JP2961738B2 - Manufacturing method of optical information recording medium - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing an optical information recording medium having an organic dye layer as a recording layer, and more particularly, to an organic solvent used for forming an organic dye layer. Regarding choice.

[Summary of the Invention]

The present invention relates to a method for producing an optical information recording medium for forming an organic dye layer by applying a coating material obtained by dissolving an organic dye in an organic solvent on a substrate. By selecting a compound that does not cause damage, a uniform organic dye layer is formed, and a highly reliable optical information recording medium can be manufactured.

[Conventional technology]

2. Description of the Related Art In recent years, in the field of information recording, researches on optical information recording methods have been advanced in various places. This optical information recording system can perform recording and reproduction without contact, and can achieve a recording density that is at least an order of magnitude higher than magnetic recording media,
It has many advantages, such as being compatible with the read-only type, write-once type, and rewritable type memory types. It is what is being done.

Of the above-mentioned memory forms, the write-once type is a type in which recording and reproduction can be performed by an end user and cannot be erased, and thus is mainly used as a long-term storage file for data. At the time of recording, a local irreversible physical change of the recording layer caused by a recording material absorbing light energy and converting it into heat energy is used. Known irreversible physical changes include a change in the shape of the recording layer (formation of pits), a change in surface properties, a change in the crystal state, and the like.

Most of write-once optical information recording media currently in practical use use a tellurium alloy or tellurium compound as a recording material. However, in recent years, organic dyes have attracted attention in place of these tellurium-based materials from the viewpoint of further improving mass productivity and economic efficiency of media. The above organic dyes need to show large absorption in the near-infrared region of a semiconductor laser used for recording and reproduction. Dyes and the like are known.

In order to form an organic dye layer, these organic dyes are dissolved in an appropriate organic solvent together with additives and binders used as necessary, and the paint prepared in this manner is made of plastic, glass, or the like. In general, a method of evaporating an organic solvent after coating on a substrate is used.

[Problems to be solved by the invention]

By the way, as an organic solvent used when preparing the above-mentioned paint, it is important to first select a compound which has sufficient solubility in an organic dye and does not damage the substrate.

For example, one of the most widely used materials for substrates at present is polycarbonate, but this material is not necessarily excellent in chemical resistance, and is decomposed, dissolved, or dissolved by the following chemicals or compounds. Subject to physical changes such as swelling, devitrification, and cracking. First, there are alkalis, ammonia, amines, and the like that decompose polycarbonate. Examples of soluble substances include chlorinated aliphatic hydrocarbons such as methylene chloride and chloroform, and heterocyclic compounds such as pyridine, dioxane, thiophene, and tetrahydrofuran. Further, swelling, devitrification, cracks, etc.
Examples include aromatic hydrocarbons such as benzene, xylene, and toluene, acetone, and methanol.

On the other hand, solvents that do not adversely affect polycarbonate, such as mineral acids, organic acids, various redox agents, fats and oils, saturated fatty acids, and cycloaliphatic hydrocarbons, are also known. Generally lacks the solubility of organic dyes,
It is difficult to form a uniform organic dye layer.

Therefore, conventionally, measures have been taken to avoid adverse effects as much as possible by appropriately selecting or combining the above-mentioned solvents, but this has never been sufficient.

Therefore, the present invention solves the above-described problems, forms a uniform organic dye layer without damaging the substrate, and provides a method for manufacturing an optical information recording medium that enables the production of a highly reliable optical information recording medium. For the purpose of providing.

[Means for solving the problem]

The present inventors have repeatedly studied to achieve the above object, and the conventional problems can be solved by appropriately selecting the type of organic solvent used when dissolving and applying an organic dye. This has led to the completion of the present invention.

That is, the method for producing an optical information recording medium according to the present invention is a method for producing an optical information recording medium in which an organic dye layer is formed by applying a coating solution in which only an organic dye is dissolved in an organic solvent onto a substrate. The organic solvent is 3-hydroxy-3-methyl-2-butanone represented by the following formula.

_{(CH 3) 2 C (OH} ) -COCH 3 This 3-hydroxy-3-methyl-2-butanone,
It has a wider range of compatibility than mineral acids, organic acids, redox agents, fats and oils, saturated fatty acids, cycloaliphatic hydrocarbons, etc., which are conventionally known as solvents that do not adversely affect the polycarbonate substrate, and are used for optical information recording media. Cyanine dyes and squarylium dyes used as organic dyes can be dissolved in a practically usable concentration range. In addition, various additives such as a nickel complex and binderdamine added for the purpose of improving properties, and a polymer binder added for the purpose of improving film formability can be dissolved depending on the type. The above organic dyes, various additives, and the like are preferably dissolved in the above-mentioned organic solvent such that the concentrations thereof are about 0.5 to 5% by weight.

As the material of the substrate, those used for ordinary optical information recording media can be used.In particular, polycarbonate is excellent in wettability to the above-mentioned organic solvent, and is used for forming a uniform organic dye layer. It is suitable.

As a coating method, a spin coating method, a doctor blade method, a gravure coating method, a web coating method, or the like can be applied. Among them, the spin coating method is particularly practical.

Note that a base film, a protective film, a metal reflective film, and the like may be formed on the optical information recording medium as needed.

[Action]

The 3-hydroxy-3-methyl-2-butanone used in the present invention has a wide range of compatibility with organic dyes, does not damage substrate materials represented by polycarbonate, and is excellent in substrate materials. Since it exhibits high wettability, it becomes possible to form an organic dye layer having a uniform thickness when applied on a substrate.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described based on experimental results.

Example 1 In this example, an optical information recording medium was manufactured by forming an organic dye layer using a cyanine dye as a recording material on a substrate made of polycarbonate.

First, a cyanine dye represented by the following structural formula (manufactured by Nippon Kogaku Dye Co., Ltd., trade name: NK-529) was dissolved in 3-hydroxy-3-methyl-2-butanone so as to have a concentration of 3% by weight. And a paint was prepared.

Next, there is a hole for connecting a rotating device having a diameter of 1.5 cm in the center, and a guide groove is formed in a signal recording portion in advance.
Set the polycarbonate substrate on the spin coater,
After the above-mentioned paint was dropped using a dispenser while rotating at a rotation speed of 300 rpm, the rotation speed was increased to 1000 rpm and held as it was for 2 seconds. Then, reduce the rotation speed to 500 rpm and hold it for 1 second, then 1500 rpm for 30 seconds
And hold it for 1 second, and finally 2000rp
The rotation was stopped after holding at m for 10 seconds.

The thickness distribution of the organic dye layer thus formed was also very uniform.

〔The invention's effect〕

As is clear from the above description, when the present invention is applied, a uniform organic dye layer can be efficiently formed without damaging the substrate. Therefore, an optical information recording medium suitable for high-speed recording and high-density recording can be provided with excellent reliability and productivity.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Nobuyuki Matsuzawa 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (56) References JP-A 2-1375 (JP, A) JP-A Sho 60-226036 (JP, A) JP-A-63-160890 (JP, A) JP-A-1-150256 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5/26

Claims (1)

(57) [Claims] 1. A method for manufacturing an optical information recording medium, wherein an organic dye layer is formed by applying a coating material in which only an organic dye is dissolved in an organic solvent to a substrate, wherein the organic solvent is 3-hydroxy-3-methyl- A method for producing an optical information recording medium, which is 2-butanone.