JP5320071B2 - Industrial production of high-quality aromatic polycarbonate. - Google Patents

Abstract

The invention aims at providing a specific process by which a high-quality and high-performance aromatic polycarbonate which is little discolored and is excellent in mechanical properties can be stably produced from a cyclic carbonate and an aromatic dihydroxyl compound industrially on a large scale (e.g., in an amount of at least one ton per hour) over a long period (e.g., over a period of 1000 hours or longer, preferably 3000 hours or longer, still preferably 5000 hours or longer). The aim can be attained by a process for the production of an aromatic polycarbonate from a cyclic carbonate and an aromatic dihydroxyl compound which comprises the step (I) of preparing a dialkyl carbonate and a diol by using a reaction-distillation column having specific structure, the step (II) of preparing a diaryl carbonate by using two reaction-distillation columns having specific structure, the step (III) of purifying the diaryl carbonate to obtain a high-purity diaryl carbonate, the step (IV) of converting a molten prepolymer prepared from an aromatic dihydroxyl compound and the high-purity diaryl carbonate into an aromatic polycarbonate by using a guide-contact flowing down type polymerizer having specific structure, and the step (V) recycling an aromatic monohydroxyl compound formed as by-product to the step (II).

Description

  The present invention relates to an industrial process for producing an aromatic polycarbonate. More specifically, the present invention relates to a method for industrially producing a high-quality, high-performance aromatic polycarbonate having no mechanical coloring and excellent mechanical properties from a cyclic carbonate and an aromatic dihydroxy compound in a large amount industrially for a long period of time. About.

  Aromatic polycarbonate is widely used in many fields as engineering plastics having excellent heat resistance, impact resistance and transparency. Various studies have been conducted on the production method of this aromatic polycarbonate. Among them, aromatic dihydroxy compounds such as 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A) and phosgene are included. The interfacial polycondensation method has been industrialized. However, in this interfacial polycondensation method, toxic phosgene must be used, and methylene chloride, which is a problem for health and the environment, must be used in a large amount of 10 times or more per polycarbonate as a polymerization solvent. Equipment is corroded by hydrogen chloride, sodium chloride, and chlorine-containing compounds such as methylene chloride, separation of chlorine-based residual impurities such as sodium chloride and methylene chloride that adversely affect polymer properties, methylene chloride and unreacted There are many problems such as the need to treat a large amount of process wastewater containing bisphenol A and the like.

  On the other hand, as a method for producing an aromatic polycarbonate from an aromatic dihydroxy compound and diaryl carbonate, for example, a melting method in which bisphenol A and diphenyl carbonate are transesterified in a molten state and polymerization is performed while extracting by-product phenol is used. Known from. Since this transesterification reaction is an equilibrium reaction and the equilibrium constant is small, polymerization does not proceed unless phenol is efficiently extracted from the surface of the melt. Unlike the interfacial polycondensation method, the melting method has the advantage of not using a solvent. On the other hand, when the polymerization proceeds to some extent, the viscosity of the polymer rises rapidly, making it difficult to efficiently extract by-product phenol etc. Therefore, there is an essential problem based on the aromatic polycarbonate itself that the degree of polymerization cannot be substantially increased. That is, in the case of aromatic polycarbonate, unlike the case of melt polycondensation of other condensation polymers such as polyamide and polyester, even when the low molecular weight state, for example, the degree of polymerization (n) is about 15-20, the melt viscosity is It becomes extremely high, and surface renewal becomes very difficult with normal stirring. And extraction of phenol from a polymer surface does not occur substantially, and a polymer having a degree of polymerization necessary for a product (n = about 35-65) cannot be produced. This is well known in the art.

  Various polymerization apparatuses are known as a polymerization apparatus for producing an aromatic polycarbonate by a melting method. A method using a vertical stirring tank type polymerizer equipped with a stirrer is generally well known. However, the vertical stirred tank type polymerizer has the advantages of high volumetric efficiency and small size on a small scale, and can proceed with polymerization efficiently, but on an industrial scale, as described above, with the progress of polymerization. There is a problem that it is difficult to efficiently extract phenol as a by-product out of the system, and the polymerization rate becomes extremely low. Furthermore, a large-scale vertical stirring tank type polymerization apparatus usually has a larger liquid volume ratio to the evaporation area than a small scale, and a so-called liquid depth is large. For this reason, even if the degree of vacuum is increased in order to increase the polymerization degree, the lower part of the stirring tank has a liquid depth, so that the polymerization is performed at a higher pressure corresponding to the liquid depth than the upper space part. Phenol and the like are difficult to extract efficiently. Therefore, the large-scale vertical stirring tank type polymerization apparatus can be used only when producing a prepolymer. In order to achieve the required degree of polymerization, a polymerization vessel for further proceeding the polycondensation reaction from this prepolymer is essential.

  In order to solve this problem, various attempts have been made to efficiently extract phenol and the like from a polymer in a high viscosity state. Most of these devices relate to improvements in mechanical stirring. For example, a method using a screw-type polymerizer having a vent (see Patent Document 1), a method using a meshing twin-screw extruder (patent) Further, a method using a thin film evaporation type reactor such as a screw evaporator or a centrifugal thin film evaporator (see Patent Document 3) is described. Further, a centrifugal thin film type evaporator and a horizontal type 2 are described. The method (refer patent document 4) which uses a shaft-stirring type polymerization device in combination is specifically disclosed. All of these methods are based on the mechanical agitation, and thus have their own limitations, and have not yet solved this problem. In other words, since there is a limit to the mechanical stirring itself that can cope with the ultra-high melt viscosity, various problems relating to the ultra-high melt viscosity of the aromatic polycarbonate remain unsolvable. These methods attempt to solve the problem by raising the temperature and lowering the melt viscosity as much as possible.

  That is, it is these methods to perform polymerization while renewing the surface of the molten prepolymer by mechanical stirring under a high temperature and high vacuum near 300 ° C., but the melt viscosity is still very high at this temperature, The degree of surface renewal cannot be increased. Accordingly, the degree of polymerization of polycarbonate that can be produced by these methods is limited, and it is difficult to produce a high molecular weight grade product. Furthermore, in these methods, since the reaction is performed at a high temperature close to 300 ° C., the resulting polymer is likely to be colored and the physical properties are deteriorated. There are still many problems to be solved in order to stably produce high-quality polycarbonate for a long period of time, such as a tendency for deterioration of physical properties.

  The present inventors have developed these methods by developing a method using a guide contact flow type polymerization apparatus in which a molten prepolymer is polymerized while dropping by its own weight along a guide such as a wire without mechanical stirring. And found out that it can be completely solved. (For example, refer to Patent Documents 5 to 12.) However, in these methods, there is no disclosure or suggestion of a specific method relating to an industrial production method capable of producing an aromatic polycarbonate of 1 ton or more per hour. It was.

  Furthermore, in order to produce an aromatic polycarbonate by an ester exchange reaction on an industrial scale, it is necessary to obtain a large amount of high-purity diaryl carbonate on an industrial scale. Aromatic dihydroxy compounds, such as high purity bisphenol A, are produced in large quantities on an industrial scale and are easy to obtain, but obtaining high purity diaryl carbonate in large quantities on an industrial scale Impossible. It is therefore necessary to produce this.

  As a method for producing diaryl carbonate, a method of reacting an aromatic monohydroxy compound and phosgene has been known for a long time, and various studies have been made recently. However, in this method, in addition to the problem of using phosgene, the diaryl carbonate produced by this method contains chlorine impurities that are difficult to separate, and cannot be used as a raw material for aromatic polycarbonate as it is. This is because this chlorinated impurity significantly inhibits the polymerization reaction of the transesterification aromatic polycarbonate carried out in the presence of a very small amount of a basic catalyst. Can't progress. Therefore, in order to use as a raw material for the transesterification aromatic polycarbonate, it is necessary to perform a thorough and troublesome separation / purification process such as sufficient washing with dilute alkaline aqueous solution and warm water, oil-water separation, and distillation. There are many problems in implementing this method on an industrial scale economically commensurate, such as a decrease in yield due to hydrolysis loss and distillation loss in the purification process.

  On the other hand, a method for producing an aromatic carbonate by a transesterification reaction between a dialkyl carbonate and an aromatic monohydroxy compound is also known. However, these transesterification reactions are all equilibrium reactions, and the equilibrium is extremely biased toward the original system and the reaction rate is slow. It was very difficult to manufacture.

  Several proposals have been made to improve this, most of which relates to the development of catalysts to increase the reaction rate. Many metal compounds have been proposed as this type of transesterification catalyst. However, since catalyst development alone cannot solve the problem of unfavorable equilibrium, there are a large number of examination subjects including examination of reaction methods in order to obtain an industrial production method for mass production.

  On the other hand, attempts have been made to improve the yield of aromatic carbonates by devising the reaction system to shift the equilibrium to the production system as much as possible. For example, in the reaction of dimethyl carbonate and phenol, by-product methanol is distilled off together with the azeotropic agent by azeotropic distillation (see Patent Document 13), by-product methanol is adsorbed by molecular sieves. A removal method (see Patent Document 14) has been proposed. Also proposed is a method of performing distillation separation of unreacted raw materials that are evaporated at the same time while separating alcohols by-produced in the reaction from the reaction mixture by an apparatus provided with a distillation tower at the top of the reactor. (See Patent Document 15).

  However, these reaction systems are basically a batch system or a switching system. This is because the improvement of the reaction rate due to the development of the catalyst has a limit for these transesterification reactions, and the reaction rate is slow, so that the batch method was considered preferable to the continuous method. Among these, a continuous stirred tank reactor (CSTR) system in which a distillation column is provided at the top of the reactor as a continuous system has been proposed, but the reaction rate is slow and the gas-liquid interface of the reactor is reduced in liquid volume. On the other hand, there is a problem that the reaction rate cannot be increased because it is small. Therefore, it is difficult to achieve the objective of stably producing aromatic carbonates continuously in large quantities for a long period of time by these methods, and there are still many solutions to achieve an economically reasonable industrial implementation. Issues to be addressed remain.

  The present inventors continuously supply dialkyl carbonate and aromatic hydroxy compound to a multistage distillation column, continuously react in the column in the presence of a catalyst, and distill low-boiling components including alcohol as a by-product. In the reactive distillation method (see Patent Document 16), the component containing the alkylaryl carbonate produced is withdrawn from the bottom of the column, and the alkylaryl carbonate is continuously fed to the multistage distillation column to make the catalyst exist. A reactive distillation method in which a low-boiling component containing dialkyl carbonate by-produced is continuously extracted by distillation while continuously reacting in the column, and a component containing diaryl carbonate is extracted from the bottom of the column (see Patent Document 17). ), These reactions are carried out using two continuous multistage distillation towers, and dialkyl carbonate as a by-product is efficiently produced. Reactive distillation method for continuously producing diaryl carbonate while recycling (see Patent Document 18), dialkyl carbonate and aromatic hydroxy compound are continuously supplied to a multistage distillation column, and the liquid flowing down in the column is distilled After being extracted from the side outlet provided in the middle stage and / or the lowermost stage of the reactor, introduced into the reactor provided outside the distillation column and reacted, provided in the stage above the stage with the outlet The transesterification reaction is carried out in a continuous multistage distillation column such as a reactive distillation method (see Patent Document 19) in which the reaction is carried out both in the reactor and in the distillation column by being introduced into the circulation inlet. Has developed a reactive distillation method that simultaneously performs reaction and distillation separation, and has disclosed for the first time in the world that a reactive distillation method is useful for these transesterification reactions.

  These reactive distillation methods proposed by the present inventors are the first to make it possible to produce aromatic carbonates efficiently and continuously, and based on these disclosures, A method for producing diaryl carbonate from dialkyl carbonate using a continuous multistage distillation column has been proposed (see Patent Documents 20 to 26).

  Further, in the reactive distillation method, the present applicant reacted a high-boiling substance containing a catalyst component with an active substance as a method capable of stably producing a high-purity aromatic carbonate for a long time without requiring a large amount of catalyst. A method of separating the catalyst component and recycling the catalyst component (see Patent Document 27), or a method of maintaining the polyvalent aromatic hydroxy compound in the reaction system at a mass ratio of 2.0 or less with respect to the catalyst metal (patent) Reference 28) was proposed. Furthermore, the present inventors also have a method in which 70 to 99% by mass of phenol by-produced in the polymerization process is used as a raw material, and diphenyl carbonate is produced by a reactive distillation method and used as a polymerization raw material for aromatic polycarbonate. Proposed (see Patent Document 29).

However, all the prior literatures proposing the production of aromatic carbonates by these reactive distillation methods disclose specific methods and apparatuses that enable industrial scale mass production (for example, 1 ton per hour). There is no description that suggests them. For example, the height (H ₁ and H ₂ : cm), diameter (D ₁ and D ₂ : cm) of _two reactive distillation columns disclosed for the production of mainly diphenyl carbonate (DPC) from dimethyl carbonate and phenol Table 1 describes the number of stages (n ₁ and n ₂ ) and the amount of reaction raw material liquid introduced (Q ₁ and Q ₂ : kg / hr).

That is, the maximum of the two continuous multistage distillation columns used for carrying out this reaction by the reactive distillation method is disclosed in Patent Documents 27 and 28 by the present applicant. Thus, the maximum value of each condition in the continuous multistage distillation column disclosed for this reaction is as follows: H ₁ = 1200 cm, H ₂ = 600 cm, D ₁ = 20 cm, D ₂ = 25 cm, n ₁ = n ₂ = 50 (Only under this condition, see Patent Document 22), Q ₁ = 86 kg / hr, Q ₂ = 31 kg / hr, and the production amount of diphenyl carbonate is only about 6.7 kg / hr, not an industrial scale production amount. It was.

  The dialkyl carbonate used in the step (II) of the present invention needs to be produced on an industrial scale, and further needs to contain no halogen. As the aromatic polycarbonate raw material, the only method in which dialkyl carbonate is industrially produced in large quantities is based on the oxidative carbonylation method in which methanol is reacted with carbon monoxide and oxygen to produce dimethyl carbonate and water. is there. However, this oxidative carbonylation method (see Patent Document 30) needs to be reacted in a slurry state using a large amount of CuCl-HCl as a catalyst, and the reaction system and the separation / purification system are very corrosive. That is a problem. In addition, since carbon monoxide is easily oxidized to carbon dioxide in this method, there is a problem that the selectivity based on carbon monoxide is as low as about 80%.

  On the other hand, several methods for producing dialkyl carbonates and diols from the reaction of cyclic carbonates and aliphatic monohydric alcohols have been proposed. This reaction is a preferred method because dialkyl carbonate can be produced without using halogen. As the reaction method, four methods have been proposed. These four reaction systems are used in the most typical reaction examples in the production method of dimethyl carbonate and ethylene glycol from ethylene carbonate and methanol. These are (1) complete batch reaction system, (2) Batch reaction method using a reaction kettle provided with a distillation column at the top, (3) Liquid flow reaction method using a tubular reactor, (4) Reactive distillation method disclosed by the present inventors for the first time (see Patent Documents 31 to 39). ). However, each of these methods has the following problems.

  That is, in the case of (1) and (3), since the upper limit of the reaction rate of the cyclic carbonate is determined by the charged composition and temperature, the reaction cannot be completed completely and the reaction rate is low. In the case of (2), in order to increase the reaction rate of the cyclic carbonate, the dialkyl carbonate to be produced must be distilled off using an extremely large amount of an aliphatic monohydric alcohol, resulting in a long reaction time. I need. In the case of (4), it is possible to advance the reaction at a higher reaction rate than in (1), (2), and (3). However, the method (4) proposed so far is a method for producing a small amount of dialkyl carbonate and diol, or a short-term production method, and relates to a long-term stable production on an industrial scale. It was not a thing. That is, the object is to produce a dialkyl carbonate stably in a large amount (for example, 2 tons or more per hour) for a long period (for example, 1000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more). It was not achieved.

  For example, the height (H: cm), the diameter (D: cm), and the number of stages of the reactive distillation column in the examples disclosed for producing dimethyl carbonate (DMC) and ethylene glycol (EG) from ethylene carbonate and methanol Table 2 shows the maximum values for (n), the production amount P (kg / hr) of dimethyl carbonate, and the continuous production time T (hr).

  In Patent Document 38 (paragraph 0060), “This example employs a process flow similar to that of the preferred embodiment shown in FIG. 1 and is transesterified by a catalytic conversion reaction of ethylene carbonate and methanol to form dimethyl ester. It was made for the purpose of operating a commercial scale apparatus for producing carbonate and ethylene glycol. The numerical values described below in this example are sufficiently applicable to the operation of an actual apparatus. " As an example, it is described that 3750 kg / hr of dimethyl carbonate was specifically produced. Since this scale described in the examples corresponds to an annual output of 30,000 tons or more, when the patent document 38 was filed (April 9, 2002), the world's largest commercial plant was operated by this method. That's right. However, there is no such fact. Further, in the example of Patent Document 38, the production amount of dimethyl carbonate is described as being exactly the same as the theoretical calculation value, but the yield of ethylene glycol is about 85.6% and the selectivity is about 88. It is 4%, and it is difficult to say that high yield and high selectivity are achieved. A particularly low selectivity indicates that this method has a fatal defect as an industrial production method. (Note that Patent Document 38 was deemed to be dismissed on July 26, 2005 due to an unexamined request.)

  The reactive distillation method has many variations such as composition change due to reaction in the distillation column, composition change due to distillation, temperature change and pressure change in the column, and it is difficult to continue stable operation for a long time. This is often accompanied, especially when dealing with large quantities. In order to continue the mass production of dialkyl carbonates and diols by reactive distillation while maintaining high yield and high selectivity, it is necessary to devise reactive distillation equipment. . However, the description relating to long-term continuous stable production in the reactive distillation method proposed so far was only 400 hours of Patent Document 31.

Japanese Patent Publication No. 50-19600 (British Patent No. 1007302) Japanese Patent Publication No.52-36159 Japanese Patent Publication No. 53-5718 (U.S. Pat. No. 3,888,826) Japanese Patent Laid-Open No. 2-153923 Japanese Patent Laid-Open No. 8-225641 JP-A-8-225643 JP-A-8-325373 WO 97-22650 JP-A-10-81741 Japanese Patent Laid-Open No. 10-298279 WO 99/36457 WO 99/64492 JP 54-48732 A (West German Patent Publication No. 736063, US Pat. No. 4,252,737) JP 58-185536 A (US Pat. No. 4,104,464) JP 56-123948 A (US Pat. No. 4,182,726) JP-A-3-291257 JP-A-4-9358 JP-A-4-211038 (WO 91/09832, European Patent 0461274, US Pat. No. 5,210,268) JP-A-4-235951 Japanese Patent Laid-Open No. 6-157424 (European Patent No. 0582931, US Pat. No. 5,334,742) Japanese Patent Laid-Open No. 6-184058 (European Patent 0582930, US Pat. No. 5,344,954) Japanese Patent Laid-Open No. 9-40616 Japanese Patent Laid-Open No. 9-59225 JP-A-9-176094 WO 00/18720 (U.S. Pat. No. 6,093,482) JP 2001-64235 A WO 97/11049 (European Patent 0855384, US Pat. No. 5,872,275) Japanese Patent Application Laid-Open No. 11-92429 (European Patent No. 1016648, US Pat. No. 6,262,210) JP-A-9-255572 (European Patent No. 0892001, US Pat. No. 5,747,609) WO 03/016257 Japanese Patent Laid-Open No. 4-198141 JP-A-9-194435 WO99 / 64382 (European Patent No. 1086940, US Pat. No. 6,346,638) WO00 / 51954 (European Patent No. 1174406, US Pat. No. 6,479,689) JP-A-5-213830 (European Patent No. 0530615, US Pat. No. 5,213,212) JP-A-6-9507 (European Patent No. 0569812, US Patent No. 5359118) JP2003-119168A (WO03 / 006418) Japanese Patent Laid-Open No. 2003-300936 JP 2003-342209 A

  The problem to be solved by the present invention is that industrially large amounts (for example, 1 per hour) of high-quality and high-performance aromatic polycarbonates that are not colored and have excellent mechanical properties from cyclic carbonates and aromatic dihydroxy compounds. It is to provide a specific method capable of stably producing for a long period (for example, 1000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more) over a long period of time.

  The inventors of the present invention have reached the present invention as a result of repeated studies to find out a specific method capable of achieving the above-described problems.

That is, in the first aspect of the present invention,
1. An industrial production method for continuously producing a high-quality aromatic polycarbonate from a cyclic carbonate and an aromatic dihydroxy compound,
(I) Continuous multi-stage distillation column T in which a catalyst is present between cyclic carbonate and aliphatic monohydric alcohol
_The low boiling point reaction mixture containing dialkyl carbonate is continuously extracted in the form of a gas from the top of the tower, and is continuously fed into the column. Step (I) of continuously producing a dialkyl carbonate and a diol by a reactive distillation system in which liquid is continuously extracted from the lower part of the column,
(II) The dialkyl carbonate and the aromatic monohydroxy compound are used as raw materials, and the raw materials are continuously supplied into a first continuous multi-stage distillation column in which a catalyst is present, and the reaction and distillation are simultaneously performed in the first column. The first column low-boiling point reaction mixture containing the generated alcohols is continuously withdrawn from the upper portion of the first column in a gaseous state, and the first column high-boiling point reaction mixture containing the generated alkylaryl carbonates is removed from the lower portion of the first column. It is continuously extracted in a liquid state, and the first column high boiling point reaction mixture is continuously fed into the second continuous multistage distillation column in which the catalyst is present, and the reaction and distillation are simultaneously performed in the second column to produce. The second tower low boiling point reaction mixture containing dialkyl carbonates is continuously withdrawn from the upper part of the second column in the form of gas, and the second tower high boiling point reaction mixture containing the diaryl carbonates to be produced is liquid from the lower part of the second tower. Continuously withdrawn while by continuously feeding the second column low boiling point reaction mixture containing a dialkyl carbonate into the first continuous multi-stage distillation column, and step (II) of continuously producing a diaryl carbonate,
(III) purification step (III) for purifying the diaryl carbonate to obtain high-purity diaryl carbonate;
(IV) The aromatic dihydroxy compound is reacted with the high-purity diaryl carbonate to produce a molten prepolymer of an aromatic polycarbonate, and the molten prepolymer is allowed to flow along the surface of the guide, and the molten prepolymer is melted during the flow. A step (IV) of producing an aromatic polycarbonate using a guide contact flow type polymerizer for polymerizing a prepolymer;
(V) an aromatic monohydroxy compound recycling step (V) in which the aromatic monohydroxy compound by-produced in step (IV) is circulated to the diaryl carbonate production step (II);
Including
(A) The continuous multi-stage distillation column T ₀ has a cylindrical body having a length L ₀ (cm) and an inner diameter D ₀ (cm), and has an internal structure having an internal number n _0. A gas outlet with an inner diameter d ₀₁ (cm) at the top of the tower or near the top of the tower, a liquid outlet with an inner diameter d ₀₂ (cm) at the bottom of the tower or near the tower, and below the gas outlet. At the top of the tower and / or
Or one or more of the first inlet to the middle portion include those having one or more second inlet port A above the liquid withdrawal to the middle and / or bottom of the column, L ₀ , D ₀ , L ₀ / D
₀ , n ₀ , D ₀ / d ₀₁ , D ₀ / d ₀₂ satisfy the formulas (1) to (6),
2100 ≦ L ₀ ≦ 8000 Formula (1)
180 ≦ D ₀ ≦ 2000 Formula (2)
4 ≦ L ₀ / D ₀ ≦ 40 Formula (3)
10 ≦ n ₀ ≦ 120 Formula (4)
3 ≦ D ₀ / d ₀₁ ≦ 20 Formula (5)
5 ≦ D ₀ / d ₀₂ ≦ 30 Formula (6)
(B) The first continuous multi-stage distillation column has a cylindrical body having a length L ₁ (cm) and an inner diameter D ₁ (cm), and has an internal structure having an internal number n _1. A gas outlet with an inner diameter d ₁₁ (cm) at the top of the tower or near the top of the tower, a liquid outlet with an inner diameter d ₁₂ (cm) at the bottom of the tower or near the tower, and below the gas outlet. At the top of the tower and / or
Or one or more third inlet at an intermediate portion include those having one or more fourth inlet A above the liquid withdrawal to the middle and / or bottom of the tower, L ₁ , D ₁ , L ₁ / D
₁ , n ₁ , D ₁ / d ₁₁ , D ₁ / d ₁₂ satisfy formulas (7) to (12),
1500 ≦ L ₁ ≦ 8000 Formula (7)
100 ≦ D ₁ ≦ 2000 Formula (8)
2 ≦ L ₁ / D ₁ ≦ 40 Formula (9)
20 ≦ n ₁ ≦ 120 Formula (10)
5 ≦ D ₁ / d ₁₁ ≦ 30 Formula (11)
3 ≦ D ₁ / d ₁₂ ≦ 20 Formula (12)
(C) The second continuous multi-stage distillation column has a cylindrical body having a length L ₂ (cm) and an inner diameter D ₂ (cm), and has an internal structure having an internal number n _2. A gas outlet with an inner diameter of d ₂₁ (cm) at the top of the tower or near the top of the tower, a liquid outlet with an inner diameter of d ₂₂ (cm) at the bottom of the tower or near the tower, and below the gas outlet. At the top of the tower and / or
Or one or more fifth inlet at an intermediate portion include those having one or more inlets of the 6 A above the liquid withdrawal to the middle and / or bottom of the tower, L ₂ , D ₂ , L ₂ / D
₂ , n ₂ , D ₂ / d ₂₁ , D ₂ / d ₂₂ satisfy formulas (13) to (18),
1500 ≦ L ₂ ≦ 8000 Formula (13)
100 ≦ D ₂ ≦ 2000 (14)
2 ≦ L ₂ / D ₂ ≦ 40 Formula (15)
10 ≦ n ₂ ≦ 80 Formula (16)
2 ≦ D ₂ / d ₂₁ ≦ 15 Formula (17)
5 ≦ D ₂ / d ₂₂ ≦ 30 Formula (18)
(D) the guide contact flow type polymerizer,
(1) A molten prepolymer receiving port, a perforated plate, a molten prepolymer supply zone for supplying the molten prepolymer to the guide of the polymerization reaction zone through the perforated plate, the perforated plate, a side casing, and a tapered bottom casing A polymerization reaction zone in which a plurality of guides extending downward from the perforated plate are provided in a space surrounded by the porous plate, a vacuum vent port provided in the polymerization reaction zone, and an aromatic provided at the bottom of the tapered bottom casing A polycarbonate discharge port, and an aromatic polycarbonate discharge pump connected to the discharge port,
(2) The internal cross-sectional area A (m ² ) in the horizontal plane of the side casing of the polymerization reaction zone is
Which satisfies equation (19),
0.7 ≦ A ≦ 300 Formula (19)
(3) A (m ² ) and internal cross-sectional area B in the horizontal plane of the aromatic polycarbonate outlet
The ratio to (m ² ) satisfies equation (20),
20 ≦ A / B ≦ 1000 Formula (20)
(4) A tapered bottom casing constituting the bottom of the polymerization reaction zone is connected to the upper side casing at an angle C degree inside, and the angle C degree is expressed by the equation (2).
Satisfying 1),
120 ≦ C ≦ 165 Formula (21)
(5) The length h (cm) of the guide satisfies the formula (22),
150 ≦ h ≦ 5000 Formula (22)
(6) The external total surface area S (m ² ) of the entire guide satisfies the formula (23).
2 ≦ S ≦ 50000 Formula (23)
An industrial process for producing high-quality aromatic polycarbonate, characterized by
2. The method according to item 1 above, wherein the produced aromatic polycarbonate is 1 ton or more per hour,
3. The d ₀₁ and d _{02 of the} continuous multistage distillation column T ₀ used in the step (I) are represented by the formula (24)
The method according to item 1 or 2, wherein:
1 ≦ d ₀₁ / d ₀₂ ≦ 5 Formula (24)
4). L ₀ , D ₀ , L ₀ / D ₀ , n ₀ , D ₀ / d ₀₁ , D ₀ / d of the continuous multistage distillation column T _0
02 is 2300 ≦ L ₀ ≦ 6000, 200 ≦ D ₀ ≦ 1000, 5 ≦ L, respectively.
₀ / D ₀ ≦ 30, 30 ≦ n ₀ ≦ 100, 4 ≦ D ₀ / d ₀₁ ≦ 15, 7 ≦ D ₀ / d _0
2 ≦ 25, The method according to any one of the preceding items 1 to 3,
5. L ₀ , D ₀ , L ₀ / D ₀ , n ₀ , D ₀ / d ₀₁ , D ₀ / d of the continuous multistage distillation column T _0
02 is 2500 ≦ L ₀ ≦ 5000, 210 ≦ D ₀ ≦ 800, 7 ≦ L _{0, respectively.}
/ D ₀ ≦ 20, 40 ≦ n ₀ ≦ 90, 5 ≦ D ₀ / d ₀₁ ≦ 13, 9 ≦ D ₀ / d ₀₂ ≦
The method according to any one of the preceding items 1 to 4, wherein the method is 20,
6). The method according to any one of the preceding items 1 to 5, wherein the continuous multistage distillation column T ₀ is a distillation column having a tray and / or a packing as the internal,
7). The method according to item 6 above, wherein the continuous multistage distillation column T ₀ is a plate type distillation column having a tray as the internal,
8). 8. The method according to item 6 or 7 above, wherein the tray of the continuous multistage distillation column T ₀ is a perforated plate tray having a perforated plate portion and a downcomer portion.
9. The perforated plate tray of the continuous multi-stage distillation column T ₀ is 100 to 1 per 1 m ^{2 of the} perforated plate area.
9. The method according to item 8 above, which has 1000 holes,
10. The cross-sectional area per hole of the perforated plate tray of the continuous multistage distillation column T ₀ is 0.5 to 5c.
10. The method according to item 8 or 9 above, wherein m ²
11. Any one of the items 8 to 10 above, wherein the aperture ratio of the perforated plate tray of the continuous multi-stage distillation column T ₀ (ratio of the total hole cross-sectional area to the area of the perforated plate portion) is 1.5 to 15%. Or the method according to claim 1.
12 The first continuous multi-stage distillation column used in step (II) and the first continuous multi-stage distillation column d ₁
The method according to any one of the preceding items 1 to 11, wherein ₁ and d ₁₂ satisfy formula (25), and d ₂₁ and d ₂₂ satisfy formula (26),
1 ≦ d ₁₂ / d ₁₁ ≦ 5 Formula (25)
1 ≦ d ₂₁ / d ₂₂ ≦ 6 Formula (26)
13. L ₁ , D ₁ , L ₁ / D ₁ , n of the first continuous multistage distillation column used in the step (II)
₁ , D ₁ / d ₁₁ , D ₁ / d ₁₂ are respectively 2000 ≦ L ₁ ≦ 6000, 150 ≦
D ₁ ≦ 1000, 3 ≦ L ₁ / D ₁ ≦ 30, 30 ≦ n ₁ ≦ 100, 8 ≦ D ₁ / d ₁₁
≦ 25, 5 ≦ D ₁ / d ₁₂ ≦ 18, and L ₂ , D ₂ , L ₂ / D ₂ , n ₂ , D ₂ / d ₂₁ , D ₂ / d _{22 of the} second continuous multistage distillation column.
Are 2000 ≦ L ₂ ≦ 6000, 150 ≦ D ₂ ≦ 1000, 3 ≦ L ₂ / D, respectively.
₂ ≦ 30, 15 ≦ n ₂ ≦ 60, 2.5 ≦ D ₂ / d ₂₁ ≦ 12, 7 ≦ D ₂ / d ₂₂ ≦
25. The method according to any one of the preceding items 1 to 12, wherein
14 L ₁ , D ₁ , L ₁ / D ₁ , n ₁ , D ₁ / d ₁₁ , D ₁ / D of the first continuous multistage distillation column
d ₁₂ is 2500 ≦ L ₁ ≦ 5000, 200 ≦ D ₁ ≦ 800, 5 ≦ L _{1, respectively.}
/ D ₁ ≦ 15, 40 ≦ n ₁ ≦ 90, 10 ≦ D ₁ / d ₁₁ ≦ 25, 7 ≦ D ₁ / d ₁₂
≦ 15, and L ₂ , D ₂ , L ₂ / D ₂ , n ₂ , D ₂ / d of the second continuous multistage distillation column
₂₁ and D ₂ / d ₂₂ are 2500 ≦ L ₂ ≦ 5000 and 200 ≦ D ₂ ≦ 800, respectively.
5 ≦ L ₂ / D ₂ ≦ 15, 20 ≦ n ₂ ≦ 50, 3 ≦ D ₂ / d ₂₁ ≦ 10, 9 ≦ D
₂ / d ₂₂ ≦ 20, The method according to any one of the preceding items 1 to 13,
15. 1 to 14 above, wherein the first continuous multistage distillation column and the second continuous multistage distillation column are distillation columns each having a tray and / or a packing as the internal.
The method according to any one of
16. The first continuous multistage distillation column is a tray type distillation column having a tray as the internal, and the second continuous multistage distillation column is a distillation column having both a packing and a tray as the internal. The method according to item 15 above, characterized by:
17. 15 or 16 above, wherein each of the trays of the first continuous multistage distillation column and the second continuous multistage distillation column is a perforated plate tray having a perforated plate portion and a downcomer portion.
Described method,
18. 18. The paragraph 17 above, wherein the perforated plate trays of the first continuous multistage distillation column and the second continuous multistage distillation column have 100 to 1000 holes per 1 m ² area of the perforated plate portion. Method,
19. 19. The method according to item 17 or 18, wherein the first continuous multi-stage distillation column and the second continuous multi-stage distillation column have a cross-sectional area per hole of the perforated plate tray of 0.5 to ⁵ cm ² .
20. The method according to item 15 or 16, wherein the second continuous multi-stage distillation column is a distillation column having a packing at the top and a tray at the bottom as the internal,
21. 21. The method according to any one of the items 15 to 20, wherein the packing of the internal of the second continuous multistage distillation column is one or two or more regular packings.
22. 21. The item 21 above, wherein the regular packing of the second continuous multistage distillation column is at least one selected from melapack, gempack, technopack, flexipack, sulzer packing, good roll packing, and glitch grid. Described method,
23. The method according to any one of claims 1 to 22, wherein the diaryl carbonate purification step (III) is distillation.
24. In the guided contact flow type polymerization reactor used in the step (IV), the side casing of the polymerization reaction zone has a cylindrical shape with an inner diameter D (cm) and a length L (cm), and the bottom casing connected to the lower part thereof The casing has a tapered shape, and the lowermost discharge port of the tapered bottom casing has a cylindrical shape with an inner diameter d (cm), and D, L, d are represented by the equations (27), (28), (2
9) and (30) are satisfied,
100 ≦ D ≦ 1800 Formula (27)
5 ≦ D / d ≦ 50 Formula (28)
0.5 ≦ L / D ≦ 30 Formula (29)
h-20 <= L <= h + 300 Formula (30)
24. The method according to any one of items 1 to 23 above,
25. The h of the guide satisfies the formula (31).
400 <h ≦ 2500 Formula (31)
25. The method according to any one of items 1 to 24 above,
26. One of the guides is a cylindrical shape having an outer diameter r (cm) or a pipe shape in which molten prepolymer is prevented from entering inside, and r 1 satisfies the formula (32).
0.1 ≦ r ≦ 1 Formula (32)
26. The method according to any one of items 1 to 25 above,
27. 27. The method according to any one of claims 1 to 26, wherein in step (IV), polymerization is carried out by connecting two or more guide contact flow type polymerization reactors.
28. 28. The two or more guide contact flow type polymerization reactors according to claim 27, wherein the guide contact flow type first reactor is the first one.
In the method of increasing the degree of polymerization in this order, a polymerization vessel and a guide contact flow-down type second polymerization vessel, the total external surface area S1 (m ² ) of the entire guide of the first polymerization vessel and The total external surface area S2 (m ² ) of the entire guide of the second polymerization vessel satisfies the formula (33).
1 ≦ S1 / S2 ≦ 20 Formula (33)
28. The method according to item 27 above,
I will provide a.

In the second aspect of the present invention,
29 . The content of the alkali metal and / or alkaline earth metal compound, in terms of these metal elements are 0.1～0.01Ppm, and high-quality halogen content, Ru der below 1ppb 29. The method according to any one of items 1 to 28 above, which comprises producing an aromatic polycarbonate.
30 . An aromatic polycarbonate partially branched from the main chain via a hetero bond such as an ester bond or an ether bond, and the content of the hetero bond is 0.05-0. the method according to any one of the above 1 to 29, characterized in that the production of 5 mol% der Ru quality aromatic polycarbonate,
I will provide a.

  By carrying out the method of the present invention, a high-quality, high-performance aromatic polycarbonate having no coloration and excellent mechanical properties is obtained from a cyclic carbonate and an aromatic dihydroxy compound at a high polymerization rate of 1 ton or more per hour. It has been found that it can be produced on an industrial scale. In addition, it has also been found that high-quality aromatic polycarbonate can be stably produced with little variation in molecular weight and for a long period of time, for example, 2000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more. Therefore, the present invention is an extremely effective method as an industrial production method for high-quality aromatic polycarbonate.

Hereinafter, the present invention will be specifically described.
In the present invention, first, step (I) for continuously producing a dialkyl carbonate and a diol on an industrial scale from a cyclic carbonate and an aliphatic monohydric alcohol is performed. The reaction in step (I) is a reversible transesterification reaction represented by the following formula.

(Wherein R ¹ represents a divalent group — (CH ₂ ) _k — (k is an integer of 2 to 6), and one or more hydrogens thereof are substituted by an alkyl group or aryl group having 1 to 10 carbon atoms. R ² represents a monovalent aliphatic group having 1 to 12 carbon atoms, and one or more hydrogen atoms may be substituted with an alkyl group or aryl group having 1 to 10 carbon atoms. Good.)

  As such a cyclic carbonate, for example, alkylene carbonates such as ethylene carbonate and propylene carbonate, 1,3-dioxacyclohex-2-one, 1,3-dioxacyclohept-2-one and the like are preferable. Of these, ethylene carbonate and propylene carbonate are more preferably used from the viewpoint of availability, and ethylene carbonate is particularly preferably used.

  As the aliphatic monohydric alcohols, those having a boiling point lower than that of the generated diols are used. Therefore, although it may vary depending on the type of cyclic carbonate used, for example, methanol, ethanol, propanol (each isomer), allyl alcohol, butanol (each isomer), 3-buten-1-ol, amyl alcohol (each isomer) ), Hexyl alcohol (each isomer), heptyl alcohol (each isomer), octyl alcohol (each isomer), nonyl alcohol (each isomer), decyl alcohol (each isomer), undecyl alcohol (each isomer) ), Dodecyl alcohol (each isomer), cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol, methylcyclopentanol (each isomer), ethylcyclopentanol (each isomer), methylcyclohexanol (each isomer) Body), ethylcyclohexanol (each ), Dimethylcyclohexanol (each isomer), diethylcyclohexanol (each isomer), phenylcyclohexanol (each isomer), benzyl alcohol, phenethyl alcohol (each isomer), phenylpropanol (each isomer), etc. Further, in these aliphatic monohydric alcohols, they may be substituted with a substituent such as halogen, lower alkoxy group, cyano group, alkoxycarbonyl group, aryloxycarbonyl group, acyloxy group, nitro group.

  Among such aliphatic monohydric alcohols, alcohols having 1 to 6 carbon atoms are preferably used, and more preferably methanol, ethanol, propanol (each isomer), butanol (each isomer). These are alcohols having 1 to 4 carbon atoms. When ethylene carbonate or propylene carbonate is used as the cyclic carbonate, methanol and ethanol are preferable, and methanol is particularly preferable.

  In carrying out the reactive distillation in step (I), any method may be used for allowing the catalyst to be present in the reactive distillation column. For example, a homogeneous catalyst that dissolves in the reaction solution under the reaction conditions may be used. In this case, the catalyst can be present in the liquid phase in the reactive distillation column by continuously supplying the catalyst into the reactive distillation column, or the heterogeneous catalyst that does not dissolve in the reaction solution under the reaction conditions. In this case, by disposing a solid catalyst in the reactive distillation column, the catalyst can be present in the reaction system, or a method using these in combination.

  When the homogeneous catalyst is continuously supplied into the reactive distillation column, it may be supplied simultaneously with the cyclic carbonate and / or the aliphatic monohydric alcohol, or may be supplied at a position different from the raw material. Since the reaction actually proceeds in the distillation column is a region below the catalyst supply position, it is preferable to supply the catalyst to a region between the column top and the raw material supply position. And the stage in which this catalyst exists needs to be 5 steps or more, Preferably it is 7 steps or more, More preferably, it is 10 steps or more.

  When a heterogeneous solid catalyst is used, the number of stages in which the catalyst exists needs to be 5 or more, preferably 7 or more, and more preferably 10 or more. A solid catalyst that also has an effect as a packing for a distillation column can be used.

As a catalyst used in the step (I), for example,
Alkali metals and alkaline earth metals such as lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium;
Basic compounds such as alkali metal and alkaline earth metal hydrides, hydroxides, alkoxides, aryloxides, amidides;
Basic compounds such as alkali metal and alkaline earth metal carbonates, bicarbonates, organic acid salts;
Tertiary amines such as triethylamine, tributylamine, trihexylamine, benzyldiethylamine;
N-alkylpyrrole, N-alkylindole, oxazole, N-alkylimidazole, N-alkylpyrazole, oxadiazole, pyridine, alkylpyridine, quinoline, alkylquinoline, isoquinoline, alkylisoquinoline, acridine, alkylacridine, phenanthroline, alkylphenanthroline Nitrogen-containing heteroaromatic compounds such as, pyrimidine, alkylpyrimidine, pyrazine, alkylpyrazine, triazine, alkyltriazine;
Cyclic amidines such as diazabicycloundecene (DBU) and diazabicyclononene (DBN);
Thallium compounds such as thallium oxide, thallium halide, thallium hydroxide, thallium carbonate, thallium nitrate, thallium sulfate, thallium organic acid salts;
Tin compounds such as tributylmethoxytin, tributylethoxytin, dibutyldimethoxytin, diethyldiethoxytin, dibutyldiethoxytin, dibutylphenoxytin, diphenylmethoxytin, dibutyltin acetate, tributyltin chloride, tin 2-ethylhexanoate;
Zinc compounds such as dimethoxyzinc, diethoxyzinc, ethylenedioxyzinc and dibutoxyzinc;
Aluminum compounds such as aluminum trimethoxide, aluminum triisopropoxide, aluminum tributoxide;
Titanium compounds such as tetramethoxy titanium, tetraethoxy titanium, tetrabutoxy titanium, dichlorodimethoxy titanium, tetraisopropoxy titanium, titanium acetate, titanium acetylacetonate;
Phosphorus compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, triphenylphosphine, tributylmethylphosphonium halide, trioctylbutylphosphonium halide, triphenylmethylphosphonium halide;
Zirconium compounds such as zirconium halide, zirconium acetylacetonate, zirconium alkoxide, zirconium acetate;
Lead and lead-containing compounds, for example, lead oxides such as PbO, PbO ₂ and Pb ₃ O ₄ ; lead sulfides such as PbS, Pb ₂ S ₃ and PbS ₂ ; Pb (OH) ₂ and Pb ₃ O ₂ Lead hydroxides such as (OH) ₂ , Pb ₂ [PbO ₂ (OH) ₂ ], Pb ₂ O (OH) ₂ ; Ninamari acids such as Na ₂ PbO ₂ , K ₂ PbO ₂ , NaHPbO ₂ , KHPbO ₂ Salts; lead salts such as Na ₂ PbO ₃ , Na ₂ H ₂ PbO ₄ , K ₂ PbO ₃ , K ₂ [Pb (OH) ₆ ], K ₄ PbO ₄ , Ca ₂ PbO ₄ , CaPbO ₃ ; PbCO ₃ , 2PbCO ₃ · Pb _(OH) carbonates of lead, such as ₂ and their basic _{salts; Pb (OCH 3) 2,} (CH 3 O) Pb (OPh), alkoxy lead such as Pb _{(OPh) 2,} aryloxy _{S; Pb (OCOCH 3) 2,} Pb (OCOCH 3) 4, Pb (OCOCH 3) 2 · PbO · 3H 2 lead salt of an organic acid and a carbonate or basic salts such as _O; Bu ₄ Pb, Ph 4 Organic lead compounds such as Pb, Bu ₃ PbCl, Ph ₃ PbBr, Ph ₃ Pb (or Ph ₆ Pb ₂ ), Bu ₃ PbOH, Ph ₂ PbO (Bu represents a butyl group, Ph represents a phenyl group); Pb— Lead alloys such as Na, Pb—Ca, Pb—Ba, Pb—Sn, Pb—Sb;
Lead minerals such as hohenite, seneene ore, and hydrates of these lead compounds;
Can be mentioned.

  These compounds can be used as homogeneous catalysts when they are dissolved in reaction raw materials, reaction mixtures, reaction by-products and the like, and can be used as solid catalysts when they are not dissolved. Furthermore, it is also preferable to use a mixture obtained by dissolving these compounds in advance using a reaction raw material, a reaction mixture, a reaction byproduct or the like, or using a mixture obtained by reacting them as a homogeneous catalyst.

  Furthermore, an anion exchange resin having a tertiary amino group, an ion exchange resin having an amide group, an ion exchange resin having at least one exchange group of a sulfonic acid group, a carboxylic acid group and a phosphoric acid group, a quaternary ammonium group Ion exchangers such as solid strongly basic anion exchangers having as an exchange group; silica, silica-alumina, silica-magnesia, aluminosilicate, gallium silicate, various zeolites, various metal exchanged zeolites, ammonium exchanged zeolites, etc. Solid inorganic compounds are used as catalysts.

  As the solid catalyst, a solid strong anion exchanger having a quaternary ammonium group as an exchange group is particularly preferably used. Examples of such a solid catalyst include a strong quaternary ammonium group having an exchange group as a strong catalyst. Examples include basic anion exchange resins, cellulose strongly basic anion exchangers having quaternary ammonium groups as exchange groups, and inorganic carrier-supporting strong basic anion exchangers having quaternary ammonium groups as exchange groups. As the strongly basic anion exchange resin having a quaternary ammonium group as an exchange group, for example, a styrene strong basic anion exchange resin is preferably used. Styrenic strongly basic anion exchange resins are strongly basic anion exchange resins having a copolymer of styrene and divinylbenzene as a base and quaternary ammonium (type I or type II) as an exchange group. It is schematically shown by the formula.

In the formula, X represents an anion, and usually X is F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , HCO ₃ ⁻ , CO ₃ ²⁻ , CH ₃ CO ₂ ⁻ , HCO ₂ ⁻ , IO ₃ ⁻ , At least one anion selected from BrO ₃ ⁻ and ClO ₃ ^— is used, and preferably at least one anion selected from Cl ⁻ , Br ⁻ , HCO ₃ ⁻ and CO ₃ ²⁻ is used. used. As the structure of the resin matrix, either a gel type or a macroreticular type (MR type) can be used, but the MR type is particularly preferable because of high resistance to organic solvents.

As a cellulose strong basic anion exchanger having a quaternary ammonium group as an exchange group, for example, —OCH ₂ CH ₂ NR ₃ X obtained by trialkylaminoethylation of part or all of —OH groups of cellulose is used. And cellulose having an exchange group. However, R represents an alkyl group, and methyl, ethyl, propyl, butyl, etc. are usually used, and methyl and ethyl are preferably used. X represents an anion as described above.

An inorganic carrier-supporting strong basic anion exchanger having a quaternary ammonium group as an exchange group is a quaternary ammonium group —O (CH ₂₎ by modifying part or all of the surface hydroxyl group —OH of the inorganic carrier. ) _N NR ₃ X means introduced. However, R and X are as described above. n is usually an integer of 1 to 6, preferably n = 2. As the inorganic carrier, silica, alumina, silica alumina, titania, zeolite and the like can be used, preferably silica, alumina and silica alumina are used, and silica is particularly preferably used. Any method can be used as a method for modifying the surface hydroxyl group of the inorganic carrier.

  A commercially available solid strong anion exchanger having a quaternary ammonium group as an exchange group can also be used. In that case, it can also be used as a transesterification catalyst after previously performing ion exchange with a desired anionic species as a pretreatment.

  Also, a solid catalyst comprising a macroreticular and gel-type organic polymer to which a heterocyclic group containing at least one nitrogen atom is bonded, or an inorganic support to which a heterocyclic group containing at least one nitrogen atom is bonded Is also preferably used as a transesterification catalyst. Further, a solid catalyst in which part or all of these nitrogen-containing heterocyclic groups are quaternized is also used. A solid catalyst such as an ion exchanger can also function as a packing.

  The amount of catalyst used in step (I) varies depending on the type of catalyst used, but is a feedstock when continuously supplying a homogeneous catalyst that dissolves in the reaction solution under the reaction conditions. Expressed as a ratio to the total mass of the cyclic carbonate and the aliphatic monohydric alcohol, it is usually used in an amount of 0.0001 to 50% by mass, preferably 0.005 to 20% by mass, more preferably 0.01 to 10% by mass. . When a solid catalyst is used in the distillation column, it is used in an amount of 0.01 to 75% by volume, preferably 0.05 to 60% by volume, more preferably based on the empty volume of the distillation column. A catalyst amount of 0.1 to 60% by volume is preferably used.

There is no particular limitation on the method of continuously supplying the cyclic carbonate and the aliphatic monohydric alcohol as raw materials to the continuous multistage distillation column T ₀ which is the reactive distillation column in the step (I), and these are not particularly limited. Any method may be used as long as it can be brought into contact with the catalyst in an area of at least 5 stages, preferably 7 stages or more, more preferably 10 stages or more. That is, the cyclic carbonate and the aliphatic monohydric alcohol can be continuously supplied from the necessary number of inlets to the stage satisfying the above-mentioned conditions of the continuous multistage distillation column. Further, the cyclic carbonate and the aliphatic monohydric alcohol may be introduced into the same stage of the distillation column, or may be introduced into different stages.

The cyclic carbonate and aliphatic monohydric alcohol as raw materials are continuously supplied to the continuous multi-stage distillation column T ₀ as a liquid, a gas or a mixture of a liquid and a gas. In addition to supplying the raw material to the distillation column in this way, it is also preferable to supply a gaseous raw material intermittently or continuously from the lower part of the distillation column. Further, cyclic carbonate is continuously supplied to the distillation column in a liquid or gas-liquid mixed state to the upper stage from the stage where the catalyst exists, and the aliphatic monohydric alcohol is gaseous and / or lower to the lower part of the distillation tower. Alternatively, a liquid continuous supply method is also a preferable method. In this case, it does not matter if an aliphatic monohydric alcohol is contained in the cyclic carbonate.

  In step (I), the feedstock may contain dialkyl carbonate and / or diol as the product. The content of the dialkyl carbonate is usually 0 to 40% by mass, preferably 0 to 30% by mass, and more preferably 0 to 30% by mass, based on the dialkyl carbonate expressed by mass% of the dialkyl carbonate in the aliphatic monohydric alcohol / dialkyl carbonate mixture. It is 20 mass%, and the diol is represented by mass% in the cyclic carbonate / diol mixture, and is usually 0 to 10 mass%, preferably 0 to 7 mass%, more preferably 0 to 5 mass%.

  When the reaction of step (I) is carried out industrially, in addition to the cyclic carbonate and / or aliphatic monohydric alcohol newly introduced into the reaction system, the cyclic carbonate recovered in this step or / and other steps It is preferable that a substance mainly composed of an aliphatic monohydric alcohol can be used as these raw materials. The present invention makes this possible and is an excellent feature of the present invention. The other step includes, for example, a step (II) for producing diaryl carbonate from a dialkyl carbonate and an aromatic monohydroxy compound. In this step (II), an aliphatic monohydric alcohol is by-produced and recovered. The recovered by-product aliphatic monohydric alcohol usually contains a dialkyl carbonate, an aromatic monohydroxy compound, an alkylaryl ether, etc., and may contain a small amount of an alkylaryl carbonate, a diaryl carbonate, etc. . The by-product aliphatic monohydric alcohol can be used as it is as the raw material of step (I), or after the content of the substance having a boiling point higher than that of the aliphatic monohydric alcohol is reduced by distillation or the like, It can also be used as a raw material.

  Moreover, since the preferable cyclic carbonate used by process (I) is manufactured by reaction of alkylene oxides, such as ethylene oxide, propylene oxide, styrene oxide, and a carbon dioxide, the cyclic | annular form which contains these compounds etc. in small quantities. Carbonate can also be used as a raw material for the step (I).

  In the step (I), the amount ratio of the cyclic carbonate to be supplied to the reactive distillation column and the aliphatic monohydric alcohol varies depending on the type and amount of the transesterification catalyst and the reaction conditions. On the other hand, aliphatic monohydric alcohols can be supplied in a molar ratio of 0.01 to 1000 times. In order to increase the reaction rate of the cyclic carbonate, it is preferable to supply the aliphatic monohydric alcohol in an excess amount of 2 moles or more, but if it is used too much, it is necessary to enlarge the apparatus. In this sense, the molar ratio of the aliphatic monohydric alcohol to the cyclic carbonate is preferably 2 to 20, more preferably 3 to 15, and still more preferably 5 to 12. If a large amount of unreacted cyclic carbonate remains, it reacts with the product diols to produce by-products such as dimers and trimers. It is preferable to reduce the residual amount of cyclic carbonate as much as possible. In the method of the present invention, even when the molar ratio is 10 or less, the reaction rate of the cyclic carbonate can be 97% or more, preferably 98% or more, more preferably 99% or more. This is also one of the features of the present invention.

  In step (I), preferably about 0.4 tons or more of dialkyl carbonate per hour is continuously produced. For this purpose, the minimum amount of cyclic carbonate to be continuously supplied is the fragrance to be produced. The amount is usually 0.44 P ton / hr, preferably 0.42 P ton / hr, more preferably 0.4 P ton / hr with respect to the amount of the group polycarbonate (P ton / hr). In a more preferable case, it can be less than 0.39 P ton / hr.

The continuous multi-stage distillation column T ₀ used in the step (I) is an internal column having a cylindrical body having a length L ₀ (cm) and an inner diameter D ₀ (cm) and having a number n ₀ inside. A gas outlet with an inner diameter d ₀₁ (cm) at the top of the tower or near the top of the tower, and a liquid outlet with an inner diameter d ₀₂ (cm) at the bottom of the tower or near the tower, the gas outlet One or more first inlets below the mouth and in the upper part and / or middle part of the tower, and one or more second inlets above the liquid outlet and in the middle part and / or lower part of the tower Introducing port, L ₀ , D ₀ , L ₀ / D ₀ , n ₀ , D ₀ / d ₀₁ , D ₀ / d ₀₂ satisfy the formulas (1) to (6), respectively It is necessary to be.
2100 ≦ L ₀ ≦ 8000 Formula (1)
180 ≦ D ₀ ≦ 2000 Formula (2)
4 ≦ L ₀ / D ₀ ≦ 40 Formula (3)
10 ≦ n ₀ ≦ 120 Formula (4)
3 ≦ D ₀ / d ₀₁ ≦ 20 Formula (5)
5 ≦ D ₀ / d ₀₂ ≦ 30 Formula (6)

As used herein, the term “top of the tower or near the top of the tower” means a portion from the top of the tower down to about 0.25 L ₀ , and the term “bottom of the tower or near the bottom of the tower” means a portion from the bottom up to approximately 0.25 L ₀ upwards. (In the first and second continuous multistage distillation columns, it is 0.25L ₁ and 0.25L ₂ respectively.)

By using a continuous multistage distillation column T ₀ that simultaneously satisfies the formulas (1), (2), (3), (4), (5) and (6), the cyclic carbonate and the aliphatic monohydric alcohol can be used. On an industrial scale, preferably 0.4 tons or more of dialkyl carbonate per hour and / or preferably 0.26 tons or more of diols per hour, with high reactivity, high selectivity and high productivity, For example, it has been found that it can be stably produced for a long period of time of 1000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more. The reason why the production of dialkyl carbonates and diols on an industrial scale having such excellent effects has become possible by carrying out the step (I) is not clear, but the formulas (1) to (6) This is presumed to be due to the combined effect produced when these conditions are combined. In addition, the preferable range of each factor is shown below.

When L ₀ (cm) is smaller than 2100, the reaction rate decreases, so that the target production amount cannot be achieved, and in order to reduce the facility cost while securing the reaction rate that can achieve the target production amount, L ₀ Must be 8000 or less. A more preferable range of L ₀ (cm) is 2300 ≦ L ₀ ≦ 6000, and further preferably 2500 ≦ L ₀ ≦ 5000.
If D ₀ (cm) is smaller than 180, the target production amount cannot be achieved, and in order to reduce the facility cost while achieving the target production amount, it is necessary to set D ₀ to 2000 or less. . A more preferable range of D ₀ (cm) is 200 ≦ D ₀ ≦ 1000, and further preferably 210 ≦ D ₀ ≦ 800.

When L ₀ / D ₀ is less than 4 or greater than 40, stable operation becomes difficult. Particularly when L ₀ / D ₀ is greater than 40, the pressure difference between the top and bottom of the tower becomes too large, so that long-term stable operation becomes difficult. Since the temperature at the bottom of the column must be increased, side reactions are likely to occur and the selectivity is lowered. A more preferable range of L ₀ / D ₀ is 5 ≦ L ₀ / D ₀ ≦ 30, and further preferably 7 ≦ L ₀ / D ₀ ≦ 20.

If n ₀ is less than 10, the reaction rate decreases, so the target production amount cannot be achieved, and in order to reduce the equipment cost while ensuring the reaction rate that can achieve the target production amount, n _{0 is set} to 120 or less. It is necessary to. Furthermore, if n ₀ is greater than 120, the pressure difference between the top and bottom of the column becomes too large, which not only makes long-term stable operation difficult, but also raises the temperature at the bottom of the column, causing side reactions. It becomes easier and the selectivity is lowered. A more preferable range of n ₀ is 30 ≦ n ₀ ≦ 100, and further preferably 40 ≦ n ₀ ≦ 90.

If D ₀ / d ₀₁ is less than 3, not only will the equipment cost be high, but a large amount of gas components will be easily discharged out of the system, so that stable operation becomes difficult. Not only makes it difficult to achieve stable operation, but also reduces the reaction rate. A more preferable range of D ₀ / d ₀₁ is 4 ≦ D ₀ / d ₀₁ ≦ 15, and further preferably 5 ≦ D ₀ / d ₀₁ ≦ 13.

If D ₀ / d ₀₂ is smaller than 5, not only the equipment cost becomes high, but also the amount of liquid withdrawn becomes relatively large and stable operation becomes difficult, and if it is larger than 30, the flow velocity at the liquid withdrawing port and piping becomes abrupt. It becomes faster and more susceptible to erosion, leading to equipment corrosion. A more preferable range of D ₀ / d ₀₂ is 7 ≦ D ₀ / d ₀₂ ≦ 25, and further preferably 9 ≦ D ₀ / d ₀₂ ≦ 20.

Furthermore, it was found that the d ₀₁ and the d _{02 of the} continuous multistage distillation column T ₀ used in the step (I) satisfy the formula (24), which is more preferable.
1 ≦ d ₀₁ / d ₀₂ ≦ 5 Formula (24)

  The long-term stable operation in the step (I) is 1000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more, and there is no flooding or pipe clogging or erosion, and the operation is performed in a steady state based on operation conditions. This means that a predetermined amount of dialkyl carbonate and diol are produced while maintaining a high reaction rate, high selectivity, and high productivity.

  The selectivity of the dialkyl carbonate and diol in the step (I) is based on the reacted cyclic carbonate, and is usually a high selectivity of 95% or more in the present invention, preferably 97% or more, more preferably A high selectivity of 99% or higher can be achieved. The reaction rate in the step (I) usually represents the reaction rate of the cyclic carbonate. In the present invention, the reaction rate of the cyclic carbonate is 95% or more, preferably 97% or more, more preferably 99% or more, still more preferably. Can be 99.5 or more, and even more preferably 99.9% or more. Thus, it is one of the outstanding features of the step (I) that a high reaction rate can be achieved while maintaining a high selectivity.

The continuous multistage distillation column T ₀ used in the step (I) is preferably a distillation column having a tray and / or a packing as an internal. The term “internal” as used in the present invention means a portion where the gas-liquid contact is actually performed in the distillation column. As such a tray, for example, a foam tray, a perforated plate tray, a valve tray, a counter-flow tray, a super flack tray, a max flack tray and the like are preferable. Irregular fillers such as Rox saddle, Dixon packing, McMahon packing, and helipack, and regular fillers such as Merapack, Gempack, Technopack, Flexipack, Sulzer packing, Goodroll packing, and glitch grid are preferable. A multistage distillation column having both a tray portion and a portion filled with a packing can also be used. The term “internal plate number n” in the present invention means the number of trays in the case of trays, and the theoretical plate number in the case of packing.
Therefore, in the case of a multistage distillation column having both a tray portion and a portion filled with a packing, the number n of plates is the sum of the number of trays and the number of theoretical plates.

In the step (I) of reacting a cyclic carbonate and an aliphatic monohydric alcohol, a tray type continuous multistage distillation column and / or a packed column type continuous multistage consisting of a tray and / or a packing having a predetermined number of internal stages. Although any of the distillation columns can be used, a high reaction rate, high selectivity, and high productivity can be achieved, but it has been found that a plate-type distillation column in which the internal is a tray is more preferable. Furthermore, it has been found that a perforated plate tray having a perforated plate portion and a downcomer portion is particularly excellent in terms of function and equipment costs. It was also found that the perforated plate tray preferably has 100 to 1000 holes per 1 m ² of the area of the perforated plate portion. More preferably, the number of holes is 120 to 900 per 1 m ² , and more preferably 150 to 800. It was also found that the cross-sectional area per hole of the perforated plate tray is preferably 0.5 to ⁵ cm ² . More preferably, the cross-sectional area per hole is 0.7 to ⁴ cm ² , and more preferably 0.9 to ³ cm ² . Furthermore, when the perforated plate tray has 100 to 1000 holes per 1 m ² of the area of the perforated plate portion and the cross-sectional area per hole is 0.5 to ⁵ cm ² , It has been found preferable.

Furthermore, it has been found that the aperture ratio of the perforated plate tray is preferably 1.5 to 15%. The aperture ratio is more preferably 1.7 to 13%, and still more preferably 1.9 to 11%. Here, the aperture ratio of the perforated plate tray represents the ratio of the cross-sectional area of all the holes existing in the perforated plate to the area of the perforated plate portion (total hole cross-sectional area). In each of the perforated plate trays, the area of the perforated plate portion and / or the cross-sectional area of the entire hole may be different. In addition, the number of holes of the perforated plate portion may be the same in all perforated plates, or may be different. It has been found that by adding the above conditions to the continuous multistage distillation column T ₀ , the problem in the step (I) can be achieved more easily.

  When carrying out the step (I), cyclic carbonates and aliphatic monohydric alcohols as raw materials are continuously fed into a continuous multistage distillation column in which a catalyst is present, and the reaction and distillation are simultaneously performed in the column, The low-boiling point reaction mixture containing the dialkyl carbonate to be produced is continuously withdrawn in the form of gas from the top of the column, and the high-boiling point reaction mixture containing diols is continuously withdrawn in the form of a liquid from the bottom of the column, thereby allowing continuous dialkyl carbonate and diols Manufactured.

Further, in step (I), in order to continuously supply the cyclic carbonate and aliphatic monohydric alcohols as raw materials into the continuous multi-stage distillation column T ₀ , the lower portion than the gas outlet at the top of the distillation column. May be supplied in liquid and / or gaseous form as a raw material mixture or separately from one or several inlets installed in the upper part or the middle part of the tower, The raw material containing is supplied in liquid form from the inlet of the upper part or middle part of the distillation column, and the aliphatic monohydric alcohol or the raw material containing a large amount thereof is located above the liquid outlet at the lower part of the distillation tower and in the middle part of the tower Or it is also a preferable method to supply in gaseous form from the inlet installed in the lower part.

The reaction time of the transesterification performed in step (I) is considered to correspond to the average residence time of the reaction liquid in the continuous multistage distillation column T ₀ , but this is the internal shape and number of stages of the distillation column, feed of raw materials Although it varies depending on the amount, type and amount of catalyst, reaction conditions, etc., it is usually 0.1 to 20 hours, preferably 0.5 to 15 hours, more preferably 1 to 10 hours.

The reaction temperature in step (I) varies depending on the type of raw material compound used and the type and amount of catalyst, but is usually 30 to 300 ° C. In order to increase the reaction rate, it is preferable to increase the reaction temperature. However, if the reaction temperature is high, side reactions are likely to occur. A preferred reaction temperature is in the range of 40 to 250 ° C, more preferably 50 to 200 ° C, and still more preferably 60 to 150 ° C. In the present invention, the reactive distillation can be carried out at a column bottom temperature of 150 ° C. or lower, preferably 130 ° C. or lower, more preferably 110 ° C. or lower, and even more preferably 100 ° C. or lower. One of the excellent features of the step (I) is that high reaction rate, high selectivity and high productivity can be achieved even at such a low column bottom temperature. The reaction pressure varies depending on the type and composition of the raw material compound used, the reaction temperature, and the like, but may be any of reduced pressure, normal pressure, and increased pressure, and is usually 1 Pa to 2 × 10 ⁷ Pa, preferably 10 ^3. It is carried out in the range of Pa to 10 ⁷ Pa, more preferably 10 ^{4 to} 5 × 10 ⁶ .

The reflux ratio of continuous multi-stage distillation column _{T 0} step (I) is usually 0-10 is used, preferably 0.01 to 5, further preferably 0.05 to 3 is used.

Material constituting step the continuous multi-stage distillation column T ₀ used in (I) is mainly carbon steel, but a metal material such as stainless steel, from the viewpoint of the quality of the dialkyl carbonate to be produced, stainless steel is preferable.

In the present invention, subsequently, step (II) for continuously producing diaryl carbonate on an industrial scale from the dialkyl carbonate produced in step (I) and the aromatic monohydroxy compound is performed. The dialkyl carbonate used in the step (II) is represented by the following formula described in the following formula.
R ² OCOOR ²
Here, R ² is as described above.
Examples of such dialkyl carbonate having R ² include dimethyl carbonate, diethyl carbonate, dipropyl carbonate (each isomer), diallyl carbonate, dibutenyl carbonate (each isomer), dibutyl carbonate (each isomer), and dipentyl. Carbonate (each isomer), dihexyl carbonate (each isomer), diheptyl carbonate (each isomer), dioctyl carbonate (each isomer), dinonyl carbonate (each isomer), didecyl carbonate (each isomer), Dicyclopentyl carbonate, dicyclohexyl carbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate (each isomer), di (phenylpropyl) carbonate (each isomer), di (phenylbutyl) Carbonate (each isomer) di (chlorobenzyl) carbonate (each isomer), di (methoxybenzyl) carbonate (each isomer), di (methoxymethyl) carbonate, di (methoxyethyl) carbonate (each isomer), di (Chloroethyl) carbonate (each isomer), di (cyanoethyl) carbonate (each isomer) and the like.

Among them, what is preferably used in the present invention are dialkyl carbonates in which R ² consists of an alkyl group having 4 or less carbon atoms which does not contain halogen, particularly preferred is dimethyl carbonate. Further, among the preferable dialkyl carbonates, more preferable are dialkyl carbonates produced in a state substantially free of halogen, for example, alkylene carbonate substantially free of halogen and halogen free. It is manufactured from alcohol.

The aromatic monohydroxy compound used in the step (II) is represented by the following general formula, and is any compound as long as the hydroxyl group is directly bonded to the aromatic group. Also good.
Ar ³ OH
Here, Ar ³ represents an aromatic group having 5 to 30 carbon atoms. Examples of such aromatic monohydroxy compounds having Ar ³ include phenol, cresol (each isomer), xylenol (each isomer), trimethylphenol (each isomer), tetramethylphenol (each isomer), Ethylphenol (each isomer), propylphenol (each isomer), butylphenol (each isomer), diethylphenol (each isomer), methylethylphenol (each isomer), methylpropylphenol (each isomer), di Various alkylphenols such as propylphenol (each isomer), methylbutylphenol (each isomer), pentylphenol (each isomer), hexylphenol (each isomer), cyclohexylphenol (each isomer); methoxyphenol (each isomer) Body), ethoxyphenol (each isomer), etc. Species alkoxyphenols; arylalkylphenols such as phenylpropylphenol (each isomer); naphthol (each isomer) and various substituted naphthols; hydroxypyridine (each isomer), hydroxycoumarin (each isomer), hydroxyquinoline ( Heteroaromatic monohydroxy compounds such as each isomer) are used.

These aromatic monohydroxy compounds can be used as a mixture of one or more. Among these aromatic monohydroxy compounds, those that are preferably used in the present invention are aromatic monohydroxy compounds in which Ar ³ is an aromatic group having 6 to 10 carbon atoms, and phenol is particularly preferred. Among these aromatic monohydroxy compounds, those that are preferably used in the present invention are those that do not substantially contain halogen.

  Therefore, the diaryl carbonate referred to in the present invention is generally represented by the following formula.

(In the formula, Ar ³ and Ar ⁴ each represent a monovalent aromatic group.)
Ar ³ and Ar ⁴ represent a monovalent carbocyclic or heterocyclic aromatic group, and in this Ar ³ , Ar ⁴ , other substituents in which one or more hydrogen atoms do not adversely influence the reaction Substituted with, for example, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a phenyl group, a phenoxy group, a vinyl group, a cyano group, an ester group, an amide group, or a nitro group It may be. Ar ³ and Ar ⁴ may be the same or different. Representative examples of the monovalent aromatic groups Ar ³ and Ar ⁴ include a phenyl group, a naphthyl group, a biphenyl group, and a pyridyl group. These may be substituted with one or more substituents as described above.

Preferred examples of Ar ³ and Ar ⁴ include those represented by the following formulas, respectively.

  Particularly preferred diaryl carbonate is substituted or unsubstituted diphenyl carbonate represented by the following formula.

(In the formula, R ⁹ and R ¹⁰ are each independently 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 phenyl. P and q are integers of 1 to 5, and when p is 2 or more, each R ⁹ may be different, and when q is 2 or more, each R ¹⁰ May be different from each other.)

  Among these diaryl carbonates, symmetrical diaryl carbonates such as unsubstituted diphenyl carbonate and lower alkyl substituted diphenyl carbonates such as ditolyl carbonate and di-t-butylphenyl carbonate are preferred, but the most preferred is the simplest Diphenyl carbonate having a simple structure is preferred. These diaryl carbonates may be used alone or in combination of two or more.

  The molar ratio of the dialkyl carbonate used as a raw material in the step (II) to the aromatic monohydroxy compound is preferably 0.1 to 10 in terms of molar ratio. Outside this range, the remaining unreacted raw material increases with respect to the predetermined production amount of the target diaryl carbonate, which is not efficient and requires a lot of energy to recover them. In this sense, the molar ratio is more preferably 0.5 to 5, more preferably 0.8 to 3, and still more preferably 1 to 2.

  In the present invention, an aromatic polycarbonate of 1 ton or more per hour is continuously produced. For this purpose, it is necessary to continuously produce a high-purity diaryl carbonate of about 0.85 ton or more per hour. is there. Therefore, in the step (II), the minimum amount of the aromatic monohydroxy compound continuously fed is usually 15 P ton / hr with respect to the amount of the aromatic polycarbonate to be produced (P ton / hr). Preferably, it is 13 P ton / hr, more preferably 10 P ton / hr. In a more preferable case, it can be less than 8 P ton / hr.

  The dialkyl carbonate and aromatic monohydroxy compound used as raw materials in the step (II) may each be high purity, or may contain other compounds, for example, the first continuous multistage It may contain a compound or reaction byproduct produced in the distillation column or / and the second continuous multistage distillation column. When industrially carried out, these raw materials were recovered from the first continuous multistage distillation column and / or the second continuous multistage distillation column in addition to the dialkyl carbonate and aromatic monohydroxy compound newly introduced into the reaction system. It is preferable to use also. In the method of the present invention, the top component which is a low boiling point reaction mixture in the second continuous multistage distillation column is supplied to the first continuous multistage distillation column. In this case, the second column low boiling point reaction mixture may be supplied as it is to the first continuous multistage distillation column, or may be supplied after a part of the components is separated.

