JPS63207822A - Aromatic polycarbonate terpolymer - Google Patents

Abstract

PURPOSE:To obtain the titled copolymer, having a low photoelastic constant and suitable as optical information recording disks using reflection and transmission of laser beams, by copolymerizing specific compounds, such as bis(hydroxy- tert-butylphenyl)propane. CONSTITUTION:The aimed copolymer, obtained by copolymerizing (A) 2-92mol.% 2,2-bis-(4-hydroxy-3-tert-butylphenyl)propane expressed by formula I with (B) 2-88mol.% 1,1'-bis-(4-hydroxyphenyl)-p-diisopropylbenzene expressed by formula II and (C) 2-96mol.% 4,4'-dihydroxy-2,2,2-triphenylethane expressed by formula III by, e.g. a phosgene method, and having preferably 13,000-50,000 viscosity-average molecular weight, >=125 deg.C glass transition temperature and <=60 Brewstars photoelastic constant.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a polycarbonate material used in optical information recording discs that record signals using laser beams or read signals recorded by reflection or transmission of laser beams. It relates to original copolymers and is mainly used for optical discs.

(Prior art) DRAW is marketed by shining a spot beam of a laser beam onto a disk, recording signals on the disk using minute pits, or detecting the amount of reflected or transmitted light of the laser beam by recording signals recorded by such pits. (
direct read after write), Erasa
The ble-DRAW (erasable direct read after write) type optical information recording/reproducing method can significantly increase the recording density, especially when erasable.
The e-DRAW type allows erasing and writing of records, and the images and sound quality reproduced from them have excellent characteristics, so it is widely used for recording and reproducing images and sound quality, recording and reproducing large amounts of information, etc. It is expected that The disks used in this recording/reproducing system are not only required to be transparent so that laser beams can pass through the disk body, but also to have optical homogeneity to reduce reading errors. Birefringence occurs when the laser beam passes through the disk body, mainly due to thermal stress generated during the cooling and flow process of the resin during disk body formation, residual stress due to bimolecular orientation and volume change near the glass transition point. This large optical non-uniformity caused by birefringence is a fatal defect for optical discs.

(Problem to be solved by the invention) Birefringence, which is mainly caused by the thermal stress bimolecular orientation and residual stress generated during the cooling and flow process of the resin during disk molding, can be obtained by selecting the forming conditions. Although the birefringence of the disc can be made quite small, it is highly dependent on the inherent birefringence of the molding resin itself, that is, the photoelastic constant.

(Means for solving the problem) Birefringence can be expressed by the following equation (1) as a product of a photoelastic constant and a residual stress.

nl-n2=C(al-a2) (1)n
+-n2: Birefringence σ1-σ2: Residual stress C: Photoelastic constant It is clear that if the photoelastic constant in equation (1) is made smaller, the birefringence of the disc obtained will be smaller even if the molding conditions are the same. Therefore, the inventors developed 2,2-bis-(4゜hydroxy-3-tert-butylphenyl)propane, 1
, 1'-bis-(4-hydroxyphenyl)-para-diisopropylbenzene and further 4,4-dihydroxy-2
, 2,2-triphenylethane through carbonate bonds, it was discovered that a resin with a small photoelastic constant can be obtained without impairing the mechanical properties of aromatic polycarbonate, and the present invention was achieved based on this discovery. .

(Structure of the Invention) The present invention comprises 2 to 92 mol% of 2,2-bis-(4-hydroxy-3-tert-butylphenyl)propane (1) and 1.1-bis-(4-hydroxyphenyl)- 2 to 88 mol% of para-diisopropylbenzene (II) and further 2 to 96 mol% of 4,4'-dihydroxy-2,2,2-triphenyl ethane (III) each having a total of 100 mol%.
An aromatic polycarbonate copolymer obtained by bonding by carbonate bonds so that the amount is mol%, the glass transition temperature is 125°C or higher, and the photoelastic constant is 60 Brewsters (Brewsters, 10
Regarding the optical disk consisting of a fragrant polycarbonate co -o -sang, which is below "M2 / N).

Ll-+3 CH3(11) In this aromatic polycarbonate copolymer, formula (I)
The structural unit of is preferably in the range of 10 to 80 mol%. If this structural unit exceeds 80 mol%, the glass transition temperature of the aromatic polycarbonate copolymer obtained will be 125°C or lower, and if it is lower than 10 mol%, the photoelastic constant of the coelectric material will be 60 Br. Stars (Brewsters, 10”m
2/N) or more, which is not desirable as an optical disc. The content of the structural unit of formula (II) is preferably 2 to 88 mol%. The structural unit of formula (II) improves the long-term thermal stability of the resulting aromatic polycarbonate and prevents discoloration due to heat, but when it exceeds 80 mol %, the photoelastic constant decreases to 60 Brewsters (10"m2). /N
) or more, and if it is less than 2 mol%, the structural unit (
II) No improvement in long-term thermal stability was observed at all. The structural unit of formula (III) is 2 to 58 mol%
A range of is preferred. Structural unit (III) also improves the long-term thermal stability of the resulting aromatic polycarbonate, especially preventing weight loss due to heat, but if it exceeds 58 mol%, the mechanical properties of the copolymer, especially the impact resistance, deteriorate and become virtually useless. Moreover, if it is lower than 2 mol%, the effect of the structural unit (IH) will not appear. In addition, the viscosity average molecular weight of the copolymer of the present invention in terms of bisphenol A-polycarbonate is IS, 000 to 5.
0,000 is preferred. If it is less than 13,000, the copolymer becomes brittle, and if it exceeds 50.000, melt flowability becomes poor and moldability becomes poor. There are the following two methods for producing the polycarbonate copolymer of the present invention.

■Transesterification method 2.2-bis-(4-hydroxy-3-tert-butylphenyl)propane, 1.1'-bis-(4-hydroxyphenyl)-para-diisopropylbenzene,
A slight stoichiometric excess of diphenyl carbonate to a mixture of 4,4-dihydroxy-2,2,2-triphenylethane is added to a mixture of 4,4-dihydroxy-2,2,2-triphenylethane at a temperature of about 1-60 to 180°C in the presence of a conventional carbonation catalyst. The reaction was carried out for about 30 minutes at normal pressure and with an inert gas introduced, and the precondensation was finally completed at a temperature of about 180 to 220°C while gradually reducing the pressure over 2 hours at 10 Torr and 220°C. do. Then, 5 Torr at 10 Torr and 270°C for 30 minutes.

React at 270°C for 20 minutes, then at 0.5 Torr or less,
Preferably 0.3 Torr to 0.3 Torr. The condensation is carried out after 1.5 to 2.0 hours at 270° C. under a vacuum of ITorr. In addition, as carbonation catalysts for carbonate bonding, alkali metal and alkaline earth metal catalysts such as lithium-based catalysts, potassium-based catalysts, sodium-based catalysts, calcium-based catalysts, and tin-based catalysts are suitable. Examples include lithium, lithium carbonate, potassium borohydride, potassium hydrogen phosphate, sodium hydroxide, sodium borohydride, calcium hydride, dibutyltin oxide, and stannous oxide. Among these, it is preferable to use a potassium catalyst.

■Phosgene method Attach a stirrer, a thermometer, a gas inlet pipe, and an exhaust pipe to a three-hole flask, and add 2,2-bis-(4,hydroxy-
3-tert-butylphenyl)propane, 1゜1-
Bis-(4-hydroxyphenyl)-para-diisopropylbenzene and 4,4'-dihydroxy-2,2,
A pyridine solution of a mixture of 2-triphenylethane is added, and phosgene gas is introduced while stirring the mixture vigorously. Since phosgene is extremely poisonous, it must be operated in a strong fume hood. Additionally, a unit is installed at the exhaust end to decompose and detoxify excess phosgene with a 10% sodium hydroxide aqueous solution. Phosgene is introduced into the flask through an empty air washing bottle, an air washing bottle containing paraffin (count the number of ponds), and an empty air washing bottle. The glass introduction tube should be inserted above the stirrer, and the tip should be widened into a funnel shape to prevent it from becoming clogged by precipitated pyridine salt. As gas is introduced, pyridine hydrochloride precipitates and the contents become cloudy. Water cooling is performed so that the reaction temperature is 30°C or less. It becomes viscous as the condensation progresses. Phosgene is passed through the mixture until the yellow color of the phosgene-hydrogen chloride complex no longer disappears. After the reaction is completed, methanol is added to precipitate the polymer, which is then filtered and dried.

