JP2000169571A - Optical polyfunctional resin molding material and optical disc base made from its material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a molding material for a disc which has extremely a low error rate and highly reliable by lowering not more than a specified number of minute foreign bodies having not less than specified values of the particle sizes and lowering not more than a specified number of big foreign bodies having not less than specified values of the particle sizes. SOLUTION: A molding material is a polycarbonate resin molding material wherein foreign materials having not less than 0.5 μm of the particle sizes are not more than 10,000 particles and the foreign materials having not less than 20 μm of the particle sizes are not more than 200 particles/g and the viscosity average molecular weight is 10,000-22,000. An optical disc made from this molding material has not more than 1×10-3 of an error rate after an accelerating deterioration test (80 deg.C×85% RH×500 hr) and not more than 10% of occurrence of being out of tracking control of regeneration laser spot. This polycarbonate is obtained by polymerization of a dihydric phenol such as bisphenol A and a carbonate precursor such as phosgene in a solvent such as methylene chloride in the presence of an acid binder such as sodium hydrate, an amino compound catalyst and an end group terminator such as a single functional phenol according to a solution method.

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 having reduced foreign matter and an optical disk substrate, and more particularly to an optical polycarbonate resin molding material having an extremely reduced amount of foreign matter having a size of 20 μm or more, and an optical polycarbonate substrate. The present invention relates to an optical disk substrate.

[0002]

2. Description of the Related Art Polycarbonate resins are excellent in heat resistance and low water absorption, and particularly excellent in transparency.
In particular, it is used as a substrate material for optical disks such as compact disks and magneto-optical disks. Optical discs use micron-sized irregularities formed on the substrate to record and reproduce information using laser light. Therefore, foreign substances (dust, carbide, etc.) on the substrate reduce the reliability of information recording and reproduction. Has a very large effect. Therefore, it is required that the amount of foreign matter is small in the polycarbonate resin constituting the substrate.

[0003] For this reason, conventionally, foreign substances in the raw materials have been reduced by filtering them with a filter in a purification step, a granulation step, or the like.
5, JP-A-63-91231, JP-B-7-1096
A technique as described in No. 55 or the like has been proposed.

Among them, Japanese Patent Application Laid-Open No. 61-90345 discloses that
The amount of foreign matter having a particle size of 0.5 μm or more contained in the optical disk substrate is set to 1 × 10 ⁵ particles / g or less. In order to satisfy this condition, foreign matter in a raw material such as a monomer is distilled and / or Alternatively, it is disclosed that it is necessary to remove by filtration and to prevent foreign matter from being mixed in the cleaning of the manufacturing equipment and the manufacturing process.

Japanese Unexamined Patent Publication (Kokai) No. 63-91231 discloses that in order to obtain a highly reliable optical disk substrate, the amount of foreign substances having a particle size of 1 μm or more needs to be 10,000 particles / g or less. And a technique for forming an optical disc substrate with a resin composition from which foreign particles have been removed by filtering a solution dissolved by an organic solvent in order to satisfy this condition, or by passing through a sintered metal filter in a molten state. Is disclosed.

Further, Japanese Patent Publication No. Hei 7-109655 discloses a concept of foreign matter strength in order to obtain sufficient reliability for recording and reproducing information on an optical disk substrate. 10,000μ of foreign matter of size
It is disclosed that it is necessary to reduce it to m ² / g or less.

[0007]

The prior art described above focuses on the amount of minute foreign matter having a size of 0.5 μm or 1 μm, and does not specifically describe the amount of a large foreign matter of 20 μm or more. There are no regulations. At present, sufficient reproduction reliability can be obtained only by reducing minute foreign substances in a substrate material for a compact disk which is widely used, but a digital versatile disk (DVD-R
OM, DVD-video, DVD-R, DVD-RA
M) are not always satisfactory.

The present invention has been made in view of the above problems, and as a result of intensive studies on the problems, it has been found that, while minimizing foreign matter as in the past, the amount of foreign matter having a size of 20 μm or more can be reduced by 200 μm. It has been found that by setting the number of pieces / kg or less, an extremely low error rate and a surprisingly reliable high-density optical disc can be obtained.

[0009]

According to the present invention, a particle size is 0.5 μm.
The above foreign substances are 10,000 particles / g or less and the particle size is 20 μm.
A polycarbonate resin, wherein the number of foreign substances having a particle size of m or more is 200 particles / kg or less, is used as a molding material for a high-density optical disk substrate.

