Method for producing aromatic polycarbonate

Abstract

Provided is a method for producing an aromatic polycarbonate, by which the molecular weight of the resulting polycarbonate is stabilized.　Disclosed is a method for producing an aromatic polycarbonate, the method comprising the following steps a) to d): a) performing transesterification using one or more aromatic dihydroxy compounds and one or more diaryl carbonates within a transesterification reactor while removing hydroxyaryl reaction products that are generated; b) subjecting the transesterification reaction product to prepolycondensation while removing the generated hydroxyaryl reaction products within at least one prepolycondensation reactor; c) subjecting the prepolycondensation reaction product to polycondensation within at least one polycondensation reactor; and d) adding diaryl carbonates and / or aromatic dihydroxy compounds between the aforementioned steps a) through c). The terminal OH% of the reaction product introduced in step c) is controlled to within ±2.0% by adjusting the ratio of the diaryl carbonates and aromatic dihydroxy compounds supplied in step a), step b), and / or step c) and controlling the residence time in step b).

Description

Method for manufacturing aromatic polycarbonates

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

[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). For example, Patent Document 3 describes controlling the OH% of the resulting polymer from the viewpoint of controlling the molecular weight.

[0003] International Publication No. 2005 / 121213, International Publication No. 2013 / 189823, Japanese Patent Publication No. Hei 3-252421

[0004] In the transesterification method for producing polycarbonate, there is a challenge in stabilizing the product properties (molecular weight) of the polycarbonate.

[0005] Patent Document 1 discloses stabilizing the molar ratio of the dihydroxy compound and diaryl carbonate during the reaction and stabilizing the conversion rate of the dihydroxy compound, but these are carried out during the raw material preparation stage, and nothing is disclosed regarding the subsequent pre-polycondensation reaction stage.

[0006] Patent Document 2 attempts to solve the above problem by condensing and recovering a portion of the vapor of the hydroxyaryl compound, which contains droplets of the dihydroxy compound and diaryl carbonate, and then re-adding it in the latter half of the polymerization reaction. However, it is not sufficient as a means to continuously adjust the terminal OH% of the intermediate polymer to the desired value because it is not possible to re-add the entire amount of discharged raw materials and is affected by fluctuations in the operation of the raw material recovery process.

[0007] Patent Document 3 attempts to solve the above problem by calculating the amount of DPC and BPA needed to reach the target terminal OH% of the intermediate polymer based on the analysis results of the terminal OH% of the intermediate polymer, and then re-adding them in the latter half of the polymerization reaction. However, since it takes time to perform the analysis and re-add the substances, this method is not sufficient for continuously adjusting the terminal OH% of the intermediate polymer to the target value.

[0008] As described above, in conventional polycarbonate manufacturing methods, it is difficult to continuously adjust the terminal OH% of the intermediate polymer to the desired value.

[0009] The present invention aims to provide a method for producing aromatic polycarbonate that stabilizes the molecular weight of the resulting polycarbonate.

[0010] The inventors have found that when the vapor of the by-product hydroxyaryl compound is discharged from the system, droplets of the starting materials, dihydroxy compound and diaryl carbonate, are also discharged, and the mol ratio of the starting materials (DPC / BPA) during the polymerization reaction is unstable. As a result, the terminal OH% of the intermediate polymer is unstable, and the molecular weight of the resulting polycarbonate is unstable.

[0011] The present invention encompasses the following embodiments: <1> A method for producing an aromatic polycarbonate, comprising the following steps a) to d): a) a transesterification reaction using one or more aromatic dihydroxy compounds and one or more diaryl carbonates in a transesterification reactor while removing the generated hydroxyaryl reaction products; b) a pre-polycondensation reaction of the reaction products of the transesterification reaction in at least one pre-polycondensation reactor while removing the generated hydroxyaryl reaction products; c) a polycondensation reaction of the reaction products of the pre-polycondensation reaction in at least one polycondensation reactor; and d) adding diaryl carbonates and / or aromatic dihydroxy compounds between steps a) to c); wherein the ratio of diaryl carbonates and aromatic dihydroxy compounds used in steps a), b) and / or c) is controlled, and the residence time in b) is controlled to control the terminal OH% of the reaction product introduced in c) to within ±2.0%. <2> The method for producing an aromatic polycarbonate according to <1>, wherein in a) 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 in a) 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 in b) is 40 to 110. <5> The method for producing an aromatic polycarbonate according to any one of <1> to <4>, wherein the amount of diaryl carbonate and aromatic dihydroxy compound encompassed with the hydroxyaryl reaction product in a) to c) is monitored, and the amount of diaryl carbonate and / or aromatic dihydroxy compound to be added in d) is determined based on that amount. <6> The method for producing an aromatic polycarbonate according to any one of <1> to <5>, wherein the transesterification reaction, the pre-polycondensation reaction and the polycondensation reaction are carried out in a continuous manner.<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 and 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 diester carbonate having aromatic groups 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 method for producing an aromatic polycarbonate according to any one of <1> to <9>, wherein a) is carried out in the presence of a catalyst, and 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 borate ester of an aromatic alcohol. <11> The method for producing an aromatic polycarbonate according to <10>, wherein the catalyst is obtained by adding to a raw material aromatic dihydroxy compound 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.

