JP2005097568A - Method for producing aromatic polycarbonate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain the production efficiency of a PC as a whole by limiting the water content of byproduct PL produced in the PC production process as a method for dealing with byproduct phenol to maintain the production efficiency of a BPA production process and DPC production process where the byproduct PL is returned. <P>SOLUTION: This method for producing an aromatic polycarbonate comprising a diphenyl carbonate production process, a bisphenol A production process and an aromatic polycarbonate production process is provided by limiting the water content contained in the byproduct phenol recovered in the aromatic polycarbonate production process by ≤0.2 wt.%, and using it as a raw material for the diphenyl carbonate production process and/or bisphenol A production process. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a method for producing an aromatic polycarbonate.

  Aromatic carbonate (abbreviated as “PC” in the claims and specification) is generally diphenyl carbonate (abbreviated as “DPC” in the claims and specification). And bisphenol A (abbreviated as “BPA” in the claims and the specification).

[Treatment of by-product phenol]
In the polymerization reaction, phenol (abbreviated as “PL” in the claims and specification) is by-produced. The by-product PL includes, as impurities, oligomers in which DPC, BPA, DPC, and BPA are reacted by one to several molecules. A method is known in which the byproduct PL is returned to the BPA manufacturing process or the DPC manufacturing process.

  That is, Patent Document 1 describes a method of returning the byproduct PL as it is or purifying it to a low purity and returning it to the BPA production process. The reason why the degree of purification of the by-product PL obtained can be lowered is that there is no problem even if DPC or the above oligomer is hydrolyzed to become PL or BPA and mixed into the BPA production process.

  Furthermore, Patent Document 2, Patent Document 3 and the like describe a method for purifying the by-product PL to a high purity and returning it to the DPC manufacturing process. The reason why it is necessary to increase the degree of purification of the obtained byproduct PL is to prevent BPA and the like from being mixed into the DPC manufacturing process and clogging.

[Cooperation between manufacturing processes]
In addition, normally, BPA is used in a state of being cooled and solidified after being purified, but the BPA manufacturing facility is provided close to the PC manufacturing facility. In this case, if the polymerization is carried out in the molten state or in a mixed solution of a constant composition of BPA and PL for use in the PC production facility, there is no need to reheat or purify the heat efficiency. improves.

[Drainage treatment]
Furthermore, in the manufacturing process of the DPC and BPA and the manufacturing process of the PC, drainage containing a large amount of organic matter is generated.

  That is, first, in the PC manufacturing process, the DPC and BPA are used as raw materials, and in the main process of manufacturing PC through the polymerization process, the evaporation component in the polymerization process is liquefied and subjected to the distillation process. The distillation residue after recovering the water becomes drainage. This distillation residue contains PL, DPC, BPA, oligomers in which several molecules of DPC and BPA are bonded, and the recovery of these greatly affects the yield of PC.

  On the other hand, methods for returning the distillation residue to the polymerization step are disclosed in Patent Document 3 and Patent Document 4, and the distillation residue is distilled again to recover the components, and the recovered distillation residue is used as a fuel. A method to be used is disclosed in Patent Document 1.

  Further, in the DPC production process, the distillation residue generated in the distillation process becomes a drained liquid in the main process of producing DPC using PL and carbonyl compounds as raw materials through the reaction process and the distillation process. This distillation residue contains DPC, and this recovery greatly affects the yield of DPC.

  On the other hand, Patent Document 5 discloses a method in which the distillation residue is distilled again, DPC is recovered, and this is returned to the reaction solution after completion of the reaction step.

  Furthermore, as described in Patent Document 6, in the BPA production process, PL and acetone are used as raw materials, and the main process for producing BPA through a synthesis reaction process, a crystallization process, and a solid-liquid separation process. The mother liquor separated from the solid-liquid separation step contains by-products such as 2,4-isomers, trisphenols, chroman compounds in addition to a large amount of PL and BPA, and a small amount of colored impurities and coloring. Contains sexual impurities. And since this mother liquor contains PL and BPA which are reaction raw materials of BPA, it is circulated and reused in all processes. However, if the whole amount is circulated without treatment, the by-products, coloring impurities and Since accumulation of colored impurities occurs, it is necessary to remove these by-products and impurities.

[Vacuum equipment]
In the step of producing DPC, DPC is purified by distillation while refluxing, and in the step of producing PC, PL is removed while being separated from DPC by distillation. These distillation operations are performed under reduced pressure by providing a vacuum facility in order to lower the distillation temperature (see Patent Document 7).

JP 2000-53759 A Japanese Patent Laid-Open No. 10-60106 Japanese Patent Laid-Open No. 9-255772 JP-A-9-165443 JP 2002-322130 A JP-A-5-331088 JP 9-38402 A

[Treatment of by-product phenol, problems when integrating three manufacturing processes]
However, in any of the above cases, although attention is paid to the content of impurities other than water, such as BPA and DPC, the content of water has not been studied. When a polymerization raw material DPC or BPC, particularly once solidified and retained, moisture contained in the raw material and further water supplied together with the polymerization catalyst are accompanied by by-product phenol. The presence of water causes a decrease in the activity of the catalyst in the BPA production process, thereby reducing the reaction conversion rate. Further, in the DPC production process, the activity of the catalyst is reduced and the produced DPC is hydrolyzed.

  Furthermore, the above-mentioned impurities are contained in the byproduct phenol generated in the PC polymerization step. These by-products include no problem even if they are sent to the DPC manufacturing process, but include impurities that are problematic when sent to the BPA manufacturing process, and impurities in the opposite case.

  Furthermore, as described above, a step for removing water is required from the distillate component mainly composed of phenol distilled in the PC polymerization step. However, when the DPC manufacturing process, the BPA manufacturing process, and the PC manufacturing process are combined in one place, the BPA manufacturing process also has a process for removing water, and therefore the same process is duplicated. .

[Cooperation between manufacturing processes]
Also, in the process of crystallizing the obtained BPA in the BPA production process, solids are likely to adhere to the wetted part of the crystallizer used, and this process is stopped once every several months. Need to be cleaned. For this reason, the process from the synthesis reaction process to the crystallization process in the manufacturing process of BPA is an intermittent operation.

  On the other hand, in the DPC manufacturing process, there is no problem as described above, and DPC can be manufactured continuously. For this reason, PC can be continuously polymerized by storing a necessary amount of BPA in a molten state.

  However, if the BPA is kept in a molten state, it tends to cause yellowing, decomposition, etc., and affects the quality of the PC obtained.

[Drainage treatment]
Furthermore, since the distillation residue in the PC production process contains PL, if all of it is returned to the polymerization process, PL will be present from the beginning of the polymerization, which affects the initial polymerization rate. Furthermore, the distillation residue in the manufacturing process of PC is generally colored, and if it is recycled as it is, the PC of the product will be colored. Even if the distillation residue is distilled again, some of the above components are also contained in the recovered distillation residue, so that the disposal as it is affects the production efficiency and causes a problem of environmental burden.

  Moreover, the distillation residue in the manufacturing process of the DPC is directly discarded. This distillation residue still contains DPC, and discarding it as it is affects the production efficiency and may cause environmental load problems.

[Vacuum equipment]
Furthermore, when distilled under reduced pressure, distillate components such as PL and DPC are pulled by the vacuum equipment, resulting in a liquid pool in the pipe connected to the vacuum equipment, or the accumulated distillate components solidified. In some cases, the vacuum state cannot be maintained. In addition, when distilled components such as PL and DPC are refluxed by a pump, the distillate components may be clogged due to solidification in the reflux pipe.

  Therefore, the present invention maintains the production efficiency in the BPA production process and the DPC production process to be sent by limiting the water content of the by-product PL generated in the PC production process to a predetermined range as a countermeasure for the byproduct phenol. As a whole, the object is to maintain the manufacturing efficiency of the PC.

  Another object of the present invention is to save labor in the purification process of the byproduct phenol by sending it to the diphenyl carbonate production process or the bisphenol A production process in accordance with impurities contained in the byproduct phenol produced in the aromatic polycarbonate polymerization process.

  Furthermore, in the problem at the time of integration of the three production processes, by using the process used to produce the existing diphenyl carbonate and bisphenol A, distillate mainly composed of phenol generated in the aromatic polycarbonate polymerization process. Another object is to save labor in the purification of the components.

  Moreover, it aims at providing the cooperation method between manufacturing processes which can provide the manufacturing method of PC which has sufficient quality about the cooperation between manufacturing processes.

  Furthermore, as a drainage treatment method, the distillation residue in the DPC manufacturing process and the distillation residue in the PC manufacturing process are returned to a specific position in each process of manufacturing the PC, thereby improving the overall efficiency and reducing the environmental burden. The purpose is to reduce.

  Furthermore, the purpose of the distillation process is to make it difficult for liquid accumulation or solidification to occur in the piping in an apparatus in which PL or DPC is distilled.

  In the present invention, as a by-product phenol countermeasure, diphenyl carbonate (DPC) production process for producing diphenyl carbonate (DPC) using phenol (PL) and carbonyl compound as raw materials, and / or phenol (PL) and acetone are used. A bisphenol A (BPA) production process for producing bisphenol A (BPA) as a raw material, and an aromatic polycarbonate (PC) through a PC polymerization process using the above-mentioned diphenyl carbonate (DPC) and bisphenol A (BPA) as a raw material In addition, in the aromatic polycarbonate (PC) manufacturing method including an aromatic polycarbonate (PC) manufacturing process for recovering by-product phenol, it is included in the by-product phenol recovered in the aromatic polycarbonate (PC) manufacturing process. Water content is 0 As 2 wt% or less, it is characterized by using as part of the raw materials of the diphenyl carbonate (DPC) production step, and / or bisphenol A (BPA) production step.

  Moreover, as a phenol used as a raw material in the said diphenyl carbonate (DPC) manufacturing process, the phenol (PL) containing 20-1000 weight ppm of cresol and / or xylenol is used, and it is used as a raw material in the said bisphenol A (BPA) manufacturing process. As at least part of the phenol used, phenol (PL) generated in the polymerization step of the aromatic polycarbonate (PC) production step can be used.

  Furthermore, 50-95 wt% is used as at least a part of the phenol used in the diphenyl carbonate manufacturing step among phenols by-produced in the aromatic polycarbonate manufacturing step, and 50-5 wt% is bisphenol A. It is characterized by being used as at least a part of the raw material of the manufacturing process.

  Moreover, about the cooperation of each process, before and / or after the said PL distillation process, the liquefied product of the PC evaporation component before applying to the said PL distillation process, and / or the byproduct phenol collect | recovered by the said PL distillation process are used. Providing a PC storage step for storage, providing a DPC storage step for storing the diphenyl carbonate obtained in the DPC distillation step after the DPC distillation step, and / or the BPA crystallization and separation step, and the PC A BPA storage step for storing a mixture of bisphenol A and phenol is provided between the polymerization steps, and the capacity of the storage tank used in each storage step is defined as follows as necessary. It is characterized by that.

・ 10 ≦ (Vc / Fc) ≦ 100 (1)
(In the formula (1), Vc indicates the capacity (m ³ ) of the PC storage tank, and Fc indicates the supply rate (m ³ / hr) of the PC evaporation component liquefaction product or by-product phenol.)
・ 10 ≦ (Vd / Fd) ≦ 100 (2)
(In the formula (2), Vd represents the capacity (m ³ ) of the DPC storage tank, and Fd represents the feed rate (m ³ / hr) of diphenyl carbonate.)
・ 10 ≦ (Vb / Fb) ≦ 1000 (3)
(In Formula (3), Vb indicates the capacity (m ³ ) of the BPA storage tank, and Fb indicates the supply amount (m ³ / hr) of bisphenol A used in the PC polymerization step.)

  Furthermore, as a drainage treatment method, the PL distillation residue is sent to the DPC distillation step and / or the DPC recovery distillation step, or the PL distillation residue and / or the DPC distillation residue and / or the DPC recovery distillation residue is sent to the BPA mother liquor treatment step. Or the PL distillation residue is sent to the DPC distillation step and / or the DPC recovery distillation step, and then the DPC distillation residue and / or the DPC recovery distillation residue is sent to the BPA mother liquor treatment step.

  Furthermore, for the distillation step, a distillation column for the DPC distillation step or the PL distillation step is provided with a condenser for condensing the substance to be distilled, a vacuum facility for reducing the pressure in the system, and the condenser and the vacuum facility. A connecting vacuum pipe is provided, and the vacuum pipe has a downward slope from the condenser side to the vacuum equipment side and rises upward from the condenser side to the vacuum equipment side The total height is 1 m or less.

  According to the present invention, the water content of the byproduct phenol is limited to a predetermined range, so even if this byproduct phenol is used as part of the raw material for the diphenyl carbonate production process or the bisphenol A production process, the production efficiency is not reduced. Less, almost retained.

Furthermore, since the impurities contained in the by-product phenol recovered at the initial stage of polymerization in the aromatic polycarbonate production process are raw materials and products in the diphenyl carbonate production process, the by-product phenol containing these impurities is not purified. It can be used as at least part of the phenol used in the diphenyl carbonate production process.
On the other hand, impurities contained in the by-product phenol recovered in the late polymerization stage of the aromatic polycarbonate production process are hydrolyzed in the bisphenol A production process to become raw materials and products in this production process, and in the bisphenol A production process. Alcohols and the like that cause a decrease in the catalytic activity of the product are hardly contained, and by-product phenol containing these impurities can be used as at least part of the phenol used in the bisphenol A production process without purification. it can.

  Furthermore, by integrating the diphenyl carbonate production process, the bisphenol A production process, and the aromatic polycarbonate production process, commercially available phenol is used as the production raw material for diphenyl carbonate, and the aromatic polycarbonate production process is used as the production raw material for bisphenol A. It is possible to use a distillate component generated in the polymerization step.

  Further, before and / or after the PL distillation step, a PC storage step is provided for storing a liquefied product of PC evaporation components before being subjected to the PL distillation step and / or by-product phenol recovered in the PL distillation step. In the case where a DPC storage step for storing the diphenyl carbonate obtained in the DPC distillation step is provided after the DPC distillation step, and / or between the BPA crystallization / separation step and the PC polymerization step, When a BPA storage process for storing a mixture of bisphenol A and phenol is provided, the quality of the compound obtained in each process can be maintained within a certain range, and the subsequent process is continued regardless of the convenience of the previous process. Can be done automatically.

  Furthermore, when sending PL distillation residue, DPC distillation residue, and / or DPC recovery distillation residue to a predetermined place, the active ingredients contained in these can be fully utilized, so that the overall efficiency can be improved, In addition, the environmental load can be reduced.

  Furthermore, if the total height of the part of the vacuum pipe that leads from the condenser to the vacuum facility rises upside down is 1 m or less, the liquid and solids accumulated in the part that rises are minimized. It is possible to prevent the pipe from being completely blocked or the pressure loss from becoming too large.

Hereinafter, embodiments of the present invention will be described in detail.
The method for producing an aromatic polycarbonate (PC) according to the present invention is a method for polymerizing diphenyl carbonate (DPC) and bisphenol A (BPA).

[DPC manufacturing process]
DPC is produced using PL and carbonyl compounds as raw materials. This carbonyl compound is used without limitation as long as it can form a carbonyl group of DPC. Examples of such carbonyl compounds include phosgene (hereinafter abbreviated as “CDC”), carbon monoxide, dialkyl carbonate, and the like. In the following, a process for producing DPC using CDC as a carbonyl compound and passing through a DPC washing process and a DPC distillation process after the reaction will be described.

  The DPC manufacturing process includes the process shown in FIG. That is, a DPC reaction step is performed in which PL and CDC are used as raw materials, and an alkaline catalyst (C1) such as pyridine is introduced into the DPC reactor 1. The reaction conditions at this time are not particularly limited, but 50 to 180 ° C. and normal pressure at which PL is in a molten state are preferable. Further, the mixing ratio (molar ratio) of PL and CDC is preferably 0.40 to 0.49 mol with respect to 1 mol of PL from the viewpoint of complete consumption of CDC.

  The DPC-containing reaction liquid a produced in the DPC reaction step is sent to the dehydrochlorination tower 2, and the dehydrochlorination step is performed. The hydrochloric acid gas (D1) generated in the DPC reactor 1 and the dehydrochlorination tower 2 is recovered and sent to a hydrochloric acid treatment step (not shown).

  Next, the obtained dehydrochlorination treatment liquid b is subjected to a DPC cleaning step. This DPC cleaning process includes the following neutralization process and water washing process. That is, the dehydrochlorination treatment liquid b is sent to the mixing tank 3 and then sent to the alkali neutralization tank 4 to neutralize the hydrochloric acid that could not be removed by the dehydrochlorination tower with the alkaline aqueous solution (E1). A summing process is performed. The neutralized waste water (D2) discharged here is sent to a waste water treatment step (not shown), and after collecting effective organic components contained therein, it is subjected to activated sludge treatment.

  And the obtained neutralization process liquid e is sent to the water-washing tank 5, and the DPC water washing process wash | cleaned with water (W) is performed. The waste water (D3) discharged in this DPC water washing step can be reused as an alkaline diluent when adjusting the alkaline aqueous solution (E1) in the neutralization step.

  The washing treatment liquid f obtained in the DPC washing step is sent to the distillation tower, and the DPC distillation step is performed. In FIG. 1, three distillation columns are used, but the present invention is not limited to this. When using three distillation columns, the first DPC distillation column 6 collects the mixed gas (F) containing water, PL, and an alkaline catalyst. The mixed gas (F) can be reused in the reaction system by separating the components.

  And the 1st distillation residue g of the said 1st DPC distillation column 6 is redistilled in the 2nd DPC distillation column 7, The refine | purified DPC which is a product is collect | recovered as a distillate.

  The distillation conditions in the first DPC distillation column 6 are not particularly limited as long as water, an alkaline catalyst, and PL are distilled and DPC remains, and 1.3 to 13 kPa is preferable. The temperature becomes the boiling point under that pressure. The distillation conditions in the second DPC distillation column 7 are not particularly limited as long as DPC is distilled and impurities having a higher boiling point than DPC remain, and 1.3 to 6.5 kPa, 150-220 degreeC is preferable.

  By the way, the DPC distillation residue X1 in the second DPC distillation column 7 includes impurities mainly composed of a methyl substitution product of DPC reacted with methylphenol, which is a phenol-containing impurity, and a bromine substitution product of DPC reacted with residual bromine in CDC. But also contains DPC itself. For this reason, this DPC distillation residue X1 may be distilled again to recover diphenyl carbonate (DPC). In this case, as shown in FIG. 1, the DPC distillation residue X1 is subjected to a recovery distillation process using a DPC recovery distillation column 8. Thereby, the DPC-containing recovery liquid d can be recovered by distillation. Then, the DPC recovery distillation residue (X1 ') in which the methyl substitution product or bromine substitution product of DPC is concentrated is collected from the remaining side of the distillation still.

  The distillation conditions in the DPC recovery distillation column 8 are not particularly limited as long as DPC is distilled and impurities having a higher boiling point than DPC remain, and are 1.3 to 6.5 kPa, 150 to 220. ° C is preferred.

  And, since the DPC-containing recovered liquid d, which is a distillate from the DPC recovery distillation tower, is a component containing a large amount of DPC, it is reintroduced into the washing / distillation process by sending it to the mixing tank 3. And the recovery efficiency of diphenyl carbonate (DPC) can be further improved.

[BPA manufacturing process]
The manufacturing process of BPA includes the process shown in FIG. That is, using PL and acetone (A) as raw materials, BPA reaction step (step (a)), BPA low boiling removal step (step (b)), BPA crystallization / separation step (step (c)), heat melting BPA is manufactured through a process (process (d)), a PL removal process (process (e)), and a granulation process (process (f)).

Next, each step will be described.
The step (a) is a step of producing BPA by subjecting PL and acetone (A) to a condensation reaction in the presence of an acidic catalyst. The raw material PL and acetone (A) used here are reacted under a condition in which PL is in excess of the stoichiometric amount. The molar ratio of PL to acetone (A) is in the range of 3-30, preferably 5-20, as the PL / acetone (A) ratio. The reaction temperature is generally 30 to 100 ° C., preferably 50 to 90 ° C., and the reaction pressure is generally normal pressure to 5 kg / cm ² · G.

  As the acidic catalyst, an inorganic acid such as hydrochloric acid, an organic acid, an ion exchange resin, or the like can be used. When an ion exchange resin is used as the acidic catalyst, a sulfonic acid type cation exchange resin having a gel type and a crosslinking degree of 1 to 8%, preferably 2 to 6% is suitable, but is not particularly limited. Further, hydrochloric acid may be used as the acid catalyst.

