JP2003301099A - Polycarbonate resin composition and optical disk substrate made thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polycarbonate resin composition excellent in precision transfer properties, high rigidity, low water absorption, and transparency; and an optical disk substrate and an optical disk obtained from the composition. <P>SOLUTION: This resin composition is characterized in that it contains 0.1-20 pts.wt. stilbene compound represented by formula [I] in 100 pts.wt. polycarbonate resin. The optical disk substrate is obtained from the composition. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbonate resin composition having precision transferability for stamper shapes, high rigidity, low water absorption, and transparency, and an optical disk substrate and an optical disk obtained therefrom. More specifically, CD (compact disc), MO (magneto-optical disc), DVD (Digital Versatile)
The present invention relates to an optical disc substrate and an optical disc that have a precise transfer property in the field of optical discs such as Disc) and have less warp of the disc due to environmental changes. In particular, the present invention relates to a substrate for a high density optical disc having an extremely large recording capacity.

[0002]

2. Description of the Related Art The recording density of an optical disk is 0.6 of that of a CD.
It has been improving steadily from GB to 4.7 GB for DVD. However, with the progress of information technology, the market development in the optical disc field has been remarkable, and in the future, it is expected that a high density optical disc capable of recording a vast amount of information will appear. For example, 100 Gbit / that can support digital broadcasting
There is a demand for an optical disc having a recording density of inch ² or more.

The high density of the optical disk is achieved by narrowing the groove or pit spacing, that is, the track pitch to increase the recording density in the track direction. For example, in order to increase the density from CD to DVD, measures are taken to increase the recording density by narrowing the track pitch from 1.6 μm to 0.74 μm.

The optical disk substrate is manufactured by injection molding (injection compression molding) of a thermoplastic resin. At that time, a fine concavo-convex shape which is a source of a recording / reproducing signal, which is attached to the mold and is pre-engraved on the stamper, is transferred from the stamper to the substrate surface. Therefore, how accurately the uneven shape of the stamper can be transferred at the time of molding the substrate, that is, the precision transfer property is important. Especially, in molding a high density optical disk substrate, such importance becomes remarkable.

In the high density optical disc, in addition to the substrate having a high transfer rate, the warp of the substrate and the change in the warp due to the environmental change are smaller than those in the conventional optical disc.
It is important for the following reasons. As the density becomes higher, the wavelength of the laser becomes shorter and the NA of the pickup lens becomes higher, so that the coma aberration becomes large even if the substrate warps even slightly.
This is because it causes a focus error and a tracking error. Further, since the distance between the pickup lens and the substrate becomes shorter due to the increase in NA, it is important that the substrate warp and the warp change due to the environmental change are small in order to avoid contact between the lens and the substrate.

Conventionally, CD (compact disc) and MO
(Magneto-optical disk), DVD (Digital Ver.
Polycarbonate has been used for a substrate of an optical disc such as a Satele Disk) because of its excellent transparency, heat resistance, mechanical properties and dimensional stability.

However, with the increase in density of optical discs, optical disc substrates made of polycarbonate have become less than satisfactory in terms of precision transferability and warpage.

To meet the demand for improved transferability, various studies have been made from both sides of molding technology and material modification. Regarding the former, it has been confirmed that, for example, a method of setting the cylinder temperature and the mold temperature at the time of molding the substrate high is effective. However, since this method is high-temperature molding, it is necessary to lengthen the cooling time in the mold, which causes a problem that the molding cycle is extended and productivity is deteriorated. If you forcibly make the cycle high and perform molding, a mold release defect occurs when you take out the substrate from the mold,
Since the pits and grooves are deformed, on the contrary, there arises a problem that the transfer accuracy is lowered. Regarding the latter, for example, a method of containing a large amount of a low molecular weight substance in a polycarbonate resin in order to impart high fluidity (JP-A-9-208).
No. 684, Japanese Patent Application Laid-Open No. 11-1551, etc.) or a method of using a specific long-chain alkylphenol as a terminal terminating agent (Japanese Patent Application Laid-Open No. 11-269260, etc.) has been proposed. However, the method of increasing the content of this low molecular weight product or the method of modifying the end group with a long-chain alkylphenol generally causes a large decrease in thermal stability, and therefore accelerates thermal decomposition at the time of molding, resulting in disc substrate The mechanical strength is remarkably reduced, the substrate is cracked due to the force of protrusion from the mold, and the substrate is damaged during handling of the optical disc substrate.

