KR20140145884A

KR20140145884A - Method For Preparing Polycarbonate

Info

Publication number: KR20140145884A
Application number: KR1020130068631A
Authority: KR
Inventors: 김성연; 박종서; 최용진
Original assignee: 주식회사 엘지화학
Priority date: 2013-06-14
Filing date: 2013-06-14
Publication date: 2014-12-24
Also published as: KR101632771B1

Abstract

The present invention relates to a production method of polycarbonate, a polycarbonate polymerization solution and an apparatus for producing polycarbonate. Exemplary methods for producing polycarbonate of the present application can provide a polycarbonate polymer solution containing a very small amount of tetrachloromethane and / or chloroethane, or not containing at all, by using a dichloromethane solvent which is to be reused by refining with a distillation column. Therefore, in the case of using the above-described method for producing polycarbonate, it is possible to reduce the process cost by reusing the solvent, to minimize the environmental pollution, and to use polycarbonate containing only very little or no impurities such as tetrachloromethane and chloroethane It is possible to produce a polymerized liquid, which can reduce the energy unnecessarily used in the drying process of the polymerized liquid and can increase the production amount of polycarbonate to the same energy.

Description

TECHNICAL FIELD The present invention relates to a method for preparing polycarbonate,

The present invention relates to a production method of polycarbonate, a polycarbonate polymerization solution and an apparatus for producing polycarbonate.

Polycarbonate has been widely used in many fields due to its excellent heat resistance, impact resistance, transparency and dimensional stability. As an industrial production method of such polycarbonate, for example, there is known a method of reacting a divalent hydroxy compound with phosgene, or an ester exchange method of reacting a divalent hydroxy compound with a carbonic acid diester. Among them, phosgene used in the method of using phosgene is produced when it is necessary due to toxicity, is used immediately, and most of the phosgene is not subjected to a separate purification process after its manufacture. Thus, the product of phosgene contains tetrachloromethane (CCl ₄ ), which is a co-produced product of the production of phosgene. This phosgene product is added to the polycarbonate without any additional purification process, and the tetrachloromethane contained in the phosgene product is dissolved in the halogen-based organic solvent. On the other hand, dichloromethane (CH ₂ Cl ₂ ) is mainly used as a halogen-based organic solvent, and when polycarbonate is produced on a large scale, dichloromethane used for the production of polycarbonate is often reused. However, when polycarbonate is produced by the method using phosgene as described above, the amount of tetrachloromethane accumulated in the dichloromethane increases as the number of times of re-use of the dichloromethane increases, and when the polycarbonate is produced using such a solvent , There is a problem that a large amount of tetrachloromethane is contained also in the polymerization liquid containing the polycarbonate produced.

Further, in the process of producing polycarbonate by reacting phosgene with a divalent hydroxy compound, chloroethane (CH ₃ CH ₂ Cl) is produced as a by-product, and the chloroethane is dissolved in dichloromethane to increase the number of times of dichloromethane reuse The amount is accumulated. Therefore, when dichloromethane is reused to produce polycarbonate, a large amount of tetrachloromethane and chloroethane are contained in the polymer solution containing the polycarbonate thus produced, which wastes enormous energy for drying it to a standard value.

The present application provides a process for producing polycarbonate, a polycarbonate polymerization solution and an apparatus for producing polycarbonate.

One embodiment of the present application is directed to a process for producing a dichloromethane comprising feeding a feed comprising dichloromethane to a distillation column, purifying the dichloromethane from the feed in the distillation column, introducing the purified dichloromethane into a polycarbonate production reactor, Wherein the polycarbonate is used as a solvent to produce a polycarbonate.

Hereinafter, the method for producing the polycarbonate will be described in detail.

The method of producing the polycarbonate can be described with reference to Figs. 1 and 2 which are one example. FIG. 1 shows an exemplary distillation column which can be applied in the above production process, and FIG. 2 exemplarily shows a device comprising the distillation column and a polycarbonate production reactor connected to the distillation column. In one example, the process for preparing the polycarbonate may include feeding (40) a feed comprising dichloromethane to the distillation column (100) to purify the dichloromethane from the feed in the distillation column (100). In addition, in one example, the process for preparing the polycarbonate can include introducing purified dichloromethane into the polycarbonate production reactor 200 and using the purified dichloromethane as a solvent to produce a polycarbonate.

