JP2003261668A - Polycarbonate resin for optical use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk substrate composed of a polycarbonate resin which has excellent resistance to hot and wet condition and which can maintain high reliability over a long term, and also to provide a molding material for the disk. <P>SOLUTION: The optical polycarbonate resin is synthesized from an aromatic bisphenol and phosgene. The resin is characterized in that chlorine being present as a chloroformate group at a molecular chain terminal is 0.1 ppm or less, remaining free chlorine is 0.1 ppm or less, and the whole amount of chlorine is 40 ppm or less. The optical disk substrate constructed from the resin is also provided. <P>COPYRIGHT: (C)2003,JPO

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 particularly to reduce the amount of chlorine present as a chloroformate group at the end of a molecular chain. Was
The present invention relates to an optical polycarbonate resin molding material, an optical disk substrate made of the material, and an optical information recording medium.

[0002]

2. Description of the Related Art Optical discs for recording / reproducing information by irradiating laser light include digital audio discs (so-called compact discs), optical video discs (so-called laser discs), various write-once discs, magneto-optical discs, and phase discs. Changeable disks have been put to practical use. Among these applications, particularly when it is used as an information recording substrate, a thin film of a metal or a metal compound or a layer containing a dye is provided as a recording layer on a transparent substrate.

Recently, studies have been actively conducted for using such an optical disk for recording a digital video image, and a digital versatile disk (DVD) has been developed as such an optical disk.

Although this DVD has the same 120 mm diameter as a CD, it records video information corresponding to one movie,
It was designed so that it could be played back with the same image quality as the current TV. Here, in order to record such video information on an optical disc, a recording capacity of, for example, 6 to 8 times that of a CD is required. In such a case, the trace components that affect the chemical properties of the material resin are important factors in the reliability of the optical disc.

For such an optical disc substrate, a polycarbonate resin which is excellent in moldability, strength, light transmittance and resistance to moist heat is mainly used. Conventionally, general polycarbonate resins contain a small amount of chlorinated compounds such as methylene chloride used as a solvent and a compound having a chloroformate group which is an unreacted residue. When molding at a high temperature of ℃ or higher, it decomposes to produce an acidic substance, which causes mold corrosion, or when a thin film having a thin film or pigment such as metal and metal compounds, or other thin film is attached. , Which may cause film corrosion or deterioration of pigments.

Therefore, in order to improve the above-mentioned drawbacks, for example, a method of reducing free chlorine in a resin by enhancing washing and liquid separation in a polymer washing step (Japanese Patent Laid-Open No. 64-2).
No. 4829) or a method of reducing the content of halogenated hydrocarbons such as methylene chloride used as a polymerization solvent by treating the polymer after polymerization with a hydrocarbon such as n-heptane (JP-A-64-31690). No. gazette) is proposed. Polycarbonate resin from which chlorine compounds are removed as much as possible by such a method does not produce an acidic substance in high temperature molding, but when left at high temperature and high humidity for a long period of time, minute white spots occur on the substrate. Alternatively, the resin itself is colored and the hue is deteriorated, resulting in a drawback that long-term reliability is impaired.

Various improvement methods have been proposed for this long-term reliability. For example, regarding the molecular chain end in the polycarbonate resin pellet of the material, chlorine existing as a chloroformate group is 2.0 ppm or less, free chlorine remaining on the molded substrate is 0.2 ppm or less, and halogenated hydrocarbon is 10 ppm or less. By doing so, the error rate due to film corrosion can be suppressed (Japanese Patent Application Laid-Open No. HEI 3-
116559).

However, there is no regulation regarding the amount of free chlorine and halogenated hydrocarbon content of the polycarbonate resin pellets as a material, nor is there any regulation regarding the total chlorine content. In addition, the free chlorine in the polycarbonate resin is 1 ppm or less, and the content of methylene chloride is 1
It is 0 ppm or less, and the content of carbon tetrachloride is 0.2 pp
m or less, the amount of chlorine bonded to the resin skeleton is 10 ppm or less as chlorine, and the content of hydrocarbon is 1 p
It is shown that the reliability of the substrate is also improved by setting the thickness to pm or less (JP-A-4-146922). However, with the spread of optical discs in recent years, demands for improving substrate productivity are increasing. Various chlorine compounds contained as impurities in polycarbonate resin are volatilized during molding, and their components adhere and accumulate during molding for a long period of time, and corrode molds and stampers, resulting in optical and mechanical properties. Since it leads to deterioration of substrate characteristics, it is necessary to wash the mold and stamper, and continuous molding must be temporarily stopped.