  The sulfonic acid cation exchange resin can be used as it is, but a modified sulfonic acid cation exchange resin can be used as necessary. Examples of the compound required for the modification include compounds having a mercapto group.

  Examples of the compound having a mercapto group include an aminoalkanethiol such as 2-aminoethanethiol, an ω-pyridylalkanethiol such as 2- (4-pyridyl) ethanethiol, and a mercapto group that is easily expressed by hydrolysis. Any known conventionally usable for this application, such as thiazolidine such as 2-dimethylthiazolidine, can be used.

  The reaction mixture produced in the step (a) generally contains by-products such as unreacted PL, unreacted acetone (A), catalyst, reaction product water (W) and colored substances in addition to BPA.

  The step (b) is a step of removing BPA low-boiling components and a catalyst such as hydrochloric acid from the reaction mixture obtained in the step (a). The BPA low-boiling component here is reaction product water (W), unreacted acetone (A), and those having boiling points close to these. In this step, these low-boiling components are removed from the reaction mixture by, for example, distillation under reduced pressure, and solid components such as the catalyst are removed by filtration or the like. In addition, when using a fixed bed catalyst reactor, there is no need for decatalysis. The distillation under reduced pressure preferably uses a pressure of 50 to 300 mmHg and a temperature of 70 to 130 ° C. The unreacted PL may be azeotropically removed and part of it may be removed from the system.

  The BPA low-boiling distillate (D4) distilled off in the step (b) contains water, a small amount of acetone (A), phenol (PL) and the like. As shown in FIG. 3, this BPA low-boiling distillate (D4) is sent to the PL separation tower 12 and, if necessary, a water separation step (step ( b-2)) is performed. The PL recovery liquid k obtained in this water separation step is recovered in the recovery PL tank 11 for BPA. The water / acetone mixture AW recovered from the top of the PL separation tower 12 is separately treated.

  The step (c) is a step in which the liquid mixture obtained in the step (b) is cooled, and a mixture of BPA and PL is precipitated and separated. Prior to this step (c), the concentration of BPA in the mixed solution obtained in the above step (b) is adjusted by distilling or adding PL so that the BPA concentration is 10 to 50% by weight, preferably 20%. Adjustment to -40% by weight is preferable for improving the workability by increasing the yield of the adduct and adjusting the apparent viscosity of the slurry mixture. Examples of the mixture of BPA and PL include adduct crystals of BPA and PL, and simple mixtures of BPA crystals and PL crystals.

  The cooling in the step (c) is generally performed to a temperature of 45 to 60 ° C., whereby an adduct crystal of BPA and PL or each crystal is precipitated, and the system becomes a slurry. This cooling is performed by heat removal by latent heat of evaporation of water applied to an external heat exchanger or crystallizer. Next, this slurry-like liquid is separated into crystals and a mother liquor containing reaction by-products by filtration, centrifugation, etc., and the crystals are subjected to the next step. Part or all of the separated mother liquor is recycled to step (a) via BPA mother liquor treatment step (g) described later, and used as part or all of PL used as a raw material, and further reacted Improve the yield.

  The step (d) is a step of heating and melting the crystal obtained in the step (c). The composition of the adduct crystal is generally in the range of 45 to 70% by weight of BPA and 55 to 30% of PL. The crystals are melted by heating to 100 to 160 ° C. and used for the next step.

  The step (e) is a step of obtaining molten BPA by removing PL from the melt obtained in the step (d). By removing PL from the melt obtained in step (d) by a method such as distillation under reduced pressure, the adduct is dissociated, and high-purity BPA can be recovered. The vacuum distillation is performed at a pressure of 10 to 100 mmHg, a temperature of 150 to 220 ° C., and a temperature at least 10 ° C. higher than the melting point of the mixed liquid of bisphenol A (BPA) and phenol (PL) present in the system. Is preferred. A method of removing residual PL by performing steam stripping in addition to vacuum distillation has also been proposed.

  The step (f) is a step of cooling and solidifying the molten BPA obtained in the step (e) and granulating it to obtain a granular product. The molten BPA is made into droplets by a granulator such as a spray dryer, and cooled and solidified to obtain a product. These droplets are prepared by spraying, dropping, spraying, etc., and cooling is usually performed by nitrogen or air.

  In this BPA production process, particularly in the above step (a), in addition to BPA, a by-product such as 2,4′-bisphenol A (hereinafter referred to as “BPA by-product”) is also synthesized. And this BPA by-product is mainly contained in the mother liquor of the said process (c), and circulates through the said BPA manufacturing process. For this reason, the BPA by-product tends to accumulate in this circulatory system, and if accumulation of a certain amount or more occurs, the separation in the step (c) becomes insufficient and is attached to the BPA side. , Tends to reduce the quality of the product BPA. For this reason, part or all of the mother liquor in the step (c) is subjected to a BPA mother liquor treatment step (step (g)) to separate and reduce the BPA by-product in the mother liquor. By using as a BPA production raw material, the quality of the product BPA can be maintained.

  In the step (g), PL is recovered by distillation, or the mother liquor is heated in the presence of a basic substance to decompose BPA by-products in the mother liquor to produce PL and PL derivatives, In this method, BPA is produced by reacting this with an acid catalyst or an alkali catalyst, and this is recovered.

  Specifically, as shown in FIG. 4, first, part or all of the mother liquor is introduced into the PL evaporator 13 and at the same time a basic substance such as sodium hydroxide or potassium hydroxide is introduced. Subsequently, it is heated to the boiling point of PL or higher to evaporate, and PL is extracted from the upper part of the PL evaporator 13. And the evaporation residue which has the said BPA and a BPA by-product as a main component from the lower part of PL evaporator 13 is sent to the residue reactor 14, and a decomposition reaction is carried out to the said BPA and a BPA by-product by applying heat of 180-300 degreeC. To obtain a decomposition product such as isopropenylphenol which is a reaction intermediate of BPA, and this is distilled from the top of the column. Moreover, the kettle residue produced in the residue reactor 14 is sent to a waste liquid treatment process (not shown) such as incineration as a waste liquid containing a large amount of organic content.

  The PL and PL derivatives, which are decomposition products of the BPA by-product, are distilled off from the upper part of the residue reactor 14 and sent to the regeneration reactor 15, but when taking out from the upper part of the residue reactor 14, the PL evaporator 13 Mix with the PL extracted from the top of the. Thereby, it can suppress that the density | concentration of PL derivative is diluted and an undesirable side reaction arises.

  Next, in the regeneration reactor 15, PL and PL derivatives, which are decomposition products of the BPA by-product, are reacted again using an acid catalyst to generate BPA and the like. This is mixed with the unreacted PL together with the PL used as the raw material and sent to the step (a). Since the BPA is recovered as it is through the step (c), and PL is used as a raw material, the production efficiency of BPA can be increased.

[PC manufacturing process]
The manufacturing process of the PC includes the process shown in FIG. That is, DPC and BPA produced by the above method are used as raw materials, and this and a basic catalyst (C2) such as an alkaline aqueous solution are introduced into the mixing tank 21, mixed, and then sent to the polymerization tank to be PC polymerized. Perform the process. The polymerization tank is not particularly limited as long as it can perform condensation polymerization while distilling off phenol produced as a by-product in the polymerization, and can be any tank of a vertical tank, a horizontal tank, and a tower tank. May be.

  Further, the number of the polymerization tanks is not particularly limited, but since the polymerization reaction is condensation polymerization while dephenolization is performed, in order to be able to change the polymerization conditions in accordance with the degree of polymerization, a plurality of polymerization tanks are provided. It is preferable to use it. In FIG. 5, three vertical polymerization tanks (first polymerization tank 22, second polymerization tank 23, and third polymerization tank 24) and one horizontal polymerization tank (fourth polymerization tank 25) are connected in series. The polymerization tank group was shown. The polymerization conditions in this case include, for example, 50 to 200 Torr at 200 to 250 ° C. in the first polymerization tank 22, 10 to 50 Torr at 230 to 280 ° C. in the second polymerization tank 23, 250 in the third polymerization tank 24. It can be 0.2 to 5 Torr at ˜300 ° C. and 0.05 to 2 Torr at 260 to 320 ° C. in the fourth polymerization vessel 25. In this way, by-product phenol (hereinafter abbreviated as “s-PL”) is distilled off as the polymerization proceeds, and PC having a desired degree of polymerization can be obtained.

  The PC evaporation component p mainly composed of s-PL generated in the PC polymerization step is liquefied by the heat exchangers 26 and 27 and the condenser 28 and sent to the PC recovery PL tank 29. Then, the remaining exhaust gas (D5) is sucked to the vacuum equipment side and sent to a processing step (not shown).

  The PC manufactured in the PC polymerization process is sent to the extruder 32. Here, while removing the contained volatile matter as exhaust gas (D5), the acid I and various additives J are added to neutralize the catalyst. And processing (not shown), such as pelletization, is performed, and PC as a product is obtained.

  The PC evaporation component p is liquefied and sent to the PC recovery PL tank 29 as described above. This PC evaporation component p contains s-PL as a main component, but contains DPC, BPA, DPC and BPA, which are raw materials, an oligomer in which one molecule to several molecules are condensation-polymerized, water derived from an alkaline catalyst, and the like. To do. For this reason, this PC evaporation component p is subjected to a PL distillation step to recover s-PL. As an example of the PL distillation step, a method using a two-stage distillation column as shown in FIG. 5 can be given as an example. First, in the first PL distillation column 30, water having a boiling point lower than that of PL is evaporated and distilled, and the PC low boiling point distillation component (D6) containing water as a main component and containing PL is removed. Next, the first-stage distillation residue q of the first PL distillation column 30 is sent to the second PL distillation column 31 to cut off the high-boiling fraction and to distill and recover s-PL. At the same time, the high-boiling PL distillation residue ( X2) is recovered.

[Treatment of byproduct phenol (s-PL) 1: moisture content of s-PL]
The water content in the s-PL distilled and recovered in the PL distillation step is preferably 0.2% by weight or less, preferably 0.1% by weight or less, more preferably 0.05% by weight or less, and 0.01% by weight. More preferred are: When it is more than 0.2% by weight, as described later, when it is sent to the DPC manufacturing process or the BPA manufacturing process, the catalytic activity is lowered in the DPC manufacturing process and the BPA manufacturing process. Is prone to hydrolysis and the like. For this reason, the production efficiency in the DPC production process and the BPA production process is likely to decrease. On the other hand, the lower the moisture content, the better. Therefore, the lower limit of the moisture content is 0% by weight.

  In the first PL distillation column 30, if water is to be distilled off from the PC evaporation component p by distillation, a considerable amount of PL accompanies the loss under normal distillation conditions. This is because water and PL are azeotropic. In order to prevent this loss, there are methods such as extractive distillation, eliminating the azeotropic property under reduced pressure conditions, increasing the number of theoretical plates and the reflux ratio, etc. Economically unfavorable. For this reason, in the first PL distillation column 30, the PC low-boiling distillate (D6) obtained by distilling part of the water together with PL under normal distillation conditions is used as the DPC washing step and / or BPA production in the DPC production step. It can send to the water separation process ((b-2) process) of a process.

  As distillation conditions for the first PL distillation column 30, the column top temperature is preferably not less than the boiling point of water and not more than the boiling point of phenol under a reduced pressure of atmospheric pressure to several tens of Torr. The top gas of the first PL distillation column 30 is a mixed gas of water and PL, and the top temperature is preferably adjusted to the boiling point in the composition of the target mixed gas. When the column top temperature is lower than the boiling point of water, the amount of water in the first stage residue q increases, and the amount of water in s-PL obtained in the second PL distillation column 31 may increase outside the above range. There is. On the other hand, if the tower top temperature is higher than the boiling point of PL, the amount of s-PL contained in the PC low boiling point distillate (D6) increases, and a large amount of energy is required for the recovery, which is not economical.

  Specifically, the PL content in the top gas of the first PL distillation column 30 is preferably 50% by weight or more, more preferably 70% by weight or more. The upper limit is preferably 99.8% by weight. If it is lower than 50% by weight, the removal of water from the PC evaporation component p becomes insufficient, and the amount of water in s-PL tends to increase. On the other hand, if it is higher than 99.8% by weight, the amount of s-PL contained in the PC low-boiling distillate (D6) increases, and a large amount of energy is required to recover s-PL.

  The s-PL thus obtained is used as part of the raw material for the DPC manufacturing process and the BPA manufacturing process.

  Specifically, in the DPC manufacturing process, s-PL is used in the DPC reaction process. When sent to the DPC reaction step, it can be used as a part or all of the raw material PL. At this time, since the contained water is within the above range, there is little influence on the reaction process, and the production efficiency of DPC can be maintained.

  Next, in the BPA production process, s-PL is used in the BPA reaction process (process (a)). When used in the BPA reaction step, it can be used as a part or all of the raw material PL. At this time, since the contained water is within the above range, there is little influence on the synthesis reaction step, and the production efficiency of BPA can be maintained.

[Treatment of PC low boiling point distillate (D6)]
As described above, the low boiling point distillate (D6) distilled off in the first PL distillation column 30 is the DPC washing step in the DPC manufacturing step and the water separation step ((b-2) in the BPA manufacturing step. By returning to the step), the PL in the PC low boiling point distillate (D6) can be recovered.

  Specifically, as shown in FIG. 1, when returned to the DPC cleaning step of the above DPC manufacturing step, for example, the alkali neutralization tank 4, the PL contained in the PC low boiling point distillate (D6) is an organic phase ( The reaction mixture is extracted as a mixed gas (F) in the first DPC distillation column 6 in the next step, and finally used as a raw material for DPC.

  Moreover, as shown in FIG.2 and FIG.3, when it returns to the water separation process ((b-2) process) of the said BPA manufacturing process, more specifically, for example, it returns to PL separation tower 12, PC low boiling point The PL contained in the residue (D6) is recovered from the bottom of the column as a PL recovery liquid k, and finally used as a raw material for BPA.

[Treatment of by-product phenol (s-PL) 2: Treatment of PC evaporation component in PC polymerization step]
As shown in FIG. 5, the PC evaporation component p containing phenol produced as a by-product in the polymerization step is liquefied by the heat exchangers 26 and 27 and the condenser 28 and sent to the PC recovery PL tank 29. The remaining exhaust gas (D5) is sent to a treatment process (not shown).

  By the way, impurities other than the byproduct phenol contained in the evaporation components of the first polymerization tank 22 to the third polymerization tank 24 are different from each other. Specifically, the evaporation component produced from the initial polymerization step includes impurities having a boiling point lower than that of PL, a small amount of a carbonyl compound, diphenyl carbonate, and the like as impurities in addition to the by-product phenol content. Since these impurities are raw materials and products in the above DPC manufacturing process and do not contain a high melting point material such as BPA, the evaporation components containing these impurities are not purified or have a low purity. By purification, it can be used as part of PL used in the DPC manufacturing process.

  On the other hand, in the evaporation component coming out of the polymerization process in the latter stage of the PC polymerization process, impurities having a boiling point higher than that of PL such as DPC, BPA, oligomers obtained from DPC and BPA as impurities other than by-product phenols Impurities having a boiling point lower than that of PL are hardly contained. These impurities are hydrolyzed in the BPA production process, become raw materials and products in this production process, and hardly contain alcohols and the like that cause a decrease in catalyst activity in the BPA production process. For this reason, the evaporation component containing these impurities can be used as a part of PL used in the BPA production process without purification or by purification with low purity.

  From this, as shown in FIG. 6, the evaporation component of the PC polymerization step can be collected in two. That is, the first PC evaporation component p1 containing a by-product phenol component recovered from the first polymerization tank 22, or the first polymerization tank 22 and the second polymerization tank 23, in the first polymerization stage 22, that is, the evaporation component in the previous polymerization step. , Sent to the first PC recovery PL tank 29a, and recovered from the evaporation component in the polymerization process in the later stage, that is, the polymerization tank after the second polymerization tank 23 or the polymerization tank after the third polymerization tank 24. The second PC evaporation component p2 containing the by-product phenol component can be sent to the second PC recovery PL tank 29b.

  The first PC evaporation component p1 recovered in this way can be used as a part of PL used as a raw material in the DPC manufacturing process without passing through the PL distillation process shown in FIG. Further, the second PC evaporation component p2 can be used as a part of PL used as a raw material in the BPA manufacturing process without passing through the PL distillation process shown in FIG.

  In the polymerization tank in which the first PC evaporation component p1 containing a by-product phenol component used in the DPC manufacturing process is obtained, that is, the first polymerization tank 22, or the first polymerization tank 22 and the second polymerization tank 23 are evaporated. It is preferable to provide reflux devices 33a and 33b for partially liquefying and refluxing the components. By providing the reflux devices 33a and 33b, among the components distilled from the first polymerization tank 22 or the first polymerization tank 22 and the second polymerization tank 23, the components having a boiling point higher than PL are returned to the polymerization tanks. The component having a higher boiling point than PL contained in the obtained first PC evaporation component p1 can be further reduced.

  By the way, the evaporation component recovered from the second polymerization tank 23 is sent to either the first PC recovery PL tank 29a or the second PC recovery PL tank 29b as described above. The selection of the recovery tank may be limited to one of the pipes. As shown in FIG. 6, the pipes connected to both of the recovery tanks are provided, and valves 34a and 34b are provided in the respective pipes. You may make it switch suitably. This is because the impurities other than the by-product phenol contained in the evaporation component recovered from the second polymerization tank 23 are relatively small, and can be used as the first PC evaporation component p1, or the second PC evaporation component This is because it can also be used as p2.

  The amount sent to the first PC recovery PL tank 29a or the amount sent to the second PC recovery PL tank 29b is the amount of evaporation component from each of the other polymerization tanks, in particular the amount sent from the second polymerization tank 23 to the first PC recovery PL tank 29a. It is adjusted by the amount of by-product phenol contained in the evaporation component and the impurity content contained in the evaporation component.

  Of the by-product phenol content contained in the evaporation component of the PC polymerization step, the amount that is sent to the DPC production step and used as part of the raw material PL, that is, the by-product phenol contained in the first PC evaporation component p1 The amount of the by-product phenol contained in the evaporation component of the PC polymerization step, that is, 50 to 50 to the total amount of the by-product phenol contained in the first PC evaporation component p1 and the second PC evaporation component p2. 95% by weight is preferable, and 50 to 70% by weight is preferable.

  Further, the amount of by-product phenol contained in the second PC evaporation component p2 is preferably 50 to 5% by weight with respect to the total amount of by-product phenol contained in the evaporation component of the PC polymerization step. % By weight is preferred.

  When the amount of by-product phenol contained in the first PC evaporation component p1 is less than 50% by weight, impurities having a lower boiling point than DPC, particularly alcohol, etc. are mixed in the second PC evaporation component p2 and used as it is as a raw material for producing BPA. Then, reaction activity tends to decrease, which is not preferable. On the other hand, if it is more than 95% by weight, BPA or oligomer having a boiling point higher than that of DPC may be mixed in the first PC vaporized component p1, which may lead to blockage of the pipe during DPC production.

  Also, the content of high boiling point compounds having a higher boiling point than DPC, such as BPA and oligomers obtained from DPC and BPA, contained in the first PC vaporization component p1, used in the DPC production process Is preferably 1.0% by weight or less, and more preferably 0.1% by weight or less. If the amount is more than 1.0% by weight, there is a possibility that the piping may be blocked during the production of DPC.

  Further, the evaporation component used in the BPA production process, that is, a low-boiling compound having a lower boiling point than DPC contained in the second PC evaporation component p2, specifically, a carbonyl compound, an alcohol by-produced from the carbonyl compound, etc. The content of is preferably 100 ppm by weight or less, and more preferably 50 ppm by weight or less. In addition, the PL used as a raw material in the BPA production process is a commercially available phenol as a deficiency in addition to the regenerated phenol content contained in the first PC evaporation component p1 and the second PC evaporation component p2, and also BPA production. Includes PL that circulates through the process. Therefore, the content of the low boiling point compound in PL used as the raw material is less than the content of the low boiling point compound in the byproduct phenol, and is usually 20 ppm by weight or less, preferably 5 ppm by weight or less. is there. If it is more than 20 ppm by weight, the catalyst activity during the production of BPA may be reduced, leading to a reduction in productivity.

  When the carbonyl compound is a dialkyl carbonate and / or an alkylaryl carbonate, the alcohol by-produced from the carbonyl compound is an alkyl alcohol obtained from the dialkyl carbonate and / or the alkylaryl carbonate.

