JPH02304741A - Optical disk and its production - Google Patents

Abstract

PURPOSE:To obtain an optical disk having small retardation, excellent optical homogeneity and high read-out sensitivity for the information recorded therein by using a specified polycarbonate resin and/or polyformal resin as a substrate. CONSTITUTION:Polycarbonate resin and/or polyformal resin derived from 20 - 90 wt.% bis-fluorence compd. expressed by formula I is used as a substrate. In formula I, R<1> - R<2> represents H or lower alkyl or phenyl group with C1-4. Thereby, the obtd. optical disk has excellent shock resistance, heat resistance, moisture resistance, transparency, small retardation and excellent optical homogeneity, high read-out sensitivity of information and high reliability.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to optical recording discs, and in particular, to optical recording discs that use polycarbonate resins or polyformal resins as disc base materials, and that have excellent transparency, heat resistance, moisture resistance, and mechanical strength. The present invention relates to an optical disc that has excellent optical properties such as low retardation (birefringence value) and excellent optical homogeneity, and a method for manufacturing the same.

[Prior Art] As an optical information recording and reproducing method, a spot beam of a laser beam is directed onto an optical recording disk.

There is a method of reading signals recorded by minute pits on an optical recording disk by detecting the amount of reflected or transmitted light. This optical information recording and reproducing method can significantly increase the recording density, and the images and sound quality reproduced from it have excellent characteristics. It is expected that it will be widely put into practical use.

The optical recording disk used in this recording and reproducing system is strongly required not only to have a transparent disk base material so that the C-the rays can pass therethrough, but also to have optical homogeneity.

Methacrylic resin and the like have been known as this type of disk material.

Furthermore, polycarbonate resins obtained by reacting bisphenol A (2,2-bis(4'-hydroxyphenyl)propane) with phosgene, diphenyl carbonate, etc. are known.

[Problems to be Solved by the Invention] However, when methacrylic resin is used as a material, it is insufficient in terms of heat resistance, moisture resistance, and impact resistance.

In addition, in the case of the aforementioned polycarbonate resin, although it has excellent heat resistance, moisture resistance, impact resistance, etc., it has a large retardation value (birefringence value) and is inferior in optical homogeneity, which makes it difficult for the information recorded on the disc to be used. The disadvantage is that the reading sensitivity is reduced and errors occur (Nikkei Electronics, No. 292, June 7, 1982).

An object of the present invention is to provide an optical disc with small retardation, excellent optical homogeneity, and high sensitivity for reading information recorded on the optical disc, and a method for manufacturing the same.

[Means for Solving the Problems] That is, the present invention provides a bis(hydroxyphenyl)fluorene compound represented by the general formula (wherein R1 to R4 above represent H, a C1 to 4 lower alkyl group, or a phenyl group). 20-90% by weight
The present invention provides an optical disc characterized in that the base material is a polycarbonate resin and/or a polyformal resin derived from the following.

Further, the present invention provides an optical disc characterized in that an optical recording film is fixed to the optical disc.

Furthermore, the present invention provides a method of manufacturing the optical disc by injection molding.

If the amount of the above compound is less than 20% by weight, the optical disc is likely to undergo changes such as warping and twisting due to heat. On the other hand, 90
If it exceeds % by weight, impact resistance will be poor.

In addition, the number average molecular weight in terms of polystyrene is 2000~
200,000 is desirable, and 10,000 to 100,000 is particularly suitable. If the number average molecular weight is less than 2,000, the impact resistance and heat resistance will be poor, and if it is greater than 200,000, the performance will be poor and the optical properties after molding will be poor, which is not preferable.

Furthermore, as a component of the base material of the present invention, mold release improving aids such as silicone, wax, fatty acids, fatty acid esters, fatty acid metal salts, aliphatic alcohols, etc. can be used to improve mold release from the stamper. may be added.

In addition, for the purpose of preventing static electricity, antistatic aids such as sulfonates of higher alcohols and quaternary ammonium salts may be added, and phenolic or sulfur-based antioxidants may be added as heat stabilizers. These additions may be used in combination with the above-mentioned polycarbonate resin and polyformal resin to the extent that they do not impede achievement of the objectives of the present invention.

The optical disc of the present invention is made by injection molding the above resin.

Alternatively, by press molding, bits serving as recording signals are transferred to resin using a mold set with a stamper.

Furthermore, in the case of a duplicate disk, a reflective layer is generally formed on the bit transfer surface by a method such as metal vacuum deposition, sputtering, or ion blasting, and if necessary, a protective layer for the reflective layer is formed. It can be formed and manufactured.

In addition, in the case of a memory disk (optical recording disk), the disk transfers the bit that becomes the tracking signal in the same manner as above, and then heats the bit surface with, for example, an amorphous rare metal or a laser. A user-writable recording layer (optical recording film) is formed (fixed) by sputtering, vacuum deposition, coating, etc. and is made of a compound that can be decomposed into can be formed and manufactured.

In particular, in the case of writable and erasable optical recording disks (magneto-optical disks, phase change type optical disks, etc.), the disk transfers the bits that become the tracking signals in the same way as above, and then transfers the bits to the bit surface. For example, it is made of a magnetic metal, a compound whose phase can be thermally changed by a laser, or the like. A recording layer (optical recording film) that can be filled in and erased by the user is formed (fixed) by sputtering, vapor deposition, coating, etc., and if necessary, a reflective layer or a protective layer as described above is formed. , can be manufactured.

The base material of the optical disc is made of polycarbonate resin and polyformal resin in order to easily achieve uniformity.
Although it is preferable to consist of a single compound, it may be composed of a plurality of compounds, or a mixture of a polycarbonate resin and a polyformal resin.

[Example] Next, the present invention will be explained in more detail by way of examples.

Using the inventive sample and the comparatively soft sample shown below.

A magneto-optical disk was manufactured and its characteristics were measured. The samples of the present invention used are as shown in (A) to (R) below. however,
Let m and n be positive integers.

(Left below) A polycarbonate resin represented by formula (1) that has a polystyrene equivalent molecular weight of approximately 20,000 and contains 20% by weight of the fluorene compound component shown on the left... (A) In the above formula (1) A polycarbonate resin having a polystyrene equivalent molecular weight of approximately 20,000 and containing 60% by weight of the fluorene compound component shown on the left.
・Old...(B) Polycarbonate resin represented by the above formula (1), with a polystyrene equivalent molecular weight of approximately 20,000, and containing 90% by weight of the fluorene compound component shown on the left...
...(C) The molecular weight in terms of polystyrene is approximately 30,000, expressed as (the blank below),
A polycarbonate resin containing 60% by weight of the fluorene compound component shown on the left. A polycarbonate resin represented by (D) with a polystyrene equivalent molecular weight of approximately 20,000 and containing 50% by weight of the fluorene compound component shown on the left. ...(E) Expressed by equation (4). The molecular weight in terms of polystyrene is approximately 20,000,
Polycarbonate resin containing 30% by weight of the fluorene compound component shown on the left: (F) represented by formula (5), with a molecular weight of about 30,000 in terms of polystyrene,
Polycarbonate resin containing 70% by weight of the fluorene compound component shown on the left (G) represented by formula (6). The molecular weight in terms of polystyrene is approximately 40,000,
Polycarbonate resin containing 50% by weight of the fluorene compound component shown on the left: (H) represented by formula (7), with a molecular weight of about 20,000 in terms of polystyrene,
Polycarbonate resin containing 40% by weight of the fluorene compound component shown on the left: (1) Represented by formula (8). The molecular weight in terms of polystyrene is approximately 20,000,
Po containing 20% by weight of the fluorene compound component shown on the left,
Reformal resin: Polyformal resin represented by (J), which has a polystyrene equivalent molecular weight of about 20,000 and contains 20% by weight of the fluorene compound component shown on the left. (K) The above formula It is expressed as (9). A polyformal resin having a molecular weight in terms of polystyrene of approximately 20,000 and containing 60% by weight of the fluorene compound component shown on the left...(L) A polyformal resin having a molecular weight in terms of polystyrene of approximately 20,000, represented by the above formula (9)F. A polyformal resin having a polystyrene equivalent molecular weight of approximately 20,000 and containing 60 weight of the fluorene compound component shown on the left, represented by a polyformal resin containing 90 weight of the fluorene compound component shown on the left.
...The fluorene compound component shown on the left has a molecular weight of about 20,000 in terms of polystyrene, and is represented by (N).
Polyformal resin including the 0th economic downturn...
(0), the molecular weight in terms of polystyrene is approximately 3
Polyformal resin containing 70% by weight of the fluorene compound component shown on the left... (P) Formula (
I3) The molecular weight in terms of polystyrene is about 30,000,
Polyformal resin containing 40% by weight of the fluorene compound component shown on the left: (Q) Expressed by formula (14), the molecular weight in terms of polystyrene is approximately 30,000,
A polyformal resin containing 30% by weight of the fluorene compound component shown on the left... Polycarbonate resin (S) and acrylic resin (T
) was used.

The above 20 types of resin (polymer) pellets' were injection molded into a mold equipped with a stambar, and the thickness was 1.
A disk with a length of 2 m and a diameter of 120 mm was obtained.

Next, a TeFeCo-based magneto-optical recording film (
A recording layer (thickness = 0.1 μm) was formed (first
figure). In Figure 1, A is a disc substrate (optical disc), B is
indicates a magneto-optical recording film, C indicates a guide groove (group), and D indicates a pit.

Note that the dimensions in FIG. 1 are merely illustrative and do not limit the present invention.

Further, an acrylic lacquer was coated on this recording layer and dried to form a protective layer to obtain a magneto-optical disk.

(1) Light transmittance of the disc 20 types of resin plates (thickness 1.2
am) was prepared, and the light transmittance at a wavelength of 830 nm was determined using a spectrophotometer.

(2) Impact resistance The above 20 types of resin plates (shape: 50m x 50mm x 1
) was made, and a 107 g weight was dropped onto the resin plate using a Dejima Seisakusho m+i DuPont impact tester.

The distance between the weight and the resin plate when a crack appeared was determined as a measure of the impact strength of a falling ball.

(3) Glass transition temperature (Tg) The above 20 types of resin plates were made, and the Tg was determined using a differential scanning calorimeter.

(4) Heat resistance The 20 types of magneto-optical disks produced as described above were left at 120° C. for 4 hours, and then the presence or absence of warpage and twisting was determined.

(5) Moisture resistance The above 20 types of resin plates (shape: 50aaX50■X1
m) was prepared, and the weight increase rate after leaving it in water at 25° C. for one week was determined as the water absorption rate.

(6) Optical homogeneity The 20 types of magneto-optical disks produced as described above were irradiated with He-Ne laser light with a wavelength of 632.8 nm using an ellipsometer (manufactured by Mizojiri Optical Industry Co., Ltd.).
The retardation was measured at 10 locations from the inside to the outside of the magneto-optical disk. The maximum value was then displayed as the maximum retardation. A smaller maximum retardation value indicates better optical homogeneity.

As is clear from Table 1 below, which summarizes the results of one-dish aging evaluation, the resins (polymers) [(A) to (R)] according to the present invention
It can be seen that all magneto-optical disks manufactured using this material have superior optical homogeneity and higher information reading sensitivity than magneto-optical disks manufactured using ordinary polycarbonate resin [(S)]. .

Moreover, the resin (polymer) [(A) to (R) according to the present invention
] All magneto-optical disks manufactured using acrylic resin [: (T)] have superior impact resistance and heat resistance, and are more reliable than magneto-optical disks manufactured using ordinary acrylic resin [: (T)]. I understand that.

Furthermore, it was revealed that the resin-made magneto-optical disk according to the present invention also has good transparency and moisture resistance.

(The following is a blank space) [Effects of the Invention] As described above, the optical disc of the present invention and its manufacturing method have excellent impact resistance, heat resistance, moisture resistance, and transparency, and have small retardation and excellent optical homogeneity. It also has high information reading sensitivity and excellent reliability.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical sectional view showing a disk substrate and a recording film before coating a protective layer of a magneto-optical disk according to an embodiment of the present invention. A... Disk substrate (optical disk), B... Magneto-optical recording film, C... Guide groove (group), D... Pit. 'Figure 1

Claims (1)

[Claims] 1. 20 to 90% by weight of a bis(hydroxyphenyl)fluorene compound represented by the general formula ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (However, the above R^1 to R^4
represents H, a lower alkyl group of C_1_ to_4 or a phenyl group. 2. The bis(hydroxyphenyl)fluorene compound has a number average molecular weight of 2000 to 20 in terms of polystyrene.
2. The optical disc according to claim 1, wherein the optical disc is in the range of 10,000 to 10,000. 3. The optical disc according to claim 1, wherein the bis(hydroxyphenyl)fluorene compound has a number average molecular weight in terms of polystyrene in the range of 10,000 to 100,000. 4. The base material contains a mold release improving agent, an antistatic agent and/or
Claims 1 and 2 characterized in that it contains a heat-resistant stabilizer or a heat-resistant stabilizer.
or the optical disc described in 3. 5. An optical disc comprising an optical recording film adhered to the optical disc according to claim 1, 2, 3 or 4. 6. 20 to 90% by weight bis(hydroxyphenyl)fluorene compound represented by the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, the above R^1 to R^4
represents a lower alkyl group or a phenyl group of C_1_ to_4) A base material made of a polycarbonate resin and/or a polyformal resin derived from
A method of manufacturing optical discs by injection molding.