JPS59202892A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To improve sensitivity (Record reproduction), S/N and durability (especially, heat-resistance, light-resistance), by installing on a substrate a pigment thin film recording layer using the specified cyanine pigment as a pigment. CONSTITUTION:A pigment thin film is so formed that 1-methyl-2-[7-(1-methly-3,3- dimethyl-5-halo-2-indolinylidene-1,3,5-heptatrienyl]-3,3-dimethyl-5-ha loindolium perchlorate is dissolved in an organic medium and this solution is spread over the substrate. The pigment thin film recording layer feature sensitivity, SN and further, both heat-resistance and light-resistance are excellent that assure long durability.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an optical information recording medium having a dye thin film containing a specific cyanine dye. More specifically, the present invention relates to an optical information recording medium used in a method in which information is directly recorded using a laser beam and information is reproduced by changes in reflected light.

Prior Art Conventionally, optical information recording media to which a dye thin film is applied as a recording medium have been known (for example, Japanese Patent Application Laid-Open No. 1694-1983).
Publication No. 8). In other words, in this type of optical memory medium, a metal reflective film is provided between the substrate and the dye thin film recording layer, and a laser beam of a wavelength at which the light absorption rate of the recording layer is at its maximum is focused and irradiated from the recording layer side. It is used to record and reproduce information.

However, in such optical information recording media, it is difficult to protect the dye recording layer, so small dust adhering to the recording layer tends to cause errors in recording and reproducing f-good news, and reflective optical information recording media In order to be used as a storage medium, a metal reflective film is required, the structure of the medium is complicated, the recording/reproducing sensitivity is not sufficient, and the information recording medium itself is not suitable for long-term storage. be.

Purpose The present invention was made in view of the above problems, and its purpose is to provide an optical information recording medium with high sensitivity (recording/reproduction) and S/N, and high storage stability (especially heat resistance and light resistance). Our goal is to provide the following.

Structure In order to achieve the above object, the present invention uses a compound having a specific structure as a dye in a dye thin film recording layer of an optical information recording medium. That is, the dye of the present invention is a 1-methyl-2-(7-(1-methyl -3,6-
cymethyl-5-noro-2-indolinisdene) -1
. This dye was found to have particularly excellent heat resistance and light resistance among cyanine dyes.The reason for this is not yet fully understood, but it is due to the large ionic radius of the counter ion and the indole ring size. Shadow of the electron attraction effect by No. 10 Gen 1. ).

The optical information recording medium of the present invention basically comprises a substrate and a dye thin film recording layer. If necessary, a subbing layer, a protective layer, etc. can be further provided. It is also possible to have a so-called air sand inch structure in which two recording media are placed facing each other with their recording layers facing each other.

The dye thin film in the present invention is, for example, 1-methyl-2-
(7-(1-methyl-3,3-dimethyl-5-halo2
-indolinylidene)-1,3,5-enyl)-5,3-dimethyl-5-haloindolium verchlorate in an organic solvent (e.g. evaporated methanol, methylene dihydride, dichloroethane, etc.) It is formed by dissolving and applying (eg spin-coating) this solution. The thinner the dye thin film is, the better the sensitivity will be, but the reflectance will also be lower, so for practical purposes it is preferably in the range of 10 to 1 [10 nm].

Information is recorded by focusing laser light with a lens to form minute holes (pits) on the recording layer, and reading is performed by irradiating a weak laser light and measuring the reflectance of the pit and other parts. This can be done by using the difference between

EXAMPLES The present invention will be further described below with reference to Examples as well as comparative examples, but the present invention is not limited thereto.

EXAMPLE A tOq6 dichloroethane solution of the dye shown in the structural formula in the table below was spin-coated onto a surface-hardened acrylic plate and dried to obtain a recording layer with a thickness of 46 nm.

The thus obtained recording medium was irradiated with a semiconductor laser with a wavelength of 790 nm, an irradiation surface power of 3.5 mW, and a beam diameter of 15 mW.
μm and linear velocity of 1.2 m/sea [1
A signal of 7M [(H) was recorded. When this recording section was irradiated with a weak laser beam and the signal was reproduced, the O/N was 58 dB.
was obtained (engine frequency band width 30 KHz).

Note that the reflectance and transmittance of this recording medium at 790 nm were 289b and 14%, respectively.

This recording medium was stored in an oven at 100° C., and the rate of discoloration due to heat was examined based on changes in transmittance. In addition, the samples were left under tungsten rubber irradiation to examine changes in transmittance and speed of color fading due to light.

As a comparative example, a similar recording medium was prepared using another similar compound that does not have a halogen atom on the indole ring, and the rate of color fading was investigated, and the values are shown in the table below.

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) Effects Since the dye thin film recording layer using the dye of the present invention has excellent heat resistance and light resistance, it can provide an optical information recording medium with a long life.

Claims (1)

[Claims] 1-Methyl-2-C7-(1-methyl-3,3-dimethyl-5-halo-2-indolinylidene)-1,3,5-hebutatrienyl)-3,3- as a dye on the substrate
An optical information recording medium comprising a dye thin film recording layer using dimethyl-5-haloindolium barchlorate.