JPH03218890A - recoding media - Google Patents

Abstract

PURPOSE:To obtain a repeatedly usable recording material having no toxity by forming a fatty acid or fatty acid derivative layer on a hydrophobic layer in a state horizontally oriented or not oriented with respect to the hydrophobic layer. CONSTITUTION:A recording medium is formed by providing a hydrophobic layer composed of a light absorbable substance on a substrate and forming a fatty acid or fatty acid derivative layer as a recording layer in a state horizontally oriented or not oriented with respect to the hydrophobic layer. Herein, the fatty acid or fatty acid derivative is saturated or unsaturated mono- or dicarboxylic acid or a fatty acid salt such as ester, amide, anilide, hydrazide, ureide, anhydride, ammonium salt or metal salt thereof and pref. has an m.p. of 50-200 deg.C, especially, 60-150 deg.C. Saturated or unsaturated fatty acid may be straight chain or branched one and the number of carbon atoms of the hydrocarbon chain in fatty acid is pref. 10 or more.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a recording medium, particularly a write-once optical memory medium,
It can also be used for display.

[Conventional Technology] In recent years, information recording methods using high energy density beams such as laser beams have been developed, and some have already been put into practical use.

An information recording medium basically consists of a substrate made of plastic, glass, etc. and a recording layer provided thereon.

There are three types of optical memory media: read-only, write-once, and rewritable. Among these, the write-once type uses Te as a recording material.
-C, CS2-Te. ．． Pb-Te-Se, TeTi-
One uses layer change using a chalcogen-based compound such as Ag-SeSTeo There are some known types that form pits.

However, the toxicity of chalcogen compounds is a problem, bubble formation and pit formation make it difficult to form a single plate, and an air gap is required, and the reality is that there is still no satisfactory recording material.

[Problems to be Solved by the Invention] The present invention aims to provide a recording medium that uses non-toxic materials and can be used repeatedly.

[Means for Solving the Problems] As a result of the present inventors studying the thermal changes of various organic materials,
It has been found that when thin film-like crystals of fatty acids or fatty acid derivatives are used in the recording layer, the crystal state changes in the areas to which heat is applied.

Furthermore, the present inventors have studied in detail the crystal growth of fatty acids and fatty acid derivatives, and found that when a film of fatty acids or fatty acid derivatives provided on a hydrophobic surface melts, it forms a crystalline state in which the molecular chains are oriented perpendicular to the hydrophobic surface. When forming a film by vapor deposition, the vapor deposition rate may be increased, or
If the substrate is deposited at a low temperature, the molecules arriving on the substrate may not have sufficient time or space for translational or rotational movement, or the molecular motion may be frozen, resulting in molecular chains being disordered or horizontally oriented with respect to the surface. This discovery led to the present invention.

That is, the structure of the present invention is as follows: (1) A recording medium having a recording layer formed by forming a layer of a fatty acid or a fatty acid derivative on a hydrophobic layer in a horizontal orientation or non-orientation with respect to the hydrophobic layer; (2) The recording medium according to item (1) above, wherein the hydrophobic layer is made of a light-absorbing substance.

(3) The above (1) characterized in that a light-absorbing substance is contained in the hydrophobic layer or in a separate layer in contact with the hydrophobic layer.
) is the recording medium described in section 2.

In the present invention, fatty acids or fatty acid derivatives are formed in a random or horizontally oriented layer on a hydrophobic substrate that can be easily oriented vertically, and the layer is locally heated and melted using a laser beam or the like to orient the part vertically. This is how records are made.

Regarding the control of the orientation state of fatty acids and fatty acid derivatives, see, for example, "Surface J Vol. 24, No. 2 (198
fli Inaoka et al.), “Surface J Vol. 2B, No. 1O
It is described in (Okui, 1988).

The recorded state can be confirmed using optical observation means such as a microscope or a polarizing microscope. In particular, such changes in the crystal state are often accompanied by changes in polarization characteristics.
In many cases, it can be clearly observed as a contrast between light and dark or a difference in color tone under crossed nicol conditions using a polarizing microscope.

Therefore, in order to reproduce (read) recorded information, the recording medium is placed so that the focused polarized light is incident on the recording medium, and the reflected or transmitted light is transmitted in the vibration direction perpendicular to the vibration direction of the incident light. This can be done by detecting the intensity of light through a polarizer.

The recording layer of the recording medium of the present invention is a layer containing a fatty acid or a fatty acid derivative as a main component, and the fatty acid or fatty acid derivative here specifically refers to a saturated or unsaturated mono- or dicarboxylic acid, or an ester or amide thereof. , anilide, hydrazide, ureido, anhydride, or fatty acid salts such as ammonium salts or metal salts. In this case, the ester is an ester with a compound having two or more hydroxy groups,
Examples include mono-, di- or triglycerides. Further, these may be substituted with a halogen, a hydroxy group, an acyl group, an acyloxy group, or a substituted or unsubstituted aryl group. These saturated or unsaturated fatty acids may be straight chain ones, and the unsaturated fatty acids may have one double bond or triple bond, or two or more. The number of carbon atoms in the hydrocarbon chain in these fatty acids is preferably 10 or more.

