JPS63178083A - Optical data recording medium - Google Patents

Abstract

PURPOSE:To enhance the stability of a recording membrane using an org. dye, by forming the recording membrane by mixing a high-molecular dye obtained by subjecting an org. dye and a polymerizable substance to random copolymerization or graft copolymerization with a single dye. CONSTITUTION:An org. dye membrane is used in a recording membrane. The recording membrane is formed by mixing a high-molecular dye, which is obtained by subjecting an org. dye and a polymerizable substance to random or graft copolymerization, with a single dye. That is, at first, a dye molecule having a chromophore therein is added to a polymerizable monomer by esterification to synthesize a polymerizable monomer. As the polymerizable monomer, there are an acrylic monomer, a styrenic monomer and a vinyl/fatty acid ester monomer and, as the dye to be used, there are a methine dye, a polymethine dye, a cyanine dye, a phthalocyanine dye, a squalium dye and an azlenium dye. In this way, the lowering in a recording characteristic due to the crystallization of the org. dye is prevented from occurring and the stability as an optical data recording medium can be enhanced without lowering the recording characteristic of said medium.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical information recording medium using an organic dye, and in particular to a write-once optical information recording medium that improves the stability of a thin film using an organic dye. Regarding recording media.

[Conventional technology]

One type of optical information recording medium is a write-once optical recording medium in which a recording film made of a heat mode recording material is formed on a substrate constituting the optical information recording medium, and this recording material contains an organic dye. In this type of optical information recording medium, the recording layer can be formed using a coating method, so it is possible to reduce costs, and the recording layer is more resistant to oxidation than the method using a metal thin film. Also, since the thermal conductivity of resin is lower than that of metal, there is also the advantage that the pit spacing can be reduced to increase the recording density.

[Problem that the invention seeks to solve]

Although optical information recording media having organic dye-based recording films have the above-mentioned advantages, there are problems with the stability of the dyes used, and there are concerns about long-term and reliable storage of information.

Regarding the deterioration of recording information characteristics caused by the progress of crystallization of organic dyes in heat mode optical information recording media using organic dyes, there is a theory that it is effective to mix different kinds of polymers. be. However, although it is desirable to mix a non-dye polymer from the viewpoint of improving stability, the dye fraction in the recording thin film decreases, resulting in a decrease in laser sensitivity or a decrease in reflection. There is a fatal problem of deterioration of recording characteristics, which is the lifeblood of an optical information recording medium, such as resulting in a recording film with low efficiency. Furthermore, because the molecular weights of the dye in the recording thin film and the polymer to be mixed are too different, there is a possibility that the state will progress from a micro phase separation state to a macro phase separation state after mixing, and the stability itself may not necessarily be satisfactory. I can't say that.

The following are examples of conventional structures using a dye polymer as a recording film.

Thermoplastic vinyl polymer with dye residue (Japanese Unexamined Patent Publication No. 5
9-45195), styrene polymers having phthalocyanine residues in their side chains (JP-A-59-62188), polymers having styrene skeletons having phthalocyanine residues in their side chains and an average molecular weight of 40,000 or less (JP-A-59-62188); Polymers having a phthalocyanine ring in the main chain (Japanese Patent Application Laid-open No. 59-73994), dye polymers or their compositions (Japanese Patent Application Laid-Open No. 185694-1982), polymers with indole rings at both ends Polymer of cyanine dye having (JP-A-59-188
No. 853), a resin having a cyanine dye in the side chain having an indole ring at both ends (Japanese Unexamined Patent Publication No. 188854/1985),
The resin has an acid anion in the side chain and a cyanine cation is bonded to this (Japanese Patent Application Laid-Open No. 59-188855), and the resin that has a light absorber and a functional group is crosslinked with a metal crosslinking agent (Japanese Patent Application Laid-Open No. 188855/1989). 59-201243), one in which a resin having a functional group and a dye having a functional group are crosslinked with a metal crosslinking agent (Japanese Patent Application Laid-Open No. 59-201244), the dye is -CO
Polymers containing two or more O-1 or -COO- (JP-A-59-229396), dye polymers (JP-A-59-2
30796), a polymer of dye and resin (JP-A-59-2
32894), and one characterized by the pigment and resin component (Japanese Patent Application Laid-Open No. 59-232896).

