JPH052703B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to polycarbonate resin optical molded products with extremely small birefringence variations, which are made using polycarbonate resin compositions that have excellent fluidity and virtually no variations in fluidity, such as optical molded products. Related to reading-type digital audio discs, video discs, memory discs, etc., and optical lenses. [Conventional technology and its problems] Conventionally, acrylic resin has been used as a material for optical transparent molded products because it has (1) good transparency, (2) good fluidity, and
(3) It is known that it has characteristics such as low birefringence and can be used as a material for transparent optical molded products (for example, JP-A-56-131654). However, acrylic resin has low heat resistance (approximately 70
℃), has low impact resistance, and may warp due to moisture. In order to eliminate the above-mentioned drawbacks, polycarbonate resins with a viscosity average molecular weight of 15,000 to 18,000 are being considered as molding materials for disks, lenses, etc. (Japanese Patent Application Laid-Open No. 180553/1983), but they have poor fluidity. However, it has drawbacks such as large birefringence, which is the most important factor for these applications, and there are still limits to its use. In particular, in precision optical systems used for reading and writing information using light such as lasers, it has been desired to develop a fracture optical material with lower birefringence. By the way, the birefringence of a resin optical transparent molded article changes depending on the characteristics of the material itself as well as the molding conditions. In other words, when molding a transparent optical molded product, the resin is melted and cooled in a mold to obtain the molded product. However, if the viscosity at the time of melting is high, the resin will be cooled unevenly, causing optical damage to the molded product. distortion remains, which appears as birefringence. In particular, in the case of injection molding, the resin is injected into the mold, so in a highly viscous state,
The orientation of the resin remains in the direction of flow, which tends to cause birefringence in the molded product. Therefore, as a means of relaxing the molding conditions, a conventionally well-known method can be considered, that is, a method of creating a highly fluid molding material by adding a plasticizer. When a sufficient amount of an olefin plasticizer or a phosphate ester plasticizer is added to improve moldability, fluidity will be good, but the mold will become dirty and the molded product will be contaminated. Alternatively, due to poor compatibility, the desired optical molded product may not be obtained due to poor appearance such as decreased transparency or an unacceptable decrease in physical properties. Therefore, the birefringence of optical transparent molded products has so far been reduced by relying on molding conditions (in particular, increasing the molding temperature) or by using low molecular weight polycarbonate resins with good fluidity. In addition, for applications with even higher fluidity, a polycarbonate resin with a lower molecular weight is used, but especially in the case of a low molecular weight polycarbonate resin with a viscosity average molecular weight of 13,000 to 14,500, the desired viscosity average molecular weight can be achieved by adding a terminal capping agent. It is extremely difficult to accurately control the molding conditions, and due to fluctuations in fluidity due to variations in molecular weight between manufacturing lots, it is necessary to change the molding conditions, or even when molding under the same molding conditions. These methods tend to cause problems such as variations in birefringence of the resulting molded product exceeding an allowable range, and also problems in mechanical properties. [Means for solving the problem] Therefore, the present inventors have worked hard to develop a reliable molding material that has good fluidity and no variation in fluidity, and therefore has extremely small changes in birefringence. As a result of investigation, it was discovered that this problem could be solved by a method of blending a polycarbonate resin oligomer with a polycarbonate resin, and the present invention was completed. That is, in the present invention, the viscosity average molecular weight is from 15,000 to
19,000 polycarbonate resin and 5 to 30 wt% of polycarbonate oligomer having an average of 2 to 15 repeating structural units, the viscosity average molecular weight of the mixture is in the range of 13,000 to 14,500, and the desired viscosity average molecular weight is This is a polycarbonate resin optical molded article formed by molding a polycarbonate resin composition in which the deviation of the branching agent is controlled within 3%. Viscosity average molecular weight using mol% is 15000-19000
This is a polycarbonate resin optically molded article obtained by molding a polycarbonate resin composition of a polycarbonate resin of 1.0 and a polycarbonate oligomer having an average of 2 to 15 repeating structural units. The configuration of the present invention will be explained below. First, the polycarbonate resin and polycarbonate oligomer of the present invention are produced in the same manner as ordinary aromatic polycarbonate resins and polycarbonate oligomers, and preferably a compound of the following general formula (1) as a dihydric phenol compound is used as a seed component. Used as phosgene or carbonic acid di general formula (1): (R in the formula is a divalent aliphatic, alicyclic, or phenyl-substituted alkyl group having 1 to 15 carbon atoms, or -0-, -S-, -SO-, -SO ₂ -, -CO -.X is an alkyl group, an aryl group, or a halogen atom, and p and q are integers of 0 to 2). It is made by reacting with an ester.
