JP2003147139A - Resin composition, optical disk substrate and optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel resin composition which can be used in the production of optical disk substrates having less moisture absorption, excellent warpage and adhesion. SOLUTION: The resin composition mainly comprises (a) a polycarbonate resin, and (b) a hydrogenated polystyrenic at a weight ratio of component (a) to component (b) of 0.5/99.5 to 49/51. An optical disk substrate uses the resin composition, and an optical disk uses the substrate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin composition suitable for use as an optical disk substrate, an optical disk substrate obtained from the resin composition, and an optical disk. More specifically, when used as an optical disc substrate, a resin composition having hygroscopicity, warpage, and excellent adhesiveness to a metal thin film or a protective layer,
The present invention relates to an optical disk substrate using the resin composition and an optical disk using the same.

[0002]

2. Description of the Related Art In recent years, the development of optical discs as information recording media has been remarkable. Currently, as optical discs, compact disc (CD), CD-ROM, DVD, C
Many things such as DR, CD-RW, PD, and DVD-RW have been put to practical use. There are various recording / reproducing methods for these optical discs, such as those that write signals by physical unevenness called pits, those that use the phase change of the substance that forms the recording layer, and those that use the magneto-optical effect in the recording layer. Although practically used, in any case, the laser light for reading and writing the record passes through the transparent resin substrate. More specifically, the laser light is incident from the transparent resin substrate side, and the recording layer and the reflective layer The structure is such that the intensity and polarization angle of the reflected light that is reflected by the laser beam, passes through the resin substrate again, and returns.

On the other hand, recently, a new type of high density optical disc has been developed. For example, in JP-A-11-7658, a reflection film, a recording film, and a light transmission layer corresponding to a surface protection layer are sequentially provided on a substrate, and laser light is incident not from the substrate side but from the light transmission layer on the opposite side. Proposing a method. In this method, the thickness of the light transmission layer is thin, for example, 70
A transparent film having a thickness of about -100 μm, thickness unevenness of the film is suppressed within a certain range, and the numerical aperture (NA) of the condenser lens for incident laser light is increased, so that the optical disc has a conventional structure. It is possible to achieve higher recording density. An optical disc having such a new structure is currently under active development as a next-generation high-density optical disc using a blue laser (hereinafter, this is abbreviated as a film surface incident type optical disc).

Conventionally, a polycarbonate resin is mainly used for a substrate of an optical disk because of its excellent transparency, heat resistance, mechanical properties, moldability, etc., and particularly 2,2-bis (4)
Aromatic polycarbonates containing -hydroxyphenyl) propane (abbreviated as bisphenol A) as a bisphenol component are mainly used because of their excellent physical property balance and cost. Transparency is not required in the next-generation high-density optical disc substrate of the above method,
The required characteristics for the warp of the substrate become extremely severe. High N. A. Since the condenser lens of (1) is brought close to the substrate and the short wavelength laser is focused on the extreme surface of the substrate, even a slight warp of the substrate may cause an error during signal detection and writing. Generally, the warp of the optical disk substrate is divided into one caused by molding and one caused by subsequent environmental changes. The warp caused when the substrate is molded can be sufficiently overcome by devising the molding conditions. On the other hand, the warpage due to environmental changes is mainly due to the hygroscopicity of the substrate itself,
In particular, the optical disc of the above method has an asymmetric structure unlike the DVD type in which two substrates having the same thickness are bonded together, and metal deposition is performed only on one surface, so that moisture absorption mainly progresses from the opposite substrate surface. The structure is such that the water absorption balance inside collapses and warpage easily occurs.

As described above, a resin for optical disks which is widely used at present is a polycarbonate resin, but the resin has a high water absorption rate, and when it is used for a film incident type optical disk substrate, there is a problem of warpage due to moisture absorption. There is concern. On the other hand, hydrides obtained by hydrogenating an aromatic ring of a styrene-based polymer have been proposed for optical disk substrate applications as resins having low hygroscopicity and low birefringence and excellent optical characteristics. However, in general, amorphous polyolefins (AP
The substrate consisting of O) has a drawback that the surface energy is low and the adhesiveness is inferior, and there is a concern that the adhesiveness is low in practical use.

[0006]

An object of the present invention is to form at least one reflective film on a resin substrate and at least one transparent protective layer on the reflective film. It is an object to provide a material suitable for an optical disc substrate of a novel system that is incident from the side and reads or writes information. More specifically, it is an object of the present invention to provide a material having excellent adhesiveness to a metal thin film and a transparent protective layer while maintaining moldability as an optical disk substrate in an optical disk substrate mainly containing a hydrogenated styrene polymer.