  In this way, the PC evaporation component p is divided into two and sent to the DPC manufacturing process and the BPA manufacturing process according to the type of impurities, so that the PL distillation process can be omitted in the PC manufacturing process, and the manufacturing efficiency It can contribute to improvement.

[Treatment of by-product phenol (s-PL) 3: Classification of usage by impurities of PC evaporation component p and commercial PL]
By the way, when the DPC manufacturing process, the BPA manufacturing process, and the PC manufacturing process are of the same scale, the amount of s-PL generated in the PC manufacturing process shown in FIG. 5 is theoretically used as a raw material in the DPC manufacturing process and the BPA manufacturing process. The amount used as a raw material in the DPC manufacturing process is approximately the same as the amount used as a raw material in the BPA manufacturing process, which is about half of the total amount used. The shortage is supplemented with commercially available PL (hereinafter simply referred to as “commercial PL”). For this reason, it may be a problem how to use s-PL or commercially available PL.

  Generally, commercially available PL contains impurities such as cresol and / or xylenol and hydroxyacetone to some extent, while the PC evaporation component p, which is a component before s-PL is distilled and recovered, includes cresol and / or Or the content of impurities such as xylenol and hydroxyacetone is low. For this reason, the usage method of s-PL can be determined by the difference in content of impurities such as cresol and / or xylenol and hydroxyacetone.

  Specifically, as PL used as a raw material for the DPC production process, phenol containing 20 to 1000 ppm by weight of cresol and / or xylenol (hereinafter referred to as “cresol containing PL”) is used to produce BPA. As PL used as a raw material of the process, it is preferable to use phenol containing cresol and / or xylenol in an amount of less than 20 ppm by weight (hereinafter referred to as “PL not containing cresol or the like”).

  Examples of the PL containing cresol include commercially available PL. In addition to the above-mentioned cresol and xylenol, this commercially available PL contains several tens of ppm by weight of impurities causing coloring such as hydroxyacetone.

  This cresol-containing PL can be used as it is in the DPC reaction step as described above. The amount of impurities such as cresol, xylenol and hydroxyacetone, which are impurities in the PL containing cresol and the like, is in an allowable range in the DPC reaction step. Then, it is evaporated as a part of the mixed gas F or removed as a distillation residue by the first DPC distillation column 6 described later. For this reason, even if it uses DPC manufactured using this cresol etc. containing PL for the said PC manufacturing process, the quality of obtained PC is not affected.

  An example of the cresol-free PL is a PC evaporation component p that is a component before s-PL is distilled and recovered. The content of catalyst poison-causing impurities such as hydroxyacetone contained in the PC evaporation component p is preferably less than 10 ppm, more preferably less than 5 ppm, and even more preferably less than 1 ppm. If it is 10 ppm or more, the life of the catalyst is significantly reduced as a result.

  As impurities contained in the PC evaporation component p, in addition to the above-described catalyst poisoning cause substances and coloring cause substances such as cresol, xylenol, and hydroxyacetone, oligomers in which DPC, BPA, DPC, and BPA are reacted by several molecules, etc. Is included.

  The content of cresol and / or xylenol contained in the PC evaporation component p is preferably 20 ppm by weight or less, and more preferably 10 ppm by weight or less. When the content is more than 20 ppm by weight, an alkyl-substituted product of BPA is produced, which may cause a decrease in the purity of BPA.

  The PC evaporation component p contains water. The presence of water causes a decrease in the activity of the catalyst in the BPA production process, leading to a decrease in the production rate of BPA. For this reason, a process for removing moisture is required. In order to do this, it is preferable to use the PC evaporation component p in the step (a) of the BPA manufacturing step after the step of removing water.

  As the step of removing the water, the water separation step (step (b-2)) can be used as it is. That is, in FIG. 3, the PC evaporation component p used as a raw material is sent to the PL separation tower 12, and a water removal process is performed. At this time, the water / acetone mixture AW to be distilled off is treated separately. The distillation residue of the PL separation tower 12 is not shown in FIGS. 2 and 3, but is sent to a high boiling removal tower to perform a high boiling point removal step for separating components having a higher boiling point than PL. Ingredients are separated and removed as the residue in the still, and PL is recovered as the distillate.

  The recovered PL may be directly used as the raw material PL for the BPA reaction step (step (a)) in the BPA production step, or once recovered in the BPA recovery PL tank 11. 2 may be used for the BPA reaction step (step (a)) via the step (c) shown in FIG. 2 and, if necessary, the mother liquor treatment step (step (g)). The BPA crystallization / separation step (step (c)) is provided because it is preferable to use clean PL for use as a cleaning solution for the synthesized BPA, and the BPA crystallization / separation step is performed. Even when subjected to the separation step (step (c)), the impurities mixed in this step are the 2,4′-isomer of BPA produced in the BPA reaction step (hereinafter referred to as “BPA by-product”). This is because the synthetic reaction step is not affected. On the other hand, the high-boiling component discharged from the high-boiling component removal step is sent to the mother liquor treatment step (g) described above, and the active component can be recovered.

  In this way, when the PC evaporation component p is sent to the BPA manufacturing process and commercially available PL is used in the DPC manufacturing process, adverse effects due to impurities contained therein can be suppressed, and the PL distillation process is omitted in the PC manufacturing process. Can contribute to the improvement of manufacturing efficiency.

[Cooperation between manufacturing processes-Installation of storage processes]
(1. PC manufacturing process)
In the PC manufacturing process, as shown in FIG. 7, before and / or after the PL distillation process, the PC evaporation component p liquefied before being subjected to the PL distillation process and / or recovered in the PL distillation process. In addition, a PC storage step (PC first storage step or PC second storage step) for storing s-PL can be provided. By providing the PC storage step, even if the PC polymerization step is temporarily stopped or intermittent, the PC evaporation component p or s-PL is stored in the PC storage step, and this is followed by The process can be continuously supplied as a raw material PL for the PL distillation process, DPC reaction process or BPA reaction process, and the next process can be operated continuously.

The capacity of the PC storage tank used in the PC storage process may be determined in consideration of the operation time and stop time of the PC polymerization process. Specifically, the capacity satisfies the condition of the following formula (1). It is preferable.
10 ≦ (Vc / Fc) ≦ 100 (1)
In the formula (1), Vc represents the capacity (m ³ ) of the PC storage tank, and Fc represents the supply rate (m ³ / hr) of the PC evaporation component liquefaction product or by-product phenol.

  If Vc / Fc is smaller than 10, it may be difficult to continuously supply the PC evaporation component p or s-PL to the next step. And it becomes difficult to adjust the composition fluctuation | variation of the PC evaporation component p accompanying the change of PC manufacture grade. On the other hand, it may be larger than 100, but if it is too large, it is not necessary to store so much from the viewpoint of production efficiency, but rather it is wasted, and an unnecessary holding time is preferable from the viewpoint of thermal stability. Absent.

  The PC storage tank may be provided only in one of the PC first storage process and the PC second storage process, or may be provided in both. In one PC storage step, one PC storage tank may be provided, or a plurality of PC storage tanks may be provided in series or in parallel. In addition, Vc of said Formula (1) in the case of providing two or more means the total amount of the capacity | capacitance of the tank which exists two or more.

(2. DPC manufacturing process)
In the DPC manufacturing process, as shown in FIG. 7, a DPC storage process for storing DPC obtained in the DPC distillation process can be provided after the DPC distillation process. By providing this DPC storage process, even if the DPC manufacturing process is temporarily stopped or intermittent, DPC is stored in this DPC storage process, and this is the next process raw material. The PC can be continuously supplied as a DPC, and the PC can be continuously manufactured.

The capacity of the DPC storage tank used in the DPC storage process storage process may be determined in consideration of the operation time and stop time of the DPC manufacturing process. Specifically, the capacity satisfies the condition of the following formula (2). It is preferable to do.
10 ≦ (Vd / Fd) ≦ 100 (2)
In the formula (2), Vd represents the capacity (m ³ ) of the DPC storage tank, and Fd represents the supply rate (m ³ / hr) of diphenyl carbonate.

  If Vd / Fd is smaller than 10, it may be difficult to continuously supply the DPC to the next process. On the other hand, it may be larger than 100, but if it is too large, it is not necessary from the viewpoint of production efficiency to store it so much, but it is useless, which is not preferable from the viewpoint of thermal stability.

  One DPC storage tank may be provided, or a plurality of DPC storage tanks may be provided in series or in parallel. In addition, Vd of the said Formula (2) in the case of providing two or more means the total amount of the capacity | capacitance of the tank which exists in plurality.

(3. BPA manufacturing process)
In the BPA manufacturing step, after the PL removal step ((e) step) as shown in FIG. 7 or although not shown, the BPA crystallization / separation step ((c) step) to the PL removal step ((e) BPA storage step for storing the mixture of bisphenol A (BPA) and phenol (PL) is provided.

  By providing this BPA storage step, any step of the BPA production step is temporarily stopped, and even if the step before the stopped step becomes intermittent, the mixture is stored in this BPA storage step, This can be provided to the PC manufacturing process, and the PC can be manufactured continuously.

  In particular, the BPA crystallization / separation step (step (c)) tends to cause solids to adhere to the wetted part of the crystallization apparatus such as the crystallization tank and heat exchanger used, and once every few months. Needs to stop this process and clean it. For this reason, the process from the BPA reaction step (step (a)) to the BPA crystallization / separation step (step (c)) tends to be intermittent. Therefore, after the PL removal step ((e) step) or not shown, the BPA storage is performed during the period from the BPA crystallization / separation step ((c) step) to the PL removal step ((e) step). Even if the process from the BPA reaction process (process (a)) to the BPA crystallization / separation process (process (c)) becomes intermittent by providing the process, the PC manufacturing process is continuously performed. be able to.

  Examples of the form of the mixture stored in the BPA storage step include an adduct crystal of BPA and PL, a slurry containing an adduct crystal of BPA and PL, a mixed solution of BPA and PL, and the like.

  The composition of the mixture of BPA and PL is generally in the range of 45 to 70% by weight of BPA and 55 to 30% of PL. For this reason, when the temperature at the time of said storage is 0-95 degreeC, an adduct will be in a crystalline state. Moreover, when the phenol ratio in said mixture is high, when storage temperature will be 40 degreeC or more, since BPA and PL which is not added will be in a molten state, it will become a slurry form or a solution. Furthermore, when the storage temperature exceeds 95 ° C., the adduct is melted, so that it becomes a molten state.

  The storage temperature is preferably 45 to 150 ° C., and it is desirable that the mixture of BPA and PL is in a slurry or solution state. In order to prevent the decomposition and coloring of BPA, it is preferable to keep the temperature as low as possible. Under the above conditions, the production of 4-isopropenylphenol, which is considered to be a color-causing substance caused by the decomposition of BPA, is suppressed. Is possible.

  Furthermore, it is also important to make the inside of the storage tank an inert gas atmosphere such as nitrogen gas to prevent air from entering. In addition, the material of the storage tank can be general austenitic stainless steel or ferritic stainless steel, but those with less elution of Fe that cause a decrease in color tone are preferably used. A steel material having a content of 16% or more and a carbon content of 0.03% or more, for example, SUS304 is preferable to SUS316, and SUS316 and SUS304 are preferably used to SUS316L and SUS304L. Naturally, SUS309S and SUS310S with higher Cr content are more preferable directions.

The capacity of the tank for storing the mixture of BPA and PL may be determined in consideration of the operation time and stop time of the BPA production process. Specifically, it is preferable that the condition of the following formula (3) is satisfied. .
10 ≦ (Vb / Fb) ≦ 1000 (3)
In the formula (3), Vb indicates the capacity (m ³ ) of the BPA storage tank, and Fb indicates the supply amount (m ³ / hr) of bisphenol A used in the PC polymerization process.

If Vb / Fb is smaller than 10, it may be difficult to perform the PC polymerization step continuously. On the other hand, it may be larger than 1000, but if it is too large, it is not necessary to store it so much from the viewpoint of production efficiency, but it becomes useless, and long-term storage is not preferable from the viewpoint of quality.
One storage tank may be provided, or a plurality of storage tanks may be provided in series or in parallel. In the case where a plurality of tanks are provided, Vb in the above formula (3) means the total amount of tank capacities.

  In the BPA storage step, the adduct having the above-described form is stored. Therefore, when the pH becomes acidic or alkaline, a decomposition reaction of BPA tends to occur. In order to prevent this, it is preferable to provide a BPA neutralization step in the BPA storage tank existing between the BPA crystallization / separation step (step (c)) and the PC polymerization step, or in the previous step. (Not shown). In this BPA neutralization step, the acid component or the base component in the mixture can be neutralized, and the decomposition of BPA in the mixture can be suppressed.

[Drainage treatment]
(Treatment of PL distillation residue (X2))
The PL distillation residue (X2) contains an oligomer in which one molecule to several molecules of PL, DPC, BPA, DPC, and BPA are polycondensed, and among them, PL, BPA, and DPC are mostly included. . Therefore, in order to effectively utilize these active ingredients, as shown in FIG. 8, the above-mentioned PL distillation residue (X2) is converted into the above-mentioned distillation step or the recovered distillation step of the DPC manufacturing step, or the above-mentioned BPA manufacturing step. It sends to a mother liquid processing process (process (g)).

  In the DPC production process, when the above-mentioned PL distillation residue (X2) is sent to the distillation process of the DPC production process without having the recovery distillation process, specifically, as shown in FIG. The PL distillation residue (X2) is sent to the first DPC distillation column 6. Thereby, the said PL distillation residue (X2) is distilled by the 1st DPC distillation column 6 and the 2nd DPC distillation column 7, and collect | recovers PL and DPC. Among these, PL is recovered as a component of the mixed gas (F) in the first DPC distillation column 6, and DPC is recovered in the second DPC distillation column 7.

  In the DPC manufacturing process, when the recovery distillation process is included and the PL distillation residue (X2) is sent to the recovery distillation process of the DPC manufacturing process, specifically, as shown in FIG. The PL distillation residue X2 is sent to the DPC recovery distillation column 8. As a result, the PL distillation residue (X2) is distilled in the DPC recovery distillation column 8 to recover PL and DPC and sent to the mixing tank 3. Among these, PL is recovered as a component of the mixed gas (F) in the first DPC distillation column 6, and DPC is recovered in the second DPC distillation column 7.

  Moreover, when sending said PL distillation residue (X2) to the said mother liquid processing process (process (g)) of the said BPA manufacturing process, specifically, as shown in FIG. 4, said PL distillation residue (X2) To the residue reactor 14. As a result, PL is distilled off as it is, but other components are decomposed, BPA and the like are generated again in the regeneration reactor 15, and sent to a BPA reactor (not shown) in the BPA production process. Thereby, PL is used as a raw material, and BPA moves integrally with BPA synthesized as it is.

(Treatment of distillation residue (X1) or recovered distillation residue (X1 ′))
In the DPC production process, the distillation residue (X1) when the recovery distillation process is not included, or the recovery distillation residue (X1 ′) when the recovery distillation process is included is DPC or a methyl substitution product of DPC. DPC-based impurities such as DPC bromine-substituted products are included, and when the above PL distillation residue (X2) is introduced into the distillation step or the recovery distillation step, a combination of BPA, DPC and BPA 1 Although the molecule | numerator-several molecules contain the oligomer etc. which several molecules condensed, among these, many BPA and DPC are included. Therefore, in order to effectively use these active ingredients, the distillation residue (X1) or the recovered distillation residue (X1 ′) is sent to the mother liquor treatment step (step (g)) of the BPA production step.

  In this case, specifically, as shown in FIG. 4, the distillation residue (X1) or the recovered distillation residue (X1 ′) is sent to the residue reactor 14. As a result, each component is decomposed, and a part thereof is converted again into BPA in the regeneration reactor 15, and the obtained BPA and phenol are sent to a BPA reactor (not shown) in the BPA production process.

(PL distillation residue (X2) and distillation residue (X1) or recovered distillation residue (X1 ′))
Examples of the treatment method for the PL distillation residue (X2), the distillation residue (X1), and the recovered distillation residue (X1 ′) include the above methods. Among these, the PL distillation residue (X2) is converted into the DPC distillation step. It is preferable to send the DPC distillation residue (X1) and DPC recovery distillation residue (X1 ′) generated in the DPC distillation step to the BPA mother liquor treatment step (step (g)).

  By doing in this way, drainage from the DPC manufacturing process, BPA manufacturing process, and PC manufacturing process is drained from the mother liquor treatment process (process (g)) of the bisphenol A (BPA) manufacturing process (D7). To one of these. In this way, the waste liquid containing a large amount of organic matter generated in each of the three steps can be combined into one, and the discharge amount as a whole waste liquid can be suppressed. The process (not shown) becomes efficient and the load can be reduced.

[Vacuum equipment]
The above DPC distillation process, PC polymerization process, and PL distillation process distillation apparatus and polymerization apparatus are connected to a condenser for condensing distillate components, vacuum equipment for reducing the pressure in the system, and the condenser and vacuum equipment. Vacuum piping is provided. Hereinafter, a distillation apparatus will be described as an example.

  As shown in FIG. 9, the distillation apparatus 41 such as a distillation tower includes a condenser 42 for condensing substances such as DPC and PL, a vacuum equipment 43 for reducing the pressure in the system, and the condenser 42. A vacuum pipe 44 that connects the vacuum equipment 43 is provided.

  In this distillation apparatus 41, a reflux part is often formed. As a device for forming the reflux portion, a condenser 42 for condensing the substance to be distilled, a condensate tank 45 for storing a part of the condensed liquid, and a condensate in the condensate tank 45 are sent back to the distillation device 41. A liquid pump 46 and a reflux pipe 47 that connects the liquid feed pump 46 and the distillation apparatus 41 are included. Hereinafter, this reflux portion is referred to as a “reflux device”.

  The vacuum facility 43 is a facility for sucking and discharging the gas in the distillation apparatus 41 and the reflux apparatus to bring the distillation apparatus 41 into a reduced pressure state. An example of such a vacuum facility 43 is a vacuum pump.

  The vacuum piping 44 connected to the vacuum facility 43 has a downward slope from the condenser 42 side toward the vacuum facility 43 side. It is desirable that this inclination be as long as possible in the horizontal portion of the vacuum pipe 44. Further, the above inclination may be greater than 0 ° downward from the horizontal direction and 90 ° or less, but when traveling 2 m in the horizontal direction toward the vacuum facility, it is desirable to proceed downward by 1 cm or more, It is more desirable if it goes down from 5 cm to 1 m. Further, it is more desirable that the inclined horizontal portion does not have a completely horizontal portion and a rising portion, and more desirably, the inclination is constant from end to end of the vacuum pipe 44. The horizontal portion refers to a horizontal state and a portion that is slightly inclined from the horizontal state. The completely horizontal portion is a portion perpendicular to the vertical direction.

  The slope may have the above-mentioned completely horizontal part or a rising part in the middle, but the total height of the rising part is preferably 1 m or less, more preferably 50 cm or less, and 10 cm or less. More preferably, there is no such part most preferably. If the total height of the rising portions exceeds 1 m, the pressure loss generated when the distillate accumulates in the rising portions becomes too large, and there is a possibility that the vacuum suction cannot be performed. In addition, said rising part means the part which has an inclination upward toward the vacuum equipment 43 from the condenser 42 contrary to said inclination. Here, the distillate is likely to be stored as a liquid or a solid. If the distillate is stored, a pressure loss occurs. If the distillate is excessively stored, the tube itself may be blocked. Therefore, it is more desirable if the above-mentioned inclination is only downward from the condenser 42 side toward the vacuum equipment 43 side.

  The condenser 42 condenses PL, DPC, and the like. The condensed distillate is withdrawn out of the system or sent to the condensate tank 45 of the reflux device for reflux to the distillation device 41.

  The pressure in the distillation column 41 is preferably a reduced pressure, more preferably 1 to 200 Torr, and particularly preferably 5 to 100 Torr. At that time, the vacuum-depressurized pressure in the vacuum pipe 44 for drawing the gas in the distillation column 41 is preferably close to or lower than the pressure in the distillation column 41, and more preferably 1 to 100 Torr.

  Furthermore, the piping structure from the top of the distillation column 41 to the condenser 42 preferably satisfies the following conditions. The inner diameter of the pipe is desirably in a range where the actual gas linear velocity is 0.01 to 20 m / sec. The length of the pipe from the top of the distillation column 41 to the condenser 42 should be as short as possible, preferably 10 m or less, and most preferably 0 m. Furthermore, the smaller the number of bent portions of the piping, the better. From these conditions, it is most desirable that the condenser 42 is provided at the top of the distillation column 41 as a top condenser. When these conditions are satisfied, the vacuum reduced pressure state of the distillation column 41 by the vacuum equipment 43 is further stabilized.

  The distilled PL or DPC gas is desirably supplied so as to flow from the top to the bottom of the condenser 42. Moreover, it is desirable that the inside of the condenser 42 and the outlet portion have a large diameter so that the gas linear velocity is reduced. If the gas linear velocity is high, it may cause pressure loss, and the vacuum depressurization of the distillation apparatus 41 may not be maintained.

  It is desirable that a mist catcher 48 for capturing mist is provided between the condenser 42 and the vacuum pipe 44. This is to prevent the mist-like PL and DPC from being mixed into the vacuum pipe 44 and collecting or solidifying as much as possible.

  The vacuum pipe 44 preferably has a facility for heating and keeping the temperature above the melting point of the distillate. As the equipment, for example, the vacuum pipe 44 may be a double pipe structure or a trace structure using steam or electricity. In addition, when the said distillate consists of a some component, it is desirable that it is more than melting | fusing point of the substance with the highest melting | fusing point in them. Moreover, although the inside of the said vacuum piping 44 is a pressure reduction state, melting | fusing point is melting | fusing point in a pressure reduction state here. If the inside of the vacuum pipe 44 is equal to or higher than the melting point of the distillate, the PL and DPC that cannot be fully condensed by the condenser 42 and remain mixed in the vacuum pipe 44 remain liquid or gas without solidifying. The possibility of clogging the inside of the pipe 44 can be further reduced. For this reason, it is desirable in terms of operation of the process that the melting point of DPC is 80 ° C. or higher and is equal to or lower than the temperature at the top of the distillation apparatus 41.

  In addition, it is desirable to provide at least one drainage port 49 in the vacuum pipe 44 toward the lower side. This is because the distillate that has been liquefied or dewed in the vacuum pipe 44 needs to be extracted without remaining in the vacuum pipe 44. It is desirable that at least one of the liquid drain ports 49 is close to a portion connected to the vacuum equipment 43 of the vacuum pipe 44. This is because, since the vacuum pipe 44 has an inclination, the distillate may accumulate before the vacuum pipe 44 is extracted from a position as close as possible to the bottom of the inclination. Such extraction of the liquid may be performed while the entire apparatus is stopped, not during vacuum decompression by the vacuum equipment 43. Further, when the length of the vacuum pipe 44 exceeds 3 m, it is more desirable to provide the liquid drain port 49 in the middle of the vacuum pipe 44 because it is easy to avoid the liquid pool.

  Furthermore, it is desirable that the vacuum pipe 44 on the condenser 42 side be provided with a supply port 50 capable of supplying a heating fluid. The position where the supply port 50 is provided is preferably closer to the condenser 42, but when the mist catcher 48 is present between the vacuum pipe 44 and the condenser 42, the mist catcher 48 and the condenser 42 are provided. It is desirable not to be between, but as close as possible to where the vacuum pipe 44 is connected to the mist catcher 48. By providing this supply port 50, the heating fluid can be poured from here and extracted from the liquid drain port 49, and the vacuum pipe 44 can be washed. Therefore, it is desirable that the portion between the supply port 50 and the liquid discharge port 49 occupy as long a region as possible in the vacuum pipe 44. Moreover, since there is an inclination, it is more efficient to supply from the one with higher potential energy. For this reason, it is desirable that the supply port 50 be open toward the upper side of the vacuum pipe 44.

  The heating fluid refers to a fluid that is fluid at the temperature in the vacuum pipe 44, and may be liquid or gas. Examples of the heating fluid include water vapor, PL, nitrogen, and the like, and water vapor or PL vapor is more desirable. The use of PL vapor is more desirable because it can be dissolved when the DPC is solidified inside the vacuum pipe 44. Only one of these or a plurality of mixtures may be used. However, it is desirable that the heating fluid does not substantially react with the material of the vacuum pipe 44, the DPC, or the like under the temperature and pressure conditions in the vacuum pipe 44, and more desirably does not react at all.

  Further, it is desirable that the vacuum pipe 44 is provided with valves 51 and 52 at portions connected to the condenser 42, the vacuum equipment 43, the mist catcher 48, and the like. This is because the heating fluid can be prevented from leaking out of the vacuum pipe 44 when it is blocked by a valve when washing with the heating fluid.

  Furthermore, it is desirable that the vacuum pipe 44 is provided with a freeze capacitor (not shown). It is more desirable that two or more freeze capacitors are installed in parallel and can be switched. If the freeze condenser is installed, the distillate component that could not be captured by the condenser 42 can be forcibly solidified and collected, and the subsequent vacuum piping 44 can block or increase pressure loss. It can be suppressed and desirable.

  When distilling off low-boiling compounds such as PL from DPC, it is also effective to use two or more condensers 42 connected in series in order to liquefy the evaporated gas distilled from the distillation apparatus 41. is there. At that time, it is preferable that the temperature of each condenser 42 is gradually lowered as the temperature of each condenser 42 increases from the distillation apparatus 41. In particular, the first condenser 42 is adjusted to 80 to 150 ° C. in order to actively condense high-boiling components such as DPC, and the liquefied condensate is circulated to the distillation apparatus 41. Next, the uncondensed gas that has not been liquefied in the first condenser 42 is adjusted to 0 to 80 ° C. in the second and subsequent condensers 42 and is almost completely liquefied. A part of the liquefied condensate is refluxed to the distillation apparatus 41 as necessary, and the remaining or the entire amount is distilled. If two or more condensers 42 are installed in this way, even if a large amount of DPC is distilled from the distillation apparatus 41, the operation can be continued without solidifying and blocking in the condenser 42, and distillation can be performed stably for a long time. It can be carried out. The freezing point of DPC is 80 ° C., which is higher than the freezing point of PL (40 ° C.). Therefore, under the temperature condition of the condenser 42 that condenses only low boiling point compounds such as ordinary PL, There is a risk that the DPC will solidify within 42. Therefore, if two or more condensers 42 are installed, the high melting point DPC is forcibly condensed and removed, and then the uncondensed gas is condensed to prevent solidification, and the degree of vacuum of the distillation apparatus 41 is stabilized. Can do. In addition, as a light boiling component to be distilled off, it is more preferable to use this multi-stage condenser 42 in the case of containing more low-boiling compounds than PL in addition to PL.

  Next, the above reflux device will be described with reference to FIG. By using this reflux device, it is possible to increase the efficiency of distillation separation while suppressing evaporation of high boiling point components.

  The horizontal portion of the reflux pipe 47 for refluxing the condensate in the condensate tank to the distillation apparatus 41 by the liquid feed pump 46 has a downward slope from the distillation apparatus 41 side to the liquid feed pump 46 side. It is good to be. It is preferable that there is no complete horizontal part or rising part in the middle of the horizontal part having this inclination, and it is more desirable if the inclination is constant. At this time, the inclination is preferably 1 cm or more downward when traveling 2 m in the horizontal direction toward the liquid feed pump 46, and more preferably 5 cm to 1 m downward. If there is a completely horizontal part or a rising part, it is necessary that the height difference due to the inclination is larger than the total height difference of the rising part, and the total height of the rising part is 1 m or less It is desirable that it is 10 cm or less. Here, the above-mentioned rising portion refers to a portion inclined upward from the distillation apparatus 41 side toward the liquid feed pump 46 side, contrary to the above inclination.

  Although depending on the position of the liquid feed pump 46, as shown in FIG. 9, the gradient between the horizontal portion of the reflux pipe 47 and the liquid feed pump 46 is vertical or nearly vertical. There may be parts. At this time, in order to extract the liquid accumulated before and after the liquid feed pump 46, liquid drain ports 53 and 54 may be provided in the pipes near the suction port and the discharge port of the liquid feed pump 46.

  It is desirable that the above-described reflux pipe 47 has a facility for heating and keeping the temperature above the melting point of the distillate. In addition, when said distillate consists of a some component, it is desirable that it can heat and hold | maintain above the melting | fusing point of the substance with the highest melting | fusing point among them. If the reflux pipe is at or above the melting point of the distillate, the distillate remains liquid or gas without solidifying, so the possibility of clogging inside can be further reduced. Examples of the equipment for heating and heat-retaining in this way include those having a double-pipe structure or a trace structure using steam or electricity.

  It is desirable that a supply port 55 is provided at a location near the distillation column 41 of the reflux pipe 47. When the operation of the entire apparatus is stopped, the reflux pipe 47 can be washed by flowing the heating fluid from the supply port 55 and extracting it from the liquid discharge port 54. At that time, it is desirable that a valve 56 is provided between the reflux pipe 47 and the distillation apparatus 41 so that the heated fluid does not flow into the distillation apparatus 41.

  The distillation apparatus for distilling PL and DPC as described above is a PC polymerization process, a DPC distillation process for recovering purified DPC by removing impurities such as PL from DPC, or DPC and BPA under vacuum It can be used for recovering PL and DPC in a PL distillation step of a PC manufacturing process in which PC is polymerized while recovering PL (s-PL) produced as a by-product by reaction. Furthermore, any process that distills PL or DPC can be used.

  In addition, the reflux apparatus for refluxing PL or DPC as described above returns the PL or DPC distilled from the exemplified distillation apparatus 41 to the distillation apparatus 41 and has a high boiling point contained in the supplied PL or DPC. In addition to the process of suppressing evaporation of components and increasing the efficiency of distillation separation, any process that needs to be refluxed can be used. The high boiling point component can be extracted separately from the lower part of the distillation apparatus 41.

  Moreover, when these apparatuses are used for the manufacture of DPC, there is preferably a take-out port 57 for taking out the DPC out of the system at a location other than the horizontal portion having the above-mentioned inclination in the reflux pipe 47.

  In these steps, by using each of the above-described devices, even when the inside of the pipe is blocked, the blockage can be easily released by the cleaning method of supplying the heated fluid from the supply ports 50 and 55 provided in the respective devices. Can do.

Hereinafter, the present invention will be described more specifically with respect to the s-PL process.
(Production of dehydrated s-PL)
[PC polymerization process]
Under a nitrogen gas atmosphere at 130 ° C., BPA (made by Mitsubishi Chemical Corporation, obtained in Reference Example 2 described later) at 34.3 kg / hr, DPC (Mitsubishi Chemical Corporation, Reference Example described later) 1) was melt-mixed at 33.5 kg / hr and heated in a first vertical stirring polymerization tank controlled at 210 ° C. under a normal pressure and nitrogen atmosphere through a raw material introduction tube heated to 130 ° C. The liquid level was kept constant while controlling the valve opening degree provided in the polymer discharge line at the bottom of the tank so that the average residence time was 60 minutes. At the same time as the supply of the raw material mixture was started, cesium carbonate as an aqueous solution as a catalyst was continuously supplied at a flow rate of 0.5 × 10 ⁻⁶ mol to 1 mol of BPA. The polymerization liquid discharged from the tank bottom was continuously continuously supplied to the second, third and fourth vertical polymerization tanks and the fifth horizontal polymerization vessel. During the reaction, the liquid level was controlled so that the average residence time in each tank was 60 minutes, and at the same time, PL produced as a by-product was distilled off. The gas evaporating from the first to third polymerization tanks was condensed and liquefied by a multistage condenser, part of which was refluxed to each polymerization tank, and the rest was collected in the s-PL tank. On the other hand, the gas evaporating from the 4th to 5th polymerizers is solidified by one of the two freeze condensers in parallel, and the solidified part is melted by switching operation with the other freeze condenser and recovered in the s-PL tank. It was.

  The polymerization conditions of each reaction tank were as follows: first polymerization tank (210 ° C., 100 Torr), second polymerization tank (240 ° C., 15 Torr), third polymerization tank (260 ° C., 0.5 Torr), fourth polymerization tank (270 ° C.). 0.5 Torr). The polycarbonate production rate was 38.3 kg / hr and the operation was performed for 400 hours.

  This polymer was introduced in a molten state into a twin-screw extruder (manufactured by Kobe Steel, Ltd., screw diameter 0.046 m, L / D = 40.2), and butyl p-toluenesulfonate equivalent to 5 ppm per polycarbonate. Was added continuously. The butyl p-toluenesulfonate was dispersed in flaky polycarbonate using a mixer to prepare a master batch, and was fed into the extruder under nitrogen using a weight feeder and pelletized. The polycarbonate obtained had a viscosity average molecular weight (Mv) of 21,000 and an initial hue (YI) of 1.7.

<Measurement of viscosity average molecular weight (Mv)>
Using a methylene chloride solution having a PC concentration (C) of 0.6 g / dl, the specific viscosity (ηsp) measured at a temperature of 20 ° C. with an Ubbelohde viscometer was used to calculate the following formula.
ηsp / C = [η] (1 + 0.28 ηsp)
[Η] = 1.23 × 10 ⁻⁴ (Mv) ^0.83

<Measurement of initial hue (YI)>
After drying the PC under nitrogen atmosphere at 120 ° C. for 6 hours, a 3 mm-thick injection molded piece was produced at 360 ° C. using a J-100 injection molding machine manufactured by Nippon Steel, Ltd., and SC- manufactured by Suga Test Instruments Co., Ltd. The YI value was measured by 1 (the larger the YI value, the more colored it is).

[S-PL purification step]
As a result of analyzing s-PL recovered at about 30.2 kg / hr from the above polymerization step, DPC was 5.0% by weight, BPA was 0.5% by weight, oligomer was 0.3% by weight, and water was 0.8%. 3% by weight was detected.
This s-PL was purified continuously in the following two distillation columns. The first PL distillation column was 200 Torr and the reflux ratio was 2, and the contained water was partially distilled off with PL, and the bottoms were supplied to the second PL distillation column. The phenol concentration in the PC low-boiling distillate distilled from the first PL distillation column was about 90% by weight. Next, in the second PL distillation column, purified s-PL was obtained at about 27 kg / hr from the top at 50 Torr and a reflux ratio of 0.5. On the other hand, a PL mixed solution containing 67% by weight, 7% by weight, and 4% by weight of DPC, BPA, and oligomer, respectively, was continuously extracted from the can at about 2.2 kg / hr.

(Experimental Example 1) Production of DPC First, dehydrated s-PL distilled in the second PL distillation column in FIG. 5 was used as a DPC raw material, and the s-PL was dehydrated in the first PL distillation column 30 during dehydration. A method for producing DPC will be specifically described while recycling the PC low-boiling distillate (D6) to be recycled to the DPC washing step.

[DPC reaction process / dehydrochlorination process]
The DPC manufacturing process was performed according to the flow shown in FIG. The DPC reactor 1 was used by connecting two reactors in series.

The purified s-PL 30.0 kg / hr (0.32 kmol / hr) melted at a temperature of 50 ° C. and a pyridine-containing PL obtained by dehydrating a low-boiling substance distilled from a low-boiling distillation column described later as a catalyst, While continuously supplying to the DPC first reactor, the temperature was raised to 150 ° C. While sufficiently stirring, phosgene (CDC) gas 3.56 Nm ^{3 /} hr (0.16 kmol / hr) was continuously supplied to the DPC first reactor. The reaction mixture flowing out from the DPC first reactor was supplied to the DPC second reactor through an overflow pipe in a gas-liquid mixed phase. The DPC second reactor is also adjusted to 150 ° C. with sufficient agitation, and the reaction solution is supplied to the dehydrochlorination tower 2, where the dehydrochlorination tower 2 performs a push-off reaction between the intermediate phenyl chloroformate and PL. To complete, countercurrent contact with nitrogen gas was performed at 160 ° C. From the bottom of the dehydrochlorination tower 2, a dehydrochlorination solution b having about 89% by weight of DPC was continuously withdrawn. Almost 100% of the supplied phosgene was converted to DPC. On the other hand, the exhaust gas at the time of DPC synthesis (D1, the reaction exhaust gas from the DPC second reactor and the nitrogen-containing exhaust gas from the tower 2 such as dehydrochlorination) is mixed and then cooled to 10 ° C., and the condensate is the DPC second reaction. After returning to the vessel, the non-condensed hydrogen chloride was neutralized with an aqueous alkali solution and discharged.

[DPC washing process / DPC washing process]
The obtained dehydrochlorination treatment liquid b and the DPC-containing recovery liquid d recovered from the DPC recovery distillation column 8 to be described later were sent to the mixing tank 3 and then to the alkali neutralization tank 4 made of Teflon lining. And about 5% by weight of sodium hydroxide aqueous solution (25% by weight of sodium hydroxide aqueous solution and the aqueous phase separated after washing in the next step, and PC low boiling point distillate obtained in the above s-PL purification step) Was supplied to the neutralization tank 4 and mixed at 80 ° C. for about 10 minutes, and then adjusted to pH 8.5. The organic phase separated by standing was transferred to the water washing tank 5. On the other hand, the separated aqueous phase (containing PL and sodium chloride) was brought into contact with water vapor, and the contained PL was recovered almost as a low-boiling distillate, and supplied to the water washing tank 5 in the next step. The washing tank 5 is washed with warm water corresponding to about 30% by weight with respect to the organic phase, the aqueous phase (recycled to the neutralization mixing tank described above) is separated, and crude DPC (water, catalyst pyridine, PL is removed). A water-washing treatment liquid f which is contained) was obtained.

[DPC distillation process-low boiling distillation process]
Next, the water washing treatment liquid f was continuously supplied to the middle stage of the first DPC distillation column 6 at a rate of about 42 kg / hr and a 0.1N aqueous sodium hydroxide solution at 70 mL / hr. The first DPC distillation column 6 has an inner diameter of 150 mm, a height of 4.0 m, a reflux device at the top, a raw material supply unit at the center, and sulzer packing (manufactured by Sumitomo Heavy Industries, Ltd.) packed into the concentration unit and the recovery unit. A continuous distillation column having 8 theoretical plates was used. Distilling the mixed gas F containing water, catalyst pyridine and unreacted PL, which are lower boiling point substances than DPC, by distillation under the conditions of a vacuum degree of 20 torr, a heating medium oil temperature of about 220 ° C., a top temperature of 80 to 100 ° C., and a reflux ratio of 1. Removed. A part of the mixed gas F was purged after the dehydration treatment, and the rest was supplied to the DPC first reactor. On the other hand, the first distillation residue g mainly composed of DPC was extracted from the bottom of the column at about 37 kg / hr. The moisture in it was not detected (10 ppm or less), and the contents of pyridine and PL were not detected (1 ppm or less) and 50 ppm, respectively.

[DPC distillation process-high boiling distillation process]
Further, the first distillation residue g was continuously supplied to the second DPC distillation column 7. The second DPC distillation column 7 has an inner diameter of 200 mm, a height of 4.0 m, a reflux device at the top, a raw material supply unit at the center, and sulzer packing (manufactured by Sumitomo Heavy Industries, Ltd.) packed into the concentration unit and the recovery unit. A continuous distillation column having 8 theoretical plates was used. Distilled under conditions of a vacuum of 20 torr, a heating medium oil temperature of about 240 ° C., a top temperature of about 180 ° C., a reflux ratio of 0.5, and a distillation rate of about 90% to obtain purified DPC from the top at about 33.5 kg / hr The DPC distillation residue (X1) having a high boiling point from the bottom of the column was purged at about 4 kg / hr. The purified DPC was a high-purity product containing 80 ppm of PL.

[DPC recovery distillation process]
Further, the DPC distillation residue (X1) purged from the bottom of the high boiling distillation column was simultaneously supplied to the DPC recovery distillation column 8, continuously distilled under the following conditions, and recovered from the top at about 3.5 kg / hr. The DPC-containing recovery liquid d was recycled to the mixing tank 3 described above, and the DPC recovery distillation column 8 as the bottom liquid was continuously purged at about 0.2 kg / hr. The conditions for DPC recovery distillation are an inner diameter of 100 mm, a height of 3.0 m, a reflux device at the top, a raw material supply unit at the center, and Sulzer Packing (manufactured by Sumitomo Heavy Industries, Ltd.) in the concentration unit and recovery unit. A packed continuous distillation column having 8 theoretical plates was used, and the vacuum degree was 20 torr, the heating medium oil temperature was about 240 ° C., the top temperature was 180 ° C., and the reflux ratio was 0.5. Further, in the DPC recovery distillation residue (X1 ′), which is the bottoms of the DPC recovery distillation column 8, about 7000 ppm by weight and 800 ppm by weight of DPC alkyl substitution and bromine substitution were detected, respectively.