[0012] According to the present invention, it is possible to provide a method for producing aromatic polycarbonate that stabilizes the molecular weight of the resulting polycarbonate.

[0013] Figure 1 is a schematic diagram of a polycarbonate manufacturing apparatus. Figure 2 is a schematic diagram of a polycarbonate manufacturing apparatus. Figure 3 shows a schematic diagram of a guided contact flow type polymerization apparatus.

[0014] 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.

[0015] [Method for Producing Aromatic Polycarbonate] This embodiment relates to a method for producing aromatic polycarbonate, comprising the following steps a) to d): a) performing a transesterification reaction in a transesterification reactor using one or more aromatic dihydroxy compounds and one or more diaryl carbonates; b) performing a pre-polycondensation reaction on the reaction products of the transesterification reaction in at least one pre-polycondensation reactor while removing the generated hydroxyaryl reaction products; c) performing a polycondensation reaction on the reaction products of the pre-polycondensation reaction in at least one polycondensation reactor; d) adding diaryl carbonates and / or aromatic dihydroxy compounds between steps a) to c); and controlling the ratio of diaryl carbonates and aromatic dihydroxy compounds used in a), b) or c), and controlling the residence time in b), thereby controlling the terminal OH% of the reaction product introduced in c) to within ±2.0%. According to this embodiment, it is possible to provide a method for producing aromatic polycarbonate that stabilizes the molecular weight of the resulting polycarbonate.

[0016] <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.

[0017] 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.

[0018] 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 containing one or more aromatic groups.)

[0019] Aromatic groups include monovalent carbocyclic or heterocyclic aromatic groups. Divalent organic groups include phenylene groups, naphthyl groups, and hydrocarbon groups substituted with two divalent aromatic groups.

[0020] 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.

[0021] 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 also be used in combination to introduce a branched structure.

[0022] In the method for producing a polycarbonate according to this embodiment, the diaryl carbonate used is, for example, a carbonic acid diester having an aromatic group with 5 to 20 carbon atoms.

[0023] The diaryl carbonate is represented, for example, by the following formula. (In the formula, Ar 1 , Ar 2 each represent a monovalent aromatic group having 5 to 20 carbon atoms.)

[0024] Ar 1 and Ar 2 The monovalent aromatic group in represents a monovalent carbocyclic or heterocyclic aromatic group, but in this Ar 1 , Ar 2 , one or more hydrogen atoms may be substituted by other substituents that do not adversely affect the reaction, such as 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. Representative examples of the monovalent aromatic group Ar 1 and Ar 2 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.

[0025] Ar 1 and Ar 2 are preferably those represented by the following formula.

[0026] Representative examples of the diaryl carbonate include substituted or unsubstituted diphenyl carbonates represented by the following formula. (In the formula, R 1 and R 2 each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 ring-constituting carbon atoms, or a phenyl group, and p and q are integers of 1 to 5. When p is 2 or more, each R 1They may be different from each other, and when q is 2 or more, each R 2 may be different from each other.

[0027] Among these diaryl carbonates, symmetric diaryl carbonates such as unsubstituted diphenyl carbonate, ditolyl carbonate, and lower alkyl-substituted diphenyl carbonate such as di-t-butylphenyl carbonate are preferred, and particularly preferred is diphenyl carbonate which is a diaryl carbonate having the simplest structure. These diaryl carbonates may be used alone or in combination of two or more.

[0028] The use ratio (charging ratio) of the aromatic dihydroxy compound and the diaryl carbonate varies depending on the types of the aromatic dihydroxy compound and the diaryl carbonate used, the polymerization temperature, and other polymerization conditions. However, the diaryl carbonate is usually used in a ratio of 0.9 to 2.5 moles, preferably 0.95 to 2.0 moles, more preferably 0.98 to 1.5 moles, per 1 mole of the aromatic dihydroxy compound.

