JP2002121374A - Polycarbonate resin molding material for optics and optical disk substrate made of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polycarbonate resin molding material for optics capable of not only having high reliability on production for a long time, but also improving productivity of a substrate, and an optical disk substrate. SOLUTION: The polycarbonate resin molding material for optics contains at most 50 ppm of a substance represented by formula (1) and at most 50 ppm of a substance represented by formula (2). The optical disk substrate made of the molding material is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical polycarbonate resin molding material and an optical disk substrate capable of maintaining high reliability for a long period of time and improving substrate productivity.

[0002]

2. Description of the Related Art Optical disks for recording and reproducing information by irradiating a laser beam include digital audio disks (so-called compact disks), optical video disks (so-called laser disks), various write-once disks, magneto-optical disks, and phase-change disks. Changeable disks and the like have been put to practical use. Of these, compact discs and laser discs are read-only (Read Only Memory:
ROM) type optical disk. In these optical disks, pits corresponding to information signals are formed in an uneven shape on a transparent substrate, and an Al reflective layer is formed thereon with a thickness of 40 nm or more. In such an optical disc, an information signal is reproduced by detecting a change in reflectance caused by optical interference generated in the pit.

On the other hand, a write-once optical disc has an R (Recordable) on which arbitrary information can be written by a user.
e) type optical disk, a magneto-optical disk and a phase change type disk are RAMs (Random Access Memory) in which arbitrary information can be repeatedly written.
y) type optical disc. That is, the R-type optical disc is formed of a write-once recording layer on a transparent substrate, the optical characteristics of which are irreversibly changed by irradiation of a laser beam, or the uneven shape is formed. As the recording layer, for example, a cyanine-based, phthalocyanine-based, or azo-based organic dye that is decomposed by heating by laser light irradiation, changes its optical constant, and causes deformation of the substrate due to volume change is used.

A magneto-optical disk allows a user to repeatedly write and delete information.
This is a rewritable optical disk that has a T
A perpendicular magnetization film having a magneto-optical effect (for example, the Kerr effect) such as a b-Fe-Co amorphous alloy thin film is formed. In this magneto-optical disk, recording pits are formed by magnetizing a small region of a perpendicular magnetization film upward or downward in response to an information signal. The information signal is reproduced by utilizing the fact that the rotation angle θk (Kerr rotation angle) of the linearly polarized light in the reflected light differs depending on the direction of magnetization of the perpendicular magnetization film.

A phase-change disk is a rewritable disk like a magneto-optical disk. For example, a phase-change disk exhibits a crystalline state in an initial state and changes its phase to an amorphous state when irradiated with a laser beam. A phase change material or the like is used. In this recording layer, recording pits are formed by phase-changing a minute area in response to an information signal.
The information signal is reproduced by detecting a change in the reflectance between the amorphous portion corresponding to the pit and the other crystal region.

In such a magneto-optical disk or a phase change disk, both sides of the recording layer are sandwiched between transparent dielectric layers for the purpose of preventing the recording layer from being oxidized and increasing the degree of signal modulation due to multiple interference. In many cases, a four-layer structure in which Al reflective layers are stacked is adopted. In addition, as the dielectric layer, a silicon nitride film, a Zn—SiO ₂ mixed film, or the like is used. By the way, recently, studies on using such an optical disk for digital video recording have been actively conducted, and a digital versatile disk (DVD) has been developed as such an optical disk.

The DVD has a diameter of 120 mm, which is the same as that of a CD, and records video information equivalent to one movie, so that the DVD can be reproduced with image quality comparable to that of a current television. Here, recording such video information on an optical disk requires, for example, a recording capacity 6 to 8 times that of a CD. For this reason, in DVD, the laser wavelength is set to 78 for CD.
By shortening the wavelength to 635-650 nm with respect to 0 nm and increasing the numerical aperture NA of the objective lens to 0.52 or 0.6 with respect to 0.45 in CD, the shortest recording mark of the track pitch or pit is obtained. The length is shortened and the recording density is increased.