(Reference Example 1) Production of DPC DPC was produced in the same manner as in Experimental Example 1 except that a commercially available PL (manufactured by Mitsubishi Chemical Corporation) was used instead of the purified s-PL.

[result]
Even when s-PL was used, the same yield as in the case of commercially available PL was obtained, and it was confirmed that the production efficiency was maintained.

(Comparative Example 1) Production of DPC In the above s-PL purification step, Example 1 was used except that s-PL (water content 0.3 wt%) obtained by bypassing the first PL distillation column was used. A DPC was produced in the same manner. As a result, due to hydrolysis in the DPC reaction step, the DPC concentration in the dehydrochlorination treatment liquid b was reduced to 86% by weight, and a significant reduction in production efficiency was observed.

(Reference Example 2) Production of BPA (BPA production process)
BPA was manufactured according to the flow shown in FIGS. That is, a sulfonic acid-type acidic cation exchange resin (trade name: Dia., Manufactured by Mitsubishi Chemical Corporation) in which 15% of sulfonic acid groups were neutralized with 4-pyridineethanethiol in a flow-through BPA reactor having a temperature controller. Ion SK-104) was filled with 60 L. This BPA reactor was charged with a PL: acetone molar ratio 10: 1 mixture at a temperature of 80 ° C. and a flow rate of 68.2 kg / hr to be reacted. The conversion rate of acetone was 80%. After removing low boiling point substances (unreacted acetone, water, part of PL) at a flow rate of 5.1 kg / h, the reaction mixture was cooled to 50 ° C. to precipitate adduct crystals. This was filtered and separated into adduct crystals and mother liquor. The flow rates were 16.5 kg / h and 46.5 kg / h, respectively. 10 wt% of this mother liquor was supplied to the mother liquor treatment step, and the other mother liquor was circulated as part of the raw material charged into the BPA reactor.

  The adduct crystals obtained here were dissolved again in PL at a flow rate of 27.2 kg / h, and then cooled to 50 ° C. to precipitate crystals, which were filtered to form adduct crystals (11.3 kg / h ) And mother liquor (32.5 kg / h). The separated crystals were heated to 180 ° C. under a reduced pressure of 0.3 mmHg to remove PL, and BPA having a purity of 99.95% or more was obtained at a flow rate of 7.7 kg / h.

  The mother liquor supplied to the mother liquor treatment step was concentrated by distilling a part of PL with the PL evaporator shown in FIG. Next, 0.1 wt% of sodium hydroxide was contained, and the residue was charged into the bottom of the residue reactor 14 controlled at 210 ° C. under a reduced pressure of 50 mmHg. The liquid level at the bottom of the column was operated under a constant condition (residence time 1 hr), and the bottom liquid of the residue reactor 14 was purged outside the system at a flow rate of 0.5 kg / h. Furthermore, the effluent from the top of the residue reactor 14 was mixed with the aforementioned PL, and 4 L of a sulfonic acid type acidic cation exchange resin (manufactured by Mitsubishi Chemical Corporation, trade name: Diaion SK-104) was charged. The flow-through regeneration reactor 15 was charged at a flow rate of 4.2 kg / h and reacted at 80 ° C. The resulting reaction liquid was circulated to the first BPA reactor.

  Low boiling point substances (unreacted acetone, water, part of PL) obtained by separation from the reaction mixture were charged into a PL recovery tower at a flow rate of 5.1 kg / h, and at the same time, ethylbenzene (azeotropic breaker) From the top of the column. Then, a mixture of acetone, water and ethylbenzene was extracted from the top of the PL recovery tower at a flow rate of 2.4 kg / h, and PL was extracted from the bottom of the tower at a flow rate of 3.5 kg / h. Furthermore, the top effluent (acetone, water, ethylbenzene) of the PL recovery tower is charged into the acetone recovery tower, and a mixture of water and ethylbenzene is fed from the bottom of the tower at a flow rate of 0.7 kg / h. Each was extracted at a flow rate of 1.6 kg / h. The PL obtained from the bottom of the PL recovery tower and the acetone obtained from the top of the acetone recovery tower were circulated as part of the raw material charged into the synthesis reactor.

  Furthermore, the above-mentioned synthesis reactor was supplemented with 2.9 kg / h of acetone corresponding to the amount purged out of the system and the amount of BPA obtained, and 15 kg / h of purified PL, and BPA reaction was performed. The BPA was continuously produced as the whole system. The BPA obtained here was charged into the aforementioned PC polymerization step to produce PC.

  The purified PL used above is a commercial industrial PL (water concentration 0.1 wt%, impurity concentration 0.05 wt%, hydroxyacetone concentration 20 ppm) manufactured by Mitsubishi Chemical Corporation at a temperature of 80 ° C. and an adhesion time of 50 minutes: Product name After contact treatment with Diaion SK-104H resin, distilled at a distillation column bottom temperature of 175 ° C. and a column top pressure of 560 mmHg, and obtained from the column top. The hydroxyacetone content in the purified PL was 1 ppm or less.

(Experimental Example 2) Production of BPA Next, the s-PL dehydrated product distilled in the second PL distillation column in FIG. 5 was used as the BPA raw material, and the PC low distilled during the s-PL dehydration was used. A method for producing BPA will be described while returning the boiling portion (D6) to the water separation step of BPA.

  In the above BPA production step (Reference Example 2), the low boiling point product (unreacted acetone, water, part of PL) (5.1 kg / h) obtained by separation from the reaction mixture was added to the s-PL described above. The low-boiling distillate obtained from the top of the first distillation column in the purification step was mixed and charged into the PL recovery column, and at the same time, ethylbenzene (azeotropic breaker) was supplied from the top of the column. Then, a mixture of acetone, water and ethylbenzene was extracted from the top of the PL recovery tower at a flow rate of 2.5 kg / h, and PL was extracted from the bottom of the tower at a flow rate of 4.0 kg / h. Furthermore, the top effluent (acetone, water, ethylbenzene) of the PL recovery tower is charged into the acetone recovery tower, and a mixture of water and ethylbenzene is fed from the bottom of the tower at a flow rate of 0.7 kg / h. Each was extracted at a flow rate of 1.7 kg / h. The PL obtained from the bottom of the PL recovery tower and the acetone obtained from the top of the acetone recovery tower were circulated as part of the raw material charged into the synthesis reactor.

  Furthermore, the above-mentioned BPA reactor is supplied with the amount of acetone purged out of the system and the amount of acetone corresponding to the amount of BPA obtained at 2.9 kg / h as PL, and the second PL distillation column in the above-mentioned PL distillation step as PL. Purified s-PL obtained from the top of the column was replenished at 14.5 kg / h, the synthesis reaction was continuously carried out, and BPA was continuously produced as the entire system. Furthermore, the BPA obtained here was charged into the aforementioned polymerization step to produce PC.

  As a result, by recycling the low-boiling distillate obtained from the top of the first distillation column in the s-PL purification process to the existing process in the BPA production process, almost all of the PL in the low-boiling distillate is obtained. The entire amount was efficiently recovered as a BPA raw material. As a result of manufacturing BPA and PC as described above while carrying out the above operations, there was no problem in the quality of the obtained BPA and PC.

(Comparative example 2) Manufacture of BPA Instead of said refinement | purification s-PL, in said s-PL refinement | purification process, s-PL obtained by bypassing the 1st PL distillation column (water content 0.3 weight%) BPA was produced in the same manner as in Experimental Example 2 except that was used. As a result, a decrease in the yield of BPA was observed. This is presumably because the activity of the ion exchange resin, which is the reaction catalyst, was reduced by the water contained.

(Comparative Example 3) Production of BPA In Reference Example 2, BPA was produced in the same manner as Reference Example 2, except that commercially available PL was used instead of purified PL. As a result, the yield of BPA gradually decreased, and it was confirmed that the activity of the catalyst was reduced by the hydroxyacetone contained.

Next, as the s-PL treatment 2, the treatment of the PC evaporation component in the PC polymerization step will be described using experimental examples.
[DPC production example (1)]
An example of producing DPC from commercially available PL and CDC is shown below.

<Reaction process>
While continuously supplying molten commercial PL and pyridine catalyst to the reactor, phosgene gas was continuously supplied under mixing at 150 ° C. The hydrogen chloride gas produced as a by-product in the phosgenation reaction was cooled to 10 ° C., the condensate was returned to the reactor, and the uncondensed gas was discharged after neutralization with an alkaline aqueous solution. On the other hand, a reaction solution containing about 91% by weight of DPC was continuously extracted from the reactor. The reaction rate of phosgene in the reaction step was almost 100%.

<Washing process>
The reaction solution and about 5% by weight aqueous sodium hydroxide solution were respectively supplied to a neutralization mixing tank made of Teflon lining, mixed at about 80 ° C. for about 10 minutes, and adjusted to pH 8.5. After neutralization, the organic phase after neutralization was transferred to a washing and mixing tank. In the washing and mixing tank, it is washed with warm water corresponding to about 30% by weight with respect to the organic phase, the aqueous phase is separated, and crude DPC (containing 1% by weight of water, 2% by weight of pyridine, 8% by weight of PL, 89% by weight of DPC) Got.

<Low boiling distillation process>
Next, the crude DPC was continuously fed to the middle stage of the low boiling distillation column at about 30 kg / hr. The low boiling distillation column has an inner diameter of 150 mm and a height of 4.0 m, a reflux device at the top, a raw material supply unit at the center, and a sulzer packing (manufactured by Sumitomo Heavy Industries, Ltd.) packed in the concentration unit and the recovery unit. A continuous distillation column having 8 theoretical plates was used. Distilled off water, pyridine, and PL, which are lower boiling point substances than DPC, by distillation under the conditions of a vacuum of 20 torr, a heating medium oil temperature of about 220 ° C., a top temperature of 80 to 100 ° C., a tower middle stage temperature of 160 ° C., and a reflux ratio of 1. did. From the column bottom, DPC (water 10 wt ppm or less, pyridine 1 wt ppm or less, PL 50 wt ppm) was continuously extracted at about 26 kg / hr.

<High boiling distillation process>
Further, this DPC (the bottoms of the low boiling distillation column) was continuously supplied to the high boiling distillation column. The high boiling distillation column has an inner diameter of 200 mm and a height of 4.0 m, a reflux device at the top, a raw material supply unit at the center, and a concentration unit and a recovery unit packed with sulzer packing (manufactured by Sumitomo Heavy Industries, Ltd.) A continuous distillation column having 8 theoretical plates was used. Distillation was carried out under the conditions of a vacuum degree of 20 torr, a heating medium oil temperature of about 240 ° C., a top temperature of about 180 ° C., and a reflux ratio of 0.5. Product (DPC containing about 350 weight ppm and about 40 weight ppm of DPC alkyl and bromine substitutes, respectively) was purged at about 2.5 kg / hr. The purified DPC was a high-purity product containing PL 80 ppm by weight.

[DPC production example (2)]
An example of producing DPC from commercially available PL and dimethyl carbonate will be described below.

<Reaction process>
On the 10th stage from the top of the tray-type distillation column (first reactive distillation column) having an internal diameter of 50 mm and a height of 5 m, the raw material solution containing commercial PL, dimethyl carbonate and tetraphenoxytitanium as a catalyst was 600 g / hr ( Dimethyl carbonate 390 g / hr, PL 200 g / hr, tetraphenoxy titanium 0.5 g / hr). The bottom of the tower was heated with a mantle heater to perform reactive distillation, and a dimethyl carbonate solution containing methanol was extracted from the top of the tower while being distilled at a distillation ratio of 12. The column bottom liquid containing methylphenyl carbonate and a small amount of DPC is extracted from the column bottom, and 10 stages from the top of the tray-type distillation column (second reactive distillation column) having an inner diameter of 80 mm and a height of 4 m and 50 actual plates. Feeded my eyes. In the second reactive distillation column, a liquid containing DPC and methylphenyl carbonate generated by further progress of the reaction was extracted from the bottom of the column. And most unreacted dimethyl carbonate and a part of unreacted PL were distilled off from the top of the second reactive distillation column and recycled to the first reactive distillation column.

<Recycling process>
A solution of dimethyl carbonate containing methanol distilled from the first reactive distillation column is fed into the middle of an distillation column (azeotropic distillation column) with an inner diameter of 32 mm and a height of 2.5 m and a real number of 30 plates, Distilled at 5. A mixed solution of methanol and dimethyl carbonate having a nearly azeotropic composition was extracted from the top of the column and then fed to an extractive distillation column. In the extractive distillation column, methanol and dimethyl carbonate were separated, methanol was purged out of the system, and dimethyl carbonate was recycled to the first reactive distillation column. The bottom liquid of the azeotropic distillation column was dimethyl carbonate containing a small amount of PL, which was circulated to the first reactive distillation column.

<Purification process>
The high boiling point reaction mixture containing the catalyst and DPC continuously withdrawn from the bottom of the second reactive distillation column was introduced into an evaporator, where the evaporated condensate containing the catalyst was purged. On the other hand, the evaporated product containing a large amount of DPC formed by the evaporator was supplied to the diphenyl carbonate purification tower. The top pressure of the purification tower is controlled to 20 Torr, the bottom temperature is controlled to 190 ° C., a low boiling point mixture containing phenol and methylphenyl carbonate is distilled from the top of the tower, a part is refluxed, and the rest is the second reactive distillation described above. Recycled to the tower. On the other hand, high boiling impurities were purged from the bottom of the diphenyl carbonate purification tower, and DPC was obtained from the middle stage of the tower.

  The operation as described above was performed continuously until each step reached a steady state. Sampling in a steady state and analysis by high performance liquid chromatography revealed that 300 ppm by weight of methylphenyl carbonate was detected in the obtained diphenyl carbonate. Further, the yield of DPC was about 95% on the basis of PL.

[Production example of BPA]
An example of producing BPA from commercially available PL and acetone will be described below.
A sulfonic acid-type acidic cation exchange resin (trade name Diaion SK, manufactured by Mitsubishi Chemical Corporation), in which 15% of sulfonic acid groups were neutralized with 4-pyridineethanethiol in a flow-through synthesis reactor having a temperature controller. -104) was charged at 60 L. Into this synthesis reactor, a mixed solution having a PL: acetone molar ratio of 10: 1 was charged at a temperature of 80 ° C. and a flow rate of 68.2 kg / hr to be reacted. The conversion rate of acetone was 80%. The reaction mixture was purged with low boiling point substances (unreacted acetone, water, part of PL) at a flow rate of 5.1 kg / h, and then cooled to 50 ° C. to precipitate adduct crystals. This was filtered and separated into adduct crystals and mother liquor. The flow rates were 16.5 kg / h and 46.5 kg / h, respectively. 10 wt% of this mother liquor was supplied to the mother liquor treatment step, and the other mother liquor was circulated as part of the raw material charged into the synthesis reactor.

  The adduct crystals obtained here were dissolved again in PL at a flow rate of 27.2 kg / h, and then cooled to 50 ° C. to precipitate crystals, which were filtered to form adduct crystals (11.3 kg / h ) And mother liquor (32.5 kg / h). The separated crystals were heated to 180 ° C. under a reduced pressure of 0.3 mmHg to remove PL, and BPA having a purity of 99.95% or more was obtained at a flow rate of 7.7 kg / h.

  On the other hand, the mother liquor supplied to the mother liquor treatment step was concentrated by distilling a part of PL. Next, 0.1% by weight of sodium hydroxide was contained, and charged to the bottom of a cracking distillation column controlled at 210 ° C. under a reduced pressure of 50 mmHg. The liquid level at the bottom of the column was operated under a constant condition (residence time: 1 hr), and the bottom liquid of the cracking distillation column was purged outside the system at a flow rate of 0.5 kg / h. Furthermore, the effluent from the top of the cracking distillation column was mixed with the above-mentioned PL, and 4 L of sulfonic acid type acidic cation exchange resin (trade name, Diaion SK-104, manufactured by Mitsubishi Chemical Corporation) was packed. The reactor was charged at a flow rate of 4.2 kg / h and reacted at 80 ° C. The resulting reaction liquid was circulated to the first synthesis reactor.

  The above-mentioned synthesis reactor is supplemented with commercial PL (18.5 kg / h) and acetone (3.6 kg / h) in amounts corresponding to the amount purged out of the system and the amount of bisphenol A obtained, The synthesis reaction was carried out continuously, and BPA was continuously produced as the whole system.

[Example of PC production (1)]
An example in which a PC is manufactured in the process shown in FIG. 6 from the DPC obtained in the DPC production example (1) and the BPA obtained from the BPA production example will be described below.

<PC polymerization process>
The DPC and BPA were melt-mixed in a mixing tank 21 in a nitrogen gas atmosphere at a 0.977 weight ratio, and continuously supplied into a first vertical stirring polymerization tank 22 controlled at 210 ° C. and 100 Torr in a nitrogen atmosphere, The liquid level was kept constant while controlling the valve opening degree provided in the polymer discharge line at the bottom of the tank so that the average residence time was 60 minutes. At the same time as the supply of the raw material mixture was started, cesium carbonate as an aqueous solution as a catalyst was continuously supplied at a flow rate of 0.5 × 10 ⁻⁶ mol to 1 mol of BPA. The polymerization liquid discharged from the tank bottom was continuously continuously supplied to the second and third vertical polymerization tanks 23 and 24 and the fourth horizontal polymerization vessel 25. During the reaction, the liquid level was controlled so that the average residence time in each tank was 60 minutes, and at the same time, PL produced as a by-product was distilled off. The gas evaporating from the first and second polymerization tanks 22 and 23 is condensed and liquefied by the recirculation devices 33a and 33b and the multistage condensers 26 and 27, respectively, and a part is refluxed to each polymerization tank, and the rest is recovered for the first PC. It collected in PL tank 29a. On the other hand, the gas evaporating from the third polymerization tank 24 is solidified by one of the two freeze condensers in parallel, the solidified part is melted by switching operation with the other freeze condenser, and collected in the second PC recovery PL tank 29b. It was. At that time, all the PC evaporation components distilled from the first and second polymerization tanks 22 and 23 are all in the first PC recovery PL tank 29a, and the PC evaporation component distilled from the third polymerization tank 24 is the second PC. Each was stored in a recovery PL tank 29b.

  The polymerization conditions of each polymerization tank were as follows: first polymerization tank 22 (210 ° C., 100 Torr), second polymerization tank 23 (240 ° C., 15 Torr), third polymerization tank 24 (260 ° C., 0.5 Torr), fourth polymerization vessel 25 (280 ° C., 0.5 Torr).

  The polymer obtained above was introduced in a molten state into a twin-screw extruder (manufactured by Kobe Steel, Ltd., screw diameter 0.046 m, L / D = 40.2), and p equivalent to 5 ppm by weight per polycarbonate. -Pelletized with continuous addition of butyl toluenesulfonate. The PC thus obtained had an Mv of 21,000 and an initial YI of 1.7. In addition, the measuring method of molecular weight (Mv) and initial hue (YI) is as above-mentioned.

<PC evaporation component>
As a result of measuring the amount and composition of each PC evaporation component recovered from the polymerization step, it was as follows.
・ First PC recovery PL tank 29a
The amount of phenol in the recovered first PC evaporation component p1 was about 60% with respect to the total amount of PL distilled in the PC polymerization step. In addition to PL, DPC was detected at 1.1% by weight, and BPA and oligomer components were not detected.
・ Second PC recovery PL tank 29b
The amount of phenol in the recovered second PC evaporation component p2 is about 40% with respect to the total amount of PL distilled in the polymerization step, and 6.0% by weight of DPC is detected in addition to PL, and BPA and oligomer components Were detected at 1.2 wt% and 0.3 wt%, respectively.

[Production example of PC (2)]
An example of producing PC from the DPC obtained in Production Example (2) of DPC and BPA obtained from the Production Example of BPA will be described below.

<PC polymerization process>
The same operation as in PC Production Example (1) was carried out except that the DPC obtained in DPC Production Example (2) was used as the DPC. The obtained PC had Mv = 21,000 and initial YI = 1.7, and was of the same quality as that of the aromatic polycarbonate production example (1).

<PC evaporation component>
As a result of measuring the amount and composition of each PC evaporation component recovered from the polymerization step, it was as follows.
・ First PC recovery PL tank 29a
The amount of phenol in the recovered first PC evaporation component p1 was about 60% with respect to the total amount of PL distilled in the PC polymerization step. In addition to PL, 1.1% by weight of DPC and 95 ppm by weight of methanol were detected, and BPA and oligomer components were not detected.
・ Second PC recovery PL tank 29b
The amount of phenol in the recovered second PC evaporation component p2 is about 40% with respect to the total amount of PL distilled in the polymerization step, and 6.0% by weight of DPC is detected in addition to PL, and BPA and oligomer components Were detected at 1.2 wt% and 0.3 wt%, respectively. Methanol was not detected (5 ppm by weight or less).

