JPH0416839A - New recording material - Google Patents

Abstract

PURPOSE:To enhance sensitivity by forming a layer of fine metal particles on a lustrous layer of metallic silver formed by bringing a silver compd. into a reaction in the presence of developing nuclei or silver or a nobler metal than silver. CONSTITUTION:Developing nuclei of silver or a nobler metal than silver are formed on a layer contg. a silver compd., a reducing agent and a binder as a layer of a compsn. forming an optical recording material and the silver compd. is brought into a reaction by heating under proper conditions for several sec to several min to form a reflective lustrous layer of metallic silver as a surface layer. In order to form this lustrous layer, the catalytically acting developing nuclei are indispensable. A layer of fine metal particles is further formed on the lustrous layer. At this time, any method may be adopted. Sensitivity is enhanced and CN ratio is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention provides a new digital recording material suitable for writing and reading mainly with laser light.

[Conventional technology]

BACKGROUND ART In recent years, racer-related technology has made remarkable progress, and as information becomes increasingly digitalized, various new optical recording materials necessary for this progress have been proposed.

An optical disc is a typical digital recording material. Optical disks using dyes have attracted attention and are being developed because they have the advantage of being inexpensive to manufacture. Furthermore, a write-once compact disk using a dye and having a high reflectance has been proposed, as disclosed in Japanese Patent Application Laid-Open No. 64-40388, and is attracting attention. Also,
Apart from this, a high-density optical card that can be carried around at all times has been proposed as a device that can be easily handled. Examples of this include JP-A-59-502139 and JP-A-58.
A well-known example is the optical card developed by Drexler, which is described in Publication No. 188346. Additionally, various companies are developing optical card materials using materials similar to those used for optical disks. 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, the characteristics necessary for recording materials, such as writing sensitivity, storage stability of recording materials, recording density, and error rate, are still insufficient. Therefore, the present inventors have discovered JP-A-2-7438, which has excellent storage stability under high temperature and high humidity conditions and can be used satisfactorily as an optical recording material even under usage conditions such as bending.
We have previously proposed a material with a metallic silver luster layer, which is described in Publication No. 9 and the like.

[Problem that the invention seeks to solve]

By increasing the sensitivity of this recording material, the burden on the laser can be reduced and recording can be performed at high speed. Therefore, improvement in sensitivity is highly desired.

[Means to solve the problem]

Utilizing the fact that a silver compound undergoes a reduction reaction when heated, the reflective metallic silver gloss layer is formed from metallic silver fine particles and a hydrophobic binder.

It has been found that when metal fine particles are further formed on this reflective metallic silver gloss layer, the sensitivity is increased, the noise level of the CN ratio is lowered, and the CN ratio is improved.

The present invention provides an optical recording material in which a metal fine particle layer is further formed on a metallic silver luster layer formed by reaction of a silver compound in the presence of silver or a metal nobler than silver, and a recording method thereof. .

The reflective metallic silver gloss layer of the present invention is manufactured as follows. That is, metal development nuclei are formed on a layer containing a silver compound, a reducing agent, a binder, etc. (optical recording material composition layer) that has been applied in advance, and further under suitable heating conditions, for example, at a temperature of at least 70°C. When heated for several seconds to several minutes, a reflective metallic silver luster layer is formed on the surface layer. In order to form this reflective metal silver-containing layer, metal development nuclei that act catalytically are essential.

The silver compounds include organic silver salts and carboxylic acid silver-containing polymers, and the following three types are preferable examples thereof. That is, (1) a silver salt of a long-chain fatty acid, (2) an organic solvent-soluble silver compound, and (2) a silver carboxylic acid-containing polymer. Silver salts of long-chain fatty acids include silver salts of stearic acid,
Particularly useful are the silver salts of hehenic acid. However, other non-photosensitive silver salts such as silver saccharate, silver benzotriazole, etc. can also be used. The organic solvent-soluble silver compound is selected from among aliphatic carboxylic acid silver salts and silver metal chelate compounds that are soluble in organic solvents. For example, as a preferred silver aliphatic carboxylate, a fluorine-containing silver aliphatic carboxylate is used, and as a silver metal chelate compound, a fluorine-containing chelate represented by fluorine-containing β-diketones is used. A curing agent is used. Particularly preferred compounds include silver trifluoroacetate, silver hexafluorobutyrate, silver perfluorooctanoate, silver trifluoromethanesulfonate, silver furoyl trifluoroacetonate, silver hexafluoroacetylacetonate, and silver hexafluoroacetylacetonate. Mention may be made of butafluorobutanoyl pivanoyl methanate, silver pivaloyl trifluoroacetonate, silver pivaloyl trifluoroacetylacetonate, and dilbacenoyl trifluoroacetonate.

The silver carboxylic acid-containing polymer can be synthesized from a natural or synthetic polymer compound having carbonic acid in the side chain of the polymer. Among these, particularly useful silver carboxylate-containing polymers include silver salt compounds derived from natural products such as silver alginate and silver pectate, and silver compounds derived from synthetic polymers such as silver polyacrylate and silver methacrylate. You can choose from. Regarding synthetic polymers, copolymers with various monomers such as acrylic acid, methyl methacrylate, acrylonitrile, vinyl chloride, and vinyl acetate can be used as bases for silver-containing polymers, and are particularly useful.

Any reducing agent for the silver compound may be used as long as it can reduce the silver compound. however,
Those that self-reduce by heat etc. do not necessarily require a reducing agent. Preferred reducing agents include, for example, inhibiting phenols in which a sterically bulky group is bonded to the carbon adjacent to the carbon to which the hydroxyl group is bonded, sterically inhibiting the hydroxyl group, such as 2,6-sheet t -butyl-4-methylphenol, 2,2'-methylenebis-(4-methyl-6t-
butylphenol), 2,2'-methylenebis-(4-
ethyl-6-t-butylphenol), 2.4.4-trimethylpentylbis-(2-hydroxy-3,5-dimethylphenyl)methane, 2.5-di-t-butyl-4
-methoxyphenol, 2-t-butyl-6-(3-t
-butyl-2-hydroxy-5-methylbenzyl)-4
-Methylphenyl acrylate, 4.4'-butylidene-bis(3-methyl-6-t-butylphenol, triethylene glycol-bis-[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate) ], 1,6-hexanethiol bis(3-(3,5
-di-t-butyl-4-hydroxyphenyl)propionate), 2,4-bis-(n-octylthio')-6
-(4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, pentaerythrityl-
Tetrakis-[3(3,5-di-t-butyl-4-hydroxyphenyl)propionate), 2,2-thiodiethylenebis-[3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl
3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,2-thiobis-(4-methyl-6-t-butylphenol), N.

N'-hexamethylenebis-(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 3,5-di-t-butyl-4-hydroxypencylphosphonate diethyl ester, 1,3.5 trimethyl-2,4
, 6-) Lis-(3,5-di-t-butyl-4-hydroxybenzyl)benzene, Bis-(3,5-di-t-butyl-4-hydroxybenzylethyl)calcium, Tris(3,5- di-t-butyl-4-hydroxyhensyl)-isocyanurate, N,N'-bis-
Examples include [3(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine. Also, reducing agents for silver salts such as hydroquinone, 2,5-dimethylhydroquinone, chlorohydroquinone, p-aminephenol, methylhydronaphthalene, phenidone, methyl gallate, p-phenyldenol, bisphenol A, 2,4-dihydroxybenzoin, etc. The acid p-methoxyphenol can also be used. The amount of reducing agent is
It varies depending on the type of reducing agent, etc., but for boat fishing, it is about 0.0% per mole of silver compound. O1 mole is 10 moles, preferably about 0.1 mole to about 3 moles.

Preferred binders in the present invention include polymethyl methacrylate, polyvinyl formal, polyvinyl butyral, vinyl chloride-vinyl acetate copolymer, cellulose acetate, polystyrene, styrene-methyl methacrylate copolymer, styrene-butyl acrylate copolymer, and styrene-butyl acrylate copolymer. It can be appropriately selected from a wide range of hydrophobic organic polymer compounds such as methyl methacrylate-methyl acrylate copolymer. The hydrophobic binder is present in a weight ratio of from about 1 to about 1 O to about 1 to about 1 O to the organic solvent soluble silver compound.

The metal development nucleus is silver or a metal species nobler than silver. Metals more noble than silver include palladium, platinum, gold,
Examples include rhodium, ruthenium, thallium, and mercury. These metal nuclei may be a single metal species, or may be a composite system or a compound such as silver sulfide or silver oxide.

The method for forming metal development nuclei on the surface of the optical recording material composition includes a method in which the metal development nuclei are dispersed in a solvent containing a suitable binder and coated on the surface of the optical recording material composition, or a method such as vapor deposition. It is also possible to form metal catalyst nuclei on the surface under gas phase conditions. Alternatively, metal development nuclei made of the metal species itself may be formed on the surface by coating the surface with a strong reducing agent or by exposing the surface to a reducing residue such as hydrogen gas for a short period of time. For example, a typical manufacturing method is to immerse the metal in a stannous chloride aqueous solution and a palladium chloride aqueous solution sequentially and apply a metal nucleus of palladium to the surface layer using electroless plating. , a method in which metals such as platinum, gold, silver, palladium, etc. are vacuum-deposited on the surface. Further, a compound that forms silver sulfide nuclei, such as sodium sulfide, may be disposed on the surface layer. Alternatively, copper metal development nuclei may be provided on the surface by exposing the surface to a reducing gas such as hydrogen scum for a short time. It is necessary to select an appropriate forming method depending on the type of silver compound, binder, etc.

When an optical recording material composition 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 reflective metallic silver-containing layer can be formed on the surface. .

Appropriate heating conditions are preferably 90 to 180°C and about 5 to 1,000 seconds. These heating conditions must be controlled to optimal conditions in order to satisfy the structure of the present invention. In particular, care must be taken because excessive development tends to cause the reflective metallic silver-containing layer to become non-uniform.

The optical recording material of the present invention can contain various additive components to improve the intended performance of the material. For example, it is possible to introduce a compound that controls the size of silver particles in the metallic silver-containing layer. Examples include toning agents such as phthalazinone used in dry silver salt photosensitive materials. Further, antifogging agents, sensitizers, etc. can be added as needed.

Any method may be used to form the metal fine particle layer on the metallic silver luster layer as long as it can form metal fine particles. Here are some examples: A metal fine particle layer can be formed by vacuum evaporation or sputtering under conditions that allow island-like growth. In addition, when bonding via an adhesive to form a protective film on this metallic silver glossy layer, it is possible to further form metal fine particles on the surface of the metallic silver glossy layer by dispersing metal fine particles in the adhesive. I can do it. Alternatively, fine metal particles may be dispersed in a solvent and applied to the metallic silver gloss layer using a spin cord or the like. In addition, the surface of the metallic silver glossy layer is heated by a heater or laser irradiation to sinter the silver fine particles in the silver fine particle layer on the surface, thereby forming a metallic silver glossy layer consisting essentially of silver fine particles or a hydrophobic binder and silver fine particles. Silver fine particles may be formed thereon.

Metals that can be used as fine metal particles include silver, gold, copper, tellurium, bismuth, palladium, cobalt,
Nickel, lead, chromium, titanium, etc. can be raised. Alternatively, an alloy containing the above metals as a main component may be used.

The size of metal fine particles is usually lnm or more 100r
Used below +m. It is difficult to produce fine particles smaller than 1 nm, and 1) fine particles larger than 00 nm cause extremely poor reflectance.

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

In that case, a method can be used in which fine metal particles are formed on the coated substrate and then a metallic silver luster layer is formed thereon, which essentially means that the metallic fine particles are present on the metallic silver lustrous layer. It is a recording material. In addition, even if the back side of the optical recording material consists only of a base film on which the optical recording layer is applied, there is also a reinforcing layer on the back side to prevent deterioration and scratches caused by bending and to protect from moisture. It's okay.

Further, the surface of the transparent protective layer is usually treated to make it less likely to be scratched.

The shape of the present invention may be a cart shape, a disk shape, or a tape shape.

The optical recording material of the present invention can be recorded with a variety of laser light sources having appropriate power, representative examples of which are He Ne lasers and semiconductor lasers. For example, it is possible to write at a speed of about 1 mb's with a beam diameter of 1 μm using a semiconductor laser of about 5 mW.

The optical recording material of the present invention can be used as a so-called write-once type recording material, and can be written on by the user as needed, but once written cannot be erased, it can be used for necessary purposes such as evidence. You can also use it.

In addition, you can write information in advance to a read-only RO.
It can also be used as an M cart.

Examples will be described below to explain the present invention in more detail, but the present invention is not limited thereto.

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

Silver trifluoroacetate 21g 2.2-methylenebis(4-ethyl-6-t-9g butylphenol) 2-butanone 192g toluene
62g 1 root of methylmethac to 1 root of butyl ac
22 g copolymerized This solution was homogenized by stirring for about 1 hour, after which the average pore size was 1. Passed through a -5 μm filter.

This solution was dried on a polyethylene terephthalate film with a film thickness of 100 μm using a small blade coater.
Coating was carried out under conditions such that the thickness of the film was 10 μm.

Thereafter, it was dried at a temperature of 22° C. and a humidity of 50% R1.

Thereafter, metal development nuclei, that is, palladium nuclei, were formed on the coated surface using the following catalyst nucleus forming method for electroless plating manufactured by Nippon Schering Co., Ltd. The coated layer was sequentially immersed in the following aqueous solutions for 10 seconds each, then washed with water and air-dried.

(Aqueous solution 1) Activator Neogant 834 40 d (Nippon Schering Co., Ltd. trade name) Distilled water 956- Sodium hydroxide 3 g (Aqueous solution 2) Reducer - Neogant WA 5J (Nippon Schering Co., Ltd. trade name) Boric acid
5g distilled water 950 - When the obtained sample was heated at 150°C for 450 seconds, silver was precipitated on the surface and a metallic silver luster layer was formed.

Next, silver, gold, copper, and palladium were individually deposited on the metallic silver gloss layer by vacuum evaporation to a thickness of 7 nm as measured by a film thickness meter using a quartz crystal. Gold and silver were also codeposited under the same conditions. Thereafter, a 1.2M thick polycarbonate substrate was placed on it, and the CN ratio was measured. The measurement conditions for the CN ratio are a wavelength of 830nfl;
N, A, 0.5, recording speed 1 m/s, recording power 10 mW, bandwidth 10 Kf (z). The results are shown in Table 1.

Comparative Example 1 A sample was prepared in exactly the same manner as in Examples 1 to 5. However, this is a sample that does not form a metal fine particle layer. The results are also shown in Table 1.

Examples 6-7 Samples were prepared in the same manner as Examples 1 to 5.

However, the metal fine particle layer was formed by dispersing metal fine particles in 2-butatol and using a spin coating method.

The metal fine particles used were gold and silver fine particles having an average particle size of 30 nm.

(The following is a blank space) It can be seen from the Examples and Comparative Examples in Table 1 that the present invention is effective.

〔Effect of the invention〕

According to the present invention, it is possible to provide a highly sensitive and stable material and a recording method thereof. This reduces the burden on optical systems such as semiconductor lasers, and allows for faster recording.

Claims (2)

[Claims] (1) An optical recording material in which a metallic fine particle layer is further formed on a metallic silver luster layer formed by reaction of a silver compound in the presence of silver or a metal nobler than silver development nuclei. (2) A method for recording information by irradiating the optical recording material according to claim (1) with pulsed laser light.