Method of producing polycarbonate

Abstract

To provide a method of producing polycarbonate which reduces raw material loss.SOLUTION: A method of producing polycarbonate includes: a preliminary polymerization process of subjecting a polymerization raw material including a dihydroxy compound, diaryl carbonate, and at least one catalyst selected from the group consisting of alkali metal and alkali earth metal compounds to ester exchange reaction under a reduced pressure condition in a polymerization reactor to obtain a molten prepolymer; and a condensation polymerization process of further subjecting the molten prepolymer to ester exchange reaction under a reduced pressure condition in the polymerization reactor to obtain polycarbonate, where the ester exchange reaction in the preliminary polymerization process is performed under a condition satisfying the following formula (1). (1) 1,100≤(-0.043×A+0.028×B+0.79)×C×D≤22,000.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] A representative method for producing polycarbonate is the transesterification method, in which a dihydroxy compound such as bisphenol A or isosorbide is transesterified with a diaryl carbonate such as diphenyl carbonate (DPC), and the polymerization is allowed to proceed by removing the by-product hydroxyaryl compound from the system (for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2005 / 121210 [Patent Document 2] JP 2011-202188 A [Patent Document 3] International Publication No. 2019 / 163964 Summary of the Invention [Problem to be solved by the invention]

[0004] As shown in Patent Document 1, in a polycarbonate production method in which a polymerization reaction is carried out while removing vapor of a by-produced hydroxyaryl compound from the system, droplets of the raw materials, a dihydroxy compound and a diaryl carbonate, are discharged along with the vapor, resulting in a loss of raw materials, and therefore there is room for improvement.

[0005] Therefore, an object of the present invention is to provide a method for producing polycarbonate that reduces raw material loss. [Means for solving the problem]

[0006] That is, the present invention includes the following embodiments. <1> A method for producing polycarbonate, comprising the steps of: a prepolymerization step of subjecting a polymerization raw material containing a dihydroxy compound, a diaryl carbonate, and at least one catalyst selected from the group consisting of alkali metals and alkaline earth metal compounds to an ester exchange reaction under reduced pressure in a polymerization vessel to obtain a molten prepolymer; a condensation polymerization step in which the molten prepolymer is subjected to a further transesterification reaction under reduced pressure in a polymerization vessel to obtain a polycarbonate; Including, The method for producing a polycarbonate, comprising carrying out the transesterification reaction in the prepolymerization step under conditions that satisfy the following formula (1): 1100 ≦ [―0.043×A+0.028×B+0.79]×C×D ≦ 22000 (1) (In formula (1), A is the acid dissociation constant (pKa) of the dihydroxy compound. However, when two or more dihydroxy compounds are used, A is the weighted average of the acid dissociation constants (pKa) of the dihydroxy compounds. B is the amount of dihydroxy compound and diaryl carbonate fed per hour (ton / hour), C is the catalyst concentration (mass ppb) relative to the diaryl carbonate calculated from the mass equivalent of the metal element in the catalyst, and D is the viscosity of the molten prepolymer after polymerization of the dihydroxy compound and diaryl carbonate for 1 hour (mPa s). <2> The A satisfies the following formula (2): <1> A method for producing the polycarbonate according to claim 1. 8 ≦ A ≦ 15 (2) <3> The B satisfies the following formula (3): <1> or <2> A method for producing the polycarbonate according to claim 1. 0.01 ≦ B ≦ 35 (3) <4> The C satisfies the following formula (4): <1> ~ <3> 2. A method for producing a polycarbonate according to claim 1 . 50 ≦ C ≦ 600 (4) <5> The D satisfies the following formula (5): <1> ~ <4> 2. A method for producing a polycarbonate according to claim 1 . 10 ≦ D ≦ 200 (5) <6> The polymerization vessel in the prepolymerization step is a stirred polymerization vessel. <1> ~ <5> 2. A method for producing a polycarbonate according to claim 1 . <7> The condensation polymerization step is carried out using a guide contact flow-down type polymerization apparatus, The guide contact flow-down type polymerization apparatus satisfies the following <Condition (1)> to <Condition (9)>: <1> ~ <6> 2. A method for producing a polycarbonate according to claim 1 . <Condition (1)> The evaporation zone has a liquid receiving port, a liquid supply zone for supplying liquid to a guide in the evaporation zone through a perforated plate, an evaporation zone in which a plurality of guides extending downward from the perforated plate are provided in a space surrounded by the perforated plate, a side casing and a bottom casing, a vacuum vent port provided in the evaporation zone, and a liquid discharge port provided at the bottom of the bottom casing. <Condition (2)> In the liquid supply zone, a flow path control component having a function of causing the liquid supplied from the liquid receiving port to flow from the periphery of the perforated plate in a direction toward the center of the perforated plate is disposed in the liquid supply zone. <Condition (3)> The internal cross-sectional area a (m 2 ) satisfies the following formula (I). 0.7 ≦ a ≦ 300 Formula (I) <Condition (4)> The internal cross-sectional area a (m 2 ) and the internal cross-sectional area b (m 2 ) satisfies the following formula (II). 20≦a / b≦1000 Formula (II) <Condition (5)> The bottom casing constituting the bottom of the evaporation zone is connected to the upper side casing at an angle c degrees inside thereof, and the angle c degrees satisfies the following formula (III). 110 ≦ c ≦ 165 Formula (III) <Condition (6)> The length h (cm) of the guide satisfies formula (IV). 150 ≦ h ≦ 5000 Formula (IV) <Condition (7)> The total external surface area S (m 2 ) satisfies formula (V). 2 ≦ S ≦ 50000 Formula (V) <Condition (8)> The perforated plate 1m 2 Average number of holes per m 2 ) satisfies formula (VI). 50 ≦ N ≦ 3000 Formula (VI) <Condition (9)> The upper area T (m 2 ) and the total effective cross-sectional area of ​​the holes Q(m 2 ) satisfies the following formula (VII). 50 ≦ T / Q ≦ 3000 Formula (VII) Effect of the Invention

[0007] According to the present invention, a method for producing polycarbonate that reduces raw material loss can be provided. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 shows a schematic diagram of an example of an inert gas absorption device constituting a polycarbonate production apparatus. [Diagram 2] FIG. 1 is a schematic diagram of an example of a guide contact flow-down type polymerization apparatus constituting a polycarbonate production apparatus. [Diagram 3] FIG. 2 shows a schematic configuration diagram of the upper part of an example of an inert gas absorption apparatus and a guide contact flow-down type polymerization apparatus. [Figure 4] FIG. 2 is an enlarged schematic diagram of an upper portion of an example of an inert gas absorption device and a guide contact flow-down type polymerization device. [Diagram 5] FIG. 1 shows a schematic configuration diagram of an example of a polycarbonate production apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention (hereinafter, also referred to as "the present embodiment") will be described in detail. Note that the present invention is not limited to the present embodiment, and various modifications can be made within the scope of the gist of the present invention.

[0010] [Production method of polycarbonate] The method for producing polycarbonate according to this embodiment includes the steps of: a prepolymerization step of subjecting a polymerization raw material containing a dihydroxy compound, a diaryl carbonate, and at least one catalyst selected from the group consisting of alkali metals and alkaline earth metal compounds to an ester exchange reaction under reduced pressure in a polymerization vessel to obtain a molten prepolymer; a condensation polymerization step in which the molten prepolymer is subjected to a further transesterification reaction under reduced pressure in a polymerization vessel to obtain a polycarbonate; Including, The transesterification reaction in the prepolymerization step is carried out under conditions that satisfy the following formula (1). 1100 ≦ [―0.043×A+0.028×B+0.79]×C×D ≦ 22000 (1) (In formula (1), A is the acid dissociation constant (pKa) of the dihydroxy compound. However, when two or more dihydroxy compounds are used, A is the weighted average of the acid dissociation constants (pKa) of the dihydroxy compounds. B is the amount of dihydroxy compound and diaryl carbonate fed per hour (ton / hour), C is the catalyst concentration (mass ppb) relative to the diaryl carbonate calculated from the mass equivalent of the metal element in the catalyst, and D is the viscosity of the molten prepolymer after polymerization of the dihydroxy compound and diaryl carbonate for 1 hour (mPa s). As described above, according to this embodiment, a method for producing polycarbonate that reduces raw material loss can be provided.

[0011] An example of a specific configuration of a polycarbonate production apparatus used in the polycarbonate production method of the present embodiment will be described below with reference to the drawings.

[0012] FIG. 5 shows a schematic configuration diagram of an example of a polycarbonate production apparatus used in this embodiment. In this polycarbonate production apparatus, the polymerization raw materials and catalyst are charged into a mixing tank 31 and mixed, then transferred by a transfer pump 32 to dissolved mixture storage tanks 33A and 33B, and from there further by transfer pumps 34A and 34B to a first polymerization vessel 35 where a prepolymerization step is carried out. Further, a prepolymerization step is carried out in a second polymerization vessel 37 via a feed pump 36 to obtain a polycarbonate prepolymer.

[0013] The polycarbonate prepolymer is transferred to a first inert gas absorption apparatus 39 via a supply pump 38, and the solubility of the inert gas is adjusted by a pressure control valve 41 before being transferred to a first guide contact flow-down type polymerization apparatus 42 for polymerization. Here, phenol is discharged from a vent as a low molecular weight component, which is a low boiling point substance.

[0014] Next, the inert gas is transferred to the second inert gas absorption apparatus 44 via the feed pump 43, and further transferred from there by the feed pumps 46A and 46B. The solubility of the inert gas is adjusted by the pressure regulating valves 47A and 47B, and the inert gas is transferred to the connected second guide contact flow-down type polymerization apparatuses 48A and 48B, where the condensation polymerization step is carried out. Here, phenol is discharged from the vent. The mixture is then transported by supply pumps 49A and 49B, and additives are added in downstream equipment 50A and 50B to obtain the desired polycarbonate. The pressure regulating valves 41, 47A, 47B that adjust the solubility of the inert gas are not limited in shape, and may be valves installed in a specified pipe or other devices capable of controlling a specified pressure.

[0015] <Preliminary Polymerization Step> In the prepolymerization step, polymerization raw materials containing a dihydroxy compound, a diaryl carbonate, and at least one catalyst selected from the group consisting of alkali metals and alkaline earth metal compounds are subjected to an ester exchange reaction in a polymerization vessel under reduced pressure conditions to obtain a molten prepolymer. The polymerization vessel in the prepolymerization step is preferably a stirred polymerization vessel.

[0016] In the method for producing a polycarbonate according to this embodiment, the transesterification reaction in the preliminary polymerization step is carried out under conditions that satisfy the following formula (1). By satisfying the conditions of formula (1), it is possible to reduce loss of raw materials. 1100 ≦ [―0.043×A+0.028×B+0.79]×C×D ≦ 22000 (1)

[0017] For example, as shown in the examples of the present specification, when the prepolymerization step is carried out twice, the first prepolymerization step satisfies formula (1), thereby providing a polycarbonate production method that reduces raw material loss as shown in the present embodiment.

[0018] In formula (1), A is the acid dissociation constant (pKa) of the dihydroxy compound. However, when two or more dihydroxy compounds are used, A is the weighted average of the acid dissociation constants (pKa) of the dihydroxy compounds. The acid dissociation constant (pKa) is the first dissociation constant, and a literature value may be used. The acid dissociation constant (pKa) may be measured by any commonly used method, for example, neutralization titration, electrical conductivity, or absorptiometry. It is preferable that A satisfies the following formula (2). 8 ≦ A ≦ 15 (2)

[0019] B is the amount of dihydroxy compound and diaryl carbonate fed per hour (ton / hour). It is preferable that B satisfies the following formula (3). 0.01 ≦ B ≦ 35 (3)

[0020] C is the catalyst concentration (mass ppb) relative to the diaryl carbonate calculated from the value converted into the mass of the metal element in the catalyst. More specifically, it can be calculated from the following formula. Catalyst concentration (mass ppb) = [mass of metal element in catalyst] / [mass of diaryl carbonate] It is preferable that C satisfies the following formula (4). 50 ≦ C ≦ 600 (4)

[0021] D is the viscosity (mPa s) of the molten prepolymer after one hour of polymerization of the dihydroxy compound and diaryl carbonate. "Molten prepolymer after one hour of polymerization" refers to the viscosity of the molten prepolymer after one hour of polymerization of the polymerization raw materials in the preliminary polymerization step. In other words, D depends on the ease of condensation polymerization of the dihydroxy compound and diaryl carbonate, the amount of catalyst, the amount of hydroxyaryl compound generated during preliminary polymerization, the reaction pressure, the stirring blade rotation speed, the temperature, etc. D can be controlled by adjusting these conditions. The viscosity of the molten prepolymer is measured by a rotational viscometer, and the temperature in the prepolymerization step is used for the viscosity measurement.

[0022] It is preferable that D satisfies the following formula (5). 10 ≦ D ≦ 200 (5)

[0023] The reaction pressure in the prepolymerization step is preferably 0.1 kPaA to 20 kPaA, more preferably 1.0 kPaA to 17.5 kPaA, and further preferably 2.0 kPaA to 15.0 kPaA.

[0024] The reaction temperature in the prepolymerization step is preferably from 100°C to 290°C, more preferably from 150°C to 280°C, and further preferably from 200°C to 270°C.

[0025] The rotation speed of the stirring blade in the preliminary polymerization step is preferably 40 rpm to 80 rpm, more preferably 45 rpm to 75 rpm, and further preferably 50 rpm to 70 rpm.

[0026] [Raw materials used in the production method of polycarbonate] In the method for continuously producing polycarbonate of the present embodiment, a dihydroxy compound and a diaryl carbonate compound, or a prepolymer thereof, is used as a raw material. The dihydroxy compound and diaryl carbonate compound, which are the raw materials used in the method for continuously producing a polycarbonate according to the present embodiment, will be described below.

[0027] (Dihydroxy Compounds) In the continuous production method for polycarbonate of the present embodiment, it is preferable that the polycarbonate contains one or more dihydroxy compounds having an acid dissociation constant (pKa) of 8 to 15 selected from the group consisting of aromatic dihydroxy compounds, alicyclic dihydroxy compounds, heteroalicyclic dihydroxy compounds, and aliphatic dihydroxy compounds.

[0028] The aromatic dihydroxy compound is preferably at least one selected from a bisphenol compound, a compound represented by the following formula (A), and a compound represented by the following formula (B). The bisphenol compound is not particularly limited, but examples thereof include 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- It is preferably one or more selected from 1,1-bis(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), and bisphenol-A is more preferable.

[0029] [ka] (In the formula, R1 to R5 represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.) An example of the compound represented by formula (A) is curcumin.

[0030] [ka] (In the formula, R 11 ~R 12 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. An example of the compound represented by formula (B) is furan-2,5-bismethanol.

