JP3100008B2 - Manufacturing method of aromatic polycarbonate - Google Patents

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 a high-quality aromatic polycarbonate without coloring.

[0002]

2. Description of the Related Art In recent years, aromatic polycarbonates have been widely used in many fields as engineering plastics having excellent heat resistance, impact resistance and transparency. Various studies have hitherto been made on the production method of the aromatic polycarbonate, and among them, an aromatic dihydroxy compound, for example, 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A) and phosgene have been studied. Has been industrialized.

However, in this interfacial polycondensation method, toxic phosgene must be used, and the apparatus is corroded by by-produced hydrogen chloride and sodium chloride, and chlorine-containing compounds such as methylene chloride used in large quantities as a solvent. In addition, there were problems such as difficulty in separating impurities such as sodium chloride and residual methylene chloride which adversely affect the physical properties of the polymer.

On the other hand, as a method for producing an aromatic polycarbonate from an aromatic dihydroxy compound and a diaryl carbonate, for example, a melting method in which bisphenol A and diphenyl carbonate are transesterified in a molten state has been known for a long time. Unlike the interfacial polycondensation method, the melting method has advantages such as not using a solvent, but has a problem that the produced polycarbonate tends to be colored because it must be reacted under high temperature and high vacuum.

[0005] It has been pointed out that this coloring in the melting method is closely related to the material used for the reactor, and it has been known that coloring cannot be avoided when a stainless steel reactor is used. . For example, USP-
No. 4383092 proposes to use tantalum, nickel or chromium as a reactor material in order to prevent this coloring. Also, Japanese Patent Application Laid-Open No. 4-723
No. 27 and JP-A-4-88017 propose a reactor material containing 85% by weight or more of chromium or nickel and a reactor material containing 20% by weight or less of iron. However, these materials are not practical due to problems such as being expensive and difficult to construct.

On the other hand, a method using inexpensive stainless steel as a reactor material has also been proposed (Japanese Patent Laid-Open No. 4-73).
No. 28, JP-A-4-7329). In these methods, a method of buffing or pickling stainless steel has been proposed to prevent coloring of the aromatic polycarbonate. However, buffing and pickling are
When using stainless steel, it is a process that is usually carried out, and it is not possible to sufficiently prevent product coloring with a stainless steel reactor only by such a process, as described in US Pat. No. 4,383,092. It is clear from the description.

[0007]

SUMMARY OF THE INVENTION According to the present invention, when producing an aromatic polycarbonate by a melting method, there is no coloring even if a stainless steel reactor which is easy to take various shapes and is easy to construct is used. It was done to find a way to get the product.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, by cleaning a stainless steel reactor with a liquid composed of a certain kind of organic substance, the object thereof can be easily achieved. That you can achieve
The present invention has been completed. That is, the present invention is characterized in that, in producing an aromatic polycarbonate by reacting an aromatic dihydroxy compound and a diaryl carbonate, a stainless steel reactor washed with a liquid containing the aromatic hydroxy compound is used. This is a method for producing an aromatic polycarbonate.

When an aromatic hydroxy compound such as phenol is present in an aromatic polycarbonate, or when a polymer has many phenolic hydroxyl groups at its terminals,
It is well known that these aromatic polycarbonates are easily colored when melted by heating.However, a liquid containing an aromatic hydroxy compound such as phenol has an excellent effect of washing a stainless steel reactor. The fact that colorless aromatic polycarbonates can be obtained is unexpected in the past. Although the reason for this is not clear, the cause of the coloration of the product when using a stainless steel reactor is probably due to the adsorbed oxygen of the stainless steel, and aromatic hydroxy compounds have excellent ability to remove this adsorbed oxygen. It is thought that it is. As a method of removing adsorbed oxygen, a method of replacing the reactor with an inert gas such as nitrogen is generally used.However, when an aromatic polycarbonate is produced using a stainless steel reactor by a melting method, the replacement with the inert gas is performed. Is not enough, and a colorless product can be obtained only by the method of the present invention.

Hereinafter, the present invention will be described in detail. In the present invention, the aromatic dihydroxy compound is

HO-Ar-OH (wherein, Ar represents a divalent aromatic group).

The aromatic group Ar is preferably, for example,

## STR2 ## -Ar ¹ -Y-Ar ² - (wherein, Ar ¹ and Ar ² represents a divalent carbocyclic or heterocyclic aromatic group having each 5-30 carbon atoms each independently , Y represents a divalent alkane group having 1 to 30 carbon atoms.).

In the divalent aromatic groups Ar ¹ and Ar ² ,
Other substituents in which one or more hydrogen atoms do not adversely influence the reaction, for example, 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, It may be substituted by a cyano group, an ester group, an amide group, a nitro group or the like.

Preferred specific examples of the heterocyclic aromatic group include an aromatic group having one or more ring-forming nitrogen, oxygen or sulfur atoms. 2
The aromatic aromatic groups Ar ¹ and Ar ² are, for example, substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene,
Represents a group such as a substituted or unsubstituted pyridylene. The substituent here is as described above.

The divalent alkane group Y is, for example,

Embedded image (Wherein R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen,
C1-C10 alkyl group, C1-C10 alkoxy group, C5-C10 cycloalkyl group, C5-C10 carbocyclic aromatic group, C6-C1
Represents a carbocyclic aralkyl group of 0. k represents an integer of 3 to 11, R ⁵ and R ⁶ are individually selected for each X, and independently of one another, are hydrogen or an alkyl group having 1 to 6 carbon atoms, and X is carbon. ).

As such a divalent aromatic group Ar,
For example,

Embedded image

[0016]

Embedded image (Wherein, R ⁷ and R ⁸ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 ring carbon atoms, or A phenyl group, m and n are integers of 1 to 4, and when m is 2 to 4, each R ⁷ may be the same or different, and when n is 2 to 4, In the formula, each R ⁸ may be the same or different.)
Are shown.

Further, the divalent aromatic group Ar is represented by the following formula:

Embedded image ^Ar 1 ^{-Z-Ar 2} - (in the ^formula, Ar 1, Ar ² is as described above, Z is a single bond, or -O -, - CO -, - S -, - SO 2 -, −
Represents a divalent group such as SO—, —COO—, and —CON (R ¹ ) —. Here, R ¹ is as described above. ) May be used.

As such a divalent aromatic group Ar,
For example,

Embedded image

[0019]

Embedded image (Wherein, R ⁷ , R ⁸ , m and n are as described above).

The aromatic dihydroxy compound of the present invention may be a single kind or two or more kinds. A typical example of the aromatic dihydroxy compound is bisphenol A.

The diaryl carbonate used in the present invention is represented by the following formula:

Embedded image (In the formula, Ar ³ represents a monovalent aromatic group.)

[0022] Ar ³ represents a monovalent represents a carbocyclic or heterocyclic aromatic group, in this Ar ^3, 1 or more hydrogen atoms does not adversely affect the reaction other substituents, for example, carbon It may be substituted by 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 group, a nitro group, or the like.

Representative examples of the monovalent aromatic group Ar ³ include:
Examples include a phenyl group, a naphthyl group, a biphenyl group, and a pyridyl group. These may be substituted with one or more substituents described above.

Preferred Ar ³ is, for example,

Embedded image And the like.

Representative examples of the diaryl carbonate include the following:

Embedded image (Wherein R ⁹ and R ¹⁰ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 ring carbon atoms, or phenyl And p and q are integers of 1 to 5, and when p is 2 or more, each R ⁹ may be different, and when q is 2 or more, each R ¹⁰
May be different from each other. Or diphenyl carbonates represented by the formula (1).

Among the diphenyl carbonates,
Unsubstituted diphenyl carbonate, ditolyl carbonate, symmetric diaryl carbonates such as lower alkyl-substituted diphenyl carbonates such as di-t-butylphenyl carbonate are preferred, and diphenyl carbonate, which is a diaryl carbonate having the simplest structure, is particularly preferred. It is. These diaryl carbonates may be used alone or in combination of two or more.

In the present invention, an aromatic dihydroxy compound and a diaryl carbonate are subjected to a melt polycondensation reaction to produce an aromatic polycarbonate. The temperature and time for performing the melt polycondensation are usually 50 to 350.
° C, preferably at a temperature in the range of 100 to 280 ° C, usually in the range of 1 minute to several tens hours, preferably several minutes to 30 hours.

As the reaction proceeds, an aromatic monohydroxy compound having a skeleton forming a diaryl carbonate is produced. The rate of the removal is increased by removing the compound from the reaction system. Therefore, while performing effective stirring, nitrogen, argon, helium,
A method of introducing an inert gas such as carbon dioxide or a lower hydrocarbon gas, and removing the aromatic monohydroxy compound to be produced by accompanying these gases, and a method of performing a reaction under reduced pressure, And a method using them in combination is preferably used. In order to efficiently remove the aromatic monohydroxy compound, a thin-film reactor having a large evaporation area, a surface-renewal type self-cleaning reactor, and the like are also preferably used. The reaction between the aromatic dihydroxy compound and the diaryl carbonate can be performed in either a batch system or a continuous system.

Although the melt polycondensation reaction can be carried out without adding a catalyst, it is carried out in the presence of a catalyst, if necessary, to increase the polymerization rate. The polymerization catalyst is not particularly limited as long as it is used in this field, and hydroxides of alkali metals and alkaline earth metals such as lithium hydroxide, sodium hydroxide, potassium hydroxide, and calcium hydroxide are used. Alkali metal salts, alkaline earth metal salts, quaternary ammonium salts of hydrides of boron and aluminum such as lithium aluminum hydride, sodium borohydride, tetramethylammonium borohydride; lithium hydride, sodium hydride Hydrides of alkali metals and alkaline earth metals such as calcium hydride, alkoxides of alkali metals and alkaline earth metals such as lithium methoxide, sodium ethoxide and calcium methoxide; lithium phenoxide, sodium phenoxide, magnesium phenoxide Kishido, LiO-Ar-OLi, NaO-Ar-ONa (A
r is an aryl group) alkali metal and alkaline earth metal aryloxides; alkali metal and alkaline earth metal organic acid salts such as lithium acetate, calcium acetate and sodium benzoate; zinc oxide, zinc acetate, zinc phenoxide and the like Zinc compounds; boron compounds such as boron oxide, boric acid, sodium borate, trimethyl borate, tributyl borate, triphenyl borate;
Silicon compounds such as silicon oxide, sodium silicate, tetraalkylsilicon, tetraarylsilicon, diphenyl-ethyl-ethoxysilicon; germanium compounds such as germanium oxide, germanium tetrachloride, germanium ethoxide, germanium phenoxide; tin oxide Tin compounds such as tin compounds bonded to alkoxy or aryloxy groups, such as dialkyltin oxide, dialkyltin carboxylate, tin acetate, ethyltin tributoxide; organotin compounds;
Lead compounds such as lead oxide, lead acetate, lead carbonate, basic carbonate, alkoxide or aryloxide of lead and organic lead; onium compounds such as quaternary ammonium salt, quaternary phosphonium salt and quaternary arsonium salt Antimony compounds such as antimony oxide and antimony acetate;
Manganese compounds such as manganese acetate, manganese carbonate and manganese borate; titanium compounds such as titanium oxide, titanium alkoxide or aryloxide; zirconium compounds such as zirconium acetate, zirconium oxide, zirconium alkoxide or aryloxide, zirconium acetylacetone And the like.

When using a catalyst, these catalysts may be used alone or in combination of two or more. The amount of these catalysts to be used is usually 0.00001-1.
0% by weight, preferably in the range of 0.00003 to 0.1% by weight. Although the molecular weight of the aromatic polycarbonate produced in the present invention is not particularly limited, it is usually 1 in number average.
It is about 000 to 50,000.

Next, a liquid containing an aromatic hydroxy compound for cleaning a stainless steel reactor in the present invention will be described. The aromatic hydroxy compound of the present invention is represented by the following formula:

Embedded image Ar ³ OH (wherein, Ar ³ represents the same monovalent aromatic group as described above)
Indicated by Specific examples of preferable Ar ³ include the above-mentioned chemical formula 10 and the like. Phenol, which has the simplest structure, is particularly preferred.

In the present invention, the liquid containing the aromatic hydroxy compound is a solution containing 10 ppm of the aromatic hydroxy compound.
The liquid contains 100 to 100%, preferably 100 to 100%, more preferably 1000 to 100%.
When the content of the aromatic hydroxy compound is small, the time required for cleaning the stainless steel reactor increases.

In the liquid containing the aromatic hydroxy compound used in the present invention, there is no particular limitation on the components other than the aromatic hydroxy compound, but the components which are homogeneously mixed with the aromatic hydroxy compound under the conditions for washing treatment. Is preferred. Specific examples include the aforementioned aromatic dihydroxy compounds and diaryl carbonates, and mixtures thereof. In addition, an oligomer or polymer obtained by condensing an aromatic dihydroxy compound and a diaryl carbonate under melting usually contains an aromatic hydroxy compound, and is a preferred specific example for practicing the present invention.

In the present invention, the temperature at which the stainless steel reactor is washed with an aromatic hydroxy compound is not particularly limited, but is usually 20 to 300 ° C., preferably 10 to 300 ° C.
The range is 0 to 250 ° C. Also, the time required for the cleaning treatment is not particularly limited, and varies depending on the cleaning solution, the cleaning temperature, and the like.
~ 100 hours. The pressure for the cleaning treatment can be any of reduced pressure, normal pressure, and pressurized pressure. The cleaning treatment of the present invention can be carried out by either a batch method or a continuous method. In the case of the batch system, one or more processes are performed.

In the present invention, after the cleaning process is completed,
If necessary, a post-washing step is performed to remove the washing end solution from the reactor. The washing liquid used in the post-washing step is not particularly limited, but preferred examples include a reaction raw material such as an aromatic dihydroxy compound, a diaryl carbonate or a mixture thereof; and an oligomer obtained by condensing an aromatic dihydroxy compound and a diaryl carbonate under melting. And polymers.

In producing an aromatic polycarbonate by melt polycondensation, it is known to those skilled in the art that the aromatic polycarbonate obtained by contact with oxygen is colored. It is preferable to make contact with oxygen as much as possible during the polycondensation.
Therefore, prior to performing the cleaning treatment of the present invention, sufficiently replacing the reactor with an inert gas to remove oxygen is an effective method for obtaining a non-colored aromatic polycarbonate by a short-time cleaning treatment. is there. It is also a preferable method to deaerate the liquid containing the aromatic hydroxy compound under reduced pressure to lower the oxygen concentration in the liquid. In addition, it is also effective not to contact oxygen in the reactor after performing the washing treatment and before performing the melt polycondensation, in order to obtain a polycarbonate without coloring.

The stainless steel used as a reactor in the present invention is usually defined as a stainless steel handbook, pp. 13-21 (published by Nikkan Kogyo Shimbun, fifth edition), and usually contains 10 to 30 weight% of Cr. %, And various materials such as martensite, ferrite, austenite, and ferrite-austenite are used. Specific examples include SUS201, SUS202, SUS3
04, SUS304L, SUS316, SUS316
L, SUS347, SUS405, SUS430, SU
S403, SUS410, SUS431, SUS440
C, SUS630 and the like, but are not limited thereto. The surface of the stainless steel may be one that has been treated by pickling or buffing.

[0038]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The molecular weight was determined by gel permeation chromatography (GP
It is the number average molecular weight (hereinafter abbreviated as Mn) measured in C). The PhOH concentration in the washing solution was measured by liquid chromatography. Color is 3.2c test piece thickness by CIELAB method
The yellowness was indicated by b ^* value.

Example 1 After replacing a SUS316 stirred tank type reactor having an inner volume of 10 L with nitrogen, degassed phenol was added at 30 kg / Hr.
, And continuously washed at 150 ° C. for 2 hours under normal pressure. After removing the remaining phenol under reduced pressure, fully degassed bisphenol A and diphenyl carbonate each 3
kg and 20 mg of sodium bicarbonate were charged, and deaeration under reduced pressure and introduction of dry nitrogen were repeated several times. After the temperature was raised to 180 ° C., degassing under reduced pressure and introduction of dry nitrogen were further repeated several times, and then the temperature was raised while gradually reducing the pressure.
The polymerization reaction was carried out at 0.1 ° C. and 0.1 Torr for 1 hour. The number average molecular weight of the obtained aromatic polycarbonate was 10,200. When I made the first dumbbell by injection molding,
The b ^* value was 3.7, and no coloring was observed.

Comparative Example 1 Example 1 was repeated except that the washing operation with phenol was not performed.
Bisphenol A and diphenyl carbonate were polymerized in exactly the same manner as described above. The number average molecular weight of the obtained aromatic polycarbonate was 10,000. Injection molding 1
No. dumbbell was manufactured, the b ^* value was 4.8,
It was colored yellow.

Comparative Example 2 An aromatic polycarbonate was obtained in exactly the same manner as in Comparative Example 1, except that a 10 L reactor made of SUS304, which had been buffed with a particle size of 3 μm and washed with acid, was used. The number average molecular weight of the obtained aromatic polycarbonate was 10,100. When the first dumbbell was produced by injection molding, the b ^* value was 4.6, and it was colored yellow.

Example 2 After replacing the SUS316 stirred tank type reactor having an internal volume of 10 L with nitrogen, 10 kg of degassed phenol was charged into the reactor, and the mixture was stirred at normal pressure and 130 ° C. for 30 minutes, and then extracted. Liquid. After repeating the same operation four times, the remaining phenol was removed under reduced pressure, and then bisphenol A and diphenyl carbonate were polymerized in the same manner as in Example 1. The number average molecular weight of the obtained aromatic polycarbonate was 10,300. When a No. 1 dumbbell was prepared by injection molding, the b ^* value was 3.6 and no coloring was observed.

Example 3 After replacing the SUS316 stirred tank type reactor having an internal volume of 10 L with nitrogen, sufficiently degassed bisphenol A and diphenyl carbonate (5 kg each) were charged into the reactor.
After stirring at 180 ° C. for 4 hours, the liquid was drained. In the drained liquid, bisphenol A and diphenyl carbonate partially reacted, and the phenol concentration in the liquid was 10% by weight. After repeating the same operation four times, the remaining phenol was removed under reduced pressure, and then bisphenol A and diphenyl carbonate were polymerized in the same manner as in Example 1. The number average molecular weight of the obtained aromatic polycarbonate is 105
00. When a No. 1 dumbbell was prepared by injection molding, the b ^* value was 3.7, and no coloring was observed.

Example 4 Three stirred tank reactors made of SUS316L and SUS316L
After replacing the continuous polymerization apparatus consisting of a 304 centrifugal thin-film evaporation reactor with nitrogen, the degassed phenol was used at normal pressure,
The mixture was washed three times batchwise at 150 ° C., and then the remaining phenol was removed under reduced pressure.

Bisphenol A and diphenyl carbonate at a weight ratio of 1/1, which were sufficiently degassed, were charged into a first stirred tank reactor, and the solution reacted at 180 ° C. for 5 hours was subjected to a reaction at 23 ° C.
The solution was fed to a second stirred tank reactor controlled at 0 ° C. and 100 Torr. The liquid continuously withdrawn from the second stirred tank reactor with a residence time of 3 hours is 2
The liquid supplied to the third stirred tank reactor controlled at 10 ° C. and 10 Torr at 40 ° C., and continuously withdrawn from the third stirred tank reactor with a residence time of 3 hours is reduced to 0 ° C. at 270 ° C. The feed was continuously supplied to a centrifugal thin-film evaporative reactor controlled at a pressure of 0.1 Torr. Eight hours after the aromatic polycarbonate started to come out of the centrifugal thin film evaporation reactor, the number average molecular weight of the polymer was 8900.
Met. When a No. 1 dumbbell was prepared by injection molding, the b ^* value was 3.6 and no coloring was observed.

Example 5 The same continuous polymerization apparatus as in Example 4 was replaced with nitrogen, and sufficiently degassed bisphenol A and diphenyl carbonate at a weight ratio of 1/1 were charged into a first stirred tank reactor. The solution reacted for 5 hours at 230 ° C.
The liquid continuously withdrawn from the second stirred tank type reactor with a residence time of about 3 hours, supplied to the second stirred tank type reactor controlled at Torr pressure, was heated at 230 ° C. to 1
The liquid supplied to the third stirred tank reactor whose pressure was controlled to 0 Torr and further continuously withdrawn from the third stirred tank reactor with a residence time of 3 hours was 23
It was continuously fed to a centrifugal thin-film evaporation reactor controlled at 0 ° C. and 10 Torr. The phenol concentration in the liquid extracted from the centrifugal thin film reactor was 0.2
% By weight. After this washing operation was continued for 10 hours, the conditions of the third stirred tank reactor were changed to 240 ° C. and 10 Torr.
The conditions of the centrifugal thin-film reactor are 270 ° C, 0.1 To
Changed to rr. Five hours after changing the conditions, the number average molecular weight of the aromatic polycarbonate extracted from the centrifugal thin-film reactor was 8,800. Injection molding 1
No. dumbbell was made, the b ^* value was 3.7,
No coloring was observed.

Example 6 An aromatic polycarbonate was obtained in exactly the same manner as in Example 1 except that the material of the reactor was SUS304L. The number average molecular weight of the obtained aromatic polycarbonate is 102.
00. When a No. 1 dumbbell was prepared by injection molding, the b ^* value was 3.7, and no coloring was observed.

Example 7 An aromatic polycarbonate was obtained in exactly the same manner as in Example 1 except that o-cresol was used instead of phenol. The number average molecular weight of the obtained aromatic polycarbonate was 10,000. When a No. 1 dumbbell was prepared by injection molding, the b ^* value was 3.7, and no coloring was observed.

Example 8 An aromatic polycarbonate was prepared in the same manner as in Example 1 except that 4 kg of 1,1-bis- (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane was used instead of bisphenol A. Obtained. The number average molecular weight of the obtained aromatic polycarbonate was 9,800. When a No. 1 dumbbell was prepared by injection molding, the b ^* value was 3.8, and no coloring was observed.

[0050]

According to the present invention, high-quality aromatic polycarbonate without coloring can be produced in a stainless steel reactor.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-88017 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 64/00-64/42

Claims (3)

(57) [Claims] In producing an aromatic polycarbonate by reacting an aromatic dihydroxy compound with a diaryl carbonate, a stainless steel reactor washed with a liquid containing an aromatic hydroxy compound is used. Production method of aromatic polycarbonate. 2. A liquid containing an aromatic hydroxy compound.
Is an aromatic hydroxy compound in an amount of 1000 ppm to 100 ppm.
%.
Production method of aromatic polycarbonate. 3. A liquid containing an aromatic hydroxy compound.
After the cleaning process, wait until the melt polycondensation is performed.
Do not allow oxygen to contact the stainless steel reactor.
The aromatic polycarbonate according to claim 1 or 2,
Recipe.