JP3197418B2 - 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] 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 disks.

[0005]

The protective layer of an optical information medium such as a self-made CD made in this manner is not described in anything, or has a common character or pattern with an ultraviolet curable ink or an oil-based ink. Is printed, and before or after recording personal information on the optical information medium, the index of the recorded content is displayed on the surface of the protective layer or the printed surface of the label, and other designs are also displayed if necessary. If it is necessary to do so, a means for attaching a label or the like to perform display is adopted.

However, the above-mentioned printing means prints in a manufacturing process after providing a protective layer, and adversely affects a device in reproducing or recording, and prints on the surface of the protective layer after recording personal information. This requires excessive equipment and it is not only difficult to print any information freely personally, but also because both the protective layer and the printed surface are hydrophobic, fingerprints and dust It was easy to adhere and not only spoiled the appearance, but also required careful handling.

When a label is affixed, or when a display is provided by ultraviolet curable ink or oil-based ink, the display surface rises by the thickness of the label, and the display surface becomes uneven, so that light is not reproduced or reproduced. There has been a problem that eccentricity or surface blur of the information medium is caused. A method of writing on the surface of the protective layer using an oil-based felt pen or the like is also available, but since it must be written by hand one by one, it is troublesome, and the drawn pattern and drawing quality vary,
There is a problem in that the appearance is poor and the appearance of the optical information medium thus formed is impaired. Further, an unnecessary partial stress is applied to the written portion, and in some cases, the recording / reproducing portion may be damaged.

In view of the above-mentioned conventional problems, the present invention has an excellent protection function without causing eccentricity or surface blur of an optical information medium at the time of reproduction or recording, and furthermore, it is possible to prevent fingerprints and dust from adhering. An object of the present invention is to provide an optical information medium which has a small appearance and is easy to handle.

[0009]

That is, in order to achieve the first object, the means adopted in the present invention is formed on a plate-shaped light-transmitting substrate by directly or through another layer. An optical information medium comprising a protective layer made of a cured resin and capable of reproducing and / or recording information optically readable by a laser beam, wherein
A hydrophilic UV-curable resin film capable of fixing an aqueous printing ink is formed on the protective layer, and the surface of the hydrophilic UV-curable resin film has an average roughness Ra of 2.0 to 0.1 μm.
m is a rough surface.

[0010]

[0011]

In the optical information medium according to the present invention, since a flat surface is displayed on the back side on the side where the laser beam is incident, eccentricity and surface eccentricity of the optical information medium during reproduction and recording can be prevented. Never come. Further, by providing the laser light on the back surface side on which the laser beam is incident, the function of protecting the reproduction and recording portions when forming a display is improved.

Further, in the case where a hydrophilic resin film on which a printing ink can be fixed is formed and a flat surface is displayed by fixing the ink on the hydrophilic resin film, a fingerprint is formed because the surface is a hydrophilic resin film. The appearance is good and the handling is easy with little adhesion of dust and dirt. Then, the aqueous ink is fixed on the hydrophilic resin film of the optical information medium, and by performing display,
Fixation becomes good, and a good matt appearance can be obtained. Since the hydrophilic resin film has a thickness sufficient to fix the ink, unnecessary bleeding can be prevented, and a good display can be obtained. A hydrophilic resin film,
When the thickness is larger than that of the lower layer ultraviolet curing resin, it is possible to prevent the optical information medium from being damaged by writing pressure when displaying on the surface with a writing instrument.

Since the hydrophilic resin film has a fine rough surface made of the hydrophilic resin film, the contact angle of the ink is smaller than that of the non-rough surface, so that the ink adheres well and the printability is improved. improves. Further, even when the optical information medium is handled by hand, fingerprints and the like do not adhere to the medium, so that the handleability is improved.

[0014]

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 laser beam is incident, and the translucent substrate 21 is on the lower side in FIG. 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 of a so-called write-once 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 hydrophilic resin film 26 described later is formed on the protective layer 25. FIG.
FIG. 4 schematically shows a further enlarged cross section of a display portion of the optical information medium of the present embodiment, and a hydrophilic resin film 26 described later formed on the protective layer 25 has an aqueous ink 27 or the like.
Has been established.

