JP2706708B2 - New optical recording material - Google Patents

Description

Description: TECHNICAL FIELD [0001] The present invention relates to an optical recording material utilizing the fact that the reflectance changes by a writing process using a laser beam.

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

A typical example is a high-density digital recording material such as an optical disk. Apart from this, a flexible optical card material has recently been proposed as a material that can be handled more easily. As one example, an optical card developed by Drexler, which is described in JP-A-59-502139 and JP-A-58-188346, is famous.

On the other hand, an optical tape has been proposed as a material capable of recording information of a larger capacity and more compact than an optical disk.

Although several systems and materials have been proposed in this way, writing sensitivity, storage stability of recording materials, recording density,
Various properties required as a recording material such as an error rate are still insufficient.

For example, materials that are highly sensitive to laser light sources do not always have good storage stability and tend to degrade under high humidity conditions, or they are gradually oxidized by oxygen in the air to cause a decrease in sensitivity. It was pointed out, and it was one step in terms of reliability.

Further, as for optical cards and optical tapes, which are assumed to be more severe in terms of bending than optical disks, new materials have been craved because conventional metal thin film materials may crack.

Already, Drexler has proposed using a silver thin film material obtained by developing a wet silver halide photographic material under special developing conditions for an optical card.

However, this material is restricted as a silver salt photographic film, for example, because it uses affinity gelatin as a binder, and it has been pointed out that the material is, for example, weak for long-term storage under high humidity.

Further, in the material using this wet silver halide film, the shape of the silver fine particles is controlled so that the reflection layer and the absorption layer are formed, and there is a problem that delicate manufacturing conditions are required. .

(Problems to be Solved by the Invention) The present invention is intended to provide a recording material which is extremely excellent in storage stability which has been regarded as a problem in this type of recording material.

In particular, it is intended to provide an optical recording material layer which is not damaged by cracks even under severe use conditions such as bending and hardly deteriorates even under severe storage conditions of high temperature and high humidity.

Another object of the present invention is to provide a low-cost recording material whose serial production is severe. That is, a very common industrial production means such as continuous coating by a roll coater or continuous heating by a hot roll can be selected, and an appropriate preformat can be provided as necessary by performing pattern exposure through a mask. . This is a very important issue in reducing the cost of the recording material.

In addition, it is extremely useful from the viewpoint of manufacturing that the metal silver-containing layer can be formed into a substantially simple layer of one kind.

(Means for Solving the Problems) A photosensitive material containing an organic silver salt oxidizing agent as a main material for forming a silver image is known as a so-called heat-developable silver salt photographic film. A completely new optical recording material was found based on the above, and the present invention was completed.

That is, the present invention provides: The reflectance of a metal silver-containing layer obtained by reacting silver ions supplied from an organic silver salt oxidizing agent with a reducing agent in the presence of silver or a metal development nucleus which is more noble than silver. Is 10 to 90
% Of the optical recording material.

The optical recording material according to the above, which is preformable by pattern exposure containing photosensitive silver halide microcrystals.

A process for producing an optical recording material as described above, wherein the organic silver salt oxidizing agent, a reducing agent for this purpose, and a trace of metal development nucleus noble than silver metal are heated to a temperature of at least 70 ° C.

A recording method for recording information by irradiating a pulsed laser beam onto the optical recording material described above to cause a change in reflectance.

 Hereinafter, the present invention will be described in detail.

The optical recording material of the present invention is particularly effective when the organic silver salt oxidizing agent and the reducing agent do not react by thermal development when no development nucleus is present, and only when silver or a metal development nucleus which is more noble than silver is present. Using this as a catalyst nucleus, the organic silver salt oxidizing agent and the reducing agent react to form metallic silver (fine particles) (including claim 1).

That is, by containing an appropriate reducing agent in the system and setting appropriate development conditions, the formation of silver fine particles inside during heating (such as the so-called thermal development of a heat-developable silver halide photographic film) is substantially achieved. It is completely novel that the organic silver salt oxidizing agent inside is diffused to the surface without causing it, and a reflective thin film layer composed of reactive metallic silver fine particles can be formed on the surface.

Therefore, the organic silver salt-containing layer itself can remain as a substantially transparent layer after the supply of silver ions.

Such a novel optical recording material of the present invention can be defined as follows.

