JP3197400B2 - Optical information media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information medium capable of obtaining good printability.

[0002]

2. Description of the Related Art At present, an optical information medium (hereinafter, referred to as a "CD") having the name of a compact disk is widely used in the fields of audio and information processing. This CD
Is provided with a reflective layer by depositing gold or aluminum on a substrate made of a donut-shaped disc such as polycarbonate,
Further, the structure is covered with a protective layer such as an ultraviolet curable resin. The data is recorded by forming uneven pits according to a spiral arrangement on the surface of the substrate, and the pits are formed in advance according to a mold such as a stamper when forming the substrate. The reflective layer is provided thereon. Therefore, when this CD is manufactured, data is already recorded on it, and it is used as a read-only optical information medium.

[0003] In this CD, an index display indicating the content recorded on the CD and various designs are printed on the surface of the protective layer with ultraviolet curable ink or oil-based ink.
These printings are usually performed by printing means such as screen printing, tampo printing or offset printing, which is performed by transferring a plate. These printing means are printing means suitable for so-called high-volume printing, in which a large number of the same patterns are printed at the same time.

[0004] On the other hand, as symbolized by the so-called karaoke boom, self-performance by amateurs has increased, and as the base has expanded, the activity of amateur players to make a relatively small number of self-made CDs has also become active. These self-made CDs
Are created, for example, for promotion, for audition, for testing, or for self-publishing. In particular, once-once optical information media such as a so-called CD-WO, which can be recorded once using a laser and the recorded content can be reproduced by a CD player, have been developed. It can be easily made. In the field of computers, so-called C
With the widespread use of D-ROMs and the spread of so-called once-write type optical information media, users have come to make their own CD-ROMs using CD-WO.

[0005]

The protective layer of an optical information medium such as a self-made CD made in this manner has nothing written or has a common character or pattern with ultraviolet curable ink or oil-based ink. It is only printed, and before or after recording personal information on the optical information medium, the index of the recorded content and, if necessary, other designs are displayed on the surface of the protective layer or the printed surface of the label. Need arises.

However, the above-mentioned printing means prints in a manufacturing process after providing a protective layer, and since both the surface of the protective layer and the printed surface are hydrophobic, after printing personal information, Excessive equipment is required to print on the surface of the protective layer, and it is difficult to freely print any information personally. Therefore, generally, a method of writing on the surface of the protective layer using an oil-based felt pen or the like, or a method of attaching a label or the like to perform display is used. However, since it is necessary to write by hand one by one, it is troublesome, and the drawn pattern and the drawing quality vary. Was. In addition, particularly when a label is attached, there is a problem that the display surface rises by the thickness of the label, causing eccentricity and surface blurring of the optical information medium during reproduction or additional recording.

[0007] An ink jet method is widely known as a means for easily printing a small number of varieties in a personal manner easily, and it is conceivable to use this method for label printing. However, since the water-based ink is used in the ink-jet method, when simply printing on a conventional optical information medium, the ink is repelled from the surface and immediately falls off when wiped, making it impossible to actually print. . Therefore, it is conceivable to make the printing surface of the optical information medium a hydrophilic film. However, when a non-reactive hydrophilic coating made of, for example, an aqueous solution of polyvinyl alcohol used for an OHP film or the like is used, water resistance is deteriorated, and thus reliability is obtained from the viewpoint of optical recording of an optical information medium. There was a problem that it was not possible.

The present invention has been made in view of the above-mentioned conventional problems, and enables to easily and satisfactorily form certain characters and patterns on the surface of a protective layer of an optical information medium, and to improve reliability from the viewpoint of optical recording. It is an object of the present invention to provide an optical information medium excellent in reliability and printing reliability.

[0009]

That is, in order to achieve the first object, the means adopted in the present invention is a method for forming an optical information medium in which a layer involved in recording or reproduction is formed on a substrate by using a laser beam. a surface other than the incident surface, small in the molecule
An optical information medium characterized by having a hydrophilic surface obtained by curing a polymerizable resin containing a hydrophilic monomer having at least one ethylenically unsaturated bond .

Preferred embodiments of the optical information medium are as follows. The hydrophilic monomer is a polyether-modified mono- or poly (meth) acrylate, (meth)
At least one selected from an acrylamide derivative, a mono- or poly (meth) acrylate having an amino group, a mono- or poly (meth) acrylate having a hydroxyl group, a mono- or poly (meth) acrylate having a phosphoric acid group, and a nitrogen-containing cyclic vinyl monomer One type of monomer is preferred, and more specifically, the hydrophilic monomer is dimethylacrylamide, mono (or) diacrylate having polyethylene glycol units, alkyl-substituted (meth) acrylamide, alkoxy-modified (meth) acrylamide,
Methylol-modified (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyhydric alcohol diglycidyl ether Mono- or poly (meth) acrylate, alkylene oxide-modified mono- or di (meth) acrylate phosphate, caprolactone-modified mono- or di (meth) acrylate phosphate, acryloylmorpholine, N-vinyloxazolidone, N-vinylsuccinimide, N-vinyl At least one monomer selected from pyrrolidone and N-vinylcaprolactam is preferred.

The polymerizable resin is preferably an active energy ray-curable resin, which is a photoinitiator, a hydrophilic resin soluble in a hydrophilic monomer, a thickener, an inorganic or insoluble inorganic monomer in a hydrophilic monomer. Organic pigments may be included .

[0012]

With the optical information medium according to the present invention, the fixability of the printing ink is improved, and characters and designs can be arbitrarily drawn by any writing means using a water-based ink or an oil-based ink. . Of course, it is also possible to use another method such as an ultraviolet curable ink. Furthermore, since the optical information medium according to the present invention has a flat display surface as compared with the optical information medium on which a label or the like is displayed, the occurrence of eccentricity or surface blur during reproduction or additional recording is prevented. can do.

The hydrophilic monomer used in the present invention, which does not meet such demands and improves the printability such as wettability and hydrophilicity of the ink, is a polyether-modified mono- or poly (meta). Acrylate, (meth)
At least one selected from an acrylamide derivative, a mono- or poly (meth) acrylate having an amino group, a mono- or poly (meth) acrylate having a hydroxyl group, a mono- or poly (meth) acrylate having a phosphoric acid group, and a nitrogen-containing cyclic vinyl monomer One monomer is preferred.

The hydrophilic monomer may be dimethylacrylamide, mono (or) diacrylate having a polyethylene glycol unit, alkyl-substituted (meth) acrylamide, alkoxy-modified (meth) acrylamide, methylol-modified (meth) acrylamide, N, N- Dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyhydric alcohol diglycidyl ether mono or poly (meth) acrylate, alkylene oxide modified Phosphoric acid mono- or di (meth) acrylate, caprolactone-modified phosphoric acid mono- or di (meth) acrylate, acryloylmorpholine, N-vinyloxazolidone, N-vinylsa Shiimido, N- vinylpyrrolidone,
By selecting at least one monomer selected from N-vinylcaprolactam, it becomes possible to improve the high hydrophilicity, adhesion, curability, and cured film strength.

The polymerizable resin containing the hydrophilic monomer is as follows:
Active energy ray-curing makes it possible to shorten the production time of the optical information medium. For example, by using the resin as an ultraviolet curing type, it is possible to obtain an optical information medium with less warpage and peeling without applying unnecessary heat to the substrate as compared with thermosetting. In addition, by incorporating a hydrophilic resin soluble in a hydrophilic monomer into the polymerizable resin, the hydrophilicity and viscosity can be adjusted, and the production variation of the optical information medium can be reduced . In addition, by including a thickener in the polymerizable resin, the viscosity can be improved , and the polymerizable resin can be applied to a screen printing method or the like. A resin film can be formed. By including an inorganic or organic pigment insoluble in the hydrophilic monomer in the polymerizable resin, the viscosity can be adjusted and the degree of bleeding or blurring when printed can be adjusted.

[0016]

Next, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 shows the optical information medium as viewed from the back side of the surface on which the reproduction light is incident.
Reference numeral 1 denotes a lower surface side in FIG. As shown in this figure, a polymerizable resin film 26 containing a hydrophilic monomer is formed on the surface of the ultraviolet curable resin layer 25. The hole provided at the center of the optical information medium is a clamp hole 4 for clamping with a clamper of a spindle when the optical information medium is set in a CD player.

FIG. 2 schematically shows a cross section of a so-called once-write type optical information medium as an example of the optical information medium. Translucent substrate 2 made of polycarbonate resin or the like
A guide groove 22 for tracking is formed in a spiral shape on 1, and a dye recording layer 23 is coated thereon. A reflective layer 24 made of a metal film such as gold, silver, or aluminum is formed on the dye recording layer 23, and a protective layer 25 is provided thereon. Further, a polymerizable resin film 26 containing a hydrophilic monomer described later is formed on the protective layer 25.

The plate-shaped translucent substrate 21 used for the optical information medium 2 has a refractive index of 1.4 to laser light.
A resin having a high transparency in the range of 1.6 and having excellent impact resistance is used. Specifically, polycarbonate, polyolefin, acrylic and the like can be exemplified, but not limited to these. The translucent substrate 21 is formed using such a resin material by, for example, an injection molding method. As shown in FIG. 2, a spiral guide groove 22 or a tracking guide unit having another shape may be provided on the surface of such a translucent substrate 21. Such tracking guide means can be usually formed by a known method using a stamper.

This optical information medium has a portion for recording information optically readable by a laser beam, or at least one of a portion for recording the information, and, for example, irradiates a laser beam. As used herein, it means a layer capable of optically reproducing or recording information, a substrate surface involved in recording or reproduction, or another surface. For example, FIG.
In the case of the above-described once-light type optical information medium, the recording and reproduction of information can be performed by the dye recording layer 23 formed on the translucent substrate 21 and the reflection layer 24 formed thereon. I do. On the other hand, in a read-only optical information medium such as a CD in which a light reflecting layer and a protective layer are sequentially laminated on a substrate, information is reproduced by a pit row formed on the light transmitting substrate 21 and a reflective layer covering the pit row. I do.

The method of recording and reproduction is optical, and a method using laser light, a magneto-optical recording and reproduction method, and the like are generally used. Recording and reproduction of such information are performed from one side of the optical information medium, and specifically, are performed by means such as making laser light incident from the front side of the light transmitting substrate 21. No optical information is recorded or reproduced from the other surface side. When laser light is used as recording light and reproduction light, the wavelength is 750.
A wavelength of about 830 nm is generally used, but laser light having a wavelength other than this may be used.

Further, in addition to the dye recording layer 23 and the reflection layer 24 shown in FIG. 2, another layer may be provided. For example,
In some cases, a layer or the like for improving reliability other than recording information may be provided, such as a layer for improving binding. In FIG. 2, the dye recording layer 23 is directly applied on the light-transmitting substrate 21, but another layer may be provided between them.

The protective layer 25 is a layer for protecting the information recording portion against a physical or mechanical failure received from the side opposite to the light transmitting substrate 21 and is provided on the side opposite to the light transmitting substrate 21 side. Such a protective layer 25 is preferably made of a resin having excellent impact resistance. The thickness of the protective layer 25 is preferably in the range of 5 to 10 microns, and it may be composed of a plurality of layers made of different materials.

In general, the protective layer 25 can be obtained by applying a monomer and oligomer of an organic compound which can be polymerized into a polymer, followed by a polymerization reaction. When it is obtained as an organic polymer by a polymerization reaction, if necessary, a polymer, a photoinitiator, a solvent such as methyl ethyl ketone, an alcohol, a leveling agent, an antistatic agent, etc. are added to a monomer or oligomer having an ethylenically unsaturated bond. An advantageous method is to apply the substance to which the substance is added and polymerize the composition by irradiating ultraviolet rays or electron beams. In particular, an ultraviolet curable resin is preferable because it can prevent a bad influence on the substrate and the information layer when the protective layer 25 is formed and can be formed in a short time.

As such an ultraviolet curable resin, a known ultraviolet curable resin can be applied as long as it is used for an optical information medium. Specifically, resins such as N-vinylpyrrolidone, tripropylene glycol diacrylate, trimethylolpropane triacrylate, and hexanediol diacrylate can be exemplified. However, the method of polymerization is not limited to the above-described active energy ray curing, specifically, ultraviolet ray or electron beam irradiation, and even if the polymerization proceeds by heat, such as an epoxy resin or a urethane resin. Alternatively, a polymerization reaction may proceed with moisture in the air, such as a dialkoxysilane coupling agent.

The main chain and side chain of the polymer thus obtained may be a saturated or unsaturated linear hydrocarbon, or may contain a cyclic compound such as melamine or bisphenol. Further, a polyether containing one or more ether bonds in the middle of the main chain or side chain of the polymer,
Other bonds exemplified by polyesters containing ester bonds, polyurethanes containing urethane bonds, ionomers containing ionic bonds, polyamides containing amide bonds, polyimides containing imide bonds, polysulfones containing sulphone bonds, polysulphides containing sulfide bonds, etc. It may be included. A copolymer compound containing two or more of these bonds may be used, or a block polymer may be used.

In order to improve the moisture resistance of these polymers, a fluorocarbon or the like may be contained in the side chain,
An epoxy resin may be included to prevent deterioration due to hydrogen halide. In order to improve the adhesion between the protective layer 25 and an adjacent layer, the side chain of the polymer may contain a hydroxyl group, a carboxyl group, an amino group, or the like, or a basic acid may be contained in the main chain or the side chain. May be included.

When the protective layer 25 is formed, a solvent and a diluent may be contained in the coating in addition to the resin, its reactant, the reaction initiator and the like in order to improve the coating property. Further, in order to stabilize the coating film, a leveling agent, a plasticizer, an antioxidant, an antistatic agent, and the like may be contained. If necessary, they may be colored with pigments or dyes.

The protective layer 25 can be formed by bonding a resin material on the light reflecting layer 24 without depending on means such as coating. The material is not limited to an organic compound, and an inorganic substance may be formed by a known method such as a sputtering method or a vapor deposition method. Further, between the light reflection layer 24 and the protective layer 25, an oxidation-resistant layer for preventing the light reflection layer 24 from being oxidized may be interposed.

In the present invention, in such an optical information medium, the polymerizable resin film 26 containing a hydrophilic monomer is formed on the surface opposite to the side where the reading laser beam is incident so that the printing ink can be fixed. . The polymerizable resin film 26 containing the hydrophilic monomer is a resin film having sufficient hydrophilicity to fix the ink to such an extent that the ink does not bleed even if the aqueous ink is dropped and touched by hand after 30 minutes. It is. That is, it is not a state in which the ink is simply attached by drying the ink, but a film to which the ink can be fixed to such an extent that the ink cannot be easily erased. Polymerizable resin film 2 containing a hydrophilic monomer
The ink printed on 6 absorbs and is fixed on the surface of the polymerizable resin film 26 containing a hydrophilic monomer without reducing the adhesion area.

The polymerizable resin film 26 containing a hydrophilic monomer can be obtained by drying or curing a polymerizable resin material containing a hydrophilic monomer. For example, as shown in FIG. 2, by coating the surface of the protective layer 25 with a polymerizable resin material containing a hydrophilic monomer and forming a polymerizable resin film 26 containing a thin hydrophilic monomer,
The printing ink can be fixed on the surface.
Specific examples of such a hydrophilic monomer include polyethylene glycol 200 diacrylate, New Frontier BPE-10: Daiichi Kogyo Seiyaku Co., Ltd., Blemmer P
ME-400: Mono or di (meth) acrylate having a polyethylene glycol unit such as Nippon Yushi Co., Ltd., N-MAN: Nitto Chemical Industry Co., Ltd., DMMA: Kojin Co., Ltd., NIPAM: Kojin Co., Ltd. ), Etc., DMAEA: Kojin Co., Ltd. and Light Ester DE: having a hydroxyl group such as (meth) acrylate having an amino group such as Kyoeisha Chemical Co., Ltd., hydroxyethyl acrylate or hydroxypropyl methacrylate ( Meth) acrylate, Denecol acrylate DA-21
2: Nagase Kasei Kogyo Co., Ltd. and epoxy ester 400E
A: Polyhydric alcohol diglycidyl ether di (meth) acrylate such as Kyoeisha Chemical Co., Ltd., AR-100,
Alkylene oxide-modified phosphate mono- or di (meth) acrylates such as MR-260 (Daichi Chemical Industry Co., Ltd.), and capractone-modified phosphate mono- or phosphoric acid such as Kayamer PM-21 (Nippon Kayaku Co., Ltd.) Examples include nitrogen-containing cyclic vinyl monomers such as di (meth) acrylate, acryloylmorpholine, and N-vinylpyrrolidone.

As described above, the polymerizable resin containing a hydrophilic monomer is preferably of an active energy ray curable type, specifically, an ultraviolet ray or an electron beam curable type. In order to obtain the active energy ray curability, it is possible to apply a known method in addition to the above description of the protective layer.

Examples of the photoinitiator used for the ultraviolet curing type include acetophenone, benzophenone, Michler's ketone, benzyl benzoin, benzoin ether, benzoyl benzoate, benzyl dimethyl ketal, and 1-hydroxycyclohexyl phenyl ketone. These photoinitiators are appropriately added at 1 to 10% by weight.
Degree, preferably 2 to 6% by weight. 10 initiators
Exceeding the amount by weight will increase the excess amount,
If the physical properties such as hardness are reduced, and less than 1% by weight,
Sufficient curability cannot be obtained.

Furthermore, it is preferable to add a hydrophilic resin soluble in the hydrophilic monomer. Specific examples of the hydrophilic resin soluble in such a hydrophilic monomer include, for example, polyethylene oxide, polyvinyl alcohol, polyvinyl methyl ether, polyvinyl formal, carboxyvinyl polymer, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, sodium carboxymethyl cellulose. Salt, polyvinylpyrrolidone and the like can be mentioned. At least one kind of these hydrophilic resins is prepared, and the above-mentioned hydrophilic monomer, photoinitiator and, if necessary, other additives are blended and coated. These resins are mixed at an adjusted mixing ratio in consideration of the reliability such as weather resistance, water resistance and warpage of the optical information medium and the manufacturability. 5% by weight of hydrophilic resin
As described above, the solubility limit (for example, about 50% by weight) can be considered, but the range is preferably 5 to 20% by weight. If the amount of the hydrophilic resin exceeds 20% by weight, the water resistance becomes poor and the printing workability is reduced. If the content is less than 5% by weight, the wettability of the ink is deteriorated, and blurring after printing is liable to occur.

In the polymerizable resin material containing the hydrophilic monomer, a compound which is soluble in the hydrophilic monomer and has an ethylenically unsaturated bond can be blended. Specific examples of such compounds include styrene, vinyl monomers such as vinyl acetate, (meth) acrylates of alkyl alcohols such as octyl acrylate and stearyl methacrylate, trimethylolpropane triacrylate, and dipentaerythritol hexaacrylate. Polyhydric alcohol (meth) acrylates, trade name ARONIX M-1100 (Toa Gosei Chemical Industry Co., Ltd.), Karayad DPCA-120 (Nippon Kayaku Co., Ltd., etc. polyester (meth) acrylates, (Meth) acrylates of compounds having an epoxy group such as 1,6-hexanediol diglycidyl ether diacrylate, acrylates of bisphenol A type epoxy resin, and acrylates of novolak type epoxy resin And (meth) acrylates of urethane resin which is a reaction product of a terminal isocyanate prepolymer comprising a polyisocyanate and a polyol and a hydroxy group-containing (meth) acrylate.

Additives can be added to the polymerizable resin material containing the hydrophilic monomer, if necessary. For example, water-absorbing pigments, wetting agents, defoamers, surface tension adjusters,
It is also possible to add a thickener or the like. As the absorbing pigment,
Inorganic or organic pigments, such as silica, talc, mica, calcium carbonate, fine pigments such as carboxymethylcellulose, dextrin, and methylcellulose, surface-treated with inorganic or organic substances, and amide-based acrylates by special coating. And organic pigments such as polyvinylpyrrolidone and vinyl acrylate acrylate copolymer (Sumikagel SP-510: Sumitomo Chemical Co., Ltd.).

Examples of the wetting agent include known anionic or nonionic wetting agents (Nopco 2272RSN, Nopco Wet 50, Nopco Wet SN20T: Sannopco Co., Ltd., etc.).
Dehydran 1620: Sannopco, etc.
Perenol S43 and S
5: Sannopco, polyethyleneimine:
SP103: Nippon Shokubai Co., Ltd., Aerosil 200: Nippon Aerosil Co., Ltd. exemplifies thickening agents such as anhydrous silica, polyvinylpyrrolidone, dibenzylidene sorbitol, oxidized wax, ethylenebisstearylamide, castor oil with water and bentonite. Can be.

The addition of a water-absorbing pigment as an additive plays a role in adjusting the printability of the ink and the workability in forming a hydrophilic film. By adding a wetting agent, wettability can be improved, fluidity can be adjusted, and a low-foaming material can be obtained. By adding an antifoaming agent or a surface tension adjusting agent, it is effective only to form a coating film without unevenness.

By adding a pigment, the polymerizable resin film 26 containing a hydrophilic monomer can be made opaque, cloudy, or colored. This makes it possible to select an appropriate optical information medium according to the color of the ink and the degree of printing, thereby improving the appearance. It is also possible to form a relief pattern by forming a so-called nucleated portion by utilizing the color of a layer provided below the protective layer.

The thickness of the polymerizable resin film 26 containing a hydrophilic monomer is preferably in the range of 5 to 30 microns in order to prevent the recording / reproducing characteristics of the optical information medium from being affected. Such a film thickness can be obtained by appropriately blending the above materials and adjusting the viscosity and the like.
The buffering effect can be enhanced by making the polymerizable resin film 26 containing a hydrophilic monomer thicker than the protective layer 25. This polymerizable resin film 26 containing a hydrophilic monomer is preferably formed on a protective layer 25 made of an ultraviolet curable resin.

The bonding strength of the layer boundary between the polymerizable resin film 26 containing a hydrophilic monomer and the protective layer 25 is better than the bonding strength of the layer boundaries of the other layers constituting the light-transmitting substrate. Is preferred. For such binding properties, a combination of an ultraviolet curable resin material forming the protective layer 25 and a polymerizable resin material containing a hydrophilic monomer thereon is appropriately selected, and the film forming method as described above is employed. Can be obtained by: For example, a reflective film 2 having a dye recording layer 23 and a metal reflective film 24 on a substrate,
In the case of an optical information medium as shown in FIG. 2 in which a protective layer 25 made of an ultraviolet curable resin such as an epoxy resin or an acrylic resin is provided on the polymer resin 4, an amide monomer and a polyvinyl resin are used as the polymerizable resin film 26 containing a hydrophilic monomer. By providing a resin film containing pyrrolidone, the above-described binding property can be obtained. Protective layer 25 and polymerizable resin film 2 containing hydrophilic monomer
When the binding property of the layer boundary with layer 6 is preferable, even if the polymerizable resin film 26 containing a hydrophilic monomer is formed only on a part of the surface of the protective layer 25, it is difficult to be peeled off. Demonstrate function. Further, warpage and peeling of the optical information medium are reduced, so that deterioration of recording and reproduction characteristics is prevented.

In order to prevent the optical information medium from warping or the like, the shrinkage rate when forming the polymerizable resin film 26 containing a hydrophilic monomer is smaller than the shrinkage rate when curing the ultraviolet curable resin forming the protective layer 25. Is preferred. Further, from the viewpoint of protecting the optical information medium against writing pressure, printing pressure, and the like, the hardness of the polymerizable resin film 26 containing a hydrophilic monomer is smaller than the hardness of the protective layer 25, for example, the protective layer described above in pencil hardness. 25
Is preferably smaller than 2H to 7H / Glass. Since such shrinkage and hardness depend on the number of functional groups of the monomer compounded in the polymerizable resin film 26 containing a hydrophilic monomer, depending on the physical properties of the compounding material, two or more monofunctional monomers or functional groups may be used. It can be obtained by appropriately selecting the degree of monomer. By doing so, it is possible to prevent the reliability of the optical information medium from deteriorating due to warpage, peeling, and the like, and stable recording and reproduction can be performed.

The polymerizable resin film 26 containing a hydrophilic monomer
May be provided over the entire surface of the protective layer 25, but may also be provided, for example, as shown in FIG. It is preferable that the surface of the polymerizable resin film 26 containing a hydrophilic monomer be a fine rough surface. When the printing ink adheres to the surface 2 of the protective layer 25 due to the fine surface state, the printing ink Is retained and fixed, that is, a so-called anchor effect is provided. In addition, the surface area of the polymerizable resin film 26 containing a hydrophilic monomer is increased by the rough surface, and ink absorption can be promoted.

The term "rough surface" as used herein means a surface having a smaller contact angle with the aqueous ink than when the surface is not rough, and preferably has an average roughness (Ra) measured by a stylus type surface roughness measuring instrument.
Is preferably about 2.0 to 0.1 μm. The effect of this surface roughness on the aqueous ink is slightly different depending on the physical properties of the film. If the surface roughness is smaller than 0.1 μm, fine lines can be drawn with good resolution, but the ink is formed solid. When the surface roughness is larger than 2.0 μm, both the fine line and the solid line are easily blurred. In particular, an average roughness (Ra) of 0.9
By setting the thickness to about 0.5 μm, both fine line printing and solid printing can be printed practically well.

The fine rough surface of the polymerizable resin film 26 containing such a hydrophilic monomer can be formed by gravure coating the surface of the protective layer 25 with a hydrophilic monomer resin. The surface 2 may be formed by coding a resin mixed with a filler by screen printing or spin coating. For example, when an organic or inorganic pigment is dispersed as a filler in a hydrophilic resin, a rough surface can be easily formed, and the anchoring effect is large. The particle size of the pigment is preferably about 1 to 5 μm, particularly 3 to 5 μm.
The size of m is preferable, and in this range, solid printability is improved.

When the surface of the polymerizable resin film 26 containing a hydrophilic monomer is subjected to plasma treatment, the fixability of the ink to the surface of the film 26 is further improved. Specifically, the optical information medium is placed in a dilute inert gas atmosphere in a vacuum state, and plasma is generated in this gas for processing. With such treatment, the surface tension of the ink attached to the treated surface is small, the contact angle of the ink is small, and the so-called ink wettability is improved. Printing of ink on this surface,
It is preferable to perform the treatment as soon as possible after the plasma treatment. The ink applicable to the optical information medium of the present invention is preferably an aqueous ink, but may be an oil-based ink or an ultraviolet-curable ink.

As described above, when characters or the like are printed on the surface 2 of the polymerizable resin film 26 containing a hydrophilic monomer, writing or screen printing can be used, but printing with an ink jet printer is particularly preferable. As you know,
The ink jet printer is used as a printer of a personal computer or the like, and can repeatedly print printed characters and printed patterns created by the computer on the surface of the polymerizable resin film 26 containing the hydrophilic monomer. Therefore, it is suitable for printing certain characters and designs on a relatively small number of optical information media. In addition, since there is no need to apply mechanical shock such as a blow or heat for fixing the printing ink during printing, the optical information medium is not damaged. Similarly, it goes without saying that the present invention can also be applied to a so-called bubble jet method in which ink particles are formed and printed by a bubble jet method in which a nozzle portion is heated by a heater.

The polymerizable resin film 26 containing such a hydrophilic monomer is usually formed on the main surface opposite to the laser light incident surface. Alternatively, an inner peripheral portion such as a clamping area on the surface on the laser beam incident side or an outer peripheral portion not used for laser beam incidence may be used. Further, the optical information medium to which the present invention can be applied is not limited to a read-only medium such as a CD or a write-once type optical information medium, but may be recorded on the surface of a medium having an air sandwich structure or a metal substrate without a substrate. It is a matter of course that the type which performs the above-mentioned is preferable, and it is needless to say that it can be used for an erasable medium. Further, the present invention is not limited to a disk shape, and can be used for an optical card and the like.

As shown in FIG. 3, patterns, characters, figures and the like are displayed 27 on the protective layer 25 in advance by using an ultraviolet curable ink or the like, and a transparent hydrophilic monomer is placed thereon. By providing the polymerizable resin film 26 including the polymer resin film 26, the display 27 may be seen through the polymerizable resin film 26. In this case, when printed on the surface of the polymerizable resin film 26, the display 27 below and the characters, designs, and the like printed on the surface appear to overlap.