[0029] <Catalyst> The reaction for producing a polycarbonate from an aromatic dihydroxy compound and a diaryl carbonate can be carried out without adding a catalyst, but in order to increase the polymerization rate, it is carried out in the presence of a catalyst as necessary.

[0030] 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; 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); and 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.

[0031] 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 0.05 to 2 ppm by mass relative to the starting aromatic dihydroxy compound. The alkali metal phenolate is preferably 0.1 to 2 ppm by mass relative to the starting aromatic dihydroxy compound. The borate ester of the aromatic alcohol is preferably 0.25 to 3 ppm by mass relative to the starting aromatic dihydroxy compound.

[0032] 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.

[0033] [Polycarbonate Manufacturing Apparatus] 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 manufacturing apparatus. The aromatic polycarbonate manufacturing 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, and a polycondensation reactor 6 for performing a polycondensation reaction. The transesterification reactor, pre-polycondensation reactor, and polycondensation reactor may each be one unit or two or more units.

[0034] As shown in Figure 2, the aromatic polycarbonate manufacturing apparatus includes a mixing tank 1 for mixing polymerization raw materials and a catalyst, two transesterification reactors 2 and 3, two pre-polycondensation reactors 4 and 5, and a polycondensation reactor 6.

[0035] 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.

[0036] 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 1It is a compound represented by the same definition as ). Phenol is an example of a hydroxyaryl reaction product.

[0037] The polycarbonate production equipment according to this embodiment includes a system that allows for the addition of raw materials (dihydroxy compounds and diaryl carbonates) to the piping between reactors in proportion to the amount of raw materials (dihydroxy compounds and diaryl carbonates) that would otherwise be lost by being carried along with the vapor of the hydroxyaryl reaction product discharged from each reactor.

[0038] The method for manufacturing polycarbonate according to this embodiment will be explained using the above-described polycarbonate manufacturing apparatus as an example.

[0039] [Method for producing aromatic polycarbonate] The method may include a step of stirring the raw materials and catalyst in a mixing tank before step a). The mixing of the raw materials and catalyst can be done in a batch manner, where the mixing is performed after all the raw materials and catalyst have been added, or in a continuous manner, where the mixing is performed while the raw materials and catalyst are continuously supplied. The catalyst may be added in multiple stages between steps a) and c). The mixing tank may be a single unit or multiple units may be installed in series or in parallel.

[0040] <Step a): Transesterification reaction> A transesterification reaction is a reaction that increases the degree of polymerization of a reactant consisting of a dihydroxy compound and a diaryl carbonate to any value, with 39 as the upper limit. The transesterification reactor installed in step a) is preferably equipped with a vent to remove the hydroxyaryl reaction product generated, from the viewpoint of carrying out the transesterification reaction. The transesterification reactor may be equipped with a stirring blade that directly stirs the liquid surface. A stirring blade that directly stirs the liquid surface means a stirring blade in which the part of the blade other than the stirring shaft is located at the gas interface. The stirring blade may or may not be located inside the liquid other than the gas-liquid interface, but using a stirring blade that stirs 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, for example, Fardler blades, anchor blades, turbine blades, double helical blades, Maxblend type stirring blades, etc.

[0041] In step a), the mixture used for the transesterification reaction is preferably a mixture that has been melted and mixed at a temperature of 100°C to 250°C, more preferably 140°C to 200°C. The temperature of the transesterification reaction is preferably 160°C to 250°C, more preferably 180°C to 230°C. The pressure of the transesterification reaction is preferably 5 kPaA to 120 kPaA, more preferably 10 kPaA to 110 kPaA.

[0042] 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.

[0043] <Step b): Pre-polycondensation reaction> A pre-polycondensation reaction is a reaction that increases the degree of polymerization of the reactants obtained in the transesterification reaction to an arbitrary value, with 110 as the upper limit. The pre-polycondensation reactor installed in step b) is preferably a reactor equipped with a vent to remove the hydroxyaryl reaction products generated, from the viewpoint of carrying out the pre-polycondensation reaction. More specifically, as a 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. Examples of ring-disk reactors include single-screw horizontal stirring reactors and twin-screw horizontal stirring reactors, specifically those described in US 2008 / 0064834 and US 8017717. 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 transesterification products are charged into the pre-polycondensation reactor before the reaction, or in a continuous manner, where the transesterification 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. A scrubber or the like may be installed in the vent of the pre-polycondensation reactor to recover the raw materials (aromatic dihydroxy compounds and diaryl carbonates) discharged from the vent and reuse them in the production of polycarbonate.

