JPH0912703A - Production of aromatic polycarbonate - Google Patents

Abstract

PURPOSE: To produce an aromatic polycarbonate low in gelatinization and excellent in color tone by a transesterification method. CONSTITUTION: In this method for continuously producing an aromatic polycarbonate by transesterifying an aromatic dihydroxy compound with an aromatic carbonic diester, a horizontal multiaxial reactor comprising plural revolving shafts 8 each has a stirring constitution (a) in which (1) stirring blades 3 are successively and eccentrically installed around shift centers of the opposing plural revolving shafts in such a way that the gaps between the tips of the stirring blades and the inner wall of a container and the gaps between the mutual stirring blades are narrow and a stirring constitution (b) in which (2) the opposing plural revolving shafts are equipped with plural paddles and scrapers 4 at their tips.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aromatic polycarbonate, and more particularly to a method for producing an aromatic polycarbonate in which gel formation is suppressed and the color tone is improved.

[0002]

2. Description of the Related Art Polycarbonate resins obtained by interfacial polycondensation of aromatic dihydroxy compounds and phosgene are widely used in various applications due to their excellent mechanical properties and thermal properties, but toxic phosgene is used. Therefore, there is a problem in safety, and use of methylene chloride as a solvent causes many problems such as environmental damage. Therefore, the transesterification method that does not use methylene chloride or phosgene has recently been in the limelight, but the polycarbonate resin obtained by the transesterification method is subject to heat history at high temperature for a long time, and there are a lot of gels, and the color tone is poor. I couldn't get a good one. For this reason, the polycarbonate obtained by the above method could not be used in the field where quality is required.

Recently, attempts have been made to produce a polycarbonate of excellent quality by the transesterification method, and various proposals have been made, but the present situation is still insufficient.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently producing an aromatic polycarbonate resin having less gel and excellent color tone by a transesterification method.

According to the studies by the present inventors, when a polycarbonate is produced by transesterifying an aromatic dihydroxy compound and an aromatic carbonic acid diester, the amount of the aromatic monohydroxy compound produced by the transesterification reaction decreases. It was found that the gel and the color tone deteriorate in the range where the intrinsic viscosity is 0.1 to 0.3 or more. As a result of further study of the cause, the viscosity of the reaction liquid rapidly increases with the increase in the degree of polymerization, which makes it easier for the vessel wall of the reaction vessel and the stirring shaft polymer to adhere, which causes growth / alteration due to long-term retention. However, it was found that the gel and color tone of the polymer obtained by mixing in the polymerization solution deteriorated.

Therefore, it is necessary to use a reactor which does not have a dead space which causes polymer retention in the latter polymerization region where the viscosity of the reaction solution increases. Further, from the viewpoint of economy, it is necessary to use a reactor having a large holdup and a high productivity per unit volume. Conventionally, as a method for producing polycarbonate, a method of connecting reactors of different types connected in series has been proposed, but from the above viewpoint, there is still no sufficient latter-stage polymerization tank.

For example, Japanese Unexamined Patent Publication No. 2-153923 proposes a combination of a thin film evaporator and a horizontal stirring tank, but the thin film evaporator cannot hold a large hold-up and has a high viscosity. As the temperature rises, the polymer adheres to the rotating shaft and stays there, thus deteriorating the quality of the polymer. In addition, in a horizontal reactor having a stirring center below the center of the container as illustrated, a liquid surface is generated, and the gas phase and the liquid phase are clearly separated inside the reactor, and the organic matter attached to the gas phase part is also separated. The quality of the polymer is inferior because it cannot be scraped off. In addition, as for the prevention of the retention of the polymer around the stirring shaft and the stirring blade due to the increase in the viscosity of the reaction solution, the measures are insufficient, and the quality of the polymer becomes poor.

Further, Japanese Patent Laid-Open No. 63-23926 proposes to use a twin-screw vent type kneading extruder for the late polymerization, but it is expensive and insufficient in terms of productivity.