  Therefore, in the present invention to be industrially implemented, the raw material supplied to the first continuous multistage distillation column preferably contains alcohols, alkylaryl carbonates, diaryl carbonates, alkylaryl ethers, Furthermore, it is preferably used even if it contains a small amount of high-boiling by-products such as a product of alkylaryl carbonate or diaryl carbonate as a product, or a derivative thereof. In the present invention, for example, when producing methylphenyl carbonate and diphenyl carbonate using dimethyl carbonate as a dialkyl carbonate and phenol as an aromatic monohydroxy compound as raw materials, methyl alcohol or methylphenyl which is a reaction product in the raw materials It preferably contains carbonate and diphenyl carbonate, and may further contain a small amount of reaction by-products such as anisole, phenyl salicylate, methyl salicylate and high-boiling by-products derived therefrom.

  Furthermore, most of the aromatic monohydroxy compounds used in step (II) consist of aromatic monohydroxy compounds by-produced in step (IV) of the present invention. This by-product aromatic monohydroxy compound needs to be recycled to step (II) by step (V).

  The diaryl carbonate produced in step (II) is obtained by a transesterification reaction between a dialkyl carbonate and an aromatic monohydroxy compound. In this transesterification reaction, one or two alkoxy groups of the dialkyl carbonate are aromatic. Includes reactions that are exchanged with aryloxy groups of monohydroxy compounds to leave alcohols, and reactions that are converted to diaryl carbonates and dialkyl carbonates by a disproportionation reaction that is a transesterification reaction between the two molecules of the alkylaryl carbonate produced. Yes. In the first continuous multi-stage distillation column of Step (II), alkylaryl carbonate is mainly obtained, and in the second continuous multi-stage distillation column, diaryl carbonate and dialkyl carbonate are mainly obtained by the disproportionation reaction of the alkylaryl carbonate. Since the diaryl carbonate obtained in the step (II) does not contain any halogen, it is important as a raw material for industrial production of the aromatic polycarbonate of the present invention. This is because if the halogen is present in the polymerization raw material in an amount less than 1 ppm, for example, the polymerization reaction is inhibited, the stable production of the aromatic polycarbonate is inhibited, and the produced aromatic polycarbonate This is because it causes deterioration of physical properties and coloring.

The catalyst used in the first continuous multistage distillation column or / and the second continuous multistage distillation column in step (II) is selected from the following compounds, for example.
<Lead compounds> Lead oxides such as PbO, PbO ₂ and Pb ₃ O ₄ ; Lead sulfides such as PbS and Pb ₂ S; Lead hydroxides such as Pb (OH) ₂ and Pb ₂ O ₂ (OH) ₂ Ninamates such as Na ₂ PbO ₂ , K ₂ PbO ₂ , NaHPbO ₂ , KHPbO ₂ ; Na ₂ PbO ₃ , Na ₂ H ₂ PbO ₄ , K ₂ PbO ₃ , K ₂ [Pb (OH) ₆ ], _{K 4 PbO 4, Ca 2 PbO} 4, lead-acid salts such as _{CaPbO 3; PbCO 3, 2PbCO 3} · Pb (OH) carbonates ₂ such as lead and its basic _{salts; Pb (OCOCH 3) 2,} Pb ( Lead salts of organic acids such as OCOCH ₃ ) ₄ , Pb (OCOCH ₃ ) ₂ .PbO.3H ₂ O and carbonates and basic salts thereof; Bu ₄ Pb, Ph ₄ Pb, Bu ₃ PbCl, Ph ₃ PbBr, Ph ₃ Pb (or _{Ph 6 Pb 2), Bu 3} PbOH, such as Ph ₃ PbO Machine Lead compounds (Bu is a butyl group, Ph represents a phenyl _{group.); Pb (OCH 3)} 2, (CH 3 O) Pb (OPh), Pb (OPh) alkoxy lead such as _2, aryloxy lead Pb-Na, Pb-Ca, Pb-Ba, Pb-Sn, lead alloys such as Pb-Sb; lead minerals such as hohenite, senaene ore, and hydrates of these lead compounds;
<Copper family metal _{compounds> CuCl, CuCl 2, CuBr,} CuBr 2, CuI, CuI 2, Cu (OAc) 2, Cu (acac) 2, copper _{oleate, Bu 2 Cu, (CH 3} O) 2 Cu, Salts and complexes of copper group metals such as AgNO ₃ , AgBr, silver picrate, AgC ₆ H ₆ ClO ₄ , [AuC≡C—C (CH ₃ ) ₃ ] n, [Cu (C ₇ H ₈ ) Cl] ₄ (Acac represents an acetylacetone chelate ligand);
<Alkali metal complexes> Alkali metal complexes such as Li (acac) and LiN (C ₄ H ₉ ) ₂ ;
<Zinc complex> Zinc complex such as Zn (acac) ₂ ;
<Cadmium complex> Cd complex such as Cd (acac) ₂ ;
<Compounds of iron group metals> Fe (C ₁₀ H ₈ ) (CO) ₅ , Fe (CO) ₅ , Fe (C ₄ H ₆ ) (CO) ₃ , Co (mesitylene) ₂ (PEt ₂ Ph) ₂ , CoC Complexes of iron group metals such as ₅ F ₅ (CO) ₇ , Ni-π-C ₅ H ₅ NO, ferrocene;
<Zirconium Complex> Zirconium complexes such as Zr (acac) ₄ and zirconocene;
<Lewis acid compounds> AlX ₃ , TiX ₃ , TiX ₄ , VOX ₃ , VX ₅ , ZnX ₂ , FeX ₃ , SnX ₄ (where X is a halogen, an acetoxy group, an alkoxy group, an aryloxy group) or the like. Lewis acids and transition metal compounds that generate Lewis acids;
<Organic tin compound> (CH ₃ ) ₃ SnOCOCH ₃ , (C ₂ H ₅ ) ₃ SnOCOC ₆ H ₅ , Bu ₃ SnOCOCH ₃ , Ph ₃ SnOCOCH ₃ , Bu ₂ Sn (OCOCH ₃ ) ₂ , Bu ₂ Sn (OCOC ₁₁ H ₂₃ ) ₂ , Ph ₃ SnOCH ₃ , (C ₂ H ₅ ) ₃ SnOPh, Bu ₂ Sn (OCH ₃ ) ₂ , Bu ₂ Sn (OC ₂ H ₅ ) ₂ , Bu ₂ Sn (OPh) ₂ , Ph ₂ Sn Organotin compounds such as (OCH ₃ ) ₂ , (C ₂ H ₅ ) ₃ SnOH, Ph ₃ SnOH, Bu ₂ SnO, (C ₈ H ₁₇ ) ₂ SnO, Bu ₂ SnCl ₂ , BuSnO (OH);
A metal-containing compound such as is used as a catalyst. These catalysts may be solid catalysts fixed in a multistage distillation column, or may be soluble catalysts that dissolve in the reaction system.

  Of course, these catalyst components are reacted with organic compounds present in the reaction system, such as aliphatic alcohols, aromatic monohydroxy compounds, alkylaryl carbonates, diaryl carbonates, dialkyl carbonates, etc. Alternatively, it may be heat-treated with raw materials or products prior to the reaction.

When the step (II) is carried out with a soluble catalyst that dissolves in the reaction system, it is preferable that these catalysts have high solubility in the reaction solution under the reaction conditions. Preferred catalysts in this sense include, for example, PbO, Pb (OH) ₂ , Pb (OPh) ₂ ; TiCl ₄ , Ti (OMe) ₄ , (MeO) Ti (OPh) ₃ , (MeO) ₂ Ti (OPh) ₂ , (MeO) ₃ Ti (OPh), Ti (OPh) ₄ ; SnCl ₄ , Sn (OPh) ₄ , Bu ₂ SnO, Bu ₂ Sn (OPh) ₂ ; FeCl ₃ , Fe (OH) ₃ , Fe (OPh) ₃ ), etc., or those treated with phenol or a reaction solution. The catalyst used in the first continuous multistage distillation column and the catalyst used in the second continuous multistage distillation column may be the same type or different types.

The first continuous multi-stage distillation column used in the step (II) is an internal having a cylindrical body having a length L ₁ (cm) and an inner diameter D ₁ (cm) and having a number n ₁ inside. A gas outlet with an inner diameter d ₁₁ (cm) at the top of the tower or near the top of the tower, and a liquid outlet with an inner diameter d ₁₂ (cm) at the bottom of the tower or near the bottom of the tower, the gas One or more third inlets below the outlet and in the upper part and / or middle part of the tower, and one or more fourth inlets above the liquid outlet and in the intermediate part and / or lower part of the tower. L ₁ , D ₁ , L ₁ / D ₁ , n ₁ , D ₁ / d ₁₁ , D ₁ / d ₁₂ satisfy formulas (7) to (13), respectively. It must be a thing.
1500 ≦ L ₁ ≦ 8000 Formula (7)
100 ≦ D ₁ ≦ 2000 Formula (8)
_{2 ≦ L 1 / D 1 ≦} 40 Equation (9)
20 ≦ n ₁ ≦ 120 Formula (10)
_{5 ≦ D 1 / d 11 ≦} 30 Equation (11)
_{3 ≦ D 1 / d 12 ≦} 20 Equation (12)

Moreover, the second continuous multi-stage distillation column used in step (II), a length _L 2 (cm), has a cylindrical body portion having an inner diameter _D 2 (cm), Inter with the number of stages _{n 2} therein A gas outlet with an inner diameter d ₂₁ (cm) at the top of the tower or near the top of the tower, and a liquid outlet with an inner diameter d ₂₂ (cm) at the bottom of the tower or the lower part of the tower, One or more fifth inlets below the gas outlet and in the upper and / or middle part of the tower, and one or more fifth inlets above the liquid outlet and in the middle and / or lower part of the tower. 6, and L ₂ , D ₂ , L ₂ / D ₂ , n ₂ , D ₂ / d ₂₁ , D ₂ / d ₂₂ satisfy Formulas (13) to (18), respectively. It is necessary to be.
1500 ≦ L ₂ ≦ 8000 Formula (13)
100 ≦ D ₂ ≦ 2000 Formula (14)
2 ≦ L ₂ / D ₂ ≦ 40 Formula (15)
10 ≦ n ₂ ≦ 80 Formula (16)
2 ≦ D ₂ / d ₂₁ ≦ 15 Formula (17)
5 ≦ D ₂ / d ₂₂ ≦ 30 Formula (18)

  By using the first continuous multi-stage distillation column and the second continuous multi-stage distillation column that simultaneously satisfy all of the formulas (7) to (18), the diaryl carbonate is converted from the dialkyl carbonate and the aromatic monohydroxy compound to about 0.85 tons or more, preferably on an industrial scale of 1 ton or more, with high selectivity and high productivity, for example, 2000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more for a long period of time. It has been found that it can be manufactured. The reason why it is possible to produce an aromatic carbonate on an industrial scale having such an excellent effect by carrying out the method of the present invention is not clear, but the conditions of the formulas (7) to (18) It is presumed that this is due to the combined effect brought about when the two are combined. In addition, the preferable range of each factor which comprises the continuous multistage distillation column used by process (II) is shown below.

If L ₁ (cm) and L ₂ (cm) are smaller than 1500 respectively, the reaction rate is lowered, so that the target production amount cannot be achieved, and the equipment cost is secured while ensuring the reaction rate that can achieve the target production amount. In order to decrease, it is necessary to set L ₁ and L ₂ to 8000 or less, respectively. More preferable ranges of L ₁ (cm) and L ₂ (cm) are 2000 ≦ L ₁ ≦ 6000 and 2000 ≦ L ₂ ≦ 6000, respectively, and more preferably 2500 ≦ L ₁ ≦ 5000 and 2500 ≦ L _2. ≦ 5000.

If D ₁ (cm) and D ₂ (cm) are each smaller than 100, the target production amount cannot be achieved, and in order to reduce the facility cost while achieving the target production amount, D ₁ and D ₂ Must be 2000 or less, respectively.

More preferable ranges of D ₁ (cm) and D ₂ (cm) are 150 ≦ D ₁ ≦ 1000 and 150 ≦ D ₂ ≦ 1000, respectively, and more preferably 200 ≦ D ₁ ≦ 800 and 200 ≦ D ₂ , respectively. ≦ 800.

In the first continuous multi-stage distillation column and the second continuous multi-stage distillation column, as long as D ₁ and D ₂ are in the above range, the inner diameter may be the same from the upper part to the lower part of the tower, or the inner diameter may be partially May be different. For example, in these continuous multistage distillation columns, the inner diameter of the upper part of the tower may be smaller or larger than the inner diameter of the lower part of the tower.

When L ₁ / D ₁ and L ₂ / D ₂ are smaller than 2 or larger than 40, stable operation becomes difficult. Especially when L ₁ / D ₁ and L ₂ / D ₂ are larger than 40, the pressure difference between the top and bottom of the tower becomes too large. Not only is this difficult, but the temperature at the bottom of the column must be increased, which leads to side reactions that tend to reduce selectivity. More preferable ranges of L ₁ / D ₁ and L ₂ / D ₂ are 3 ≦ L ₁ / D ₁ ≦ 30 and 3 ≦ L ₂ / D ₂ ≦ 30, respectively, and more preferably 5 ≦ L ₁ / D. ₁ ≦ 15 and 5 ≦ L ₂ / D ₂ ≦ 15.

If n ₁ is less than 20, the reaction rate decreases, so that the target production amount in the first continuous multistage distillation column cannot be achieved, and the facility cost is reduced while ensuring the reaction rate that can achieve the target production amount. Requires n ₁ to be 120 or less. Furthermore, if n ₁ is larger than 120, the pressure difference between the top and bottom of the column becomes too large, so that not only long-term stable operation of the first continuous multistage distillation column becomes difficult, but also the temperature at the bottom of the column must be increased. Therefore, a side reaction is likely to occur, resulting in a decrease in selectivity. A more preferable range of n ₁ is 30 ≦ n ₁ ≦ 100, and further preferably 40 ≦ n ₁ ≦ 90.

In addition, if n ₂ is less than 10, the reaction rate decreases, so the target production amount in the second continuous multistage distillation column cannot be achieved, and the equipment cost is reduced while ensuring the reaction rate that can achieve the target production amount. In order to achieve this, n ₂ needs to be 80 or less. Further, if n ₂ is greater than 80, the pressure difference between the upper and lower sides of the column becomes too large, so that not only long-term stable operation of the second continuous multistage distillation column becomes difficult, but also the temperature at the bottom of the column must be increased. Therefore, a side reaction is likely to occur, resulting in a decrease in selectivity. A more preferable range of n ₂ is 15 ≦ n ₂ ≦ 60, and further preferably 20 ≦ n ₂ ≦ 50.

If D ₁ / d ₁₁ is smaller than 5, not only will the equipment cost of the first continuous multistage distillation column increase, but also a large amount of gas components will easily come out of the system, making it difficult to stably operate the first continuous multistage distillation column. If it is greater than 30, the amount of gas components extracted becomes relatively small, which not only makes stable operation difficult, but also reduces the reaction rate. A more preferable range of D ₁ / d ₁₁ is 8 ≦ D ₁ / d ₁₁ ≦ 25, and further preferably 10 ≦ D ₁ / d ₁₁ ≦ 20. Further, if D ₂ / d ₂₁ is smaller than 2, not only the equipment cost of the second continuous multistage distillation column is increased, but also a large amount of gas components are easily discharged out of the system. When it exceeds 15 and the amount of gas components extracted is relatively small, not only stable operation becomes difficult, but also the reaction rate decreases. A more preferable range of D ₂ / d ₂₁ is 5 ≦ D ₂ / d ₂₁ ≦ 12, and further preferably 3 ≦ D ₂ / d ₂₁ ≦ 10.

If D ₁ / d ₁₂ is smaller than 3, not only the equipment cost of the first continuous multi-stage distillation column is increased, but also the amount of liquid withdrawn is relatively increased, and the stable operation of the first continuous multi-stage distillation tower becomes difficult. If it is larger than this, the flow velocity at the liquid outlet and the piping will increase rapidly, and erosion will easily occur, resulting in corrosion of the device. A more preferable range of D ₁ / d ₁₂ is 5 ≦ D ₁ / d ₁₂ ≦ 18, and further preferably 7 ≦ D ₁ / d ₁₂ ≦ 15. Further, if D ₂ / d ₂₂ is smaller than 5, not only the equipment cost of the second continuous multi-stage distillation column is increased, but also the amount of liquid withdrawal becomes relatively large, and the stable operation of the second continuous multi-stage distillation tower becomes difficult. If it is larger than 30, the flow velocity at the liquid outlet and the piping is rapidly increased, and erosion is likely to occur, resulting in corrosion of the apparatus. A more preferable range of D ₂ / d ₂₂ is 7 ≦ D ₂ / d ₂₂ ≦ 25, and further preferably 9 ≦ D ₂ / d ₂₂ ≦ 20.

Furthermore, in the step (II), it was found that it is further preferable when the d ₁₁ and the d ₁₂ satisfy the formula (25) and the d ₂₁ and the d ₂₂ satisfy the formula (26).
1 ≦ d ₁₂ / d ₁₁ ≦ 5 Formula (25)
1 ≦ d ₂₁ / d ₂₂ ≦ 6 Formula (26)

  The long-term stable operation in the step (II) is 1000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more, and there is no flooding, piping clogging or erosion, and the operation is in a steady state based on operation conditions. This means that a predetermined amount of diaryl carbonate is produced while maintaining high selectivity.

Step (II) is characterized in that diaryl carbonate is stably produced at a high selectivity for a long period of time with a high productivity of preferably 1 ton or more per hour, more preferably 2 ton or more per hour, More preferably, it is to produce 3 tons or more of diaryl carbonate per hour. In Step (II), L ₁ , D ₁ , L ₁ / D ₁ , n ₁ , D ₁ / d ₁₁ , and D ₁ / d _{12 of} the first continuous multistage distillation column are 2000 ≦ L ₁ ≦ 6000, respectively. 150 ≦ D ₁ ≦ 1000, 3 ≦ L ₁ / D ₁ ≦ 30, 30 ≦ n ₁ ≦ 100, 8 ≦ D ₁ / d ₁₁ ≦ 25, 5 ≦ D ₁ / d ₁₂ ≦ 18, L ₂ , D ₂ , L ₂ / D ₂ , n ₂ , D ₂ / d ₂₁ , D ₂ / d _{22 of the} continuous multistage distillation column are 2000 ≦ L ₂ ≦ 6000, 150 ≦ D ₂ ≦ 1000, 3 ≦, respectively. In the case of L ₂ / D ₂ ≦ 30, 15 ≦ n ₂ ≦ 60, 2.5 ≦ D ₂ / d ₂₁ ≦ 12, 7 ≦ D ₂ / d ₂₂ ≦ 25, 2 tons or more per hour, preferably 1 More than 2.5 tons per hour, more preferably more than 3 tons per hour It is characterized in that to produce the Boneto.

Further, in step (II), L ₁ , D ₁ , L ₁ / D ₁ , n ₁ , D ₁ / d ₁₁ , and D ₁ / d _{12 of} the first continuous multistage distillation column are 2500 ≦ L ₁ ≦ 5000, respectively. 200 ≦ D ₁ ≦ 800, 5 ≦ L ₁ / D ₁ ≦ 15, 40 ≦ n ₁ ≦ 90, 10 ≦ D ₁ / d ₁₁ ≦ 25, 7 ≦ D ₁ / d ₁₂ ≦ 15, L ₂ , D ₂ , L ₂ / D ₂ , n ₂ , D ₂ / d ₂₁ , D ₂ / d _{22 in the} continuous multistage distillation column are 2500 ≦ L ₂ ≦ 5000, 200 ≦ D ₂ ≦ 800, 5 ≦, respectively. In the case of L ₂ / D ₂ ≦ 10, 20 ≦ n ₂ ≦ 50, 3 ≦ D ₂ / d ₂₁ ≦ 10, 9 ≦ D ₂ / d ₂₂ ≦ 20, 3 tons or more per hour, preferably per hour 3.5 tons or more, more preferably 4 tons or more of a diaryl carbonate per hour It is characterized in that to produce the door.

The selectivity of the diaryl carbonate in the step (II) refers to the reacted aromatic monohydroxy compound, and in the step (II), it is usually a high selectivity of 95% or more, preferably 97% or more, Preferably, a high selectivity of 98% or more can be achieved.
The first continuous multistage distillation column and the second continuous multistage distillation column used in step (II) are preferably distillation columns having trays and / or packings as internal. The term “internal” as used in the present invention means a portion where the gas-liquid contact is actually performed in the distillation column. As such a tray, the thing as described in the item of process (I) is preferable. The “internal stage number n” is as described above.

  In the first continuous multi-stage distillation column of step (II), a reaction for mainly producing an alkylaryl carbonate from a dialkyl carbonate and an aromatic monohydroxy compound is carried out, but this reaction has an extremely small equilibrium constant and a reaction rate. Since it is slow, it was found that the first continuous multi-stage distillation column used for the reactive distillation is more preferably a plate-type distillation column whose tray is an internal. In the second continuous multistage distillation column, a reaction for disproportionating the alkylaryl carbonate is mainly carried out. This reaction also has a small equilibrium constant and a slow reaction rate. However, it has been found that the second continuous multistage distillation column used for reactive distillation is more preferably a distillation column in which the internal has both a packing and a tray. Furthermore, it was also found that the second continuous multistage distillation column is preferably one having a packing at the top and a tray at the bottom. It has also been found that the packing of the second continuous multi-stage distillation column is preferably ordered packing, and melapack is particularly preferable among the ordered packing.

Further, the trays installed in the first continuous multistage distillation column and the second continuous multistage distillation column, respectively, are particularly excellent in terms of function and equipment costs. It was found. It was also found that the perforated plate tray preferably has 100 to 1000 holes per 1 m ² of the area of the perforated plate portion. More preferably, the number of holes is 120 to 900 per 1 m ² , and more preferably 150 to 800.

It was also found that the cross-sectional area per hole of the perforated plate tray is preferably 0.5 to ⁵ cm ² . More preferably, the cross-sectional area per hole is 0.7 to ⁴ cm ² , and more preferably 0.9 to ³ cm ² . Furthermore, when the perforated plate tray has 100 to 1000 holes per 1 m ² of the area of the perforated plate portion and the cross-sectional area per hole is 0.5 to ⁵ cm ² , It has been found preferable. It has been found that the object of the present invention can be achieved more easily by adding the above conditions to a continuous multistage distillation column.

  When carrying out step (II), the raw material dialkyl carbonate and aromatic monohydroxy compound are continuously fed into the first continuous multistage distillation column in which the catalyst is present, and the reaction and distillation are carried out in the first column. The first tower low-boiling point reaction mixture containing alcohols produced at the same time is continuously withdrawn in the form of a gas from the upper part of the first tower, and the first tower high-boiling point reaction mixture containing the alkylaryl carbonates produced is removed from the first tower. Continuously in liquid form from the bottom of the column, continuously supplying the high-boiling reaction mixture of the first column into the second continuous multi-stage distillation column in which the catalyst is present, and simultaneously performing the reaction and distillation in the second column; The second tower low boiling point reaction mixture containing the dialkyl carbonates to be produced is continuously withdrawn in the form of a gas from the upper part of the second tower, and the second tower high boiling point reaction mixture containing the diaryl carbonates to be produced is removed from the lower part of the second tower. Ri liquid continuously withdrawn while by continuously feeding the second column low boiling point reaction mixture containing a dialkyl carbonate into the first continuous multi-stage distillation column, the diaryl carbonate is continuously produced.

  As described above, this raw material may contain reaction by-products such as alcohols, alkylaryl carbonates, diaryl carbonates, alkylaryl ethers, and high-boiling compounds as reaction products. Considering the equipment and cost for separation and purification in other steps, in the case of the present invention which is actually carried out industrially, it is preferable to contain a small amount of these compounds.

  In step (II), in order to continuously supply the dialkyl carbonate and the aromatic monohydroxy compound as raw materials into the first continuous multistage distillation column, the lower part is lower than the gas outlet at the top of the first distillation column. May be supplied in liquid and / or gaseous form from one or several inlets installed in the upper part or middle part of the column, or a raw material rich in aromatic monohydroxy compounds may be supplied to the first distillation column. The raw material containing a large amount of dialkyl carbonate is supplied in the form of gas from the inlet provided at the lower part of the first distillation column and at the lower part of the column. This is also a preferred method.

  In step (II), the first column high boiling point reaction mixture containing alkylaryl carbonates continuously extracted from the lower part of the first continuous multistage distillation column is continuously supplied to the second continuous multistage distillation column. The supply position is lower than the gas outlet at the top of the second distillation column, but is supplied in liquid and / or gaseous form from one or several inlets installed at the top or middle of the column. It is preferable. Moreover, when using the distillation tower which has a packing part in the upper part which is a preferable embodiment of this invention, and a tray part in the lower part, at least 1 place of an inlet may be installed between a packing part and a tray part. preferable. Further, when the packing is composed of a plurality of regular packings of two or more, it is also a preferable method to install introduction ports at intervals constituting the plurality of regular packings.

  Further, in step (II), after condensing the top gas extraction components of the first continuous multistage distillation column and the second continuous multistage distillation column, respectively, a reflux operation may be performed in which a part thereof is returned to the upper part of each distillation column. This is the preferred method. In this case, the reflux ratio of the first continuous multistage distillation column is 0 to 10, and the reflux ratio of the second continuous multistage distillation column is in the range of 0.01 to 10, preferably 0.08 to 5, more preferably, It is in the range of 0.1 to 2. A reflux ratio of 0 where no reflux operation is performed in the first continuous multistage distillation column is also a preferred embodiment.

  In step (II), any method may be used for allowing the catalyst to be present in the first continuous multistage distillation column. When the catalyst is in a solid state insoluble in the reaction solution, the first continuous multistage is used. It is preferable to fix in the column by a method of installing in a stage in the distillation column or a method of installing in a packed form. In the case of a catalyst that dissolves in the raw material or the reaction solution, it is preferable to supply the catalyst into the distillation column from a position above the middle part of the first distillation column. In this case, the catalyst solution dissolved in the raw material or the reaction liquid may be introduced together with the raw material, or the catalyst liquid may be introduced from an inlet different from the raw material. The amount of the catalyst used in the first continuous multistage distillation column of the present invention varies depending on the type of catalyst used, the type of raw material and its ratio, reaction temperature, reaction pressure and other reaction conditions, but the total mass of the raw material. Expressed in terms of a ratio, the amount is usually 0.0001 to 30% by mass, preferably 0.0005 to 10% by mass, and more preferably 0.001 to 1% by mass.

  In step (II), any method may be used for allowing the catalyst to be present in the second continuous multistage distillation column. However, when the catalyst is in a solid state insoluble in the reaction solution, It is preferable to fix in the column by a method of installing in a stage in a continuous multi-stage distillation column or a method of installing in a packed form. Moreover, in the case of the catalyst which melt | dissolves in a raw material or a reaction liquid, it is preferable to supply in a distillation tower from the position above the intermediate part of this 2nd distillation tower. In this case, the catalyst solution dissolved in the raw material or the reaction liquid may be introduced together with the raw material, or the catalyst liquid may be introduced from an inlet different from the raw material. The amount of the catalyst used in the second continuous multi-stage distillation column of the present invention varies depending on the type of catalyst used, the type of raw material and its ratio, the reaction temperature, the reaction pressure and other reaction conditions, but the total mass of the raw material. Expressed in terms of a ratio, the amount is usually 0.0001 to 30% by mass, preferably 0.0005 to 10% by mass, and more preferably 0.001 to 1% by mass.

  In step (II), the catalyst used in the first continuous multistage distillation column and the catalyst used in the second continuous multistage distillation column may be the same type or different types, Preferably, the same type of catalyst is used. Further preferred are catalysts of the same type that can be dissolved in both reaction solutions. In this case, the catalyst is usually dissolved in the high boiling point reaction mixture of the first continuous multistage distillation column, extracted from the lower part of the first distillation column together with the alkylaryl carbonate, etc., and supplied to the second continuous multistage distillation column as it is. This is a preferred embodiment. In addition, it is also possible to newly add a catalyst to a 2nd continuous multistage distillation column as needed.

  The reaction time of the transesterification performed in the step (II) is considered to correspond to the average residence time of each reaction solution in the first continuous multistage distillation column and the second continuous multistage distillation column. Although it varies depending on the internal shape and number of stages of the distillation column, the feed amount of the raw material, the type and amount of the catalyst, the reaction conditions, and the like, it is generally 0. 01 to 10 hours, preferably 0.05 to 5 hours, more preferably 0.1 to 3 hours.

  The reaction temperature of the first continuous multistage distillation column varies depending on the type of raw material compound used and the type and amount of the catalyst, but is usually in the range of 100 to 350 ° C. In order to increase the reaction rate, it is preferable to increase the reaction temperature. However, if the reaction temperature is high, side reactions are likely to occur, and this is not preferable because by-products such as alkylaryl ethers increase. In this sense, a preferable reaction temperature in the first continuous multistage distillation column is in the range of 130 to 280 ° C, more preferably 150 to 260 ° C, and still more preferably 180 to 250 ° C.

  The reaction temperature of the second continuous multistage distillation column varies depending on the type of raw material compound used and the type and amount of the catalyst, but is usually in the range of 100 to 350 ° C. In order to increase the reaction rate, it is preferable to increase the reaction temperature. However, if the reaction temperature is high, side reactions are also likely to occur. For example, alkyl aryl ethers and Fries transition of raw materials and products such as alkyl aryl carbonates and diaryl carbonates. This is not preferable because by-products such as reaction products and derivatives thereof increase. In this sense, the preferable reaction temperature in the second continuous multistage distillation column is in the range of 130 to 280 ° C, more preferably 150 to 260 ° C, and still more preferably 180 to 250 ° C.

Further, the reaction pressure of the first continuous multistage distillation column varies depending on the type and composition of the raw material compound used, the reaction temperature, etc., but the first continuous multistage distillation column may be any of reduced pressure, normal pressure, and increased pressure, Usually, the column top pressure is 0.1 to 2 × 10 ⁷ Pa, preferably 10 ⁵ to 10 ⁷ Pa, more preferably 2 × 10 ^{5 to} 5 × 10 ⁶ .

The reaction pressure of the second continuous multistage distillation column varies depending on the type and composition of the raw material compound used, the reaction temperature, etc., but may be any of reduced pressure, normal pressure, and increased pressure. It is performed in the range of 2 × 10 ⁷ Pa, preferably 10 ³ to 10 ⁶ Pa, more preferably 5 × 10 ³ to 10 ⁵ .

  In addition, two or more distillation columns can also be used as the first continuous multi-stage distillation column in the step (II). In this case, it is possible to connect two or more distillation columns in series, connect them in parallel, or connect them in combination of series and parallel. In addition, two or more distillation towers can be used as the second continuous multistage distillation tower in the step (II). In this case, it is possible to connect two or more distillation columns in series, connect them in parallel, or connect them in combination of series and parallel.

  The materials constituting the first continuous multistage distillation column and the second continuous multistage distillation column used in the step (II) are mainly metal materials such as carbon steel and stainless steel. Is preferably stainless steel.

  The second tower high boiling point reaction mixture continuously extracted in liquid form from the lower part of the second continuous multistage distillation column in the step (II) is mainly composed of diaryl carbonate, but usually unreacted alkyl aryl carbonate, It contains a small amount of unreacted raw material, a small amount of high-boiling by-products, etc., and when a homogeneous catalyst is used, this catalyst component is also included. Therefore, it is necessary to carry out the purification step (III) for obtaining high-purity diaryl carbonate from the second tower high-boiling point reaction mixture. Step (III) may be any method as long as it can obtain high-purity diaryl carbonate from the second tower high boiling point reaction mixture. For example, a method such as distillation and / or recrystallization. Among these, in the present invention, it was found that the step (III) is particularly preferably performed by a distillation method.

  Furthermore, in the present invention, the step (III) uses two distillation towers (a high-boiling substance separation tower, a diaryl carbonate purification tower having a side cut outlet), and in the high-boiling substance separation tower, unreacted alkyl aryl carbonate , Continuously separating a small amount of unreacted raw material, a top component mainly composed of diaryl carbonate, and a small amount of high-boiling by-products and / or a bottom component mainly composed of a catalyst component, The boiling point substance separation tower top component is continuously supplied to the diaryl carbonate purification tower, and in the diaryl carbonate purification tower, the top component, the side cut component, and the bottom component are continuously separated. It has been found that a distillation separation method that obtains high-purity diaryl carbonate as a side-cut component is more preferable.

  In addition, the whole or a part of the bottom component of the high-boiling-point substance separation tower is recycled and reused in the first continuous multistage distillation tower and / or the second continuous multistage distillation tower as a catalyst component in the step (II). Is preferred. In addition, since a small amount of diaryl carbonate is usually contained in the tower top component of the diaryl carbonate purification tower, the tower top component is left as it is, or the low boiling point component contained in the tower top component is separated in another distillation tower. It is also a preferred method to recover high-purity diaryl carbonate by separating all or part of the bottom components of the distillation column after separation into a high-boiling-point material separation column and / or diaryl carbonate purification column.

  In step (III), a high-purity diaryl carbonate of usually 99.9% or more, preferably 99.99% or more is obtained. And content of a high boiling point by-product is 100 ppm or less normally, Preferably it is 50 ppm or less, More preferably, it is 10 ppm or less. In the present invention, since a halogen-free raw material and a catalyst are usually used, the halogen content of the obtained high-purity diaryl carbonate is 0.1 ppm or less, preferably 10 ppb or less, more preferably 1 ppb or less. It is.

  Subsequently, step (IV) is performed. That is, an aromatic dihydroxy compound and the high-purity diaryl carbonate are reacted to produce a molten prepolymer of an aromatic polycarbonate, and the molten prepolymer is allowed to flow down along the surface of the guide, It is the process of manufacturing an aromatic polycarbonate using the guide contact flow type | formula polymerization device which performs superposition | polymerization of this.

In the step (IV), the aromatic dihydroxy compound used is a compound represented by the following general formula.
HO-Ar-OH
(In the formula, Ar represents a divalent aromatic group).

The divalent aromatic group Ar is preferably represented by the following general formula, for example.
—Ar ¹ —Y—Ar ² —
(In the formula, Ar ¹ and Ar ² each independently represent a divalent carbocyclic or heterocyclic aromatic group having 5 to 70 carbon atoms, and Y is a divalent having 1 to 30 carbon atoms. Represents an alkane group.)

In the divalent aromatic groups Ar ¹ and Ar ² , one or more hydrogen atoms have other substituents that do not adversely influence the reaction, for example, halogen atoms, alkyl groups having 1 to 10 carbon atoms, carbon atoms 1 to It may be substituted with 10 alkoxy groups, phenyl group, phenoxy group, vinyl group, cyano group, ester group, amide group, nitro group or the like. Preferable specific examples of the heterocyclic aromatic group include aromatic groups having one or more ring-forming nitrogen atoms, oxygen atoms or sulfur atoms. The divalent aromatic groups Ar ¹ and Ar ² represent groups such as substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene, substituted or unsubstituted pyridylene, and the like. The substituents here are as described above.
The divalent alkane group Y is, for example, an organic group represented by the following formula.

(Wherein R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a cycloalkyl having 5 to 10 carbon atoms in the ring structure. Group, a carbocyclic aromatic group having 5 to 10 ring carbon atoms, and a carbocyclic aralkyl group having 6 to 10 carbon atoms, k is an integer of 3 to 11, and R ⁵ and R ⁶ are each X Independently selected from each other, each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms, X represents carbon, and R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ In the range where one or more hydrogen atoms do not adversely affect the reaction, for example, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a phenyl group, a phenoxy group, vinyl Group, cyano group, ester group, amide group, nitro group, etc. Be one that is substituted may be.)

  As such a bivalent aromatic group Ar, what is shown by a following formula is mentioned, for example.

(Wherein R ⁷ and R ⁸ each independently represents a hydrogen atom, a halogen 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, m and n are integers of 1 to 4, and when m is 2 to 4, each R ⁷ may be the same or different, and when n is 2 to 4 R ⁸ may be the same or different.

Further, the divalent aromatic group Ar may be represented by the following formula.
—Ar ¹ —Z—Ar ² —
(In the formula, Ar ¹ and Ar ² are as described above, Z is a single bond or —O—, —CO—, —S—, —SO ₂ —, —SO—, —COO—, —CON (R ¹ )-Represents a divalent group such as-, where R ¹ is as described above.

  Examples of such a divalent aromatic group Ar include those represented by the following formula.

(Wherein R ⁷ , R ⁸ , m and n are as described above.)
Furthermore, specific examples of the divalent aromatic group Ar include substituted or unsubstituted phenylene, substituted or unsubstituted naphthylene, substituted or unsubstituted pyridylene, and the like.

  The aromatic dihydroxy compound used in the present invention may be a single type or two or more types. A typical example of the aromatic dihydroxy compound is bisphenol A. Moreover, in this invention, you may use together the trivalent aromatic trihydroxy compound for introduce | transducing a branched structure in the range which does not impair the objective of this invention.

  The use ratio (preparation ratio) of the aromatic dihydroxy compound and high-purity diaryl carbonate in step (IV) varies depending on the type of aromatic dihydroxy compound and diaryl carbonate used, the polymerization temperature, and other polymerization conditions. It is used in a proportion of usually 0.9 to 2.5 mol, preferably 0.95 to 2.0 mol, more preferably 0.98 to 1.5 mol with respect to 1 mol of the aromatic dihydroxy compound.

  In the step (IV), a molten prepolymer produced from an aromatic dihydroxy compound and diaryl carbonate (hereinafter referred to as a molten prepolymer) is produced from an aromatic dihydroxy compound and diaryl carbonate. It means a melt in the middle of polymerization having a polymerization degree lower than that of an aromatic polycarbonate having a polymerization degree, and may of course be an oligomer. Such a melted prepolymer used in step (IV) may be obtained by any known method. For example, a molten mixture of a predetermined amount of an aromatic dihydroxy compound and diaryl carbonate is subjected to normal pressure and / or reduced pressure in a temperature range of about 120 ° C. to about 280 ° C. using one or more vertical stirring tanks. It can manufacture by removing the aromatic monohydroxy compound byproduced by reaction, stirring under. A method of continuously producing a melted prepolymer having a necessary degree of polymerization in which the degree of polymerization is sequentially increased using two or more vertical stirring tanks connected in series is particularly preferable.

  In the step (IV), the molten prepolymer is continuously supplied to a guide contact flow type polymerization reactor to continuously produce an aromatic polycarbonate having a desired degree of polymerization. The guide contact flow type polymerization apparatus is a polymerization apparatus in which a prepolymer is melted down along a guide to perform polymerization, and can produce 1 ton or more aromatic polycarbonate per hour.

The guide contact flow type polymerizer is:
(1) A molten prepolymer receiving port, a perforated plate, a molten prepolymer supply zone for supplying the molten prepolymer to the guide of the polymerization reaction zone through the perforated plate, the perforated plate, a side casing, and a tapered bottom casing A polymerization reaction zone in which a plurality of guides extending downward from the perforated plate are provided in a space surrounded by the porous plate, a vacuum vent port provided in the polymerization reaction zone, and an aromatic provided at the bottom of the tapered bottom casing A polycarbonate discharge port, and an aromatic polycarbonate discharge pump connected to the discharge port,
(2) The internal cross-sectional area A (m ² ) in the horizontal plane of the side casing of the polymerization reaction zone satisfies the formula (19),
0.7 ≦ A ≦ 300 Formula (19)
(3) The ratio of the A (m ² ) and the internal cross-sectional area B (m ² ) in the horizontal plane of the aromatic polycarbonate outlet satisfies the formula (20),
20 ≦ A / B ≦ 1000 Formula (20)
(4) The tapered bottom casing constituting the bottom of the polymerization reaction zone is connected to the upper side casing at an angle C degree inside, and the angle C degree satisfies the formula (21). To do,
120 ≦ C ≦ 165 Formula (21)
(5) The length h (cm) of the guide satisfies the formula (22),
150 ≦ h ≦ 5000 Formula (22)
(6) The external total surface area S (m ² ) of the entire guide satisfies the formula (23).
2 ≦ S ≦ 50000 Formula (23)
It is necessary.

  Polymerization that satisfies various conditions in order to produce high-quality, high-performance aromatic polycarbonate on an industrial scale with an output of 1 ton or more per hour with no variation in molecular weight and long-term stability. Therefore, the present invention has found these conditions. In the present invention, the absence of molecular weight variation means that the number average molecular weight is 200 or less. In the present invention, an aromatic polycarbonate having a number average molecular weight variation of preferably 150 or less, more preferably 100 or less, can be produced stably for a long time.

More specifically, as shown in the conceptual diagram (FIG. 5), the internal cross-sectional area A (m ² ) in the horizontal plane (aa ′ plane) of the side casing 10 of the polymerization reaction zone 5 is expressed by the formula (19). It is necessary to satisfy

When A is smaller than 0.7 m ² , the target production amount cannot be achieved, and in order to achieve this production amount while reducing the equipment cost, A needs to be 300 m ² or less.

Further, the and A ^{(m 2),} the ratio of the internal cross-sectional area B ^{(m 2)} in the horizontal plane of the aromatic polycarbonate discharge port 7 (b-b 'plane), it is necessary to satisfy the equation (20) .

  In order to discharge these melts having a high melt viscosity without degrading the quality of the produced aromatic polycarbonate or the aromatic polycarbonate prepolymer having an increased degree of polymerization, A / B satisfies the formula (20). Must be.

  Further, a tapered bottom casing 11 constituting the bottom of the polymerization reaction zone 5 is provided at an angle C degrees with respect to the upper side casing 10, and the angle C degrees is expressed by the formula (21). It is also necessary to satisfy

  In order to reduce the equipment cost, C should be as close to 90 degrees as possible. However, the quality of the aromatic polycarbonate falling from the lower end of the guide 4 or the aromatic polycarbonate prepolymer with an increased degree of polymerization should be reduced. In order to move these melts having a high melt viscosity to the discharge port 7 without being lowered, C must satisfy the formula (21).

  Further, it is necessary that the length h (cm) of the guide satisfies the formula (22). When h is shorter than 150 cm, the degree of polymerization of the melted prepolymer can be increased, but the degree is not sufficient, and the variation in the degree of polymerization increases by about 200 or more in number average molecular weight, which is not preferable. When h is longer than 5000 cm, the difference in the melt viscosity of the melted prepolymer between the upper and lower parts of the guide becomes too large, and the variation in the degree of polymerization is about 300 or more (in some cases, about 500 or more) in terms of number average molecular weight. Thus, the physical properties of the resulting aromatic polycarbonate vary, which is not preferable. In the present invention, the fact that the variation in the degree of polymerization is large means, for example, a variation in which there is a difference of about 200 or more, expressed by the number average molecular weight.

Furthermore, the external total surface area S (m ² ) of the guide 4 needs to satisfy the formula (23).
If S is less than 2 m ² , the target production volume cannot be achieved, and in order to achieve this production volume while reducing equipment costs, and to eliminate variations in physical properties, S should be 50000 m ² or less. is necessary.

  Surprisingly, by using a guide contact flow type polymerization reactor that simultaneously satisfies the formulas (19), (20), (21), (22) and (23), there is no coloration and high mechanical properties are excellent. High-quality, high-performance aromatic polycarbonate can be produced stably at a production rate of 1 ton or more per hour, and for a long period of several thousand hours or more, for example, 5,000 hours or more, with no variation in molecular weight. It was found. When these conditions are not satisfied at the same time, the desired production amount cannot be obtained, the variation in molecular weight is represented by a number average molecular weight, and there is a variation of about 200 or more, and stable production is 1,000. Inconveniences such as lack of time and easy coloration occur.

  In Step (IV), the reason why it is possible to produce an aromatic polycarbonate on an industrial scale having such an excellent effect is not clear, but in addition to the above-mentioned reasons, these conditions were combined. It is presumed that this is due to the emergence of complex effects that sometimes occur. For example, using a high surface area guide that satisfies equations (22) and (23), the molten prepolymer can be polymerized at a relatively low temperature, producing large quantities of high quality aromatic polycarbonate having the desired molecular weight. The tapered bottom casing that satisfies the equation (21) can be manufactured and can reduce the time for this large amount of high quality product aromatic polycarbonate falling from the guide to reach the outlet, This is presumed to reduce the thermal history of the produced aromatic polycarbonate.

  Such industrial-scale manufacturing technology can only be established by long-time operation using large-scale manufacturing equipment, but manufacturing equipment costs at that time are important factors to consider. , Do not wait for the argument. Another effect of the present invention is that the polymerization vessel used in step (IV) is a guide contact flow type polymerization vessel satisfying the formulas (19), (20), (21), (22) and (23). Therefore, the facility cost can be reduced as an industrial production facility.

The ranges required for dimensions, angles, etc. in the guide contact flow type polymerization reactor used in step (IV) are as described above, but more preferable ranges are as follows. A more preferable range of the internal cross-sectional area A (m ² ) in the horizontal plane of the side casing of the polymerization reaction zone is 0.8 ≦ A ≦ 250, and more preferably 1 ≦ A ≦ 200.

In addition, a more preferable range of the ratio of the A (m ² ) and the internal cross-sectional area B (m ² ) in the horizontal plane of the aromatic polycarbonate outlet is 25 ≦ A / B ≦ 900, and more preferably 30 ≦ A / B ≦ 800.

  Further, a more preferable range of the angle C degrees formed inside the tapered bottom casing constituting the bottom of the polymerization reaction zone with respect to the upper side casing is 125 ≦ C ≦ 160, and more preferably 135 ≦ C ≦ 165. In the case of increasing the degree of polymerization sequentially using a plurality of guide contact flow type polymerization apparatuses, assuming that the corresponding angles are C1, C2, C3,..., C1 ≦ C2 ≦ C3 ≦ It is preferable that

Also, the required length h (cm) of the guide depends on the factors such as the degree of polymerization of the raw material prepolymer, the polymerization temperature and pressure, the degree of polymerization of the aromatic polycarbonate or prepolymer to be produced in the polymerization vessel, and the production amount. More preferably, the range is more preferably 200 ≦ h ≦ 3000, and more preferably 250 ≦ h ≦ 2500. It is particularly preferable when h satisfies the formula (31).
400 <h ≦ 2500 Formula (31)

The required total external surface area S (m ² ) of the entire guide also varies depending on the same factors as described above, but a more preferable range is 4 ≦ S ≦ 40000, and more preferably 10 ≦ S ≦ 30000. is there. 15 ≦ S ≦ 20000 is a particularly preferable range. The external total surface area of the entire guide referred to in the present invention means the entire surface area of the guide in which the molten prepolymer contacts and flows down. For example, in the case of a guide such as a pipe, it means the outer surface area. The surface area of the inner surface of the pipe that does not allow the prepolymer to flow down is not included.

In the guide contact flow type polymerization reactor used in step (IV), the shape of the internal cross section in the horizontal plane of the side casing of the polymerization reaction zone may be any shape such as a polygon, an ellipse, and a circle. Since the polymerization reaction zone is usually operated under reduced pressure, it may be anything that can withstand it, but it is preferably in the case of a circular shape or a shape close thereto. Therefore, the side casing of the polymerization reaction zone of the present invention is preferably cylindrical. In this case, it is preferable that a tapered bottom casing is connected to the lower part of the cylindrical side casing, and a cylindrical aromatic polycarbonate discharge port is provided at the lowermost part of the bottom casing. When the inner diameter of the cylindrical portion of the side casing is D (cm), the length is L (cm), and the inner diameter of the discharge port is d (cm), D, L, and d are expressed by the formula (27). , (28), (29) and (30) are preferably satisfied.
100 ≦ D ≦ 1800 Formula (27)
5 ≦ D / d ≦ 50 Formula (28)
0.5 ≦ L / D ≦ 30 Formula (29)
h−20 ≦ L ≦ h + 300 Formula (30)

  In the guide contact flow type polymerization reactor, a more preferable range of D (cm) is 150 ≦ D ≦ 1500, and further preferably 200 ≦ D ≦ 1200. Moreover, the more preferable range of D / d is 6 ≦ D / d ≦ 45, and further preferably 7 ≦ D / d ≦ 40. Further, a more preferable range of L / D is 0.6 ≦ L / D ≦ 25, and more preferably 0.7 ≦ L / D ≦ 20. Further, a more preferable range of L (cm) is h-10 ≦ L ≦ h + 250, and more preferably h ≦ L ≦ h + 200. If D, d, L, and h do not satisfy these relationships at the same time, it is difficult to achieve the object of the present invention.