[0044] 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 by installing multiple reactors in series or in parallel. The pre-polycondensation reaction may be carried out in a batch manner, where all the transesterified products are charged 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.

[0045] In step b), the supply amount from step a) 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 transesterification reaction reactor to the inlet of the polycondensation reaction reactor in accordance with the amount of diaryl carbonate and / or aromatic dihydroxy compounds lost in each reactor, so it is preferable to adjust 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 loss of diaryl carbonate and / or aromatic dihydroxy compounds in each reactor is stabilized, allowing for a more accurate determination of the level of additional supply of diaryl carbonate and / or aromatic dihydroxy compounds. After starting the additional supply of diaryl carbonate and / or aromatic dihydroxy compounds, the supply amount to each reactor installed after the additional supply point of diaryl carbonate and / or aromatic dihydroxy compounds will increase by the amount of the additional supply. This increase shortens the residence time in each reactor installed after the additional supply point of diaryl carbonate and / or aromatic dihydroxy compounds compared to before the additional supply started. By adjusting the amount flowing out from each reactor to the next step and increasing the liquid volume in each reactor until the residence time is equivalent to that before the additional supply 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 process, the amount of material released from the prepolymerization reaction 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-polymerization reaction and the amount of hydroxyaryl compounds vented (including the amount of unreacted aromatic dihydroxy compounds and diaryl carbonates) are adjusted so that the amount of material released from the pre-polycondensation reaction is equal to ±20%, more preferably ±15% of the sum of the released and vented amounts. The amount of material released from the pre-polycondensation reaction and the sum of unreacted raw materials, and the amount of diaryl carbonates and / or aromatic dihydroxy compounds added by the raw material supply step described later are adjusted. It is sufficient to match the sum of the released and vented amounts from each reactor with the sum of the supply amounts from the transesterification reaction within a preferred range; the discharge (vent) point and the supply point do not need to be the same. Also, as long as the supply amount from the transesterification reaction is set to a preferred amount, there may be one or more supply ports from the transesterification reaction.

[0046] 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 it is known that the venting amount in a particular apparatus is constant, it is also possible to capture the venting amount relatively accurately even with low-frequency measurements (e.g., every 60 to 720 minutes). 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.

[0047] <Step c): Polycondensation reaction> A polycondensation reaction is a reaction that increases the degree of polymerization of the reactant obtained in the pre-polycondensation reaction to any value of 110 or more. The polycarbonate of this embodiment contains multiple polycarbonate main chains. These multiple polycarbonate main chains as a whole may be partially branched by being bonded to at least one side chain via one type of branching selected from the group consisting of ester bonds and ether bonds. That is, since the polycarbonate of this embodiment is obtained by melt polymerization, two types of transition reactions can occur in the polycondensation reaction step, so two types of branched structures are formed.

[0048] 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 functions or equipment necessary for continuous polycarbonate manufacturing operation.

[0049] 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.

[0050] The polycondensation reactor installed in step c) 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 reaction product, 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 US 2008 / 0064834 and US 8017717. 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.

[0051] 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 discharge 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.

[0052] 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.

[0053] 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 a series or parallel configuration of multiple reactors.

[0054] By changing the reaction temperature, reaction pressure (degree of reduced pressure), and reaction time (residence time in the polycondensation reactor) 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.

[0055] 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.