[0010] In the present specification, "foreign matter" refers to a contaminant mixed in through various routes in all processes from production of an aromatic polycarbonate resin from a raw material to molding of an optical disk substrate. All components insoluble in methylene chloride, such as impurities and dust contained in monomers, solvents, etc.), dust adhering to production equipment or carbides generated during the molding process.

According to the present invention, in order to obtain sufficient reliability as a disk substrate used for a high-density optical disk such as a digital versatile disk, a molding material (aromatic polycarbonate resin) provided for molding the substrate is required. Regarding the amount of foreign matter contained, it is necessary that the number of foreign matter having a particle size of 0.5 μm or more is 10,000 or less and the number of foreign matter having a particle size of 20 μm or more is 200 or less. Even when the number of foreign particles having a particle size of 0.5 μm or more is 10,000 or less, the foreign particles surely cause an error in a high-density optical disk substrate formed of a material having a particle size of 20 μm or more exceeding 200 particles / kg. , Sufficient reliability cannot be obtained. Similarly, foreign particles having a particle size of 20 μm or more are 200 particles / kg.
Even if the particle size is less than or equal to
In a high-density optical disk substrate molded from a material exceeding 0 / g, foreign matter surely causes an error, and sufficient reliability cannot be obtained. In order to obtain a more reliable substrate, it is preferable that the number of foreign substances having a particle size of 0.5 μm or more be set to 10,000 or less and the number of foreign substances having a particle size of 20 μm or more be set to 100 or less. Furthermore, if the number of foreign particles having a particle size of 20 μm or more is set to 20 particles / kg or less, reliable reliability substantially equivalent to the case where there is no foreign matter can be obtained. Also,
In order to obtain a more reliable substrate, it is preferable that the number of foreign particles having a particle size of 20 μm or more be 200 particles / kg or less and the number of foreign particles having a particle size of 0.5 μm or more be 6000 particles / g or less. 2000 foreign particles / g with a particle size of 0.5 μm or more
In the following case, it is possible to obtain reliable reliability substantially equivalent to the case where nothing is provided.

As described above, the number of foreign substances has an influence on the reliability of the substrate, but the influence of the number of foreign substances having a particle size of 0.5 μm or more is controlled by controlling the temperature of the disk at 80 ° C. and the relative humidity of 85%. It is confirmed by checking the error rate after holding in the tank for 500 hours. The error rate of the disk obtained from the aromatic polycarbonate resin molding material is preferably 1 × 10 ⁻³ or less, and is 7 × 10 ⁻³ or less.
^-4 or less, more preferably 3 × 10 ^-4 or less. On the other hand, the influence of the number of foreign particles having a particle size of 20 μm or more is confirmed by reproducing 100 disks by a player and examining the occurrence rate of a phenomenon in which tracking control of a reproduced laser spot is lost due to the foreign materials during reproduction. The occurrence rate of the disk obtained from the aromatic polycarbonate resin molding material is preferably 10% or less, more preferably 5% or less, and even more preferably 1% or less.

The polycarbonate resin used in the present invention is usually obtained by reacting a dihydric phenol with a carbonate precursor by a solution 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-diisopropylbenzene,
3-bis (4-hydroxyphenyl) -5,7-dimethyladamantane, 4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxydiphenylsulfoxide, 4,4′-dihydroxydiphenylsulfide,
Examples thereof include 4′-dihydroxydiphenyl ketone, 4,4′-dihydroxydiphenyl ether, and 4,4′-dihydroxydiphenyl ester, 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 or haloformate is used, and specific examples include phosgene, diphenyl carbonate, dihaloformate of dihydric phenol and the like.

In producing the polycarbonate resin by reacting the dihydric phenol with the carbonate precursor by a solution method or a melting method, a catalyst, a terminal stopper, an antioxidant for the dihydric phenol and the like may be used, if necessary. May be used. 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 solution 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.

In such a polymerization reaction, a terminal stopper is usually used. Monofunctional phenols can be used as such a terminal stopper. Monofunctional phenols are commonly used as molecular terminators for molecular weight control, and the resulting polycarbonate resins are capped by groups based on monofunctional phenols, so that Excellent heat stability. Such a monofunctional phenol is generally a phenol or a lower alkyl-substituted phenol, and may be a monofunctional phenol represented by the following general formula.

[0019]

Embedded image [Wherein A is a hydrogen atom, a linear or branched alkyl group having 1 to 9 carbon atoms or a phenyl-substituted alkyl group, and r is an integer of 1 to 5, preferably 1 to 3].

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

Other monofunctional phenols include:
Phenols or benzoic acid chlorides having a long-chain alkyl group or an aliphatic polyester group as a substituent, or long-chain alkyl carboxylic acid chlorides can be used. When blocked, these not only function as a terminal terminator or a molecular weight regulator, but also improve the melt flowability of the resin, not only facilitate the molding process, but also reduce the physical properties as a substrate, especially the water absorption of the resin. And the effect of reducing the birefringence of the substrate is preferably used. Among them, the following general formula [Ia]
And phenols having a long-chain alkyl group represented by [Ib] as a substituent are preferably used.

[0022]

Embedded image

[0023]

Embedded image [Wherein, X represents -R-O-, -R-CO-O- or -R
—O—CO—, wherein R is a single bond or 1 carbon atom
Represents a divalent aliphatic hydrocarbon group of 10 to 10, preferably 1 to 5, and n represents an integer of 10 to 50. ]

The substituted phenols of [Ia] preferably have n of 10 to 30, especially 10 to 26, and specific examples thereof include decylphenol, dodecylphenol, tetradecylphenol, hexadecylphenol, and the like. Octadecylphenol, eicosylphenol, docosylphenol, triacontylphenol and the like can be mentioned.

As the substituted phenols of [Ib], 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 26. Suitable examples thereof include, for example, decyl hydroxybenzoate, dodecyl hydroxybenzoate, tetradecyl hydroxybenzoate, hexadecyl hydroxybenzoate, eicosyl hydroxybenzoate, docosyl hydroxybenzoate and tricontyl hydroxybenzoate. Can be These terminal stoppers are desirably introduced at least at 5 mol%, preferably at least 10 mol%, based on all terminals of the obtained polycarbonate resin. You may mix and use more than one kind.

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 off the produced alcohol or phenol. The reaction temperature varies depending on the boiling point of the produced alcohol or phenol, but is usually in the range of 120 to 350 ° C.
In the latter half of the reaction, the pressure of the system is reduced to about 10 to 0.1 Torr to facilitate the distillation of the alcohol or phenol produced. The reaction time is usually 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 such a 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 , 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, manga 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 these polymerization catalysts to be used is preferably 1 × 10 ⁻⁸ to 1 × 1 with ^respect to 1 mol of the dihydric phenol used as the raw material.
It is selected in the range of 0 ^-3 equivalents, more preferably 1 × 10 ^{-7 to} 5 × 10 ^-4 equivalents.

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 intrinsic viscosity) [η] = 1.23 × 10 ^-4 M ^0.83 c = 0.7

The raw material polycarbonate resin is produced by a conventionally known method (solution polymerization method, melt polymerization method, etc.) and then filtered in a solution state, or the granulated raw material after granulation (desolvation) is heated, for example. It is preferable to remove impurities and foreign substances such as low molecular weight components and unreacted components by washing with a poor solvent such as acetone under the conditions. 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 an additive such as a phosphorus-based antioxidant. 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.

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.

[0032]

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.

(A) Error rate after wet heat treatment In order to reproduce the increase in error rate when left in a severe atmosphere for a long time, the disk was heated to a temperature of 80 ° C. and a relative humidity of 85%.
Was maintained in a thermo-hygrostat controlled for 500 hours, and then the error rate was measured. This measurement is performed to investigate the effect of the number of foreign particles having a particle size of 0.5 μm or more on the reliability of the disk. .

(B) Off-Tracking Occurrence Rate 100 discs were reproduced by a player, and it was confirmed whether or not a foreign substance caused the tracking control of the reproduced laser spot to be lost during reproduction. This measurement was conducted with a particle size of 20.
The purpose is to investigate the influence of the number of foreign particles having a size of μm or more on the reliability of the disk.

Example 1 In a reactor equipped with a thermometer, a stirrer and a reflux condenser, 219.4 parts of ion-exchanged water and 40.2% of a 48% aqueous sodium hydroxide solution were added.
After dissolving 57.5 parts (0.252 mol) of 2,2-bis (4-hydroxyphenyl) propane and 0.12 parts of hydrosulfite, 181 parts of methylene chloride was added thereto, and the mixture was stirred. Phosgene 2 at 15-25 ° C
8.3 parts were blown in for 40 minutes. After completion of the phosgene blowing, 7.2 parts of a 48% aqueous sodium hydroxide solution and p
2.42 parts of -tert-butylphenol was added, stirring was started, 0.06 parts of triethylamine was added after emulsification, and the mixture was further stirred at 28 to 33 ° C for 1 hour to complete the reaction. After the completion of the reaction, the product was diluted with methylene chloride, washed with water, acidified with hydrochloric acid, and washed with water.When the conductivity of the aqueous phase became almost the same as that of ion-exchanged water, an isolation chamber having a foreign substance take-out port in the bearing was formed. The methylene chloride was evaporated by the provided kneader to obtain a powder having a viscosity average molecular weight of 15,000. To this powder was added 0.01% by weight of tris (2,4-di-tert-butylphenyl) phosphite and 0.08% by weight of monoglyceride stearate. Next, the powder was used as a vent-type twin screw extruder [KTX manufactured by Kobe Steel Ltd.]
-46] and melt-kneaded while degassing at a cylinder temperature of 240 ° C to obtain pellets. The pellets are added to 0.0
The sample was dissolved in methylene chloride filtered through a 5 μm filter, and this sample was passed through a liquid fine particle counter by a light scattering / light blocking method using laser light, and the number of foreign substances contained in the pellet was measured. As a result, 0.5 μ
The number of foreign particles having a particle size of m or more was 0.99 × 10 ⁴ particles / g, and the number of foreign particles having a particle size of 20 μm or more was 190 particles / kg.

On the other hand, a mold exclusively for DVD was mounted on the injection molding machine, and a nickel stamper for DVD containing information such as address signals was mounted on this mold. Then, the pellets are put into a hopper of a molding machine by automatic conveyance, and a cylinder temperature of 380 ° C., a mold temperature of 115 ° C., and an injection speed of 30 ° C.
An optical disk substrate having a diameter of 120 mm and a thickness of 0.6 mm was obtained under the conditions of 0 mm / sec and a holding pressure of 40 kgf / cm ² . Thereafter, an aluminum film is sputtered on the substrate,
An optical disk was obtained by bonding the sheets. This optical disk is set on a deck (DDU-1000 manufactured by Pulstec) and PI
An error was measured. Table 1 shows the results.

Example 2 The number of foreign substances having a size of 0.5 μm or more was 0.9 as raw material pellets.
An optical disk substrate was molded and evaluated in the same manner as in Example 1 except that a polycarbonate resin having a density of 8 × 10 ⁴ particles / g and a number of foreign substances having a size of 20 μm or more was 80 particles / kg was used. Table 1 shows the results.

Example 3 The procedure of Example 1 was repeated except that 2.42 parts of p-tert-butylphenol was replaced by 2.72 parts, and the viscosity average molecular weight was 1400.
0 powder was obtained. The same additives as in Example 1 were added to this powder, and then pellets were obtained as in Example 1. The pellets thus obtained had a number of foreign substances of 0.5 μm or more of 0.99 × 10 ⁴ / g and a number of foreign substances of 20 μm or more of 70 / kg. Thereafter, an optical disk substrate was formed in the same manner as in Example 1, and this was evaluated.
Table 1 shows the results.

Example 4 As a raw material pellet, the number of foreign substances having a size of 0.5 μm or more was 0.9.
An optical disk substrate was molded in the same manner as in Example 1 except that a polycarbonate resin having a density of 8 × 10 ⁴ particles / g and 0 particles / kg of 20 μm or more was used and evaluated. Table 1 shows the results.

Example 5 The number of foreign particles having a size of 0.5 μm or more was 0.5 as raw material pellets.
An optical disk substrate was molded in the same manner as in Example 1 except that a polycarbonate resin having a density of 1 × 10 ⁴ particles / g and a number of foreign substances having a size of 20 μm or more of 180 particles / kg was used.
This was evaluated. Table 1 shows the results.

Example 6 The number of foreign particles having a size of 0.5 μm or more was 0.1 as a raw material pellet.
An optical disk substrate was molded in the same manner as in Example 1 except that a polycarbonate resin having a density of 8 × 10 ⁴ particles / g and 180 μg / kg of foreign substances of 20 μm or more was used.
This was evaluated. Table 1 shows the results.

Example 7 The number of foreign particles having a particle size of 0.5 μm or more was 0.3 as raw material pellets.
An optical disk substrate was molded in the same manner as in Example 1 except that a polycarbonate resin having a density of 8 × 10 ⁴ particles / g and a number of foreign substances having a size of 20 μm or more of 50 particles / kg was used and evaluated. Table 1 shows the results.

Example 8 A reactor equipped with a stirrer and a distillation column was charged with 2,2-bis (4-
228 parts (about 1 mol) of (hydroxyphenyl) propane,
220 parts (about 1.03 mol) of diphenyl carbonate (manufactured by Bayer) and sodium hydroxide 0.00 as a catalyst.
0024 parts (about 6 × 10 ^-7 mol / bisphenol A 1 mol) and tetramethylammonium hydroxide 0.00
73 parts (about 8 × 10 ^-5 mol / bisphenol A 1 mol)
And the atmosphere was replaced with nitrogen. This mixture was heated to 200 ° C. and dissolved with stirring. Then, the degree of decompression is set to 30
Most of the phenol was distilled off in 1 hour while heating as Torr, and the temperature was further raised to 270 ° C.
After conducting the polymerization reaction for 2 hours as orr,

[0044]

Embedded image

2.3 parts of a terminal terminator represented by the formula (1) were added. Thereafter, a terminal blocking reaction was performed at 270 ° C. and 1 Torr or less for 5 minutes. Next, in the molten state, 0.0023 parts of tetrabutylphosphonium dodecylbenzenesulfonate is added as a catalyst neutralizing agent, and the mixture is added at 270 ° C. and 10 Torr.
r, and the reaction was continued for 10 minutes at a viscosity average molecular weight of 150 or less.
00 polymer was obtained. The polymer was sent to the extruder by a gear pump. During the extruder, 0.01% by weight of tris (2,4-di-tert-butylphenyl) phosphite and 0.08% by weight of monoglyceride stearate were added to obtain polycarbonate pellets.

The pellet is dissolved in methylene chloride which has been previously filtered through a 0.05 μm filter, and this sample is passed through a liquid fine particle counter using a light scattering / light blocking system using laser light, and is contained in the pellet. The number of foreign substances was measured. As a result, the number of foreign substances of 0.5 μm or more was 0.97 × 10 ⁴ / g, and the number of foreign substances of 20 μm or more was 200 / kg. Hereinafter, an optical disk substrate was formed in the same manner as in Example 1, and this was evaluated. Table 1 shows the results.

Comparative Example 1 The number of foreign substances having a size of 0.5 μm or more was 0.9 as raw material pellets.
An optical disk substrate was molded in the same manner as in Example 1 except that a polycarbonate resin having a density of 3 × 10 ⁴ particles / g and a number of foreign substances having a size of 20 μm or more of 270 particles / kg was used.
This was evaluated. Table 1 shows the results.

Comparative Example 2 The number of foreign particles having a size of 0.5 μm or more was 1.5 as raw material pellets.
An optical disk substrate was molded in the same manner as in Example 1 except that a polycarbonate resin having a density of 1 × 10 ⁴ particles / g and a number of foreign substances having a size of 20 μm or more of 180 particles / kg was used.
This was evaluated. Table 1 shows the results.

[0049]

[Table 1]

From these results, in order to obtain a highly reliable high-density optical disk substrate, it is not possible to obtain only a small amount of fine particles having a size of 0.5 μm in the aromatic polycarbonate resin molding material used for molding the substrate. It is clear that a large foreign matter of 20 μm or more, which is sufficient and is not so much a problem in a conventional compact disk or the like, must be reduced to a minimum.

[0051]

As described above, according to the molding material of the present invention, not only the number of foreign substances having a particle size of 0.5 μm or more in the material is as small as 10000 / g or less but also 20 μm or less.
Since foreign matter having a size of m or more is reduced to an extremely small value of 200 particles / kg or less, an optical disk substrate with few errors and extremely high reliability can be obtained. In particular, a high density optical disk such as a digital versatile disk (DVD) can be obtained. The effect it has on the offer is extraordinary.

Continued on the front page F term (reference) 4J029 AA09 AB07 AC01 AC02 AD01 AD10 AE05 BB04A BB05A BB10A BB12A BB12B BB12C BB13A BB13B BB16A BD09A BE04 BF14A BH02 DB07 DB11 DB13 HA01 HC01 J02J041J031 JF131 JF141 JF161 JF181 JF221 JF271 JF321 JF331 JF361 JF371 JF381 JF471 JF541 KB05 KD01 KE02 KE05 KE09 KH05 5D029 KA07 KC20

Claims (5)

[Claims] 1. The method according to claim 1, wherein foreign substances having a particle size of 0.5 μm or more
An optical polycarbonate resin molding material characterized in that the number of foreign substances having a particle size of 20 μm or less and a particle size of 20 μm or more is 200 particles / kg or less. 2. A viscosity average molecular weight of 10,000 to 2,200.
2. The optical polycarbonate resin molding material according to claim 1, wherein the value is 0. 3. An optical disk substrate made of the optical polycarbonate resin molding material according to claim 1. 4. An optical disk substrate for a digital versatile disk, comprising the optical polycarbonate resin molding material according to claim 1. 5. The polycarbonate for optical use according to claim 1,
Made of resin molding material, accelerated deterioration test (80 ° C x 85%
Error rate after RH x 500 hours) is 1 x 10 ^-3Below
Light with an out-of-tracking occurrence rate of 10% or less
disk.