JP2000302858A - Molding material for optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a molding material of polycarbonate having good moldability as well as a low birefringence by reacting 1,1'-bi-2-naphthol and 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisphenol with a carbonate forming compound. SOLUTION: Phosgene is blowed into 1,1'-bi-naphthol and 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisphenol in the existence of an alkali solution and an organic solvent followed by adding a quaternary ammonium salt to initiate polycondensation. Then a monovalent phenol is added to adjust molecular weight and further a tertiary amine polymerization catalyst is added to accelerate the polycondensation. The obtained polycondensation reaction product is a polycarbonate having structure units represented by formulas I and II, the content of the structure unit represented by formula I being 5 to 40 mol% of all the structure units, and having an intrinsic viscosity of 0.30 to 0.50 dl/g. The product is usable for a molding material for an optical recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to molding a polycarbonate resin optical recording medium having reduced moldability and reduced birefringence suitable for manufacturing optical recording media such as compact disks, laser disks, optical cards, MO disks, and the like. About the material.

[0002]

2. Description of the Related Art Bisphenol A type polycarbonate has recently been widely used as a base material for optical discs, taking advantage of its characteristics such as transparency, heat resistance, hydrolysis resistance and dimensional stability. However, there are some problems when using polycarbonate for optical disks.

Of the performance as an optical disk substrate, birefringence, which substantially weakens a laser beam used for reading and writing information, is the most important problem. For a material having a large birefringence, errors increase, and as a recording medium, Is inferior in reliability.

[0004] Various polycarbonate resin materials have been developed for the purpose of reducing the birefringence. (JP 6
However, in recent years, in the field of optical disks, which have been increasing in density, the measures against birefringence cannot be said to be sufficient with these materials.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a molding material for an optical recording medium having both excellent moldability and low birefringence.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the conventional problems, and as a result, a copolymerized polycarbonate resin derived from two specific bisphenols has a low birefringence. The present invention has been found to be a high-quality optical recording medium molding material having both excellent moldability and excellent moldability, and has completed the present invention.

[0007]

DETAILED DESCRIPTION OF THE INVENTION That is, the present invention has structural units represented by the general formulas (A) and (B), and the structural unit of the general formula (A) is 5 to 40 mol in all the structural units. % And an intrinsic viscosity of 0.30 to 0.50 dl / g.

[0008]

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[0009]

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[0010] More specifically, the polycarbonate of the present invention comprises 1,1'-bi-2-naphthol and 4,4 '-[1,3-phenylenebis (1-methylethylidene)] bisphenol and a carbonate ester. It is also obtained by reacting with a forming compound.

Examples of the carbonate-forming compound include phosgene and bisallyl carbonates such as diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, and dinaphthyl carbonate. These compounds can be used in combination of two or more.

The polycarbonate of the present invention can be prepared by a known method used for producing a polycarbonate from bisphenol A, for example, a direct reaction of a dihydric phenol with phosgene (phosgene method), or a reaction between a dihydric phenol and a bisaryl carbonate. , Etc. can be employed.

In the former phosgene method, 1,1'-bi-2-naphthol, which induces the general formula (A) in the present invention, and the general formula (B) are usually derived in the presence of an acid binder and a solvent. 4,4 '-[1,3-phenylenebis (1-methylethylidene)] bisphenol is reacted with phosgene. As the acid binder, for example, pyridine, hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide, and the like are used. As the solvent, for example, methylene chloride, chloroform, chlorobenzene, xylene and the like are used. Further, a tertiary amine catalyst such as triethylamine and a catalyst such as a quaternary ammonium salt are used to promote the condensation polymerization reaction, and phenol, pt-butylphenol, p-cumylphenol, A monofunctional compound such as a phenol represented by the general formula (C) is added as a molecular weight regulator.

[0014]

Embedded image (Wherein, R ₁ represents an alkyl group having 4 to 20 carbon atoms;
_{2 to} R ₃ each independently represent hydrogen, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Z represents an ester group, an ether group, a carbonyl group, or simply represents a bond. )

Further, if desired, antioxidants such as sodium sulfite and hydrosulfite, phloroglucin, isatin bisphenol, 1,1,1-tris (4-hydroxyphenyl) ethane, α, α ′, α ″- A small amount of a branching agent such as tris (4-hydroxyphenyl) -1,3,5-triisopropylbenzene may be added.
C, preferably in the range of 5 to 40C. The reaction time depends on the reaction temperature, but is usually 0.5 minutes to 10 hours, preferably 1 minute to 2 hours.
During the reaction, it is desirable to maintain the pH of the reaction system at 10 or more.

