JPH10188345A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to write characters, etc., with an ink jet printer without the blurring and repelling of ink by forming a film obtd. by UV curing of a mixture composed of a curing compsn. and fillers as the protective layer exposed on the front surface of an optical recording medium formed by successively laminating a recording layer, a metallic reflection layer and >=2 layers of the protective layers. SOLUTION: The recording layer is formed on an injection molded polycarbonate resin substrate and an Au thin film is formed as the reflection layer thereon by sputtering. The surface of the thin film is spin coated with a UV curing resin and thereafter, the resin is irradiated with UV rays to form the first protective layer which is then subjected to screen printing of the curing compsn. consisting of a hydrophilic polymer, hydrophilic monomer, cation monomer, copolymerizable monomer and radical initiator by mixing the compsn. with the fillers and kneading the mixture with a dispersing machine. The compsn. is then cured by the irradiation with the UV rays to form the hydrophilic surface layer of 20μm, by which the optical recording medium is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly to an optical recording medium whose surface can be written with a writing instrument, an ink jet printer or a sublimation printer.

[0002]

2. Description of the Related Art A read-only optical recording medium such as a compact disk (CD) or a laser disk (LD), which has been widely and widely used at present, stores information by an injection molding method based on a master usually called a stamper. To manufacture substrates with According to this method, it is possible to produce a medium having the same information at low cost and in large quantities, but it is not suitable for producing a small amount of a medium because the stamper is very expensive. Further, with the progress of the information society in recent years, there has been a growing demand for higher density recording than magnetic recording media. Therefore, an optical recording medium has been developed for creating a small amount of information recording medium or for allowing a user to freely record and store data.

[0003] Optical recording media are classified into two types: a write-once type, in which information can be recorded and reproduced, and a rewritable type, in which data can be erased after recording. Among them, a single-recordable write-once compact disc is called a CD-R, which is a normal read-only CD.
Users are gradually increasing because of compatibility with. After the CD-R has been purchased, it is necessary for the user to know what information is recorded on the medium in some way so that the user can write the data after purchasing the medium.

In general, a method of displaying a title or the like is a method of manually writing on a surface with an oil-based felt pen.
Handwriting is not preferred when selling media to end users after data has been entered into the DR. On the other hand, a method of attaching a paper or film label such as a proppy disc has the advantage of printing well-designed characters and pictures on a printer, but if you want to put letters on the entire surface of the disc, a large area donut-shaped label And it is very difficult to stick them together. In addition, when the film is peeled, there is a possibility that the film may be peeled and caught in the apparatus, and thus another method has been desired.

[0005]

From these uses, a method of printing a recorded content using an ink jet printer or the like by applying a hydrophilic coating layer on the side opposite to the light incident surface of the medium has been put into practical use. A CD-R medium having a special surface corresponding to is available on the market.

However, when recording contents and the like are printed by an ink-jet printer or the like, there is a problem that the print portion is blurred or repelled, resulting in insufficient resolution and printing. An object of the present invention is to provide an optical recording medium that solves such a problem and an ink suitable for the medium.

[0007]

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive studies and as a result, have found that an optical recording medium comprising a recording layer, a metal reflective layer, and two or more protective layers sequentially laminated. In, the protective layer exposed on the surface, a curable composition comprising a hydrophilic polymer and a hydrophilic monomer and a copolymerizable monomer and a radical initiator, a cationic monomer is further added, kneaded product of this and a filler Was found to be able to solve the above problem by being obtained by UV curing, and the present invention was achieved.