The polycarbonate produced is methylene chloride, pyridine,
Because it dissolves in chloroform, tetrahydrofuran, etc.
These solutions are purified by reprecipitation with methanol.

The polycarbonate copolymer obtained in this way is
The present invention is useful for a DRAW optical information recording disc that records a signal using a laser beam or reads out a recorded signal by reflecting or transmitting the laser beam. EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples. In addition, the viscosity average molecular weight shown in the following examples is determined using a methylene chloride solution of bisphenol A polycarbonate at 20°C and obtained as the relational expression between the intrinsic viscosity [rlF and the molecular weight M [r1] = 1.11 x 10-4M0.82[E
, Mii11er&O, Bayer; USP2,999
, 844 (1961)] is the molecular weight in terms of bisphenol A polycarbonate calculated from the intrinsic viscosity.

(Example) Example 1 2.2-bis-(4,hydroxy-3-tert-butylphenyl)propane 204 parts by weight (50 mo1%)
and LI'-bis-(4-hydroxyphenyl)-para-
Diisopropylbenzene 125 parts by weight (30 mo1%)
70 parts by weight (20 mo1%) of 4,4'-dihydroxy-2,2,2-triphenylethane and 264 parts by weight of diphenyl carbonate were placed in a 31-lough flask, and after repeating degassing and N2 purge 5 times, silicon bath 160
The mixture was melted at 0.degree. C. while nitrogen was being introduced. Once melted, a solution of potassium borohydride, which is a carbonation catalyst, dissolved in phenol (10-3 mo1% amount based on the total amount of bisphenol charged) was added, and the mixture was heated at 160°C under N2.

The mixture was stirred and brewed for 30 minutes. Next, under the same temperature IQQTorr
After stirring for 30 minutes, it was further stirred at the same temperature for 5 minutes.
The pressure was reduced to QTorr and the reaction was carried out for 60 minutes. Next, the temperature was gradually raised to 220° C. and the reaction was carried out for 60 minutes, and 80% of the theoretical amount of phenol was distilled out through the reaction up to this point. Thereafter, the pressure was reduced to 1 Q Torr at the same temperature, and the reaction was carried out for 30 minutes.The temperature was gradually raised to 270°C, and the reaction was carried out for 30 minutes. Further, at the same temperature, the pressure was reduced to 5 Torr and the reaction was allowed to proceed for 30 minutes, and almost all of the theoretical amount of phenol was distilled out to complete the precondensation.

Next, it was tightened after 2 hours at the same temperature at 0.1 to Q and 3 Torr. After the product polymer was taken out and cooled under nitrogen, the solution viscosity was measured at 20° C. using dichloromethane as a solvent. Viscosity average molecular weight Mv calculated from this value
=22,000. Also, DSC (D771/
Digital Scanning Calorimeter; Perki
n-Elmer 2C type), the glass transition point is Tg=1
It turned out to be 39°C. Furthermore, when the photoelastic constant was measured, C=41 Brewsters (Brewsters,
10-12 m2/N). The equipment used for measurement was DSC; differential scanning calorimeter Perkin-E1mer 2.
C type, the photoelastic constant was measured using a self-made one, but the method for calculating the photoelastic constant was a test piece (50 mm x 10 mm x
1 mm) in the length direction, each value was substituted into the above equation (1), and the photoelastic constant was determined from the slope. Incidentally, the photoelastic constant of polycarbonate of 2,2-bis-(4,hydroxyphenyl)propane is C
=82 Brewsters (10-
12m2/N).