As described above, all of the conventional techniques are aimed at the effect of improving the transferability by improving the fluidity of the resin, but they have not been able to obtain a practically efficient substrate with high efficiency. .

On the other hand, various requests have been made to improve the warpage from both sides of molding technology and material modification. Regarding the former, by adjusting the molding conditions in detail, the warpage of the substrate can be suppressed to a small level,
At the same time, it was difficult to accurately transfer the stamper shape. For the latter, it is known to be effective to use a rigid material having a high bending or tensile modulus. Therefore, for the purpose of improving the rigidity of the polycarbonate resin, a method of blending additives such as glass fiber and a filler has been attempted. However, although the above additives improve the rigidity of the polycarbonate resin,
There is a problem that the additive is exposed on the surface and the transfer accuracy is lowered.

Regarding the warpage due to environmental changes, in order to suppress water absorption deformation, Japanese Patent Laid-Open No. 2000-11449 discloses that "a substrate, a recording layer arranged on this substrate for recording an information signal, and a recording layer thereof. A disc-shaped information recording medium having a transparent protective layer to be laminated, and recording / reproducing an information signal by entering light from the transparent protective layer side. This substrate comprises a resin core layer and a core. Information recording characterized in that it is integrated with the layer, and one surface has unevenness of the information signal on the recording layer side, and is composed of a resin surface layer having fluidity compared to the core layer. A substrate that is a “medium” and uses a resin having a water absorption rate of 0.3% or less on the surface layer of the substrate has been proposed, and a direction for solving the problem is shown by a complicated substrate configuration by two-color molding or sandwich molding. .

[0012]

DISCLOSURE OF THE INVENTION The present invention relates to a polycarbonate resin composition having precision transferability with respect to a stamper shape, high rigidity, low water absorption and transparency, and a high transfer rate and low warpage obtained from the same. It is an object of the present invention to provide an optical disk substrate and an optical disk, especially a high density optical disk substrate.

The term "precision transferability" as used in the present invention means that when an optical disk substrate is manufactured by injection molding using a thermoplastic resin molding material, the fine concave-convex shape stamped on the stamper can be faithfully transferred. It is a property.

[0014]

According to the research conducted by the present inventors, the above-mentioned object of the present invention is to provide a polycarbonate resin 100.
What is achieved by a polycarbonate resin composition comprising 0.1 to 20 parts by weight of a stilbene compound represented by the following formula [I], and an optical disk substrate and an optical recording medium made of the resin, based on parts by weight. Was found.

[0015]

[Chemical 2]

