JP3159283B2 - 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 that can be printed with a printing ink on a surface opposite to a side where laser light is incident.

[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
Has a structure in which a reflective layer is provided by depositing gold or aluminum on a light-transmitting substrate made of a donut-shaped disk such as polycarbonate, and further a protective layer such as an ultraviolet curable resin is applied on the reflective layer. ing. Then, data is recorded by forming uneven pits on the surface of the light-transmitting substrate according to a spiral arrangement, and the pits are formed in a mold such as a stamper when the light-transmitting substrate is formed. The reflective layer is formed beforehand, and 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] This CD is printed on the surface of a protective layer with an oil-based ink and an index display showing the content recorded on the CD and various designs. 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 disks.

[0005]

The protective layer of an optical information medium such as a self-made CD made in this manner is not described or has only a common character or pattern printed with oil-based ink. Before or after recording personal information on the optical information medium, it is necessary to display an index of the recorded contents and, if necessary, other designs on the surface of the protective layer or the printing surface of the label.

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.

SUMMARY OF THE INVENTION In view of the above problems, the present invention can easily and satisfactorily form certain characters and patterns on the surface of a protective layer of an optical information medium, and furthermore, has a function of protecting reproduction and recording portions. An object of the present invention is to provide a highly reliable optical information medium in an excellent optical information medium.

[0008]

That is, in order to achieve the above object, the means adopted in the present invention is to provide an intermediate layer directly or via another layer on a plate-shaped translucent substrate, A protective layer made of a resin formed in close contact with the intermediate layer directly or via another layer, the protective layer is directly attached to the light-transmitting substrate outside the inner and outer peripheral edges of the intermediate layer, In an optical information medium capable of reproducing and / or recording information optically readable by laser light, a hydrophilic resin film on which a water-based printing ink can be fixed is provided on the surface on the protective layer side. The resin film is provided in an area inside any one of the inner and outer peripheries of the intermediate layer on a plane.

The hydrophilic resin film formed on the protective layer is preferably a hydrophilic resin film provided on the protective layer made of the ultraviolet curable resin layer.

[0010]

In the optical information medium according to the present invention, the hydrophilic resin film on which the printing ink can be fixed is formed on the surface on the protective layer side, which is the back surface on the side where laser light is incident. By fixing an aqueous printing ink on the surface, characters, designs, and the like can be printed. However, the hydrophilic resin film swells when moisture such as aqueous ink adheres, and contracts when it dries. Since the edge of the intermediate layer has a step,
The partial strength is weak, and the hydrophilic resin film may be damaged during swelling and drying. Therefore, in the present invention, the hydrophilic resin film provided on the protective layer side is provided in a region inside any one of the inner and outer peripheries of the intermediate layer on a plane, so that the printing ink When the hydrophilic resin film repeatedly swells and contracts due to adhesion,
Even if a stress occurs in the protective layer, the stress hardly reaches the edge of the intermediate layer. For this reason, cracks, peeling, and peeling are less likely to occur at the edges of the intermediate layer.
Therefore, even if a reliability test such as an acceleration test is performed, it is possible to prevent the recording / reproducing characteristics from deteriorating.

When the protective layer of the optical information medium is formed of a UV-curable resin, a hydrophilic resin film is provided thereon, so that the binding of those layer boundaries can be changed to other layers constituting the light-transmitting substrate. Better than the binding property of the layer boundary. This allows
Peeling of the hydrophilic resin layer on the surface layer of the optical information medium does not occur,
An optical information medium having high weather resistance and high reliability can be obtained.

[0012]

[0013]

Next, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 shows a so-called write-once type optical information medium as an example of the optical information medium, viewed from the back side of a surface on which laser light is incident. I have. As shown in this figure, the hydrophilic resin film 2
6 are formed. 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 taken along the line AA of the optical information medium of FIG. A dye recording layer 23 is coated on a translucent substrate 21 made of polycarbonate resin or the like. On the dye recording layer 23, an intermediate layer 2 made of a metal film of gold, silver, aluminum or the like or other films.
4 and a protective layer 25 is provided thereon.
Further, a hydrophilic resin film 2 described later is formed on the protective layer 25.
6 are formed. The periphery of the protective layer 25 is directly adhered to the translucent substrate 21.