  The exact reason why high-quality, high-performance aromatic polycarbonate with high polymerization rate, no coloration, and excellent mechanical properties can be stably produced on the industrial scale without long-term molecular weight variation in step (IV) Although it is not clear, the following can be considered. That is, in the guide contact flow-down polymerization method of step (IV), the raw material melted prepolymer is guided from the receiving port 1 to the guide 4 via the supply zone 3 and the perforated plate 2 and flows down along the guide. However, the degree of polymerization increases. In this case, since the molten prepolymer flows down along the guide, effective internal stirring and surface renewal are performed, and phenol and the like are effectively extracted, so that the polymerization proceeds at a high speed. As the polymerization proceeds, the melt viscosity becomes higher, so that the adhesive force to the guide increases, and the amount of the melt adhering to the guide increases as it goes to the lower part of the guide. This means that the residence time of the molten prepolymer on the guide, that is, the polymerization reaction time is increased. In addition, the melted prepolymer flowing down under its own weight while being supported by the guide has a very large surface area per mass and its surface is renewed efficiently. High molecular weight in the latter half of the polymerization, which was impossible, can be easily achieved. This is one of the excellent features of the polymerization vessel used in step (IV).

  In the latter half of the polymerization below the middle part of the guide, the amount of melt adhering to the guide increases, but there is only an adhesive holding force that matches the melt viscosity, so at the same height of multiple guides, Approximately the same amount of melt with the same melt viscosity will be supported by each guide. On the other hand, since the melt is continuously supplied to the guide from the top, the melt having an approximately the same melt viscosity and having a high polymerization degree continuously falls from the lower end of the guide to the tapered bottom casing. Will go. That is, at the bottom of the taper-shaped bottom casing, aromatic polycarbonate having substantially the same polymerization degree generated while flowing down the guide accumulates, and it is possible to continuously produce aromatic polycarbonate with no variation in molecular weight. . This is one of the other excellent features of the polymerizer of the present invention. The aromatic polycarbonate accumulated in the bottom of the tapered bottom casing is continuously extracted by the discharge pump 8 through the discharge port 7, and is usually continuously pelletized through an extruder. In this case, it is also possible to add additives such as stabilizers and weathering agents with an extruder.

The perforated plate constituting the guide contact flow type polymerization reactor used in the step (IV) is usually selected from a flat plate, a corrugated plate, a plate having a thick central portion, and the shape of the perforated plate is usually circular. , Oval, triangular, polygonal and other shapes. The holes of the perforated plate are usually selected from shapes such as a circle, an ellipse, a triangle, a slit, a polygon, and a star. Cross-sectional area of the hole is usually 0.01～100Cm ^2, preferably 0.05～10Cm ^2, particularly preferably from 0.1 to 5 cm ^2. The distance between the holes is usually 1 to 500 mm, preferably 25 to 100 mm, as the distance between the centers of the holes. The hole of the porous plate may be a hole penetrating the porous plate or may be a case where a tube is attached to the porous plate. Further, it may be tapered.

  Further, the guide constituting the guide contact flow type polymerizer used in the step (IV) is a material having a very large ratio of the length in the vertical direction to the average length of the outer periphery of the horizontal cross section. It represents. The ratio is usually in the range of 10 to 1,000,000, preferably in the range of 50 to 100,000. The shape of the cross section in the horizontal direction is usually selected from shapes such as a circle, an oval, a triangle, a quadrangle, a polygon, and a star. The shape of the cross section may be the same or different in the length direction. The guide may be hollow.

  The guide may be a single guide such as a wire-like one, a thin rod-like one, or a thin pipe-like one that prevents molten prepolymer from entering inside, but it may be a combination of multiple guides such as twisting together. Good. Moreover, a net-like thing or a punching plate-like thing may be sufficient. The surface of the guide may be smooth or uneven, and may partially have protrusions or the like. Preferable guides are a cylindrical shape such as a wire shape or a thin rod shape, a net shape such as the above-mentioned thin pipe shape, or a punching plate shape.

  This guide may have a heating source such as a heat medium or an electric heater inside itself, but a guide without a heating source is particularly preferable because there is no concern about thermal denaturation of the prepolymer or aromatic polycarbonate on its surface. .

  In the guide contact flow type polymerization apparatus of the present invention that enables the production of high-quality aromatic polycarbonate on an industrial scale (production amount, long-term stable production, etc.), it is particularly preferable that a plurality of wire-like or thin rod-like or This is a guide of the type in which the guides are coupled at appropriate intervals in the vertical direction using a support material in the horizontal direction from the upper part to the lower part of the thin pipe-shaped guide. For example, a plurality of wire-shaped or thin rod-shaped guides or a wire net-like guide fixed at an appropriate vertical distance, for example, 1 cm to 200 cm, using a support material in the horizontal direction from the upper part to the lower part of the thin pipe-shaped guide. A three-dimensional guide in which a plurality of wire net-like guides are arranged at the front and back and they are combined at a suitable vertical distance, for example, 1 cm to 200 cm using a lateral support material, or a plurality of wire-like guides or thin It is a three-dimensional guide in the form of a jungle gym in which the front and rear, left and right of the rod-shaped or thin pipe-shaped guide are fixed at an appropriate vertical interval, for example, 1 cm to 200 cm, using a lateral support material. The support material in the lateral direction not only helps to keep the distance between the guides substantially the same, but also helps to strengthen the strength of the guide that becomes flat or curved as a whole, or the guide that becomes three-dimensional. These supporting materials may be the same material as the guide, or may be different.

In the guide contact flow type polymerization apparatus, when one guide is a cylindrical shape having an outer diameter r (cm) or a pipe shape in which no molten prepolymer is inserted inside, r 1 satisfies the formula (32). It is preferable.
0.1 ≦ r ≦ 1 Formula (32)

  This guide advances the polymerization reaction while causing the molten prepolymer to flow down, but also has a function of holding the molten prepolymer for a certain period of time. This holding time is related to the polymerization reaction time. As the polymerization proceeds, the melt viscosity increases, and as described above, the holding time and the holding amount increase. The amount that the guide retains the molten prepolymer varies depending on the outer surface area of the guide, that is, the outer diameter in the case of a cylinder or pipe, even if the melt viscosity is the same.

  Further, the guide installed in the polymerization vessel of the present invention needs to be strong enough to support the weight of the molten prepolymer being held in addition to the weight of the guide itself. In this sense, the thickness of the guide is important. In the case of a columnar shape or a pipe shape, it is preferable that the formula (32) is satisfied. When r is smaller than 0.1, it becomes difficult to perform stable operation for a long time in terms of strength. If r is greater than 1, the guides themselves become very heavy and not only have the disadvantage that the thickness of the perforated plates has to be very large in order to hold them in the polymerization vessel, but also the molten prepolymer Inconvenient problems such as an increase in the amount of excessively retained amount and an increase in molecular weight variation occur. In this sense, a more preferable range of r is 0.15 ≦ r ≦ 0.8, and a more preferable range is 0.2 ≦ r ≦ 0.6.

  A preferable material for such a guide is selected from metals such as stainless steel, carbon steel, hastelloy, nickel, titanium, chromium, aluminum and other alloys, and a polymer material having high heat resistance. Particularly preferred is stainless steel. In addition, the surface of the guide may be subjected to various treatments such as plating, lining, passivation treatment, acid washing, and phenol washing as necessary.

  The positional relationship between the guide and the perforated plate and the positional relationship between the guide and the hole in the perforated plate are not particularly limited as long as the molten prepolymer can flow under the guide contact. The guide and the porous plate may be in contact with each other or may not be in contact. The guide is preferably installed in correspondence with the holes of the perforated plate, but is not limited thereto. This is because the molten prepolymer falling from the perforated plate may be designed to contact the guide at an appropriate position. As a preferable specific example of installing the guide corresponding to the hole of the perforated plate, (1) the upper end of the guide is fixed to the upper inner wall surface of the polymerization vessel, and the guide penetrates near the center of the hole of the perforated plate (2) a method of providing a guide in a state where the guide is passed through the hole of the porous plate, and (2) a method of providing the guide in a state where the guide is penetrated through the hole of the porous plate. Examples include a method of fixing the upper end of the guide to the lower surface of the perforated plate.

  As a method of flowing down the molten prepolymer along the guide through the perforated plate, a method of flowing down with a liquid head or its own weight, or extruding the molten prepolymer from the perforated plate by applying pressure using a pump or the like, etc. The method is mentioned. Preferably, a predetermined amount of the raw melt prepolymer is supplied to the supply zone of the polymerization vessel under pressure using a supply pump, and the molten prepolymer guided to the guide through the perforated plate flows down along the guide under its own weight. It is a method to go. The molten prepolymer is usually continuously fed to the guide contact flow type polymerization apparatus while being heated to a predetermined polymerization temperature. Therefore, it is preferable that a jacket or the like is usually installed on the outer wall surface of the guide contact flow type polymerization reactor, and it is preferable to heat the jacket to a predetermined temperature through a heating medium or the like. This preferably heats and / or keeps the molten prepolymer and the prepolymer supply zone and perforated plate, and keeps the polymerization reaction zone, the side casing and the tapered bottom casing.

  In step (IV), the temperature of the reaction for producing an aromatic polycarbonate by polymerizing a molten prepolymer obtained from an aromatic dihydroxy compound and diaryl carbonate in a guide contact flow type polymerization reactor is usually in the range of 80 to 350 ° C. is there. However, in the polymerization apparatus of the present invention, since efficient surface renewal with internal stirring is performed, the polymerization reaction can proceed at a relatively low temperature. Therefore, the preferable reaction temperature is 100 to 290 ° C, and more preferably 150 to 270 ° C. In a conventional reactor for horizontal biaxial stirring type ultra-high viscosity polymer, which is a conventional polymerization vessel, it was necessary to stir for a long time under a high vacuum of 133 Pa or less, usually at a high temperature of 300 ° C. or higher. Moreover, yellowing due to air leakage from the agitation shaft seal and contamination with foreign substances were not avoided. Since the polymerization apparatus of the present invention does not have mechanical stirring, there is no seal part of the stirrer, so that leakage of air or the like is very small. Moreover, it is a feature of the present invention that the polymerization can be sufficiently carried out at a temperature as low as about 20 to 50 ° C. as compared with the case of the conventional horizontal biaxially stirred ultrahigh viscosity polymer reactor. This is also a major reason why it is possible to produce a high-quality aromatic polycarbonate that is free from coloring and physical property degradation.

  Moreover, even if a conventional horizontal biaxial agitation type reactor for ultra-high viscosity polymer is used, it is impossible to produce an aromatic polycarbonate having a medium viscosity grade or higher because of its ultra-high viscosity. High viscosity grade aromatic polycarbonates can be easily produced in the guide contact flow type polymerizer. That is, in the guided contact flow type polymerization apparatus of the present invention, it is possible to produce all grades of aromatic polycarbonate from a disk grade having a relatively low molecular weight to a high viscosity grade. This is also a major feature of the present invention.

  In step (IV), an aromatic monohydroxy compound is produced with the progress of the polymerization reaction, and the reaction rate is increased by removing this from the reaction system. Therefore, an inert gas that does not adversely influence the reaction, such as nitrogen, argon, helium, carbon dioxide or lower hydrocarbon gas, is introduced into the polymerization vessel, and the aromatic monohydroxy compound produced is entrained in these gases. For example, a method that removes the reaction or a method in which the reaction is performed under reduced pressure is preferably used. Alternatively, a method using these in combination is also preferably used, but in these cases as well, it is not necessary to introduce a large amount of inert gas into the polymerization vessel, and the inside may be maintained at an inert gas atmosphere.

  It is also preferable to absorb the inert gas and then polymerize the inert gas-absorbing molten prepolymer before supplying the molten prepolymer to the guide contact flow type polymerization reactor.

  The preferred reaction pressure in the polymerization vessel in the step (IV) varies depending on the type, molecular weight, polymerization temperature, etc. of the aromatic polycarbonate to be produced. For example, the aromatic polycarbonate is produced from a molten prepolymer from bisphenol A and diphenyl carbonate. In this case, the range of 400 to 3,000 Pa is preferable when the number average molecular weight is 5,000 or less, and the range of 50 to 500 Pa is preferable when the number average molecular weight is 5,000 to 10,000. When the number average molecular weight is 10,000 or more, 300 Pa or less is preferable, and a range of 20 to 250 Pa is particularly preferable.

  In carrying out the step (IV), it is possible to produce an aromatic polycarbonate having the desired degree of polymerization with only one guide contact flow type polymerizer, but the degree of polymerization of the molten prepolymer used as a raw material Depending on the production amount of the aromatic polycarbonate, a system in which two or more guide contact flow type polymerization reactors are connected and the degree of polymerization is sequentially increased is also preferable. In this case, it is a preferable method because guides and reaction conditions suitable for the degree of polymerization of the prepolymer or aromatic polycarbonate to be produced can be adopted separately in each polymerization vessel. For example, a guide contact flow type first polymerization device, a guide contact flow type second polymerization device, a guide contact flow type third polymerization device, a guide contact flow type fourth polymerization device,... If the total external surface area of the entire guide of each polymerizer is S1, S2, S3, S4,..., Then S1 ≧ S2 ≧ S3 ≧ S4 ≧ ... it can. Also, the polymerization temperature may be the same in each polymerization vessel, or may be raised in order. It is also possible to lower the polymerization pressure in each polymerization vessel in order.

In this sense, for example, when the polymerization degree is increased in this order using two polymerizers of a guide contact flow type first polymerization device and a guide contact flow type second polymerization device, It is preferable to use a guide in which the external total surface area S1 (m ² ) of the entire guide and the external total surface area S2 (m ² ) of the entire guide of the second polymerization vessel satisfy the formula (33).
1 ≦ S1 / S2 ≦ 20 Formula (33)

  When S1 / S2 is smaller than 1, there are inconveniences such as large variations in molecular weight, making stable production difficult for a long period of time, and difficulty in obtaining a predetermined production amount. When S1 / S2 is larger than 20, 2 The flow rate of the molten prepolymer flowing down the guide in the polymerization vessel is increased, resulting in inconvenience that the residence time of the molten prepolymer is reduced and it becomes difficult to obtain an aromatic polycarbonate having the required molecular weight. come. In this sense, a more preferable range is 1.5 ≦ S1 / S2 ≦ 15.

  In step (IV), an aromatic polycarbonate of 1 ton or more per hour is produced, but since the aromatic monohydroxy compound by-produced by the polymerization reaction is discharged out of the system, from 1 ton per hour A large amount of molten prepolymer needs to be fed to the polymerization vessel. Accordingly, the amount of the melted prepolymer to be supplied varies depending on the degree of polymerization and the degree of polymerization of the aromatic polycarbonate to be produced, but is usually 10 to 500 kg / hr higher per 1 ton / hr of the production of the aromatic polycarbonate. 1.01 to 1.5 tons / hr.

The reaction for producing an aromatic polycarbonate from the aromatic dihydroxy compound and diaryl carbonate in the step (IV) can be carried out without adding a catalyst, but is performed in the presence of a catalyst as necessary in order to increase the polymerization rate. . The catalyst is not particularly limited as long as it is used in this field, but alkali metal and alkaline earth metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, and calcium hydroxide. Alkali metal salts, alkaline earth metal salts, quaternary ammonium salts of hydrides of boron and aluminum such as lithium aluminum hydride, sodium borohydride, tetramethylammonium borohydride; lithium hydride, sodium hydride, Alkali metal and alkaline earth metal hydrogen compounds such as calcium hydride; Alkali metal and alkaline earth metal alkoxides such as lithium methoxide, sodium ethoxide, calcium methoxide; lithium phenoxide, sodium phenoxide, magnesium phenoxide, Alyloxides of alkali metals and alkaline earth metals such as iO—Ar—OLi and NaO—Ar—ONa (Ar is an aryl group); organics of alkali metals and alkaline earth metals such as lithium acetate, calcium acetate and sodium benzoate Acid salts; zinc compounds such as zinc oxide, zinc acetate, zinc phenoxide; boron oxide, boric acid, sodium borate, trimethyl borate, tributyl borate, triphenyl borate, (R ¹ R ² R ³ R ⁴ ) Ammonium borates or phosphonium borates (R ¹ , R ² ) represented by NB (R ¹ R ² R ³ R ⁴ ) or (R ¹ R ² R ³ R ⁴ ) PB (R ¹ R ² R ³ R ⁴ ) , R ^3, R ⁴ is described under the formula) compounds of boron and the like;. silicon oxide, sodium silicate, Tetoraaru Silicon compounds such as silicon, tetraarylsilicon, diphenyl-ethyl-ethoxysilicon; germanium compounds such as germanium oxide, germanium tetrachloride, germanium ethoxide, germanium phenoxide; tin oxide, dialkyltin oxide, dialkyltin carboxy Rate, tin compounds such as tin acetate, ethyltin tributoxide, tin compounds bonded to alkoxyl or aryloxy groups, tin compounds such as organic tin compounds; lead oxide, lead acetate, lead carbonate, basic carbonate, lead and organic lead Lead compounds such as alkoxides or aryloxides; onium compounds such as quaternary ammonium salts, quaternary phosphonium salts and quaternary arsonium salts; antimony compounds such as antimony oxide and antimony acetate; manganese acetate and charcoal Manganese compounds such as manganese oxide and manganese borate; Titanium compounds such as titanium oxide, titanium alkoxide or aryloxide; Zirconium compounds such as zirconium acetate, zirconium oxide, zirconium alkoxide or aryloxide, zirconium acetylacetone, etc. Mention may be made of catalysts.

When using a catalyst, these catalysts may be used only by 1 type and may be used in combination of 2 or more type. The amount of these catalysts, the aromatic dihydroxy compound of the raw material, usually ^{10 -10} to 1 wt%, preferably ¹⁰ -9 ^{to 10 -1} wt%, more preferably ¹⁰ -8 to 10 ^- It is selected in the range of ² % by mass. In the case of the melt transesterification method, the polymerization catalyst used remains in the aromatic polycarbonate of the product, but these polymerization catalysts usually have an adverse effect on polymer properties. Therefore, it is preferable to reduce the amount of the catalyst used as much as possible. In the method of the present invention, since the polymerization can be carried out efficiently, the amount of catalyst used can be reduced. This is also one of the features of the present invention that can produce high-quality aromatic polycarbonate.

  There are no particular restrictions on the material of the guide contact flow type polymerizer or piping used in step (IV), and usually stainless steel, carbon steel, hastelloy, nickel, titanium, chromium, other alloys, etc. Selected from the above metals and polymer materials with high heat resistance. In addition, the surface of these materials may be subjected to various treatments such as plating, lining, passivation treatment, acid washing, and phenol washing as necessary. Particularly preferred are stainless steel, nickel, glass lining and the like.

During the production of the prepolymer in step (IV) and during polymerization in the guide contact flow type polymerization apparatus, a large amount of aromatic monohydroxy compound by-produced by the reaction is usually withdrawn continuously in a gaseous state and condensed into a liquid state. And recovered. In this invention, it is necessary to perform the recycling process (V) of the aromatic monohydroxy compound which circulates the aromatic monohydroxy compound by-produced in the process (IV) to the diaryl carbonate production process (II). In the industrial production method, it is important to recover the by-product aromatic monohydroxy compound in the whole amount or with as little loss as possible, and to circulate and reuse it. The by-product aromatic monohydroxy compound by-produced and recovered in the step (IV) of the present invention usually contains a part of diaryl carbonate. However, since the purity is high, it remains in the diaryl carbonate production step (II) as it is. It can also be recycled and reused. In addition, when a small amount of aromatic dihydroxy compound or a small amount of oligomer is mixed in the recovered aromatic monohydroxy compound, after distilling to remove these high-boiling substances, a diaryl carbonate production process It is preferable to circulate and reuse in (II).
The aromatic polycarbonate produced by carrying out the system of the present invention has a repeating unit represented by the following chemical formula 9.

(In the formula, Ar is the same as described above.)
Particularly preferred is an aromatic polycarbonate containing 85 mol% or more of a repeating unit represented by the following chemical formula 10 among all repeating units.

  Moreover, the terminal group of the aromatic polycarbonate manufactured by implementing the method of this invention consists of the aryl carbonate group normally shown by a hydroxyl group or a following formula.

(In the formula, Ar ⁵ is the same as Ar ³ and Ar ⁴ described above.)
Although there is no restriction | limiting in particular in the ratio of a hydroxy group and an aryl carbonate group, Usually, it is the range of 95: 5-5: 95, Preferably it is the range of 90: 10-10: 90, More preferably, it is 80: 20-20 : 80 range. Particularly preferred is an aromatic polycarbonate in which the proportion of phenyl carbonate groups in the terminal groups is 60 mol% or more.

  The aromatic polycarbonate produced by carrying out the method of the present invention may be partially branched with respect to the main chain via a hetero bond such as an ester bond or an ether bond. The amount of the heterogeneous bond is usually 0.005 to 2 mol%, preferably 0.01 to 1 mol%, more preferably 0.05 to 0.5 mol, based on the carbonate bond. %. This amount of dissimilar bonds improves flow characteristics during melt molding without deteriorating other polymer properties, making it suitable for precision molding and molding at relatively low temperatures, with excellent performance. Can be manufactured. The molding cycle can also be shortened, contributing to energy saving during molding.

  The aromatic polycarbonate produced by carrying out the method of the present invention contains almost no impurities, but contains an aromatic metal and / or alkaline earth metal as a metal element of 0.001 to 1 ppm. A group polycarbonate can be produced. Preferably, this content is 0.005 to 0.5 ppm, more preferably 0.01 to 0.1 ppm. When such a metal element is 1 ppm or less, preferably 0.5 ppm or less, more preferably 0.1 ppm, the physical properties of the product aromatic polycarbonate are not adversely affected. Is high quality.

  Particularly preferred among the aromatic polycarbonates produced by carrying out the method of the present invention are those produced by using a halogen-free aromatic dihydroxy compound and diaryl carbonate, and the halogen content is usually 10 ppb or less. In the method of the present invention, those having a halogen content of 5 ppb or less can be produced, and more preferably aromatic polycarbonates having a halogen content of 1 ppb or less can be produced, so that a very high quality product can be obtained. become.

  It is apparent from the examples that the method of the present invention can produce an aromatic polycarbonate having no variation in molecular weight stably for a long time because a specific polymerizer is used.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.
Number average molecular weight (Mn): Measured by gel permeation chromatography (GPC) using tetrahydrofuran as a carrier solvent, number average molecular weight using a converted molecular weight calibration curve according to the following formula obtained using standard monodisperse polystyrene (Mn) was determined.
M _PC = 0.3591 M _PS ^1.0388
_{(Wherein, M PC} molecular weight of the aromatic _{polycarbonate, M PS} represents the molecular weight of the polystyrene.)
Color: Using an injection molding machine, a test piece having a length of 50 mm, a width of 50 mm, and a thickness of 3.2 mm was continuously molded from an aromatic polycarbonate at a cylinder temperature of 290 ° C. and a mold temperature of 90 ° C. The color tone of the obtained test piece was measured by the CIELAB method (Commission Internationale de l'Eclairage 1976 Lab Diagram), and the yellowness was indicated by b ^* value.
Tensile elongation: An aromatic polycarbonate was injection molded at a cylinder temperature of 290 ° C. and a mold temperature of 90 ° C. using an injection molding machine. The tensile elongation (%) of the obtained specimen having a thickness of 3.2 mm was measured according to ASTM D638.
The amount of heterogeneous bond was measured by the method described in WO97 / 32916, alkali metal / alkaline earth metal was measured by the ICP method, and halogen was measured by the ion chromatography method.

[Example 1]
(1) Step of continuously producing dimethyl carbonate and ethylene glycol (I)
<Continuous multi-stage distillation column _T 0>
As shown in FIG. 1, L ₀ = 3300 cm, D ₀ = 300 cm, L ₀ / D ₀ = 11, n ₀ = 60, D ₀ / d ₀₁ = 7.5, D ₀ / d ₀₂ = 12 A multistage distillation column was used. In this example, a perforated plate tray having a cross-sectional area per hole of the perforated plate portion = about 1.3 cm ² and a number of holes = about 180 to 320 / m ² was used as an internal.
<Reactive distillation>
Ethylene carbonate 3.27 tons / hr of a liquid form was continuously introduced the installed inlets at the 55 th stage from the bottom of (3-a) into the distillation column T _0. Gaseous methanol (containing 8.96% by mass of dimethyl carbonate) 3.238 ton / hr and liquid methanol (containing 6.66% by mass of dimethyl carbonate) 7.489 ton / hr It was continuously introduced into the distillation column T ₀ from the installed inlets (3-b and 3-c). The molar ratio of the starting materials introduced into the distillation column T ₀ was methanol / ethylene carbonate = 8.36.
As a catalyst, 4.8 tons of ethylene glycol was added to 2.5 tons of KOH (48 mass% aqueous solution), heated to about 130 ° C., gradually reduced in pressure, and heat-treated at about 1300 Pa for about 3 hours to obtain a uniform solution. A thing was used. The catalyst solution, from the introduction port provided in 54 stage from the bottom (3-e), was continuously introduced into the distillation column T ₀ (K concentration: 0.1 wt% relative to the feed ethylene carbonate). Reactive distillation was continuously carried out under the conditions that the temperature at the bottom of the column was 98 ° C., the pressure at the top of the column was about 1.118 × 10 ⁵ Pa, and the reflux ratio was 0.42.

  After 24 hours, stable steady operation was achieved. The low boiling point reaction mixture withdrawn in the form of gas from the top 1 of the column was cooled with a heat exchanger to be liquid. The dimethyl carbonate in the liquid low boiling point reaction mixture continuously extracted from the distillation column at 10.678 tons / hr was 4.129 tons / hr and methanol was 6.549 tons / hr. In the liquid continuously withdrawn from the tower bottom 2 at 3.382 tons / hr, ethylene glycol is 2.356 tons / hr, methanol is 1.014 tons / hr, and unreacted ethylene carbonate is 4 kg / hr. Met. Excluding dimethyl carbonate contained in the raw material, the actual production amount per hour of dimethyl carbonate was 3.340 tons, and the actual production amount of ethylene glycol per hour excluding ethylene glycol contained in the catalyst solution was 2. It was 301 tons. The reaction rate of ethylene carbonate was 99.88%, the selectivity of dimethyl carbonate was 99.99% or more, and the selectivity of ethylene glycol was 99.99% or more.

  Long-term continuous operation was performed under these conditions. After 500 hours, 2000 hours, 4000 hours, 5000 hours, and 6000 hours, the actual production amount per hour is as follows: dimethyl carbonate 3.340 tons, 3.340 tons, 3.340 tons, 3.340 tons Ton, 3.340 ton, ethylene glycol is 2.301 ton, 2.301 ton, 2.301 ton, 2.301 ton, 2.301 ton, and the reaction rate of ethylene carbonate is 99.90%, 99 .89%, 99.89%, 99.88%, 99.88%, and the selectivity of dimethyl carbonate is 99.99% or more, 99.99% or more, 99.99% or more, 99.99% or more The selectivity of ethylene glycol was 99.99% or more, 99.99% or more, 99.99% or more, 99.99% or more, 99.99% or more.

(2) Step of continuously producing diphenyl carbonate (II)
<First continuous multistage distillation column 101>
As shown in FIG. 2, L ₁ = 3300 cm, D ₁ = 500 cm, L ₁ / D ₁ = 6.6, n ₁ = 80, D ₁ / d ₁₁ = 17, D ₁ / d ₁₂ = 9 A multistage distillation column was used. In this example, a perforated plate tray having a cross-sectional area per hole = about 1.5 cm ² and the number of holes = about 250 holes / m ² was used as an internal.
<Second continuous multistage distillation column 201>
L ₂ = 3100 cm, D ₂ = 500 cm, L ₂ / D ₂ = 6.2, n ₂ = 30, D ₂ / d ₂₁ = 3.85, D ₂ / d ₂₂ = 11. A continuous multistage distillation column 1 was used. In this embodiment, as the internal, two melapacks (total theoretical plate number: 11) are installed in the upper part, and the cross-sectional area per hole = about 1.3 cm ² and the number of holes = about 250 / A perforated plate tray having m ² was used.

<Reactive distillation>
Diphenyl carbonate was produced by performing reactive distillation using an apparatus in which the first continuous multistage distillation column 101 and the second continuous multistage distillation column 201 were connected as shown in FIG.
Raw material 1 composed of phenol / dimethyl carbonate = 1.9 (weight ratio) was continuously introduced in liquid form at a flow rate of 50 tons / hr from the upper inlet 11 of the first continuous multistage distillation column 101. On the other hand, the raw material 2 consisting of dimethyl carbonate / phenol = 3.6 (weight ratio) was continuously introduced in a gaseous state from the lower inlet 12 of the first continuous multistage distillation column 101 at a flow rate of 50 tons / hr. The molar ratio of the raw material introduced into the first continuous multistage distillation column 101 was dimethyl carbonate / phenol = 1.35. This raw material contained substantially no halogen (1 ppb or less outside the detection limit in ion chromatography). The catalyst was introduced as Pb (OPh) ₂ from the upper inlet 11 of the first continuous multistage distillation column 101 so as to be about 100 ppm in the reaction solution. In the first continuous multistage distillation column 101, the reactive distillation was continuously performed under the conditions that the temperature at the bottom of the column was 225 ° C. and the pressure at the top of the column was 7 × 10 ⁵ Pa. The first tower low boiling point reaction mixture containing methyl alcohol, dimethyl carbonate, phenol and the like is continuously withdrawn from the top 13 of the first tower in the form of a gas, passed through the heat exchanger 14 and 34 tons / hr from the outlet 16. Extracted at flow rate. On the other hand, the first tower high boiling point reaction mixture containing methylphenyl carbonate, dimethyl carbonate, phenol, diphenyl carbonate, catalyst and the like was continuously extracted in liquid form from the first tower bottom 17.

Since a stable steady state was reached after 24 hours, the first tower high-boiling point reaction mixture was directly taken from the raw material inlet 21 installed between the melapack and the perforated plate tray of the second continuous multistage distillation tower 201. It was continuously supplied at a flow rate of ton / hr. The liquid supplied to the second continuous multistage distillation column 201 contained 18.2% by mass of methylphenyl carbonate and 0.8% by mass of diphenyl carbonate. In the second continuous multi-stage distillation column 201, the reactive distillation was continuously performed under the conditions that the temperature at the bottom of the column was 210 ° C., the pressure at the top of the column was 3 × 10 ⁴ Pa, and the reflux ratio was 0.3. After 24 hours, stable steady operation was achieved. The second tower low boiling point reaction mixture containing 35% by mass of dimethyl carbonate and 56% by mass of phenol was continuously withdrawn from the top 23 of the second column, and the flow rate at the outlet 26 was 55.6 tons / hr. The second tower high boiling point reaction mixture containing 38.4% by mass of methylphenyl carbonate and 55.6% by mass of diphenyl carbonate was continuously extracted from the bottom 27 of the second column. The second column low boiling point reaction mixture was continuously supplied from the inlet 11 to the first continuous multistage distillation column 101. At this time, the amount of dimethyl carbonate and phenol to be newly supplied was adjusted so as to maintain the composition and amount of the raw material 1 and the raw material 2 in consideration of the composition and amount of the second tower low boiling point reaction mixture. . The production amount of diphenyl carbonate was found to be 5.74 tons per hour. The selectivity for diphenyl carbonate with respect to the reacted phenol was 98%.

  Long-term continuous operation was performed under these conditions. After 500 hours, 2000 hours, 4000 hours, 5000 hours, and 6000 hours, the production amount of diphenyl carbonate (excluding diphenyl carbonate contained in the raw material) is 5.74 tons and 5.75 tons per hour. It was 5.74 tons, 5.74 tons, and 5.75 tons, and the selectivity was 98%, 98%, 98%, 98%, 98%, and was very stable. Moreover, the produced aromatic carbonate contained substantially no halogen (1 ppb or less).

(3) Step of obtaining high-purity diphenyl carbonate (III)
The second high boiling point reaction mixture withdrawn from the bottom of the second continuous multistage distillation column is continuously fed to a high boiling point material separation column (length 1700 cm, inner diameter 340 cm, 30 stages), and the temperature at the bottom of the column Distillation was continuously performed at 206 ° C., a pressure at the top of the column of 3800 Pa, and a reflux ratio of 0.6. A diaryl carbonate purification tower having a side cut outlet (length 2200 cm, inner diameter 280 cm, 12 stages above the inlet, introduced as it is, with the tower top component continuously extracted from the tower top of the high boiling point material separating tower being introduced. It was continuously supplied to the introduction port of 18 stages between the mouth and the side cut mouth installed at the lower part thereof and 5 stages below the side cut mouth. In the diaryl carbonate purification tower, distillation was continuously carried out at a tower bottom temperature of 213 ° C., a tower top pressure of 5000 Pa, and a reflux ratio of 1.5. The purity of the diphenyl carbonate continuously extracted from the side cut outlet was 99.999% or more and the halogen content was 1 ppb or less.
The high-purity diphenyl carbonate thus obtained was once stored in a molten state in a storage tank.

(4) Process for producing high-quality aromatic polycarbonate (IV)
An aromatic polycarbonate was produced using a guide contact flow type polymerization apparatus as shown in FIG. The material of this polymerization vessel is all stainless steel. This polymerization vessel has a cylindrical casing and a cone portion, and L = 1,000 cm, h = 900 cm, D = 500 cm, d = 40 cm, C = 155 degrees, and S = 250 m ² . The molten polymer supplied from the supply port 1 is uniformly distributed to each guide 4 by the perforated plate 2. An inert gas supply port 9 is provided at the lower part of the polymerization vessel, and a vacuum vent port 6 is provided at the upper part. The outside of the polymerization vessel is a jacket and is heated by a heat medium.
A melt prepolymer (number average molecular weight Mn is 4,000) of aromatic polycarbonate maintained at 260 ° C. produced from bisphenol A and the high-purity diphenyl carbonate (molar ratio of bisphenol A to 1.05) is a feed pump. Thus, the water was continuously supplied from the supply port 1 to the supply zone 3. The molten prepolymer, which was continuously supplied to the polymerization reaction zone 5 through the perforated plate 2 in the polymerization vessel, proceeded with the polymerization reaction while flowing down along the guide 4. The polymerization reaction zone is maintained at 80 Pa through the vacuum vent 6. The produced aromatic polycarbonate that has entered the bottom 11 of the polymerization vessel from the lower part of the guide 4 is continuously fed at a flow rate of 5.5 tons / hr from the discharge port 7 by the discharge pump 8 so that the amount at the bottom is constant. Extracted.

The number average molecular weight Mn of the aromatic polycarbonate extracted from the extraction port 12 after 50 hours from the start of the operation was 10,500, which was a good color (b ^* value 3.2). The tensile elongation was 98%. 60 hours, 100 hours, 500 hours, 1,000 hours, 2,000 hours, 3,000 hours, 4,000 hours, 5,000 hours and 5,000 hours after the start of operation. The Mn of the released aromatic polycarbonate was 10,500, 10,550, 10,500, 10,550, 10,500, 10,500, 10,550, 10,500, respectively, and was stable. .
In the aromatic polycarbonate thus produced, the content of alkali metal and / or alkaline earth metal compound is 0.04 to 0.05 ppm in terms of these metal elements, and the content of chlorine is 1 ppb or less. Further, the content of heterogeneous bonds was 0.12 to 0.15 mol%.

(5) Phenol recycling process (V)
A phenol solution containing about 10% diphenyl carbonate and a small amount of bisphenol A recovered as a by-product in step (IV) and continuously supplied to a phenol purification tower (length 1500 cm, inner diameter 270 cm, 9 stages) It was done. Distillation was continuously carried out at a tower bottom temperature of 185 ° C., a tower top pressure of 2000 Pa, and a reflux ratio of 0.9. The phenol recovered from the top of the column was once stored in a tank and then recycled to step (II). The diphenyl carbonate recovered from the side cut portion was supplied to the high boiling point material separation tower in step (III) and recovered as high purity diphenyl carbonate.

[Example 2]
(1) Step of continuously producing dimethyl carbonate and ethylene glycol (I)
Using the same continuous multi-stage distillation column as in Example 1, reactive distillation was performed under the following conditions.
Liquid ethylene carbonate 2.61 ton / hr was continuously introduced into the distillation column from the introduction port (3-a) installed at the 55th stage from the bottom. Gaseous methanol (containing 2.41% by mass of dimethyl carbonate) 4.233 ton / hr and liquid methanol (containing 1.46% by mass of dimethyl carbonate) 4.227 ton / hr are in the 31st stage from the bottom. It was continuously introduced into the distillation column from the installed inlets (3-b and 3-c). The molar ratio of the raw material introduced into the distillation column was methanol / ethylene carbonate = 8.73. The catalyst was continuously fed to the distillation column in the same manner as in Example 1. Reactive distillation was continuously carried out under the conditions that the temperature at the bottom of the column was 93 ° C., the pressure at the top of the column was about 1.046 × 10 ⁵ Pa, and the reflux ratio was 0.48.

  After 24 hours, stable steady operation was achieved. The low boiling point reaction mixture withdrawn in the form of gas from the top 1 of the column was cooled with a heat exchanger to be liquid. The dimethyl carbonate in the liquid low boiling point reaction mixture continuously extracted from the distillation column at 8.17 tons / hr was 2.84 tons / hr and methanol was 5.33 tons / hr. In the liquid continuously extracted at 2.937 ton / hr from the bottom 2 of the column, ethylene glycol is 1.865 ton / hr, methanol is 1.062 ton / hr, and unreacted ethylene carbonate is 0.2 kg. / hr. Excluding dimethyl carbonate contained in the raw material, the actual production amount per hour of dimethyl carbonate was 2.669 tons, and the actual production amount of ethylene glycol per hour excluding ethylene glycol contained in the catalyst solution was 1. It was 839 tons. The reaction rate of ethylene carbonate was 99.99%, the selectivity of dimethyl carbonate was 99.99% or more, and the selectivity of ethylene glycol was 99.99% or more.

  Long-term continuous operation was performed under these conditions. After 1000 hours, 2000 hours, 3000 hours, 5000 hours, the actual production amount per hour is 2.669 tons, 2.669 tons, 2.669 tons, 2.669 tons of dimethyl carbonate, Ethylene glycol is 1.839 tons, 1.839 tons, 1.839 tons, and 1.839 tons, and the reaction rates of ethylene carbonate are 99.99%, 99.99%, 99.99%, 99.99. %, The selectivity for dimethyl carbonate is 99.99% or more, 99.99% or more, 99.99% or more, 99.99% or more, and the selectivity for ethylene glycol is 99.99% or more, 99.99%. As described above, they were 99.99% or more and 99.99% or more.

(2) Step of continuously producing diphenyl carbonate (II)
Using the same apparatus as in Example 1, reactive distillation was performed under the following conditions.
The raw material 1 consisting of phenol / dimethyl carbonate = 1.1 (weight ratio) was continuously introduced in liquid form from the upper inlet 11 of the first continuous multistage distillation column 101 at a flow rate of 40 tons / hr. On the other hand, the raw material 2 consisting of dimethyl carbonate / phenol = 3.9 (weight ratio) was continuously introduced in a gaseous state from the lower inlet 12 of the first continuous multistage distillation column 101 at a flow rate of 43 ton / hr. The molar ratio of the raw material introduced into the first continuous multistage distillation column 101 was dimethyl carbonate / phenol = 1.87. This raw material contained substantially no halogen (1 ppb or less outside the detection limit in ion chromatography). The catalyst was introduced as Pb (OPh) ₂ from the upper inlet 11 of the first continuous multistage distillation column 101 so as to be about 250 ppm in the reaction solution. In the first continuous multi-stage distillation column 101, the reactive distillation was continuously performed under the conditions that the temperature at the bottom of the column was 235 ° C. and the pressure at the top of the column was 9 × 10 ⁵ Pa. The first tower low boiling point reaction mixture containing methyl alcohol, dimethyl carbonate, phenol and the like is continuously withdrawn in the form of a gas from the top 13 of the first tower, passed through the heat exchanger 14 and is 43 tons / hr from the outlet 16. Extracted at flow rate. On the other hand, the first tower high boiling point reaction mixture containing methylphenyl carbonate, dimethyl carbonate, phenol, diphenyl carbonate, catalyst and the like was continuously extracted in liquid form from the first tower bottom 17.

Since a stable steady state was reached after 24 hours, the first tower high-boiling point reaction mixture was passed through the raw material inlet 21 installed between the melapack and the perforated plate tray of the second continuous multistage distillation tower 201 as it was. It was continuously supplied at a flow rate of ton / hr. The liquid supplied to the second continuous multistage distillation column 201 contained 20.7% by mass of methylphenyl carbonate and 1.0% by mass of diphenyl carbonate. In the second continuous multistage distillation column 201, the reactive distillation was continuously performed under the conditions that the temperature at the bottom of the column was 205 ° C., the pressure at the top of the column was 2 × 10 ⁴ Pa, and the reflux ratio was 0.5. After 24 hours, stable steady operation was achieved. The second tower low boiling point reaction mixture is continuously withdrawn from the second tower top 23, and the second tower bottom 27 contains 26.2% by weight methylphenyl carbonate and 60.8% by weight diphenyl carbonate. The column high boiling point reaction mixture was continuously withdrawn. The second column low boiling point reaction mixture was continuously supplied from the inlet 11 to the first continuous multistage distillation column 101. At this time, the amount of dimethyl carbonate and phenol to be newly supplied was adjusted so as to maintain the composition and amount of the raw material 1 and the raw material 2 in consideration of the composition and amount of the second tower low boiling point reaction mixture. . The production amount of diphenyl carbonate was found to be 4.03 tons per hour. The selectivity for diphenyl carbonate was 97% with respect to the reacted phenol.
Long-term continuous operation was performed under these conditions. After 500 hours, 1000 hours, and 2000 hours, the production amount of diphenyl carbonate per hour was 4.03 tons, 4.03 tons, and 4.04 tons, and the selectivity was 97% with respect to the reacted phenol. 97% and 97%, which were very stable. Moreover, the produced aromatic carbonate contained substantially no halogen (1 ppb or less).

(3) Step of obtaining high-purity diphenyl carbonate (III)
The same method as in Example 1 was performed.

(4) Process for producing high-quality aromatic polycarbonate (IV)
In the same polymerization vessel as in Example 1, an aromatic polycarbonate melt prepolymer (number average molecular weight Mn is 3,500) produced from bisphenol A and high-purity diphenyl carbonate (molar ratio of bisphenol A: 1.05), It was continuously supplied from the supply port 1 to the supply zone 3 by the supply pump. An aromatic polycarbonate was produced by polymerization in the same manner as in Example 1 except that the pressure in the polymerization reaction zone was maintained at 100 Pa. 50 hours, 100 hours, 500 hours, 1,000 hours, 2,000 hours, 3,000 hours, 4,000 hours, 5,000 hours and 5,000 hours after the start of operation. The Mn of the aromatic polycarbonate thus obtained was 7,600, 7,600, 7,650 7,600, 7,650, 7,650, 7,600, 7,600, respectively, and was stable.
The aromatic polycarbonate produced in this manner has an alkali metal and / or alkaline earth metal compound content of 0.03 to 0.04 ppm in terms of these metal elements, and a chlorine content of 1 ppb or less. The content of heterogeneous bonds was 0.08 to 0.1 mol%.

(5) Phenol recycling process (V)
The same method as in Example 1 was performed.

[Example 3]
(1) Step of continuously producing dimethyl carbonate and ethylene glycol (I)
As shown in FIG. 1, L ₀ = 3300 cm, D ₀ = 300 cm, L ₀ / D ₀ = 11, n ₀ = 60, D ₀ / d ₀₁ = 7.5, D ₀ / d ₀₂ = 12 A multistage distillation column was used. In this example, a perforated plate tray having a cross-sectional area per hole in the perforated plate portion = about 1.3 cm ² and a number of holes = about 220 to 340 / m ² was used as an internal.
Liquid ethylene carbonate 3.773 tons / hr was continuously introduced into the distillation column from the inlet (3-a) installed at the 55th stage from the bottom. Gaseous methanol (containing 8.97% by mass of dimethyl carbonate) 3.736 tons / hr and liquid methanol (containing 6.65% by mass of dimethyl carbonate) 8.641 tons / hr It was continuously introduced into the distillation column from the installed inlets (3-b and 3-c). The molar ratio of the raw material introduced into the distillation column was methanol / ethylene carbonate = 8.73. The catalyst was continuously fed to the distillation column in the same manner as in Example 1. Reactive distillation was continuously carried out under the conditions that the temperature at the bottom of the column was 98 ° C., the pressure at the top of the column was about 1.118 × 10 ⁵ Pa, and the reflux ratio was 0.42.

  After 24 hours, stable steady operation was achieved. The low boiling point reaction mixture withdrawn in the form of gas from the top of the column was cooled to a liquid by a heat exchanger. The dimethyl carbonate in the liquid low boiling point reaction mixture continuously extracted from the distillation column at 12.32 tons / hr was 4.764 tons / hr and methanol was 7.556 tons / hr. In the liquid continuously extracted at 3.902 tons / hr from the bottom of the column, ethylene glycol was 2.718 tons / hr, methanol was 1.17 tons / hr, and unreacted ethylene carbonate was 4.6 kg / hr. hr. Excluding dimethyl carbonate contained in the raw material, the actual production amount per hour of dimethyl carbonate was 3.854 tons, and the actual production amount of ethylene glycol per hour excluding ethylene glycol contained in the catalyst solution was 2. It was 655 tons. The reaction rate of ethylene carbonate was 99.88%, the selectivity of dimethyl carbonate was 99.99% or more, and the selectivity of ethylene glycol was 99.99% or more.

  Long-term continuous operation was performed under these conditions. The actual production amount per hour after 1000 hours, 2000 hours, 3000 hours, and 5000 hours is 3.854 tons, 3.854 tons, 3.854 tons, 3.854 tons of dimethyl carbonate, Ethylene glycol is 2.655 tons, 2.655 tons, 2.655 tons, 2.655 tons, and the reaction rate of ethylene carbonate is 99.99%, 99.99%, 99.99%, 99.99. %, The selectivity for dimethyl carbonate is 99.99% or more, 99.99% or more, 99.99% or more, 99.99% or more, and the selectivity for ethylene glycol is 99.99% or more, 99.99%. As described above, they were 99.99% or more and 99.99% or more.

(2) Step of continuously producing diphenyl carbonate (II)
Reactive distillation was performed under the following conditions using the same apparatus as in Example 1 except that the cross-sectional area per hole of the perforated plate tray in the second continuous multistage distillation column 201 was about 1.8 cm ² .
The raw material 1 consisting of phenol / dimethyl carbonate = 1.7 (weight ratio) was continuously introduced in liquid form from the upper inlet 11 of the first continuous multistage distillation column 101 at a flow rate of 86 tons / hr. On the other hand, the raw material 2 consisting of dimethyl carbonate / phenol = 3.5 (weight ratio) was continuously introduced in a gaseous state from the lower inlet 12 of the first continuous multistage distillation column 101 at a flow rate of 90 ton / hr. The molar ratio of the raw material introduced into the first continuous multistage distillation column 101 was dimethyl carbonate / phenol = 1.44. This raw material contained substantially no halogen (1 ppb or less outside the detection limit in ion chromatography). The catalyst was introduced as Pb (OPh) ₂ from the upper inlet 11 of the first continuous multistage distillation column 101 so as to be about 150 ppm in the reaction solution. In the first continuous multi-stage distillation column 101, the reactive distillation was continuously performed under the conditions that the temperature at the bottom of the column was 220 ° C. and the pressure at the top of the column was 8 × 10 ⁵ Pa. The first tower low boiling point reaction mixture containing methyl alcohol, dimethyl carbonate, phenol and the like is continuously withdrawn in the form of gas from the top 13 of the first tower, passed through the heat exchanger 14 and is 82 ton / hr from the outlet 16. Extracted at flow rate. On the other hand, the first tower high boiling point reaction mixture containing methylphenyl carbonate, dimethyl carbonate, phenol, diphenyl carbonate, catalyst and the like was continuously extracted in liquid form from the first tower bottom 17.

