Limited play data storage media and method for limiting access to data thereon

Description: TECHNICAL FIELD [0001] The present invention relates to a storage medium. More specifically, the present invention relates to a limited reproduction storage medium.

BACKGROUND ART [0002] Magneto-optical media, magneto-optical media, and magneto-optical media are the main resources of high-performance storage technology that enables high storage capacity at an affordable price per 1 megabyte of storage capacity. The use of optical media is compact discs (CDs), digital versatile discs (DVDs) such as multi-layered structures such as DVD-5 and DVD-9 and multifaceted formats such as DVD-10 and DVD-18, and photomagnetic. Formats such as discs (MO) and other write-once and rewritable formats such as CD-R, CD-RW, DVD-R, DVD-RW, DVD + RW, DVD-RAM (collectively, "" It is called "information storage medium") and is widely used for audio, video and computer data applications. In these formats, the data is encoded on the board as a digital data string. In pre-recorded media for optical media such as CDs, the data are usually pits or grooves formed on the surface of the plastic substrate by methods such as injection molding, stamping and the like.

[0003] Depending on the application, it is desirable to limit the life of the optical disc. For example, a trial computer program is offered to potential customers to solicit the purchase of software. Such programs are intended for use within a limited period of time. In addition, music and movies are currently rented for a limited time. For each of these uses, the disc must be returned at the end of the term. There is a need for machine-readable optical discs that do not need to be returned at the end of the rental period. Limited playback discs provide a solution to these problems.

[0004] Limited playback discs are manufactured by various methods. One method consists of forming a disc in which the reflective layer is protected by a porous layer so that the reflective layer is oxidized after a lapse of a predetermined period. When the reflective layer reaches a certain oxidation level, the disc becomes unreadable. The problem with the other limited reproduction techniques described above is that these techniques can be nullified. If the method of imposing playback restrictions on an optical disc can be easily disabled by a customer or microenterprise, the disc is no longer "limited playback". For example, if an optical disc is made non-reproducible by a coating or material, a disc that can be used indefinitely can be obtained by simply removing or modifying the coating and / or the material.

[0005] There is a strong demand on the movie studio side to protect intellectual property. Commercializing a limited reproducible information storage medium that could easily be invalidated and become an information storage medium that can be used indefinitely would pose an unacceptable risk of loss of intellectual property.

[Patent Document] US Pat. No. 4,906,498 [Patent Document] US Patent No. 6343063 [Patent Document] European Patent Application Publication No. 385341 [Patent Document] Japanese Patent Application Laid-Open No. 59-124891 [Patent Document] Japanese Patent Application Laid-Open No. 02-018728 [Patent Document] Japanese Patent Application Laid-Open No. 02-037539 [Patent Document] International Publication No. 01/93257 Pamphlet [0006] The present invention relates to a) the first substrate, b) the reflective layer, c) Data layer provided between the substrate and the reflective layer, d) Reactive layer consisting of one or more carriers and one or more reactive materials, and e) Oxygen permeability at 25 ° C of about 0.01 ~ Provided is a limited reproducible optical storage medium for data, comprising an optically transparent second substrate of about 1.35 Barrer, a second substrate between the reactive layer and the laser incident surface.

BEST MODE FOR CARRYING OUT THE INVENTION [0007] Although many terms are used in the present specification and claims, they are defined to have the following meanings.

[0008] Even if it is described in the singular form, it means including a plurality of cases unless it is clear from the context.

[0009] The term "as appropriate" means that the event or situation described following the term may or may not occur, such description may or may not occur. Including cases.

[0010] The reproduction time is defined as the total time during which the limited reproduction type information storage medium can be reproduced without error in the reproduction apparatus.

[0011] This time, it was found that the reproduction time of the limited reproduction type information storage medium can be effectively extended by using an optically transparent substrate having an oxygen transmission rate of about 0.01 to about 1.35 Barre at 25 ° C. In addition, 1Barrer = 10^-10cm³(STP) cm / cm² S cmHg. The optically transparent substrate is located between the reactive layer and the laser entrance surface and is called the "second substrate". When exposed to oxygen, a essentially colorless reactive material, such as leucomethylene blue, oxidizes to form an opaque or translucent layer (eg, methylene blue, a dark blue dye). An information storage medium having an opaque / translucent layer can no longer be reproduced by a medium reproduction device. By adjusting the time required for the opacity, a limited reproduction type information storage medium having a desired life for a predetermined application can be obtained by using the dye layer. When the dye layer is initially separated from the air by a second substrate with a thickness of 0.5 to 0.7 mm, using a substrate with an oxygen permeability of about 0.01 to about 1.35 Barre at 25 ° C, the oxygen permeability of the second substrate The time it takes for the dye layer to become opaque is significantly longer than when using an information storage medium with a value greater than about 1.35 Barrer.

[0012] The effectiveness of the second substrate, which prolongs the time to opacity of the dye layer, depends to some extent on the rate at which oxygen diffuses through the second substrate into the reactive dye layer. Oxygen leakage through the second substrate begins after the lag time estimated by the following equation (Crank, The Mathematics of Diffusion, 2nd ed., Oxford University Press, 1975).

[0013] L²/ (6D) In the equation (Formula 1), L is the thickness of the second substrate and D is the diffusion coefficient of oxygen in the second substrate. The diffusion coefficient D can be obtained from the permeability P and the solubility S by D = P / S, where S is typically 6.69 × 10 for oxygen in polycarbonate.^-3[cc] / ([cc] [cmHg]) (Encyclopedia of Polymer Science, vol VI, p.568). In addition, D is cm²In / s units. The thickness of the second substrate is 0.6 mm, and the material of the second substrate has an oxygen permeability of 1.39 Barrer and a diffusion coefficient of 2.1 × 10.^-8cm²For / s polycarbonate, the lag time is about 8 hours. However, the diffusion coefficient is 0.7 × 10^-8cm²When reduced to / s, the transmittance is about 0.47 Barrer and the lag time is about 24 hours if the solubility does not change.

[0014] In certain optical media formats, the thickness of the second substrate may vary from the range specified for DVD. For example, in the proposed Blu-ray video disc, the data layer is isolated from the air by a 100 μm film. In this case, it is necessary to lower the transmittance of the membrane in order to obtain a sufficient diffusion lag time. For example, using a 100 μm thick polycarbonate film with a transmittance of 1.39 Barrer, the lag time is expected to be 13 minutes. For membranes with a transmittance of 0.013 Barrer, the lag time is expected to be 24 hours.

[0015] The information storage medium includes a second substrate having low birefringence at the reading laser wavelength and high light transmittance (that is, readable by an optical medium device). Typically, the reading laser wavelength is in the range of about 390 to about 430 nm (blue and violet lasers) or in the range of about 630 to about 650 nm (red laser). The second substrate is made of a material having sufficient optical transparency (eg, birefringence of about ± 100 nm or less) so that the information storage medium can be read by the medium device. Theoretically, any plastic material that exhibits these properties can be used as the second substrate.

[0016] The information storage medium includes a second substrate, a first substrate, a reactive layer, a data layer, and a reflective layer. The information storage medium may further include a light absorption layer and an adhesive layer. The plastic materials used for the first and second substrates are the parameters of the subsequent processing process (eg, the layering of subsequent layers), such as the sputtering temperature from about room temperature (about 25 ° C) to about 150 ° C, afterwards. Should be able to withstand storage conditions (eg, in high temperature automobiles with temperatures as high as about 70 ° C). That is, it is desirable that the plastic material has sufficient thermal stability to prevent deformation during the deposition process of various layers and storage by the end user. Usable plastic materials include thermoplastic resins having a glass transition temperature of about 100 ° C or higher, preferably about 125 ° C or higher, more preferably about 140 ° C or higher, and even more preferably about 200 ° C or higher (eg,). , Polyetherimide, polyetheretherketone, polysulfone, polyethersulfone, polyetherethersulfone, polyphenylene ether, polyimide, polycarbonate, etc.), but materials with a glass transition temperature of more than about 250 ° C are more preferable, especially m. -Examples include polyetherimides in which phenylenediamine is replaced with sulfonedianiline or oxydianiline, and polyimides, and combinations containing one or more of these plastic materials. Generally, polycarbonate is used.

[0017] Some possible examples of materials for the first and second substrates include amorphous materials, crystalline materials and semi-crystalline thermoplastic materials such as polyvinyl chloride, polyolefins (not particularly limited, but linear and linear and). Including cyclic polyolefins, polyethylene, chlorinated polyethylene, polypropylene, etc.), polyesters (not particularly limited, but polyethylene terephthalate, polybutylene terephthalate, polycyclohexylmethylene terephthalate, etc.), polyamides, polysulfones (not particularly limited, but hydride polysulfones, etc.) ), Polyethylene, polyetherimide, polyethersulfone, polyphenylene sulfide, polyetherketone, polyetheretherketone, ABS resin, polystyrene (not particularly limited, but not limited to, hydride, syndiotactic and tactical polystyrene, polycyclohexylethylene, Styrene-co-acrylonitrile, styrene-co-maleic anhydride, etc.), polybutadiene, polyacrylate (including, but not limited to, polymethylmethacrylate (PMMA), methylmethacrylate-polyetherpolymer, etc.), polyacrylonitrile, polyacetal, polycarbonate, etc. Polyphenylene ether (not particularly limited, but derived from 2,6-dimethylphenol, copolymer with 2,3,6-trimethylphenol, etc.), ethylene-vinyl acetate copolymer, polyvinyl acetate, liquid crystal polymer, ethylene -Tetrafluoroethylene copolymers, aromatic polyesters, polyvinyl fluoride, vinylidene polyvinylfluoride, vinylidene chloride and tetrafluoroethylene (eg, Teflon®), but are not limited thereto.

[0018] The terms "polycarbonate" and "polycarbonate composition" as used herein include compositions having structural units of the following formula (I).

[0019] [Chemical formula 1]<img file="JP4166754B2_D0001.tif" />[0020] In the formula, R¹About 60% or more of the total number of groups are aromatic organic groups, the rest of which are aliphatic, alicyclic or aromatic groups. Preferably R¹Is an aromatic organic group, more preferably a group of the following formula (II).

[0021] [Chemical 2]<img file="JP4166754B2_D0002.tif" />[0022] In the formula, A¹And A²Are monocyclic divalent aryl groups, respectively, and Y¹Is A¹And A²It is a bridging group with 0, 1 or 2 atoms intervening with. In an exemplary embodiment, A¹And A²Is separated by a single atom. Non-limiting examples of this type of group include -O-, -S-, -S (O)-, -S (O).₂)-, -C (O)-, Methylene, Cyclomethylene, 2- [2.2.1]-Bicycloheptylidene, Ethylidene, Isopropylidene, Neopentylidene, Cyclohexylidene, Cyclopentadecylidene, Cyclododecylidene , Adamanthilidene, etc. In another embodiment, A¹And A²There is no atom that separates from, and a specific example is biphenol. Bridge base Y¹May be a hydrocarbon group or a saturated hydrocarbon group (eg, methylene, cyclohexylidene or isopropylidene) or a heteroatom such as -O- or -S-.

[0023] Polycarbonate is A¹And A²Can be produced by the reaction of dihydroxy compounds separated by only one atom. The term "dihydroxy compound" as used herein includes, for example, a bisphenol compound having the following general formula (III).

[0024] [Chemical 3]<img file="JP4166754B2_D0003.tif" />[0025] In the formula, R^aAnd R^bRepresents hydrogen, halogen atom or monovalent hydrocarbon group independently, p and q are each independently an integer of 0 to 4, and X^aRepresents one of the groups of equation (IV) below.

[0026] [Chemical 4]<img file="JP4166754B2_D0004.tif" />[0027] In the formula, R^cAnd R^dRepresent each independently a hydrogen atom or a monovalent linear or cyclic hydrocarbon group, R^eIs a divalent hydrocarbon group.

[0028] Some representative non-limiting examples of suitable dihydroxy compounds are divalent phenols and dihydroxy-substituted aromatic hydrocarbons as disclosed in the name or formula (general or specific formula) in US Pat. No. 4,217,438. There is hydrogen. Specific examples of the bisphenol compound represented by the formula (III) include 1,1-bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, and 2,2-bis (4). -Hydroxyphenyl) Propane (hereinafter referred to as "bisphenol A" or "BPA"), 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) octane, 1,1- Bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) n-butane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxy-3-methylphenyl) propane (Hereinafter referred to as "DMBPA"), bis (hydroxyaryl) such as 1,1-bis (4-hydroxy-t-butylphenyl) propane, 2,2-bis (4-hydroxy-3-bromophenyl) propane. ) Alcan, 1,1-bis (4-hydroxyphenyl) cyclopentane, 9,9'-bis (4-hydroxyphenyl) fluorene, 9,9'-bis (4-hydroxy-3-methylphenyl) fluorene, 4 , 4'-Biphenol, as well as 1,1-bis (4-hydroxyphenyl) cyclohexane and 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane (hereinafter referred to as "DMBPC" or "BCC") Such bis (hydroxyaryl) cycloalkanes, as well as combinations containing one or more of these bisphenol compounds can be mentioned.

[0029] If it is desired to use a carbonate copolymer instead of a homopolymer, a polycarbonate obtained by polymerizing two or more kinds of dihydric phenols, or a dihydric phenol and a glycol, a hydroxy-terminated or acid-terminated polyester, or a dibase. Copolymers with acids, hydroxy acids or aliphatic diacids can also be used. In general, useful aliphatic diacids have about 2 to about 40 carbon atoms. The preferred aliphatic diacid is dodecanedioic acid.

[0030] Polyarylate and polyester-carbonate resins or blends thereof can also be used. Branched polycarbonates and blends of linear and branched polycarbonates are also useful. Branched polycarbonate can be produced by adding a branching agent during polymerization.

[0031] Such branching agents are well known and include polyfunctional organic compounds having three or more functional groups and mixtures thereof, wherein the functional groups are hydroxyl, carboxyl, anhydrous carboxyl, haloformyl or these. There are combinations. Specific examples include trimellitic acid, trimeritic acid anhydride, trimeritic acid trichloride, tris-p-hydroxyphenylethane, isatin-bis-phenol, tris-phenol TC (1,3,5-tris ((p-hydroxy)). Phenyl) isopropyl) benzene), tris-phenol PA (4 (4 (1,1-bis (p-hydroxyphenyl) -ethyl) α, α-dimethylbenzyl) phenol), 4-chloroformylphthalic anhydride, trimesin There are combinations containing one or more of these branching agents, such as acids, benzophenone tetracarboxylic acids, and the like. The branching agent can be added at a level of about 0.05 to about 2.0% by weight based on the total weight of the substrate. Examples of branching agents and methods for producing branched polycarbonate are described in US Pat. Nos. 3635895 and 4001184. In the present invention, all types of polycarbonate end groups are envisioned.

[0032] Preferred polycarbonate is A¹And A²Each of them is p-phenylene and Y¹Is based on bisphenol A, which is isopropylidene. Preferably, the weight average molecular weight of the polycarbonate is in the range of about 5000 to about 100,000 atomic mass units, more preferably in the range of about 10000 to about 65000 atomic mass units, and most preferably about 15000 to about 35000 atomic mass units. Within the range of units.

[0033] In monitoring and evaluating polycarbonate synthesis, it is particularly important to measure the concentration of fleece products present in the polycarbonate products. The formation of prominent fleece products can cause polymer branching and uncontrollable melting behavior. As used herein, the terms "fleece" and "fleece product" mean the repeating unit of formula (V) below in polycarbonate.

[0034] [Chemical 5]<img file="JP4166754B2_D0005.tif" />[0035] In the formula, R^a, R^b, P and q are for equation (III), X^aIs the divalent group described for formula (III).

[0036] The polycarbonate composition may contain various additives usually blended in this type of resin composition. Such additives include, for example, fillers or reinforcing materials, heat stabilizers, antioxidants, light stabilizers, plasticizers, antistatic agents, mold release agents, additional resins, foaming agents, and the like. Examples include combinations containing one or more agents.

[0037] The second substrate is usually the above-mentioned thermoplastic resin, provided that the oxygen transmission rate at 25 ° C. is about 0.01 to about 1.35 Barrer. Generally, the second substrate is a polycarbonate, a polycarbonate copolymer or a polycarbonate blend. Typically, examples of polycarbonates having an oxygen permeability of about 0.01 to about 1.35 Barre at 25 ° C include polycarbonates containing structural units corresponding to structural formulas (VI) and structural formulas (VII).

[0038] [Chemical 6]<img file="JP4166754B2_D0006.tif" />[0039] In the formula, R¹, R², R⁴And R⁵Are independently H or C₁-C₆Alkyl and R³Is C_3-20Aliphatic ring with halogen, C as appropriate_1-20Alkyl, C_3-20Cycloalkyl, C_3-20May be substituted with aryl, or C_3-6May be condensed with an aromatic ring, R⁶And R⁷Are independently C₁-C₆Alkyl, phenyl, C₁-C₆Selected from the group consisting of alkyl-substituted phenyls or hydrogens, n is an integer from 1 to 4, p is an integer from 1 to 4, q is an integer from 1 to 4, and s is an integer from 1 to 4. is there.

[0040] Typical examples of the unit of the structural formula (VI) are not particularly limited, but 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane (DMBPC), 1,1-bis (4-hydroxy). -3-Methylphenyl) cyclopentane, 1,1-bis (4-hydroxy-3-methylphenyl) cycloheptan, 1,1-bis (4-hydroxy-3-methylphenyl) -3,3,5- Includes residues of trimethylcyclohexane (DMBPI), fluorenylidene-9-bis (3-methyl-4-hydroxybenzene) DMBPF and mixtures thereof. DMBPC residues and DMBPF residues are the most preferred structural units (VIs).

[0041] Typical examples of the unit of the structural formula (VII) are not particularly limited, but are 2,2-bis (4-hydroxy-3-methyl) propane (DMBPA) and 4,4'-(l-phenylethylidene). ) Residues of bis (2-methylphenyl) (DMbisAP) can be mentioned.

[0042] In one embodiment of the invention, the polycarbonate contains from about 10 to about 100 mol% of DMBPC residues. DMBPC can be easily synthesized from cyclohexanone and orthocresol.

[0043] In one embodiment of the invention, the polycarbonate contains from about 10 to about 100 mol% of DMBPA residues. DMBPA can be easily synthesized from acetone and orthocresol.

[0044] In addition, examples of polycarbonate having an oxygen permeability of about 0.01 to about 1.35 Barre at 25 ° C include polycarbonate containing structural units corresponding to structural formulas (VIII) and (IX).

[0045] [Chemical 7]<img file="JP4166754B2_D0007.tif" />[0046] In the formula, R⁸Is selected from divalent aliphatic hydrocarbon groups, divalent aromatic groups and divalent aliphatic ether groups, R⁹And R¹⁰Are independently monovalent hydrocarbon groups and halogen groups, X is a trivalent hydrocarbon group, t is an integer of 0 to 4, and u is an integer of 0 to 4.

[0047] In a preferred embodiment of structural formula (VIII), R⁸Is a divalent alkylene, cycloalkylene, divalent alkylene ether or cycloalkylene ether group. The preferred alkylene group has about 1 to about 20 carbon atoms and may be a linear alkylene group or a branched alkylene group. Preferred cycloalkylene groups have about 4 to about 7 ring carbon atoms. More preferably, R⁸Is a linear divalent ethylene group-CH₂-CH₂-Or linear divalent butylene group-CH₂-CH₂-CH₂-CH₂-.

[0048] R⁸The divalent aliphatic ether group represented by has the following general formula.

-(R'-O)_vIn the -R -formula, R and R are independently alkylene or cycloalkylene groups, and v is a positive number having an average value of about 1 to about 10. The preferred alkylene group represented by R and R has about 1 to about 10 carbon atoms, and may be a branched alkylene group or a linear alkylene group. Preferred cycloalkylene groups represented by R and R have ring carbon atoms of about 4 to about 7. Preferably, both R and R are linear ethylene groups, where v is 1.

[0050] In a preferred embodiment of structural formula (IX), t and u are 0 or 1, and R⁹And R¹⁰Are independently monovalent aliphatic groups, preferably alkyl and cycloalkyl groups. Preferred alkyl groups have about 1 to about 20 carbon atoms. Specific examples of preferred alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, tertiary butyl, pentyl and neopentyl, with methyl being most preferred. Preferred cycloalkyl groups have about 4 to about 7 ring carbon atoms. Specific examples of preferred cycloalkyl groups include cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl and cycloheptyl. 1 or more R⁹And R¹⁰If the substituents are present, they may be the same or different. Preferably R⁹And R¹⁰Are all methyl groups, most preferably the methyl group is at the 3,3'position with respect to the X of the aromatic ring.

[0051] X preferably represents a trivalent aliphatic group having about 1 to about 6 carbon atoms. Most preferably, X is a trivalent aliphatic group having 5 carbon atoms or a trivalent aliphatic group having 6 carbon atoms.

[0052] In general, the aromatic ring of structural formula (IX) is bonded to the same carbon atom in the carbon chain represented by X, and the cyano group is bonded to one of the terminal carbons of X.

[0053] A polycarbonate copolymer or blend having a reduced oxygen permeability may be used. For example, the monomer may be copolymerized with BPA to synthesize a polycarbonate having a reduced oxygen permeability. Examples of monomers include aliphatic glycols, ortho-substituted bisphenols, diester bisphenols such as 4,4- [2,2-oxybis (ethylene-1-oxycarbonyl) diphenols], 5,5-bis (5,5-bisphenols). There are cyano-substituted bisphenols such as 4-hydroxyphenyl) hexanenitrile as well as aromatic dihydric phenols. Polycarbonate may be blended with a polymer having a low oxygen permeability to reduce the oxygen permeability of the entire polycarbonate blend. Examples of low oxygen permeability polymers that can be blended include polyarylates, some oxygen shielding grade nylons, polyvinyl acetate, polyvinyl alcohol, polyvinylidene chloride, polyethylene terephthalate and other polyesters. Furthermore, the present invention also includes copolymers of BPA with structural formulas (VI), (VII), (VIII) or (IX) to produce polymeric polycarbonates with reduced oxygen permeability.

[0054] In the present invention, the oxygen permeability of the second substrate can be lowered by adding a low molecular weight additive to the polycarbonate. Examples include anti-plasticizers, pigments, mold release agents, heat stabilizers, UV absorbers and the like. Specific examples of antiplasticizers that can be dispersed on a polycarbonate substrate to reduce oxygen permeability include dimethylphthalate and diphenylphthalate (Macromolecules). 27,7041-7048,1994) and other anti-plasticizers disclosed in US Pat. No. 3,386,935. Further, the oxygen scavenger may be dispersed on the polycarbonate substrate in order to reduce the oxidation rate (and the reflectance decrease rate) of the dye coating. Specific examples of deoxidizers that can be dispersed in polycarbonate without reducing optical permeability include polyunsaturated fatty acids such as ascorbic acid, trihydroxybenzoic acid, and linoleic acid, and other oxidizing polydiene or oxidizing polyethers. There are unsaturated hydrocarbons, ascorbic acid compounds, polyamides such as MXD6, which is a condensed polymer of m-xylene diamine and adipic acid, and other oxidizing organic compounds. See, for example, International Publication No. 01/83318, and U.S. Pat. Nos. 5049624, 5211875, 5075372, and 5529833. Metal catalysts such as cobalt, copper and rhodium compounds may be used in combination with oxidizing organic compounds to efficiently remove oxygen. Most preferred catalysts include cobalt neodecanoate (II), N, N'-dialycylidene ethylenediamine cobalt (II) (CoSalen), and other cobalt salts.

[0055] Generally, the thickness of the second substrate is about 0.5 mm to about 0.7 mm. In another embodiment of the invention, the thickness of the second substrate is from about 0.05 mm to about 0.3 mm.

[0056] A catalyst may be used to accelerate the processing of the first substrate material or the second substrate material (for example, the production of polycarbonate by a melting method) or to control the properties (for example, viscosity) of the substrate material. .. Specific examples of the catalyst that can be used include tetraalkylammonium hydroxide and tetraalkylphosphonium hydroxide, and diethyldimethylammonium hydroxide and tetrabutylphosphonium hydroxide are preferable. The catalyst may be used alone or in combination with deactivation such as acid (eg phosphoric acid). Further, water may be injected into the polymer melt during compounding and removed as water vapor from the vent to remove residual volatile compounds.

[0057] Information storage media are first manufactured by forming substrate materials using conventional reactors capable of appropriately mixing various precursors, such as single-screw or twin-screw extruders, kneaders, blenders, etc. it can. The extruder should be maintained at a temperature high enough to melt the substrate material precursor without causing decomposition. For polycarbonate, for example, a temperature in the range of about 220 ° C to about 360 ° C, preferably a temperature in the range of about 260 ° C to about 320 ° C can be used. Similarly, the residence time in the extruder should be controlled to minimize decomposition. A maximum dwell time of about 2 minutes or more can be used, with a maximum of about 1.5 minutes being preferred and a maximum of about 1 minute being particularly preferred. Even if the mixture is appropriately filtered by melt filtration, screen pack or a combination thereof to remove inconvenient contaminants or decomposition products before extruding into the desired shape (usually pellets, sheets, webs, etc.). Good.

[0058] After the production of the plastic resin composition is finished, it may be molded into a substrate by various molding techniques, processing techniques or a combination thereof. Available techniques include injection molding, film casting, extrusion, press molding, blow molding, stamping and the like. Once the substrate is manufactured, it includes additional processing such as electroplating, coating techniques (spin coating, spray coating, vapor deposition, screen printing, painting, immersion, etc.), lamination, sputtering, etc., as well as one or more of these processing techniques. The combination may be used to provide the desired layer on the substrate. Usually, the thickness of the substrate is about 600 μm or less.

[0059] An example of a limited regenerative polycarbonate data storage medium includes an injection-molded polycarbonate substrate. Other layers that can be placed on the substrate include a data layer, a dielectric layer, a reactive layer, an adhesive layer, a reflective layer, a protective layer, a second substrate, a light absorbing layer, and a combination including one or more of these layers. is there.

