JP2003128935A - Optical transparent thermoplastic resin molding material and optical disk substrate consisting of the same material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk substrate capable of being obtained in a high good quality rate and also having a high reliability, and an optical trans parent thermoplastic resin molding material. SOLUTION: This optical transparent thermoplastic resin molding material is characterized by having >=1 piece/40 g and <=50 pieces/40 g total number of foreign materials having >=15 μm particle diameter, and <=5% foreign materials having >=5 [W/(mK)] difference of heat conductances among them, and the optical transparent thermoplastic resin molding material is characterized by having >=1 piece/40 g and <=50 pieces/40 g total number of foreign materials having >=15 μm particle diameter, and <=55% copper or foreign materials containing copper among them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transparent thermoplastic resin molding material and an optical disk substrate with reduced foreign matter, and not only limits the total amount of foreign matter, but also takes into account its thermophysical properties, and The present invention relates to an optical transparent thermoplastic resin molding material in which the proportion of foreign matter having physical properties is limited, and an optical disk substrate made of the material.

[0002]

2. Description of the Related Art A transparent thermoplastic resin is an acrylic resin,
Styrene resins, polycarbonate resins, amorphous polyolefin resins, and the like exist, but these are used as materials for optical applications represented by optical disk substrates such as compact disks and magneto-optical disks. Optical discs use micron-sized irregularities formed on the substrate to record and reproduce information with laser light, so foreign matter (dust, carbides, etc.) in the substrate can reduce the reliability of information recording and reproduction. Have an extremely large impact. Therefore, it is required that the amount of foreign matter is small in the transparent thermoplastic resin forming the substrate. Among such a series of transparent thermoplastic resins, polycarbonate resins are widely used worldwide because they are excellent in heat resistance and low water absorption and particularly excellent in transparency. Taking a polycarbonate resin, which is particularly widely used as this optical disk substrate material, as an example, the transparent thermoplastic resin that constitutes the substrate is required to have a small amount of foreign matter, and therefore, conventionally, The foreign matter in the raw material is filtered with a filter in the refining process or the granulating process to reduce the foreign matter. For example, JP-A-61-90345 and 63.
-91231 gazette, Japanese Patent Publication No. 7-109655 gazette,
Techniques such as those described in Japanese Patent Laid-Open No. 2000-173101 have been proposed.

Of these, in Japanese Patent Laid-Open No. 61-90345, the amount of foreign matter having a particle size of 0.5 μm or more contained in an optical disk substrate is set to 1 × 10 ⁵ particles / g or less, and this condition is satisfied. It is disclosed that it is necessary to remove foreign substances in the raw materials used, such as monomers, by distillation and / or filtration in order to satisfy the conditions, and to prevent foreign substances from being mixed in the cleaning of the manufacturing equipment and the manufacturing process.

Further, in Japanese Patent Laid-Open No. 63-91231, a grain size of 1 is used to obtain a highly reliable optical disk substrate.
It is necessary to control the amount of foreign matter having a size of μm or more to 10,000 pieces / g or less, and in order to satisfy this condition, a solution dissolved with an organic solvent is filtered or when it is in a molten state. A technique of forming an optical disk substrate with a resin composition from which foreign particles are removed by passing through a sintered metal filter is disclosed.

In Japanese Patent Publication No. 7-109655, in order to obtain sufficient reliability in recording and reproducing information on an optical disk substrate, the concept of foreign matter strength is used, and particularly particle diameter of 1.1 μm or less. The amount of foreign matter of size 1
It is disclosed that it is necessary to reduce the amount to 2,000 μm ² / g or less.

[0006] Further, in Japanese Patent Laid-Open No. 2000-173101, in order to obtain an optical disc substrate having few errors and extremely high reliability, the number of foreign matters in each particle size category is taken into consideration, and A technique for an optical polycarbonate resin molding material with reduced foreign matter and an optical disk substrate made of the material is disclosed.

[0007]

The above-mentioned prior art is to examine in detail the relationship between the total amount of foreign matter or the amount of foreign matter for each detailed particle size classification and the information error of the final recording medium. It does not necessarily reflect the actual state of defect elimination in the actual disc manufacturing process. In the currently widely used substrate materials for compact discs, sufficient reduction in the total amount of fine foreign matters has been sufficient to achieve sufficient reproduction reliability. This is due to the idea that there will be less foreign matter). However, digital versatile discs (D
VD-ROM, DVD-video, DVD-R, DV
It has been found that in the case of a substrate material for a high-density optical disc represented by D-RAM etc., indiscriminate regulation of total foreign matter is not always satisfactory in terms of quality and economy. . In fact, manufacturers that manufacture optical disk substrates routinely inspect products with defect inspection machines to determine whether they are nondefective or defective.
The defect inspecting device is a device for shining light on a substrate and detecting a minute shadow in the transmitted or reflected light that is obtained to judge a good product or a defective product. As a matter of course, an optical disk substrate having a defect equal to or higher than the specific value determined by this inspection machine has a high error and is inferior in reliability, and is rejected as a defective product.

