JPH0656984A - Production of aromatic polycarbonate - Google Patents

Abstract

PURPOSE:To produce a noncolored aromatic polycarbonate in a stainless steel reactor. CONSTITUTION:A stainless steel reactor is washed with a fluid containing an aromatic hydroxy compound, and an aromatic dihydroxy compound and a diaryl carbonate are reacted in this reactor to obtain the aromatic polycarbonate.

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 been conducted on the production method of the aromatic polycarbonate, and among them, aromatic dihydroxy compounds such as 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A) and phosgene Has been industrialized.

However, in this interfacial polycondensation method, toxic phosgene must be used, and hydrogen chloride and sodium chloride produced as by-products and chlorine-containing compounds such as methylene chloride used in large amounts as a solvent corrode the apparatus. However, there is a problem that impurities such as sodium chloride, which adversely affect the physical properties of the polymer, and separation of residual methylene chloride are difficult.

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. Unlike the interfacial polycondensation method, the melting method has advantages such as not using a solvent, but since the reaction must be carried out under high temperature and high vacuum, there is a problem that the produced polycarbonate is easily colored.

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 the coloring cannot be escaped when a stainless steel reactor is used. . For example, USP-
No. 4,383,092 proposes to use tantalum, nickel or chromium as a reactor material in order to prevent this coloring. In addition, Japanese Patent 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, respectively. However, all of these materials are not practical because they are 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).
28, JP-A-4-7329). In these methods, a method of buffing stainless steel or pickling it is proposed in order to prevent coloring of the aromatic polycarbonate. However, buffing and pickling
It is a process that is usually carried out when stainless steel is used, and it is not possible to sufficiently prevent product coloration in a stainless steel reactor by such a process as described in USP-4383092. It is clear from the description.

[0007]

According to the present invention, when an aromatic polycarbonate is produced by a melting method, various shapes are easily formed, and even if a stainless steel reactor which is easy to construct is used, no coloring occurs. It was designed to find a way to obtain a product.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention easily cleaned the stainless steel reactor with a liquid composed of a certain kind of organic substance to achieve its purpose. Find out that
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 an aromatic hydroxy compound is used. It is a method for producing an aromatic polycarbonate.

When an aromatic hydroxy compound such as phenol is present in the aromatic polycarbonate, or when there are many phenolic hydroxyl groups at the polymer terminal,
It is well known that these aromatic polycarbonates are easily colored when heated and melted, but a liquid containing an aromatic hydroxy compound such as phenol is excellent in the effect of cleaning a stainless steel reactor. The fact that gives an aromatic polycarbonate free of color is heretofore completely unexpected. Although the reason for this is not clear, the reason why the product is colored when a stainless steel reactor is used is probably due to the adsorbed oxygen of stainless steel, and aromatic hydroxy compounds have excellent ability to remove this adsorbed oxygen. It is thought to be because it is. As a method for removing adsorbed oxygen, usually, a method of subjecting a reactor to substitution treatment with an inert gas such as nitrogen is used, but when producing an aromatic polycarbonate using a stainless steel reactor by a melting method, substitution with an inert gas is used. This is not enough and the method according to the invention is the first to obtain a product without coloring.

The present invention will be described in detail below. In the present invention, the aromatic dihydroxy compound means the following chemical formula 1

Embedded image HO—Ar—OH (in the formula, Ar represents a divalent aromatic group).

The aromatic group Ar is preferably, for example,

Embedded image wherein —Ar ¹ —Y—Ar ² — (wherein Ar ¹ and Ar ² each independently represent a divalent carbocyclic or heterocyclic aromatic group having 5 to 30 carbon atoms). , Y represents a divalent alkane group having 1 to 30 carbon atoms)).

In the divalent aromatic groups Ar ¹ and Ar ² ,
Another substituent in which one or more hydrogen atoms do not adversely affect 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 with a cyano group, an ester group, an amide group, a nitro group or the like.

Preferred specific examples of the heterocyclic aromatic group include aromatic groups having one or more ring-forming nitrogen atoms, oxygen atoms or sulfur atoms. Two
The valent 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 substituents here are as described above.

The divalent alkane group Y is represented by the following chemical formula 3, for example.

[Chemical 3] (In the formula, R ¹ , R ² , R ³ , and R ⁴ are each independently hydrogen,
Alkyl group having 1 to 10 carbon atoms, alkoxy group having 1 to 10 carbon atoms, cycloalkyl group having 5 to 10 ring carbon atoms, carbocyclic aromatic group having 5 to 10 ring carbon atoms, and 6 to 1 carbon atoms
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 each other, hydrogen or an alkyl group having 1 to 6 carbon atoms, and X is carbon. ) Is an organic group.