[0009]

The present inventors have arrived at the present invention as a result of extensive studies to solve these problems.
That is, in the present invention, one or more rigid stirring tanks and one or more horizontal reaction tanks are arranged in series, and the aromatic dihydroxy compound and the aromatic carbonic acid diester are transesterified to continuously produce an aromatic polycarbonate. In the way
At least one of the horizontal reaction tanks has a plurality of rotary shafts that rotate in the same direction in synchronism with each other, and (1) a plurality of rotary shafts 8 facing the disk-shaped stirring plate 3 to each of the rotary shafts. And (2) a stirring configuration in which the tip of the stirring plate 3 is installed with a narrow gap with respect to the inner wall of the container and the mutual stirring plates 3 in order to be eccentrically mounted in the same direction around the axis of A plurality of paddles 7 are attached to the plurality of rotating shafts 8 and scrapers 4 having a length substantially corresponding to the distance between the paddles are attached to the tips of the plurality of rotating shafts 8. A horizontal multiaxial reactor having a structure in which the paddle 7 attached to it and the stirring configuration (b) installed so as to pass through in close proximity to the space formed by the scraper 4 are arranged in axial combination is used. Aromatic poly characterized by Is a Boneto method of manufacturing.

In the present invention, the aromatic dihydroxy compound and the aromatic carbonic acid diester are reacted in at least one rigid stirring tank to form a prepolymer having an intrinsic viscosity of 0.1 to 0.3. Supply to horizontal multi-axis reactor,
It is possible to produce a gel having an intrinsic viscosity of 0.3 to 0.7 and an aromatic polycarbonate having a good color tone. A prepolymer having an intrinsic viscosity of 0.1 to 0.3 can be reacted in a horizontal uniaxial reactor and then further polymerized in the horizontal multiaxial reactor.

The horizontal multiaxial reactor used in the present invention preferably has a stirring blade having a specific structure.
That is, the disk-shaped stirring plates 3 are sequentially eccentrically mounted in the same direction around the axes of the plurality of opposed rotating shafts 8, and the tips of the stirring plates 3 are closely spaced from the inner wall of the container and the mutual stirring plates 3. And a stirring structure (a) installed with a plurality of paddles 7 on a plurality of rotating shafts 8 facing each other, and a scraper 4 having a length substantially corresponding to the interval between the paddles 7 attached to the tip of the paddles 7. The stirring structure (b) installed so as to pass close to the inner wall and to pass close to the space formed by the rotating shaft 8 and the paddle 7 and the scraper 4 attached to the rotating shaft 8 is arranged in the axial direction. It is a stirring blade having a structure arranged in combination with.

The stirring structure (a) has a function of forcibly scraping off the polymer on the container wall and a function of transferring the reaction liquid in the axial direction. Further, since the stirring plate 3 is formed in a disc shape, it has a feature that a wide liquid film is not formed in the same plane.

The stirring structure (b) has a forced scraping function and a liquid film forming function, which are superior to those of the stirring structure (a), but has a characteristic that the axial liquid feeding function of the reaction liquid is inferior.

Therefore, in the present invention, the stirring structure (a) having an excellent liquid feeding function is arranged on the side of the reaction liquid supply section 1 and thereafter, the stirring structure (b) is arranged axially to the polymer extraction section 6. Preferably. The polymer extraction section 6 may be provided with a stirring structure (a), or the stirring structure (a) may be optionally provided between the stirring structures (b) for the purpose of enhancing the liquid transfer inside the horizontal multiaxial reactor. It can also be arranged.

In the present invention, the vacuum suction unit 2 is preferably installed above the stirring structure (a). By doing so, it is possible to prevent the polymer from being drawn into the vacuum system and the resulting blockage.

In the present invention, when the reaction solution has a high viscosity,
It is extremely effective to install the extracting screw 5 in the polymer extracting portion 6 in the vicinity of the stirring structure (b). By doing so, the amount of extracted liquid corresponding to the amount of supplied liquid is secured, and the stability of operation is improved.

The L / D of the horizontal multiaxial reactor of the present invention is not particularly limited, but generally 1 to 10, preferably 2 to 6 is used.

The smaller the clearance between the stirring blade and the inner wall of the vessel and the clearance between the stirring blades of the horizontal multi-screw reactor of the present invention, the more effective the scraping efficiency is. However, it is usually 2 to 50 mm in relation to the working accuracy. Used.