Further, chlorine bound in the resin skeleton such as a chloroformate group decomposes to generate free chlorine, which also causes corrosion, which leads to a decrease in productivity. As described above, the conventional resins have been insufficient for improving productivity. In addition, a metal-based recording material is often used as the information recording layer of the optical information recording medium, and the presence of chlorine adversely affects the metal, and particularly in a high-density optical information recording medium such as a DVD. Is not always satisfactory in terms of long-term reliability of the information recording layer.

[0010]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above conventional circumstances, and an object of the present invention is to improve the chemical properties of a polycarbonate resin, which is a material, and to provide a polycarbonate resin injection molded article. It is an object of the present invention to provide an optical information recording medium having excellent long-term reliability in an optical information recording medium as a substrate with high productivity.

As a result of intensive studies aimed at achieving the above object, the present inventor has reduced the contents of chloroformate groups and free chlorine in a polycarbonate resin and, at the same time, makes the total chlorine amount not more than a specific amount. The inventors have found that it is possible to obtain an optical disk capable of controlling deterioration of a substrate made of a polycarbonate resin extremely effectively and maintaining high reliability for a long period of time. In addition, reducing these chloroformate groups and free chlorine, and at the same time reducing the total amount of chlorine, also leads to a reduction in the generation and volatilization of halogenated hydrocarbons, and is an optical polycarbonate resin molding material with improved substrate productivity. It was also found that an optical disk substrate can be obtained.

[0012]

According to the present invention, the residual chlorine present as a chloroformate group at the terminal of the molecular chain is 0.1 ppm or less and the free chlorine is 0.1 p or less.
Provided is a polycarbonate resin having a total chlorine content of 40 ppm or less and a total chlorine content of 40 ppm or less.

In the present invention, CD-R, CD-RW,
MO, digital video disc, DVD-ROM, DV
In order to improve the long-term reliability and productivity of a substrate of an optical disc of a digital versatile disc (DVD) typified by D-audio, DVD-R, DVD-RAM, etc., the substrate is molded. 0.1 p of chlorine present as a chloroformate group at the end of the molecular chain contained in the polycarbonate resin, which is the molding material used for
It is necessary that pm or less, free chlorine be 0.1 ppm or less, and total chlorine amount be 40 ppm or less. In addition, preferably, chlorine present as a chloroformate group at the terminal of the molecular chain is 0.05 ppm or less, free chlorine is 0.06 ppm or less, and total chlorine amount is 20 ppm or less, so that a more reliable effect can be obtained.

The polycarbonate resin used in the present invention is usually obtained by reacting a dihydric phenol with phosgene by an interfacial polymerization method. Typical examples of the dihydric phenol used here include hydroquinone, resorcinol, 4,4′-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane and 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 called 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, 1,3-bis (4-hydroxyphenyl) -5,7-dimethyladamantane,
4,4'-dihydroxydiphenyl sulfone, 4,4'-
Examples thereof include dihydroxydiphenyl sulfoxide, 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxydiphenyl ketone, 4,4′-dihydroxydiphenyl ether and 4,4′-dihydroxydiphenyl ester. These may be used alone or in combination of two or more.

Among them, 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)
A homopolymer or copolymer obtained from at least one bisphenol selected from the group consisting of -m-diisopropylbenzene is preferable, and bisphenol A is particularly preferable.
Homopolymer of 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.

When a polycarbonate resin is produced by reacting the above dihydric phenol with phosgene by an interfacial polymerization method, a catalyst, an antioxidant for the dihydric phenol, etc. may be used, if necessary. 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 difunctional carboxylic acid, It may also be a mixture of two or more of the obtained polycarbonate resins.

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

In the polymerization reaction of the polycarbonate resin by the interfacial polymerization method, monofunctional phenols are used as a terminal stopper. Monofunctional phenols are used as molecular terminators for molecular weight control, and the resulting polycarbonate resin is thermostable as compared to those that do not because the ends are blocked by groups based on monofunctional phenols. Is excellent.

Such monofunctional phenols are generally phenols or lower alkyl-substituted phenols, and the monofunctional phenols represented by the following general formula (1) can be shown.

[0020]

[Chemical 1]

[In the formula, A is a hydrogen atom or 1 to 1 carbon atoms.
9, preferably 1-8 aliphatic hydrocarbon groups, and r is an integer of 1-5, preferably 1-3].