(In the formula, a plurality of R ₁ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a chlorine atom, a bromine atom or a cyano group, and a plurality of R ₂ are independently hydrogen. It represents an atom, an alkyl group, an aryl group, an alkoxy group, a cyano group, a nitrile group, a carboxamide group or a carboximide group.) The present invention will be described in more detail below. The polycarbonate resin used in the present invention is usually obtained by reacting a dihydric phenol with a carbonate precursor by an interfacial polymerization method or a melt polymerization method. Typical examples of the dihydric phenol used here are hydroquinone, resorcinol, 4,4′-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane, bis {(4-hydroxy-3,5-dimethyl) phenyl. } Methane, 1,1
-Bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane,
2,2-bis (4-hydroxyphenyl) propane (bisphenol-A), 2,2-bis {(4-hydroxy-3-methyl) phenyl} propane, 2,2-bis {(4-hydroxy-3, 5-dimethyl) phenyl} propane, 2,2-bis {(3,5-dibromo-4-hydroxy) phenyl} propane, 2,2-bis {(3-isopropyl-4-hydroxy) phenyl} propane,
2,2-bis {(4-hydroxy-3-phenyl) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl)
-3-Methylbutane, 2,2-bis (4-hydroxyphenyl) -3,3-dimethylbutane, 2,4-bis (4
-Hydroxyphenyl) -2-methylbutane, 2,2-
Bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1
-Bis (4-hydroxyphenyl) -4-isopropylcyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 9,9
-Bis (4-hydroxyphenyl) fluorene, 9,9
-Bis {(4-hydroxy-3-methyl) phenyl} fluorene, 1,1'-bis- (4-hydroxyphenyl) -ortho-diisopropylbenzene, 1,1'-bis- (4-hydroxyphenyl) -meta -Diisopropylbenzene, 1,1'-bis- (4-hydroxyphenyl) -para-diisopropylbenzene, 1,3-bis (4-hydroxyphenyl) -5,7-dimethyladamantane, 4,4'-dihydroxydiphenylsulfone ,
4,4'-dihydroxydiphenyl sulfoxide, 4,
4'-dihydroxydiphenyl sulfide, 4,4'-
Dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl ether and 4,4'-dihydroxydiphenyl ester, 1,1-bis (4-hydroxyphenyl) -2 methylpropane, 1,1-bis (4-hydroxyphenyl) -2 -Ethylhexane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane and the like can be mentioned. These can be used alone or in combination of two or more kinds.

Among them, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 1,1-bis (4-hydroxyphenyl) -2 methylpropane, 2,
2-bis (4-hydroxyphenyl) -4-methylpentane is preferred.

Examples of the carbonate precursor used when producing a polycarbonate using the above dihydric phenol include carbonyl halide, carbonate ester, haloformate, and the like. Specifically, phosgene,
Examples thereof include diphenyl carbonate or dihaloformate of dihydric phenol, and phosgene or diphenyl carbonate is preferable.

When a polycarbonate resin is produced by reacting the above-mentioned dihydric phenol with a carbonate precursor by, for example, a solution polymerization method or a melt polymerization method, a catalyst, an end terminating agent, and oxidation of the dihydric phenol may be added, if necessary. You may use an inhibitor etc.

The reaction by the interfacial polymerization method is usually a reaction between a dihydric phenol and phosgene, which is carried out in the presence of an acid binder and an organic solvent. As the acid binder, for example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or an amine compound such as pyridine is used. As the organic solvent, halogenated hydrocarbons such as methylene chloride and chlorobenzene are used. It is also possible to use a catalyst such as a tertiary amine such as triethylamine, tetra-n-butylammonium bromide, or tetra-n-butylphosphonium bromide, a quaternary ammonium compound, or a quaternary phosphonium compound for accelerating the reaction. it can. At that time, the reaction temperature is usually 0 to 40 ° C., the reaction time is preferably 10 minutes to 5 hours, and the pH during the reaction is preferably 9 or more.

In addition, in such a polymerization reaction, a terminal stopper is usually used. Monofunctional phenols can be used as such an end terminator. Monofunctional phenols are commonly used as molecular terminating agents for molecular weight control, and the resulting polycarbonate resins are compared to those that do not because the ends are blocked by groups based on monofunctional phenols. Excellent thermal stability. Such monofunctional phenols are generally phenols or lower alkyl-substituted phenols represented by the following formula [II]

[0022]

[Chemical 3]

[In the formula, A is a hydrogen atom or 1 to 9 carbon atoms.
Is a linear or branched alkyl group or a phenyl-substituted alkyl group, and r is an integer of 1 to 5, preferably 1 to 3. ] Monofunctional phenols represented by can be shown.

Specific examples of the above monofunctional phenols include phenol, p-tert-butylphenol, p-cumylphenol and isooctylphenol.

