JPH0822612B2 - Optical information recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improved optical information recording medium that can be used in the optical recording field.

[Prior art]

Recently, A as a recording layer in an optical information recording medium
It has been proposed to use an organic dye thin film instead of a metal thin film such as l or Te.

The advantage of the organic dye thin film is that the melting point and decomposition temperature are low and the thermal conductivity is low, so there is a possibility of high sensitivity and high density, and since film formation is possible by coating, mass productivity is high, Cost reduction can be expected, and when plastic materials are used for the substrate, thermal expansion, water permeability, and other physical and chemical characteristics are similar, which may reduce cracking of the recording film and warp deformation of the substrate. There is such a thing.

However, when an organic dye thin film is formed on a plastic substrate by a coating method, a highly soluble solvent such as acetone or dichloroethane is often used in the plastic substrate, so that there is a problem that even the plastic substrate is dissolved during coating. It was If the plastic substrate is dissolved even during coating, the reflectance of the dye film does not increase, and the advantages of the organic dye thin film described above are impaired. Therefore, in order to overcome the above problems, it is possible to apply a substrate using a solvent that does not dissolve,
A pigment material having excellent storage stability suitable for application has not yet been found. Further, it has been proposed to provide a recording layer after providing an undercoat layer such as a photopolymer layer on the substrate, but there is a problem that the number of steps for providing the undercoat layer increases, resulting in higher cost and lower productivity. is there.

In addition, currently commercially available injection molded plastic substrates for optical discs have poor solvent resistance and the only solvents that do not affect the substrates are water and alcohol. Further, since the optical recording medium is severely required to have environmental resistance (including resistance to temperature and humidity), the recording material must be insoluble in water. From this point of view, in order to form a recording film on an injection-molded substrate that contributes to cost reduction by coating, it has high solubility in an alcohol solvent, water resistance and storage stability (light resistance, light resistance,
It has been necessary to develop recording materials with excellent heat resistance.

〔Purpose〕

Therefore, an object of the present invention is to provide an optical information recording medium which has a high C / N, excellent storability, little reproduction deterioration, and can be manufactured at low cost.

Another object of the present invention is to provide a dye compound soluble in a weak solvent (for example, water, an alcohol solvent, or a mixed solvent thereof) which does not dissolve the plastic substrate.

〔Constitution〕

In view of the above-mentioned drawbacks of the prior art, the present inventor has conducted various studies on many dye compounds, and as a result, selected an indole-based cyanine dye from polymethine-based dyes and further selected a substituent bonded to the N atom of the indole ring. The inventors have found that the stability of the cyanine dye to light and heat can be further improved by making the kinds of the substituents bonded to the N atom of the indolenine ring different from each other, and the present invention has been completed.

The above object of the present invention is to provide a plastic substrate and the following formula (I):
And an optical information recording medium comprising a recording layer containing at least one of the compounds represented by (II).

 Where R₁, R₂, R₃And R_FourAre the same or different
May be alkyl group, alkenyl group, alcohol
Represents an oxy group or an aralkyl group, these groups being substituted
May be R_FiveIs a substituted or unsubstituted C₁~ C₃Represents an alkyl group, R₆Is a substituted or unsubstituted C₃~ C₁₈Alkyl group,-(C
H₂)_a−OCOR or − (CH₂)_a-OR (R is C₁~ C₃Al
Represents a kill group and a is 1-5)
Dashi R_FiveIs C₃R for alkyl₆Is C₃Not alkyl
Yes, R₇Is hydrogen, alkyl group, alkenyl group, alkoxy
Group, hydroxyl group, halogen, substituted or unsubstituted amino group,
Represents an alkanoyloxy group or an aralkyl group, Z is a substituted or unsubstituted 4- to 8-membered ring, preferably 5-membered
Represents the group of atoms required to form a ring or 6-membered ring
And each said member ring may be condensed with an aromatic ring, A is CH = CH_lOrAnd B isOr CH = CH_mCH =, where m and l
Represents 0 or 1 to 3) n represents or 3, and X represents an acid anion. A preferred example of X is I
, Br , Cl , ClO_Four , BF_Four , SbF₆ Give
be able to.

In the above general formulas (I) and (II) Represents the residue of the indole ring and Indicates the residue of the indolenine ring, both of which are tautomers. The benzene nucleus of the indole ring and the indolenine ring may be substituted with one or more groups selected from an alkyl group, an alkenyl group, an alkoxy group, a halogen or an aralkyl group, or one or more groups. The benzene rings of may be fused to form, for example, benzoindole or naphthindole.

Also, in the above general formula The dotted line indicates that a single bond or a double bond is formed depending on A bound thereto. For example, if A takes -CH =, On the other hand, if A takes -CH = CH-, it means It shows that it becomes.

According to the present invention, the recording layer has the above general formulas (I) and (II)
And at least one of the compounds represented by
These compounds are characterized by the substituents attached to the N atoms of the indole and indolenine rings. That is,
The substituents R ₅ and R ₆ are different from each other. R ₅ represents a substituted or unsubstituted C _{1 to} C ₃ alkyl group, R ₆ represents a substituted or unsubstituted C _{3 to} C ₁₈ alkyl group, — (CH ₂ ) _a —OCOR or —
It represents a _{(CH 2) a -OR (R} = C 1 ~C 3 alkyl, a = 1~5). It is considered that such characteristics of the dye compound according to the present invention give high solubility in alcoholic solvents, excellent storage stability (light resistance, heat resistance) and the like.

Typical examples of the dye compound according to the present invention are shown below with general formulas, but the present invention is not limited thereto.

The recording layer in the present invention has the above general formulas (I) and (I
It has at least one of the dye compounds represented by I) as a main component. The dye compound may be contained in a proportion of 50 to 100% by weight, preferably 70 to 98% by weight, based on the total solid content of the recording layer. Further, other dyes and stabilizers may be contained in order to improve recording characteristics and stability. Examples of other dyes include phthalocyanine-based, tetrahydrocholine-based, dioxazine-based, triphenothiazine-based, phenanthrene-based, polymethine (cyanine, merocyanine) -based, anthraquinone (indanthrene) -based, xanthene-based, triphenylmeta-based, Examples include croconium-based, azulene-based, pyrylium-based, squarylium-based, and naphthoquinone-based dyes.

Any stabilizer can be used, but the metal complex aminium salt and triphenylamine have a particularly large improvement in stability and light resistance and good compatibility with the above-mentioned compounds of the present invention. Compounds are preferred. Examples of metal complexes include acetylacetonato chelate systems containing Ni, Co, Cu, Mn, etc. as central metals, bisdithio-α-diketone systems, and bisphenols as disclosed in JP-A-59-55795. Examples thereof include an enyldithiol system, a salicylaldehyde oxime system, and a thiobisphenolate chelate system. Among these, a bisdithio-α-diketone system and a bisphenyldithiol system are particularly preferable. Examples of aminium salts are described in Japanese Patent Application No. 59-18222 (filed on February 6, 59) and Japanese Patent Application No. 59-91922 (filed on May 10, 59) relating to the present applicant. As mentioned above, compounds represented by the following general formula can be given.

However, R represents hydrogen or a lower alkyl group, and X
Represents an acid anion, m is 0, 1 or 2, and A
Is (N is 1 or 2) or (Where m is 2) and all aromatic nuclei present may be substituted by lower alkyl, lower alkoxy, halogen or hydrogen.

Further, examples of triphenylamine compounds include compounds represented by the following general formula as described in the specification of Japanese Patent Application No. 60-24297 (filed on October 31, 60) filed by the present applicant. You can

Where A represents phenyl, cyclohexylamino, dibenzylamino or dialkylamino having a C ₁ -C ₄ alkyl group, B is the same as A or represents a hydrogen atom, X represents an acid anion and the above formula All aromatic nuclei present therein may be substituted by lower alkyl, lower alkoxy, lower alkylthio, halogen or hydroxyl.

The stabilizer is usually contained in an amount of 0.02 to 1 mol, preferably 0.05 to 0.3 mol, per 1 mol of the compound of the above formula (I) or (II) of the present invention. Further, other additives such as a binder, a dispersant, a flame retardant, a lubricant, an antistatic agent and a plasticizer may be added to the recording layer.

The recording layer can be formed by coating. The thickness of the coating film is 100 to 5000Å, preferably 200 to 2000Å. If the film thickness is less than 100Å, absorption is too small to record.
If it exceeds 000Å, the recording sensitivity will decrease and the noise will increase.

