Optical information recording medium near infrared absorbing mat

Details Optical information recording medium near infrared absorbing mat Optical information recording medium near infrared absorbing mat

1995-06-12

1997-10-14

Ryan, Patrick J.

Stock material or miscellaneous articles

Circular sheet or circular blank

428 642, 428 644, 428 647, 428 648, 428913, 430270, 430271, 430495, 430945, 369283, 369288, B32B 300

Patent

active

056770251

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to an optical information recording medium (which will be hereinafter sometimes referred to as recording medium) utilized for a computer memory, an image and voice filing memory, an optical card, etc., and to a near infrared absorbing material used therefor.


BACKGROUND ART

There is a known recording medium which has an organic dye film as a recording layer and in which a phthalocyanine compound is used for the organic dye film (JP-A-58-183296, JP-A-58-37851, etc.). While phthalocyanine compounds have advantages that they show extremely high stability against heat and light, they pose problems that they have poor solubility in organic solvents, they have a fault in productivity because they have never been hitherto formed into a film without resorting to a vapor deposition method, and they are apt to be associated so that high refraction index and high reflectance are not obtainable.
Recently, a semiconductor laser having an oscillation wave length which is shorter (near 680 nm) than those utilized in the conventional optical disks began to be put to practical use with a view toward making the recording density high. However, no organic dye films are known which show light absorptivity and light reflectivity in a wave length region of 700 nm or less. There is, therefore, a limit in a high density recording with respect to the material.
In a WORM compact disk-type (CD-R) recording medium having a substrate on which an organic dye film, a metal reflecting layer and a protecting layer are superimposed in this order, a high reflectance is required in order to meet with the CD standard. Thus, there has been a need for the development of an organic dye material which exhibits high reflectance in a reproduction wave length region (700-830 nm) and which is highly stable.
Recently, with a view toward accomplishing the prevention of association and the improvement in refraction index of phthalocyanine compounds, there was an attempt to introduce a bulky alkoxy group into the alpha-position of the phthalocyanine compounds and CD-R-type recording media were proposed in which the phthalocyanine compounds were further halogenated for attaining wave length matching (JP-A-3-62878, 3-215466, 4-34816, 4-226390, 4-15263-6, 5-17477, 5-86301, 5-25177, 5-25179, 5-17700, 5-1272, etc.). While such phthalocyanine compounds in fact provide an improvement in refraction index, they are still not fully satisfactory. A further improvement is desired.
It is, therefore, a first object of the present invention to provide a novel phthalocyanine near infrared absorbing material which has an improved solubility, which has high productivity and which shows high absorptivity for a near infrared ray, without adversely affecting the stability that is inherent to phthalocyanine compounds.
A second object of the present invention is to provide a recording medium whose recording material is a phthalocyanine compound which is highly soluble in organic solvents, which is high in productivity, which permits solvent coating and which retains advantages inherent to phthalocyanine compounds.
A third object of the present invention is to provide a recording medium which is applicable to optical pick up using a semiconductor laser of 630-700 nm and which permits high density recording.
A fourth object of the present invention is to provide a recording medium permitting the accomplishment of CD-R media which show high refraction index in a wave length region of 770-830 nm and which has excellent storage stability, excellent reproduction stability and high reflectance.


DISCLOSURE OF THE INVENTION

A phthalocyanine compound is a large cyclic planer compound and is tend to extremely highly associate. Thus, the phthalocyanine compound has such properties that, when the compound is formed into a film, the absorption spectrum becomes broad and the reflectance (refraction index) becomes lowered.
In this circumstance, in the present invention, a substituent having sterically bulky structure is introduced into the n

REFERENCES:
patent: 5132153 (1992-07-01), Hirose et al.
patent: 5232757 (1993-08-01), Kalyanaraman et al.
patent: 5248538 (1993-09-01), Kovacs et al.
patent: 5424171 (1995-06-01), Yanagisawa et al.

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