[Means for solving problems]

The present invention was constructed to solve the above problems, and consists of polymerizing an organic dye by random copolymerization or graft copolymerization with a polymerizable substance, and mixing this polymerized dye with a single dye. This method is characterized in that a recording thin film is formed.

[Effect]

The absorption spectrum of a polymerized dye made from the same dye used in organic dye optical information recording media is not significantly different from the absorption spectrum of this single dye, and this polymerized dye itself is also used in recording films. It has the property that it can be Furthermore, it has good compatibility with individual dyes, and there is no fear of so-called phase separation. Organic dye recording films obtained by mixing such polymerized dyes have a higher initial recording and
It has excellent optical recording properties in all aspects, including playback properties, recording/playback properties after aging (accelerated deterioration), and durability. That is, due to the effect of preventing dye crystallization during aging, the recording medium properties are considerably superior to polymer mixed dye films.

[Structure of the invention]

The structure of the present invention is to polymerize an organic dye by random copolymerization or graft copolymerization with a polymerizable substance, and to form a recording thin film by mixing this polymerized dye with a single dye.

First, a polymerizable monomer is synthesized by adding a dye molecule having a chromophore within the molecule to a polymerizable monomer by esterification or the like.

Here, the following types of polymerizable polymers can be considered.

(Acrylic monomers) Acrylic acid, acrylic esters, methacrylic acid, methacrylic esters, etc. (Styrene monomers) Styrene, α-methylstyrene, divinylbenzene, chlorostyrene, cyanostyrene, aminostyrene, hydroxystyrene, etc. (acrylamide monomers) ) Acrylamide, methacrylamide, diacetone acrylamide, etc. (fatty acid vinyl ester monomers) Vinyl acetate, vinyl esters, tolyl and isonitrile monomers) Acrylonitrile, methacrylonitrile, adiponitrile, phthalonitrile, isonitrile, etc. (vinyl ether monomers) Alkyl vinyl ether etc. (halogenated olefin monomers) hinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, vinylidene fluoride, etc. (conjugated diene monomers) butadiene, isoprene, chloroprene, fluoroprene, cyanoprene, etc. (N-vinyl compound monomers) (Olefin monomer) Ethylene, propylene, isobutylene, etc. Next, a polymerized organic dye is obtained by random or graft copolymerization of an organic dye monomer with a polymerizable monomer.

In this case, the following radical polymerization initiators can be considered.

(Azo initiators) Azobisisobutyronitrile, etc. (Peroxide initiators) Benzoyl peroxide, di-t-butyl peroxide, potassium persulfate, etc. (Aqueous redox initiators) Cumene hydroperoxide and amines (Water-insoluble redox initiator) Hydroperoxide, benzoyl peroxide, etc., dimethylaniline, cobalt naphthenate, etc. Furthermore, during radiation polymerization, photoinitiators such as ultraviolet sensitizers and visible light sensitizers are added. do.

The following types of dyes may be used.

Methine dyes, polymethine dyes, cyanine dyes, carposianine dyes, anthraquinone dyes, azo dyes, phthalocyanine dyes, squarylium dyes, azulenium dyes, etc. Also, dye molecules are bonded to the above polymerizable monomers directly or via the following linking groups.

(R; hydrogen atom, alkyl group, etc.) 10-1-CO-1-C○○- -OCO-1-8O□ -1 -ocoo-1-NR-1 -CONR-1-CONRCO- -NRCO- 1-S-1-3ChNR-1-R3O□-Polymerizable monomers and dyes may be bonded and chained as follows.

(M: Monomer, D: Dye) (1) In the case of polymerization alone - M -M -M -M - DDD (2) In the case of simultaneous polymerization of a monomer that does not bind a dye and a monomer that binds a dye Example-M-M-
M -M - D D -M -M -M -M - D (3) Example of polymer chain containing a dye polymerization part-M
-D -M -D - -M -M -D -D -D - (4) A polymer of polymerizable monomer 1 dye bonded with polymerizable monomer 1 dye or each part of the polymerizable dye An example of what is included in a molecular chain.

-M -D -M -D - -M -M -D -D - Note that the seven tsummers are not limited to the same type, and may be of different types.