FIG. 4 is a cross-sectional view showing a main part of a printing apparatus for performing ink jet recording on the hydrophilic resin film 26 of such a write-once type optical information medium, and FIG.
The holder 31 holds the optical information medium 2 when performing ink jet recording by such an apparatus.

The holder 31 is rectangular, and has a circular hole 33 at the center of which is slightly larger than the outer diameter of the optical information medium 2, and a step 32 for holding the outer peripheral edge of the optical information medium 2 is provided inside the hole. It is provided over the entire circumference. The depth of the step 3 is slightly smaller than the thickness of the optical information medium 2. For this reason, as shown in FIG. 3, the optical information medium 2 is fitted into the hole 33 of the holder 31 with the hydrophilic resin film 26 side up, and the outer peripheral portion of the optical information medium 2 on the laser light incident surface side is fixed. When supported by the step portion 32, the optical information medium 2 is held by the holder 31 so that the surface of the hydrophilic resin film 26 is slightly higher than the surface of the holder 31.

The optical information medium 2 held by the holder 31 is extended on a feed table 41 of the printing apparatus shown in FIG. 4, and the rollers 42 and 43 are sent to a position where the rollers 42 and 43 hit the end of the holder 31. When a printing signal is input to the printing apparatus from a computer or the like, the holder 3 is driven by driving the rollers 42 and 43.
1 is started. This optical information medium 2 is a table 4
A print head 44 is disposed just above the position where the ink passes over the surface of the hydrophilic resin film 26 of the optical information medium 2.
Print characters and designs on the surface of the.

As described above, the printing apparatus shown in FIG. 4 is an ink jet printer for performing ink jet printing. In this type of printer, a plurality of thin print nozzles are arranged in a print head 44 as is well known. The print nozzle generates a bubble in the ink in the print nozzle by an electrothermal converter operated by an electric signal, for example, and ejects the ink from the nozzle tip. This allows
As described above, ink is attached to a predetermined position on the surface of the hydrophilic resin film 26 of the optical information medium 2 conveyed along the feed table 41.

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.

The optical information medium has at least one of a portion for reproducing or recording information optically readable by a laser beam, and a portion for recording the information. A layer capable of optically reproducing or recording information by irradiation, a light-transmitting substrate surface involved in recording or reproduction, or another surface. For example, in the case of the above-mentioned write-once type optical information medium shown in FIG. 2, information is recorded and recorded by the dye recording layer 23 formed on the translucent substrate 21 and the intermediate layer 24 formed thereon. Enable playback. On the other hand, in a read-only optical information medium such as a CD in which a light reflection layer and a protective layer are sequentially laminated on a light-transmitting substrate, a pit row formed on the light-transmitting substrate 21 and a reflection layer covering the pit row are formed. Reproduce information.

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. In this way, a layer adjacent to the recording layer that absorbs and reflects light and prevents light transmission so that recording and reproduction are not performed from the other surface side is defined as an intermediate layer in the present invention. It is not necessarily limited to a layer having a high reflectance. When a laser beam is used as the recording light and the reproduction light, a laser beam having a wavelength of 770 to 830 nm is generally used, but a laser beam having another wavelength may be used.