[0031] The alicyclic dihydroxy compound is preferably one or more selected from the group consisting of a compound represented by the following formula (C), 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol. A compound having cis and trans isomers, such as 1,4-cyclohexanedimethanol, may be a mixture of cis and trans isomers, and the mixing ratio (mass ratio) is not particularly limited, but may be one having an easily available mixing ratio. [ka] (In the formula, R 13 ~R 16 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. An example of the compound represented by formula (C) is 2,2,4,4-tetramethyl-1,3-cyclobutanediol.

[0032] The heteroalicyclic dihydroxy compound is preferably at least one selected from a compound represented by the following formula (D), a compound represented by the following formula (E), and a compound represented by the following formula (F).

[0033] [ka] (In the formula, R7 and R8 represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.) An example of the compound represented by formula (D) is 1,4-dioxane-2,5-diol.

[0034] [ka] (In the formula, R9~R 10 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. An example of the compound represented by formula (E) is 1,4-anhydroerythritol.

[0035] [ka] (In the formula, R1 to R4 represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.) An example of the compound represented by formula (F) is isosorbide.

[0036] The aliphatic dihydroxy compound is preferably one or more compounds selected from the compounds represented by the following formula (G). [ka] (In the formula, R5 represents an alkylene group having 2 to 12 carbon atoms.) The compound represented by formula (G) is particularly preferably at least one selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0037] The dihydroxy compound used in the present embodiment may be one type alone or two or more types. A polyol compound having three or more valences may be used in combination to introduce a branched structure.

[0038] (Diaryl carbonate compounds) The diaryl carbonate compound used in this embodiment is preferably a diaryl carbonate compound represented by the following formula (H). [ka] (In the formula, Ar 3 , Ar 4 each independently represents a monovalent aromatic group having 5 to 20 carbon atoms. Ar 3 and Ar 4 is preferably a monovalent carbocyclic or heterocyclic aromatic group. 3 , Ar 4In the above, one or more hydrogen atoms may be substituted with 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. 3 , Ar 4 may be the same or different. 3 and Ar 4 Representative examples of Ar include, but are not limited to, 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. 3 and Ar 4 Although there is no particular limitation, examples thereof include those represented by the following formulas. [ka] Representative examples of diaryl carbonate compounds include, but are not limited to, substituted or unsubstituted diphenyl carbonates represented by the following formula (H-1). [ka] (In the formula, R 9 and R 10 each independently represents 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 carbon atoms, or a phenyl group; p and q each independently represent an integer of 1 to 5; when p is 2 or more, each R 9 may be different from each other, and when q is 2 or more, each R 10 may be different from each other.

[0039] Among these diaryl carbonate compounds, symmetrical diaryl carbonates such as unsubstituted diphenyl carbonate, ditolyl carbonate, and lower alkyl-substituted diphenyl carbonate such as di-t-butylphenyl carbonate are preferred. Diphenyl carbonate, which is the diaryl carbonate with the simplest structure, is particularly preferred. These diaryl carbonate compounds may be used alone or in combination of two or more.

[0040] The diaryl carbonate compound preferably includes a diaryl carbonate compound obtained by using carbon dioxide as a raw material.

[0041] A particularly preferred diaryl carbonate compound used as a raw material in the production method of this embodiment is diphenyl carbonate which is produced and purified by reacting ethylene carbonate, which has been produced and purified by reacting ethylene oxide with CO2, with methanol to produce and purify dimethyl carbonate and purified phenol, and which is produced and purified by a reactive distillation method. This is an ultra-high purity product which does not contain alkali metals / alkaline earth metals or chlorine. The manufacturing methods for these are not particularly limited, but may be described, for example, in WO 2004 / 105696, WO 2007 / 34669, WO 2007 / 60893, WO 2007 / 60984, WO 2007 / 69462, WO 2007 / 69513, WO 2007 / 69514, WO 2007 / 72728, WO 2005 / 123638, WO 2007 / 74692, WO 200 Reference can be made to International Publication No. 7 / 88782, International Publication No. 2006 / 1256, International Publication No. 2006 / 1257, International Publication No. 2006 / 6566, International Publication No. 2006 / 6568, International Publication No. 2006 / 6585, International Publication No. 2006 / 6588, International Publication No. 2006 / 41075, International Publication No. 2006 / 43491, International Publication No. 2007 / 69529, International Publication No. 2007 / 69531, International Publication No. 2007 / 72705, and the like. Furthermore, as the diaryl carbonate compound used as the raw material in the production method of this embodiment, diphenyl carbonate produced and purified by reacting dialkyl carbonate produced and purified by reacting alcohol with CO2 with purified phenol is also suitable. The production methods for these are not particularly limited, but reference can be made to, for example, WO 2005 / 783, WO 2007 / 114130, WO 2003 / 55840, WO 2011 / 105442, WO 2006 / 67982, etc.

[0042] (molten prepolymer) The raw material molten prepolymer used in the polycarbonate production method of this embodiment is produced from a dihydroxy compound and a diaryl carbonate. The ratio of use (feed ratio) varies depending on the types of dihydroxy compound and diaryl carbonate compound used, the polymerization temperature and other polymerization conditions, but the diaryl carbonate compound 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 mole of the dihydroxy compound.

[0043] The molten prepolymer (molten prepolymer) produced from the dihydroxy compound and the diaryl carbonate compound means a molten product in the middle of polymerization, produced from the dihydroxy compound and the diaryl carbonate compound, having a lower degree of polymerization than the polycarbonate having the desired degree of polymerization, and may of course be an oligomer.

[0044] The average degree of polymerization of the molten prepolymer of polycarbonate that can be produced by the polycarbonate production method of this embodiment may be any value, and varies depending on the chemical structure, but is usually about 2 to 2,000. Such a molten prepolymer used as a polymerization raw material may be obtained by any known method.

[0045] In this embodiment, the molar ratio of the total amount of dihydroxy compounds to the diaryl carbonate compounds, i.e., the molar ratio of the dihydroxy compounds is determined by the number average molecular weight Mn and OH% of the target polycarbonate, the total amount of dihydroxy compounds and the type of diaryl carbonate, the polymerization temperature, and other polymerization conditions. From the viewpoint of realizing a better polymerization reaction and more effectively preventing coloration and a decrease in heat resistance, the ratio of the dihydroxy compounds to the total amount of dihydroxy compounds is preferably 0.90 to 1.15, more preferably 0.92 to 1.13, and even more preferably 0.94 to 1.10, on a molar basis.

[0046] (catalyst) The method for producing a polycarbonate in this embodiment is carried out in the presence of at least one catalyst selected from the group consisting of alkali metal and alkaline earth metal compounds. The catalyst used in the present embodiment is not particularly limited, but examples thereof include hydroxides of alkali metals or alkaline earth metals such as lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, etc.; alkali metal salts, alkaline earth metal salts, and quaternary ammonium salts of boron or aluminum hydrides such as lithium aluminum hydride, sodium borohydride, and tetramethylammonium borohydride; hydrogen compounds of alkali metals or alkaline earth metals such as lithium hydride, sodium hydride, and calcium hydride; alkoxides of alkali metals or alkaline earth metals such as lithium methoxide, sodium ethoxide, and calcium methoxide; aryloxides of alkali metals or alkaline earth metals such as lithium phenoxide, sodium phenoxide, magnesium phenoxide, LiO-Ar-OLi, and NaO-Ar-ONa (Ar is an aryl group); and organic acid salts of alkali metals or alkaline earth metals such as lithium acetate, calcium acetate, and sodium benzoate. Only one type of catalyst may be used alone, or two or more types may be used in combination. Among these, alkali metal or alkaline earth metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, etc. are preferred.

[0047] In addition, the amount of the catalyst used is preferably 30 to 1,000 ppb by mass, more preferably 40 to 800 ppb by mass, and even more preferably 50 to 600 ppb by mass, relative to the raw material diaryl carbonate compound, from the viewpoints of achieving a practically satisfactory polymerization reaction and preventing coloration and a decrease in heat resistance.

[0048] The ratio of hydroxyl groups to aryl carbonate groups is not particularly limited, but is preferably in the range of 95:5 to 5:95, more preferably in the range of 90:10 to 10:90, and further 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.

[0049] <Condensation polymerization process> In the condensation polymerization step, the molten prepolymer is further subjected to a transesterification reaction under reduced pressure conditions in a polymerization vessel to obtain a polycarbonate. The polymerization vessel used when using the molten prepolymer as a raw material and further polymerizing the raw material may be any generally used one, and is not particularly limited. Examples of such reactors include stirred tank reactors, thin film reactors, centrifugal thin film evaporation reactors, surface renewal type twin-screw kneading reactors, twin-screw horizontal stirring reactors, wetted-wall reactors, perforated plate reactors in which polymerization is performed while the material is allowed to fall freely, and wire-attached perforated plate reactors in which polymerization is performed while the material is allowed to fall along a wire. It is preferable to use a guide contact flow-down type polymerization apparatus in which the raw materials are polymerized while being allowed to fall freely along a guide. By allowing the raw materials described above to flow down along the outer surface of a guide and continuously producing polycarbonate by a melt polycondensation method, the polycarbonate obtained has effects such as a low melt flow rate, suppressed haze, and excellent color. The term "guide" used in the present embodiment refers to an article along which the molten material moves. The guide is not particularly limited, but examples thereof include a pipe and a rod.

[0050] In the polycarbonate production method of this embodiment, an inert gas absorbing device may be installed to absorb inert gas into the molten prepolymer of polycarbonate before it is supplied to the guided contact flow-down type polymerization apparatus. In addition, in this embodiment, when a plurality of guided contact flow-down type polymerization apparatuses are connected and used, an inert gas absorbing device may be installed for each polymerization apparatus to absorb inert gas into the molten prepolymer of polycarbonate before it is supplied to the polymerization apparatus. The inert gas absorbing equipment is not particularly limited, but examples thereof include a vertical tubular tank (e.g., a vertical cylindrical tank) with wires and / or wire mesh provided therein and a stirring tank.

[0051] With regard to the manufacturing methods thereof, reference can be made to, but is not particularly limited to, for example, International Publication No. WO 1997 / 22650, International Publication No. WO 1999 / 36457, International Publication No. WO 2005 / 121211, International Publication No. WO 2005 / 123805, International Publication No. WO 2006 / 64656, International Publication No. WO 2006 / 64664, International Publication No. WO 2006 / 64667, International Publication No. WO 2006 / 67993, and International Publication No. WO 2006 / 67994.

[0052] In the guide contact flow-down type polymerization apparatus used in this embodiment, the raw material is caused to flow down along the outer surface of the guide, for example, while the raw material prepolymer flows down by its own weight, efficient surface renewal is performed with natural stirring inside the prepolymer, so that the polymerization reaction can proceed at a relatively low temperature. Therefore, the preferable reaction temperature is 100 to 280°C, and more preferably 150 to 270°C. In this way, the production method of this embodiment is a production method in which the raw material is caused to flow down along the outer surface of the guide, so that polymerization can be sufficiently carried out at a lower temperature than in the case of a conventional mechanically stirred polymerization apparatus, and high-quality polycarbonate can be produced without coloration or deterioration of physical properties.

[0053] The materials of the guide contact flow-down type polymerization apparatus and piping used in this embodiment are not particularly limited, and can be selected from, for example, metals such as stainless steel, carbon steel, Hastelloy, nickel, titanium, chromium, and other alloys, and polymer materials with high heat resistance. The surfaces of these materials may be subjected to various treatments as necessary, such as plating, lining, passivation treatment, acid washing, and phenol washing. Stainless steel, nickel, glass lining, and the like are preferable, and stainless steel is particularly preferable. In addition, it is preferable to use gear pumps that can quantitatively discharge high-viscosity substances as the discharge pump for the molten prepolymer or polycarbonate, and the material of these gears may be stainless steel or other special metals.

[0054] In the condensation polymerization step, the evaporation of the low boiling point substance is preferably carried out using a guide contact flow-down type polymerization apparatus. In addition, the guide contact flow-down type polymerization apparatus preferably satisfies <Condition (1)> to <Condition (9)> described later.

[0055] FIG. 1 shows a schematic configuration diagram of an example of the first inert gas absorbing device 39 and the second inert gas absorbing device 44, and FIG. 2 shows a schematic configuration diagram of an example of the guide contact flow-down type polymerization devices 42, 48A, 48B. The inert gas absorption apparatus shown in FIG. 1 and the guide contact flow-down type apparatus shown in FIG. 2 differ in that they each have an inert gas absorption zone in which the inert gas is absorbed and an evaporation zone in which low boiling point substances are evaporated in their internal spaces, but they have the same basic apparatus structure. 3 and 4 are schematic diagrams showing the upper part of an example of an inert gas absorption apparatus and a guide contact type falling polymerization apparatus.

[0056] In the polycarbonate production apparatus used in this embodiment, the guide contact flow-down type polymerization apparatus preferably satisfies the following <Condition (1)> to <Condition (9)>. In the polycarbonate production method according to this embodiment, the molten prepolymer obtained in the above-mentioned preliminary polymerization step is supplied as the following liquid.

[0057] <Condition (1)> The evaporation zone 5 has a liquid receiving port 1, a liquid supply zone 3 for supplying liquid to a guide 4 of an evaporation zone 5 through a perforated plate 2, an evaporation zone 5 in which a plurality of guides 4 extending downward from the perforated plate 2 are provided in a space surrounded by the perforated plate 2, a side casing 10 and a bottom casing 11, a vacuum vent port 6 provided in the evaporation zone 5, and a liquid discharge port 7 provided at the bottom of the bottom casing.

[0058] <Condition (2)> In the liquid supply zone 3, a flow path control component 20 having the function of flowing the liquid supplied from the liquid receiving port 1 to the porous plate 2 from the periphery toward the center of the porous plate 2 is installed in the liquid supply zone 3.

[0059] <Condition (3)> The internal cross-sectional area A (m 2 ) satisfies the following formula (I). 0.7 ≦ A ≦ 300 Formula (I)

[0060] <Condition (4)> The internal cross-sectional area A (m 2 ) and the internal cross-sectional area B (m 2 ) satisfies formula (II). 20 ≦ A / B ≦ 1000 Formula (II) By satisfying the above formula (II), it tends to be possible to discharge the evaporated and concentrated liquid or polymer, or the melt having an increased melt viscosity, without deteriorating the quality of the produced polymer.

[0061] <Condition (5)> The bottom casing 11 constituting the bottom of the evaporation zone 5 is connected to the upper side casing 10 at an angle C degrees inside thereof, and it is preferable that the angle C degrees satisfies the formula (III). 110 ≦ C ≦ 165 Formula (III) In order to reduce equipment costs, it is preferable that C is as close to 90 degrees as possible. However, in order to move the concentrated liquid and polymer dropping from the lower end of the guide 4, which have increased melt viscosity, to the liquid discharge port 7 without deteriorating the quality of these melts, it is preferable that C satisfies formula (III).

