JPH0316276B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat mode write-once optical recording medium. Prior art and its problems Optical recording media have the characteristics that the recording medium does not deteriorate due to wear and tear because there is no contact between the medium and the writing or reading head.For this reason, research and development of various optical recording media have been carried out. ing. Among such optical recording media, heat mode write-once optical recording media are being actively developed because they do not require image processing in a dark room. Such a heat mode optical recording medium is an optical recording medium that uses recording light as heat, and a part of the medium is melted or removed using laser recording light to form small holes called pits. However, there are devices that record information using these pits and detect the presence or absence of these pits using readout light. As an example of such a pit-forming type medium, one is known in which a recording layer made of a thermoplastic resin and a dye as a light absorber is coated and the resin is melted to form pits. There is. According to research conducted by the present inventors, it has been confirmed that it is possible to write on such a medium again by erasing the pits once formed using erasing light or heat to flatten the entire or part of the surface of the recording layer. ing. By the way, such conventional media have a recording layer of a thermoplastic resin and a dye that are compatible or blended. For this reason, phase separation, dye migration, bleeding, and reagglomeration are likely to occur in the recording layer. These problems occur more easily as the dye concentration increases, so it is not possible to increase the dye concentration in the recording layer, resulting in a low recording rate and low write sensitivity and read S/N ratio. There is. In order to eliminate these drawbacks, the present inventors' research has revealed that it is sufficient to form the recording layer using a thermoplastic resin carrying a dye, and we have previously explained this. is suggesting. By the way, phthalocyanine dyes such as metal phthalocyanine are known as one of the dyes that are stable against heat, light, etc. Therefore, if a recording layer is formed using a thermoplastic resin containing a phthalocyanine dye, it is expected that an optical recording medium with extremely good characteristics will be realized. However, for example KFSchoch, Jr et al, J.
Amer.Chem.Soc.101, 7071 (1979) and G.Meyer
et al., Makromor.Chem., 176, 1919 (1975) and
JBDavison et al, Makromolecules, 11,
186, (1978) etc., the coating properties are poor, the readout S/N ratio is low, and these vary depending on the location, and the S/N ratio due to repeated irradiation with the readout light is low. There is a drawback that the reproduction deterioration of the N ratio is also large. Purpose of the Invention The present invention was made in view of the above-mentioned circumstances, and its main purpose is to provide a film with good coating properties and
It is an object of the present invention to provide a write-once optical recording medium having a recording layer made of a polymer containing a phthalocyanine dye, which has a high readout S/N ratio and little reproduction deterioration. These objects are achieved by the invention described below. That is, it is formed from a styrene polymer having a styrene polymer as the main chain, a phthalocyanine residue in the side chain, and the benzene ring of the phthalocyanine bonded to the benzene ring of the styrene unit of the styrene polymer via -CO-. This is a write-once type optical recording medium characterized by having a recording layer that is a write-once type. Specific Configuration of the Invention The specific configuration of the present invention will be described in detail below. The polymer in the present invention has a phthalocyanine residue in its side chain. That is, a phthalocyanine residue is bonded to the main chain or side chain of the polymer via a linking group as a side chain. In this case, the polymer backbone is a styrene homopolymer or styrene copolymer having styrene units, ie a styrene polymer. At this time, in addition to being easy to synthesize, it has high reflectance, high solubility, and high chemical and physical stability.
It has advantages such as being inexpensive, non-toxic, and having good moisture resistance and microbial resistance. In this way, when the skeleton is a styrene polymer, the phthalocyanine residue is bonded to the benzene ring of the styrene unit via a suitable linking group. In such a case, the bond of the phthalocyanine residue is preferably present in the benzene ring in the phthalocyanine ring. In addition, since it is preferable to form the linking group by bonding a functional group introduced in advance to the phthalocyanine residue to the benzene ring of styrene, it is especially advantageous to use -CO - is a group. On the other hand, the central atom of phthalocyanine is not particularly limited and may be H, but phthalocyanine is usually preferably a metal phthalocyanine in terms of absorption wavelength, and the central metal atom is Li, Na, K, Be, Mg, Ca, Sr, Ba, Sc,
Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo,
W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir,
Ni, Pb, Pt, Cu, Ag, Au, Cd, Hg, Al,
Ga, In, Tl, Si, Ge, Sn, Sb, Te, Ce, Nd,
Sm, Eu, Gd, Tb, Ho, Er, Im, Yb, Lu,
It may be any of Th, U, Np, etc. Further, other ligands may be further coordinated to the central metal atom from above and below the phthalocyanine ring. In addition to the above-mentioned linking groups, the benzene ring of phthalocyanine also contains amino groups, alkyl or arylcarbamoyl groups, alkyl or aryl groups to which a nitro group, a carboxylic acid group, a halogen atom, an alkyl group or an aryl group may be bonded. An oxycarbonyl group, an acid chloride group, etc. may be bonded. Such substituents are present in the molecule from 0 to
Contains about 7 pieces. As mentioned above, the styrene polymer may be a styrene homopolymer or a copolymer, and examples of copolymers include styrene, 2-vinylpyridine, 4-vinylpyridine, and acrylic ester. There are copolymers with , methacrylic acid ester, acrylonitrile, butadiene, vinyl acetate, etc. When the skeleton is a styrene copolymer, there is no particular restriction on the copolymerization ratio, but the copolymerization ratio is usually about 10 moles or less per mole of styrene. Further, the copolymer may be a random polymer or a block or graft polymer. Furthermore, there is no limit to the average number of repeating units in the styrene polymer. Further, the content of phthalocyanine residues in the polymer is usually about 0.1 to 100 mol% of the number of repeating units. Such a polymer of the present invention may be polymerized after bonding a metal phthalocyanine to a monomer unit, but in general, after forming a polymer skeleton, if necessary, via a linking group, Attach phthalocyanine to the skeleton. The specific synthesis method when using styrene polymer as the polymer skeleton is Makromol.chen. 180 2073-2084 1979
, Polymer Preprints, Japan 30 1480 1981, etc. Next, specific examples of polymers will be given, but the present invention is not limited to these. In addition, in the following, M represents the central metal atom of the phthalocyanine, and R represents a substituent bonded to the benzene ring of the phthalocyanine ring.

[Table] The recording layer in the present invention is substantially formed from such a polymer. In order to form such a recording layer, it is generally necessary to apply the coating according to a conventional method, and the thickness thereof is generally as follows.
It is approximately 0.01 to 10 μm. In addition, such a recording layer may contain other polymers or oligomers, various plasticizers, surfactants, antistatic agents, lubricants, flame retardants, stabilizers, dispersants, leveling agents, antibleeding agents, visible Light absorbers, ultraviolet absorbers, infrared absorbers, antioxidants,
Contains water repellent, solubility improver, emulsifier, antifoaming agent, polishing agent, antiblocking agent, softener, slip improver, pinhole prevention agent, yuzu peel prevention agent, antimicrobial agent, etc. Good too. On the other hand, the substrate for supporting such a recording layer is not particularly limited.
Various materials can be used for the material. However, in terms of thermal conductivity, surface properties, mechanical strength, hygroscopicity, warp, etc., various types of glass, various types of tempered glass, various ceramics, polymethacrylic resin, polyacrylic resin, polycarbonate resin, phenol resin, epoxy Various resins such as resin, diallyl phthalate resin, polyester resin, polyimide resin, polyether sulfone, polyether ketone, methylpentene polymer, polyarylate resin, polyolefin, polyphenylene sulfide, nylon, fluororesin, etc. may be used. is preferred. Further, the shape and dimensions of the base body can be varied depending on the intended use, such as a disk, tape, belt, or drum. In this case, the medium of the present invention may have the above-mentioned recording layer on one surface of such a substrate, or may have recording layers on both surfaces thereof. In addition, two substrates with recording layers coated on one surface are used, and the recording layers are placed facing each other with a predetermined gap between them, and the substrate is sealed to prevent dust and scratches. You can also avoid it. In addition, in the above-mentioned medium, a subbing layer such as a metal reflective layer or various resin layers may be provided on the substrate, if necessary, and a recording layer may be provided on this subbing layer. Other subbing layers include various thermoplastic resins,
A coating layer of thermosetting resin, ultraviolet ray or electron beam curable resin, or the like may also be used. Furthermore, a reflective layer, a subbing layer, and a recording layer can be formed in this order on the substrate. Furthermore, the thickness of the recording layer can be designed to be non-reflective. In addition, a guide groove may be provided in the substrate, and a recording layer may be provided on the protrusion and/or in the recess of this groove. Furthermore, a reflective layer, an anti-transmissive film layer, a protective layer, etc. can be provided on the recording layer, if necessary. Specific Effects of the Invention The medium of the present invention is generally irradiated with recording light that is focused in a predetermined manner in a pulsed manner while the medium is running. At this time, due to the heat generated by the phthalocyanine residues in the light-absorbing polymer in the recording layer, the polymer itself melts and deforms, forming pits. The pits formed in this manner are read out by detecting the reflected or transmitted light of the readout light while the medium is running. In such a case, erasing may be performed by heating the whole or a part of the medium, or by irradiating the whole or a part of the medium with erasing light. It is also possible to perform line erasing by scanning the erasing light while the medium is running. By such irradiation with erasing light and heating, the recording layer in the pit forming portion is melted and flattened, and writing can be performed again. Such erasing and rewriting can be repeated many times. Specific Effects of the Invention Since the recording layer of the present invention is composed of the above-mentioned polymer, phase separation, dye migration, and bleeding do not occur, the dye concentration can be increased, and the writing sensitivity and recording rate can be improved. improves. Furthermore, there is little deterioration during playback. Also, there is no scattering of pigment. Furthermore, it has high shelf life and archival properties. In addition, compared to the case of using other phthalocyanine polymers as mentioned above, the coating properties are better, so the readout S/N ratio is high, there is less variation in S/N ratio depending on the location, and playback is easier. Deterioration is also reduced. Since it contains phthalocyanine dye residues, it has high heat resistance and light resistance. Specific Examples of the Invention Hereinafter, specific examples of the present invention will be shown and the present invention will be explained in further detail. Example The above-mentioned exemplified light-absorbing polymers No. 1 to 10 were
Synthesized according to Makromol.Chem. 180 2073-2084. That is, using the corresponding metal phthalocyanine carboxylic acid, converting it into an acid chloride, performing a Friedel-Crafts reaction with the corresponding backbone polymer, introducing phthalocyanine into the styrene unit, and then performing a predetermined reaction to synthesize it. Table 1 shows the number average molecular weight in the polymer, the copolymerization ratio of the styrene polymer (comonomer/styrene), and the phthalocyanine content (mol %). These structures were identified using infrared and visible absorption spectra and chemical analysis. Each polymer obtained in this way was mixed with benzene,
Various media were prepared by dissolving it in DMF, DMSO, etc. and coating it on a 30 cmφ glass substrate to a thickness of 0.6 μm. Separately, for comparison, medium No. 11 was prepared in the same manner using a phthalocyanine polymer having -Pc'-O- as a repeating unit. In this case, Pc′ is an unsubstituted iron phthalocyanine residue, and Fe is
The connecting arms extend above and below the ring. And its number average molecular weight is 50,000. Separately, polystyrene (PS) having a number average molecular weight of 50,000 and iron phthalocyanine MPc were dissolved in a weight ratio of 3:1 to obtain medium No. 12 in the same manner. Each medium in Table 1 thus obtained was focused with a He-Ne laser to a diameter of 1 μm (focusing section output 10 mW),
A pulse train was irradiated. The pulse width was changed, and the pulse width at which pits were formed on the surface of the recording layer was measured, and was taken as the reciprocal of the writing sensitivity (μsec). The results are shown in Table 1 below. Next, writing was performed with the pulse width fixed at 1 μsec. After writing, the He-Ne laser readout light is 1μ
Focused light on mφ (focusing part output 1mW), 300n sec,
Pulse irradiation was performed at a repetition frequency of 100Hz. This reflected light is then detected with a photodiode,
The read S/N ratio (dB) was measured. The results are shown in Table 1. Note that the RMS value (effective value) was used as the noise. Furthermore, after writing, this readout light was irradiated for 1 minute, and the S/N ratio was then measured to evaluate reproduction deterioration. Table 1 shows cases in which there was a change in the S/N ratio after 1 minute as ×, and cases in which there was no change as ○. Also, apart from this, after writing, the medium is 40
The recording was stored for one week at 80% relative humidity, and the S/N ratio after storage was measured to evaluate the recordability. The results are shown in Table 1 with ○ indicating no change at all, △ indicating a slight change, and × indicating significant deterioration.

[Table] From the results shown in Table 1, the effects of the present invention are clear.

Claims (1)

[Claims] 1 Formed from a styrene polymer having a sletin polymer as the main chain, a phthalocyanine residue in the side chain, and the benzene ring of the phthalocyanine bonded to the benzene ring of the styrene unit of the styrene polymer via -CO-. What is claimed is: 1. A write-once optical recording medium, comprising a recording layer.