The method for producing the polycarbonate can be described with reference to FIG. 3, which is one example. In one example, the polycarbonate may be prepared by preparing a polycarbonate in a reactor 200, recovering the used solvent, supplying the recovered solvent as a feed 40 to the distillation column 100, ) And purifying the dichloromethane from the solvent and introducing the purified dichloromethane back into the reactor (200). That is, for example, after polycarbonate is prepared using purified dichloromethane as a solvent, a polycarbonate is prepared, the remaining solvent is recovered, and the recovered dichloromethane is again fed to a distillation column to purify dichloromethane from the solvent. The process of using it as a solvent for the production of the polycarbonate again can be repeatedly carried out. Therefore, when the above method is used, even when the dichloromethane solvent is continuously reused, a polycarbonate polymerization liquid containing very little or no impurities can be produced.

The method for producing the polycarbonate can employ a generally known method. For example, the polycarbonate may be prepared by a method using a compound represented by the following formula (1) and a polyhydric hydroxy compound, and an ester exchange method for reacting a polycarboxylic diester with a polyhydric hydroxy compound.

[Chemical Formula 1]

X ₁ and X ₂ are each independently a halogen selected from fluorine (F), chlorine (Cl), bromine (Br) and iodine (I).

In one example, the step of preparing the polycarbonate may include reacting the compound represented by Formula 1 and a polyhydric hydroxy compound in the presence of a solvent.

In one example, the compound represented by Formula 1 may be a phosgene in which X ₁ and X ₂ in Formula 1 are all Cl. Generally, the phosgene is produced and used immediately when necessary due to toxicity, and is not subjected to a separate purification process after its manufacture. That is, most of the phosgene products not subjected to a separate purification process contain tetrachloromethane (CCl ₄ ), which is a co-produced product of phosgene production. These phosgene products are added to the polycarbonate production process, and tetrachloromethane contained in the phosgene product is dissolved in dichloromethane, and the amount of dichloromethane is accumulated as the number of times of dichloromethane is increased. Further, in the process of producing the polycarbonate by reacting the phosgene with the polyhydric hydroxy compound, chloroethane (CH ₃ CH ₂ Cl) is produced as a by-product, and the chloroethane is dissolved in the dichlorodomethane to increase the number of times of dichloromethane reuse The amount is accumulated. However, as described above, the amount of the impurities contained in the dichloromethane does not increase when the dichloromethane is purified through the distillation column.

The polyhydric hydroxy compound which can be reacted with the compound represented by the formula (1) to produce a polycarbonate can be used without limitation in the compounds known in the art. Examples of the polyhydric hydroxy compound include bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2- (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2- Methane, 1,1-bis (4-hydroxyphenyl) phenylethane, 4,4'-dihydroxy-2,2,2-triphenylethane, 2,2- Bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, (4-hydroxy-3-tert-butylphenyl) propane, 1,1-bis Bis (3,5-dimethyl-4-hydroxyphenyl) propane, 1,1'-bis (4-hydroxyphenyl) -p-diisopropylbenzene, 1,1'- Bis (4-hydroxyphenyl) -m-diisopropylbenzene or 1,1-bis (4-hydroxyphenyl) cyclohexyl And the like.

The flow rate of the feed containing dichloromethane to the distillation column is not particularly limited and can be adjusted depending on, for example, the operating conditions of the distillation column and the amount of the solvent used in the production of the polycarbonate. In one example, the feed comprising dichloromethane may be fed to the distillation column at a flow rate of about 50 to 150 kg / hr.

