JPS63199733A - Aromatic polycarbonate terpolymer - Google Patents

Abstract

PURPOSE:To obtain the title terpolymer having a small photoelastic constant and excellent mechanical properties and being useful for optical information recording discs, by copolymerizing three specified compounds selected from bisphenol compounds through carbonate bonds. CONSTITUTION:2-60mol.% 1,1'-bis(4-hydroxyphenyl)-m-diisopropylbenzene (A) of formula I is mixed with 2-70mol.% 1,1-bis(4-hydroxyphenyl)cyclohexane (B) of formula II and 2-90mol.% 4,4'-dihydroxy-2,2,2-triphenylethane (C) of formula III so that the total of components A-C may be 100mol.%. A diphenyl carbonate (D) in an amount slightly excess over the stoichiometric amount is added to this mixture, and the obtained mixture is reacted at normal pressure in an inert gas atmosphere in the presence of a carbonation catalyst (E) such as KBH4 to obtain the title terpolymer of a glass transition temperature >=125 deg.C and a photoelastic constant <=60 Brewsters.

Description

Detailed Description of the Invention (Industrial Application Field) This invention relates to polycarbonate used in optical information recording disks that record signals with laser beams or read out recorded signals by reflection or transmission of laser beams. This invention relates to terpolymers and is mainly used in optical discs.

(Prior art) DRAW (Direct RAW) is a method in which a spot beam of a laser beam is applied to a disk, and signals are recorded on the disk using minute pits, or signals recorded by such pits are read out by detecting the amount of reflected or transmitted light of the laser beam. Read After Write), Erasab
le-DRAW (erasable, direct read)
The after-write (after-write) type optical information recording/reproducing method can significantly increase the recording density, and is especially suitable for erasable
- With the DRAW type, it is also possible to erase and write records,
In addition, since the images and sound quality reproduced from them have excellent characteristics, it is expected that they will be widely put to practical use in recording and reproducing images and sound quality, recording and reproducing large amounts of information, etc.

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 residual stress caused by the thermal stress caused by the cooling and flow process of the resin during the formation of the disk body, the orientation of two molecules, and the 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 disk can be made considerably small, it is highly dependent on the inherent birefringence of the molded MQ'fl 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.

n□-n2=C(a,-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 discovered that 1,1', bis-(4-hydroxyphenyl)-meta-diisopropylbenzene and 1
, 1-bis-(4,hydroxyphenyl)cyclohexane and further 4,4-nidihydroxy-2,2,2-triphenylethane are copolymerized through carbonate bonds without impairing the mechanical properties of the aromatic polycarbonate. The present invention was based on the discovery that a resin with a small photoelastic constant can be obtained.

(Structure of the Invention) The present invention comprises 2 to 60 mol% of 1,1', bis, (4, hydroxyphenyl)-meta-diisopropylbenzene (1), and 1,1'. Bis-(4-hydroxyphenyl)cyclohexane (II) 2 to 70 mol% and further: 2, 4, 4
dihydroxy-2,2,2-triphenylethane (I
II) An aromatic polycarbonate copolymer obtained by bonding 2 to 90 mol% through carbonate bonds such that the total of each is 100 mol%, the glass transition temperature of which is 1256C or higher, and which is resistant to light. Elastic constant is 60
Puri 1-Stars (Brewsters, 10°”m”
/N) or less.

In this aromatic polycarbonate copolymer, formula (I)
The structural unit of is preferably in the range of 20 to 55 mol%. If this structural unit exceeds 50 mol%, the glass transition temperature of the resulting aromatic polycarbonate copolymer will be 125°C or lower, and if it is lower than 20 mol%, the photoelastic constant of the coelectric material will be 60 Brewsters (Brewsters). 10-1
2m2/N) or more, which is not preferable as an optical disc. The content of the structural unit of formula (II) is preferably 3 to 70 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 75 mol%, the photoelastic constant decreases to 6.
0 Brewsters, 10”m2
/N) or more, and if it is less than 3 mol %, no improvement in long-term thermal stability due to the introduction of the structural unit (II:) will be observed. The content of the structural unit of formula (III) is preferably 3 to 70 mol%. Structural unit (III) also improves the long-term thermal stability of the resulting aromatic polycarbonate, especially preventing weight loss due to heat, but if the amount exceeds 75 mol%, the mechanical properties of the copolymer, and especially the impact resistance, deteriorate, resulting in a substantial increase in the Moreover, if it is lower than 2 mol %, the effect of the structural unit (III) will not appear. The copolymer of the present invention has a viscosity average molecular weight of 13.0 in terms of bisphenol A-polycarbonate.
00 to 50,000 is preferred. If it is less than 13,000, the copolymer becomes brittle, and if it exceeds 50,000, the melt fluidity will be poor and the moldability will be poor. There are the following two methods for producing the polycarbonate copolymer of the present invention.

■Transesterification method 1.1', bis-(4-hydroxyphenyl), meta-
diisopropylbenzenyl)cyclohexane, 4,4 dihydroxy-2.2
．． An inert gas was introduced into a slightly stoichiometrically equivalent excess of diphenyl carbonate to a mixture of 2-triphenylethane at a temperature of about 160-180° C. and normal pressure in the presence of a conventional carbonation catalyst. React for about 30 minutes under the following conditions, and gradually reduce the pressure for 2 hours to about 180~2
The precondensation was completed at 220° C. and 10 Torr. Thereafter, a reaction is carried out at 10 Torr, 270°C for 30 minutes, 5 Torr, 270°C for 20 minutes, and then 0.5 Torr or less, preferably 0.3 Torr to 0.5 Torr.
The diameter condensation is allowed to proceed for 1.5 to 2.0 hours at 270° C. under reduced pressure 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 hydroxide, 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-bottle flask, and add 1,1'-bis, (4. hydroxyphenyl)-meta-diisopropylbenzene, 1,1-
A pyridine solution of a mixture of bis-(4-hydroxyphenyl)cyclohexane and 4,4-dihydroxy-2.2.2-triphenylethane is added, and phosgene gas is introduced while stirring 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. For phosgene, use an empty air washing bottle and an air washing bottle containing paraffin (count the number of ponds)
, into the flask through an empty wash 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. Pass phosgene until the yellow color of the phosgene-hydrogen chloride complex disappears. After the reaction is complete, methanol is added to precipitate the polymer, which is then filtered and dried. The resulting polycarbonate is dissolved in methylene chloride, pyridine, chloroform, tetrahydrofuran, etc. Since it is soluble, it is purified by reprecipitation from these solutions with methanol.The polycarbonate copolymer thus obtained can be used to record a signal with a laser beam, or to read out a signal recorded by reflection or transmission of a laser beam. It is useful for DRAW and Erasabie-DRAW type optical information recording discs.The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples. The viscosity average molecular weight shown in the examples is obtained as the relational expression between the intrinsic viscosity [r1] and the molecular weight M by measuring using a methylene chloride solution of bisphenol A polycarbonate at 20°C [r11=1.11X10- 4MO-82[E.Mii1
1er&O. Bayer; USP 2,999,844 (
This is the molecular weight in terms of bisphenol A polycarbonate calculated from the intrinsic viscosity using the 1961 formula.

(Example) Example 1 1,1'-bis-(4-hydroxyphenyl), meta-
Diisopropylbenzene 166 parts by weight (40 mo1%)
and 161 parts by weight (50 mo1%) of 1,1-bis(4-hydroxyphenyl)cyclohexane, 353 t1 part (10 mo1%) of 4,4=dihydroxy-2,2,2-)diphenylethane, and 264 parts by weight of diphenyl carbonate. Place in a three-necked flask, degas, and purge with N2 for 5 hours.
After repeating this process several times, the mixture was melted in a silicon bath at 160° C. while introducing nitrogen.

Once melted, add 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),
The mixture was stirred and incubated at 160'C under N2 for 30 minutes. Next, the pressure was reduced to 1 QQ Torr at the same temperature and stirred for 30 minutes, and then the pressure was further reduced to 5 Q Torr at the same temperature and reacted for 60 minutes. Next, the temperature was gradually raised to 220°C and the reaction was carried out for 60 minutes.
After that, the pressure was reduced to 1Q Torr at the same temperature, and the reaction was allowed to proceed for 30 minutes. The temperature was gradually raised to 270°C, and 30
It was allowed to react for a minute. Furthermore, the pressure was reduced to 5 Torr at the same temperature.
The reaction was allowed to proceed for 0 minutes, and almost the entire theoretical amount of phenol was distilled out to complete the precondensation. Next, at the same temperature, 0. 1 to Q, tightened after 2 hours at 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. The viscosity average molecular weight Mv calculated from this value was 18,900. In addition, DSC (Diff 7L/Ncial Scanning Calorimeter; Perkin-Elmer
2C type), the glass transition point was found to be Tg=135°C. Furthermore, when the photoelastic constant was measured, C = 56 Brewsters (10"m2/N)
It turned out to be. The equipment used for measurement was a DSC.
; The photoelastic constant was measured using a differential scanning calorimeter Perkin-E1mer 2C model, which I made in-house.The method for calculating the photoelastic constant was to apply different magnitudes of tensile stress to a test piece (50 mm x 10 mm x 1 mm). They were added in the length direction, each value was substituted into the equation (1), and the photoelastic constant was determined from the slope. Incidentally, the photoelastic constant of the polycarbonate of 2,2-bis-(4-hydroxyphenyl)propane was C=82 Brewsters (10-12 m2/N).

Example 2 A three-hole flask is equipped with a stirrer, a thermometer, a gas inlet pipe, and an exhaust pipe. 1 in a 10% by weight aqueous solution of sodium hydroxide,
166 parts by weight (40 mo1%) of 1-bis-(4-hydroxyphenyl)-meta-diisopropylbenzene and 1,
161 parts by weight (50 mo1%) of 1-bis-(4-hydroxyphenyl)cyclohexane and 35 parts by weight of 4,4-dihydroxy-2,2,2-triphenylethane (10 m
1%) was dissolved, dichloromethane was added, and phosgene gas was introduced while stirring the solution 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 the introduction of phosgene gas was water-cooled to 256C or less. As the condensation progresses, the solution becomes viscous. Further, phosgene was passed through the mixture until the yellow color of the phosgene and hydrogen chloride complex 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 was Mv=19,800.

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 Characteristics) A recording film was attached to the polycarbonate copolymer produced as described above, and the optical recording characteristics were evaluated. That is, Example 1
, 2, using an injection molding machine (
130m in diameter using a Guina melter made by Multiki Seisakusho.
A sputtering device (RF sputtering device, manufactured by Japan Vacuum Co., Ltd.) was formed using a Tb23.5Fe64.2CO12,3 (atomic%) alloy target 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 is expressed as the CN ratio,
Evaluation was made based on BER and CN ratio change rate under conditions of 60° C. and 90 RH%. The results are shown in Table 1.

Table 1 (Note 1) CN ratio = writing power 7 mW (milliwatt), reading power 1 mW, carrier frequency 114 Hz
, measured at 30 KHz in the resolution band (Note 2) CN change rate (%) = Decrease in CN ratio after 30 days under conditions of 60°C and 90 RH% relative to the initial CN ratio (Raw 3) Comparative example = Conventionally known polycarbonate A magneto-optical disk was made using a substrate (AD-5503 manufactured by Ondai Kasei 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] 1,1'-bis-(4-hydroxyphenyl)-meta-
Diisopropylbenzene 2-60 mol%, 1,1-bis-(4-hydroxyphenyl)cyclohexane 2-70%
Aromatic polycarbonate copolymer obtained by bonding 2 to 90 mol% of 4,4'-dihydroxy-2,2,2-triphenylethane through carbonate bonds such that the total of each becomes 100 mol%. coalescence, the glass transition temperature of which is 125°C or higher, and the photoelastic constant of 60 Brewsters (Brewsters, 10^-^1^2m^2/N)
An aromatic polycarbonate terpolymer which is: