JPH01168728A - Polycarbonate resin - Google Patents

Abstract

PURPOSE:To obtain the title resin having low birefringence and excellent optical characteristics and being useful for a transparent resin material such as an optical recording base. CONSTITUTION:A polycarbonate resin having a reduced viscosity of 0.3dl/g or larger (measured at 25 deg.C in 0.5g/dl soln. in chloroform) is obtd. by reacting a dihydric alcohol (A) of formula I (wherein R1-6 are each H, halogen, 1-6C alkyl or 1-6C alkoxy) and a carbonate deriv. (B) (e.g., phosgene) and, if necessary, in the presence of 1-10mol% monohydric phenol which is an MW controlling agent, based on the component A is an org. base (e.g., pyridine).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel polycarbonate resin, particularly to an optically excellent polycarbonate resin with reduced birefringence.

[Prior Art] Polycarbonate resin is a synthetic resin widely used industrially, and is usually made of dihydric phenol such as 2,2-bis(4'-hydroxyphenyl)propane (hereinafter abbreviated as bisphenol A). It is produced by the reaction of carbonic acid with a carbonic acid derivative such as phosgene.

By the way, polycarbonate resin manufactured from bisphenol A has excellent properties such as excellent impact resistance, low hygroscopicity, and is stable to heat. However, when using it as an optical recording substrate, bisphenol Aromatic polycarbonate resins, typified by polycarbonate resins manufactured from A, contain highly anisotropic aromatic rings in their main chains, reducing birefringence, which is extremely important as a property of optical recording substrates. It was difficult to do so.

To solve this problem, in addition to reducing the molecular weight, attempts have been made to reduce molecular orientation during molding by examining molding conditions. However, since birefringence is caused by the material itself, it is extremely difficult to stably produce substrates with low birefringence, and there are no polycarbonate resins that can be used as optical recording substrates. It has not been discovered yet.

[Problems to be Solved by the Invention] The object of the present invention is to solve the problems of polycarbonate resin when used as an optical recording substrate without impairing the advantages of polycarbonate resin, which has excellent impact resistance, moisture absorption, and heat resistance. An object of the present invention is to provide an excellent polycarbonate resin with improved birefringence.

[Means for Solving the Problems] The present invention is based on the formula (I) (wherein R1, R2, R3, R4, R, and R6 may be the same or different from each other, and each Hydrogen, halogen, C1-C5 alkyl group, or C
~C5 alkoxy group. ) and using chloroform as a solvent, the concentration is 0.5 g/
The present invention relates to a polycarbonate resin in which the reduced viscosity [77SP/C] of the d1 solution at 25°C is 0.3ci1/g or more.

The method for producing the polycarbonate resin represented by the general formula (I) of the present invention is the same as conventionally known methods for producing polycarbonate resins, except that a dihydric alcohol represented by the general formula (n) is used instead of divalent bisphenols. It can be done by the following method.

Formula (II) (wherein R1, R2, R3, Ra, Rs and R6 may be the same or different, and each represents hydrogen, halogen, 01-C5 alkyl group, or It is a C-C5 alkoxy group.) Examples thereof are shown as (a) to (C).

(a) A method in which the dihydric alcohol represented by the above general formula (n) is dissolved in an organic base such as pyridine or triethylamine, and a carbonic acid derivative such as phosgene is bubbled into the solution to react. (b) Methylene chloride (C) Metal In the presence of transesterification catalysts such as oxides,
A method of reacting the dihydric alcohol represented by the above general formula (n) with a carbonic acid diaryl ester. In either method, 1 to 10 mol% of the dihydric alcohol is used as a molecular weight regulator. phenols such as phenol, p-tert-butylphenol, p-cumylphenol, etc. may also be added.

[Function] The polycarbonate resin represented by the general formula (I) of the present invention is a resin with excellent impact resistance, hygroscopicity, and thermal stability,
Moreover, since the birefringence caused by the resin itself is extremely small compared to aromatic polycarbonate resins, it can be used for transparent resin applications such as optical recording substrates that require low birefringence.

[Examples] The method of the present invention is shown in Examples below, but the present invention is not limited to these.

Further, the physical properties shown in Examples were measured by the following method.

(Birefringence) Using a light microscope, measure retardation using the Senarmont compensator method at 546 nm.

Example 1 10.2 1.5-decalin diol in a 309 bottom flask
g (60 mmof), 50 ml of pyridine and 200 ml of methylene chloride without magnetic stirring.

7.1 g (36 mmol) of phosgene was blown into the mixture over about 20 minutes. After further stirring at room temperature for 30 minutes, the reaction solution was poured into methanol and 90% of the white powder polymer was added.
% yield. The obtained polymer has a concentration of 0.5 g/d when chloroform is used as a solvent! The reduced viscosity [ηs p / c ] of the solution at 25° C. was 0.4 d1/g.

In IR spectrum measurement using the KBr tablet method, the absorption derived from the carbonyl bond of the carbonate group was 1731ao.
-', the absorption derived from the decalin ring is 2950.287
0 and 14403-1, and it was confirmed that the obtained polymers were the desired products. Tg is 179 by thermal analysis.
It was found that the temperature and Td were 335°C.

Furthermore, almost no letteration was observed due to 30-degree incidence.

Example 2 1.5-decalindiol 23.8g (14mmo
fl), diphenyl carbonate 30.0g (1,
4mmoj2), antimony trioxide 0.8■ (2゜8X
10-3 mmo 1 ) was placed in a 300 ml Separafour flask and stirred with a gear motor equipped with a stirring blade. Next, while reducing the pressure to 70 mmHg with a vacuum pump, incubate at 180 N at 200°C for 2 hours and further at lmmHg for 2 hours.
The mixture was heated and stirred for hours, and the distilled phenol was collected. After the reaction is completed, the reaction product is dissolved in chloroform and reprecipitated with methanol to obtain a white powdery polymer. The structure and physical properties of the obtained polymer were the same as those of the polymer obtained by the phosgene method.

Comparative Example Bisphenol A9.2 in a 300m1 309 bottom flask
g (40 mmol), 40 ml of pyridine, and 90 ml of methylene chloride were added, and the mixture was stirred magnetically. 4.8 g of phosgene (<48 mmof) was blown therein over about 20 minutes, and after further stirring at room temperature for 30 minutes, the reaction solution was poured into methanol to obtain a white powdery polymer with a yield of 95%. The obtained polymer had a concentration of 0.0 when using chloroform as a solvent.
Reduced viscosity of 5g/dρ solution at 25°C [ηsp/c
] was 2.5 d1/g. IR by KBr tablet method
In the spectrum measurement, the absorption derived from the carbonyl bond of the carbonate group was seen at 1773(+!l-', the absorption derived from the phenyl group was seen at 3030C1l-1, and the absorption that fluctuates due to the methyl group was seen at 2976■-1. Confirm that Tg is 147℃ and Tg by thermal analysis.
It was found that d was 482°C. Furthermore, the retardation at 30 degrees incidence was 65 nm/circle. [Effects of the Invention] As is clear from the above explanation, the polycarbonate resin of the present invention exhibits excellent transparency, low birefringence, and heat resistance, It is useful for optical resin materials such as optical recording substrates.

Claims (1)

[Claims] (1) Formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼... (I) (In the formula, R_1, R_2, R_3, R_4, R_5 and R_6 may be the same or different. and each hydrogen, halogen, C_1-C_5 alkyl group, or C_1-C_5 alkoxy group.
The reduced viscosity [ηsp/c] of the dl solution at 25°C is 0.
．． A polycarbonate resin with a density of 3 dl/g or more.