[0007]

Since the laser light does not pass through the substrate in the film-side incident type optical disk, unlike the conventional optical disk, the transparency and optical characteristics of the substrate are not required. The inventors of the present invention have made extensive studies in order to achieve the object in view of such characteristics. As a result, a hydrogenated styrene polymer obtained by hydrogenating an aromatic ring of a polystyrene resin is blended with a polycarbonate resin at a certain ratio. The present inventors have found that the composition is suitable as a disk substrate material having improved adhesiveness while maintaining moldability, and arrived at the present invention.

That is, the present invention is a resin composition mainly composed of a polycarbonate resin (a) and a hydrogenated styrene polymer (b), the weight ratio of which is (a) / (b).
= 0.5 / 99.5 to 49/51, which is a resin composition. The polycarbonate resin (a) is preferably an aromatic polycarbonate mainly containing 2,2-bis (4-hydroxyphenyl) propane as a bisphenol component. The hydrogenated styrene polymer (b) is hydrogenated polystyrene obtained by hydrogenating 80 mol% or more of the aromatic ring of polystyrene, or a conjugated diene component in a copolymer of styrene and a conjugated diene. All of the derived double bonds and 8 of the aromatic rings derived from the styrene component
It is preferably a hydrogenated styrene-conjugated diene copolymer obtained by hydrogenating 0 mol% or more.

The present invention is also an optical disk substrate using these resin compositions. In particular, at least one reflective film and at least one transparent protective layer are formed on the resin substrate, and laser light is incident from the transparent protective layer side on the resin substrate or the resin substrate. It is suitable for use as an optical disk substrate having a substrate thickness in the range of 0.3 to 1.2 mm, which is used for an optical disk characterized by reading and / or writing information on a recording layer formed on the upper layer. . Furthermore, the present invention includes an optical disc using these optical disc substrates.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
There is no particular limitation on the polycarbonate resin used in the present invention. Generally, polycarbonate is a general term for polymers whose main chain is bound by a carbonic acid bond, but generally, a dihydroxy compound such as bisphenol and phosgene or diphenyl carbonate are polymerized by a known method such as an interfacial polymerization method or a melt polymerization method. It can be obtained by a condensation reaction.

Examples of the dihydroxy compound used here include 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl).
Cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, bis (4-hydroxyphenyl) methane, 1,1-bis (4
-Hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, bis (4-hydroxyphenyl) diphenylmethane, 2,2-bis (4
-Hydroxy-3-methylphenyl) propane, 2,2
-Bis (3-phenyl-4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3-t-butylphenyl) propane, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9- Bis (4-hydroxy-
3-methylphenyl) fluorene, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, 1,3-bis {2- (4-hydroxyphenyl) propyl} benzene, 1,4-bis {2 -(4
-Hydroxyphenyl) propyl} benzene, 2,2-
Bis (4-hydroxyphenyl) -1,1,1-3,
Aromatic bisphenols such as 3,3-hexafluoropropane, 2,2-dimethyl-1,3-propanediol,
Spiroglycol, 1,4-cyclohexanediol,
Aliphatic diols such as 1,4-cyclohexanedimethanol may be mentioned.

Among these, an aromatic polycarbonate called bisphenol A containing 2,2-bis (4-hydroxyphenyl) propane as a bisphenol component can be preferably mentioned in terms of physical properties and cost. These dihydroxy compounds may be used alone or in combination of two or more kinds to form a copolycarbonate. It is also possible to use it as a polyester carbonate partially containing a terephthalic acid and / or isophthalic acid component.

The molecular weight of the polycarbonate resin used in the present invention is 8,000 to 10 in terms of its viscosity average molecular weight.
It is in the range of 10,000. Viscosity average molecular weight is 8,000
If it is smaller, the molded product becomes extremely brittle even in the resin composition, which is not preferable. On the other hand, if it exceeds 100,000, the melt fluidity tends to deteriorate, and it tends to be difficult to obtain a good molded product. More preferably 10,000 to 50,0
The range is 00. The viscosity average molecular weight was calculated by substituting the intrinsic viscosity obtained in a methylene chloride solution of polycarbonate into the Mark-Hoink-Sakurada formula. Various coefficients at this time can be obtained, for example, from Polymer Handbook 3rd Revised Edition Wiley Company (1989) (Polymer Ha).
ndbook 3rd Ed. Willey, 198
9), pages 7 to 23.