On the other hand, in the latter transesterification method,
1'-bi-2-naphthol, 4,4 '-[1,3-phenylenebis (1-
Methylethylidene)] bisphenol and bisaryl carbonate are mixed and reacted at elevated temperature under reduced pressure. At this time, a monofunctional compound such as pt-butylphenol, p-cumylphenol, and phenols represented by the general formula (C) may be added as a molecular weight regulator. The reaction is usually performed at a temperature in the range of 150 to 350 ° C., preferably 200 to 300 ° C., and the degree of vacuum is finally 1 mm.
It is preferable that the content be not more than Hg, and phenols derived from the bisaryl carbonate generated by the transesterification reaction are distilled out of the system. The reaction time depends on the reaction temperature and the degree of pressure reduction, but is usually about 1 to 6 hours. The reaction is preferably performed in an atmosphere of an inert gas such as nitrogen or argon. Further, if desired, the reaction may be performed by adding an antioxidant or a branching agent.

As the molecular weight regulator of the present invention, a monohydric phenol represented by the general formula (C), which is expected to be effective in improving fluidity, is preferable.
Long-chain alkyl-substituted phenols such as octylphenol, nonylphenol, decanylphenol, tetradecanylphenol, heptadecanylphenol, and octadecanylphenol; butyl hydroxybenzoate, octyl hydroxybenzoate, nonyl hydroxybenzoate, decanyl hydroxybenzoate, Hydroxybenzoic acid long-chain alkyl esters such as heptadecanyl hydroxybenzoate;
Long-chain alkyloxyphenols such as butoxyphenol, octyloxyphenol, nonyloxyphenol, decanyloxyphenol, tetradecanyloxyphenol, heptadecanyloxyphenol, and octadecanyloxyphenol are exemplified.

In the phosgene method and the transesterification method, the phosgene method is more preferable in consideration of the reactivity of the compound for deriving the structure of the general formula (A) and the compound for deriving the structure of the general formula (B).

When the phosgene method is employed in the present invention, it is preferable to add a small amount of a quaternary ammonium salt in order to carry out the reaction efficiently after the completion of the phosgene blowing.
Specifically, tetramethylammonium chloride, trimethylbenzylammonium chloride, triethylbenzylammonium chloride, tetraethylammonium bromide, tetra-n-butylammonium iodide and the like are exemplified, among which trimethylbenzylammonium chloride and triethylbenzylammonium chloride are exemplified. preferable. The quaternary ammonium salt is generally preferably used in an amount of 0.0005 to 5 mol% based on all bisphenols used. Three to ten minutes after the addition of the quaternary ammonium salt, a tertiary amine such as triethylamine and a molecular weight regulator are preferably added for polymerization. The addition amount of the tertiary amine is 0.01 to 1.0 mol% based on all bisphenols. The amount of the molecular weight modifier to be added is 3 to 10 mol% based on all bisphenols.

The polycarbonate polymer synthesized by these reactions can be molded by a known molding method such as extrusion molding, injection molding, blow molding, compression molding, and wet molding. It is desirable that extrusion and injection molding can be easily performed, and in particular, in the case of precision molding for optical recording media, the intrinsic viscosity is preferably in the range of 0.30 to 0.50 dl / g.

The structural unit represented by the general formula (A) of the present invention comprises all structural units in consideration of moldability, heat resistance and low birefringence.
5-40 mol% is preferred. The structural unit of general formula (A) is 5mo
If it is less than 1%, the effect of improving the birefringence is small, and if it exceeds 40 mol%, the molding conditions are narrowed due to an increase in the glass transition temperature, and molding defects and an increase in birefringence due to molecular orientation are likely to occur.

The polycarbonate molding material for an optical recording medium of the present invention is preferably molded by injection molding. If the fluidity is too large or too small, there is a problem in moldability. For example, Koka type flow tester (280 ° C, 160kgf / c
m ² , nozzle diameter 1mm x 10mm) measurement, 15 ~ 90 × 10 ^-2 cc / sec
Is preferable. If the flow rate is less than 15 × 10 ^-2 cc / sec, the fluidity is poor and poor filling into the mold or a flow mark may occur.If the flow rate exceeds 90 × 10 ^-2 cc / sec, mold release failure or warpage is likely to occur. .

The polycarbonate molding material for an optical recording medium of the present invention must be highly refined as in the case of a general polycarbonate for an optical disk. Specifically, dust having a diameter of 50 μm or more is substantially not detected, dust having a diameter of 0.5 to 50 μm is 3 × 10 ⁴ or less, inorganic and organic residual chlorine is 2 ppm or less, residual alkali metal is 2 ppm or less, and residual hydroxyl group Purification is performed so as to satisfy the criteria as low as possible, such as 200 ppm or less, residual nitrogen amount 5 ppm or less, and residual monomer 20 ppm or less. In some cases, post-treatment such as extraction is performed to remove low molecular weight substances or remove solvents.

The polycarbonate molding material for an optical recording medium may be a hindered phenol-based or phosphite-based antioxidant; Lubricants and mold release agents such as ester, fatty acid, fatty acid glyceride, beeswax and other natural fats and oils; benzotriazole, benzophenone, dibenzoylmethane, and salicylate light stabilizers; polyalkylene glycol, fatty acid glyceride, etc. An antistatic agent or the like may be appropriately used in combination, and furthermore, it is possible to use it arbitrarily by mixing it with ordinary polycarbonate for optical recording media within the range that does not impair the performance in terms of cost and the like. The molding temperature for injection molding of the present molding material is preferably 280 to 360 ° C. from the viewpoint of fluidity.

[0025]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 1,1'- was added to 58 liters of an 8.8% (w / v) aqueous sodium hydroxide solution.
Bi-2-naphthol 2.86Kg (hereinafter abbreviated as BNP, 10mol)
10.38 kg of 4,4 '-[1,3-phenylenebis (1-methylethylidene)] bisphenol (hereinafter abbreviated as BPM, 30 mol) and 10 g of hydrosulfite were added and dissolved. To this, 36 liters of methylene chloride was added, and 5 kg of phosgene was blown in over 50 minutes while stirring at 15 ° C. After blowing, 5 g of triethylbenzylammonium chloride
(0.022 mol) was added and vigorously stirred for 5 minutes to emulsify the reaction solution, and then 300 g of p-tert-butylphenol (hereinafter referred to as PTBP).
2.0 mol), 20 ml of triethylamine (0.14 mol) was further added, and the mixture was stirred and polymerized for about 1 hour. The polymerization liquid is separated into an aqueous phase and an organic phase, the organic phase is neutralized with phosphoric acid,
After repeated washing with water until the conductivity of the washing liquid became 10 μS or less, a purified resin liquid was obtained. The obtained purified resin liquid was slowly dropped into 45 ° C. hot water under vigorous stirring to solidify the polymer while removing the solvent. After filtering the solids,
After drying, a white powdery polymer was obtained. This polymer had an intrinsic viscosity [η] of 0.36 dl / g at a temperature of 20 ° C. in a solution having a concentration of 0.5 g / dl using methylene chloride as a solvent. As a result of analyzing the obtained polymer from an infrared absorption spectrum, 17
Absorption by a carbonyl group at a position near 70 cm ^-1 , 1240 cm ^-1
Absorption by an ether bond was observed in the vicinity of the position, and it was confirmed that the compound had a carbonate bond. Also, 3650 ~
Almost no absorption due to hydroxyl groups was observed at the position of 3200 cm ^-1 . The monomer in this polycarbonate is
All the monomers were below 20 ppm as determined by analysis. As a result of combining these, this polymer was recognized as a polycarbonate polymer composed of the following structural units.

[0027]

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To the obtained polycarbonate powder, 300 ppm of stearic acid monoglyceride was added, and the mixture was treated with a vented 50 mm extruder equipped with a 50 μm polymer filter.
C. and extruded to form a melt pellet. The obtained pellets were obtained at a resin temperature of 350 ° C., a mold temperature of 100 ° C., and an injection pressure of 29.4 MPa, with an outer diameter of 120 mm and a thickness of 1.
A 2 mm disk was injection molded, and after being left indoors for 2 days, the birefringence at 30 ° oblique incidence was measured. The flow value (Q value) of the extruded pellet was measured and used as a measure of molding fluidity. Further, a cast film having a thickness of 50 μm was prepared using polycarbonate powder, and a photoelastic sensitivity was measured by applying a load of 300 to 1100 g. The results are shown in Table 1.

Example 2 BNP was changed to 4,58 kg (16 mol), BPM was changed to 8.3 kg (24 mol), and 664 g of p-heptadecanylphenol was used instead of PTBP.
(Hereinafter abbreviated as PHPDP, 2.0 mol) in the same manner as in Example 1. Intrinsic viscosity [η] of the obtained polymer
Was 0.37 dl / g, and the polymer was confirmed to be a polycarbonate polymer having the following structural units by infrared absorption spectrum analysis or the like. The results are shown in Table 1.

[0030]

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Example 3 Example 1 except that BNP was changed to 1.14 kg (4 mol), BPM was changed to 12.46 kg (36 mol), and PTBP was changed to 240 g (1.6 mol).
The same was done. The intrinsic viscosity [η] of the obtained polymer is 0.1.
At 49 dl / g, this polymer was confirmed to be a polycarbonate polymer having the following structural units from infrared absorption spectra and the like. The results are shown in Table 1.

[0032]

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Example 4 The BNP was changed to 2.29 kg (8 mol) and the BPM to 11.07 kg (32 mol), and 1,1,1-tris (4-hydroxyphenyl) ethane 24
The procedure was performed in the same manner as in Example 1 except that g (0.08 mol) was added. The intrinsic viscosity [η] of the obtained polymer was 0.40 dl / g, and the polymer was recognized as a polycarbonate polymer having the following structural unit from an infrared absorption spectrum or the like. Table 1 shows the results
It was shown to.

[0034]

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COMPARATIVE EXAMPLE 1 Instead of the polycarbonate of Example 1, 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as "commercially available") for optical recording media was used.
BPA) type polycarbonate (Mitsubishi Gas Chemical Co., Ltd.)
Example 1 using H-4000 ([η] = 0.35dl / g).
The same test was performed. The results are shown in Table 1.

Comparative Example 2 Without BNP, using only 13.84 kg (40 mol) of BPM and 288 g of PTBP
(1.92 mol) in the same manner as in Example 1. The intrinsic viscosity [η] of the obtained polymer was 0.35 dl / g, and the polymer was recognized as a polycarbonate polymer having the following structural units from infrared absorption spectra and the like. Table 1 shows the results
It was shown to.

[0037]

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Comparative Example 3 The procedure of Example 1 was repeated, except that BPM was not used and only BNP was used at 11.44 kg (40 mol). The reactivity of BNP was poor, and a large amount of unreacted monomer was generated. The intrinsic viscosity was 0.25 dl / g, and molding was not possible due to insufficient strength.

[0039]

[Table 1]

[Explanation of Table 1] Birefringence: Automatic ellipsometer manufactured by Mizojiri Optical Industry Co., Ltd.
Measurement wavelength: 632.8 nm. Photoelasticity sensitivity: 300 to 1100 for a 50 μm thick cast film
g was applied and the photoelastic sensitivity was measured at an Epson meter wavelength of 632.8 nm. Flow value (Q value): Shimadzu Corporation's high-grade flow tester is used. 280 ℃, 160kgf / cm ^2, the flow rate per unit time in the nozzle diameter 1 mm × 10 mm conditions. (Unit x 10 ^-2 cc / sec) BNP: 1,1'-bi-2-naphthol BPM: 4,4 '-[1,3-phenylenebis (1-methylethylidene)] bisphenol BNP Concentration: Formula (A ) Ratio of structural units to total structural units
(mol%). BPM concentration: The ratio of the formula (B) structural unit to all structural units
(mol%). Intrinsic viscosity: 0.5g / 100cc dichloromethane resin solution 20
The intrinsic viscosity [η] (dl / g) was determined at 0 ° C. and the Huggins constant of 0.45.

[0041]

According to the present invention, it is possible to provide a molding material for an optical recording medium having both excellent moldability and low birefringence. In particular,
It is suitable for rewritable optical disks and magneto-optical disks that require high-density recording and reliability.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J029 AA09 AB01 AB02 AB04 AC02 AD01 AD10 AE04 AE05 BB16A BC09 HA01 HC01 JA091 JB191 JC031 JC091 JC221 KB25 KE09 5D029 KA07 KC07

Claims (5)

[Claims] 1. It has a structural unit represented by the general formula (A) or (B), wherein the structural unit of the general formula (A) is 5 to 40 mol% of all the structural units, and the intrinsic viscosity is 0.30-0.50dl
/ g polycarbonate molding material for optical recording media. Embedded image Embedded image (2) 1,1'-bi-2-naphthol and 4,4 '-[1,3-
2. A molding material for an optical recording medium according to claim 1, wherein phenylenebis (1-methylethylidene)] bisphenol is reacted with a carbonate-forming compound. 3. The molding material for an optical recording medium according to claim 1, wherein the molecular terminal is derived from a monohydric phenol represented by the general formula (C). Embedded image (Wherein, R ₁ represents an alkyl group having 4 to 20 carbon atoms;
_{2 to} R ₃ each independently represent hydrogen, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Z represents an ester group, an ether group, a carbonyl group, or simply represents a bond. ) 4. An aqueous solution of an alkali in the presence of an alkaline aqueous solution and an organic solvent.
After blowing phosgene into 1'-bi-2-naphthol and 4,4 '-[1,3-phenylenebis (1-methylethylidene)] bisphenol, a quaternary ammonium salt is added to start the polycondensation reaction. 2. The method for producing a molding material for an optical recording medium according to claim 1, further comprising adding a monohydric phenol serving as a molecular weight regulator and further adding a tertiary amine polymerization catalyst to promote polycondensation. 5. The method for producing a molding material for an optical recording medium according to claim 4, wherein the quaternary ammonium salt is triethylbenzylammonium chloride or trimethylbenzylammonium chloride.