkali metal oxides] Examples of the alkali metal oxide include sodium oxide and potassium oxide.

[0056] If the amount of alkali metal oxide used relative to the polycarbonate resin used is small, the decomposition rate will be slow, the decomposition time will be long, and efficiency will tend to deteriorate. Therefore, the molar ratio of alkali metal oxide to 1 mole of repeating unit of polycarbonate resin ((mass [g] of alkali metal oxide used / molecular weight [g / mol] of alkali metal oxide) / (mass [g] of polycarbonate resin used / molecular weight [g / mol] of repeating unit of polycarbonate resin)) is preferably 0.0001 or more, more preferably 0.0005 or more, and even more preferably 0.001 or more. For example, it can be 0.001 or more or 0.01 or more. If the amount of alkali metal oxide used relative to the polycarbonate resin used is large, the amount of acid required for neutralization after decomposition will increase, and production efficiency will tend to decrease. Therefore, the molar ratio of alkali metal oxide to 1 mole of repeating unit of polycarbonate resin is preferably 1 or less, more preferably 0.9 or less, and even more preferably 0.8 or less.

[0057] [Alkylamine] In the present invention, an alkylamine is a compound having an amine structure in which at least one hydrogen atom of ammonia is substituted with an alkyl group. The alkylamine preferably has a boiling point of 200°C or less, more preferably 160°C or less. If the boiling point is within this range, it can be removed together with the alkyl ester by reducing pressure and / or heating. Furthermore, if the boiling point is too low, the alkylamine may volatilize during the decomposition reaction, resulting in a decrease in the decomposition rate. Therefore, the boiling point of the alkylamine is preferably 10°C or higher, more preferably 30°C or higher.

[0058] The alkylamine is preferably an alkylmonoamine or an alkyldiamine.

[0059] Among alkylamines, monoalkylmonoamines, which are primary amines, react with the carbonate bond portions of polycarbonate resins to produce isocyanates, so dialkylmonoamines, which are secondary amines, or trialkylmonoamines, which are tertiary amines, are more preferred. Dialkylmonoamines, which are secondary amines, react with the carbonate bond portions of polycarbonate resins to produce tetraalkylureas, so trialkylmonoamines, which are tertiary amines, are even more preferred.

[0060] The alkylamine is preferably an alkylmonoamine represented by the general formula (I).

[0061] [ka]

[0062] In general formula (I), R A represents an alkyl group having 1 to 3 carbon atoms, and R B ~R C each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. R A is preferably a methyl group, an ethyl group, an n-propyl group, or an i-propyl group, and R B ~R C are each independently preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or an i-propyl group.

[0063] Specific examples of the alkylamine represented by the general formula (I) include methylamine, ethylamine, propylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, and the like.

[0064] The alkylamine is preferably an alkyldiamine represented by the general formula (II).

[0065] [ka]

[0066] In general formula (II), R D ~R G each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and m represents an integer of 1 to 6. R D ~R G are each independently preferably a methyl group, an ethyl group, an n-propyl group, or an i-propyl group.

[0067] Specific examples of the alkylamine represented by general formula (II) include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, N-methylethylenediamine, N,N'-dimethylethylenediamine, N,N'-dimethyltrimethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N'-diethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, 1,3-diaminopropane, N-methyl-1,3-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, and N,N,N',N'-tetramethyl-1,3-diaminopropane.

[0068] If the amount of alkylamine used is small relative to the amount of polycarbonate resin used, the decomposition rate will be slow, the decomposition time will be long, and efficiency will tend to deteriorate. Therefore, the molar ratio of N of the amino group of the alkylamine to 1 mole of repeating unit of the polycarbonate resin ((mass [g] of alkylamine used × number of N of amino group / molecular weight of alkylamine [g / mol]) / (mass [g] of polycarbonate resin used / molecular weight of repeating unit [g / mol])) is preferably 0.0005 or more, more preferably 0.0007 or more, and even more preferably 0.001 or more. For example, it can be 0.01 or more, 0.1 or more, etc. If the amount of alkylamine used is large relative to the amount of polycarbonate resin used, an amine odor will be more likely to be generated and dialkyl carbonate will be less likely to be produced. Therefore, the molar ratio of N of the amino group of the alkylamine to 1 mole of the repeating unit of the polycarbonate resin is preferably 4.5 or less, and the smaller the ratio, the more preferred it is in the order of 4.0 or less, 3.0 or less, 2.0 or less, 1.0 or less, 0.9 or less, and 0.8 or less.

[0069] [Pyridine] In the present invention, pyridine may be unsubstituted or may have a substituent such as a methyl group or a hydroxyl group, and is preferably unsubstituted pyridine.

[0070] If the amount of pyridine used is small relative to the amount of polycarbonate resin used, the decomposition rate will be slow, the decomposition time will be long, and the efficiency will tend to deteriorate. Therefore, the molar ratio of pyridine to 1 mole of repeating unit of polycarbonate resin ((mass [g] of pyridine used / molecular weight [g / mol] of pyridine) / (mass [g] of polycarbonate resin used / molecular weight [g / mol] of repeating unit of polycarbonate resin)) is preferably 0.0005 or more, more preferably 0.0007 or more, and even more preferably 0.001 or more. For example, it can be 0.01 or more, 0.1 or more, etc. If the amount of pyridine used is large relative to the amount of polycarbonate resin used, odor will be more likely to be generated and dialkyl carbonate and condensation products will be less likely to be produced. Therefore, the molar ratio of pyridine to 1 mole of repeating units of the polycarbonate resin is preferably 4.5 or less, and the smaller the ratio, the more preferred it is in the order of 4.0 or less, 3.0 or less, 2.0 or less, 1.0 or less, 0.9 or less, and 0.8 or less.

[0071] (Reaction solution) The reaction solution prepared contains a polycarbonate resin, an alkyl ester, an aliphatic alcohol, and a catalyst. The reaction is preferably carried out in a slurry solution in which the polycarbonate resin is dispersed in a liquid component containing the alkyl ester and the aliphatic alcohol. The slurry concentration in the reaction solution (mass of solids in the reaction solution / mass of the reaction solution) is preferably 0.01 or more, more preferably 0.05 or more. It is also preferably 0.5 or less, more preferably 0.4 or less. If the slurry concentration (solid concentration) is too low, the decomposition efficiency will decrease, and if the slurry concentration is too high, mixing will be poor.

[0072] The liquid components in the prepared reaction liquid are mainly composed of alkyl esters and aliphatic alcohols, and the total mass of the alkyl esters and aliphatic alcohols relative to the mass of all liquid components is 0.8 or more, 0.9 or more, 0.95 or more, etc.

[0073] The total mass of the polycarbonate resin, alkyl ester, aliphatic alcohol, and catalyst relative to the mass of the reaction liquid can be 0.9 or more, 0.95 or more, 0.98 or more, 0.99 or more, etc. The reaction liquid may also consist of the polycarbonate resin, alkyl ester, aliphatic alcohol, and catalyst.

[0074] When attempting to obtain a dialkyl carbonate together with bisphenol, the presence of water in the reaction solution makes the produced dialkyl carbonate more likely to decompose. Therefore, the water content in the reaction solution (mass of water / mass of reaction solution) is usually 0.005 or less. The water content in the reaction solution is preferably 0.001 or less, more preferably 0.0005 or less.

[0075] (Preparation of reaction solution) The preparation of the reaction solution is preferably carried out at 10°C or higher, more preferably 20°C or higher. The preparation of the reaction solution is preferably carried out at 40°C or lower, more preferably 35°C or lower. If the temperature during preparation of the reaction solution is too low, some types of alkyl esters may be prone to solidification, leading to poor mixing or making it difficult to achieve uniform mixing. Furthermore, if the temperature during preparation of the reaction solution is too high, some types of catalysts may be prone to volatilization, making it difficult to prepare the desired concentration or to control the decomposition reaction.

[0076] The order of mixing the polycarbonate resin, alkyl ester, aliphatic alcohol, and catalyst is not particularly limited, and for example, the alkyl ester, aliphatic alcohol, and catalyst may be sequentially supplied to the polycarbonate resin, or the polycarbonate resin, aliphatic alcohol, and catalyst may be sequentially supplied to the alkyl ester. To achieve more uniform mixing, it is preferable to supply the polycarbonate resin to the reaction vessel after the alkyl ester and / or aliphatic alcohol.

[0077] (Decomposition reaction) In the presence of alkyl esters, aliphatic alcohols, and catalysts, the carbonate bonds in polycarbonate resins are cleaved, resulting in decomposition. This produces decomposition products such as bisphenols and dialkyl carbonates. By controlling the amount of alkyl esters and aliphatic alcohols and the reaction time, the decomposition reaction can be controlled, such as by preferentially producing bisphenols and dialkyl carbonates.

[0078] In order to prevent the decomposition reaction from proceeding during the preparation of the reaction solution (during the mixing of the polycarbonate resin, alkyl ester, aliphatic alcohol, and catalyst), the concentration of the polycarbonate resin and the temperature during the preparation of the reaction solution may be controlled to clearly separate the reaction solution preparation step from the decomposition reaction step, but the reaction solution preparation step and the decomposition step do not necessarily have to be clearly separated. The decomposition reaction of the polycarbonate resin may proceed during the preparation of the reaction solution, and a portion of the polycarbonate resin may be decomposed. By partially decomposing the polycarbonate resin during the preparation of the reaction solution, the decomposition reaction can proceed more efficiently.

[0079] The decomposition reaction may be carried out under normal pressure or under increased pressure, but is preferably carried out under normal pressure since the reaction proceeds sufficiently even under normal pressure.

[0080] (Reaction temperature) The reaction mixture may be prepared at the same temperature as when the reaction mixture was prepared until the decomposition reaction is terminated. However, it is preferable to raise the temperature to a predetermined reaction temperature after the reaction mixture is prepared (after mixing the polycarbonate resin, alkyl ester, aliphatic alcohol, and catalyst). If the temperature during the preparation of the reaction mixture is too high, it may be difficult to control the decomposition reaction. Raising the temperature after the preparation of the reaction mixture is preferable because it allows the decomposition reaction to proceed stably.

[0081] The reaction temperature (the decomposition temperature at which the polycarbonate is decomposed) is appropriately selected depending on the type of alkyl ester, reaction time, etc., but at high temperatures, the aliphatic alcohol in the reaction solution evaporates, and alcoholysis stops. At low temperatures, the alkyl ester solidifies, solvolysis proceeds more slowly, and the reaction rate decreases, resulting in a longer decomposition time. For these reasons, the reaction temperature is preferably 60°C or higher, with higher temperatures being more preferred in the order of 70°C or higher, 75°C or higher, and 80°C or higher. Also, 150°C or lower is preferred, with lower temperatures being more preferred in the order of 120°C or lower, 110°C or lower, 100°C or lower, and 95°C or lower.

[0082] In particular, the decomposition of polycarbonate resin is preferably carried out at a reaction temperature of 60 to 120°C under normal pressure, more preferably at a reaction temperature of 70 to 110°C under normal pressure, and even more preferably at a reaction temperature of 80 to 100°C under normal pressure.

[0083] When the reaction is carried out at the same temperature as that used for preparing the reaction solution, the reaction temperature is the average temperature from the time when mixing of the polycarbonate resin, alkyl ester, aliphatic alcohol, and catalyst is completed to the time when neutralization or distillation to terminate the decomposition reaction is started. When the reaction is carried out by raising the temperature after preparation of the reaction solution, the reaction temperature is the average temperature from the time when a predetermined temperature is reached to the time when neutralization or distillation to terminate the decomposition reaction is started.

[0084] (Reaction time) The reaction time is appropriately selected depending on the slurry concentration, reaction temperature, etc., but since a long reaction time tends to decompose the produced bisphenol, it is preferably 30 hours or less, and the shorter the reaction time, the more preferable it is in the order of 25 hours or less, 20 hours or less, 15 hours or less, 10 hours or less, and 5 hours or less. Furthermore, since a short reaction time may not allow the decomposition reaction to proceed sufficiently, the reaction time is preferably 0.1 hours or more, more preferably 0.5 hours or more, and even more preferably 1 hour or more.

[0085] The reaction time is the time from the completion of mixing the polycarbonate resin, alkyl ester, aliphatic alcohol, and catalyst to the start of neutralization and distillation to terminate the decomposition reaction. The end point of the reaction time may be determined by monitoring the decomposition reaction using liquid chromatography or the like.

[0086] (Method for stopping the decomposition reaction of polycarbonate resin) The method for terminating the decomposition reaction of polycarbonate resin is appropriately selected depending on the type of catalyst used. When an alkylamine or pyridine is used as the catalyst, the decomposition reaction can be terminated by distilling off or neutralizing the alkylamine or pyridine. In a method in which an acid is supplied and the alkylamine or pyridine is removed by neutralization, an ammonium salt or a pyridinium salt is generated, which must also be removed. Therefore, the alkylamine or pyridine is preferably removed by distillation. Furthermore, when an alkali metal hydroxide, alkali metal alkoxide, alkali metal carbonate, or the like is used as the catalyst, the decomposition reaction can be terminated by neutralization, etc.

[0087] In particular, the method for producing bisphenol of the present invention is suitable as a method for producing 2,2-bis(4-hydroxyphenyl)propane (hereinafter sometimes referred to as "bisphenol A").

[0088] (Bisphenol recovery) Bisphenol can be recovered from the reaction mixture after the decomposition reaction by means of crystallization, column chromatography, or the like after the decomposition reaction of the polycarbonate resin has been stopped.

[0089] Bisphenol is preferably recovered by crystallization, and the bisphenol production method of the present invention preferably includes a crystallization step for recovering bisphenol by crystallization. Specifically, after the decomposition reaction of the polycarbonate resin, the catalyst and solvent are removed from the reaction solution, and an organic solvent is added and mixed to obtain an organic phase, which is washed with water or saline, and further neutralized and washed with ammonium chloride water, if necessary. The washed organic phase is then cooled and crystallized.

[0090] Examples of organic solvents that can be used during neutralization and crystallization include aromatic hydrocarbons such as toluene, xylene, ethylbenzene, diethylbenzene, isopropylbenzene, and mesitylene; aliphatic hydrocarbons such as hexane, heptane, octane, nonane, decane, undecane, and dodecane; and aliphatic alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, n-pentanol, i-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, n-undecanol, n-dodecanol, ethylene glycol, diethylene glycol, and triethylene glycol.

[0091] Incidentally, prior to the crystallization, excess alkyl ester and organic solvent may be removed by distillation before the crystallization.

[0092] [Bisphenol manufacturing method (1)] The method for producing bisphenol of the present invention can be a method for producing bisphenol (1) including the following steps A, B1, and C1. Step A: A step of decomposing a polycarbonate resin in the presence of an alkyl ester, an aliphatic alcohol, and a catalyst to obtain a polycarbonate decomposition liquid containing bisphenol. Step B1: A step of concentrating the polycarbonate decomposition liquid obtained in Step A to obtain a concentrated liquid Step C1: A step of supplying an aromatic hydrocarbon to the concentrated liquid obtained in Step B1 to cause crystallization to precipitate bisphenol, obtaining a slurry containing bisphenol, and subjecting the obtained slurry to solid-liquid separation to obtain bisphenol.

[0093] Each step will be described in detail below.

[0094] [Process A] In step A, for example, a solution containing polycarbonate resin, alkyl ester, aliphatic alcohol, and a catalyst is stirred for a predetermined time. This decomposes the polycarbonate resin, produces bisphenol, and produces a polycarbonate decomposition liquid containing bisphenol. The types and mixing ratios of the polycarbonate resin, alkyl ester, aliphatic alcohol, and catalyst, as well as the reaction temperature, are as described above.

[0095] [Process B1] In step B1, the polycarbonate decomposition liquid can be concentrated by distilling off the solvent. The distillation is preferably carried out so that the concentrated liquid is 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less of the polycarbonate decomposition liquid. The distillation is also preferably carried out so that the concentrated liquid is 20% by mass or more, more preferably 30% by mass or more of the polycarbonate decomposition liquid. If the concentration is too high, the bisphenol solidifies, which can cause the problem of making it impossible to extract the concentrated liquid. For example, the distillation can be carried out at a temperature of 50 to 200°C and a pressure of 0.1 kPa to 150 kPa.

[0096] The polycarbonate decomposition liquid may be concentrated after neutralization and washing. The neutralization method may be appropriately selected depending on the type of catalyst. For example, when a basic catalyst is used, neutralization is carried out by mixing the polycarbonate decomposition liquid with an acid such as hydrochloric acid, sulfuric acid, or phosphoric acid. Neutralization is preferably carried out by adjusting the amount of acid to be mixed so that the pH is 5.5 to 9.0 (preferably pH 6.0 to 8.0). After mixing the polycarbonate decomposition liquid with the acid, the aqueous phase is removed, and if a neutralization salt precipitates, the neutralization salt is removed, thereby obtaining a neutralized liquid containing bisphenol. This neutralized liquid may be concentrated.

[0097] [Process C1] In step C1, the concentrated solution is mixed with an aromatic hydrocarbon, and bisphenol is precipitated by crystallization from the mixture containing the concentrated solution and the aromatic hydrocarbon. Examples of the aromatic hydrocarbon to be mixed with the concentrated solution include toluene, xylene, ethylbenzene, diethylbenzene, isopropylbenzene, and mesitylene, with toluene being preferred.

[0098] Crystallization can usually be carried out by cooling a mixed liquid containing the concentrated solution and aromatic hydrocarbon. For example, the temperature before crystallization is set to 60 to 100°C (preferably 70 to 90°C), and then cooled to 40 to 70°C (preferably 40 to 65°C). This causes bisphenol to precipitate in the mixed liquid, yielding a slurry containing bisphenol.

[0099] The bisphenol-containing slurry is then subjected to solid-liquid separation, allowing the bisphenol to be recovered as a solid content. Solid-liquid separation can be performed by known means such as filtration or centrifugation. For example, solid-liquid separation can be performed using a horizontal belt filter, a rotary vacuum filter, a rotary pressure filter, a batch filter, a centrifugal filtration separator, a centrifugal sedimentation separator, or a hybrid type centrifugal separator (screen ball decanter) thereof.

[0100] The obtained bisphenol may be further purified by washing with water, washing with suspension, etc. Crystallization may be performed multiple times. By dissolving the bisphenol obtained in step C1 in an aromatic hydrocarbon and crystallizing the resulting solution, it is possible to precipitate bisphenol with a higher purity.

[0101] [Bisphenol manufacturing method (2)] The method for producing bisphenol of the present invention can be a method for producing bisphenol (2) comprising the following steps A, B2, and C2. Step A: A step of decomposing a polycarbonate resin in the presence of an alkyl ester, an aliphatic alcohol, and a catalyst to obtain a polycarbonate decomposition liquid containing bisphenol. Step B2: A step of removing alkyl esters and aliphatic alcohols from the solution containing the polycarbonate decomposition liquid and aromatic monoalcohol obtained in Step A to obtain a solution containing bisphenols and aromatic monoalcohols. Step C2: A step of recovering bisphenol from the solution containing bisphenol and aromatic monoalcohol obtained in Step B

[0102] Each step will be described in detail below.

[0103] Step A in the bisphenol production method (2) is the same as step A in the bisphenol production method (1).

[0104] [Process B2] In step B2, the alkyl diester and aliphatic alcohol can be removed by distilling the solution containing the polycarbonate decomposition liquid and the aromatic monoalcohol. For example, the distillation can be carried out at a temperature of 50 to 200°C and a pressure of 0.1 kPa to 150 kPa. It is also preferable to remove at least a portion of the aromatic monoalcohol by distillation.

[0105] Furthermore, the polycarbonate decomposition liquid may be neutralized and washed before being subjected to the next step, as in step B1 of the bisphenol production method (1), or the polycarbonate decomposition liquid may be neutralized and washed before being mixed with an aromatic monoalcohol.