On the other hand, the hydrogenated styrene-based polymer used in the present invention is a styrene-based polymer having a cyclohexane structure obtained by nuclear hydrogenation of an aromatic ring. Examples of the styrene-based polymer include polystyrene, which is a homopolymer of styrene, or a styrene-based copolymer obtained by copolymerizing styrene with another monomer such as a conjugated diene. In any case, vinyl aromatic compounds other than styrene, such as α-methylstyrene, 4-methylstyrene, 2-methylstyrene, vinylnaphthalene, etc., can be used in combination with styrene. As the conjugated diene used in the styrene-based copolymer, isoprene, 1,3-butadiene,
2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene and the like can be mentioned. Among these, isoprene, 1,3 from the viewpoint of polymerization activity and economy.
3-Butadiene is preferred. These may be used alone or in combination of two or more.

As one of those preferably used as the hydrogenated styrene polymer used in the resin composition of the present invention,
Hydrogenated polystyrene obtained by hydrogenating polystyrene is mentioned. The resin has high rigidity, and polystyrene as a precursor is extremely inexpensive and preferable in terms of cost. Other preferable hydrogenated styrenic polymers in the present invention include hydrides of the above styrene-conjugated diene copolymers. The structure of the styrene-conjugated diene copolymer is not particularly limited, but is a styrene-conjugated diene-styrene triblock structure, or a further subdivided multiblock structure, taper type structure, random type structure, or a certain central point. Can be mentioned as a radial type structure. The ratio of the conjugated diene component is also not particularly limited, but the use of hydrogenated styrene-conjugated diene copolymers containing these rubber components has a great effect of improving toughness as compared with hydrogenated polystyrene, but on the other hand rubber The rigidity decreases as the introduced amount of the component increases. Therefore, it is recommended to determine the amount of conjugated diene component in consideration of the physical property balance of the entire resin composition with polycarbonate. The amount of the conjugated diene component in the styrene-conjugated diene copolymer before hydrogenation is preferably 20% by weight or less, more preferably 15% by weight or less, still more preferably 12% by weight or less.

The styrene-based polymer which is a precursor before hydrogenation can be obtained by a known method such as emulsion polymerization, suspension polymerization and solution polymerization. For example, a preferable method for polymerizing the styrene-conjugated diene copolymer is anionic polymerization using an organic lithium or the like as an initiator. In such anionic polymerization, the polymerization reaction is usually performed using a hydrocarbon solvent. Specifically, pentane, hexane, heptane, octane, aliphatic hydrocarbons such as decane, cyclopentane, cyclohexane, methylcyclohexane, cycloaliphatic hydrocarbons such as cyclooctane, benzene, toluene, aromatic hydrocarbons such as xylene. I can name it. Among these hydrocarbon solvents, cyclohexane or methylcyclohexane is preferably used in terms of solubility and reactivity.

In addition to the above hydrocarbon-based solvent, a polar solvent may be used for the purpose of controlling the polymerization reaction, controlling the microstructure of the conjugated diene moiety, and the like. Examples of the polar solvent include ethers such as tetrahydrofuran, dioxane, diethylene glycol dimethyl ether, diethyl ether, methyl ethyl ether and methyl tert-butyl ether, amines such as triethylamine and tetraethylethylenediamine, and phosphines. It is necessary to use those polymerization catalysts that are sufficiently dried and dehydrated.

As the anionic polymerization initiator, an organolithium compound is generally used, and specifically, ethyllithium, n-propyllithium, isopropyllithium, n
-Butyl lithium, sec-butyl lithium, tert
-Butyl lithium and the like. Among these, n-butyllithium or sec-butyllithium is preferably used because of its easy availability and ability to initiate a polymerization reaction. When an organolithium compound is used, the polymerization temperature is usually -20 ° C to 120 ° C, preferably 10 ° C to 1
It is in the range of 00 ° C. The polymerization needs to be carried out in an inert atmosphere such as nitrogen or argon in order to prevent deactivation of the catalyst and the active end of the polymer during the polymerization. Although the polymerization reaction depends on the concentration and kind of the initiator to be used, it is usually completed in a few minutes to a few hours, and a copolymer can be quantitatively obtained almost according to the monomer charging ratio. In this polymerization step, copolymers having various structures can be obtained depending on the method of adding the monomers.
For example, a block copolymer can be obtained by sequentially adding the next monomer after the monomer added previously is almost completely reacted.

