JPH0973662A - Optical recording medium and method for printing on surface of optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical recording medium whose surface can be easily and satisfactorily printed by successively laminating a light absorbing layer, a light reflecting layer, a protective layer and a printable layer on a transparent substrate and imparting an ionic surface to the printable layer. SOLUTION: A light absorbing layer, a light reflecting layer, a protective layer and a printable layer are successively laminated on a transparent substrate and an ionic property whose polarity is reverse to that of the ionic property of ink used for printing is imparted to the surface of the printable layer being the outermost layer. The drying rate of ink sticking to the surface of the optical recording medium is increased and printing can be made clear.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical recording medium and a method for printing on the surface thereof.

[0002]

2. Description of the Related Art Optical recording media, commonly known as optical disks, have a larger storage capacity than conventional recording media and can be randomly accessed. Therefore, they are exclusively used for reproduction such as audio software, computer software, game software, and electronic publishing. Widely used as a medium. In addition, in recent years, a write-once type recordable optical disc having an organic recording layer or an inorganic recording layer based on various recording principles has been developed, and a part thereof has been put to practical use. Recordable compact disc (C
D-WO). It can be additionally recorded and can be reproduced by a compact disk player or drive dedicated to reproduction by exhibiting a reflectance equivalent to that of a compact disk dedicated to reproduction.

Recently, this recordable compact disc has been widely distributed to individual users, and has come to be used for making a self-made CD by an amateur musician and making a self-made CD-ROM by a computer user. It is used to record personal information in many other uses. When holding or distributing an optical recording medium recording personal information, it is often necessary to display an index of recorded contents or other design on the surface of the disc. However, no letters or patterns are written on the protective layer, which is the outermost layer of commercially available recordable compact discs, or common letters and patterns are printed with UV curable ink or oil-based ink. However, the surface layer is not suitable for displaying with ink or the like, and it is difficult for the user to print the index or the like later using a simple device such as an inkjet printer.

Therefore, generally, a method of writing on the surface of the protective layer by using an oily felt pen or the like is adopted.
However, this is troublesome because it requires manual writing one by one, and there is a problem in that the drawn pattern and drawing quality vary, and the appearance of the optical recording medium is impaired. There is also a method of sticking a label, etc., but the display surface rises by the thickness of the label, and it is easy to cause eccentricity or surface blurring of the optical recording medium at the time of reproduction or additional recording, and when peeling the label,
There is also the risk that the protective layer will peel off with the label and damage the disc itself.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide an optical recording medium capable of easily and satisfactorily printing characters and patterns on the surface thereof.

[0006]

The inventors of the present invention have made earnest studies in view of the above problems, and as a result, have made the surface of the print receiving layer, which is the outermost layer, have an ionic property so that the ink used for printing has an opposite polarity. The inventors have found that the above object can be achieved by using an ionic ink, and have reached the present invention.

That is, the gist of the present invention is as follows. Firstly, in an optical recording medium in which at least a light absorbing layer, a light reflecting layer, a protective layer and a print receiving layer are sequentially laminated on a transparent substrate, the print receiving layer is an ion. An optical recording medium characterized by having a polar surface, and secondly, in the method of printing on the surface of the optical recording medium, an ionic substance having a polarity opposite to that of the print-receiving layer of the optical recording medium. There is a method of printing on the surface of an optical recording medium, which is characterized by printing using ink.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The transparent substrate used in the present invention is not particularly limited as long as it is substantially transparent to the laser light used, and examples thereof include resins such as polycarbonate, polymethyl methacrylate, and amorphous polyolefin, and glass. In addition, a spiral guide groove or a tracking guide having another shape may be provided on the surface of the transparent substrate.

Any material can be used as the material for forming the light absorbing layer as long as it can be used as a dye for an optical recording medium, and organic dyes are preferred. Examples of organic dyes include cyanine dyes, squarylium dyes, croconium dyes, azulenium dyes, triarylamine dyes, anthraquinone dyes, metal-containing azo dyes, dithiol metal complex salt dyes, indoaniline metal complex dyes. , Phthalocyanine dyes, naphthalocyanine dyes, and intermolecular charge transfer dyes are preferably used. These dyes can be used alone or in combination of two or more.
Further, a deterioration inhibitor, a binder and the like may be added and used as necessary. As a method of forming a light absorbing layer containing such an organic dye, a method of dissolving an organic dye or the like in an organic solvent and spin coating is preferably used.
A vapor deposition method can also be used for a dye having a sublimation property such as a phthalocyanine dye.

Further, as the light absorption layer, a magneto-optical recording using a phase change type using a chalcogenide alloy thin film such as GeSbTe or TeSe which is an inorganic thin film and a rare earth-transition metal alloy thin film such as TbFeCo. It is also possible to use a mold or the like. The thickness of the light absorption layer is usually 1
The thickness is 0 nm to 5 μm, preferably about 70 nm to 3 μm.

The light reflecting layer is formed of a material having a high reflectance with respect to the laser light used, and is preferably a metal such as gold, silver, copper or aluminum, or an alloy thereof. The light reflection layer is formed by the sputtering method,
It is preferable that the thin film is formed by a vacuum deposition method or the like and has a thickness of 50 to 200 nm. Further, a dielectric layer or an organic polymer layer may be provided between the substrate, the light absorption layer, and the light reflection layer, if necessary.

The protective layer is usually provided by coating a monomer or oligomer of an organic compound, which can be polymerized into a polymer, or a polymer, and then carrying out a crosslinking reaction.
An ultraviolet curable resin is desirable as the material of the protective layer, but the material is not limited to this, and may be a resin that crosslinks due to heat, moisture in the air, or other factors. If necessary, additives such as a deterioration inhibitor, a diluent and a plasticizer may be contained, and the coloring agent may be colored with a pigment or a dye. The protective layer of the present invention is not limited to the above-mentioned crosslinked polymer and may be any known material for the protective layer. Further, the forming means is
A method other than coating, for example, a known method such as a sputtering method or a vapor deposition method can also be applied. The protective layer is a single layer,
It may be a plurality of layers made of different materials.

The protective layer may also serve as a print receiving layer described later. In this case, the layer structure of the present invention is one in which at least a light absorbing layer, a light reflecting layer and a protective layer which also serves as a print receiving layer are sequentially laminated on a transparent substrate. A feature of the invention is that the print receptive layer has an ionic surface. The ionic surface can be obtained by having an ionic functional group acting as an acid or a base on the surface. For example,
Addition of a polymer having an ionic functional group, an ionic surfactant, an additive such as an ionic antistatic agent, or other particles having an ionic surface to the print-receiving layer, or on the surface of the print-receiving layer It is obtained by coating. Alternatively, other means may be used.

For example, in the case of a polymer having an ionic functional group, a polymer having a carboxyl group, a hydroxyl group, an amino group, a quaternary ammonium group, a sulfonic acid group or the like is preferably used. The print-receiving layer having an ionic surface is particularly effective in improving the fixability of water-based ink. That is, it accelerates the drying of the water-based ink and improves the water resistance of the printed ink. This is because a polar dye is used in water-based ink, so the polar sites of the dye bind to the ionic sites on the surface of the print-receiving layer, and the water molecules previously bound to the dye are released and evaporated. It ’s easier,
It is presumed that the dye becomes difficult to newly bond with other water molecules.

It is preferable to form the above-mentioned ionic surface by adding an ionic surfactant because the fixing property of the ink tends to be further improved. It is presumed that this is because the hydrophilic groups of the surfactant are arranged so as to surround the polar site of the dye and the hydrophobic groups face outward, so that the bond between the dye and the water molecule becomes more difficult. When the ionic surface is formed by the addition of an ionic surfactant, the ionic surfactant may be added in advance to the component forming the print receiving layer before the print receiving layer is formed. The ionic surfactant may be directly applied to the surface of the receiving layer. When the ionic surfactant is added, the addition amount is usually 0.1% by weight or more, preferably 1% by weight or more based on the components of the print receiving layer. Examples of other components constituting the print receiving layer include various pigments, pigment dispersants, ultraviolet absorbers, wetting agents, defoaming agents, surface tension adjusting agents, and the like.

The method for forming the print-receptive layer is generally, but not limited to, the method of applying a solution containing the components constituting the print-receptive layer to the surface of the protective layer and drying. . When the protective layer also serves as the print receiving layer, an ionic surfactant or the like may be added to a monomer or oligomer such as an ultraviolet curable resin, and then the protective layer may be formed by the method described above.

If necessary, an intermediate layer such as a second protective layer, an adhesive layer, a dye diffusion preventing layer and an elastic layer may be provided between the protective layer and the print receiving layer. Further, the print receiving layer can be partially provided instead of the entire surface of the protective layer.
The surface of the optical recording medium of the present invention can be printed using any of water-based ink, oil-based ink, UV-curable ink, etc., but ions having the opposite polarity to the ionic surface of the print-receiving layer are used. The effect of the present invention is most remarkable when a water-based ink is used. That is, it is preferable to use an anionic ink when the print receiving layer has a cationic surface and a cationic ink when the print receiving layer has an anionic surface. Since anionic inks are the mainstream in commercially available water-based printing inks, it is more preferable to make the print-receiving layer of the optical recording medium cationic because it is easy to adapt to the already established printing process.