[0106] [Process C2] The bisphenol can be recovered from the solution containing the bisphenol and the aromatic monoalcohol obtained in step B2 by crystallization, etc. For example, when a polycarbonate resin derived from bisphenol A is used and phenol is used as the aromatic monoalcohol in step B2, a polycarbonate decomposition liquid containing bisphenol A is obtained in step A, and a solution containing bisphenol A and phenol is obtained in step B2. In step C2, this solution containing bisphenol A and phenol is crystallized to obtain adduct crystals of bisphenol A and phenol, and then phenol is removed from the melt of the adduct crystals to obtain bisphenol A. Alternatively, the solution containing bisphenol A and phenol may be incorporated into a reaction process, purification process, or mother liquor circulation process (a process of alkaline decomposition of bisphenol A in the mother liquor) of a production plant that produces bisphenol A from acetone and phenol, and crystallized together with the bisphenol A produced in the production plant to obtain adduct crystals of bisphenol A and phenol, and then phenol is removed from the melt of the adduct crystals to obtain bisphenol A.

[0107] <Uses of bisphenol> The bisphenol obtained by the bisphenol production method of the present invention (hereinafter, sometimes referred to as "recycled bisphenol") can be used as a constituent, curing agent, additive, or precursor thereof for various thermoplastic resins such as polyether resins, polyester resins, polyarylate resins, polycarbonate resins, polyurethane resins, and acrylic resins, and various thermosetting resins such as epoxy resins, unsaturated polyester resins, phenolic resins, polybenzoxazine resins, and cyanate resins, which are used in a variety of applications including optical materials, recording materials, insulating materials, transparent materials, electronic materials, adhesive materials, and heat-resistant materials. It is also useful as a color developer or additive for thermal recording materials, etc., such as a color-fading inhibitor, a disinfectant, and an antibacterial and antifungal agent.

[0108] Among these, it is preferably used as a raw material (monomer) for thermoplastic resins and thermosetting resins because it can impart good mechanical properties, and more preferably as a raw material for polycarbonate resins and epoxy resins. It is also preferably used as a color developer, and more preferably in combination with a leuco dye or a discoloration temperature regulator.

[0109] <Method for producing recycled polycarbonate resin of the present invention> The present invention relates to a method for producing a recycled polycarbonate resin (hereinafter sometimes referred to as the "method for producing a recycled polycarbonate resin of the present invention"), in which bisphenol is obtained through the bisphenol production method of the present invention, and then a bisphenol raw material containing the bisphenol (recycled bisphenol) is used to produce a recycled polycarbonate resin. The method for producing a recycled polycarbonate resin of the present invention utilizes a chemical recycling method in which polycarbonate resin is produced using recycled bisphenol as a raw material, which is obtained by decomposing polycarbonate resin contained in waste plastics, etc., into the bisphenol monomer.

[0110] The method for producing a polycarbonate resin of the present invention can be carried out by appropriately selecting a known method for polymerizing a polycarbonate resin, except that a bisphenol raw material containing recycled bisphenol is used as the bisphenol. Polycarbonate resins are generally produced by polymerizing a bisphenol and a carbonate diester in the presence of a catalyst.

[0111] In the method for producing recycled polycarbonate resin of the present invention, the recycled polycarbonate resin can be obtained, for example, by polymerizing a bisphenol raw material containing recycled bisphenol (bisphenol obtained by the method for producing bisphenol of the present invention) and a carbonate diester raw material.

[0112] For example, recycled polycarbonate resin can be produced by a method in which a bisphenol raw material containing recycled bisphenol is subjected to an ester exchange reaction with a carbonate diester raw material such as diphenyl carbonate in the presence of an alkali metal compound and / or an alkaline earth metal compound.

[0113] The recycled bisphenol may be used as the entire bisphenol raw material, or may be mixed with a non-recycled ordinary bisphenol and used as part of the bisphenol raw material. The amount of recycled bisphenol is not particularly limited, and may be any amount, such as 0.1% by mass or more, 1% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more. Since a higher proportion of recycled bisphenol is more environmentally friendly, from the viewpoint of environmental consideration, a higher amount of recycled bisphenol relative to the bisphenol raw material is preferable.

[0114] The above transesterification reaction can be carried out by appropriately selecting a known method, but an example of a method using diphenyl carbonate as the carbonate diester raw material will be described below.

[0115] In the method for producing recycled polycarbonate resin of the present invention, diphenyl carbonate is preferably used in excess relative to the bisphenol raw material. A large amount of diphenyl carbonate is preferred relative to the bisphenol raw material, as this reduces the number of terminal hydroxyl groups in the produced recycled polycarbonate resin and improves the thermal stability of the polymer. A small amount is preferred relative to the bisphenol raw material, as this increases the transesterification rate and facilitates the production of recycled polycarbonate resin with the desired molecular weight. For these reasons, the amount of diphenyl carbonate used relative to 1 mole of bisphenol raw material is typically 1.001 moles or more, preferably 1.002 moles or more, and typically 1.3 moles or less, preferably 1.2 moles or less.

[0116] As a method for supplying the raw materials, the bisphenol raw material and diphenyl carbonate can be supplied in solid form, but it is preferable to melt one or both of them and supply them in a liquid state.

[0117] When producing recycled polycarbonate resin by the transesterification reaction of diphenyl carbonate with a bisphenol raw material, a transesterification catalyst is usually used. It is preferable to use an alkali metal compound and / or an alkaline earth metal compound as the transesterification catalyst. These may be used alone or in any combination and ratio of two or more. For practical purposes, it is desirable to use an alkali metal compound.

[0118] The amount of catalyst used per mole of bisphenol raw material or diphenyl carbonate is usually 0.05 μmol or more, preferably 0.08 μmol or more, more preferably 0.10 μmol or more, and is usually 100 μmol or less, preferably 50 μmol or less, more preferably 20 μmol or less.

[0119] When the amount of catalyst used is within the above range, it is easy to obtain the polymerization activity required to produce a recycled polycarbonate resin of the desired molecular weight, and it is also easy to obtain a polycarbonate resin that has excellent polymer color, does not undergo excessive polymer branching, and has excellent fluidity during molding. To produce recycled polycarbonate resin by the above method, it is preferable to continuously feed both of the above raw materials into a raw material mixing tank, and then continuously feed the resulting mixture and the transesterification catalyst into a polymerization tank.

[0120] In the production of recycled polycarbonate resin by the transesterification method, the two raw materials are usually supplied to a raw material mixing tank, stirred uniformly, and then supplied to a polymerization tank where a catalyst is added to produce a polymer.

[0121] (Recycled polycarbonate resin and its composition) The recycled polycarbonate resin obtained by the method for producing recycled polycarbonate resin of the present invention may be used as is, or may be used as a recycled polycarbonate resin composition containing virgin polycarbonate resin and recycled polycarbonate resin. The recycled polycarbonate resin composition can be obtained by appropriately selecting a known kneading method or the like to mix virgin polycarbonate resin and recycled polycarbonate resin. When preparing a recycled polycarbonate resin composition containing virgin polycarbonate resin and recycled polycarbonate resin, there is no particular limitation on the amount of recycled polycarbonate resin, but the higher the proportion of recycled polycarbonate resin, the more environmentally friendly it is. Therefore, from the standpoint of environmental consideration, the amount of recycled polycarbonate resin relative to the recycled polycarbonate resin composition is preferably 50% by mass or more, and more preferably 70% by mass or more, 80% by mass or more, and 90% by mass or more in that order.

[0122] The resulting recycled polycarbonate resin or composition can be molded into various molded articles such as optical members and optical recording media, in the same manner as virgin polycarbonate resin.

[0123] <Epoxy resin manufacturing method> The present invention relates to a method for producing an epoxy resin, which comprises obtaining bisphenol through the method for producing bisphenol of the present invention, and then producing an epoxy resin using a polyhydric hydroxy compound raw material containing the bisphenol.The present invention also relates to a method for producing an epoxy resin, which comprises further reacting an epoxy resin raw material containing the epoxy resin obtained through the method for producing an epoxy resin with a polyhydric hydroxy compound raw material to produce an epoxy resin.

[0124] In the method for producing an epoxy resin of the present invention, an epoxy resin (hereinafter sometimes referred to as "recycled epoxy resin") is produced using recycled bisphenol and / or an epoxy resin produced using recycled bisphenol as at least a part of the raw materials.

[0125] The method for producing an epoxy resin of the present invention is not particularly limited, and known production methods can be used, except that recycled bisphenol (bisphenol obtained by the bisphenol production method of the present invention) and / or an epoxy resin produced using recycled bisphenol are used as raw materials. For example, as described below, recycled bisphenol can be used as at least a part of the polyvalent hydroxy compound raw material when producing using a one-stage method, an oxidation method, or a two-stage method. The obtained epoxy resin can also be used as at least a part of the epoxy resin raw material when producing using a two-stage method.

[0126] The term "epoxy resin raw material" refers to an epoxy resin used as a raw material in the method for producing an epoxy resin of the present invention. The term "polyhydric hydroxy compound" is a general term for dihydric or higher phenol compounds and dihydric or higher alcohol compounds, and the term "polyhydric hydroxy compound raw material" refers to a polyhydric hydroxy compound used as a raw material in the method for producing an epoxy resin of the present invention.

[0127] The epoxy resin of the present invention can be produced by a one-stage method, an oxidation method, a two-stage method, or the like. The one-step method for producing an epoxy resin is a method in which recycled bisphenol (bisphenol obtained by the method for producing bisphenol of the present invention) is reacted with epihalohydrin to obtain an epoxy resin. The oxidation method for producing epoxy resin involves allylation of recycled bisphenol with an allyl halide (allyl chloride, allyl bromide, etc.), followed by oxidation to obtain epoxy resin. The two-stage method for producing an epoxy resin is a method in which an epoxy resin raw material is reacted with a polyhydroxy compound raw material, and recycled bisphenol and / or an epoxy resin produced using recycled bisphenol are used as the raw material.

[0128] Hereinafter, methods for producing epoxy resins using the one-stage method, the oxidation method, and the two-stage method will be described.

[0129] (One-stage method for producing epoxy resin) In the present invention, the method for producing an epoxy resin by a one-step process is not particularly limited as long as it is a known production method, but will be described in detail below.

[0130] The one-stage method for producing an epoxy resin may involve using recycled bisphenol in combination with a polyhydric hydroxy compound other than recycled bisphenol (hereinafter, sometimes referred to as "another polyhydric hydroxy compound"). That is, the one-stage method for producing an epoxy resin involves reacting a polyhydric hydroxy compound raw material with epihalohydrin to obtain an epoxy resin, and at least a portion of the polyhydric hydroxy compound raw material can be recycled bisphenol.

