KR101823723B1 - Control method for safe continuous manufacturing of polycarbonate oligomer - Google Patents

Abstract

A method for safely manufacturing a polycarbonate oligomer, which is capable of automatically detoxifying harmful phosgene even in the event of an abnormality without leaking out of the system.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a control method for secure continuous production of a polycarbonate oligomer,

The present invention relates to a control method for the safe continuous production of polycarbonate oligomers.

In general, as a production method of a polycarbonate, there are known an interfacial polymerization method in which biphasic phenols (bisphenols) are directly reacted with phosgene, and an ester exchange method in which bisphenols and diphenyl carbonate are reacted under solventless conditions. However, Since the carbonate is obtained, the interface method becomes mainstream (see, for example, Patent Document 1).

In the interfacial method, bisphenols, alkali compounds such as sodium hydroxide and phosgene are used as raw materials of the polycarbonate, and if necessary, a terminal stopper (molecular weight regulator) is added. In an industrial production plant for polycarbonate, phosgene is generally blown into an alkali aqueous solution of bisphenols to produce a polycarbonate oligomer having a reactive chloroformate group, and simultaneously or sequentially with the polycarbonate oligomer, a polycarbonate oligomer And an alkali aqueous solution of a bisphenol are reacted to produce a polycarbonate.

Patent Document 2 discloses a method of storing liquid liquefied phosgene obtained by distillation purification of phosgene and producing polycarbonate using the liquefied phosgene.

However, since phosgene is highly toxic, it is not preferable from the viewpoint of safety to store it. For example, there is a risk that phosgene leaks if the liquefied phosgene reservoir is destroyed by corrosion or the like. Such a risk can be reduced by installing a phosgene detoxification facility. However, because the amount of phosgene retained is large, it takes time to detoxify the phosgene, and in order to detoxify in a short time, a large-scale facility is required.

Patent Document 3 discloses a continuous production method of a polycarbonate oligomer used for producing a polycarbonate oligomer without directly liquefying a phosgene gas obtained by reacting chlorine and carbon monoxide. According to this method, the amount of phosgene retained in the system is reduced as compared with the method using liquefied phosgene.

Japanese Laid-Open Patent Publication No. 2004-331916 Japanese Patent Application Laid-Open No. 2001-261321 International Publication No. 2007/083721

However, none of the above-mentioned Patent Documents discloses a case in which an accident such as clogging of the reactor occurs due to precipitation of oligomer by the feedstock supply trouble to the oligomer reactor, and no harmful phosgene is leaked outside the system A method for producing polycarbonate is not disclosed.

A problem to be solved by the present invention is to provide a method for continuously producing a polycarbonate oligomer in the production of polycarbonate, a method for automatically stopping the apparatus even in the event of an abnormality and for removing harmful phosgene without leaking outside the system And the like.

The above problem is solved by a control method of continuous production of the polycarbonate oligomer described below.

(1) for continuously producing a phosgene gas containing unreacted carbon monoxide by supplying chlorine and carbon monoxide to a phosgene reactor, and a step (1) for continuously producing a phosgene gas, an alkali aqueous solution of a dihydric phenol, and an organic A process for controlling continuous production of a polycarbonate oligomer comprising continuously (2) continuously feeding a solvent into an oligomer reactor to continuously prepare a reaction mixture containing a polycarbonate oligomer,

The supply of the chlorine and the carbon monoxide in the step (1) is stopped, the supply of the phosgene gas to the oligomer reactor is stopped, and the supply of the phosgene to the oligomer reactor is stopped when the following conditions (i) and / A method for controlling continuous production of a polycarbonate oligomer wherein a toxic gas containing a gas is transferred to a detoxifying means to render it harmless.

(I): the flow rate of the solvent (F2 [kg / h]) supplied to the oligomer reactor, the flow rate of the alkali aqueous solution of the divalent phenol compound (F3 [kg / h]) and the concentration of the dihydric phenol compound When the value of the parameter < F2 / (F3 x a / 100) >

(Ii): the flow rate of the phosgene gas supplied to the oligomer reactor (F1 [kg / h]), the flow rate of the alkali aqueous solution of the dihydric phenol compound (F3 [kg / h]) and the concentration of the dihydric phenol compound ) &Lt; (F3 x a / 100) / F1 > becomes equal to or smaller than 1.23.