That is, the present invention provides (1) an optical recording medium comprising a recording layer, a metal reflection layer, and two or more protective layers sequentially laminated on a transparent substrate, wherein the protective layer exposed on the surface is hydrophilic. Polymer, hydrophilic monomer,
A kneaded product of a curable composition comprising a cationic monomer, a copolymerizable monomer and a radical initiator and a filler is prepared by
V. An optical recording medium comprising a material obtained by curing and having the surface of the protective layer printable, and (2) a protective layer made of a UV-curable resin exposed on the surface. , A) 1 to 80 parts by weight of a hydrophilic polymer, b)
20 to 88 parts by weight of hydrophilic monomer, c) cationic monomer 10
To 70 parts by weight, d) 1 to 40 parts by weight of a copolymerizable monomer and e) 0.1 to 10 parts by weight of a radical initiator. Wherein the optical recording medium according to the above (1), wherein the protective layer surface is configured to be printable,
(3) The protective layer made of a UV-curable resin exposed on the surface comprises: a) 10 to 70 parts by weight of a hydrophilic polymer, b) 20 to 78 parts by weight of a hydrophilic monomer, c) 10 to 70 parts by weight of a cationic monomer. 50 parts by weight, d) 1 to 20 parts by weight of a copolymerizable monomer, and e)
The kneaded product of a curable composition comprising 1 to 8 parts by weight of a radical initiator and a filler is obtained by UV-curing, and the surface of the protective layer is configured to be printable (1). (4) The optical recording medium according to any one of the above (1) to (3), wherein the cationic monomer has an amide group and / or an amino group. And (5) the filler contained in the protective layer made of a UV curable resin exposed on the surface is made of a UV curable resin containing an organic filler and / or an inorganic filler having water absorbency and / or oil absorbency, The optical recording medium according to any one of (1) to (4), wherein the total amount of the filler is 1 to 80 parts by weight with respect to 100 parts by weight of the UV curable resin exposed on the surface. Yes, and (6) UV hard exposed on the surface The UV curable resin in which the filler contained in the protective layer made of a resin is a UV curable resin containing an organic filler and / or an inorganic filler having water absorbency and / or oil absorbency, and the total amount of the filler is exposed on the surface. The optical recording medium according to the above (5), which is 5 to 50 parts by weight relative to parts by weight, and (7) the above (1) to (6), wherein the recording layer is made of an organic dye. (8) The optical recording medium according to any one of (1) to (7) above, wherein the protective layer exposed on the surface is printed with an aqueous or oil-based ink. A printable medium comprising: (9) an organic filler and / or an inorganic filler having a water absorbing property and / or an oil absorbing property; and the UV-curable composition according to any one of the above (2) to (6). UV curable ink suitable for forming a simple protective layer.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of an optical recording medium used in the present invention comprises a transparent substrate, a recording layer, a metal reflective layer, and two or more protective layers. Layers may be stacked.

Since the substrate used in the present invention performs reproduction and recording by light, any transparent material can be used. Examples thereof include, but are not limited to, polycarbonate resin, acrylic resin, polystyrene resin, vinyl chloride resin, epoxy resin, polyester resin, polymer materials such as polyolefin, and inorganic materials such as glass. Among these, the mechanical strength of the substrate, the ease of providing grooves and read-only signals, etc.,
It is preferable to use a polycarbonate resin, an acrylic resin, or a polyolefin resin from the viewpoint of economy and economical efficiency, and more preferable is a polycarbonate resin.

The shape of these substrates may be plate-like or film-like, and may be circular or card-like. Further, these substrate surfaces may have guide grooves and pits indicating recording positions, and pits for partially read-only information.
These grooves and pits are usually formed by a known method using a stamper.

The recording layer used in the present invention generally uses an organic dye such as a cyanine-based, phthalocyanine-based, or azo-based dye. These dyes may be substituted with various substituents for solubility in a solvent or recording characteristics. These dyes may be used alone or in combination of two or more.

The recording layer containing the dye described above can be generally formed by a coating method such as spin coating, spray coating or dip coating. Solvent that does not damage the resin substrate when forming the above dye by coating method,
That is, the dye may be dissolved in a solvent that does not substantially dissolve the resin for the substrate and then applied.

In the present invention, the thickness of the recording layer is usually 50 to 20.
0 nm is preferred. When forming a recording layer containing a dye, in addition to the above-described dye, nitrocellulose, ethyl cellulose, acrylic resin, polystyrene resin, a resin such as a urethane resin, a leveling agent, an antifoaming agent, etc. impair the effects of the present invention. It can also be used together in a range that does not exist. Although a recording layer mainly containing an organic dye is described, it is apparent that the present invention can be applied to a medium using an inorganic substance, a polymer, or a metal as the recording layer.

As the reflective layer provided on the recording layer in the present invention, a metal film having a high reflectivity such as gold, silver, aluminum or an alloy thereof is used. These metal reflective layers can be formed by a method such as vapor deposition or sputtering. The thickness of these reflective layers is usually 500 to 20.
It is preferably about 00 °. The reflective layer can be formed by multilayering.

