JP5320905B2 - Method for producing aromatic polycarbonate resin - Google Patents

Description

  The present invention relates to a method for producing an aromatic polycarbonate resin, and more specifically, an aromatic polycarbonate for obtaining products of different grades having different viscosity average molecular weight (Mv) and degree of branching by switching operation by changing reaction conditions of the transesterification method. The present invention relates to a method for producing a resin.

  The aromatic polycarbonate resin is produced by polycondensation of an aromatic dihydroxy compound and a carbonic acid diester in a molten state by the transesterification method in the presence of a catalyst, and desorbing by-product phenols. When obtaining different grades of products with different viscosity average molecular weights (Mv) and degrees of branching, a switching operation is performed to change the reaction (polycondensation) conditions in a series of processes using one manufacturing facility. . For example, when a switching operation from a product with a large Mv to a product with a small Mv is performed, a period until a steady state (a state in which a standard product of a product with a small Mv is obtained by eliminating the influence of the previous reaction condition) How to shorten is important from the viewpoint of production efficiency.

As a method for producing an aromatic polycarbonate resin mentioned in the above switching operation, the number of fish eyes of the aromatic polycarbonate resin is traced, and based on the change, the timing of the cleaning operation of the gas phase portion of the reactor is determined. An improved method has been proposed (Patent Document 1).
JP 2007-31621 A

  According to the above method, it is possible to appropriately determine the timing of the washing operation of the gas phase portion of the reactor, and it is possible to efficiently produce an aromatic polycarbonate resin having a small number of fish eyes and excellent hue, but switching operation No consideration is given to how to shorten the period until the steady state is reached after performing.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain a different grade product having different viscosity average molecular weight (Mv) or degree of branching by switching operation by changing reaction conditions of the transesterification method. When the aromatic polycarbonate resin is manufactured, the period until the steady state is reached after the switching operation is shortened, and the aromatic polycarbonate resin having a small number of fish eyes and excellent hue can be efficiently manufactured. Another object of the present invention is to provide a method for producing an aromatic polycarbonate resin.

  That is, the first gist of the present invention is that after producing the polycarbonate resin A having the viscosity average molecular weight Ma, the production conditions are changed, and the viscosity average molecular weight Mb is smaller than the viscosity average molecular weight Ma using the same production equipment. A polycarbonate resin production method for producing a polycarbonate resin B, the production method comprising a polycondensation step in which an ester exchange reaction between an aromatic dihydroxy compound and a carbonic acid diester compound is performed, and the resulting aromatic polycarbonate resin in a molten state And at least a purification step of removing foreign substances by passing the polymer filter through a melt extruder. When obtaining the polycarbonate resin A, the polymer filter uses a polymer filter having a large opening diameter to obtain the polycarbonate resin B. Is a polymer filter with a smaller opening diameter When switching from polycarbonate resin A to polycarbonate resin B, switch to a polymer filter with a small opening diameter, the number of fish eyes 2 hours before switching, and the number of fish eyes 1 hour before switching The difference is 10 or less. The method lies in a method for producing an aromatic polycarbonate resin.

  The second gist of the present invention is that after the polycarbonate resin C having the branching degree Nc is manufactured, the manufacturing conditions are changed and the branching degree Nd is smaller than the branching degree Nc using the same manufacturing equipment. A polycarbonate resin production method for producing a polycarbonate resin D, the production method comprising a polycondensation step for performing an ester exchange reaction between an aromatic dihydroxy compound and a carbonic acid diester compound, and the resulting aromatic polycarbonate resin in a molten state And at least a purification step of removing foreign matters by passing the polymer filter through a melt extruder. When obtaining a polycarbonate resin C, the polymer filter uses a polymer filter having a large opening diameter to obtain a polycarbonate resin D. Use a polymer filter with a smaller aperture. When switching from the polycarbonate resin C to the polycarbonate resin D, the polymer filter is switched to a small opening diameter, and the difference between the number of fish eyes 2 hours before the switching and the number of fish eyes 1 hour before the switching is 10 It exists in the manufacturing method of aromatic polycarbonate resin characterized by the following.

  According to the present invention, an aromatic polycarbonate resin having a small number of fish eyes and an excellent hue can be efficiently produced in different grades having different viscosity average molecular weights (Mv) and degrees of branching.

  Hereinafter, the present invention will be described in detail. In the present invention, an aromatic dihydroxy compound and a carbonic acid diester are used as raw materials.

  As aromatic dihydroxy compounds, 2,2-bis (4-hydroxyphenyl) propane (also known as bisphenol A), 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane (also known as tetrabromobisphenol) A), bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) octane 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis (3-tert-butyl-4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5) -Dimethylphenyl) propane, 2,2-bis (3-bromo-4-hydroxyphenyl) propane, 2,2-bis (3,5 Dichloro-4-hydroxyphenyl) propane, 2,2-bis (3-phenyl-4-hydroxyphenyl) propane, 2,2-bis (3-cyclohexyl-4-hydroxyphenyl) propane, 1,1-bis (4 -Hydroxyphenyl) -1-phenylethane, bis (4-hydroxyphenyl) diphenylmethane, 2,2-bis (4-hydroxyphenyl) -1,1,1-trichloropropane, 2,2-bis (4-hydroxyphenyl) ) -1,1,1,3,3,3-hexachloropropane, 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane and the like bis (hydroxyaryl) ) Alkanes; 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cycl Hexane, bis (hydroxyaryl) cycloalkanes such as 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9- Cardio structure-containing bisphenols such as bis (4-hydroxy-3-methylphenyl) fluorene; dihydroxydiaryl ethers such as 4,4′-dihydroxydiphenyl ether and 4,4′-dihydroxy-3,3′-dimethyldiphenyl ether; 4 , 4′-dihydroxydiphenyl sulfide, dihydroxydiaryl sulfides such as 4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfide; 4,4′-dihydroxydiphenyl sulfoxide, 4,4′-dihydroxy-3,3 ′ -Dimethyldiphenyl sulfoxide, etc. Dihydroxy diaryl sulfoxides; dihydroxy diaryl sulfones such as 4,4′-dihydroxydiphenyl sulfone, 4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfone; hydroquinone, resorcin, 4,4′-dihydroxydiphenyl, etc. Can be mentioned. Among these, bis (4-hydroxyphenyl) alkanes are preferable, and bisphenol A is particularly preferable from the viewpoint of impact resistance. Furthermore, for the purpose of enhancing flame retardancy, a compound in which one or more tetraalkylphosphonium sulfonates are bonded to the above aromatic dihydroxy compound can also be used. These aromatic dihydroxy compounds may be used in combination of two or more.

  Examples of the carbonic acid diester include compounds represented by the following general formula (1).

  Here, in the general formula (1), A ′ is a linear, branched or cyclic monovalent hydrocarbon group having 1 to 10 carbon atoms which may be substituted. Two A ′ may be the same or different from each other. In addition, as a substituent on A ′, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a phenyl group, a phenoxy group, a vinyl group, a cyano group, an ester group, an amide Examples include a group and a nitro group.

  Specific examples of the carbonic acid diester include substituted diphenyl carbonates such as diphenyl carbonate and ditolyl carbonate, and dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, and di-t-butyl carbonate. Among these, diphenyl carbonate (hereinafter sometimes abbreviated as DPC) and substituted diphenyl carbonate are preferable. These carbonic acid diesters can be used in combination of two or more.

  The carbonic acid diester may be partially substituted with dicarboxylic acid or dicarboxylic acid ester, and the ratio is usually 50 mol% or less, preferably 30 mol% or less. Examples of typical dicarboxylic acid or dicarboxylic acid ester include terephthalic acid, isophthalic acid, diphenyl terephthalate, and diphenyl isophthalate. When substituted with such a dicarboxylic acid or dicarboxylic acid ester, a polyester carbonate is obtained.

  Carbonic acid diesters (including the above-mentioned substituted dicarboxylic acids or dicarboxylic acid esters; the same applies hereinafter) are used in excess with respect to the aromatic dihydroxy compound. That is, the ratio (molar ratio) of the carbonic acid diester to the aromatic dihydroxy compound is usually 1.00 to 1.30, preferably 1.01 to 1.20, and more preferably 1.05 to 1.20. When the molar ratio is excessively small, the terminal hydroxyl groups of the resulting aromatic polycarbonate increase, and the thermal stability of the resin tends to deteriorate. If the molar ratio is excessively large, the transesterification reaction rate decreases, and it becomes difficult to produce an aromatic polycarbonate having a desired molecular weight, and the residual amount of carbonic acid diester in the resin increases. It may cause odors during molding or when it is used as a molded product. Therefore, the amount of terminal hydroxyl groups is preferably 100 ppm or more. By setting it as the amount of such a terminal hydroxyl group, the fall of molecular weight can be suppressed and a color tone becomes more favorable.

  Generally, a polycarbonate having a desired molecular weight and terminal hydroxyl group amount can be obtained by adjusting the mixing ratio of the carbonic acid diester and the aromatic dihydroxy compound or adjusting the degree of vacuum during the reaction. As a more aggressive method, there is a well-known adjustment method in which a terminal terminator is added separately during the reaction. In this case, examples of the terminal terminator include monohydric phenols, monovalent carboxylic acids, and carbonic acid diesters. The amount of terminal hydroxyl groups greatly affects the thermal stability, hydrolysis stability, color tone, etc. of the product polycarbonate. The amount of terminal hydroxyl groups is usually 1,000 ppm or less, preferably 700 ppm or less in order to give practical physical properties although it depends on the use.

The transesterification catalyst is not particularly limited, but an alkali metal compound and / or an alkaline earth metal compound is preferable. In addition, a basic compound such as a basic boron compound, a basic phosphorus compound, a basic ammonium compound, or an amine compound can be used in combination. Among these transesterification catalysts, alkali metal compounds are preferable from a practical viewpoint. These transesterification catalysts may be used in combination of two or more. The amount of the transesterification catalyst used is usually 1 × 10 ⁻⁹ to 1 × 10 ⁻¹ mol, preferably 1 × 10 ⁻⁷ to 1 × 10 ⁻³ mol, more preferably 1 to 1 mol of the aromatic dihydroxy compound. It is the range of * 10 < ^-7 > -1 * 10 <^-6> mol.

  Examples of the alkali metal compound include inorganic alkali metal compounds such as alkali metal hydroxides, carbonates and hydrogencarbonate compounds; organic alkali metal compounds such as alkali metal alcohols (or phenols) and salts with organic carboxylic acids. Can be mentioned. Here, examples of the alkali metal include lithium, sodium, potassium, rubidium, and cesium. Among these alkali metal compounds, cesium compounds are preferable, and cesium carbonate, cesium hydrogen carbonate, or cesium hydroxide is particularly preferable.

  A method for producing an aromatic polycarbonate resin includes a polycondensation step in which an ester exchange reaction between an aromatic dihydroxy compound and a carbonic acid diester compound is performed, and the obtained aromatic polycarbonate resin is passed through a polymer filter by a melt extruder. And a purification step for removing foreign substances.

  First, as a raw material preparation step, a batch, semi-batch or continuous stirring tank type apparatus is used in an inert gas atmosphere such as nitrogen or argon to prepare a raw material mixed melt. For example, when bisphenol A is used as the aromatic dihydroxy compound and diphenyl carbonate is used as the carbonic acid diester, the temperature of the melt mixing is usually 120 to 180 ° C, preferably 125 to 160 ° C.

Next, as a polycondensation step, an ester exchange reaction between the aromatic dihydroxy compound and the carbonic acid diester compound is performed. The transesterification reaction is usually carried out continuously in a multistage system of two or more stages, preferably 3 to 7 stages. Specific reaction conditions for each tank are temperature: 150 to 320 ° C., pressure: normal pressure to reduced pressure (1.01 × 10 ⁶ Pa to 1.3 Pa), and average residence time: 5 to 150 minutes.

  And in each multi-stage reactor, in order to more effectively remove the by-produced phenol out of the system as the polycondensation reaction proceeds, the reaction conditions are set to higher temperature and higher vacuum step by step. Finally, the pressure is reduced to 2 Torr (266.6 Pa) or less. Thereby, a melt polycondensation reaction can be performed while removing by-products such as aromatic hydroxy compounds. In order to prevent quality deterioration such as hue of the aromatic polycarbonate obtained, it is preferable to set the temperature and the residence time as short as possible within the above range.

  The melt polycondensation can be carried out batchwise or continuously, but the continuous method is preferred in consideration of the stability of the resin composition of the present invention. As a catalyst deactivator, a compound that neutralizes the catalyst, for example, a sulfur-containing acidic compound or a derivative formed therefrom can be used. The usage-amount of the compound which neutralizes a catalyst is 0.5-10 equivalent normally with respect to the alkali metal which the said catalyst contains, Preferably it is the range of 1-5 equivalent. In addition, the ratio of the compound that neutralizes the catalyst to the polycarbonate is usually in the range of 1 to 100 ppm, preferably 1 to 20 ppm.

  The viscosity average molecular weight of the aromatic polycarbonate resin is not particularly limited, but is usually 10,000 or more, preferably 15,000 or more.

  The polymer filter used in the purification process to remove foreign substances is a filter that filters out foreign substances present in the aromatic polycarbonate resin, and its form is generally a candle type, a pleat type, a leaf disk type, etc. Among them, a leaf disk type polymer filter is particularly preferable. The leaf disk type is usually a disk shape, and one or more layers of woven wire meshes having various wire diameters and aperture ratios are used. The types of weaving include plain weave, twill weave, plain tatami weave, twill tatami weave, and may be non-woven fabric. As the material, stainless steel such as SUS-316 or SUS-316L is usually used, but sintered metal or resin can also be used. Moreover, absolute filtration precision is 0.5-50 micrometers normally, Preferably it is 0.5-20 micrometers. In addition, as a melt extruder, although a vent type single-screw or multi-screw extruder is usually mentioned, a meshing type twin screw extruder is particularly preferable, and the screw rotation direction may be the same direction rotation or different direction rotation.

  In the present invention, a polycarbonate resin A having a viscosity average molecular weight Mb smaller than the viscosity average molecular weight Ma is produced using the same production equipment after the production of the polycarbonate resin A having the viscosity average molecular weight Ma is changed. It is a manufacturing method of resin. The viscosity average molecular weight Ma is usually 15,000 or more, preferably 20,000 or more, more preferably 23,000 or more, and the upper limit is usually 100,000. The lower limit of the viscosity average molecular weight Mb is usually 10,000, preferably 13,000, more preferably less than 15,000. And the difference of viscosity average molecular weight Ma and Mb is 1,000 or more normally, Preferably it is 2,000 or more, More preferably, it is 3,000 or more.

  In the present invention, after manufacturing the polycarbonate resin C having the branching degree Nc, the manufacturing conditions are changed, and the polycarbonate resin D having the branching degree Nd smaller than the branching degree Nc is manufactured using the same manufacturing equipment. It is the manufacturing method of the polycarbonate resin to do. The degree of branching Nc is usually 0.2 to 1 mol%, preferably 0.3 to 1 mol%, more preferably 0.4 to 1 mol%. Moreover, said branching degree Nd is 0.05-0.5 mol% normally, Preferably it is 0.1-0.5 mol%, More preferably, it is 0.2-0.5 mol%. The difference between the branching degrees Nc and Nd is usually 0.01 mol% or more, preferably 0.05 mol% or more, and more preferably 0.10 mol% or more.

  Such switching is the same as the method described in the above-mentioned JP-A-2-153925, and is performed by changing reaction conditions such as catalyst concentration, polycondensation temperature and residence time in the reactor. In the method for producing an aromatic polycarbonate resin by the transesterification method, it is difficult to completely avoid the formation of a branched structural unit during polycondensation. In particular, in a grade having a large viscosity average molecular weight (Mv), the polycondensation temperature or There is no choice but to increase the catalyst concentration, and the number of fish eyes estimated to be derived from the branched structural unit tends to increase.

  In addition, when the polymer filter to be attached to the melt extruder is selected based on the viscosity average molecular weight (Mv), when obtaining the polycarbonate resin A, the polymer filter is a polymer filter having a large opening diameter. When obtaining, a polymer filter having a smaller opening diameter is used, and when switching from polycarbonate resin A to polycarbonate resin B, a switch is made to a polymer filter having a smaller opening diameter, and the fish eye two hours before the switching is used. The difference between the number and the number of fish eyes one hour before switching is 10 or less. The reason for using a polymer filter with a large opening diameter when the Mv is high is that the pressure loss depending on the viscosity is prevented from becoming excessively large and the polymer filter is prevented from being damaged in exchange for a slight decrease in the foreign matter removal rate. It is to do. The size of the opening diameter is relative, and the opening diameter of the polymer filter specifically used is determined by the quality of the target resin (fisheye content, etc.).

