JP2005182890A - Optical recording medium, and recording method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium having a label recording layer recordable by utilizing a laser beam common to the laser beam for performing recording and reproducing to an optical recording layer. <P>SOLUTION: The optical recording medium is an optical recording medium 10 having an optical recording layer 12 on a primary surface of a support substrate 11 in which a label recording layer 14 is formed on this optical recording layer 12 via a intermediate layer 13 and at least reversible thermosensitive chromogenic composition, which colors and discolors due to heat, and photothermal conversion material, which generates heat by absorbing the light, are included in this label recording layer 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical recording medium including a label recording layer for recording various information such as an image and a title separately from an optical recording layer, and a recording method using the same.

  In recent years, with the widespread use of various optical media such as CD-R, DVD + R, DVD-R, etc., their use is expanding in a wide variety of fields such as backup of large-capacity data or recording of music and video. Furthermore, rewritable media such as CD-RW, DVD-RW, DVD + RW, and DVD-RAM and recording systems using these have been proposed and put into practical use.

  By the way, in a recording medium of the type that stores information recorded once semi-permanently, such as the above-mentioned CD-R and DVD-R, for example, when a title, an index, an image, etc. corresponding to recorded information are attached, The user writes directly on the label surface with a pen, prints using a method such as an ink jet method or a thermal transfer method, or attaches a label sticker prepared separately.

However, in the case of rewritable media such as CD-RW, DVD-RW, DVD + RW, DVD-RW, etc., once an image or character is printed by the method described above, Since the information cannot be rewritten, if the information recorded on the various media is changed, the label sticker must be newly rewritten or rewritten.
When the label sticker is replaced, the peeled label sticker may adhere to the surface of the optical disk, or the optical recording surface may be damaged, and the appearance may be impaired.

  By the way, so-called heat-sensitive recording media that can record and erase information reversibly by heat, with the spread of various prepaid cards, point cards, credit cards, IC cards, etc., visualization of the balance and various information, It is also being put to practical use in the application of readability, and further in the use of copying machines and printers.

Regarding the so-called thermosensitive recording medium as described above, a leuco dye type, that is, a recording medium having a constitution in which a leuco dye that is an electron donating color developing compound and a developer / color-reducing agent are dispersed in a resin base material, And the method of recording by irradiating an infrared laser beam using this is proposed (for example, refer patent documents 1-4).
Also, a method for recording on such a thermal recording medium using a thermal head has been proposed (see, for example, Patent Document 5).
However, these methods have a practical problem that they are extremely inconvenient at a general user level because a writing device is large and expensive.

On the other hand, there has also been proposed a method for recording arbitrary information on a label recording layer that decomposes or changes in quality when irradiated with laser light (see, for example, Patent Document 6).
However, since this method uses an irreversible reaction, there is a problem that once information is recorded, it cannot be erased.

JP-A-2-188293 JP-A-2-188294 JP-A-5-124360 Japanese Patent Laid-Open No. 7-108761 JP 2000-6539 A JP 2000-173096 A

  As described above, there is an increasing demand for an optical recording medium having a label recording layer capable of repeatedly rewriting characters such as a desired image and title, but it can be easily used even at a general user level. There is no disclosure of a low-cost and practically convenient recording medium and a recording method using the same.

  Therefore, in the present invention, in view of the conventional problems as described above, it has stable color development / decoloring property, can realize clear contrast, and is easily used at a general user level. An optical recording medium having a label recording layer and a recording method using the same are provided.

  In the present invention, an optical recording layer is provided on one main surface of the support substrate, and a label recording layer is formed on the optical recording layer via an intermediate layer. The label recording layer includes at least Provided is an optical recording medium comprising a reversible thermosensitive color-developing composition that reversibly emits and discolors by heat and a light-heat conversion material that absorbs light and generates heat.