[0062] <Condition (6)> The length h (cm) of the guide 4 satisfies the formula (IV). 150 ≦ h ≦ 5000 Formula (IV) By making the length h of the guide 4 150 cm or more, concentration and polymerization can be carried out at a speed and quality sufficient for practical use. By making h 5000 cm or less, the difference in viscosity of the liquid between the upper and lower parts of the guide 4 does not become too large, which tends to prevent variations in the concentration degree and the polymerization degree.

[0063] <Condition (7)> The total external surface area S (m 2 ) satisfies the following formula (V). 2 ≦ S ≦ 50000 Formula (V) S(m 2 ) of 2 or more tends to enable the amount of evaporated liquid or manufactured polymer production of 1 ton or more per hour to be achieved. Also, S(m 2 ) is 50,000 or less, this production volume can be achieved while reducing equipment costs, and there is a tendency to eliminate variation in physical properties.

[0064] <Condition (8)> The perforated plate 1m 2 Average number of holes per m 2 ) satisfies formula (VI). 50 ≦ N ≦ 3000 Formula (VI) Average number of holes in the perforated plate N (pcs / m 2 ) is the total number of holes multiplied by the area of ​​the upper surface of the perforated plate 2 (including the area above the holes) T(m 2 ) is the number divided by The holes in the perforated plate 2 are preferably arranged almost uniformly on the perforated plate 2, but since the distance K (cm) between the periphery of the perforated plate 2 and the inner wall surface of the evaporation zone 5 is preferably longer than the distance between adjacent holes, the number of holes per unit area in the periphery is preferably smaller than that in the center. In this embodiment, the average number of holes N is used in this sense. A more preferable range for N is 70≦N≦2000, and an even more preferable range is 100≦N≦1000.

[0065] <Condition (9)> The upper area T (m 2 ) and the total effective cross-sectional area of ​​the holes Q(m 2 ) satisfies the following formula (VII). 50 ≦ T / Q ≦ 3000 Formula (VII) The T / Q ratio is more preferably from 100 to 2,500, and further preferably from 250 to 1,500. The "effective cross-sectional area" of the hole in the perforated plate refers to the area of ​​the narrowest part of the cross section of the hole through which the liquid passes. When the guide 4 penetrates the hole, it is the area obtained by subtracting the cross-sectional area of ​​the guide 4 from the cross-sectional area of ​​the hole. Q(m 2 ) represents the sum of the effective cross-sectional areas of those holes.

[0066] When the above formulae (VI) and (VII) are satisfied, there is a tendency that the evaporation treatment of a large amount of liquid, particularly a highly viscous liquid, can be carried out continuously and stably for a long period of time.

[0067] By using a polycarbonate production apparatus satisfying the above-mentioned configuration, not only the problems of the conventionally known evaporation apparatuses are solved, but also concentrated liquids and polymers that are free of coloration and have high quality and high performance tend to be obtained. In addition, by using the above-mentioned production apparatus, the evaporated liquid tends to be stably produced at a rate of 1 ton or more per hour for a long period of time of several thousand hours or more, for example, 5,000 hours or more.

[0068] The reason why a polycarbonate production apparatus satisfying the above-mentioned configuration has such excellent effects is presumably due to the composite effects that are brought about when those conditions are combined, in addition to the various reasons mentioned above. For example, a guide with a high surface area that satisfies the above formulas (IV) and (V) is very effective for efficient internal mixing and surface renewal of large amounts of liquid, prepolymer, or polymer supplied at a relatively low temperature, and can efficiently evaporate low-boiling point substances, helping to obtain large amounts of high-quality concentrated liquid or polymer, such as more than 1 ton per hour. It is also presumed that the angle C that satisfies the above formula (III) is because it can shorten the time until the large amount of high-quality concentrated liquid or polymer falling from the guide 4 is discharged from the liquid discharge port 7, thereby reducing the thermal history.

[0069] The performance of an industrial-scale guided contact flow-down type polymerization apparatus can only be established through long-term operation using large-scale production equipment, and the cost of the production equipment in such a case is an important factor to be considered. The guide contact flow-down type polymerization apparatus constituting the above-mentioned polycarbonate production apparatus can reduce the equipment cost relative to performance, as compared with conventional evaporators and polymerization reactors.

[0070] The specific conditions and suitable ranges of dimensions, angles, etc. in the above-mentioned guide contact flow-down type polymerization apparatus are as described above, but more preferable ranges are as follows. The internal cross-sectional area A (m 2 A more preferred range for A is 0.8≦A≦250, and even more preferred is 1≦A≦200.

[0071] In addition, the internal cross-sectional area A (m 2 ) and the internal cross-sectional area B (m 2 ) is more preferably in the range of 25≦A / B≦900, and even more preferably in the range of 30≦A / B≦800.

[0072] A more preferable range of the angle C degrees that the bottom casing 11 constituting the bottom of the evaporation zone 5 makes with the upper side casing 10 inside thereof, as shown in formula (III), is 120≦C≦165, and even more preferably 135≦C≦165. When the concentration degree or polymerization degree is increased sequentially using a plurality of guide contact flow-down type polymerization apparatuses, it is preferable that C1≦C2≦C3≦..., where the corresponding angles are C1, C2, C3,...

[0073] The required length h (cm) of the guide 4 shown in formula (IV) varies depending on factors such as the amount, viscosity, and temperature of the liquid to be treated, the amount and boiling point of the low-boiling point substance, the pressure and temperature of the evaporation zone, and the required concentration or degree of polymerization, but a more preferable range is 200≦h≦3000, and even more preferably 400<h≦2500.

[0074] In addition, the total external surface area S (m 2 ) also varies depending on the same factors as above, but a more preferable range is 10≦S≦40,000, and even more preferably 15≦S≦30,000.

[0075] In this specification, the total external surface area of ​​the entire guide means the entire surface area of ​​the guide that contacts and allows liquid to flow down; for example, in the case of a guide such as a pipe, it means the outer surface area and does not include the surface area of ​​the inner surface of the pipe that does not allow liquid to flow down.

[0076] As shown in FIGS. 1 to 3, liquid receiving port 1 is preferably provided above liquid supply zone 3. As shown in FIG. The liquid receiving port 1 may be located in one or more locations, but it is preferable to arrange it so that the liquid is supplied to the perforated plate 2 as uniformly as possible in the liquid supply zone 3, and if there is one location, it is preferably located in the center of the upper part of the liquid supply zone 3. In the liquid supply zone 3, a flow path control component 20 having a function of directing the flow of liquid supplied from the liquid receiving port 1 to the perforated plate 2 mainly from the periphery to the center of the perforated plate 2 is preferably installed in the liquid supply zone 3. The flow path control component 20 has the effect of preventing the liquid from staying for a long period of time in the space between the holes (e.g., 21) of the perforated plate 2 and the inner side wall surface 22 of the liquid supply zone by directing the flow of the liquid from the periphery to the center of the perforated plate 2. The liquid mainly flowing from the periphery to the center of the perforated plate 2 is supplied to the guide 4 through the holes of the perforated plate that exist between them.

[0077] The shape of the flow path control component 20 may be any shape as long as it can exert its effect, but it is preferable that the outer shape of its cross section is similar to the outer shape of the cross section of the perforated plate 2. Here, the cross section of the flow path control component 20 refers to the place showing the maximum area when the flow path control component 20 is cut along a horizontal plane. The preferred range of the distance between the flow path control component 20 and the inner side wall surface 22 of the liquid supply zone 3 varies depending on the amount, viscosity, etc. of the liquid to be treated, but in the guide contact flow-down type polymerization apparatus and inert gas absorption apparatus that constitute the above-mentioned polycarbonate production apparatus, when the viscosity of the liquid to be handled is relatively high, the distance is usually preferably in the range of 1 cm to 50 cm, more preferably 2 cm to 30 cm, and even more preferably 3 cm to 20 cm.

[0078] 3 and 4, there is a predetermined gap between the upper inner wall surface 23 of the liquid supply zone 3 and the flow path control component 20, and this gap may be any size, but it is preferable to minimize the residence time of the liquid in the liquid supply zone 3. In this sense, this gap is preferably 1 cm to 200 cm, more preferably 2 cm to 170 cm, and even more preferably 3 cm to 150 cm. The distance between the upper inner wall surface 23 of the liquid supply zone 3 and the flow path control component 20 can be made to be approximately the same from the liquid receiving port 1 to the inner side wall surface 22 of the liquid supply zone 3, or the flow path control component 20 can be made so that the distance gradually narrows, or conversely, the distance gradually widens. Moreover, the distance between the flow path control component 20 and the porous plate 2 is usually 1 cm to 50 cm, preferably 2 cm to 30 cm, and more preferably 3 cm to 20 cm. The gap between the perforated plate 2 and the flow path control component 20 may be substantially the same from the inner side wall surface 22 of the liquid supply zone 3 to the center of the perforated plate, or the gap may be gradually narrowed, or conversely, gradually widened. Preferably, the flow path control component 20 has substantially the same gap or gradually narrows.

[0079] The flow path control component 20 functions as a kind of baffle plate, since it prevents the liquid supplied from the liquid inlet 1 from being led directly to the holes in the perforated plate 2. When the area of ​​the perforated plate 2 is large, it is also preferable to short-circuit a part of the supplied liquid to the vicinity of the center of the perforated plate 2 without passing through the peripheral parts of the perforated plate 2, and for this purpose, it is also a preferable embodiment to provide one or more holes near the center of the flow path control component 20 or in another appropriate part.

[0080] In order to prevent the formation of a "dead space" in the liquid supply zone 3, it is further preferable that the angle, i.e., E degrees, between the inner side wall surface 22 of the liquid supply zone and the perforated plate 2 satisfies the following formula (VIII): 100 ≦ E < 180 Formula (VIII) Here, when the inner side wall surface 22 of the liquid supply zone is flat, the angle E is formed between the inner side wall surface 22 and the perforated plate 2 in a cross section perpendicular to the flat surface and perpendicular to the upper surface of the perforated plate 2 . Furthermore, when the inner side wall surface 22 is a concave curved surface, the angle between the tangent line at the point where the curve formed in the cut surface along a plane perpendicular to the concave surface and perpendicular to the upper surface of the perforated plate 2 begins to rise and the upper surface of the perforated plate 2 is E. A more preferable range for E is 120≦E<180, and even more preferable is 145≦E<180. It is also preferable to devise a way to prevent the vicinity of the junction between the upper inner wall surface 23 and the inner side wall surface 22 of the liquid supply zone 3 from becoming a "dead space." It is preferable to make the angle between these two surfaces greater than 90°, or if it is 90° or close to it, to make the vicinity of the junction concave so that liquid does not stagnate.

[0081] In the above-mentioned polycarbonate production apparatus, it is preferable that the distance K (cm) between the guide 4 closest to the inner wall surface of the side casing 10 of the evaporation zone 5 and the inner wall surface satisfies the following formula (IX). 5 ≦ K ≦ 50 Formula (IX) When liquid adheres to the inner wall surface of the side casing 10 of the evaporation zone 5, evaporation and concentration occurs on the inner wall surface, and the concentrated liquid flows down the inner wall surface. However, since the outer wall surface of this inner wall is usually heated by steam or a heat medium through a jacket or the like to keep the evaporation zone 5 warm and / or to heat it, or is heated by an electric heater or the like, the liquid adhering to the inner wall surface is more highly concentrated and usually has a higher viscosity than the liquid flowing down the guide 4. Such a viscous liquid spends a longer time flowing down the wall surface (residence time), and becomes even more viscous. Moreover, since the outer wall surface is constantly heated, thermal denaturation is likely to occur. This tendency is particularly strong when handling highly viscous liquids such as prepolymers and polymers, such as when used as a polymerization vessel or a polymer purification and / or recovery device. In such cases, the polymers attached to the inner wall surface of the evaporation zone 5 are likely to become discolored, become high molecular weight, or gel, and the inclusion of such denatured substances is undesirable for the polymer product. Therefore, the longer the distance K (cm) between the guide 4 closest to the inner wall surface and the inner wall surface, the better, but in the case of an industrial device, the shorter the distance K (cm) is, in consideration of manufacturing costs and in order to obtain high evaporation capacity with as small a device as possible.

[0082] By using the above-mentioned polycarbonate production apparatus, it is possible to suppress the above-mentioned adverse effects on the product, and also to keep the K(cm) range (formula (IX)) as short as possible, so that high evaporation capacity can be obtained with a small apparatus. From this viewpoint, a more preferable range of K(cm) is 10≦K≦40, and an even more preferable range is 12≦K≦30.

[0083] In the above-mentioned polycarbonate production apparatus, the shape of the inner cross section in the horizontal plane of the side casing 10 of the evaporation zone 5 of the guide contact flow-down type polymerization apparatus may be any shape such as polygonal, elliptical, circular, etc. The evaporation zone 5 is usually operated under reduced pressure, and may have any shape that can withstand the pressure, but is preferably circular or nearly circular. Therefore, the side casing 10 of the evaporation zone 5 is preferably cylindrical. In this case, it is preferable that a cone-shaped bottom casing is installed under the cylindrical side casing 10, and a cylindrical liquid outlet 7 is provided at the lowest part of the bottom casing.

[0084] In the above-mentioned guide contact flow-down type polymerization apparatus for producing polycarbonate, when the side and bottom casings of the evaporation zone 5 are made of the above-mentioned cylindrical and cone parts, respectively, and the liquid outlet 7 for the concentrated liquid or polymer is cylindrical, it is preferable that, when the inner diameter of the cylindrical part of the side casing is D (cm), the length is L (cm), and the inner diameter of the liquid outlet 7 is d (cm), D, L, and d satisfy the following formulas (X), (XI), (XII), and (XIII). 100 ≦ D ≦ 1800 Formula (X) 5 ≦ D / d ≦ 50 Equation (XI) 0.5 ≦ L / D ≦ 30 Formula (XII) h-20 ≦ L ≦ h+300 Formula (XIII) Here, h is the length of the guide 4 shown in the above <Condition (6)>.

[0085] In the above-mentioned guide contact flow-down type polymerization apparatus, a more preferable range of D (cm) is 150≦D≦1500, and even more preferably 200≦D≦1200. A more preferable range for D / d is 6≦D / d≦45, and even more preferable range is 7≦D / d≦40. A more preferable range for L / D is 0.6≦L / D≦25, and even more preferable is 0.7≦L / D≦20. A more preferable range of L (cm) is h - 10 ≦ L ≦ h + 250, and even more preferable range is h ≦ L ≦ h + 200. Regarding D, d, and L, it is preferable that the balance between the amount of prepolymer that can be attached to the wire and the size of the polymerization vessel (D), and the balance between the size of the withdrawal port d at the bottom of the polymerization vessel, fall within the above-mentioned ranges. The number of wires (=polymerization vessel size (D)) is determined by the amount of prepolymer supplied, and in order to extract the fallen polymer (which has a higher viscosity than the supplied prepolymer due to the progress of polymerization), a pipe diameter (d) corresponding to the viscosity may be required. On the other hand, since the liquid or melt is continuously supplied to the guide from above, by satisfying the above-mentioned formula, the liquid with approximately the same viscosity or the melt with approximately the same melt viscosity and a higher degree of polymerization will continuously fall from the lower end of the guide to the bottom casing. In other words, the liquid with approximately the same viscosity and the polymer with approximately the same degree of polymerization produced while flowing down the guide will accumulate at the bottom of the bottom casing, and concentrated liquid with no variation in evaporation degree and polymer with no variation in molecular weight tend to be continuously produced. This is one of the other excellent features of the guide contact flow-down type polymerization apparatus constituting the above-mentioned polycarbonate production apparatus.

[0086] The concentrated liquid and polymer accumulated in the lower part of the bottom casing 11 are continuously discharged by a discharge pump 8 through a liquid discharge port 7, and in the case of a polymer, it is normally continuously pelletized through an extruder or the like. In this case, it is also possible to add additives and the like in the extruder.

[0087] In the above-mentioned polycarbonate production apparatus, the spatial volume V (m 2 ) in which liquid can exist in the liquid supply zone 3 is from the liquid supply port 1 (the joint between the liquid supply port 1 and the upper inner wall surface 23 of the liquid supply zone 3) to the upper surface of the perforated plate 2. 3 ) and the upper area T (m 2 ) preferably satisfies the following formula (XIV): 0.02(m) ≦ V / T ≦ 0.5(m) Formula (XIV) The spatial volume V (m 3 ) is the substantial volume of liquid in the liquid supply zone 3 during continuous operation of the guide contact flow-down type polymerization apparatus, excluding the volume of the flow path control component 20. The liquid retention amount in the liquid supply zone 3 is V(m 3 ), and the smaller this amount is, the shorter the residence time in the liquid supply zone 3 is and the less adverse effects there are caused by thermal denaturation. However, in order to obtain concentrated liquid and / or polymer with a predetermined concentration or polymerization degree stably over a long period of time at an evaporated liquid rate of 1 ton / hr or more, it is preferable to supply the liquid as evenly as possible to the holes in the perforated plate 2. For this purpose, it is preferable that the value of V / T is within the range of the above formula (XIV). A more preferable range of the value of V / T is 0.05(m)≦V / T ≦0.4(m), and even more preferably 0.1(m)≦V / T ≦0.3(m).

[0088] Furthermore, in the above-mentioned guide contact flow-down type polymerization apparatus for producing polycarbonate, the space volume V (m 3 ) and the spatial volume Y (m 3 ) preferably satisfies the following formula: 10≦Y / V≦500 In order to evaporate a large amount of liquid per unit time stably and efficiently for a long period of time without causing deterioration of physical properties due to thermal denaturation, it is preferable that the value of Y / V is within this range, and a more preferable range of the value of Y / V is 15≦Y / V≦400, and even more preferably 20≦Y / V≦300. The spatial volume Y (m 3 ) is the spatial volume from the lower surface of the perforated plate 2 to the liquid outlet 7, including the volume occupied by the guide.

[0089] In the guide contact flow-down type polymerization apparatus constituting the above-mentioned polycarbonate production apparatus, when one guide 4 is cylindrical with an outer diameter r (cm) or pipe-shaped so that liquid, gaseous substance, or molten prepolymer does not enter inside, it is preferable that the outer diameter r (cm) satisfies the following formula (XV). 0.1 ≦ r ≦ 1 Formula (XV)

[0090] The guide 4 allows the liquid or molten prepolymer to flow downward while evaporating and concentrating it or polymerizing it, but it also has the function of retaining the liquid or molten prepolymer for a certain period of time. This retention time is related to the evaporation time or polymerization reaction time, and since the liquid viscosity or melt viscosity increases as the evaporation or polymerization progresses, the retention time and amount tend to increase. The amount of liquid or molten prepolymer that the guide 4 retains varies depending on the external surface area of ​​the guide 4, i.e., its outer diameter in the case of a cylindrical or pipe-shaped guide, even if the melt viscosity is the same. In addition, the guide 4 installed in the guide contact flow-down type polymerization apparatus preferably has a strength sufficient to support the mass of the liquid, molten prepolymer, or polymer held therein, in addition to the mass of the guide 4 itself. In this sense, the thickness of the guide 4 is important, and in the case of a cylindrical or pipe-shaped guide, it is preferable that the thickness satisfies the above formula (XV).

[0091] When the outer diameter r (cm) of the guide 4 is 0.1 or more, stable operation for a long time tends to be possible in terms of strength. Also, by making r (cm) 1 or less, the guide itself can be prevented from becoming very heavy, and inconveniences such as the need to make the thickness of the perforated plate 2 very thick to hold them in the guide contact flow-down type polymerization apparatus can be avoided, and an increase in the number of areas holding too much liquid, molten prepolymer, or polymer can be prevented, and inconveniences such as large variations in concentration and molecular weight tend to be avoided. In this sense, a more preferable range of the outer diameter r (cm) of the guide 4 is 0.15≦r≦0.8, and further preferably, 0.2≦r≦0.6.

[0092] The positional relationship between the guide 4 and the perforated plate 2, and the positional relationship between the guide 4 and the holes in the perforated plate 2 are not particularly limited as long as the liquid, raw material molten prepolymer, or polymer can come into contact with the guide and flow downward. The guide 4 and the perforated plate 2 may or may not be in contact with each other. It is preferable, but not limited to, to install the guide 4 in correspondence with the holes in the perforated plate 2. The reason for this is that the guide 4 may be designed so that the liquid, raw material molten prepolymer, or polymer dropping from the perforated plate 2 contacts the guide 4 at an appropriate position.

[0093] Preferred modes for installing the guide 4 in correspondence with the hole in the perforated plate 2 include, for example, (1) a method in which the upper end of the guide is fixed to the lower surface of the flow path control component, etc., so that the guide is provided in a state in which the guide penetrates near the center of the hole in the perforated plate, (2) a method in which the upper end of the guide is fixed to the peripheral portion of the upper end of the hole in the perforated plate, so that the guide is provided in a state in which the guide penetrates the hole in the perforated plate, and (3) a method in which the upper end of the guide is fixed to the lower surface of the perforated plate, etc.

[0094] The method for causing the liquid, raw material molten prepolymer, or polymer to flow down along the guide 4 through the perforated plate 2 is not particularly limited, but examples thereof include a method for causing the liquid, raw material molten prepolymer, or polymer to flow down by a liquid head or its own weight, or a method for applying pressure using a pump or the like to extrude the liquid, raw material molten prepolymer, or polymer from the perforated plate 2. A preferred method is a method in which a predetermined amount of liquid, raw material molten prepolymer, or polymer is supplied under pressure using a supply pump to a liquid supply zone of the evaporator, and the liquid, raw material molten prepolymer, or polymer guided to the guide 4 through the perforated plate 2 flows down along the guide by its own weight.

[0095] In the above-mentioned polycarbonate manufacturing apparatus, the preferred material of such a guide is selected from metals such as stainless steel, carbon steel, Hastelloy, nickel, titanium, chromium, aluminum and other alloys, polymer materials having high heat resistance, etc. The most preferred material is stainless steel. Furthermore, the surface of the guide may be subjected to various treatments as required, such as plating, lining, passivation treatment, acid washing, washing with a solvent or phenol, or the like.

[0096] It is not clear why the above-mentioned polycarbonate manufacturing equipment can be used to stably produce high-quality, high-performance concentrated liquids and polymers with fast evaporation and polymerization rates, no coloring, good color tone, and excellent mechanical properties on an industrial scale for a long period of time (without variations in molecular weight, in the case of polymer production), but it is assumed as follows. That is, in the guide contact flow-down type polymerization apparatus constituting the above-mentioned polycarbonate production apparatus, the raw material liquid is introduced from the liquid receiving port 1 through the liquid supply zone 3 and the perforated plate 2 to the guide 4, and is concentrated or the degree of polymerization increases while flowing down along the guide 4. In this case, the liquid or molten prepolymer is effectively stirred internally and its surface is renewed while flowing down along the guide, and low boiling point substances are effectively removed, so that the concentration or polymerization proceeds at a high speed. As the concentration or polymerization proceeds, the viscosity increases, so the adhesion to the guide 4 increases, and the amount of the liquid or molten material adhering to the guide 4 increases toward the lower part of the guide 4. This means that the residence time of the liquid or molten prepolymer on the guide, that is, the evaporation time or the polymerization reaction time, increases. Moreover, the liquid or molten prepolymer flowing down under its own weight while being supported by the guide 4 has a very wide surface area per weight, and its surface is renewed efficiently, so that it is considered that evaporation concentration in a high viscosity range and high molecular weight in the latter half of polymerization, which were impossible in the conventionally known evaporation devices and mechanically stirred polymerization reactors, can be easily performed. This is one of the excellent features of the polycarbonate manufacturing apparatus described above.

[0097] In the above-mentioned guide contact flow-down type polymerization apparatus constituting the polycarbonate manufacturing apparatus, the amount of liquid or melt adhering to the guide 4 increases in the latter half of evaporation or polymerization, but since there is only an adhesive holding force corresponding to the viscosity, at the same height of multiple guides 4, approximately the same amount of liquid or melt with approximately the same viscosity is supported by each guide 4. On the other hand, since liquid or melt is continuously supplied to the guide 4 from the top, liquid with approximately the same viscosity or melt with a higher degree of polymerization with approximately the same melt viscosity will continuously fall from the lower end of the guide to the bottom casing. In other words, liquid with approximately the same viscosity and polymer with approximately the same degree of polymerization generated while flowing down the guide will accumulate at the bottom of the bottom casing, and concentrated liquid with no variation in evaporation degree and polymer with no variation in molecular weight will tend to be continuously produced. This is one of the other excellent features of the above-mentioned guide contact flow-down type polymerization apparatus. The concentrated liquid and polymer accumulated in the lower part of the bottom casing are continuously extracted by a discharge pump 8 through a liquid discharge port 7, and in the case of polymer, it is usually continuously pelletized through an extruder or the like. In this case, it is also possible to add additives and the like in the extruder.

[0098] The perforated plate 2 constituting the guide contact flow-down type polymerization apparatus is not particularly limited, but is usually selected from, for example, a flat plate, a corrugated plate, a plate thickened at the center, etc. The cross-sectional shape of the perforated plate 2 is not particularly limited, but is usually selected from shapes such as a circle, an oval, a triangle, a polygon, etc. The cross section of the holes in the perforated plate is not particularly limited, but is usually selected from shapes such as a circle, an oval, a triangle, a slit, a polygon, and a star. The cross-sectional area of ​​the hole is usually, for example, 0.01 to 100 cm 2 and preferably 0.05 to 10 cm 2 and more preferably 0.1 to 5 cm 2The distance between the holes is usually, for example, 1 to 500 mm, and preferably 10 to 100 mm, as measured from the center of the holes. The holes in the perforated plate 2 may be holes passing through the perforated plate 2, or may be holes in which tubes are attached to the perforated plate 2. The holes may also be tapered.

[0099] In the above-mentioned guide contact flow-down type polymerization apparatus, it is preferable that the perforated plate 2 and its holes satisfy the above-mentioned formulae (VI) and (VII). Moreover, the guide 4 constituting the guide contact flow-down type polymerization apparatus does not have a heating source such as a heat medium or an electric heater inside itself, and is preferably made of a material in which the ratio of the length in the vertical direction to the average length of the circumference of the horizontal cross section is very large. The ratio (length in the vertical direction to the cross section / average length of the circumference of the horizontal cross section) is usually, for example, in the range of 10 to 1,000,000, and preferably in the range of 50 to 100,000.

[0100] The horizontal cross-sectional shape of the guide 4 is not particularly limited, but is usually selected from shapes such as a circle, an oval, a triangle, a rectangle, a polygon, a star, etc. The cross-sectional shape of the guide 4 may be the same or different in the length direction. The guide 4 may also be hollow. The guide 4 constituting the above-mentioned polycarbonate manufacturing apparatus has a major feature that it does not have a heat source itself, and therefore there is absolutely no concern about thermal denaturation of the liquid on the surface of the guide 4.

[0101] The guide 4 may be a single member such as a wire, a thin rod, or a thin pipe that prevents liquid or molten prepolymer from entering inside, or may be a combination of multiple members twisted together, etc. Also, it may be a net or a punched plate. The surface of the guide 4 may be smooth or uneven, and may partially have protrusions, etc. Preferred guides 4 are those in the form of a wire or thin rod or other cylindrical shape, the above-mentioned thin pipe or net, or a punched plate.

[0102] In the guide contact flow-down type polymerization apparatus constituting the above-mentioned polycarbonate production apparatus that enables production of high-quality concentrated liquid or polymer on an industrial scale (production volume, long-term stable production, etc.), a particularly preferred type of guide is one in which a plurality of wire-shaped or thin rod-shaped or thin pipe-shaped guides 4 are connected from top to bottom at appropriate intervals above and below using lateral support materials. For example, a lattice-like or mesh-like guide in which multiple wire-like, thin rod-like, or thin pipe-like guides are fixed at appropriate vertical intervals, for example 1 cm to 200 cm, from top to bottom using lateral support materials; a three-dimensional guide in which multiple lattice-like or mesh-like guides are arranged front to back and connected at appropriate vertical intervals, for example 1 cm to 200 cm, using lateral support materials; or a jungle gym-like three-dimensional guide in which multiple wire-like, thin rod-like, or thin pipe-like guides are fixed at appropriate vertical intervals, for example 1 cm to 200 cm, using lateral support materials on the front, back, left and right. The lateral supports not only help maintain the same spacing between each guide, but also provide additional strength to the guides, whether they are generally planar, curved, or three-dimensional. These supports may be of the same material as the guides, or they may be of a different material.

[0103] The above-mentioned guide contact flow-down type polymerization apparatus can also be used as an evaporation apparatus for a liquid having a relatively high viscosity, such as a polymerization apparatus for a condensation polymer, an apparatus for purifying a thermoplastic polymer containing a low boiling point substance such as a monomer, an oligomer, or a by-product, or an apparatus for separating and recovering the polymer from a thermoplastic polymer solution. Therefore, the liquid supplied from the liquid supply zone is a monomer for producing a condensation polymer, a mixture of two or more monomers, a prepolymer of a condensation polymer, or a molten liquid of a condensation polymer in which low-boiling point substances are by-product substances and / or oligomers produced in a polycondensation reaction, and the low-boiling point substances are evaporated and removed from the molten liquid, thereby enabling the apparatus to be used as a polymerization apparatus for condensation polymers in order to improve the degree of polymerization of the prepolymer of the condensation polymer and / or the polymer.