[0131] The content of recycled bisphenol in the polyhydroxy compound raw material is not particularly limited, but since a high content of recycled bisphenol is environmentally friendly, it is preferably 1 to 100 mass %, more preferably 10 to 100 mass %.

[0132] Here, "other polyhydric hydroxy compounds" is a general term for divalent or higher phenol compounds and divalent or higher alcohol compounds, excluding recycled bisphenols. In the one-stage method for producing epoxy resins, the "raw polyhydric hydroxy compound" refers to all polyhydric hydroxy compounds, including recycled bisphenols and other polyhydric hydroxy compounds used as needed.

[0133] Other polyhydric hydroxy compounds include various polyhydric phenols such as bisphenol A, tetramethylbisphenol A, bisphenol F, tetramethylbisphenol F, bisphenol S, bisphenol C, bisphenol AD, bisphenol AF, hydroquinone, resorcinol, methylresorcinol, biphenol, tetramethylbiphenol, dihydroxynaphthalene, dihydroxydiphenyl ether, thiodiphenols, phenol novolac resin, cresol novolac resin, phenol aralkyl resin, biphenyl aralkyl resin, naphthol aralkyl resin, terpene phenol resin, dicyclopentadiene phenol resin, bisphenol A novolac resin, naphthol novolac resin, brominated bisphenol A, brominated phenol novolac resin, and various phenols and benzaldehyde, hydroxybenzaldehyde, and the like. Examples of the polyhydric phenol resin include polyhydric phenol resins obtained by a condensation reaction between various aldehydes such as benzoxaldehyde, crotonaldehyde, and glyoxal; polyhydric phenol resins obtained by a condensation reaction between xylene resin and phenols; various phenol resins such as co-condensation resins of heavy oils or pitches with phenols and formaldehydes; chain aliphatic diols such as ethylene glycol, trimethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, and 1,6-hexanediol; cyclic aliphatic diols such as cyclohexanediol and cyclodecanediol; and polyalkylene ether glycols such as polyethylene ether glycol, polyoxytrimethylene ether glycol, and polypropylene ether glycol.

[0134] In the reaction, the polyhydric hydroxy compound raw material is dissolved in epihalohydrin to form a homogeneous solution. As the epihalohydrin, epichlorohydrin or epibromohydrin is usually used, but epichlorohydrin is preferred in the present invention.

[0135] The amount of epihalohydrin used is preferably an amount corresponding to typically 1.0 to 14.0 equivalents, particularly 2.0 to 10.0 equivalents, per equivalent of hydroxyl groups in the polyhydric hydroxy compound raw material (total polyhydric hydroxy compounds). When the amount of epihalohydrin is equal to or greater than the lower limit, it is easy to control the polymerization reaction, and the resulting epoxy resin can have an appropriate epoxy equivalent, which is preferred. On the other hand, when the amount of epihalohydrin is equal to or less than the upper limit, production efficiency tends to be improved, which is preferred.

[0136] Next, while stirring the solution, an alkali metal hydroxide is added as a solid or in aqueous solution in an amount corresponding to typically 0.1 to 3.0 equivalents, preferably 0.8 to 2.0 equivalents, per equivalent of hydroxyl groups in the polyhydric hydroxy compound raw material, and the reaction is allowed to proceed. Adding an amount of alkali metal hydroxide equal to or greater than the lower limit described above is preferred because the unreacted hydroxyl groups are less likely to react with the resulting epoxy resin, making it easier to control the polymerization reaction. Adding an amount of alkali metal hydroxide equal to or less than the upper limit described above is also preferred because impurities due to side reactions are less likely to be generated. The alkali metal hydroxide used here typically includes sodium hydroxide or potassium hydroxide.

[0137] This reaction can be carried out under normal pressure or reduced pressure, and the reaction temperature is preferably 20 to 200°C, more preferably 40 to 150°C. A reaction temperature equal to or higher than the lower limit is preferred because the reaction is easily progressed and easily controlled. On the other hand, a reaction temperature equal to or lower than the upper limit is preferred because side reactions are less likely to proceed, and it is particularly easy to reduce the amount of polymer.

[0138] This reaction is also carried out while dehydrating, if necessary, by azeotroping the reaction solution while maintaining a predetermined temperature, cooling the volatilized vapor, separating the resulting condensate into oil and water, and returning the dehydrated oil to the reaction system. To prevent a rapid reaction, the alkali metal hydroxide is added intermittently or continuously in small amounts over a period of preferably 0.1 to 24 hours, more preferably 0.5 to 10 hours. Adding the alkali metal hydroxide for a period of time equal to or greater than the above-mentioned lower limit is preferred because it prevents the reaction from proceeding too quickly and makes it easier to control the reaction temperature. Adding the alkali metal hydroxide for a period of time equal to or less than the above-mentioned upper limit is preferred because it makes it easier to reduce the amount of polymer.

[0139] After the reaction is completed, the insoluble by-product salts are removed by filtration or by washing with water, and then the unreacted epihalohydrin can be removed by heating and / or distillation under reduced pressure.

[0140] In addition, in this reaction, a catalyst such as a quaternary ammonium salt such as tetramethylammonium chloride or tetraethylammonium bromide, a tertiary amine such as benzyldimethylamine or 2,4,6-tris(dimethylaminomethyl)phenol, an imidazole such as 2-ethyl-4-methylimidazole or 2-phenylimidazole, a phosphonium salt such as ethyltriphenylphosphonium iodide, or a phosphine such as triphenylphosphine may be used.

[0141] Furthermore, in this reaction, an inert organic solvent may be used, such as alcohols such as ethanol and isopropanol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ethers such as dioxane and ethylene glycol dimethyl ether; glycol ethers such as methoxypropanol; and aprotic polar solvents such as dimethyl sulfoxide and dimethylformamide.

[0142] [Production of epoxy resin with reduced total chlorine content] When it is necessary to reduce the total chlorine content of the epoxy resin obtained as described above, an epoxy resin having a reduced total chlorine content can be produced by reacting it with an alkali.

[0143] The reaction with the alkali may be carried out using an organic solvent for dissolving the epoxy resin. The organic solvent used in the reaction is not particularly limited, but it is preferable to use a ketone-based organic solvent in terms of production efficiency, handling, workability, etc. Furthermore, an aprotic polar solvent may be used in order to further reduce the amount of hydrolyzable chlorine.

[0144] Examples of ketone-based organic solvents include ketone-based solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Methyl isobutyl ketone is particularly preferred because of its effectiveness and ease of post-treatment. These solvents may be used alone or in combination of two or more.

[0145] Examples of aprotic polar solvents include dimethyl sulfoxide, diethyl sulfoxide, dimethyl sulfone, sulfolane, dimethylformamide, dimethylacetamide, and hexamethylphosphoramide. These may be used alone or in combination of two or more. Among these aprotic polar solvents, dimethyl sulfoxide is preferred because it is easily available and has excellent effects.

[0146] The amount of the solvent used is such that the concentration of the epoxy resin in the liquid to be subjected to the alkali treatment is usually 1 to 95% by mass, and preferably 5 to 80% by mass.

[0147] As the alkali, a solid or solution of an alkali metal hydroxide can be used. Examples of the alkali metal hydroxide include potassium hydroxide and sodium hydroxide, and sodium hydroxide is preferred. The alkali metal hydroxide may also be dissolved in an organic solvent or water. Preferably, the alkali metal hydroxide is used as a solution in which it is dissolved in a water solvent or an organic solvent.

[0148] The amount of alkali metal hydroxide used is preferably 0.01 to 20.0 parts by mass or less, and more preferably 0.10 to 10.0 parts by mass, relative to 100 parts by mass of the epoxy resin, calculated as the solid content of the alkali metal hydroxide. If the amount of alkali metal hydroxide used is less than the lower limit, the effect of reducing the total chlorine content is low, and if it is more than the upper limit, a large amount of polymer is produced, resulting in a low yield.

[0149] The reaction temperature is preferably 20 to 200°C, more preferably 40 to 150°C, and the reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 10 hours.

[0150] After the reaction, excess alkali metal hydroxide and secondary salts can be removed by washing with water or the like, and the organic solvent can be further removed by heating and / or distillation under reduced pressure and / or steam distillation.

[0151] (Oxidation method for producing epoxy resin) The method for producing an epoxy resin by oxidation is not particularly limited as long as it is a known production method, and can be carried out according to, for example, the methods described in JP-A-2011-225711, JP-A-2012-092247, JP-A-2012-111858, etc.

[0152] In the oxidation method for producing an epoxy resin, similar to the one-stage method, a polyhydric hydroxy compound other than the recycled bisphenol may be used in combination with the recycled bisphenol. That is, the oxidation method for producing an epoxy resin is a method in which a raw polyhydric hydroxy compound is allylated with an allyl halide, followed by an oxidation reaction to obtain an epoxy resin, and at least a portion of the raw polyhydric hydroxy compound is recycled bisphenol.

[0153] In the oxidation method for producing an epoxy resin, the "raw polyhydroxy compound" refers to all polyhydroxy compounds, including recycled bisphenols and other polyhydroxy compounds used as needed. Examples of the other polyhydroxy compounds include those similar to those used in the one-stage method. The content of recycled bisphenols in the raw polyhydroxy compound is not particularly limited, but a high content of recycled bisphenols is environmentally friendly, so a content of 1 to 100% by mass is preferred, and 10 to 100% by mass is more preferred.

[0154] (Two-stage method for producing epoxy resin) The method for producing an epoxy resin by the two-stage method is not particularly limited as long as it is a known production method, but will be described in detail below.

[0155] The two-stage method for producing an epoxy resin includes a step of reacting an epoxy resin raw material with a polyhydric hydroxy compound raw material, and at least a part of the epoxy resin raw material is an epoxy resin produced using recycled bisphenol, and / or at least a part of the polyhydric hydroxy compound raw material is recycled bisphenol. The two-stage method for producing an epoxy resin is any of the following methods (i) to (iii).

[0156] Method (i): A method of reacting an epoxy resin other than an epoxy resin produced using recycled bisphenol with a polyhydroxy compound raw material containing recycled bisphenol.

[0157] In method (i), the epoxy resin raw material is an epoxy resin other than the epoxy resin produced using recycled bisphenol, and the polyhydroxy compound raw material is all polyhydroxy compounds including recycled bisphenol and other polyhydroxy compounds used as needed.

[0158] Method (ii): A method of reacting an epoxy resin raw material containing an epoxy resin produced using recycled bisphenol with a polyhydroxy compound raw material containing recycled bisphenol.

[0159] In method (ii), the epoxy resin raw material is the total epoxy resin, which is a combination of the epoxy resin produced using recycled bisphenol and other epoxy resins used as needed, and the polyhydroxy compound raw material is the total polyhydroxy compound, which is a combination of the recycled bisphenol and other polyhydroxy compounds used as needed.

[0160] Method (iii): A method of reacting an epoxy resin raw material containing an epoxy resin produced using recycled bisphenol with a polyhydroxy compound other than recycled bisphenol.

[0161] In method (iii), the epoxy resin raw material is a total epoxy resin that combines the epoxy resin produced using recycled bisphenol with other epoxy resins that are used as needed, and the polyhydroxy compound raw material is a polyhydroxy compound other than recycled bisphenol.

[0162] The epoxy resins produced using recycled bisphenols used in methods (ii) and (iii) can be obtained by a one-step method for producing epoxy resins or an oxidation method for producing epoxy resins. Alternatively, the epoxy resins obtained by method (i) may be used. The epoxy resins other than the epoxy resins produced using recycled bisphenols are the same as the other epoxy resins described later in the method for producing a cured epoxy resin, and the other polyhydroxy compounds are the same as those used in the one-step method.

[0163] In the methods (i) and (ii), the content of recycled bisphenol in the polyhydroxy compound containing recycled bisphenol is not particularly limited, but a high content of recycled bisphenol is environmentally friendly, so it is preferably 1 to 100 mass%, more preferably 10 to 100 mass%. In the methods (ii) and (iii), the content of the epoxy resin produced using recycled bisphenol in the epoxy resin raw material containing the epoxy resin produced using recycled bisphenol is not particularly limited, but since a high content of the epoxy resin produced using recycled bisphenol is environmentally friendly, it is preferably 1 to 100 mass%, more preferably 10 to 100 mass%.

[0164] In the two-stage reaction, the amounts of the epoxy resin raw material and the polyvalent hydroxy compound raw material used are preferably such that the equivalent ratio (epoxy group equivalent):(hydroxyl group equivalent) is 1:0.1-2.0, more preferably 1:0.2-1.2. When this equivalent ratio is within the above range, it is easy to promote high molecular weight and more epoxy group terminals can be left, which is preferable.

[0165] A catalyst may be used in the two-stage reaction. Any compound with catalytic activity that promotes the reaction between an epoxy group and a phenolic hydroxyl group or an alcoholic hydroxyl group may be used. Examples of the catalyst include alkali metal compounds, organic phosphorus compounds, tertiary amines, quaternary ammonium salts, cyclic amines, and imidazoles. Among these, quaternary ammonium salts are preferred. A single catalyst may be used, or two or more catalysts may be used in combination. The amount of catalyst used is typically 0.001 to 10% by mass based on the epoxy resin raw material.

[0166] A solvent may be used in the two-stage reaction, and any solvent capable of dissolving the epoxy resin raw material may be used. Examples include aromatic solvents, ketone solvents, amide solvents, and glycol ether solvents. A single solvent may be used, or two or more solvents may be used in combination. The resin concentration in the solvent is preferably 10 to 95% by mass, more preferably 20 to 80% by mass. If a highly viscous product is produced during the reaction, the reaction can be continued by adding additional solvent. After completion of the reaction, the solvent can be removed or further added as necessary.

[0167] In the two-stage reaction, the reaction temperature is preferably 20 to 250°C, more preferably 50 to 200°C. If the reaction temperature is above the upper limit, the resulting epoxy resin may deteriorate. If the reaction temperature is below the lower limit, the reaction may not proceed sufficiently. The reaction time is usually 0.1 to 24 hours, preferably 0.5 to 12 hours.

[0168] <Method of manufacturing a cured epoxy resin product> The method for producing a cured epoxy resin product of the present invention involves obtaining an epoxy resin through the above-described method for producing an epoxy resin, obtaining a composition containing the epoxy resin and a curing agent (hereinafter, sometimes referred to as an "epoxy resin composition"), and then curing the epoxy resin composition to obtain a cured epoxy resin product.

[0169] Furthermore, if necessary, the epoxy resin composition may appropriately contain other epoxy resins (hereinafter simply referred to as "other epoxy resins") other than the epoxy resin obtained by the epoxy resin production method of the present invention, curing agents, curing accelerators, inorganic fillers, coupling agents, etc.

[0170] The content of recycled epoxy resin in the epoxy resin composition is not particularly limited. Because a high content of recycled epoxy resin is environmentally friendly, the recycled epoxy resin is preferably 40 parts by mass or more, more preferably 60 parts by mass or more, per 100 parts by mass of all epoxy resin components in the epoxy resin composition. When other epoxy resins are included, the recycled epoxy resin may be present in an amount of 40 to 99 parts by mass or 60 to 99 parts by mass, per 100 parts by mass of all epoxy resin components in the epoxy resin composition. The term "total epoxy resin components" refers to the total amount of all epoxy resins contained in the epoxy resin composition, including the recycled epoxy resin and other epoxy resins used as needed.

[0171] (hardening agent) In the present invention, a curing agent refers to a substance that contributes to the crosslinking reaction and / or chain extension reaction between epoxy groups of an epoxy resin. In the present invention, even substances that are usually called "curing accelerators" are considered to be curing agents as long as they contribute to the crosslinking reaction and / or chain extension reaction between epoxy groups of an epoxy resin.

[0172] In the epoxy resin composition, the content of the curing agent is preferably 0.1 to 1000 parts by mass, more preferably 500 parts by mass or less, based on 100 parts by mass of the total epoxy resin components.

[0173] The curing agent is not particularly limited, and any commonly known epoxy resin curing agent can be used. Examples include phenolic curing agents, amine curing agents such as aliphatic amines, polyetheramines, alicyclic amines, and aromatic amines, acid anhydride curing agents, amide curing agents, tertiary amines, and imidazoles. One type of curing agent may be used alone, or two or more types may be used in combination. When two or more types of curing agents are used in combination, they may be mixed in advance to prepare a mixed curing agent before use, or each component of the curing agent may be added separately and mixed simultaneously when mixing the recycled epoxy resin obtained by the epoxy resin production method of the present invention and the components of other epoxy resins.

[0174] [Phenol-based hardener] Specific examples of phenolic curing agents include recycled bisphenol, bisphenol A, tetramethyl bisphenol A, bisphenol F, tetramethyl bisphenol F, bisphenol C, bisphenol S, bisphenol AD, bisphenol AF, hydroquinone, resorcinol, methyl resorcinol, biphenol, tetramethyl biphenol, dihydroxynaphthalene, dihydroxydiphenyl ether, thiodiphenols, phenol novolac resin, cresol novolac resin, phenol aralkyl resin, biphenyl aralkyl resin, naphthol aralkyl resin, terpene phenol resin, dicyclopentadiene phenol resin, bisphenol A novolac resin, trisphenolmethane type resin, naphthol novolac resin, brominated bisphenol These include various polyhydric phenols such as phenol A and brominated phenol novolac resins; polyhydric phenol resins obtained by the condensation reaction of various phenols with various aldehydes such as benzaldehyde, hydroxybenzaldehyde, crotonaldehyde, and glyoxal; polyhydric phenol resins obtained by the condensation reaction of xylene resin and phenols; co-condensation resins of heavy oil or pitch with phenols and formaldehydes; and various phenolic resins such as phenol-benzaldehyde-xylylene dimethoxide polycondensates, phenol-benzaldehyde-xylylene dihalide polycondensates, phenol-benzaldehyde-4,4'-dimethoxide biphenyl polycondensates, and phenol-benzaldehyde-4,4'-dihalide biphenyl polycondensates.

[0175] These phenolic curing agents may be used alone or in any combination of two or more in any blending ratio.

[0176] The amount of the phenolic curing agent to be added is preferably 0.1 to 1000 parts by mass, and more preferably 500 parts by mass or less, per 100 parts by mass of all epoxy resin components in the epoxy resin composition.

[0177] [Amine-based curing agent] Examples of amine-based curing agents (excluding tertiary amines) include aliphatic amines, polyether amines, alicyclic amines, and aromatic amines.

[0178] Examples of aliphatic amines include ethylenediamine, 1,3-diaminopropane, 1,4-diaminopropane, hexamethylenediamine, 2,5-dimethylhexamethylenediamine, trimethylhexamethylenediamine, diethylenetriamine, iminobispropylamine, bis(hexamethylene)triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, N-hydroxyethylethylenediamine, and tetra(hydroxyethyl)ethylenediamine.

[0179] Examples of polyetheramines include triethylene glycol diamine, tetraethylene glycol diamine, diethylene glycol bis(propylamine), polyoxypropylene diamine, polyoxypropylene triamines, and the like.

[0180] Examples of alicyclic amines include isophoronediamine, methacenediamine, N-aminoethylpiperazine, bis(4-amino-3-methyldicyclohexyl)methane, bis(aminomethyl)cyclohexane, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro(5,5)undecane, and norbornenediamine.

[0181] Examples of aromatic amines include tetrachloro-p-xylylenediamine, m-xylylenediamine, p-xylylenediamine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, 2,4-diaminoanisole, 2,4-toluenediamine, 2,4-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diamino-1,2-diphenylethane, 2,4-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, m-aminophenol, m-aminobenzylamine, benzyldimethylamine, 2-(dimethylaminomethyl)phenol, triethanolamine, methylbenzylamine, α-(m-aminophenyl)ethylamine, α-(p-aminophenyl)ethylamine, diaminodiethyldimethyldiphenylmethane, and α,α'-bis(4-aminophenyl)-p-diisopropylbenzene.

[0182] The amine-based curing agents listed above may be used alone or in any combination of two or more in any blending ratio.

[0183] The amine-based curing agent is preferably used so that the equivalent ratio of functional groups in the curing agent to epoxy groups in all epoxy resin components contained in the epoxy resin composition is in the range of 0.1 to 2.0. More preferably, the equivalent ratio is in the range of 0.8 to 1.2. This range is preferable because unreacted epoxy groups and functional groups of the curing agent are less likely to remain.