The coating is performed by deep coating, spray coating, blade coating, spin coating, roller coating, curtain coating and the like. As the coating solvent, a weak solvent that does not dissolve the plastic substrate can be used.
Therefore, in the present invention, it is possible to save the trouble of insolubilizing the substrate (for example, installing an undercoat layer, irradiating electromagnetic rays, etc.). This does not mean eliminating the undercoat layer. As the weak solvent, water or an alcohol solvent such as methanol or ethanol, or a mixed solvent of an alcohol solvent and another solvent such as methanol / acetone can be used. When using a mixed solvent, other solvents up to 50%, preferably 30%, relative to the alcohol solvent
It is appropriate to mix up to.

The plastic substrate on which the recording layer is applied is preferably formed by injection molding from the viewpoint of productivity and cost, and should be transparent to the laser light used only when recording / reproducing is performed from the substrate side. Representative examples thereof include acrylic resins such as polymethylmethacrylate (PMMA), polycarbonate, polymethylpentene, etc., but are not limited thereto. A pre-group of address signals or the like and a pre-group of guide grooves may be formed on the surface of the substrate. In addition, the shape of the substrate is tape, disk, drum,
It may be any such as a belt.

The optical recording medium of the present invention basically comprises a substrate and a recording layer, but a protective layer may be provided on the recording layer according to the purpose. The thickness of the protective layer is 0.1 to 30 μm, preferably 0.2 to 10 μm. Scratches on the recording layer, dust,
Vinyl resin for protection from dirt,
Polymer materials such as polyamide resins, natural rubber, ionomer resins, inorganic compounds such as SiO ₂ , MgF ₂ , SiO, Ti
O _2, ZnO, TiN, SiN, etc., metal or metalloid example Zn, C
u, S, Ni, Cr, Ge, Se, Al, Ag or the like can be used. Further, for the purpose of improving the reflectance, the above-mentioned metal or metalloid or an organic thin film having a metallic luster such as a methine dye or a xanthene dye can be used.

Further, the recording layer in the present invention may be provided on one side or both sides on the substrate, and further, a so-called air-sun-gerty structure in which the recording medium is paired and sealed with a space so that the recording layers are on the inside is a dust. You can also prevent scratches. Further, in the Saint-Gerache structure, a laminated structure may be used in which the material used for the substrate is adhered as a protective plate on the opposite side of the recording layer.

When the optical information recording medium of the present invention is used for recording / reproducing information, the recording of information is performed by a physical shape change (pit formation) caused by the interaction between the recording layer and the light or heat by irradiation of the writing laser beam. To be done. On the other hand, reproduction of information is performed by sensing the reflectance of the recording layer by irradiating a reading laser beam.

In addition, the wavelength for recording or reading light is 750 to 850 nm.
The semiconductor laser or the like can be used.

〔effect〕

According to the present invention, it is possible to obtain a recording medium that has less reproduction deterioration than conventional recording materials and has excellent storage stability.
Further, the recording layer can be formed directly on the injection-molded plastic substrate by the coating method, and the manufacturing cost can be greatly reduced.

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

〔Example〕

Example 1 Groove area 92 mmφ to 187 mmφ, groove depth 900 Å, half-value width 0.
Injection-molded polymethylmethacrylate substrate with a groove of 4μm and pitch of 1.6μm (thickness 1.2mm, inner diameter 3
A solution of 1% by weight of the above-exemplified compound (1) in methanol was applied onto a 5 mmφ and an outer diameter of 200 mmφ by spinner coating to form a recording layer having a film thickness of about 550 Å to prepare a recording medium.

Example 2 A recording medium was prepared in the same manner as in Example 1 except that the exemplified compound (3) was used as the dye compound.

Example 3 A recording medium was produced in the same manner as in Example 1 except that the exemplified compound (5) described above was used as the dye compound.

Example 4 A recording medium was prepared in the same manner as in Example 1 except that the exemplified compound (18) was used as the dye compound.

Example 5 A recording medium was prepared in the same manner as in Example 1 except that the exemplified compound (24) was used as the dye compound.

Example 6 A recording medium was produced in the same manner as in Example 1 except that a mixture of the exemplified compound (1) above and the exemplified compound (28) in a weight ratio of 7: 3 was used as the dye compound.

Example 7 A recording medium was prepared in the same manner as in Example 1 except that 7.5% by weight of the nickel complex represented by the following general formula was added to the compound (1) of Example 1.

Example 8 A recording medium was produced in the same manner as in Example 7 except that the compound of the following general formula was used instead of the nickel complex in Example 7.