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

As other monofunctional phenols,
Phenols or benzoic acid chlorides having a long-chain alkyl group or an aliphatic ester group as a substituent,
Alternatively, long-chain alkylcarboxylic acid chlorides can be used, and when these are used to block the ends of the polycarbonate copolymer, they not only function as a terminal stopper or a molecular weight modifier, but also melt flow of the resin. The properties are improved, the molding process is facilitated, and the physical properties as a substrate, particularly the effect of lowering the water absorption of the resin, and the effect of reducing the birefringence of the substrate are also preferably used. Among them, phenols having a long chain alkyl group represented by the following general formulas (2) and (3) as a substituent are preferably used.

[0024]

[Chemical 2]

[0025]

[Chemical 3]

[In the formula, X is -R-O-, -R-CO-O.
-Or-RO-CO-, wherein R represents a single bond or a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 5, and n represents an integer of 10 to 50. Show. ]

As the substituted phenols of the formula (2), those in which n is 10 to 30, particularly 10 to 26 are preferable,
Specific examples thereof include decylphenol, dodecylphenol, tetradecylphenol, hexadecylphenol, octadecylphenol, eicosylphenol, docosylphenol and triacontylphenol.

Suitable substituted phenols of the formula (3) are compounds in which X is —R—CO—O— and R is a single bond, and n is 10 to 30, particularly 10 to 26. Preferred are decyl hydroxybenzoate, dodecyl hydroxybenzoate, tetradecyl hydroxybenzoate, hexadecyl hydroxybenzoate, eicosyl hydroxybenzoate, docosyl hydroxybenzoate and triaconyl hydroxybenzoate. .

It is desirable that these terminal terminators are introduced into at least 5 mol%, preferably at least 10 mol% of the terminals of the obtained polycarbonate resin, and the terminator may be used alone or You may mix and use 2 or more types.

The viscosity average molecular weight (M) of the polycarbonate resin is preferably 10,000 to 22,000, more preferably 12,000 to 20,000, and 1
Especially preferred is 3,000 to 18,000. A polycarbonate resin having such a viscosity average molecular weight is preferable because sufficient strength can be obtained as an optical material, melt flowability at the time of molding is also good, and molding distortion does not occur. The viscosity average molecular weight in the present invention is obtained by inserting the specific viscosity (η _sp ) obtained from a solution of 0.7 g of polycarbonate resin dissolved in 100 mL of methylene chloride at 20 ° C. into the following equation.

Η _sp /c=[η]+0.45×[η] ² c
(However, [η] is the intrinsic viscosity) [η] = 1.23 × 10 ⁻⁴ M ^0.83 c = 0.7

As a method of reducing the chlorine content in the polycarbonate resin, for example, after the monofunctional phenols are added, a catalyst is added to carry out a sufficient reaction, or after the production by a conventionally known interfacial polymerization method, Alkaline extraction in solution, or granulation (desolvation) of the granular raw material, for example, ketones such as acetone, aliphatic hydrocarbons such as hexane, aromatic hydrocarbons such as xylene, polycarbonate poor solvent and non-solvent It is preferable to remove it by washing with. It is desirable to carry out these methods and means by appropriately combining and repeating until the chlorine content is reduced to a target value. As an example, in the acetone extraction, a method of using a larger amount than the conventional amount of the polycarbonate resin, for example, using about 5 times by weight or more, raising the extraction temperature, stirring at the time of extraction Examples include more powerful methods.

Further, if the washed and purified polycarbonate resin solution and the washing solution are separated by centrifugation and filtration, free chlorine remaining in the pellet can be reduced. Further, in the extrusion step (pelletizing step) of obtaining a pelletized polycarbonate resin for injection molding, it is preferable to remove foreign matters by passing through a sintered metal filter having a filtration accuracy of 10 μm in the molten state. If necessary, it is also preferable to add a release agent such as a polyhydric alcohol fatty acid ester, and an additive such as a phosphorus-based antioxidant. In addition to the above method, the chlorine content can also be reduced by injecting a small amount of water into the molten polycarbonate resin in the pelletizing step and removing the water from the vacuum ventro. In any case, it is necessary that the content of foreign materials, impurities, solvents, etc. in the raw material resin before injection molding be as low as possible.

In the present invention, the amount of chlorine remaining as a chloroformate group at the end of the molecular chain in the polycarbonate resin is adjusted to 0.1 ppm or less by the above-mentioned method, and at the same time,
The amount of free chlorine remaining in the pre-resin is set to 0.1 ppm or less, and the total amount of chlorine remaining in the pellet is set to 40 ppm or less. This is because chlorine remaining in the resin, especially the above-mentioned chloroformate group, is decomposed into free chlorine during molding and during storage of the substrate, and as described above, deterioration of the resin, mold corrosion, and recording film formation. This is because it promotes corrosion and deterioration.

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

The optical polycarbonate resin molding material according to the present invention is obtained by subjecting an optical disk substrate, which is an injection-molded product of the polycarbonate resin molding material, to an optical disc substrate at 120 ° C. in water vapor.
Even if left for 1 hour, there is little deterioration in hue, and even if held for a long time under high temperature and high humidity conditions, minute white spots are extremely few. Specifically, ΔE indicating a change in hue is 0.13 or less, and a suitable value is 0.10 or less. Further, after the disk substrate was left in a constant temperature and humidity chamber controlled at a temperature of 80 ° C. and a relative humidity of 85% for 1000 hours, the number of white spots having a size of 20 μm or more was 2 or less per substrate having a diameter of 120 mm, which is preferable. No more than one. Therefore, CD-
R, CD-RW, MO, digital video disc, DV
D-ROM, DVD-audio, DVD-R, DVD
-It is excellent as a substrate of an optical disc of a digital versatile disc (DVD) typified by RAM and the like, particularly a substrate of a DVD. In terms of productivity, the incidence of defective substrates, which is caused by abnormal birefringence during long-time molding, is reduced. This is because the anomaly of birefringence is considered to be mainly caused by the occurrence of anomaly on the substrate surface due to corrosion of the die or stamper surface.

[0037]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto. The evaluation was according to the following method. (1) Viscosity average molecular weight 100 ml of methylene chloride and polycarbonate resin 0.7
The specific viscosity (η
It was calculated by inserting _SP ) 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 (2) Quantitative analysis sample of chloroformate group ( (Polycarbonate resin) was precisely weighed and dissolved in methylene chloride, and 4- (4-nitrobenzyl) pyridine was used as a color-developing group, and the amount was quantified by a spectrophotometer. A long cell having an optical path length of 10 cm was used as a cell for containing the solution.

(3) Quantitative analysis of free chlorine 1.0 to 1.7 g of a sample (polycarbonate resin) was precisely weighed and dissolved in 30 cm ³ of methylene chloride, and acetone was added thereto to immediately add a 0.0004 M silver nitrate / acetone solution. The free chlorine content was quantified by potentiometric titration with an automatic titrator to determine the free chlorine concentration in the sample. (4) Total chlorine content The total chlorine content is measured by chlorine analyzer [Mitsubishi Chemical Industries TSX-1
Quantification was performed using a 0 type machine].

(5) Long-term reliability test Disk molding machine [DISK 3M manufactured by Sumitomo Heavy Industries, Ltd.
III] optical disk substrate (diameter 120
(mm, thickness 0.6 mm) was left in an airtight container filled with water vapor (120 ° C.) for 11 hours, and then treated with a color difference meter [Nippon Denshoku Industries Co., Ltd. Z-1001DP] as an untreated substrate. The color difference was measured by the comparison and the ΔE was calculated from the following formula. ΔE = [(ΔL) ² + (Δa) ² + (Δb) ² ] ^1/2 ΔL, Δa, Δb: L of the untreated substrate and the substrate after the test,
Difference between a and b values Also, after similarly forming an optical disk substrate for 1000 hours in a constant temperature and humidity bath controlled at a temperature of 80 ° C. and a relative humidity of 85%, white spots having a size of 20 μm or more are generated in the substrate. I counted the number. This was performed for 25 optical disk substrates, the average value thereof was determined, and this was defined as the number of white dots.

(6) DVD productivity test injection molding machine, Sumitomo Heavy Industries DISK 3M III
Attach a die for DVD to this, attach a pitted nickel stamper for DVD to this die, put the molding material into the hopper of the molding machine by automatic conveyance, cylinder temperature 380 ℃, mold temperature 115 ° C, injection speed 300mm
/ Sec, holding pressure 40kgf / cm2, diameter 1
An optical disk substrate having a thickness of 20 mm and a thickness of 0.6 mm was continuously molded. After the continuous molding was started, the number of defective substrates produced increased due to an abnormality in birefringence, and the number of molded substrates until the number of defective substrates per 100 sheets exceeded 10% was determined. In addition, the standard for judging the non-defective product of the production substrate was that the birefringence was ± 100 nm or less in the double pass.

