JPH0371888A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical recording medium having high sensitivity to light in a near infrared region, increased in solvent solubility, showing high reflectivity, having no toxity and also excellent in durability by forming an org. membrane based on a specific naphthalocyanine compound on a substrate. CONSTITUTION:An optical recording medium is constituted by forming a naphthalocyanine compound represented by general formula I (wherein at least one of Y1 and Y2 is a group represented by formula II) on a substrate. The optical recording medium wherein the specific naphthalocyanine compound is formed on the substrate as the membrane satisfied sensitivity in a near infrared region, reflectivity and durability and is useful as a medium for recording and reproduction using various lights such as an optical disk, an optical card or a tape. So far as the purpose is not damaged, a stabilizer, a lubricant, an antistatic agent, a high-molecular compound as a binder, other dye and a sensitizer may be used together with the naphthalocyanine compound. The material of the substrate to be used must be transparent to laser beam when writing recording is performed on the side of the substrate by laser beam.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of industrial application) The present invention relates to an optical recording medium, particularly an optical recording medium having an organic recording layer for a semiconductor laser having absorption in the near-infrared region.

(Prior Art) In recent years, the development of semiconductor lasers has been remarkable, and small and stable oscillators have become available at low cost and have begun to be used as light sources for various recording devices. However, the wavelengths of these semiconductor lasers are limited to relatively long wavelengths, and semiconductor lasers capable of oscillating short wavelength light have problems in terms of lifespan, output, etc.

Therefore, as a recording medium for semiconductor lasers, it is essential to use a material that absorbs in the near-infrared region as a thin film layer.
Materials with a maximum absorption wavelength of 750 μm or less are often inappropriate. Conventionally, as this type of recording medium, there is one in which a thin film formed on a substrate is irradiated with a laser beam to form bits, and recorded information is read out based on the difference in reflectance between the bits and the non-bit parts. This recording and playback (reading)
The recording layer for this purpose may have two or more layers consisting of a recording thin-film RFC layer and a reflective film, but it is advantageous to have only a recording thin-film layer that has both of the above-mentioned functions.

In the case of a single-layer film for this recording thin film layer, it is necessary that the material of the recording thin film layer itself has a high reflectance in order to obtain a high C/N ratio. As a recording medium for this keyaki,
Inorganic materials using low melting point metals such as Te or alloys thereof are known, and organic materials using cyanine dyes and phthalocyanine compounds are known.

(Problems to be solved by the invention) Inorganic optical recording media using Te-based alloys have relatively high sensitivity, but they have problems with toxicity, and the film formation method uses sputtering, etc., so equipment costs are high. However, it also has the disadvantage of low productivity. Organic thin-film optical recording media using cyanine dyes have the advantage of being able to be produced using relatively inexpensive methods such as spin coding, but they are not satisfactory in terms of performance, such as storage stability (durability). The current situation is that this state has not been reached. Furthermore, in the case of naphthoquinone and anthraquinone, they have poor solubility in solvents and have storage stability problems such as the formation of agglomerated structures. Furthermore, phthalocyanine compounds are also unsatisfactory due to their solvent solubility, semiconductor laser matching properties, and crystal changes during storage.

(Means for solving the problem) A method for recording and reproducing optical recording media that is highly sensitive to light in the near-infrared region, has high solvent solubility, high reflectance, is nontoxic, and has excellent durability. In order to provide a thin film material and thereby an excellent optical recording medium, the present invention was arrived at as a result of intensive studies. That is, the present invention is an optical recording medium characterized in that an organic thin film containing a naphthalocyanine compound as a main component shown in the following configuration [1] is formed on a substrate.

(However, in formula [1], M is S'1.Sn, G.

X represents an element selected from halogen, alkyl group, aryl group, acyl group, amino group, substituted amino group, nitro group, alkoxy group, sulfonic acid group, sulfonylamide group, and hydroxy group. , represents one or more groups which may be the same or different, p represents the number of O~2, q represents the number of 0~4, Yl and Y2 may be the same or different, but Y, and Y2 At least one of them is the formula [
2], where in formula [2], n represents a number of O to 10, R1 to R7 are groups that may be the same or different, and include a halogen, a hydroxy group, and a group having 1 to 10 carbon atoms. 12 alkyl group or alkoxy group, an aryl group having 6 to 10 carbon atoms, a cycloalkyl group having 4 or more carbon atoms, or a substituted product thereof. ) The optical recording medium in which the specific naphthalocyanine compound of the present invention is formed as a thin film on a substrate satisfies all of the sensitivity, reflectance, and durability in the near-infrared region, and is suitable for optical discs, optical cards, tapes, etc. It is useful as a medium for recording and reproducing using various types of light.

A stabilizer, a lubricant, an antistatic agent, a polymer compound as a binder, another dye, or a sensitizer may be used in combination with the naphthalocyanine compound as long as the object of the present invention is not impaired. The substrate material used in the present invention may be transparent or opaque to the laser beam used, but if writing and recording is performed using the laser beam from the substrate side, it must be transparent to the laser beam.

Examples of these substrate materials include glass, acrylic resin, methacrylic resin, polyester resin, nitrocellulose resin, polyamide resin, polycarbonate resin, polymethylpentene-1 resin, epoxy resin, vinyl chloride resin, polyvaraphenylene resin, etc. . These resins are in the form of sheets, films, disks, etc., and if necessary, these resins may have an undercoat layer or a layer coated with a specific metal. good.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, the measurement and evaluation of characteristics in Examples were as follows.

A spectral naphthalocyanine compound was dissolved in ethanol to a concentration of 1.5%, and a thin film of 70 nm thick was formed on a glass substrate using a spin coater. The absorption and reflection spectra of this were measured using a UV-VIS spectrometer (Shimadzu UV21 OA). From this, the reflection $ (R%) of 830n■ was determined.

The recording medium obtained above was irradiated with an 830 nm semiconductor laser at an optical power of 71 nm and a lens diameter of 1 am to write in the concave portion of the track. , 5 mW) as the read light, the write light pulse width at which the C/N ratio of the reflected light was 50 dB or more was measured, and the reciprocal of the sensitivity was calculated.

After irradiating the above recording medium at 63° C. for 300 hours using a Cyshine carbon arc fade meter, the reflectance and C/N ratio were measured to examine deterioration.

The recording medium obtained above was heated at 70°C and 90%RH for 3 hours.
The reflectance and C7N ratio were measured after storage for several months.

Put 1.5 g of a naphthalocyanine compound in a test tube with a stopper, add 5 w, Q of ethanol, and after sealing the cap, heat at 60℃ for 3 hours.
It was dissolved by applying ultrasound for 0 minutes. Then bring it to room temperature and
After standing for a period of time, it was filtered and the soluble content was measured to determine the solubility.

(Example) Naphthalocyanine compounds corresponding to the following experimental orders were dissolved in ethanol and coated onto a glass substrate using a spin coater to a solid content thickness of 70 nm. Various characteristics and performances of each of the obtained samples were evaluated. The results are shown in Table-1. However, in the formula, Me represents a methyl group, Et represents an ethyl group, and t-Bu represents a tertiary-butyl group.

Hereinafter, Yokobosu 2 Positive 6 (Comparative example) Y,, Yt= -8u 1e Has a3 A4 Tori 7 (Comparative example) Yr+ Yx'' (Effect of the invention) Thin film containing the specific naphthalocyanine compound of the present invention as a main component The optical recording medium formed on the substrate has well-balanced properties required for an optical recording medium in terms of solubility, reflectance, reciprocal of writing sensitivity, and read C/N ratio. It was also found that the durability is excellent.On the other hand, even if a similar naphthalocyanine compound is used, if it is not represented by the general formula of the present invention, it can be used as an optical recording medium. It was found that both materials were inferior in terms of mechanical properties and were of little practical use.

Claims (1)

[Claims] (1) An optical recording medium characterized by forming a thin film containing a naphthalocyanine compound represented by the following general formula [1] as a main component on a substrate. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [1] (However, in formula [1], M is S_i, S_n, G
_e represents an element selected from halogen, alkyl group, aryl group, acyl group, amino group, substituted amino group, nitro group, alkoxy group, sulfonic acid group, sulfonylamide group, and hydroxy group. In addition, it represents one or more groups which may be the same or different, and p is 0 to
2, q indicates a number from 0 to 4, and Y_1 and Y_2 are
Although they may be the same or different, it indicates that at least one of Y_1 and Y_2 is a group represented by formula [2], provided that in formula [2], n represents a number from 0 to 10, and R^1 ~
R^7 can be the same or different groups, such as halogen, hydroxyl group, ▲numerical formula, chemical formula, table, etc.▼[2] Alkyl group or alkoxy group with 1 to 12 carbon atoms, aryl group with 6 to 10 carbon atoms , represents a cycloalkyl group having 4 or more carbon atoms or a substituted product thereof. )