As described above, while there is an increasing demand for quality improvement of optical transparent thermoplastic resin molding materials typified by polycarbonate and optical disk substrates made of such materials, with the recent spread of optical disk substrates. Due to the increase in production volume, the demand for improved substrate productivity is also increasing. Since optical disk substrates are currently mass-produced, the economic merit for optical disk substrate producers is enormous even if the yield rate is improved by several percent.

As a result of intensive studies made by the present inventors, when foreign matter having a large difference in thermophysical properties from the resin is present in the resin for forming the substrate, the resin is cooled in the process of injection molding to obtain the substrate. It was found that the resin around the foreign matter causes a large optical distortion. The optical strain generated around the foreign matter having a large difference in thermophysical properties from these resins is detected as a defect by the defect inspection machine. That is, a foreign substance having a large difference in thermophysical properties from the resin is more likely to be detected including the optical distortion around the resin, and is inspected as a foreign substance defect larger than the actual size of the foreign substance. It is decided by the opportunity.
This has been a hindrance to obtaining an optical optical disk substrate with high yield and high reliability.

The present invention has been made in view of the above-mentioned problems, and as a result of extensive studies on the problems, as a result of various foreign substances existing in the resin, copper or copper-containing foreign substances are heat-treated with the resin. It was found that the optical strain is large, probably due to the large difference in the physical properties, and that the difference in the thermal conductivity is largely effective as the difference in the thermophysical properties. On the other hand, in the resin production process, the reduction of foreign matter generally involves an increase in manufacturing cost. The present inventors have also found that when aiming for a foreign matter content below a certain fixed amount, enormous cost increase is inevitable in the resin production process. Thus, the amount of foreign matter of a specific size in the resin is limited to within the allowable range from the viewpoint of both product quality and manufacturing cost, and the proportion of foreign matter whose thermal conductivity difference with the resin is a specific value or more By prescribing, especially by stipulating the proportion of copper or copper-containing foreign matter to be below a specific value, it is possible to suppress the occurrence of large optical distortions around the foreign matter, which is surprisingly high quality and highly reliable. The present invention has been achieved by finding that an optical disk substrate can be obtained.

[0011]

According to the present invention, a transparent thermoplastic resin for optics, particularly a high-density optical disc, a polycarbonate resin molding material, and an optical disc substrate made therefrom, according to the following (1) to (6): Will be provided. (1) The total number of foreign particles having a particle size of 15 μm or more is 1/4
55% or less of foreign substances having a thermal conductivity difference of 5 [W / (m · K)] or more from 0 g to 50/40 g and having a difference of 5 [W / (m · K)] or more from the resin. Thermoplastic molding material. (2) The total number of foreign particles with a particle size of 15 μm or more is 1/4
A transparent thermoplastic resin molding material for optics, which is 0 g or more and 50 pieces / 40 g or less, and 55% or less of copper or copper-containing foreign matters. (3) The optical transparent thermoplastic resin molding material according to the item (1) or (2), wherein the optical transparent thermoplastic resin is a polycarbonate resin. (4) The polycarbonate resin is 10,000 to 2
The optical transparent thermoplastic resin molding material according to the item (3), which has a viscosity average molecular weight of 2,000. (5) An optical disk substrate molded from the optical transparent thermoplastic resin molding material according to any one of items (1) to (4). (6) An optical disc using the optical disc substrate according to the item (5).

In the present invention, the "foreign matter" is a contaminant that is mixed in from every step of producing a transparent thermoplastic resin, especially an aromatic polycarbonate resin from raw materials and molding the optical disk substrate. Impurities and dust contained in raw materials (monomers, solvents, etc.), dust adhering to manufacturing equipment, and carbides generated in the molding process, and all components that are insoluble in solvents such as methylene chloride.