Example 9 Groove area 92 mmφ to 187 mmφ, groove depth 900Å, half-value width 0.
Injection molded polycarbonate substrate with a groove of 4 μm and pitch of 1.6 μm (thickness 1.2 mm, inner diameter 35 mmφ,
An outer diameter of 200 mmφ) was spin-coated with a solution prepared by dissolving 1% by weight of the exemplified compound (11) in a mixed solvent of methanol / 1,2-dichloroethane (weight ratio 85/15) to form a recording layer having a thickness of about 550 Å. Then, a recording medium was prepared.

Example 10 Methanol / acetone (85/15 weight ratio) 1 of the above-exemplified compound (37) on the same polycarbonate substrate as in Example 9
A recording medium having a thickness of 550 Å was formed by spin-coating a solution of the weight% solution.

Example 11 A recording medium was prepared in the same manner as in Example 10 except that the exemplified compound (40) was used as the dye compound.

Example 12 A recording medium was produced in the same manner as in Example 10 except that the exemplified compound (43) was used as the dye compound.

Example 13 A recording medium was prepared in the same manner as in Example 10 except that the exemplified compound (50) was used as the dye compound.

Example 14 A recording medium was prepared in the same manner as in Example 10 except that the same polymethylmethacrylate (PMMA) substrate as in Example 1 was used as the substrate and the exemplified compound (36) was used as the dye compound.

Example 15 A recording medium was produced in the same manner as in Example 10 except that 5% of the following nickel complex was added to the exemplified compound (37).

Example 16 A recording medium was produced in the same manner as in Example 10 except that the following aminium salt was added to the exemplified compound (37) in an amount of 10%.

Example 17 A recording medium was prepared in the same manner as in Example 11 except that 10% of the following triphenylamine compound was added to the exemplified compound (40).

Example 18 A recording medium was prepared in the same manner as in Example 10 except that the exemplified compound (45) was used as the dye compound.

Example 19 A recording medium was prepared in the same manner as in Example 18 except that 10% of the triphenylamine compound used in Example 17 was added.

Example 20 A recording medium was prepared in the same manner as in Example 10 except that a 1: 1 mixture of the exemplified compound (37) and the exemplified compound (45) was used as the dye compound.

Example 21 A recording medium was produced in the same manner as in Example 20 except that 15% of the same nickel complex as in Example 15 was added.

Example 22 A recording layer having a film thickness of about 550Å was formed by applying a solution prepared by dissolving 1% by weight of the exemplified compound (1) in methanol / methylcellosolve (85/15 weight ratio) on the same polycarbonate substrate as in Example 9 by a spinner. To form a recording medium.

Example 23 A recording medium was prepared in the same manner as in Example 22 except that the exemplified compound (2) was used as the dye compound.

Example 24 A recording medium was prepared in the same manner as in Example 22 except that the exemplified compound (8) was used as the dye compound.

Example 25 A recording medium was prepared in the same manner as in Example 22 except that the exemplified compound (9) was used as the dye compound.

Example 26 A recording medium was produced in the same manner as in Example 22 except that the exemplified compound (11) was used as the dye compound.

Example 27 A recording medium was prepared in the same manner as in Example 22 except that the exemplified compound (15) was used as the dye compound.

Example 28 In Example 22, polymethylmethacrylate was used as the substrate and the above exemplified compound (10) was added to methanol / 1,2.
A recording medium was prepared using a solution dissolved in dichloroethane (90/10 weight ratio).

Example 29 A recording medium was prepared by using a solution prepared by adding 5% of the following nickel complex to the exemplified compound (2) described in Example 23.

Example 30 A recording medium was prepared using a solution prepared by adding 10% of the following aminium salt to the exemplified compound (2) in Example 23.

Example 31 A recording medium was prepared using a solution prepared by adding 10% of the following triphenylamine compound to the exemplified compound (2) in Example 23.

Example 32 A carbon tetrachloride solution (5%) of ethylene-vinyl acetate copolymer (EV-150) was formed on the recording layer formed in Example 9 to a thickness of
A protective layer coated at 0.5 μm was provided.

Example 33 On the same substrate as in Example 9, 1% by weight of the exemplified compound (11) / polyvinyl butyral resin (BT-60 Hoechst) (8/12 weight ratio) was added to methanol / 1,2-dichloroethane (85 A solution dissolved in a mixed solvent (/ 15 weight ratio) was applied by a spinner to form a recording layer having a thickness of 600Å to prepare a recording medium.

Example 34 A recording medium was prepared in the same manner as in Example 9 except that the exemplified compound (55) was used instead of the exemplified compound (11).

Example 35 A recording medium was prepared in the same manner as in Example 9 except that the exemplified compound (61) was used instead of the exemplified compound (11).

Example 36 A recording medium was prepared using a solution obtained by adding 10% of the aminium salt used in Example 16 to the compound (55) used in Example 34.

Comparative Example 1 In the above general formula, R is CH ₃ , C ₂ H ₅ or C ₃ H, respectively.
_It was attempted to dissolve each compound of ₇ in methanol, but the solubility was poor and a coating solution could not be formed.

Comparative example 2 In the above general formula, each compound in which R represents CH ₃ or C ₂ H ₅ was tried to be dissolved in methanol, but it was extremely insoluble and a coating solution could not be formed.

Comparative Example 3 In Comparative Example 2, when a solvent system (methanol / 1,2-dichloroethane 30/70 weight ratio) having a solubility high enough to form a coating solution was used, the substrate was dissolved and the groove was completely disappeared.

Comparative Example 4 In the above general formula, 1% by weight of each compound in which R represents CH ₃ or C ₂ H ₅ is added to methanol / acetone (85/1
However, the recording layer could not be formed because it was insoluble in the solvent.

Comparative Example 5 A recording medium was prepared in the same manner as in Example 1 except that the following compounds were used as the dye compound.

Comparative Example 6 A recording medium was prepared in the same manner as in Example 1 except that the following compounds were used as the dye compound.

Comparative Example 7 Example except that the following compounds were used as dye compounds
A recording medium was formed in the same manner as 10.

Comparative Example 8 A recording medium was produced in the same manner as in Example 1 except that the following compounds were used as the dye compound.

Comparative Example 9 A recording medium was produced in the same manner as in Example 1 except that the following compounds were used as the dye compound.

Comparative Example 10 A recording medium was prepared in the same manner as in Comparative Example 9 except that the aminium salt used in Example 30 was added to the compound used in Comparative Example 9.

The recording characteristics and storability were measured for each of the recording media prepared in Examples 1 to 36 and Comparative Examples 1 to 10. Recording was performed using a semiconductor laser with a wavelength of 790 nm, a beam diameter of 1.6 μm, and a linear velocity of 1.
Recording was performed at 5 m / sec and a recording power of 2.7 mW, and a 0.7 MHz signal was recorded. Reproduction was performed using the same laser. The reflectance and C / N ratio were measured. The C / N ratio was obtained by spectral analysis of reflected light (scanning filter 30 KHz). The reflectance was measured from the substrate side.

Next, place the same recording medium in a constant temperature and humidity chamber at 60 ° C and 90% RH.
The reflectance and C / N were measured after storage for 1000 hours and an accelerated storage test. Further, another recording medium was irradiated with 1 K.W. of tungsten light from a distance of 20 cm for 12 hours to perform a reproduction deterioration acceleration test, and then the reflectance and C / N were measured. The results are summarized in the table below.

Claims (1)

[Claims] 1. An optical information recording medium comprising a plastic substrate and a recording layer containing at least one of the compounds represented by the following formulas (I) and (II). In the formula, R ₁ , R ₂ , R ₃ and R ₄ may be the same or different and each represents an alkyl group, an alkenyl group, an alkoxy group or an aralkyl group, and these groups may be substituted. , R ₅ represents a C ₁ -C ₃ alkyl group or a substituted or unsubstituted, R ₆ is a substituted or unsubstituted C ₃ -C ₁₈ alkyl group, - (CH _2)
a -OCOR or - represents (CH _{2) a} -OR (R is and a represents C ₁ -C ₃ alkyl group from 1 to 5), except
When R ₅ is C ₃ alkyl, R ₆ is not C ₃ alkyl, R ₇ is hydrogen, an alkyl group, an alkenyl group, an alkoxy group,
Represents a hydroxyl group, a halogen, a substituted or unsubstituted amino group, an alkanoyloxy group or an aralkyl group, Z represents an atomic group necessary for forming a substituted or unsubstituted 4 to 8 membered ring, and each membered ring is Optionally fused to an aromatic ring, A is CH = CH ₁ or And B is Or CH = CH _m CH =, where m and l
Represents 0 or 1 to 3) n represents 2 or 3, X represents an acid anion, and the benzene nucleus of the indole ring and the indolenine ring is an alkyl group, an alkenyl group, an alkoxy group, a halogen or an aralkyl group. It may be substituted by one or more selected groups or one or more benzene rings may be fused.