Method for manufacturing aromatic polycarbonates

Abstract

The present invention provides a method for producing aromatic polycarbonate that suppresses the amount of unreacted raw materials discharged outside the system. [Solution] A method for producing aromatic polycarbonate, comprising: step a) mixing raw materials in a mixing tank for raw material mixing using one or more aromatic dihydroxy compounds and one or more diaryl carbonates; step b) transesterification reaction; step c) pre-polycondensation reaction; step d) polycondensation reaction; step e) recovery of diaryl carbonates and / or aromatic dihydroxy compounds encombusted with the hydroxyaryl reaction product in at least one of steps b) to d); and step f) adding at least a portion of the recovered diaryl carbonates and / or aromatic dihydroxy compounds to the raw material mixture before supplying it to the transesterification reactor.

Description

[Technical Field]

[0001] This invention relates to a method for producing aromatic polycarbonate. [Background technology]

[0002] Transesterification is a typical method for producing aromatic polycarbonates. In this method, a dihydroxy compound such as bisphenol A (hereinafter also referred to as "BPA") is transesterified with a diaryl carbonate such as diphenyl carbonate (hereinafter also referred to as "DPC"), and polymerization is carried out by removing the by-product hydroxyaryl compound from the system (for example, Patent Documents 1-2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2005 / 121213 [Patent Document 2] International Publication No. 2013 / 189823 [Overview of the project] [Problems that the invention aims to solve]

[0004] In the transesterification method for producing polycarbonate, when the by-product hydroxyaryl compound is removed from the system, some of the diaryl carbonate and / or aromatic dihydroxy compounds, which are the raw materials, are carried out of the system along with the hydroxyaryl compound vapor. To reduce raw material costs, a recovery process for the discharged raw materials is sometimes implemented, in which the diaryl carbonate and / or aromatic dihydroxy compounds discharged from the system along with the hydroxyaryl compound vapor are recovered from the hydroxyaryl compound vapor and reused. However, if a large amount of unreacted raw materials are discharged from the system, the recovery burden becomes large. In addition, even when a recovery process is implemented, some of the diaryl carbonate and / or aromatic dihydroxy compounds carried out of the hydroxyaryl compound vapor cannot be completely separated from the hydroxyaryl compound and cannot be recovered in the predetermined proportion, resulting in raw material loss. For these reasons, it is desirable to reduce the amount of unreacted raw materials discharged from each step in the transesterification method for producing polycarbonate.

[0005] In Patent Document 2, a portion of the vapor of the hydroxyaryl compound, which includes droplets of the dihydroxy compound and diaryl carbonate used as raw materials, is condensed, recovered, and re-added in the latter half of the polymerization reaction. However, since the re-addition occurs between the transesterification reaction step and the pre-polycondensation reaction step, which are under reduced pressure conditions, it is conceivable that the re-added raw materials will be entrained again with the vapor of the hydroxyaryl compound, increasing the amount of unreacted raw materials discharged from the system. Therefore, there is room for improvement.

[0006] The present invention aims to provide a method for producing aromatic polycarbonate that suppresses the amount of unreacted raw materials discharged outside the system. [Means for solving the problem]

[0007] The inventors focused on suppressing the discharge of unreacted raw materials outside the system. They discovered that by supplying these materials to a specific process, the amount re-encompassed into the steam is suppressed, thereby reducing the discharge of diaryl carbonates and / or aromatic dihydroxy compounds.

[0008] The present invention includes the following embodiments. <1> A method for producing an aromatic polycarbonate, comprising: the following steps a) to f): a) mixing raw materials using one or more aromatic dihydroxy compounds and one or more diaryl carbonates in a raw material mixing tank; b) subjecting the raw material mixture to a transesterification reaction in at least one transesterification reactor while removing the generated hydroxyaryl reaction product; c) subjecting the reaction product of the transesterification reaction to a prepolycondensation reaction in at least one prepolycondensation reactor while removing the generated hydroxyaryl reaction product; d) subjecting the reaction product of the prepolycondensation reaction to a polycondensation reaction in at least one polycondensation reactor while removing the generated hydroxyaryl reaction product; e) recovering diaryl carbonate and / or aromatic dihydroxy compound entrained by the hydroxyaryl reaction product in at least one step among steps b) to d), and f) adding at least a portion of the recovered diaryl carbonate and / or aromatic dihydroxy compound to the raw material mixture before feeding to the transesterification reactor, A method for producing an aromatic polycarbonate, comprising the above steps. <2> The method for producing an aromatic polycarbonate according to <1>, wherein in step b), the conversion rate of the aromatic dihydroxy compound and / or the diaryl carbonate is 70 to 100%. <3> The method for producing an aromatic polycarbonate according to <1> or <2>, wherein the average degree of polymerization n of the reaction product of step b) is 1 to 20. <4> The method for producing an aromatic polycarbonate according to any one of <1> to <3>, wherein the average degree of polymerization n of the reaction product of step c) is 40 to 110. <5> The method for producing an aromatic polycarbonate according to any one of <1> to <4>, wherein a terminal OH percentage of the reaction product introduced into the polycondensation reactor is monitored, and the amount of the diaryl carbonate and / or the aromatic dihydroxy compound to be added to the raw material mixture in step f) is determined based on the terminal OH percentage. <6> The method for producing an aromatic polycarbonate according to any one of <1> to <5>, wherein by adjusting the ratio of the diaryl carbonate to the aromatic dihydroxy compound to be subjected to the step b), the terminal OH percentage of the reaction product introduced in the step d) is controlled within ±2.0%. <7> The method for producing an aromatic polycarbonate according to any one of <1> to <6>, wherein the aromatic dihydroxy compound is a compound represented by formula (1): HO-Z-OH···(1), wherein Z is a divalent organic group having 6 to 30 carbon atoms containing one or more aromatic groups. <8> The method for producing an aromatic polycarbonate according to any one of <1> to <7>, wherein the diaryl carbonate is a carbonic acid diester having an aromatic group having 5 to 20 carbon atoms. <9> The method for producing an aromatic polycarbonate according to any one of <1> to <8>, wherein the aromatic dihydroxy compound is bisphenol A, and the diaryl carbonate is diphenyl carbonate. <10> the transesterification reaction is carried out in the presence of a catalyst, The method for producing an aromatic polycarbonate according to any one of <1> to <9>, wherein the catalyst is added in the form of at least one alkali metal salt, or a mixture of at least one alkali metal salt of an aromatic alcohol and at least one boric acid ester of an aromatic alcohol. <11> The catalyst is obtained by adding a mixture of 0.05 to 2 ppm by mass of an alkali metal salt, or 0.1 to 2 ppm by mass of an alkali metal phenolate, and 0.25 to 3 ppm by mass of a boric acid ester of an aromatic alcohol to the starting aromatic dihydroxy compound. <10> A method for producing aromatic polycarbonate as described in [reference]. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a method for producing aromatic polycarbonate that suppresses the amount of unreacted raw materials discharged outside the system. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram of a polycarbonate manufacturing apparatus. [Figure 2] Figure 2 is a schematic diagram of the polycarbonate manufacturing apparatus. [Figure 3] Figure 3 shows a schematic diagram of a guided contact flow type polymerization apparatus. [Figure 4] Figure 4 is a schematic diagram of the polycarbonate manufacturing apparatus used in the examples and comparative examples. [Modes for carrying out the invention]

[0011] The following describes in detail embodiments for carrying out the present invention (hereinafter referred to as "this embodiment"). This embodiment is illustrative for explaining the present invention, and the present invention is not limited to this embodiment. The present invention can be implemented with appropriate modifications within the scope of its gist. In this specification, for example, the notation of a numerical range such as "1 to 100" includes both the lower limit "1" and the upper limit "100". The same applies to other numerical range notations.

[0012] The amount of unreacted raw materials discharged from the system refers to the amount of diaryl carbonates and aromatic dihydroxy compounds discharged from the system along with the vapor of the hydroxyaryl reaction product. Note that diaryl carbonates and aromatic dihydroxy compounds can also be produced by the reverse reaction in transesterification, and these diaryl carbonates and aromatic dihydroxy compounds are also included in the unreacted raw materials.

[0013] In raw material loss, "loss" refers to the difference between the amount of diaryl carbonate and aromatic dihydroxy compounds discharged from the system along with the vapor of the hydroxyaryl reaction products and the amount of diaryl carbonate and aromatic dihydroxy compounds recovered in the recovery process. Specifically, when considering diaryl carbonate loss, it refers to the difference between the amount of diaryl carbonate discharged from the system along with the vapor of the hydroxyaryl reaction products and the amount of diaryl carbonate recovered in the recovery process. Similarly, when considering aromatic dihydroxy compound loss, it refers to the difference between the amount of aromatic dihydroxy compounds discharged from the system along with the vapor of the hydroxyaryl reaction products and the amount of diaryl carbonate recovered in the recovery process.

[0014] [Method for producing aromatic polycarbonate] This embodiment is a method for producing aromatic polycarbonate, Next steps a)~f): a) Mixing raw materials in a mixing tank for raw material mixing using one or more aromatic dihydroxy compounds and one or more diaryl carbonates. b) In at least one transesterification reactor, carry out the transesterification reaction while removing the hydroxyaryl reaction product generated from the raw material mixture. c) In at least one pre-polycondensation reactor, the reaction products of the transesterification reaction are subjected to a pre-polycondensation reaction while removing the resulting hydroxyaryl reaction products. d) In at least one polycondensation reactor, the reaction products of the pre-polycondensation reaction are subjected to polycondensation while removing the resulting hydroxyaryl reaction products. e) Recovering the diaryl carbonate and / or aromatic dihydroxy compound encombusted with the hydroxyaryl reaction product in at least one of the steps b) to d) above, f) Adding at least a portion of the recovered diaryl carbonate and / or aromatic dihydroxy compound to the raw material mixture before supplying it to the transesterification reactor. This invention relates to a method for producing aromatic polycarbonate having [a certain characteristic]. According to this embodiment, a method for producing aromatic polycarbonate can be provided that suppresses the amount of unreacted raw materials discharged outside the system. Furthermore, according to this embodiment, by suppressing the amount of unreacted raw materials discharged outside the system, raw material loss of diaryl carbonate and / or aromatic dihydroxy compounds can also be suppressed.

[0015] <Raw materials> In the method for producing aromatic polycarbonate according to this embodiment, aromatic dihydroxy compounds and diaryl carbonates, or prepolymers thereof, are used as raw materials.

[0016] The following describes the aromatic dihydroxy compounds and diaryl carbonates, which are raw materials used in the polycarbonate manufacturing method of this embodiment. Bio-derived raw materials may be used in the production of these aromatic dihydroxy compounds and diaryl carbonates.

[0017] Aromatic dihydroxy compounds are compounds represented by formula (1): HO-Z-OH···(1). (In the formula, Z is a divalent organic group having 6 to 30 carbon atoms that contains one or more aromatic groups.)

[0018] The aromatic group is a monovalent carbocyclic or heterocyclic aromatic group. Examples of divalent organic groups include phenylene groups, naphthyl groups, and hydrocarbon groups substituted with two divalent aromatic groups.

[0019] The aromatic dihydroxy compound is not particularly limited, but is preferably one or more selected from, for example, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 1,1-bis(4-hydroxyphenyl)-1-phenylethane (bisphenol AP), 2,2-bis(4-hydroxyphenyl)hexafluoropropane (bisphenol AF), 2,2-bis(4-hydroxyphenyl)butane (bisphenol B), bis(4-hydroxyphenyl)diphenylmethane (bisphenol BP), 2,2-bis(3-methyl-4-hydroxyphenyl)propane (bisphenol C), 1,1-bis(4-hydroxyphenyl)ethane (bisphenol E), bis(4-hydroxyphenyl)methane (bisphenol F), 5,5'-(1-methylethylidene)-bis[1,1'-(bisphenyl)-2-ol]propane (bisphenol PH), and 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z), with bisphenol A being more preferred.

[0020] The aromatic dihydroxy compound used in this embodiment may be a single compound or two or more compounds. A trihydroxy compound having three hydroxyl groups may be used in combination to introduce a branched structure.

[0021] The diaryl carbonate used in the method for producing polycarbonate according to this embodiment is, for example, a diester carbonate having an aromatic group with 5 to 20 carbon atoms.

[0022] Diaryl carbonates can be represented, for example, by the following formula. [ka] (In the formula, Ar 1 Ar 2 (Each represents a monovalent aromatic group with 5 to 20 carbon atoms.)

[0023] Ar 1 and Ar 2The monovalent aromatic group in represents a monovalent carbocyclic or heterocyclic aromatic group, this Ar 1 , Ar 2 , one or more hydrogen atoms may be substituted with other substituents that do not adversely affect the reaction, for example, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a phenyl group, a phenoxy group, a vinyl group, a cyano group, an ester group, an amide group, a nitro group, etc. Ar 1 , Ar 2 may be the same or different. The monovalent aromatic groups Ar 1 and Ar 2 representative examples thereof include a phenyl group, a naphthyl group, a biphenyl group, and a pyridyl group. These may be substituted with one or more of the above-mentioned substituents.

[0024] Ar 1 and Ar 2 are preferably those represented by the following formula.

Chemical

[0025] Representative examples of diaryl carbonates include substituted or unsubstituted diphenyl carbonates represented by the following formula.

Chemical

[0026] Among these diaryl carbonates, symmetrical diaryl carbonates such as unsubstituted diphenyl carbonate, ditril carbonate, and lower alkyl-substituted diphenyl carbonate such as di-t-butylphenyl carbonate are preferred, but diphenyl carbonate, which has the simplest structure, is particularly preferred. These diaryl carbonates may be used individually or in combination of two or more.

[0027] The ratio of aromatic dihydroxy compounds to diaryl carbonates used (compound ratio) varies depending on the types of aromatic dihydroxy compounds and diaryl carbonates used, as well as the polymerization temperature and other polymerization conditions. Diaryl carbonates are typically used in a ratio of 0.9 to 2.5 moles, preferably 0.95 to 2.0 moles, and more preferably 0.98 to 1.5 moles per mole of aromatic dihydroxy compound.

[0028] <Catalyst> The reaction to produce polycarbonates from aromatic dihydroxy compounds and diaryl carbonates can be carried out without a catalyst, but it is carried out in the presence of a catalyst as needed to increase the polymerization rate.

[0029] Examples of catalysts include alkali metal and alkaline earth metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, and calcium hydroxide; alkali metal salts, alkaline earth metal salts, and quaternary ammonium salts of boron and aluminum hydrides such as lithium aluminum hydride, sodium borohydride, and tetramethylammonium borohydride; alkali metal and alkaline earth metal hydrogen compounds such as lithium hydride, sodium hydride, and calcium hydride; alkali metal and alkaline earth metal alkoxides such as lithium methoxide, sodium ethoxide, and calcium methoxide; and alkali metal and alkaline earth metal alkoxides such as lithium phenoxide, sodium phenoxide, magnesium phenoxide, LiO-Ar-OLi, and NaO-Ar-ONa (Ar is an aryl group). Examples include allyloxides of alkaline earth metals; organic acid salts of alkali metals and alkaline earth metals such as lithium acetate, calcium acetate, and sodium benzoate; zinc compounds such as zinc oxide, zinc acetate, and zinc phenoxide; tin compounds such as boron oxide, boric acid, sodium borate, trimethyl borate, tributyl borate, triphenyl borate, tin oxide, dialkyltin oxide, dialkyltin carboxylate, tin acetate, and ethyltin tributoxide, as well as tin compounds bonded to alkoxy or allyloxy groups, and organotin compounds; lead compounds such as lead oxide, lead acetate, lead carbonate, basic carbonates, lead, and organolead alkoxides or allyloxides; quaternary ammonium salts, quaternary phosphonium salts, and mixtures of alkali metal phenolates and boric acid esters of aromatic alcohols.

[0030] The catalyst is preferably added in the form of at least one alkali metal salt, or a mixture of at least one alkali metal salt of an aromatic alcohol and at least one borate ester of an aromatic alcohol. The alkali metal salt is preferably in an amount of 0.05 to 2 ppm by mass relative to the starting aromatic dihydroxy compound. The alkali metal phenolate is preferably in an amount of 0.1 to 2 ppm by mass relative to the starting aromatic dihydroxy compound. The borate ester of the aromatic alcohol is preferably in an amount of 0.25 to 3 ppm by mass relative to the starting aromatic dihydroxy compound.

[0031] When catalysts are used, they may be used individually or in combination of two or more. The amount of these catalysts used is typically 10 times the amount of the aromatic dihydroxy compound used as a raw material. -10 ~1% by mass, preferably 10% -9 ~10 -1 Mass%, more preferably 10 -8 ~10 -2 It is in the range of mass percent.

[0032] [Polycarbonate manufacturing equipment] The apparatus used in the method for producing aromatic polycarbonate according to this embodiment will now be described. Figure 1 is a schematic diagram of the aromatic polycarbonate production apparatus. The aromatic polycarbonate production apparatus includes a mixing tank 1 for mixing polymerization raw materials and a catalyst, a transesterification reactor 2 for performing a transesterification reaction, a pre-polycondensation reactor 4 for performing a pre-polycondensation reaction, a polycondensation reactor 6 for performing a polycondensation reaction, a raw material supply unit 71 for additionally supplying diaryl carbonate and / or aromatic dihydroxy compounds from am, and a raw material supply unit 72 for additionally supplying diaryl carbonate and / or aromatic dihydroxy compounds ao. The transesterification reactor, pre-polycondensation reactor, and polycondensation reactor may each be one unit or there may be two or more units. The raw materials supplied from the raw material supply units 71 and 72 may be diaryl carbonate and / or aromatic dihydroxy compounds recovered as unreacted components, or diaryl carbonate and / or aromatic dihydroxy compounds newly introduced from outside the system.

[0033] As shown in Figure 2, the aromatic polycarbonate manufacturing apparatus includes a mixing tank 1 for mixing polymerization raw materials and catalysts, two transesterification reactors 2 and 3, two pre-polycondensation reactors 4 and 5, a polycondensation reactor 6, a raw material supply unit 71 for supplying diaryl carbonate and / or aromatic dihydroxy compounds from am, and a raw material supply unit 72 for supplying diaryl carbonate and / or aromatic dihydroxy compounds ao.

[0034] The transesterification reactor, pre-polycondensation reactor, and polycondensation reactor each have vents that can continuously discharge the hydroxyaryl reaction products generated within each reactor. By sampling and analyzing the vapor discharged from each vent, the amount of raw materials (dihydroxy compounds and diaryl carbonates) carried along with the discharged hydroxyaryl reaction product vapor can be monitored.

[0035] The hydroxyaryl reaction product is a hydroxyaryl compound derived from a diaryl carbonate, for example, an aromatic group having 5 to 20 carbon atoms and a hydroxyl group, more specifically, the formula: HO-Ar 1 (In the formula, Ar 1 The above Ar 1 It is a compound represented by the same definition as ). Phenol is an example of a hydroxyaryl reaction product.

[0036] The polycarbonate production equipment according to this embodiment includes equipment that can monitor the terminal OH% of the reaction product introduced into the polycondensation reactor and add the raw materials (dihydroxy compounds and diaryl carbonates) to the raw material mixing tank and the piping between each reactor based on the terminal OH%.

[0037] The method for manufacturing polycarbonate according to this embodiment will be explained using the above-described polycarbonate manufacturing apparatus as an example.

[0038] [Method for producing aromatic polycarbonate] <Step a): Raw material mixing> Raw material mixing involves mixing one or more aromatic dihydroxy compounds, one or more diaryl carbonates, and a catalyst in a raw material mixing tank, and proceeding with a polycondensation reaction with an upper limit of 3 for the degree of polymerization of the raw material mixture. The raw material mixing tank may be equipped with a stirring blade that directly agitates the liquid surface. A stirring blade that directly agitates the liquid surface means a stirring blade in which the part other than the stirring axis is located at the gas interface. The stirring blade may or may not be located inside the liquid outside the gas-liquid interface, but using a stirring blade that agitates not only the gas-liquid interface but also the inside of the liquid is a preferred embodiment of this product. There are no particular restrictions on the shape of the stirring blade, and various types of stirring blades can be used, such as Fardler blades, anchor blades, turbine blades, double helical blades, and Maxblend type stirring blades.

[0039] The mixing temperature of the raw materials is preferably 100°C to 250°C, more preferably 120°C to 200°C. The mixing pressure of the raw materials is preferably 101kPaA to 120kPaA, more preferably 101kPaA to 110kPaA.

[0040] The mixing of raw materials and catalyst can be done in a batch process, where all raw materials and catalyst are charged before mixing, or in a continuous process, where the raw materials and catalyst are supplied continuously while mixing is performed. The catalyst may be added in multiple stages between steps b) and d). The raw material mixing tank may be a single unit or multiple units may be installed in series or parallel. The average degree of polymerization n of the mixture after raw material mixing is preferably greater than 0 and less than or equal to 2. The degree of polymerization refers to the number of repeating units of the polymer. The average degree of polymerization n can be adjusted to a preferred range by satisfying the above-mentioned charging ratio, catalyst amount, temperature, and pressure.

[0041] <Step b): Transesterification reaction> A transesterification reaction is a reaction that increases the degree of polymerization of the raw material mixture obtained in step a) to any value, with 39 being the upper limit. The transesterification reactor installed in step b) is preferably equipped with a vent to remove the by-product hydroxyaryl reaction product, from the viewpoint of carrying out the transesterification reaction. A scrubber or the like may be installed in the vent of the transesterification reactor to recover the raw materials (aromatic dihydroxy compounds and diaryl carbonates) discharged from the vent and reuse them in the production of polycarbonate. The transesterification reactor may be equipped with impellers that directly agitate the liquid surface. Impellers that directly agitate the liquid surface mean impellers in which the part of the impeller other than the stirring shaft is located at the gas interface. Impellers may or may not be located inside the liquid other than the gas-liquid interface, but using impellers that agitate not only the gas-liquid interface but also the inside of the liquid is a preferred embodiment of this product. There are no particular restrictions on the shape of the impellers, and various types of impellers can be used, such as Fardler impellers, anchor impellers, turbine impellers, double helical impellers, and Maxblend type impellers.

[0042] The temperature of the transesterification reaction is preferably 160 to 250°C, and more preferably 180 to 230°C. The pressure of the transesterification reaction is preferably 5 kPaA to 120 kPaA, and more preferably 10 kPaA to 110 kPaA.

[0043] The transesterification reaction may be carried out in a single reactor or in multiple reactors installed in series or parallel. The transesterification reaction may be carried out in a batch manner, where all the mixture is charged into the transesterification reactor before the reaction, or in a continuous manner, where the mixture is continuously supplied while the reaction is carried out. The conversion rate of the raw materials after the transesterification reaction is usually in the range of 70 to 100%, preferably 75 to 100%. The average degree of polymerization n of the reactants after the transesterification reaction is preferably 1 to 20. The conversion rate and average degree of polymerization n can be adjusted to a preferred range by satisfying the above-mentioned charging ratio, catalyst amount, temperature, and pressure.