Example 1 219.4 parts of ion-exchanged water and a 48% aqueous sodium hydroxide solution were placed in a reactor equipped with a thermometer, a stirrer and a reflux condenser.
0.2 part was charged, and then 57.5 parts (0.252 mol) of 2,2-bis (4-hydroxyphenyl) propane and 0.12 part of hydrosulfite were dissolved therein, and then 181 parts of methylene chloride was added. Then, 28.3 parts of phosgene was blown in under stirring at 15 to 25 ° C. for 40 minutes. After the completion of blowing phosgene, 7.2 parts of a 48% sodium hydroxide aqueous solution and 2.48 parts of p-tert-butylphenol were added, stirring was started, and after emulsification, 0.06 part of triethylamine was added, and further at 28 to 33 ° C. for 1 hour. The reaction was completed by stirring. After completion of the reaction, the product was diluted with methylene chloride and washed with water, then acidified with hydrochloric acid and washed with water, and when the water phase conductivity became almost the same as that of ion-exchanged water, an isolation chamber with a foreign matter outlet in the bearing part was installed. Methylene chloride was evaporated with the provided kneader to obtain a powder having a viscosity average molecular weight of 14,800. 5 parts of acetone to 100 parts of this powder
00 parts was added, and the mixture was stirred at 50 ° C. for 1 hour for extraction treatment. The same extraction treatment was repeated twice in total, acetone was removed, and tris (2,4-di-t) was added to the dried powder.
0.01 wt% of ert-butylphenyl phosphite and 0.08 wt% of stearic acid monoglyceride were added. Next, while adding water to the powder with a vent type twin-screw extruder provided with a water injection hole, the cylinder temperature was adjusted to 2
Melt kneading was performed at 40 ° C. while being degassed to obtain pellets.

Example 2 In Example 1, one step of extraction treatment with acetone was performed.
The same process as in Example 1 was carried out except that the process was repeated to obtain pellets.

Comparative Example 1 Pellets were obtained in the same manner as in Example 1 except that the extraction treatment with acetone and the step of adding water during extrusion were omitted.

Comparative Example 2 Example 1 was repeated except that after the reaction was completed, chlorobenzene was used instead of diluting the product with methylene chloride after the reaction, and the extraction treatment with acetone and the step of adding water during extrusion were omitted. The same treatment as above was performed to obtain pellets. The obtained pellets were evaluated by the method described above. The results are shown in the table below.

[0045]

[Table 1]

[0046]

The molding material of the present invention is a polycarbonate resin containing 0.1 ppm or less of chlorine present as a chloroformate group at the end of the molecular chain, which is contained in the material, 0.1 p of residual free chlorine
The polycarbonate resin for optics, which has a total chlorine content of 40 ppm or less and has a pm or less, has excellent moisture and heat resistance and can produce a high-performance optical polycarbonate resin molding material and optical disk substrate that can maintain high reliability for a long period of time. It can be obtained by sex. CD-R, CD
-RW, MO, Digital Versatile Disc (D
In optical discs such as VD), especially in DVDs, the effect produced is exceptional.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F071 AA50 AF30 AH19 BA01 BB05                       BC01 BC03                 4J029 AA09 AB01 AD10 AE04 AE05                       BB03 BB04 BB05 BB09 BB10                       BB11 BB13 BC09 BD08 HA01                       HC01 JB19                 5D029 KA08 KC20

Claims (5)

[Claims] 1. A chlorine synthesized from an aromatic bisphenol and phosgene, which is present as a chloroformate group at the end of the molecular chain is 0.1 ppm or less, and residual free chlorine is 0.1 ppm or less. Chlorine content is 40pp
An optical polycarbonate resin characterized by being m or less. 2. The optical polycarbonate resin according to claim 1, wherein chlorine present as a chloroformate group at the terminal of the molecular chain is 0.05 ppm or less. 3. An optical disk substrate made of the injection-molded body of the polycarbonate resin according to claim 1. 4. An optical disk substrate for a digital versatile disk (DVD), which is made of the injection-molded body of the polycarbonate resin according to claim 1. 5. An optical information recording medium using the optical disk substrate according to claim 3.