As other monofunctional phenols,
Phenols or benzoic acid chlorides having a long-chain alkyl group or an aliphatic ester group as a substituent,
Alternatively, long-chain alkylcarboxylic acid chlorides can be used, and when these are used to block the ends of the polycarbonate polymer, they not only function as a terminal stopper or a molecular weight modifier, but also melt flowability of the resin. Is not only improved and the molding process is facilitated, but also has the effect of lowering the physical properties of the substrate, in particular the water absorption of the resin, and the effect of reducing the birefringence of the substrate, and is therefore preferably used. Above all, the following formulas [III] and [IV]

[0026]

[Chemical 4]

[0027]

[Chemical 5]

[Wherein, X is -R-CO-O- or -R
-O-CO-, where R is a single bond or 1 carbon atom
-10, preferably 1-5 divalent aliphatic hydrocarbon group is shown, and n shows the integer of 10-50. ] Phenols having a long-chain alkyl group represented by the formula as a substituent are preferably used.

The substituted phenols of the above formula (III) are preferably those in which n is 10 to 30, particularly 10 to 26, and specific examples thereof include decylphenol, dodecylphenol, tetradecylphenol, hexadecylphenol and octadecyl. Phenol, eicosylphenol, docosylphenol, triacontylphenol and the like can be mentioned.

Suitable substituted phenols of the above formula (IV) are compounds in which X is —R—CO—O— and R is a single bond, and n is 10 to 30, particularly 10 to 2.
6 are preferred, and specific examples thereof include decyl hydroxybenzoate, dodecyl hydroxybenzoate, tetradecyl hydroxybenzoate, hexadecyl hydroxybenzoate, eicosyl hydroxybenzoate, docosyl hydroxybenzoate and triacontyl hydroxybenzoate. Can be mentioned.

It is desirable that these terminal terminators are introduced at the terminal of at least 5 mol%, preferably at least 10 mol% based on all the terminals of the obtained polycarbonate resin, and the terminator alone is used. Or you may use it in mixture of 2 or more types.

A typical example of the reaction by the melt polymerization method is a transesterification reaction between a dihydric phenol and a carbonate ester. The dihydric phenol and the carbonate ester are mixed while heating in the presence of an inert gas, It is carried out by a method of distilling the produced alcohol or phenol. The reaction temperature varies depending on the boiling point of the alcohol or phenol to be produced, but is usually in the range of 120 to 350 ° C. In the latter half of the reaction, the reaction system is 10 to 0.1 Tor
The pressure is reduced to about r (1,300 to 13 Pa) to facilitate the distillation of the produced alcohol or phenol. The reaction time is usually about 1 to 4 hours.

Examples of the carbonate ester include an ester such as an aryl group having 6 to 10 carbon atoms, an aralkyl group or an alkyl group having 1 to 4 carbon atoms which may have a substituent. Specifically, diphenyl carbonate,
Examples thereof include ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, and among them, diphenyl carbonate is preferable.

Also, a polymerization catalyst is used to increase the polymerization rate.
As the polymerization catalyst, for example, water can be used.
Sodium oxide, potassium hydroxide, dihydric phenol
Alkali metal compounds such as thorium salt and potassium salt;
Calcium oxide, barium hydroxide, magnesium hydroxide, etc.
Alkaline earth metal compounds of tetramethylammonium
Hydroxide, tetraethylammonium hydroxy
Nitrogen-containing salts such as sodium chloride, trimethylamine and triethylamine
Basic compound; Alcohol of alkali metal or alkaline earth metal
Xides; organic acid salts of alkali metals and alkaline earth metals
Kinds; In addition, zinc compounds, boron compounds, aluminum
Um compounds, silicon compounds, germanium compounds,
Organotin compounds, lead compounds, osmium compounds,
Antimony compounds, manganese compounds, titanium compounds
Esterification reaction of zirconium compounds, zirconium compounds, etc.,
The catalyst used in the transesterification reaction can be used
It The catalysts may be used alone or in combination of two or more.
You may use it. The amount of these polymerization catalysts used depends on the raw materials.
1 mol per 1 mol of the dihydric phenol ^-8
~ 1 x 10^-3Equivalent, more preferably 1 × 10^-7~ 5 x 1
0^-FourIt is selected within the equivalent range.