According to the method of the present invention, in the continuous production of the polycarbonate oligomer by the interfacial method, even when an accident occurs such that the oligomer is precipitated by the raw material supply trouble to the oligomer reactor and the reactor is occluded, The supply of carbon monoxide and the supply of phosgene to the oligomer reactor are automatically stopped and the phosgene in the system is automatically controlled to be sent to the detoxification means so that the polycarbonate oligomer can be safely produced without leaking phosgene out of the system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart outlining one preferred embodiment of a control method for continuous production of a polycarbonate oligomer of the present invention.

The control method of the continuous production of the polycarbonate oligomer of the present invention is characterized in that, in the continuous production of the polycarbonate oligomer by the interfacial method, the flow rate of the phosgene gas (F1) supplied to the oligomer reactor, the flow rate of the solvent (F2) The supply of chlorine and carbon monoxide, which are raw materials of the po- singen, and the supply of the carbon monoxide and the carbon monoxide, and the supply of the carbon monoxide, And automatically controlling the supply of phosgene in the system to the detoxification means while automatically stopping the supply of phosgene to the oligomer reactor.

[Production of polycarbonate]

The control method of the continuous production of the polycarbonate oligomer of the present invention is applied to the interfacial method in which the divalent phenol and phosgene are directly reacted, and is applied in the continuous reaction method.

The method for continuously producing the polycarbonate oligomer according to the present invention comprises the steps of (1) continuously producing phosgene gas containing unreacted carbon monoxide by supplying chlorine and carbon monoxide to a phosgene reactor, and (3) (2) continuously feeding a continuously prepared aqueous solution of phosgene gas, an aqueous alkali solution of a dihydric phenol and an organic solvent into an oligomer reactor, thereby continuously producing a reaction mixture containing a polycarbonate oligomer.

&Lt; Process (1) >

Process (1) is a process for continuously producing phosgene gas containing unreacted carbon monoxide by supplying chlorine and carbon monoxide to a phosgene reactor.

From the viewpoint of the quality of the polycarbonate oligomer, carbon monoxide is preferably prepared by reacting oxygen with coke, petroleum, natural gas, alcohol or the like, and purifying at a purity of 95 vol% or more. Particularly, it is preferable that the content of the sulfur component is 50 ppm or less. The ratio (molar ratio) of chlorine to carbon monoxide is preferably 1: 1.01 to 1: 1.3, more preferably 1: 1.02 to 1: 1.2.

The reaction can be carried out by a known method described in, for example, Japanese Patent Publication (Kokoku) No. 55-14044. As the catalyst, a catalyst containing activated carbon as a main component can be used. Since the reaction is an exothermic reaction, it is preferable to cool the phosgene reactor to maintain the internal temperature of the reactor at 350 DEG C or lower.

The phosgene gas obtained in the step (1) usually contains unreacted carbon monoxide. The content of carbon monoxide in the phosgene gas is preferably 1 to 30% by volume, more preferably 2 to 20% by volume from the viewpoints of cost and quality of the polycarbonate oligomer. That is, a phosgene gas having a purity of 99 to 70% by volume is preferable.

&Lt; Process (2) >

Step (2) is a step of continuously producing a reaction mixture containing a polycarbonate oligomer by successively supplying an aqueous alkali solution of phosgene gas, a bifunctional phenol and an organic solvent continuously prepared in the step (1) to an oligomer reactor to be.

Examples of raw materials in the production of the polycarbonate include phosgene gas, divalent phenols (bisphenols), alkaline compounds used for dissolving the divalent phenols, and organic solvents. If necessary, monovalent phenol Or other additives may be used.

As the phosgene gas, the phosgene gas continuously produced in the above step (1) is used.