  The recording method of the present invention performs recording using an optical recording apparatus having at least an optical pickup having a condensing system and a laser light source, a recording optical system, and a recording mechanism. A recording layer, an intermediate layer, and a label recording layer are formed. The label recording layer includes at least a reversible thermosensitive coloring composition that reversibly emits and discolors by heat, and light-heat that generates heat by absorbing light. The label recording layer forming surface of the optical recording medium configured to contain the conversion material is set to face the incident side of the laser beam emitted from the optical pickup, and the laser beam having a wavelength near 650 nm or 785 nm. Is irradiated while being moved relative to the surface of the label recording layer, and the label recording layer is reversibly changed into two states of a coloring state and a decoloring state.

  According to the present invention, for example, by irradiating a laser beam having a wavelength corresponding to a light absorption band of a label recording layer such as a CD recording wavelength band (near 785 nm) or a DVD recording wavelength band (near 650 nm) An optical recording medium capable of repeatedly recording characters such as images and titles is provided.

  Further, according to the present invention, recording can be performed by reversibly changing the label recording layer between the coloring state and the decoloring state without damaging the optical recording layer of the optical recording medium or impairing the aesthetic appearance. And erasure can be repeated, and it is possible to record functional information to improve the convenience of optical recording media and to improve the appearance of the appearance according to individual preferences. It was.

  Further, according to the recording method of the present invention, desired recording is performed on the label recording layer using a conventionally used recording / reproducing apparatus for CD or recording / reproducing apparatus for DVD, and this is erased and repeated. Recording, and the trouble of separately preparing a recording device for the label recording layer is eliminated, and recording and / or erasing can be performed on the label layer very easily and at low cost. .

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.

As shown in FIG. 1, the optical recording medium 10 of the present invention has an optical recording layer 12 on a support substrate 11, and a label recording layer 14 containing a reversible thermosensitive coloring composition via an intermediate layer 13. Is formed.
Hereinafter, each component will be described in detail.

  The support substrate 11 is made of a material having excellent heat resistance, high transparency to the irradiation laser light, and high dimensional stability in the planar direction, and is a polycarbonate resin that is a conventionally known substrate material for various optical disks. An acrylic resin or the like can be applied, and for example, it can be produced by injection molding.

The optical recording layer 12 can be applied to any conventionally known ROM type recording layer, and various recording layers such as other dye-based recording layers, magneto-optical recording layers, phase change recording layers, etc. Irradiate laser light of a predetermined wavelength, such as write-once media such as DVD + R and DVD-R, and media that can be rewritten repeatedly such as CD-RW, DVD-RW, DVD + RW, and DVD-RAM Thus, it is assumed that it has a function of recording and reproducing signals.
Specifically, a ROM type recording medium has a structure in which a metal reflective layer is formed on fine irregularities, and in a dye-based recording layer applied to CD-R, DVD + R, DVD-R, etc., It has a structure in which a recording dye layer and a metal reflective layer are laminated on a support substrate 11 on which fine guide grooves are formed, and is also used for CD-RW, DVD + RW, DVD-RW, DVD-RAM, etc. In the applied phase change recording layer, a dielectric layer, a recording phase change material layer, a dielectric layer, and a metal reflective layer are laminated on a support substrate 11 on which fine guide grooves are formed. It has a configuration.

The intermediate layer 13 is formed in various forms according to the final aspect of the optical recording medium 10.
For example, when an adhesive layer for improving the adhesion between the optical recording layer 12 and a label recording layer 14 described later or a protective layer for the optical recording layer 12, an acrylic or methacrylic monomer is used. It can be formed using a UV curable resin with a center.
When a laminated optical recording medium such as a DVD is used, as shown in FIG. 2, the intermediate layer 13 is a second thin film made of the same material as that of the support substrate 11 whose film thickness is appropriately controlled. The support substrate 15 is assumed.

  The label recording layer 14 includes at least a reversible thermosensitive coloring composition that can be reversibly and stably controlled by heat to control the coloring state and the decoloring state, a light-heat converting material that absorbs light and generates heat, and It is assumed that a resin binder is contained.

The reversible thermosensitive color-developing composition is composed of at least a color-forming compound having an electron donating property and a developer / color-reducing agent having an electron accepting property.
For example, a leuco dye can be applied as the color-providing compound having an electron donating property, and specifically, an existing thermal paper dye can be used.
The hue can be freely selected, and the visibility can be enhanced as a hue of black, blue, red, etc., or the design can be enhanced by selecting green, peach, purple, or the like.
As the developing / color-reducing agent having electron acceptability, known organic acids having a long-chain alkyl group (Japanese Patent Laid-Open Nos. 5-124360, 7-108761, 7-188294, 2001) -105733, JP-A-2001-113829, etc.) can be applied.
In order to increase the recording sensitivity, it is preferable that the developing / color-reducing agent has a low melting point.
In addition, by controlling, for example, a long-chain alkyl group, acidity, the number of functional groups, etc. in the molecular structure of the developer / subtractor, the label recording layer 14 is designed so as to perform irreversible color development. Can do. In this case, it is suitable for non-rewritable media such as CD-R and DVD-R.

As the light-to-heat conversion material, a dye that absorbs light in the vicinity of 785 nm which is the recording wavelength band of CD or light in the vicinity of 650 nm which is the recording wavelength band of DVD can be used.
In order to obtain good visibility, a material having a small absorption with respect to light in the visible region and a large molar extinction coefficient is preferable as compared with absorption with respect to light having a wavelength near 650 nm or 785 nm. , Cyanine dyes, phthalocyanine dyes, organometallic complex dyes, diimonium salt dyes, aminium salt dyes, iminium salt dyes, metal thin films, aluminum hydroxide, copper phosphate, and the like.

A sensitizer may be added to the label recording layer 14 as necessary. Examples of the sensitizer include stearic acid amide, p-benzylbiphenyl, p-acetoluidide, 2-benzyloxynaphthalene, dibenzyl oxalate, di (4-methylbenzyl) oxalate, benzyl p-benzyloxybenzoate, 1, Examples include 2-di (3-methylphenoxy) ethane, paraffin wax, zinc stearate, and calcium stearate.
Moreover, you may add various additives, such as a ultraviolet absorber, antioxidant, a light stabilizer, and antiseptic | preservative, to the label recording layer 14 as needed.

  Examples of the resin binder for forming the label recording layer 14 include polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethyl cellulose, polystyrene, styrene copolymer, phenoxy resin, polyester, aromatic polyester, Examples include polyurethane, polycarbonate, polyacrylic acid ester, polymethacrylic acid ester, acrylic acid copolymer, maleic acid polymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, and starch.

Next, a configuration aspect of the label recording layer 14 will be described.
As shown in FIG. 3, in the first configuration mode, in the label recording layer 14, a reversible thermosensitive coloring composition 30 comprising a color developing compound 20 and a developer / color reducing agent 21, and a light-to-heat conversion material. 22 is in a mixed state.
In the case of the embodiment as shown in FIG. 3, the label recording layer 14 is composed of the above-described reversible thermosensitive coloring composition 30 comprising the color developing compound 20, the developer / color reducing agent 21, etc., and the light-heat comprising the cyanine dye. It can be formed by applying a coating material prepared by mixing and dissolving the conversion material 22 and various additives using a resin binder, an organic solvent, water, or the like.

As a second configuration mode, as shown in FIGS. 4 and 5, in one label recording layer 14, the light-to-heat conversion material 22 is separated from the reversible thermosensitive coloring composition 30 and in an independent state. Shall be made.
For example, in FIG. 4, a light-heat containing a color-forming layer 24 containing a reversible thermosensitive color-forming composition 30 and a light-heat conversion composition 23 comprising a light-heat conversion material, a resin binder, and various additives. It is assumed that the conversion layer 25 has a configuration in which the conversion layer 25 is separated and independently stacked.
In this case, a paint made of a resin binder containing the reversible thermosensitive coloring composition 30 and the like, and a paint made of the light-heat conversion composition 23 containing the light-heat conversion material 22 and the like in a resin binder, respectively, are predetermined. The label recording layer 14 having a laminated structure is formed by adjusting using a solvent and applying these at desired positions.
The light-heat conversion layer 25 is formed by applying a solution obtained by dissolving or dispersing the light-heat conversion material 22 in a predetermined solvent at a desired position without using a resin binder, and volatilizing the solvent. You can also.
Further, as shown in FIG. 5, either one of the reversible thermosensitive coloring composition 30 and the light-to-heat conversion composition 23 is encapsulated in a microcapsule, or a resin binder that is not compatible with each other is used. In other words, the boundary 27 may be formed in one label recording layer so that both are separated and independent.

  The film thickness of the label recording layer 14 is preferably 1 to 20 μm, more preferably 2 to 10 μm. If the film thickness is too thin, sufficient color density cannot be obtained. If the film thickness is too thick, the heat capacity becomes large, the color development / decoloring property is lowered, or the transparency of the label recording layer 14 is lowered and the visibility is remarkably deteriorated. It is to do.

Various functional layers and protective layers (not shown) may be formed on the label recording layer 14 as necessary.
The protective layer can be formed using a conventionally known ultraviolet curable resin or thermosetting resin, and the film thickness is preferably about 0.1 to 20 μm, more preferably about 0.5 to 5 μm. This is because if the film thickness is too thin, a sufficient protective effect cannot be obtained, whereas if it is too thick, heat transfer is difficult.

Next, a recording method for the label recording layer 14 of the optical recording medium 10 of the present invention will be described.
Note that the optical recording medium 10 has a disk shape.
In this example, a recording / reproducing apparatus that has an optical pickup having a condensing system and a laser light source, a recording optical system, and a recording mechanism and performs recording and reproduction on the optical recording layer 12 of the optical recording medium 10 is used. Shall.
As shown in FIG. 6, the label recording layer 14 surface side of the optical recording medium 10 is installed in the optical disc arrangement portion of the recording / reproducing apparatus so as to face the incident side of the laser beam emitted from the optical pickup. That is, when the recording or reproducing operation is performed on the optical recording layer 12, the surface of the optical recording medium 10 is reversed.
Then, the laser light L is applied to the label recording layer of the optical recording medium 10 using a laser light source, an optical system, and a recording mechanism. Note that a laser beam in the CD recording wavelength band (near 785 nm) or the DVD recording wavelength band (near 650 nm) is selected according to the absorption characteristics of the light-heat conversion material 22 contained in the label recording layer 14.
For example, when recording the label layer 14 using a light-to-heat conversion material having absorption in the CD recording wavelength band, laser light having a wavelength of around 785 nm is used so that the reversible thermosensitive coloring composition reaches the coloring temperature. Irradiation with energy causes the light-to-heat conversion material to generate heat, causing a color reaction between the coloring compound and the developing / color-reducing agent to cause color development.
While rotating the optical recording medium 10, the optical pickup is moved relatively in the radial direction of the optical recording medium 10 to irradiate laser light L to an arbitrary position of the optical recording medium 10. At this time, an arbitrary image can be recorded by modulating the intensity of the laser light L in accordance with the image to be recorded.
In addition, when performing recording on the optical recording layer 12, the mechanism of controlling the focal position according to the displacement of the optical recording medium 10 can be used in the same manner, and the laser beam can be focused on the position of the label recording layer 14. Uniform recording can be reproduced in the plane.

  The label recording layer 14 which is a main part of the optical recording medium 10 of the present invention will be described with specific examples, but the present invention is not limited to the examples shown below.

[Example 1]
In this example, the label recording layer 14 of the optical recording medium 10 is, as shown in FIG. 3, in a resin in a state where a color developing compound (leuco dye), a developer / color reducing agent, and a light-heat conversion material are mixed. It shall have the structure contained in.
As the support substrate 11, a polycarbonate substrate having a thickness of 1.2 mm was used.
Subsequently, the following materials were applied with a wire bar, and heat-dried at 110 ° C. for 5 minutes to form a label recording layer 14 with a film thickness of 4 μm.

(Reversible thermosensitive coloring composition)
Leuco dye (substance shown in chemical formula (1) below): 2 parts by weight

  Developer / color-reducing agent (substance shown in chemical formula (2) below): 4 parts by weight

Vinyl chloride vinyl acetate copolymer: 5 parts by weight (90% vinyl chloride, 10% vinyl acetate, average molecular weight (MW) 115000)
Methyl ethyl ketone (MEK): 91 parts by weight (light-to-heat conversion material)
Cyanine infrared absorbing dye: 0.2 part by weight (manufactured by American Source Inc., ADS775MP, absorption wavelength peak in recording layer: 785 nm)

  On the label recording layer formed as described above, a protective layer having a thickness of about 2 μm was formed using an ultraviolet curable resin.

