JP3169271B2 - Information recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writable information recording medium, and more particularly to an information recording medium having a recording layer and a light reflection layer on a light transmitting substrate.

[0002]

2. Description of the Related Art It is generally well known that organic dyes such as cyanine and phthalocyanine are used in a recording layer of a writable information recording medium.

[0003] As a writing method for such an information recording medium, a laser beam is focused on a very small area of a recording layer, converted into heat energy, and changed in properties of the recording layer (pit formation). It is carried out. In order to smoothly change the properties of the recording layer, the medium may have a so-called air sandwich structure in which two recording layers are provided on a substrate and the recording layers are arranged to face each other. General.

A writing laser beam used in such a type of information recording medium is irradiated from the transparent substrate side to form optically readable pits in the recording layer. The read laser beam for reproducing the recorded data has a lower output than the write laser beam, and the contrast between the portion where the pit is formed and the other portion is read as an electric signal.

On the other hand, unlike the above-mentioned medium, a so-called ROM (read only memory) on which data is already recorded in advance.
There are also y) type media, which are widely used in the fields of audio recording and information processing. However, this does not have a writable recording layer as described above. That is, prepits corresponding to data to be reproduced are already formed on a plastic substrate by injection molding, and a reflective layer made of a metal such as Au, Ag, Cu, or Al is formed thereon, and further protected on this. A layer is formed. A typical medium of this ROM type is a compact disk called a so-called CD. The specifications of the recording and reading signals of the CD are standardized, and a CD reproducing apparatus is widely used as a compact disk player (CD player) according to the standard.

The writable information recording medium is similar to a CD in that a laser beam is used, and the medium is also similar to a CD in that the medium has a disk shape. Therefore, there has been a strong demand for the development of a writable medium that can be used as it is in a CD player, conforming to the CD specification standard, and actual samples have begun to be presented to meet this demand.

The organic dye contained as a main component in the recording layer of such a writable information recording medium cannot be said to have sufficient light resistance, and has an effect of preventing fading as one means for improving the light resistance. Nitroso compounds have been used.

[0008]

However, such nitroso compounds are generally toxic and require careful selection. In addition, there are problems such as the appearance of a large number of toxic by-products during the synthesis of this compound. Therefore, a substance that can be substituted for this compound, that is, it is non-toxic, has excellent safety, is easy to synthesize, and has no discoloration prevention. There is a strong demand for a medium having a recording layer provided with a substance having an excellent effect.

The present invention has been made in view of such circumstances, and an object of the present invention is to solve the above-mentioned problems and to provide a writable information recording medium excellent in safety and light resistance. is there.

[0010]

According to the present invention, there is provided an information recording medium having a recording layer on a substrate and a light reflecting layer on the recording layer.
It is configured to contain at least one cyanine dye selected from cyanine dyes represented by the following general formulas [I] and [II] and a diphenylamine-based compound represented by the following general formula [III]. .

Hereinafter, the specific structure of the present invention will be described in more detail with reference to FIGS. FIG. 1 is a schematic perspective view of the information recording medium of the present invention, with a portion cut away.

In the information recording medium 1 of the present invention, a recording layer 12 is provided on a light-transmitting substrate 11, a light reflecting layer 13 is provided on the recording layer 12, and a light reflecting layer 13 is provided. A protective layer 14 is provided on the substrate.

The recording layer 12 formed on the substrate 11 contains at least one cyanine dye selected from the cyanine dyes represented by the following general formulas [I] and [II].

[0014]

Embedded image In the general formula [I], R ₁ and R ₂ each represent an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 3 to 5 carbon atoms. When the number of carbon atoms exceeds 8, waxing occurs, and handling becomes inconvenient.

[0015] X ^- represents a counter ion, ClO ₄ specifically ^-, I ^-, Br ^-, and the like.

[0016]

Embedded image In the general formula [II], R ₃ and R ₄ each represent an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 3 to 5 carbon atoms. When the number of carbon atoms exceeds 8, the same disadvantages as in the case of the above general formula [I] occur. X ^- represents a counter ion, it has the same meaning as above.

The cyanine dyes represented by the general formulas [I] and [II] may be used alone, but usually, the cyanine dyes represented by the formula [I] and the cyanine dyes represented by the formula [II] It is preferable to use a mixture of dyes. This is to ensure high reflectivity, recording sensitivity, and the degree of modulation of the recorded signal. When mixed, the ratio is 100 to 300 parts by weight of the cyanine dye of the general formula [II] with respect to 100 parts by weight of the cyanine dye of the general formula [I].

Further, in the recording layer 12, in order to prevent the photodegradation (fading) of the cyanine dye, the following general formula [II]
I] is contained.

[0019]

Embedded image In the formula [III], R _{5 to} R ₈ each represent hydrogen or carbon 1
-8, more preferably 1-3, substituted or unsubstituted alkyl groups. The substituents of R _{5 to} R ₈ may be the same or different.

As a specific example of the diphenylamine-based compound, a substance represented by the following structural formula [DP-1] (4,4'-
Bis (dimethylamino) diphenylamine is exemplified.

[0021]

Embedded image Such a diphenylamine-based compound is contained in an amount of 5 to 50 parts by weight, more preferably 20 to 25 parts by weight, based on 100 parts by weight of the cyanine dye. If this value exceeds 50 parts by weight, there is a disadvantage that the recording sensitivity is reduced, and if this value is less than 5 parts by weight, there is a disadvantage that the fading prevention effect is reduced.

Further, the recording layer 12 may contain a quencher, particularly a Ni complex represented by the following general formula [IV], in addition to the diphenylamine-based compound.

[0023]

Embedded image In the formula, R ₉ , R ₁₀ , R _11, and R ₁₂ each represent hydrogen or a substituent.

As the substituent, CH ₃ O—, CH ₃ OC
_{H 2 CH 2 O-, CH 3} COO -, (n-C 3 H 7) 2
_{N -, (C 2 H 5} ) 2 N-, Cl- , and the like.

As a specific example of such a quencher,
For example, those having the following structural formulas [Q-1] to [Q-4] can be mentioned. Among them, those having the structural formula [Q-1] are preferable.

[0026]

Embedded image

[0027]

Embedded image

[0028]

Embedded image

[0029]

Embedded image The recording layer 12 containing the cyanine dye and the diphenylamine-based compound is applied by a conventional means such as a spin coating method.

The thickness of the recording layer 12 to be applied is 30 to 9
00 nm, preferably 100 to 300 nm. If this value is less than 30 nm, the absorption is reduced, so that the sensitivity in the semiconductor laser wavelength range is reduced, and the signal cannot be recorded. In this case, if the value exceeds 900 nm, the dye becomes too thick and the absorption increases. However, there is a disadvantage that the reflectance is reduced.

As the solvent used for coating, various known solvents can be used, for example, diacetone alcohol,
Ethyl cellosolve, methyl cellosolve, isophorone, methanol, tetrafluoropropanol, and the like.

The substrate 1 on which such a recording layer 12 is coated
1 is usually in the form of a disk.
It is preferable to use a so-called integrally formed injection-molded resin substrate from the viewpoint of improving productivity. It is formed. In particular, it is preferable to use a polycarbonate resin (PC) having an average molecular weight of 32,000 to 40,000. Further, the substrate is not limited to an injection molded resin substrate formed integrally, but may be a substrate formed by a so-called 2P (photo-polymer) method. The thickness of such a substrate 11 is 1.0 to 1.5
mm.

The recording layer 12 applied on the substrate 11
On top of this, a light reflection layer 13 is provided. The light reflection layer 13 is made of a metal such as Au, Ag, Cu, or Al, and is formed by vacuum deposition, sputtering, ion plating, or the like. The thickness of the light reflection layer 13 is as follows.
It is about 0.02 to 2.0 μm.