[0184] [Tertiary amine] Examples of tertiary amines include 1,8-diazabicyclo(5,4,0)undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol. The above-mentioned tertiary amines may be used alone or in any combination of two or more kinds in any blending ratio.

[0185] The above tertiary amine is preferably used so that the equivalent ratio of the functional groups in the curing agent to the epoxy groups in all epoxy resin components contained in the epoxy resin composition is in the range of 0.1 to 2.0. More preferably, the equivalent ratio is in the range of 0.8 to 1.2. This range is preferable because it makes it difficult for unreacted epoxy groups or functional groups of the curing agent to remain.

[0186] [Acid anhydride curing agent] Examples of the acid anhydride curing agent include acid anhydrides and modified acid anhydrides.

[0187] Examples of acid anhydrides include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, dodecenylsuccinic anhydride, polyadipic anhydride, polyazelaic anhydride, polysebacic anhydride, poly(ethyloctadecanedioic) anhydride, poly(phenylhexadecanedioic) anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, methylhimic anhydride, trialkyltetrahydrophthalic anhydride, Examples of the dicarboxylic acid anhydride include methylcyclohexene dicarboxylic acid anhydride, methylcyclohexene tetracarboxylic acid anhydride, ethylene glycol bistrimellitate dianhydride, HET anhydride, Nadic anhydride, methylnadic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexane-1,2-dicarboxylic acid anhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride, and 1-methyl-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride.

[0188] Examples of modified acid anhydrides include those obtained by modifying the above-mentioned acid anhydrides with glycols. Examples of glycols that can be used for modification include alkylene glycols such as ethylene glycol, propylene glycol, and neopentyl glycol, and polyether glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol. Furthermore, copolymer polyether glycols of two or more of these glycols and / or polyether glycols can also be used.

[0189] The acid anhydride curing agents listed above may be used alone or in any combination of two or more in any amount.

[0190] When an acid anhydride curing agent is used, it is preferably used so that the equivalent ratio of functional groups in the curing agent to epoxy groups in all epoxy resin components in the epoxy resin composition is in the range of 0.1 to 2.0. More preferably, the equivalent ratio is in the range of 0.8 to 1.2. This range is preferable because it makes it difficult for unreacted epoxy groups or functional groups of the curing agent to remain.

[0191] [Amide-based curing agent] Examples of the amide-based curing agent include dicyandiamide and its derivatives, polyamide resins, and the like. The amide curing agent may be used alone or in any combination and ratio of two or more kinds. When an amide curing agent is used, it is preferable to use the amide curing agent in an amount of 0.1 to 20 mass % based on the total amount of all epoxy resin components and the amide curing agent in the epoxy resin composition.

[0192] [Imidazoles] Examples of imidazoles include 2-phenylimidazole, 2-ethyl-4(5)-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyano-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl- Examples of such imidazoles include 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and adducts of epoxy resins with the above imidazoles. Note that, since imidazoles have catalytic activity, they can generally be classified as curing accelerators, but in the present invention they are classified as curing agents. The imidazoles listed above may be used alone or in any combination and ratio of two or more.

[0193] When imidazoles are used, the amount of imidazoles is preferably 0.1 to 20% by mass based on the total amount of all epoxy resin components and imidazoles in the epoxy resin composition.

[0194] [Other hardeners] In addition to the above-mentioned curing agents, other curing agents can be used in the epoxy resin composition. There are no particular restrictions on the other curing agents that can be used in the epoxy resin composition, and any curing agent generally known as a curing agent for epoxy resins can be used. These other curing agents may be used alone or in combination of two or more.

[0195] [Other epoxy resins] The epoxy resin composition may contain an epoxy resin other than the epoxy resin obtained by the epoxy resin production method of the present invention. By containing the other epoxy resin, various physical properties can be improved.

[0196] Other epoxy resins that can be used in the epoxy resin composition include all epoxy resins other than those obtained by the epoxy resin production method of the present invention. Specific examples include bisphenol A type epoxy resins, bisphenol C type epoxy resins, trisphenolmethane type epoxy resins, anthracene type epoxy resins, phenol-modified xylene resin type epoxy resins, bisphenol cyclododecyl type epoxy resins, bisphenol diisopropylidene resorcinol type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type epoxy resins, bisphenol AF type epoxy resins, hydroquinone type epoxy resins, methylhydroquinone type epoxy resins, dibutylhydroquinone type epoxy resins, resorcinol type epoxy resins, methylresorcinol type epoxy resins, biphenol type epoxy resins, tetramethylbiphenol type epoxy resins, tetramethylbisphenol F type epoxy resins, dihydroxydiphenyl ether type epoxy resins, epoxy resins derived from thiodiphenols, dihydroxynaphthalene type epoxy resins, dihydroxyanthracene type epoxy resins, dihydroxydihydroanthracene type epoxy resins, dicyclopentadiene type epoxy resins, dihydrogen Examples of epoxy resins include epoxy resins derived from roxystilbenes, phenol novolac epoxy resins, cresol novolac epoxy resins, bisphenol A novolac epoxy resins, naphthol novolac epoxy resins, phenol aralkyl epoxy resins, naphthol aralkyl epoxy resins, biphenyl aralkyl epoxy resins, terpene phenol epoxy resins, dicyclopentadiene phenol epoxy resins, epoxy resins derived from phenol-hydroxybenzaldehyde condensates, epoxy resins derived from phenol-crotonaldehyde condensates, epoxy resins derived from phenol-glyoxal condensates, epoxy resins derived from co-condensation resins of heavy oils or pitches with phenols and formaldehydes, epoxy resins derived from diaminodiphenylmethane, epoxy resins derived from aminophenols, epoxy resins derived from xylenediamine, epoxy resins derived from methylhexahydrophthalic acid, and epoxy resins derived from dimer acids.These may be used alone or in any combination of two or more in any blending ratio.

[0197] When the epoxy resin composition contains the other epoxy resins described above, the content thereof is preferably 1 to 60 parts by mass, more preferably 40 parts by mass or less, per 100 parts by mass of all epoxy resin components in the composition.

[0198] (curing accelerator) The epoxy resin composition preferably contains a curing accelerator, which enables shortening of the curing time and lowering of the curing temperature, making it easier to obtain a desired cured product.

[0199] The curing accelerator is not particularly limited, but specific examples include organic phosphines, phosphorus compounds such as phosphonium salts, tetraphenylboron salts, organic acid dihydrazides, boron halide amine complexes, and the like.

[0200] Phosphorus compounds that can be used as curing accelerators include triphenylphosphine, diphenyl(p-tolyl)phosphine, tris(alkylphenyl)phosphine, tris(alkoxyphenyl)phosphine, tris(alkylalkoxyphenyl)phosphine, tris(dialkylphenyl)phosphine, tris(trialkylphenyl)phosphine, tris(tetraalkylphenyl)phosphine, tris(dialkoxyphenyl)phosphine, tris(trialkoxyphenyl)phosphine, tris(tetraalkoxyphenyl)phosphine, trialkylphosphine, Examples of such phosphines include organic phosphines such as phosphine, dialkylarylphosphine, and alkyldiarylphosphine; complexes of these organic phosphines with organic borons; and compounds obtained by adding these organic phosphines to quinone compounds such as maleic anhydride, 1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, and phenyl-1,4-benzoquinone; and compounds such as diazophenylmethane.

[0201] Among the curing accelerators listed above, organic phosphines and phosphonium salts are preferred, and organic phosphines are most preferred. The curing accelerators listed above may be used alone or in any combination and ratio of two or more.

[0202] The curing accelerator is preferably used in an amount of 0.1 to 20 parts by mass relative to 100 parts by mass of all epoxy resin components in the epoxy resin composition. When the content of the curing accelerator is equal to or greater than the lower limit, a good curing acceleration effect can be obtained, while when the content is equal to or less than the upper limit, the desired cured physical properties can be easily obtained, which is preferred.

[0203] (Inorganic filler) The epoxy resin composition can contain an inorganic filler. Examples of inorganic fillers include fused silica, crystalline silica, glass powder, alumina, calcium carbonate, calcium sulfate, talc, and boron nitride. These may be used alone or in any combination of two or more in any ratio. The amount of inorganic filler to be used is preferably 10 to 95% by mass of the total epoxy resin composition.

[0204] (mold release agent) A mold release agent can be blended into the epoxy resin composition. Examples of mold release agents that can be used include natural waxes such as carnauba wax, synthetic waxes such as polyethylene wax, higher fatty acids such as stearic acid and zinc stearate and their metal salts, and hydrocarbon-based mold release agents such as paraffin. These may be used alone or in any combination of two or more types in any blending ratio.

[0205] The amount of the release agent is preferably 0.001 to 10.0 parts by mass relative to 100 parts by mass of all epoxy resin components in the epoxy resin composition. When the amount of the release agent is within the above range, good release properties can be exhibited while maintaining curing properties, which is preferable.

[0206] (coupling agent) A coupling agent can be blended into the epoxy resin composition. The coupling agent is preferably used in combination with an inorganic filler, and blending of the coupling agent can improve the adhesion between the epoxy resin matrix and the inorganic filler. Examples of the coupling agent include a silane coupling agent and a titanate coupling agent.

[0207] Examples of the silane coupling agent include epoxy silanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino silanes such as γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, and γ-ureidopropyltriethoxysilane; mercapto silanes such as 3-mercaptopropyltrimethoxysilane; vinyl silanes such as p-styryltrimethoxysilane, vinyltrichlorosilane, vinyltris(β-methoxyethoxy)silane, vinyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloxypropyltrimethoxysilane; and polymeric epoxy, amino, and vinyl silanes.

[0208] Examples of titanate coupling agents include isopropyl triisostearoyl titanate, isopropyl tri(N-aminoethyl aminoethyl) titanate, diisopropyl bis(dioctyl phosphate) titanate, tetraisopropyl bis(dioctyl phosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphite titanate, bis(dioctyl pyrophosphate)oxyacetate titanate, and bis(dioctyl pyrophosphate)ethylene titanate.

[0209] These coupling agents may be used either alone or as a mixture of two or more in any combination and ratio.

[0210] When a coupling agent is used in the epoxy resin composition, the amount thereof is preferably 0.001 to 10.0 parts by mass per 100 parts by mass of the total epoxy resin components. When the amount of the coupling agent is equal to or greater than the lower limit, the effect of improving the adhesion between the epoxy resin matrix and the inorganic filler due to the incorporation of the coupling agent tends to be enhanced. On the other hand, when the amount of the coupling agent is equal to or less than the upper limit, the coupling agent is less likely to bleed out from the resulting cured product, which is preferable.