As such a divalent aromatic group Ar,
For example,

[Chemical 4]

[0016]

[Chemical 5] (In the formula, 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-constituting 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 Each R ⁸ may be the same or different.)
The items shown in are listed.

Further, the divalent aromatic group Ar is represented by the following chemical formula 6

Embedded image Ar ¹ —Z—Ar ² — (wherein Ar ¹ and Ar ² are as described above, Z is a single bond, or —O—, —CO—, —S—, —SO ₂ —, −
SO -, - COO -, - CON (R 1) - represents a divalent group, such as. However, R ¹ is as described above. )

As such a divalent aromatic group Ar,
For example,

[Chemical 7]

[0019]

[Chemical 8] (In the formula, R ⁷ , R ⁸ , m and n are as described above.).

The aromatic dihydroxy compound of the present invention may be a single type or two or more types. A representative example of the aromatic dihydroxy compound is bisphenol A.

The diaryl carbonate used in the present invention is represented by the following chemical formula 9

[Chemical 9] (In the formula, Ar ³ represents a monovalent aromatic group.).

Ar ³ represents a monovalent carbocyclic or heterocyclic aromatic group, but in this Ar ³ , one or more hydrogen atoms do not adversely influence the reaction, and other substituents such as halogen. Even if it is substituted with an 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 group, a nitro group, or the like. Good.

A typical example of the monovalent aromatic group Ar ³ is:
Examples thereof include a phenyl group, a naphthyl group, a biphenyl group and a pyridyl group. These may be substituted with one or more substituents as described above.

Preferred Ar ³ is, for example,

[Chemical 10] And so on.

As typical examples of the diaryl carbonate, the following compounds 11

[Chemical 11] (In the formula, 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-constituting carbon atoms, or phenyl. Represents a group, p and q are integers from 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 is}
May be different from each other. ) And substituted or unsubstituted diphenyl carbonates.

Among these diphenyl carbonates,
Symmetrical diaryl carbonates such as unsubstituted diphenyl carbonate and lower alkyl-substituted diphenyl carbonates such as ditolyl carbonate and di-t-butylphenyl carbonate are preferable, but diphenyl carbonate having the simplest structure is particularly preferable. Is. These diaryl carbonates may be used alone or in combination of two or more.

In the present invention, an aromatic polycarbonate can be produced by subjecting an aromatic dihydroxy compound and a diaryl carbonate to a melt polycondensation reaction. The temperature and time for carrying out the melt polycondensation are usually 50 to 350.
C., preferably in the range of 100 to 280.degree. C., usually for 1 minute to several tens of hours, preferably for several minutes to 30 hours.

With the progress of the reaction, an aromatic monohydroxy compound having a skeleton for forming a diaryl carbonate is produced, and the rate thereof can be increased by removing it from the reaction system. Therefore, at the same time as performing effective stirring, an inert gas such as nitrogen, argon, helium, or carbon dioxide or a lower hydrocarbon gas is introduced to generate the aromatic monohydroxy compound, and the generated aromatic monohydroxy compound is mixed with these gases. It is preferable to use a method of removing it by entraining it, a method of carrying out the reaction under reduced pressure, a method of using these in combination, and the like. Further, 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.

The melt polycondensation reaction can be carried out without adding a catalyst, but in order to increase the polymerization rate, it is carried out in the presence of a catalyst, if necessary. The polymerization catalyst is not particularly limited as long as it is used in this field, but hydroxides of alkali metals and alkaline earth metals such as lithium hydroxide, sodium hydroxide, potassium hydroxide and calcium hydroxide. 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 , Hydrogen compounds of alkali metals and alkaline earth metals such as calcium hydride; alkali metal and alkaline earth metal alkoxides 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) such as an alkali metal and an alkaline earth metal aryloxide; lithium acetate, calcium acetate, an organic acid salt of an alkaline earth metal such as sodium benzoate; zinc oxide, zinc acetate, zinc phenoxide, etc. Zinc compounds; boron compounds such as boron oxide, boric acid, sodium borate, trimethyl borate, tributyl borate, and triphenyl borate;
Compounds of silicon such as silicon oxide, sodium silicate, tetraalkyl silicon, tetraaryl silicon, diphenyl-ethyl-ethoxy silicon; germanium compounds such as germanium oxide, germanium tetrachloride, germanium ethoxide, germanium phenoxide; tin oxide Compounds such as dialkyl tin oxide, dialkyl tin carboxylate, tin acetate, tin compounds bound to an alkoxy group such as ethyltin tributoxide or aryloxy group, tin compounds such as organotin compounds;
Lead compounds such as lead oxide, lead acetate, lead carbonate, basic carbonate, lead and organic lead alkoxides or aryloxides; quaternary ammonium salts, quaternary phosphonium salts, quaternary arsonium salts and other onium compounds Compounds of antimony 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 acetate, zirconium oxide, zirconium alkoxide or aryloxide, zirconium compounds such as zirconium acetylacetone. Examples thereof include catalysts.

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

Next, a liquid containing an aromatic hydroxy compound for cleaning the stainless steel reactor according to the present invention will be described. The aromatic hydroxy compound of the present invention is represented by the following chemical formula 12

Embedded image Ar ³ OH (In the formula, 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. Particularly, phenol, which has the simplest structure, is preferable.

In the present invention, the liquid containing an aromatic hydroxy compound means that the aromatic hydroxy compound is 10 ppm.
To 100%, preferably 100 to 100%, more preferably 1000 to 100%.
When the content of the aromatic hydroxy compound is low, the time required for cleaning the stainless steel reactor becomes long.

In the liquid containing the aromatic hydroxy compound used in the present invention, the components other than the aromatic hydroxy compound are not particularly limited, but the components which are uniformly mixed with the aromatic hydroxy compound under the washing treatment condition. Is preferred. Specific examples thereof include the above-mentioned aromatic dihydroxy compounds and diaryl carbonates, and a mixture thereof. An oligomer or polymer obtained by condensing an aromatic dihydroxy compound and a diaryl carbonate under melting usually contains an aromatic hydroxy compound, which is a preferred specific example for carrying out the present invention.

In the present invention, the temperature at which the stainless steel reactor is washed with the aromatic hydroxy compound is not particularly limited, but is usually 20 to 300 ° C., preferably 10
It is in the range of 0 to 250 ° C. Moreover, the time required for the cleaning treatment is not particularly limited, and varies depending on the liquid to be cleaned, the cleaning temperature, etc., but is usually several minutes to several hundred hours, preferably 1 minute.
~ 100 hours. The pressure for cleaning treatment may be any of reduced pressure, normal pressure and increased pressure. The cleaning treatment of the present invention can be carried out in either a batch system or a continuous system. In the case of the batch method, the treatment is carried out once or twice or more.

In the present invention, after the cleaning process is completed,
If necessary, a post-washing step for removing the washing-finished solution from the reactor is performed. The washing liquid used in the post-washing step is not particularly limited, but preferable examples include reaction raw materials such as aromatic dihydroxy compounds, diaryl carbonates or mixtures thereof; oligomers obtained by condensing aromatic dihydroxy compounds and diaryl carbonates under melting. And polymers.

It is known to those skilled in the art that the aromatic polycarbonate obtained by contact with oxygen in producing the aromatic polycarbonate by melt polycondensation is known to those skilled in the art. It is preferable to make contact with oxygen as much as possible during polycondensation.
Therefore, prior to 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 colorless aromatic polycarbonate in a short cleaning treatment. is there. It is also a preferable method to degas the liquid containing the aromatic hydroxy compound under reduced pressure to reduce the oxygen concentration in the liquid. Further, it is also effective not to bring oxygen into contact with the inside of the reactor after the washing treatment and before the melt polycondensation, in order to obtain a polycarbonate without coloring.

The stainless steel used as a reactor in the present invention is usually 10 to 30 wt% of Cr, as defined and classified in the Stainless Steel Handbook, pages 13 to 21 (published by Nikkan Kogyo Shimbun, 5th edition). %, And various types such as martensite type, ferrite type, austenite type, and ferrite / austenite type are used. As a specific example, SUS201, SUS202, SUS3
04, SUS304L, SUS316, SUS316
L, SUS347, SUS405, SUS430, SU
S403, SUS410, SUS431, SUS440
C, SUS630, etc. are mentioned, but not limited to them. The surface of stainless steel may be treated with pickling or buffing.

[0038]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto. The molecular weight is 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 liquid was measured by liquid chromatography. The color of the test piece is 3.2c according to the CIELAB method.
Measured in m, the yellowness index is given by the b ^* value.