As the dihydric phenols, 2,2-bis (4-hydroxyphenyl) propane (collectively, bisphenol A; BPA) is preferable in view of the physical properties of the polycarbonate. Examples of the dihydric phenols other than bisphenol A include bis (4-hydroxyphenyl) methane; 1,1-bis (4-hydroxyphenyl) ethane; Bis (4-hydroxyphenyl) alkane such as 1,2-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) cyclohexane; Dihydroxydiphenyl, bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) cycloalkane such as 1,1-bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfide, bis Hydroquinone, and the like. These bifunctional phenols may be used singly or in combination of two or more kinds.

As the alkali compound used for dissolving the dihydric phenols, sodium hydroxide is preferable.

The alkaline aqueous solution of the divalent phenol is supplied after it is adjusted to a predetermined concentration in advance. At this time, the concentration (a [mass%]) is monitored online using an analyzer based on titration and the like. The measurement method is not particularly limited, and for example, a method of determining the concentration by titration using hydrochloric acid can be used.

The organic solvent may be any one which dissolves the polycarbonate oligomer. Examples thereof include chlorinated solvents such as methylene chloride, dichloroethane, chloroform, chlorobenzene and carbon tetrachloride, and cyclic oxy compounds such as dioxane. In the present invention, chlorinated solvents are preferable, and methylene chloride is particularly preferably used in view of solubility of the polycarbonate oligomer. In addition to the organic solvents exemplified above, a solvent such as an alkane or the like called a poor solvent may be used as long as the solubility of the polycarbonate oligomer is not lowered.

One kind of organic solvent may be used alone, or two or more kinds may be mixed and used.

Examples of the monohydric phenol used as the molecular weight modifier include phenol, p-cresol, p-tert-butylphenol, p-tert-octylphenol, p-cumylphenol and nonylphenol. Among them, p-tert-butylphenol and phenol are preferable from the standpoints of cost and ease of availability.

For the production of the polycarbonate oligomer, a polymerization catalyst such as a tertiary amine or a quaternary amine may be used if necessary. As the polymerization catalyst, TEA (triethylamine) is preferable.

As the oligomer reactor, a reactor having a tubular structure having a mixing portion in which a reactor of a continuous reaction system is used and a reaction raw material is mixed is preferably used.

Also, the oligomer reactor is installed in the building and isolated from the outside. The inside of the building is always replaced with air, and the ventilation air inside is sent to the detoxification means by a blower or the like.

The amount of the raw material supplied to the oligomer reactor in the step (2) and the reaction conditions are appropriately determined according to the scale and production amount of the apparatus.

For example, preferable conditions for producing polycarbonate oligomer of about 200 kg per hour are described below, but the present invention is not limited thereto. The flow rate F1 of the phosgene gas obtained by the step (1) is preferably 3.7 to 4.1 kg / h. The flow rate (F2) of the organic solvent such as methylene chloride is preferably 20 to 24 kg / h. The temperature of the phosgene gas is preferably in the range of boiling point (7.8 ° C) to 90 ° C of phosgene. As the alkaline aqueous solution of the bifunctional phenol, an aqueous solution of sodium hydroxide of bisphenol A is preferable and supplied in a predetermined concentration and adjusted in advance. In the sodium hydroxide aqueous solution of bisphenol A, the preferred bisphenol A concentration (a) is 12.5 to 14.0 mass%, and the preferable sodium hydroxide concentration is 5.1 to 6.1 mass%. The flow rate (F3) of the sodium hydroxide aqueous solution of bisphenol A is preferably 42 to 46 kg / h.

In the step (2), a reaction mixture containing a polycarbonate oligomer having a chloroformate group is obtained. The properties of the polycarbonate oligomer are not particularly limited, and the reaction conditions may be set so as to obtain optimum properties. However, the molecular weight measured by VPO (vapor pressure osmometry) is preferably about 600 to 5,000.

The reaction mixture containing the polycarbonate oligomer is also a mixture of an aqueous phase in which a polycarbonate oligomer is dissolved in the organic solvent and an aqueous phase containing an aqueous alkali solution. The reaction mixture is introduced into a condensation reactor and subjected to a condensation reaction to produce a polycarbonate.

After completion of the condensation reaction, the reaction solution is washed by a known method, concentrated, and pulverized to give a powdery polycarbonate, which can then be pelletized by an extruder or the like.

[Control method for continuous production of polycarbonate oligomer]

In the oligomer reactor, a predetermined amount of a phosgene gas, an aqueous alkali solution of a dihydric phenol and an organic solvent are continuously supplied. The supply pressure of the phosgene gas and the inlet pressure in the oligomer reactor are appropriately set according to the size, shape and the like of the phosgene or oligomer reactor. Usually, the supply pressure P1 of the phosgene gas is 0.4-0.5 MPaG, (P2) is 0.15 to 0.35 MPaG, and the value of the pressure difference (P1 - P2) of both is continuously operated to a differential pressure of 0.105 MPa to 0.35 MPa.

In the control method for continuously producing the polycarbonate oligomer of the present invention, the flow rate of the phosgene gas (F1), the flow rate of the solvent (F2), the flow rate of the aqueous alkali solution of the dihydric phenol compound (F3) (Mass%)] is always monitored as to whether or not the following conditions (i) and / or (ii) are satisfied, and when the condition is satisfied, the production and supply of phosgene is stopped by the automatic system And the toxic gas containing the phosgene gas in the system is transferred to the detoxifying means and rendered harmless.

(I): the flow rate of the solvent (F2 [kg / h]) supplied to the oligomer reactor, the flow rate of the alkali aqueous solution of the divalent phenol compound (F3 [kg / h]) and the concentration of the dihydric phenol compound When the value of the parameter < F2 / (F3 x a / 100) >

(Ii): the flow rate of the phosgene gas supplied to the oligomer reactor (F1 [kg / h]), the flow rate of the alkali aqueous solution of the dihydric phenol compound (F3 [kg / h]) and the concentration of the dihydric phenol compound ) &Lt; (F3 x a / 100) / F1 > becomes equal to or smaller than 1.23.

<Condition (i)>

The condition (i) is that the flow rate of the solvent (F2 [kg / h]) supplied to the oligomer reactor, the flow rate of the alkali aqueous solution of the divalent phenol compound (F3 [kg / h]) and the concentration of the dihydric phenol compound ) &Lt; F2 / (F3 x a / 100) > becomes equal to or less than 3.27. This parameter defines the balance between the solvent flow rate supplied to the oligomer reactor and the alkaline aqueous solution flow rate of the dihydric phenol compound.

Although a predetermined amount of the phosgene gas, the alkali aqueous solution of the dihydric phenol and the organic solvent are continuously supplied to the oligomer reactor, if the solvent supply amount is insufficient due to the trouble such as the solvent supply pump, the polycarbonate oligomer concentration generated in the oligomer reactor becomes high , So that polycarbonate oligomers may precipitate and block the exit of the oligomer reactor. Then, the pressure in the oligomer reactor rises, and the solvent or the oligomer raw material flows back to the phosgene reactor, and the operating voltage rises above the design pressure due to the evaporation of the solvent, and there is a risk that the phosgene leaks out of the system.

Therefore, in the present invention, from the viewpoint of safety, the flow rate of the solvent (F2 [kg / h]) supplied to the oligomer reactor, the flow rate of the aqueous alkali solution of the divalent phenol compound (F3 [kg / h] (F3 / a / 100)> of 3.27 using the parameter [a [mass%]) is less than 3.27. However, when the automatic system is frequently activated by a trouble of transient, it becomes difficult to operate efficiently. Therefore, from the viewpoint of efficiently operating after ensuring safety, It may be set to a value of <F2 / (F3 x a / 100)> of 2.52 or less, or to a value of 2.43 or less.

In general, the value of the above-mentioned parameter < F2 / (F3 x a / 100) > is preferably 3.30 to 4.60, more preferably 3.60 to 4.10 from the viewpoint of productivity and the like.

<Condition (ii)>

The condition (ii) is that the flow rate of the phosgene gas supplied to the oligomer reactor (F1 [kg / h]), the flow rate of the alkali aqueous solution of the divalent phenol compound (F3 [kg / h] (F3 x a / 100) / F1 &gt; using the parameter &lt; (F3 x a / 100) / F1 &gt; This parameter specifies the balance between the flow rate of the phosgene gas supplied to the oligomer reactor and the flow rate of the alkaline aqueous solution of the dihydric phenol compound.