[0044] <Step c): Pre-polycondensation reaction> A pre-polycondensation reaction is a reaction that increases the degree of polymerization of a reactant obtained in a transesterification reaction to any desired value, with 110 being the upper limit. The pre-polycondensation reactor installed in step c) is preferably a reactor equipped with a vent to remove the hydroxyaryl reaction product generated, from the viewpoint of advancing the pre-polycondensation reaction. More specifically, as the pre-polycondensation reactor, a reactor equipped with a stirring blade to directly stir the liquid surface, a ring-disk reactor, a thin-film polymerization reactor, a centrifugal thin-film evaporation polymerization reactor, a surface-renewal twin-screw kneading polymerization reactor, a wet-wall polymerization reactor, a porous plate polymerization reactor that polymerizes while free-falling, and a guided contact-flow polymerization apparatus that allows polymerization to proceed by melting and dropping the polymer along a support can be used. An example of a guided contact-flow polymerization apparatus is a porous plate polymerization apparatus with wires. An example of a ring-disk reactor is a single-screw horizontal stirring reactor or a twin-screw horizontal stirring reactor, specifically the apparatus described in US2008 / 0064834 and US8017717. These polymerization reactors may be used individually or in combination. The pre-polycondensation reaction can be carried out in a batch manner, where all the transesterified products are loaded into the pre-polycondensation reactor before the reaction, or in a continuous manner, where the transesterified products are continuously supplied while the pre-polycondensation reaction is carried out. The pre-polycondensation reactor may be installed as a single unit or in series or parallel configuration. To recover the raw materials (aromatic dihydroxy compounds and diaryl carbonates) discharged from the vent of the pre-polycondensation reactor and reuse them in the production of polycarbonate, a scrubber or the like may be installed at the vent of the pre-polycondensation reactor.

[0045] The temperature for the pre-polycondensation reaction is preferably 200 to 300°C, more preferably 230 to 290°C. The pre-polycondensation pressure is preferably 0.2 kPaA to 10 kPaA, more preferably 0.5 kPaA to 8 kPaA. The pre-polycondensation reaction may be carried out in a single reactor or in multiple reactors installed in series or parallel. The pre-polycondensation reaction may be carried out in a batch manner, where all the transesterified products are loaded into the pre-polycondensation reactor before the reaction, or in a continuous manner, where the transesterified products are continuously supplied while the pre-polycondensation reaction is carried out.

[0046] In step c), the supply amount from step b) and the supply amount to the polycondensation reaction step (the outflow amount from the pre-polycondensation reaction step to the next step) are controlled. The residence time in the pre-polycondensation reaction step is maintained by increasing or decreasing the outflow amount from the pre-polycondensation reaction step in accordance with the increase or decrease in the supply amount from the transesterification reaction step to the pre-polycondensation reaction step. As will be described later, there is a step of additionally supplying diaryl carbonate and / or aromatic dihydroxy compounds to the flow from the reactor for the transesterification reaction to the inlet of the reactor for the polycondensation reaction, depending on the terminal OH% of the reactants after the pre-polycondensation reaction. Therefore, it is preferable to perform the adjustment to maintain the residence time before and after the start of the additional supply of diaryl carbonate and / or aromatic dihydroxy compounds. By adjusting the residence time before starting the additional supply of diaryl carbonate and / or aromatic dihydroxy compounds, the amount of diaryl carbonate and / or aromatic dihydroxy compounds discharged from the system along with the vapor of the by-product hydroxyaryl reaction product becomes stable, thus making the additional supply amount of diaryl carbonate and / or aromatic dihydroxy compounds more stable. After starting the additional supply of diaryl carbonate and / or aromatic dihydroxy compounds, the supply amount to each reactor installed in steps b) to d) will increase by the amount of the additional supply. This increase shortens the residence time in each reactor installed in steps b) to d) compared to before the additional supply was started. By adjusting the amount flowing out from each reactor to the next step and increasing the amount of liquid held in each reactor until the residence time is equivalent to that before the additional supply was started, the range of variation in the physical properties of the reaction product can be further reduced. In the pre-polycondensation reaction step, in the case of a batch system, it is preferable to set the residence time of each batch to an arbitrary time ±20%.In the case of a continuous system, the amount of material released from the prepolymerization reaction step and the amount of hydroxyaryl compounds vented (including the amount of unreacted aromatic dihydroxy compounds and diaryl carbonates) are monitored so that the variation in residence time in each pre-polycondensation reactor is within ±20% of the desired time. Preferably, the amount of material released from the pre-polycondensation reaction step and the amount of unreacted raw materials, plus diaryl carbonates and / or aromatic dihydroxy compounds added by the raw material supply step described later are adjusted so that the variation in residence time in each pre-polycondensation reactor is within ±20% of the desired time.

[0047] The amount of hydroxyaryl compounds vented as a by-product in each pre-polycondensation reactor (including the amount of unreacted aromatic dihydroxy compounds and diaryl carbonates) can be measured more accurately with more measurement points. However, by, for example, knowing the trend of venting from each point in advance, it is also possible to estimate the total amount by measuring at only one point. Furthermore, the more continuous or frequent the measurements (e.g., every 1 to 60 minutes), the more accurately the venting amount can be determined. However, if the venting amount in a particular apparatus is known to be constant, it is also possible to capture the venting amount relatively accurately even with low-frequency measurements (e.g., every 60 to 720 minutes).

[0048] In step c), the terminal OH% of the reactants after the pre-polycondensation reaction is monitored in order to adjust the amount of additional diaryl carbonate and / or aromatic dihydroxy compound supplied in step e) described later. The more frequently (e.g., every 60 minutes) the terminal OH% is measured, the more frequently the amount of additional diaryl carbonate and / or aromatic dihydroxy compound supplied can be adjusted, and the more stable the terminal OH% can be. However, if the operating conditions such as flow rate, temperature, and pressure are stable and the change in the amount of additional diaryl carbonate and / or aromatic dihydroxy compound supplied is small, even with low-frequency measurements (every 60 to 720 minutes), control within ±2.0% of the terminal OH% as described later can be maintained. The average degree of polymerization n of the reactants after the pre-polycondensation reaction is preferably 40 to 110. The average degree of polymerization n can be adjusted to a preferred range by satisfying the conversion rate, temperature, and pressure in the transesterification reaction described above.

[0049] <Step d): Polycondensation reaction> A polycondensation reaction is a reaction that increases the degree of polymerization of the reactants obtained in a pre-polycondensation reaction to any value of 110 or higher. The polycarbonate of this embodiment comprises multiple polycarbonate main chains. These multiple polycarbonate main chains as a whole may be partially branched, with each chain being linked to at least one side chain via a branch selected from the group consisting of ester bonds and ether bonds. In other words, since the polycarbonate of this embodiment is obtained by melt polymerization, two types of transition reactions can occur in the polycondensation reaction step, resulting in the formation of two types of branched structures.

[0050] Furthermore, the manufacturing apparatus for producing polycarbonate in this embodiment may be any apparatus that has sufficient mechanical strength, or it may be an apparatus that has any other devices or equipment with any other functions necessary for continuous polycarbonate manufacturing operation.

[0051] The polycondensation reaction can be carried out in a batch manner, where all the pre-polycondensation reactants are loaded into the polycondensation reactor before the reaction, or in a continuous manner, where the pre-polycondensation reactants are continuously supplied while the reaction is carried out.

[0052] The polycondensation reactor installed in step d) is preferably equipped with a vent to remove the hydroxyaryl reaction products generated, from the viewpoint of advancing the polycondensation reaction. There are no particular restrictions on the polycondensation reactor used for the polycondensation of the pre-polycondensation reactant, but it is preferable to use a polycondensation reactor with a large surface area to evaporate by-products such as monohydroxy compounds. Specifically, ring-disk reactors, thin-film polymerizers, centrifugal thin-film evaporation polymerizers, surface-renewal twin-screw kneading polymerizers, wet-wall polymerizers, perforated plate polymerizers that polymerize while free-falling, and guided contact-fall polymerization apparatuses that allow polycondensation to proceed by melting and dropping the polymer along a support are used, and polycondensation reactors using one or more of these types are used. An example of a guided contact-fall polymerization apparatus is a wire-equipped perforated plate polymerizer. Examples of ring-disk reactors include single-screw horizontal stirring reactors and twin-screw horizontal stirring reactors, specifically those described in US2008 / 0064834 and US8017717. Among these polycondensation reactors, guided contact flow polymerization apparatuses or ring-disk reactors are preferred from the viewpoint of being able to increase the degree of polymerization.

[0053] Figure 3 shows a schematic configuration diagram of a guided contact flow polymerization apparatus. The guided contact flow polymerization apparatus 10 includes a liquid inlet 11, a perforated plate 12, a liquid supply zone 13 for supplying liquid to the guides 14 of the evaporation zone 15 through the perforated plate 12, an evaporation zone 15 in which a plurality of guides 14 extending downward from the perforated plate 12 are provided in the space surrounded by the perforated plate 12, a side casing 18 and a bottom casing 19, a vacuum vent port 16 provided in the evaporation zone 15, and a liquid outlet port 17 provided at the very bottom of the bottom casing. The raw material / prepolymer introduced from the liquid inlet 11 flows downward along the guides 14. At that time, polycondensation proceeds as the raw material / prepolymer flows, and the by-product hydroxyaryl reaction product is released from the vacuum vent port 16.

[0054] By using the guided contact flow polymerization apparatus described above, it is possible to obtain concentrated liquids and polymers with less discoloration, higher quality, and higher performance. Furthermore, by using the guided contact flow polymerization apparatus, it is possible to stably produce the evaporated liquid at a rate of more than 1 ton per hour, and for long periods of several thousand hours or more, for example, more than 5,000 hours.

[0055] The temperature for the polycondensation reaction is preferably 260 to 320°C. The polycondensation pressure is preferably 0.025 kPaA to 1.0 kPaA, and more preferably 0.05 kPaA to 0.75 kPaA. The polycondensation reaction may be carried out in a single reactor, or in multiple reactors installed in series or parallel.

[0056] By changing the reaction temperature, reaction pressure (degree of reduced pressure), reaction time (residence time in the polycondensation reactor), etc., in the polycondensation reaction process, polycarbonates with different molecular weights can be produced. There are no particular restrictions on the degree of polymerization n of the reactants after the polycondensation reaction, but it is usually in the range of n = 110 to 200.

[0057] The ratio of hydroxyl groups to aryl carbonate groups in the polycarbonate obtained by polymerization is not particularly limited, but is usually in the range of 95:5 to 5:95, preferably in the range of 90:10 to 10:90, and more preferably in the range of 80:20 to 20:80. Particularly preferred is a polycarbonate in which the proportion of phenyl carbonate groups in the terminal groups is 85 mol% or more, from the viewpoint of heat stability and hue.

[0058] <Process e): Recovery Process> In step e), diaryl carbonate and / or aromatic dihydroxy compounds encompassed to the hydroxyaryl reaction product in at least one of steps b) to d) are recovered. In steps b) to d), hydroxyaryl reaction products are generated and discharged from the reactor. The hydroxyaryl reaction products are discharged from the reactor accompanied by diaryl carbonate and / or aromatic dihydroxy compounds, but the diaryl carbonate and / or aromatic dihydroxy compounds are separated and recovered from the hydroxyaryl reaction products. From the viewpoint of minimizing raw material loss, it is preferable to recover the diaryl carbonate and / or aromatic dihydroxy compounds accompanied by the hydroxyaryl reaction products in all steps b) to d). The recovery method is not particularly limited and can be recovered by conventionally known methods, such as scrubbers or distillation columns.

[0059] <Step f): Raw material addition process before supplying to the transesterification reactor> In step f), at least a portion of the diaryl carbonate and / or aromatic dihydroxy compound recovered in step e) is added to the raw material mixture before supplying it to the transesterification reactor. In step f), that is, at any point before step b), the discharge of unreacted raw materials can be reduced by supplying additional diaryl carbonate and / or aromatic dihydroxy compound. The diaryl carbonate and / or aromatic dihydroxy compound may be newly added rather than recovered.

[0060] In addition to the addition before supplying to the transesterification reactor, diaryl carbonate and / or aromatic dihydroxy compounds may also be added between steps b) and d) (see step g) below). However, if the additional supply is placed between steps b) and d), the diaryl carbonate and / or aromatic dihydroxy compounds will be directly supplied to the process under reduced pressure conditions, increasing the amount of unreacted raw materials discharged from the system as the added diaryl carbonate and / or aromatic dihydroxy compounds are again carried along with the vapor of the hydroxyaryl reaction product and discharged outside the system. In contrast, if the additional supply of diaryl carbonate and / or aromatic dihydroxy compounds is placed upstream of the supply piping to step b), discharge from the system at the time of additional supply will be virtually eliminated, as the process is basically at atmospheric pressure or slightly pressurized. As the reaction between the additionally supplied diaryl carbonate and the aromatic dihydroxy compound progresses and the molecular weight increases, even under reduced pressure conditions, the reaction becomes less volatile when only one molecule each of carbonate and aromatic dihydroxy reacts. Therefore, the proportion of the reaction product that is carried over to the vapor of the hydroxyaryl reaction product and discharged outside the system decreases. The diaryl carbonate and aromatic dihydroxy compound discharged outside the system cannot be fully recovered, and is recovered at a roughly constant rate regardless of the amount discharged. Therefore, setting the additional supply location of the diaryl carbonate and / or aromatic dihydroxy compound to any location before step b) and reducing the amount of unreacted raw materials of the additionally supplied diaryl carbonate and aromatic dihydroxy compound discharged outside the system reduces the loss of diaryl carbonate and aromatic dihydroxy compound, resulting in better economic performance.

[0061] The terminal OH% of the reaction product to be used in step d) can also be adjusted by the amount of diaryl carbonate and / or aromatic dihydroxy compound added to the raw material mixture in step f). The terminal OH% of the reaction product to be used in step d) is basically determined by the ratio of diaryl carbonate and aromatic dihydroxy compound used in the transesterification reaction. However, since some of the diaryl carbonate and / or aromatic dihydroxy compound is discharged through the vents of the transesterification reaction step, pre-polycondensation reaction step, or polycondensation reaction step, a deviation occurs from the pre-set ratio of diaryl carbonate and aromatic dihydroxy compound, and the terminal OH% of the reaction product to be used in step d) does not reach the desired value. By using this step, the terminal OH% of the reaction product to be used in step d) can be adjusted to the desired value by adjusting the amount of additional diaryl carbonate and / or aromatic dihydroxy compound supplied while monitoring the terminal OH% of the reaction product to be used in step d). The terminal OH% of the reaction product supplied to step d) can be monitored, for example, by sampling the reaction product of the pre-polycondensation reaction supplied to the polycondensation reactor in step d) and measuring it according to the terminal OH% measurement method described later.

[0062] The adjustment of the terminal OH% of the reaction product to be used in step d) is possible, as shown in step g) below, whether the additional supply of diaryl carbonate and / or aromatic dihydroxy compound is set between steps b) and d), or at any location before step b). However, if the additional supply is set between steps b) and d), diaryl carbonate and / or aromatic dihydroxy compound will be supplied directly to the process under reduced pressure conditions, increasing the proportion of the added diaryl carbonate and / or aromatic dihydroxy compound that is again carried out with the vapor of the hydroxyaryl reaction product and discharged outside the system. In contrast, if the additional supply of diaryl carbonate and / or aromatic dihydroxy compound is set upstream of the supply piping to step b), discharge outside the system at the time of additional supply is almost nonexistent because the process is basically at atmospheric pressure or slightly pressurized. As the reaction between the additionally supplied diaryl carbonate and the aromatic dihydroxy compound progresses and the molecular weight increases (even at the stage where only one molecule each of carbonate and aromatic dihydroxy has reacted), it becomes less volatile even under reduced pressure, thus reducing the proportion that is carried out of the system along with the vapor of the hydroxyaryl reaction product. Since it is not possible to recover the entire amount of diaryl carbonate and aromatic dihydroxy compound discharged from the system, and a roughly constant proportion is recovered regardless of the amount of diaryl carbonate and aromatic dihydroxy compound discharged from the system, it is more economical to set the additional supply location of diaryl carbonate and / or aromatic dihydroxy compound to any location before step b), thereby reducing the proportion of the additionally supplied diaryl carbonate and aromatic dihydroxy compound discharged from the system, as this reduces the loss of diaryl carbonate and aromatic dihydroxy compound. Furthermore, in this embodiment, the terminal OH% of the reaction product subjected to step d) tends to maintain a constant value, and even with monitoring as described above, there are not many instances where deviations in the terminal OH% require adjustment. This is because, as mentioned earlier, by supplying the diaryl carbonate and / or aromatic dihydroxy compounds recovered from each step to a step before the supply piping of step b), the recycled components have more opportunities to increase their molecular weight through the reaction, and less is discharged outside the system again, thus reducing the loss of diaryl carbonate and aromatic dihydroxy compounds. As a result of this reduction in discharge outside the system, the ratio of diaryl carbonate and / or aromatic dihydroxy compounds supplied as raw materials and contributing to the reaction from step b) through step c) tends to deviate from the value set in the supply of step b). Consequently, a derivative effect is obtained in which the terminal OH% of the reaction product subjected to step d) tends to maintain the desired value.

[0063] The terminal OH% of the reaction product introduced in step d) is preferably controlled within ±2.0%, more preferably within ±1.9%, and even more preferably within ±1.8%. By controlling within this OH% range, the molecular weight of the resulting polycarbonate can be stabilized.

[0064] The diaryl carbonate and / or aromatic dihydroxy compound supplied in addition to the raw material mixture before it is supplied to the transesterification reactor may be fresh, but from an economic standpoint, the raw materials (aromatic dihydroxy compound and diaryl carbonate) are usually purified from the condensate of steam recovered from the vents of each reactor. The additional supply of the raw materials (aromatic dihydroxy compound and diaryl carbonate) may be supplied in its entirety from one location or in divided portions from multiple locations, as long as it is an additional supply to the raw material mixture before it is supplied to the transesterification reactor. The temperature of the additionally supplied diaryl carbonate and / or aromatic dihydroxy compound is not particularly limited as long as it is above the melting temperature of the additionally supplied raw materials, but it is preferably 200°C or lower.

[0065] Furthermore, in addition to the raw materials (aromatic dihydroxy compounds and diaryl carbonates), polycarbonates with different hydroxyl group end ratios and end structures can also be produced by supplying known end modifiers such as the aforementioned aromatic dihydroxy compounds, hydroxyl-terminated polycarbonate prepolymers (low-polymerization polycarbonates), the aforementioned diaryl carbonates, aryl carbonate-terminated polycarbonate prepolymers, and monofunctional substituted phenols such as t-butylphenol and t-octylphenol.

[0066] <Process g): Raw material addition process from process b) to process d)> The method for producing aromatic polycarbonate in this embodiment is: g) Add diaryl carbonate and / or aromatic dihydroxy compounds to the raw material mixture between b) and d), It may also have the following:

[0067] The adjustment of the terminal OH% of the reaction product subjected to step d) is possible whether the additional supply of diaryl carbonate and / or aromatic dihydroxy compound is performed between step b) and step d), or at any point before step b).

[0068] The diaryl carbonate and / or aromatic dihydroxy compound added in step g) is the same as that described in step f).

[0069] The proportion of diaryl carbonate and aromatic dihydroxy compound added in step f) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 100% by mass, based on the total amount of diaryl carbonate and aromatic dihydroxy compound added in steps f) and g).

[0070] <Catalyst deactivator> The method for producing polycarbonate according to this embodiment may include a step of adding a catalyst deactivator. Any known catalyst deactivator can be used as the catalyst deactivator, but from the viewpoint of producing polycarbonate with high thermal stability and low discoloration, ammonium salts and phosphonium salts of sulfonic acid are preferred, and examples of the above salts of dodecylbenzenesulfonic acid, such as tetrabutylphosphonium dodecylbenzenesulfonate, are used.

[0071] Furthermore, esters of sulfonic acids can also be used. Examples of such esters include octyl benzenesulfonate, phenyl benzenesulfonate, methyl p-toluenesulfonate, ethyl p-toluenesulfonate, butyl p-toluenesulfonate, octyl p-toluenesulfonate, phenyl p-toluenesulfonate, and diphenylhydrogen phosphite. In particular, from the viewpoint of producing polycarbonates with high thermal stability and low discoloration, tetrabutylphosphonium dodecylbenzenesulfonate is preferably used.

[0072] Furthermore, phosphite esters can also be preferably used, including diphenyl monodecyl phosphite, trioleyl phosphite, tridecyl phosphite, trilauryl phosphite, tris(tridecyl) phosphite, diphenyl mono(2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, diphenyl mono(tridecyl) phosphite, and diphenyl hydrogen phosphite, with diphenyl hydrogen phosphite being preferably used.

[0073] The amount of catalyst deactivator used is preferably 0.5 to 50 moles per mole of transesterification catalyst, more preferably 0.5 to 10 moles, and even more preferably 0.8 to 5 moles.

[0074] The catalyst deactivator may be added, for example, after step d), and then the extruder may be connected and extrusion molding may be performed.

[0075] <Additives> The method for producing polycarbonate according to this embodiment may include a step of adding additives. Examples of additives include resins other than polycarbonate, such as ABS and PET, as well as various stabilizers, antioxidants, UV absorbers, mold release agents, dyes and pigments, and flame retardants. This makes it possible to produce polycarbonate resin compositions suitable for various applications.

[0076] Furthermore, by combining these, a variety of polycarbonate resin compositions can be manufactured.

[0077] Examples of additives include heat stabilizers, antioxidants, light stabilizers, UV absorbers, mold release agents, dyes and pigments, as well as metal deactivators, antistatic agents, lubricants, nucleating agents, and so on.

[0078] Examples of heat-resistant stabilizers and antioxidants include, but are not limited to, phosphorus compounds, phenolic stabilizers, organic thioether stabilizers, and hindered amine stabilizers.

[0079] Examples of light stabilizers and UV absorbers include, but are not limited to, salicylic acid-based UV absorbers, benzophenone-based UV absorbers, benzotriazole-based UV absorbers, and cyanoacrylate-based UV absorbers.

[0080] Known release agents can be used, and are not limited to the following, but include, for example, hydrocarbon-based release agents such as paraffins, aliphatic acid-based release agents such as stearic acid, fatty acid amide-based release agents such as stearic acid amide, alcohol-based release agents such as stearyl alcohol and pentaerythritol, aliphatic ester-based release agents such as glycene monostearate, and silicone-based release agents such as silicone oil.

[0081] As dyes and pigments, known organic and inorganic dyes and pigments can be used. In addition, for metal deactivators, antistatic agents, lubricants, and lubrication agents, known materials that exhibit these properties can be used depending on the purpose. These may be used individually or in combination of two or more types.

[0082] The additive may be added, for example, after step d), and then the extruder may be connected and extrusion molding may be performed. [Examples]

[0083] The present invention will be described in more detail below with reference to specific examples. However, the present invention is not limited in any way to the examples shown below.

[0084] <Terminal OH%> Dissolve 0.3g of the sample in 5ml of deuterium-substituted chloroform and analyze it in a nuclear magnetic resonance analyzer at 23°C. 1 End groups were measured using 1H-NMR (Valqua EX-400). The hydroxyl group end concentration (mol%) was calculated based on the ratio of hydroxyl groups to the number of hydroxyl ends. The above-mentioned terminal OH% measurements were performed every four hours until 72 hours after the start of manufacturing. The average of the measured terminal OH% values ​​was calculated, and the maximum error from the average OH% value was determined.

[0085] <Weight average molecular weight (Mw)> Prepolymers or pellets were used as the target of measurement, and the results were obtained using gel permeation chromatography (HLC-8320GPC, manufactured by Tosoh Corporation, with two TSK-GEL Super Multipore HZ-M tubes and an RI detector), with tetrahydrofuran as the eluent, at a temperature of 40°C. The weight-average molecular weight of the prepolymer or pellet was determined using the converted molecular weight calibration curve obtained from the calibration curve of standard monodisperse polystyrene (EasiVial VARIAN) using the following formula. M PC =0.3591M PS 1.0388 (In the formula, M PC M is the molecular weight of aromatic polycarbonate. PS (This indicates the molecular weight of polystyrene.)

[0086] <Conversion rate of aromatic dihydroxy compounds> 0.5 g of the reaction solution and 0.05 g of phenylurethane as an internal standard were dissolved in 40 mL of THF. An ACQUITY UPLC (Waters) column was used, and a mixed eluent consisting of distilled water and acetonitrile was used as the eluent. The column temperature was 40°C, and the distilled water / acetonitrile solution ratio was started at 80 / 20. After 1.5 minutes, the ratio was gradually increased to 30 / 70 over 4.5 minutes, held at 30 / 70 for 2 minutes, then gradually increased to 0.1 / 99.9 over 2 minutes, held at that ratio for 0.9 minutes, and then increased to 80 / 20 over 0.1 seconds.

[0087] A 1.8 μm, 100 mm long HSS T3 column was used, and measurements were performed using a UV detector with a detection wavelength of 254 nm. The amount of unreacted aromatic dihydroxy compound in the reaction solution was determined from the extinction coefficient of the internal standard substance, and this was subtracted from the amount of aromatic dihydroxy compound added to determine the addition rate of the aromatic dihydroxy compound.

[0088] [Example 1] Polycarbonate was manufactured using a polycarbonate manufacturing apparatus having the configuration shown in Figure 4, as described below. The apparatus shown in Figure 4 has a raw material supply unit 71 for supplying diaryl carbonate and / or aromatic dihydroxy compounds from am, a raw material supply unit 72 for supplying diaryl carbonate and / or aromatic dihydroxy compounds from ao, a raw material supply unit 73 for supplying diaryl carbonate and / or aromatic dihydroxy compounds from bm, a raw material supply unit 74 for supplying diaryl carbonate and / or aromatic dihydroxy compounds from bo, a raw material supply unit 75 for supplying diaryl carbonate and / or aromatic dihydroxy compounds from cm, and a raw material supply unit 76 for supplying diaryl carbonate and / or aromatic dihydroxy compounds from co, and is configured so that the introduction position can be changed and its effect can be evaluated. Agitation tank type mixing tank 1 (capacity 40m³) 3 A total of 23 tons / h of molten diphenyl carbonate (hereinafter "DPC") and bisphenol A (hereinafter "BPA") (DPC / BPA mol ratio = 1.0) and potassium hydroxide were supplied to the 200 ppb by mass relative to the diphenyl carbonate, and mixed at 200°C. Next, a transfer pump was used to stir-fed transesterification reactors 2 and 3 (contents 30 m³). 3 The material was then transferred to the following reactors for the transesterification reaction: the transesterification reaction in transesterification reactor 2 was carried out at 200°C / 60kPaA, and the transesterification reaction in transesterification reactor 3 was carried out at 220°C / 15kPaA. Next, the material was transferred using a transfer pump to the stirred tank type pre-polycondensation reactors 4 and 5 (capacity 20m³). 3The material was then transferred to the following reactors for a pre-polycondensation reaction. The pre-polycondensation reaction in pre-polycondensation reactor 4 was conducted at 250°C / 10kPaA, and the pre-polycondensation reaction in pre-polycondensation reactor 5 was conducted at 280°C / 5kPaA. Next, the material was transferred to guided contact-flow type polycondensation reactor 6 by a transfer pump for the polycondensation reaction. The polycondensation reaction in polycondensation reactor 6 was conducted at 280°C / 0.5kPaA, and the operation was continued for 12 hours. After that, the composition of the condensate from each vent was analyzed every hour until the end of operation to calculate the amount of DPC and BPA discharged from each vent per hour, and their average values ​​were calculated. (DPC discharged: 749 kg / h, BPA discharged: 29 kg / h) Subsequently, in order to bring the terminal OH% closer to the desired value, the entire amount of DPC and BPA purified and recovered from the condensate of each vent was used to start the additional supply of DPC and BPA from supply point am. (The average values ​​of the additional supply from 6 hours to 72 hours after the start of additional supply were 414 kg / h for DPC and 13 kg / h for BPA.) From 6 hours to 72 hours after the start of additional supply, the amount of DPC and BPA discharged from each vent and the amount of DPC and BPA purified and recovered from the condensate of each vent were recorded every hour, and the average difference was evaluated as the loss amount. In addition, from 6 hours to 72 hours after the start of additional supply, the terminal OH% after the pre-polycondensation reaction and the molecular weight (Mw) after the polycondensation reaction were measured every 4 hours. The loss amount and measurement results are shown in Table 1.

[0089] [Example 2] In Example 1, polycarbonate was produced using the same procedure as in Example 1, except that the supply points for DPC and BPA were changed from am to a-o, and the average amount of additional supply was used from 6 hours after the start of additional supply to 72 hours later, as shown in Table 1. Loss amounts were evaluated, molecular weight (Mw) was measured, and terminal OH% was measured. The results are shown in Table 1.

[0090] [Example 3] In Example 1, polycarbonate was produced using the same procedure as in Example 1, except that the additional supply of DPC and BPA was made equal to the amount discharged outside the system from each vent, using DPC and BPA purified and recovered from the condensate of each vent plus new raw materials. Loss amounts were evaluated, molecular weight (Mw) was measured, and terminal OH% was measured, and the results are shown in Table 1.

[0091] [Example 4] In Example 1, polycarbonate was produced using the same procedure as in Example 1, except that the initial DPC / BPA mol ratio was changed from 1.0 to 1.2. Loss was evaluated, molecular weight (Mw) was measured, and terminal OH% was measured. The results are shown in Table 1.

[0092] [Example 5] In Example 4, polycarbonate was produced using the same procedure as in Example 4, except that the pressures in steps c) and d) were as shown in Table 1. Loss evaluation, molecular weight (Mw), and terminal OH% were measured, and the results are shown in Table 1.

[0093] [Comparative Example 1] To verify the effect of the additional supply location of DPC and BPA in Example 1, polycarbonate was manufactured using the same procedure as in Example 1, except that the supply point was changed from am to bm. Loss amount was evaluated, molecular weight (Mw) was measured, and terminal OH% was measured. The results are shown in Table 1.

[0094] [Comparative Example 2] To verify the effect of the additional supply location of DPC and BPA in Example 1, polycarbonate was manufactured using the same procedure as in Example 1, except that the supply point was changed from am to bo. Loss amount was evaluated, molecular weight (Mw) was measured, and terminal OH% was measured. The results are shown in Table 1.

[0095] [Comparative Example 3] To verify the effect of the additional supply position of DPC and BPA in Example 1, polycarbonate was manufactured using the same procedure as in Example 1, except that the supply point was changed from am to cm. Loss amount was evaluated, molecular weight (Mw) was measured, and terminal OH% was measured. The results are shown in Table 1.

[0096] [Comparative Example 4] To verify the effect of the additional supply location of DPC and BPA in Example 1, polycarbonate was manufactured using the same procedure as in Example 1, except that the supply point was changed from am to co. Loss amount was evaluated, molecular weight (Mw) was measured, and terminal OH% was measured. The results are shown in Table 1.

[0097] [Comparative Example 5] To verify the effect of the additional supply location of DPC and BPA in Example 3, polycarbonate was manufactured using the same procedure as in Example 3, except that the supply point was changed from am to co. Loss amount was evaluated, molecular weight (Mw) was measured, and terminal OH% was measured. The results are shown in Table 1.

[0098] [Comparative Example 6] To verify the effect of the additional supply location of DPC and BPA in Example 4, polycarbonate was manufactured using the same procedure as in Example 4, except that the supply point was changed from am to co. Loss amount was evaluated, molecular weight (Mw) was measured, and terminal OH% was measured. The results are shown in Table 1.

[0099] [Comparative Example 7] To verify the effect of the additional supply location of DPC and BPA in Example 5, polycarbonate was manufactured using the same procedure as in Example 5, except that the supply point was changed from am to co. Loss amount was evaluated, molecular weight (Mw) was measured, and terminal OH% was measured. The results are shown in Table 1.