Example 1 After replacing a stirred tank reactor made of SUS316 with an internal volume of 10 L with nitrogen, degassed phenol was added at 30 kg / hr.
Then, it was continuously washed for 2 hours under the conditions of atmospheric pressure and 150 ° C. After removing residual phenol under reduced pressure, degassed bisphenol A and diphenyl carbonate 3 each
kg and 20 mg of sodium hydrogen carbonate were charged, and deaeration under reduced pressure and introduction of dry nitrogen were repeated several times. After the temperature was raised to 180 ° C., deaeration under reduced pressure and the introduction of dry nitrogen were further repeated several times, and then the temperature was raised while gradually reducing the pressure to 275
The polymerization reaction was carried out at 0.1 Torr for 1 hour. The number average molecular weight of the obtained aromatic polycarbonate was 10,200. When injection molding was used to make No. 1 dumbbell,
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 carried out.
Bisphenol A and diphenyl carbonate were polymerized in exactly the same manner as in. The number average molecular weight of the obtained aromatic polycarbonate was 10,000. Injection molding 1
I made a No. dumbbell, and 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 was buffed with a particle size of 3 microns and pickled was used. The number average molecular weight of the obtained aromatic polycarbonate was 10,100. When injection molding was carried out to produce No. 1 dumbbell, the b ^* value was 4.6 and it was colored yellow.

Example 2 A stirring tank reactor made of SUS316 having an internal volume of 10 L was replaced with nitrogen, 10 kg of degassed phenol was charged into the reactor, and the mixture was stirred at 130 ° C. under atmospheric pressure for 30 minutes and then withdrawn. Liquor After repeating the same operation four times, residual 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 injection molding was carried out to produce No. 1 dumbbell, the b ^* value was 3.6, and coloring was not observed.

Example 3 A stirring tank reactor made of SUS316 having an internal volume of 10 L was replaced with nitrogen, and then 5 kg of sufficiently degassed bisphenol A and diphenyl carbonate were charged into the reactor.
After stirring at 180 ° C. for 4 hours, the liquid was drained. The extracted liquid was partially reacted with bisphenol A and diphenyl carbonate, and the phenol concentration in the liquid was 10% by weight. After repeating the same operation four times, residual 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.
It was 00. When injection molding was carried out to produce No. 1 dumbbell, the b ^* value was 3.7, and coloring was not observed.

Example 4 Three stirred tank reactors made of SUS316L and SUS
A continuous polymerization device consisting of a centrifugal thin film evaporation type reactor made of 304 was replaced with nitrogen, and then deaerated phenol was used at normal pressure,
It was washed batchwise three times under the condition of 150 ° C., and then the residual phenol was removed under reduced pressure.

A fully degassed 1/1 weight ratio of bisphenol A and diphenyl carbonate were charged into a first stirred tank reactor and reacted at 180 ° C. for 5 hours to give 23
It was fed to a second stirred tank reactor whose pressure was controlled at 100 Torr at 0 ° C. The liquid continuously withdrawn from the second stirred tank reactor with a residence time of 3 hours was 2
The liquid, which was supplied to the third stirred tank reactor whose pressure was controlled at 10 Torr at 40 ° C. and was continuously withdrawn from the third stirred tank reactor at a residence time of 3 hours, was 0 ° C. at 270 ° C. It was continuously fed to a centrifugal thin film evaporation type reactor whose pressure was controlled to 1 Torr. 8 hours after the aromatic polycarbonate started to be discharged from the centrifugal thin film evaporation type reactor, the number average molecular weight of the polymer was 8900.
Met. When injection molding was carried out to produce No. 1 dumbbell, the b ^* value was 3.6, and coloring was not observed.

Example 5 The same continuous polymerization apparatus as in Example 4 was replaced with nitrogen, and then sufficiently degassed bisphenol A and diphenyl carbonate in a weight ratio of 1/1 were charged into the first stirred tank reactor, and 180 The liquid reacted at 5 ℃ for 5 hours at 230 ℃ 100
The liquid continuously withdrawn from the second stirred tank reactor with a residence time of about 3 hours, which was supplied to the second stirred tank reactor whose pressure was controlled at Torr, was 1 ° C at 230 ° C.
The liquid supplied to the third stirred tank reactor whose pressure was controlled at 0 Torr and 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 type reactor controlled at 0 Torr at 10 Torr. The concentration of phenol in the liquid extracted from the centrifugal thin film reactor is 0.2.
% By weight. After continuing this washing operation for 10 hours, the conditions of the third stirred tank reactor were set to 240 ° C. and 10 Torr
The conditions of the centrifugal thin film reactor are 270 ° C and 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 produced, and the b ^* value was 3.7.
No coloring was observed.

Example 6 An aromatic polycarbonate was obtained in 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 was 102.
It was 00. When injection molding was carried out to produce No. 1 dumbbell, the b ^* value was 3.7, and coloring was not 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 injection molding was carried out to produce No. 1 dumbbell, the b ^* value was 3.7, and coloring was not 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 injection molding was carried out to produce No. 1 dumbbell, the b ^* value was 3.8, and coloring was not observed.

[0050]

Industrial Applicability According to the present invention, high-quality aromatic polycarbonate having no color can be produced in a stainless steel reactor.

Claims (1)

[Claims] 1. When 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. Aromatic polycarbonate manufacturing method.