Further, in addition to the dye recording layer 23 and the intermediate 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 desirably a resin having excellent impact resistance. For example, the hardness of the protective layer 25 is desirably 2H to 7H / Grass in pencil hardness. The thermal deformation temperature of the protective layer 25 is desirably 80 degrees or higher, and more desirably 100 degrees or higher. 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 crosslinking reaction. When this is obtained as an organic polymer by a cross-linking reaction, from the viewpoint of workability, a mixture of a monomer and an oligomer of an organic heavy compound having one or more reactive acryloyl groups (—CH ＝ CH 2) in a molecule, a reaction initiator, It is advantageous to add a small amount of a reaction catalyst, apply a mixture of these in a liquid state with a solvent such as methyl ethyl ketone or alcohol, and crosslink the mixture by irradiating ultraviolet rays or electron beams. In particular, an ultraviolet curable resin is preferable because the protective layer 25 can be formed in a short time by preventing the transparent substrate and the information layer from being adversely affected when the protective layer 25 is formed. Such an ultraviolet curable resin is
As long as it is used for an optical information medium, a known ultraviolet curable resin can be applied. Specifically, resins such as N-vinylpyrrolidone, tripropylene glycol diacrylate, trimethylolpropane triacrylate, and hexanediol diacrylate can be exemplified.

However, the method of cross-linking is not limited to the above-described ultraviolet irradiation, but may be a method in which cross-linking proceeds by heat, such as an epoxy resin or a urethane resin, or a dialkoxysilane coupling agent. The polymerization reaction may proceed with moisture in the air as described above.

The main chain and side chain of the thus obtained crosslinked product may be a saturated or unsaturated linear hydrocarbon, or may contain a cyclic compound such as melamine or bisphenol. Also, a polyether containing one or more ether bonds in the middle or main chain of the crosslinked product,
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 crosslinked products, 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 the intermediate layer 24 or the hydrophilic resin layer 26, the crosslinked product contains a hydroxyl group, a carboxyl group, an acrylic group, an amino group, a vinyl acetate group, or the like in a side chain thereof. Or
The main chain or side chain may contain a basic acid.

When the protective layer 25 is formed, a solvent and a diluent may be contained in the coating to improve coating properties, in addition to the resin and its reactant, reaction initiator, and the like. 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 curing of the resin can be changed depending on the crosslink density of the crosslinked structure or the concentration of reactive acroyl, and also depends on the degree of freedom of molecular rotation of the oligomer itself which can be a main chain. If the shrinkage ratio during curing of the protective layer 25 is reduced, the protective layer 25 is less likely to crack even when a heat cycle test is performed after curing to prevent resin distortion. In consideration of mechanical strength, this shrinkage is preferably 12% or less, and more preferably 10% or less.

The protective layer 25 can also be formed by bonding a resin material on the intermediate 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, an oxidation-resistant layer for preventing oxidation of the intermediate layer 24 may be interposed between the intermediate layer 24 and the protective layer 25.

In the present invention, in such an optical information medium, the hydrophilic resin film 26 is formed so that the printing ink can be fixed on the surface opposite to the side where the reading laser beam is incident. The hydrophilic resin film 26 is a resin film having sufficient hydrophilicity to drop the aqueous ink and fix the ink to such an extent that the ink does not bleed even if touched by hand after 30 minutes. 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. The ink printed on the hydrophilic resin film 26 does not reduce the attached area,
It is fixed on the surface of the hydrophilic resin film 26.

For example, as shown in FIG. 2, the surface of the protective layer 25 is coated with a hydrophilic resin and a thin hydrophilic resin film 26 is formed so that the printing ink can be fixed on the surface. I have. The hydrophilic resin film 26 is formed inside the intermediate layer 24 on a plane, that is, in a region inside any one of the inner and outer peripheries. More preferably, as shown in FIG. 2, the hydrophilic resin film 26 is preferably formed on a plane in a region inside both the outer and inner peripheries of the intermediate layer 24. However, for example, when the protective layer 25 extends to the peripheral surface of the outer peripheral edge of the light-transmitting substrate 21 and is directly adhered to the same peripheral surface, bonding at the outer peripheral edge of the light-transmitting substrate 21 and the protective layer 25 is performed. In such a case, the hydrophilic resin film 26 becomes
May be formed outside the outer circumference of the.

