JPH1139715A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the bleeding of ink in particular in printing of a recording medium surface by forming the outermost layer of a substrate of a UV curing resin having a specific compsn. SOLUTION: A recording layer, a metallic reflection layer and a protective layer are successively laminated on a transparent substrate. The outermost layer is formed of a UV curing resin compsn. which contains an org. filler and/or the org. filler, a hydrophilic monomer and a polymer soluble in this hydrophilic monomer and which polymer is a homopolymer or copolymer formed of >=1 kind of monomer selected from a group of alkyl esters of (meth)acrylic acid and an N-alkyl substitution product of (meth)acrylic acid amide. The polymer is preferably a homopolymer of the alkyl ester of the (meth)acrylic acid and the number of carbons of the alkyl group is preferably >=2. The polymer is preferably >=2 kinds of copolymers of the alkyl ester of the (meth)acrylic acid and the total number of carbons of the alkyl group is preferably >=4.

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 a printable optical recording medium. Note that "printable" means that writing with various writing tools and printing with various printers are possible.

[0002]

2. Description of the Related Art An optical recording medium (optical disk) on which information can be written and / or read by a laser has a larger recording capacity and a random access than conventional recording media. It is used as a recording medium in fields such as computer software, game software, and electronic publishing. In particular, a write-once compact disc ("CD-WO" or "CD-
R "), which has the same reflectance as a read-only compact disc, has the characteristic that it can be reproduced by a read-only compact disc player or drive after recording.

In the above-mentioned optical recording medium, for example, when patent information is written, it is desired to print the year of the information on the surface of the optical recording medium. JP-A-7-169100 discloses that a protective layer (outermost layer) is formed from a UV-curable resin composition containing a hydrophilic polymer, a hydrophilic monomer, a water-absorbing and / or oil-absorbing organic filler, and / or an organic filler. There has been proposed a printable optical recording medium comprising:

However, the protective layer of the optical recording medium is
It is said that repelling of the printing ink is prevented, and that the hydrophilic polymer is excellent in fixability of the printing ink. However, the bleeding property of the printing ink is hardly sufficient.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a printable optical recording medium in which bleeding of ink, particularly in printing, is more effectively prevented. An optical recording medium is provided.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that it is surprising that a specific polymer is used in the printing layer of the recording medium described in JP-A-7-169100. In particular, it has been found that bleeding of the printing ink can be more effectively and effectively prevented without impairing the function of preventing repelling of the printing ink and the fixability of the printing ink.

The present invention has been completed based on the above findings, and the gist of the present invention is that an optical recording medium comprising a transparent substrate and at least a recording layer, a metal reflective layer and a protective layer laminated in this order. Wherein at least an organic filler and / or an organic filler, a hydrophilic monomer, and a polymer soluble in the hydrophilic monomer are contained, and the polymer is an alkyl ester of (meth) acrylic acid and (meth) acrylic Forming the outermost layer with a UV-curable resin composition that is a homopolymer or a copolymer formed from one or more monomers selected from the group of N-alkyl-substituted acid amides A printable optical recording medium characterized by the following.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The optical recording medium of the present invention is configured by sequentially laminating at least a recording layer, a metal reflective layer and a protective layer on a transparent substrate.

As the transparent substrate, for example, a polymer material such as a polycarbonate resin, an acrylic resin, a polystyrene resin, a vinyl chloride resin, an epoxy resin, a polyester resin, and an amorphous polyolefin, and an inorganic material such as glass are used. In particular, a polycarbonate resin is preferable because of its high light transmittance and low optical anisotropy.

On the surface of the transparent substrate, guide grooves, pits, etc. (groove information, etc.) indicating recording positions are usually formed. The groove information or the like is usually given when a substrate is made by injection molding or casting, but may be made by a laser cutting method or a 2P method (Photo-Polymer method).

The recording layer is not particularly limited as long as it can be recorded by irradiation with a laser beam, and may be either a recording layer made of an inorganic substance or a recording layer made of an organic substance.

The recording layer made of an inorganic material includes, for example, Tb.Fe.Co and Dy.F.
A rare earth transition metal alloy such as e.Co is used. Also,
Chalcogen-based alloys such as Ge.Te and Ge.Sb.Te that change phases may also be used.

An organic dye is mainly used for the recording layer made of an organic substance. Such organic dyes include macrocyclic azaannulene dyes (phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, etc.), polymethine dyes (cyanine dyes, merocyanine dyes, squalilium dyes, etc.), anthraquinone dyes, azurenium dyes, and metal-containing dyes. Examples include azo dyes and metal-containing indoaniline dyes. In particular, metal-containing azo dyes are preferable because of their excellent durability and light resistance.

The dye-containing recording layer is usually formed by spin coating,
The film is formed by a coating method such as spray coating, dip coating, and roll coating. In this case, the solvent may be a ketone alcohol solvent such as diacetone alcohol or 3-hydroxy-3-methyl-2-butanone, a cellosolve solvent such as methyl cellosolve or ethyl cellosolve, or a perfluoro solvent such as tetrofluoropropanol or octafluoropentanol. Alkyl alcohol solvents, hydroxyethyl solvents such as methyl lactate and methyl isobutyrate are preferably used.

The metal reflection layer is usually made of gold, silver, aluminum or the like, but is preferably made of silver. The metal reflection layer is formed by a vapor deposition method, a sputtering method, or an ion plating method. Note that an intermediate layer may be provided between the metal reflective layer and the recording layer for the purpose of improving the adhesion between the layers or for the purpose of increasing the reflectance.

The protective layer may have two or more layers as necessary. When the number of protective layers is one, the protective layer is the outermost layer. In the present invention, in order to provide a printing function, the outermost layer (protective layer) is a UV curable resin containing a specific polymer, a hydrophilic monomer, and a water-absorbing and / or oil-absorbing organic filler and / or an organic filler. It must be formed from a composition.

As the organic filler, a water-absorbing and / or oil-absorbing filler is used. For example, acrylic resin, polyacrylate, polymethacrylate, styrene resin, polyester, polycarbonate,
In addition to fine particles of modified melamine resin, fine particles of polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, rubber and the like, crosslinked fine particles of these polymers, as well as lignin, protein, cellulose, and silk powders can be mentioned.
In particular, lignin, protein, cellulose, or silk powder is preferable because of high water absorption and oil absorption.

As the inorganic filler, a water-absorbing and / or oil-absorbing filler is used.
Talc, clay, calcium carbonate, calcium silicate,
Examples include barium sulfate, mica, diatomaceous earth silica, aluminum hydroxide, alumina, zirconium oxide, and zirconium hydroxide.

Examples of the hydrophilic monomer include tetrahydrofurfuryl acrylate, hydroxyethyl (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, dimethyl (meth) acrylamide, diethyl (Meth) acrylamide, acryloyl morpholine, N- vinylpyrrolidone, 2
-Ethoxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, ethyl carbitol (meth) acrylate, glycidyl (meth) acrylate,
In addition to 1,6-hexanediol acrylate, monomers having a hydroxyl group or an ether group in the molecule, such as di (meth) acrylate of bisphenol A epoxy resin, and the like can be mentioned.

Incidentally, the aforementioned Japanese Patent Application Laid-Open No. 7-169100
In the printable optical recording medium described in
Polyvinyl alcohol, hydroxyethyl cellulose,
Hydroxypropyl cellulose, polyacrylamide,
Although hydrophilic polymers such as homopolymers and copolymers such as polyvinylpyrrolidone and polyethylene oxide are used, in the present invention, in order to more effectively prevent bleeding of the ink particularly in printing, the polymer is more hydrophobic than the above polymers. Use a polymer with a high molecular weight.

That is, in the present invention, a homopolymer formed from one or more monomers selected from the group consisting of an alkyl ester of (meth) acrylic acid and an N-alkyl substituent of (meth) acrylic amide is used. Use polymers or copolymers. In addition, the N-alkyl substituent of the above-mentioned acrylamide includes a monoalkyl substituent and a dialkyl substituent. Then, specific examples of the above-mentioned polymers include the following polymers (1) to (5).

(1) Homopolymer of alkyl ester of (meth) acrylic acid (2) Copolymer of two or more alkyl esters of (meth) acrylic acid (3) N-alkyl-substituted (meth) acrylamide (4) Copolymer of two or more N-alkyl-substituted (meth) acrylamides (5) Alkyl ester of (meth) acrylic acid and N-alkyl-substituted (meth) acrylamide Copolymer of

The starting monomer for the homopolymer of the above (1) may be a methyl ester of (meth) acrylic acid, but for the purpose of the present invention, a (meth) acrylic compound having an alkyl group having 2 or more carbon atoms. Alkyl esters of acids are preferred.

The starting monomer for the copolymer (2) is preferably a combination of two or more alkyl esters of (meth) acrylic acid in which each alkyl group has a total carbon number of 4 or more.

As the starting monomer for the homopolymer of the above (3), an N-alkyl-substituted (meth) acrylamide having a (substituted) alkyl group having 2 or more carbon atoms is preferable. In the case of a dialkyl-substituted product, the number of carbon atoms in the above alkyl group means the total number of carbon atoms in two alkyl groups.

The starting monomer for the copolymer (4) is preferably a combination of two or more N-alkyl-substituted (meth) acrylic amides in which each alkyl group has a total carbon number of 4 or more.

As the raw material monomer for the copolymer (5), an alkyl ester of (meth) acrylic acid and an N-alkyl-substituted (meth) acrylic amide in which the total number of carbon atoms in each alkyl group is 4 or more are used. Is preferred.

The upper limit of the number of carbon atoms is determined by the solubility of the polymer in the hydrophilic monomer.
Therefore, it is appropriately determined in consideration of the molecular weight of the polymer, the type of the hydrophilic monomer, and the amount of use (dissolution) of the polymer.
Among the above polymers, (1) a copolymer of two or more alkyl esters of (meth) acrylic acid, wherein the total number of carbon atoms of each alkyl group is 4 or more; N of the above (meth) acrylamide
Particularly preferred is an alkyl-substituted copolymer in which the total number of carbon atoms in each alkyl group is 4 or more.

Specific examples of the above polymers include methyl methacrylate: propyl methacrylate copolymer, methyl methacrylate: butyl methacrylate copolymer, ethyl methacrylate: propyl methacrylate copolymer, and ethyl methacrylate: butyl methacrylate copolymer. Polymer, N-ethyl methacrylamide: N-butyl methacrylamide copolymer, N, N-dimethyl methacrylamide:
N, N-dipropyl methacrylamide copolymer and the like.

A crosslinking monomer may be added to the UV-curable resin composition in order to improve the crosslinking density (coating film hardness) of the protective layer. Such crosslinkable monomers include trimethylolpropane tri (meth) acrylate, acrylated isocyanurate, 1,4 butanediol di (meth) acrylate, 1,6 hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate. ) Acrylate, dicyclopentadienyl di (meth) acrylate,
Pentaerythritol tetra (meth) acrylate, cyclodecane triacrylate and the like can be mentioned.

Examples of the radical initiator used in the UV-curable resin composition include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-diethoxyacetophenone, An acetophenone-based radical initiator such as 4'-phenoxy-2,2-dichloroacetophenone, a propiophenone-based radical initiator such as 2-hydroxy-2-methylpropiophenone, and an anthraquinone-based radical initiator such as 2-chloroanthraquinone And thioxanthone-based radical initiators such as 2,4-diethylthioxanthone.

In the UV-curable resin composition, the hydrophilic monomer is used in an amount of usually 20 to 85 parts by weight, preferably 30 to 60 parts by weight.
Parts by weight, the polymer is usually 1 to 80 parts by weight, preferably 5 to 40 parts by weight, the crosslinkable monomer is usually 0 to 40 parts by weight, preferably 1 to 20 parts by weight, and the radical initiator is usually 0.1 to 0.1 parts by weight. The filler is used in an amount of usually from 5 to 70 parts by weight, preferably from 20 to 50 parts by weight, based on 100 parts by weight of the UV curable resin. You.

The optical recording medium of the present invention comprises at least a recording layer, a metal reflective layer and a protective layer sequentially laminated on a transparent substrate, and the outermost layer is formed from the above-mentioned UV-curable resin composition. It is characterized by comprising. When the number of the protective layers is one, the protective layer is the outermost layer. However, the number of the protective layers may be two or more as needed. In such a case, the type of the resin of the lower protective layer is not particularly limited, but a UV curable resin is preferable as in the case of the outermost protective layer. The thickness of the recording layer is usually 10 to 5000 nm, and the thickness of the metal reflection layer is usually 5 nm.
The thickness of the protective layer is usually in the range of 1 to 100 μm. When there are two or more protective layers, the outermost layer formed of the above-mentioned UV-curable resin composition may be formed only in the printing region.

The lower protective layer is formed by applying a UV curable resin by a method such as spin coating, dip coating, bar coating, or screen printing and then irradiating with UV. The outermost protective layer is formed by a bar coating method, a blade coating method, an air knife coating method,
The method is performed by applying the UV curable resin composition by a method such as a roll coating method or a screen printing method and then irradiating with UV. As the UV lamp, a mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, or the like is used. The irradiation energy amount is usually 150 to 20.
00 mJ / cm ² , preferably 250-1000 mJ /
selected from the range of cm ² .

In the optical recording medium of the present invention, writing (recording) and / or reading (reproduction) of information is performed by a laser beam converged to about 1 μm. That is,
Recording is performed on the laser beam irradiated part (recording part) of the recording layer.
It is performed by melting, evaporation, sublimation, deformation, denaturation and the like. Reproduction is performed by reading the difference in reflectance between the laser light irradiated part and the non-irradiated part by using the laser light. As the laser light, a semiconductor laser light is preferably used.

[0036]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Example 1 A solution of a metal-containing azo dye was dropped onto an injection-molded polycarbonate resin substrate (diameter: 5 inches) having a depth of 1600 mm and a width of 0.45 μm and a groove, and rotated at 500 rpm by spin coating. After coating in a number, 30
After drying for a minute, a recording layer was formed.

Next, a silver film having a thickness of 800 ° (80 nm) was formed on the recording layer by sputtering to form a reflective layer. Then, a UV curable resin was spin-coated on the entire surface of the reflective layer, and then cured by irradiating UV rays to form a 5 μm protective layer.

Next, a UV curable resin composition having the composition shown in the following table was applied to the entire surface of the protective layer so as to have a thickness of 14 μm, and then cured by irradiating ultraviolet rays to obtain an optical recording medium of the present invention. .

[0040]

(1) Methyl methacrylate: butyl methacrylate copolymer (copolymerization ratio = 1: 1): 15 parts by weight (2) Tetrahydrofurfuryl acrylate: 20 parts by weight (3) 1,6-hexanediol di Acrylate: 13 parts by weight (4) Cyclodecane triacrylate: 7 parts by weight (5) 2-hydroxy-2-methyl-1-phenyl-propan-1-one (radical initiator): 5 parts by weight (6) Silk fine Powder: 40 parts by weight

The outermost layer of the above-mentioned optical recording medium is provided with an ink jet printer (C
When characters were printed with a D-ROM printer “CP-1000”), no bleeding of the print was observed.

Example 2 The optical recording of the present invention was carried out in the same manner as in Example 1 except that the UV-curable resin composition having the composition shown in Table 2 was used and the coating film thickness was changed to 15 μm. I got the medium.
When characters were printed on the outermost layer of the optical recording medium with an inkjet printer ("CP-1000"), no bleeding of the print was observed.

[0043]

(1) Methyl methacrylate: butyl methacrylate copolymer (copolymerization ratio = 3: 1) (Rohm &: product “Paraloid 60” manufactured by Haus): 15 parts by weight (2) Tetrahydrofurfuryl acrylate: 40 Parts by weight (3) 2-hydroxy-2-methyl-1-phenyl-propan-1-one (radical initiator): 5 parts by weight (4) fine silk powder: 40 parts by weight

Example 3 The optical recording of the present invention was performed in the same manner as in Example 1 except that the UV-curable resin composition having the composition shown in Table 3 was used and the coating film thickness was changed to 15 μm. I got the medium.
When characters were printed on the outermost layer of the optical recording medium with an inkjet printer ("CP-1000"), no bleeding of the print was observed.

[0045]

[Table 3] (1) Ethyl methacrylate: butyl methacrylate copolymer (copolymerization ratio = 1: 1) (Rohm &: manufactured by Haus “Paraloid 66”): 15 parts by weight. Parts by weight (3) 1,6-hexanediol diacrylate: 15 parts by weight (4) cyclodecane triacrylate: 7 parts by weight (5) 2-hydroxy-2-methyl-1-phenyl-propan-1-one (radical (Initiator): 5 parts by weight (6) Silk fine powder: 38 parts by weight

Example 4 The optical recording of the present invention was performed in the same manner as in Example 1 except that the UV-curable resin composition having the composition shown in Table 4 was used and the coating film thickness was changed to 15 μm. I got the medium.
When characters were printed on the outermost layer of the optical recording medium with an inkjet printer ("CP-1000"), no bleeding of the print was observed.

[0047]

(4) (1) N-ethyl methacrylamide: N-butyl methacrylamide copolymer (copolymerization ratio = 1: 1): 15 parts by weight (2) tetrahydrofurfuryl acrylate: 40 parts by weight (3) 2-hydroxy -2-methyl-1-phenyl-propan-1-one (radical initiator): 5 parts by weight (4) Silk fine powder: 40 parts by weight

Example 5 The optical recording of the present invention was performed in the same manner as in Example 1 except that the UV-curable resin composition having the composition shown in Table 5 was used and the coating film thickness was changed to 15 μm. I got the medium.
When characters were printed on the outermost layer of the optical recording medium with an inkjet printer ("CP-1000"), no bleeding of the print was observed.

[0049]

(1) N, N-dimethylmethacrylamide: N, N-dipropylmethacrylamide amide copolymer (copolymerization ratio = 1: 1): 15 parts by weight (2) Tetrahydrofurfuryl acrylate: 20 parts by weight (3) 1,6-hexanediol diacrylate: 15 parts by weight (4) cyclodecane triacrylate: 7 parts by weight (5) 2-hydroxy-2-methyl-1-phenyl-propan-1-one (radical initiator ): 4 parts by weight (6) Fine powder of silk thread: 39 parts by weight

[0050]

According to the present invention described above, there is provided an optical recording medium which can be printed and in which bleeding of ink, particularly during printing, is more effectively prevented.

Claims (6)

[Claims] 1. An optical recording medium comprising a transparent substrate and at least a recording layer, a metal reflective layer and a protective layer sequentially laminated on the transparent substrate, wherein at least an organic filler and / or an organic filler, a hydrophilic monomer, A polymer soluble in a hydrophilic monomer, wherein the polymer is selected from the group consisting of an alkyl ester of (meth) acrylic acid and an N-alkyl substituent of (meth) acrylamide A printable optical recording medium comprising the above outermost layer formed of a UV-curable resin composition that is a homopolymer or a copolymer formed from the above monomers. 2. The optical recording medium according to claim 1, wherein the polymer in the UV-curable resin composition is a homopolymer of an alkyl ester of (meth) acrylic acid, and the alkyl group has 2 or more carbon atoms. . 3. The polymer in the UV-curable resin composition is a copolymer of two or more alkyl esters of (meth) acrylic acid, and the total number of carbon atoms in each of the alkyl groups is 4 or more. An optical recording medium according to claim 1. 4. The UV-curable resin composition according to claim 1, wherein the polymer is a homopolymer of an N-alkyl-substituted (meth) acrylamide and the alkyl group has 2 or more carbon atoms. Optical recording medium. 5. The polymer in the UV-curable resin composition is a copolymer of two or more N-alkyl-substituted (meth) acrylamides, and the total number of carbon atoms in each of the alkyl groups is 4 or more. The optical recording medium according to claim 1. 6. The polymer in the UV-curable resin composition is a copolymer of an alkyl ester of (meth) acrylic acid and an N-alkyl-substituted (meth) acrylic amide, and a total of the above-mentioned respective alkyl groups. 2. The optical recording medium according to claim 1, which has 4 or more carbon atoms.