JPH0441553A - Optical molding material - Google Patents

Abstract

PURPOSE:To prepare the title material having an excellent transparency and enabling the production of an optical master having no internal defect by compounding a polycarbonate resin with a small amt. of a specific phenol compd. CONSTITUTION:The title material is prepd. by compounding a polycarbonate resin (e.g. a polymer obtd. by reacting a dihydroxydiaryl compd. such as bisphenol A with phosgene in the presence of an alkali in a mixed solvent comprising water and a halogenated hydrocarbon) with 100-200ppm (based on the resin) phenol compd. of which hydrogen atoms on the benzene ring may be substituted by lower alkyl groups or halogen atoms (e.g. p-di-tert-butylphenol). A molded article with a guaranteed long-team stability can be produced from the material without degrading transparency. For instance, when the compsn. is used for producing a master for a polycarbonate optical disc, the master has scarcely any internal defect even when kept at high temp. and humidity for a long time, enabling the production of an extremely reliable optical disc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical polycarbonate resin molding material, and more specifically, it is capable of producing an optical polycarbonate base that has excellent transparency and is free from internal defects. This invention relates to polycarbonate molding materials.

[Prior Art 1] Polycarbonate resin has excellent transparency, heat resistance, and dimensional stability, and is therefore known to be used as an optical base for optical discs, lenses, prisms, and the like. These optical substrates are required to be free from coloration, highly transparent, and free from foreign matter and internal defects (scratches) for boat fishing.

On the other hand, polycarbonate resins are usually produced by reacting a dihydroxydiaryl compound such as bisphenol A with phosgene in the presence of an alkali in a mixed solvent consisting of water and a halogenated hydrocarbon, or are produced by making polycarbonate resins for optical use. In the case of non-polymerized polymers, in addition to adjusting the molecular weight of the bomber to a relatively low value to improve moldability, avoiding contamination of foreign substances from the outside, and sufficiently refining the resulting polymer, it is possible to It is necessary to keep the contamination of solvents and secondary salts as low as possible.

[Problems to be Solved by the Invention] However, when a master disc for an optical disk is manufactured by, for example, an injection molding method using the polycarbonate resin manufactured in this way, there is no problem with the master disc immediately after molding, but
When this master disc is held for a long time under high temperature and high humidity, there is a drawback in that minute defects with a diameter of several tens of microns are generated in the master disc.

Although these point defects are minute and occur in small numbers, they affect the reliability of recorded information when used as optical discs (for example, signal reading errors), so their occurrence should be suppressed as much as possible. This is very important. Although the cause of this point defect is not clear, it is thought to be caused by partial hydrolysis of the polycarbonate resin. Therefore, attempts have been made to add various stabilizers to polycarbonate resin, but so far no method has been found that can sufficiently suppress the above-mentioned point defects without impairing the optical function. do not have.

[Means for Solving the Problems 1] In view of the above-mentioned circumstances, the present inventors have developed a method that can suppress the occurrence of point defects even when an optical disc master made of polycarbonate resin is kept at high temperature and high humidity for a long time. As a result of extensive research, we have found that when molding optical disc masters using a polycarbonate molding material containing a certain compound, the resulting master is not colored, has good transparency, and does not have the above-mentioned dots. It was found that almost no defects occurred.

That is, the gist of the present invention is characterized in that 10-200 ppm of a phenol compound in which the hydrogen atom of the benzene ring may be substituted with a lower alkyl group or a halogen atom is blended into the polycarbonate resin. It consists of optical polycarbonate resin molding materials.

The present invention will be explained in detail below.

The production method for the polycarbonate resin targeted by the present invention is not particularly limited, but usually, a dihydroxydiaryl compound and phosgene are mixed in a mixed solvent of water and a halogenated hydrocarbon in the presence of an alkali. Examples include polymers obtained by reaction. Further, as the dihydroxydiaryl compound, 2,2-bis(4-hydroxyphenyl)propane [having bisphenol Al as the main component is typically used as a typical dihydroxydiaryl compound. In some cases, the polycarbonate resin of the present invention may be a copolymer with other components.

Since precise molding is required for optical use, the average molecular weight of the polycarbonate resin used in the present invention is usually
Viscosity average molecular weight 12000-20000, preferably 1
It is 3000-18000. The average molecular weight of the polycarbonate-1 resin can be adjusted according to a conventional method, for example, by adding a known terminal capping agent such as phenol or P-tert-butylphenol to the polymerization system.

In addition, the polycarbonate resin used in the present invention needs to have as low a content of impurities as possible, such as reaction solvents and by-product salts.

In the present invention, it is an essential requirement that a phenol compound in which the hydrogen atom of the benzene ring may be substituted with a lower alkyl group or a halogen atom is added to the polycarbonate-1 resin.

As the phenol compound of the present invention, phenol-0-1
-S-1 or direct bond. R represents a lower alkyl group or a halogen atom, n represents an integer of 0 to 5, and m represents an integer of 0 to 4. ), but bisphenols are particularly preferred. The lower alkyl group usually has 1 to 4 carbon atoms.

Specific examples of phenolic compounds include phenol, methylphenol, catechol, resorcinol, /\
Butylparahen, 2-t-butylhydroquinone, P-di-t-butylphenol, glycitur, 2,2-bis(4-hydroxyphenyl)propane [bisphenol Al, 2,2-bis(3,5-dibromo-4-hydroxy) Examples include phenyl)propane.

The amount of the additive of the present invention added to the polycarbonate resin is as follows:
10-200 ppm, preferably 30 ppm on resin
-100 ppm. If the amount is too small, the occurrence of defects cannot be sufficiently suppressed, while if it is too large, the properties as an optical substrate will be impaired, which is not preferable.

The method of blending the additive of the present invention into the resin requires adding it to the resin before the process of molding the optical molded article, and it is usually added to polycarbonate resin powder or granules, or pelletized products thereof. However, from the viewpoint of uniform dispersibility of the additives, it is preferable to add the additives to resin powder or granules, pelletize the resulting pellets, and then use the pellets for molding into optical molded articles. The mixing treatment can be carried out by adding a predetermined amount of the additive to the polycarbonate resin using a conventional mixer, or by supplying the predetermined amount of the additive together with the resin into the hopper of a pelletizer or molding machine. Further, the additive of the present invention can be supplied as a powder or an aqueous solution, but when adding an aqueous solution, it is usually necessary to take care that the water content in the resin does not exceed 5000 ppm.

In the present invention, the above-mentioned additives are blended into the polycarbonate resin, but if necessary, additives such as a heat stabilizer and a mold release agent may also be blended.

However, in the case of the present invention, it is not desirable to use too many additives, and it is preferable to use the minimum required amount of other additives that do not adversely affect the quality of the optical molded product. Suitable heat stabilizers include, for example, trisnonylphenyl phosphite, tridecyl phosphite, di(
Examples of suitable mold release agents include stearic acid monoglyceride, behenic acid monoglyceride, pentaerythritol monoglyceride, stearyl stearate, pentaerythritol tetrastearate, etc. Examples include rates. All of these additives need to be of high purity and, in some cases, need to be purified before use.

The polycarbonate molding material of the present invention can be used to produce optical molded products such as optical discs and discs using an injection molding machine according to a conventional method, but the molding temperature (resin, temperature) at this time is , typically 330-400°C. In addition, the injection pressure is usually 1000-2000 kg
/ am2G.

[Example] Next, the present invention will be explained in more detail by giving examples.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1-2 and Comparative Example 1 [Manufacture of polycarbonate 1 A 13.5% aqueous solution of sodium salt of bisphenol A prepared by dissolving 100 parts by weight of bisfuconol A in 640 parts by weight of a 5.6% aqueous sodium hydroxide solution. 340 parts by weight of methylene chloride was mixed uniformly, and 48 parts by weight of phosgene was added to the mixture.
．． 7 parts by weight was introduced and the reaction was carried out at room temperature to produce an oricomer.

Next, the reaction mixture containing the oligomer was separated into an aqueous phase and a methylene chloride phase, and the methylene chloride phase was mixed with 270 parts by weight of methylene chloride, 160 parts by weight of a 5% aqueous sodium hydroxide solution, and 3.95 parts by weight of P-tert-butylphenol. After adding 2.44 parts by weight of 2% triethylamine aqueous solution and stirring vigorously in a chamber or on a plate to perform interfacial polymerization, the resulting mixture was separated into an aqueous phase and a methylene chloride solution. A solution of methylene chloride was mixed with water, ■ aqueous sulfuric acid solution, and water for 1 minute using a tip yarn, and then stirred with a shearing blade. By discharging water at 45°C in the device, methylene chloride was introduced and polycarbonate resin granules were precipitated (q-).Then, this was separated and dried to recover the polycarbonate resin. two.

The viscosity average molecular weight of this polycarbonate resin is 145
00, and the total light transmittance was good at 93%.

[Molding of optical disc master] To the polycarbonate resin recovered by the above method, ■ Stearic acid monoglycenolyte was added as a mold release agent.
100ppm
■As a heat stabilizer, cy(monononylphenyl)-mono(
dinonylphenyl)-phosphite 100 ppm ■The additives shown in Table 1 were mixed uniformly, and melt-kneaded, extruded, and cut using a 40 mm diameter pelletizer at 270°C and 1H to form polycarbonate. A resin pellet was obtained.

Using these pellets, an optical disc master (diameter 130 mm, thickness 1.2 mm) was molded using a disc injection molding method at a molding resin temperature of 370°C, and an optical disc master made of polycarbonate resin was molded. I got it.

All of the optical disc masters obtained here have excellent transparency,
There were no internal defects.

The polycarbonate master discs obtained in this way (5 discs each) were subjected to a holding test under constant temperature and humidity, the number of point defects after the test was determined, and the transparency of the master discs was evaluated. Shown in the table/62.

Note that the number of point defects and transparency were determined by the following method.

1) Measurement of the number of point defects Five polycarbonate masters obtained by injection molding were heated to a temperature of 8
After 500 hours of holding test under constant temperature and humidity at 5°C and 85% humidity, count the total number of point defects of 20 microns or more that occurred in all test masters, divide this by 5, and calculate the number of defects per disk. The average number is shown.

2) Transparency Five polycarbonate master discs after the retention test in 1 above were stacked together, and the degree of coloring and transparency when observed from the side were determined by the naked eye.

Table 1 Even if the master is held, there are almost no inner-hole defects in the master.

Therefore, when an optical disc is manufactured by forming an information recording film on this master disc, an extremely highly reliable optical disc can be obtained. .

Book 1) TBA: 2,2-bis(3,5-syphromo-4-hydroxyphenyl $2,) BPA: 2,2-bis(4-hydroxyphenyl)propane [Effect of the invention 1 According to the present invention, polycarbonate When producing optical molded articles made of resin, by adding specific additives, the long-term stability of the molded articles can be guaranteed without impairing the transparency of the molded articles. For example, when manufacturing a polycarbonate optical disk master, it is exposed to high temperature
Long hours at the bottom, 1M people E-Ryo Kasei Co., Ltd.

Claims (1)

[Claims] (1) Polycarbonate resin, with respect to the resin, 10
- 200 ppm of a phenol compound in which the hydrogen atom of the benzene ring may be substituted with a lower alkyl group or a halogen atom.