A protective layer is provided on the reflective layer. For example, there are those which polymerize by a general radical reaction of acrylate or methacrylate, and those which perform cationic polymerization by light such as epoxy. These resins may be polymerized singly or as a mixture of monomers and oligomers. It is also possible to dilute with a solvent and apply.
Among them, a UV curable type is desirable from the viewpoint of workability. When the protective layer is formed, it is performed by a method such as spin coating, dip coating, bar coating, screen printing, etc. In many cases, the spin coating method is used from the viewpoint of workability. These film thicknesses are used in a thickness of 1 μm to 100 μm.
0 μm is desirable.

Not only one protective layer but also two or more protective layers may be laminated, for example, to improve the scratch resistance. It is also possible to print a label or the like entirely or partially on the protective layer by screen printing or the like.

The protective layer exposed on the surface of the present invention is used to sufficiently absorb and fix the ink of an ink jet printer, and particularly, a hydrophilic polymer, a hydrophilic monomer and a cationic monomer, and a copolymerizable polymer. By forming a kneaded product of a curable composition comprising a monomer and a radical initiator and a filler with a UV-curable resin obtained by UV-curing, the ink absorption speed is increased, and good absorption and fixing properties are obtained. , Resolution is obtained.

The filler contained in the protective layer made of a UV-curable resin exposed on the surface includes water-absorbing and / or
Alternatively, an organic filler and / or an inorganic filler having an oil absorbing property is used.

Specific examples of the organic filler include acrylic resin, polyacrylate, polymethacrylate, styrene resin, polyester, polycarbonate,
Modified melamine resin fine particles, fine particles of polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, rubber and the like, cross-linked fine particles of these polymers, and powders of lignin, protein, cellulose and the like are also included. At this time, in order to prevent the ink of the oil-based pen or the water-based pen from repelling, it is necessary that the filler to be added has a high water-absorbing or oil-absorbing property. From this viewpoint, lignin, protein, and cellulose powders are preferred. It is particularly effective when it contains a solvent that does not easily dry, such as ink for an ink jet printer.

Specific examples of the inorganic filler include silica,
Talc, clay, calcium carbonate, calcium silicate,
Examples include barium sulfate, mica, diatomaceous earth silica, aluminum hydroxide, alumina, zirconium oxide, and zirconium hydroxide. When the silica filler is manufactured by crushing, sufficient effects cannot be obtained due to low water absorption or oil absorption. However, in the case of synthetic silica or the like in which fine primary particles are collected to form secondary particles, it is effective because the solvent of the oil-based pen or the aqueous pen penetrates into the gaps between the secondary particles.

In the case of inorganic fillers, the oil absorption is often measured. Generally, it is represented by the amount of linseed oil absorbed per 100 g of filler according to the JIS-K-5101 method. In the present invention, it is 5 ml / 100 g (filler amount).
The above is desirable, and furthermore, 15 ml / 100 g (filler amount)
The above is more desirable. Although there is no general method for measuring the amount of water absorption, it is preferable that the amount of water absorbed into the filler when water is dropped on the filler is used. In the case of a filler whose surface is treated with fluorine, water droplets become spherical without being absorbed by the filler. If such a filler is used, both oily and water-based inks repel without drying.

The organic filler and the inorganic filler can be used alone, but can be used together for improving the drying property after writing, adjusting the viscosity of the ink, or improving the color tone. At this time, the mixing ratio can be variously changed depending on the purpose.

Incidentally, a filler having a thickening action such as Aerosil may be added for adjusting the viscosity of the ink.
Various additives can be used according to other purposes. Leveling agent, defoamer, defoamer, thickener,
Examples thereof include an anti-sagging agent, an anti-settling agent, a pigment dispersing aid, a wetting agent and a dispersing aid.

As the resin containing the filler, a UV curable resin is preferable. Solvent-containing resins such as thermosetting resins require a complicated drying step, and organic solvents released by drying are not preferable in terms of working environment. The UV-curable resin is usually used without a solvent, but when a filler is added to the UV-curable resin, the amount of addition is limited due to an increase in viscosity. Therefore, the drying speed of the ink becomes slow, which is not preferable for this purpose. In order to further improve the characteristics of the resin layer, it is preferable to further devise the resin layer. That is, this resin layer has one or more hydrophilic polymers, one or more hydrophilic monomers, one or more crosslinkable monomers, one or more cationic monomers, and a radical initiator. UV curable resin containing an agent is used.

The addition of the hydrophilic polymer to the layer exposed on the surface facilitates fixing of the ink adhered to the surface. The hydrophilic polymer includes homopolymers and copolymers such as polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, polyacrylamide, polyvinyl pyrrolidone, and polyethylene oxide. In the case of a copolymer, a combination with a non-hydrophilic polymer may be used. This may be added one kind, 2
You may use in combination of types or more. The more you add, the better the ink of the pen and printer will be fixed,
Since the viscosity of the resin is so high that a film cannot be formed or the polymer is precipitated, the total amount of the hydrophilic polymer in the resin composition is 1 to 80 parts by weight. Desirably 10
It is good to use 70 parts by weight.

In the present invention, the hydrophilic polymer is dissolved in a highly polar hydrophilic monomer. Hydrophilic monomers include hydroxy (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, phenoxyhydroxypropyl (meth) acrylate, chlorohydroxypropyl (meth) acrylate, diethylene glycol mono (Meth) acrylate,
Triethylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, dipropylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, glycerin mono (meth) acrylate, glycerin di (meth)
Acrylate, pentaerythritol tri (meth) acrylate, phenylglycidyl ether (meth) acrylate, dipentaerythritol penta (meth) acrylate, bisphenol A epoxy resin di (meth) acrylate having an OH group in the molecule, Dimethyl (meth) acrylamide, diethyl (meth) acrylamide, acroylmorpholine, N-vinylpyrrolidone, 2-ethoxyethyl (meth) acrylate,
-Highly polar substances such as methoxyethyl (meth) acrylate, ethyl carbitol (meth) acrylate, and glycidyl (meth) acrylate are used. It may be monofunctional or a difunctional or higher functional monomer.

These monomers uniformly dissolve a hydrophilic polymer like a solvent, and when characters are written on a resin layer with a pen or an ink jet printer containing a large amount of an organic solvent or water, bleeding and bleeding are suppressed. In particular, when a polymer having high hydrophilicity is used, the hydrophilic polymer is easily dissolved when a monomer having a highly polar group such as a hydroxyl group, a carboxyl group, an amino group, or an amide group in the molecule is used. In order to improve the solubility of the hydrophilic polymer, water, alcohols such as methanol, ethanol, propanol, butanol, pentanol and hexanol, ethers such as dimethyl ether, diethyl ether, methyl ethyl ether and dipropyl ether, acetone and cyclohexane And some solvents such as ketones such as dichloroethane and halogen such as chloroform. The total amount of the hydrophilic monomer in the resin composition is 20 to 88 parts by weight. Preferably, 20 to 78 parts by weight are added.

In the present invention, by adding a cationic monomer to the layer exposed on the surface, characters or the like are written on the surface of the layer exposed on the surface with a pen or an ink jet printer containing a large amount of an organic solvent or water. In this case, bleeding and bleeding can be further suppressed, and the resolution can be significantly improved. Particularly, a cationic monomer having a group such as an amino group or an amide group in the molecule is effective.

Examples of the cationic monomer having an amino group or an amide group include dimethyl (meth) acrylamide, diethyl (meth) acrylamide, dimethylaminomethyl (meth) acrylate, and dimethylaminomethyl (meth).
Acrylate quaternary salt, dimethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate quaternary salt, diethylaminomethyl (meth) acrylate, diethylaminomethyl (meth) acrylate quaternary salt, diethylaminoethyl (meth) acrylate, diethylaminoethyl (Meth) acrylate quaternary salts, methylenebis (meth) acrylate, acryloylmorpholine, N-vinylpyrrolidone and the like are used. The total amount of the cationic monomer contained in a part of the hydrophilic monomer is 10
Add to ~ 70 parts by weight. Preferably, the amount is 10 to 50 parts by weight.

To these are added crosslinking monomers. These include trimethylolpropane tri (meth) acrylate, acrylated isocyanurate, 1,4 butanediol di (meth) acrylate, 1,6 hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, dicyclo Pentadienyl di (meth)
Acrylate, pentaerythritol tetra (meth) acrylate and the like are used. In the case where the hydrophilic monomer is polyfunctional such as glycerin di (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipentaerythritol hexa (meth) acrylate, it is not always necessary to add the hydrophilic monomer. By adding the crosslinkable monomer, the crosslink density of the protective layer exposed on the surface is increased, and the coating film hardness is increased. The total amount of the crosslinking monomer in the resin composition is 1 to 40 parts by weight. Preferably, 1 to 20 parts by weight is added.

When a hydrophilic polymer is added to a mixture of a hydrophilic monomer, a cationic monomer and a crosslinkable monomer which can be cured by UV light, the viscosity increases. Addition of fillers to these mixtures further increases the viscosity. For this reason, if the viscosity of the monomer is too high, the viscosity becomes very high after the addition of the filler, and the application becomes impossible. In this experiment, it is necessary to select a UV-curable resin having as low a viscosity as possible.

