JPH0233742A - Black-type optical disk substrate - Google Patents

Abstract

PURPOSE:To manufacture easily the black-type optical disk substrate by incorporating a combination of green, blue and red dyes which transmit light of specific wavelength into polycarbonate and controlling the transmittance of the polycarbonate at specific values. CONSTITUTION:The green, glue and red dyes which allow laser light, especially near 780nm and 830nm wavelength, to transmit are incorporated into the polycarbonate to constitute the black-type optical disk substrate having light transmittance <=10% for 400 - 650nm, and >=80% for 770 - 850nm. The dyes to be used are not specified except that they endure the temperature of forming polycarbonate. Also, colors of green, blue, and red are not limited to the standard colors.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an optical disk substrate, particularly a black optical disk substrate.

<Prior art> A method of detecting minute irregularities on a substrate using a laser beam to reproduce sound and images, and a recording/reproducing method of recording and reproducing information using an information recording layer provided on one side of the substrate have recently attracted attention. ing.

The resin substrate used for such information recording is required to have excellent transparency, and polycarbonate is used because it has excellent transparency.

In addition, since optical disk substrates are required to be transparent,
It was rarely colored, and even if it was, it was only light colors.

On the other hand, optical disk substrates such as audio compact
Black is the mainstream color for records, the predecessor of discs, and black is also a major trend in color, but it would be completely unthinkable to make the disc base black because it would prevent laser beams from passing through it. Met.

<Object of the Invention> An object of the present invention is to provide a black disk substrate. The inventor has discovered that laser beams, in particular 7B0nI1
1 neighborhood and 830rll! The present invention was completed as a result of extensive research into methods of creating a color tone close to black by combining various dyes that do not interfere with the transmission of light in the vicinity of 1.

<Structure of the Invention> That is, the present invention consists of polycarbonate 1 to 400 containing a green dye and/or a blue dye and a red dye.
- 11 items with light transmittance of 10% or less at a wavelength of 650 nm
The present invention relates to a black optical disc substrate having a light transmittance of 80% or more at a wavelength of 770 to 850 nm.

Polycarbonate I to be used in the present invention is produced by reacting a dihydric phenol and a carbonate I precursor by a solution method or a melt method.

A typical example of dihydric phenol is 2.2-his (
4-Hydroxyphenyl)propane [bisphenol△
], 1,1-bis(4-hydroxyphenyl)cyclohexylene, 2,2-bis(4-hydroxy3.5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dibu[ ] Mphenyl) propane, 2.2
-bis(4-hydroxy-3-methylfer)propane, bis(4-hydroxyphenyl)sulfone, and the like. Preferred dihydric phenol/hydric phenol is a bis(4-hydroxyphenyl)alkane, especially one in which bisphenol A is used as the main raw material. Further, examples of the carbonate 1 to precursor include 7J rubonylhalite, carbonyl ester, or haloformate, and specific examples thereof include phosgene, diphenyl carbonate, dihalopormate of dihydric phenol, and mixtures thereof.

In manufacturing polycarbonate-1-, the above-mentioned dihydric phenols can be used alone or in combination of two or more.

Furthermore, two or more types of the obtained polycarbonates may be used in combination. The viscosity average molecular weight of polycarbonate is generally 10,000 to 50,000, preferably 13,000.
~30000. When producing such polycarbonates 1 to 1, suitable molecular weight regulators, branching agents for improving processability, catalysts for promoting reactions, etc. can be used as necessary.

The green dye, blue dye, and red dye to be used do not need to be particularly limited as long as they can withstand the molding temperatures of polycarbonate 1, and green, blue, and red do not have to be standard colors. good.

The ratio and amount of green dye, blue dye, and red dye used vary depending on the color tone of each dye and the color tone of the intended disk substrate. 400-650nm of substrate
The light transmittance of the wavelength should be 10% or less, preferably 5% or less. If the light transmittance exceeds 10%, the obtained disk substrate will not have a black color and the objective will not be achieved.

In addition, when using a combination of green dye and red dye, blue dye and red dye, or green dye, blue dye and red dye, a small proportion of a dye of another tone, such as yellow dye, may be added. 400-6 of the disk substrate obtained using
It is also possible to further reduce the light transmittance at a wavelength of 50 nm, which is also preferable. However, it is necessary to use a material that does not lower the light transmittance of the resulting disk substrate for wavelengths of 770 to 850 nm below 80%, preferably below 85%. This light transmittance is 80%, preferably 80%.
If it is less than 5%, it will impede the transmission of laser light, making it unsuitable as a disk substrate.

Any method can be used to dye polycarbonate. Usually, a predetermined amount of dye is blended into polycarbonate in the form of powder or pellets, and dyed pellets are formed using an extruder. At this time, it is also possible to mix a high concentration of dye to form a master pellet, which is then mixed with undyed polycarbonate pellets.

Furthermore, in order to produce a black disc substrate, the dyed polycarbonate pellets 1 to 1 described above or a mixture of highly dyed polycarbonate pellets and undyed polycarbonate pellets are used and molded according to a conventional method. Bye.

<Effects of the Invention> According to the present invention, it has become possible for the first time to easily provide a black disk substrate, which has not been considered in the past.

<Example> Examples will be given below for further explanation. Note that the light transmittance was measured using a Hitachi spectrophotometer U-2000 on a sample plate with a thickness of 1 mm.

Examples 1 to 3 The dye listed in Table 1 was added to the powder of bisphenol △ with a viscosity average molecular fi of 15,000 to 1 q of polycarbonate 1 in the amount listed in the table, mixed, and then an extruder was used to produce 27
It was turned into pellets at 0°C. The obtained berets 1 to 1 are molded into mold 7 at 340℃ using a 3-ounce indexing machine. J degree 80°
A sample plate was molded using C. The measurement results of each spectral transmittance are as shown in FIGS. 1 to 3. The chart of Example 1 is shown in FIG. 1, the chart of Example 2 is shown in FIG. 2, and the chart of Example 3 is shown in FIG.

(margin below)

[Brief explanation of the drawing]

FIGS. 1 to 3 are charts showing the light transmittance of the black disc substrate of the present invention. Diagram

Claims (1)

[Claims] Made of polycarbonate blended with a green dye and/or a blue dye and a red dye, and has a light transmittance of 10% or less in the wavelength range of 400 to 650 nm and in the wavelength range of 770 to 850 nm.
A black optical disc substrate having a light transmittance of 80% or more at a wavelength of .