Examples of such a hydrophilic resin include, for example, polyethylene oxide (polyethylene).
oxide), polyvinyl alcohol (polyvi)
Nyl alcohol, polyvinyl methyl ether, polyvinyl formal (polyvinyl format)
l), carboxyvinyl polymer (carboxyvi)
nyl polymer, hydroxyethylcellulos
e), hydroxypropylcellulose (hydroxy)
propyl cellulose, methylcellulose, carboxymethylcellulose sodium salt (sodium car)
boxymethylcellulose, polyvinylpyrrolidone (polyvinylpyrrolidone)
ne), morpholine, ketone formaldehyde, styrene / maleic anhydride copolymer, shellac, dextrin, poly (pyrrolidonyl ethyl acrylate), polyacrylic acid and its metal salts, polyamine, polyacrylamide, polyethylene glycol Polydiethylaminoethyl (meth) acrylate, polyhydroxystyrene, polyvinylalkyl ether, polyvinylhydroxybenzoate, polyphthalic acid, cellulose acetate hydroxydiene phthalate, for example, LH-40 having a main chain of methyl methacrylate and a side chain of N-methylolacrylamide ( Soken Chemical Co., Ltd.)
Such as graft primers, water-soluble alkyd, water-soluble polyester, water-soluble polyepoxy, polyamide, polyvinyl methyl ether, saponified polyvinyl acetate,
Examples thereof include carboxymethylcellulose, carboxymethylcellulose sodium salt, gum arabic, guar gum, sodium alginate and the like. At least one of these hydrophilic resins is prepared, and a photopolymerizable monomer and a photoinitiator described below, and other additives as necessary, are blended and coated.

These resins are mixed and adjusted in balance 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 it is desirable to set the range of 15 to 20% by weight. If the amount is too large, the water resistance becomes poor, and the printing workability tends to deteriorate. If the amount is too small, the wettability of the ink is deteriorated, and fading after printing is liable to occur.

It is desirable to add a photopolymerizable monomer to the hydrophilic resin. Further, a hydrophilic photopolymerizable monomer may be used instead of the resin. Examples of the hydrophilic photopolymerizable monomer include polyether-modified mono (meth) acrylate, (meth) acrylamide derivative, mono (meth) acrylate having an amino group, mono (meth) acrylate having a hydroxyl group, and mono (meth) acrylate having a phosphate group. At least one monomer selected from (meth) acrylates and nitrogen-containing cyclic vinyl monomers is exemplified. Specifically, dimethylacrylamide (SN-SX
-2833: manufactured by San Nopco), polyethylene, mono (meth) acrylate having a glycol unit, alkyl-substituted (meth) acrylamide, alkoxy-modified (meth) acrylamide, methylol-modified (meth) acrylamide, N, N-dimethylaminoethyl (meth) A) acrylate, N, N-diethylaminoethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyhydric alcohol diglycidyl ether mono (meth) acrylate, alkylene oxide-modified mono (meth) acrylate phosphate , Caprolactone-modified mono (meth) acrylate phosphate, acryloylmorpholine, N-vinyloxazolidone, N
At least one selected from vinyl succinimide, N-vinyl pyrrolidone and N-vinyl caprolactam
Species of monomers. Further, in order to improve photocurability, (meth) acrylates of polyhydric alcohol and its alkylene oxide adduct, polyhydric alcohol diglycidyl ether di (meth) acrylate, and the like are used. These are appropriately added in an amount of about 50 to 100% by weight.

A photoinitiator is added to these to form an ultraviolet curable resin. Specific examples of the photoinitiator include acetophenone, benzophenone, Michler's ketone, benzyl benzoin, benzoin ether, benzoyl benzoate,
Benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, thioxanthones, benzyl,
-Ethylanthraquinone, methylbenzoyl formate, diacetyl and the like. These photoinitiators,
It is appropriately added in an amount of about 1 to 8% by weight, preferably 2 to 6% by weight. If the amount of the initiator is too large, the printing workability tends to be deteriorated. If the amount is too small, the curing time is long and the productivity is lowered, or the ultraviolet curability cannot be obtained. In addition, you may mix said resin with a photopolymerization monomer for viscosity adjustment.