That is, in the presence of silver or a metal development nucleus which is more noble than silver, the reflectance of the metal silver-containing tank obtained by the reaction of silver ions supplied from the organic silver salt oxidizing agent with the reducing agent is reduced.
The optical recording material is 10 to 90%.

In this case, each layer of the reflective metallic silver-containing layer and the substantially transparent organic silver salt supply layer in this optical recording material has a clear boundary, or at least, as an optical recording material. Not important. However, in order to improve the recording density as an optical recording material, metallic silver is present as being dispersed uniformly as a dispersion at least much smaller than 2-3 μm, or as a uniform continuous layer in the order of 2-3 μm. It is preferably a metal silver-containing layer that can be handled.

The value of the reflectance is represented by the intensity ratio of the light reflected at a regular reflection angle (-75 °) with respect to the light incident on the optical recording material at an angle of 75 °.

For the measurement of the reflectance, a light source in the vicinity of 750 to 850 nm is used.

Further, in the present invention, it is desirable that the organic silver salt supply layer itself is substantially transparent even after the supply of silver ions, and the transmittance at the light wavelength (750 to 850 nm) used for the measurement of the reflectance is low.
75% or more, preferably 85% or more is desirable in terms of system construction.

The thickness of the recording layer itself including the organic silver salt supply layer of this optical recording material is preferable from the viewpoint of improving the recording density as thinner as possible, as long as a difference in reflectance is obtained,
Usually, the total thickness is set to about 1 to 20 μm.

Also, the larger the value of the reflectivity, the easier the detection system construction is. However, if the reflectivity is high, the laser power cannot be effectively absorbed.
%, 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 dissolving an organic silver salt oxidizing agent and a reducing agent therefor,
After being uniformly coated on a suitable base film, it is prepared by drying.

As the organic silver salt oxidizing agent for this purpose, silver salts of various carboxylic acids, such as long-chain fatty acids, silver saccharinate, silver benzotriazole and the like can be used. Among them, 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 films is bonded, and the hydroxyl group is sterically converted. You can choose from hindered phenols that are impaired.

For example, 2,6-di-t-butyl-4-methylphenol, 2,2'-methylenebis- (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t -Butylphenol), 2,2,4-trimethylpentylbis- (2-hydroxy-3,5-dimethylphenyl) methane, 2,5-di-t-butyl-4-methoxyphenol, and the like. Also, reducing agents for silver salts such as hydroquinone, 2,5-dimethylhydroquinone, chlorohydroquinone, p-aminophenol, methylhydronaphthalene, phenidone, methyl gallate,
Bisphenol A, 2,4-dihydroxybenzoic acid, p-
Methoxyphenol can also be used.

The amount of the reducing agent varies depending on the type of the reducing agent and the like, but is generally about 0.01 to about 1 mol per mol of the organic silver salt oxidizing agent.
It is 10 moles, preferably about 0.1 to about 3 moles.

The organic silver salt oxidizing agent and the reducing agent are previously used in alcoholic solvents such as methanol and ethanol, ketone solvents such as 2-butanone and acetone, ester solvents such as ethyl acetate, and aromatic hydrocarbon solvents such as toluene and xylene. And an organic synthetic polymer compound or an organic natural polymer compound are mixed and dispersed to prepare a uniform coating solution.

Here, the selection of the polymer compound as the binder is as follows.
It is important not only for preparing a coating solution having good stability, but also for greatly affecting the storage stability of an optical recording material obtained after coating drying and heat development.

In particular, in order to provide more favorable stability under high humidity storage conditions, affinity binders such as gelatin and polyvinyl alcohol should be avoided.

Preferred binders in the present invention are 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. it can. The hydrophobic binder is from about 10: 1 to about 1:10 by weight to the organic silver salt oxidizing agent.

In the present invention, the reflective metallic silver-containing layer is formed as follows. That is, it can be obtained by providing a layer of a metal development nucleus which is more noble than silver on the previously coated organic silver salt layer.

This typical preparation method can be performed in exactly the same manner as the method of providing a metal nucleus by electroless plating. For example, a metal nucleus of palladium is applied to the surface layer by sequentially immersing in an aqueous solution of stannous chloride and an aqueous solution of palladium chloride.
No change in appearance occurs before and after this processing.

When the 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 are 90 to 140 ° C. for about 20 to 30 seconds. These development conditions must be controlled to optimal conditions to satisfy the constitution of the present invention.

