JPH03160021A - Production of polycarbonate - Google Patents

Abstract

PURPOSE:To obtain an essentially chloride ion-free, colorless, transparent, high- mol.wt. polycarbonate without using toxic phosgene by reacting a dialkyl carbonate with an aromatic dihydroxy compound in the presence of a specified transesterification catalyst. CONSTITUTION:A dialkyl carbonate is reacted with an aromatic dihydroxy compound in the presence of RmSnY4-m (wherein R is an alkyl group, a phenyl group, an alkoxyl group or a phenoxy group; Y is an acyloxy group such as acetyloxy or propionyloxy; and m is an integer of 0.4) as a transesterification catalyst. As the catalyst, (C4H9)3SnOOCCH3 which can give a high-mol.wt. polycarbonate of a colorless and transparent hue is desirable. Representative examples of the above aromatic dihydroxy compounds include compounds of formulas I, II, III and IV (wherein R1, R2, R3 and R4 are each a hydrogen atom, a 1-8 C linear or branched alkyl group or a phenyl group; and X is a halogen atom; and n = 0-4).

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for producing a high molecular weight polycarbonate obtained by reacting a dialkyl carbonate and an aromatic dihydroxy compound in the presence of RmSnY4-n as a transesterification catalyst. It is.

(Prior Art and Problems to be Solved by the Invention) The high molecular weight polycarbonate of the present invention has a wide range of uses, particularly for injection moldings or as a glass sheet in place of window glass. It is a general-purpose engineering thermoplastic. Although the interfacial polycondensation method is generally effective for producing polycarbonate, it has drawbacks such as the use of toxic phosgene and the fact that chlorine ions remain in the polycarbonate produced. In order to eliminate these drawbacks, it was proposed in 1983 that polycarbonate could be produced by an interfacial polycondensation reaction between liquid trichloromethyl chloroformate, which is a dimer of phosgene, and a special dihydric phenol instead of toxic phosgene. -182336. However, a special dihydric phenol, 9,9-
There is only a description of bis(4-hydroxyphenyl)fluorenes. Angew et al. also reported that polycarbonate can be obtained from 2,2-bis(4-hydroxyphenyl)propane using triphosgene instead of toxic phosgene. Chem. (Angevante, Hemy) 99. 922 (1987), German Patent DE 3
440141, a reaction mechanism in which phosgene is generated has also been proposed.

On the other hand, in the transesterification reaction, a transesterification catalyst is added to diphenyl carbonate and an aromatic dihydroxy compound, and a prepolymer is synthesized while distilling off phenol under heating and reduced pressure. High molecular weight polycarbonate is obtained by heating to remove phenol (U.S. Pat. No. 4,345,062).
Unlike other engineering plastics, high molecular weight polycarbonate has an extremely high melt viscosity, so it requires high temperatures of 290°C or higher, and high vacuum (10-2 Torr) to distill off phenol, which has a high boiling point.
Because of this, it is difficult to industrialize the process in terms of equipment, and it is known that residual phenol in polycarbonate, which is used for human consumption, has an unfavorable effect on hue and physical properties.

Furthermore, there is a special method for producing an aromatic polycarbonate by combining bisalkyl carbonate esters of aromatic dihydroxy compounds having an alkyl carbonate group at the terminals using a transesterification reaction and self-condensing them in the presence of a catalyst. It is disclosed in Japanese Patent No. 63-205318. This production method involves self-condensation in the absence of aromatic dihydroxy compounds, and the catalysts that can be used are Zn, A
II of the periodic table represented by l, Sn, Ti, etc.
It is described that the catalyst is selected from metal elements belonging to Class B, IIIB, IVA, and IVB and their compounds.

However, this method is a method for producing carbonate, which is different from the starting material of the present invention.

Additionally, JP-A No. 63-223035 discloses a method for producing aromatic polycarbonate by heating a bisalkyl carbonate ester of an aromatic dihydroxy compound to synthesize a prebolymer using a transesterification reaction. However, the catalyst used in the solid phase polymerization reaction to increase the molecular weight is not particularly described.