Specific examples of saturated fatty acids include undecanoic acid, lauric acid, myristic acid, pentadecanoic acid, palmitic acid, hebutadecanoic acid, stearic acid, nanodecanoic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melisic acid. Examples of unsaturated fatty acids include oleic acid, elaidic acid, linoleic acid,
These include sorbic acid and stearolic acid.

Specific examples of esters include methyl esters, ethyl esters, hexyl esters, octyl esters, decyl esters, dodecyl esters, tetradecyl esters, stearyl esters, eicosyl esters, and docosyl esters of these fatty acids.

Further, examples of metal salts include metal salts of these fatty acids such as sodium, potassium, magnesium, calcium, nickel, cobalt, zinc, cadmium, and aluminum.

The fatty acid or fatty acid derivative used preferably has a melting point in the range of 50 to 200°C, particularly 60 to 150°C. If it is lower than this, there may be a problem with the preservation of records.
Also, if it is high, the energy required for recording will be large and the recording speed will be slow.

Examples of light-absorbing substances include azo dyes, cyanine dyes, naphthoquinone dyes, anthraquinone dyes, squarylium dyes, phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, indigo dyes,
Infrared absorbing dyes such as dithiol complex dyes, azulenium dyes, quinone imine dyes, and quinone diimine dyes, and metals such as Cr, Ge, Pt, and NiSSisA1 can be used.

Materials forming the hydrophobic layer include silicone resin, polystyrene, vinylidene fluoride resin, vinylidene fluoride-trifluoroethylene copolymer, vinylidene chloride resin, polyethylene, polypropylene, vinyl chloride-vinyl acetate copolymer, and acrylic resin. , polyurethane, polycarbonate resin, various waxes, etc. can be used.

Substrates used in the recording medium of the present invention include glass plates, metal plates, and plastic plates such as polymethyl methacrylate and polycarbonate. However, if the information is to be read using transmitted light after recording, it is necessary to use a substrate that transmits the reproduction light. When reading by reflected light, a film of a metal or semimetal such as platinum, titanium, silicon, chromium, nickel, germanium, or aluminum is provided as a reflective layer, if necessary.

EXAMPLES The present invention will be specifically described below with reference to Examples.

[Example: Cr was vapor-deposited to a thickness of 1000× on a glass substrate to form a light-absorbing material layer. Next, a tetrahydrofuran solution of silicone resin (KR216 manufactured by Shin-Etsu Chemical) was added to Cr using a spinner.
A hydrophobic layer with a thickness of 0.1 μm was provided.

Mo
Using a boat, keep the glass substrate at lO℃ and vacuum degree 5.
The recording layer was deposited at a deposition rate of 20 layers/sec at X 10' Torr to form a recording layer with a thickness of 2000 layers.

While rotating the recording medium thus produced at 90 rpm, a semiconductor laser beam with a wavelength of 830 nm focused to a diameter of 1 μm was applied at a frequency of 200 kHz. Irradiation was performed under conditions of a duty ratio of 50% and an intensity of 6IIIW.

When a recording medium irradiated with laser light is observed in a crossed Nicol state using a reflective polarizing microscope, the unirradiated area is a dark field, but a line-shaped bright field recording area with a width of approximately 1 μM is formed in the laser beam irradiated area of the recording layer. I was able to observe what was happening.

Next, the X-ray diffraction of the unrecorded area and the recorded area (irradiated with laser beams so as to overlap each other) was measured. The results are shown in FIGS. 1 and 2. In the unrecorded area, the diffraction peaks caused by the (110) plane appear strongly, indicating that there are horizontally oriented areas. On the other hand, in the recording section 2
The peak at θ = 21.6° disappears, and only the diffraction peaks (0051) (but -2.3, 4, 5.7) due to the long plane spacing appear, and the recording part is stearic acid. This indicates that they are vertically oriented. Therefore, it can be understood that the recording is based on changes in the state of stearic acid.

[Effects of the Invention] As explained above, the recording medium of the present invention is non-toxic and
Moreover, it can be used repeatedly.

[Brief explanation of drawings]

1 and 2 are X-ray diffraction diagrams of the unrecorded area and the recorded area of the recording medium of Example 1, respectively.

Claims (2)

[Claims] (1) A recording medium characterized in that a recording layer is formed by forming a layer of a fatty acid or a fatty acid derivative on a hydrophobic layer in a horizontal orientation or non-orientation with respect to the hydrophobic layer. (2) The recording medium according to claim (1), wherein the hydrophobic layer is made of a light-absorbing substance. (3) The recording medium according to claim (1), wherein a light-absorbing substance is contained in the hydrophobic layer or in a separate layer in contact with the hydrophobic layer.