In particular, care must be taken because excessive development leads to the formation of unnecessary silver particles in the organic silver salt-containing layer and the non-uniformity of the reflective metallic silver-containing layer.

The metallic silver-containing layer incorporates a trace amount of metal development nucleus noble than silver, and a metal development species nobler than silver that acts catalytically is essential for the expression of this reflective layer.

Palladium, platinum,
Gold, rhodium, ruthenium, thallium, mercury and the like can be mentioned. These metal nuclei need not be a single metal species, but may be a composite system or a sulfide.

Further, as a method of giving a metal species which is more noble than silver to the surface layer, a method of dispersing these minute metal development nuclei in a solvent containing an appropriate binder and coating the fine particles on the surface layer as a second layer, or vapor deposition It is also possible to adopt a method of forming a small amount of metal development nuclei on the surface under the gas phase conditions such as described above.

Further, more simply, it is possible to use the silver metal nucleus itself as a catalyst nucleus. In this case, instead of using the metal species noble than silver, the organic metal is oxidized with a stronger reducing agent such as ascorbic acid. It can be substituted by covering the surface of the silver salt oxidizing agent layer.

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

In addition, the surface is exposed to a reducing gas such as hydrogen gas for a short time,
Silver metal development nuclei may be provided on the surface layer.

In some of such techniques, physical phenomena in photographic chemistry are successfully performed on a surface layer by a heat development method to form a metallic silver-containing layer.

The optical recording material of the present invention can contain various additional components to improve the performance of the target material. For example, for the purpose of controlling silver metal to a predetermined size, a toning agent such as phthalazone in a dry silver salt photographic film, an anti-fogging agent, and a sensitizer can be added.

Among the by-products formed by the reaction between the organic silver salt oxidizing agent and the reducing agent, an organic compound such as a fatty acid formed from a silver salt of a long-chain fatty acid plays a role of a plasticizer in a binder. To control writing sensitivity.

Further, in the present invention, it is possible to incorporate photosensitive silver halide into the recording material by applying the technique of dry silver salt, and by such a compounding, it is possible to carry out pattern exposure through a mask beforehand during production. It has been found that a preformatting process in which a track guide, a track number, a speed adjustment signal, and the like are recorded in advance can be easily performed (including claim 2).

Such a change in composition can be achieved by reacting a part of the organic silver salt oxidizing agent with a halogen ion source and changing part of the organic silver salt oxidizing agent to photosensitive silver halide in advance, or by separately preparing There is a method in which the deposited silver halide microcrystals are dispersed 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. The protective layer is selected from organic polymer compounds having good transparency such as polycarbonate, polystyrene, polymethyl methacrylate, polyvinyl chloride, polyvinylidene chloride, and polyethylene terephthalate.

Also, an optical recording material layer is provided on the back surface of the optical recording material layer,
It may consist only of the base film to be applied, and may further have a reinforcing layer on the back surface against bending and the like.

The optical recording material of the present invention is generally formed in a card shape, but is not limited thereto, and may be in a disk shape or a tape shape.

The optical recording material of the present invention can be recorded by various laser light sources having appropriate power, and typical examples thereof include a He-Ne laser and a semiconductor laser. For example, using a semiconductor laser of about 10 mW, writing can be performed at a speed of about several tens cm / sec with a beam diameter of 2 to 3 μm.

The optical recording material of the present invention, as a so-called write-once type recording material, can be utilized as a material that can be written by a user as needed, and information is written in advance,
It can also be used as a read-only ROM card.

In order to explain the present invention in more detail below, examples thereof will be described, but this does not limit the present invention to examples.

(Example 1) A suspension composed of the following components was prepared.

Hebenic acid 20 g Polyvinyl butyral 18 g Phthazone 2.3 g 2,2'-methylenebis- (4-t-butyl-6-t-
(Butylphenol) 6 g 2-butanone 200 g toluene 60 g This suspension was homogenized by a ball mill for about 12 hours, and then undispersed substances were removed through a filter having an average pore size of 1.5 μm.

The suspension is dried with a small applicator and
A slit having a thickness of μm was selected, uniformly coated on a 125 μm polyester film, and dried at room temperature (the obtained sample is referred to as Sample No. 1).

Next, the sheet of Sample No. 1 was sequentially immersed in the following aqueous solution for 10 seconds, washed with water, and air-dried.

(Sample No. 2) (Aqueous solution 1) 2 g of stannous chloride 100 ml of distilled water 2 ml of concentrated hydrochloric acid (aqueous solution 2) 0.1 g of palladium chloride 200 ml of distilled water 5 ml of concentrated hydrochloric acid The obtained samples were each heated at 130 ° C. for 6 seconds.

Sample No. 1 had almost no change in appearance and had a transmittance of 92%, whereas Sample No. 2 had a metallic gloss on the coated surface layer and had a reflectance of 35%.

Next, a writing test was performed on Sample No. 2 using semiconductor laser light having an emission wavelength of 830 nm (beam diameter 3 μm, emission output 10 mW). When the scanning speed was set to 40 cm / sec and the pulse was transmitted, 3 μm perpendicular to the scanning direction
m, a hole of 3.5 μm was recorded parallel to the scanning direction.

(Example 2) A solution of the following components was spin-coated on the sample of Sample No. 1 in Example 1, and applied so that the applied thickness after drying was 0.6 µm.

Polyvinyl alcohol 10 g Sodium chloroaurate (III) 100 mg Methanol 20 ml Distilled water 500 ml The sample dried at room temperature was further vacuum dried at 50 ° C. for 24 hours.

When the obtained sample was subjected to heat treatment in the same manner as in Example 1, an optical recording material having a reflectivity of 46% was produced. This could be written with a semiconductor laser beam as in Example 1.

(Example 3) A suspension composed of the following components was prepared in a dark room, and an optical recording material was prepared in the same manner as in Sample No. 2 of Example 1 under red light.

Silver behenate 20 g Vinyl chloride-vinyl acetate copolymer 15 g Phthalazone 6 g 2,2'-methylenebis- (4-t-butyl-6-t-
Butylphenol) 10 g Calcium bromide 0.3 g Cobalt iodide 0.4 g 2-butanone 200 g Toluene 50 g The obtained optical recording material is exposed to a 300 W high-pressure mercury lamp for 10 seconds through a chromium mask with a 10 μm pitch and a 2 μm width. Then, the entire surface was immediately heated at 130 ° C. for 4 seconds.

In the obtained optical recording material, a metal reflective layer having a non-glossy portion (light yellow transparent layer, which can be used as a tracking guide) having a pitch of 2 μm in an exposed portion was obtained. This reflectance was 40%.

It was proved that it was writable and readable at a speed of 45 cm / sec by an optical card tester equipped with a 10 mW semiconductor laser.

(Example 4) The sample No. 2 of Example 1, the sample of Example 2, and the sample of Example 3 were stored for one week under a storage acceleration test condition of 70 ° C. and 80% RH, and the degree of deterioration was examined.

Almost no change in appearance such as reflectivity and pit shape was observed, indicating that the optical recording material of the present invention was a material having extremely excellent stability.

(Example 5) In place of sodium chloroaurate (III) of Example 2, samples were prepared using mercuric acetate and hydroquinone at 100 mg each.

Similarly, a sample using potassium diiodic potassium platinate instead of the palladium chloride of Example 1 was also prepared.

All of these samples were found to have a metallic luster surface by heating at 130 ° C. for 5 seconds.

(Effects of the Invention) As described above, the present invention is a novel optical recording material containing an organic silver salt oxidizing agent as a main material for forming a silver image, and therefore has extremely excellent storage stability and has a severe condition such as bending. It has the effect that it is not damaged even under use conditions such as cracks and hardly deteriorates even under severe storage conditions of high temperature and high humidity.

In addition, a low-cost recording material capable of continuous production can be provided. In particular, an appropriate preformat can be provided through a mask, which is effective in reducing the cost of an optical recording material.

Claims (4)

(57) [Claims] (1) The reflectance of a metallic silver-containing layer obtained by reacting silver ions supplied from an organic silver salt oxidizing agent with a reducing agent in the presence of silver or a metal development nucleus which is more noble than silver is obtained. Optical recording material that is 10-90%. 2. The optical recording material according to claim 1, wherein said optical recording material can be preformatted by pattern exposure containing photosensitive silver halide microcrystals. 3. The optical recording material according to claim 1, wherein said organic silver salt oxidizing agent, a reducing agent therefor, and a trace of metal development nucleus noble from silver metal are heated to a temperature of at least 70 ° C. or higher. Manufacturing method to manufacture. 4. A recording method for recording information by irradiating a pulsed laser beam onto the optical recording material according to claim 1 to cause a change in reflectivity.