Mitsui Toatsu Chemicals, Incorporated

Mitsui Chemicals, Inc.

Yamamoto Chemicals, Inc.

Tomoyoshi Sasakawa

Sumio Hirose

Tadahiko Mizukuki

Nobuhisa Kitagawa

Tadashi Koike

Shinichi Murakami

Kouichi Yabuuchi

Kouhei Shizuka

Kenichi Sugimoto

Tsutami Misawa

Takeshi Tsuda

Taizo Nishimoto

Hideki Umehara

Yuji Inatomi

Shigeru Takahara

Yuko Suzuki

Jun Tokuhiro

Hiroyuki Hyakutake

Hiroshi Sukawa

Kouichi Shiina

An optical recording medium comprising a recording layer, a light interference layer, a reflective layer and a protective layer that are laminated on a substrate, characterized in that said recording layer and said light interference layer comprise at least one organic dye, and that a light absorbent and/or a thermal decomposition promoter are/is added to said light interference layer, wherein the optical recording medium has compatibility that allows good recording and/or reproduction by using lasers of different two wavelength ranges and has good recording properties.

Optical recording medium

An optical recording medium comprises a substrate, a recording layer overlying the substrate in a manner such that it is not present at the inner and outer peripheral portions of the substrate, a metal reflective layer overlying the recording layer in a manner such that the inner periphery of the metal reflective layer is coterminous with that of the recording layer while the outer peripheral portion of the reflective layer extends over the outer perphery of the recording layer, and a protective layer wholly covering the metal reflective layer extending over the recording layer, both at the inner and outer peripheral portions. The optical recording medium exhibits an excellent adhesion strength of the protective layer even when stood under high humidity and high temperature conditions for a long period of time, and the protective layer is not peeled off when subjected to a tape peeling test.

Optical recording medium and production thereof

An optical recording medium comprises a substrate, a recording layer overlying the substrate in a manner such that it is not present at the inner and outer peripheral portions of the substrate, a metal reflective layer overlying the recording layer in a manner such that the inner periphery of the metal reflective layer is coterminous with that of the recording layer while the outer peripheral portion of the reflective layer extends over the outer periphery of the recording layer, and a protective layer wholly covering the metal reflective layer extending over the recording layer, both at the inner and outer peripheral portions. The optical recording medium exhibits an excellent adhesion strength of the protective layer even when stood under high humidity and high temperature conditions for a long period of time, and the protective layer is not peeled off when subjected to a tape peeling test.

An optical recording medium of a single plate type capable of recording comprises a transparent resin substrate having a groove of 900-1800 .ANG. in depth and 0.3-0.6 .mu.m in width, a recording layer containing a dye overlying the substrate, a reflective layer overlying the recording layer and a protective layer overlying the reflective layer, the thickness of the recording layer being 800-1250 .ANG. at the groove portion and 500-1100 .ANG. at the land portion.

An optical recording medium of a single plate type comprises a substrate, a recording layer overlying the substrate, a reflective layer overlying the recording layer, and a protective layer overlying the reflective layer, the recording layer being produced by coating a nonpolar solvent-soluble substituted phthalocyanine dye in a nonpolar solvent and the nonpolar solvent content of in the recording layer being 5% by weight or less.

This invention relates to an optical recording medium characterized by high sensitivity, high stability, etc, and a process for making the optical recording medium. Specifically, the present invention provides an optical recording medium composed of a transparent substrate having prepits and/or pregrooves for system control signals and first and second recording layers formed thereon in order, the both layers having individually a specific reflectance, transmittance and absorbance. To the optical recording medium, a laser beam is irradiated on the transparent substrate side to record or read out information and, by detecting the variation of the amount of light as a sum of the reflected light from the boundary between the first recording layer and the substrate and the reflected light from the boundary between the second recording layer and the air, the system control signals are primarily obtained from the prepits and/or pregrooves. Regarding the two recording layers, the first recording layer contains an organic dye having a transmittance of 10-50% and an absorbance of 40% or more against the wavelength of a laser beam used for writing while the second recording layer contains an organic dye having an absorbance of 20% or less and a reflectance of 25% or more at the air boundary at the wavelength region of the laser beam. The optical recording medium can be made in accordance with the process of the present invention wherein (a) a transparent substrate having prepits and/or pregrooves for system control signals is provided, (b) two kinds of solution are prepared by allowing two organic dyes each soluble exclusively in either a low-polar solvent or else a high-polar solvent to dissolve in the respective counterpart solvent, and (c) the two kinds of dye solution are applied on the transparent substrate in series to form the first recording layer and the second recording layer.

Optical recording medium and process for fabricating the same

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Chiba, Japan

Tomoyoshi Sasakawa