On the light reflecting layer 13, usually, the light absorbing layer 1
A protective layer 14 is provided to protect the light reflecting layer 2 and the light reflecting layer 13. The protective layer 14 is generally formed by spin-coating an ultraviolet-curable resin and then irradiating with ultraviolet light to cure the coating. In addition, an epoxy resin, an acrylic resin, a silicone resin, a urethane resin, or the like is used as a material of the protective layer 14. The thickness of such a protective layer 14 is
Usually, it is about 0.1 to 100 μm.

An intermediate layer for protecting the substrate 11 from a solvent may be provided between the substrate 11 and the light absorbing layer 12. Further, an intermediate layer may be provided between the light absorption layer 12 and the light reflection layer 13 to increase the light absorption efficiency.

The wavelength of light used for recording and reproducing information in the case of the present invention is 780 to 830 μm.
It is about.

[0037]

Hereinafter, the present invention will be described in more detail with reference to specific examples. [Preparation of Sample 1 of the Present Invention] As the cyanine dye contained in the recording layer, the following two types of cyanine dyes [D
[-1] and [D-2] used the above [DP-1] (4,4'-bis (dimethylamino) diphenylamine) as a diphenylamine-based compound. The mixing ratio (parts by weight) of these components is [D-1]: [D-2]: [DP
-1] = 100: 180: 65.

Cyanine dye [D-1] In the above general formula [I], R ₁ and R ₂ are respectively nC ₄ H ₉ and X ⁻ is ClO ₄ ⁻ .

Cyanine dye [D-2] In the above general formula [II], R ₃ and R ₄ are respectively nC ₃ H ₇ and X ⁻ is I ⁻ .

Each of these dyes and diphenylamine-based compound was dissolved in a solvent (1000 parts by weight) of ethyl cellosolve, and this was dissolved in a solvent having a diameter of 120 mm and a thickness of 1.
It was applied on an acrylic substrate of 2 mm to a thickness of 120 nm.

[Preparation of Sample 2 of the Present Invention] Sample 2 of the present invention was prepared by further adding the above quencher [Q-1] to the composition of the recording layer used in Sample 1 of the present invention. The mixing ratio (parts by weight) is [D-1]: [D-
2]: [DP-1]: [Q-1] = 100: 180: 6
5:40.

[Preparation of Comparative Sample 1] Diphenylamine compound [DP-1] used in Sample 1 of the present invention.
With 2- (3,5-di-) represented by the following structural formula [C-1]
Bis (1,2,2,6,6-pentamethyl-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonate
4-piperidyl) compound. Otherwise, Comparative Sample 1 was prepared in the same manner as Sample 1 of the present invention.

[0043]

Embedded image [Preparation of Comparative Sample 2] The diphenylamine-based compound [DP-1] used in Sample 1 of the present invention was replaced with bis (2,2,6,6-tetramethyl-4-) represented by the following structural formula [C-2]. Piperidyl) sebacate compound. Otherwise, Comparative Sample 2 was prepared in the same manner as Sample 1 of the present invention.
Was prepared.

[0044]

Embedded image [Preparation of Comparative Sample 3] The diphenylamine-based compound [DP-1] used in Sample 1 of the present invention was changed to a compound represented by the following structural formula [C-3]. Otherwise, Comparative Sample 3 was prepared in the same manner as Sample 1 of the present invention.

[0045]

Embedded image [Preparation of Comparative Sample 4] The diphenylamine-based compound [DP-1] used in Sample 1 of the present invention was changed to a compound represented by the following structural formula [C-4]. Otherwise, Comparative Sample 4 was prepared in the same manner as Sample 1 of the present invention.

[0046]

Embedded image [Preparation of Comparative Sample 5] The diphenylamine compound [DP-1] used in Sample 1 of the present invention was changed to a compound represented by the following structural formula [C-5]. Otherwise, Comparative Sample 5 was prepared in the same manner as Sample 1 of the present invention.