(Means for Solving the Problems) The present inventors essentially produced chlorine ions without using toxic phosgene by reacting a dialkyl carbonate with an aromatic dihydroxy compound in the presence of a special transesterification catalyst. We have now discovered that it is possible to obtain colorless and transparent high-molecular weight polycarbonate containing no polycarbonate. That is, the present invention provides (1) RmSnY as a transesterification catalyst.
A method for producing polycarbonate, which comprises reacting a dialkyl carbonate and an aromatic dihydroxy compound in the presence of 4-m.

(Here, R is an alkyl group, a phenyl group, an alkoxyl group, or a phenoxy group, Y is an acyloxy group such as an acetyloxy group or a propionyloxy group, and m is O-
It is an integer of 4. ) (2) A polycarbonate characterized in that a polycarbonate is obtained via an oligomer of a dialkyl carbonate-capped aromatic dihydroxy compound obtained from a dialkyl carbonate and an aromatic dihydroxy compound in the presence of RmSnY4-m as a transesterification catalyst. manufacturing method.

(Here, R is an alkyl group, a phenyl group, an alkoxyl group, or a phenoxy group, Y is an acyloxy group such as an acetyloxy group or a propionyloxy group, and m is 0 to 4
is an integer. ) (3) A method for producing a polycarbonate in which the aromatic dihydroxy compound described in (1) or (2) is represented by (I), (II), (III), or (I¥).

R1Me (Rl, R2, Ra, R4 are hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, or a phenyl group, and X is a halogen atom, and n=o to 4) (4) The above A method for producing a polycarbonate copolymer according to (1), (2), or (3).

(5) RmSnY4-m described in (1) or (2) or (3) or (4) is (C4H9)3SnOOCCH3
The present invention relates to a method for producing a polycarbonate, which is a method for producing a polycarbonate.

Representative examples of dialkyl carbonates that can be used in the present invention include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, di-n-propyl carbonate, di-n-propyl carbonate, and di-n-propyl carbonate. Examples include butyl carbonate, di-t-butyl carbonate, diamyl carbonate, dihexyl carbonate, diheptyl carbonate, dioctyl carbonate, dicyclopropyl carbonate, etc., but preferably the alkyl group that is eliminated when forming a carbonate bond is Dimethyl carbonate has a low boiling point and is made from inexpensive methyl alcohol. Moreover, the following compounds are mentioned as representative examples of aromatic dihydroxy compounds. Aromatic dihydroxy compounds classified into general formula (I) include 2,2-bis-(4-hydroxyphenyl)propane, 2,2-bis-(4-hydroxyphenyl)butane, 2,2-bis-(4-hydroxyphenyl)butane, and 2,2-bis-(4-hydroxyphenyl)propane. -hydroxyphenyl)-4-methylpentane, 2,2-bis-(4-hydroxyphenyl)octane, 4.4'-
dihydroxy-2.2.2- }liphenylethane, 2
, 2-bis-(3,5-dibromo.4-hydroxyphenyl)propane, and the like. As a bisphenol classified into general formula (II), 2,2-bis-(4
．． Hydroxy-3-methylphenyl)broban, 2,2
-bis(4-hydroxy-3-isopropylphenyl)propane, 2,2-bis-(4-hydroxy-3-s
ee. butylphenyl)propane, 2,2-bis-(4
-hydroxy-3-tertiarybutylphenyl)propane and the like. Examples of bisphenols classified into general formula (III) include 1.1'-bis-(4-hydroxyphenyl)-p-diisopropylbenzene, 1.
Examples include 1'-bis-(4-hydroxyphenyl)-m-diisopropylbenzene. As a bisphenol classified into general formula (IV), 1,1-bis(4-
hydroxyphenyl)cyclohexane. Furthermore, general formulas (I), (II), (III), (IV
) It is also possible to produce a copolymerized polycarbonate in which two or more dihydric phenols selected from the following are combined.