An additive may be separately added to the hydrophilic resin material. For example, it is also desirable to incorporate a water-absorbing pigment, a wetting agent, a defoaming agent, a surface tension adjusting agent, and the like. Specifically, inorganic powders such as finely divided silica, talc, mica, calcium carbonate, titanium oxide, zinc white, colloidal silica, carbon black, red iron oxide, fine powders such as carboxymethylcellulose, dextrin, methylcellulose, etc .; Organic pigments such as polyvinylpyrrolidone, vinyl acrylate copolymer (Sumikagel SP-510: manufactured by Sumitomo Chemical Co., Ltd.), collagen powder, etc., insoluble in acrylates and the like, and known anionic or nonionic wetting agents (Nopco 2272RS)
N, Nopcowet 50, Nopcowet SN20T:
All are manufactured by San Nopco), antifoaming agent (Nopco 8034: manufactured by San Nopco, Dehydran 1620: manufactured by Henkel, AD9)
301: manufactured by Mitsubishi Rayon Co., Ltd., surface tension modifiers (perenol s43, s5: manufactured by Henkel), thickeners such as polyethyleneimine (SP103 Nippon Shokubai Co., Ltd.).

The water-absorbing pigment as an additive plays a role in adjusting the printability of the ink and the workability in forming a hydrophilic film. The wetting agent improves the wettability, adjusts the fluidity, can obtain a low foaming agent, and uses the same equipment as another layer forming step in the manufacturing process of the optical information medium such as screen printing. Can be formed,
Manufacturing efficiency can be improved. An antifoaming agent or a surface tension adjusting agent can form a coating film without unevenness.

The hydrophilic resin film 26 can be made opaque, cloudy, or colored by a pigment. 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 hydrophilic resin film 26 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. Also, the hydrophilic resin film 2
In No. 6, the buffering effect can be enhanced by making the thickness of the protective layer 25 larger than that of the protective layer 25.

The hydrophilic resin film 26 is desirably formed on the protective layer 25 made of an ultraviolet curable resin. In particular, immediately after the formation of the UV-curable resin film as the protective layer 25, that is, before the UV-curable resin serving as the base is cured but its activity is lost, that is, radical molecules in the UV-curable resin react. Alternatively, by forming the hydrophilic resin film 26 in a state where it remains without disappearing, the layer boundaries can be integrated to improve the binding property.

It is desirable that the bonding between the layer boundaries between the hydrophilic resin film 26 and the protective layer 25 is better than the bonding between the layer boundaries of the other layers constituting the light-transmitting substrate. Such a binding property can be obtained by appropriately selecting a combination of an ultraviolet curable resin material for forming the protective layer 25 and a hydrophilic resin material thereon, and employing the film forming method as described above. it can. For example, as shown in FIG. 2, a dye recording layer 23 and a metal reflective film 24 are provided on a light-transmitting substrate, and a protective layer 25 made of an ultraviolet curable resin such as an epoxy resin or an acrylic resin is provided on the reflective film 24. In the case of a suitable optical information medium, as the hydrophilic resin film 26,
By providing a hydrophilic resin film containing an amide-based acrylate and polyvinylpyrrolidone, the above-described binding properties can be obtained. When the layer boundary between the protective layer 25 and the hydrophilic resin film 26 has a good binding property, the hydrophilic resin film 26 is hardly peeled off even if it is formed only on a part of the surface of the protective layer 25, and the optical information is formed together with the protective layer 25. Demonstrate media protection. Further, warpage and peeling of the optical information medium are reduced, so that deterioration of recording and reproduction characteristics is prevented. However, it is desirable that the strength is weaker than the binding property between the light-transmitting substrate and the protective layer. By doing so,
Even when the hydrophilic resin film expands and contracts, it can be prevented from being separated from between the protective layer and the light transmitting substrate.

In order to prevent the optical information medium from warping or the like, it is desirable that the shrinkage rate when forming the hydrophilic resin film 26 is smaller than the shrinkage rate when drying the ultraviolet curable resin forming the protective layer 25. From the viewpoint of protecting the optical information medium against writing pressure, printing pressure, and the like, the hardness of the hydrophilic resin film 26 is set to
It is desirable that the hardness of the protective layer 25 is smaller than the hardness 2H to 7H / Grass described above, for example, in pencil hardness. Such a shrinkage or hardness depends on the number of functional groups of the monomer compounded in the ultraviolet curable resin forming the protective layer 25 and the hydrophilic resin film 26 formed thereon. Can be obtained by appropriately selecting a monofunctional monomer or a monomer having about two functional groups as the hydrophilic resin according to the physical properties of the hydrophilic resin. 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.

It is preferable that the surface of the hydrophilic resin film 26 has a fine rough surface. When the printing ink adheres to the surface 2 of the protective layer 25, the printing ink is held in the fine concave portions due to the fine surface condition. So-called anchoring effect. In addition, the surface area of the hydrophilic resin film 26 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 0.9 to 0.1 μm. The effect of this surface roughness on water-based inks varies slightly depending on the physical properties of the film.However, when the surface roughness is small, fine lines can be drawn with good resolution, When formed, there is a risk of fading. If the surface roughness is too large, both fine lines and solids are likely to bleed. In particular, the average roughness (Ra) is 0.8 to 0.3.
By setting the thickness to about μm, both fine line printing and solid printing can be printed practically well.

The fine rough surface of the hydrophilic resin film 26 can be formed by gravure coating a hydrophilic resin on the surface of the protective layer 25. For example, a filler is mixed on the surface 2 of the protective layer 25. It can also be formed by coating the applied resin 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 suitably about 1 to 5 μm, and especially when the size is 3 to 5 μm, solid printability is improved.

When the surface of the hydrophilic resin film 26 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. It is desirable to print the ink on this surface 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 hydrophilic resin film 26, writing, screen printing, or the like can be used, but printing with an ink jet printer is particularly preferable. As is well known, the ink jet printer is used as a printer of a personal computer or the like, and can repeatedly print a print character or a print pattern created by the computer on the surface of the hydrophilic resin film 26. 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 an impact such as an impact at the time of printing or heat for fixing the printing ink, 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.

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
A polycarbonate translucent substrate having a diameter of 1.2 mm and a thickness of 1.2 mm is prepared. The hardness of this translucent substrate is Pencil hardness HB
(Upilon: manufactured by Mitsubishi Gas Chemical Company), and had a coefficient of thermal expansion of 6 × 10 -5 / ° C. at 20 to 120 ° C.

0.65 g of 1,1, -dibutyl 3,3,
3,3, tetramethyl 4,5,4,5, -dibenzoindodicarbocyanine perchlorate (manufactured by Japan Photochromic Laboratories) was dissolved in 10 ml of diacetone alcohol, and the solution was placed on the light-transmitting substrate at a rotational speed of 10 ml. Was appropriately changed to obtain an average film thickness of 130 nm, and dried to form a dye recording layer. Over this, a ring-shaped mask was covered, and gold was sputtered to form an intermediate layer having a thickness of 100 nm. Thereafter, the above-mentioned dye on the outer periphery of the gold coating was wiped off.

Next, an ultraviolet curable resin (SD-1) containing a polyfunctional acrylate monomer as a main component by a spin coating method.
7: manufactured by Dainippon Ink) so as to be directly applied to the outside of the inner and outer peripheral edges of the gold film, and 230 mj using a 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 this UV-curable resin is as follows: Pencil hardness 5H / on glass (2
H / on PC).

As the component A, a monofunctional ultraviolet curable amide acrylate containing a photoinitiator (SN5X-283)
3: Sannopco) as a C component, polyethylene glycol diacrylate (SN) having a bifunctional molecular weight of 400
5X-2911: manufactured by San Nopco)
As the B component, powdery polyvinylpyrrolidone (K9
0: manufactured by Tokyo Chemical Industry Co., Ltd.) in an amount of 10% by weight and sufficiently dissolved and mixed. Then, as a D component, finely divided silica having a particle size of about 4 μm (XR37B: Tokuyama Tatsuda, D component) or D ′ in this liquid. As a component, polyvinylpyrrolidone resin particles having a particle diameter of about 4 μm (KOLID
ON CLM: BASF) was mixed in the following ratio, and these were dispersed using a ball mill containing 12 balls of 21 pots over 24 hours to prepare a hydrophilic resin solution.