[0008] Of these, an increase in the numerical aperture NA of the objective lens reduces the allowable amount of warpage of the disk substrate. For this reason, in the case of DVD, the thickness of the substrate is reduced to 0.6 mm from 1.2 mm of the CD, whereby
The distance that the laser light passes through the disk substrate is shortened to compensate for the allowable amount of warpage (Nikkei Electronics, February 27, 1995 No. 630).
Then, as described in JP-A-6-274940, in order to compensate for a decrease in disk strength due to further thinning of the substrate, the substrate is further laminated on a recording layer formed on the substrate, so-called, Adhered structure is adopted. As the recording layer of the bonded optical disc, a ROM-type recording layer used in the above-described single-plate configuration,
Either the R-type recording layer or the RAM-type recording layer can be adopted.

Further, the bonded optical disk includes a single-sided bonded optical disk using only one surface thereof,
There is a double-sided bonded optical disk using both sides. For the optical disk substrates as described above, polycarbonate resins excellent in moldability, strength, light transmittance, moisture resistance, and the like are often used.

However, the polycarbonate resin having such excellent properties also has a disadvantage that it is easily hydrolyzed under high temperature and high humidity, and is liable to decrease in molecular weight and impact strength. Further, if the substrate is left under high temperature and high humidity for a long period of time, there is a disadvantage that minute white spots are generated on the substrate and the long-term reliability is impaired.

On the other hand, with the spread of optical discs in recent years, there has been an increasing demand for improved substrate productivity. The resin contains various volatile components as impurities, and if molding is performed for a long period of time, various components accumulate on a mold, a stamper, and the like, which leads to deterioration of substrate characteristics such as optical and mechanical characteristics. In addition, there is a problem that the above various substrate characteristics are deteriorated by long-time molding. For this reason,
In order to clean the mold and the stamper, the continuous molding had to be temporarily stopped, which had an adverse effect on the improvement of productivity.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and as a result of intensive studies on the problems, the following formula (1) in a polycarbonate resin was obtained.
By reducing the content of the substance represented by the formula and the content of the substance represented by the formula (2), deterioration of the substrate made of the polycarbonate resin can be controlled very effectively, and high reliability can be maintained for a long period of time. I found that a disc was obtained. In addition, the reduction of the substance represented by the formula (1) and the substance represented by the formula (2) leads to a reduction in volatile components at the same time, and an optical polycarbonate resin molding material and an optical disc substrate having improved substrate productivity. Was also found.

[0013]

That is, the present invention provides a polycarbonate resin having a content of a substance represented by the following formula (1) of 50 ppm or less and a content of a substance represented by the formula (2) of 50 ppm or less. An optical polycarbonate resin molding material and an optical disk substrate made of the same.

[0014]

Embedded image

Wherein A is a hydrogen atom, an alkyl group, a phenylalkyl group or an aliphatic ester group, and r is an integer of 1 to 5.

[0016]

Embedded image

Wherein A is a hydrogen atom, an alkyl group, a phenylalkyl group or an aliphatic ester group, and r is an integer of 1 to 5.

In the present invention, CD-R, CD-R
W, MO, digital video disk, DVD-ROM,
Digital versatile discs (DVs represented by DVD-audio, DVD-R, DVD-RAM, etc.)
D) In order to obtain sufficient reliability as a substrate for an optical disk substrate, particularly a disk substrate used for a high-density optical disk such as a DVD substrate, and to improve substrate productivity, a molding material provided for molding the substrate The content of the substance represented by the formula (1) in the (aromatic polycarbonate resin) is 50.
ppm or less and the content of the substance represented by the formula (2) is 50 or less.
It is necessary to be below ppm. Here, equation (1)
And in (2), A is a hydrogen atom, an alkyl group or an aliphatic ester group, preferably an alkyl group having 1 to 9 carbon atoms or a phenylalkyl group (the alkyl portion has 1 to 9 carbon atoms); r is an integer of 1 to 5, preferably 1 to 3. These indicate the contents of those added as terminal stoppers during the polymerization reaction of the polycarbonate resin and remaining as a simple substance in the resin, and those released during the polymerization reaction and remaining as a simple substance in the resin.