In addition, RmSnY4- used as a transesterification catalyst
A typical example of m is (04Hg)3SnOOCCH3
, (C4Hg)2Sn(OOCCH3)2 , (
C4H9)2Sn(OOCC2H5), (C6H50
)ssnoOccHa , (C6H50)2sn(O
Examples include OCCH3)2. It is also possible to use two or more of these catalysts in combination. Preferably,
Examples include (C4Hg)3SnOOCCH3, in which the resulting high molecular weight polycarbonate is colorless and transparent. Further, the amount of the catalyst to be used can be in the range of i
It is 1 mole. If the amount is less than 5X10-4 mol, the polymerization rate will be slow and this will cause coloration, and if it exceeds 5X10-1 mol, the catalyst remaining in the resulting polycarbonate will cause an adverse effect on the physical properties, such as a decrease in mechanical properties.

Regarding the reaction conditions for carrying out the polycondensation reaction in the method of the present invention, dialkyl carbonate is used in an amount of 0.5 to 10 times the mole of the aromatic dihydroxy compound as a raw material, preferably 1 to 5 times the mole. It is. If it is less than 1 mole, the degree of polymerization will not increase stoichiometrically, and if it exceeds 5 moles, the amount of excess dialkyl carbonate to be removed from the system will increase, which is disadvantageous in terms of equipment. General reaction conditions include adding 1.5 times the molar amount of dimethyl carbonate to 1 mole of 2,2-bis(4-hydroxyphenyl)propane under nitrogen.
Charged into a US316 reactor and used as a catalyst (C4H9)
After adding 5.times.10@-3 moles of 3SnOOCCHs, the mixture is reacted at a temperature of 90'C to 320'C for 1 hour under normal pressure or increased pressure, and by-produced methanol and excess dimethyl carbonate are removed from the system. Further under reduced pressure 200 ~
A high molecular weight polycarbonate can be obtained by reacting at 280°C for 2 to 3 hours and removing methanol from the system.

In addition, when obtaining a high molecular weight polycarbonate via an oligomer of an aromatic dihydroxy compound sealed with a dialkyl carbonate, twice the molar amount of dimethyl carbonate is added per mole of 2,2-bis(4-hydroxyphenyl)propane. Charged into a SUS316 reactor under nitrogen,
5X10 (C4H9)3SnOOCCH3 as catalyst
- After adding 3 mol, at normal pressure or under pressure, 90°C ~
The weight average molecular weight (in terms of polystyrene) of the above oligomer obtained by reacting in the range of 250 ° C for 10 to 30 minutes and removing by-product methanol and excess dimethyl carbonate from the system is in the range of i,ooo to 18,000. and is preferably in the range of 1,500 to 15,000.

If it is less than 1,500, the time required for post-condensation under reduced pressure will be prolonged, which will adversely affect the hue of the resulting polycarbonate, and if it exceeds 15,000, the reaction time will be undesirably prolonged under normal or elevated pressure.

The present invention will be explained in detail below using examples, but the present invention is not limited to these examples in any way.

(Example) Example 1 2,2-bis(4
228 parts by weight of -hydroxyphenyl)propane, 157 parts by weight of dimethyl carbonate, and (C4H9)3SnOO
After charging 1.75 parts by weight of CCH3 and performing nitrogen substitution by pressurization and normal pressure operation, the reaction temperature was raised to 180 °C, the pressure was maintained at 8 Kg / cm2 with stirring, and the reaction was carried out for 1 hour. Ta. At this time, the raw methyl alcohol and excess dimethyl carbonate were distilled off. 2,2-
The reaction rate of bis(4-hydroxyphenyl)proban is 9
It was 5%. Next, the raw oligomer (weight average molecular weight = 1,500) was placed in a round-bottom reaction vessel at atmospheric pressure and gradually heated to 240-250°C under reduced pressure. After about 3 hours, the temperature was finally raised to 280'C under a pressure of about 5 mmHg and treated for 15 minutes. As the methyl alcohol was removed, the liquid in the system became viscous. The obtained polymer was clear and colorless, and gel permeation chromatography revealed that it had a weight average molecular weight of 40,500 (in terms of polystyrene).

Example 2 Aromatic dihydroxy compound 2.2-bis(4-hydroxyphenyl)propane 11 as raw material was prepared in the same manner as in Example 1.
4 parts by weight, 145 parts by weight of 4.4'-dihydroxy-2,2.2-triphenylethane, 157 parts by weight of dimethyl carbonate, and (C4H9)3Sn00CCH3 1.
75 parts by weight was charged and reacted in the same manner as in Example 1 to obtain an oligomer (weight average molecular weight = 1,700), placed in a round bottom reaction vessel at atmospheric pressure, and gradually reduced to 250 to 260 parts by weight while reducing the pressure.
It was heated to 'C. After about 3 hours, finally about 4mmHg
The humidity was raised to 280°C at a pressure of The obtained polymer was clear and colorless, and was found to have a weight average molecular weight of 39,000 (in terms of polystyrene) by gel permeation chromatography. In addition, hydrogen-2,2-bis(4-hydroxyphenyl)propane and 4,4'-dihydroxy-2.2.2 were detected using a magnetic resonance apparatus.
-} It was found that it was a polycarbonate containing 1:1 of liphenylethane. Furthermore, the glass transition temperature was 166°C as measured by a differential thermal analyzer.

Example 3 2,2-bis(4
228 parts by weight of -hydroxyphenyl)propane and 117 parts by weight of dimethyl carbonate and (C4H9冫3SnOO)
After charging 2.63 parts by weight of CCH3 and purging with nitrogen through pressurization and normal pressure operation, the reaction temperature was raised to 200'C, maintained at a pressure of 10 Kg/am2 with stirring, and reacted for 1 hour. . At that time, residual methyl alcohol and excess dimethyl carbonate were distilled off. Next, the pressure was returned to normal, and the pressure was reduced to remove by-products while gradually heating to 240 to 250'C. After about 2 hours, the temperature was finally raised to 290°C under a pressure of about 4 mmHg, and treatment was carried out for 25 minutes. The weight average molecular weight of the obtained polymer was determined by gel permeation chromatography to be 39,00.
0 (calculated as boristyrene).

Comparative Example 1 A catalyst (C4H9)33nOO was prepared in the same manner as in Example 1.
1.70 tetrabutyl titanate instead of CCH3
A reaction was carried out by adding parts by weight, but the liquid taken out was reddish brown and the molecular weight did not increase.

(Effects of the Invention) According to the present invention, it is possible to overcome the drawbacks of conventional polycarbonate production methods and to produce industrially efficient polycarbonate.

[Brief explanation of the drawing]

FIG. 1 shows the IR spectrum of the polymer obtained in Example 1.3.

Claims (5)

[Claims] (1) A method for producing polycarbonate, which comprises reacting a dialkyl carbonate and an aromatic dihydroxy compound in the presence of RmSnY4-m as a transesterification catalyst. (Here, R is an alkyl group, a phenyl group, an alkoxyl group, or a phenoxy group, Y is an acyloxy group such as an acetyloxy group or a propionyloxy group, and m is 0 to 4
is an integer. ) (2) A polycarbonate characterized by obtaining a polycarbonate via an oligomer of a dialkyl carbonate-capped aromatic dihydroxy compound obtained from a dialkyl carbonate and an aromatic dihydroxy compound in the presence of RmSnY4-m as a transesterification catalyst. Manufacturing method. (Here, R is an alkyl group, a phenyl group, an alkoxyl group, or a phenoxy group, Y is an acyloxy group such as an acetyloxy group or a propionyloxy group, and m is 0 to 4
is an integer. ) (3) The aromatic dihydroxy compound according to claim 1 or 2 is (I), (II), (III), (IV)
A method for manufacturing polycarbonate represented by ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(III) ▲There are mathematical formulas, chemical formulas, tables, etc.▼( IV) (R_1, R_2, R_3, R_4 are hydrogen or have 1 carbon number
~8 linear or branched alkyl group, or phenyl group, where X is a halogen atom and n = 0 to 4) (4) A polycarbonate obtained by reacting the dialkyl carbonate according to claim 1 or 2 with at least two or more aromatic dihydroxy compounds selected from the aromatic dihydroxy compounds according to claim 3. Polymer manufacturing method. (5) RmSnY4-m according to claim 1 or 2 or 3 or 4 is (C_4H_9)_3
A method for producing polycarbonate that is SnOOCCH_3.