[Example 2]
In this example, as shown in FIG. 5, the label recording layer 14 contains the light-heat conversion material 22 in a resin that is incompatible with the resin constituting the reversible thermosensitive color-forming composition 30, and light-heat conversion is performed. The composition 23 was separated and made independent.
As the support substrate 11, a polycarbonate substrate having a thickness of 1.2 mm was used.
Subsequently, a coating material containing the following reversible thermosensitive color-forming composition 30 and the light-heat conversion composition 23 is applied on a support substrate with a wire bar, and subjected to a heat drying treatment at 110 ° C. for 5 minutes. The recording layer 14 was formed to a thickness of 4 μm.

(Reversible thermosensitive coloring composition)
Leuco dye (substance shown in chemical formula (1) below): 2 parts by weight

  Developer / color-reducing agent (substance shown in chemical formula (2) below): 4 parts by weight

Vinyl chloride vinyl acetate copolymer: 5 parts by weight (90% vinyl chloride, 10% vinyl acetate, average molecular weight (MW) 115000)
Methyl ethyl ketone (MEK): 91 parts by weight

(Light-heat conversion composition)
Cyanine infrared absorbing dye: 0.2 part by weight (manufactured by American Source Inc., ADS775MP, absorption wavelength peak in recording layer: 785 nm)
Vinyl chloride-vinyl acetate-vinyl alcohol copolymer: 5 parts by weight (91% vinyl chloride, 3% vinyl acetate, 6% vinyl alcohol)
Isocyanate: 1 part by weight (Nippon Polyurethane Co., Ltd., Coronate L)
Tetrohydrafuran (THF): 91 parts by weight The above materials were mixed, stored in an oven at 80 ° C. for 48 hours, sufficiently cured by heat, and pulverized to an average particle size of 1 μm with a ball mill.

  On the label recording layer formed as described above, a protective layer having a thickness of about 2 μm was formed using an ultraviolet curable resin.

Example 3
In this example, as shown in FIG. 4, the label recording layer 14 is formed by laminating a light-heat conversion layer 25 containing a light-heat conversion material 22 and a color developing layer 24 containing a leuco dye and a developer / color-reducing agent. It was assumed that it had the structure made.
As the support substrate 11, a polycarbonate substrate having a thickness of 1.2 mm was used.
The light-heat conversion layer 25 is formed by spin-coating a coating made of the following light-heat conversion composition on the support substrate 11 to a thickness of 2 μm. The color forming layer 24 is formed on the light-heat conversion layer 25 by the following method. A coating made of a reversible thermosensitive coloring composition shown in FIG.
A label recording layer 14 was obtained by heat drying at 110 ° C. for 5 minutes.

(Reversible thermosensitive coloring composition)
Leuco dye (substance shown in chemical formula (1) below): 2 parts by weight

  Developer / color-reducing agent (substance shown in chemical formula (2) below): 4 parts by weight

Vinyl chloride vinyl acetate copolymer: 5 parts by weight (90% vinyl chloride, 10% vinyl acetate, average molecular weight (MW) 115000)
Methyl ethyl ketone (MEK): 91 parts by weight

(Light-heat conversion composition)
Phthalocyanine infrared absorbing dye: 0.8 part by weight (manufactured by Yamamoto Kasei Co., Ltd., D99-038, absorption wavelength peak in recording layer: 770 nm)

  On the label recording layer formed as described above, a protective layer having a thickness of about 2 μm was formed using an ultraviolet curable resin.

Example 4
The leuco dye used in Example 1 was changed to a compound represented by the following chemical formula (3).
Other conditions were the same as in Example 1, and a sample was prepared.

Example 5
The cyanine infrared absorbing dye used in Example 1 was changed to a compound represented by the following chemical formula (4).
Other conditions were the same as in Example 1, and a sample was prepared.

Example 6
The cyanine-based infrared absorbing dye used in Example 1 was changed to a compound represented by the following chemical formula (5).
Other conditions were the same as in Example 1, and a sample was prepared.

Example 7
The cyanine-based infrared absorbing dye used in Example 1 was changed to Sanyo Dye Co., Ltd. Fe-Phthalogicane.
Other conditions were the same as in Example 1, and a sample was prepared.

Example 8
As the support substrate 11, two polycarbonate substrates having a thickness of 0.6 mm were used to produce a bonded optical recording medium having a configuration as shown in FIG.
Other conditions were the same as in Example 1, and a sample was prepared. That is, the label recording layer 14 is formed on the second support substrate 15 as shown in FIG.

  The sample optical recording media of Examples 1 to 8 manufactured as described above were evaluated for reflection density, erasing characteristics, and repeating characteristics as described below.

(Reflection density evaluation)
A laser having a wavelength of 785 nm and a power of 20 mW was used for Examples 1 to 7 by using an optical disk recording / reproducing device at a radius of 55 mm on the label recording layer surface while rotating the optical recording medium of Examples 1 to 8 at 600 rpm. Recording was performed by irradiating the laser beam of 650 nm and 20 mW in Example 8 while moving the laser beam at a speed of 40 μm / s in the radial direction.
At this time, the laser spot size on the label recording layer surface was about 3 μm.
The reflection density (OD) of the image thus recorded was measured with a Macbeth densitometer.

(Erase characteristics evaluation)
A laser having a wavelength of 785 nm and a power of 20 mW was used for Examples 1 to 7 by using an optical disk recording / reproducing device at a radius of 55 mm on the label recording layer surface while rotating the optical recording medium of Examples 1 to 8 at 600 rpm. Recording was performed by irradiating the laser beam of 650 nm and 20 mW in Example 8 while moving the laser beam at a speed of 40 μm / s in the radial direction.
Thereafter, a 120 ° C. hot stamp was applied to each sample for 1 second to erase the recording, and the measurement was performed using a Macbeth densitometer.

(Repeated characteristic evaluation)
A laser having a wavelength of 785 nm and a power of 20 mW was used for Examples 1 to 7 by using an optical disk recording / reproducing device at a radius of 55 mm on the label recording layer surface while rotating the optical recording medium of Examples 1 to 8 at 600 rpm. Recording was performed by irradiating the laser beam of 650 nm and 20 mW in Example 8 while moving the laser beam at a speed of 40 μm / s in the radial direction. Thereafter, a 120 ° C. hot stamp was applied to each sample for 1 second to erase the record.
The above recording and erasing were repeated 100 times at the same position, and then the recorded image was measured with a Macbeth densitometer.

〔Evaluation results〕
Table 1 below shows the results of each evaluation performed on the optical recording media of Examples 1 to 8.

As shown in Table 1, in any of Examples 1 to 8, it was found that the recorded image had a sufficiently high reflection density, and the irradiation laser beam was efficiently converted into heat and colored.
Further, the reflection density after erasure was low, and it was found that the label recording layer had extremely excellent erasing characteristics.
Further, as shown in Table 1, in each of Examples 1 to 8, after the recording and erasing were repeated 100 times, no significant deterioration of each label recording layer was observed, and each label recording layer It was confirmed that the film had sufficient durability and recording stability for practical use.

As is apparent from the above, the label recording layer constituting the optical recording medium of the present invention has stable color development, high definition, contrast, and image stability that is practically acceptable in daily life. It turned out that it can exhibit sex.
In addition, since the visual information can be recorded on the label recording layer by irradiating the laser beam in the CD recording wavelength band or the DVD recording wavelength band, the recording / reproducing apparatus common to the data recording on the CD or DVD is used. Through this process, it was confirmed that arbitrary images, titles, etc. can be recorded easily.

The schematic sectional drawing of an example of the optical recording medium of this invention is shown. The schematic sectional drawing of another example of the optical recording medium of this invention is shown. 1 shows a configuration example of a label recording layer which is a main part of the optical recording medium of the present invention. The other example of a structure of the label recording layer which is the principal part of the optical recording medium of this invention is shown. The other example of a structure of the label recording layer which is the principal part of the optical recording medium of this invention is shown. FIG. 3 shows a state diagram for performing recording on the label recording layer of the optical recording medium of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Optical recording medium, 11 ... Support substrate, 12 ... Optical recording layer, 13 ... Intermediate layer, 14 ... Label recording layer, 15 ... 2nd support substrate, 20 ... Color developing compound, 21... Developer / color reducing agent, 22... Light-to-heat conversion material, 23... Light-to-heat conversion composition, 24... Coloring layer, 25 .. light-to-heat conversion layer, 27. 30, reversible thermosensitive coloring composition

Claims (11)

An optical recording medium having an optical recording layer on one main surface of a support substrate,
A label recording layer is formed on the optical recording layer via an intermediate layer,
The label recording layer contains at least a reversible thermosensitive color-developing composition that reversibly emits and discolors by heat, and a light-heat conversion material that absorbs light and generates heat. An optical recording medium. The reversible thermosensitive color-developing composition contains at least a color-forming compound having an electron donating property and a developer / color-reducing agent having an electron accepting property,
By a reversible reaction between the color-providing compound having electron donating property and the developer having electron accepting property,
2. The optical recording medium according to claim 1, wherein the label recording layer is reversibly changed between a coloring state and a decoloring state. In the label recording layer,
The optical recording medium according to claim 1, wherein the reversible thermosensitive coloring composition and the light-heat conversion material are mixed. In the label recording layer,
2. The light-heat conversion composition comprising at least the light-heat conversion material contained in a resin binder is separated and independent from the reversible thermosensitive coloring composition. An optical recording medium according to 1.   The resin binder constituting the light-heat conversion composition is not compatible with the resin binder in the label recording layer existing around the light-heat conversion composition, and the light-heat conversion composition is the reversible thermosensitive coloring composition, The optical recording medium according to claim 4, wherein the optical recording medium is in a separated and independent state. The label recording layer is
A coloring layer containing at least the reversible thermosensitive coloring composition;
A light-heat conversion layer containing at least the light-heat conversion material,
The optical recording medium according to claim 1, wherein the optical recording medium has a configuration in which the layers are separated and independently stacked.   2. The optical recording medium according to claim 1, wherein the label recording layer is made to absorb light in a wavelength band near 785 nm by the light-heat conversion material.   2. The optical recording medium according to claim 1, wherein the label recording layer is made to absorb light in a wavelength band near 650 nm by the light-heat conversion material. An optical recording layer is provided on the main surface of the support substrate, and a label recording layer is formed on the optical recording layer via an intermediate layer. The label recording layer is reversibly generated at least by heat. Using an optical recording medium containing a reversible thermosensitive color-developing composition that decolors and a light-to-heat conversion material that absorbs light in the wavelength band near 785 nm,
A recording method characterized by reversibly changing the label recording layer into two states, a colored state and a decolored state, by irradiating a laser beam having a wavelength near 785 nm. An optical recording layer is provided on the main surface of the support substrate, and a label recording layer is formed on the optical recording layer via an intermediate layer. The label recording layer is reversibly generated at least by heat. Using an optical recording medium containing a reversible thermosensitive color-developing composition that decolors and a light-to-heat conversion material that absorbs light in the wavelength band near 650 nm,
A recording method comprising: reversibly changing the label recording layer into two states, a colored state and a decolored state, by irradiating a laser beam having a wavelength near 650 nm. At least using an optical recording device comprising an optical pickup, a recording optical system, and a recording mechanism comprising a condensing system and a laser light source,
An optical recording layer is provided on the main surface of the support substrate, and a label recording layer is formed on the optical recording layer via an intermediate layer. The label recording layer is reversibly generated at least by heat. A laser beam emitted from the optical pickup on the surface of the optical recording medium on which the label recording layer is formed of an optical recording medium containing a reversible thermosensitive color-developing composition and a light-heat conversion material Set to face the incident side of
A recording method comprising: recording on the label recording layer by irradiating the laser beam with an intensity corresponding to an image to be recorded while moving relative to the optical recording medium.

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