When the content of the substance represented by the formula (1) is 50 p
pm or less and the content of the substance represented by the formula (2) is 50 p
When the pressure is suppressed to not more than pm, generation of minute white spots on the substrate and the number of times of cleaning the mold and the stamper can be minimized. When a material having a content of the substance represented by the formula (1) or a content of the substance represented by the formula (2) exceeding 50 ppm is used, sufficient reliability and substrate productivity cannot be obtained.

The effect of ensuring that the content of the substance represented by the formula (1) is 50 ppm or less, preferably 30 ppm or less, more preferably 20 ppm or less can be obtained. Most preferred is 10 ppm or less. The content of the substance represented by the formula (2) is 50 pp.
m or less, preferably 40 ppm or less, and more preferably 30 ppm or less can provide a certain effect. Most preferred is 15 ppm or less.

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 melting method.
Representative examples of the dihydric phenol used here include 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 (commonly known as 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, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 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, α,
α'-bis (4-hydroxyphenyl) -o-diisopropylbenzene, α, α'-bis (4-hydroxyphenyl) -m-diisopropylbenzene, α, α'-bis (4-hydroxyphenyl) -p-diisopropyl Benzene, 1,3-bis (4-hydroxyphenyl) -5,7
-Dimethyladamantane, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfoxide, 4,4'-dihydroxydiphenylsulfide, 4,4'-dihydroxydiphenylketone,
4'-dihydroxydiphenyl ether and 4,4 '
-Dihydroxydiphenyl ester and the like, and these can be used alone or in combination of two or more.

Bisphenol A, 2,2-bis {(4-hydroxy-3-methyl) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane,
2,2-bis (4-hydroxyphenyl) -3-methylbutane, 2,2-bis (4-hydroxyphenyl) -3,
3-dimethylbutane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane and α, α′-bis ( 4-hydroxyphenyl)
Homopolymers or copolymers obtained from at least one bisphenol selected from the group consisting of -m-diisopropylbenzene are preferred, and bisphenol A is particularly preferred.
And 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane and bisphenol A, 2,2-bis {(4-hydroxy-3-methyl) phenyl} propane or α, α'-bis (4-
A copolymer with (hydroxyphenyl) -m-diisopropylbenzene is preferably used.

As the carbonate precursor, carbonyl halide, carbonate ester, haloformate and the like are used, and specific examples include phosgene, diphenyl carbonate and dihaloformate of dihydric phenol.

In producing the polycarbonate resin by reacting the dihydric phenol with the carbonate precursor by an interfacial polymerization method or a melting method, a catalyst, an antioxidant of the dihydric phenol, etc. may be used, if necessary. Is also good.
Further, the polycarbonate resin may be a branched polycarbonate resin obtained by copolymerizing a trifunctional or higher polyfunctional aromatic compound, or a polyester carbonate resin obtained by copolymerizing an aromatic or aliphatic bifunctional carboxylic acid,
Further, a mixture of two or more of the obtained polycarbonate resins may be used.

The reaction by the interfacial polymerization method is usually a reaction between dihydric phenol and phosgene, and 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, for example, halogenated hydrocarbons such as methylene chloride and chlorobenzene are used. Further, for promoting the reaction, for example, 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 may be used. it can. At that time, the reaction temperature is usually 0 to 40 ° C., the reaction time is preferably about 10 minutes to 5 hours, and the pH during the reaction is preferably maintained at 9 or more.

The reaction by the melting method is usually a transesterification reaction between a dihydric phenol and a carbonate ester,
The method is carried out by a method in which a dihydric phenol and a carbonate ester are mixed while heating in the presence of an inert gas to distill a monohydroxy compound (eg, phenol) to be produced. The reaction temperature varies depending on the boiling point of the monohydroxy compound to be formed and the like, but is usually in the range of 120 to 350 ° C. In the latter stage of the reaction, the pressure of the system is reduced to about 10 to 0.1 Torr to facilitate the distillation of the generated monohydroxy compound. Since the monohydroxy compound generated during the reaction remains in the polycarbonate resin, a sufficient reaction time is required, and the reaction time is about 1 to 4 hours.

Examples of the carbonate ester include an optionally substituted 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. Specific examples include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate and the like. Is preferred.

A polymerization catalyst can be used to increase the polymerization rate. Examples of the polymerization catalyst include sodium hydroxide, potassium hydroxide, alkali metal compounds such as sodium and potassium salts of dihydric phenol, and water. Alkaline earth metal compounds such as calcium oxide, barium hydroxide and magnesium hydroxide; nitrogen-containing basic compounds such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethylamine and triethylamine; alkoxides of alkali metals and alkaline earth metals Manganese, organic acid salts of alkali metals and alkaline earth metals, zinc compounds, boron compounds, aluminum compounds, silicon compounds, germanium compounds, organic tin compounds, lead compounds, osmium compounds, antimony compounds Compounds, titanium compounds, usually the esterification reaction, such as zirconium compounds, there can be used a catalyst used in the transesterification reaction. The catalyst may be used alone or in combination of two or more. The amount of the polymerization catalyst to be used is preferably 1 × 10 ⁻⁸ to 1 × 10 ⁸ per 1 mol of the starting dihydric phenol.
^-4 equivalents, more preferably 1 × 10 ^{−7 to} 5 × 10 ⁻⁴ equivalents.

In order to reduce the number of phenolic terminal groups in the polymerization reaction, a terminal stopper other than monofunctional phenols, for example, bis (chlorophenyl) carbonate, bis (bromo) Compounds such as phenyl) carbonate, bis (nitrophenyl) carbonate, bis (phenylphenyl) carbonate, chlorophenylphenylcarbonate, bromophenylphenylcarbonate, nitrophenylphenylcarbonate, phenylphenylcarbonate, methoxycarbonylphenylphenylcarbonate and ethoxycarbonylphenylphenylcarbonate Is preferably added. Among them, 2-chlorophenylphenyl carbonate and 2-methoxycarbonylphenylphenyl are preferable, and 2-methoxycarbonylphenylphenyl is particularly preferably used.

In the polymerization reaction of the polycarbonate resin by the interfacial polymerization method, a monofunctional phenol is used as a terminal stopper. Monofunctional phenols are used as molecular terminators to control the molecular weight, and the resulting polycarbonate resin has a higher thermal stability than non-phenolic ones because the ends are blocked by groups based on monofunctional phenols. Is excellent.

As such monofunctional phenols, monofunctional phenols represented by the following general formulas (3) to (5) can be shown.

[0032]

Embedded image

[In the formula, B is a hydrogen atom or an alkyl group having 1 to 9 carbon atoms or a phenylalkyl group of each alkyl group, and r is an integer of 1 to 5, preferably 1 to 3].

[0034]

Embedded image

[0035]

Embedded image

[In these formulas, X is -RO-, -RC
Wherein R represents a single bond or a divalent aliphatic hydrocarbon group having 1 to 10, preferably 1 to 5 carbon atoms, and n represents 10 to 50. Indicate the integer of

Specific examples of the monofunctional phenol represented by the general formula (3) include, for example, isopropylphenol, p-tert-butylphenol, p-cresol, p-cumylphenol and isooctylphenol.

The monofunctional phenols represented by the above general formulas (4) and (5) are phenols having a long-chain alkyl group or an aliphatic ester group as a substituent. When the ends of the resin are blocked, these not only function as a terminator or a molecular weight regulator, but also improve the melt flowability of the resin, which facilitates molding and processing, as well as physical properties as a substrate,
Particularly, it has an effect of lowering the water absorption of the resin, and has an effect of reducing the birefringence of the substrate, and is preferably used.

The substituted phenols of the above general formula (4) are preferably those having n of 10 to 30, especially 10 to 26, and specific examples thereof include decyl phenol, dodecyl phenol, tetradecyl phenol, hexadecyl phenol and Octadecylphenol, eicosylphenol, docosylphenol, triacontylphenol and the like can be mentioned.

As the substituted phenols of the above general formula (5), a compound in which X is -R-CO-O- and R is a single bond is suitable, and n is 10 to 30, especially 10 to 30
26 are preferred, examples of which include, for example, decyl hydroxybenzoate, dodecyl hydroxybenzoate, tetradecyl hydroxybenzoate, hexadecyl hydroxybenzoate, eicosyl hydroxybenzoate, docosyl hydroxybenzoate and tricontyl hydroxybenzoate. No.

Among these monofunctional phenols, monofunctional phenols represented by the above formula (3) are preferred, more preferably alkyl-substituted or phenylalkyl-substituted phenols, and particularly preferably p-tert.
-Butylphenol or p-cumylphenol. These monofunctional phenolic terminal stoppers are used in at least 5 terminals relative to all terminals of the obtained polycarbonate resin.
Mol%, preferably at least 10 mol%, is introduced at the end, and the terminator is used alone or
You may mix and use more than one kind.

The polycarbonate resin has a viscosity average molecular weight (M) of preferably 10,000 to 22,000, more preferably 12,000 to 20,000, and more preferably 13,000 to 20,000.
000 to 18,000 is particularly preferred. A polycarbonate resin having such a viscosity average molecular weight is preferable because sufficient strength is obtained as an optical material, and the melt fluidity during molding is good, and molding distortion is not generated. The viscosity average molecular weight referred to in the present invention is obtained by inserting the specific viscosity (η _sp ) obtained from a solution obtained by dissolving 0.7 g of a polycarbonate resin in 100 mL of methylene chloride at 20 ° C. into the following equation.

Η _sp /c=[η]+0.45×[η] ² c
(Where [η] is the limiting viscosity) [η] = 1.23 × 10 ⁻⁴ M ^0.83 c = 0.7 The raw material polycarbonate resin was produced by a conventionally known ordinary method (interfacial polymerization method, melt polymerization method, etc.). After that, alkali extraction or filtration treatment in a solution state or granulation (desolvation) of the granular raw material is performed using, for example, ketones such as acetone, aliphatic hydrocarbons such as hexane, and polycarbonates such as aromatic hydrocarbons such as xylene. It is preferable to remove impurities and foreign substances such as low molecular weight components and unreacted components by washing with a poor solvent and a non-solvent. Further, in the extrusion step (pelletizing step) of obtaining a pellet-like polycarbonate resin for use in injection molding, it is preferable to remove foreign matter 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 additives such as a release agent such as a polyhydric alcohol fatty acid ester and an antioxidant such as a phosphorus compound. In any case, it is necessary to minimize the content of foreign materials, impurities, solvents and the like in the raw material resin before injection molding.

As a method for reducing the content of the substances represented by the formulas (1) and (2), for example, after the addition of the monofunctional phenols, a catalyst is added to carry out a sufficient reaction,
After manufacturing by a conventionally known conventional method (solution polymerization method, melt polymerization method, etc.), alkali extraction in a solution state,
The granular raw material after granulation (desolvation) is removed by washing with a poor solvent and a non-solvent such as a polycarbonate such as ketones such as acetone, aliphatic hydrocarbons such as hexane, and aromatic hydrocarbons such as xylene. Is preferred. These methods and means are desirably combined or repeated until the content of the substances represented by the formulas (1) and (2) is reduced to a target value. As an example, in the acetone extraction, the amount used is larger than that of the conventional polycarbonate resin, for example, about 10 times by weight or more, or the extraction temperature is increased, and the extraction is agitated more than before. There is a method such as powerfully performing.

When an optical disk substrate is manufactured from the above polycarbonate resin, an injection molding machine (including an injection compression molding machine) is used. As this injection molding machine, a commonly used one may be used, but from the viewpoint of suppressing the generation of carbides and increasing the reliability of the disk substrate, the adhesion to the resin as a cylinder or a screw is low, and the corrosion resistance and abrasion resistance are low. It is preferable to use a material made of a material having properties.
Injection molding conditions are cylinder temperature 300-400.
C. and a mold temperature of 50 to 140 ° C. are preferred, whereby an optically excellent optical disc substrate can be obtained. The environment in the molding step is preferably as clean as possible from the viewpoint of the present invention. It is also important to sufficiently dry the material to be subjected to molding to remove moisture, and to take care not to cause stagnation that may cause decomposition of the molten resin. It is also important to take care not to use a substrate having an abnormality in birefringence, mechanical characteristics, etc. as a product or a test substrate.

The optical disk substrate made of the optical polycarbonate resin molding material according to the present invention has very small generation of minute white spots even when it is kept under high temperature and high humidity conditions for a long time.
DR, CD-RW, MO, digital video disk,
DVD-ROM, DVD-audio, DVD-R, D
Digital versatile, represented by VD-RAM, etc.
It is excellent as a substrate of an optical disk of a disk (DVD), particularly a substrate of a DVD. The characteristics under the conditions of high temperature and high humidity are as follows. The disk is left in a constant temperature and humidity chamber controlled at a temperature of 80 ° C. and a relative humidity of 85% for 1000 hours, and has a size of 20 μm.
It is confirmed by checking the number of white spots generated above. The number of white spots generated on a disk obtained from the polycarbonate resin molding material according to the present invention was 2 per substrate having a diameter of 120 mm.
Or less, and preferably one or less.

[0047]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The evaluation was performed according to the following method. (1) Quantitative analysis of the substance represented by the formula (1) Quantification was performed using high performance liquid chromatography (HPLC). (2) Quantitative analysis of the substance represented by the formula (2) Quantification was performed using high performance liquid chromatography (HPLC). (3) Long-term reliability test Disk molding machine [DISK 3M manufactured by Sumitomo Heavy Industries, Ltd.]
III] optical disc substrate (diameter 120
mm, thickness 1.2 mm) at a temperature of 80 ° C and a relative humidity of 85.
%, The number of white spots having a size of 20 μm or more in the substrate was counted. This was performed for 25 optical disk substrates, and the average value was determined, and this was defined as the number of white spots.

(4) CD productivity test Injection molding machine, DISK3 M III manufactured by Sumitomo Heavy Industries, Ltd.
Attach a mold for exclusive use of CD to the mold, attach a stamper for pitted nickel CD to this mold, and put the molding material into the hopper of the molding machine by automatic conveyance, cylinder temperature 330 ° C, mold temperature The molding was continuously performed at 65 ° C. After the start of continuous molding, the number of defective substrates produced increased due to abnormal birefringence and mechanical properties, and the number of molded substrates until the number of defective substrates per 100 units exceeded 10% was determined. The criteria for conforming product boards were as follows: the birefringence was ± 100 nm or less in a double pass, and the mechanical characteristics were ± 1.6 degrees in a radial warpage angle.

(5) DVD productivity test Injection molding machine, DISK3 M III manufactured by Sumitomo Heavy Industries, Ltd.
A mold for DVD is attached to the mold, a nickel stamper for DVD made of pits is mounted on the mold, and a molding material is automatically fed into a hopper of a molding machine. The molding was continuously performed at 112 ° C., and the number of molded sheets was obtained in the same manner as in the CD productivity test. The criterion for judging the quality of a production board is that the birefringence is ± 100 nm or less in a double pass, and the mechanical properties are ±
The angle was set to within 0.8 degrees and the circumferential warpage angle was set to within ± 0.3 degrees.

Example 1 The compound of formula (1), in which r is 1 and the moiety A is bonded to the para-position by a tert-butyl group at a concentration of 23 ppm, where r is 1 and the moiety A is Is bonded to the para-position by a tert-butyl group,
pm-containing 2,2-bis (4-hydroxyphenyl) propane skeleton polycarbonate powder, 40 ppm of a phosphorus-based antioxidant [tris (2,4-di-t-butylphenyl) phosphite] and an aliphatic ester (glycerin) After adding 350 ppm of monostearate), the mixture was pelletized by an extruder. Table 1 shows the results of a long-term reliability test, a CD productivity test, and a DVD productivity test performed using the obtained pellets.

Example 2 In Example 1, r is 1 and A portion is tert-
11 ppm of a substance represented by the formula (1) bonded to the para position by a butyl group is contained, r is 1, and A part is te.
A 2,2-bis (4- (4-phenyl) group containing 25 ppm of a substance represented by the formula (2) bonded to the para position with an rt-butyl group.
The same operation as in Example 1 was performed except that a (hydroxyphenyl) propane skeleton polycarbonate powder was used. Table 1 shows the results.

Example 3 In Example 1, r is 1 and A portion is tert-
6 ppm of a substance represented by the formula (1) bonded to the para position with a butyl group is contained, r is 1, and the A portion is ter.
Except that a 2,2-bis (4-hydroxyphenyl) propane skeleton polycarbonate powder containing 7 ppm of a substance represented by the formula (2) bonded to the para position with a t-butyl group was used. The same operation as in No. 1 was performed. Table 1 shows the results.

Comparative Example 1 In Example 1, r was 1 and A portion was tert-
82 ppm of a substance represented by the formula (1) bonded to the para position by a butyl group is contained, r is 1, and the A portion is te.
2,2-Bis (4-containing 95 ppm of a substance represented by the formula (2) bonded to the para position with an rt-butyl group.
The same operation as in Example 1 was performed except that a (hydroxyphenyl) propane skeleton polycarbonate powder was used. Table 1 shows the results.

From these results, in order to obtain a highly reliable high-density optical disk substrate, the content of the substance represented by the formula (1) contained in the optical polycarbonate resin molding material used for substrate molding was 50 ppm. It is clear that the content of the substance represented by the following formula (2) must be reduced to 50 ppm or less.

[0055]

[Table 1]

[0056]

According to the molding material of the present invention, the content in the material, that is, the content of the substance represented by the following formula (1) is 50 ppm or less and the content of the substance represented by the formula (2): , Which is as low as 50 ppm or less, and a polycarbonate resin molding material for optical use and an optical disk substrate that can maintain high reliability for a long period of time and improve substrate productivity can be obtained. The effects achieved by optical disks such as CD-Rs, CD-RWs, MOs, and digital versatile disks (DVDs), especially DVDs, are particularly remarkable.

Continued on the front page F term (reference) 4F071 AA50 AA81 AC10 AH12 BB05 BC01 4J002 CG001 EH006 EJ027 EJ067 GS02 5D029 KA07 KC17

Claims (6)

[Claims] The content of the substance represented by the formula (1) is 50
An optical polycarbonate resin molding material comprising a polycarbonate resin having a content of the substance represented by the formula (2) of not more than 50 ppm, which is not more than 50 ppm. Embedded image Wherein A is a hydrogen atom, an alkyl group, a phenylalkyl group or an aliphatic ester group, and r is an integer of 1 to 5. Embedded image Wherein A is a hydrogen atom, an alkyl group, a phenylalkyl group or an aliphatic ester group, and r is an integer of 1 to 5. 2. An optical polycarbonate molding material according to claim 1, wherein the polycarbonate resin has a viscosity average molecular weight of 10,000 to 22,000. 3. In the formula (1), A is an alkyl group having 1 to 9 carbon atoms or a phenylalkyl group in each alkyl group, and r is an integer of 1 to 5. Polycarbonate resin molding material. 4. The optical element according to claim 1, wherein in the formula (2), A is an alkyl group having 1 to 9 carbon atoms or a phenylalkyl group in each alkyl group, and r is an integer of 1 to 5. Polycarbonate resin molding material. 5. An optical disk substrate formed from the optical polycarbonate resin molding material according to claim 1. 6. A digital versatile resin formed from the optical polycarbonate resin molding material according to claim 1.
An optical disk substrate for a disk (DVD).