[0104] As the condensation polymer, polycarbonates such as aliphatic polycarbonate, polycarbonate and various copolycarbonates; polyester polycarbonates, and the like are preferable. By using a polycarbonate production apparatus equipped with the above-mentioned guided contact flow-down type polymerization apparatus, it is possible to stably produce high-purity, high-performance condensation polymers that are free of coloration, gel-like substances, or solid foreign matter and have no variation in molecular weight over a long period of time.

[0105] The above-mentioned guide contact falling flow type polymerization apparatus is suitable for evaporating and removing low boiling point substances from a relatively highly viscous liquid. For example, when the above-mentioned guided contact flow-down type polymerization apparatus is used as a polymerization vessel for a condensation polymer, in a conventional polymerization vessel, there is a portion where a part of the liquid remains heated for a long time, and as a result, the retained liquid undergoes denaturation such as coloration, gelation, crosslinking, formation of ultra-high molecular weight, solidification, burning, carbonization, etc., and these denatured substances gradually or intensively become mixed into the polymer, which is unavoidable. However, not only is there no such drawback, but the present invention has excellent effects not found in conventional polymerization vessels. That is, for example, when a molten prepolymer obtained from a dihydroxy compound and a diaryl carbonate is polymerized to produce a polycarbonate, the reaction temperature usually needs to be in the range of 200 to 350°C. In particular, the viscosity increases rapidly in the latter half of the polymerization. Since the aromatic monohydroxy compound produced by the equilibrium reaction must be extracted from the ultra-high viscosity substance, even if a conventional polymerization vessel such as a horizontal twin-shaft stirring reactor for ultra-high viscosity polymers is used, the reaction must be carried out for a long time at a high temperature of 300°C or more and under a high vacuum of 133 Pa or less, and it is difficult to produce a high molecular weight substance for use in a sheet. However, in the guide contact flow-down type polymerization apparatus constituting the above-mentioned polycarbonate production apparatus, efficient surface renewal accompanied by internal stirring is performed, so the polymerization reaction can proceed at a relatively low temperature. Therefore, the preferred reaction temperature is 100 to 290°C, and more preferably 150 to 270°C. The above-mentioned polycarbonate production apparatus is characterized in that the polymerization can be sufficiently carried out at a lower temperature than in the case of a conventional mechanically stirred polymerization apparatus, and this is also one of the reasons why high-quality polycarbonate without coloration or deterioration of physical properties can be produced. Furthermore, conventional polymerization reactors have the drawback that air and other foreign matter may leak in through the seal parts of the agitator under high vacuum, and foreign matter may get mixed in. However, the above-mentioned guide contact flow-down type polymerization apparatus has no mechanical agitation and no seal parts in the agitator, so that leakage of air and other foreign matter and mixing in are extremely low, and high-purity, high-performance polycarbonate can be produced.

[0106] In addition, when a condensation polymer is produced using the above-mentioned polycarbonate production apparatus, the reaction pressure in the guide contact flow-down type polymerization apparatus varies depending on the type of low boiling point by-product, the type and molecular weight of the polymer produced, the polymerization temperature, etc., but is preferably in the range of 400 to 3,000 PaA when the number average molecular weight is 5,000 or less, and is preferably in the range of 50 to 500 PaA when the number average molecular weight is 5,000 to 10,000. When the number average molecular weight is 10,000 or more, the pressure is preferably 300 PaA or less, and particularly preferably in the range of 20 to 250 PaA.

[0107] When a condensation polymer is produced using the above-mentioned guide contact flow-down type polymerization apparatus as a polymerization vessel, it is possible to produce a polymer having a desired degree of polymerization using only one guide contact flow-down type polymerization apparatus. However, a system in which two or more guide contact flow-down type polymerization apparatuses are connected together to successively increase the degree of polymerization depending on the degree of polymerization of the molten monomer or molten prepolymer used as the raw material, the production amount of the polymer, etc. may also be adopted. In such a case, two or more guide contact flow-down type polymerization apparatuses are preferably connected in any one of series, parallel, and a combination of series and parallel.

[0108] In this case, guides and reaction conditions suitable for the polymerization degree of the prepolymer or polymer to be produced can be separately adopted in each guide contact flow-down type polymerization apparatus. For example, in the case of using a first guide contact flow-down type polymerization apparatus, a second guide contact flow-down type polymerization apparatus, a third guide contact flow-down type polymerization apparatus, a fourth guide contact flow-down type polymerization apparatus, etc., and increasing the degree of polymerization in this order, if the total external surface areas of the guides of each polymerization apparatus are S1, S2, S3, S4, etc., then S1≧S2≧S3≧S4≧. The polymerization temperature may be the same in each polymerization apparatus, or may be increased in sequence. The polymerization pressure can also be decreased in sequence in each polymerization apparatus. In this sense, for example, when two polymerization apparatuses, a first guide contact flow-down type polymerization apparatus and a second guide contact flow-down type polymerization apparatus, are used to increase the degree of polymerization in this order, the total external surface area S1 (m 2 ) and the total external surface area S2 (m 2 It is preferable to use a guide such that 1 ≦ S1 / S2 ≦ 20 Formula (XVI) When the S1 / S2 ratio is 1 or more, the variation in molecular weight can be suppressed, stable production over a long period of time becomes possible, and a desired production amount can be obtained. By making S1 / S2 20 or less, the flow rate of the molten prepolymer flowing down the guide in the second polymerization device can be suppressed, and as a result, the residence time of the molten prepolymer can be sufficiently secured, and a polymer with a required molecular weight can be obtained. A more preferable range is 1.5≦S1 / S2≦15.

[0109] In the above-mentioned polycarbonate production apparatus, it is preferable to further install an inert gas absorbing apparatus for absorbing an inert gas into the molten prepolymer of the condensation polymer before it is supplied to the guide contact flow-down type polymerization apparatus. In addition, when a plurality of guide contact flow-down type polymerization apparatuses are connected to be used, it is preferable that an inert gas absorption apparatus for absorbing an inert gas into the molten prepolymer of the condensation polymer before being supplied to the guide contact flow-down type polymerization apparatus is provided for each polymerization apparatus.

[0110] Hereinafter, a case where one guide contact flow-down type polymerization apparatus and one inert gas absorption apparatus are used in combination will be described. The molten prepolymer is introduced into an inert gas absorbing device before being supplied to a guided contact flow-down type polymerization apparatus. In the inert gas absorbing device, the molten prepolymer is treated with an inert gas to cause the molten prepolymer to absorb the inert gas, thereby causing the molten prepolymer to absorb a specific amount of inert gas, 0.0001 to 1 N liters (where N liters is a volume measured under standard temperature and pressure conditions), per 1 kg of the molten prepolymer. The molten prepolymer having absorbed the specific amount of inert gas is then supplied to a guided contact flow-down type polymerization apparatus and polymerized.

[0111] Treating the molten prepolymer with an inert gas means that the molten prepolymer is made to absorb the inert gas under conditions that make it difficult for the molten prepolymer to polymerize. The amount of the inert gas absorbed in the molten prepolymer is preferably 0.0001 to 1 N liter, more preferably 0.001 to 0.8 N liter, and further preferably 0.005 to 0.6 N liter per 1 kg of the molten prepolymer. When the amount of absorbed inert gas is 0.0001 N liters or more per kg of the molten prepolymer, the effect of increasing the polymerization rate achieved by using the inert gas-absorbing prepolymer and the effect of stable polycarbonate production achieved by using the inert gas-absorbing prepolymer become large. Also, in this embodiment, the amount of absorbed inert gas does not need to be more than 1 N liters per kg of the molten prepolymer.

[0112] The amount of inert gas absorbed by the molten polymer can be easily measured by directly measuring the amount of inert gas supplied. When the inert gas is absorbed by the molten prepolymer while flowing through the inert gas absorbing device, the amount of absorbed inert gas can be calculated from the difference between the amount of inert gas supplied and the amount of inert gas discharged. It can also be measured by supplying a predetermined amount of molten prepolymer to an inert gas absorbing device charged with an inert gas of a predetermined pressure, and measuring the amount of pressure reduction in the inert gas absorbing device caused by the inert gas being absorbed by the molten prepolymer. It can also be measured by a batch method in which a predetermined amount of molten prepolymer is supplied to the absorbing device in a batch manner and then the amount of inert gas absorption is measured, or by a continuous method in which the molten prepolymer is continuously supplied to the absorbing device and the amount of inert gas absorption is measured while continuously withdrawing it.

[0113] In this embodiment, it is preferable to absorb the inert gas by treating the molten prepolymer with an inert gas using an inert gas absorption device under a predetermined pressure and under conditions in which the molten prepolymer is difficult to polymerize. Absorbing the inert gas into the molten prepolymer means dispersing and / or dissolving the inert gas in the molten prepolymer. The term "dispersion" refers to a state in which the inert gas is mixed in the molten prepolymer in the form of bubbles, forming a gas-liquid mixed phase, and the term "dissolution" refers to a state in which the inert gas is mixed with the molten prepolymer, forming a uniform liquid phase. It is particularly preferred that the inert gas be dissolved in the molten prepolymer, rather than merely dispersed. In order to efficiently dissolve the inert gas in the molten prepolymer, it is preferable to increase the gas-liquid interfacial area to improve contact efficiency, or to carry out the reaction under pressurized inert gas.

[0114] The inert gas absorption apparatus constituting the above-mentioned polycarbonate production apparatus is not particularly limited in type as long as it is an apparatus capable of absorbing an inert gas into a molten prepolymer, and examples thereof include known apparatuses such as a packed tower type absorption apparatus, a tray type absorption apparatus, a spray tower type absorption apparatus, a fluidized packed tower type absorption apparatus, a liquid film cross-flow absorption type absorption apparatus, a high-speed swirling flow type absorption apparatus, and a mechanical power type absorption apparatus, as well as an apparatus in which the molten prepolymer is absorbed while falling along a guide under an inert gas atmosphere. Alternatively, an apparatus may be used in which an inert gas is directly supplied into a pipe for supplying the molten prepolymer to a guide-contact flow-down type polymerization apparatus, and the prepolymer is absorbed. A spray tower type absorption apparatus or an apparatus for absorbing the prepolymer while dropping it along a guide is particularly preferred.

[0115] As the inert gas absorbing apparatus, an apparatus of the same type as the guide contact flow-down type polymerization apparatus is particularly preferred. Since an inert gas absorption apparatus is operated under conditions that hardly allow polymerization to proceed, it is functionally completely different from a polymerization apparatus. However, the outstanding feature of this type of apparatus is that the surface area per mass of the molten material flowing down the guide is very large, and combined with very good surface renewal and internal stirring of the molten material, it enables very efficient inert gas absorption in a short period of time. Unlike the polymerization device, the inert gas absorption device has almost no change in viscosity of the molten prepolymer at the top and bottom of the guide, so the processing capacity of the molten prepolymer per unit time is large. Therefore, even if it is the same type, the inert gas absorption device can generally be made smaller than the guide contact flow-down type polymerization device.

[0116] The production of the polycarbonate preferred in this embodiment will be described. When the number average molecular weights of the molten prepolymer before and after inert gas absorption are M1 and M2, respectively, it is preferable that the change in molecular weight (M2-M1) before and after inert gas absorption is substantially 2,000 or less, more preferably 1,000 or less, and even more preferably 500 or less. The temperature at which the molten prepolymer absorbs the inert gas is not particularly limited as long as it is in a molten state, but is usually in the range of 150 to 350°C, preferably 180 to 300°C, and more preferably 230 to 270°C.

[0117] The pressure Pg (PaA) at which the inert gas is absorbed into the molten prepolymer is preferably equal to or higher than the pressure used to produce the molten prepolymer. That is, it is preferable to absorb the inert gas under pressure conditions equal to or higher than the reaction pressure used in producing a molten prepolymer of polycarbonate by reacting a dihydroxy compound with a diaryl carbonate. In addition, Pg (PaA) is a pressure higher than the pressure Pp (PaA) of the polymerization reaction in the subsequent guide contact flow-down type polymerization apparatus, and it is preferable that Pg (PaA) satisfies the following relationship with M1 (as defined above). Formula: Pg > 4 × 10 12 × M1 -2.6871 When Pg(PaA) satisfies the relationship of the above formula, the effect of increasing the polymerization rate achieved by using the inert gas-absorbing prepolymer and the effect of stable production of polycarbonate achieved by using the inert gas-absorbing prepolymer are large. It is particularly preferable that the pressure during absorption of the inert gas is normal pressure or increased pressure, since this increases the rate at which the inert gas is absorbed into the molten prepolymer, and as a result, the size of the absorption device can be reduced. There is no particular upper limit to the pressure during inert gas absorption, but it is usually 2×10 7 PaA or less, preferably 1×10 7 PaA or less, preferably 5×106 Inert gas absorption is carried out under a pressure of PaA or less.

[0118] The method for absorbing the inert gas into the molten prepolymer in the inert gas absorption apparatus may be a method in which most of the inert gas supplied to the inert gas absorption apparatus is absorbed into the molten prepolymer, or a method in which a portion of the supplied inert gas is absorbed into the molten prepolymer. The former method is not particularly limited, but examples thereof include a method using a spray tower type absorption apparatus or an apparatus in which the prepolymer is dropped along a guide to absorb the prepolymer, and supplying an amount of inert gas substantially equal to the amount of inert gas absorbed in the molten prepolymer while maintaining the pressure of the absorption apparatus substantially constant, and a method using an absorption apparatus in which an inert gas is directly supplied into a pipe for supplying the molten prepolymer to a polymerization reactor. The latter method is not particularly limited, but examples thereof include a method in which a spray tower type absorption apparatus or an apparatus in which a molten prepolymer is absorbed while falling along a guide is used as an inert gas absorption apparatus, in which an inert gas in an amount greater than that which can be absorbed in the molten prepolymer is circulated through the absorption apparatus, and the excess inert gas is discharged from the inert gas absorption apparatus. The former method is particularly preferred in that the amount of inert gas used is reduced.

[0119] In addition, the inert gas absorption can be performed either by a continuous method in which a molten prepolymer is continuously supplied to an absorption apparatus to absorb the inert gas and the molten prepolymer having absorbed the inert gas is continuously discharged, or by a batch method in which the molten prepolymer is charged in batches into an absorption apparatus to absorb the inert gas.

[0120] The inert gas is a general term for a gas that does not undergo a chemical reaction with the molten prepolymer and is stable under polymerization conditions. The inert gas is not particularly limited, but examples thereof include nitrogen, argon, helium, carbon dioxide, organic compounds that are gaseous at the temperature at which the prepolymer maintains a molten state, and lower hydrocarbon gases having 1 to 8 carbon atoms. The particularly preferred inert gas is nitrogen.