Since a stable steady state was reached after 24 hours, the first tower high-boiling point reaction mixture was passed through the raw material inlet 21 installed between the melapack and the perforated plate tray of the second continuous multistage distillation tower 201 as it was. It was continuously supplied at a flow rate of ton / hr. The liquid supplied to the second continuous multistage distillation column 201 contained 16.0% by mass of methylphenyl carbonate and 0.5% by mass of diphenyl carbonate. In the second continuous multistage distillation column 201, the reactive distillation was continuously performed under the conditions that the temperature at the bottom of the column was 215 ° C., the pressure at the top of the column was 2.5 × 10 ⁴ Pa, and the reflux ratio was 0.4. After 24 hours, stable steady operation was achieved. The second tower low boiling point reaction mixture is continuously withdrawn from the second tower top 23, and the second tower bottom 27 contains 25.5% by weight of methylphenyl carbonate and 59.5% by weight of diphenyl carbonate. The column high boiling point reaction mixture was continuously withdrawn. The second column low boiling point reaction mixture was continuously supplied from the inlet 11 to the first continuous multistage distillation column 101. At this time, the amount of dimethyl carbonate and phenol to be newly supplied was adjusted so as to maintain the composition and amount of the raw material 1 and the raw material 2 in consideration of the composition and amount of the second tower low boiling point reaction mixture. . The production amount of diphenyl carbonate was found to be 7.28 tons per hour. The selectivity for diphenyl carbonate with respect to the reacted phenol was 98%.
Long-term continuous operation was performed under these conditions. After 500 hours, 1000 hours and 2000 hours, the production amount of diphenyl carbonate per hour is 7.28 tons, 7.29 tons and 7.29 tons, and the selectivity is 98% with respect to the reacted phenol. 98% and 98%, which were very stable. Moreover, the produced aromatic carbonate contained substantially no halogen (1 ppb or less).

(3) Step of obtaining high-purity diphenyl carbonate (III)
The same method as in Example 1 was performed.

(4) Process for producing high-quality aromatic polycarbonate (IV)
An aromatic polycarbonate was produced using a polymerization apparatus in which two guide contact flow type polymerization reactors as shown in FIG. 6 were arranged in series. The material of these polymerization vessels is all stainless steel. The guide contact flow-down type first polymerization vessel has a cylindrical casing and a cone portion, and L = 950 cm, h = 850 cm, D = 400 cm, d = 20 cm, C = 150 degrees, and S = 750 m ² . The second polymerization vessel is the same as that used in Example 1.

  An aromatic polycarbonate melt prepolymer (number average molecular weight Mn is 2,500) produced from bisphenol A and high-purity diphenyl carbonate (molar ratio of bisphenol A to 1.06) is fed to the first polymerizer by a feed pump. It was continuously supplied from the port 1 to the supply zone 3. The molten prepolymer continuously supplied to the polymerization reaction zone through the perforated plate 2 in the first polymerization vessel proceeded with the polymerization reaction while flowing down along the guide 4. The polymerization reaction zone of the first polymerization vessel is maintained at a pressure of 800 Pa through the vacuum vent port 6. An aromatic polycarbonate melted prepolymer (number average molecular weight Mn is 5,500) having an increased degree of polymerization that has entered the bottom 11 of the polymerization vessel from the bottom of the guide 4 so that the amount at the bottom is constant. It was continuously extracted from the discharge port 7 at a constant flow rate by the discharge pump 8. This molten prepolymer was continuously supplied to the supply zone 3 from the supply port 1 of the second polymerization vessel by a supply pump. The molten prepolymer, which was continuously supplied to the polymerization reaction zone through the perforated plate 2 in the second polymerization vessel, proceeded with the polymerization reaction while flowing down along the guide 4. The polymerization reaction zone of the second polymerization vessel is maintained at a pressure of 50 Pa through the vacuum vent port 6. The produced aromatic polycarbonate that has entered the bottom 11 of the second polymerization vessel from the lower part of the guide 4 is continuously fed from the discharge port 7 at a flow rate of 6 tons / hr by the discharge pump 8 so that the amount at the bottom becomes constant. Extracted.

The number average molecular weight Mn of the aromatic polycarbonate extracted from the outlet 12 of the second polymerization vessel 50 hours after the start of operation was 11,500, and the color was good (b ^* value 3.2). It was. The tensile elongation was 99%. 60 hours, 100 hours, 500 hours, 1,000 hours, 2,000 hours, 3,000 hours, 4,000 hours, 5,000 hours and 5,000 hours after the start of operation. The Mn of the released aromatic polycarbonate was 11,500, 11,550, 11,500, 11,550, 11,500, 11,500, 11,550, 11,500, respectively, and was stable. .
In the aromatic polycarbonate thus produced, the content of alkali metal and / or alkaline earth metal compound is 0.03 to 0.05 ppm in terms of these metal elements, and the chlorine content is 1 ppb or less. Further, the content of heterogeneous bonds was 0.11 to 0.16 mol%.

(5) Recycling process of aromatic monohydroxy compounds (V)
The same method as in Example 1 was performed.

  According to the present invention, a high-quality, high-performance aromatic polycarbonate that is excellent in mechanical properties and is not colored from a cyclic carbonate and an aromatic dihydroxy compound has an industrial scale of 1 ton or more per hour at a high polymerization rate. Can be manufactured. Moreover, there is little variation in molecular weight, and a high-quality aromatic polycarbonate can be stably produced over a long period of time, for example, 2000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more. Therefore, the present invention is an extremely effective method as an industrial production method for high-quality aromatic polycarbonate.

FIG. 2 is a schematic view of a continuous reaction distillation column T ₀ preferable for carrying out the present invention. An internal made up of a perforated plate tray is installed inside the body. It is the schematic of the 1st continuous reaction distillation column preferable for implementing this invention. An internal is installed inside the trunk. It is the schematic of the 2nd continuous reaction distillation column preferable for implementing this invention. Inside the barrel part, an internal material is provided which consists of regular packing at the top and a perforated plate tray at the bottom. It is the schematic of the apparatus which connected the 1st continuous reaction distillation column and the 2nd continuous reaction distillation column preferable for implementing this invention. 1 is a schematic view of a preferred guide contact flow polymerization reactor for practicing the present invention. FIG. FIG. 2 is a schematic view of a guide contact flow polymerizer having a cylindrical side casing and a tapered bottom casing preferred for practicing the present invention.

Explanation of symbols

(Figure 1)
1: Gas outlet, 2: Liquid outlet, 3-a to 3-e: Inlet, 4-a to 4-b: Inlet, 5: End plate, 6: Internal, 7: Body part, 10 : Continuous multistage distillation column, L ₀ : barrel length (cm), D ₀ : barrel inner diameter (cm), d ₀₁ : inner diameter (cm) of gas outlet, d ₀₂ : inner diameter (cm) of liquid outlet
(FIGS. 2, 3 and 4)
1: Gas outlet, 2: Liquid outlet, 3: Inlet, 4: Inlet, 5: End plate, L ₁ , L ₂ : Body length (cm), D ₁ , D ₁ : Body inner diameter ( cm), d ₁₁ , d ₂₁ : Gas outlet inner diameter (cm), d ₁₂ , d ₂₂ : Liquid outlet inner diameter (cm), 101: First continuous multistage distillation column, 201: Second continuous multistage distillation column, 11 12, 21: inlet, 13, 23: tower top gas outlet, 14, 24, 18, 28: heat exchanger, 17, 27: tower bottom liquid outlet, 16, 26: tower top component outlet, 31: Second component multistage distillation column bottom component outlet (FIGS. 5 and 6)
1: molten prepolymer receiving port, 2: perforated plate, 3: molten prepolymer supply zone, 4: guide, 5: polymerization reaction zone, 6: vacuum vent port, 7: aromatic polycarbonate discharge port, 8: aromatic polycarbonate Discharge pump, 9: inert gas supply port used as required, 10: side casing of polymerization reaction zone, 11: tapered bottom casing of polymerization reaction zone, 12: extraction port for aromatic polycarbonate

Claims (30)

An industrial production method for continuously producing a high-quality aromatic polycarbonate from a cyclic carbonate and an aromatic dihydroxy compound,
(I) Continuous multi-stage distillation column T in which a catalyst is present between cyclic carbonate and aliphatic monohydric alcohol
_The low boiling point reaction mixture containing dialkyl carbonate is continuously extracted in the form of a gas from the top of the tower, and is continuously fed into the column. Step (I) of continuously producing a dialkyl carbonate and a diol by a reactive distillation system in which liquid is continuously extracted from the lower part of the column,
(II) The dialkyl carbonate and the aromatic monohydroxy compound are used as raw materials, and the raw materials are continuously supplied into a first continuous multi-stage distillation column in which a catalyst is present, and the reaction and distillation are simultaneously performed in the first column. The first column low-boiling point reaction mixture containing the generated alcohols is continuously withdrawn from the upper portion of the first column in a gaseous state, and the first column high-boiling point reaction mixture containing the generated alkylaryl carbonates is removed from the lower portion of the first column. It is continuously extracted in a liquid state, and the first column high boiling point reaction mixture is continuously fed into the second continuous multistage distillation column in which the catalyst is present, and the reaction and distillation are simultaneously performed in the second column to produce. The second tower low boiling point reaction mixture containing dialkyl carbonates is continuously withdrawn from the upper part of the second column in the form of gas, and the second tower high boiling point reaction mixture containing the diaryl carbonates to be produced is liquid from the lower part of the second tower. Continuously withdrawn while by continuously feeding the second column low boiling point reaction mixture containing a dialkyl carbonate into the first continuous multi-stage distillation column, and step (II) of continuously producing a diaryl carbonate,
(III) purification step (III) for purifying the diaryl carbonate to obtain high-purity diaryl carbonate;
(IV) The aromatic dihydroxy compound is reacted with the high-purity diaryl carbonate to produce a molten prepolymer of an aromatic polycarbonate, and the molten prepolymer is allowed to flow along the surface of the guide, and the molten prepolymer is melted during the flow. A step (IV) of producing an aromatic polycarbonate using a guide contact flow type polymerizer for polymerizing a prepolymer;
(V) an aromatic monohydroxy compound recycling step (V) in which the aromatic monohydroxy compound by-produced in step (IV) is circulated to the diaryl carbonate production step (II);
Including
(A) The continuous multi-stage distillation column T ₀ has a cylindrical body having a length L ₀ (cm) and an inner diameter D ₀ (cm), and has an internal structure having an internal number n _0. A gas outlet with an inner diameter d ₀₁ (cm) at the top of the tower or near the top of the tower, a liquid outlet with an inner diameter d ₀₂ (cm) at the bottom of the tower or near the tower, and below the gas outlet. One or more first inlets in the upper part and / or middle part of the tower, and one or more second inlets above the liquid outlet and in the middle part and / or lower part of the tower L ₀ , D ₀ , L ₀ / D
₀ , n ₀ , D ₀ / d ₀₁ , D ₀ / d ₀₂ satisfy the formulas (1) to (6),
2100 ≦ L ₀ ≦ 8000 Formula (1)
180 ≦ D ₀ ≦ 2000 Formula (2)
4 ≦ L ₀ / D ₀ ≦ 40 Formula (3)
10 ≦ n ₀ ≦ 120 Formula (4)
3 ≦ D ₀ / d ₀₁ ≦ 20 Formula (5)
5 ≦ D ₀ / d ₀₂ ≦ 30 Formula (6)
(B) The first continuous multi-stage distillation column has a cylindrical body having a length L ₁ (cm) and an inner diameter D ₁ (cm), and has an internal structure having an internal number n _1. A gas outlet with an inner diameter d ₁₁ (cm) at the top of the tower or near the top of the tower, a liquid outlet with an inner diameter d ₁₂ (cm) at the bottom of the tower or near the tower, and below the gas outlet. At the top of the tower and / or
Or one or more third inlet at an intermediate portion include those having one or more fourth inlet A above the liquid withdrawal to the middle and / or bottom of the tower, L ₁ , D ₁ , L ₁ / D
₁ , n ₁ , D ₁ / d ₁₁ , D ₁ / d ₁₂ satisfy formulas (7) to (12),
1500 ≦ L ₁ ≦ 8000 Formula (7)
100 ≦ D ₁ ≦ 2000 Formula (8)
2 ≦ L ₁ / D ₁ ≦ 40 Formula (9)
20 ≦ n ₁ ≦ 120 Formula (10)
5 ≦ D ₁ / d ₁₁ ≦ 30 Formula (11)
3 ≦ D ₁ / d ₁₂ ≦ 20 Formula (12)
(C) The second continuous multi-stage distillation column has a cylindrical body having a length L ₂ (cm) and an inner diameter D ₂ (cm), and has an internal structure having an internal number n _2. A gas outlet with an inner diameter of d ₂₁ (cm) at the top of the tower or near the top of the tower, a liquid outlet with an inner diameter of d ₂₂ (cm) at the bottom of the tower or near the tower, and below the gas outlet. At the top of the tower and / or
Or one or more fifth inlet at an intermediate portion include those having one or more inlets of the 6 A above the liquid withdrawal to the middle and / or bottom of the tower, L ₂ , D ₂ , L ₂ / D
₂ , n ₂ , D ₂ / d ₂₁ , D ₂ / d ₂₂ satisfy formulas (13) to (18),
1500 ≦ L ₂ ≦ 8000 Formula (13)
100 ≦ D ₂ ≦ 2000 (14)
2 ≦ L ₂ / D ₂ ≦ 40 Formula (15)
10 ≦ n ₂ ≦ 80 Formula (16)
2 ≦ D ₂ / d ₂₁ ≦ 15 Formula (17)
5 ≦ D ₂ / d ₂₂ ≦ 30 Formula (18)
(D) the guide contact flow type polymerizer,
(1) A molten prepolymer receiving port, a perforated plate, a molten prepolymer supply zone for supplying the molten prepolymer to the guide of the polymerization reaction zone through the perforated plate, the perforated plate, a side casing, and a tapered bottom casing A polymerization reaction zone in which a plurality of guides extending downward from the perforated plate are provided in a space surrounded by the vacuum plate, a vacuum vent port provided in the polymerization reaction zone,
An aromatic polycarbonate discharge port provided at the bottom of the tapered bottom casing, and an aromatic polycarbonate discharge pump connected to the discharge port,
(2) The internal cross-sectional area A (m ² ) in the horizontal plane of the side casing of the polymerization reaction zone is
Which satisfies equation (19),
0.7 ≦ A ≦ 300 Formula (19)
(3) A (m ² ) and internal cross-sectional area B in the horizontal plane of the aromatic polycarbonate outlet
The ratio to (m ² ) satisfies equation (20),
20 ≦ A / B ≦ 1000 Formula (20)
(4) A tapered bottom casing constituting the bottom of the polymerization reaction zone is connected to the upper side casing at an angle C degree inside, and the angle C degree is expressed by the equation (2).
Satisfying 1),
120 ≦ C ≦ 165 Formula (21)
(5) The length h (cm) of the guide satisfies the formula (22),
150 ≦ h ≦ 5000 Formula (22)
(6) The external total surface area S (m ² ) of the entire guide satisfies the formula (23).
2 ≦ S ≦ 50000 Formula (23)
An industrial process for producing high-quality aromatic polycarbonate, characterized in that The process according to claim 1, wherein the aromatic polycarbonate produced is 1 ton or more per hour. The method according to claim 1 or 2, wherein the d ₀₁ and the d _{02 of the} continuous multistage distillation column T ₀ used in the step (I) satisfy the formula (24).
1 ≦ d ₀₁ / d ₀₂ ≦ 5 Formula (24) L ₀ , D ₀ , L ₀ / D ₀ , n ₀ , D ₀ / d ₀₁ , D ₀ / d _{02 of the} continuous multistage distillation column T ₀
2300 ≦ L ₀ ≦ 6000, 200 ≦ D ₀ ≦ 1000, 5 ≦ L ₀ /
D ₀ ≦ 30, 30 ≦ n ₀ ≦ 100, 4 ≦ D ₀ / d ₀₁ ≦ 15, 7 ≦ D ₀ / d ₀₂ ≦
25. The method according to any one of claims 1 to 3, wherein the method is 25. L ₀ , D ₀ , L ₀ / D ₀ , n ₀ , D ₀ / d ₀₁ , D ₀ / d _{02 of the} continuous multistage distillation column T ₀
Are 2500 ≦ L ₀ ≦ 5000, 210 ≦ D ₀ ≦ 800, 7 ≦ L ₀ / D, respectively.
₀ ≦ 20, 40 ≦ n ₀ ≦ 90, 5 ≦ D ₀ / d ₀₁ ≦ 13, 9 ≦ D ₀ / d ₀₂ ≦ 20
The method according to any one of claims 1 to 4, characterized in that Said continuous multi-stage distillation column T ₀ A method according to any one of claims 1 to 5, characterized in that a distillation column having trays and / or packings as the internal. The method according to claim 6, wherein the continuous multi-stage distillation column T ₀ is a tray-type distillation column having a tray as the internal. Claim 6 or 7 method wherein a said tray in said continuous multi-stage distillation column T ₀ is a sieve tray having a sieve portion and a downcomer portion. The perforated plate tray of the continuous multistage distillation column T ₀ is 100 to ¹⁰ per 1 m ^{2 of the} perforated plate portion area.
9. A method according to claim 8, characterized in that it has 00 holes. The method according to claim 8 or 9, wherein a cross-sectional area per hole of the perforated plate tray of the continuous multistage distillation column T ₀ is 0.5 to ⁵ cm ² . The aperture ratio of the perforated plate tray of the continuous multistage distillation column T ₀ (the ratio of the total hole cross-sectional area to the area of the perforated plate portion) is 1.5 to 15%. The method according to any one of the above. The first continuous multistage distillation column used in step (II), the first continuous multistage distillation column, d ₁₁ and d ₁₂ satisfy the formula (25), and d ₂₁ and d ₂₂ are the formula (26 The method according to any one of claims 1 to 11, wherein:
1 ≦ d ₁₂ / d ₁₁ ≦ 5 Formula (25)
1 ≦ d ₂₁ / d ₂₂ ≦ 6 Formula (26) L ₁ , D ₁ , L ₁ / D ₁ , n ₁ , D of the first continuous multistage distillation column used in step (II)
₁ / d ₁₁ and D ₁ / d ₁₂ are 2000 ≦ L ₁ ≦ 6000 and 150 ≦ D ₁ ≦, respectively.
1000, 3 ≦ L ₁ / D ₁ ≦ 30, 30 ≦ n ₁ ≦ 100, 8 ≦ D ₁ / d ₁₁ ≦ 25
5 ≦ D ₁ / d ₁₂ ≦ 18, and L ₂ , D ₂ , L ₂ / D ₂ , n ₂ , D ₂ / d ₂₁ , D ₂ / d _{22 of the} second continuous multi-stage distillation column.
Are 2000 ≦ L ₂ ≦ 6000, 150 ≦ D ₂ ≦ 1000, 3 ≦ L ₂ / D, respectively.
₂ ≦ 30, 15 ≦ n ₂ ≦ 60, 2.5 ≦ D ₂ / d ₂₁ ≦ 12, 7 ≦ D ₂ / d ₂₂ ≦
The method according to claim 1, wherein the method is 25. L ₁ , D ₁ , L ₁ / D ₁ , n ₁ , D ₁ / d ₁₁ , D ₁ / d _{12 of the} first continuous multistage distillation column.
Are 2500 ≦ L ₁ ≦ 5000, 200 ≦ D ₁ ≦ 800, and 5 ≦ L ₁ / D _{1, respectively.}
≦ 15, 40 ≦ n ₁ ≦ 90, 10 ≦ D ₁ / d ₁₁ ≦ 25, 7 ≦ D ₁ / d ₁₂ ≦ 15
And
L ₂ , D ₂ , L ₂ / D ₂ , n ₂ , D ₂ / d ₂₁ , D ₂ / d _{22 of the} second continuous multistage distillation column.
Are 2500 ≦ L ₂ ≦ 5000, 200 ≦ D ₂ ≦ 800, 5 ≦ L ₂ / D _{2, respectively.
≦ 15, 20 ≦ n 2 ≦} 50, 3 ≦ D 2 / d 21 ≦ 10, according to any one of 9 ≦ D ₂ / d _22, characterized in that ≦ 20 claims 1 to 13 Method. 15. The first continuous multistage distillation column and the second continuous multistage distillation column are distillation columns each having a tray and / or a packing as the internal, respectively. The method described in 1. The first continuous multi-stage distillation column is a tray-type distillation column having a tray as the internal;
16. The process of claim 15, wherein the second continuous multistage distillation column is a distillation column having both packing and trays as the internal. The method according to claim 15 or 16, wherein each of the trays of the first continuous multistage distillation column and the second continuous multistage distillation column is a perforated plate tray having a perforated plate portion and a downcomer portion. 18. The perforated plate trays of the first continuous multi-stage distillation column and the second continuous multi-stage distillation column have 100 to 1000 holes per 1 m ² area of the perforated plate portion.
The method described. The method according to claim 17 or 18, wherein the first continuous multi-stage distillation column and the second continuous multi-stage distillation column have a cross-sectional area of 0.5 to ⁵ cm ² per hole in the perforated plate tray. . The method according to claim 15 or 16, wherein the second continuous multistage distillation column is a distillation column having a packing as an upper part and a tray as a lower part as the internal. 21. The method according to any one of claims 15 to 20, wherein the packing of the internal of the second continuous multistage distillation column is one or more regular packings. The regular packing of the second continuous multistage distillation column is a mela pack, a gem pack, a techno pack,
The method according to claim 21, wherein the method is at least one selected from a flexi pack, a sulzer packing, a good roll packing, and a glitch grid. The diaryl carbonate purification step (III) is distillation.
The method according to any one of 22. In the guided contact flow type polymerization reactor used in the step (IV), the side casing of the polymerization reaction zone has a cylindrical shape with an inner diameter D (cm) and a length L (cm), and the bottom casing connected to the lower part thereof The casing is tapered, the lowermost discharge port of the tapered bottom casing is cylindrical with an inner diameter d (cm), and D, L, d are equations (27), (28), (29) And (30) is satisfied,
100 ≦ D ≦ 1800 Formula (27)
5 ≦ D / d ≦ 50 Formula (28)
0.5 ≦ L / D ≦ 30 Formula (29)
h-20 <= L <= h + 300 Formula (30)
24. A method according to any one of claims 1 to 23. The h of the guide satisfies the formula (31).
400 <h ≦ 2500 Formula (31)
25. A method according to any one of claims 1 to 24. One of the guides is a cylindrical shape having an outer diameter r (cm) or a pipe shape in which molten prepolymer is prevented from entering inside, and r 1 satisfies the formula (32).
0.1 ≦ r ≦ 1 Formula (32)
26. A method according to any one of claims 1-25. 27. The method according to any one of claims 1 to 26, wherein in step (IV), polymerization is carried out by connecting two or more guide contact flow type polymerization reactors. 28. The two or more guide contact flow type polymerization reactors according to claim 27 are two polymerization vessels of a guide contact flow type first polymerization device and a guide contact flow type second polymerization device, and the degree of polymerization is increased in this order. In this method, the external total surface area S1 (m ² ) of the entire guide of the first polymerization vessel and the external total surface area S2 (m ² ) of the entire guide of the second polymerization vessel satisfy the formula (33).
1 ≦ S1 / S2 ≦ 20 Formula (33)
28. The method of claim 27. High-quality aromatic polycarbonate in which the content of alkali metal and / or alkaline earth metal compound is 0.1 to 0.01 ppm in terms of these metal elements, and the halogen content is 1 ppb or less The method according to claim 1, wherein the method is manufactured. An aromatic polycarbonate partially branched to the main chain via a hetero bond such as an ester bond or an ether bond, and the content of the hetero bond is relative to the carbonate bond,
30. A process according to any one of the preceding claims, characterized in that it produces a high quality aromatic polycarbonate that is 0.05 to 0.5 mol%.