  On the other hand, when the polymer filter mounted on the melt extruder is selected according to the degree of branching, the polymer filter is a polymer filter having a large opening diameter when the polycarbonate resin C is obtained, and the polycarbonate filter D when the polymer filter is obtained. A polymer filter with a smaller opening diameter is used, and when switching from polycarbonate resin C to polycarbonate resin D, the polymer filter is switched to a polymer filter with a smaller opening diameter, and the number of fish eyes 2 hours before switching, The difference from the number of fish eyes one hour before switching is 10 or less. The reason for this is that when the degree of branching is high, the melt viscosity in the low shear rate region becomes larger than when the degree of branching is small, and as a result, the same phenomenon as when the above Mv is high occurs. .

  The feature of the present invention is that, when switching from a product having a large viscosity average molecular weight (Mv) to a small product or switching from a product having a high degree of branching to a product having a small degree of branching, immediately after changing the reaction conditions, the opening diameter is small. Instead of switching to the polymer filter, as described above, the number of fish eyes of the aromatic polycarbonate resin that has passed through the polymer filter is tracked, and based on the change, the polymer filter is switched to a polymer filter having a small opening diameter.

  When switching from a product having a large viscosity average molecular weight (Mv) to a product having a small viscosity, after changing the reaction conditions and immediately switching to a polymer filter having a small opening diameter, there are the following problems. That is, when the reaction conditions were switched, the Mv of the aromatic polycarbonate resin in the reaction system became small (lower viscosity) at a relatively early time, but this occurred when a product with a large Mv before switching was obtained. The state in which the number of fish eyes has increased continues for a while and then gradually disappears. Then, the reaction system reaches a steady state. Therefore, by switching to a polymer filter having a small opening diameter, filtration becomes difficult, and as a result, the aromatic polycarbonate resin containing foreign substances is discharged from the polymer filter over a long period of time.

  On the other hand, when a polymer filter having a large opening diameter is used as it is even after changing the reaction conditions as described above, the Mv of the aromatic polycarbonate resin in the reaction system becomes small (low viscosity), resulting in foreign matter. Filtration of aromatic polycarbonate resin containing is promoted.

  When switching from a product with a high degree of branching to a product with a small degree of branching, after changing the reaction conditions and immediately switching to a polymer filter with a small opening diameter, there are the following problems. That is, when the reaction conditions are switched, the degree of branching of the aromatic polycarbonate resin in the reaction system decreases relatively early, but the fish eye produced when a product with a large degree of branching before switching is obtained. The state in which the number has increased continues for a while and gradually disappears. Then, the reaction system reaches a steady state. Therefore, by switching to a polymer filter having a small opening diameter, filtration becomes difficult, and as a result, the aromatic polycarbonate resin containing foreign substances is discharged from the polymer filter over a long period of time.

  On the other hand, when a polymer filter having a large opening diameter is used as it is even after changing the reaction conditions as described above, the degree of branching of the aromatic polycarbonate resin in the reaction system is reduced, resulting in aromatics containing foreign substances. Filtration of polycarbonate resin is promoted.

  In the present invention, when switching from a product having a large viscosity average molecular weight (Mv) or a degree of branching to a product having a small degree of branching, a polymer filter having a large opening diameter is used for a while after changing the reaction conditions. When such a state becomes longer, the removal rate of the foreign matter remains lowered, and a steady state for obtaining a product with a small Mv or a small degree of branching is not achieved.

  Therefore, in the present invention, the number of fish eyes of the aromatic polycarbonate resin that has passed through the polymer filter is tracked, and the polymer filter having a small opening diameter is switched based on the change. When the reaction conditions are changed, it changes as follows. That is, the melt viscosity of the aromatic polycarbonate resin is decreased, the pressure loss of the melt extruder is decreased, the number of fish eyes of the aromatic polycarbonate resin that has passed through the polymer filter is gradually decreased, and then becomes a substantially constant value.

  In the present invention, the time point at which the fluctuation of the fisheye number is reduced and becomes a substantially constant value can be used as the polymer filter switching time point. In addition, it is possible to obtain the polymer filter switching time in advance based on accumulated data indicating the transition of the number of fish eyes. Switching of the polymer filter can be performed by a conventional method with the supply of the melt extruder temporarily stopped. The above-mentioned “change in the number of fish eyes is reduced to a substantially constant value” means that when the number of fish eyes is measured over time, the difference between the number of fish eyes one hour ago and the current number of fish eyes is 10 Means less than or equal to the number.

  According to the present invention, an aromatic polycarbonate resin having a small number of fish eyes and an excellent hue can be efficiently produced in different grades having different viscosity average molecular weights (Mv) and degrees of branching. For the aromatic polycarbonate resin of the present invention, conventionally known additives such as other thermoplastic resins, flame retardants, impact modifiers, antistatic agents, slip agents, antiblocking agents, lubricants, depending on the application. Antifogging agents, natural oils, synthetic oils, waxes, organic fillers, and inorganic fillers can be appropriately selected and used. And the aromatic polycarbonate resin obtained by the manufacturing method of this invention is used as a film, a sheet | seat, a bottle, etc. other than a machine part, the part of an electric appliance, miscellaneous goods, etc.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. Analysis of the aromatic polycarbonate resin was performed by the following method.

(1) Viscosity average molecular weight (Mv):
By using an Ubbelohde viscometer, the intrinsic viscosity [η] at 20 ° C. in methylene chloride of an aromatic polycarbonate resin pellet (sample) is measured, and the value obtained from the following formulas (1) and (2) is meant.

[Equation 1]
ηsp / C = [η] × (1 + 0.28ηsp) (1)
[Η] = 1.23 × 10 ⁻⁴ × (Mv) ^0.83 (2)
(In the formula (2), ηsp is the intrinsic viscosity [η] measured at 20 ° C. in the methylene chloride of the sample, and C is the concentration of the methylene chloride solution. (Use a 6 g / dl solution.)

(2) Degree of branching:
The degree of branching was expressed as the ratio (mol%) of the total number of moles of the branched compound represented by the following formulas (1) to (5) with respect to 1 mole of the bisphenol A structural unit. Specifically, the content of each compound was determined as follows. That is, 1 g of aromatic polycarbonate (sample) was dissolved in 100 ml of methylene chloride, 18 ml of 28% sodium methoxide methanol solution and 80 ml of methanol were added, and 25 ml of pure water was further added, followed by stirring at room temperature for 2 hours. Completely hydrolyzed. Thereafter, 1N hydrochloric acid was added for neutralization, and the methylene chloride layer was separated to obtain a hydrolyzate. 0.05 g of the hydrolyzate was dissolved in 10 ml of acetonitrile, and the measurement was performed using reverse phase high performance liquid chromatography (HPLC). In reverse phase liquid chromatography, a mixed solvent consisting of acetonitrile and 10 mM ammonium acetate aqueous solution is used as an eluent, and the column is used under the condition that the acetonitrile / 10 mM ammonium acetate aqueous solution ratio starts from 20/80 and is gradient to 80/20. The measurement was performed at a temperature of 40 ° C. For detection, a UV detector having a wavelength of 280 nm (“SPD-6A” manufactured by Shimadzu Corporation) was used. The branched compounds represented by the following formulas (1) to (5) use “LC-MS (Agilent-1100”) manufactured by Agilent, and “NMR (AL-400)” manufactured by JEOL. Each content was calculated from each peak area relative to the peak area of bisphenol A by preparing a calibration curve of bisphenol A.

(3) Number of fish eyes:
First, an aromatic polycarbonate resin pellet dried at 130 ° C. for 5 hours was extruded at 320 ° C. to obtain a film having a width of 140 mm and a thickness of 70 μm. A single screw extruder (manufactured by Isuzu Chemical Co., Ltd.) having a diameter of 30 mm was used for the extrusion molding. Next, using an optical foreign object inspection apparatus (“GX40K” manufactured by Dia Instruments Co., Ltd.), a width selected from the center of the film (a width selected from the center of the film) 80 mm × length 1.7 m × thickness The number of fish eyes (size 50 to 500 μm) of a 70 μm film (volume 952 cm ³ ) was measured. That is, using a light amount of 800 mV, the number of fish eyes in the absorbed light amount range of 100 to 300 mV is (A), and the number of light amount ranges of 300 mV or more is (B). did. The measurement was performed twice and the average value was shown.

[Equation 2]
Number of fish eyes = (A)-(B) (3)

(4) Hue:
Aromatic polycarbonate resin pellets are dried at 120 ° C. for 5 hours and then molded using an injection molding machine (“J100SS-2” manufactured by Nippon Steel) under conditions of barrel temperature of 300 ° C. and mold temperature of 90 ° C. Thus, a sheet having a thickness of 3 mm and a side of 100 mm square was obtained. And the hue of the said sheet | seat was determined visually.

Example 1:
In a nitrogen gas atmosphere, diphenyl carbonate (DPC) and bisphenol A (BPA) were mixed at a constant molar ratio (DPC / BPA = 1.050) to prepare a raw material melt. This raw material melt was continuously supplied into the first vertical stirring reactor having a capacity of 100 L controlled at 220 ° C. and 1.33 × 10 ⁴ Pa through the raw material introduction pipe at a flow rate of 88.7 kg / hour. The liquid level was kept constant while controlling the valve opening degree provided in the polymer discharge line at the bottom of the reactor so that the average residence time was 60 minutes. At the same time as starting the supply of the raw material melt, an aqueous cesium carbonate solution was continuously supplied as a catalyst at a ratio of 1.0 μmol (as a metal amount, 2.0 μmol with respect to 1 mol of bisphenol A) with respect to 1 mol of bisphenol A.

  The reaction liquid discharged from the bottom of the reactor is continuously continuously supplied to the second and third vertical stirring reactors (capacity 100 L) and the fourth horizontal reactor (capacity 150 L), and the bottom of the fourth reactor From the polymer outlet. Next, in the molten state, this polymer was fed into a twin-screw extruder (screw diameter 0.046 m, L / D = 36) having a polymer filter installed at the die outlet, and p-toluenesulfonate (catalyst) Is continuously kneaded, extracted in a strand form from the die, and cut with a cutter to obtain high molecular weight grade (Mv: 25,500) aromatic polycarbonate resin pellets. It was.

The reaction conditions in the second to fourth reactors were the second reactor (240 ° C., 2.00 × 10 ³ Pa, 75 rpm), the third reactor (270 ° C., 66.7 Pa, 75 rpm), the second reactor, respectively. Four reactors (290 ° C., 67 Pa, 5 rpm) were used, and conditions were set for high temperature, high vacuum, and low stirring speed as the reaction proceeded. Further, during the reaction, the liquid level is controlled so that the average residence time of the second and third reactors is 60 minutes and the average residence time of the fourth reactor is 90 minutes. Phenol was also distilled off.

  In addition, as a polymer filter, a commercially available leaf disk type polymer filter (manufactured by Nagase Sangyo Co., Ltd., with a metal nonwoven fabric type (material: SUS316L) having an absolute filtration accuracy of 50 μm mounted on a center post (polymer filter) A) was used.

  The above operation was continuously performed for 1 month, and then the DPC / BPA molar ratio was gradually increased to 1.090, the supply amount of the aqueous cesium carbonate solution was halved, and the temperature of the fourth reactor was decreased, The production conditions were switched to low molecular weight grade (Mv: 15,000).

  Then, the number of fish eyes of the aromatic polycarbonate resin that passed through the polymer filter (A) was tracked every hour, and when the number of fish eyes reached a substantially constant value (140) (18 hours after switching reaction conditions). One hour after the elapse of time, the polymer filter was switched, and the production of low molecular weight grade (Mv: 15,000) aromatic polycarbonate resin pellets was continued. As a polymer filter, a commercially available leaf disk type polymer filter (manufactured by Nippon Pole Co., Ltd., a metal nonwoven fabric type (material: SUS316L) with an absolute filtration accuracy of 120 μm mounted on a center post (polymer filter B) The properties of the aromatic polycarbonate resin that passed through the polymer filter (B) were measured, the viscosity average molecular weight (Mv) was 15,100, the number of fish eyes was 24, and the hue was transparent.

Comparative Example 1:
In Example 1, after the production of the high molecular weight grade aromatic polycarbonate resin pellets, the production conditions were changed to the low molecular weight grade production conditions, and at the same time, except that the polymer filter (A) was changed to the polymer filter (B). Similarly, an aromatic polycarbonate resin was produced. In this case, until the physical properties of the aromatic polycarbonate resin that has passed through the polymer filter (B) are substantially the same as in Example 1 (Mv: 15,000, number of fish eyes: 33), the reaction conditions are changed to 92. It took time.

Example 2:
Separately, in the same manner as in Example 1, a high molecular weight (highly branched) grade (branching degree: 0.48 mol%) aromatic polycarbonate resin was continuously produced for one month, and then an aqueous cesium carbonate solution was supplied. The amount was halved and the average residence time of the fourth reactor was 120 minutes, and the production conditions were switched to low branching grades (degree of branching: 0.27 mol%, Mv: 25,600).

  Then, the number of fish eyes of the aromatic polycarbonate resin that passed through the polymer filter (A) was tracked every hour, and when the number of fish eyes reached a substantially constant value (427) (11 hours after switching the reaction conditions) One hour after the elapse of time, the polymer filter was switched, and the production of low-branching grade (degree of branching: 0.27 mol%) aromatic polycarbonate resin pellets was continued. As a polymer filter, a commercially available leaf disk type polymer filter (manufactured by Nagase Sangyo Co., Ltd., metal nonwoven fabric type (material: SUS316L) with an absolute filtration accuracy of 20 μm mounted on a center post (polymer filter B ′ The properties of the aromatic polycarbonate resin that passed through the polymer filter (B ′) were measured, the viscosity average molecular weight (Mv) was 25,500, the degree of branching was 0.27 mol%, and the number of fish eyes was 255 and the hue was transparent.

Comparative Example 2:
In Example 2, after the production of the highly branched grade aromatic polycarbonate resin pellets, the production conditions were changed to the low branch grade production conditions, and at the same time, the polymer filter (A) was changed to the polymer filter (B ′). In the same manner as above, an aromatic polycarbonate resin was produced. In this case, after switching the reaction conditions until the physical properties of the aromatic polycarbonate resin having passed through the polymer filter (B ′) are substantially the same as in Example 2 (Mv: 25,600, number of fish eyes: 263). It took 52 hours.

Claims (2)

  Manufacturing method of polycarbonate resin which manufactures polycarbonate resin B which has viscosity average molecular weight Mb smaller than viscosity average molecular weight Ma using the same manufacturing equipment after manufacturing polycarbonate resin A which has viscosity average molecular weight Ma The production method includes a polycondensation step in which an ester exchange reaction between an aromatic dihydroxy compound and a carbonic acid diester compound is performed, and the resulting aromatic polycarbonate resin in a molten state is passed through a polymer filter by a melt extruder. A polymer filter having a large opening diameter when obtaining the polycarbonate resin A, and a polymer filter having a smaller opening diameter when obtaining the polycarbonate resin B. Made to use, and When switching from polycarbonate resin A to polycarbonate resin B, switch to a polymer filter with a small opening diameter, and the difference between the number of fish eyes two hours before switching and the number of fish eyes one hour before switching must be 10 or less. A process for producing an aromatic polycarbonate resin characterized by   Manufacturing method of polycarbonate resin which manufactures polycarbonate resin D which has branching degree Nd smaller than branching degree Nc using the same manufacturing equipment after manufacturing polycarbonate resin C which has branching degree Nc The production method includes a polycondensation step in which an ester exchange reaction between an aromatic dihydroxy compound and a carbonic acid diester compound is performed, and the resulting aromatic polycarbonate resin in a molten state is passed through a polymer filter by a melt extruder. A polymer filter with a large opening diameter when obtaining the polycarbonate resin C, and a polymer filter with a smaller opening diameter when obtaining the polycarbonate resin D. Made to use and polycarbonate When switching from fat C to polycarbonate resin D, switch to a polymer filter with a small opening diameter, and the difference between the number of fish eyes 2 hours before switching and the number of fish eyes 1 hour before switching should be 10 or less. A method for producing an aromatic polycarbonate resin.