[0121] In the polycarbonate production method of the present embodiment, in the above-mentioned guided contact flow-down type polymerization apparatus, in order to maintain the pressure of the molten prepolymer in which the inert gas has been absorbed in the molten prepolymer supply piping between the inert gas absorbing apparatus and the guided contact flow-down type polymerization apparatus at a predetermined pressure, a predetermined pressure regulating valve may be installed immediately before the inlet of the guided contact flow-down type polymerization apparatus, thereby controlling the pressure of the molten prepolymer. The inside of the guided contact flow-down type polymerization apparatus is at a relatively high vacuum, and the molten prepolymer near the supply port of the apparatus is easily sucked into the apparatus, resulting in a low pressure state. Therefore, the inert gas absorbed in the inert gas absorption device may separate from the molten prepolymer and coagulate. Therefore, in order to prevent this, it is preferable to supply the inert gas to the inert gas absorption device at a pressure higher than the pressure at which the inert gas is absorbed by the molten prepolymer. Specifically, the pressure is preferably in the range of 15 kPaA to 200 kPaA, more preferably 20 kPaA to 150 kPaA, and further preferably 20 to 100 kPaA.

[0122] When a pressure regulating valve is installed or when the pressure is higher than the pressure at which the inert gas is absorbed into the molten prepolymer, the pressure of the molten prepolymer in the piping is stabilized, and separation and aggregation of the inert gas such as nitrogen once absorbed into the molten prepolymer can be suppressed. The uniformity of the molten prepolymer is stabilized, and the uniform and continuous foaming phenomenon of the molten prepolymer is maintained in the guided contact flow-down type polymerization apparatus, so that a stable product can be produced, and there is a tendency that the color tone can be improved and the occurrence of foreign matter such as fish eyes and gels can be suppressed. On the other hand, even if the pressure exceeds 200 kPaA, the effect will not change, and excessive load will be placed on the exhaust gear pump and piping of the inert gas absorption apparatus, which is not realistic as it is necessary to improve the pressure resistance, so it is preferable to set the upper limit at 200 kPaA.

[0123] The polycarbonate production apparatus used in this embodiment preferably satisfies the various conditions described above and has mechanical strength corresponding thereto, and may be equipped with any other device or equipment having any other function necessary for continuous operation. Furthermore, the polycarbonate production apparatus used in this embodiment may be one in which a plurality of the above-mentioned guided contact flow-down type polymerization apparatuses and inert gas absorption apparatuses are combined, or may be one to which devices and equipment having any function other than evaporation are added.

[0124] The downstream equipment 50A and 50B are not particularly limited as long as they are conventional equipment that receives molten polycarbonate, and examples thereof include an extruder, a pelletizer, a sifter, a dryer, a silo, and a packaging machine. For example, it is preferable to feed molten polycarbonate to an extruder, and mix other resins such as ABS or PET, a catalyst deactivator, and additives in the extruder. These other resins and optional additives may be used alone or in combination of two or more.

[0125] (Catalyst deactivator) In the method for producing the polycarbonate of the present embodiment, although not particularly limited, a known catalyst deactivator described in, for example, International Publication No. 2005 / 121213 may be used. In particular, from the viewpoint of producing a polycarbonate having good thermal stability and little coloration, ammonium salts and phosphonium salts of sulfonic acid are preferred, and the above-mentioned salts of dodecylbenzenesulfonic acid such as tetrabutylphosphonium dodecylbenzenesulfonate are more preferred. In addition, as the catalyst deactivator, an ester of sulfonic acid can also be used, and examples of the ester of sulfonic acid include octyl benzenesulfonate, phenyl benzenesulfonate, methyl paratoluenesulfonate, ethyl paratoluenesulfonate, butyl paratoluenesulfonate, octyl paratoluenesulfonate, and phenyl paratoluenesulfonate. In particular, from the viewpoint of producing a polycarbonate having good thermal stability and little coloration, tetrabutylphosphonium dodecylbenzenesulfonate is preferably used. When an alkali metal salt and / or an alkaline earth metal salt is used as the polymerization catalyst, the amount of the catalyst deactivator is preferably 0.5 to 50 mol, more preferably 0.5 to 10 mol, and even more preferably 0.8 to 5 mol, per 1 mol of the polymerization catalyst.

[0126] (Additives) The polycarbonate can be added with resins other than polycarbonate, such as ABS or PET, and additives such as various stabilizers, antioxidants, UV absorbers, release agents, dyes and pigments, and flame retardants, etc. This allows the production of polycarbonate resin compositions suited to various applications. Furthermore, by combining these, a variety of polycarbonate resin compositions can be produced. The additives include heat stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, release agents, dyes and pigments, as well as metal deactivators, antistatic agents, lubricants, nucleating agents and the like. Examples of the heat stabilizer and antioxidant include, but are not limited to, phosphorus compounds, phenol-based stabilizers, organic thioether-based stabilizers, and hindered amine-based stabilizers. Examples of light stabilizers and ultraviolet absorbers include, but are not limited to, salicylic acid-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. As the release agent, a known release agent can be used, and examples thereof include, but are not limited to, 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 glyceryl monostearate, and silicone-based release agents such as silicone oil. As the dyes and pigments, known organic and inorganic dyes and pigments can be used. In addition, for the metal deactivator, antistatic agent, lubricant, lubricant, etc., known materials that exhibit these properties can be used depending on the purpose. These may be used alone or in combination of two or more types.

[0127] (Extruder) From the viewpoint of producing a polycarbonate having good thermal stability and little coloration, a single-screw extruder with a short residence time is preferred, and from the viewpoint of producing a polycarbonate with little foreign matter, a dynamic mixer having an agitator without a residence section is preferred, and a twin-screw extruder having self-cleaning properties is even more preferred. When the catalyst deactivator and / or additives are added in a molten state or in a solution state, a metering pump such as a plunger pump is preferably used as a supply device to the kneading device. In order to prevent molten polycarbonate from flowing back from the kneading apparatus into the piping for supplying the catalyst deactivator and / or additives, the catalyst deactivator and / or additive supply section in the kneading apparatus is generally equipped with an injection valve having a check function. In the case where a plurality of supply sections join together and are connected to the injection valve, it is preferable to install a check valve in the piping between the metering pump and the kneading apparatus. Furthermore, a forced injection device such as a vane pump may be installed between the metering pump and the kneading device. It is preferable that the pipes for supplying the catalyst deactivator and / or the additives are kept warm. When the catalyst deactivator and / or additive are supplied in a molten state, it is preferable to control the temperature to be at or above their melting point and below the temperature at which they do not deteriorate. When the catalyst deactivator and / or additive are supplied in a solution state using a specified solvent, it is preferable to control the temperature to be at or above the melting point of the solution, or above the temperature at which the catalyst deactivator and / or additive do not precipitate and below the temperature at which they do not deteriorate. When the softening temperature of the molten polycarbonate is within the above temperature range, even if the molten polycarbonate flows back into the supply pipe, the molten state is maintained and the polycarbonate is prevented from solidifying. These supply pipes are preferably provided with a downward slope toward the kneading device.

[0128] The polycarbonate of this embodiment can be obtained by the above-mentioned method for producing a polycarbonate.

[0129] As is apparent from the above description, the production method of the present embodiment makes it possible to continuously produce polycarbonate. The polycarbonate obtained by the method for producing a polycarbonate according to the present embodiment can be made into a molded article through a predetermined molding process. The molding step may be a known molding step without any particular limitation. For example, a molded product can be obtained by molding polycarbonate using an injection molding machine, an extrusion molding machine, a blow molding machine, a sheet molding machine, or the like. The resulting molded products can be used in a wide range of applications, including automobiles, electrical appliances, electronics, office automation, optical media, building materials, and medical applications. EXAMPLES

[0130] In the present examples, various measurements were carried out by the methods shown below.

[0131] [A: acid dissociation constant pKa] In this example, the following literature values ​​were used for the acid dissociation constant pKa: Bisphenol A: 9.80 1,3-Propanediol: 14.46 1,4-Butanediol: 14.73 1,6-Hexanediol: 14.87 1,4-Cyclohexanedimethanol: 14.70 Ethylene glycol: 15.10 Glycerol: 14.15 Erythritol: 13.90 Xylitol: 13.24 1,4-Dioxane-2,5-diol: 11.97 Furan-2,5-bismethanol: 13.70 1,4-anhydroerythritol: 13.66 2,2,4,4-Tetramethyl-1,3-cyclobutanediol: 14.67 Curcumin: 8.09 Isosorbide: 13.10 When two or more dihydroxy compounds are used, A was determined as the weighted average of the acid dissociation constants (pKa) of the dihydroxy compounds.

[0132] [B: Supply amount] The amount of the dihydroxy compound and the diaryl carbonate fed per hour was the total amount of the dihydroxy compound and the diaryl carbonate fed to the stirred tank type first polymerization vessel 35.

[0133] [C: Catalyst concentration] The catalyst concentration relative to the diaryl carbonate was calculated from the value converted into the mass of the metal element in the catalyst (unit: mass ppb). Catalyst concentration (mass ppb) = [mass of metal element in catalyst] / [mass of diaryl carbonate]

[0134] [D: Viscosity of molten prepolymer] The viscosity was measured using a rotational viscometer in accordance with JIS Z 8803: 2011. The measurement temperature was the temperature of the stirred tank type first polymerization vessel.

[0135] [Raw material loss weight] From 24 hours to 72 hours after the start of production, the phenol gas accompanied with the unreacted raw materials discharged from each vent of the stirred tank type first polymerization vessel 35, the stirred tank type second polymerization vessel 37, the first guide contact flow-down type polymerization vessel 42, the second guide contact flow-down type polymerization vessel 48A, and the second guide contact flow-down type polymerization vessel 48B was condensed and recovered in total using a condenser (not shown) for composition analysis (liquid chromatography) and measurement of the amount of raw material loss per day. From the results of the composition analysis and the amount of phenol gas recovered including the unreacted raw materials, the weights of the dihydroxy compound and diaryl carbonate discharged outside the system were calculated.

[0136] [Continuity of operation] 72 hours after the start of production, the molten prepolymer was checked for the presence or absence of discolored foreign matter (discolored polymer foreign matter that is produced when excessive heat is applied to the polymer). <Standards> ○: No discoloration or foreign matter ×: Discoloration and foreign matter occurred

[0137] Example 1 Using a polycarbonate production apparatus having the configuration shown in FIG. 5, polycarbonate was produced as follows.

[0138] As shown in FIG. 5, polycarbonate was produced using a polycarbonate production apparatus in which two inert gas absorption devices (a first inert gas absorption device 39 and a second inert gas absorption device 44) and two guide contact flow-down type polymerization devices (a first guide contact flow-down type polymerization device 42 and a second guide contact flow-down type polymerization device 48A) were connected in series in the order of the first inert gas absorption device 39, the first guide contact flow-down type polymerization device 42, the second inert gas absorption device 44, and the second guide contact flow-down type polymerization device.

[0139] The first inert gas absorption apparatus 39 and the second inert gas absorption apparatus 44, the schematic configuration of which is shown in Fig. 1, were used. Note that the inert gas absorption apparatuses 39 and 44 have almost the same apparatus configuration as the guide contact flow-down type polymerization apparatuses 42, 48A, and 48B described below, and therefore the same reference numerals are used for the common parts.

[0140] In the first inert gas absorbing device, the upper part of the casing in the inert gas absorbing zone was cylindrical, and the tapered lower part constituting the bottom casing 11 was an inverted cone with an inner diameter of 0.5 m, a width of 32.3 cm, h=4 m, and five wires with a diameter of 3 mm arranged at 8 cm intervals. Each of the five wires had two guides 4 to which wires with a diameter of 3 mm and a length of 32.3 cm were attached at 25 cm intervals perpendicular to the wires, and the upper ends of these were directly attached to the perforated plate 2. The distance between the two guides was 80 mm. The perforated plate 2 had 10 holes with a diameter of about 0.2 cm to distribute the molten prepolymer to each guide. A jacket (not shown) was attached to the outside of the first inert gas absorbing device and was heated with a heat medium. The second inert gas absorbing device had almost the same shape as the first inert gas absorbing device, except that the diameter of the holes in the perforated plate 2 was about 0.6 cm.

[0141] The first guide contact flow-down type polymerization apparatus 42 has the same structure as the inert gas absorption apparatus, and in the polymerization reaction zone, the upper part of the casing is cylindrical, and the tapered lower part of the bottom casing 11 is an inverted cone with an inner diameter of 0.5 m, and has two guides with a width of 32.3 cm and a length of h=8 m, in which five wires with a diameter of 3 mm are arranged at intervals of 8 cm, and the upper ends of these guides are directly attached to the porous plate 2. The interval between the two guides was 80 mm each.

[0142] The molten prepolymer was distributed to each guide 4 through ten holes of about 0.2 cm in diameter on the perforated plate (distribution plate) 2. A jacket (not shown) was attached to the outside of the first guide contact flow-down type polymerization apparatus, and it was heated with a heat medium. The second guide contact flow-down type polymerization apparatus had almost the same shape as the first guide contact flow-down type polymerization apparatus, except that the diameter of the holes in the perforated plate was about 0.4 cm.

[0143] The method for producing the polycarbonate in Example 1 will be specifically described below. Mixing tank 31 (inner capacity 1m 3 200 kg of molten diphenyl carbonate (hereinafter referred to as "DPC-1") at 160°C was added to the mixing tank 31. Next, potassium hydroxide was added as a catalyst at 200 ppb by mass (catalyst concentration converted into the mass of metal element in potassium hydroxide) relative to the diphenyl carbonate, and bisphenol A (acid dissociation constant pKa = 9.8) was gradually added in an amount equal to the moles of DPC-1 added while heating and stirring so as to maintain the temperature of the mixed liquid in the mixing tank 31 at 100°C or higher. When the temperature of the mixture reaches 180°C, the dissolved mixture storage tank (1 m 3 )Transferred to 33A. The dissolved mixture held in dissolved mixture storage tank 33A for 4 to 6 hours was filtered at a flow rate of 0.04 ton / hr through two polymer filters with different pore sizes (not shown, upstream pore size 5 μm, downstream pore size 2.5 μm) arranged in series between dissolved mixture storage tank 33A and stirred tank-type first polymerization vessel 35.

[0144] The dissolved mixture after filtration was heated in a preheater (not shown) and supplied to a stirring tank type first polymerization vessel 35. The liquid temperature at the outlet of the preheater was 210°C. When the level of the dissolved mixture in dissolved mixture storage tank 33A fell below a predetermined value, the source of the dissolved mixture supplied to stirred tank-type first polymerization vessel 35 was switched from dissolved mixture storage tank 33A to dissolved mixture storage tank 33B. Supply of the dissolved mixture to stirred tank-type first polymerization vessel 35 was carried out continuously by repeating an operation of alternately switching the supply source between dissolved mixture storage tanks 33A and 33B every 3.9 hours. Both of the dissolved mixture storage tanks 33A and 33B were equipped with an internal coil and a jacket, and maintained at 180°C.