(Experimental example 1)
DPC and BPA were manufactured using the PC evaporation component containing by-product phenol obtained in the above PC production example (1).
<Manufacturing DPC>
Except for changing the amount corresponding to 60% of the commercial PL used in the above-mentioned DPC production example (1) to the first PC evaporation component p1 recovered in the above-mentioned PC production example (1), The same operation as in Production Example (1) was performed to produce DPC. As a result, the phosgene reaction rate in the reaction process and the quality of the obtained DPC were not changed.

<Manufacture of BPA>
In the above-mentioned BPA production example, the amount corresponding to 40% of the commercial PL continuously supplied to the synthesis reactor was changed to the second PC evaporation component p2 recovered in the PC production example (1). Performed the same operation as in the BPA production example described above to produce BPA. As a result, there was no problem in the conversion rate of acetone and the quality of bisphenol A.

(Experimental example 2)
DPC and BPA were manufactured using the PC evaporation component containing by-product phenol obtained in the above PC production example (2).
<Manufacturing DPC>
Except that the amount corresponding to 60% of the commercial PL used in the above-mentioned DPC production example (2) was changed to the first PC evaporation component p1 recovered in the above-mentioned PC production example (2), the DPC The same operation as in Production Example (2) was performed to produce DPC. As a result, it was possible to obtain DPC of equivalent quality, and it was confirmed that there was no problem even if methanol derived from methylphenyl carbonate was mixed.

<Manufacture of BPA>
In the BPA production example described above, the amount corresponding to 40% of the commercial PL continuously supplied to the synthesis reactor was changed to the second PC evaporation component p2 recovered in the PC production example (2). Performed the same operation as in the BPA production example described above to produce BPA. As a result, there was no problem in the conversion rate of acetone and the quality of BPA. Further, the methanol concentration in the reaction raw material was not detected.

(Comparative Example 1)
DPC was manufactured using the 2nd PC evaporation component p2 collect | recovered in the manufacture example (1) of the said PC.
<Manufacturing DPC>
Except for changing all the commercially available PL used in the above-mentioned DPC production example (1) to the second PC evaporation component p2 recovered in the above-mentioned PC production example (1), the above-mentioned DPC production example (1) The same operation was performed to produce DPC. As a result, the reaction solution was blocked in the pipe for transferring to the cleaning process, and the operation could not be continued.

(Comparative Example 2)
BPA was manufactured using the 1st PC evaporation component p1 collect | recovered in the manufacture example (2) of the said PC.
<Manufacture of BPA>
In the BPA production example described above, all of the commercially available PL continuously supplied to the synthesis reactor was changed to the first PC evaporation component p1 (containing 95 ppm by weight of methanol) recovered in the PC production example (2). Except for the above, BPA was continuously produced according to the above-mentioned BPA production examples. As a result, it is considered that the conversion rate of acetone was significantly reduced to 55.0%, and the catalyst performance was lowered by the contained methanol. Moreover, the methanol concentration in the raw material phenol during the synthesis reaction was diluted with the circulating mother liquor and was about 30 ppm by weight.

Next, as the s-PL treatment 3, the usage classification according to the PC evaporation component p and commercially available PL impurities will be described using experimental examples.
(Experimental example 1)
(Manufacturing of DPC)
[Reaction process]
While continuously supplying molten commercial PL (manufactured by Mitsubishi Chemical Corporation, cresol content: 45 ppm by weight, hydroxyacetone content: 27 ppm by weight, hereinafter referred to as “PL1”) and a pyridine catalyst to the reactor, While mixing at 150 ° C., phosgene gas was continuously supplied. The hydrogen chloride gas produced as a by-product in the phosgenation reaction was cooled to 10 ° C., the condensate was returned to the reactor, and the uncondensed gas was discharged after neutralization with an alkaline aqueous solution. On the other hand, a reaction solution containing about 91% by weight of DPC was continuously extracted from the reactor.

[Washing process]
The reaction solution and about 5 wt% sodium hydroxide aqueous solution were respectively supplied to a neutralization mixing tank made of Teflon lining and mixed at 80 ° C. for about 10 minutes to adjust the pH to 8.5. After neutralization, the organic phase after neutralization was transferred to a washing and mixing tank. In the washing and mixing tank, it is washed with warm water corresponding to about 30% by weight with respect to the organic phase, the aqueous phase is separated, and crude DPC (containing 1% by weight of water, 2% by weight of pyridine, 8% by weight of PL, 89% by weight of DPC) Got.

[Low boiling distillation process]
Next, the crude DPC was continuously fed to the middle stage of the low boiling distillation column at about 30 kg / hr. The low-boiling distillation column has an inner diameter of 150 mm, a height of 4.0 m, a reflux device at the top, a raw material supply unit at the center, and a concentration unit and a recovery unit packed with sulzer packing (manufactured by Sumitomo Heavy Industries), 8 theoretical plates A continuous distillation column was used. Distilled off water, pyridine, and PL, which are lower boiling point substances than DPC, by distillation under the conditions of a vacuum of 20 torr, a heating medium oil temperature of about 220 ° C., a top temperature of 80 to 100 ° C., a tower middle stage temperature of 160 ° C., and a reflux ratio of 1. did. From the column bottom, DPC (water 10 wt ppm or less, pyridine 1 wt ppm or less, PL 50 wt ppm) was continuously extracted at about 26 kg / hr.

[High boiling distillation process]
Further, this DPC (the bottoms of the low boiling distillation column) was continuously supplied to the high boiling distillation column. The high boiling distillation column has an inner diameter of 200 mm, a height of 4.0 m, a reflux device in the upper part, a raw material supply part in the center, and packed with sulzer packing (manufactured by Sumitomo Heavy Industries) in the concentration part and the recovery part. A continuous distillation column was used. Distilled under the conditions of a vacuum of 20 torr, a heating medium oil temperature of about 240 ° C., a top temperature of about 180 ° C. and a reflux ratio of 0.5, and purified DPC (containing 80 ppm by weight of PL) was obtained from the top at about 23.5 kg / hr It was.

(Reference Example 1)
Instead of the above-mentioned commercially available PL (PL1), a by-product phenol (cresol content: 5 ppm by weight, hydroxy) obtained by distillation-purifying the PC evaporation component p obtained from a PC manufacturing plant at Mitsubishi Chemical Corporation under the following conditions: A DPC was produced in the same manner as in Experimental Example 1, except that the acetone content was 1 ppm by weight or less, hereinafter referred to as “PL2”.
[Distillation purification conditions]
In the first distillation column, the contained water was partially distilled off with PL at 200 Torr and a reflux ratio of 2, and the bottoms were continuously supplied to the second distillation column. In the second distillation column, by-product phenol purified from the top was obtained at 50 Torr and a reflux ratio of 0.5, and from the bottom, a high-boiling component DPC, BPA, and a PL mixture containing oligomers were continuously added. Purged.
〔result〕
Even if it used for DPC manufacture, without refine | purifying commercially available pL, high-purity DPC which does not produce discoloration etc. with high purity was obtained similarly to the case where the by-product phenol refined by distillation was used.

(Experimental Example 2, Comparative Example 1) Production of BPA A sulfonic acid type cation exchange resin (styrene-divinylbenzene crosslinked copolymer) in which 15% by weight of sulfonic acid groups were modified with 4- (2-mercaptoethyl) pyridine. A sulfonated product (Diaion SK104H, manufactured by Mitsubishi Chemical Co., Ltd.) is charged into a reactor, and a raw material fluid (PL: acetone) composed of the above PL (PL2 or PL1) and acetone (manufactured by Mitsubishi Chemical Co., Ltd.) is filled therein. = 13: 1 (molar ratio)) was continuously circulated with LHSV = 5 hr ^{−1 on the} basis of a phenol wet catalyst, and a BPA production reaction was performed at a reaction temperature of 70 ° C. for 1008 hours. Table 1 shows the reaction rate of acetone immediately after the start of the reaction, the acetone reaction rate after 1008 hours, and the selectivity of BPA. The ratio of the acetone reaction rate after 1008 hours to the acetone reaction rate after 120 hours from the start of the reaction was calculated as the activity maintenance rate. The results are also shown in Table 1.

The reaction rate (%) and the catalyst activity retention rate (%) were calculated from the following formulas.
Reaction rate (%) = {(amount of supplied acetone−amount of unreacted acetone) / amount of supplied acetone} × 100
Activity maintenance rate (%) = (acetone conversion rate after 1008 hours) / (acetone conversion rate after 120 hours) × 100

[result]
When PL obtained by distillation purification of PL distilled in the polymerization step was used, unlike the case of using commercially available PL, both the reaction rate and the catalyst activity retention rate were high.

  Moreover, when using what distilled and refine | purified PL distilled in the superposition | polymerization process, the color tone of BPA obtained was white, but when using commercially available PL, it was yellowing a little. Assuming that PC was produced using these, when BPA was produced using distilled and purified PL distilled in the polymerization step, white high-purity PC would be obtained. When BPA is produced by using it, it is expected that the obtained PC is slightly yellowed and the purity is also lowered.

Next, the cooperation between the manufacturing processes will be described more specifically with reference to the flow shown in FIG. Note that, unlike FIG. 7, the BPA storage step was provided between the heating and melting step (step (d)) and the PL removal step (step (e)).
(Experimental example 1)
[Manufacture of BPA]
A sulfonic acid type acidic cation exchange resin (product name: Diaion SK manufactured by Mitsubishi Kasei Co., Ltd.), in which 15% of sulfonic acid groups were neutralized with 4-pyridineethanethiol in a flow-through BPA reactor having a temperature controller. -104) was charged at 60 L. This synthetic reactor was charged with a mixture of PL: acetone (A) at a molar ratio of 10: 1 at a temperature of 80 ° C. and a flow rate of 68.2 kg / hr to be reacted. The conversion rate of acetone (A) was 80%. The reaction mixture was purged with low boiling point substances (unreacted acetone, water, part of PL) at a flow rate of 5.1 kg / h, and then cooled to 50 ° C. to precipitate adduct crystals. This was filtered and separated into adduct crystals and mother liquor. The flow rates were 16.5 kg / h and 46.5 kg / h, respectively. 10 wt% of this mother liquor was supplied to the mother liquor treatment step, and the other mother liquor was circulated as part of the raw material charged into the synthesis reactor.

  The adduct crystals obtained here were dissolved again in phenol at a flow rate of 27.2 kg / h, cooled to 50 ° C. to precipitate crystals, and filtered to form adduct crystals (11.3 kg / h ) And mother liquor (32.5 kg / h). The separated crystals are mixed with purified PL 1.5 kg / hr, and a 60:40 wt% mixture of BPA and PL is stocked in a BPA storage tank (under the following conditions) at 12.8 kg / hr. The PL removal process was continuously supplied at 12.0 kg / hr.

  The BPA storage tank is made of SUS304 and has a capacity of 150 L (Vb / Fb = 22 described in the specification), the system is sealed with nitrogen, and the internal temperature of the mixture of BPA and PL is 120 ° C. Adjusted. Further, in the above mixture of BPA and PL, about 10 wt. Ppb of PL sulfonic acid which was considered to have eluted from the ion exchange resin was detected, so that the acidic substance was completely neutralized before being transferred to the storage tank. Accordingly, an aqueous solution of caustic soda corresponding to neutralization was added and neutralized, and then supplied to the storage tank. The liquid level in the storage tank has gradually increased slightly since the start of operation.

  Next, the mixture of BPA and PL in the BPA storage tank is continuously transferred to the PL removal step at 12.0 kg / hr, and heated to 180 ° C. under a reduced pressure of 0.3 mmHg to remove PL. BPA with a purity of 99.95% or more was obtained at a flow rate of 7.2 kg / hr (6.8 L / hr). The obtained BPA was continuously supplied to an aromatic polycarbonate production process described later.

  On the other hand, the mother liquor supplied to the mother liquor treatment step (not shown in FIG. 7; see FIG. 4) was concentrated by distilling a part of PL with the PL evaporator 13. Next, 0.1 wt% of sodium hydroxide was contained, and the residue was charged into the bottom of the residue reactor 14 controlled at 210 ° C. under a reduced pressure of 50 mmHg. The liquid level at the bottom of the column was operated under constant conditions (residence time: 1 hr), and the bottom liquid of the residue reactor 14 was purged outside the system at a flow rate of 0.5 kg / h. Furthermore, the effluent from the top of the residue reactor 14 was mixed with the aforementioned PL, and 4 L of sulfonic acid type acidic cation exchange resin (manufactured by Mitsubishi Chemical Corporation: trade name Diaion SK-104) was charged. The flow-through regeneration reactor 15 was charged at a flow rate of 4.2 kg / h and reacted at 80 ° C. The resulting reaction liquid was circulated to the first BPA reactor.

  The aforementioned BPA reactor was replenished with commercially purged amounts (18.5 kg / h) and acetone (3.6 kg / h) corresponding to the amount purged out of the system and the amount of BPA obtained. The synthesis reaction was carried out continuously, and BPA was continuously produced as the whole system.

[Manufacture of PC]
A manufacturing example of the PC will be described below in accordance with the flow shown in FIG.
The BPA and DPC supplied continuously are melt-mixed in a mixing tank 21 at a 1.024 weight ratio in a nitrogen gas atmosphere, and controlled in a nitrogen atmosphere at 210 ° C. and 100 Torr. The liquid level was kept constant while controlling the valve opening degree provided in the polymer discharge line at the bottom of the tank so that the average residence time was 60 minutes. At the same time as the supply of the raw material mixture was started, cesium carbonate as an aqueous solution as a catalyst was continuously supplied at a flow rate of 0.5 × 10 ⁻⁶ mol to 1 mol of BPA. The polymerization solution discharged from the bottom of the tank was successively continuously supplied to the second and third vertical polymerization tanks 23 and 24 and the fourth horizontal polymerization tank 25. During the reaction, the liquid level was controlled so that the average residence time in each tank was 60 minutes, and at the same time, PL produced as a by-product was distilled off. The PC evaporation component p evaporating from the first and second polymerization tanks was condensed and liquefied by a multistage condenser, a part of which was refluxed to each polymerization tank, and the rest was collected in the PC PL tank 29. On the other hand, the gas evaporating from the third and fourth polymerization tanks 24 and 25 is solidified by one of the two freeze condensers in parallel, and the solidified part is melted by switching operation with the other freeze condenser. 29 (not shown).

  The polymerization conditions in each reaction tank were as follows: first polymerization tank (210 ° C., 100 Torr), second polymerization tank (240 ° C., 15 Torr), third polymerization tank (260 ° C., 0.5 Torr), fourth polymerization tank (280 ° C. 0.5 Torr).

  The polymer obtained above was pelletized while continuously adding butyl p-toluenesulfonate equivalent to 5 ppm by weight per PC in the molten state. The polycarbonate thus obtained had an Mv of 21,000 and an initial YI of 1.8.

<Measurement of molecular weight (Mv)>
Using a methylene chloride solution with a PC concentration (C) of 0.6 g / dl, the molecular weight (Mv) was calculated from the specific viscosity (ηsp) measured at a temperature of 20 ° C. with an Ubbelohde viscometer using the following two equations. Calculated.
ηsp / C = [η] (1 + 0.28 ηsp)
[Η] = 1.23 × 10 ⁻⁴ (Mv) ^0.83

<Measurement of initial hue (YI)>
After drying the PC at 120 ° C. for 6 hours in a nitrogen atmosphere, a 3 mm-thick injection molded piece was produced at 360 ° C. with a J-100 injection molding machine, and the Suga test machine ( Manufactured by Co., Ltd .: The YI value was measured by SC-1 (the larger the YI value, the more colored it is).

  After the above operation was continued for 1 week, the synthesis reaction / crystallization process was temporarily stopped for about 8 hours for the purpose of washing the BPA crystallizer. However, in the meantime, the post-process was continuously operated using the mixed solution stocked in the storage tank, and BPA and aromatic polycarbonate could be produced. In addition, the obtained quality was not different from the initial quality at the time of continuous operation for one week and the operation of only the subsequent process thereafter.

(Experimental example 2)
Except for changing the capacity of the BPA storage tank at the time of BPA production in Experimental Example 1 to 2 m ³ (Vb / Fb = 294), the same operation as in Experimental Example 1 above was performed, and BPA and aromatic polycarbonate were continuously added. Manufactured. Mv of the obtained aromatic polycarbonate was 21,000, and initial YI was 1.8.
Moreover, although the said operation was continued for 2 months, the hue (initial YI) of the aromatic polycarbonate showed 1.8-1.9, and the favorable product was able to be obtained. Furthermore, after that, the BPA synthesis reaction and crystallization process was temporarily stopped for about 3 days, but the subsequent process can be operated continuously using the mixed solution stocked in the storage tank. There was no problem with the product quality. After that, as described above, the BPA pre-process (up to the process before the BPA storage tank) is intermittently stopped for 3 days every two months, and from the post-process of the BPA to the production of the aromatic polycarbonate. With continuous operation, good quality aromatic polycarbonate was continuously obtained for about half a year.

(Comparative Example 1)
Except for changing the capacity of the BPA storage tank at the time of BPA production in Experimental Example 1 to 50 L (Vb / Fb = 7), the same operation as in Experimental Example 1 was performed, and BPA and aromatic polycarbonate were continuously added. Manufactured. Mv of the obtained aromatic polycarbonate was 21,000, and initial YI was 1.8.

  However, after two days have passed since the above operation was started, the BPA storage tank is full, and the production speed of the pre-process for bis-PL production (up to the process before the storage tank) is reduced. Was adjusted to be constant. Thereafter, when only the previous process was stopped, the liquid level in the storage tank was lowered as soon as it was seen, and it was emptied after about 4 hours, and all processes of the post process and the PC process had to be stopped.

(Comparative Example 2)
In Comparative Example 1, BPA was continuously produced and obtained while adjusting the production rate of the BPA pre-process (up to the process before the storage tank) so that the liquid level of the storage tank was constant. After cooling, the BPA was granulated and stored once in a newly provided BPA powder hopper (capacity: 1 m ³ ). Then, PC was continuously manufactured as mentioned above, supplying and dissolving to a DPC solution using a powder measurement feeder. While the BPA was present in the powder hopper, there was no problem in the PC production speed even if the BPA process was temporarily stopped, but in this method, the melted BPA is made into powder. Therefore, it is necessary to cool once and then heat for melting, which is disadvantageous in terms of thermal efficiency. In addition, dust was generated during the supply of BPA, causing a problem that the gas line was blocked.

(Comparative Example 3)
In Comparative Example 1, the production rate after the storage tank was slightly increased so that the liquid level of the storage tank was constant, and BPA was continuously produced at 7.7 kg / hr. The obtained BPA alone was stored in a newly provided tank with a capacity of 2 m ³ and the internal temperature was controlled at 160 ° C., and then supplied as a raw material for producing PC at 7.2 kg / hr as in Comparative Example 1. did. Although the initial YI of the obtained PC was 1.8, as the operation was continued, the hue clearly started to deteriorate, and the quality deteriorated greatly when the BPA alone was melted and held.

(Experimental example 3)
Next, an experimental example in which the BPA manufacturing process, the DPC manufacturing process, and the PC manufacturing process are linked and a BPA, DPC, and PC storage process are provided in each manufacturing process will be described below.
[Manufacture of BPA]
It implemented similarly to the said Experimental example 1.

[Manufacturing DPC]
<Reaction process>
While continuously supplying pyridine-containing phenol obtained by dehydrating a low-boiling substance distilled from a low-boiling distillation column described later as a catalyst to 6.4 kg / hr of molten phenol at a temperature of 50 ° C. to 150 ° C. The temperature rose. While sufficiently stirring, 0.75 Nm ³ / hr of phosgene gas was continuously supplied to the first reactor. The reaction mixture flowing out from the first reactor was supplied to the second reactor through an overflow pipe in a gas-liquid mixed phase. The second reactor is also adjusted to 150 ° C. with sufficient agitation, and the reaction solution is supplied to the degassing tower. In the degassing tower, the intermediate reaction between phenylchloroformate and phenol is completed. Countercurrent contact with nitrogen gas was performed at 160 ° C. From the bottom of the degassing tower, a reaction solution containing about 89% by weight of diphenyl carbonate was continuously extracted. Nearly 100% of the supplied phosgene was converted to diphenyl carbonate. On the other hand, the exhaust gas during synthesis of diphenyl carbonate (the reaction exhaust gas from the second reactor and the nitrogen-containing exhaust gas from the degassing tower) is mixed and then cooled to 10 ° C., and the condensate is returned to the second reactor. Uncondensed hydrogen chloride was neutralized with an aqueous alkali solution and discharged.