Example 2 A three-hole flask is equipped with a stirrer, a thermometer, a gas inlet pipe, and an exhaust pipe. 2, in a 10% by weight aqueous solution of sodium hydroxide.
204 parts by weight (50 mo1%) of 2-bis-(4-hydroxy-3-tert-butylphenyl)propane and 1
, 125 parts by weight (30 mo 1%) of 1'-bis-(4-hydroxyphenyl)-para-diisopropylbenzene and 70 parts by weight (20 mo 1%) of No. 42 dihydroxy-2,2,2-triphenylethane were dissolved, and dichloromethane was added. In addition, phosgene gas was introduced while stirring the mixture vigorously. Phosgene was introduced from the cylinder into the flask through an empty air wash bottle, a water filled air wash bottle, and an empty air wash bottle. The reaction temperature during introduction of phosgene gas was water-cooled to be 25° C. or lower.

As the condensation progresses, the solution becomes viscous. Further, phosgene was passed through the mixture until the yellow color of the phosgene-hydrogen chloride complex no longer disappeared. After the reaction was completed, the reaction solution was poured into methanol, filtered, and washed with water repeatedly. Further, the produced polycarbonate was purified by reprecipitation with methanol from a dichloromethane solution. After purification and thorough drying, the solution viscosity was measured at 20°C using dichloromethane as a solvent.

The viscosity average molecular weight calculated from this value is Mv=23,80
It was 0. Furthermore, when the same measurements as in Example 1 were performed, it was found that the glass transition point and photoelastic constant were the same as in Example 1.

(Evaluation of recording properties) A recording film was attached to the polycarbonate copolymer produced as described above, and the optical recording properties were evaluated. That is, Example 1
, 2, using an injection molding machine (
130m in diameter using a Guina melter made by Multiki Seisakusho.
m, formed into a disk-shaped substrate with a thickness of 1.2 mm, and sputtering equipment (RF sputtering equipment, manufactured by Japan Vacuum Co., Ltd.) using an alloy target of Tb23.5Fe64°2CO12,3 (atomic%) on this substrate. Among them, 1,000 people formed magneto-optical recording films. On this recording film, a protective film of 1,000 inorganic glasses as described in JP-A-60-177449 by the present applicant was formed using the same sputtering apparatus as above. The performance of the obtained magneto-optical disk was evaluated by the CN ratio, BER, and the rate of change in CN ratio under the conditions of 60° C. and 90 RH%. The results are shown in Table 1.

Table 1 (Note 1) CN ratio = writing power 7mW (milliwatt)
.

Measured at reading power 1mW, carrier frequency IMHz, 30KHz in resolution band (Note 2) CN change rate (%) = 60 relative to initial CN ratio
'C.

Comparative example of degree of decrease in CN ratio after 30 days under 90RH% condition (Note 3) = conventionally known polycarbonate (Ondaikasei)
A magneto-optical disk was fabricated using a substrate manufactured by AD-5503) manufactured by Co., Ltd. in the same manner as above.

As is clear from the results in Table 1, the polycarbonate copolymer according to the present invention has a significantly improved CN ratio due to a decrease in birefringence value, and is also found to have excellent durability.

Claims (1)

[Claims] 2,2-bis-(4-hydroxy-3-tert-butylphenyl)propane 2 to 92 monole%, 1,1'-
2 to 88 mol% of bis-(4-hydroxyphenyl)-para-diisopropylbenzene and 2 to 96 mol% of 4,4'-dihydroxy-2,2,2-triphenylethane each having a total of 100 mol%. An aromatic polycarbonate copolymer obtained by bonding through carbonate bonds, which has a glass transition temperature of 125°C or higher and a photoelastic constant of 60 Brewsters (10^-^1 ^2m^
2/N) or less.