FIG. 5 is a cross-sectional view showing a main configuration 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 its center 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. 4, the optical information medium 2 is fitted into the hole 33 of the holder 31 with the hydrophilic resin film 26 side facing upward, and the outer peripheral portion of the optical information medium 2 on the laser light incident surface side is moved. 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 in the holder 31 is extended on a feed table 41 of a printing apparatus shown in FIG. 5, 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. 5 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 from such a resin material by, for example, injection molding. As shown in FIG. 2, such a translucent substrate 21
May be provided with a spiral guide groove 22 or a tracking guide means having another shape. 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 recorded portion, for example, for irradiating a laser beam. As used herein, it means a layer capable of optically reproducing or recording information, a light-transmitting substrate surface involved in recording or reproduction, or another surface. For example, in the case of the aforementioned write-once type optical information medium shown in FIG. 2, the dye recording layer 23 formed on the light transmitting substrate 21 is used.
And the reflective layer 24 formed thereon allows information to be recorded and reproduced. 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. 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 protection layer 25 is a layer for protecting the information recording portion against a physical or mechanical obstacle 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 more,
A degree or more is more desirable. The thickness of the protective layer 25 is 5 to 10
The range of microns is desirable, 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 oligomer of an organic heavy compound having one or more reactive acryloyl groups (—CH ＝ CH 2) in the 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. 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, N vinylpyrrolidone,
Resins such as tripropylene glycol diacrylate, trimethylolpropane triacrylate, and hexanediol diacrylate can be exemplified.

However, the method of crosslinking is not limited to the above-described ultraviolet irradiation, and a method of crosslinking by heat, such as an epoxy resin or a urethane resin, may be used. Alternatively, a dialkoxysilane coupling agent may be used. 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 light reflecting layer 24 or the hydrophilic resin film 26, the side chain of the crosslinked product contains a hydroxyl group, a carboxyl group, an acryl group, an amino group, a vinyl acetate group, or the like. And the base chain or side chain may contain a basic acid.

In the formation of the protective layer 25, a solvent and a diluent may be contained during the coating in addition to the resin, its reactant, the reaction initiator and the like in order to improve the coatability. 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 may 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 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. The display thus fixed has a flat surface. Here, "flat" means that there is substantially no difference in surface roughness between the display portion and the non-display portion.

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. Examples of such a hydrophilic resin include, for example, polyethylene oxide (polye).
poly (ethylene oxide), polyvinyl alcohol (polyvinyl alcohol), polyvinyl methyl ether (polyvinylmethyl ethyl)
ther) polyvinyl formal (polyvinyl)
formula), carboxyvinyl polymer (car
boxyvinyl polymer, hydroxyethylcellulose
urose, hydroxypropylcellulose (hyd)
roxypropyl cellulose, methylcellulose, sodium carboxymethylcellulose (sodium)
carboxymethyl cellulos
e), polyvinylpyrrolidone (polyvinyl p)
rrolidone), morpholine
ne), ketone formaldehyde, styrene / maleic anhydride copolymer, shellac, dextrin, poly (pyrrolidonylethyl acrylate), polyacrylic acid and its metal salts, polyamine, polyacrylamide, polyethylene glycol, polydiethylaminoethyl ( LH-40 (manufactured by Soken Chemical Co., Ltd.) comprising meth) acrylate, polyhydroxystyrene, polyvinylalkyl ether, polyvinylhydroxybenzoate, polyphthalic acid, cellulose acetate hydroxydiene phthalate, for example, a backbone of methyl methacrylate and a side chain of N-methylolacrylamide. Such as graft primers, water-soluble alkyd, water-soluble polyester, water-soluble polyepoxy, polyamide, polyvinyl methyl ether, saponified polyvinyl acetate, Cellulose, carboxymethyl cellulose sodium salt, gum arabic, may be mentioned 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 mentioned above, the solubility limit (for example, about 50% by weight) can be considered, but it is desirable to set the range of 5 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 blended with 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 adjusters (perenol s43, s5: manufactured by Henkel), thickeners such as polyethyleneimine (SP103: manufactured by Nippon Shokubai).

