JP2004234821A - Optical information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information recording medium on the label surface side of which visible information can be recorded by irradiation of a low output laser beam using a laser device for recording/reproducing electronic information without exerting a thermal influence and the like to the electronic information recorded on the medium. <P>SOLUTION: In the optical information recording medium 100 which has a substrate 101 and an electronic information recording layer 102, a reflection layer 103, a protective layer 104, a visible information recording layer 105 and an over coat layer forming an outermost layer which are successively layered on the substrate 101 and wherein the reflectance to irradiation light from the label surface side is 15% or more and 50% or less, focusing of the low output laser beam emitted from the label surface side is satisfactorily performed, and visible information is satisfactorily recorded in the visible information recording layer 105. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an optical information recording medium, and more particularly, to an optical information recording medium in which electronic information is optically recorded / reproduced and visible information is satisfactorily recorded on the label side using a low-output laser beam. Media related.

2. Description of the Related Art In recent years, electronic information recording media for recording, storing, and rewriting a large amount of information have been increasingly important as computer peripheral devices. Among them, an optical information recording medium on which recording and reproduction are performed by using a laser beam is attracting attention as a large-capacity recording medium because it can perform high-density information recording, storage, and reproduction. Examples of such optical information recording media include phase-change optical recording media such as CD-RW and DVD-RW, and organic dye-based optical recording media such as CD-R and DVD-R. No.
The contents of the electronic information recorded on such an optical information recording medium can be confirmed by optically reproducing the information. On the other hand, displaying the contents of the electronic information on the surface of the medium as visible information is a matter of information management. It is important. Conventionally, as such a display method, for example, a method of printing and recording the contents of electronic information on a label surface of a medium (a surface opposite to a surface on which electronic information is recorded) by an inkjet printer or a thermal printer, A method of attaching a label or the like on which the content of electronic information is recorded has been adopted. Recently, a method of recording visible information on the label side of a medium by using a laser beam has been reported (see Patent Documents 1 and 2), and the recording of visible information can be performed without mechanically affecting the medium. It is expected as a method.

JP 2000-173096 A JP 2001-283364 A

However, the method of recording visible information on the label side of a medium using a laser beam reported in Patent Document 1 or Patent Document 2 has the following problems. In other words, the method of recording visible information on the label side of the medium with laser light utilizes changes in reaction, melting, and precipitation due to heat. Therefore, it is necessary to pay sufficient attention to the irradiation method. For this reason, in order to reduce the thermal influence on such a medium, it is necessary to use a low-output laser beam. When such a low-output laser beam is used, it is effective to efficiently concentrate the energy of the laser beam by concentrating the low-output laser beam on a layer for recording visible information (a visible information recording layer). However, for that purpose, it is necessary to apply a focus servo.
In this case, in order to focus the laser light stably, it is necessary to ensure a sufficient amount of reflected light that reflects the laser light emitted from the label surface side. Normally, increasing the laser light absorptivity of the visible information recording layer enables good recording to be performed on the visible information recording layer even when a low-power laser beam is irradiated. , The reflectance with respect to light is lowered, and stable focusing becomes difficult. On the other hand, if the absorption rate of the laser light of the visible information recording layer is reduced, it is possible to increase the reflectance with respect to the laser light irradiated from the label surface side. It becomes difficult to perform good recording on the layer.
The present invention has been made to solve a technical problem that has been highlighted when recording visible information on a visible information recording layer formed on the label side of an optical information recording medium by using such a low-output laser beam. It is.
That is, an object of the present invention is to provide an optical information recording medium in which visible information is recorded on the label surface side by a low-output laser beam without adversely affecting electronic information recorded on the medium.

In order to achieve this object, the optical information recording medium to which the present invention is applied is formed such that the reflectance with respect to the laser light emitted from the label surface side is within a certain range. That is, the optical information recording medium to which the present invention is applied is provided with the substrate and the visible information by light irradiated from the label surface side opposite to the substrate side, which is provided directly or via another layer on the substrate. And a visible information recording layer on which is recorded, the reflectance of the light irradiated from the label surface side is 15% or more and 50% or less.
Further, in the optical information recording medium to which the present invention is applied, digital information is recorded on a substrate having guide grooves and / or pits for recording and reproduction, and at least light irradiated from the substrate side on the substrate. An electronic information recording layer, a reflective layer formed on the electronic information recording layer, and a visible information recording layer on which visible information is recorded by light emitted from the label surface side opposite to the substrate side. An optical information recording medium having a reflectance of 15% or more and 50% or less with respect to light emitted from the label surface side opposite to the substrate side.

  Further, the visible information recording layer may be characterized in that an overcoat layer is formed on the label side of the visible information recording layer. In this case, it is preferable that the lower limit of the thickness of the overcoat layer is 10 μm and the upper limit is 100 μm. Further, the visible information recording layer is characterized by being made of a material whose color developing property changes or a material whose transparency changes by a laser beam applied to the visible information recording layer. Further, the visible information recording layer preferably has a reflective layer formed on at least one side of the visible information recording layer. In this case, the visible information recording layer and the reflective layer may be in contact with each other, or an optional layer that transmits light may be provided between the visible information recording layer and the reflective layer.

  The present invention also provides a substrate, an electronic information recording layer provided directly on the substrate or via another layer, and on which digital information is recorded by light irradiated from the substrate side, and a substrate side of the electronic information recording layer. And a protective layer formed on the side of the reflective layer opposite to the substrate side, wherein the optical information recording medium is formed on the side of the protective layer opposite to the substrate side. The visible information recording layer in which visible information is recorded by light emitted from the label surface side opposite to the substrate side, and the visible information recording layer is formed of a light transmissive material on the label surface side. And an overcoat layer, and has a reflectance of 15% or more and 50% or less with respect to light emitted from the label surface side opposite to the substrate side. it can. In the optical information recording medium to which the present invention is applied, “visible information” refers to information visually read, such as characters, symbols, images such as illustrations and photographs, and geometric patterns, and “electronic information”. Means information read by a certain reproducing apparatus, such as information recorded as a digital signal.

  According to the present invention, there is provided an optical information recording medium in which visible information is recorded on a label surface by irradiation with a low-power laser beam.

Hereinafter, an optical information recording medium to which the best mode for carrying out the present invention (hereinafter, referred to as the present embodiment) is applied will be described in detail with reference to the drawings.
(1st Embodiment)
FIG. 1 is a diagram for explaining the structure of the first embodiment of the optical information recording medium to which the present embodiment is applied. The optical information recording medium 100 shown here has a substrate 101, an electronic information recording layer 102 formed on the substrate 101 in order, and a side of the electronic information recording layer 102 opposite to the side on which the laser beam 107 is incident. Has a structure in which a reflective layer 103, a protective layer 104, a visible information recording layer 105, and an overcoat layer 106 that forms the outermost layer are sequentially laminated.
As shown in FIG. 1, an electronic information recording layer 102 provided on an optical information recording medium 100 has a laser beam incident from an objective lens (not shown) of a laser device for recording / reproducing electronic information via a substrate 101. Recording and reproduction of electronic information are performed by the light 107. On the other hand, when the optical information recording medium 100 is turned upside down and set in a laser device for recording / reproducing electronic information, for example, the visible information recording layer 105 is irradiated with laser light emitted from the label side via the overcoat layer 106. Light 108 records visible information. A part of the laser beam 108 is reflected by the reflective layer 103 provided below the visible information recording layer 105 (on the substrate 101 side), and the reflected light 109 is focused for condensing the laser beam 108. Used for

The substrate 101 is basically formed of a material transparent to the wavelength of the recording light and the reproduction light for the electronic information recording layer 102. As a material for forming the substrate 101, for example, other than a polymer material such as a polycarbonate resin, an acrylic resin, a methacrylic resin, a polystyrene resin, a vinyl chloride resin, an epoxy resin, a polyester resin, and an amorphous polyolefin resin, And an inorganic material such as glass. In particular, polycarbonate resins are preferable because they are excellent in terms of high light transmittance, low optical anisotropy, and high mechanical strength. Further, from the viewpoints of chemical resistance, moisture absorption resistance, optical characteristics, and the like, amorphous polyolefin is preferable.
For example, a guide groove and / or pit for recording / reproducing is provided on a surface of the substrate 101 which is in contact with the electronic information recording layer 102, and is molded by a molding method such as injection molding. Such guide grooves and / or pits are preferably provided at the time of molding the substrate 101. For example, the guide grooves and / or pits may be provided on the substrate 101 using an ultraviolet (UV) curable resin. The lower limit of the thickness of the substrate 101 is usually 1.1 mm, preferably 1.15 mm, and the upper limit of the thickness is usually 1.3 mm, preferably 1.25 mm.

The electronic information recording layer 102 is formed of a material capable of recording electronic information (information such as information recorded by a digital signal, such as information recorded by a certain reproducing device) by irradiation with a laser beam 107, and is usually made of an organic substance. It is formed as a recording layer made of an inorganic material. The electronic information recording layer 102 may be formed directly on the substrate 101, or may be formed between the substrate 101 and the electronic information recording layer 102 via an optional layer, if necessary. Is also good.
When the electronic information recording layer 102 is a recording layer made of an organic substance, an organic dye is mainly used. Examples of such organic dyes include macrocyclic azaannulene dyes (phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, etc.), polymethine dyes (cyanine dyes, merocyanine dyes, squalilium dyes, etc.), anthraquinone dyes, azurenium dyes, azo dyes Dyes, metal-containing azo dyes, metal-containing indoaniline dyes, and the like. Among these, metal-containing azo dyes, cyanine dyes and phthalocyanine dyes are preferred. In particular, metal-containing azo dyes are preferable because of their excellent durability and light resistance.

Examples of a method for forming the electronic information recording layer 102 made of an organic substance include dry film forming methods such as a vacuum evaporation method and a sputtering method, and wet film forming methods generally performed such as a casting method, a spin coating method, and an immersion method. Can be Of these, a wet film forming method is preferable from the viewpoint of mass productivity and cost, and a spin coating method is particularly preferable.
When the electronic information recording layer 102 is formed as a recording layer made of an inorganic substance, for example, a rare-earth transition metal alloy such as Tb-Te-Co or Dy-Fe-Co on which recording is performed by the magneto-optical effect is used. . Further, chalcogen-based alloys such as Ge.Te and Ge.Sb.Te that change phases may be used. These layers may be a single layer or may be composed of two or more layers.
Examples of a method for forming the electronic information recording layer 102 made of an inorganic substance include a vapor deposition method, an ion plating method, and a sputtering method. Among them, the sputtering method is particularly preferable in terms of mass productivity and cost. The thickness of the electronic information recording layer 102 varies depending on the type of the recording layer, but the lower limit is usually 5 nm, preferably 10 nm, and the upper limit is usually 500 nm, preferably 300 nm. The electronic information recording layer 102 of the optical information recording medium 100 to which the present embodiment is applied may be a recordable / erasable phase-change recording layer.

The reflection layer 103 is provided in contact with the electronic information recording layer 102 on the side opposite to the substrate 101, and generally has a function of reflecting the laser beam 107 emitted from the substrate 101 side to the substrate 101 side. When the substrate 101 is provided with a recording / reproducing guide groove and / or pit, the reflective layer 103 has an uneven shape corresponding thereto.
As a material for forming the reflective layer 103, a material having a sufficiently high reflectance at the wavelength of the reproduction light can be used, and examples thereof include Au, Al, Ag, Cu, Ti, Cr, Ni, Pt, Ta, and Pd. It is possible to use a metal alone or as an alloy. Among these, Au, Al, and Ag have high reflectivity and are suitable as a material for the reflective layer. Further, those containing Ag as a main component are particularly preferable in terms of low cost and high reflectance.
Examples of a method for forming the reflective layer 103 include an evaporation method, an ion plating method, and a sputtering method. Among them, the sputtering method is particularly preferable in terms of mass productivity and cost. The lower limit of the thickness of the reflective layer 103 is usually 30 nm, preferably 50 nm, and the upper limit is usually 150 nm, preferably 120 nm.

The protective layer 104 is generally formed of a light transmissive material, for example, an ultraviolet (UV) curable resin. Specific examples of the ultraviolet (UV) curable resin include, for example, acrylate resins such as urethane acrylate, epoxy acrylate, and polyester acrylate. Most of these materials are laser light transmitting materials, and thus can be suitably used. One of these ultraviolet (UV) curable resins may be used alone, or two or more thereof may be used in combination. Further, the protective layer 104 may be a single-layer film or a multilayer film having two or more layers.
As a method of forming the protective layer 104 with an ultraviolet (UV) curable resin, usually, an ultraviolet (UV) curable resin is used as it is or after dissolving in a suitable solvent to prepare a coating solution, and then reflecting the coating solution. It can be formed by being applied over the layer 103 and curing by irradiating ultraviolet (UV) light. In this case, as a coating method, a spin coating method, a casting method, or the like can be adopted. In addition, the protective layer 104 can be formed by any of the above-described various coating methods, various wet film formation methods such as a screen printing method, and various dry film formation methods such as a vacuum evaporation method, a sputtering method, and an ion plating method. It is formed by a method appropriately selected according to a material to be used. Among them, a wet film forming method, particularly a spin coating method is preferable, and a spin coating method is generally used. The lower limit of the thickness of the protective layer 104 is usually 1 μm, preferably 3 μm, and the upper limit is usually 15 μm, preferably 10 μm.

When the visible information recording layer 105 is irradiated with light, usually, the recording material constituting the layer is discolored, and as a result, the visible information (images such as characters, symbols, illustrations and photographs, geometric patterns, etc.) , Information visually read). The recording material that constitutes the visible information recording layer 105 is not particularly limited, but as a substance that changes the absorption of visible light, it is roughly classified into the following (a) a type in which the coloring property changes, and (b) a transparent type. And the type whose gender changes.
(A) Examples of the recording material of the type in which the coloring property changes include, for example, a coloring organic dye generally used for optical recording of electronic information. Such organic dyes include macrocyclic azaannulene dyes (phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, etc.), polymethine dyes (cyanine dyes, merocyanine dyes, squalilium dyes, etc.), anthraquinone dyes, azurenium dyes, azo dyes And metal-containing azo dyes and metal-containing indoaniline dyes.

Further, a leuco dye having a lactone ring portion in the molecular structure may be mentioned. Leuco dyes are preferred because the contrast during color development is high and the amount of heat required for color development can be kept low.
Specific examples of leuco dyes include, for example, 3-diethylamino-7-chloroanilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilino Fluoran, 3-diethylamino-6-methyl-7-2, 4-xyridinofluoran, 3-diethylamino-6-methyl-7- (m-toluidino) -fluoran, 3-diethylamino-7,8-benzofluor Fluoran compounds such as silane and 3-diethylamino-6-methyl-7-xidinofluoran; crystal violet lactone, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindole- 3-yl) -4-azaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-me Le indol-3-yl) phthalide, 3,3-bis (1-n-butyl-2-methylindole-3-yl) phthalide compounds such phthalide and the like. Of these, phthalide compounds are preferred.

An electron-accepting compound or a dye that absorbs recording laser light and generates heat is used in combination with these leuco dyes as necessary. In this case, examples of the electron-accepting compound include an organic phosphoric acid compound having an aliphatic group having 6 or more carbon atoms, an aliphatic carboxylic acid compound, and a phenol compound. Preferably, it is a phenol compound.
Specific examples of the electron-accepting compound include organic phosphoric acid compounds such as dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, and eicosylphosphonic acid.
As the aliphatic carboxylic acid compound, α-hydroxydecanoic acid, α-hydroxytetradecanoic acid, α-hydroxyhexadecanoic acid, α-hydroxyoctadecanoic acid, α-hydroxypentadecanoic acid, α-hydroxyeicosanoic acid, α-hydroxydokosan Acids, α-hydroxytetracosanoic acid, α-hydroxyhexacosanoic acid, α-hydroxyoctacosanoic acid and the like. Examples of the phenol compound include a gallic acid compound, a benzoic acid compound, and a bisphenol compound.
Specific examples of these compounds include, for example, gallic acid compounds such as methyl gallate, propyl gallate, butyl gallate, lauryl gallate and the like. Examples of the benzoic acid compound include methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, and 2,4-didroxybenzoic acid. Examples of the bisphenol-based compound include bisphenol S and bisphenol A. Furthermore, 4'-hydroxy-4-octadecyl benzanilide, N-octadecyl-4-hydroxybenzamide, N- (4-hydroxyphenyl) -N'-octadecyl urea, 4-hydroxyphenylpropiono-behenyl hydrazide and the like can be mentioned. These electron accepting compounds may be used alone or in combination of two or more.
Examples of the light-absorbing dye include the various dyes described above as organic dyes used for optical recording of electronic information, and infrared-absorbing dyes such as bisanthrone-based and indoaniline-based dyes.

Next, as the recording material (b) of a type in which the transparency changes, for example, an organic low-molecular compound that is dispersed in a resin base material at about 0.1 to 2 μm and melts or crystallizes by heat treatment can be cited. As such a compound, for example, a known organic low-molecular compound such as a higher fatty acid having 12 or more carbon atoms can be used. Such an organic low-molecular compound may be a compound composed of a fatty acid, an aliphatic dibasic acid, a ketone, an ether, an alcohol, a fatty acid ester and a derivative thereof, or a mixture of one or more of them. It can also be used.
Among the organic low molecular weight compounds that melt or crystallize by heat treatment, fatty acid alkyl esters having 12 or more carbon atoms are preferable because they have a low melting point (mp) and melt and crystallize by heat treatment at a relatively low temperature. Furthermore, in addition to the fatty acid alkyl ester having 12 or more carbon atoms, a high melting point (mp) aliphatic dibasic acid having 10 or more carbon atoms is used in combination, and the mixing ratio of the fatty acid alkyl ester and the aliphatic dibasic acid is adjusted. In addition, it is possible to adjust the temperature range in which the film is made transparent, and to change the degree of transparency and cloudiness at a predetermined temperature.
Examples of fatty acid alkyl esters having 12 or more carbon atoms include methyl stearate, ethyl stearate, butyl stearate, octyl stearate, stearyl stearate, behenyl stearate, methyl behenate, ethyl behenate, butyl behenate, behenate Octyl acid, stearyl behenate, behenyl behenate, methyl lignoserate, ethyl lignocerate and the like can be mentioned.
Examples of the aliphatic dibasic acid having 10 or more carbon atoms include sebacic acid, dodecandioic acid, tetradecandioic acid, eicosantioic acid, and the like. When a fatty acid alkyl ester having 12 or more carbon atoms and an aliphatic dibasic acid having 10 or more carbon atoms are used in combination, the compounding ratio is preferably about 1: 1 to 10: 1, more preferably 2: 1 to 6: 1. . Since the aliphatic dibasic acid on the high melting point side is considered to play a role in controlling the crystallization behavior as a seed crystal of the fatty acid alkyl ester on the low melting point side, its effect may be lost if the blending amount is too small. Conversely, if the amount is too large, the contrast may be reduced.
Among these recording materials constituting the visible information recording layer 105, those containing (a) a leuco dye of a type whose color developing property changes and (b) those of a type whose transparency changes are gaseous at the time of coloring. Is not generated, so that there is no possibility that other layers such as the overcoat layer 106 provided on the visible information recording layer 105 are raised or peeled off.
As a method for forming the visible information recording layer 105, a known wet film formation method as described in the section of the method for forming the electronic information recording layer 102 can be used. Among them, spin coating or screen printing is preferable, and spin coating is more preferable. The lower limit of the thickness of the visible information recording layer 105 is usually 0.1 μm, preferably 0.5 μm, and the upper limit of the thickness is usually 5 μm, preferably 3 μm.

The overcoat layer 106 is provided on the label side of the visible information recording layer 105 so as to protect the visible information recording layer 105 from physical damage or the like and to efficiently narrow the laser beam 108 to the visible information recording layer 105. To form the outermost layer. By providing the overcoat layer 106, the laser beam 108 can be efficiently narrowed down, so that visible information can be recorded on the visible information recording layer 105 even when the power of the laser beam 108 is reduced. Thereby, the thermal influence on the electronic information can be further reduced.
The material constituting the overcoat layer 106 is not particularly limited as long as it is a material that protects the visible information recording layer 105 from external force and the like and is transparent to laser light. As a material constituting the overcoat layer 106, as an organic substance, a thermoplastic resin, a thermosetting resin, an electron beam curable resin, an ultraviolet (UV) curable resin, or the like can be given. The overcoat layer 106 can be formed by dissolving a thermoplastic resin, a thermosetting resin, or the like in a suitable solvent, applying a coating solution, and drying the coating solution. The ultraviolet (UV) curable resin is applied as it is or after dissolving in an appropriate solvent to prepare a coating solution, and then applying the coating solution, and irradiating with ultraviolet (UV) light to cure the overcoat layer 106. Can be formed. As the ultraviolet (UV) curable resin, for example, acrylate resins such as urethane acrylate, epoxy acrylate, and polyester acrylate can be used. Examples of the inorganic substance include SiO ₂ , SiN ₄ , MgF ₂ , and SnO ₂ . These materials may be used alone or in a combination of two or more. Further, the overcoat layer 106 may be a single-layer film or a multilayer film of two or more layers as long as it is transparent to the laser beam 108.

The overcoat layer 106 is preferably formed by a wet film forming method using the above-described various organic substances. As the wet film forming method, a spin coating method, a casting method, a screen printing method, or the like can be employed as in the case of the protective layer 104 described above. Among them, the spin coating method is particularly preferred because of its high surface smoothness. In particular, when the overcoat layer 106 is formed, if a transparent substrate made of a laser-transmissive material is to be bonded in advance, it is necessary to perform accurate alignment of the substrate, and air bubbles are generated in the adhesive layer. Various measures in the manufacturing process are required, such as reducing the pressure in the bonding process so as not to enter. Therefore, from the viewpoint of productivity, it is advantageous to provide the overcoat layer 106 by a wet film forming method such as spin coating or screen printing.
The lower limit of the thickness of the overcoat layer 106 is 10 μm, preferably 20 μm, and the upper limit of the thickness is 100 μm, preferably 80 μm. If the thickness of the overcoat layer 106 is excessively small, there is a possibility that a sufficient protection function of the visible information recording layer 105 cannot be maintained. Further, the focus of the recording laser beam becomes unstable, and recording cannot be performed stably. For example, when the thickness of the overcoat layer 106 is less than 10 μm, if the thickness variation in the circumferential direction of the overcoat layer 106 is equal to or more than the wavelength of the laser light (up to 900 nm), interference of the laser light occurs, and The fluctuation of the amount of reflected light becomes large, and it becomes impossible to perform stable focusing. When the thickness is 10 μm or more, even if the thickness fluctuates, interference hardly occurs, so that focusing can be stably performed. If the thickness of the overcoat layer 106 is excessively high, when the overcoat layer 106 is formed by coating, overcoating or the like is required, and the forming process becomes complicated. Further, there is a possibility that a problem such as an increase in the warpage of the disk due to the curing shrinkage of the coating material may occur. The refractive index of the overcoat layer 106 is preferably 0.4 or more, and more preferably 0.5 or more. Moreover, it is preferably 2.6 or less, more preferably 1.9 or less. If the refractive index of the overcoat layer 106 is excessively large, the amount of reflection of the laser beam 108 on the surface of the overcoat layer 106 increases, and it may be difficult to efficiently record visible information on the visible information recording layer 105. .

In general, when a layer is formed by spin coating, the thickness of the layer to be formed is controlled by controlling three factors such as the viscosity of the coating solution, the number of rotations, and the rotation time. Usually, the upper limit of the thickness of a layer such as a protective layer formed on an optical disc is about 3 to 7 μm. Therefore, when a layer is formed by a spin coating method, the viscosity of a coating liquid for forming the layer is 100 CPS or less, The layer is formed by controlling the rotation time to 7000 to 1000 rpm and the rotation time to 1 to 3 seconds.
However, the overcoat layer 106 in the present embodiment is a layer that is thicker than a protective layer or the like provided on a normal optical disc. That is, in order to form the overcoat layer 106 having a thickness of 10 μm or more, when the overcoat layer 106 is formed by the spin coating method, the viscosity of the coating solution should be as large as possible, the number of rotations should be as low as possible, and the rotation time should be as long as possible. To form an overcoat layer 106. Specifically, the viscosity is usually 200 CPS or more, preferably 300 CPS or more. However, it is usually 10,000 CP or less, preferably 6000 CPS or less. The number of rotations is usually 1000 rpm or more, preferably 2000 rpm or more. However, it is usually 6000 rpm or less, preferably 5000 rpm or less. The rotation time is usually 4 seconds or more, but 10 seconds or less.

The optical information recording medium 100 to which the present embodiment is applied has a reflectance of 15% or more, preferably 20% or more, but 50% or less, preferably 40% or less with respect to light emitted from the label side. It is formed to be in the range.
Here, the reflectance is obtained by irradiating the label surface side of the optical information recording medium 100 before recording the visible information with light having a wavelength corresponding to the wavelength (λ) of the laser light irradiating the visible information recording layer 105, This is a numerical value obtained by measuring the spectral reflectance on the label surface side using a reflection measuring integrating sphere (spacer with a 10 ° angle) of a spectrophotometer. Generally, the laser beam used in the present invention is a semiconductor laser beam, and the wavelength (λ) of the semiconductor laser beam is about 300 to 800 nm.
In the optical information recording medium 100 to which the present embodiment is applied, the reflectance with respect to the light irradiated from the label surface side is 15% or more, preferably 20% or more, but 50% or less, preferably 40% or less. It is formed so that it may be in the range. Thereby, the balance between the ratio of the laser beam 108 irradiated from the label surface side to be absorbed by the visible information recording layer 105 and the ratio of the reflected light 109 reflected to the label surface side is maintained. As a result, the amount of light incident on the visible information recording layer 105 is secured, and the reflected light 109 reflecting the laser light 108 emitted from the label surface is stabilized, and focusing is performed by the stable reflected light 109. . This makes it possible to record clear visible information on the visible information recording layer 105 using low-power laser light.

  The method for forming the optical information recording medium 100 to which the present embodiment is applied so that the reflectance with respect to light emitted from the label surface side is in a range of 15% or more and 50% or less is not particularly limited. For example, when the visible information recording layer 105 is made of a coloring organic dye, the absorption ratio of the visible information recording layer 105 with respect to the laser light 108 is controlled by the mixing ratio of the laser light absorbing dye used in combination with the coloring organic dye. Then, there is a method of forming the reflectance to be 15% or more and 50% or less. In addition, an absorption rate is measured as an absorbance. In this case, in the composition (coating solution) of the recording material used to form the visible information recording layer 105, the solid content of the laser light absorbing dye is 1% by weight or more, preferably 3% by weight or more. % By weight, preferably 7% by weight or less. Normally, when the heat absorption efficiency of the visible information recording layer 105 is taken into consideration, it is considered that the light-absorbing dye is contained at about 20%. However, in this embodiment, the reflectance is set to 15% or more and 50% or less. In addition, the reflectance is adjusted with the light absorbing dye in the above range.

Further, a method of controlling the reflectance by changing the thickness of the visible information recording layer 105 formed by a wet film forming method is also possible. The reflectance can be reduced by increasing the thickness of the visible information recording layer 105, and can be increased by decreasing the thickness of the visible information recording layer 105. In general, the thickness of the visible information recording layer 105 having a reflectance of 15% or more and 50% or less is usually 0.1 μm or more, preferably 0.5 μm or more, and the upper limit of the thickness is usually 5 μm or less, preferably Is 3 μm or less. Usually, in order to sufficiently change the recording portion of the visible information recording layer and clearly record the visible information, it is considered that the thickness of the visible information recording layer is about 10 μm. However, in the present invention, the reflectance is 15%. As described above, the reflectance is adjusted so that the thickness of the visible information recording layer 105 is within the above range so as to be 50% or less.
In the present embodiment, the content of the light-absorbing dye in the visible information recording layer 105 must be 1% by weight or more and 15% by weight or more in solid content concentration in order to stably set the reflectance to 15% or more and 50% or less. It is very effective to set the thickness of the visible information recording layer 105 to 0.1 μm or more and 5 μm or less.
In the optical information recording medium 100 to which the present embodiment is applied, the reflection layer 103 serves as a reflection layer for a laser beam 107 irradiated from the substrate 101 side for recording electronic information, and transmits the visible information. Since it serves as a reflective layer for the laser beam 108 irradiated from the label side for recording, it is preferable in simplifying the layer configuration and reducing the manufacturing cost. Further, when recording visible information on the visible information recording layer 105, in order to obtain a reflected light 109 for stable focusing, a lower side of the visible information recording layer 105 (on the opposite side to the incident surface of the recording laser beam). ) Is preferably provided with a second reflective layer. Further, an overcoat layer made of a light transmissive material may be formed between the second reflective layer and the visible information recording layer 105.

(Second embodiment)
FIG. 2 is a diagram for explaining the structure of the second embodiment of the optical information recording medium to which the present embodiment is applied. The optical information recording medium 200 shown in FIG. 2 has a substrate 201, an electronic information recording layer 202 formed on the substrate 201 in order, and an opposite side to the side of the electronic information recording layer 202 where the laser beam 207 is incident. A first reflective layer 203 provided in contact with the side, a protective layer 204, a visible information recording layer 205, a translucent second reflective layer 213, and an overcoat layer 206 forming the outermost layer are sequentially laminated. It has a structure.
As shown in FIG. 2, an electronic information recording layer 202 provided on an optical information recording medium 200 has a laser beam incident from an objective lens (not shown) of a laser device for recording / reproducing electronic information via a substrate 201. Recording and reproduction of electronic information are performed by the light 207. On the other hand, when the optical information recording medium 200 is turned upside down and set in a laser device for recording / reproducing electronic information, for example, the visible information recording layer 205 irradiates the visible information recording layer 205 from the label side via the overcoat layer 206. Visible information is recorded by the light 208. A part of the laser light 208 is reflected by the translucent second reflective layer 213 provided in contact with the visible information recording layer 205, and the reflected light 209 is focused for condensing the laser light 208. Used for
The description of the portions overlapping the optical information recording medium 100 in the first embodiment described above, such as the shape and material of each layer constituting the optical information recording medium 200 to which the present embodiment is applied, is omitted, and different portions will be described. Will be described in detail.

In the optical information recording medium 200 to which the present embodiment is applied, a translucent second reflective layer 213 is provided above the visible information recording layer 205 (on the label side). The translucent second reflective layer 213 is formed using the same material as the first reflective layer 203 so that the reflectance is about 10% or more and about 50% or less. The translucent second reflective layer 213 has a function of reflecting a part of the laser beam 208 emitted from the label surface side and transmitting a part of the laser light 208 to reach the visible information recording layer 205. The method for controlling the reflectance of the translucent second reflective layer 213 is not particularly limited, and includes, for example, a method for controlling by changing the thickness of the layer.
As a material for forming the translucent second reflective layer 213, for example, a metal such as Au, Al, Ag, Cu, Ti, Cr, Ni, Pt, Ta, or Pd can be used alone or as an alloy. It is. Among them, Au, Al, and Ag are preferable because it is easy to control the reflectance by changing the layer thickness.
Examples of a method for forming the translucent second reflective layer 213 include a vapor deposition method, an ion plating method, and a sputtering method. Among them, the sputtering method is particularly preferable in terms of mass productivity and cost. The lower limit of the thickness of the translucent second reflective layer 213 is usually 3 nm, preferably 5 nm, and the upper limit is usually 70 nm, preferably 50 nm.
In the optical information recording medium 200 to which the present embodiment is applied, by providing the translucent second reflective layer 213 above the visible information recording layer 205 (label side), the laser beam 208 emitted from the label side Is reflected by the translucent second reflective layer 213, and focusing is performed using the reflected light 209, so that clear visible information is recorded on the visible information recording layer 205 using a low-output laser beam. Becomes possible.

  Incidentally, the optical information recording media 100 and 200 to which the present embodiment is applied may have arbitrary layers other than those described above. For example, in the first embodiment, when a recording layer made of an inorganic substance is used as the electronic information recording layer 102, a dielectric layer sandwiching the electronic information recording layer 102 is provided, and furthermore, between each layer or optically. An arbitrary layer may be provided in contact with the outermost layer of the information recording media 100 and 200.

As described above, the two embodiments of the optical recording medium to which the present invention is applied have been described. However, the present embodiment is not limited to the above aspect, and various modifications can be made. For example, the optical recording medium may have a plurality of electronic recording layers. Optical recording using a substrate having a guide groove and / or pit having a thickness of about 0.6 mm (first substrate) and a so-called dummy substrate having no guide groove and / or pit (second substrate). In the case of a medium, a laminated structure composed of a first substrate / electronic information recording layer / reflection layer / adhesion layer / second substrate / visible information recording layer / overcoat layer, or a first substrate / electronic information recording layer / The present invention can be applied to a laminated structure including a reflective layer / adhesive layer / visible information recording layer / second substrate /. In this case, the overcoat layer and the second substrate side are the label side, respectively, and other layers may be provided as needed between each layer or as the outermost layer.
Furthermore, the present invention is not limited to a so-called substrate-surface incident type optical disk, but may be any so-called film-surface incident type optical recording medium in which information is recorded and reproduced by irradiating a laser beam from the protective layer side (that is, the film surface side). -The present invention can be applied to a laminated structure including a bar coat layer / visible information recording layer / substrate / reflection layer / electronic information recording layer / protective layer. In this case, the overcoat layer side is the label side, and the substrate has guide grooves and / or pits on the side where the information recording layer is provided. Further, other layers may be provided as needed between each layer or as the outermost layer.

Hereinafter, an optical information recording medium to which the present embodiment is applied will be described more specifically with reference to examples. The present embodiment is not limited to the examples.
(1) Recording of Visible Information on Optical Information Recording Medium FIG. 3 is a diagram for explaining a recording apparatus that records visible information on an optical information recording medium having a visible information recording layer. The recording device 300 shown in FIG. 3 is such that visible information can be recorded on an optical information recording medium 11 having a visible information recording layer by an ordinary optical disk drive, and the optical information recording medium 11 is mounted. A spindle 12, a spindle motor 13 for rotating the spindle 12, a stepping motor 14 for feeding, a screw shaft 15 rotated by the stepping motor 14, and a pickup 16 moved to an arbitrary position are provided. .
As shown in FIG. 3, in this recording apparatus 300, an optical information recording medium 11 is mounted on a spindle 12 and rotated by a spindle motor 13, and a screw shaft 15 is rotated by a stepping motor 14 for feed feed. The pickup 16 is moved to the position. The spindle motor 13 performs servo with an FG pulse signal, and adjusts the optical information recording medium 11 to an arbitrary rotation speed. The optical information recording medium 11 is focused on by the focus servo, and the laser light 17 is condensed to write visible information on the optical information recording medium 11. At this time, the laser power is controlled by the front monitor so that writing can be performed with an appropriate power. The write signal irradiates a pulse having a duty of about 50% on the optical information recording medium 11 with an output of 40 to 50 mW. The spindle rotation speed is 160 to 2560 rpm.
(2) Measurement of reflectance The spectral reflectance of the label surface of the optical information recording medium was measured using a Hitachi spectrophotometer U-3500 type reflection measuring integrating sphere (spacer with a 10 ° angle) (relative to a standard white plate). The measurement was performed using light having a wavelength (780 nm) corresponding to the wavelength of a laser beam used to record visible information (unit:%).

(Examples 1 to 7, Comparative Example 1 and Comparative Example 2)
A polycarbonate resin substrate having a groove of 0.45 μm in width and 155 nm in depth and a thickness of 1.2 mm was formed by injection molding. On this substrate, a fluorine-containing alcohol solution of a metal-containing azo dye was applied by spin coating, and dried at 90 ° C. for 15 minutes to form an electronic information recording layer having a thickness of 70 nm. Next, on this electronic information recording layer, Ag was sputtered to form a reflective layer having a thickness of 70 nm. Further, an ultraviolet (UV) curable resin ("SD-374" manufactured by Dainippon Ink and Chemicals, Inc.) mainly composed of an acrylate monomer is applied on the reflective layer by spin coating, and then irradiated with ultraviolet (UV) light. And cured to form a protective layer having a thickness of 7 μm, thereby producing a CD-R. Subsequently, 0.2 parts by weight of a phthalide-based leuco dye, 0.6 parts by weight of an electron-accepting compound composed of a phenolic compound, 0.05 parts by weight of a bisanthrone-based infrared-absorbing dye, and a binder resin shown in Table 1 (10% by weight toluene solution) Toluene was added to 4 parts by weight to prepare a color-forming organic dye composition having a solid content concentration shown in Table 1, and this was applied on a protective layer by spin coating, and then heated at 50 ° C. After drying for 30 minutes, a visible information recording layer was formed. Then, on this visible information recording layer, an ultraviolet (UV) curable resin ("SD-301", manufactured by Dainippon Ink and having a viscosity of 500 CPS) mainly composed of an acrylate monomer was used at a rotation speed of 250 rpm and a rotation time of 6 seconds. The composition is applied by a spin coating method under the conditions, and cured by irradiating ultraviolet (UV) light to form an overcoat layer (refractive index: 1.5) having a thickness of 20 μm, and nine types having different reflectivities shown in Table 1 Was produced.
The nine types of optical information recording media thus manufactured are set in the recording device 300 shown in FIG. 3, respectively, and a low-power laser beam having a wavelength (λ) of 780 nm and an output of 50 mw is applied to the label surface of the optical information recording medium. Irradiation was performed from the side, and visible information was recorded on the visible information recording layer. Table 1 shows the results.

  From the results shown in Table 1, when the visible information recording layer was irradiated with low-power laser light having a wavelength (λ) of 780 nm, the optical information recording medium having a reflectance of 15.3 to 40.6% (Examples 1 to 4). In Example 7), it was found that focusing with a low-output laser beam having a wavelength (λ) of 780 nm and an output of 50 mW was performed well, and the visible information was recorded well in the visible information recording layer. On the other hand, in the case of the optical information recording media having the reflectivities of 6.8% (Comparative Example 1) and 12.0% (Comparative Example 2), focusing of the laser beam cannot be performed satisfactorily. It can be seen that it is difficult to record clear visible information on the visible information recording layer.

FIG. 2 is a diagram for describing a structure of an optical information recording medium according to a first embodiment to which the present embodiment is applied. It is a figure for explaining the structure of the 2nd embodiment of the optical information recording medium to which this embodiment is applied. FIG. 2 is a diagram for explaining a recording device that records visible information on an optical information recording medium having a visible information recording layer.

Explanation of reference numerals

11, 100, 200: optical information recording medium, 12: spindle, 13: spindle motor, 14: stepping motor, 15: screw shaft, 16: pickup, 17: laser beam, 101, 201: substrate, 102, 202: electronic Information recording layer, 103 reflective layer, 203 first reflective layer, 104, 204 protective layer, 105, 205 visible information recording layer, 106, 206 overcoat layer, 107, 207 laser light, 108, 208 .., Laser light, 109, 209, reflected light, 213, translucent second reflective layer, 300, recording device

Claims (7)

Board and
A visible information recording layer provided directly or via another layer on the substrate, where visible information is recorded by light emitted from a label surface side opposite to the substrate side,
An optical information recording medium, wherein a reflectance of the light irradiated from the label side is 15% or more and 50% or less. A substrate having a guide groove and / or a pit for recording and reproduction;
On the substrate, at least, an electronic information recording layer in which digital information is recorded by light emitted from the substrate side,
A reflective layer formed on the electronic information recording layer;
A visible information recording layer in which visible information is recorded by light emitted from the label side that is opposite to the substrate side,
An optical information recording medium having a reflectance of 15% or more and 50% or less with respect to light emitted from the label surface side opposite to the substrate side.   The optical information according to claim 1, wherein the visible information recording layer has an overcoat layer made of a light transmitting material formed on the label surface side of the visible information recording layer. 4. recoding media.   4. The optical information recording medium according to claim 3, wherein the lower limit of the thickness of the overcoat layer is 10 μm, and the upper limit is 100 μm.   5. The visible information recording layer according to claim 1, wherein the visible information recording layer is formed of a material whose color developing property changes or a material whose transparency changes by light applied to the visible information recording layer. 6. The optical information recording medium described in the above.   The optical information recording medium according to any one of claims 1 to 5, wherein the visible information recording layer has a reflective layer formed on at least one side of the visible information recording layer. Board and
An electronic information recording layer provided directly or via another layer on the substrate, where digital information is recorded by light emitted from the substrate side,
A reflective layer formed on the opposite side of the electronic information recording layer from the substrate side,
An optical information recording medium, comprising: a protective layer formed on a side opposite to the substrate side of the reflective layer;
A visible information recording layer formed on the opposite side of the protective layer from the substrate side, where visible information is recorded by light emitted from the label surface side opposite to the substrate side.
On the label side of the visible information recording layer, an overcoat layer formed of a light transmissive material,
An optical information recording medium having a reflectance of 15% or more and 50% or less with respect to light emitted from the label surface side opposite to the substrate side.

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