JPH0647617B2 - Method for producing polycarbonate by melting method - Google Patents

Description

The present invention relates to a method for producing a polycarbonate resin.

More specifically, it relates to a method for producing a polycarbonate resin having excellent saponification stability and mechanical strength by a melting method.

(Prior Art and Its Problems) An aromatic polycarbonate resin is an engineering plastic excellent in heat resistance and mechanical properties, but since it has a carbonate bond, saponification stability becomes a problem. For example, in the molding of this resin, when the pellets are not sufficiently dried, when they are heated and melted, they cause a decrease in molecular weight due to hydrolysis, resulting in deterioration of various physical properties.

Also, in molded articles, hydrolysis occurs over time,
It causes warpage and deterioration of mechanical properties. In order to solve such problems, various measures have been taken to improve saponification stability. For example, German Patent Publication No. 2063
As specified in No. 050, 2211957,
In the synthesis of bisphenol A-based polycarbonate, 2,2 as the aromatic bishydroxy compound component
It has been proposed that the inclusion of -bis (3,5-dialkyl-4-hydroxyphenyl) propane (hereinafter referred to as tetraalkyl-substituted bisphenol A) is effective for saponification stability. However, due to its rigid molecular structure, the tetraalkyl-substituted bisphenol A makes the resulting polymer brittle when contained in a large amount.

Further, tetraalkyl-substituted bisphenol A is poorer in reactivity than bisphenol A due to the steric hindrance derived from its molecular structure and the electrical effect of the alkyl group, so the polycarbonate containing it is polymerized by the melting method. Difficult and is usually synthesized by the solvent method. However, in the solvent method, phosgene is often used as a carbonate source, and in that case, there are the following problems. B) Phosgene is highly toxic and requires careful handling. B) It is difficult to collect and reuse the reaction by-product (HCl). C) It is difficult to obtain raw materials for phosgene because it is prohibited by law to move or carry it out. D) A purification step by washing the produced polymer is necessary.

(Object of the Invention) The present invention has been studied to solve such problems, and its object is a polycarbonate excellent in saponification stability and mechanical properties by a melting method without impairing heat resistance. Is to synthesize.

Then, as a result of diligent studies, the present inventors have added the tetraalkyl-substituted bisphenol A and the alicyclic bishydroxy compound to the bisphenol A as the bishydroxy compound component to impair the excellent physical properties of the aromatic polycarbonate. The present inventors have found the surprising fact that the above problems can be solved without any problem and completed the present invention.

(Structure of the Invention) That is, the present invention relates to a method for producing a polycarbonate by a melt reaction of a bishydroxy compound and a carbonic acid ester, wherein an aromatic bishydroxy compound such as bisphenol A and tetraalkyl-substituted bisphenol A is used as the bishydroxy compound component. A method for producing a polycarbonate having excellent saponification stability and mechanical properties, which comprises using 1 to 40 mol% of an alicyclic bishydroxy compound with respect to an aromatic bishydroxy compound.

The tetraalkyl-substituted bisphenol A used in the present invention is represented by the following general formula.

(R is _{-C 3 H 3, -C 2 H} 5, -C 3 H 7, or -C
H (CH ₃ ) ₂ represents the same group or different groups. Among these, particularly when R is —CH ₃ , it is preferable because the reactivity is high and the thermal stability of the produced polymer is high.

The compounding molar ratio of bisphenol A and tetraalkyl-substituted bisphenol A used in the present invention is 99/1.
Within 50 to 50/50, σ, σ, σ ′,
When the content of σ′-tetraalkyl-substituted bisphenol A is more than this range, it becomes difficult to obtain a high molecular weight product, which causes deterioration of mechanical properties. When it is less than this range, remarkable saponification It is not preferable because the effect of stability cannot be seen.

Examples of the alicyclic bishydroxy compound used in the present invention include 1,2-cyclohexanediol 1,3-cyclohexanediol 1,4-cyclohexanediol 4- (4-hydroxycyclohexyl) cyclohexanol 3- (3-hydroxycyclohexyl) Examples thereof include cyclohexanesanol 2,6-dihydroxydecalin 2,7-dihydroxydecalin, but are not limited thereto. Further, among these alicyclic bishydroxy compounds, it gives a product having good heat resistance. It is particularly preferable to use 1,3-cyclohexanediol or 1,4-cyclohexanediol.

The addition amount of the alicyclic bishydroxy compound used in the present invention is within the range of 1 to 40 mol% with respect to the aromatic bishydroxy compound. When it is 40 mol% or more, the heat resistance of the product deteriorates. And, the addition amount of the alicyclic bishydroxy compound is preferably within the range of 1 to 10 mol% because a product having excellent physical properties can be obtained, which is preferable.

The carbonic acid ester used in the present invention may be any ester as long as it can be transesterified with a bishydroxy compound and the produced monohydroxy compound can be easily removed from the reaction system by a method such as decompression. There are cycloalkyl carbonates, diaryl carbonates and bisalkyl carbonates of aromatic bishydroxy compounds and the corresponding biscycloalkyl or bisaryl carbonates. Among these, it is thermally stable and the produced monohydroxy compound can be easily removed from the reaction system.

Diaryl carbonates and bisaryl carbonates of aromatic bishydroxy compounds are preferably used, for example diphenyl carbonate, dicresyl carbonate, bis- (4-chlorophenyl) carbonate, bis-phenyl carbonate of hydroquinone, bis-phenyl carbonate of resorcin. , Bis- (4-
Examples thereof include bisphenyl carbonate of hydroxyphenyl) propane, bisphenyl carbonate of 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, and bisphenyl carbonate of bis- (4-hydroxyphenyl) ether.

The polymerization method of the present invention is not different from the conventional method, and the aromatic bishydroxy compound and the alicyclic bishydroxy compound, and equimolar to 1.2 times the molar amount of these bishydroxy compounds, preferably 1.0. ~ 1.1 times the molar amount of carbonic acid ester was charged, and the catalyst used in a normal transesterification reaction was added to the mixture to raise the temperature to a temperature at which the transesterification reaction occurs, and then the monohydroxy compound produced was gently added to the reaction system. In order to distill it to the outside, the temperature may be adjusted to a vacuum degree, and finally the reaction may be performed at 250 to 350 ° C. and a vacuum degree of 1 mmHg or less until no distillate is left.

The catalyst used in the present invention may be a conventional S exchange reaction catalyst, for example, a simple substance of an alkali metal or an alkaline earth metal, its oxide, hydroxide, hydride, amidated product, carbonate, acetate, alcoholate. , Phenolate, basic metal oxides such as ZnO, PbO and Sb ₂ O ₃ , or quaternary ammonium compounds such as trimethylphenylammonium chloride and tetrabutylammonium hydroxide.

(Effect of the Invention) The produced polymer obtained by the production method of the present invention can be pelletized or molded by a molding machine as it is without requiring a purification step such as washing. Moreover, since it has excellent saponification stability, it is not necessary to pay attention to water management during molding as in the conventional case. Further, compared with the polymer obtained by the conventional melting method, it has a higher molecular weight, and further has high saponification stability and mechanical properties without impairing heat resistance, so that it can be used as a housing material, automobile part material, electronic part material, etc. It is expected to show excellent performance for various applications.

(Example) Hereinafter, the present invention will be described more specifically with reference to Examples. In Examples and Comparative Examples, all units are by weight unless otherwise specified.

Example 1 Bisphenol A4 was added to a reactor equipped with a stirrer that had been replaced with nitrogen.
1.0 part, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane 5.68 parts, 1,4-cyclohexanediol 1.16 parts, and diphenyl carbonate 4
8.3 parts were charged and melted at 150 ° C. until uniform. Next, 0.00005 parts of lithium hydroxide was added, and the mixture was stirred for 30 minutes and then at 200 ° C. and 100 mmHg for 1.5 hours. Then, the temperature is 200 to 270 ° C., and the vacuum degree is 100.
By reacting up to 0.1 mmHg for 4 hours, about 40 ml of phenol is distilled out, and the molecular weight of 30000 (GP
A polycarbonate (according to C measurement) was obtained.

Example 2 In the same manner as in Example 1, except that 1.16 parts of 1,3-cyclohexanediol was used in place of 1,4-cyclohexanediol, a molecular weight of 36,000 (GPC
A polycarbonate (according to measurement) was obtained.

Example 3 Bisphenol A3 was added to a reactor equipped with a stirrer that had been replaced with nitrogen.
6.5 parts, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane 11.4 parts, 1,4-cyclohexanediol 1.16 parts, and diphenyl carbonate 4
8.3 parts were charged and the reaction was carried out in the same manner as in Example 1,
A polycarbonate having a molecular weight of 29,000 (by GPC measurement) was obtained.

Comparative Example 1 Bisphenol A4 was added to a reactor equipped with a stirrer that had been replaced with nitrogen.
5.6 parts and diphenyl carbonate 46.0 parts were charged and the reaction was carried out in the same manner as in Example 1 to obtain a molecular weight of 24,000.
A polycarbonate (by GPC measurement) was obtained.

Comparative Example 2 Bisphenol A4 was added to a reactor equipped with a stirrer that had been subjected to nitrogen substitution.
5.6 parts, 1,4-cyclohexanediol 1.16 parts, and diphenyl carbonate 48.3 parts were charged and the reaction was carried out in the same manner as in Example 1 to obtain a molecular weight of 43,000 or more (GP.
A polycarbonate (according to C measurement) was obtained.

Comparative Example 3 Bisphenol A4 was added to a reactor equipped with a stirrer that had been replaced with nitrogen.
1.0 part, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane 5.68 parts and diphenyl carbonate 46.0 parts were charged and the reaction was carried out in the same manner as in Example 2 to obtain a molecular weight of 18, 000 (according to GPC measurement) of polycarbonate was obtained.

Comparative Example 4 Bisphenol A3 was added to a reactor equipped with a stirrer that had been replaced with nitrogen.
6.5 parts, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane 11.4 parts and diphenyl carbonate 46.0 parts were charged and the reaction was carried out in the same manner as in Example 1 to obtain a molecular weight of 12 1,000 polycarbonate (according to GPC measurement) were obtained.

Table 1 shows the charged molar ratios of the bishydroxy compounds in Examples 1 to 3 and Comparative Examples 1 to 4, the molecular weight of the produced polymer, saponification stability, heat resistance, and tensile yield strength. As is clear from this table, in the system containing the tetraalkyl-substituted bisphenol A and the alicyclic bishydroxy compound, as compared with the system not containing these, the saponification stability and the mechanical properties of saponification were improved without impairing the heat resistance. Excellent polycarbonate is obtained.

Claims (1)

[Claims] 1. A method for producing a polycarbonate by a melt reaction of a bishydroxy compound and an ester carbonate, wherein bisphenol A and 2,2-bis (3,5-dialkyl-4-hydroxyphenyl) propane are used as bishydroxy compound components. An aromatic bishydroxy compound consisting of 1 to 40 relative to the aromatic bishydroxy compound
A method for producing a polycarbonate having excellent saponification stability and mechanical properties, which comprises using a mol% of an alicyclic bishydroxy compound.