To these, a radical initiator is added. Examples of the radical initiator include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-diethoxyacetophenone and 4'-phenoxy-2,2-dichloroacetophenone. Examples include acetophenone type, propiophenone type such as 2-hydroxy-2-methylpropiophenone, anthraquinone type such as 2-chloroanthraquinone, and thioxanthone type such as 2,4-diethylthioxanthone. The amount added at this time is 0.1 to 10 parts by weight of the resin. Preferably, it is 1 to 8 parts by weight. At this time, one photoinitiator may be used, or two or more photoinitiators may be combined.

The filler is used in an amount of 1 to 100 parts by weight of the resin.
8080 parts by weight, preferably 5-50 parts by weight. Considering storage stability, it is desirable to stir uniformly with a disper or the like.

The method of forming the layer exposed on the surface includes a bar coating method, a blade coating method, an air knife coating method, a roll coating method, and a screen printing method. Screen printing is particularly desirable because it can be improved. In the present invention, a solvent can be used for the UV-curable resin in order to improve the coating property when the resin layer is formed. Film thickness 1
Although it is designed to be about 100 μm, it is preferably 1 to 20 μm in consideration of the influence on the warpage of the disk. If a single protective layer is provided on the reflective layer, the protective layer may be provided on the entire surface of the disk or may be provided partially.

The applied resin layer is cured by UV light.
When cured by exposure to UV light, 150-2000 mJ / c
m^TwoGive energy. Preferably 250-1000mJ
/ Cm ^TwoDedicate At this time, the coating film hardens in a few seconds. Hardening
UV lamp used for mercury lamp, high pressure mercury lamp, ultra high pressure mercury
Lights and metal halide lamps are desirable.

Layers may be further partially overlapped with portions where characters are written or printed. For example, portions other than where different titles, numbers, dates, and the like are written in each medium may be described with a common company name, mark, medium product name, software name recorded in the medium, and the like. In such a case, several layers may be further stacked by screen printing, offset printing, or the like.

When writing on the protective layer exposed on the surface configured as described above, an oil-based pen, an aqueous pen containing water and a water-soluble organic solvent, an oil-based stamp, and an aqueous stamp can be used. In addition, an ink jet printer, a sublimation printer, or a thermal transfer printer using an oil-based or water-based ink can also be used.

[0039]

EXAMPLES The present invention will be described below in more detail with reference to examples, but embodiments of the present invention are not limited thereto.

EXAMPLE 1 A recording layer made of a phthalocyanine dye was applied to an injection molded polycarbonate resin substrate having a spiral groove (depth 140 nm, width 0.5 μm, pitch 1.6 μm) having a thickness of 1.2 mm and a diameter of 120 mm by using an octane solution. A film was formed by spin coating. Thickness 1 as a reflective layer on this recording layer
An Au thin film of 00 nm was formed by sputtering. After spin-coating an ultraviolet-curable resin, Die Cure Clear SD-17 (manufactured by Dainippon Ink and Chemicals, Inc.), the film was irradiated with ultraviolet rays to form a 6 μm-thick first protective layer.
30 parts by weight of polyvinylpyrrolidone-vinyl acetate copolymer (7: 3, 50% ethanol solution, manufactured by Tokyo Chemical Industry Co., Ltd.), 2-hydroxypropyl acrylate 30
1 part by weight, 25 parts by weight of dimethylacrylamide, 15 parts by weight of trimethylolpropane triacrylate, and 5 parts by weight of Darocur 1173, a radical initiator.
00 parts by weight of synthetic silica TOKUSIL GU
20 parts by weight (manufactured by Tokuyama Soda Co., Ltd.) were mixed and kneaded with a disper. After screen printing, it was cured by irradiating ultraviolet rays to form a 20 μm hydrophilic surface layer to obtain a CD-R medium. When characters were directly printed on this resin layer by an ink jet printer on the hydrophilic surface layer, a sufficient resolution was obtained without the printed portion bleeding or bleeding.