Although a predetermined amount of the phosgene gas, the alkaline aqueous solution of the dihydric phenol and the organic solvent are continuously supplied to the oligomer reactor, if the supply amount of the alkali aqueous solution of the dihydric phenol is insufficient due to the trouble such as the dihydric phenol compound supply pump, There is a risk that the phosgene leaks out of the system while it is not consumed in the oligomer reactor but flows unreacted to the downstream process.

Therefore, in the present invention, from the viewpoint of safety, the flow rate of the phosgene gas (F1 [kg / h]) supplied to the oligomer reactor, the flow rate of the aqueous alkali solution of the dihydric phenol compound (F3 [kg / h] (F3 x a / 100) / F1 &gt; using the parameter a (mass%) becomes equal to or less than 1.23, the automatic system is started. However, when the automatic system is frequently activated by a trouble of transient, it becomes difficult to operate efficiently. Therefore, from the viewpoint of efficient operation after securing the safety, F3 x a / 100) / F1 > is 1.05 or less, or may be set to a value of 1.00 or less.

The value of the parameter < (F3 x a / 100) / F1 > is preferably 1.28 to 2.00, more preferably 1.40 to 1.80, from the viewpoint of productivity and the like during normal operation.

In the control method for continuous production of the polycarbonate oligomer of the present invention, the operations (a), (b) and (c) below are automatically carried out when the above conditions (i) and / It prevents harmful phosgene leakage and is harmless.

(a) The supply of chlorine and carbon monoxide in the step (1) for continuously producing the phosgene gas is stopped. This is an operation for stopping the production of the phosgene gas for the purpose of not increasing the amount of the phosgene gas in the system.

(b) stop feeding the phosgene gas to the oligomer reactor. This is an operation for preventing the leakage of phosgene because some phosgene is not consumed in the oligomer reactor and there is a possibility that the phosgene flows to the downstream process while being unreacted.

(c) The toxic gas containing the phosgene gas in the system is transferred to the detoxifying means and rendered harmless. This is an operation for detoxifying the phosgene gas in the system from the viewpoint of higher safety in addition to preventing increase and leakage of phosgene by the operations of (a) and (b) described above and blocking the system.

&Lt;

The detoxification means is a facility for detoxifying the poisonous gas containing the phosgene gas by releasing it, and known ones can be used. As specific examples, there may be mentioned a release facility for releasing, an absorption tower for bringing the toxic gas into contact with the release agent, and the like. It is also possible to use a tower-type desalting plant described in JP-A-6-319946 or JP-A-2005-305414.

For acid gases such as phosgene and chlorine, an alkaline substance is used as the release agent. The alkaline substance used as the releasing agent is not particularly limited, but sodium hydroxide and potassium hydroxide are generally used. In addition, they are usually used as an aqueous solution.

In the case where the detoxification means is a decomposition tower, the structure of the decomposition tower is not particularly limited, but as a typical example, the release is sprayed from the upper part of the column with a spray or the like through a shower to remove the harmful gas supplied from below . A filler such as a lashing ring may be filled between the discharge port of the release port and the inlet port of the gas so as to increase the contact efficiency between the release port and the gas. The number of the disposal tower is not particularly limited, and it is designed so that the toxic gas concentration in the detoxication process gas is lowered to a predetermined concentration or lower, which is preferably not detected.

The deterrent means are always operated against unpredictable events without the leakage of toxic gases. Further, the ventilation air in the building in which the oligomer reactor is installed is sent to the detoxifying means by a blower or the like to be detoxified and then released to the outside.

One preferred embodiment of the present invention will be described with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart outlining one preferred embodiment of a control method for continuous production of a polycarbonate oligomer of the present invention.

Typically, during operation, chlorine and carbon monoxide of the raw materials for producing phosgene are supplied to the phosgene reactor through the regulating valve, and phosgene gas is produced in the phosgene reactor. Since the reaction is an exothermic reaction, the phosgene reactor is cooled by cooling water.

The phosgene gas (reaction product) containing unreacted carbon monoxide is introduced into the oligomer reactor through the regulating valve. In the oligomer reactor, in addition to the phosgene gas, an alkali aqueous solution of divalent phenol (specifically, for example, an aqueous sodium hydroxide solution of bisphenol A) and an organic solvent (specifically, for example, methylene chloride) , An emulsion solution containing a polycarbonate oligomer is prepared.

Further, the control valve formed in the supply path of chlorine and carbon monoxide automatically controls these flow rates, and the regulating valve formed in the supply path to the oligomer reactor of the phosgene gas controls the supply pressure of the phosgene gas supplied to the oligomer reactor.

The phosgene gas flow rate (F1), the solvent flow rate (F2), and the alkaline aqueous solution flow rate (F3) of the dihydric phenol compound supplied to the oligomer reactor are always monitored using a flow meter. In the alkali aqueous solution of the dihydric phenol, the divalent phenol compound concentration (a) is adjusted to a predetermined concentration in advance, and the concentration (a) thereof is always monitored using a densitometer. These data are sent to the automatic control device (indicated by the dotted line in the figure) and calculated for the parameters specified by the conditions (i) and (ii) based on the data sent from the automatic control device.

When an abnormality occurs, that is, when the condition (i) and / or the condition (ii) is satisfied with respect to the parameter, the control valve formed in the supply path of chlorine and carbon monoxide from the automatic control device, The control valve formed in the supply path to the reactor, and the control valve formed in the flow path to the detoxification device are simultaneously sent (arrows in bold solid lines in the figure).

By the signal from the automatic control device, the control valve formed in the supply path of chlorine and carbon monoxide is closed to stop the supply of chlorine and carbon monoxide. Further, the control valve formed in the supply passage for the oligomer reactor of the phosgene gas is closed to stop the supply of the phosgene gas to the oligomer reactor.

The regulating valve formed in the flow path to the detoxication apparatus is normally closed during operation but is opened by a signal from the automatic control apparatus and the toxic gas containing the phosgene gas in the system is transferred to the detoxication apparatus. In the detoxification apparatus, the toxic gas containing the phosgene gas is harmless.

As described above, one preferred embodiment of the present invention has been described with reference to the drawings, but the present invention is not limited thereto. For example, although not shown in FIG. 1, each fluid supply stop valve may be formed in addition to the control valve.

Example

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples at all.

Example 1-1

(Automatic control device)

As shown in Fig. 1, the flow rate of the solvent (F2 [kg / h]) supplied to the oligomer reactor, the flow rate of the aqueous alkaline solution of the divalent phenol compound (F3 [kg / h]) and the concentration of the dihydric phenol compound ]) Or the phosgene gas flow rate F1 (kg / h) supplied to the oligomer reactor (2), when the value of the parameter < F2 / (F3 x a / 100) When the value of the parameter <(F3 x a / 100) / F1> using the alkaline aqueous solution flow rate (F3 [kg / h]) of the phenol compound and the concentration of the dihydric phenol compound (a [mass%]) The control valve formed in the supply passage for chlorine and carbon monoxide and the control valve formed in the supply passage for the oligomer reactor of the phosgene gas are closed and the control valve formed in the flow passage for the decomposition device is opened So as to control the operation of the automatic control device.

(Detoxification device)

A distillation column with a column diameter of 600 mm and a packed bed height of 10 m filled with Cascade Mini Ring (CMR) (trade name, manufactured by Matsui Machine Co., Ltd.) was used as a detoxification apparatus. In the decomposition column, an aqueous solution of sodium hydroxide having a concentration of 10% by mass was circulated at 2 m &lt; 3 &gt; / h as the release. Aqueous sodium hydroxide solution was supplied from the top of the column and toxic gas was supplied from the bottom.

(Preparation of phosgene)

As the phosgene reactor, a shell-and-tube reactor in which commercially available granular activated carbon (palm shell activated carbon pulverized with a diameter of 1.2 to 1.4 mm) was filled in the tube was used.

1.2 kg / h of carbon monoxide and 2.8 kg / h of chlorine were supplied to the phosgene reactor, and 3.9 kg / h of phosgene gas was prepared. In the shell part of the phosgene reactor, 90 ° C water was passed through to remove reaction heat.

(Preparation of polycarbonate oligomer)

As the oligomer reactor, a tubular reactor having an inner diameter of 6 mm and a length of 30 m was used. The oligomer reactor was immersed in a cooling bath at 20 占 폚. The phosgene gas was continuously supplied to the oligomer reactor from the upstream phosgene production process, and the supply pressure of the phosgene gas supplied to the oligomer reactor was set to 0.45 MPaG.

(A) obtained by dissolving bisphenol A (BPA) in a 6% by mass aqueous sodium hydroxide solution of phosgene gas, 13.5% by mass of BPA sodium hydroxide aqueous solution, methylene chloride, 25% by mass of p- A methylene chloride solution of tert-butylphenol was fed to prepare a polycarbonate oligomer solution. At this time, the supply flow rate F1 of the phosgene gas was 3.9 kg / h, the supply flow rate F3 of the aqueous BPA sodium hydroxide solution was 44 kg / h, the supply flow rate F2 of the methylene chloride was 22 kg / h, The feed rate of the methylene chloride solution of butylphenol was 0.46 kg / h. The value of F2 / (F3 x a / 100) is 3.70, and the value of (F3 x a / 100) / F1 is 1.52. The inlet pressure in the oligomer reactor was also 0.20 MPaG.

Here, the methylene chloride flow rate (F2) supplied to the oligomer reactor was lowered to 19.3 kg / h, and the value of F2 / (F3 x a / 100) was intentionally set to 3.25.

As a result, the supply of chlorine and carbon monoxide to the phosgene reactor was stopped by the automatic control device, the supply of the phosgene gas to the oligomer reactor was stopped, and the phosgene gas produced by the phosgene reactor was transferred to the detoxification apparatus. As a result of performing the component measurement on the gas discharged from the outlet of the decomposition tower, the phosgene was not detected and was harmless.

Examples 1-2

Except that the methylene chloride flow rate F2 to be supplied to the oligomer reactor was lowered to 14.9 kg / h and the value of F2 / (F3 x a / 100) was intentionally made to be 2.51 To prepare a polycarbonate oligomer.

As a result, in the same manner as in Example 1-1, the supply of chlorine and carbon monoxide to the phosgene reactor was stopped by the automatic control device, the supply of the phosgene gas to the oligomer reactor was stopped, and the phosgene produced by the phosgene reactor The gas was transferred to the detoxification unit. As a result of performing the component measurement on the gas discharged from the outlet of the decomposition tower, the phosgene was not detected and was harmless.

Example 1-3

Except that the flow rate of methylene chloride (F2) supplied to the oligomer reactor was lowered to 14.4 kg / h, and the value of F2 / (F3 x a / 100) was changed to 2.42 To prepare a polycarbonate oligomer.

As a result, in the same manner as in Example 1-1, the supply of chlorine and carbon monoxide to the phosgene reactor was stopped by the automatic control device, the supply of the phosgene gas to the oligomer reactor was stopped, and the phosgene produced in the phosgene reactor The gas was transferred to the detoxification unit. As a result of performing the component measurement on the gas discharged from the outlet of the decomposition tower, the phosgene was not detected and was harmless.

Comparative Example 1-1

An attempt was made to manufacture a polycarbonate oligomer in the same manner as in Example 1-1, except that the automatic control device was not used.

However, if not automatically controlled, the pressure in the oligomer reactor rose sharply. If this abnormal operation is continued, the reaction liquid inside the oligomer reactor is refluxed to the phosgene reactor, the methylene chloride evaporates, the pressure in the phosgene reactor is increased to break the phosgene reactor, and the phosgene leaks out of the system , This operation was stopped.

Example 2-1

The flow rate of the aqueous BPA sodium hydroxide solution (F3) supplied to the oligomer reactor was lowered to 35.5 kg / h, and intentionally the value of (F3 x a / 100) / F1 was set to 1.23 To prepare a polycarbonate oligomer.

As a result, in the same manner as in Example 1-1, the supply of chlorine and carbon monoxide to the phosgene reactor was stopped by the automatic control device, the supply of the phosgene gas to the oligomer reactor was stopped, and the phosgene produced by the phosgene reactor The gas was transferred to the detoxification unit. As a result of performing the component measurement on the gas discharged from the outlet of the decomposition tower, the phosgene was not detected and was harmless.

Example 2-2

The same procedure as in Example 2-1 was repeated except that the flow rate (F3) of the aqueous BPA sodium hydroxide solution supplied to the oligomer reactor was lowered to 30.1 kg / h, and the value of (F3 x a / 100) / F1 was 1.04 To prepare a polycarbonate oligomer.

As a result, in the same manner as in Example 2-1, the supply of chlorine and carbon monoxide to the phosgene reactor was stopped by the automatic control device, the supply of the phosgene gas to the oligomer reactor was stopped, and the phosgene produced by the phosgene reactor The gas was transferred to the detoxification unit. As a result of performing the component measurement on the gas discharged from the outlet of the decomposition tower, the phosgene was not detected and was harmless.

Example 2-3

The same procedure as in Example 2-1 was repeated, except that the flow rate (F3) of the aqueous BPA sodium hydroxide solution supplied to the oligomer reactor was lowered to 28.7 kg / h and the value of (F3 x a / 100) / F1 was 0.99 To prepare a polycarbonate oligomer.

As a result, in the same manner as in Example 2-1, the supply of chlorine and carbon monoxide to the phosgene reactor was stopped by the automatic control device, the supply of the phosgene gas to the oligomer reactor was stopped, and the phosgene produced by the phosgene reactor The gas was transferred to the detoxification unit. As a result of performing the component measurement on the gas discharged from the outlet of the decomposition tower, the phosgene was not detected and was harmless.

Comparative Example 2-1

An attempt was made to manufacture a polycarbonate oligomer in the same manner as in Example 2-1 except that the automatic control device was not used.

However, when not automatically controlled, since the flow rate of the BPA sodium hydroxide aqueous solution is small relative to the flow rate of the phosgene gas supplied to the oligomer reactor, a phosgene gas having a stoichiometric ratio or more is supplied to the oligomer reactor, This operation was stopped because it was supposed to flow into the downstream process and leak out of the system.

Industrial availability

According to the method of the present invention, a polycarbonate oligomer can be continuously produced safely. Particularly, even when an accident such as clogging of the reactor occurs due to the precipitation of oligomer by the raw material supply trouble to the oligomer reactor, the production and supply of the phosgene are stopped urgently by automatic control, and the phosgene gas The toxic gas containing the toxic gas is made harmless and the toxic gas is not leaked out of the system.

Claims (2)

(1) for continuously producing a phosgene gas containing unreacted carbon monoxide by supplying chlorine and carbon monoxide to a phosgene reactor, and a step (1) for continuously producing a phosgene gas, an alkali aqueous solution of a dihydric phenol, and an organic A process for controlling continuous production of polycarbonate oligomer comprising continuously (2) continuously supplying a solvent to an oligomer reactor to continuously prepare a reaction mixture containing a polycarbonate oligomer,
The supply of the chlorine and the carbon monoxide in the step (1) is stopped, the supply of the phosgene gas to the oligomer reactor is stopped, and the supply of the phosgene to the oligomer reactor is stopped when the following conditions (i) and / A method for controlling continuous production of a polycarbonate oligomer wherein a toxic gas containing a gas is transferred to a detoxifying means to render it harmless.
(I): the flow rate of the solvent (F2 [kg / h]) supplied to the oligomer reactor, the flow rate of the alkali aqueous solution of the divalent phenol compound (F3 [kg / h]) and the concentration of the dihydric phenol compound When the value of the parameter < F2 / (F3 x a / 100) >
(Ii): the flow rate of the phosgene gas supplied to the oligomer reactor (F1 [kg / h]), the flow rate of the alkali aqueous solution of the dihydric phenol compound (F3 [kg / h]) and the concentration of the dihydric phenol compound ) &Lt; (F3 x a / 100) / F1 > becomes equal to or smaller than 1.23. The method according to claim 1,
Wherein said detoxifying means is a control method for continuous production of polycarbonate oligomer which is a means for bringing toxic gas containing phosgene gas into contact with an alkaline aqueous solution to detoxify

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