JP2655845B2 - Optical glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a homopolymer comprising only 3,4 '-(1-methylethylidene) bisphenol (hereinafter, referred to as 3,4'-bisphenol A). Also, the present invention relates to an optical glass obtained by molding a polycarbonate resin having no crystallinity, a small light scattering property, and excellent heat stability and transparency, using 3,4'-bisphenol A and various bisphenols as dihydric phenol components. .

(Problems to be Solved by the Prior Art and the Invention) A polycarbonate resin derived from 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A) is excellent in transparency, heat resistance, impact resistance and the like. It is widely used as a material for optical glass. However, it has become clear that polycarbonate has some disadvantages such as crystallization tendency during processing and crystallization accompanied by whitening by a crystallization solvent in a thermal stability test. Also,
Considering optical fiber as one of optical materials, manufacturing, processing,
It is necessary that crystallization does not occur under the conditions used.

In a precision optical system used for reading and writing of information by light using a laser or the like, birefringence of an optical element is a serious problem.

In optical disk substrates, when writing or erasing information, the laser output is much higher than during reproduction and instantaneously rises to a temperature higher than the melting point of the substrate resin. , Causing new occurrence of birefringence.

(Means for Solving the Problems) The present inventors have conducted intensive studies to eliminate the disadvantages of 2,2-bis (4-hydroxyphenyl) -propane-based polycarbonate as described above. The inventors have found that the object is achieved, and have reached the present invention.

That is, the present invention provides A repeating unit (I) represented by the formula: (Wherein X is a single bond, alkylene having 1 to 6 carbons, alkylidene having 2 to 6 carbons, −S−, −SO ₂ −, R _{1 to} R ₄ each represent a hydrogen atom, an alkyl group, an aryl group, or a halogen atom. ) Having a repeating unit (II) represented by the following formula, wherein the repeating unit (I) has a molar fraction of 5 to 100% and a viscosity-average molecular weight in terms of bisphenol A type polycarbonate) of 5,000
It is an optical glass formed by molding a polycarbonate polymer having a low crystallinity, a small light scattering property, and excellent heat stability and transparency.

In addition, bisphenol A type polycarbonate conversion means
Relational formula between intrinsic viscosity and viscosity average molecular weight of bisphenol A type polycarbonate [η] = 1.11 × 10 ^-4 (Mv)
^It means the viscosity average molecular weight of the polycarbonate calculated using ^0.82 .

The present invention relates to the present invention, wherein the repeating unit (I) has a mole fraction of 5 to 10
0% and relates to a polycarbonate polymer having no crystallinity and consisting of the obtained polycarbonate polymer.

The molar ratio of the repeating unit (I) is preferably 5 to 100%. When the molar fraction of the repeating unit (I) is less than 5%, it is difficult to obtain a polycarbonate copolymer having no crystallinity.

The viscosity average molecular weight of the copolymer of the present invention is 5,000 to 100,000
However, 12,000 to 50,000 is preferred for the following reasons. If it is less than 12,000, the copolymer becomes brittle, and if it exceeds 50,000, it is presumed that the fluidity of the copolymer decreases and moldability tends to deteriorate.

 Further, the third component can be copolymerized.

There are the following two methods for producing the polycarbonate copolymer of the present invention.

Transesterification method A mixture of 3,4'-bisphenol A and various bisphenols is converted to a stoichiometrically slightly excess diphenyl carbonate in the presence of a normal carbonation catalyst.
The reaction is carried out at a temperature of 160-180 ° C under normal pressure and with an inert gas introduced for about 30 minutes, and finally at a temperature of 180-220 ° C while gradually reducing the pressure over about 2 to 3 hours. 10Torr, 220
Terminate the precondensation at ℃. After that, 30 Torr at 10 Torr and 270 ° C
Reaction at 270 ° C for 20 minutes at 5 Torr, then 0.5 Torr or less,
Preferably under a reduced pressure of 0.3 Torr to 0.1 Torr, at 270 ° C. for 1.5
After about 2.0 hours, the condensation proceeds. In addition, as a carbonate conversion catalyst for a carbonate bond, a lithium catalyst, a potassium catalyst, a sodium catalyst, a calcium catalyst,
Suitable are alkali metal and alkaline earth metal catalysts such as tin catalysts, for example, lithium hydroxide, lithium carbonate, potassium borohydride, potassium hydrogen phosphate, sodium hydroxide, sodium borohydride, calcium hydride, dibutyl. Tin oxide and stannous oxide.

Of these, it is preferable to use a potassium-based catalyst.

Phosgene method Stirrer, thermometer, gas inlet tube,
Attach exhaust pipe. A mixture of 3,4'-bisphenol A and various bisphenols is dissolved in an aqueous sodium hydroxide solution, dichloromethane is added, and phosgene gas is introduced while stirring vigorously. However, since phosgene is highly toxic, it is operated in a strong draft. In addition, a unit that decomposes and detoxifies excess phosgene with an aqueous solution of 10% sodium hydroxide is installed at the exhaust end. Phosgene is introduced into the flask through a gas bottle from a cylinder, a gas bottle containing paraffin (counting the number of bubbles), or an empty gas bottle. The gas inlet tube should be inserted above the stirrer, and the tip should be expanded in a funnel shape. The contents become cloudy with the introduction of gas.
Water cooling is performed so that the reaction temperature becomes 30 ° C. or less. It becomes viscous as the condensation progresses. After the reaction is completed, methanol is added to precipitate a polymer, which is separated by filtration and dried. The resulting polycarbonate is soluble in methylene chloride, pyridine, chloroform, tetrahydrofuran and the like, and is purified by reprecipitation from these solutions with methanol.

The polycarbonate copolymer thus obtained is a polymer having no crystallinity.

 Hereinafter, the content of the invention will be specifically described with reference to examples.

The measuring method of the items used for evaluating the polycarbonate obtained by the present invention is as follows.

-Evaluation method of yellow index Dissolve 0.5 g of sample with methylene chloride and adjust to 10 ml.
The adjusted sample was placed in a UV cell (10 × 10 × 45 mm ³ ), and the spectrophotometer UV-240 (manufactured by Shimadzu Corporation) was used to adjust the sample to 380 nm.
The absorbance (A) at 580 nm was measured. The yellow index was determined by the following equation.

Yellow index = A _380nm- A _580nm , viscosity average molecular weight 20 ° C, intrinsic viscosity [η] (g / dl) of methylene chloride solution is measured using a Ube-Rohde viscometer, and viscosity average molecular weight is calculated using the following formula. Mv was calculated.

[Η] = 1.11 × 10 ^-4 (Mv) ^0.82・ Evaluation method for heat resistance
Place it on a Teflon sheet in a hot-air circulation type thermostat set at 60 ° C, sample after 10 days, 20 days, 30 days of heating time,
The weight loss rate and viscosity average molecular weight were determined to evaluate the deterioration of the sample due to heat aging.

The weight loss rate Δwt% is I asked more. As the initial weight, the weight of a sample obtained by drying the above hot press sheet with a hot air circulating dryer at 120 ° C. for 4 hours was used.

・ Evaluation method of hydrolysis resistance Prepare a 50 × 50 × 0.6mm thick sheet by hot pressing
In a thermo-hygrostat controlled at 0 ° C. and 100% relative temperature, deterioration of the sample due to hydrolysis was measured over time with respect to viscosity average molecular weight and change in sheet appearance. The percentage of the viscosity average molecular weight of the initial viscosity average molecular weight after 30 days of the hydrolysis test was referred to as the hydrolysis viscosity average molecular weight retention (%) for 30 days, and was used as a measure of the hydrolysis resistance together with the change in the sheet appearance after 30 days.

-Measurement of the crystallinity of the polymer The crystallinity of the sample after the heat aging resistance test at 160 ° C for 30 days is determined from the melting peak area by DSC (heating rate 20 ° C / min). However, 100% crystallized bisphenol A polycarbonate has a heat of fusion of 26.2 cal / g (JPMercier a
nd R. Legras, J. Polymer Sci. Lett. Ed. 8 645 (1970))
And the heat of fusion of indium used as a standard was 6.87 cal /
g was determined from the area ratio to standard indium.

-Surface hardness evaluation method It was determined according to the evaluation method of JIS-K-5401.