The viscosity average molecular weight of the aromatic homo- or co-polycarbonate resin used in the present invention is from 15,000 to
19,000, and the average value n of the repeating units of the aromatic homo- or copolycarbonate resin oligomer ranges from 2 to 15. As the dihydric phenol compound represented by the above general formula (1), bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)
Ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis( 4-
Hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-bis(4-
hydroxy-3-bromophenyl)propane,
2,2-bis(4-hydroxy-3-chlorophenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)propane
-Hydroxyphenyl) sulfone, bis(4-hydroxyphenyl) sulfoxide, bis(4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl)ketone, 1,1-bis(4-hydroxyphenyl)- Examples include 1-phenylethane and bis(4-hydroxyphenyl)diphenylmethane, with 2,2-bis(4-hydroxyphenyl)propane being particularly preferred. As the molecular weight regulator or terminal capping agent of the present invention, commonly used alkyl-substituted phenols such as para-tertiary butylphenol; para-long chain alkyl-substituted phenols such as octylphenol, laurylphenol, and stearylphenol; lauryl hydroxybenzoate; , para-hydroxyalkyl benzoates such as stearyl hydroxybenzoate; para-alkoxyphenols such as dodecyloxyphenol and octadecyloxyphenol. In addition, the branching agent used in the preferred embodiment is one that eliminates phenomena such as "grinding" when molded by methods such as injection molding, and eliminates brittle fracture due to bending of molded products. Such branching agents include phloroglycin, 2,6-dimethyl-2,4,6-tri(4-hydroxyphenyl)heptene-3,4,
6-dimethyl-2,4,6-tri(4-hydroxyphenyl)heptene-2,1,3,5-tri(2-hydroxyphenyl)benzole, 1,1,
1-tri(4-hydroxyphenyl)ethane,
2,6-bis(2-hydroxy-5-methylbenzyl)-4-methylfuphenol, α, α′, α″, -
Tri(4-hydroxyphenyl)-1,3,5-
Polyhydroxy compounds exemplified by triisopropylbenzene, 3,3-bis(4-hydroxyaryl)oxindole (=isatin bisphenol), 5-chloroisatin, 5,7
-Dichloroisatin, 5-bromiisatin, etc. are exemplified. Further, the amount used is in the range of 0.02 to 3 mol%, more preferably 0.05 to 1.0 mol% of the dihydric phenol used. The method of blending the polycarbonate oligomer with the polycarbonate resin is not particularly limited, and may include a method of blending a solution of both and removing the solvent to obtain a molding material, or a method of blending powder or pellets of both. good. The amount of polycarbonate oligomer to be added to the polycarbonate resin is determined by measuring the viscosity average molecular weight of both, and blending the amount of polycarbonate oligomer that will give the desired viscosity average molecular weight. On the other hand, it is usually in the range of 1 to 60 wt%, preferably 5 to 30 wt%, particularly 15 to 30 wt%. The "Q value" of the composition for optical molded articles of the present invention obtained by the above method is determined by the type of dihydric phenol used, the type and amount of the terminal stopper (viscosity average molecular weight), the amount of oligomer added, etc. For example, 2,2-bis(4-hydroxyphenyl)propane is used as the dihydric phenol, 6.42 mol% of para-tert-butylphenol is used as the end capper, and 2,6-dimethyl-2,
A polycarbonate resin with a viscosity average molecular weight of 15,500 obtained using 0.2 mol% of 4,6-tri(4-hydroxyphenyl)heptene-3, 2,2bis(4-hydroxyphenyl)propane, and terminal termination. paratertiary butylphenol as an agent
15 oligomers with n=7 obtained using 28.7 mol%
The Mv of the composition obtained by adding % is in the range of 13,800 to 14,200, and is controlled within an error of 3%. However, "Q value" is the melt viscosity measured with an elevated flow tester, and is expressed in units of cc/sec of the amount of molten resin flowing out from a 1 mmφ x 10 mmL nozzle at 280℃ and under a pressure of 160Kg/ ^cm2 . The flow value "Q value" increases as the melt viscosity decreases. The polycarbonate resin composition of the present invention as described above is molded to obtain a transparent polycarbonate resin optical molded article of the present invention. The molding method is usually a conventional method such as injection molding or compression molding. For injection molding, resin temperature 280
-360°C, preferably 320-340°C. [Example] Since the polycarbonate resin composition of the present invention has fluidity precisely controlled within a predetermined range, there is no variation between lots, and desired optical molded products can be obtained under predetermined conditions. This feature is described below using reference examples, examples, etc. Reference example 1 [Aromatic polycarbonate resin oligomer (n=
Production of 7)] In a reaction tank with an inner capacity of 400 g equipped with a stirrer, a phosgene gas blowing pipe, and a cooling jacket, 25 kg of a 48% by weight aqueous solution of caustic soda, 250 g of water, 60 g of methylene chloride, 100 g of hydrosulfite, and 2,
27.5 kg of 2-bis(4-hydroxyphenyl)propane (=BPA) was added one after another, and while maintaining the liquid temperature in the range of 15 to 20°C, 15 kg of phosgene was blown in for 30 minutes to cause a reaction. After that, 6 kg of 48% by weight caustic soda aqueous solution, 100 g of triethylamine, and p-tertiary butylphenol (=TBP) were added to the reaction system.
A solution of 5.2 kg dissolved in 50 methylene chloride was added, and stirring was continued for an additional 60 minutes. The settled methylene chloride tank was extracted and transferred to a purification phase with an internal capacity of 300 ml with a stirrer, and 100 ml of each
Neutralization was performed using a 1% aqueous phosphoric acid solution and washing with water was performed.
The content of the purified methylene chloride solution is 500.
The mixture was transferred to a solidification tank and heated under stirring with 300 ml of water to distill off methylene chloride. After cooling, the precipitate was filtered and dried to obtain 33.6 kg of aromatic polycarbonate oligomer powder. The melting point of the obtained polycarbonate oligomer is
The temperature was 229-232°C, the viscosity average molecular weight was 5×10 ³ , and the number average molecular weight was 2.0×10 ³ by end group analysis. Reference example [Aromatic polycarbonate resin oligomer (n=
10) Production] In the production method of Reference Example 1, the amount of phosgene was
14.6Kg, and 33Kg of aromatic polycarbonate oligomer powder was obtained in the same manner except that the TBP amount was changed to 3.6Kg. The melting point of the obtained polycarbonate oligomer is
The temperature was 235-238°C, the viscosity average molecular weight was 7×10 ³ , and the number average molecular weight was 2.9×10 ³ by end group analysis. Reference Example 3 [Production of terminal-modified aromatic polycarbonate resin oligomer (n = 10)] In the production method of Reference Example 1, the amount of phosgene was
36 kg of aromatic polycarbonate oligomer powder was obtained in the same manner except that lauryl p-oxybenzoate (=ROBP) was used instead of TBP and the additive was changed to 7.3 kg. The melting point of the obtained polycarbonate oligomer is
The temperature was 218-222°C, the viscosity average molecular weight was 7×10 ³ , and the number average molecular weight was 2.9×10 ³ by end group analysis. Reference Example 4 [Manufacture of branched aromatic polycarbonate resin] Dissolve 3.7 kg of sodium hydroxide in 42 kg of water,
BPA7.3Kg, 2,6-dimethyl-2,4,6-tri(4-hydroxyphenyl) while keeping at ℃
25 g of heptene-3 (=TPH) and 8 g of hydrosulfite were dissolved. To this was added 28 methylene chloride, 305 g of TBP was added while stirring, and 3.5 kg of phosgene was blown into the mixture over 60 minutes. After the phosgene injection was completed, the reaction solution was vigorously stirred to emulsify it, and after emulsification, 8 g of triethylamine was added and stirring was continued for about 1 hour to polymerize. Separate the polymerization solution into an aqueous phase and an organic phase, neutralize the organic phase with phosphoric acid, repeat washing with water until the pH of the washing solution becomes neutral, and then add 35% of isofuropanol to precipitate the polymer. I let it happen. The precipitate was filtered and then dried to obtain a white powdery polycarbonate resin. Next, this polycarbonate resin was extruded using a vented 40 mm extruder at a temperature of 240 to 260°C to obtain pellets. The viscosity molecular weight of this pellet determined from the intrinsic viscosity in a methylene chloride solution was 16,000. Reference Example 5 [Production of branched aromatic polycarbonate resin] A branched aromatic polycarbonate resin was obtained in the same manner as in Reference Example 4 except that the amount of TBP was changed to 270 g. The viscosity average molecular weight of the branched aromatic polycarbonate resin was 18,000. Reference example 6 [Manufacture of ordinary aromatic polycarbonate resin] Dissolve 3.7 kg of sodium hydroxide in 42 kg of water,
While maintaining the temperature at °C, 7.3 kg of BPA and 8 g of hydrosulfite were dissolved. To this was added 28 methylene chloride, 305 g of TBP was added while stirring, and 3.5 kg of phosgene was blown into the mixture over 60 minutes. After the phosgene injection was completed, the reaction solution was vigorously stirred to emulsify it, and an emulsifier, 8 g of triethylamine, was added thereto, and stirring was continued for about 1 hour for polymerization. Separate the polymerization solution into an aqueous phase and an organic phase, neutralize the organic phase with phosphoric acid, repeat washing with water until the pH of the washing solution becomes neutral, and then add 35% of isopropanol to precipitate the polymer. I let it happen. The precipitate was filtered and then dried to obtain a white powdery polycarbonate resin. Next, this polycarbonate resin was extruded using a vented 40 mm extruder at a temperature of 240 to 260°C to obtain pellets. The viscosity average molecular weight of this pellet determined from the intrinsic viscosity in a methylene chloride solution was 16,000. Comparative Example 1 [Manufacture of ordinary aromatic polycarbonate resin] Dissolve 3.7 kg of sodium hydroxide in 42 kg of water,
While maintaining the temperature at °C, 7.3 kg of BPA and 8 g of hydrosulfnite were dissolved. Methylene chloride 28 was added to this, and while stirring, 346 g of TPB (target molecular weight 14,000) was added, and 3.5 kg of phosgene was blown in over 60 minutes. After the phosgene injection was completed, the reaction solution was vigorously stirred to emulsify it, and an emulsifier, 8 g of triethylamine, was added thereto, and stirring was continued for about 1 hour for polymerization. Separate the polymerization solution into an aqueous phase and an organic phase, neutralize the organic phase with phosphoric acid, repeat washing with water until the pH of the washing solution becomes neutral, and then add 35% of isopropanol to precipitate the polymer. I let it happen. The precipitate was filtered and then dried to obtain a white powdery polycarbonate resin. Reaction and polymerization were carried out in 10 batches under exactly the same conditions. Next, these 10 types of polycarbonate resins were each extruded using a vented 40 mm extruder at a temperature of 240 to 260°C to obtain pellets. The viscosity average molecular weight determined from the intrinsic viscosity of these 10 types of pellets in methylene chloride solution is
It was in the range of 13,200 to 14,900, and the deviation from the target viscosity average molecular weight was about 10%. Examples 1 to 3 and Comparative Example 1 The pellets obtained in Reference Examples 1 to 6 were mixed in the ratios shown in Table 1 to produce extruded pellets. This operation was repeated 10 times. The "viscosity average molecular weight" and "Q value" of these pellets are shown in Table 1 as Examples 1 to 3. Further, the pellets obtained in Comparative Example 1 were also shown in the same manner. After drying these pellets at 120°C for 4 hours, they were molded using a compact disc mold at a resin temperature of 340°C, a mold temperature of 90°C, an injection pressure of 1000 kg/cm ² , and a holding pressure of 300 kg/cm ² . Injection molding of a disc with an outer diameter of 120 mm and a thickness of 1.2 mm (injection molding machine, manufactured by Sumitomo Heavy Industries, Ltd.;
Neo mats 350/120 (with SYCAP), 48 after molding
The birefringence of the molded product over time was measured. Birefringence was measured using a polarizing microscope (Olympus Optical Co., Ltd.)
Using a POM type polarizing microscope (manufactured by POM), arbitrary points on the circumference of R = 24 mm, R = 42 mm, and R = 56 mm were selected from the center of the disk. The results are shown in Table 2.

【table】

[Operation and effects of the invention]

As described above, the polycarbonate resin optical molded product produced by the manufacturing method of the present invention has extremely small variations in the fluidity of the molding material, extremely small variations in birefringence under the same molding conditions, and also has other variations. It is clear that molded products with stable mechanical properties and the like without the occurrence of small defects can always be obtained, and that they have both good physical properties and productivity.

Claims (1)

[Claims] 1. A polycarbonate resin having a viscosity average molecular weight of 15,000 to 19,000, containing 5 polycarbonate oligomers having an average of 2 to 15 repeating structural units.
~30 wt%, the viscosity average molecular weight of the mixture is in the range of 13,000 to 14,500, and the deviation from the desired viscosity average molecular weight is controlled within 3%. A polycarbonate resin obtained by molding a polycarbonate resin composition. Optical molded products. 2. The polycarbonate according to claim 1, wherein the polycarbonate resin having a viscosity average molecular weight of 15,000 to 19,000 is obtained by using a branching agent in an amount of 0.02 to 3 mol% based on a dihydric phenol compound. Resin optical molded products.