[0100] As shown in Table 1, it was found that adding DPC and BPA to the raw material mixture before supplying it to the transesterification reactor reduces the amount of raw material loss in the production of polycarbonate compared to adding DPC and BPA after step b). Furthermore, it was found that an additional effect of adding DPC and BPA to the raw material mixture before supplying it to the transesterification reactor is that the controllability of the terminal OH% is improved and the molecular weight (Mw) after the polycondensation reaction is stabilized. When DPC and BPA are added after step b), the amount of discharged material outside the system and the amount of recovered raw materials are unstable. Therefore, as in Comparative Example 5, by using new raw materials in addition to DPC and BPA purified and recovered from the condensate of each vent, the controllability of the terminal OH% can be improved by continuously adjusting the amount of discharged material outside the system from each vent and the amount of additional supply to be equal. On the other hand, when DPC and BPA are added to the raw material mixture before supplying it to the transesterification reactor, the amount of discharged material outside the system is stable, so the controllability of the terminal OH% is good even without the adjustments made in Comparative Example 5.

[0101] [Example 6] Polycarbonate was manufactured using a polycarbonate manufacturing apparatus having the configuration shown in Figure 4, as described below. Ring-disk type apparatuses were used as the pre-polycondensation reactors 4 and 5 and the polycondensation reactor 6. Mixing tank type 1 (Capacity 2m³) 3 A total of 70 kg / h of molten diphenyl carbonate (hereinafter "DPC") and bisphenol A (hereinafter "BPA") (DPC / BPA mol ratio = 1.1) and potassium hydroxide were supplied to the molten diphenyl carbonate at a concentration of 200 ppb by mass, and mixed at 200°C. Next, a transfer pump was used to stir-fed transesterification reactors 2 and 3 (contents 2 m³). 3 The material was then transferred to the transesterification reactors 4 and 5 (with a volume of 2 m³) and the transesterification reaction was carried out. The transesterification reaction in transesterification reactor 2 was carried out at 210°C / 40 kPaA, and the transesterification reaction in transesterification reactor 3 was carried out at 220°C / 10 kPaA. Next, the material was transferred using a transfer pump to ring-disk type pre-polycondensation reactors 4 and 5 (with a volume of 2 m³). 3The material was then transferred to the pre-polycondensation reactor 4 and a pre-polycondensation reaction was carried out. The pre-polycondensation reaction in pre-polycondensation reactor 4 was carried out at 250°C / 7kPaA, and the pre-polycondensation reaction in pre-polycondensation reactor 5 was carried out at 280°C / 3kPaA. Next, the material was transferred to the ring-disk type polycondensation reactor 6 by a transfer pump and a polycondensation reaction was carried out. The polycondensation reaction in polycondensation reactor 6 was carried out at 310°C / 0.2kPaA. The above operation was continued for 12 hours. After that, the composition of the condensate from each vent was analyzed every hour until the end of the operation to calculate the amount of DPC and BPA discharged from each vent per hour, and the average values ​​were calculated. (DPC discharged: 2.3 kg / h, BPA discharged: 0.17 kg / h) After that, in order to bring the terminal OH% closer to the desired value, the entire amount of DPC and BPA purified and recovered from the condensate of each vent was used to start the additional supply of DPC and BPA from supply point am. (The average values ​​of the additional supply from 6 to 72 hours after the start of additional supply were 1.42 kg / h for DPC and 0.10 kg / h for BPA.) From 6 to 72 hours after the start of additional supply, the amount of DPC and BPA discharged from each vent and the amount of DPC and BPA purified and recovered from the condensate of each vent were recorded every hour, and the average difference was evaluated as the loss amount. In addition, from 6 to 72 hours after the start of additional supply, the terminal OH% after the pre-polycondensation reaction and the molecular weight (Mw) after the polycondensation reaction were measured every 4 hours. The loss amount and measurement results are shown in Table 2.

[0102] [Example 7] In Example 6, polycarbonate was produced using the same procedure as in Example 6, except that the pressures in steps c) and d) were as shown in Table 2. Loss evaluation, molecular weight (Mw) measurement, and terminal OH% measurement were performed, and the results are shown in Table 2.

[0103] [Comparative Example 8] To verify the effect of the additional supply position of DPC and BPA in Example 6, polycarbonate was manufactured using the same procedure as in Example 6, except that the supply point was changed from am to cm. Loss amount was evaluated, molecular weight (Mw) was measured, and terminal OH% was measured. The results are shown in Table 2.

[0104] [Comparative Example 9] To verify the effect of the additional supply position of DPC and BPA in Example 7, polycarbonate was manufactured using the same procedure as in Example 7, except that the supply point was changed from am to cm. Loss amount was evaluated, molecular weight (Mw) was measured, and terminal OH% was measured. The results are shown in Table 2.

[0105] As shown in Table 2, even when a ring-disk type reactor is used as the reactor for the pre-polycondensation reaction and the polycondensation reaction, it was found that adding DPC and BPA to the raw material mixture before supplying it to the transesterification reactor reduces the amount of raw material loss in the production of polycarbonate compared to adding DPC and BPA in step b) and later.

[0106] [Table 1]

[0107] [Table 2]

Claims

1. A method for producing aromatic polycarbonate, Next steps a) to f): a) Mixing raw materials in a mixing tank for raw material mixing using one or more aromatic dihydroxy compounds and one or more diaryl carbonates. b) In at least one transesterification reactor, the starting material mixture is subjected to a transesterification reaction while removing the resulting hydroxyaryl reaction product. c) In at least one pre-polycondensation reactor, the reaction product of the transesterification reaction is subjected to a pre-polycondensation reaction while removing the resulting hydroxyaryl reaction product. d) In at least one polycondensation reactor, the reaction products of the pre-polycondensation reaction are subjected to polycondensation while removing the resulting hydroxyaryl reaction products. e) Recovering diaryl carbonate and / or aromatic dihydroxy compounds encombusted with the hydroxyaryl reaction product in at least one of the steps b) to d) above, and f) Adding at least a portion of the recovered diaryl carbonate and / or aromatic dihydroxy compound to the raw material mixture before supplying it to the transesterification reactor. A method for producing aromatic polycarbonate having [a certain characteristic].

2. The method for producing an aromatic polycarbonate according to claim 1, wherein in (b) above, the conversion rate of the aromatic dihydroxy compound and / or the diaryl carbonate is 70 to 100%.

3. The method for producing an aromatic polycarbonate according to claim 1 or 2, wherein the average degree of polymerization n of the reaction product in b) is 1 to 20.

4. The method for producing an aromatic polycarbonate according to claim 1 or 2, wherein the average degree of polymerization n of the reaction product in c) is 40 to 110.

5. A method for producing an aromatic polycarbonate according to claim 1 or 2, comprising monitoring the terminal OH% of the reaction product introduced into the polycondensation reactor and determining the amount of the diaryl carbonate and / or the aromatic dihydroxy compound to be added to the raw material mixture in step f) based on the terminal OH%.

6. A method for producing an aromatic polycarbonate according to claim 1 or 2, wherein the ratio of diaryl carbonate to aromatic dihydroxy compound used in b) is controlled to within ±2.0% of the terminal OH% of the reaction product introduced in d).

7. The method for producing an aromatic polycarbonate according to claim 1 or 2, wherein the aromatic dihydroxy compound is a compound represented by formula (1): HO-Z-OH...(1) (wherein Z is a divalent organic group having 6 to 30 carbon atoms containing one or more aromatic groups).

8. The method for producing an aromatic polycarbonate according to claim 1 or 2, wherein the diaryl carbonate is a diester carbonate having an aromatic group having 5 to 20 carbon atoms.

9. The method for producing an aromatic polycarbonate according to claim 1 or 2, wherein the aromatic dihydroxy compound is bisphenol A and the diaryl carbonate is diphenyl carbonate.

10. The aforementioned transesterification reaction is carried out in the presence of a catalyst. The method for producing an aromatic polycarbonate according to claim 1 or 2, wherein the catalyst is added in the form of at least one alkali metal salt, or a mixture of at least one alkali metal salt of an aromatic alcohol and at least one boric acid ester of an aromatic alcohol.

11. The method for producing an aromatic polycarbonate according to claim 10, wherein the catalyst is obtained by adding a mixture of 0.05 to 2 ppm by mass of an alkali metal salt, or 0.1 to 2 ppm by mass of an alkali metal phenolate, and 0.25 to 3 ppm by mass of a borate ester of an aromatic alcohol to a raw material aromatic dihydroxy compound.

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