In the hydrogenation of the styrene polymer thus obtained, a known method can be used. The hydrogenation catalyst used in the present invention is not particularly limited, and a known catalyst capable of nuclear hydrogenating an aromatic ring can be used. Specifically, a solid catalyst in which a noble metal such as nickel, palladium, platinum, cobalt, ruthenium, or rhodium or a compound such as an oxide, salt, or complex thereof is supported on a porous carrier such as carbon, alumina, silica, or silica / alumina diatomaceous earth. Is mentioned. Among these, those in which nickel, palladium, and platinum are supported on alumina, silica, and silica / alumina diatomaceous earth have high reactivity and are preferably used. The hydrogenation catalyst is preferably used in the range of 0.5 to 40% by weight based on the polymer, depending on its catalytic activity.

The hydrogenation reaction conditions are usually hydrogen pressure of 2.94 to
The reaction is performed at a temperature of 24.5 MPa (30 to 250 kgf / cm ² ) and a reaction temperature of 70 to 250 ° C. If the reaction temperature is too low, the reaction is difficult to proceed, and if the reaction temperature is too high, the molecular weight is likely to decrease due to the cleavage of the molecular chain. In order to prevent the decrease in molecular weight due to the breakage of the molecular chain and to allow the reaction to proceed smoothly, the hydrogenation reaction is carried out at an appropriate temperature appropriately determined by the type and concentration of the catalyst used, the solution concentration of the polymer, the molecular weight, etc. It is preferable to carry out.

The solvent used in the hydrogenation reaction is preferably a solvent which does not poison the hydrogenation catalyst.
Preferable examples are saturated aliphatic hydrocarbons such as cyclohexane and methylcyclohexane used as a solvent during the polymerization reaction. In addition, for the purpose of enhancing the activity of the reaction or suppressing the decrease in the molecular weight due to the breakage of the molecular chain, ethers such as tetrahydrofuran, dioxane and methyl t-butyl ether, polar solvents such as esters and alcohols are added to the polymer. You may add to the said solvent in the range which does not prevent solubility.

In the hydrogenation reaction step, the concentration of the polymer is 3 to 3.
It is preferable to carry out the hydrogenation reaction within the range of 50% by weight. If the concentration of the polymer is less than 3% by weight, it is not preferable from the viewpoint of productivity and economical efficiency, and if it is 50% by weight or more, the solution viscosity is too high, which is not preferable from the viewpoint of handling and reactivity. After completion of the hydrogenation reaction, the catalyst can be removed by a known post-treatment method such as centrifugation or filtration. From the polymer solution from which the hydrogenation catalyst has been removed, the solvent is removed by evaporation,
The hydrogenated styrene polymer can be obtained by a method such as stripping or reprecipitation.

The above hydrogenation reaction is a so-called nuclear hydrogenation reaction, and the aromatic ring derived from styrene has a cyclohexane structure. In the hydrogenated styrene polymer used in the present invention, it is preferable that 80 mol% or more of the aromatic ring is hydrogenated to have a cyclohexane structure. Hydrogenation rate is 80 mol%
If the amount is less than the above range, the number of unhydrogenated polystyrene sites increases, which may reduce the glass transition temperature or the thermal stability during melt molding. More preferably, the hydrogenation rate is 90 mol% or more. Under such hydrogenation reaction conditions, styrene-
In the case of the conjugated diene copolymer, the double bond derived from the conjugated diene component is almost completely hydrogenated. The hydrogenation rate of these can be determined by a method such as NMR measurement.

The molecular weight range of the hydrogenated polymer used in the present invention is the reduced viscosity (0.5 g / d in toluene solution).
L shows the reduced viscosity measured at 30 ° C. The same shall apply hereinafter). The reduced viscosity η _sp / c is 0.1 to 2 dL
/ G is more preferable, and more preferably 0.
2-1dL / g, more preferably 0.25-0.8d
L / g. Reduced viscosity is less than 0.1 dL / g,
That is, when the molecular weight of the polymer is extremely low, the toughness of the resin composition using the polymer tends to decrease, which is not preferable. Further, if the reduced viscosity is higher than 2 g / dL, that is, if the molecular weight of the polymer is too high, the melt fluidity of the resin composition using it tends to decrease, which is not preferable.

The hydrogenated styrene polymer in the present invention has a saturated water absorption of 0.0 when immersed in pure water at 23 ° C.
It is preferably 5% by weight or less, and more preferably 0.02% by weight or less. When the saturated water absorption is high,
As a matter of course, the resin composition with polycarbonate also has a high water absorption rate, and the effect of suppressing the warp of the disk due to the environmental change becomes insufficient. The resin composition of the present invention,
It consists mainly of a polycarbonate resin (a) and a hydrogenated styrene polymer (b), but the weight ratio of both resins is (a) / (b) = 0.5 / 99.5 to 49/51. is there. If the weight ratio is less than 0.5 / 99.5, that is, if the composition of the polycarbonate resin is less than 0.5% by weight, the effect of improving the adhesiveness is insufficient and the weight ratio is 4 or less.
When it is more than 9/51, that is, when the composition of the polycarbonate resin is more than 49% by weight, it tends to be difficult to sufficiently knead with the polycarbonate, and streaky surface roughness occurs on the surface of the molded substrate, and it is used as an optical disc substrate. Becomes difficult. A preferable composition ratio is (a) / (b) =
1/99 to 40/60, more preferably 5/95 to 3
The range is 0/70.

The method for preparing the resin composition by mixing the polycarbonate resin and the hydrogenated styrene polymer is not particularly limited, and the solvent is distilled off from the solution state in which both resins are dissolved, or both resins are melt-kneaded. A known method such as the above can be used. Generally, since the compatibility of both resins is extremely low, it is desirable to mix them as well as possible so that the phase separation structure of the composition becomes fine, and a method of melt-kneading with a biaxial ruder or the like can be preferably mentioned. It is also preferable to use a compatibilizer having compatibility with both resins.

The resin composition of the present invention contains Irganox 1010, 1 in order to improve the thermal stability during melt molding.
076 (manufactured by Ciba-Geigy) and other hindered phenols, Sumilizer GS, GM (manufactured by Sumitomo Chemical Co., Ltd.) partially acrylated polyphenols, Irgafos 1
It is preferable to add stabilizers such as phosphorus compounds represented by phosphite series compounds such as 68 (manufactured by Ciba Geigy).
If necessary, a releasing agent such as a long chain aliphatic alcohol or a long chain aliphatic ester, and other additives such as a lubricant, a plasticizer, an ultraviolet absorber and an antistatic agent can be added. The optical disk substrate in the present invention can be molded using a conventionally known optical disk molding facility. Although the molding conditions depend on the thickness of the substrate and the stamper used, it is necessary to control the molding timely according to the material used. Further, it is necessary to sufficiently dry the material to remove water before molding.

Since the thermal stability of hydrogenated styrene-based polymers is generally inferior to that of polycarbonate, the melting temperature at the time of molding must be determined in consideration of the thermal stability of hydrogenated styrene-based polymers. The temperature is preferably in the range of 300 to 360 ° C., though it depends on the types of polycarbonate and hydrogenated polymer and the molecular weight. The mold temperature during molding is determined in consideration of the balance between the disc transferability, releasability and warpage.
These are greatly affected by the structure of the stamper used and the heat distortion temperature (HDT) of the resin composition. Generally, a lower mold temperature is more advantageous in suppressing warpage,
When the mold temperature is high and the transfer property is poor, the transfer property is good, but there is a tendency that the warp and the mold releasability from the mold are deteriorated.

The optical disk substrate of the present invention becomes an optical disk by forming at least one reflective film on one surface and at least one transparent protective layer on the reflective film. Examples of the material of the reflective film include Al, Au, and an alloy of Al, and the reflective film is formed by an ion beam sputtering method, a DC sputtering method, or the like. Usually, a recording layer such as a phase change recording film or a magneto-optical film is provided on the reflective film according to the recording method. Such a phase change recording film can be formed of a calgon compound or a single chalcogen, for example, each of Te, Se alone, GeTe, Sb ₂ Se ₃ , and G.
eSb ₂ Te ₄ , Ge ₂ Sb ₂ Te ₅ , GeSbTeSe,
Examples include chalcogenite materials such as InSbTe and InSe. The transparent protective layer may be an optical transparent film such as a polycarbonate film, and the method for forming the transparent protective layer may be a method in which an ultraviolet curable resin is used and the resin is adhered by irradiation with ultraviolet rays.

In general, an optical disk has a donut shape, and thus the above-mentioned various metal films are often not formed on the periphery of the center hole and the peripheral edge. Therefore, in an optical disk substrate using a material having low adhesiveness, the decrease in adhesiveness at such a portion is most concerned. The resin composition of the present invention has a hydrogenated styrenic polymer as a main component, but by blending a polycarbonate resin therein, it becomes possible to significantly improve the adhesiveness with an ultraviolet curable resin, and the adhesion of a metal film Good adhesiveness can be exhibited not only in the above-mentioned portion but also in the portion directly bonded to the transparent protective layer. Therefore, according to the present invention, it is possible to provide an optical disk substrate having a significantly reduced water absorption rate while maintaining adhesiveness as compared with a conventional polycarbonate resin.

[0031]

EXAMPLES The present invention will be described in detail below with reference to examples. However, the present invention is not limited to these examples. Cyclohexane as a solvent, styrene as a monomer, and isoprene used in the polymerization of the styrene-isoprene copolymer were all distilled and purified and sufficiently dried. Cyclohexane and methyl t-butyl ether, which were the solvents used during the hydrogenation, were commercial products of special grade. Concentration of n-butyllithium from Kanto Chemical Co., Ltd. was 1.
A 59 M n-hexane solution was purchased and used as it was.
Ni / silica / alumina catalyst (Ni loading 65% by weight)
Was purchased from Aldrich and used as is. The composition ratio and hydrogenation rate of the copolymer are JEOL JNM-A-
It quantified by < ¹ > H-NMR measurement using a 400 type nuclear magnetic resonance absorption apparatus.

Various physical property measurements carried out in Examples and Comparative Examples,
The molding is performed by the following method. 1) Glass transition temperature (Tg): TAInstrumen
Model 920 DSC manufactured by ts is used, and the heating rate is 20 ° C.
It was measured in minutes. 2) Heat distortion temperature (HDT): Measured under a load of 181.3 N / cm ² according to JIS K-7207. 3) Saturated water absorption rate: 50 mmφ, 23 mm thick disc 23
It was immersed in ion-exchanged water at 0 ° C., and the weight change after 7 days was measured. 4) Flexural modulus and flexural strength: JIS K-7203
The bending test was performed according to the following procedure. That is, using UCT-1T manufactured by Orientec Co., Ltd., sample thickness 3 mm, sample width 12 mm, edge span width 46 m
Three-point bending measurement was performed at m and a crosshead speed of 2 mm / min to calculate bending elastic modulus (GPa) and bending strength (MPa).

5) Disc molding: An injection molding machine (model "MO40D3H") manufactured by Nissei Plastic Co., Ltd. was used, and a stamper corresponding to a blue laser having a land / groove structure with a groove depth of 40 nm and a groove pitch of 300 nm was used. . As molding conditions, the cylinder temperature is 330 ° C., the mold temperature is 120 ° C. (fixed mold with a stamper), 1
Molding was performed at 15 ° C. (moving side mold) and a cooling time of 15 seconds. 6) Disc transferability and surface observation: Atomic force microscope (model "SFA-300") manufactured by Seiko Instruments Inc.
Was used to observe the land depth, land / groove shape and surface state at a position 58 mm from the center. 7) Evaluation of Adhesion: Of the adhesion evaluations according to JIS K5400, the evaluation was made according to the X-cut tape method. Recording surface side of optical disc (side to which transparent protective film is attached)
Select a place around the center hole where the reflective film is not provided, make a X-shaped notch with an angle of 30 ° using a cutter knife, and stick Nichiban Cellotape on it and peel it off to remove it. I observed.

[Production Example 1] A homopolymer of polystyrene (BAS) was placed in a stainless steel autoclave having a capacity of 10 L.
Company F Type 158K, weight average molecular weight 280,0
00) 800 g to cyclohexane 2400 g, methyl t
-Dissolve in a mixed solvent of 800 g of butyl ether,
/ Silica-alumina catalyst (Ni loading 65% by weight) 10
0 g was added, and the hydrogen pressure was 9.81 MPa (100 kg / cm
² ) and hydrogenated at a temperature of 180 ° C. for 6 hours.

After returning to room temperature and performing nitrogen substitution sufficiently, the solution was taken out from the autoclave and subjected to pressure filtration using a membrane filter having a pore size of 0.1 micron (“Fluoropore” manufactured by Sumitomo Electric Industries, Ltd.). A colorless transparent solution was obtained. To this clear solution, 0.4% by weight of Sumilizer GS (Sumitomo Chemical Co., Ltd.) as a stabilizer was added to the polymer, and then the solution was concentrated under reduced pressure and flushed to remove the solvent. Pelletization was performed to obtain colorless and transparent hydrogenated polystyrene pellets. The reduced viscosity η _sp / c measured at 30 ° C. in a toluene solution having a resin concentration of 0.5 g / dL was 0.50 dL / g. Also ¹ H
-The hydrogenation rate of the aromatic ring measured by NMR was 99.2%.

[Production Example 2] The interior of a stainless steel autoclave having a volume of 10 L was thoroughly dried and replaced with nitrogen,
A solution of 380 g of styrene and 1300 g of cyclohexane was charged. Then, an amount corresponding to 7.1 mmol of n-butyllithium was added in the form of a cyclohexane solution having a concentration of 1.59 M to initiate polymerization. After stirring for 2 hours at a temperature of 50 ° C. to completely react styrene, 85 g of isoprene,
A solution of 250 g of cyclohexane was added and further reacted at 50 ° C. for 2 hours. Then, a solution of 383 g of styrene and 780 g of cyclohexane was added, and the mixture was further reacted at 50 ° C. for 2 hours. After this, 2 mL of isopropanol was added to stop the reaction.