According to the present invention, in order to obtain an optical disk substrate having a high yield rate and a high reliability used for a high density optical disk such as a digital video disk, the above-mentioned (1) is used as a molding material used for molding the substrate. Or a transparent thermoplastic resin molding material for optics which satisfies the condition shown in the item (2). The molding material of the present invention is required to satisfy the conditions of the above (1) or (2), and a high density optical disk substrate molded from a material which does not satisfy the conditions is economically high in yield rate. A reliable optical disc substrate cannot be obtained. It is necessary that the molding material of the present invention satisfies the above conditions, and for a high density optical disk substrate molded from a material that does not meet the above conditions, an optical optical disk substrate for optical use with high yield and high reliability is economical. I can't get it well.

In the present invention, the particle size of the foreign particles for counting the total number of foreign particles is set to 15 μm or more when the defect inspection machine recognizes even optical distortion around the foreign particles, and the foreign particles having a particle size equal to or larger than this size, particularly copper, are contained. This is because when a foreign substance is present, it is often detected specifically as a defect having an allowable limit or more (for example, 100 μm or more). However, even if foreign particles of the same size are present, the degree of optical distortion varies depending on the position in the thickness direction of the substrate. In the thickness direction, the strain becomes smaller when it deviates from the central portion.

This does not mean that foreign matter of less than 15 μm may be present. 15 μm
It is better that the amount of foreign matter is less than another viewpoint.

In the present invention, the lower limit of the total number of foreign substances is set to 1/40 g in view of the burden on the manufacturing cost of the foreign substance removing step. From the viewpoint of reducing the burden, 3 /
It is possible to allow up to 40 g, and even up to 5 pieces / 40 g.

When the total number of foreign matters is close to these lower limit values, the proportion of copper or copper-containing foreign matters can be determined as an average value by increasing the number of measurement samples and increasing the total number of foreign matters.

The transparent thermoplastic resin used in the present invention is
A thermoplastic resin having transparency that can be used for optical applications, and examples thereof include acrylic resin, styrene resin, polycarbonate resin, and amorphous polyolefin resin. Among these, aromatic polycarbonate resins and alicyclic polyolefin resins, particularly aromatic polycarbonate resins are preferable.

With respect to the aromatic polycarbonate resin, the aromatic polycarbonate resin usable in the present invention is not particularly limited in its production method, but a dihydric phenol and a carbonate precursor are usually prepared by a solution polymerization method or a melt polymerization method. The thing obtained by making it react is mentioned. Representative examples of dihydric phenols 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 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'-dihydroxy Examples thereof include diphenyl sulfoxide, 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxydiphenyl ketone, 4,4′-dihydroxydiphenyl ether and 4,4′-dihydroxydiphenyl ester, which may be used alone or in combination of two or more. Can be mixed and used.

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 a homopolymer obtained from at least one bisphenol selected from the group consisting of α, α'-bis (4-hydroxyphenyl) -m-diisopropylbenzene or Copolymers are preferred, especially homopolymers of bisphenol A and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane with bisphenol A, 2,2-bis {(4-hydroxy- A copolymer with 3-methyl) phenyl} propane or α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene is preferably used.

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

When a polycarbonate resin is produced by reacting the above-mentioned dihydric phenol with a carbonate precursor by a solution polymerization method or a melt polymerization method, a catalyst, a terminal terminator and an antioxidant for the dihydric phenol may be added, if necessary. Etc. 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 difunctional carboxylic acid, It may also be a mixture of two or more of the obtained polycarbonate resins.

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

Further, in such a polymerization reaction, a terminal stopper is usually used. Monofunctional phenols can be used as such an end terminator. Monofunctional phenols are commonly used as molecular terminating agents for molecular weight control, and the resulting polycarbonate resins are compared to those that do not because the ends are blocked by groups based on monofunctional phenols. Excellent thermal stability. Such monofunctional phenols are generally phenols or lower alkyl-substituted phenols, and can be monofunctional phenols represented by the following general formula (1).

[0025]

[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 monofunctional phenols include phenol, p-tert-butylphenol, p-cumylphenol and isooctylphenol.

Further, 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.

[0029]

[Chemical 2]

[0030]

[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 such substituted phenols of formula (2), n is 10 to
30, especially 10 to 26 are preferable, and specific examples thereof include decylphenol, dodecylphenol,
Examples thereof include tetradecylphenol, hexadecylphenol, octadecylphenol, eicosylphenol, docosylphenol and triacontylphenol.