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 with 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 desirably 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.

It is desirable that the hydrophilic resin film 26 be formed on the protective layer 25 made of an ultraviolet curable resin. In particular, by forming the hydrophilic resin film 26 immediately after forming the UV-curable resin film as the protective layer 25, that is, before the UV-curable resin serving as the base is completely cured, the layer boundaries thereof are integrated. As a result, the binding property can be improved.

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.

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.

The hydrophilic resin film 26 may be provided over the entire surface of the protective layer 25. For example, as shown in FIG. 1, the hydrophilic resin film 26 may be provided except for the inner and outer peripheral edges of the protective layer 25. 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 due to the fine surface condition, the printing ink is held in the fine concave portions. A so-called anchor effect for fixing is provided. 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 2.0 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 1.0 to 0.5
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 coding 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 10 μm, and especially when the size is 3 to 5 μm, the solid printability becomes good.

When the surface of the hydrophilic resin film 26 is subjected to the 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 is particularly preferably performed using an ink jet printer. 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 (Iupilon, manufactured by Mitsubishi Gas Chemical) having a diameter of 1.2 mm and a thickness of 1.2 mm is prepared.

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. On this, gold was sputtered to form a reflective layer having a thickness of 100 nm.

Next, an ultraviolet curable resin (SD-1) containing a polyfunctional acrylate monomer as a main component was formed by spin coating.
7: Dainippon Ink) and 230m with a high pressure mercury lamp
j / cm2 of ultraviolet light, cured and cured to a thickness of 10μ.
m of protective layers were formed.

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

Within 30 minutes after the formation of the protective layer, using a 300-mesh screen, this hydrophilic resin solution was screen-printed thereon except for the inner and outer peripheral edges of the protective layer. By irradiating ultraviolet rays, a hydrophilic resin film having a thickness of 15 μm was formed.

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.

[0057]

[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.).
Both the surface roughness of the ink-fixed portion and the surface roughness of the ink-unfixed portion were 0.9 to 0.6 μm. The hardness of the resin was 4H / on gl
ss (2H / on 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 at different places using aqueous black ink. And ink jet printing performance (IJP performance). 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.

[0061]

[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.

[0063]

[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.

[0065]

[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 peeling test (cross-cut test) was performed. It was 100/100 in the film part.

[0067]

As described above, according to the optical information medium of the present invention, the optical information medium has an excellent protection function without causing eccentricity or surface blurring during reproduction or recording, and furthermore has excellent fingerprint and dust. It is possible to provide an optical information medium which has a small appearance and good appearance and is easy to handle.

[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 schematic vertical sectional view of a main part of the optical information medium according to the embodiment.

FIG. 3 is an enlarged schematic longitudinal sectional view of a main part showing an ink fixing state of the optical information medium according to the embodiment of the present invention.

FIG. 4 is an exploded perspective view of a holder and an optical information medium used for printing on the surface of the optical information medium using an inkjet printer.

FIG. 5 is a schematic cross-sectional view of a main part showing an ink jet printer used in an 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 Hydrophilic Resin Film 27 Aqueous Ink

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-64-43826 (JP, A) JP-A-6-60432 (JP, A) JP-A-8-12088 (JP, A) JP-A-8- 102086 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 7/24 G11B 11/105 G11B 23/38 G11B 23/40

Claims (1)

(57) [Claims] 1. A protective layer made of a resin formed on a plate-shaped translucent substrate and adhered directly or via another layer to reproduce and / or read information optically readable by a laser beam. Or UV curing on recordable optical information media
A hydrophilic UV-curable resin film capable of fixing an aqueous printing ink is formed on the protective layer made of a hydrophilic resin,
The surface of the hydrophilic UV-curable resin film has an average roughness Ra
Has a rough surface of 2.0 to 0.1 μm.