In one example, the feed may comprise dichloromethane, tetrachloromethane and chloroethane. The content of tetrachloromethane contained in the feed is not particularly limited, but may be, for example, 1.5 wt% or less, 1.0 wt% or less, 0.7 wt% or less, 0.5 wt% or less, 0.3 wt% or less, or 0.1 wt% . The smaller the content of tetrachloromethane contained in the feed is, the more advantageous it is to purify the dichloromethane, so that the lower limit is not limited. For example, the lower limit may be 0 wt% or more, or 0 wt% or more. Similarly, the content of chloroethane contained in the feed is not particularly limited, but may be, for example, 5.5 wt% or less, 5.0 wt% or less, 4.5 wt% or less, 4.0 wt% or less, 3.5 wt% or less, 3.0 wt% or less, 2.5 Up to 2.0 wt.%, Up to 1.5 wt.%, Up to 1.0 wt.%, Or up to 0.8 wt.%. Also, the lower the content of the chlorotrifluoro-feed is, the more advantageous it is to purify the dichloromethane, so that the lower limit is not limited. For example, the lower limit may be 0 wt% or more, or 0 wt% or more.

If the content of tetrachloromethane or chloroethane contained in the feed exceeds the above-mentioned range, the purification efficiency may decrease, or the cost for purification may increase.

In one example, moisture can be removed from the feed with tetrachloromethane and chloroethane through purification of the dichloromethane from feed fed to the distillation column. Thus, pure dichloromethane containing very little or very little moisture can be obtained.

The operation temperature of the lower portion and the upper portion of the distillation column in the process of purifying dichloromethane from the feed is not particularly limited and can be appropriately adjusted to effectively remove tetrachloromethane and chloroethane from the feed to obtain pure dichloromethane . In one example, the lower operating temperature of the distillation column during the purification of dichloromethane may be about 10 ° C to 100 ° C. The other lower limit of the lower operating temperature may be, for example, about 20 캜, 30 캜 or 35 캜. The other upper limit of the lower operating temperature may be, for example, about 90 캜, 80 캜, 70 캜, 60 캜 or 50 캜. In addition, the upper operation temperature of the distillation column during the purification of the dichloromethane may be about 10 ° C to 100 ° C. The other lower limit of the upper operating temperature may be, for example, about 15 캜, 20 캜, 25 캜 or 30 캜. The upper limit of the upper operating temperature may be, for example, about 90 ° C, 80 ° C, 70 ° C, 60 ° C or 50 ° C. If dichloromethane is purified from the feed with the upper and lower operating temperatures of the distillation column being maintained within the above-mentioned range, dichloromethane having high purity can be obtained with excellent purification efficiency. In addition, the upper and lower operating temperatures may be selected within the ranges described above so as not to overlap each other. For example, the bottom operating temperature of the distillation column during the purification process can be adjusted to be higher than the upper operating temperature. For example, the lower operating temperature may be from about 1 캜 to about 10 캜, from about 1 캜 to about 9 캜, from about 1 캜 to about 8 캜, from about 1 캜 to about 7 캜, from about 1 캜 to about 5 캜, Lt; RTI ID = 0.0 > 5 C < / RTI > The upper and lower operating temperatures may be, for example, temperatures based on absolute pressure.

The operation pressure of the lower part and the upper part of the distillation tower in the process of purifying dichloromethane is not particularly limited and the operating pressure can be adjusted in consideration of, for example, the operation temperature of the lower part and the upper part of the distillation tower. In one example, the lower operating pressure of the distillation column during the purification of the dichloromethane may be in the range of 500 mbar to 5000 mbar in absolute pressure. Other lower limits of the lower operating pressure may be, for example, 600 mbar, 700 mbar, 800 mbar, 900 mbar, 950 mbar or 1,000 mbar. The other upper limit of the lower operating pressure may be, for example, 4000 mbar, 3000 mbar, 2000 mbar, 1500 mbar or 1300 mbar. Also, in one example, the upper operating pressure of the distillation column in the dichloromethane purification process may be from about 200 mbar to about 5000 mbar in absolute pressure. Other upper limits of the upper operating pressure may be about 300 mbar, 400 mbar, 500 mbar, 600 mbar, 700 mbar, 800 mbar, 900 mbar, 950 mbar, 960 mbar, 980 mbar, 990 mbar or about 1,000 mbar. Further, the upper limit of the upper operating pressure may be, for example, 4000 mbar, 3000 mbar, 2000 mbar, 1500 mbar or 1300 mbar.

The range of the lower and upper pressures is not particularly limited, and for example, the lower operating pressure can also be determined according to the upper pressure determined in consideration of proper purification efficiency.

Another embodiment of the present invention relates to a polycarbonate polymerization liquid prepared by the above-described method for producing polycarbonate, wherein the content of tetrachloromethane is less than 100 ppm and the content of chloroethane is less than 2000 ppm.

As used herein, the term " polycarbonate polymer solution " means a solution containing a polycarbonate before purification into a solution in which polycarbonate is polymerized.

In one example, the polycarbonate polymerization liquid may be obtained through the above-described method for producing polycarbonate, and the polycarbonate polymerization liquid may contain a very small amount of tetrachloromethane and chloroethane.

In one example, the polycarbonate-polymerized liquid can be processed into a polycarbonate product through a step of drying the impurities contained in the polymerization liquid. However, the amount of each impurity contained in the polycarbonate polymer solution may be different from that allowed to be contained in the polymerization solution. In this case, as an example, energy for drying impurities having a small content that can be contained in the polymerization solution may be used to dry other impurities already contained in the reference solution in the polymerization solution, resulting in energy inefficiency. For example, the content of water allowed to be contained in the polymerization solution is less than several thousand ppm. At this time, the water content during drying of the polymer solution is dried to a content of much less than several thousand ppm, for example, about several hundred ppm, and unnecessary energy can be used for drying the water. Therefore, it is possible to prevent unnecessary energy from being used in the drying process of the polymerization liquid by controlling the polycarbonate polymerization liquid to contain very small amounts of tetrachloromethane and chloroethane.

In one example, adjusting the polycarbonate polymerization solution to include very small amounts of tetrachloromethane and chloroethane can be performed by increasing the purity of the solvent used in the polycarbonate polymerization. The reason for this is that the content of impurities such as tetrachloromethane, chloroethane and water in the solvent used for producing the polycarbonate is such that the impurities are not involved in the synthesis of the polycarbonate. Therefore, the content of the polycarbonate obtained after the synthesis of the polycarbonate Or at least maintained in the polymer solution. Therefore, the use of a high purity solvent can reduce the energy entering the drying process after polycarbonate polymerization. That is, the purity of the solvent used for producing the polycarbonate must be high to improve the production efficiency of the polycarbonate.

In one example, the content of tetrachloromethane in the polycarbonate polymer solution is less than 100 ppm, less than 95 ppm, less than 90 ppm, less than 85 ppm, less than 80 ppm, less than 75 ppm, less than 70 ppm, less than 65 ppm, , Less than 55 ppm, less than 50 ppm, or less than 45 ppm. The smaller the content of tetrachloromethane in the polymerization liquid is, the lower the energy used for drying the tetrachloromethane from the polymerization liquid can be saved, so that the lower limit is not limited. For example, the lower limit may be 0 ppm.

In one example, the content of chloroethane contained in the polycarbonate polymer solution is less than 2000 ppm, less than 1800 ppm, less than 1600 ppm, less than 1400 ppm, less than 1200 ppm, less than 1000 ppm, less than 900 ppm, less than 800 ppm , Less than 700 ppm, less than 680 ppm, less than 650 ppm, less than 630 ppm, less than 600 ppm, less than 580 ppm, or less than 560 ppm. The content of chloroethane in the polymerization solution is preferably as small as that of tetrachloromethane, and the lower limit thereof is not limited. For example, the lower limit may be 0 ppm.

Another embodiment of the present application is directed to a process for the preparation of dichloromethane from a distillation column which is fed with a feed comprising dichloromethane to purify dichloromethane from the feed and to dichloromethane which is purified in the distillation column, The present invention relates to an apparatus for producing polycarbonate including a reactor installed so that the production of polycarbonate proceeds.

In one example, the apparatus for producing polycarbonate may be an apparatus for implementing the above-described method for producing polycarbonate.

An apparatus for producing the polycarbonate will be described in detail with reference to FIG. 2 as an example, but the apparatus for producing the polycarbonate is not limited to FIG. Referring to FIG. 2, an apparatus for producing polycarbonate may include a distillation column 100 for purifying a feed containing dichloromethane and a reactor 200 for proceeding with the synthesis of a polycarbonate. On the left side of the distillation column 100 of FIG. 2, the direction of the flow of supplying (40) a feed containing dichloromethane to the distillation column is indicated. FIG. 2 shows that the feed is fed from the middle of the distillation column, but the feeding position of the feed is not limited to this, and the distillation efficiency of the substance to be distilled may be considered.

Figure 2 shows three outflow streams (1, 2, 3) from the distillation column as an example. Each of the outflow streams 1, 2 and 3 is divided into a stream 50 which is refluxed into the distillation column via the heat exchanger 10, 20 and 30 from the distillation column and a stream 60 which finally flows out of the distillation column. The amount of the reflux stream into the distillation column and the amount of the finally discharged stream from the distillation column can be expressed as a mass reflux ratio and the mass reflux ratio can be expressed by the amount of the reflux stream into the distillation column when the amount of the finally discharged stream from the distillation column is 1 . Thus, one example is that the mass reflux ratio of 3 satisfies the expression of "the amount of flow finally flowing out of the distillation column: the flow amount of reflux into the distillation column = 1: 3", so that the amount of reflux into the distillation column It can mean that the mass is three times greater than the amount of flow that flows out. The mass reflux ratio of each outflow can be appropriately adjusted in consideration of the purification efficiency and the like, and is not particularly limited. As an example, the mass reflux ratio in the flow of refined dichloromethane may be controlled to be greater than 150, greater than 160, greater than 170, or greater than 180. The upper limit of the mass reflux ratio is not particularly limited, but may be, for example, about 1,000 or less, 900 or less, 800 or less, 700 or less, or 650 or less. If the distillation column has a plurality of outflow points, the mass reflux ratio may be the outflow point from which the purified dichloromethane flows out of the distillation column.

The heat exchangers 10, 20 and 30 of FIG. 2 may serve as a reboiler or a condenser, and may be used for various purposes depending on the position where the heat exchanger is disposed. In one example, the heat exchanger 30 placed on the outflow stream 3 at the bottom of the distillation tower of Fig. 2 may be a reboiler and may be an outlet stream 1 at the top of the distillation column and an outflow stream 2 The heat exchangers 10, 20 may be condensers.

In FIG. 2, the distillation tower according to one example is shown as having a plurality of stages, but the number of the distillation tower is not limited by FIG. In one example, the distillation column may be a multi-stage distillation column having 10 to 40 stages.

The polycarbonate production apparatus may also be installed in such a manner that the solvent used in the reactor can be recovered and introduced into the distillation column again in one example. Here, the reactor included in the polycarbonate production apparatus can be used without limitation those conventionally used in the polycarbonate manufacturing industry.

Referring to FIG. 3, one can see that the reactor 200 and the distillation column 100 are connected so that the solvent used in the reactor 200 can be recovered and introduced into the distillation column 100 again. That is, the apparatus for producing polycarbonate includes a first part in which a distillation column and a reactor are connected so that purified dichloromethane can be introduced into the reactor, for example, a distillation column, and a first part in which a solvent used in the reactor is recovered and then introduced into the distillation column. There may be a second portion to which the reactor is connected.

Exemplary methods for producing polycarbonate of the present application can provide a polycarbonate polymer solution containing a very small amount of tetrachloromethane and / or chloroethane, or not containing at all, by using a dichloromethane solvent which is to be reused by refining with a distillation column. Therefore, in the case of using the above-described method for producing polycarbonate, it is possible to reduce the process cost by reusing the solvent, to minimize the environmental pollution, and to use polycarbonate containing only very little or no impurities such as tetrachloromethane and chloroethane It is possible to produce a polymerized liquid, which can reduce the energy unnecessarily used in the drying process of the polymerized liquid and can increase the production amount of polycarbonate to the same energy.

1 is a schematic view of a cross-sectional view of a distillation column according to one embodiment.
Figures 2 and 3 are schematic cross-sectional views of an apparatus for producing polycarbonate according to one embodiment.

The present application will be described in more detail with reference to the following examples and comparative examples, but the scope of the present application is not limited by the following examples.

Example One.

A feed having a composition as described in the feed column of Table 1 below was connected to a distillation tower having 22 reactors connected to a reactor of polycarbonate and equipped with a reboiler and a condenser, and supplied at a flow rate of 100 kg / hr. The upper operating temperature of the running distillation column was maintained in the range of about 38.8 캜 to 39.3 캜, and the lower operating temperature was maintained in the range of about 41.2 캜 to 41.7 캜. In addition, the operating pressure at the top of the distillation tower was 1013 mbar, and the operating pressure at the bottom of the distillation tower was 1050 mbar. The feed was separated into the respective components in streams 3 to 3, which are the three outflow streams shown in Fig. Stream 1 is the outflow stream at the top of the distillation column, stream 2 is the outflow stream at the 10th stage of the distillation column, and stream 3 is the outflow stream at the bottom of the distillation column. Of the three effluent streams shown in FIG. 1, the mass reflux ratio in streams 1 and 3 was adjusted to zero and the mass reflux ratio in stream 2 was adjusted to 189.8.

The composition of the components obtained in the three outflow streams stream 1 to 3 shown in FIG. 1 are shown in Table 1 below. Among them, the flow of stream 2 was separated into solvents for the production of polycarbonate and was used to evaluate the energy efficiency of the polycarbonate production process.

ingredient Boiling point Feed Stream 1 Stream 2 Stream 3 unit
(kg / hr) CH ₂ Cl ₂ 39.6 DEG C 99.58 0.0578 98.584 0.417 CH ₃ CH ₂ Cl 12.3 DEG C 0.20 0.145 0.055 trace CCl ₄ 76.72 DEG C 0.02 trace 0.004 0.016 H ₂ O 100 ℃ 0.20 0.020 0.180 trace unit
(weight%) CH ₂ Cl ₂ 39.6 DEG C 99.58% 77.79% 99.80% 96.30% CH ₃ CH ₂ Cl 12.3 DEG C 0.20% 19.52% 0.0556% trace CCl ₄ 76.72 DEG C 0.02% trace 0.004% 3.70% H ₂ O 100 ℃ 0.20% 2.69% 0.20% trace

Example 2.

The same procedure as in Example 1 was repeated except that the composition of the feed in Example 1 was changed to the composition described in the feed column in Table 2 below and the mass reflux ratio in stream 2 of the distillation column was adjusted to 600 The solvent was separated and the results are shown in Table 2.

ingredient Boiling point Feed Stream 1 Stream 2 Stream 3 unit
(kg / hr) CH ₂ Cl ₂ 39.6 DEG C 99.02 0.919 98.030 0.071 CH ₃ CH ₂ Cl 12.3 DEG C 0.70 0.662 0.038 trace CCl ₄ 76.72 DEG C 0.08 trace 0.004 0.076 H ₂ O 100 ℃ 0.20 0.041 0.158 trace unit
(weight%) CH ₂ Cl ₂ 39.6 DEG C 99.02% 56.66% 99.80% 48.40% CH ₃ CH ₂ Cl 12.3 DEG C 0.70% 40.81% 0.0383% trace CCl ₄ 76.72 DEG C 0.08% trace 0.004% 51.6% H ₂ O 100 ℃ 0.20% 2.53% 0.20% trace

Comparative Example One.

(Feed containing 99.58 parts by weight of dichloromethane, 0.20 parts by weight of chloroethane, 0.02 part by weight of tetrachloromethane and 0.20 parts by weight of water) containing dichloromethane before purification in Example 1 was evaluated for the energy efficiency of the polycarbonate production method Was used as the solvent.

Comparative Example 2.

(Feed containing 99.02 parts by weight of dichloromethane, 0.70 parts by weight of chloroethane, 0.08 part by weight of tetrachloromethane and 0.20 parts by weight of water) containing dichloromethane before purification in Example 2 was evaluated for the energy efficiency of the polycarbonate production method Was used as the solvent.

The components of the solvent for preparing the polycarbonates of Examples 1 to 2 and Comparative Examples 1 and 2 are shown in Table 3 below.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 CH ₂ Cl ₂ 99.80 99.80 99.58 99.02 CH ₃ CH ₂ Cl 0.0556 0.0383 0.20 0.70 CCl ₄ 0.004 0.004 0.02 0.08 H ₂ O 0.20 0.20 0.20 0.20 Content: wt%

As shown in Table 3, in the polycarbonate polymerization liquid prepared using the solvents of Comparative Examples 1 and 2, more chloroethane and tetrachloromethane than the polycarbonate polymerization liquid prepared using the solvents of Examples 1 and 2 And the like. Therefore, the production method of the polycarbonate using the solvents of Comparative Examples 1 and 2 uses more energy to dry the by-products than those of Examples 1 and 2. As a result, the production of polycarbonate to the same energy is significantly lowered .

1: Effluent flow at the top of the distillation tower
2: Effluent flow in the middle of the distillation column
3: Effluent flow from the bottom of the distillation tower
10, 20, 30: heat exchanger
40: feeding a feed containing dichloromethane to the distillation column
50: flow reflux into the distillation column
60: Flow finally flowing out from the distillation tower
70: Recovery of polycarbonate
100: distillation tower
200: reactor

Claims

Feeding a feed containing dichloromethane to the distillation column, purifying the dichloromethane from the feed in the distillation column, introducing the purified dichloromethane into a polycarbonate production reactor, and using the purified dichloromethane as a solvent to produce a polycarbonate &Lt; / RTI >

The process of claim 1, further comprising recovering the solvent in a polycarbonate production reactor, feeding the solvent back to the distillation column, purifying the dichloromethane from the solvent in the distillation column, and introducing the purified dichloromethane back into the reactor &Lt; / RTI >

The polycarbonate according to claim 1, wherein the polycarbonate is prepared by reacting a compound represented by the following formula (1) and a polyhydric hydroxy compound in the presence of a solvent:
[Chemical Formula 1]

In Formula 1, X ₁ and X ₂ are each independently fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

The process for producing a polycarbonate according to claim 3, wherein X ₁ and X ₂ in formula (1) are chlorine (Cl).

4. The process according to claim 3, wherein the polyhydric hydroxy compound is selected from the group consisting of bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2- Bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) Dihydroxy-2,2,2-triphenylethane, 2,2-bis (3,5-dihydroxyphenyl) phenylmethane, 1,1- Bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxy- (4-hydroxy-3-tert-butylphenyl) propane, 2,2-bis (4-hydroxy- (3,5-dimethyl-4-hydroxyphenyl) propane, 1,1'-bis (4-hydroxyphenyl) -p-diisopropylbenzene, 1 , 1'-bis (4-hydroxyphenyl) -m-diisopropylbenzene or 1,1-bis (4-hydroxyphenyl ) The process for producing a cyclohexane polycarbonate.

2. The process of claim 1 wherein the feed comprises dichloromethane, tetrachloromethane and chloroethane.

The process for producing a polycarbonate according to claim 6, wherein the content of tetrachloromethane in the feed is 1.5 wt% or less.

The process for producing a polycarbonate according to claim 6, wherein the content of chloroethane in the feed is 5.5 wt% or less.

The method of claim 1, wherein the upper operating temperature of the distillation column is maintained at 10 ° C to 100 ° C during dichloromethane purification.

The method of claim 1, wherein the upper operating pressure of the distillation column is maintained at 200 mbar to 5,000 mbar in the dichloromethane purification process.

The method of claim 1, wherein the lower operating temperature of the distillation column is maintained at 10 ° C to 100 ° C during dichloromethane purification.

The method of claim 1, wherein the lower operating temperature of the distillation column is maintained to be higher than the upper operating temperature in the dichloromethane purification process.

The method of claim 1, wherein the lower operating pressure of the distillation column is maintained at 500 mbar to 5,000 mbar in the dichloromethane purification process.

A polycarbonate polymer solution prepared by the method of claim 1, wherein the content of tetrachloromethane is less than 100 ppm and the content of chloroethane is less than 2000 ppm.

A distillation column installed to purify dichloromethane from a feed containing dichloromethane and a reactor provided with dichloromethane introduced in the distillation column to introduce dichloromethane as a solvent so as to allow the production of polycarbonate Manufacturing apparatus.

The apparatus for producing polycarbonate according to claim 15, wherein the reactor and the distillation column are installed so that the solvent used in the reactor can be recovered and introduced into the distillation column again.