<Washing process>
The obtained reaction liquid, diphenyl carbonate recovered from a recovery distillation column, which will be described later, and an aqueous solution of about 5% by weight sodium hydroxide (25% by weight sodium hydroxide aqueous solution and an aqueous phase separated after washing in the next step) Were mixed in a neutralization mixing tank made of Teflon lining and mixed at 80 ° C. for about 10 minutes to adjust the pH to 8.5. After neutralization, the organic phase after neutralization was transferred to a washing and mixing tank. On the other hand, the separated aqueous phase (containing phenol and sodium chloride) was brought into contact with water vapor to recover almost all of the phenol contained as phenol-containing water and supplied to the washing and mixing tank in the next step. In the washing and mixing tank, it is washed with warm water corresponding to about 30% by weight with respect to the organic phase, the aqueous phase (recycled to the neutralization mixing tank described above) is separated, and crude diphenyl carbonate (water, catalyst pyridine, phenol) Containing).

<Low boiling distillation process>
Next, the crude diphenyl carbonate was continuously supplied to the middle stage of the low boiling distillation column at about 9 kg / hr and 0.1 N aqueous sodium hydroxide solution at 15 mL / hr. The low-boiling distillation column has an inner diameter of 100 mm and a height of 4.0 m, has a reflux device at the top, a raw material supply unit at the center, and is packed with sulzer packing (manufactured by Sumitomo Heavy Industries, Ltd.) in the concentration unit and recovery unit. A staged continuous distillation column was used. Distillation and removal of water, catalyst pyridine and unreacted phenol, which are substances having a lower boiling point than diphenyl carbonate, were performed by distillation under conditions of a degree of vacuum of 20 torr, a heating medium oil temperature of about 220 ° C., a top temperature of 80 to 100 ° C., and a reflux ratio of 1. A part of the low boiling point substance was purged after the dehydration treatment, and the rest was fed to the first phosgenation first reactor. On the other hand, diphenyl carbonate is extracted from the bottom of the column at about 7.8 kg / hr, the moisture in it is undetected (10 ppm or less), and the contents of pyridine and phenol are undetected (1 ppm or less) and 50 ppm, respectively. there were.

<High boiling distillation process>
Furthermore, this diphenyl carbonate (the bottoms of the low boiling distillation column) was continuously supplied to the high boiling distillation column. The high boiling distillation column has an inner diameter of 100 mm and a height of 4.0 m, has a reflux apparatus at the top, a raw material supply unit at the center, and is packed with sulzer packing (manufactured by Sumitomo Heavy Industries, Ltd.) in the concentration unit and recovery unit. A staged continuous distillation column was used. Distilled under the conditions of a vacuum of 20 torr, a heat transfer oil temperature of about 240 ° C., a top temperature of about 180 ° C., a reflux ratio of 0.5, and a distillation rate of about 90%, purified diphenyl carbonate was about 7.1 kg / hr from the top ( 7 L / hr), and high boilers were purged from the bottom of the column at about 0.8 kg / hr. Purified diphenyl carbonate is a high-purity product containing 80 ppm of phenol, and is stored in a 200 L tank made of SUS316 (Vd / Fd = 29 described in the specification) at a constant amount (about 100 L) at 100 ° C. Thereafter, it was supplied as a PC polymerization raw material at 7 L / hr.

<Recovery distillation process>
Further, the bottoms of the high-boiling distillation column purged from the bottoms are simultaneously supplied to the recovery distillation column and continuously distilled under the following conditions. The diphenyl carbonate recovered at about 0.7 kg / hr from the top is described above. Recycled to a neutralization mixing tank, the bottoms were continuously purged at about 0.04 kg / hr. The conditions for diphenyl carbonate recovery distillation were an inner diameter of 50 mm, a height of 3.0 m, a reflux device at the top, a raw material supply unit at the center, and a sulzer packing (manufactured by Sumitomo Heavy Industries, Ltd.) in the concentration unit and recovery unit. Using a continuous distillation column having 8 theoretical plates, the degree of vacuum was 20 torr, the heat medium oil temperature was about 240 ° C., the top temperature was 180 ° C., and the reflux ratio was 0.5. Moreover, about 7000 weight ppm and about 800 weight ppm of the alkyl substitution product and bromine substitution product of diphenyl carbonate were detected in the bottoms of the recovery distillation column, respectively.

[Manufacture of PC]
<Polymerization process>
Under a nitrogen gas atmosphere at 130 ° C., normal pressure is obtained through a raw material introduction pipe heated and mixed at 130 ° C. by melting and mixing bisphenol A obtained above at 7.2 kg / hr and diphenyl carbonate at 7.1 kg / hr. In a nitrogen atmosphere, while continuously feeding into the first vertical stirring polymerization tank controlled at 210 ° C., while controlling the valve opening degree provided in the polymer discharge line at the bottom of the tank so that the average residence time is 60 minutes The liquid level was kept constant. At the same time as the supply of the raw material mixture was started, cesium carbonate in an aqueous solution as a catalyst was continuously supplied at a flow rate of 0.5 × 10 ⁻⁶ mol to 1 mol of bisphenol A. The polymerization liquid discharged from the tank bottom was continuously continuously supplied to the second, third and fourth vertical polymerization tanks and the fifth horizontal polymerization tank. During the reaction, the liquid level was controlled so that the average residence time in each tank was 60 minutes, and at the same time, the by-produced phenol was distilled off. The gas evaporating from the first to third polymerization tanks was condensed and liquefied by a multistage condenser, a part was refluxed to each polymerization tank, and the rest was collected in a byproduct phenol tank. On the other hand, the gas evaporating from the 4th to 5th polymerization tanks is solidified by one of the two freeze condensers in parallel, and the solidified part is melted by switching operation with the other freeze condenser, It was recovered.

  The polymerization conditions for each reaction tank were as follows: second polymerization tank (210 ° C., 100 Torr), third polymerization tank (240 ° C., 15 Torr), fourth polymerization tank (260 ° C., 0.5 Torr), fifth polymerization tank (270 ° C.). 0.5 Torr). The polycarbonate was produced at a production rate of 8.0 kg / hr.

  Next, this polymer was introduced into a twin-screw extruder (manufactured by Kobe Steel, Ltd.) in a molten state, and 5 ppm equivalent of butyl p-toluenesulfonate per polycarbonate was continuously added. The butyl p-toluenesulfonate was dispersed in flaky polycarbonate using a mixer to prepare a master batch, and was fed into the extruder under nitrogen using a weight feeder and pelletized. The polycarbonate thus obtained had an Mv of 21,000 and an initial YI of 1.7.

-Molecular weight (Mv):
It is a value calculated using the following both equations from the specific viscosity (ηsp) measured at a temperature of 20 ° C. with an Ubbelohde viscometer using a methylene chloride solution having a polycarbonate concentration (C) of 0.6 g / dl. .
ηsp / C = [η] (1 + 0.28 ηsp)
[Η] = 1.23 × 10 ⁻⁴ × (Mv) ^0.83

-Initial hue (YI):
After the polycarbonate resin was dried at 120 ° C. for 6 hours in a nitrogen atmosphere, a 3 mm-thick injection molded piece was produced at 360 ° C. with a J-100 injection molding machine manufactured by Nippon Steel, Ltd., and SC manufactured by Suga Test Instruments Co., Ltd. The YI value was measured by -1 (the larger the YI value, the more colored it is).

<By-product phenol purification process>
By-product phenol recovered from the polymerization step at about 6.3 kg / hr (6 L / hr) is the by-product phenol tank (200 L tank made of SUS304. Vc / Fc = 33 described in the specification). After storing a certain amount (about 100 L), the following distillation purification was performed and recycled as a DPC production raw material. The shortage was partially supplemented with commercially available PL.
The first distillation column was 200 Torr and the reflux ratio was 2, and the contained water was partially distilled off together with phenol, and the bottoms were supplied to the second distillation column. In the second distillation column, purified phenol was obtained at about 5.8 kg / hr from the top at 50 Torr and a reflux ratio of 0.5, and supplied to the DPC production process via the purified phenol tank. On the other hand, a phenol mixture containing 67 wt%, 7 wt%, and 4 wt% of diphenyl carbonate, bisphenol A, and oligomer, respectively, was continuously extracted from the bottom.

  Although the above experiment was continued for 400 hours, it was necessary to temporarily stop the DPC manufacturing process due to a temperature control trouble, etc., but the entire system was not stopped by using the liquid in the storage tank, I was able to deal with the problem as soon as possible. Further, during the operation, a polycarbonate grade of Mv = 15,000 was produced, and at that time, a temporary compositional variation of by-product phenol recovered from the polymerization tank was caused. The fluctuation could be alleviated, and the operating conditions of the by-product phenol purification process of the next process could be changed smoothly.

  Next, the present invention will be described more specifically with respect to the drainage treatment. First, the methods for measuring the viscosity average molecular weight (Mv) and the initial hue (YI) are as described above.

(Experimental example 1)
(DPC manufacturing process)
This was performed according to the flow shown in FIG. Details are shown below.
[DPC reaction process]
While continuously supplying molten PL and a pyridine catalyst to the DPC reactor 1, phosgene (CDC) gas was continuously supplied with mixing at 150 ° C. Subsequently, the hydrogen chloride gas (D1) produced as a by-product in the phosgenation reaction is cooled to 10 ° C., the condensate is returned to the reactor, and the uncondensed gas is neutralized with an aqueous alkali solution. After discharge. On the other hand, from the dehydrochlorination tower 2, the dehydrochlorination treatment liquid b containing about 91% by weight of DPC was continuously extracted.

[DPC washing process / DPC washing process]
The dehydrochlorination treatment liquid b was sent to the mixing tank 3 and then sent to the alkali neutralization tank 4 made of Teflon lining. Moreover, about 5 weight% sodium hydroxide aqueous solution was supplied to the alkali neutralization tank 4, and it mixed for about 10 minutes under 80 degreeC, and was adjusted to pH 8.5. The neutralized organic phase was transferred to the water washing tank 5 after stationary separation. Washing tank 5 is washed with warm water corresponding to about 30% by weight with respect to the organic phase, the aqueous phase is separated, and crude DPC (containing 1% by weight of water, 2% by weight of pyridine, 8% by weight of PL, 89% by weight of DPC) A water washing treatment solution f was obtained.

[DPC distillation process-low boiling distillation process]
Next, the water washing treatment liquid f was continuously supplied to the middle stage of the first PL distillation column 6 at about 30 kg / hr. The first PL distillation column 6 has an inner diameter of 150 mm and a height of 4.0 m, has a reflux device at the top, a raw material supply unit at the center, and is packed with sulzer packing (manufactured by Sumitomo Heavy Industries, Ltd.) in the concentration unit and recovery unit. A continuous distillation column having 8 theoretical plates was used. A mixed gas containing water, pyridine, and PL, which are substances having a lower boiling point than DPC by distillation under the conditions of a vacuum degree of 20 torr, a heating medium oil temperature of about 220 ° C., a top temperature of 80 to 100 ° C., a tower middle stage temperature of 160 ° C. F distilled off. From the bottom of the column, a first distillation residue g, which was a bottomed liquid containing DPC (water 10 wt ppm or less, pyridine 1 wt ppm or less, PL 50 wt ppm) at about 26 kg / hr, was continuously extracted.

[DPC distillation process-high boiling distillation process]
Further, the first distillation residue g was continuously supplied to the second PL distillation column 7. The second PL distillation column 7 has an inner diameter of 200 mm, a height of 4.0 m, a reflux device at the top, a raw material supply unit at the center, and sulzer packing (manufactured by Sumitomo Heavy Industries, Ltd.) packed in the concentration unit and the recovery unit. A continuous distillation column having 8 theoretical plates was used. Distillation was carried out under the conditions of a vacuum degree of 20 torr, a heating medium oil temperature of about 240 ° C., a top temperature of about 180 ° C., and a reflux ratio of 0.5. DPC distillation residue (X1), a product (DPC containing about 350 ppm by weight and about 40 ppm by weight of DPC alkyl and bromide substitutes, respectively) was purged at about 2.5 kg / hr. The purified DPC was a high-purity product containing 80 ppm by weight of PL.

(PC manufacturing process)
[PC polymerization process]
This was performed according to the flow shown in FIG. That is, the purified DPC and BPA obtained in the above DPC production process were melt-mixed in a mixing tank 21 at a 0.977 weight ratio in a nitrogen gas atmosphere and heated to 130 ° C. through a raw material introduction tube, and at a normal pressure, nitrogen In the atmosphere, the liquid level was continuously supplied into the vertical first polymerization tank 22 controlled at 210 ° C., and the valve opening degree of the polymer discharge line at the bottom of the tank was controlled so that the average residence time was 60 minutes. The level was kept constant. At the same time as the supply of the raw material mixture was started, cesium carbonate as an aqueous solution as a catalyst was continuously supplied at a flow rate of 0.5 × 10 ⁻⁶ mol to 1 mol of BPA. The polymerization liquid discharged from the tank bottom was continuously continuously supplied to the second and third vertical polymerization tanks and the fourth horizontal polymerization vessel. During the reaction, the liquid level was controlled so that the average residence time of each tank was 60 minutes, and PL produced as a by-product was distilled off at the same time. The PC evaporation component p evaporating from the first to third polymerization tanks was condensed and liquefied by a multistage condenser, a part was refluxed to each polymerization tank, and the rest was recovered in the PC recovery PL tank 29. On the other hand, the gas evaporating from the fourth polymerization vessel was solidified by one of the two freeze capacitors in parallel, the solidified part was melted by switching operation with the other freeze capacitor, and recovered in the PC recovery PL tank 29 ( Not shown).

  The polymerization conditions for each reaction vessel were as follows: first polymerization vessel (210 ° C., 100 Torr), second polymerization vessel (240 ° C., 15 Torr), third polymerization vessel (260 ° C., 0.5 Torr), fourth polymerization vessel (270 ° C.). 0.5 Torr).

  The polymer obtained above was introduced into a twin-screw extruder (Kobe Steel Co., Ltd., screw diameter 0.046 m, L / D = 40.2) 32 in a molten state, and equivalent to 5 ppm by weight per PC. Pellets were made while continuously adding butyl p-toluenesulfonate. The PC thus obtained had a viscosity average molecular weight (Mv) of 21,000 and an initial hue (YI) of 1.7.

[PL distillation process]
As a result of analyzing the PC evaporation component p recovered from the PC polymerization step, DPC was detected at 5.0% by weight, BPA at 0.5% by weight, oligomer at 0.3% by weight, and water at 0.2% by weight. It was.
The PC evaporation component p was continuously purified by the following two distillation columns (first PL distillation column 30 and second PL distillation column 31). The first PL distillation column 30 is 200 Torr, the reflux ratio is 2, and the contained water is distilled off together with a part of PL as a PC low-boiling distillate (D6). The 2PL distillation column 31 was continuously supplied. In the second PL distillation column 31, purified PL is obtained from the top at 50 Torr and a reflux ratio of 0.5, and DPC, BPA, and oligomer are 67 wt%, 7 wt%, and 4 wt% from the bottom, respectively. The contained PL distillation residue (X2) was continuously purged.

(Example of sending distillation residue X2 from the PC manufacturing process to the distillation process from the DPC manufacturing process)
PL distillation residue purged from the by-product PL purification process of the PC manufacturing process (containing X2, PL 22% by weight, DPC 67% by weight, BPA 7% by weight, oligomer 4% by weight) to the first DPC distillation column 6 of the DPC manufacturing process Then, the first distillation residue g which is the bottoms of the first DPC distillation column 6 was supplied to the second DPC distillation column 7. As a result, almost 100% of the PL distillation residue (X2) is recovered from the top of the first DPC distillation column 6, and about half of the DPC is recovered from the top of the second DPC distillation column 7, and the PL distillation residue ( The active ingredient could be efficiently recovered simply by recycling X2) to the existing predetermined process.
As a result of manufacturing the DPC and PC as described above while performing the above operations, there was no problem in the quality of the obtained DPC and PC.

(Experimental example 2)
(DPC manufacturing process)
This was performed according to the flow shown in FIG. Details are shown below.
[Recovery distillation process]
The DPC distillation residue (X1) purged from the high boiling distillation process of the DPC production process of Experimental Example 1 is supplied to the DPC recovery distillation column 8 and continuously distilled under the following conditions, and the DPC-containing recovery liquid d is distilled from the top. It was collected. The collected distillate was recycled to the washing process of the DPC manufacturing process to improve the yield. On the other hand, from the bottom of the DPC recovery distillation column, a DPC recovery distillation residue (X1 ′) which is a high boiling point product (DPC containing about 7000 wt ppm and about 800 wt ppm of DPC alkyl substitution and bromine substitution, respectively) is obtained. Continuously purged.

The conditions for DPC recovery distillation are an inner diameter of 100 mm, a height of 3.0 m, a reflux device at the top, a raw material supply unit at the center, and Sulzer Packing (manufactured by Sumitomo Heavy Industries, Ltd.) in the concentration unit and recovery unit. A packed continuous distillation column having 8 theoretical plates was used, and the vacuum degree was 20 torr, the heating medium oil temperature was about 240 ° C., the top temperature was 180 ° C., and the reflux ratio was 0.5.
Other operations were carried out in the same manner as in Experimental Example 1, and a high-purity product of purified DPC (containing PL 80 ppm by weight) was produced to produce PC.

(Example of sending distillation residue (X2) of PC manufacturing process to recovery distillation process of DPC manufacturing process)
The PL distillation residue purged from the PL distillation step of the PC manufacturing step (containing X2, PL 22% by weight, DPC 67% by weight, BPA 7% by weight, oligomer 4% by weight) was supplied to the DPC recovery distillation column 8 of the DPC manufacturing step. . As a result, almost 100% of the PL and about 80% by weight of DPC are recovered from the top of the recovery distillation column, and the active ingredient is made efficient simply by recycling the PL distillation residue X2 to the existing predetermined process. Could be recovered.
As a result of manufacturing the DPC and PC as described above while performing the above operations, there was no problem in the quality of the obtained DPC and PC.

(Experimental example 3)
(BPA manufacturing process)
The flow shown in FIGS. A sulfonic acid type acidic cation exchange resin (trade name: Diaion SK, manufactured by Mitsubishi Chemical Corporation), in which 15% of sulfonic acid groups were neutralized with 4-pyridineethanethiol in a flow-through BPA reactor having a temperature controller. -104) was charged at 60 L. This BPA reactor was charged with a PL: acetone molar ratio 10: 1 mixture at a temperature of 80 ° C. and a flow rate of 68.2 kg / hr to be reacted. The conversion rate of acetone was 80%. The reaction mixture was purged with low boiling point substances (unreacted acetone, water, part of PL) at a flow rate of 5.1 kg / h, and then cooled to 50 ° C. to precipitate adduct crystals. This was filtered and separated into adduct crystals and mother liquor. The flow rates were 16.5 kg / h and 46.5 kg / h, respectively. 10 wt% of this mother liquor was supplied to the mother liquor treatment step, and the other mother liquor was circulated as part of the raw material charged into the synthesis reactor.

  The adduct crystals obtained here were dissolved again in phenol at a flow rate of 27.2 kg / h, cooled to 50 ° C. to precipitate crystals, and filtered to form adduct crystals (11.3 kg / h ) And mother liquor (32.5 kg / h). The separated crystals were heated to 180 ° C. under a reduced pressure of 0.3 mmHg to remove PL, and BPA having a purity of 99.95% or more was obtained at a flow rate of 7.7 kg / h.

On the other hand, as shown in FIG. 4, the mother liquor supplied to the mother liquor treatment step was concentrated by distilling a part of PL with a PL evaporator 13. Next, 0.1% by weight of sodium hydroxide was contained, and the residue was charged into the bottom of the residue reactor 14 cracking distillation column controlled at 210 ° C. under a reduced pressure of 50 mmHg. The liquid level at the bottom of the column was operated under a constant condition (residence time: 1 hr), and the bottom liquid of the cracking distillation column was purged outside the system at a flow rate of 0.5 kg / h. Furthermore, the effluent from the top of the residue reactor 14 was mixed with the above-mentioned PL, and 4 L of sulfonic acid type acidic cation exchange resin (manufactured by Mitsubishi Chemical Co., Ltd .: trade name Diaion SK-104) was packed. The flow-through regeneration reactor 15 was charged at a flow rate of 4.2 kg / h and reacted at 80 ° C. The resulting reaction liquid was circulated to the first BPA reactor.
The aforementioned BPA reactor was supplemented with acetone (3.6 kg / h) and PL (18.5 kg / h) in amounts corresponding to the amount purged out of the system and the amount of BPA obtained. The reaction was carried out continuously, and BPA was continuously produced as the whole system.