Therefore, as the most preferred embodiment of the present invention,
Examples thereof include a method of incorporating a cationic surfactant in the print receiving layer. The first such cationic activator is
Amines from quaternary to tertiary, quaternary ammonium salts,
Examples thereof include imidazole salt, sulfonium salt, phosphonium salt and arsonium salt. Further, amphoteric surfactants containing a cationic group such as betaine type, glycine type, alanine type and sulfobetaine type surfactants can be preferably used.

The method for printing on the surface of the optical recording medium of the present invention may be writing or screen printing, but printing with an ink jet printer is particularly preferred. The inkjet printer has no mechanical shock such as hitting at the time of printing and thermal shock such as heating for fixing the ink, and thus does not damage the optical recording medium. Similarly, printing by the bubble jet method can be preferably applied.

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these as long as the gist thereof is not exceeded. Example 1 As a transparent substrate, a recording groove having a diameter of 120 mm provided with a periodically meandering tracking groove for a recordable compact disc,
A polycarbonate substrate having a thickness of 1.2 mm was used.

The light-absorbing layer was formed by dissolving the metal-containing azo dye in a concentration of 2.4% by weight in methyl cellosolve, filtering and then forming a film on the transparent substrate by spin coating. After the dye was applied, it was dried in an oven at 80 ° C. for 10 minutes to remove the solvent. Then, a gold film having an average thickness of 100 nm was formed as a light reflection layer on the light absorption layer by a DC magnetron sputtering method in an argon gas.

Further, an ultraviolet curable resin (trade name: SD-318; manufactured by Dainippon Ink and Chemicals, Inc.) is applied on the light reflecting layer by a spin coating method to a thickness of 3 μm and cured by irradiation with ultraviolet rays. This formed a protective layer. afterwards,
95 parts by weight of UV-curable screen printing ink (trade name: Sericol UV Matt White; manufactured by Teikoku Ink Co., Ltd.) and a cationic surfactant (trade name: Saftomer ST2000H;
5 parts by weight of Mitsubishi Kagaku Co., Ltd. was mixed and the coating solution was stirred until it was uniformly dispersed to apply it to the surface of the protective layer to form a print receiving layer.

Printing was carried out on the obtained disc by the ink jet method using the following two types of ink, and the characteristics were evaluated. The results are shown in Table 1. The inkjet printer is CD-RO manufactured by FGI Co., Ltd.
M printer FA949 was used.

[0024]

Table 1 Ink composition Anion ink C.I. I. Direct Black 38 2 parts by weight Diethylene glycol 30 parts by weight Water 70 parts by weight Cationic ink Diacrylic Supra Black GSL (manufactured by Mitsubishi Chemical) 2 parts by weight Diethylene glycol 30 parts by weight Water 70 parts by weight The characteristics were evaluated according to the following criteria.

(1) As for printability, the sharpness of the obtained print image was visually evaluated and ranked according to the following criteria.

[0026]

[Table 2] ⊚: Very clear. ○: It is clear. Δ: Almost clear. X: The image is faint and repellent, and the image is light.

(2) The drying time was measured by measuring the time required from the printing until the ink was not transferred even when the recycled paper was applied to the image. Those not dried in 30 minutes were set to 30 minutes or longer.

Example 2 A cationic surfactant (trade name Chemistat 7300; manufactured by Sanyo Chemical Co., Ltd.) was used in place of the cationic surfactant (trade name Saftomer ST2000H) in Example 1.
Except that the same was used. The results are shown in Table 1.

Example 3 An anionic surfactant (Chemistat 6120, trade name; manufactured by Sanyo Chemical Co., Ltd.) was used instead of the cationic surfactant (trade name Saftomer ST2000H) in Example 1.
Except that the same was used. The results are shown in Table 1.

Example 4 The same as Example 1 except that an amphoteric surfactant (trade name Saftomer ST1200; manufactured by Mitsubishi Chemical Co., Ltd.) was used instead of the cationic surfactant (trade name Saftomer ST2000H). did. The results are shown in Table 1.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the surfactant was not added to the print receiving layer coating solution. The results are shown in Table 1.

[0032]

[Table 3]

[0033]

According to the present invention, the drying speed of the ink adhering to the surface of the optical recording medium can be increased and the printing can be made clear.

Claims (4)

[Claims] 1. An optical recording medium in which at least a light absorbing layer, a light reflecting layer, a protective layer and a print receiving layer are sequentially laminated on a transparent substrate, wherein the print receiving layer has an ionic surface. recoding media. 2. The optical recording medium according to claim 1, wherein the print receiving layer contains an ionic surfactant. 3. The optical recording medium according to claim 1, wherein the print receiving layer has a cationic surface. 4. The method for printing on the surface of an optical recording medium according to claim 1, wherein an ionic ink having a polarity opposite to that of the print receiving layer of the optical recording medium is used. A method for printing on the surface of an optical recording medium, which comprises: