JPH01260646A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To improve thermal and optical stability and to prevent degradation of regenerated signal, by incorporating specific compounds in one layer among a primer coating, recording layer and protective layer. CONSTITUTION:At least one compound selected from formulae I and II is to be incorporated in at least one layer among the primer layer, recording layer and protective layer. In formulae I and II, R1-R8 represent substituted or non- substituted alkyl groups, alkoxy groups or hydrogen, and X represents an acid anion. Namely, the recording medium is essencially composed by providing the recording layer on the substrate, said recording layer comprising an organic dye the chief component of which is polymethyne compound. As required, the primer layer is provided between the substrate and the recording layer, or the protective layer on the recording layer. Therefore, the thermal stability and optical stability can be improved and degradation of regenerated signal can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an improved optical information recording medium that can be used in the optical recording field.

[Prior art]

Until now, optical information recording media have been proposed in which a recording layer made of a low melting point metal or a low melting point metal and a dielectric is provided on a substrate, but these have poor storage stability, low resolution, and recording density. It has disadvantages such as low yield, difficult manufacturing conditions, and high cost. Therefore, it has recently been proposed to use an organic dye thin film as the recording layer in place of the metal thin film. This organic dye thin film has a low melting point, low decomposition temperature, and low thermal conductivity, so it has the potential for high sensitivity and high density, and because film formation can be done by coating, it is highly mass-producible and expected to be low cost. There are advantages such as being able to

Conventionally, it has been known to use a film of a polymethine compound such as a cyanine dye or a merocyanine dye as the organic dye film. However, recording layers composed of such dyes have poor heat and light stability, have problems with storage stability, and are susceptible to playback deterioration. An object of the present invention is to provide an optical information recording medium having a recording layer containing a polymethine compound that has excellent properties and improved reproduction deterioration.

〔composition〕

The above object is achieved by incorporating the following general formula (1) into at least one of the undercoat layer, the recording layer and the M retention layer in the optical information recording medium.
This is achieved by containing at least one compound selected from (II) and (II).

General formula (■) 2 General formula (■): (In the above formula, R1 to R8 are substituted or unsubstituted alkyl groups or alkoxy groups or hydrogen, and X represents an acid anion.) The optical information recording medium of the present invention includes: Basically, it is constructed by providing a recording layer made of an organic dye mainly composed of a polymethine compound on a substrate, but if necessary, an undercoat layer or a recording layer may be added between the substrate and the recording layer. A protective layer can be provided on top.

Alternatively, the pair of recording media configured in this manner may be formed into an air sandwich structure in which the recording layer is placed inside and sealed with another substrate through a space, or an air sandwich structure in which the pair of recording media is bonded through a protective layer (laminated) may be used. ) structure.

Next, the materials constituting the optical information recording medium of the present invention and the necessary characteristics of each layer will be specifically explained.

(1) Substrate 3 - As a necessary characteristic of the substrate, it must be transparent to the laser beam used only when recording and reproducing is performed from the substrate side, and it does not need to be transparent when recording and reproducing is performed from the recording side. As the substrate material, for example, plastics such as polyester, acrylic resin, polyamide, polyolefin resin, phenol resin, epoxy resin, polyimide, glass, ceramic, or metal can be used.

Note that a preformat such as an address signal or a pregroove for a guide groove may be formed on the surface of the substrate.

(2) Recording layer The recording layer is capable of recording information by causing some kind of optical change by irradiation with laser light, and is made of an organic dye whose main component is a polymethine compound. In this case, the polymethine compound includes polymethine dyes, cyanine dyes, merocyan dyes, croconium dyes, pyrylium dyes, etc. Specific examples include those described in JP-A-58-194595, etc. There is.

In order to improve recording characteristics and stability, the recording layer of the recording medium of the present invention may contain other dyes, such as phthalocyanine-based dyes, te-1-lahytrocholine-based dyes, dioxazine-based dyes, triphetchazine-based dyes, and phenanthrene dyes. dyes, anthraquinone (indanthrene), xanthine, triphenylmethane, triphenylamine, azulene dyes, and metals or metal compounds, such as In, Sn,
Te, Bi, ^Q, Se, TeO2, SnO3Ag
, Cu, etc. may be mixed and dispersed, or may be laminated. In addition, the recording layer can contain a polymer material, a storage stabilizer (metal complex, phenolic compound), a dispersant, a flame retardant, a lubricant, a pharynx agent, and the like. The thickness of the recording layer is 100 to 10/jm, preferably 200 to 2 μm. Methods for forming the recording no. include vapor deposition, CVD,
In addition to sputtering, solvent coating methods such as dip coating, spray coating, spinner coating,
Blade coating, roller coating, curtain coating, etc. can be used.

(3) Undercoat layer The undercoat layer (a) improves adhesion, (b) serves as a barrier against water or gas, (c) improves storage stability of the recording layer, and (d)
) improvement of reflectance, (e) protection of the substrate from solvents, (f)
Used for purposes such as forming pre-grooves. (a
), various polymer materials such as ionomer resins, polyamide resins, vinyl resins, natural resins, natural polymers, silicones, liquid rubbers, and silane coupling agents can be used. ,(b)
For the purpose of (C), inorganic compounds such as Sin□, M gF 2, Sin, T
iO2, ZnO, TjN, SiN, etc., metals or metalloids such as Zn, Cu, S, Ni, Cr, Ge
, Se, Au, Ag, AQ, etc. can be used. Also, for the purpose of (d) metals, e.g.
, Ag, etc., organic thin films with metallic luster, such as methine dyes, xanthine dyes, etc., can be used (e
) and (f), ultraviolet curing resins, thermosetting resins, thermoplastic resins, etc. can be used.

(4) Protective layer The protective layer is used for the purposes of (a) protecting the recording layer from scratches, dust, dirt, etc., (b) improving storage stability of the recording layer, and (c) improving reflectance. be done. For these purposes, the materials listed above for the undercoat layer can be used.

In the present invention, the undercoat layer and the protective layer may contain stabilizers, dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers, etc., as in the case of the recording layer. . Furthermore, the undercoat layer and the protective layer can also contain a polymethine compound.

In the present invention, at least one compound selected from the general formulas (I) and (n) is used to improve the light resistance of the polymethine compound. The polymethine compound and the above compounds are used in a weight ratio of 30:0 to 99:1, preferably 60:40 to 95:5.6 Next, specific examples of preferred compounds for use in the present invention will be shown.

Table 1 Table 2 [Effects] The optical information recording medium of the present invention configured as described above is capable of recording and reproducing using long wavelength light such as a semiconductor laser, and has improved thermal stability and optical stability. It has excellent storage stability and little deterioration during reproduction. Furthermore, pits can be formed in a good shape and a high C ratio can be obtained.

〔Example〕

The present invention will be further explained below with reference to Examples, but the present invention is not limited to these Examples.

(Example 1) Polymethyl methacrylate (PMMA) with a thickness of 1.2 cm
On a plate (diameter 130 mm), the following compound (1) and the compound Nα2 were mixed at 85:15 on a substrate (diameter 130 mm) on which a helical group with a depth of 2000 people and a half value of 40.4/1 m was provided using an acrylic photopolymer. A 1,2-dichloroethane solution was coated with a spinner at a weight ratio of 1,2-dichloroethane to form a recording layer having a thickness of 700 mm, thereby obtaining a recording medium.

H3CH3 (Examples 2 to 3) In Example 1, a recording medium was obtained using the compound Nα5 and the compound Nα20 instead of the compound Nα2.

(Example 4) In Example 1, a recording medium was obtained using the following compound (II) instead of the above compound (I).

II CI(, C13 (Example 5) In Example 1, a recording medium was obtained by using the above compound (II) instead of the above compound (1) and using the above compound Nα15 instead of the above compound Nα2.

(Examples 6 to 7) In Example 1, a recording medium was obtained by using the following compound (III) instead of the above compound (I), and using the above compound Nα10 and the above compound Nα20 instead of the above compound Nα2.

=11- (Examples 8 to 9) In Example 1, the following compound (IV) was used instead of the above compound (1), and the above compound N[12 was replaced with the above compound Nα5 and the above compound Nα5 and the above compound Nn25 were used. Got the medium.

(Comparative Example 1) A recording medium was obtained using the same method as in Example 1 except that the recording layer contained only the polymethine dye.

(Comparative Example 2) A recording medium was obtained in Example 6 using a recording layer containing only a polymethine dye.

(Comparative Example 3) A recording medium was obtained in Example 8 using a recording layer containing only a polymethine dye.

Information was written and reproduced on each recording medium obtained as described above using a semiconductor laser beam with a wavelength of 790 nm from the substrate side at a recording frequency of 5 MHz and a linear velocity of 2.1 m/see, and a spectrum analysis of the reproduced waveform (scanning filter, Bandwidth 30K)lz) was performed to measure the reflectance and C/N ratio. Furthermore, this same recording medium was irradiated with 1K111 tungsten light from a distance of 30 ang for 15 hours to perform an accelerated reproduction deterioration test, and then the reflectance and C ratio were measured. In this case, the reflectance was measured from the substrate side.

The above measurement results are shown in the table below.

Table-3

Claims (1)

[Claims] (1) In an optical information recording medium, a recording layer containing an organic dye containing a polymethine compound as a main component is provided on a substrate directly or via an undercoat layer, and further a protective layer is provided as necessary. An optical information recording medium, characterized in that at least one of the recording layer and the protective layer contains at least one compound selected from the following general formulas (I) and (II). General formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ General formula (II): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the above formula, R_1 to R_8 are substituted or unsubstituted alkyl groups or alkoxy group or hydrogen, X represents an acid anion)