(Example of sending DPC distillation residue (X1) in the DPC manufacturing process and PL distillation residue (X2) in the PC manufacturing process to the mother liquor treatment process in the BPA manufacturing process)
The DPC distillation residue (X1, DPC alkyl substitution: about 350 ppm by weight, DPC bromine substitution: about 40 ppm by weight, the rest is DPC) in the above DPC production process at a flow rate of 0.11 kg / h, PL distillation residue purged from the by-product PL purification process (containing X2, PL 22% by weight, DPC 67% by weight, BPA 7% by weight, oligomer 4% by weight) at a flow rate of 0.15 kg / h as a mother liquor in the above BPA production process It supplied to the process ((g) process). At this time, the liquid level at the bottom of the residue reactor 14 was operated under a constant condition (residence time: 1 hr), and the bottom liquid was purged out of the system at 0.6 kg / h.

As a result, almost 100% of the PL and the decomposition product of BPA are recovered from the top of the residue reactor 14 in the mother liquor treatment process, and each distillation residue is simply recycled to the existing predetermined process. The active ingredient was recovered efficiently.
As a result of manufacturing BPA, DPC, and PC as described above while performing the above operations, there was no problem in the quality of the obtained BPA, DPC, and PC.
(Experimental example 4)

(Example of sending DPC recovery distillation residue (X1 ′) of DPC manufacturing process and PL distillation residue (X2) of PC manufacturing process to mother liquor treatment process of BPA manufacturing process)
PC production at a flow rate of 0.11 kg / h of the DPC recovered distillation residue (X1 ′, alkyl substitution product of DPC: about 7000 ppm by weight, bromine substitution product of DPC: about 800 ppm by weight, the rest is DPC) in the above DPC production process PL distillation residue purged from the by-product PL purification process (containing X2, PL 22% by weight, DPC 67% by weight, BPA 7% by weight, oligomer 4% by weight) at a flow rate of 0.15 kg / h in the above BPA production process It was supplied to the mother liquor treatment step (step (g)). At this time, the liquid level at the bottom of the residue reactor 14 was operated under a constant condition (residence time 1 hr), and the bottom liquid was purged out of the system at 0.6 kg / h.

As a result, almost 100% of the above-mentioned distillation residue and decomposition product of BPA are recovered from the top of the residue reactor 14 in the mother liquor treatment process, and it is effective only by recycling each distillation residue to the existing predetermined process. The components could be recovered efficiently.
As a result of manufacturing BPA, DPC, and PC as described above while performing the above operations, there was no problem in the quality of the obtained BPA, DPC, and PC.
(Experimental example 5)

(Example in which the PL distillation residue (X2) in the PC manufacturing process is sent to the recovery distillation process in the DPC manufacturing process, and the DPC recovery distillation residue (X1 ′) is sent to the mother liquor treatment process in the BPA manufacturing process)
The PL distillation residue purged from the by-product PL purification process of the PC manufacturing process (containing X2, PL 22% by weight, DPC 67% by weight, BPA 7% by weight, oligomer 4% by weight) to the DPC recovery distillation column 8 of the DPC manufacturing process The active component supplied and distilled from the DPC recovery distillation column 8 is recycled to the washing step of the DPC production process, and the DPC recovery distillation residue (X1 ′) which is the bottom of the DPC recovery distillation column 8 is The active ingredient supplied to the mother liquor treatment process ((g) process) of the BPA production process and recovered in the process was used as a synthetic raw material for the BPA production process. As a result of continuously operating BPA, DPC and PC for 400 hours while carrying out the above operations, there is no problem in the quality of the obtained BPA, DPC and PC, and high boiling waste is the mother liquor of the BPA production process. The amount of waste discharged from the treatment process was drastically reduced and the yield was greatly improved.

Process drawing showing an example of the flow of the DPC manufacturing process according to the present invention Process drawing showing an example of the flow of the BPA manufacturing process according to the present invention Process drawing which shows the example of the flow of the water separation process (process (b-2)) of the BPA manufacturing process which concerns on this invention Process drawing which shows the example of the flow of the mother liquid processing process (process (g)) of the BPA manufacturing process which concerns on this invention Process drawing showing an example of the flow of the PC manufacturing process according to the present invention Process drawing showing an example of another flow of the PC manufacturing process according to the present invention Process drawing which shows the example of the flow at the time of providing a DPC storage process, a BPA storage process, and / or a PC storage process in the DPC manufacturing process, BPA manufacturing process, and PC manufacturing process concerning this invention In the DPC manufacturing process, the BPA manufacturing process, and the PC manufacturing process according to the present invention, the PL distillation residue (X2), the DPC distillation residue (X1), and / or the DPC recovery distillation residue (X1 ′) are sent to the predetermined process. Process diagram showing an example of the flow shown Process drawing which shows the example of the flow of the vacuum apparatus concerning this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DPC reactor 2 Dehydrochlorination tower 3 Mixing tank 4 Alkali neutralization tank 5 Water washing tank 6 1st DPC distillation tower 7 2nd DPC distillation tower 8 DPC recovery distillation tower

11 Recovery PL tank for BPA 12 PL separation tower 13 Phenol evaporator 14 Residue reactor 15 Regeneration reactor

21 Mixing tank 22 1st polymerization tank 23 2nd polymerization tank 24 3rd polymerization tank 25 4th polymerization vessel 26 Heat exchanger 27 Heat exchanger 28 Condenser 29 PC recovery PL tank 29a 1st PC recovery PL tank 29b 2nd PC use Recovery PL tank 30 First PL distillation column 31 Second PL distillation column 32 Extruders 33a and 33b

41 distillation apparatus 42 condenser 43 vacuum equipment 44 vacuum pipe 45 condensate tank 46 liquid feed pump 47 reflux pipe 48 mist catcher 49 liquid outlet 50 supply port

51 Valve 52 Valve 53 Fluid outlet 54 Fluid outlet 55 Supply port 56 Valve 57 Extraction port

A Acetone BPA Bisphenol A
C1 Alkaline catalyst C2 Basic catalyst CDC Phosgene D1 Hydrochloric acid gas D2 Neutralization drainage D3 Drainage D4 BPA low boiling point distillate D5 Exhaust gas D6 PC low boiling point distillate D7 Waste liquid

AW Water / acetone mixture DPC Diphenyl carbonate E1 Alkaline aqueous solution F Mixed gas I Acid J Additive p PC evaporation component p1 First PC evaporation component p2 Second PC evaporation component PL Phenol s-PL Byproduct phenol W Water X1 DPC distillation residue X1 'Recovery Distillation residue X2 PL distillation residue

a DPC-containing reaction solution b Dehydrochlorination treatment solution d DPC-containing recovery solution e Neutralization treatment solution f Washing treatment solution g First distillation residue k PL recovery solution p PC evaporation component q First-stage distillation residue

Claims (44)

A process for producing diphenyl carbonate using phenol and a carbonyl compound as raw materials,
And / or a bisphenol A production process for producing bisphenol A using phenol and acetone as raw materials,
In addition, in the method for producing an aromatic polycarbonate, comprising the above-mentioned diphenyl carbonate and bisphenol A as raw materials, an aromatic polycarbonate is produced through a PC polymerization step, and an aromatic polycarbonate production step for recovering by-product phenol is included.
The amount of water contained in the byproduct phenol recovered in the aromatic polycarbonate production process is 0.2% by weight or less, and is used as a raw material for the diphenyl carbonate production process and / or the bisphenol A production process. A method for producing an aromatic polycarbonate.   The said diphenyl carbonate manufacturing process is a process which has a DPC reaction process and a DPC distillation process, The manufacturing method of the aromatic polycarbonate of Claim 1 characterized by the above-mentioned.   The bisphenol A production process includes a BPA reaction process, a BPA low boiling removal process, and a BPA crystallization / separation process, and the BPA low boiling distillate discharged from the BPA low boiling removal process is subjected to a BPA water separation process. The method for producing an aromatic polycarbonate according to claim 1, further comprising a step of recovering.   Of the aromatic polycarbonate production process, the process of recovering by-product phenol is a process of liquefying the PC evaporation component in the PC polymerization process and subjecting it to a PL distillation process, and removing PC low-boiling distillate from the PC evaporation component. The method for producing an aromatic polycarbonate according to claim 1, wherein the by-product phenol is recovered.   The method for producing an aromatic polycarbonate according to claim 4, wherein the phenol concentration in the low boiling point of PC removed in the PL distillation step is 50 to 99.8% by weight. The diphenyl carbonate manufacturing process has a DPC washing process between the DPC reaction process and the DPC distillation process,
The method for producing an aromatic polycarbonate according to claim 4, wherein the PC low-boiling distillate generated in the PL distillation step is sent to the DPC washing step.   The method for producing an aromatic polycarbonate according to any one of claims 4 to 6, wherein a PC low-boiling distillate generated in the PL distillation step is sent to the BPA water separation step.   The method for producing an aromatic polycarbonate according to any one of claims 1 to 7, wherein the content of hydroxyacetone in the phenol used as a raw material in the bisphenol A production process is less than 10 ppm by weight.   The method for producing an aromatic polycarbonate according to any one of claims 3 to 8, wherein the acid catalyst used in the BPA reaction step is a sulfonic acid type cation exchange resin modified with a compound having a mercapto group. Before and / or after the PL distillation step, a PC storage step for storing a liquefied product of the PC evaporation component before being subjected to the PL distillation step and / or by-product phenol recovered in the PL distillation step is provided. The method for producing an aromatic polycarbonate according to any one of claims 4 to 9, wherein the capacity of the PC storage tank used in the PC storage step is set to a capacity that satisfies the following formula (1).
10 ≦ (Vc / Fc) ≦ 100 (1)
(In the formula (1), Vc indicates the capacity (m ³ ) of the PC storage tank, and Fc indicates the supply rate (m ³ / hr) of the PC evaporation component liquefaction product or by-product phenol.) A DPC storage step for storing the diphenyl carbonate obtained in the DPC distillation step is provided after the DPC distillation step, and the capacity of the DPC storage tank used in the DPC storage step is a capacity that satisfies the following formula (2). The method for producing an aromatic polycarbonate according to any one of claims 2 to 10, wherein:
10 ≦ (Vd / Fd) ≦ 100 (2)
(In the formula (2), Vd represents the capacity (m ³ ) of the DPC storage tank, and Fd represents the feed rate (m ³ / hr) of diphenyl carbonate.)   The fragrance according to any one of claims 3 to 11, wherein a BPA storage step for storing a mixture of bisphenol A and phenol is provided between the BPA crystallization / separation step and the PC polymerization step. A method for producing a polycarbonate. The method for producing an aromatic polycarbonate according to claim 12, wherein the capacity of the BPA storage tank used in the BPA storage step is set to a capacity satisfying the following formula (3).
10 ≦ (Vb / Fb) ≦ 1000 (3)
(In Formula (3), Vb indicates the capacity (m ³ ) of the BPA storage tank, and Fb indicates the supply amount (m ³ / hr) of bisphenol A used in the PC polymerization step.)   The mixture of bisphenol A and phenol stored in the BPA storage step is a slurry containing an adduct crystal of bisphenol A and phenol, an adduct crystal of bisphenol A and phenol, and a mixture of bisphenol A and phenol. The method for producing an aromatic polycarbonate according to claim 12 or 13, which is in any form.   The method for producing an aromatic polycarbonate according to any one of claims 12 to 14, wherein a neutralization step is provided between or before the BPA crystallization step and the PC polymerization step.   The process for producing an aromatic polycarbonate according to any one of claims 12 to 15, wherein the steps from the BPA reaction step to the BPA crystallization step are intermittently performed and the PC polymerization step is continuously performed. Method.   The method for producing an aromatic polycarbonate according to any one of claims 4 to 16, wherein the PL distillation residue produced in the PL distillation step is sent to the DPC distillation step. The diphenyl carbonate manufacturing step has a DPC recovery distillation step of recovering diphenyl carbonate from the DPC distillation residue of the DPC distillation step,
The method for producing an aromatic polycarbonate according to any one of claims 4 to 17, wherein the PL distillation residue produced in the PL distillation step is sent to the DPC distillation step and / or the DPC recovery distillation step. In the bisphenol A production process, part or all of the mother liquor discharged from the BPA crystallization / separation process is sent to the BPA mother liquor treatment process to reduce by-products in the mother liquor, and then used as a raw material for bisphenol A production. Having a step of using as part or all of the phenol used,
18. The PL distillation residue produced in the PL distillation step and / or the DPC distillation residue produced in the DPC distillation step is sent to the BPA mother liquor treatment step of the bisphenol A production step. A process for producing an aromatic polycarbonate as described in 1. above.   The PL distillation residue produced in the PL distillation step and / or the DPC distillation residue produced in the DPC distillation step and / or the DPC collection distillation residue produced in the DPC recovery distillation step are converted into the BPA mother liquor treatment step in the bisphenol A production step. The method for producing an aromatic polycarbonate according to any one of claims 4 to 19, wherein   21. The PL distillation residue produced in the PL distillation step is sent to the DPC distillation step, and then the distillation residue produced in the DPC distillation step is sent to the BPA mother liquor treatment step. A process for producing an aromatic polycarbonate as described in 1. above.   The PL distillation residue generated in the PL distillation step is sent to the DPC distillation step and / or DPC recovery distillation step, and then the DPC distillation residue and / or DPC recovery distillation residue generated in the DPC distillation step is converted into the BPA mother liquor treatment step. The method for producing an aromatic polycarbonate according to any one of claims 4 to 21, wherein   In the BPA mother liquor treatment step, a basic substance is added to part or all of the mother liquor and heated to produce phenol and a phenol derivative, and then the phenol and phenol derivative are converted using an acid catalyst or an alkali catalyst. The method for producing an aromatic polycarbonate according to any one of claims 19 to 22, wherein bisphenol A is obtained by reaction.   The method for producing an aromatic polycarbonate according to claim 23, wherein the basic substance is sodium hydroxide or potassium hydroxide. A distillation column for the DPC distillation step is provided with a condenser for condensing the substance to be distilled, a vacuum facility for reducing the pressure in the system, and a vacuum pipe connecting the condenser and the vacuum facility,
The vacuum pipe has a downward slope from the condenser side to the vacuum equipment side, and the total height of the portions rising upward from the condenser side to the vacuum equipment side is The method for producing an aromatic polycarbonate according to any one of claims 2 to 24, which is 1 m or less. In the polymerization apparatus used in the step of liquefying the PC evaporation component in the PC polymerization step, a condenser for condensing the distilled PC evaporation component, a vacuum facility for reducing the pressure in the polymerization system, and the condenser and vacuum facility, A vacuum pipe that connects
The vacuum pipe has a downward slope from the condenser side toward the vacuum equipment side, and the total height of the portions rising upward from the condenser side toward the vacuum equipment side 26. The method for producing an aromatic polycarbonate according to any one of claims 2 to 25, wherein the length is 1 m or less. A distillation column for the PL distillation step is provided with a condenser for condensing the substance to be distilled, a vacuum facility for reducing the pressure in the system, and a vacuum pipe for connecting the condenser and the vacuum facility,
The vacuum pipe has a downward slope from the condenser side to the vacuum equipment side, and the total height of the portions rising upward from the condenser side to the vacuum equipment side is 27. The method for producing an aromatic polycarbonate according to claim 2, wherein the aromatic polycarbonate is 1 m or less.   28. The method for producing an aromatic polycarbonate according to claim 26 or 27, wherein the vacuum pipe has a facility for heating and keeping the inside at a temperature equal to or higher than the melting point of the distillate from the distillation column and / or the polymerization apparatus.   The method for producing an aromatic polycarbonate according to any one of claims 25 to 28, wherein at least one liquid discharge port is provided on the vacuum equipment side of the vacuum pipe.   30. The method for producing an aromatic polycarbonate according to claim 25, wherein a supply port capable of supplying a heating fluid is provided on the condenser side of the vacuum pipe.   The method for producing an aromatic polycarbonate according to claim 30, wherein the vacuum pipe is washed by supplying the heating fluid from the supply port.   The method for producing an aromatic polycarbonate according to claim 30 or 31, wherein the heating fluid contains at least one of water vapor, phenol, and nitrogen. As a phenol used as a raw material in the diphenyl carbonate production process, a phenol containing 20 to 1000 ppm by weight of cresol and / or xylenol is used.
The aromatic according to any one of claims 1 to 32, wherein phenol produced in the polymerization step of the aromatic polycarbonate production step is used as at least a part of phenol used as a raw material in the bisphenol A production step. A method for producing polycarbonate.   The method for producing an aromatic polycarbonate according to claim 33, wherein the content of cresol and / or xylenol in the phenol used as a raw material in the bisphenol A production process is less than 20 ppm by weight.   The phenol produced in the polymerization step of the aromatic polycarbonate production step is used after passing through the step of removing water as at least part of the phenol used as a raw material in the bisphenol A production step, or 33 or 34. A method for producing an aromatic polycarbonate according to 34. The bisphenol A production process has a BPA reaction process, a BPA low boiling removal process, and a BPA crystallization / separation process, and the BPA low boiling distillate discharged from the BPA low boiling removal process is subjected to a BPA water separation process. Having a step of collecting
36. The method for producing an aromatic polycarbonate according to claim 35, wherein the step of removing water is a water separation step of the bisphenol A production step.   37. The method for producing an aromatic polycarbonate according to claim 35, further comprising a BPA high-boiling fraction separating step for separating a component having a higher boiling point than phenol after the step of removing water. In the bisphenol A production process, part or all of the mother liquor discharged from the BPA crystallization / separation process is sent to the BPA mother liquor treatment process to reduce by-products in the mother liquor, and then used as a raw material for bisphenol A production. Having a step of using as part or all of the phenol used,
The method for producing an aromatic polycarbonate according to claim 37, wherein a component having a boiling point higher than that of the phenol obtained in the BPA high-boiling removal step is sent to the BPA mother liquor treatment step.   Among the phenols by-produced in the aromatic polycarbonate production process, 50 to 95% by weight is used as at least part of the phenol used in the diphenyl carbonate production process, and 50 to 5% by weight is used in the bisphenol A production process. The method for producing an aromatic polycarbonate according to any one of claims 1 to 38, wherein the aromatic polycarbonate is used as at least part of the raw material.   Of the phenol by-produced in the aromatic polycarbonate production process, 50 to 70% by weight is used as at least a part of the phenol used in the diphenyl carbonate production process, and 50 to 30% by weight is produced in the bisphenol A production process. The method for producing an aromatic polycarbonate according to claim 39, wherein the aromatic polycarbonate is used as at least a part of the raw material.   The polymerization step in the aromatic polycarbonate production process is composed of at least three polymerization tanks, and among the polymerization tanks, the by-product phenol recovered from the first tank or the first tank and the second tank is the diphenyl carbonate. Used as at least a part of the phenol used in the manufacturing process, and used as a by-product phenol recovered from the second tank or subsequent polymerization tanks in the polymerization tank in the bisphenol A manufacturing process. The method for producing an aromatic polycarbonate according to any one of claims 1 to 40, wherein the aromatic polycarbonate is used as at least a part of the phenol.   The method for producing an aromatic polycarbonate according to any one of claims 39 to 41, wherein the byproduct phenol used in the diphenyl carbonate production step contains 1.0 wt% or less of a high-boiling compound having a higher boiling point than diphenyl carbonate. .   43. The method for producing an aromatic polycarbonate according to any one of claims 39 to 42, wherein the polymerization tank in which a by-product phenol used in the diphenyl carbonate production step is obtained has a reflux device for refluxing an evaporation component.   When the carbonyl compound is a dialkyl carbonate and / or an alkylaryl carbonate, and the phenol by-produced in the aromatic polycarbonate production process is used as a part of the raw material of the bisphenol A production process, the phenol used as the raw material is 44. The method for producing an aromatic polycarbonate according to any one of claims 39 to 43, comprising 20 ppm by weight or less of an alkyl alcohol obtained from dialkyl carbonate and alkylaryl carbonate, and dialkyl carbonate and / or alkylaryl carbonate.

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