Next, specific examples of the present invention will be described.
A guide groove having a width of 0.8 μm, a depth of 0.08 μm, and a track pitch of 1.6 μm has a diameter of 46 to 117 mm in order to spirally guide tracking by a stamper.
120mmφ outer diameter, 15mm inner diameter formed in the range of
Prepare a polycarbonate substrate having a diameter of 1.2 mm and a thickness of 1.2 mm.

0.65 g of 1,1, -dibutyl 3,3,
3,3, tetramethyl 4,5,4,5, -dibenzoindodicarbocyanine perchlorate: The Japan Photographic Dye Laboratories was dissolved in 10 ml of diacetone alcohol, and this was averaged on the substrate while changing the number of revolutions. 130 nm thick
, And dried to form a dye recording layer. On top of this, gold was sputtered to a thickness of 1
A 00 nm reflective layer was formed.

Next, an ultraviolet-curable resin (TYD-102:
San Nopco Co., Ltd.) and apply 230mj with high pressure mercury lamp
/ Cm 2 UV light and cured to a thickness of 10 μm
Was formed. The hardness of the protective layer made of the ultraviolet curable resin is as follows: pencil hardness 5H / on glass (2H /
on PC).

Various resins were blended at the ratios shown in Table 1 and dispersed in a ball mill containing 12 balls of 21 pots over a period of 24 hours to obtain various coating materials shown in Examples 1 to 5. Was prepared. For comparison, a coating material having the composition shown in Comparative Example was also prepared.

[0053]

[Table 1]

However, * 1 to * 12 in Table 1 are as follows. * 1 Compound having a radical polymerizable double bond dissolved in a hydrophilic monomer * 2 Ethylene oxide-modified trimethylolpropane triacrylate (Sannopco Co., Ltd.) * 3 Ethylene oxide-modified bisphenol A diacrylate (Daiichi Kogyo Seiyaku Co., Ltd. * 4) Reactive polyvinyl alcohol (Nitto Chemical Industry Co., Ltd.) * 5 Polyvinylpyrrolidone (ISP Technologies I)
nc. * 6 Trimethylolpropane triacrylate * 7 Epoxy diacrylate (Sannopco Co., Ltd.) * 8 Benzyl dimethyl ketal (Nippon Ciba Geigy Co., Ltd.) * 9 Methyl ethyl ketone peroxide (Nippon Oil & Fats Co., Ltd.) * 10 Cobalt naphthenate ( Nippon Yushi Co., Ltd.) * 11 Anhydrous silica (Nippon Aerosil Co., Ltd.) * 12 Surface-treated silica (Fuji Silysia Chemical Ltd.) In Example 4, a cured film was obtained by irradiating with 2 Mrad electron beam. In Example M, a cured film was obtained by heating at 80 ° C. for 30 minutes.

The coating material thus prepared was screen-printed on the protective layer using a 300-mesh screen except for the inner and outer peripheral edges of the protective layer, under the same conditions as the protective layer. By irradiating ultraviolet rays,
A hydrophilic resin film having a thickness of 15 μm was formed.

A semiconductor laser having a wavelength of 780 nm modulated into an EFM signal and having a power of 7.8 mW and a power of 7.8 mW was applied to this optical information medium.
By irradiating along a guide groove at a linear velocity of 1.4 m / sec, predetermined optical information was recorded. Thereafter, these optical information media were subjected to an accelerated deterioration test at a temperature of 70 ° C. and a humidity of 85% RH. When the surface of the hydrophilic resin film was checked 100 hours after the start of the test, no change from the initial state was observed in any of the samples, as indicated by the circles in Table 2. When the same accelerated deterioration test was carried out for the comparative example, as shown by the crosses, spots seemingly melted on the surface of the medium of Comparative Example 3 after 100 hours from the start of the test. Was.

Next, printing was performed using an aqueous black ink using an ink jet printer, and the ink jet printing performance (IJP performance) was examined. That is, it was checked whether or not kanji having many strokes were printed by an ink jet printer and printing could be performed without crushing the space between the lines. A good print result without fading could be obtained. On the other hand, in the case of Comparative Example 1, as shown by the symbol “△” in Table 2,
Slight blurring occurred, and in the case of Comparative Example 2, the space between the lines was crushed as shown by X in Table 2.

After printing on the surface of the hydrophilic resin film, the printed surface was rubbed by hand three minutes after printing.
As shown by the marks, no blurring occurred. On the other hand, in Comparative Examples 1 and 2, as shown by X in Table 2, bleeding and blurring occurred.

After printing for the IJP test as described above on the surface of the hydrophilic resin film of the optical information medium with an ink jet printer, the print was carried out at a temperature of 70 ° C., a humidity of 85% RH, a temperature of 70 ° C. for 8 hours and a humidity of 0%. 10% RH (DRY)
A 0-hour accelerated deterioration test was performed to confirm fading and blurring of the prints.
Then, a little bleeding was seen, but other things could not see bleeding and blurring. On the other hand, as shown by X in Table 2, all of the comparative examples suffered from bleeding and blurring. Further, in order to compare the binding property between the protective layer and the hydrophilic resin film, a peeling test (cross-cut test) was performed. As shown in Table 2, in Examples 1 to 5, Comparative Examples 1 to 5 were used. Good results were obtained as compared with Nos.

[0060]

[Table 2]

[0061]

As described above, according to the optical information medium of the present invention, certain characters and patterns are easily and satisfactorily written on the surface of the protective layer of the optical information medium using ordinary aqueous ink or oil-based ink. A highly reliable optical information medium that can be obtained.

[Brief description of the drawings]

FIG. 1 is an external perspective view of an optical information medium.

FIG. 2 is a schematic longitudinal sectional view of a main part of an optical information medium showing an embodiment of the present invention.

FIG. 3 is a schematic vertical sectional view of a main part of an optical information medium showing another embodiment of the present invention.

[Explanation of symbols]

 2 Optical Information Medium 4 Clamp Hole 21 Translucent Substrate 22 Guide Groove 23 Dye Recording Layer 24 Reflective Layer 25 Protective Layer 26 Polymerizable Resin Film Containing Hydrophilic Monomer

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takashi Ishiguro 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Yuden Co., Ltd. (56) References JP-A-6-60432 (JP, A) JP-A-8 -102088 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/24 G11B 11/105

Claims (9)

(57) [Claims] 1. An optical information medium in which a layer involved in recording or reproduction is formed on a substrate, a hydrophilic monomer having at least one ethylenically unsaturated bond in a molecule on a surface other than a laser beam incidence surface. An optical information medium having a hydrophilic surface obtained by curing a polymerizable resin containing: 2. The method according to claim 1, wherein the hydrophilic monomer is a polyether-modified monoacrylate, a polyether-modified polyacrylate, a polyether-modified monomethacrylate, a polyether-modified polymethacrylate, an acrylamide derivative, a methacrylamide derivative, Monoacrylate having a group, polyacrylate having an amino group, monomethacrylate having an amino group, polymethacrylate having an amino group, monoacrylate having a hydroxyl group, polyacrylate having a hydroxyl group, monomethacrylate having a hydroxyl group, and hydroxyl group Having polymethacrylate, monoacrylate having phosphoric acid group, monomethacrylate having phosphoric acid group, polyacrylate having phosphoric acid group, polymethacrylate having phosphoric acid group, nitrogen-containing An optical information medium comprising at least one monomer selected from cyclic vinyl monomers. 3. The method according to claim 1, wherein the hydrophilic monomer is dimethylacrylamide, monoacrylate having a polyethylene glycol unit, diacrylate having a polyethylene glycol unit, alkyl-substituted acrylamide, alkyl-substituted methacrylamide, alkoxy-modified acrylamide, alkoxy-modified Methacrylamide,
Methylol-modified acrylamide, methylol-modified methacrylamide, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl acrylate,
N-diethylaminoethyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, polyhydric alcohol diglycidyl ether monoacrylate, polyhydric alcohol diglycidyl ether polyacrylate, polyhydric alcohol diglycidyl ether mono Methacrylate, polyhydric alcohol diglycidyl ether polymethacrylate, alkylene oxide-modified phosphate monoacrylate, alkylene oxide-modified phosphate monomethacrylate, alkylene oxide-modified phosphate diacrylate, alkylene oxide-modified phosphate dimethacrylate, caprolactone-modified phosphorus Acid monoacrylate, caprolactone-modified monomethacrylic acid phosphate At least one selected from the group consisting of phosphate, caprolactone-modified diphosphate phosphate, caprolactone-modified dimethacrylate phosphate, acryloylmorpholine, N-vinyloxazolidone, N-vinylsuccinimide, N-vinylpyrrolidone, and N-vinylcaprolactam An optical information medium characterized by being a monomer of the formula: 4. The optical information medium according to claim 1, wherein said polymerizable resin is an active energy ray curable resin. 5. The optical information medium according to claim 1, wherein said polymerizable resin contains a photoinitiator. 6. The optical information medium according to claim 1, wherein the polymerizable resin contains a hydrophilic resin soluble in the hydrophilic monomer. 7. The one of the optical information medium according to claim 1-6, wherein the polymerizable resin is an optical information medium which comprises a thickener. In any of the optical information medium as claimed in claim 8 according to claim 1-7, wherein the polymerizable resin is an optical information medium which comprises inorganic or organic pigments insoluble in the hydrophilic monomer. 9. claimed in any one of the optical information medium of claim 1-8, the optical information medium, characterized in that the flat display ink is absorbed fixing the hydrophilic surface has been subjected.