[0056] <Step d): Additional raw material supply step> Adjust the ratio of diaryl carbonate to aromatic dihydroxy compound used in step a) transesterification reaction, step b) pre-polycondensation reaction, or step c) polycondensation reaction. "Used in step a) transesterification reaction, step b) pre-polycondensation reaction, or step c) polycondensation reaction" means using it in any of the steps, and as a result, the total amount of raw materials used in steps a) to c) will be adjusted. Basically, the entire amount of diaryl carbonate and aromatic dihydroxy compound raw materials is used in the transesterification reaction, but if a portion of it is discharged from the vents of the transesterification reaction, pre-polycondensation reaction step, or polycondensation reaction step, the pre-set ratio of diaryl carbonate to aromatic dihydroxy compound will shift by the time it enters the polycondensation reaction step. Diaryl carbonate and / or aromatic dihydroxy compound discharged from any of the steps may be added between the transesterification reactor in step a) and the inlet of the polycondensation reactor in step c). This process allows the ratio of diaryl carbonate to aromatic dihydroxy compound to the desired value. When using one transesterification reactor in step a), it is preferable to add the mixture between the pre-polycondenser in step b) and the inlet of the polycondensation reactor in step c). When using two or more transesterification reactors in step a), it is preferable to add the diaryl carbonate and / or aromatic dihydroxy compound between the first and subsequent transesterification reactors in step a) and the inlet of the polycondensation reactor in step c). Since the diaryl carbonate and aromatic dihydroxy compound react in step a) transesterification and step b) pre-polycondensation, the amount of diaryl carbonate and aromatic dihydroxy compound flowing into step c) polycondensation is not the same as the amount of raw materials supplied to the transesterification reaction. However, by replenishing the losses in each step in the flow up to the inlet of the polycondensation reaction, the raw material ratio in monomer terms in the polycondensation reaction can be controlled.

[0057] "Adjusting the ratio of diaryl carbonate to aromatic dihydroxy compound" means maintaining the ratio of unreacted diaryl carbonate to aromatic dihydroxy compound within a certain range. The amount of raw materials (aromatic dihydroxy compound and diaryl carbonate) lost along with the vapor of the hydroxyaryl reaction product discharged from each reactor is monitored, and diaryl carbonate and / or aromatic dihydroxy compound are added to minimize the deviation of the ratio of diaryl carbonate to aromatic dihydroxy compound from a predetermined value. For example, it is preferable to add diaryl carbonate and / or aromatic dihydroxy compound in an amount equal to or ±20% by mass relative to the total amount of loss, so that the ratio of the total amount of diaryl carbonate and aromatic dihydroxy compound used at least up to step c) polycondensation reaction remains within ±20% by mass. In the method for producing aromatic polycarbonate according to this embodiment, it is preferable to monitor the amount of diaryl carbonate and aromatic dihydroxy compound encompassed with the hydroxyaryl reaction product from a) to c) and determine the amount of diaryl carbonate and / or aromatic dihydroxy compound to be added in d) based on that amount (hereinafter also referred to as the "method for determining the amount to be added"). Furthermore, this method of determining the amount of each compound to be added in d) based on the monitoring results is particularly effective when the transesterification reaction, the pre-polycondensation reaction, and the polycondensation reaction are carried out in a continuous process. For example, when the prior art described in Patent Document 3 is applied in a continuous process, the OH% of the reaction product discharged from b) is analyzed, and the amount of diaryl carbonate and / or aromatic dihydroxy compound to be added in c) is determined using the analysis results. However, since the reaction product passes through c) before the analysis results of the OH% of the reaction product discharged from b) become clear, the method described in Patent Document 3 is not effective when applied in a continuous process. In contrast, the additive amount determination method used in this embodiment, as described above, can monitor the amount of compound in the intermediate stages of the polymerization process and reflect the measurement results without delay, making it suitable for continuous polymerization methods.

[0058] The terminal OH% of the reaction product introduced in step c) is preferably controlled within ±2.0%, more preferably within ±1.9%, and even more preferably within ±1.8%. By controlling within this range of terminal OH%, the molecular weight of the resulting polycarbonate can be stabilized. The terminal OH% can be measured by the method described in the examples. The terminal OH% can be adjusted by adjusting the ratio of the diaryl carbonate to the aromatic dihydroxy compound subjected to step a), step b), or step c), and by controlling the residence time in step b).

[0059] After supplying diaryl carbonate and / or aromatic dihydroxy compounds, the ratio of diaryl carbonate to aromatic dihydroxy compounds used in step a) transesterification, step b) pre-polycondensation, or step c) polycondensation is preferably 0.5 to 2.5 moles, more preferably 0.6 to 2.0 moles, of diaryl carbonate per mole of aromatic dihydroxy compound. For example, the amount of diaryl carbonate and / or aromatic dihydroxy compound supplied to the flow from the transesterification reactor to the inlet of the polycondensation reactor is preferably an amount equivalent to the amount of raw materials (aromatic dihydroxy compounds and diaryl carbonate) lost by discharge from the vents of each reactor, in order to bring the ratio of diaryl carbonate to aromatic dihydroxy compound closer to the initial charge ratio. The amount of raw materials (aromatic dihydroxy compounds and diaryl carbonates) lost by discharge from the vents of each reactor can be calculated by condensing the entire amount of hydroxyaryl compound vapor containing the raw materials (aromatic dihydroxy compounds and diaryl carbonates) discharged from the vents of each reactor and performing a compositional analysis. This allows for the calculation of the amount of raw materials (aromatic dihydroxy compounds and diaryl carbonates) lost per unit time.

[0060] The diaryl carbonate and / or aromatic dihydroxy compound supplied in addition to the flow from the transesterification reactor to the polycondensation reactor inlet may be fresh, or the raw materials (aromatic dihydroxy compound and diaryl carbonate) may be purified from the condensate of steam recovered from the vents of each reactor. The additional supply of raw materials (aromatic dihydroxy compound and diaryl carbonate) may be supplied entirely from one location or in divided quantities from multiple locations. The temperature of the diaryl carbonate and / or aromatic dihydroxy compound supplied in addition to the flow from the transesterification reactor to the polycondensation reactor inlet 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.

[0061] Furthermore, polycarbonates with different hydroxyl group ratios and terminal structures can also be produced by supplying known terminal 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, instead of the raw materials (aromatic dihydroxy compounds and diaryl carbonates).

[0062] <Catalyst Inactivator> The method for producing polycarbonate according to this embodiment may include a step of adding a catalyst inactivator. Any known catalyst inactivator can be used as the catalyst inactivator, but from the viewpoint of producing polycarbonate with high thermal stability and little 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] The catalyst deactivator may be added, for example, after step c), and then the extruder may be connected and extrusion molding may be performed.

[0067] <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, ultraviolet absorbers, mold release agents, dyes and pigments, and flame retardants. This makes it possible to produce polycarbonate resin compositions suitable for various applications.

[0068] Furthermore, by combining these, a variety of polycarbonate resin compositions can be manufactured.

[0069] 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.

[0070] Examples of heat-resistant stabilizers and antioxidants include, but are not limited to, phosphorus compounds, phenolic stabilizers, organic thioether stabilizers, and hindered amine stabilizers.

[0071] 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.

[0072] 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.

[0073] 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 exhibiting these properties can be used depending on the purpose. These may be used individually or in combination of two or more types.

[0074] The additive may be added, for example, after step c), and then the extruder may be connected and extruded.

[0075] 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.

[0076] <Terminal OH%> Dissolve 0.3 g of sample in 5 ml of deuterium-substituted chloroform and analyze at 23°C using a nuclear magnetic resonance analyzer. １End 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 end OH% measurements were performed once every four hours until 72 hours after the start of manufacturing. The average of the measured end OH% was calculated, and the maximum error from the average end OH% value was calculated.

[0077] <Weight-average molecular weight (Mw)> Prepolymers or pellets were used as the target of measurement, and gel permeation chromatography (HLC-8320GPC, Tosoh Corporation; two TSK-GEL Super Multipore HZ-M vials; RI detector) was used, with tetrahydrofuran as the eluent, and the measurement was performed at a temperature of 40°C. The weight-average molecular weight of the prepolymer or pellets was determined using the converted molecular weight calibration curve obtained from the calibration curve of standard monodisperse polystyrene (EasiVial VARIAN) using the following formula. 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.)

[0078] <Conversion Rate of Aromatic Dihydroxy Compounds> 0.5 g of reaction solution and 0.05 g of phenylurethane as internal standard were dissolved in 40 mL of THF. An ACQUITY UPLC (Waters Corporation) was used, and a mixed eluent consisting of distilled water and acetonitrile was used as the eluent. The column temperature was 40°C, the distilled water / acetonitrile solution ratio was started at 80 / 20, and after 1.5 minutes, it was gradientd to 30 / 70 over 4.5 minutes, held at 30 / 70 for 2 minutes, then gradientd to 0.1 / 99.9 over 2 minutes, held at that ratio for 0.9 minutes, and then gradientd back to 80 / 20 over 0.1 seconds.

[0079] 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 amount was subtracted from the amount of aromatic dihydroxy compound added to determine the addition rate of the aromatic dihydroxy compound.