In the polymerization reaction, in order to reduce the number of phenolic terminal groups, for example, bis (chlorophenyl) carbonate, bis (bromophenyl) carbonate, bis (nitrophenyl) carbonate may be added after or at the end of the polycondensation reaction. , Bis (phenylphenyl)
Carbonate, chlorophenyl phenyl carbonate,
It is preferable to add compounds such as bromophenylphenyl carbonate, nitrophenylphenyl carbonate, phenylphenyl carbonate, methoxycarbonylphenylphenyl carbonate and ethoxycarbonylphenylphenyl carbonate. Of these, 2-chlorophenylphenyl carbonate, 2-methoxycarbonylphenylphenyl carbonate and 2-ethoxycarbonylphenylphenyl carbonate are preferable, and 2-methoxycarbonylphenylphenyl carbonate is particularly preferable.

The viscosity average molecular weight of the polycarbonate resin is preferably controlled within the range of 10,000 to 30,000, and more preferably within the range of 12,000 to 20,000. A polycarbonate resin optical molding material having such a viscosity average molecular weight is preferable because sufficient strength as an optical material can be obtained and the melt fluidity at the time of molding is good and molding distortion does not occur. If the molecular weight is excessively low, the strength of the substrate after molding will be problematic. On the contrary, if the molecular weight is excessively high, the melt fluidity during molding will be poor.
A raw material polycarbonate resin in which unfavorable optical distortion is increased in a substrate is produced by a conventionally known conventional method (solution polymerization method, melt polymerization method, etc.) and then filtered in a solution state to remove impurities and foreign matters such as unreacted components. It is preferable to remove.

The stilbene compound used in the present invention is a compound represented by the following formula [I].

[0038]

[Chemical 6]

(In the formula, a plurality of R ₁ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a chlorine atom, a bromine atom or a cyano group, and a plurality of R ₂ are independently hydrogen. Represents an atom, an alkyl group, an aryl group, an alkoxy group, a cyano group, a nitrile group, a carboxamide group or a carboximide group.)

In the above formula [I], preferably a plurality of R ₁ 's each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and a plurality of R ₂ 's each independently represent a hydrogen atom, an alkyl group or an aryl group. Alternatively, the compound is an alkoxy group. As a specific compound, stilbene or 4,4 dimethylstilbene is preferable.

The stilbene compound is used in an amount of 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the polycarbonate resin.

Any method may be employed in preparing the compositions of the present invention. For example, a polycarbonate resin in a solution state, after mixing the stilbene compound, the solvent is distilled off, then by a vent-type extruder or the like, a method of melt pelletization, or a polycarbonate resin and the stilbene compound super mixer, tumbler, A method of mixing with a Nauta mixer or the like and pelletizing with a biaxial ruder or the like is used. If necessary, additives such as a stabilizer, an antioxidant, a light stabilizer, a coloring material, a sliding material, and a release agent can be added. Further, in the extrusion step (pelletizing step) of obtaining a pellet-shaped polycarbonate resin for injection molding, it is preferable to remove foreign matters by passing through a sintered metal filter having a filtration accuracy of 10 μm in a molten state. If necessary, it is also preferable to add an additive such as a phosphorus-based antioxidant. In any case, it is necessary that the content of foreign materials, impurities, solvents, etc. in the raw material resin before injection molding be as low as possible.

When an optical disk substrate is manufactured from the above polycarbonate resin, an injection molding machine (including an injection compression molding machine) is used. This injection molding machine may be one that is generally used, but from the viewpoint of suppressing the generation of carbides and improving the reliability of the disk substrate, it has low adhesion to resin as a cylinder or screw, and has corrosion resistance and wear resistance. It is preferable to use a material formed of a material exhibiting properties.
Cylinder temperature is 300-400 as conditions for injection molding.
C. and a mold temperature of 50 to 140.degree. C. are preferable, and an optically excellent optical disk substrate can be obtained by these. The environment in the molding process is preferably as clean as possible in view of the purpose of the present invention. In addition, it is important to sufficiently dry the material to be molded to remove water, and to take measures so as not to cause retention that would cause decomposition of the molten resin.