(Example) Example 1 55 parts by weight (20 mol%) of 3,4'-bisphenol A, 219 parts by weight (80 mol%) of bisphenol A and 264 parts by weight of diphenyl carbonate were put into a three-liter three-necked flask and degassed and purged with N ₂ . After repeating five times, the mixture was melted in a silicon bath at 160 ° C. while introducing nitrogen. When molten, potassium borohydride as a carbonate catalyst was dissolved in phenol in advance (10 ^{-3 based on the} total amount of bisphenol charged).
mol%), and the mixture was stirred and brewed at 160 ° C. under N ₂ for 30 minutes. Next, after stirring at 10 Torr at the same temperature, the mixture was further stirred at the same temperature for 5 Torr.
The pressure was reduced to 0 Torr, and the reaction was performed for 60 minutes. Then gradually increase the temperature to 220
The reaction was carried out for 60 minutes, and 80% of the theoretical phenol distillation amount was distilled off by the reaction up to this point. Then, at the same temperature, 10
Reduce the pressure to Torr and react for 30 minutes, gradually raise the temperature to 270 ° C.
The reaction was performed for 0 minutes. Further, at the same temperature, the pressure was reduced to 5 Torr, and the reaction was carried out for 30 minutes. Next, the mixture was post-condensed at 0.1 to 0.3 Torr for 2 hours at the same temperature. After removing and cooling the product polymer under nitrogen, the solution viscosity was measured at 20 ° C. using dichloromethane. The viscosity average molecular weight calculated from this value is Mv
= 25,300.

Example 2 Except for using 3,4'-bisphenol A 137 parts by weight (50 mmol%) and bisphenol A 137 parts by weight (50 mol%),
Polymerization of the copolymerized polycarbonate was carried out in the same manner as in Example 1.

Mv = 22,700.

Example 3 A copolymerized polycarbonate was polymerized in the same manner as in Example 1, except that 164 parts by weight (60 mol%) of 3,4'-bisphenol A and 110 parts by weight (40 mol%) of bisphenol A were used.

Mv = 22,600.

Example 4 A copolymerized polycarbonate was polymerized in the same manner as in Example 1 except that 274 parts by weight (100 mol%) of 3,4'-bisphenol A was used.

Mv = 21,400.

Comparative Example Bisphenol A274 parts by weight and diphenyl carbonate
After 264 parts by weight were put into a three-necked flask and degassing and N ₂ purging were repeated 5 times, the mixture was melted in a silicon bath at 160 ° C. while introducing nitrogen. When melted, a solution of potassium borohydride, a carbonate catalyst, previously dissolved in phenol (10 ^-3 mol% based on the total amount of bisphenol charged)
Was added and the mixture was stirred and brewed at 160 ° C. under N ₂ for 30 minutes. Next, the mixture was stirred at the same temperature at 100 Torr for 30 minutes.
The pressure was reduced to rr 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. In the reaction so far, 80% of the theoretical amount of phenol was distilled off. After that, 10 To at the same temperature
Reduce to rr and react for 30 minutes, gradually raise the temperature to 270 ° C.
Minutes. Further, at the same temperature, the pressure was reduced to 5 Torr, and the reaction was carried out for 30 minutes. Next, the mixture was post-condensed at 0.1 to 0.3 Torr for 2 hours at the same temperature. After removing and cooling the product polymer under nitrogen, the solution viscosity was measured at 20 ° C. using dichloromethane. The viscosity average molecular weight calculated from this value is Mv
= 22,400.

 Table 1 summarizes the properties of these examples and comparative examples.

(Effect of the Invention) As can be seen from Table 1, 3,4'-bisphenol A
The copolymer or homopolycarbonate using, compared to polycarbonate from bisphenol A, the polymer has no crystallinity, good transparency in the heat aging test,
The yellow index confirms the low coloration. In addition, the surface hardness is higher in three stages from 2B to H, indicating that scratches and the like are not easily formed.

The optical glass of the present invention obtained by forming a polycarbonate using 3,4'-bisphenol A can be, for example, a lens,
It is useful as a prism, optical fiber, optical waveguide, or optical disk.

Claims (1)

(57) [Claims] (1) It has a repeating unit represented by the following formulas (I) and (II), and the repeating unit (I) has a mole fraction of 5 to 10:
An optical glass obtained by molding a polycarbonate polymer having a viscosity average molecular weight of 5,000 to 100,000 in terms of a viscosity average molecular weight (in terms of bisphenol A type polycarbonate) of 5,000 to 100,000. (Wherein X is a single bond, alkylene having 1 to 6 carbons, alkylidene having 2 to 6 carbons, −S−, −SO ₂ −, R _{1 to} R ₄ each represent a hydrogen atom, an alkyl group, an aryl group, or a halogen atom).