Example 1 A component: B component: C component: D component = 67: 15: 5: 13 Example 2 A component: B component: C component: D ′ component = 65: 15: 5: 15 3 A component: B component: C component: D component = 57: 15: 15: 13 Example 4 A component: B component: C component: D ′ component = 50: 15: 20: 15 After forming the protective layer, 300 Using a mesh screen, apply this hydrophilic resin solution to φ44-11 on the protective layer.
7 is screen-printed concentrically and irradiated with ultraviolet light under the same conditions as for the protective layer to give a thickness of 12
A μm hydrophilic resin film was formed. This hydrophilic resin film is
Inward from the inner and outer peripheral edges of any of the dye recording layer and the metal film
Side region.

In the first to fourth embodiments, the third embodiment
Table 1 shows the time-dependent changes in the viscosity of the hydrophilic resin solution used in Examples 1 and 2. Further, to compare the shrinkage rate, the ultraviolet-curable resin and the hydrophilic resin used for the protective layer were both applied at a thickness of 15 μm on a 10 μm-thick polyethylene terephthalate film, and cured by irradiating ultraviolet rays. The ultraviolet curable resin used for the protective layer was not bent, and the hydrophilic resin film was not bent. That is, the ultraviolet curable resin used for the protective layer has a larger shrinkage ratio than the hydrophilic resin film.

[0055]

[Table 1]

The surface state of the hydrophilic resin film thus formed is a semi-transparent rough surface, and the surface roughness (Ra)
Was measured with a stylus-type surface roughness meter (DEKTAK3030: manufactured by Becoin Instruments Inc.).
0.9 to 0.6 μm. The hardness of the resin is
All have pencil hardness 4H / on glass (2H / o
n PC).

The optical information medium obtained in this way has EF
A 780 nm wavelength semiconductor laser modulated into an M signal,
By irradiating along the guide groove at a power of 7.8 mW and a linear velocity of 1.4 m / sec, predetermined optical information was recorded. Thereafter, the temperature of the optical information medium was set to 70 ° C. and the humidity was set to 8
An accelerated deterioration test of 5% RH was performed. After confirming the surface of the hydrophilic resin film after 100 hours from the start of the test,
No change from the initial state was observed. For comparison, a similar accelerated deterioration test was performed on an OHP sheet for ink-jet printing. As a result, spots seemingly melted on the surface 100 hours after the start of the test.

Further, in the accelerated deterioration test, before the test (initial stage), at 24 hours after the start of the test, and at 100 hours after the start of the test, an ink jet printer was used to print using water-based black ink at different places. Inkjet printer printing performance (IJP performance) was examined. In other words, whether an ink-jet printer prints “●” or “■”, prints solid without printing in a mesh pattern, prints kanji with many strokes, and prints without breaking the space between lines. The kanji printability was examined. The results are as shown in Table 2.

[0059]

[Table 2] ─────────────────────────────────── Initial 24 hours later 100 hours later ──── ─────────────────────────────── Example 1 Solid printability Slightly blurred-Kanji printability better than initial-Good-Good Example 2 Solid printability Slightly faint-More blurring from the beginning Kanji printability Good-Good Example 3 Solid printability Good Good Good Kanji printability Good Good Good Example 4 Solid printability Good Good Slight kanji printability Good Good Good OHP sheet Solid printability Faint-Same as the initial (76 hours) Kanji printability Good-Same as the initial (76 hours) ────────────────────────── ─────────

For Examples 3 and 4, a temperature of 70
Table 3 shows the results of an accelerated deterioration test performed at 0 ° C. and a humidity of 0% RH (DRY) to check the IJP performance before and after the test.

[0061]

[Table 3]

For Examples 3 and 4, a temperature of 70
Table 4 shows the warp angles of the optical information medium measured before and after an accelerated deterioration test was performed at 0 ° C. and a humidity of 0% RH (DRY). Table 4 also shows the warp angle after leaving for 98 hours under standard conditions of a temperature of 23 ° C. and a humidity of 50% RH. In addition,
The warp angle was measured in a radial direction at a position having a radius of 55 mm from the center according to the CD standard, and the average value was shown. The comparative example has a protective layer having a thickness of 25 μm and does not have a hydrophilic resin film. In each case, the angle is 0.6 ° or less specified by the CD standard.

[0063]

[Table 4] 角 Warp angle (°) 100 hours after initial standard condition (98 hours) ─── ───────────────────────── Example 3 0.05 0.18 0.13 Example 4 0.02 0.17 0.15 Comparison Example 0.02 0.17 0.15────────────────────────────

Further, printing for the IJP test as described above was performed on the surface of the hydrophilic resin film of the optical information medium with an ink jet printer, and the printing was performed at a temperature of 70 ° C. and a humidity of 85% RH and a temperature of 70 ° C. for 8 hours. A 100-hour accelerated deterioration test was performed under the condition of 0% RH (DRY), and blurring or blurring of the print was confirmed. As a result, almost no blurring or blurring was observed. After printing on the surface of the hydrophilic resin film, the printed surface was rubbed by hand three minutes after printing, but no blurring or the like occurred. In order to compare the binding property between the protective layer and the hydrophilic resin film, a peel test (cross-cut test) was performed. As a result, at the interface between the metal film and the protective layer , 97/100
On the other hand, it was 100/100 at the interface between the protective layer and the hydrophilic resin film .

Further, 100 sheets of the optical information medium were placed in water.
Immersed for 1 week, pulled up, dried, cross-sectioned, and
When inspected for peeling, no abnormality such as peeling between the layers was observed. On the other hand, for comparison, an optical information medium in which a hydrophilic resin film having a thickness of 12 μm was provided in a portion of φ38 to 119 was manufactured. The hydrophilic resin film of this optical information medium is different from the dye recording layer.
The inner and outer edges of the hydrophilic resin film
Are located outside the inner and outer peripheral edges of the dye recording layer. this
In the same manner, the optical information medium was subjected to the tests of immersion in water and drying . As a result, delamination of the inner and outer peripheral portions was observed in 15 out of 100 sheets.

[0068]

As described above, according to the optical information medium of the present invention, it is possible to easily and satisfactorily form certain characters and patterns on the surface of the protective layer of the optical information medium. In the optical information medium having the excellent protection function, a highly reliable optical information medium can be provided.

[Brief description of the drawings]

FIG. 1 is an external perspective view of an optical information medium according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an exploded perspective view of a holder and an optical information medium used when printing on the surface of the optical information medium of the embodiment using an ink jet printer.

FIG. 4 is a schematic cross-sectional view of a main part showing an ink jet printer used for printing on the optical information medium of the embodiment.

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-43826 (JP, A) JP-A-6-60432 (JP, A) JP-A-2-236833 (JP, A) JP-A-4- 285738 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 7/24

Claims (2)

(57) [Claims] An intermediate layer is provided on a plate-shaped translucent substrate directly or through another layer, and furthermore, a protection made of a resin formed in close contact with the intermediate layer directly or through another layer. Have layers
In an optical information medium capable of reproducing and / or recording information optically readable by a laser beam , the protective layer
Is a light-transmitting substrate outside the inner and outer peripheral edges of the intermediate layer.
A hydrophilic resin film which is directly adhered and on which a water-based printing ink can be fixed is provided on the surface on the side of the protective layer, and the hydrophilic resin film is formed on a peripheral portion of both the inner and outer peripheries of the intermediate layer on a plane.
An optical information medium characterized by being provided in a region inside . 2. The optical information medium according to claim 1, wherein the protective layer is made of an ultraviolet curable resin.