[0047]

Embedded image [Preparation of Comparative Sample 6] The diphenylamine-based compound [DP-1] used in Sample 1 of the present invention was changed to a compound represented by the following structural formula [C-6]. Otherwise, Comparative Sample 6 was prepared in the same manner as Sample 1 of the present invention.

[0048]

Embedded image [Preparation of Comparative Sample 7] The diphenylamine-based compound [DP-1] used in Sample 1 of the present invention was changed to a compound represented by the following structural formula [C-7]. Otherwise, Comparative Sample 7 was prepared in the same manner as Sample 1 of the present invention.

[0049]

Embedded image [Preparation of Comparative Sample 8] The diphenylamine compound [DP-1] used in Sample 1 of the present invention was omitted. Except for this, Comparative Sample 8 was the same as Sample 1 of the present invention.
Was prepared.

[Preparation of Comparative Sample 9] The diphenylamine compound [DP-1] used in Sample 2 of the present invention described above.
Was removed. Except for this, Comparative Sample 9 was produced in the same manner as Sample 2 of the present invention.

The samples 1 and 2 of the present invention and the comparative samples 1 to 9 were subjected to a light resistance test in the following manner. [Light Resistance Test] A white fluorescent lamp (40 w) was continuously irradiated from a distance of 10 cm from the sample for 30 hours.

Thereafter, the sample was taken out, the transmittance was measured, and the value of fading rate (%) = (transmittance after 30 hours / initial transmittance) × 100 was measured. This value is set to 0
○ (very good) in the range of less than ７7%, Δ (slightly problematic) in the range of 7 to less than 10%, and × (impractical) in the range of 10% or more.

[0053]

[Table 1]

[0054]

The effects of the present invention are clear from the results shown in Table 1. That is, since the recording layer of the information recording medium of the present invention contains a diphenylamine-based compound, it has extremely excellent effects on light resistance and safety.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an information recording medium of the present invention with a part cut away.

FIG. 2 is a partially enlarged cross-sectional view of a notch in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Information recording medium 11 ... Substrate 12 ... Recording layer 13 ... Light reflection layer 14 ... Protective layer

──────────────────────────────────────────────────続 き Continuation of the front page (72) Fumio Matsui Inventor, Pioneer Research Institute, 6-1-1-1 Fujimi, Tsurugashima-shi, Saitama (56) References JP-A-1-99885 (JP, A) JP-A-Hei 4-185381 (JP, A) JP-A-4-146189 (JP, A) JP-A-64-47590 (JP, A) JP-A-3-232844 (JP, A) JP-A-5-85057 (JP, A A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/26 G11B 7/24 516 CAPLUS (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. An information recording medium having a recording layer on a substrate and a light reflecting layer on the recording layer, wherein the recording layer is a cyanine dye represented by the following general formulas [I] and [II]: An information recording medium comprising: at least one cyanine dye selected from the group consisting of: and a diphenylamine-based compound represented by the following general formula [III]. Embedded image In the formula [I], R ₁ and R ₂ each represent an alkyl group having 1 to 8 carbon atoms, and X ⁻ represents a counter ion. Embedded image In the formula [II], R ₃ and R ₄ each represent an alkyl group having 1 to 8 carbon atoms, and X ⁻ represents a counter ion. Embedded image In the formula [III], R _{5 to} R ₈ each represent hydrogen or carbon 1
Represents 8 substituted or unsubstituted alkyl group, R ₅ ~
The substituents of R ₈ may be the same or different. 2. The information recording medium according to claim 1, wherein the diphenylamine-based compound is contained in an amount of 5 to 50 parts by weight based on 100 parts by weight of the cyanine dye. 3. The information recording medium according to claim 1, wherein the recording layer further contains a quencher of a Ni complex.