JPH0441550A - Optical polycarbonate resin 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 aliph. carboxylic acid. 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 5-1000ppm (based on the resin) aliph. carboxylic acid of which hydrogen atoms on the aliph. group may be substituted by OH groups (pref. adipic acid of tartaric acid). A molded article with a guaranteed long-term 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 resin 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 resin is 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. In some cases, it is better to adjust the molecular weight of the polymer to a relatively low value in order to improve moldability, to avoid contamination of foreign substances from the outside, and to sufficiently purify the resulting polymer to reduce the amount of solvent and other substances in the polymer. It is necessary to keep the contamination of accessory 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
There is a drawback in that when this master disc is held for a long time under high temperature and high humidity, minute defects with a diameter of several tens of microns are generated within 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, cause signal reading errors, etc.9), so their occurrence should be suppressed as much as possible. This is important.The cause of these point defects is not clear, but it is thought to be caused by partial hydrolysis of the polycarbonate resin.Therefore, various stabilizers are added to the polycarbonate resin. Although attempts have been made, to date no method has been found that can sufficiently suppress the above-mentioned point defects without impairing the optical function.

[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 a master disc for optical discs using polycarbonate molding material containing a certain compound, the resulting master disc is not colored, has good transparency, and has the above-mentioned points. It was found that almost no defects occurred.

That is, the gist of the present invention is to add 5 to 1000 ppm of an aliphatic carboxylic acid having 1 to 10 carbon atoms, in which the hydrogen atoms of the aliphatic groups may be substituted with hydroxyl groups, to the polycarbonate resin. An optical polycarbonate resin molding material characterized by the following:

The present invention will be explained in detail below.

The production method for the polycarbonate resin that is the subject of the present invention is not particularly limited. Usually, a dihydroxydiaryl compound and phosgene are mixed in a mixed solvent consisting of water and a halogenated hydrocarbon in the presence of an alkali. Examples include polymers obtained by reaction. Further, as the dihydroxydiaryl compound, a compound containing 2,2-his(4-hydroxyphenyl)propane [bisphenol A1 as a main component is typically typical.

In some cases, the polycarbonate-1 resin of the present invention may be a copolymer with other components.

The average molecular weight of the polycarbonate resin used in the present invention is usually a viscosity average molecular weight of 12,000-20,000, preferably 130, since precise molding is required for optical use.
It is 00-18000. The average molecular weight of the polycarbonate 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.

Furthermore, the polycarbonate resin used in the present invention needs to contain as little impurities as possible, such as foreign substances, reaction solvents, and by-product salts.

In the present invention, it is an essential requirement that an aliphatic carboxylic acid having 1 to 10 carbon atoms, preferably 3 to 8 carbon atoms, in which the hydrogen atom of the aliphatic group may be substituted with a hydroxyl group, is blended into the polycarbonate resin. It is something to do.

Monovalent, divalent or trivalent aliphatic carboxylic acids can be used, but monovalent or divalent ones are particularly preferred. Specific examples of these aliphatic carboxylic acids include, for example:
Examples include formic acid, acetic acid, propionic acid, adipic acid, succinic acid, fumaric acid, tartaric acid, citric acid, etc.
Adipic acid and tartaric acid are preferred.

It should be noted that higher fatty acids such as stearic acid and palmitic acid are not suitable for use as additives in the present invention because the effects of the present invention such as suppression of point defects are insufficient.

The amount of the additive of the present invention added to the polycarbonate resin is as follows:
5-1000 ppm, preferably 10
〇-800ppm, more preferably 20-700ppm
It is m. If this amount is too small, it will not be possible to sufficiently suppress the occurrence of point defects when the molded master is kept at high temperature and high humidity, while if it is too large, its properties as an optical substrate will deteriorate. This is not desirable as it will damage it.

In order to incorporate the additive of the present invention into the resin, it is necessary to add it to the resin before molding the optical molded article, and it is usually added to the resin in the form of powder or granules of polycarbonate resin, or pelletized products thereof. However, from the viewpoint of uniform dispersibility of the additive, it is preferable to add the additive to resin powder or granules, pelletize this, and then use it for molding into an optical molded article. 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 thermal stabilizers include, for example, trisnonylphenyl phosphite, tridecyl phosphite, di(monononylphenyl)
- Phosphite esters such as dinonylphenyl phosphite can be mentioned. In addition, suitable mold release agents include, for example,
Examples include stearic acid monoglyceride, behenic acid monoglyceride, pentaerythol monoglyceride, stearyl stearate, and pentaerythritol tetrastearate. 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 disk masters using a conventional method, for example, an injection molding machine.
Resin temperature) is usually 330-400°C. In addition, the injection pressure is usually 1000-2000 kg/
It is Cm2G.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1-9 and Comparative Example 1 [Manufacture of polycarbonate 1 13.5% aqueous solution of sodium salt of bisphenol A prepared by dissolving 100 parts by weight of bisphenol A in 640 parts by weight of 5.6% aqueous sodium hydroxide solution and methylene chloride 340 parts by weight of phosgene were mixed uniformly, and 48.
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. and 2.44 parts by weight of a 2% triethylamine aqueous solution were added thereto, and the mixture was stirred thoroughly at room temperature to perform interfacial polymerization, and the resulting mixture was separated into an aqueous phase and a methylene chloride phase.

The methylene chloride solution that dissolves the produced polycarbonate obtained here is thoroughly washed with water, ■ aqueous hydrochloric acid solution, and ■ water, and then it is poured into water at 45°C in a stirring device equipped with shear blades. The methylene chloride was volatilized and polycarbonate resin granules were precipitated. Then, this was separated and dried to recover polycarbonate resin.

The viscosity average molecular weight of this polycarbonate resin is 1450
0, and the total light transmittance was as good as 93%.

[Molding of optical disk master] Stearic acid monoglyceride is added to the polycarbonate resin recovered by the above method as a mold release agent.
100 ppm■ As a heat stabilizer, di(monononylphenyl)-mono(dinonylphenyl)-
Phosphite 00 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 iH degree to obtain polycarbonate resin pellets.

Using this pellet, an optical disk master (diameter 13
0 mm, thickness 1.2 mm) to obtain an optical disc master made of polycarbonate resin.

All of the optical disc masters obtained here have excellent transparency,
It was completely free of internal defects.

Bolicarbooto master discs obtained in this way (5 discs each)
A holding test was conducted under constant temperature and humidity, and the number of point defects after the test was determined, and the transparency of the master was evaluated. The results are shown in Table 1.

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 carrying out a holding test for 500 hours at a constant temperature and humidity of 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 and the degree of coloring and transparency when observed from the side were determined by the naked eye.

[Effect of the invention 1 According to the present invention, when producing an optical molded product made of polycarbonate resin, by adding a specific additive, the long-term stability of the molded product is guaranteed without impairing the transparency of the molded product. can do. For example, when a polycarbonate optical disk master is manufactured, even if it is kept under high temperature and high humidity for a long time, internal defects will hardly occur in the master. Therefore, when an optical disc is manufactured by forming an information recording film on this master disc, an optical disc with extremely high reliability can be obtained.

Claims (1)

[Claims] (1) Polycarbonate resin, 5-
A polycarbonate resin molding material for optical use, characterized in that it contains 1000 ppm of an aliphatic carboxylic acid having 1 to 10 carbon atoms in which the hydrogen atoms of the aliphatic groups may be substituted with hydroxyl groups.