When carrying out continuous polymerization of polycarbonate by using the apparatus having the above-mentioned constitution, the liquid is continuously injected from the reaction liquid supply section and is uniformly transferred to the inner wall of the container while being axially transferred by the stirring constitution (a). A film is formed and the reaction is accelerated. At this time, the stirring shaft provided with the stirring configurations (a) and (b) is gradually driven by a motor, preferably 1 to 50 rp.
They are rotated in the same direction at a rotation speed of m. The reaction liquid having the increased viscosity is further promoted to be polymerized by the stirring constitution (b) having further excellent liquid film forming property and scraping property, and moves toward the outlet due to the liquid head difference. The polymer is extracted by the screw 5 and discharged out of the system.

When the continuous polymerization of polycarbonate is carried out according to the present invention as described above, not only the reaction is carried out in a very short time, but also the wall surface of the gas phase portion which is not immersed in the reaction solution is coated and renewed by the reaction solution. As a result, heat deterioration products are not generated on the wall surface. In addition, even if the viscosity of the reaction liquid increases, the polymer attached to the stirring shaft and the stirring blade is forcibly scraped off, so that no thermal deterioration product is generated and a high quality polymer can be obtained for a long period of time. Have advantages.

In the present invention, when the horizontal multiaxial reactor is used in a wide range of polymerization degree, it is preferable to divide the heating jacket into a plurality of parts and operate the inlet side at a temperature lower than that of the outlet side. In this case, the temperature difference is 10 to 100 ° C, preferably 10 to 50 ° C.

The aromatic dihydroxy compound used in the present invention is not particularly limited, but for example, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2, 2-bis (4
-Hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis (4-hydroxy-t-butylphenyl) propane, etc. Bis (hydroxyaryl) alkanes, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1
-Bis (hydroxyaryl) cycloalkanes such as bis (hydroxyphenyl) cyclohexane, 4,4 '
-Dihydroxyaryl ethers such as dihydroxydiphenyl ether, dihydroxyaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide, dihydroxyaryl sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-
Dihydroxyaryl sulfones such as dihydroxydiphenyl sulfone and the like and mixtures thereof are used. In particular, 2,2-bis (4-hydroxyphenyl) propane is preferable, and those containing 2 to 20 mol% of other components in this are also preferably used.

Examples of the aromatic carbonic acid diester used in the present invention include optionally substituted esters such as aryl groups having 6 to 10 carbon atoms and aralkyl groups. Specific examples include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate and the like.

In producing the polycarbonate according to the present invention, the aromatic carbonic acid diester is 1.00 to 1.30 mol, preferably 1.005 to 1.10 mol, per 1 mol of the aromatic dihydroxy compound. Used in an amount of.

In the present invention, when a polycarbonate is produced by the transesterification reaction of the aromatic dihydroxy compound and the aromatic carbonic acid diester as described above, a polymerization catalyst may be used to accelerate the polymerization rate.

As the polymerization catalyst, an alkali metal compound,
At least one catalyst selected from the group consisting of alkaline earth metal compounds and nitrogen-containing basic compounds can be used.

As the alkali metal compound, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate , Sodium stearate, potassium stearate, lithium stearate, sodium salt of bisphenol A, potassium salt, lithium salt, sodium benzoate, potassium benzoate, lithium benzoate and the like.

Examples of the alkaline earth metal compound include calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, calcium carbonate, barium carbonate and carbonic acid. Examples thereof include magnesium, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, and strontium stearate.

Examples of the nitrogen-containing basic compound include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, trimethylbenzylammonium hydroxide, trimethylamine, triethylamine, dimethylbenzylamine, triphenylamine and the like.

Other polymerization catalysts include alkali metal and alkaline earth metal salts of hydroxides of boron and aluminum, quaternary ammonium salts, alkoxides of alkali metals and alkaline earth metals, alkali metals and alkaline earth metals. Metal organic acid salts, zinc compounds, boron compounds,
Although catalysts used for usual esterification reaction and transesterification reaction of silicon compounds, germanium compounds, organotin compounds, lead compounds, osmium compounds, antimony compounds, zirconium compounds, etc. can be used, It is not limited to. When using a catalyst, you may use only 1 type and may use it in combination of 2 or more type.

The amount of these catalysts used is 0.0000001 to 1% by weight based on the aromatic dihydroxy compound as a raw material,
The range is preferably 0.000001 to 0.5% by weight, more preferably 0.00001 to 0.1% by weight.

In the transesterification reaction of the aromatic dihydroxy compound and the aromatic carbonic acid diester of the present invention, the aromatic monohydroxy compound produced by stirring with heating under an inert gas atmosphere is distilled as is conventionally known. It is done by letting out. The reaction temperature is usually in the range of 120 to 350 ° C., and the system decompression degree is 10 to 0.1 Torr in the latter stage of the reaction.
The reaction is completed by facilitating the distillation of the aromatic monohydroxy compound produced by increasing the ratio to r.

An example of the present invention is shown in FIGS. In the figure,
(A) is a stirring configuration (a), (b) is a stirring configuration (b), 1
Is a reaction solution supply unit, 2 is a vacuum suction unit, 3 is a stirring plate, 4 is a scraper, 5 is an extraction screw, 6 is an extraction unit, 7 is a paddle, and 8 is a rotating shaft.

[0034]

EFFECTS OF THE INVENTION According to the present invention, in the production of a polycarbonate resin, by using a specific reactor having a small dead space, it is possible to transesterify a polycarbonate having a good hue with a suppressed branching of a polymer and a small amount of gel. It can be produced using a reaction.

[0035]

The present invention will be described below in detail with reference to examples. Unless otherwise specified,% and parts in the examples are% by weight.
Or parts by weight. In the following examples, the physical properties of polycarbonate were measured as follows.

Intrinsic viscosity: A 0.7 g / dl methylene chloride solution was measured using an Ubbelohde viscometer.

Pellet color: Measured with a color difference meter manufactured by Nippon Denshoku Kogyo.

[Example 1] Diphenyl carbonate was charged into a melting tank equipped with a stirrer at a ratio of 1.01 mol to 1 mol of 2,2-bis (4-hydroxyphenyl) propane, and the mixture was purged with nitrogen and dissolved at 150 ° C. The melted mixture
It was transferred to a raw material storage tank kept at 50 ° C.

Next, a rectification column is provided and the internal temperature is 180 ° C.
The molten mixed solution was continuously supplied to a rigid stirring tank whose internal pressure was maintained at 30 Torr, and 0.00002 was added to 1 mol of 2,2-bis (4-hydroxyphenyl) propane.
Equivalent amount of bisphenol A disodium salt (0.0000
(Corresponding to 12 parts by weight) was continuously supplied as a polymerization catalyst, and the reaction was carried out while removing the produced phenol from the rectification column.

The obtained reaction product was continuously supplied to a rigid stirring tank equipped with another rectification column having an internal temperature of 250 ° C. and an internal pressure of 10 Torr, and further reacted while distilling phenol. Was continued, and the obtained reaction product was continuously extracted using a gear pump. As a result, a prepolymer having an intrinsic viscosity of 0.20 was obtained.

Then, the prepolymer is heated to an internal temperature of 270 ° C.
Phenol generated was continuously fed to a horizontal biaxial reactor (shown in FIGS. 1 and 2) equipped with seven paddle units each having a scraper whose internal pressure was maintained at 1 Torr, while stirring at a stirring speed of 15 rpm. By further polymerizing while removing it to the outside, a polycarbonate having an intrinsic viscosity of 0.50 was continuously obtained. The pellet color of the obtained polycarbonate was L = 64.1 and b = −0.2, and was 0.
100 insoluble in methylene chloride present in 5 kg
The number of micro gels having a size of μ or less (referred to as micro gel) was 5, which was good.

[Example 2] As a polymerization catalyst, 0.1 mol of 2,2-bis (4-hydroxyphenyl) propane was used.
000002 equivalents of bisphenol A disodium salt (corresponding to 0.0000012 parts by weight) and 0.0001 equivalents of tetramethylammonium hydride (0.00
(Equivalent to 004 parts by weight) was used and the same operation as in Example 1 was carried out to obtain a polycarbonate having an intrinsic viscosity of 0.94.
The pellet color of the obtained polycarbonate is L = 6.
3.5, b = 0.4, and there were two microgels.

[Comparative Example] Example was carried out except that a horizontal biaxial reactor having a gas phase portion at the upper part and equipped with lattice-shaped stirring blades rotating in opposite directions was used instead of the horizontal reactor of Example 1. The same operation as in Example 1 was carried out to obtain a polycarbonate having an intrinsic viscosity of 0.50. The pellet color of the obtained polycarbonate was L = 62.5 and b = 1.5, and the number of microgels was 30, which was inferior in quality.

[Brief description of the drawings]

FIG. 1 shows an example of a cross section of a horizontal multiaxial reactor used in the present invention.

FIG. 2 shows an example of the external appearance of a horizontal multiaxial reactor used in the present invention.

[Explanation of symbols]

 1: Reaction liquid supply part 2: Vacuum suction part 3: Stirrer plate 4: Scraper 5: Extraction screw 6: Extraction part 7: Paddle 8: Rotating shaft M: Motor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Sawaki 2-1, Hinodecho, Iwakuni-shi, Yamaguchi Prefecture Iwakuni Research Center, Teijin Limited

Claims (9)

[Claims] 1. An aromatic polycarbonate is continuously produced by transposing an aromatic dihydroxy compound and an aromatic carbonic acid diester by arranging at least one rigid stirring tank and at least one horizontal reaction tank in series. In the above method, at least one of the horizontal reaction tanks has a plurality of rotating shafts that rotate in the same direction in synchronization, and (1) a plurality of disc-shaped stirring plates are provided to face each of the rotating shafts. (A), in which the agitating plate is installed while being eccentrically mounted in the same direction around the axis of the rotating shaft, and the tip of the agitating plate is installed with a narrow gap between the inner wall of the container and the agitating plates of each other, (2) A plurality of paddles and scrapers each having a length substantially corresponding to the distance between the paddles are attached to a plurality of opposing rotary shafts, and the scrapers pass near the inner wall of the container and are attached to the rotary shafts and the opposing rotary shafts. Padd Stirrer configuration (b) installed to pass close to the space formed by the ruler and scraper
A method for producing an aromatic polycarbonate, which comprises using a horizontal multiaxial reactor having a structure in which and are combined in the axial direction. 2. The horizontal multiaxial reactor is a horizontal multiaxial reactor having a structure in which a stirring structure (a) is provided on the side of a reaction solution supply section and a vacuum suction section is installed above it. The manufacturing method according to claim 1. 3. The production method according to claim 1, wherein a withdrawal screw is installed in the withdrawal portion of the polymer of the horizontal multiaxial reactor in the vicinity of the stirring structure (b). 4. The production method according to claim 1, wherein a stirring structure (a) is provided in the vicinity of the polymer withdrawal part of the horizontal multiaxial reactor. 5. The heating jacket of the horizontal multiaxial reactor is divided into two or more parts, and the inlet side is 10 to 100 ° C. higher than the outlet side.
The manufacturing method according to claim 1, which is operated at a low temperature. 6. An aromatic dihydroxy compound and an aromatic carbonic acid diester are reacted in at least one rigid stirring tank to form a prepolymer having an intrinsic viscosity of 0.1 to 0.3,
The production method according to claim 1, wherein the prepolymer is supplied to a horizontal multiaxial reaction tank to obtain an aromatic polycarbonate having an intrinsic viscosity of 0.3 to 0.7. 7. The aromatic dihydroxy compound is 2,2-
The production method according to claim 1, which is bis (4-hydroxyphenyl) propane. 8. The aromatic carbonic acid diester is at least one selected from the group consisting of diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate and bis (diphenyl) carbonate. The manufacturing method according to any one of claims 1 to 7. 9. The production method according to claim 1, wherein the catalyst is at least one selected from the group consisting of alkali metal compounds, alkaline earth metal compounds and nitrogen-containing basic compounds.