[0080] [Example 1] Polycarbonate was manufactured as follows using a polycarbonate manufacturing apparatus having the configuration shown in Figure 2. Mixing tank 1 of the stirring tank type (capacity 40 m³) 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 diphenyl carbonate at a ratio 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 30 m³). ３ The material was then transferred to the transesterification reactors 4 and 5 (with a volume of 20 m³) and the transesterification reaction was carried out. The transesterification reaction in transesterification reactor 2 was carried out at 200°C / 60 kPaA, and the transesterification reaction in transesterification reactor 3 was carried out at 220°C / 15 kPaA. Next, the material was transferred using a transfer pump to the stirred tank type pre-polycondensation reactors 4 and 5 (with a volume of 20 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 / 10kPaA, and the pre-polycondensation reaction in pre-polycondensation reactor 5 was carried out at 280°C / 5kPaA. Next, the material was transferred by a transfer pump to the guided contact flow type polycondensation reactor 6 and a polycondensation reaction was carried out. The polycondensation reaction in polycondensation reactor 6 was carried out 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, and the amount of DPC and BPA loss per hour was calculated every hour until the end of operation. (DPC loss: 730-870 kg / h, BPA loss: 25-30 kg / h) The additional hourly supply rates of DPC and BPA were changed each time the loss amount was calculated, and 730-870 kg / h of DPC and 25-30 kg / h of BPA were supplied from supply point b-o. Furthermore, from the start of the additional supply of DPC and BPA, the supply and discharge rates in each reactor were adjusted to minimize fluctuations in the amount of reactants held in each reactor, and the residence time in each reactor was continuously adjusted until the end of operation so that it was within ±20% of the residence time at the start of the additional supply of DPC and BPA. From 6 hours after the start of supply to 72 hours, the molecular weight (Mw) after the polycondensation reaction was measured every 4 hours, and the range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated. The evaluation results are shown in Table 1.

[0081] [Example 2] Polycarbonate was produced using the same procedure as in Example 1, except that the supply points for DPC and BPA were changed from b-o to a-m. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0082] [Example 3] Polycarbonate was produced using the same procedure as in Example 1, except that the supply points for DPC and BPA were changed from b-o to a-o. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0083] [Example 4] Polycarbonate was produced using the same procedure as in Example 1, except that the supply points of DPC and BPA were changed from b-o to b-m. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0084] [Example 5] Polycarbonate was produced using the same procedure as in Example 1, except that the supply points for DPC and BPA were changed from b-o to a-o and b-o, and the supply amounts at each supply point were as shown in Table 1. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0085] [Examples 6-8] Polycarbonate was produced using the same procedure as in Example 3, except that the pressure inside each reactor in the pre-polycondensation reaction was changed as shown in Table 1. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0086] [Example 9] Polycarbonate was produced using the same procedure as in Example 3, except that the mol ratio of DPC and BPA supplied to the mixing tank 1 was changed from 1.0 to 1.2. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0087] [Example 10] Polycarbonate was produced using the same procedure as in Example 8, except that the mol ratio of DPC and BPA supplied to the mixing tank 1 was changed from 1.0 to 1.2. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0088] [Example 11] Polycarbonate was produced using the same procedure as in Example 1, except that the frequency of calculating raw material loss up to the polycondensation step was changed as shown in Table 1. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0089] [Example 12] Polycarbonate was produced using the same procedure as in Example 1, except that the frequency of calculating raw material loss up to the polycondensation step was changed as shown in Table 1. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0090] [Comparative Example 1] In order to verify the effect of additional supply of DPC and BPA in Example 1, polycarbonate was manufactured using the same procedure as in Example 1, except that the additional supply of DPC and BPA from supply point b-o was set to 0 kg / h. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0091] [Comparative Example 2] In order to verify the effect of additional supply of DPC and BPA in Example 8, polycarbonate was manufactured using the same procedure as in Example 8, except that the additional supply of DPC and BPA from supply point a-o was set to 0 kg / h. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0092] [Comparative Example 3] In order to verify the effect of supplying an amount equivalent to the amount lost in Example 3, polycarbonate was produced using the same procedure as in Example 3, except that the amount of additional DPC and BPA supplied from supply point a-o was changed according to the amount of DPC and BPA purified and recovered from the condensate of each vent (the supply amounts are as shown in Table 1). The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0093] [Comparative Example 4] In order to confirm the effect of supplying an amount equivalent to the amount lost in Example 8, polycarbonate was produced using the same procedure as in Example 8, except that the amount of additional DPC and BPA supplied from supply point a-o was changed according to the amount of DPC and BPA purified and recovered from the condensate of each vent (the supply amounts are as shown in Table 1). The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 1.

[0094] As shown in Table 1, it was found that by stably supplying an amount of DPC and BPA equivalent to the amount of DPC and BPA lost from each vent during the reaction, the terminal OH% after the prepolymerization reaction was stabilized, and the range of variation and standard deviation of the molecular weight (Mw) after the polycondensation reaction were reduced.

[0095] [Example 13] Polycarbonate was manufactured as follows using a polycarbonate manufacturing apparatus having the configuration shown in Figure 2. A stirring tank type mixing tank 1 (contents 2 m³) 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 diphenyl carbonate at a ratio of 200 mass ppb 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). ３ The 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. After continuing the above operation for 12 hours, the composition of the condensate from each vent was analyzed and the amount of DPC and BPA loss per hour was calculated. From the obtained calculation results, the amount of additional DPC and BPA to be supplied per hour was determined, and 2 kg / h of DPC and 100 g / h of BPA were supplied from supply point a-o. From 6 hours after the start of supply to 72 hours later, the molecular weight (Mw) after the polycondensation reaction was measured every 4 hours, and the range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated. The evaluation results are shown in Table 2.

[0096] [Example 14] Polycarbonate was produced using the same procedure as in Example 13, except that the pressure inside each reactor in the pre-polycondensation reaction was changed as shown in Table 2. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 2.

[0097] [Comparative Example 5] In order to verify the effect of additional supply of DPC and BPA in Example 13, polycarbonate was produced using the same procedure as in Example 13, except that the additional supply of DPC and BPA from supply point a-o was set to 0 kg / h. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 2.

[0098] [Comparative Example 6] In order to verify the effect of additional supply of DPC and BPA in Example 14, polycarbonate was produced using the same procedure as in Example 14, except that the additional supply of DPC and BPA from supply point a-o was set to 0 kg / h. The range of variation and standard deviation of the molecular weight (Mw) analysis results were evaluated, and the results are shown in Table 2.

[0099] As shown in Table 2, even when a ring-disk type reactor was used as the reactor for the pre-polycondensation and polycondensation reactions, it was found that by stably supplying an amount of DPC and BPA equivalent to the amount of DPC and BPA lost from each vent during the reaction, the terminal OH% after the pre-polymerization reaction was stabilized, and the range of variation and standard deviation of the molecular weight (Mw) after the polycondensation reaction were reduced.

[0100]

[0101]

[0102]

[0103]

[0104] This application is based on Japanese Patent Application No. 2024-195872 filed on November 8, 2024, the contents of which are incorporated herein by reference.

[0105] 1... Mixing tank, 2, 3... Transesterification reactor, 4, 5... Pre-polycondensation reactor, 6... Polycondensation reactor, 10... Guided contact flow polymerization apparatus, 11... Liquid inlet, 12... Perforated plate, 13... Liquid supply zone, 14... Guide, 15... Evaporation zone, 16... Vacuum vent, 17... Liquid outlet, 18... Side casing, 19... Bottom casing

Claims

1. A method for producing aromatic polycarbonate, comprising the following steps a) to d): a) a transesterification reaction using one or more aromatic dihydroxy compounds and one or more diaryl carbonates in a transesterification reactor while removing the generated hydroxyaryl reaction products; b) a pre-polycondensation reaction of the reaction products of the transesterification reaction in at least one pre-polycondensation reactor while removing the generated hydroxyaryl reaction products; c) a polycondensation reaction of the reaction products of the pre-polycondensation reaction in at least one polycondensation reactor; and d) adding diaryl carbonates and / or aromatic dihydroxy compounds between steps a) to c); wherein the ratio of diaryl carbonates and aromatic dihydroxy compounds used in steps a), b), and / or c) is controlled, and the residence time in b) is controlled to control the terminal OH% of the reaction product introduced in c) to within ±2.0%.

2. The method for producing an aromatic polycarbonate according to claim 1, wherein, in a) 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 a) 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 b) is 40 to 110.

5. A method for producing an aromatic polycarbonate according to claim 1 or 2, wherein the amount of diaryl carbonate and aromatic dihydroxy compound encompassed to the hydroxyaryl reaction product is monitored in steps a) to c), and the amount of diaryl carbonate and / or aromatic dihydroxy compound to be added in step d) is determined based on that amount.

6. A method for producing an aromatic polycarbonate according to claim 1 or 2, wherein the transesterification reaction, the pre-polycondensation reaction, and the polycondensation reaction are carried out in a continuous manner.

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 method for producing an aromatic polycarbonate according to claim 1 or 2, wherein step a) is carried out in the presence of a catalyst, and 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 borate 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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