[0211] (Other ingredients) The epoxy resin composition may contain components other than those described above. Examples of other components include flame retardants, plasticizers, reactive diluents, pigments, etc., and these can be appropriately added as needed. However, this does not in any way preclude the addition of components other than those listed above.

[0212] Examples of the flame retardant include halogen-based flame retardants such as brominated epoxy resins and brominated phenol resins, antimony compounds such as antimony trioxide, phosphorus-based flame retardants such as red phosphorus, phosphate esters and phosphines, nitrogen-based flame retardants such as melamine derivatives, and inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide.

[0213] (Curing method) A cured epoxy resin product can be obtained by curing an epoxy resin composition. The curing method is not particularly limited, but a cured product can usually be obtained by a thermosetting reaction caused by heating. During the thermosetting reaction, it is preferable to appropriately select the curing temperature depending on the type of curing agent used. For example, when a phenolic curing agent is used, the curing temperature is usually 80 to 250°C. It is also possible to lower the curing temperature by adding a curing accelerator to these curing agents. The reaction time is preferably 0.01 to 20 hours. A reaction time of at least the lower limit is preferred because the curing reaction tends to proceed more efficiently. On the other hand, a reaction time of not more than the upper limit is preferred because it is easy to reduce deterioration due to heating and energy loss during heating.

[0214] (Application) The epoxy resin cured product obtained by curing the epoxy resin composition has a high elastic modulus at 250°C and excellent resistance to heat distortion. Therefore, the cured epoxy resins can be effectively used in any application requiring these physical properties, such as in the coatings field (electrodeposition coatings for automobiles, heavy-duty anticorrosion coatings for ships and bridges, and coatings for the interior surfaces of beverage cans), in the electrical and electronics field (laminated plates, semiconductor encapsulants, insulating powder coatings, coil impregnation, etc.), and in the civil engineering, construction, and adhesives field (earthquake-resistant reinforcement of bridges, concrete reinforcement, building flooring, water facility linings, drainage and permeable pavements, and adhesives for vehicles and aircraft).

[0215] The epoxy resin composition may be used for the above-mentioned applications after curing, or may be cured during the manufacturing process for the above-mentioned applications. [Example]

[0216] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0217] [Raw materials and reagents] The polycarbonate resin used was "NOVAREX (registered trademark) M7027BF" manufactured by Mitsubishi Chemical Engineering Plastics Corporation. Methanol, phenol, dimethyl malonate, ethylene diacetate, butyl acetate, sodium hydroxide, sodium phenoxide, acetonitrile, and cesium carbonate were used as reagents from Fujifilm Wako Pure Chemical Industries, Ltd. Diphenyl carbonate used was a product of Mitsubishi Chemical Corporation.

[0218] [analysis] The confirmation of the production, purity, and quantification of bisphenol A were carried out by high performance liquid chromatography according to the following procedures and conditions. Quantitative method: Internal standard method using biphenyl as an internal standard Equipment: Shimadzu LC-2010A, Waters 5μm 150mm x 4.6mm ID Method: Low-pressure gradient method ·Analysis temperature: 40℃ ·Eluent composition: Solution A: Acetonitrile Solution B: 85% phosphoric acid:water = 1 mL:999 mL solution At 0 min of analysis time, the eluent composition was A:B = 35:65 (volume ratio, same below), and from 0 to 5 min of analysis time, the eluent composition was A:B = 35:65, and then gradually changed to A:B = 90:10 from 5 to 40 min of analysis time. ·Flow rate: 0.85mL / min Detection wavelength: 280nm

[0219] [Viscosity average molecular weight (Mv)] The viscosity average molecular weight (Mv) was determined by dissolving the polycarbonate resin in methylene chloride (concentration: 6.0 g / L), measuring the specific viscosity (ηsp) at 20°C using an Ubbelohde viscometer, and calculating the viscosity average molecular weight (Mv) using the following formula. ηsp / C=[η](1+0.28ηsp) [η]=1.23×10 -4 Mv 0.83

[0220] [Pellet YI] Pellet YI (transparency of polycarbonate resin) was evaluated by measuring the YI value (yellowness index value) of reflected light of polycarbonate resin pellets in accordance with ASTM D 1925. The instrument used was a spectrophotometer "CM-5" manufactured by Konica Minolta, and the measurement conditions were a measurement diameter of 30 mm and SCE. The CM-A212 Petri dish calibration glass was fitted into the measurement unit, and the CM-A124 zero calibration box was placed over it to perform zero calibration. Then, the built-in white calibration plate was used to perform white calibration. Measurements were then performed using the CM-A210 white calibration plate, confirming that L* was 99.40±0.05, a* was 0.03±0.01, b* was -0.43±0.01, and YI was -0.58±0.01. YI was measured by filling a cylindrical glass container with an inner diameter of 30 mm and a height of 50 mm with pellets to a depth of about 40 mm. The pellets were removed from the glass container and the measurement was repeated twice, and the average of the three measurements was used.

[0221] [pH measurement] The pH was measured using a pH meter "pH METER ES-73" manufactured by Horiba Ltd., with respect to the aqueous phase at 25°C taken out of the flask.

[0222] [Melted color of bisphenol A] The melt color of bisphenol A was measured by placing 20 g of bisphenol C in a test tube "P-24" (24 mmφ × 200 mm) manufactured by Nichiden Rika Glass Co., Ltd., melting it at 175°C for 30 minutes, and measuring the Hazen color number using "SE6000" manufactured by Nippon Denshoku Industries Co., Ltd.

[0223] [Example 1] 20 g of methanol (20 g ÷ 32 g / mol = 0.6 mol, molar ratio of methanol to 1 mole of repeating unit of polycarbonate resin = 0.6 mol ÷ 0.3 mol = 2.0), 220 g of dimethyl malonate, and 4 g of sodium phenoxide were placed in a jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer under a nitrogen atmosphere, and then 80 g of polycarbonate resin (since the molecular weight of the repeating unit of polycarbonate resin is 254 g / mol, the number of moles of repeating unit = 80 g ÷ 254 g / mol = 0.31 mol) was added at room temperature (liquid volume: 20 g + 220 g + 4 g + 80 g = 324 g). The jacket temperature was then raised to 120°C. When the temperature reached 120°C, undissolved polycarbonate resin was observed in the reaction solution (it was in a slurry state), and internal reflux was occurring. The reaction was continued for 3 hours while maintaining the jacket temperature at 120°C, and a homogeneous reaction solution was obtained. The composition of a portion of the resulting reaction liquid was confirmed by high performance liquid chromatography, and it was found that bisphenol A was 20.5% by mass (20.5 ÷ 100 × 324 g ÷ 228 g / mol ÷ 0.3 mol × 100 = 97% by mole).

[0224] [Example 2] In a jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer, 20 g of methanol (20 g ÷ 32 g / mol = 0.6 mol; molar ratio of methanol to 1 mole of repeating unit of polycarbonate resin = 0.6 mol ÷ 0.3 mol = 2.0), 220 g of dimethyl malonate, and 1 g of potassium hydroxide were placed under a nitrogen atmosphere, and then 80 g of polycarbonate resin (since the molecular weight of the repeating unit of polycarbonate resin is 254 g / mol, the number of moles of repeating unit = 80 g ÷ 254 g / mol = 0.31 mol) was placed at room temperature (liquid volume: 20 g + 220 g + 1 g + 80 g = 321 g). The jacket temperature was then raised to 120°C. When the temperature reached 120°C, undissolved polycarbonate resin was observed in the reaction solution (it was in a slurry state), and internal reflux was occurring. The reaction was continued for 3 hours while maintaining the jacket temperature at 120°C, and a homogeneous reaction solution was obtained. The composition of a portion of the resulting reaction liquid was confirmed by high performance liquid chromatography, and it was found that bisphenol A was 19.7% by mass (19.7 ÷ 100 × 321 g ÷ 228 g / mol ÷ 0.3 mol × 100 = 92 mol%).

[0225] [Example 3] In a jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer, 20 g of methanol (20 g ÷ 32 g / mol = 0.6 mol; molar ratio of methanol to 1 mole of repeating unit of polycarbonate resin = 0.6 mol ÷ 0.3 mol = 2.0), 120 g of ethylene diacetate, and 4 g of phenoxy sodium were placed under a nitrogen atmosphere, and then 80 g of polycarbonate resin (since the molecular weight of the repeating unit of polycarbonate resin is 254 g / mol, the number of moles of repeating unit = 80 g ÷ 254 g / mol = 0.31 mol) was placed at room temperature (liquid volume: 520 g + 120 g + 4 g + 80 g = 224 g). The jacket temperature was then raised to 120°C. Undissolved polycarbonate resin was observed in the reaction liquid when it reached 120°C (it was in a slurry state). The reaction was continued for 3 hours while maintaining the jacket temperature at 120°C, and a homogeneous reaction liquid was obtained. The composition of a portion of the resulting reaction liquid was confirmed by high performance liquid chromatography, and it was found that bisphenol A was 29.4% by mass (29.4 ÷ 100 × 224 g ÷ 228 g / mol ÷ 0.3 mol × 100 = 96 mol%).

[0226] [Example 4] In a jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer, 48 g of butanol (48 g ÷ 74 g / mol = 0.6 mol; molar ratio of methanol to 1 mole of repeating unit of polycarbonate resin = 1.6 mol ÷ 0.3 mol = 2.0), 240 g of butyl acetate, and 4 g of sodium phenoxide were placed under a nitrogen atmosphere, and then 80 g of polycarbonate resin (since the molecular weight of the repeating unit of polycarbonate resin is 254 g / mol, the number of moles of repeating unit = 80 g ÷ 254 g / mol = 0.3 mol) was placed at room temperature (liquid volume: 48 g + 240 g + 4 g + 80 g = 372 g). The jacket temperature was then raised to 120°C. Undissolved polycarbonate resin was observed in the reaction liquid when it reached 120°C (it was in a slurry state). The reaction was continued for 3 hours while maintaining the jacket temperature at 120°C, and a homogeneous reaction liquid was obtained. The composition of a portion of the resulting reaction liquid was confirmed by high performance liquid chromatography, and it was found that bisphenol A was 14.1% by mass (14.1 ÷ 100 × 372 g ÷ 228 g / mol ÷ 0.3 mol × 100 = 77% by mole).