As the substituted phenols of the formula (3), compounds in which X is —R—CO—O— and R is a single bond are suitable, 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 triacontyl 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 reaction by the melt polymerization method is usually a transesterification reaction between a dihydric phenol and a carbonate ester, and an alcohol produced by mixing the dihydric phenol and the carbonate ester while heating in the presence of an inert gas. Alternatively, it is carried out by a method of distilling phenol. The reaction temperature varies depending on the boiling point of the alcohol or phenol to be produced, but is usually in the range of 120 to 350 ° C. In the latter stage of the reaction, the pressure of the reaction system is reduced to about 10 to 0.1 Torr to facilitate the distillation of the produced alcohol or phenol. The reaction time is usually about 1 to 4 hours.

Examples of the carbonate ester include an 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 thereof include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, among which diphenyl carbonate. Is preferred.

A polymerization catalyst can be used to accelerate the polymerization rate. Examples of the polymerization catalyst include alkali metal compounds such as sodium hydroxide, potassium hydroxide, sodium salt of dihydric phenol and potassium salt, 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, organotin 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 catalysts may be used alone or in combination of two or more. The amount of these polymerization catalysts used is preferably 1 × 10 ⁻⁸ to 1 × 1 with ^respect to 1 mol of the dihydric phenol as a raw material.
It is selected in the range of 0 ^-3 equivalent, more preferably 1 x 10 ^{-7 to} 5 x 10 ^-4 equivalent.

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
(Where [η] is the intrinsic viscosity) [η] = 1.23 × 10 ⁻⁴ M ^0.83 c = 0.7 After the raw material polycarbonate resin is produced by a conventionally known method (solution polymerization method, melt polymerization method, etc.) , Impurities such as low molecular weight components and unreacted components are removed by filtering in a solution state or washing the granular raw material after granulation (desolvation) with a poor solvent such as acetone under heating conditions. It is preferable to remove. 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. Especially, the difference in thermal conductivity with resin is 5 [W /
(M · K)] or more, in order to obtain a resin in which the amount of foreign matter, especially copper or copper-containing foreign matter, is small, select a raw material with less foreign matter as a polymerization raw material and use an apparatus with less such foreign matter. It is also requested to use it. It is also preferable to remove copper or copper-containing foreign matter by installing a magnetic separator in the step after pelletizing. Further, as a fundamental measure, it is also preferable to use as few pipes, equipments and devices made of materials that are considered to be related to the generation of the foreign matter specified in the present invention as possible in the process. If necessary, it is also preferable to add an additive such as a phosphorus-based antioxidant. In any case, it is necessary that the content of foreign materials, impurities, solvents, etc. in the raw material resin before injection molding be as low as possible.

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

Example 1 A bisphenol-A type polycarbonate resin powder having a viscosity average molecular weight of 15,000 was obtained by a solution polymerization method under conditions in which the mixing of external foreign matter and the generation of internal foreign matter were controlled, and then pelletized. Pellets were obtained. The pellet was dissolved in methylene chloride which had been filtered with a filter of 0.05 μm in advance, and this sample was filtered with a filter of 15 μm to obtain a filter collected product, and the number of foreign matters was visually counted. The total number of foreign matters was 35/40 g. In addition, the collected foreign matters are analyzed by the XMA analyzer OXF.
A more detailed analysis using a Link ISIS 300-I manufactured by ORD Co., Ltd. detected 8 pieces / 40 g of copper-containing foreign matters.

Next, using an optical disk substrate injection molding machine, Meiki Seisakusho M-35BD-DM, a cylinder temperature of 370 ° C. and a mold temperature of 118 ° C. were continuously used for 1,000.
Molded a number of DVD substrates, and check the yield rate of the obtained substrates in-1
It was measured by Basler's defect inspector.
This defect inspector uses a line scan camera with a resolution of 2,048 pixels and rotates the DVD substrate in the circumferential direction to scan 12,000 images of the entire surface of the DVD substrate. , To determine whether the board is good or bad. The quality of the defect inspecting machine was determined to be good or bad with 100 μm as a reference. Table 1 shows the obtained yield values.

It should be noted that when the defect inspecting apparatus recognizes and determines about 100 μm of the defective substrate as a defective product, the defective portion is visually inspected with a polarizing plate and a microscope, and it is found that a foreign substance of almost that size is present. However, there were many cases where foreign matter of about 15 μm was present. When the resin in the portion having a foreign substance of about 15 μm was dissolved in a solvent (chloroform), and the foreign substance was taken out from the resin and analyzed using the XMA analyzer, Cu was detected in many places.

Example 2 A bisphenol-A type polycarbonate resin powder having a viscosity average molecular weight of 15,000 was obtained by a solution polymerization method under the condition that the mixing of external foreign matter and the generation of internal foreign matter were controlled. This powder has a particle size of 15 to 20
Copper powder of μm was added and pellets were obtained by pelletizing.
The pellet was dissolved in methylene chloride which had been filtered with a filter of 0.05 μm in advance, and this sample was filtered with a filter of 15 μm to obtain a filter collected product, and the number of foreign matters was visually counted. The total number of foreign matters was 37/40 g. In addition, the collected foreign matter is analyzed by an XMA analyzer OXFO.
A more detailed analysis was performed using Link ISIS 300-I manufactured by RD, and 12/40 g of copper-containing foreign substances were detected.

Next, the non-defective rate evaluation similar to that in Example 1 was performed. Table 1 shows the obtained yield values.

Comparative Example A bisphenol-A type polycarbonate resin powder having a viscosity average molecular weight of 15,000 was obtained by a solution polymerization method under the condition that the mixing of external foreign matter and the generation of internal foreign matter were controlled. This powder has a particle size of 15 to 20
Copper powder of μm was added and pellets were obtained by pelletizing.
The pellet was dissolved in methylene chloride which had been filtered with a filter of 0.05 μm in advance, and this sample was filtered with a filter of 15 μm to obtain a filter collected product, and the number of foreign matters was visually counted. The total number of foreign matters was 39/40 g. In addition, the collected foreign matter is analyzed by an XMA analyzer OXFO.
A more detailed analysis was performed using Link ISIS 300-I manufactured by RD Co., Ltd., and 29 copper foreign matters / 40 g were detected.

The same experiment as in Example 1 was conducted except that this pellet was used. Table 1 shows the obtained yield values. Here, the thermal conductivity of copper is 336 [W / (m ·
K)] or more (Chemical Handbook (edited by The Chemical Society of Japan / Maruzen Co., Ltd.)), and the thermal conductivity of the polycarbonate resin is 0.203 [W / (m · K)] or less (Chemical Equipment Handbook (Chemical Industry) Meeting / Maruzen Co., Ltd.), and the difference in thermal conductivity between the two is 5 [W / (m · K)] or more.

[0047]

[Table 1]

From these results, in order to obtain a high-quality and high-reliability optical disc substrate for optical use, not only is the total amount of foreign substances present in the resin limited according to the present invention, but also various types of foreign substances Among these, it is understood that it is necessary to use an optical transparent thermoplastic resin molding material, particularly a polycarbonate resin molding material, in which the ratio of foreign matters is selectively limited based on the difference in thermal conductivity from the resin.

[0049]

INDUSTRIAL APPLICABILITY As described above, the present invention not only limits the total amount of foreign substances existing in the resin, but also selectively selects, among the various foreign substances, the difference in thermal conductivity from the resin. The present invention relates to an optical polycarbonate resin molding material characterized by limiting the proportion of the foreign matter and an optical disk substrate made of the material, and it is possible to obtain a highly reliable optical optical disk substrate with a high yield rate, particularly a digital optical disk substrate. The effect achieved by providing high-density optical discs such as video discs (DVDs) is exceptional.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11B 7/24 G11B 7/24 526Z 11/105 521 11/105 521A (72) Inventor Kyoichi Kubo Tokyo Chiyoda 1-2-2, Saiwaicho, ward F-Term inside Teijin Kasei Co., Ltd. (reference) 4J002 BC021 BG031 CG001 DA076 DE096 DJ006 DM006 GS02 5D029 KA01 KA07 KC09 5D075 EE03 FG15

Claims (6)

[Claims] 1. The total number of foreign particles having a particle size of 15 μm or more is 1.
55% or less of foreign matter having a number of 40/40 g or more and 50/40 g or less, of which the difference in thermal conductivity with the resin is 5 [W / (m · K)] or more. Transparent thermoplastic resin molding material for. 2. The total number of foreign matters having a particle size of 15 μm or more is 1.
A transparent thermoplastic resin molding material for optics, characterized in that the number is 40/40 g or more and 50/40 g or less, and copper or copper-containing foreign matter is 55% or less. 3. The optical transparent thermoplastic resin molding material according to claim 1, wherein the transparent thermoplastic resin is a polycarbonate resin. 4. The polycarbonate resin is 10,000
The optical transparent thermoplastic resin molding material according to claim 3, which has a viscosity average molecular weight of 0 to 22,000. 5. An optical disc substrate molded from the optical transparent thermoplastic resin molding material according to any one of claims 1 to 4. 6. An optical disc using the optical disc substrate according to claim 5.