Furthermore, when forming a second protective film on a recording medium composed of a substrate, a first protective film, and a recording film in this order, these protective films must be formed in a manner that significantly impedes the sensitivity characteristics of the recording film. There should be no giblets.

Furthermore, if the light absorption spectrum of the dye used in these protective films has strong absorption in the visible or ultraviolet region, it is possible to improve storage deterioration as an optical recording medium; The dye concentration in the polymer protective film and the thickness of the protective film are desirably within a range that does not significantly impair sensitivity or S/N characteristics.

The polymerized dye recording film according to the present invention can be used as the first and/or second protective film.

The characteristics of the second protective film when the substrate, recording film, and second protective film are formed in this order are as follows.

If the light absorption spectrum of the dye used in the protective film and the light absorption spectrum of the recording film are similar, the recording sensitivity will vary slightly depending on the dye concentration of the dye polymer used in the protective film and the thickness of the protective film. However, since the dye polymer protective film is formed on top of the recording film, it is clearly observed that bits with clear edges are formed by laser irradiation, and the stability against readout light is significantly improved. .

[Example 1] Examples of polymerizable monomers in which a dye molecule containing a chromophore in the molecule is added to an acrylic acid monomer or a methacrylic acid monomer by esterification or the like are as follows. be.

Here, R is C0OH, F(, alkyl group, acryloyl group, alkyl ester, phenyl group, phenyl ester, those having C0OH, H at their terminals, alkoxy group, etc.). In this example, R is OCOCa Hv
It is. The polymerizable monomer (A) thus obtained was combined with acrylic acid methyl ester (B) to azobisisobutylnitrile (AIB) in the same manner as in ordinary radical polymerization.
A polymerization initiator such as N) is added and heated in a solvent such as dimethyl sulfoxide (DMS○) to obtain a copolymer.

In this case, the molar ratio of (A) and (B) was as shown in the table below.

Table 1 [Example 2] A recording film as a mixture was formed using the mixing ratio of polymerized tetra-tert-amylnaphthalocyanine vanadyl and tetra-tert-amylnaphthalocyanine vanadyl dye as shown in the following table.

In addition, A in the table shows polymerized tetra-tert-amylnaphthalocyanine vanadyl consisting of 30 parts by weight of a polymerized monomer obtained by adding tetra-tert-amylnaphthalocyanine vanadyl to acrylic acid and 100 parts by weight of an acrylic acid methyl ester monomer. B is tetra-tert-amylnaphthalocyanine vanadyl, C is 83 before accelerated test
Reflectance at 0 nm, D is 60°C190RH, 1
The reflectance at 830 nm after 000 hours is shown.

Table 2 [Comparative example] In the table below, the symbol E is 1/2 second nitrocellulose.

Other details are the same as in Table 2 above.

Table 3 From the above table, the mixing ratio of polymerized tetra-tert-amylnaphthalocyanine vanadyl and tetra-tert-amylnaphthalocyanine vanadyl dye is 1 part by weight to 5 parts by weight.
0 parts by weight: If it is 100 parts by weight, the reflectance is high and 6
This can be said to be a preferable range since there is little decrease in reflectance after storage at 0°C, 90RH, and 1000 hours.

On the other hand, as a comparative example, when nitrocellulose (nitrogen content 12%) with a viscosity of 1/2 second based on JIS standard -6703 is mixed (Table 3), as the mixing ratio of nitrocellulose increases, 60 ° C. Although the deterioration of the reflectance after storage for 1,000 hours is reduced, the reflectance before this accelerated test has already decreased. Samples 6 and 7 as comparative examples also showed a large decrease in reflectance after the accelerated test, making it difficult to put them into practical use. Note that the reflectance is measured using an integrating sphere and is a measurement value of regular reflection.

〔effect〕

As specifically shown above, the present invention polymerizes an organic dye with a polymerizable substance by a polymerization method such as random copolymerization or graft copolymerization, and mixes this polymerized dye with a single dye to form a recording thin film. This prevents the recording characteristics from deteriorating due to crystallization of the optical information recording medium (and significantly improves the stability of the recording medium). Can be done.

Claims (1)

[Claims] In an optical information recording medium using an organic dye thin film in the recording layer, the recording thin film is formed by mixing an organic dye and a polymerized organic dye obtained by copolymerizing this organic dye with a polymerizable substance. An optical information recording medium characterized by: