JPH0199885A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To improve the heat and light stabilities and reduce be deterioration in reproduction of be title medium, by forming on a support a recording layer containing a polymethylene compound and a light stabilizer comprising a specified addition salt of an amine and having a thermal decomposition point of 160 deg.C or above. CONSTITUTION:An optical information recording medium is prepared by forming on a support directly or via an undercoat layer a recording layer containing an organic coloring matter comprising a polymethylene compound as the principal component and a light stabilizer comprising an addition salt of an amine compound of formula I or II, wherein R<1>-R<6> are each a lower alkyl group, and having a thermal decomposition point of 160 deg.C or above. The obtained medium makes possible recording and reproduction by means of a long- wavelength light of, e.g., a semiconductor laser and has improved heat and light stabilities. Furthermore it has an excellent preservability and reduced deterioration in reproduction.

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 derivative is provided on a substrate, but these have poor storage stability, low resolution, and low recording density. It has disadvantages such as low production conditions, difficult manufacturing conditions, and high costs. 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. Optical discs using such polymethine dyes in their recording layers have high light absorption and reflectance, and are therefore ranked as highly sensitive.

Although it is known that high-contrast recording characteristics can be obtained, it has the disadvantage that it has poor stability against light and is susceptible to film deterioration due to reproduction light (reproduction deterioration). As a means of improving this, attempts have been made to include a light stabilizer, and various light stabilizers have been developed, but none have been satisfactory.

〔the purpose〕

An object of the present invention is to provide an information recording medium containing a polymethine compound having excellent heat and light stability and improved reproduction deterioration.

〔composition〕

The above object is to contain a light stabilizer consisting of an addition salt of an amine compound represented by the following general formula (1) or (If) and having a thermal decomposition point of 160° C. or higher in the recording layer of an optical information recording medium. This is achieved by

General formula (I) N+Q-NR'tF)a General formula (n) (In the above formula, R1-R5 represent a lower alkyl group) The optical information recording medium of the present invention basically comprises a polymethine compound on a substrate. It is constructed by providing a recording layer made of an organic dye whose main component is, but if necessary, an undercoat layer can be provided between the substrate and the recording layer, or a protective layer can be provided on the recording layer.

Alternatively, the pair of recording media constructed in this way 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 a close-contact sandwich structure in which they are bonded via a protective layer may be used. (combined 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 The required characteristics of the substrate are that 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. 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, merocyanine dyes, croconium dyes, pyrylium dyes, etc., and specific examples thereof are described in, for example, JP-A-58-194595.

The recording layer of the recording medium of the present invention may contain other dyes, such as phthalocyanine dyes, tetrahydrocholine dyes, dioxazine dyes, and triphetchazine dyes, if necessary, in order to improve recording characteristics and stability.

Phenanthrene series, anthraquinone (indanthrene)
dyes, xanthine-based, triphenylmethane-based, triphenylamine-based, azulene-based dyes, metals or metal compounds,
For example, In, Sn, Te, Bi, A base, Ss
, TaO2, SnO, Ag, Cu, Cd, Zn
etc. may be dispersed in the recording layer, or may be laminated.

In addition to the above, polymer materials, storage stabilizers (metal complexes, phenolic compounds), dispersants, flame retardants, lubricants, plasticizers, etc. can be included. The thickness of the recording layer is 100 to 50
00 people, preferably 200-2000 people.

As a method for forming the recording layer, 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)
It is used for purposes such as forming pregrules. (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, MgF, Sin, Ti in addition to the above polymer materials
O2, Zn0%TiN, SiN, etc., metals or semimetals such as Zn, Cu, S, Ni, Cr, Ge,
Ss, Au, Ag, Am, etc. can be used. Further, for the purpose (d), metals such as 80, Ag, etc., and organic thin films 1 having metallic luster, such as methine dyes, xanthine dyes, etc., can be used.

For purposes (e) and (f), ultraviolet curing resins,
Thermosetting resin, thermoplastic resin, etc. can be used.

(4) Protective layer The protective layer (a) protects the recording layer from scratches, dust, dirt, etc.; (b) Improved storage stability of the recording layer.

(c) Used for the purpose of improving reflectance, etc. 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 a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, a plasticizer, etc., as in the case of the recording layer. . Furthermore, the undercoat layer and the protective layer can also contain a polymethine compound and/or a light stabilizer.

In the present invention, in order to improve the light resistance of the polymethine compound and prevent playback deterioration of the recording medium, an addition salt of an amine compound represented by the general formula (I) or (II) is used, and the thermal decomposition point is 160°C or higher. Use certain light stabilizers.

Conventionally, various kinds of photostabilizers have been proposed for polymethine compounds, but the research conducted by the present inventors has shown that there are some that have good photostabilizing functions for polymethine compounds.
It has been confirmed that the relationship that the reproduction deterioration in an actual optical disk device can be reduced as it is does not hold. Therefore, in order to solve the problem of playback deterioration in optical disk devices, it is not enough to simply improve the optical stability; it is necessary to identify and overcome other causes.

Deterioration of the data recording area of an optical disk is caused by the step (1) of irradiating a high-energy beam necessary to form pits and recording them as concave portions, and the step (1) of irradiating a low-energy beam that does not deform the recording layer to reduce the amount of reflected light. This occurs in both stages of reading out the record (If) due to brightness and darkness. According to the research conducted by the present inventors, at the reproduction light power (0.3 mw or less) normally used for polymethine-based recording materials, the optical stabilization function of the optical stabilizer and the reproduction deterioration of the unrecorded area of the recording material deteriorate. It was found that although there is a correlation with the recording material, there is no good correlation with the recording material of the recording section. That is, in the recording medium having the structure shown in FIG. 1, reproduction deterioration of the recording material 4 in the unrecorded area can be improved by using a material with excellent light stabilizing function as a light stabilizer. The regeneration deterioration of the material 3 varies greatly depending on the type of the light stabilizer, even if the light stabilizer has an excellent light stabilizing function. As a result of further investigation into the cause, the present inventors have clarified that the deterioration mechanism is as follows.

That is, when actually forming pits with a laser beam, the relationship between the light intensity distribution of the beam and the pit diameter is as shown in FIG. 2, where the beam irradiates the recording layer with a larger diameter than the pit system. Therefore, the recording material around the formed pits (shaded areas) is subjected to a history due to heat and light during recording. What is the reason why the reproduction deterioration characteristics of the actual recording section varied despite the strong optical stabilization function in the experiments conducted by the present inventors?

It was found from the results of compositional analysis around the pits that it depends on the degree of damage to the stabilizer during recording.

Figure 3 shows the relationship between the decomposition point temperature of the photostabilizer and the signal survival rate (illusion) at the land level of the recording section after 1 million cycles.As is clear from this graph, it is clear that the In this case, the reproduction deterioration of the recording material in the recording unit shows a correlation with the thermal decomposition temperature of the stabilizer, and it is found that the higher the thermal decomposition temperature of the stabilizer, the lower the reproduction deterioration. It can be seen that the problem of regeneration deterioration can be effectively solved by using a stabilizer at a temperature of 200° C. or higher, particularly 200° C. or higher.

The light stabilizer used in the present invention has the general formula (1) or (
It is an addition salt of an amine compound represented by U), and in this case, the addition salt includes hydrogen halide, perchloric acid, tetrafluoroboric acid, fluorinated antimonic acid, hexafluorophosphoric acid, alkyl sulfuric acid, alkylbenzene. Examples include those formed by reaction with various acids such as sulfonic acid.

The proportion of the light stabilizer used in the present invention is 2 to 60 parts by weight, preferably 5 to 60 parts by weight, based on 100 parts by weight of the polymethine compound.
In the present invention, the polymethine compound has a thermal decomposition point of 160°C or higher, preferably 200°C or higher.
It is preferable to use a temperature higher than ℃.

〔effect〕

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, has improved thermal stability and optical stability, and has excellent storage stability and playability. It has little deterioration.

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

Example 1 100 mg of the following polymethine compound (1), 15 mg of the light stabilizer (1) below, and 10 g of methanol were placed on an injection polycarbonate substrate with a guide groove pitch of 1.6 μm, a recording section guide groove depth of 900 people, and a diameter of 130 m. and 1,
A recording layer having a thickness of 700 mm was formed by dissolving the mixture in a mixed solvent containing 2 g of 2-diglolethane and coating with a spinner to obtain a recording medium.

Dye (■): Light stabilizer (■): Example 2 In Example 1, the following compound (II) was used as a light stabilizer.
) A recording medium was obtained in the same manner except that the following was used.

Light stabilizer (■): In Example 1, the following compound (m) was used as a light stabilizer.
A recording medium was obtained in the same manner except that .

Light stabilizer (■): Example 4 In Example 1, the following compound (mV
) A recording medium was obtained in the same manner except that the following was used.

Light stabilizer (■): Comparative example 1 In Example 1, the following compound (V) was used as a light stabilizer.
A recording medium was obtained in the same manner except that .

Light stabilizer (V) Winter◎-N(Et), ), SbF,.

Comparative Example 2 In Example 1, the following compound (■) was used as a light stabilizer.
A recording medium was obtained in the same manner except that .

Light stabilizer (VI) Ki◎-N (BIJ),).

CaO2 Next, each recording medium obtained as described above was heated at a linear velocity of 2.1
m/sac, reproduction light intensity 0.3w+w, beam diameter 1.6
The same address was reproduced 1 million times under pm conditions, and the ratio of the signal strength before and after reproduction was taken as the signal strength residual rate.

The measurement results are shown in Table-1.

[Brief explanation of the drawing]

Figure 1 is an explanatory plan view of the recording medium, Figure 2 is an explanatory diagram showing the relationship between the pit diameter and the beam intensity distribution when pits are formed in the recording layer, and Figure 3 is the thermal decomposition of the light stabilizer. point and lO
It shows the signal survival rate (%) at the recording section land level after 00,000 times. 1...Guide groove, 2...Recording pit, 3...Recording part recording material, 4...Recording part recording material, Patent applicant Rico Co., Ltd. Attorney Toshiaki Ikeura (and 1 others) Name) Figure 1 Now Figure 2 Figure 3 Figure 9 J's p-scream 1 degree (0C)

Claims (1)

[Claims] (1) In an optical information recording medium, in which 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 a protective layer is further provided as necessary, in the recording layer. An optical information recording medium characterized in that the optical information recording medium contains a light stabilizer which is made of an addition salt of an amine compound represented by the following general formula (I) or (II) and has a thermal decomposition point of 160° C. or higher. 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^6 represent lower alkyl groups)