Example 2 After forming a recording layer and a reflective layer as in Example 1, an ultraviolet-curable resin Die Cure Clear SD-17 was further formed on this reflective layer.
(Dai Nippon Ink Chemical Industry Co., Ltd.) was spin-coated and irradiated with ultraviolet light to form a 6 μm-thick first protective layer.
20 parts by weight of a urethane acrylate oligomer, 40 parts by weight of hydroxyethyl acrylate, 20 parts by weight of methylenebisacrylamide, 15 parts by weight of 1,4-butanediol diacrylate, and a radical initiator Darocure 1173
To 5 parts by weight of resin and 100 parts by weight of organic filler containing protein as the main component (average particle size 10 μm)
Was mixed with 10 parts by weight and kneaded with a disper. After screen-printing it, it is cured by irradiating ultraviolet rays,
A CD-R medium was formed by forming a hydrophilic surface layer of μm. When characters were directly printed on this resin layer by an ink jet printer on this hydrophilic surface layer, a sufficient resolution was obtained without the printed portion bleeding or bleeding.

Comparative Example 1 A CD-R medium was prepared in the same manner as in Example 1 except that dimethylacrylamide was omitted. When characters were directly printed on the hydrophilic surface layer with an ink jet printer on the resin layer, finely drawn character portions were blurred, and sufficient resolution could not be obtained.

Comparative Example 2 A CD-R medium was prepared in the same manner as in Example 2, except that methylenebisacrylamide was omitted. When characters were directly printed on the hydrophilic surface layer with an ink jet printer on the resin layer, finely drawn character portions were blurred, and sufficient resolution could not be obtained.

[0044]

As is apparent from the results of the examples and comparative examples, according to the present invention, an optical recording medium on which characters and the like can be written by an ink jet printer without ink bleeding or repelling is provided. can do.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor: Masayuki Kawamoto 1900 Togo, Mogo-shi, Chiba Mitsui Toatsu Chemical Co., Ltd.

Claims (9)

[Claims] An optical recording medium comprising a recording layer, a metal reflection layer, and two or more protective layers sequentially laminated on a transparent substrate.
A protective layer exposed on the surface was obtained by UV-curing a kneaded product of a filler and a curable composition comprising a hydrophilic polymer, a hydrophilic monomer, a cationic monomer, a copolymerizable monomer and a radical initiator. An optical recording medium comprising a protective layer and a surface of the protective layer being printable. 2. The protective layer comprising a UV-curable resin exposed on the surface comprises: a) 1 to 80 parts by weight of a hydrophilic polymer, b) 20 to 88 parts by weight of a hydrophilic monomer, c) 10 to 10 parts by weight of a cationic monomer.
A kneaded product of a curable composition comprising 70 parts by weight, d) 1 to 40 parts by weight of a copolymerizable monomer, and e) 0.1 to 10 parts by weight of a radical initiator, and a filler obtained by UV curing. 2. The optical recording medium according to claim 1, wherein said protective layer surface is printable. 3. The protective layer made of a UV-curable resin exposed on the surface comprises: a) 10 to 70 parts by weight of a hydrophilic polymer,
b) a curable composition comprising 20 to 78 parts by weight of a hydrophilic monomer, c) 10 to 50 parts by weight of a cationic monomer, d) 1 to 20 parts by weight of a copolymerizable monomer, and e) 1 to 8 parts by weight of a radical initiator. 3. The optical recording medium according to claim 1, wherein the surface of the protective layer is made printable, which is obtained by UV-curing a kneaded product of a binder and a filler. 4. The optical recording medium according to claim 1, wherein the cationic monomer has an amide group and / or an amino group. 5. The filler contained in a protective layer made of a UV curable resin exposed on the surface is made of a UV curable resin containing an organic filler and / or an inorganic filler having water absorbency and / or oil absorbency. The optical recording medium according to any one of claims 1 to 4, wherein the total amount is 1 to 80 parts by weight based on 100 parts by weight of the UV curable resin exposed on the surface. 6. The filler contained in a protective layer made of a UV-curable resin exposed on the surface is made of a UV-curable resin containing an organic filler and / or an inorganic filler having a water absorbing property and / or an oil absorbing property. The optical recording medium according to claim 5, wherein the total amount is 5 to 50 parts by weight based on 100 parts by weight of the UV curable resin exposed on the surface. 7. The recording layer according to claim 1, wherein the recording layer comprises an organic dye.
The optical recording medium according to any one of the above. 8. The optical recording medium according to claim 1, wherein the protective layer exposed on the surface is printed with an aqueous or oil-based ink. 9. A printable protective layer comprising an organic filler and / or an inorganic filler having a water absorbing property and / or an oil absorbing property and the UV curable composition according to any one of claims 2 to 6. UV curable ink.