JPH0379659A - Molding material for optical application - Google Patents

Abstract

PURPOSE:To provide a molding material having excellent heat resistance and moldability and used for optical applications by compounding a polycarbonate resin having a specific range of viscosity-average mol.wt. with a pentaerythritol mono-tetrathiopropionate. CONSTITUTION:(A) 100 pts.wt. of a polycarbonate resin having a viscosity average mol.wt. of 12000-30000 is compounded with (B) 0.001-0.3 of a pentaerythritol mono-tetrathiopropionate such as pentaerythritol tetrakis(beta-lauryl- thiopropionate), if necessary, phosphorous acid, an organic phosphite, a mold release agent (preferably the simultaneous use of stearyl monoglyceride and butyl stearate), etc., to provide a molding material reduced in the generation of gelled products, etc., in molding processes and used for optical applications.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to optical molding of polycarbonate resin having excellent heat resistance and moldability, which is suitable for manufacturing optical molded products such as optical discs, lenses, and prisms. Regarding materials.

[Conventional technology and its problems]

Recently, polycarbonate resin has been improved due to its transparency, heat resistance,
Taking advantage of its characteristics such as hydrolysis resistance and dimensional stability, it has come to be widely used as a substrate material for lenses, optical information disks, etc.

In particular, optical information discs, such as compact discs (CDs), on which signals can be written and rewritten, are highly anticipated as new memory materials. In terms of performance as an optical disk substrate, the most important problem to avoid is the inclusion of foreign matter that causes diffuse reflection of laser beams, and similarly, gel-like matter, which is a decomposition product of polycarbonate that occurs during molding, must be reduced as much as possible. The details of the chemical structure of this gel-like substance are unknown, but when polycarbonate is dissolved in methylene chloride, it is detected as an insoluble substance and can be quantified by light scattering, and its size is approximately 0.5 to 10 uyA. It is of a certain degree.

With conventional polycarbonate resin, when the above gel-like material is molded at a high temperature of 300 to 380 degrees Celsius,
Approximately 104 to 105 particles were generated per gram of resin, and this was one of the major causes of deterioration in the noise level of optical discs.

Various heat stabilizers have been proposed to reduce the generation of gel-like substances, but conventionally known organic phosphites and organic phosphonites are hydrolyzable and have not been developed for a long time in high-temperature and humid environments. On the contrary, another disadvantage arises in that it accelerates the hydrolysis of the resin and promotes the formation of white spots.

Furthermore, organic phosphine and organic phosphine oxyto had insufficient effect of suppressing the generation of gel-like substances.

[Means to solve the problem]

The present invention was completed as a result of extensive research into a stabilizer that reduces the generation of gel-like substances due to decomposition and deterioration during heating and melting of polycarbonate resin, and does not promote hydrolysis of polycarbonate even in high-temperature and humid environments. .

That is, the present invention has a viscosity average molecular weight of 12.000 to 30.00.
Per 100 parts by weight of polycarbonate resin of 000, mono- to tetra-thiopropionate of pentaerythritol represented by the following general formula (1) o, ooi to O03
It is an optical molding material made by blending parts by weight.

General formula (1): (R-3-CH,CH,C00C
H,), C(CH,OH),.

(R in the formula may be the same or different and represent hydrogen or an alkyl group having 1 to 22 carbon atoms, and m represents an integer of 1 to 4.) Hereinafter, the structure of the present invention will be explained.

The polycarbonate resin of the present invention is a homo- or co-polycarbonate resin obtained by the reaction of dihydric phenol with a carbonate precursor such as phosgene or diphenyl carbonate, a further branched resin, or a resin with a long-chain alkyl group or ester group at the end. Introduced: Modified polycarbonate resin obtained by using bisphenol, vinylphenol, etc., which have carbon-carbon unsaturated double bonds as a comonomer or terminal capping agent, and grafted with styrene, etc., and terephthalic acid chloride as a part of phosgene. , isophthalic acid chloride with some ester bonds, or modified polystyrene using phenolic hydroxyl groups as a comonomer and graft polymerized with polycarbonate resin. Average molecular weight is 12.000-30.
000, and 12,000 to 23,000
The area is 23.000 to 30.00 for injection bottom type.
The 0 region is extruded into a sheet shape, which is suitable for use as an optical disk or optical card substrate.

Here, as the dihydric phenol, 2.2-bis(4-
hydroxyphenyl)propane (=bisphenol A)
, bis(4-hydroxyphenyl)methane, 1,2-bis(4-hydroxyphenyl)ethane, 2,2-bis(
4-hydroxyphenyl)butane, 1,1-bis(4-
Hydroxyphenyl)-1-phenylmethane, 1゜1-
Bis(4-hydroxyphenyl-1,1-diphenyl)
Methane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfide, bis(
Examples include 4-hydroxyphenyl) sulfone, and those in which a lower alkyl group or a halogen atom is substituted for these phenyl groups, and bisphenol A is particularly representative.

The mono- or tetra-thiopropionate of pentaerythritol represented by the above general formula (1) of the present invention, which is blended into the above polycarbonate resin, prevents the generation of gel-like substances due to decomposition and deterioration during heating and melting of the polycarbonate resin. It also has the effect of suppressing the hydrolysis of polycarbonate and suppressing the generation of white spots even in high temperature and high humidity environments. A typical example is pentaerythritol tetrakis-(β-lauryl-thiopropionate) (=Sumilizer TP-D, manufactured by Sumitomo Chemical ■).

In particular, the white spot prevention effect is important for improving reliability as an optical material, and conventional stabilizers have been insufficient.

The amount of the compound of general formula (1) added is 0.001 to 0.3 parts by weight per 100 parts by weight of the polycarbonate resin, and if it is less than 0.001 parts by weight, the effect of suppressing the generation of gel-like substances is insufficient. However, if it is used in an amount exceeding 0.3 parts by weight, it is not preferable because it accelerates deterioration in a high temperature and humid environment. Incidentally, the pentaerythritol mono- or tetrathiopropionate of the present invention can naturally be used with other phosphorous acids,
It may be used in combination with organic phosphites, organic phosphonites, sterically hindered phenolic antioxidants, and the like.

Although the optical molding material of the present invention essentially contains the above-mentioned components, a release agent for improving transferability and others may be added as additives. Examples of mold release agents include fatty acid esters, particularly partial esters of polyhydric alcohols, long-chain fatty acids, paraffin, silicone oil, etc. Particularly partial esters of saturated fatty acids having 10 to 22 carbon atoms and polyhydric alcohols from 0.0001 to 0.01 part by weight and carbon number 10-3
A preferred method is to use a combination of 0.005 to 0.2 parts by weight of an ester of 0 saturated fatty acids and a monohydric alcohol having 30 or less carbon atoms.

〔Example〕

The present invention will be explained below with reference to Examples.

Note that %, parts, etc. in Examples and the like are based on weight unless otherwise specified, and the quantitative determination, appearance, and long-term moisture resistance test of the gel-like material were measured by the following method.

The pellet and the molded article were each dissolved in methylene chloride at a concentration of Ig/10 (7), and the insoluble foreign matter was quantified by a light scattering method, and the difference (Δ) was taken as the number of gel-like materials generated during molding.

The measuring device used was a particulate counter model 4100 manufactured by Vialock/Leuco.

[Note that in the case of the above method, foreign substances other than gel-like substances are also measured as gel-like substances. However, by capturing the foreign matter with a PTFB membrane filter and quantitatively analyzing it with 8PMA, gel-like matter and other foreign matter can be clearly distinguished. By this method, it has been confirmed that the increased amount is essentially a gel-like material. ] Appearance and long-term moisture resistance test (white point score) Using a 3.0 oz injection molding machine (manufactured by Sumitomo Heavy Industries ■, disc 51J3 model), the pellet was molded into a resin temperature of 320°C and a mold temperature of 105°C, with a thickness of 1.2 mm and a diameter of 130 mm. The disc is bottom-shaped, and the disc is visually observed for hue, burns, flow marks, and the presence or absence of chain-like formations (exterior appearance).

In addition, after putting this disk in an environmental tester at 80°C and 90% RH for 500 hours, the 50-
The number of white spots above is read using an optical microscope.

Examples 1 to G and Comparative Examples 1 to 3 Caustic soda aqueous solution of bisphenol A and methylene chloride
While stirring (=MC) at 20°C, phosgene was introduced. Next, p-tert-butylphenol and triethylamine were added, and the mixture was reacted for 1 hour with strong stirring, after which a methylene chloride solution of the reaction product mixture was separated and washed repeatedly with water.

Add 2 parts of n-hebutane (=nH) to 100 parts by volume of this solution.
5 parts by volume were added and mixed, the mixed solution was dropped into warm water, and then the temperature was raised to 100°C and the solvent was distilled off to obtain a slurry of polycarbonate powder.

This powder was filtered out and dried at 120°C for 8 hours to obtain polycarbonate with a viscosity average molecular weight of 15.000.

To this polycarbonate powder, 0.01 part of stearic acid monoglyceride and 0.03 part of butyl stearate were mixed with 100 parts of polycarbonate resin as additives and mold release agents listed in Table 1, and the resin temperature was adjusted to 250 to 270°C. The material was extruded into pellets to obtain a molding material.

Using the above pellet, a disk with a thickness of 2 mm and a diameter of 120 mm was shaped into a bottom shape, and the gel-like material was quantitatively determined, and the appearance and long-term moisture resistance tests were conducted. Table 1 shows the results.

Table 1 note) Fee: The stabilizer was as follows.

[Operation and effects of the invention]

As described above, the optical molding material of the aromatic polycarbonate resin of the present invention has less molecular weight reduction and less occurrence of burning during molding processes such as extrusion and injection molding, and less generation of gel-like substances. Further, even when the product is forced to be used in a high temperature and high humidity environment, there is little generation of white spots due to hydrolysis. As a result, it is not only effective in reducing the initial noise level of optical discs used for reading or writing signals, but also ensures excellent reliability during long-term use or use after long-term storage.

Claims (1)

[Scope of Claims] 0.001 to 0.001 to tetra-thiopropionate of pentaerythritol represented by the following general formula (1) per 100 parts by weight of a polycarbonate resin having a viscosity average molecular weight of 12,000 to 30,000. An optical molding material containing 0.3 parts by weight. General formula (1): (R-S-CH_2CH_2COOCH
_2)_mC(CH_2OH)_4_-_m (R in the formula
may be the same or different from each other, and hydrogen or carbon number 1
-22 alkyl group is shown, and m is an integer of 1-4. )