JPH02141284A - Novel optical recording material - Google Patents

Abstract

PURPOSE:To enhance storage stability by setting the reflectivity of a metal silver- containing layer, which is obtained by reacting the silver ion supplied from an organosilver salt oxidizing agent with a reducing agent in the presence of silver or a metal developing nucleus more noble than silver, to a specific range. CONSTITUTION:In an optical recording material wherein the reflectivity of a metal silver-containing layer obtained by reacting the silver ion supplied from an organosilver salt oxidizing agent with a reducing agent in the presence of silver or a metal developing nucleus more noble than silver shows 10 - 90%, the organosilver salt oxidizing agent and the reducing agent are preliminarily dispersed or dissolved uniformly and applied to a base film uniformly to be dried. As the organosilver salt oxidizing agent, a silver salt of carboxylic acid, silver saccharate and silver benzotriazole inclusive long chain fatty acid can be used. The reducing agent to said organosilver salt oxidizing agent can be selected from hindered phenols wherein a stereoscopically bulky group is bonded to carbon adjacent to carbon to which a phenolic hydroxyl group is bonded to hinder the hydroxyl group stereoscopically. By this method, the optical recording material having good storage stability with respect to a laser beam source and not deteriorated even under a high temp. and high humidity storage condition can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical recording material that utilizes the change in reflectance caused by a writing process using a laser beam.

[Conventional technology]

In recent years, with remarkable progress in laser-related technology, various new recording materials have been proposed.

A typical example of this is a high-density digital recording material such as an optical disk, but apart from this, a flexible optical card material has recently been proposed as a material that can be handled more easily. As an example of this, JP-A-59-502139
The optical card developed by Drexler Corporation, which is described in Japanese Patent Laid-Open No. 58-188346, is famous.

On the other hand, optical tape has been proposed as a material that is more compact than optical disks and can record a large amount of information.

Although several systems and materials have been proposed, there are problems with writing sensitivity, storage stability of recording materials, recording density,
The characteristics necessary for recording materials, such as error rate, were still insufficient.

For example, it has been pointed out that materials that are highly sensitive to laser light sources do not necessarily have good storage stability and are susceptible to deterioration under high humidity conditions, or that they are gradually oxidized by oxygen in the air, resulting in a decrease in sensitivity. It has been updated in terms of credibility.

In addition, for optical cards and optical tapes, which are expected to be used under more severe bending conditions than optical disks, new materials have been desired since conventional metal YI film materials may crack. The Drexler Company has already proposed the use of a silver thin film material obtained by developing a wet silver halide photographic material under special development conditions in optical cards.

However, this material has limitations as a silver salt photographic film, such as the use of hydrophilic gelatin as a binder, and problems have been pointed out, such as its inability to be stored under high humidity conditions for long periods of time.

In addition, in materials using this wet silver halide film, the shape of the silver particles is controlled so that a reflective layer and an absorbing layer are formed, which poses problems such as requiring delicate manufacturing conditions. .

[Problem to be solved by the invention]

In particular, the present invention aims to provide a recording material that is extremely excellent in storage stability, which has been viewed as a problem with this type of recording material.

In particular, the objective was to provide an optical recording material layer that does not suffer damage such as cracks even under severe usage conditions such as bending, and that hardly deteriorates even under severe storage conditions of high temperature and humidity.

Further, the present invention aims to provide a low-cost recording material that can be continuously produced. That is, roll coater
Very common industrial production means can be selected, such as continuous coating with a hot roller, continuous heating with a hot roll, or a suitable preformat can be provided as required by pattern exposure through a mask. This is an extremely important issue in reducing the cost of recording materials.

Furthermore, it is extremely useful for manufacturing that the metal silver-containing layer can be formed into a substantially simple layer of one type.

[Means to solve the problem]

A photosensitive material using an organic silver salt oxidizing agent as an image forming material is known as a heat-developable silver salt photographic film.
The present inventors discovered a completely new optical recording material based on this basic composition and completed the present invention.

In particular, a metallic silver layer is formed using development nuclei as catalyst nuclei only when silver or metal development nuclei nobler than silver are present under conditions that cannot be reduced by mere thermal development with an organic silver salt oxidizing agent and a reducing agent. This is how it was done. Organic silver salt oxidizing agents can be used to produce blackening (formation of silver particles) during heating, similar to the heat development of so-called heat-developable silver salt photographic films, by containing an appropriate reducing agent in the system and using appropriate development conditions. ), and the internal organic silver salt oxidizing agent can diffuse to the surface to form a reflective metal thin film layer on the surface, which is completely novel. Therefore, the organic silver salt-containing layer itself can remain as a substantially transparent layer after silver ions are supplied.

Such a novel optical recording material of the present invention can be defined as follows. That is, the reflectance of the metallic silver-containing layer obtained by reacting the silver ions supplied from the silver salt oxidizing agent with the reducing agent in the presence of metal development nuclei nobler than silver is 10 to 90. % in optical recording materials.

In this case, the reflective metallic silver-containing layer and the substantially transparent organic silver salt-supplying layer in this optical recording material may or may not have sharp boundaries. It's not important. However, in order to improve the recording density as an optical recording material, metallic silver must be uniformly dispersed as a dispersion that is infinitesimal in size than at least 2 to 3 microns, or it must be present in a uniform continuous state in the order of 2 to 3 microns. Preferably, it is a metal vA layer that can be treated as a Vt layer.

Note that the reflectance value is expressed as the intensity ratio of light reflected at a regular reflection angle (-75@) to light incident on the optical recording material at an angle of 75 degrees.

A light source around 750 to 850 nm is used to measure this reflectance.

Further, in the present invention, it is desirable that the organic silver salt-containing layer itself remains substantially transparent even after silver ions are supplied, and the transmittance at the light wavelength (750 to 850 nm) used for measuring the reflectance is 75 nm. % or more, preferably 85% or more from the viewpoint of system construction.

Regarding the thickness of the recording layer itself including the organic silver salt oxidizing agent of this optical recording material, as long as a difference in reflectance can be obtained, the thinner the thickness, the better from the viewpoint of improving the recording density. The thickness is set to about 1 to 20 μm.

In addition, the larger the reflectance value, the easier it is to construct a detection system, but conversely, if the reflectance is high, the laser power cannot be effectively absorbed, so in practice it is
%, preferably about 25 to 60%.

In the optical recording material of the present invention, pits are formed in the metal silver-containing layer by a laser beam such as a semiconductor laser or a He-Ne laser, and information is recorded by exposing the transparent organic silver salt-containing layer.

The optical recording material of the present invention is prepared by first uniformly dispersing or melting an organic silver salt oxidizing agent and a reducing agent therefor, coating the mixture uniformly on a suitable base film, and then drying.

As the organic silver salt oxidizing agent for this purpose, silver salts of various carboxylic acids containing long-chain fatty acids, silver salt phosphate, silver hensitriazole, etc. can be used. Among these, silver behenate, silver stearate, and the like are particularly useful.

As a reducing agent for this organic silver salt oxidizing agent, a sterically bulky group is bonded to the carbon adjacent to the carbon to which the phenolic hydroxyl group used in ordinary dry silver salt photographic film is bonded, and the wood acid group is sterically You can choose from hindered phenols that are physically impaired. For example, 2.6-Gt-
Butyl-4-methylphenol, 2,2゛-methylenebis-(4-methyl-6-1butylphenol), 2,2
°-Methylenebis-(4-ethyl-6-t-butylphenol), 2,2,4-trinotylpentylbis(
2-hydroxy-3,5-dimethylphenyl)methane,
2.5-di also includes monobutyl-4-methoxyphenol and the like. Also, hydroquinone, 2.5-
Reducing agents for silver salts, such as dimethylhydroquinone, chlorohydroquinone, p-aminephenol, methylhydronaphthalene, phenidone, and methyl gallate, as well as bisphenol A, 2,4-dihydroxybenzoic acid, and p-methoxyphenol, can also be used. .

The amount of reducing agent varies depending on the type of reducing agent, etc., but for boat fishing it is about 0.01 to 1 mole of organic silver salt oxidizing agent.
About 10 moles, preferably about 0.1 to about 3 moles.

The organic silver salt oxidizing agent and reducing agent are prepared in advance using an alcohol solvent such as methanol or ethanol, a ketone solvent such as 2-butanone or acetone, an ester solvent such as ethyl acetate, or an aromatic hydrocarbon solvent such as toluene or xylene. A uniform coating solution is prepared by mixing and dispersing an organic solvent such as the above and an organic synthetic polymer compound or an organic natural polymer compound.

Here, the selection of a polymer compound as a binder is important not only for creating a stable coating solution, but also for the storage stability of the optical recording material after coating drying and heat development. This is extremely important as it has a major impact on In particular, hydrophilic binders such as gelatin, polyvinyl alcohol, etc. should be avoided in order to provide more favorable stability under high humidity storage conditions. Preferred binders in the present invention may be appropriately selected from a wide range of hydrophobic organic polymer compounds such as polymethyl methacrylate, polyvinyl formal, polyvinyl butyral, vinyl chloride-vinyl acetate copolymer, cellulose acetate, and polystyrene. can. The hydrophobic binder is used in a weight ratio of about 1 to 1 O to the organic silver salt oxidizing agent.
The ratio is approximately 1:10.

In the present invention, the reflective tin metal-containing layer is created as follows. That is, it is obtained by providing a layer of metal development nuclei nobler than silver on the aforesaid pre-coated silver salt layer.

This typical production method can be performed in exactly the same manner as the method of providing metal nuclei by electroless plating. for example,
It is sequentially immersed in an aqueous solution of stannous chloride and an aqueous solution of palladium chloride to impart metal nuclei of palladium to the surface layer. No change in appearance occurs before or after this treatment.

When an organic silver salt oxidizing agent layer having such a surface layer is heated under appropriate heating conditions, for example, at a temperature of at least 70° C. for several seconds to several minutes, a recording material layer having a metallic silver luster can be formed on the surface layer. Suitable heating conditions include 90~
It takes about 2 to 30 seconds at 140°C. These development conditions must be controlled to optimal conditions in order to satisfy the constitution of the present invention.

In particular, care must be taken because excessive development tends to cause unnecessary root particles to be formed in the organic silver salt-containing layer and to cause the reflective silver-gold region-containing layer to become non-uniform.

This metallic silver-containing layer contains a very small amount of development nuclei of a metal nobler than silver, and a metal species nobler than silver that acts catalytically is essential for the development of this reflective layer. Examples of metals nobler than silver include palladium, platinum, gold, rhodium, ruthenium, thallium, and mercury.

These metal nuclei do not need to be a single metal species, but may be a composite system or a sulfide.

In addition, as a method of imparting nobler metal species to the surface layer, there are methods such as dispersing these minute metal development nuclei in a solvent containing an appropriate binder and coating the surface layer as a second layer, or vapor deposition. It is also possible to form a trace amount of metal development nuclei on the surface under gas phase conditions.

Furthermore, it is also possible to use the silver metal nucleus itself as a catalyst nucleus more simply, and in this case, instead of using a metal species nobler than silver, the organic material is treated with a stronger reducing agent such as ascorbic acid. It can also be substituted by covering the surface with a silver salt oxidizing agent layer.

Further, a compound that forms silver sulfide nuclei, such as sodium sulfide, may be disposed on the surface layer.

Alternatively, the surface may be exposed to a reducing gas such as hydrogen gas for a short time to provide silver-gold area development nuclei on the surface layer.

Some of these methods successfully perform what is known as physical development in photochemistry on the surface layer using heat development.
A layer containing metallic silver is formed.

The optical recording material of the present invention can contain various additive components to improve the intended performance of the material. For example, for the purpose of controlling the silver-gold area to a predetermined size, a toning agent such as phthalazine, which is used in dry silver salt photographic films, an antifogging agent, and a sensitizer can be added.

Furthermore, among the side reaction products formed by the reaction between the organic silver salt oxidizing agent and the reducing agent, organic compounds such as fatty acids formed from silver salts of long-chain fatty acids are present in the binder and play a role as a plasticizer. You can control the writing sensitivity.

Furthermore, in the present invention, it is possible to incorporate photosensitive silver halide into the recording material by applying dry silver salt technology, and by such combination, it is possible to perform pattern exposure through a mask in advance during manufacturing. It was also found that pre-formatting can be easily performed using the following method. Such a change in composition can be achieved by applying a halogen ion source to a part of the organic silver salt oxidizing agent and converting a part of the organic silver salt oxidizing agent into photosensitive silver halide in advance, or by preparing a separate silver halide. There is a method of dispersing the deposited silver halide microcrystals in a coating solution containing an organic silver salt oxidizing agent.

The optical recording material of the present invention is provided with a transparent protective layer for the purpose of protecting the recording layer. This GI layer is selected from highly transparent organic polymer compounds such as polycarbonate, polystyrene, polymethyl methacrylate, polyvinyl chloride, polyvinyl chloride, and polyethylene terephthalate.

Further, the optical recording layer may consist only of a base film coated on the back side of the optical recording material layer, or a reinforcing layer against bending etc. may be further provided on the back side.

The shape of the optical recording material of the present invention is generally card-shaped, but is not limited to this, and may be disk-shaped or tape-shaped.

The optical recording material of the present invention can be recorded with various laser light sources having appropriate power, typical examples of which are He--He lasers and semiconductor lasers. For example, using a semiconductor laser of about 10 mW, writing can be performed at a speed of about several 10 c+n/sec with a beam diameter of 2 to 3 microns.

The optical recording material of the present invention can be used as a so-called write-once type recording material, which a user can write on as needed, and can also be used as a read-only RO'l card, etc., on which information can be written in advance. be able to.

In order to explain the present invention in more detail, examples will be described below, but the present invention is not limited to the examples.

Example 1 A suspension consisting of the following components was prepared.

Hehenic acid 20g Polyvinyl butyral 18g 8g Phthalazine 2.3g 22”-methylenebis(4-L-butyl-6-t-butylphenol)
6g 2-butanone
200g toluene
60g of this suspension was homogenized by a ball mill for about 12 hours, and then passed through a filter with an average pore size of 1.5μ to remove undispersed matter.

After drying this Q/r49 with a small applicator,
A slit with a diameter of 6 μm was selected, and it was uniformly coated on a 1.25 μm polyester film and dried at room temperature.

(The obtained sample is designated as sample No. 1.) Then the sample After being immersed in water for 10 seconds each, it was washed with water and air-dried.

(Sample No. 2) (Aqueous solution 1) Stannous chloride 2g Distilled water
100 - Concentrated hydrochloric acid
2 ml (water soluble e1.2) Palladium chloride 0.1 g Distilled water 200 d Concentrated hydrochloric acid
Samples obtained for 5 ran each were heated at 130'C for 6 seconds.

Sample No. 1 has almost no change in appearance and transmittance of 92
%, whereas sample No. In No. 2, the coated surface layer had a metallic luster and the reflectance was 35%.

Next, a semiconductor laser beam having an emission wavelength of 830 nm (beam diameter 3μ, emission output 1OmW) was applied to sample No. 2.
) was used to conduct a writing test. Scan speed 4
When pulses were emitted at 0 cm/sec, holes of 3 μm perpendicular to the scanning direction and 3.5 μm parallel to the scanning direction were recorded.

Example 2 Sample No. in Example 1. A solution of the following components was spin-coded onto the sample No. 1, and the coating thickness after drying was 0.6.
It was applied so that it was μ.

Polyvinyl alcohol Log gold chloride (I
Sodium [[) acid 100mg methanol
20,! Distilled water
Samples dried at room temperature for 500 d are
Further, it was vacuum dried at 50'C for 24 hours.

The obtained sample was heat-treated in the same manner as in Example 1, and an optical recording material with a reflectance of 46% was produced. As in Example 1, this could be written with a semiconductor laser beam.

Example 3 A suspension consisting of the following components was prepared in a dark room, and sample No. 1 of Example 1 was prepared under red light. An optical recording material was prepared in the same manner as in Example 2.

Behenic acid 20g Vinyl chloride-vinyl acetate copolymer 15.

Phthalazine 6g2.2”
-Methylenebis(4-t-butyl-6-t-butylphenol) 10g calcium bromide
0.3g cobalt iodide
0.4g 2-butanone
200g toluene
50g of the obtained optical recording material is 2μ in 10μ pitch.
Through the chrome mask, which is notched with a width of 30
Exposure to a high-pressure mercury lamp for 10 seconds and immediately heat at 130℃ for 4 hours.
The entire surface was heated for seconds.

In the optical recording material tested in 4 tests, a metal reflective layer was obtained in which a non-glossy area (light yellow transparent layer, which can be used as a tracking guide) of 2 μm x 7 inches was formed in the exposed area. This reflectance was 40%.

It was verified that this could be written and read at a speed of 45 cm/sec using an optical card test machine equipped with a 10 mW semiconductor laser.

Example 4 Samples No. 2 of Example 1, Examples 2, and 3 were stored for one week under accelerated storage test conditions of 70°C, 180% RH, and their degree of deterioration was examined.

The changes in appearance, such as reflectance and focus shape, are mostly i, T!
It has been found that the optical recording material of the present invention is extremely stable.

Example 5 A sample was prepared using 100 mg of each of mercuric acetate and hydroquinone in place of sodium chloroaurate (III) in Example 2.

Similarly, a sample was also prepared using potassium iodoplatinate instead of palladium chloride in Example 1.

It was found that all of these samples had a metallic luster surface when heated at 130° C. for 5 seconds.

Claims (4)

[Claims] (1) In the presence of silver or a metal development nucleus nobler than silver,
The reflectance of the metallic silver-containing layer obtained by reacting the silver ions supplied from the organic silver salt oxidizing agent with the reducing agent is 10.
Optical recording material that is ~90%. (2) An optical recording material according to claim (1), which contains photosensitive silver halide microcrystals and can be preformatted by pattern exposure. (3) The optical recording material according to claim (1) is produced by heating the organic silver salt oxidizing agent, the reducing agent therefor, and a trace amount of metal catalyst nuclei nobler than silver metal to a temperature of at least 70°C or higher. Manufacturing method to produce. (4) A recording method for recording information by causing a change in reflectance by irradiating the optical recording material according to claim (1) with pulsed laser light.