A portion of this polymerization solution was sampled and ¹ H
-By NMR, the amount of isoprene component in the copolymer was 9.8% by weight, which was almost the same as the charged amount. To this copolymer solution, 300 g of cyclohexane, 700 g of methyl t-butyl ether, Ni / silica-alumina catalyst (N
i supported amount of 65% by weight) 80 g was added, and a hydrogen pressure of 9.81 MPa (100 k) was used using an autoclave with a capacity of 10 L.
g / cm ^2), it was carried out for 6 hours hydrogenation reaction at a temperature of 180 ° C.. After returning to room temperature and performing nitrogen substitution sufficiently, the solution was taken out from the autoclave and pressure-filtered using a membrane filter having a pore size of 0.1 micron (“Fluoropore” manufactured by Sumitomo Electric Industries, Ltd.). A solution was obtained.

After adding 0.3% by weight of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) as a stabilizer to the transparent solution, the solution was concentrated under reduced pressure and flushed to remove the solvent. It was removed and pelletized to obtain a colorless transparent pellet of hydrogenated styrene-isoprene copolymer. In a toluene solution of such a resin having a concentration of 0.5 g / dL, 30
The reduced viscosity η _sp / c measured at 0 ° C was 0.46 dL / g. Further, as measured by ¹ H-NMR, the hydrogenation rate of the isoprene component was 99.9 mol% or more and substantially all was hydrogenated, and the hydrogenation rate of the aromatic ring was 99.3%. Do you get it.

[Example 1] Pellets (a) of polycarbonate (trade name "Panlite AD5503") manufactured by Teijin Chemicals Ltd. and pellets (b) of hydrogenated polystyrene obtained in Production Example 1 were used in a weight ratio. Is (a) / (b) = 10/9
Mix to 0. Then, the mixed pellets were extruded using a biaxial ruder at a temperature of 280 ° C. while being melt-kneaded to obtain pellets of a target resin composition. In order to measure various physical properties of such a resin composition, injection molding is performed at a cylinder temperature of 320 ° C. and a mold temperature of 60 ° C. using an injection molding machine (model “PS20E2A”) manufactured by Nissei Resin Co., Ltd.
A cloudy molded product was obtained. The physical property measurement results are shown in Table 1.

Separately from this molding, the resin composition pellets were molded into an injection molding machine (model "MO40" manufactured by Nissei Plastic Industry Co., Ltd.).
D3H ") was used to form a disk having a diameter of 120 mm and a thickness of 1.2 mm. The obtained disc substrate is AF
It was found from the M measurement that both the depth and the shape were transferred according to the land / groove structure of the stamper, and the smoothness of the substrate surface was high. Also, the warp of the substrate was small.

After depositing an aluminum thin film on the stamper surface of the disk substrate by sputtering,
In addition, a UV curable resin (trade name "KA" manufactured by Nippon Kayaku Co., Ltd.
RAYAD KCD-805 ") was applied by spin coating, and a thickness of 7 obtained by solution film formation thereon.
200 μm polycarbonate film is stuck together, 200
Adhesion was performed by UV curing in which ultraviolet light of mW / cm ² was irradiated for 5 seconds. On the surface of the obtained optical disk on which the polycarbonate film is attached, JISK5400
A peeling test was conducted according to the X-cut tape method of the adhesiveness evaluation method described in 1., and it was found that the bonded film did not peel off and the adhesiveness was good.

[Example 2] Pellets (a) of polycarbonate (trade name "Panlite AD5503") manufactured by Teijin Chemicals Ltd. and pellets (b) of hydrogenated polystyrene obtained in Production Example 1 were used in a weight ratio. Is (a) / (b) = 20/8
A resin composition was prepared and a sample for measuring physical properties was molded in the same manner as in Example 1 except that the mixture was mixed so as to be 0. The physical properties of the molded product are shown in Table 1. Further, in the same manner as in Example 1, disk molding of the resin composition and subsequent disk substrate treatment were performed. The depth and shape of the obtained disk substrate were transferred through a stamper by AFM measurement.
It was also found that the smoothness of the substrate surface was high. Also, the warp of the substrate was small.

After sputtering such a disk substrate in the same manner as in Example 1, the polycarbonate film was UV-irradiated.
An optical disk was prepared by bonding the pieces together by curing. The adhesiveness of the film was evaluated in the same manner as in Example 1, but it was found that the adhesiveness was good without peeling in the peeling test.

[Example 3] Pellets (a) of polycarbonate (trade name "Panlite AD5503") manufactured by Teijin Chemicals Ltd. and pellets of hydrogenated styrene-isoprene-styrene copolymer obtained in Production Example 2 ( A resin composition was prepared and a sample for measuring physical properties was molded in the same manner as in Example 1 except that b) was mixed so that the weight ratio was (a) / (b) = 20/80. The physical properties of the molded product are shown in Table 1.
Further, in the same manner as in Example 1, disk molding of the resin composition and subsequent disk substrate treatment were performed. It was found by AFM measurement that the obtained disk substrate was transferred through a stamper in terms of both depth and shape, and that the substrate surface had high smoothness. Also, the warp of the substrate was small. After sputtering this disc substrate in the same manner as in Example 1, a polycarbonate film was attached by UV curing to form an optical disc. The adhesiveness of the film was evaluated in the same manner as in Example 1, but it was found that the adhesiveness was good without peeling in the peeling test.

Comparative Example 1 The hydrogenated polystyrene obtained in Production Example 1 was subjected to the same procedure as in Example 1 to form a sample for measuring physical properties, disk formation and subsequent disk substrate treatment.
Table 1 shows the results of measuring the physical properties of the molded product. It was found by AFM measurement that the obtained disk substrate was transferred through a stamper in terms of both depth and shape, and that the substrate surface had high smoothness. After sputtering this disk substrate in the same manner as in Example 1, the polycarbonate film is UV-irradiated.
An optical disk was prepared by bonding the pieces together by curing. The adhesiveness of the film was evaluated in the same manner as in Example 1, but in the peeling test, the film was completely peeled off and the adhesiveness was poor.

[0046]

[Table 1]

From Table 1, it can be seen that the optical disk substrate using the resin composition of the present invention has low hygroscopicity and excellent adhesiveness.

[0048]

According to the present invention, a novel resin composition comprising a hydrogenated styrene polymer and a polycarbonate resin is provided. Such a resin composition has lower water absorption, which is a cause of warpage due to environmental changes, than the case of using a polycarbonate resin alone, and the adhesiveness is significantly improved as compared to the case of using a hydrogenated styrene-based polymer alone. It is preferably used as a material for a new type optical disc substrate in which a laser beam is incident and read from the recording surface side formed in the above.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 69:00) (C08L 25/02 69:00) (72) Inventor Shunichi Matsumura Hinode Town, Iwakuni City, Yamaguchi Prefecture No. 2 No. 1 F-term in Iwakuni Research Center, Teijin Limited (reference) 4J002 AC111 BC011 BP011 CG002 CG012 CG022 CG032 FD03 GS02 4J100 AA02Q AA03Q AA20P AB02P AS02Q AS03Q AS04Q CA01 CA04 CA31 HA04 HA05 HB29 K35 JA14 HE35 HD14 HD22 HE22

Claims (7)

[Claims] 1. A resin composition mainly comprising a polycarbonate resin (a) and a hydrogenated styrene polymer (b), the weight ratio of which is (a) / (b) = 0.5 / 99.
The resin composition is in the range of 5 to 49/51. 2. The resin composition according to claim 1, wherein the polycarbonate resin (a) is an aromatic polycarbonate mainly containing 2,2-bis (4-hydroxyphenyl) propane as a bisphenol component. 3. The resin composition according to claim 1, wherein the hydrogenated styrene-based polymer (b) is hydrogenated polystyrene obtained by hydrogenating 80 mol% or more of the aromatic ring of polystyrene. 4. The hydrogenated styrenic polymer (b) comprises all double bonds derived from a conjugated diene component in a copolymer of styrene and a conjugated diene, and 80 aromatic rings derived from the styrene component. The resin composition according to claim 1 or 2, which is a hydrogenated styrene-conjugated diene copolymer obtained by hydrogenating mol% or more. 5. An optical disk substrate using the resin composition according to claim 1. 6. A resin substrate, on which at least one reflective film and at least one transparent protective layer are formed on the reflective layer, and laser light is incident from the transparent protective layer side, or on the resin substrate. The thickness of the substrate used in an optical disk for reading and / or writing information on a recording layer formed on the resin substrate is 0.
The optical disk substrate according to claim 5, which is in a range of 3 to 1.2 mm. 7. An optical disc using the optical disc substrate according to claim 6.