JPH05273691A - Optical recording material - Google Patents

Abstract

PURPOSE:To enable writing at an ultra-high speed by laminating a high-polymer film having small oxygen permeability on a photoreactive film consisting of a polymer contg. a specific ion pair charge transfer complex. CONSTITUTION:The high-polymer film 3 having the small oxygen permeability is laminated on the photoreactive film 2 consisting of the polymer contg. the ion pair charge transfer complex of the 4, 4'-bipyridinium ions obtd. by acting a donor on 4,4'-bipyridinium as an acceptor to form the ion pair charge transfer complex, by which the protection against oxidation is provided. The compd. forming the ion pair charge transfer complex with the 4,4'-bipyridinium ions includes, for example, tetraphenylborate having plural fluoro substd. The polymer incorporating the ion pair charge transfer complex includes, for example, poly(tetrahydrofuran) having 4,4'-bipyridinium groups in a part of the main chain or a vinyl polymer having the 4,4'-bipyridinium groups in the side chain, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording material, and more particularly to an optical recording material based on a photoinduced electron transfer reaction which causes a charge transfer upon irradiation with light.

[0002]

2. Description of the Related Art At present, a method of writing information on a magneto-optical disk or the like is to change a substance such as a rare earth-transition metal alloy existing in the disk by heat of laser light, which is a so-called heat mode. This is a method called recording. But,
In heat mode recording, the density is almost determined by the degree of condensing light and is 100 mega per square cm (1 mega = 10).
It is said that it is difficult to record information at high density of more than 100,000) bits. Therefore, photon mode recording has been required to record information according to the wavelength and polarization characteristics of the light itself. That is, the photon mode
This is because in the case of de-recording, it is possible to multiplex and write because it can be multiplexed. The photon-mode recordable material is a material that causes a reaction at the level of one molecule by light, and examples of such a material include a photochemical hole burning material and a photochromic material.

The photochemical hole-burning material disperses a dye which reacts with light in a substance in which the movement of the molecule is frozen, and when a laser light having a certain wavelength is irradiated, the molecular structure of the dye is changed by the photochemical reaction. It is changed and a small hole is created in the absorption spectrum, which is used for optical recording. The recording density is 100 giga (1 giga = 1 billion) bits per cm ^{2, which} is a very large recording density. However, it has a drawback that it cannot be used unless it is cooled to a temperature of −196 ° C. or lower because a photochemical reaction is carried out while the movement of molecules is frozen.

On the other hand, the photochromic material changes the molecular structure by light to enable recording, but it has drawbacks in terms of durability of repeated writing and writing speed. By the way, the 4,4′-bipyridinium ion acts as a cationic electron acceptor (acceptor) with many organic compounds or inorganic anions and charge transfer (CT).
In the photoexcited state, it forms a complex,
One electron moves to. The present inventor previously found that tetrakis [3,5-bis (trifluoromethyl) phenyl] borate anion having a chemically stable and bulky structure and 4,4
When 4'-bipyridinium ion forms an ion-paired CT complex and is irradiated with light under degassing, photoinduced electron transfer occurs, resulting in a blue state, and in the dark place, the CT state, which is the original pale yellow state, changes slowly. It returns to a blue state when it is photoexcited again, and such a change can be repeated many times, and the speed of color change based on this photoinduced electron transfer reaction is very fast at the picosecond order. It was found to change with.

Therefore, based on the above phenomenon, 4,4 '
-A polymer containing an ion-pair charge transfer complex with a bipyridinium ion is expected as an optical recording material capable of ultra-high speed writing, but since the polymer has a large reactivity with an oxidizing agent such as oxygen, Therefore, the above reversible color change cannot be generated.

[0006]

Therefore, the present inventor has completed the present invention as a result of various investigations for improving the above-mentioned drawbacks and using it as an optical recording material. An object is to provide an optical recording material based on a photo-induced electron transfer reaction that can be written at a speed.

[0007]

The gist of the present invention is 4,
It is an optical recording material characterized in that a polymer film having a low oxygen permeability is laminated on a photoreactive film made of a polymer containing an ion pair charge transfer complex with 4'-bipyridinium ion. That is, in the present invention, 4,4′-bipyridinium ion is used as an acceptor, and it is allowed to act with a donor to form an ion-pair charge transfer complex to obtain 4.4 ′.
An optical recording material in which a polymer film having a low oxygen transmission rate is laminated on a photoreactive film made of a polymer containing an ion-pair charge transfer complex of bipyridinium ion to protect it from oxidation. The compound providing the 4,4′-bipyridinium ion in the present invention is a compound having the following structural formula (1).

[0008]

[Chemical 1]

In the formula, R ¹ and R ² are a phenyl group having an alkyl group or a substituent, a benzyl group or a poly (tetraethylene oxide) group. In the present invention, 4,4 '
-A compound that forms an ion-pair charge transfer complex with a bipyridinium ion is a compound that acts as a donor with respect to 4,4'-bipyridinium ion, for example, tetraphenylborane having a plurality of fluoro substituents. Specific examples of some of these are tetraphenyl borate as shown below.

[0010]

[Chemical 2]

In the formula, R is CF ₃ , --CF ₂ CF ₂ CF ₂ CF
₃ ,

[0012]

[Chemical 3]

[0013]

[Chemical 4]

Etc. and M represents a metal ion or an ammonium ion.

In the present invention, the polymer containing the above ion-pair charge transfer complex has 4,4 'in a part of the main chain.
-Poly (tetrahydrofuran) having a bipyridinium group, vinyl polymer having a 4,4'-bipyridinium group in a side chain, or poly (methyl methacrylate) having a low molecular weight 4,4'-bipyridinium salt dispersed therein. .. In the case of a dispersion system, the content is about 20% with respect to the polymer.

The polymer film having a low oxygen permeability used in the present invention is a polyvinyl alcohol film, a polyvinyl acetate film, a polyacrylonitrile film or the like. In the case of a polymer having a 4,4′-bipyridinium group in its main chain or side chain, it is preferable to use a water-soluble polymer protective film because of its high solubility in many organic solvents.

The method for producing an optical recording element according to the present invention comprises an ion-pair charge transfer complex with 4,4'-bipyridinium ion by a casting method on a substrate such as glass or polycarbonate. It can be easily obtained by molding a polymer film, that is, a photoreactive film, and forming a polymer film having a low oxygen transmission rate thereon.

As a method of forming the photoreactive film, the above-mentioned 4,
An organic solution of, for example, 1,2-dimethoxyethane, of a polymer containing 4'-bipyridinium ion and tetraphenyl borate having a plurality of fluoro substituents as its counter ion is prepared on a substrate. Or a solution of an ion-pair charge transfer complex containing 4,4'-bipyridinium ion in a polymer solution is cast on a substrate, and then polyvinyl alcohol-
A polymer having a low oxygen transmission rate, such as silicone, is applied and dried.
The concentration of the photoreactive film forming solution used is 3 mg / ml
The concentration of the polyvinyl alcohol aqueous solution is about 10 mg / ml.

The optical recording element thus obtained is illustrated in FIG. In the figure, 1 is a substrate, 2 is a photoreactive film, and 3 is a polymer protective film. Furthermore, the present invention will be specifically described with reference to examples.

[0020]

【Example】

Example 1 Tetrahydrofuran (24.45 g) and trifluoromethanesulfonic anhydride (1.40 g) are stirred for about 15 minutes in an argon atmosphere at room temperature and then cooled to -70 ° C. So 0.53g dissolved in 10ml tetrahydrofuran
4,4'-bipyridine was added and stirred for several hours,
A polymer containing a 4,4'-bipyridinium group in a part of the main chain was prepared. The 4,4'-bipyridinium ion concentration was 4.
It was 3 × 10 to ⁴ mol / g. Tetrakis [3,5-bis (trifluoromethyl) phenyl] is added to this polymer.
A borate salt was allowed to act to obtain a CT complex salt. Then, the CT complex salt was dissolved in 1,2-dimethoxyethane to give about 0.
A 3% concentration solution was prepared, cast on a glass substrate and dried to form a photoreactive film. Subsequently, an aqueous polyvinyl alcohol solution having a concentration of about 1% was applied onto the photoreactive film and dried to obtain an optical recording material. The obtained optical recording material turned blue when irradiated with light in the air, and its life (time to decay to 1 / e = 1 / 2.718 of absorbance immediately after irradiation) was about 70 hours at 20 ° C. It was For comparison, the one without the polyvinyl alcohol protective film did not change its color when exposed to light in the air, and when it was exposed to light under deoxidation and turned blue, it took about 3 minutes to add air. The color disappears.

Example 2 5 mg of N, N 'was added to 1 ml of a 1,2-dimethoxyethane solution of poly (methyl methacrylate) (10 mg / ml).
A tetrakis [3,5-bis (trifluoromethyl) phenyl] borate salt of -dimethyl-4,4'-bipyridinium was dissolved and cast on a glass substrate to obtain an optical recording material after drying. The obtained optical recording material turned blue when irradiated with light in the air, and its life (time to decay to 1 / e = 1 / 2.718 of absorbance immediately after irradiation) was about 45 days at 20 ° C. It was

[0022]

INDUSTRIAL APPLICABILITY As described above, the present invention uses an ion-pair charge-transfer complex as a photoreactive film, so that it is reversible by simply transferring electrons between ion pairs without causing a structural change due to light irradiation. Since it shows a color change, it is possible to provide a rewritable optical recording material, and as an ion pair charge transfer complex, 4,4'- is formed in a part of the main chain.
When a tetrakis [3,5-bis (trifluoromethyl) phenyl] borate salt of a polymer containing a bipyridinium group is used, the writing speed is as fast as several tens of picoseconds. Further, since a polymer film such as polyvinyl alcohol is laminated, the recorded state can be stably maintained in the air.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical recording material according to the present invention. Substrate 2. Photoreactive film 3. Protective film

Claims (3)

[Claims] 1. A photoinduced electron transfer characterized by laminating a polymer film having a low oxygen transmission rate on a photoreactive film made of a polymer containing an ion-pair charge transfer complex with 4,4′-bipyridinium ion. Optical recording material based on reaction. 2. The compound forming an ion pair charge transfer complex with 4,4′-bipyridinium ion is tetraphenylborate having a plurality of fluoro substituents.
The optical recording material described. 3. The optical recording material according to claim 1, wherein the ion-pair charge transfer complex is 4,4′-bipyridinium tetrakis [3,5-bis (trifluoromethyl) phenyl] borate salt.