JPH0441552A - Optical polycarbonate molding compound - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical polycarbonate molding material, and more specifically, a polycarbonate that has excellent transparency and can produce an optical polycarbonate base free of internal defects. It relates to molding materials.

[Prior Art 1] Since polycarbonate resin has excellent transparency, heat resistance, and dimensional stability, it is known to be used as an optical substrate for, for example, optical discs, lenses, and brisms. These optical substrates are required to be highly transparent (not colored and free of foreign matter or internal defects) for boat fishing.

On the other hand, polycarbonate resins are usually produced by reacting a dihydroxidine aryl 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 In the case of polycarbonate, improve moldability.
t: In addition to adjusting the molecular weight of the Bommer to a relatively low value, we also avoid the contamination of foreign substances from the outside, and thoroughly purify the resulting polymer to minimize the contamination of solvents and by-product salts into the polymer. It is necessary to keep it low.

[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 this There is a drawback in that when the master disc is held at high temperature and high humidity for a long time, 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, 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 Problem 1) In view of the above-mentioned circumstances, the present inventors have developed a method that can suppress the occurrence of point defects even if 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 to add polycarbonate resin to the polycarbonate resin.
5-11000pp per l- to the resin (7) Optical use characterized by blending an aromatic carboxylic acid in which the hydrogen atom of the aromatic ring may be substituted with a lower alkyl group, hydroxyl group or halogen atom Exists in polycarbonate 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, one whose main component is usually 2,2-bis(4-hydroxyphenyl)propane [bisphenol A] is typical. In some cases, the polycarbonate resin of the present invention may be a copolymer with other components.

Average molecule -u of polycarbonate resin used in the present invention
Since ε requires precise molding for optical use, it is usually
Viscosity average outside P amount 12000-20000, preferably 1
It is 3000-18000. 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 aromatic carboxylic acid in which the hydrogen atom of the aromatic ring may be substituted with a lower alkyl group, a hydroxyl group, or a halogen source r is blended into the polycarbonate resin.

The aromatic carboxylic acid of the present invention usually has an aromatic ring such as a benzene ring or a naphthalene ring substituted with a carboxyl group, or a lower alkyl group, a hydroxyl group, or a halogen atom as a substituent that does not have any other adverse effects. (Preferably a bromine atom or a chlorine atom) may be substituted as a nucleus. A lower alkyl group usually has 1 to 4 carbon atoms. Further, the aromatic carboxylic acid may be monovalent to trivalent carbonic acid, but divalent or trivalent carboxylic acid is usually preferred.

Specific examples of these aromatic carbonic acids include benzoic acid, e-aroic acid, drooxybenzoic acid, bromobenzoic acid, methylammonic acid, phthalic acid, terephthalic acid, isophthalic acid,
Examples include trimellitic acid, trimesic acid, naphthoic acid, natutaledicarphonic acid, and in particular, terephthalic acid,
Isophthalic acid, trimellitic acid and trimesic acid are preferred.

The amount of the additive of the present invention added to the polycarbonate resin is as follows:
5-1000 ppm, preferably 10
-800 ppm, more preferably 20-700 ppm
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.

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 necessary amount of other additives that do not adversely affect the quality of the optical molded product.

Suitable thermal stabilizers include, for example, phosphorous esters such as trisnonylphenyl phosphite, tridecyl phosphite, di(monononylphenyl)-dinonylphenyl phosphite, and the like. Suitable mold release agents include, for example, stearic acid monoglyceride, behenic acid monoglyceride, pentaerythritol monoglyceride, stearyl stearate, pentaerythritol tetrastearate, and the like. 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/
cm2G.

[Example J 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 1-5 and Comparative Example 1 [Production of polycarbonate] A 13.5% aqueous solution of sodium salt of bisphenol A prepared by dissolving 00 parts by weight of bisphenol Al in 640 parts by weight of a 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 oligomer.

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 interfacial polymerization was carried out by stirring vigorously in a room under the syrup.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 was thoroughly washed with water, ■ aqueous hydrochloric acid solution, and ■ water. By releasing it into the water,
Methylene chloride was stirred in a loincloth to precipitate polycarbonate resin granules. Then, this was separated and dried to recover polycarbonate and resin.

The viscosity average molecular weight of this polycarbonate resin is 14
500, and the total light transmittance was good at 93%.

[Molding of optical disk master 1] Stearic acid monoglyceride was added to the polycarpoint resin recovered by the above method as a mold release agent.
100 ppm■ As a heat stabilizer, di(monononylphenyl)-mono(dinonylphenyl)-
Phosphite 100 ppm ■ The additives shown in Table 1 were mixed uniformly, and melt-kneaded, extruded and cut at a temperature of 270°C using a 40 mm diameter pelletizer 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 master discs for optical discs obtained here had excellent transparency and had no internal defects.

The polycarbonate master discs obtained in this way (5 discs each) were subjected to a holding test at constant temperature and constant temperature, and the number of point defects after the test was determined, and the results of evaluating the transparency of the master discs were evaluated. Measurement of the number of point defects shown in Table 1 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 [Effects of the Invention] According to the present invention, when producing optical molded products made of polycarbonate resin, by adding specific additives, the transparency of the molded products can be improved. Long-term stability can be guaranteed. 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 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-
An optical polycarbonate molding material, characterized in that it contains 1000 ppm of an aromatic carboxylic acid in which hydrogen atoms in aromatic rings may be substituted with lower alkyl groups, hydroxyl groups, or halogen atoms.