[0145] In the first stirred tank type polymerization vessel 35 and the second stirred tank type polymerization vessel 37, stirring was performed under reduced pressure, and the dissolved mixture was polymerized while removing the generated phenol to perform prepolymerization, thereby obtaining a molten prepolymer. During the prepolymerization, gas was discharged from the vents of the first polymerizer 35 and the second polymerizer 37. At that time, the temperature of the first stirred tank type polymerization vessel 35 was 220°C, the pressure was 13.3 kPaA, the impeller rotation speed was 60 rpm, and the viscosity of the molten prepolymer at the outlet of the first stirred tank type polymerization vessel 35 (residence time in the first stirred tank type polymerization vessel 35 = the liquid retention volume in the first stirred tank type polymerization vessel divided by the liquid supply volume to the first stirred tank type polymerization vessel: 1 hour) was 41 mPa s. Furthermore, the temperature of the second stirred tank type polymerization vessel 37 was 270°C, and the pressure was 2.66 kPaA. The obtained molten polycarbonate prepolymer was continuously fed by a feed pump 38 through the liquid receiving port 1 of the first inert gas absorption device to the liquid feeding zone 3 .

[0146] The prepolymer was continuously supplied to the inert gas absorption zone 15, which was the internal space, through the perforated plate 2, which was the distribution plate of the first inert gas absorption device 39, and absorbed the inert gas while flowing down along the guide 4. The inert gas absorbing zone 15 , which is the internal space of the first inert gas absorbing device 39 , is maintained at 180 kPaA by supplying nitrogen gas from the inert gas supply port 9 . The molten prepolymer (containing 0.04 N liters of nitrogen per kg of the molten prepolymer) which dropped from the lower part of the guide 4 into the tapered lower part of the bottom casing 11 of the first inert gas absorption apparatus 39 was continuously discharged by a discharge pump 8 (corresponding to the symbol 40 in FIG. 5) so that the amount at the bottom of the apparatus was approximately constant, and the pressure of the molten prepolymer entering the valve was maintained at 25 kPaA by a pressure regulating valve 41 at the liquid receiving port 1 of the first guide contact flow-down type polymerization apparatus 42, and the molten prepolymer was continuously supplied to the liquid supply zone 3 through the liquid receiving port 1 of the first guide contact flow-down type polymerization apparatus 42 (see FIG. 2).

[0147] The prepolymer was continuously supplied to the evaporation zone 5, which was the internal space, through the perforated plate 2, which was the distribution plate, of the first guide contact flow-down type polymerization apparatus 42, and was allowed to flow down along the guide 4, while the polymerization reaction of polycarbonate was continuously carried out by the melt polycondensation method. During the melt polycondensation, gas was discharged from the vent of the first guide contact flow-down type polymerization apparatus 42. The evaporation zone 5 , which was the internal space of the first guide contact flow-down type polymerization apparatus 42 , was maintained at a pressure of 800 PaA through a vacuum vent port 6 . The molten prepolymer of polycarbonate with an increased degree of polymerization, which dropped from the bottom of the guide 4 into the tapered bottom of the bottom casing 11 of the first guide contact flow-down type polymerization apparatus 42, was continuously extracted at a constant flow rate from the liquid discharge port 7 by a discharge pump 8 (corresponding to the symbol 43 in FIG. 5) so that the amount at the bottom would be approximately constant, and was then continuously supplied to the liquid supply zone 3 of the second inert gas absorption apparatus 44.

[0148] The molten prepolymer was continuously fed through the perforated plate 2 serving as the distribution plate of the second inert gas absorbing device 44 into the inert gas absorbing zone 15 serving as the internal space. The molten prepolymer was allowed to flow downward along the guide 4 while absorbing the inert gas. The inert gas absorbing zone 15 , which is the internal space of the second inert gas absorbing device 44 , was maintained at 200 kPaA by supplying nitrogen gas from the inert gas supply port 9 . The molten prepolymer (containing 0.05 N liter of nitrogen per 1 kg of the molten prepolymer) which dropped from the lower part of the guide 4 into the tapered lower part of the bottom casing 11 of the second inert gas absorption apparatus 44 was continuously discharged at a constant rate by supply pumps 46A and 46B, and the pressure of the molten prepolymer entering the valves was maintained at 25 kPaA by pressure regulating valves 47A and 47B at the liquid receiving ports 1 of the second guide contact flow-down type polymerization apparatuses 48A and 48B, and the molten prepolymer was continuously supplied to each liquid supply zone 3. The molten prepolymer was continuously supplied to the evaporation zone 5, which was the internal space, through the perforated plate 2, which was the distribution plate in the second guide contact flow-down type polymerization apparatuses 48A and 48B, and was allowed to flow down along the guide 4, while the polymerization reaction of polycarbonate was continuously carried out by the melt polycondensation method (see FIG. 2). During the melt polycondensation, gas was discharged from the vents of the second guide contact flow-down type polymerization apparatuses 48A and 48B. The evaporation zones, which were the internal spaces of the second guide contact flow-down type polymerization apparatuses 48A and 48B, were each maintained at a pressure of 120 PaA through a vacuum vent port 6. The polycarbonate that dropped from the bottom of the guide 4 into the tapered bottom of the bottom casing 11 of the second guide contact flow-down type polymerization apparatus 48A and 48B was continuously extracted as strands from the downstream equipment 50A and 50B by discharge pump 8 (corresponding to symbols 49A and 49B in FIG. 5) so that the amount at the bottom would be approximately constant, and after cooling, it was cut to obtain pellet-like polycarbonate. No additives were added.

[0149] The production was continued for 72 hours, and 24 hours after the start of production, the phenol gas accompanied with the unreacted raw materials discharged from each vent of the first stirred tank type polymerization vessel 35, the second stirred tank type polymerization vessel 37, the first guide contact flow-down type polymerization vessel 42, the second guide contact flow-down type polymerization vessel 48A, and the second guide contact flow-down type polymerization vessel 48B was condensed and recovered in total using a condenser (not shown) for composition analysis (liquid chromatography) and measurement of the amount of raw material loss per day. Furthermore, 72 hours after the start of production, the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of the first stirred tank type polymerization vessel 35 was confirmed. The results are shown in Table 1.

[0150] [Examples 2 to 4] Polycarbonate was produced in the same manner as in Example 1 except that the raw materials and conditions were changed as shown in Table 1, and the amount of raw material loss and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of the stirred tank-type first polymerization vessel 35 were confirmed.

[0151] [Comparative Examples 1-2] Polycarbonate was produced in the same manner as in Example 1 except that the conditions were changed as shown in Table 1, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of stirred tank-type first polymerization vessel 35 were confirmed.

[0152] [Table 1]

[0153] Example 5 Using a polycarbonate production apparatus having the configuration shown in FIG. 5, polycarbonate was produced as follows. For the first inert gas absorption device 39, in the inert gas absorption zone 15, which is the internal space, the upper part of the side casing 10 is cylindrical, and the bottom casing 11, which is the tapered lower part constituting the casing, is an inverted cone, with L = 500 cm, h = 400 cm, D = 200 cm, d = 20 cm, and C = 150° in Figure 1. The diameter of the guide 4 provided in the inert gas absorption zone 50, which is the internal space, is 0.3 cm, and the total external surface area S of the guide 4 is 60 m 2 The diameter of the holes in the perforated plate provided above the inert gas absorption zone 50, which is the internal space, was about 0.2 cm. The second inert gas absorbing device 44 had almost the same shape as the first inert gas absorbing device 39, except that the diameter of the holes in the perforated plate was about 0.6 cm. A schematic diagram of a guide contact flow-down type polymerization apparatus is shown in Fig. 2. This guide contact flow-down type polymerization apparatus had a disk-shaped flow path control part 20 having a thickness of about 2 cm, and a cylindrical guide 4, as shown in Fig. 3.

[0154] FIG. 3 is a schematic diagram showing the upper part of the guide 4 of the guide contact flow-down type polymerization apparatus. In the guide contact flow-down type polymerization apparatus, the flow path control component 20 was suspended and fixed from the upper part so that the distance from the upper inner wall surface 23 of the liquid supply zone 3 was about 8 cm. The distance between the inner side wall surface 22 of the liquid supply zone 3 and the flow path control component 20 was approximately 9 cm, and the distance between the perforated plate 2 and the flow path control component 20 was approximately 8 cm. The peripheral portion of this disk-shaped flow path control component 20 was designed so that the vertical cross section was a semicircle with a radius of about 1 cm, and was designed to prevent liquid from accumulating on the peripheral portion. The material of this guide contact flow-down type polymerization apparatus was all stainless steel. The discharge pump 8 was a gear pump when the concentrated liquid was highly viscous, and was a normal liquid-transfer pump when the viscosity was not so high. The guide contact flow-down type polymerization vessel 42 had a cylindrical side casing 10 and a cone-shaped bottom casing 11, and in FIG. 2, L=950 cm and h=850 cm. The inner diameter of the side casing of the evaporation zone 5 was D=400 cm, the inner diameter of the liquid outlet 7 of the cone-shaped bottom casing 11 was d=20 cm, and C=150 degrees. Total external surface area of ​​the entire guide 4 S = 750 m 2 It was. Also, the diameter of the guide was 0.3 cm. Perforated plate 2, 1m 2 Average number of holes per m 2 ) = about 500. The diameter of the holes in the perforated plate = about 0.2 cm. The upper area of ​​the perforated plate, including the upper area of ​​the holes, T (m 2 ) and the total effective cross-sectional area of ​​the holes Q(m 2 ) was 1,300 (T / Q).

[0155] In the liquid supply zone 3 in FIG. 2, the liquid containing a low boiling point substance supplied from the liquid receiving port 1 passes between the upper surface of the flow path control component 20 and the upper inner wall surface 23 of the liquid supply zone 3, and between the inner side wall surface 22 of the liquid supply zone 3 and the flow path control component 20 in FIG. 3, mainly flowing from the periphery to the center of the perforated plate 2, and is uniformly distributed to each guide 4 through the holes 21 of the perforated plate 2, etc. The guided contact flow-down type polymerization apparatus was provided at its lower part with an inert gas supply port 9, and at its upper part with a vacuum vent port 6 (connected to a gas condenser and a pressure reducing device) for withdrawing the evaporated low boiling point substances. The outside of the guide contact flow-down type polymerization apparatus was provided with a jacket or a heating tube for a heat transfer medium, so that a predetermined temperature could be maintained with the heat transfer medium. The second guide contact flow-down type polymerization apparatuses 48A and 48B had a disk-shaped flow path control component 20 having a thickness of about 2 cm and a guide 4 in the structure shown in FIG. The disk-shaped flow path control component 20 was suspended and fixed from above so that the distance from the upper inner wall surface 23 of the liquid supply zone was about 8 cm. The distance between the inner side wall surface 22 of the liquid supply zone and the flow path control component 20 was about 9 cm, and the distance between the perforated plate 2 and the flow path control component 20 was about 8 cm. The peripheral portion of this disk-shaped flow path control component 20 was designed so that the vertical cross section was a semicircle with a radius of about 1 cm, and was designed to prevent liquid from accumulating on the peripheral portion. Moreover, the cross section of the connection between the inner side wall surface 22 of the liquid supply zone and the perforated plate 2 was machined to have a concave shape on the inside as shown in FIG. 4, and the angle E of the rising portion was about 170 degrees.

[0156] The materials of the guide contact flow-down type polymerization apparatus were all stainless steel. A discharge pump 8 was provided at the bottom of the second guide contact flow-down type polymerization apparatus. When the concentrated liquid was highly viscous, a gear pump was used, and when the viscosity was not so high, a normal liquid transfer pump was used. The second guide contact flow-down type polymerization apparatus had a cylindrical side casing 10 and a cone-shaped bottom casing 11 . The second guide contact flow-down type polymerization apparatus had L=1,000 cm and h=900 cm in FIG. The inner diameter of the side casing of the evaporation zone 5 was D=500 cm, the inner diameter of the liquid outlet 7 of the cone-shaped bottom casing 11 was d=40 cm, and C=155 degrees. Total external surface area of ​​the entire guide 4 S = 250 m 2 It was. Moreover, the outer diameter r of the guide was 0.3 cm. Perforated plate 2, 1m 2 Average number of holes per m 2 )N = about 140. The diameter of the holes in the perforated plate = about 0.4 cm. The upper area of ​​the perforated plate, including the upper area of ​​the holes, T (m 2 ) and the total effective cross-sectional area of ​​the holes Q(m 2 ) was 470 (T / Q). The structure of the second guide contact flow-down type polymerization apparatus in the liquid supply zone 3 was the same as that of the first guide contact flow-down type polymerization apparatus. The materials of the above-mentioned inert gas absorption apparatus and the first and second guide contact flow-down type polymerization apparatus were all stainless steel, except for the discharge pump 8.

[0157] As shown in FIG. 5, polycarbonate was produced using a polycarbonate production apparatus in which two inert gas absorption apparatuses (a first inert gas absorption apparatus 39 and a second inert gas absorption apparatus 44) and two guide contact flow-down type polymerization apparatuses (a first guide contact flow-down type polymerization apparatus 42 and a second guide contact flow-down type polymerization apparatus 48A and 48B) were connected in series in the order of the first inert gas absorption apparatus 39, the first guide contact flow-down type polymerization apparatus 42, the second inert gas absorption apparatus 44, and the second guide contact flow-down type polymerization apparatus (two apparatuses arranged in parallel). The method for producing the polycarbonate in Example 5 will be specifically described below. Mixing tank 31 (inner capacity 120m 3 ) was charged with 40 tons of molten diphenyl carbonate (DPC-1) at 160°C. Next, potassium hydroxide was added as a catalyst at 120 ppb by mass relative to the diphenyl carbonate, and the same mole of bisphenol A (acid dissociation constant pKa = 9.8) as the DPC-1 was added over a period of 1.8 hours while heating and stirring the mixed liquid in the mixing tank so as to maintain the temperature of the mixed liquid at 100°C or higher. When the dihydroxy compound was a solid, it was weighed using a weighing hopper equipped with a load cell weighing device, and when it was a liquid, it was weighed using a Coriolis type mass weigher. When the temperature of the mixture reaches 180°C, the dissolved mixture storage tank (capacity 120 ml) 3 )The transfer took an hour to 33A. The dissolved mixture held in dissolved mixture storage tank 33A for 4 to 6 hours was filtered at a flow rate of 10 ton / hr through two polymer filters with different pore sizes (not shown, upstream pore size 5 μm, downstream pore size 2.5 μm) arranged in series between dissolved mixture storage tank 33A and stirred tank-type first polymerization vessel 35. The dissolved mixture after filtration was heated in a preheater (not shown) and supplied to a stirring tank type first polymerization vessel 35. The liquid temperature at the outlet of the preheater was 210°C. When the level of the dissolved mixture in dissolved mixture storage tank 33A fell below a predetermined value, the source of the dissolved mixture supplied to stirred tank-type first polymerization vessel 35 was switched from dissolved mixture storage tank 33A to dissolved mixture storage tank 33B. Supply of the dissolved mixture to stirred tank-type first polymerization vessel 35 was carried out continuously by repeating an operation of alternately switching the supply source between dissolved mixture storage tanks 33A and 33B every 3.9 hours. Both of the dissolved mixture storage tanks 33A and 33B were equipped with an internal coil and a jacket, and maintained at 180°C.

[0158] In a first stirred tank type polymerization vessel 35 and a second stirred tank type polymerization vessel 37, stirring was carried out under reduced pressure, and the dissolved mixture was reacted while removing generated phenol, to obtain a prepolymer. At that time, the temperature of the first stirred tank-type polymerization vessel 35 was 220°C, the pressure was 13.3 kPaA, the impeller rotation speed was 60 rpm, and the viscosity of the molten prepolymer at the outlet of the first stirred tank-type polymerization vessel 35 (residence time in the first stirred tank-type polymerization vessel 35: 1 hour) was 78 mPa s. Furthermore, the temperature of the second stirred tank-type polymerization vessel 37 was 270°C, and the pressure was 2.66 kPaA. The obtained molten polycarbonate prepolymer was continuously fed by a feed pump 38 through the liquid receiving port 1 of the first inert gas absorption device to the liquid feeding zone 3 . The prepolymer was continuously supplied to the inert gas absorption zone 15, which was the internal space, through the perforated plate 2, which was the distribution plate of the first inert gas absorption device 39, and absorbed the inert gas while flowing down along the guide 4. The inert gas absorption zone 15 , which was the internal space of the first inert gas absorption device 39 , was maintained at 180 kPaA by supplying nitrogen gas from the inert gas supply port 9 . The molten prepolymer (containing 0.04 N liters of nitrogen per 1 kg of the molten prepolymer) which dropped from the lower part of the guide 4 into the tapered lower part of the bottom casing 11 of the first inert gas absorption apparatus 39 was continuously discharged by a discharge pump 8 (corresponding to the symbol 40 in FIG. 5 ) so that the amount at the bottom of the apparatus was approximately constant, and the pressure of the molten prepolymer entering the valve was maintained at 25 kPaA by a pressure regulating valve 41 at the liquid receiving port 1 of the first guide contact flow-down type polymerization apparatus 42, and the molten prepolymer was continuously supplied to the liquid supply zone 3 via the liquid receiving port 1 of the first guide contact flow-down type polymerization apparatus 42. The prepolymer was continuously supplied to the evaporation zone 5, which was the internal space, through the perforated plate 2, which was the distribution plate of the first guide contact flow-down type polymerization apparatus 42, and while flowing down along the guide 4, the polymerization reaction of polycarbonate was continuously carried out by the melt polycondensation method. The evaporation zone 5 , which was the internal space of the first guide contact flow-down type polymerization apparatus 42 , was maintained at a pressure of 800 PaA through a vacuum vent port 6 . The molten prepolymer of polycarbonate with an increased degree of polymerization, which dropped from the bottom of the guide 4 into the tapered bottom of the bottom casing 11 of the second guide contact flow-down type polymerization apparatus 42, was continuously extracted at a constant flow rate from the liquid discharge port 7 by a discharge pump 8 (corresponding to the symbol 43 in FIG. 5) so that the amount at the bottom would be approximately constant, and was then continuously supplied to the liquid supply zone 3 of the second inert gas absorption apparatus 44.

[0159] The molten prepolymer was continuously fed through the perforated plate 2 serving as the distribution plate of the second inert gas absorbing device 44 into the inert gas absorbing zone 15 serving as the internal space. The molten prepolymer was allowed to flow downward along the guide 4 while absorbing the inert gas. The inert gas absorbing zone 15 , which is the internal space of the second inert gas absorbing device 44 , was maintained at 200 kPaA by supplying nitrogen gas from the inert gas supply port 9 . The molten prepolymer (containing 0.05 N liter of nitrogen per 1 kg of the molten prepolymer) that dropped from the lower part of the guide 4 into the tapered lower part of the bottom casing 11 of the second inert gas absorption apparatus was divided into two parts (divided at a ratio of 50:50) by the three-way polymer valve 45 and continuously discharged at a constant amount by the discharge pump 8 (corresponding to the symbols 46A and 46B in FIG. 5) so that the amount at the bottom would be approximately constant, and the pressure of the molten prepolymer entering the valve was maintained at 25 kPaA by the pressure regulating valves 47A and 47B at the liquid receiving ports 1 of the second guide contact flow-down type polymerization apparatuses 48A and 48B, and the molten prepolymer was continuously supplied to each liquid supply zone 3. The molten prepolymer was continuously supplied to the evaporation zone 5, which was the internal space, through the perforated plate 2, which was the distribution plate in the second guide contact flow-down type polymerization apparatus, and while the molten prepolymer was flowing down along the guide 4, the polymerization reaction of polycarbonate was continuously carried out by the melt polycondensation method. The evaporation zone 5 , which was the internal space of the second guide contact flow-down type polymerization apparatus, was maintained at a pressure of 120 PaA through a vacuum vent port 6 . The polycarbonate that dropped from the bottom of guide 4 into the tapered bottom of bottom casing 11 of the second guide contact flow-down type polymerization apparatus was continuously extracted as strands from downstream equipment 50A, 50B by supply pumps 49A, 49B so that the amount at the bottom would be approximately constant, and after cooling, it was cut to obtain pellet-like polycarbonate. No additives were added.

[0160] The production was continued for 72 hours, and 24 hours after the start of production, the phenol gas accompanied with the unreacted raw materials discharged from each vent of the first stirred tank type polymerization vessel 35, the second stirred tank type polymerization vessel 37, the first guide contact flow-down type polymerization vessel 42, the second guide contact flow-down type polymerization vessel 48A, and the second guide contact flow-down type polymerization vessel 48B was condensed and recovered in total using a condenser (not shown) for composition analysis (liquid chromatography) and measurement of the amount of raw material loss per day. Furthermore, 72 hours after the start of production, the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of the first stirred tank type polymerization vessel 35 was confirmed. The results are shown in Table 2.

[0161] [Examples 6 to 9] Polycarbonate was produced in the same manner as in Example 5 except that the raw materials and conditions were changed as shown in Table 2, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of stirred tank-type first polymerization vessel 35 were confirmed.

[0162] [Comparative Examples 3 to 6] Polycarbonate was produced in the same manner as in Example 5 except that the conditions were changed as shown in Table 2, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of stirred tank-type first polymerization vessel 35 were confirmed.

[0163] [Table 2]

[0164] [Examples 10 to 13] Except for changing the dihydroxy compound to a component containing isosorbide (formula F-1 below) shown in Table 3 and changing the conditions as described in Table 3, polycarbonate was produced in the same manner as in Example 1, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of the stirred tank-type first polymerization vessel 35 were confirmed. [ka]

[0165] [Comparative Examples 7 to 8] Polycarbonate was produced in the same manner as in Example 10 except that the conditions were changed as shown in Table 3, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of stirred tank-type first polymerization vessel 35 were confirmed.

[0166] [Table 3]

[0167] [Examples 14 to 25] Except for changing the dihydroxy compound to a component containing curcumin (the following formula A-1) shown in Table 4 and changing the conditions as described in Table 4, polycarbonate was produced in the same manner as in Example 1, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of the stirred tank-type first polymerization vessel 35 were confirmed. [ka]

[0168] Comparative Example 9 Polycarbonate was produced in the same manner as in Example 14 except that the conditions were changed as shown in Table 4, and the amount of raw material loss under the conditions was confirmed, as well as the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of stirred tank-type first polymerization vessel 35.

[0169] [Table 4]

[0170] [Examples 26 to 28] Except for changing the dihydroxy compound to a component containing 1,4-dioxane-2,5-diol (formula D-1 below) shown in Table 5 and changing the conditions as described in Table 5, polycarbonate was produced in the same manner as in Example 1, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of the stirred tank-type first polymerization vessel 35 were confirmed. [ka]

[0171] Comparative Example 10 Polycarbonate was produced in the same manner as in Example 26 except that the conditions were changed as shown in Table 5, and the amount of raw material loss under the conditions was confirmed, as well as the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of stirred tank-type first polymerization vessel 35.

[0172] [Table 5]

[0173] [Examples 29 to 31] Except for changing the dihydroxy compound to a component containing furan-2,5-bismethanol (formula B-1 below) shown in Table 6 and changing the conditions as described in Table 6, polycarbonate was produced in the same manner as in Example 1, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of the stirred tank-type first polymerization vessel 35 were confirmed. [ka]

[0174] Comparative Example 11 Polycarbonate was produced in the same manner as in Example 29 except that the conditions were changed as shown in Table 6, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of stirred tank-type first polymerization vessel 35 were confirmed.

[0175] [Table 6]

[0176] [Examples 32 to 34] Except for changing the dihydroxy compound to a component containing 1,4-anhydroerythritol (formula E-1 below) shown in Table 7 and changing the conditions as described in Table 7, polycarbonate was produced in the same manner as in Example 1, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of the stirred tank-type first polymerization vessel 35 were confirmed. [ka]

[0177] Comparative Example 12 Polycarbonate was produced in the same manner as in Example 32 except that the conditions were changed as shown in Table 7, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of the stirred tank-type first polymerization vessel 35 were confirmed.

[0178] [Table 7]

[0179] [Examples 35 to 37] Except for changing the dihydroxy compound to a component containing 2,2,4,4-tetramethyl-1,3-cyclobutanediol (formula C-1 below) shown in Table 8 and changing the conditions as described in Table 8, polycarbonate was produced in the same manner as in Example 1, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of the stirred tank-type first polymerization vessel 35 were confirmed. [ka]

[0180] Comparative Example 13 Polycarbonate was produced in the same manner as in Example 35 except that the conditions were changed as shown in Table 8, and the amount of raw material loss under those conditions and the presence or absence of discolored foreign matter in the molten prepolymer at the outlet of the stirred tank-type first polymerization vessel 35 were confirmed.

[0181] [Table 8] [Explanation of symbols]

[0182] 1 Liquid inlet 2 perforated plate 3 Liquid Delivery Zone 4 Guide 5. The evaporation zone, which is the internal space 6 Vacuum vent 7 Liquid outlet 8 Discharge Pump 9 Inert gas supply port 10 Side casing 11 Bottom casing 12 Extraction port 15 Inert gas absorption zone, which is the internal space 20 Flow path control parts 21 Perforated plate hole 22 Inner sidewall of liquid supply zone 23 Upper inner wall surface of liquid supply zone 31 Mixing tank 32, 34A, 34B Transfer pump 33A,33B Dissolved mixture storage tank 35 First Polymerizer 36, 38, 40, 43, 46A, 46B, 49A, 49B Supply Pump 37 Second Polymerizer 39 First inert gas absorption device 41, 47A, 47B Pressure Regulating Valve 42 First guide contact flow-down type polymerization device 44 Second inert gas absorption device 45 3-way polymer valve 48A, 48B Second guide contact flow-down type polymerization device 50A downstream device 50B Back-end equipment

Claims

1. A method for producing polycarbonate, comprising the steps of: a prepolymerization step of subjecting a polymerization raw material containing a dihydroxy compound, a diaryl carbonate, and at least one catalyst selected from the group consisting of alkali metals and alkaline earth metal compounds, to an ester exchange reaction in a polymerization vessel under reduced pressure conditions to obtain a molten prepolymer; a condensation polymerization step in which the molten prepolymer is subjected to a further transesterification reaction under reduced pressure in a polymerization vessel to obtain a polycarbonate; Including, The method for producing a polycarbonate, comprising carrying out the transesterification reaction in the prepolymerization step under conditions that satisfy the following formula (1): 1100 ≦ [-0.043 × A + 0.028 × B + 0.79] × C × D ≦ 22000 (1) (In formula (1), A is the acid dissociation constant (pKa) of the dihydroxy compound, provided that when two or more dihydroxy compounds are used, A is the weighted average of the acid dissociation constants (pKa) of the dihydroxy compounds; B is the amount of dihydroxy compound and diaryl carbonate fed per hour (ton / hour); C is the catalyst concentration (mass ppb) relative to the diaryl carbonate calculated from the mass equivalent of the metal element in the catalyst, and D is the viscosity (mPa·s) of the molten prepolymer after polymerizing the dihydroxy compound and the diaryl carbonate for 1 hour.

2. The method for producing a polycarbonate according to claim 1 , wherein A satisfies the following formula (2): 8 ≦ A ≦ 15 (2)

3. The method for producing a polycarbonate according to claim 1 , wherein B satisfies the following formula (3): 0.01≦B≦35 (3)

4. The method for producing a polycarbonate according to claim 1 , wherein C satisfies the following formula (4): 50≦C≦600 (4)

5. The method for producing a polycarbonate according to claim 1 , wherein D satisfies the following formula (5): 10≦D≦200 (5)

6. 2. The method for producing a polycarbonate according to claim 1, wherein the polymerization vessel in the prepolymerization step is a stirred polymerization vessel.

7. The condensation polymerization step is carried out using a guide contact flow-down type polymerization apparatus, The method for producing a polycarbonate according to any one of claims 1 to 6, wherein the guide contact flow-down type polymerization apparatus satisfies the following <Condition (1)> to <Condition (9)>. <Condition (1)> The evaporation zone has a liquid receiving port, a liquid supply zone for supplying liquid to a guide in the evaporation zone through a perforated plate, an evaporation zone in which a plurality of guides extending downward from the perforated plate are provided in a space surrounded by the perforated plate, a side casing and a bottom casing, a vacuum vent port provided in the evaporation zone, and a liquid discharge port provided at the bottom of the bottom casing. <Condition (2)> In the liquid supply zone, a flow path control component having a function of causing the liquid supplied from the liquid receiving port to flow from the periphery of the perforated plate in a direction toward the center of the perforated plate is disposed in the liquid supply zone. <Condition (3)> The internal cross-sectional area a (m 2 ) satisfies the following formula (I). 0.7≦a≦300 Formula (I) <Condition (4)> The internal cross-sectional area a (m 2 ) and the internal cross-sectional area b (m 2 ) satisfies the following formula (II). 20≦a / b ≦ 1000 Formula (II) <Condition (5)> The bottom casing constituting the bottom of the evaporation zone is connected to the upper side casing at an angle C degrees inside thereof, and the angle c degrees satisfies the following formula (III). 110≦c≦165 Formula (III) <Condition (6)> The length h (cm) of the guide satisfies formula (IV). 150≦h≦5000 Formula (IV) <Condition (7)> The total external surface area S (m 2 ) satisfies formula (V). 2 ≦ S ≦ 50000 Formula (V) <Condition (8)> The perforated plate 1m 2 Average number of holes per m 2 ) satisfies formula (VI). 50 ≦ N ≦ 3000 Formula (VI) <Condition (9)> The upper area T (m 2 ) and the total effective cross-sectional area Q (m 2 ) satisfies the following formula (VII). 50 ≦ T / Q ≦ 3000 Formula (VII)

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