[0227] [Example 5] Into a jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer, 48 g of butanol (48 g ÷ 74 g / mol = 0.6 mol; molar ratio of methanol to 1 mole of repeating unit of polycarbonate resin = 1.6 mol ÷ 0.3 mol = 2.0), 240 g of butyl acetate, and 4 g of triethylamine were placed under a nitrogen atmosphere, and then 80 g of polycarbonate resin (since the molecular weight of the repeating unit of polycarbonate resin is 254 g / mol, the number of moles of repeating unit = 80 g ÷ 254 g / mol = 0.3 mol) was placed at room temperature (liquid volume: 48 g + 240 g + 4 g + 80 g = 372 g). The jacket temperature was then raised to 120°C. Undissolved polycarbonate resin was observed in the reaction liquid when it reached 120°C (it was in a slurry state). The reaction was continued for 3 hours while maintaining the jacket temperature at 120°C, and a homogeneous reaction liquid was obtained. The composition of a portion of the resulting reaction liquid was confirmed by high performance liquid chromatography, and it was found that bisphenol A was 10.3% by mass (10.3 ÷ 100 × 372 g ÷ 228 g / mol ÷ 0.3 mol × 100 = 56 mol%).

[0228] [Comparative Example 1] A jacketed separable flask equipped with a Dimroth condenser, a stirring blade, and a thermometer was charged with 80 g of methanol (80 g ÷ 32 g / mol = 2.5 mol; molar ratio of methanol to 1 mole of polycarbonate resin repeating unit = 2.5 mol ÷ 0.31 mol = 8.1) and 1 g of potassium hydroxide under a nitrogen atmosphere, and then 80 g of polycarbonate resin (the molecular weight of the polycarbonate resin repeating unit is 254 g / mol, so the number of moles of repeating unit = 80 g ÷ 254 g / mol = 0.31 mol) was charged at room temperature (liquid volume: 80 g + 1 g + 80 g = 161 g). Thereafter, the jacket temperature was raised to 120° C. Before reaching 120° C., the methanol evaporated, and it was confirmed that decomposition was not progressing.

[0229] Table 1 summarizes the catalyst, alkyl ester, aliphatic alcohol, and bisphenol A production rate in Examples 1 to 5 and Comparative Example 1. Table 1 shows that polycarbonate can be decomposed at normal pressure by using alkyl ester.

[0230] [Table 1]

[0231] [Example 6] 70% by mass of sulfuric acid was added to neutralize the reaction liquid obtained in Example 1. The resulting liquid was filtered through a glass filter to remove sodium sulfate, and a filtrate was obtained. The obtained filtrate was transferred to a distillation apparatus equipped with a thermometer, stirring blades, a distillation tube, and a pressure regulator. The pressure was adjusted from atmospheric pressure (101.33 kPa) to 16.00 kPa, and while monitoring the distillate volume, methanol and dimethyl malonate were extracted as fractions to obtain a bottom residue. 280 g of toluene was added to the obtained bottom residue, and a homogeneous solution was obtained while maintaining the temperature at 80°C. The temperature was then gradually lowered to 5°C to obtain a slurry. The obtained slurry was filtered using a centrifuge to obtain a cake.

[0232] The entire cake obtained was fed into a jacketed separable flask equipped with a Dimroth condenser, stirring blades, and a thermometer under a nitrogen atmosphere. 200 g of toluene was then added to obtain a slurry. The resulting slurry was heated to 80°C to form a homogeneous solution. The resulting homogeneous solution was washed three times with 100 g of demineralized water. The temperature was then lowered to 5°C to obtain a slurry. The resulting slurry was filtered using a centrifuge to obtain a refined cake. The entire refined cake was dried using an evaporator equipped with an oil bath at an oil bath temperature of 85°C and 20.00 kPa for 3 hours to obtain 25 g of a solid. The obtained solid was identified by high-performance liquid chromatography and found to be bisphenol A with a purity of 99.9%.

[0233] A 45 mL glass reactor equipped with a stirrer and a distillation tube was charged with 10.00 g (0.04 mol) of the obtained bisphenol A, 9.95 g (0.05 mol) of diphenyl carbonate, and 18 μL of a 400 ppm by mass aqueous cesium carbonate solution. The glass reactor was depressurized to approximately 100 Pa, and then the pressure was returned to atmospheric pressure with nitrogen. This operation was repeated three times to replace the inside of the reactor with nitrogen. The reactor was then immersed in an oil bath at 220°C to dissolve the contents.

[0234] The stirrer was rotated at 100 revolutions per minute, and the pressure inside the reaction vessel was reduced from 101.3 kPa to 13.3 kPa absolute pressure over 40 minutes while distilling off phenol, which was a by-product of the oligomerization reaction of bisphenol A and diphenyl carbonate inside the reaction vessel.

[0235] Subsequently, the pressure inside the reaction vessel was maintained at 13.3 kPa, and the transesterification reaction was carried out for 80 minutes while further distilling off phenol.

[0236] Thereafter, the temperature outside the reactor was raised to 290°C, and the pressure inside the reactor was reduced from 13.3 kPa to 399 Pa absolute over 40 minutes, and the distilled phenol was removed from the system.

[0237] Thereafter, the absolute pressure in the reaction vessel was reduced to 30 Pa, and the polycondensation reaction was carried out. When the agitator in the reaction vessel reached a predetermined agitation power, the polycondensation reaction was terminated. The time from raising the temperature to 290°C to completing the polymerization was 120 minutes.

[0238] The reactor was then pressurized with nitrogen to an absolute pressure of 101.3 kPa, and then the pressure was increased to a gauge pressure of 0.2 MPa. The polycarbonate resin was extracted from the reactor to obtain a polycarbonate resin having a viscosity average molecular weight (Mv) of 27,100. [Industrial Applicability]

[0239] According to the present invention, bisphenol can be obtained from waste plastics and the like by utilizing chemical recycling. Furthermore, this can be used to produce polycarbonate resins and epoxy resins, which is industrially useful.

Claims

1. Polycarbonate resin, A method for producing bisphenols by decomposing them in the presence of an alkyl ester, an aliphatic alcohol, and a catalyst, The method for producing bisphenol, wherein the catalyst is any one selected from the group consisting of alkali metal hydroxides, alkali metal alkoxides, alkali metal carbonates, alkali metal oxides, alkylamines, and pyridines.

2. the alkali metal hydroxide is sodium hydroxide or potassium hydroxide; the alkali metal carbonate is sodium carbonate, potassium carbonate, sodium bicarbonate or potassium bicarbonate; the alkali metal alkoxide is sodium phenoxide or sodium methoxide; 2. The method for producing bisphenol according to claim 1, wherein the alkali metal oxide is sodium oxide or potassium oxide.

3. The method for producing bisphenol according to claim 1, wherein the alkylamine is represented by the following formula (I) or the following formula (II): 【Chemistry 1】 In formula (I), R A represents an alkyl group having 1 to 3 carbon atoms, and R B ~R C each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 【Chemistry 2】 In formula (II), R D ~R G each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; and m represents an integer of 1 to 6.

4. 4. The method for producing bisphenol according to claim 1, wherein the alkyl ester is any one selected from the group consisting of methyl ester, ethyl ester, butyl ester and glycol ester.

5. The method for producing bisphenol according to any one of claims 1 to 4, wherein the bisphenol is 2,2-bis(4-hydroxyphenyl)propane.

6. The method for producing bisphenol according to any one of claims 1 to 5, wherein the decomposition temperature of the polycarbonate resin is 150°C or lower.

7. The method for producing bisphenol according to any one of claims 1 to 6, wherein the alkyl ester has 2 or more and 6 or less carbon atoms.

8. 8. The method for producing bisphenol according to claim 1, wherein the aliphatic alcohol is any one selected from the group consisting of methanol, ethanol, butanol, and ethylene glycol.

9. 9. The method for producing bisphenol according to claim 1, comprising the following steps A, B1, and C1: Step A: A step of decomposing the polycarbonate resin in the presence of the alkyl ester, the aliphatic alcohol, and the catalyst to obtain a polycarbonate decomposition liquid containing bisphenol. Step B1: A step of concentrating the polycarbonate decomposition liquid obtained in Step A to obtain a concentrated liquid Step C1: A step of supplying an aromatic hydrocarbon to the concentrated liquid obtained in Step B1 to cause crystallization to precipitate bisphenol, thereby obtaining a slurry containing bisphenol, and subjecting the obtained slurry to solid-liquid separation to obtain bisphenol.

10. 9. The method for producing bisphenol according to claim 1, comprising the following steps A, B2, and C2: Step A: A step of decomposing the polycarbonate resin in the presence of the alkyl ester, the aliphatic alcohol, and the catalyst to obtain a polycarbonate decomposition liquid containing bisphenol. Step B2: A step of removing the alkyl ester and the aliphatic alcohol from the solution containing the polycarbonate decomposition liquid and the aromatic monoalcohol obtained in Step A to obtain a solution containing a bisphenol and the aromatic monoalcohol. Step C2: A step of recovering bisphenol from the solution containing bisphenol and aromatic monoalcohol

11. A method for producing a recycled polycarbonate resin, comprising obtaining bisphenol through the method for producing bisphenol according to any one of claims 1 to 10, and then using a bisphenol raw material containing the bisphenol to produce a recycled polycarbonate resin.

12. A method for producing an epoxy resin, comprising obtaining bisphenol through the method for producing bisphenol according to any one of claims 1 to 10, and then producing an epoxy resin using a polyhydric hydroxy compound raw material containing the bisphenol.

13. A method for producing an epoxy resin, comprising: obtaining an epoxy resin through the method for producing an epoxy resin according to claim 12; and then further reacting an epoxy resin raw material containing the epoxy resin with a polyvalent hydroxy compound raw material to produce an epoxy resin.

14. A method for producing a cured epoxy resin product, comprising obtaining an epoxy resin through the method for producing an epoxy resin according to claim 12 or 13, obtaining an epoxy resin composition containing the epoxy resin and a curing agent, and then curing the epoxy resin composition to obtain a cured epoxy resin product.

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