The optical disk substrate molded in this way is
Compact disc (CD), magneto-optical disc (M
O), DVD, and other existing optical discs, as well as the Blu-ray Disc (B) that performs recording / reproduction through a transparent cover layer with a thickness of 0.1 mm that covers the disc substrate.
It is also suitably used as a substrate for a high density optical disc represented by D).

Since the polycarbonate resin optical molding material of the present invention is excellent in high precision transferability, the interval between groove rows or pit rows is 0.1 μm to 0.8 μm, preferably 0.1 to 0.5 μm. More preferably 0.1
It is possible to easily obtain an optical disk substrate of 0.35 μm by molding. The optical depth of the groove or pit is λ / 8n to λ / 2n, preferably λ / 6n to λ / 2n, with respect to the wavelength λ of the laser light used for recording and reproduction and the refractive index n of the substrate, and further, Preferably λ / 4n
It is possible to obtain an optical disk substrate in the range of λ / 2n. Thus, the recording density is 100 Gbit / inch2.
It is possible to easily provide the base material of the high-density optical disc recording medium as described above.

[0046]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto as long as the gist thereof is not exceeded. In the examples and comparative examples, "parts" are parts by weight. The evaluation was according to the following method.

(1) Viscosity average molecular weight 100 mL of methylene chloride and 0.7% of polycarbonate resin
specific viscosity (ηs
p) was inserted into the following equation to obtain. ηsp / c = [η] + 0.45 × [η] ² c (where [η] is the intrinsic viscosity) [η] = 1.23 × 10 ⁻⁴ M ^0.83 c = 0.7

(2) Glass Transition Temperature TA Instrument Thermal Analysis System DSC-
2910, under nitrogen atmosphere (nitrogen flow: 40 m
1 / min) and the rate of temperature rise: 20 ° C./min.

(3) Water Absorption Rate According to ASTM D-570, a φ45 mm molded plate was dipped in water to obtain the weight change rate (% by weight).

(4) Flexural modulus It was measured according to ASTM D-790.

(5) Transferability An injection molding machine MO40D-3H manufactured by Nissei Plastic Industry Co., Ltd., a depth of 200 nm, a stamper having grooves of 0.5 μm and a width of 0.2 μm, and a diameter of 120 mm and a thickness of 1 was used. .2
A mm optical disc substrate was molded. The cylinder temperature was 360 ° C., the mold clamping force was constant at 40 tons, and the mold temperature was set for each resin as shown in Table 1. The depth of the groove transferred from the stamper to the substrate was measured at 5 positions at a radius of 40 mm using an atomic force microscope (Seiko Denshi Kogyo SPI3700). The transferability was expressed as a transfer rate represented by the following formula. The larger this value, the better the transferability. Transfer rate (%) = 100 x disc groove depth / stamper groove depth

(6) Initial Mechanical Properties (Initial R-Tilt) An optical disk substrate having a diameter of 120 mm and a thickness of 1.2 mm was molded using an injection molding machine MO40D-3H manufactured by Nissei Plastic Industry Co., Ltd. After that, a reflection film, a dielectric layer 1, a phase-change recording film, on the signal surface side of the disk substrate obtained by injection molding,
The dielectric layer 2 was sputter-deposited, and a polycarbonate thin film cover layer was attached thereon to form an optical disk. Subsequently, spacers were sandwiched so that the disks did not come into contact with each other, and the disks were left for 2 days or more in an environment of a temperature of 23 ° C. and a humidity of 50% RH. Made by Japan EM Co., Ltd. when the Tilt changes due to heat shrinkage and environmental changes become stable.
Tilt was evaluated by a dimensional shape measuring instrument DLD-3000U to obtain initial mechanical properties.

(7) Maximum value of warp deformation amount (ΔR-Til
tmax) The substrate evaluated for initial mechanical properties is 30 ° C., humidity 90% RH
After leaving it in the constant temperature and humidity chamber for 72 hours,
After moving to an environment of 3 ° C. and humidity of 50% RH, the maximum value of the warp deformation amount of the disk (ΔR-Tiltmax) after that is three-dimensional shape measuring device DLD- manufactured by Japan EM Co., Ltd.
It was evaluated by 3000 U. Examples 1 to 3, Comparative Examples 1 to
2 Addition of the additive in an amount of parts by weight shown in Table 1 to 100 parts by weight of a polycarbonate resin having a viscosity average molecular weight of 15,200 (manufactured by Teijin Chemicals) obtained by using bisphenol A as a dihydric phenol component, Mix evenly. Subsequently, the powder was subjected to a vent type twin-screw extruder [KTX-46 manufactured by Kobe Steel, Ltd.] at a cylinder temperature of 260 ° C.
The mixture was melt-kneaded while being degassed to obtain pellets of the resin composition. Using this resin composition pellet, various physical properties were evaluated by the methods described above. The evaluation results are shown in Table 1.

From the pellets of this resin composition, an injection molding machine MO40D-3H manufactured by Nissei Plastic Industry Co., Ltd., depth 200n
An optical disk substrate having a diameter of 120 mm and a thickness of 1.2 mm was formed by using a stamper in which grooves each having m, an interval of 0.5 μm and a width of 0.2 μm were engraved. The cylinder temperature is 36
The mold clamping temperature was set to 0 ° C., the mold clamping force was kept constant at 40 tons, and the mold temperature was set for each resin as shown in Table 1. Using this disc substrate, various substrate characteristics were evaluated by the methods described above. The evaluation results are shown in Table 1. The stilbene compounds listed in Table 1 are as follows. Stilbene: manufactured by Tokyo Kasei Kogyo trans-stilbene 4,4 Dimethyl stilbene: manufactured by Tokyo Kasei Kogyo 4,4-
Dimethyl-trans-stilbene

[0055]

[Table 1]

[0056]

According to the present invention, it is possible to provide an optical disk substrate having a stamper shape transferred with high precision as an optical recording medium formed by molding a specific polycarbonate resin, particularly a high density recording medium. The effect produced is exceptional.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11B 7/24 563 G11B 7/24 563D 563E (72) Inventor Hideyuki Tsunemori 1-chome, Uchiyuki-cho, Chiyoda-ku, Tokyo No. 2 F-term in Teijin Kasei Co., Ltd. (reference) 4J002 CG001 EA036 GS02 5D029 KA07 WB11 WB17 WC01 WC04 WC05 WD10

Claims (8)

[Claims] 1. A stilbene compound represented by the following formula [I] is added in an amount of 0.1 to 100 parts by weight of a polycarbonate resin.
A polycarbonate resin composition comprising 20 parts by weight. [Chemical 1] (In the formula, a plurality of R ₁ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a chlorine atom, a bromine atom or a cyano group, and a plurality of R ₂ are each independently a hydrogen atom, an alkyl group. Represents a group, an aryl group, an alkoxy group, a cyano group, a nitrile group, a carboxamide group or a carboximide group.) 2. A plurality of R _{1 s} in the formula [I] are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and a plurality of R _{2 s} are each independently a hydrogen atom, an alkyl group, an aryl group or The polycarbonate resin composition according to claim 1, which is an alkoxy group. 3. The polycarbonate resin has a viscosity average molecular weight of 10,000 as measured in a methylene chloride solution at 20 ° C.
The polycarbonate resin composition according to claim 1 or 2, which is in the range of 0 to 30,000. 4. An optical molding material comprising the polycarbonate resin composition according to claim 1. 5. An optical disk substrate molded using the optical molding material according to claim 4. 6. A groove row or pit row formed by using the optical molding material according to claim 4 has an interval of 0.1.
An optical disk substrate having a size of μm to 0.8 μm. 7. The optical depth of a groove or pit molded using the optical molding material according to claim 4 is such that the wavelength λ of laser light used for recording and reproduction and the refractive index n of the substrate.
The optical disk substrate according to claim 5, wherein the range is λ / 8n to λ / 2n. 8. An optical recording medium using the optical disk substrate according to claim 5.