[0060] On recordable media, the data is laser encoded. The laser-irradiated active data layer undergoes a phase change, thereby forming a series of highly reflective or non-reflective regions that make up the data stream. In these formats, the laser beam first passes through the substrate and then reaches the data layer. At the data layer, the beam is reflected or unreflected according to the encoded data. The laser light then returns through the substrate and enters the photodetector, where the data is interpreted. Therefore, the data layer is placed between the substrate and the reflective layer. Data layers for optical applications are typically pits, grooves or combinations thereof on the substrate layer. Preferably, the data layer is embedded in the substrate surface. Typically, injection molding-compression techniques are used to mold the substrate and the mold is filled with a molten polymer as defined herein. The mold may include preforms, inserts and the like. By cooling the polymer system and compressing it while it is at least partially melted, the desired surface structure (eg, pits and grooves) arranged in a spiral, concentric or other aligned state is the desired portion of the substrate (eg, pits and grooves). That is, it is stamped on one side or both sides of the desired area).

[0061] The data layer that can be used for magnetic or optomagnetic applications may contain any material as long as it can store readable data, examples of which are oxides (eg silicon oxide). Rare earth element-transition metal alloys, nickel, cobalt, chromium, tantalum, platinum, terbium, gadolinium, iron, boron, etc., and alloys and combinations containing one or more of these, organic dyes (eg cyanine or phthalocyanine dyes), and There are, but are not limited to, inorganic phase change compounds (eg TeSeSn, InAgSb, etc.).

The protective layer protects the medium from dust, oil and other contaminants, the thickness of which can be greater than about 100 μm and less than about 10 Å, preferably no more than about 300 Å in some embodiments. A thickness of about 100 Å or less is particularly preferred. The thickness of the protective layer is usually, at least in part, determined by the type of read / write mechanism used, such as magnetism, light or magneto-optical. Possible protective layers include, in particular, corrosion resistant materials such as gold, silver, nitrides (eg silicon nitride, aluminum nitride, etc.), carbides (eg, silicon carbide, etc.), oxides (eg, silicon dioxide, etc.), polymer materials (eg, silicon dioxide, etc.). For example, polyacrylates and polycarbonates), carbon films (diamonds, diamond-like carbons, etc.), and combinations containing one or more of these materials.

[0063] The dielectric layer is typically located on one or both sides of the data layer and is often used as a thermal control layer, the thickness of which can usually be greater than or less than about 1000 Å and less than or equal to about 200 Å. It can also be made smaller like. Usable dielectric layers include nitrides (eg, silicon nitride, aluminum nitride, etc.), oxides (eg, oxidation, etc.), among other materials that are environmentally friendly and preferably non-reactive with surrounding layers. There are combinations that include aluminum), sulfides (eg, zinc sulfide), carbides (eg, silicon carbide), and one or more of the materials described above.

[0064] The reflective layer should be thick enough to reflect a sufficient amount of energy (eg, light) to allow data acquisition. Generally, the reflective layer can have a thickness of up to about 700 Å, but a thickness of about 300 to about 600 Å is generally preferred. Possible reflective layers include materials capable of reflecting a particular energy field, including metals (eg, alloys and mixtures containing one or more of the metals mentioned above, such as aluminum, silver, gold, silicon, titanium). is there.

[0065] The reactive layer typically contains both a polymer matrix and a reactive material. The reactive layer initially has sufficient transparency to allow data reading by the information storage medium device, but later blocks data reading by the device (eg, a sufficient amount of incident light at the laser wavelength of a given device). It is necessary to form a layer (which absorbs reflected light or a combination thereof). Typically, a layer having an initial reflectance of about 50% or more from the reflective layer can be used, an initial reflectance of about 65% or more is preferable, and an initial reflectance of about 75% or more is particularly preferable. After the medium has been exposed to oxygen, eg, air, for a desired period of time (eg, the permissible regeneration time of the medium), the reflectance of the layer is about 45% or less, preferably about 30% or less, more preferably about 20% or less, particularly preferably. Should be less than about 10%.

The reactive material can be introduced into the storage medium as a coating formulation or blended in an adhesive formulation. Examples of the reactive layer include an oxygen sensitive dye in the PMMA coating adjacent to the reflective layer or a reactive dye in the adhesive layer between the substrate and the reflective layer.

[0067] Usable reactive materials include reaction products containing oxygen-sensitive leucomethylene blue or reduced methylene blue, brilliant cresil blue, basic blue 3, toluidine 0, and one or more of these reactive materials. There are combinations. The structure of these materials is shown below.

[0068] [Chemical 8]<img file="JP4166754B2_D0008.tif" />[0069] The synthesis method and the production of the colored methylene blue dye by oxygen-dependent reoxidation are shown below.

[0070] [Chemical 9]<img file="JP4166754B2_D0009.tif" />[0071] Generally, the critical reflectance at which the limited reproduction information storage medium becomes reproducible (or non-reproducible) is less than about 20%, and more generally, the critical reflectance is less than about 10%.

[0072] In addition, the substrate may contain a dye that selectively filters the light that reaches the reactive layer. Photobleaching resistance is improved by limiting the wavelength of light that passes through the substrate and reaches the reactive layer. Anthraquinones, perylenes, perinones, indantrons, quinacridones, xanthenes, oxazines, oxazolines, thioxanthenes, indigoids, thioindigoids, naphthalimides, cyanins, xanthenes, methines, lactones , Cumarins, bis-benzoxathiolthiophene (BBOT), naphthalenetetracarboxyde derivatives, monoazo and diazo pigments, triarylmethanes, aminoketones, bis (styrel) biphenyl derivatives, and one of these colorants Appropriate photofilterability can be obtained by blending a dye of a combination of chemical substances including seeds or more into a substrate. The photofilter dye may be appropriately combined with a deoxidizing material, an additive, and a copolymer of structures (VI), (VII), (VIII), and (IX) that reduce oxygen permeability.

[0073] In addition to the oxygen-sensitive leuco dye described above, since the data storage medium is of a limited regeneration type, many other dyes and light-shielding materials can be synthesized and introduced into the reactive layer. For example, other reactive materials that can be used are found in US Pat. Nos. 4404257 and 5815484. Further, the reactive material may contain a mixture containing any one or more of the above-mentioned reactive materials.

[0074] The amount of reactive material in the reactive layer depends on the desired lifetime of the information storage medium. The amount of the reactive material in the reactive layer can be adjusted to about 0.1% by weight based on the total weight of the reactive layer, but is preferably about 1% by weight. The upper limit of the reactive material is about 10% by weight, preferably about 7% by weight, even more preferably about 6% by weight, even more preferably about 5% by weight.

The desired lifetime of the information storage medium depends on the rate at which the reactive material oxidizes to form the laser light absorbing dye. The rate of oxidation depends on the concentration of reactive material (eg, leuco dye) and oxygen in the reactive layer. The oxygen concentration in the reactive layer as a function of time after exposing the information storage medium to air depends on the permeability of oxygen passing through the substrate and the presence or absence of oxygen scavengers.

[0076] For example, when leucomethylene blue (LMB) is oxidized to methylene blue, the oxidation rate is expressed by the following rate equation.

[0077] d [MB] / dt = k_eff[O₂] [LMB] (Formula 2), k_effIs the effective rate coefficient and depends on environmental and chemical factors such as temperature, pressure, acidity and mobility of the reactants in the reactive dye layer without particular limitation. The time required for oxygen to diffuse to the substrate can be approximated by Equation 1. Therefore, the lower the diffusion coefficient and transmittance, the longer the diffusion lag time until the leuco dye starts to oxidize. Oxygen concentration in the reactive layer [O₂] Can be reverted to the diffusion coefficient of oxygen by solving Fick's second law of diffusion, which is subject to appropriate boundary conditions at each layer in the medium (Crank, <u style="single">The Mathematics of Diffusion</u>, 2nd ed., Oxford University Press, 1975). If the reactive dye is in the adhesive, the oxygen concentration at the interface between the transparent substrate and the reactive layer [O₂] Is as follows.

[0078] [O₂] = [O₂]_∽In erfc {L / (4Dt) ^ .5} (Formula 3), erfc is a complementary error function, L is the thickness of the substrate in cm, and t is in seconds (s). It's time. cm²It is assumed that the diffusion coefficient of oxygen expressed in / s units is constant. Oxygen concentration in the substrate in equilibrium [O₂]_∞Can be interpreted as the solubility of oxygen in mole / L units.

[0079] The reactive material is preferably mixed with a carrier because it forms a reactive layer by depositing on the substrate surface, impregnating at least a part of the substrate surface, or combining deposition and impregnation. When the reactive material is compounded in the coating formulation, carriers are typically present in the range of about 65-85%, preferably about 70-80%, based on the total weight of the coating formulation. When the reactive material is compounded in the adhesive formulation, the carrier typically ranges from about 90% to about 99.9%, and more typically from about 95% to about, based on the total weight of the adhesive formulation. It is in the range of 99.5%. Usable carriers include thermoplastic acrylic polymers, polyester resins, epoxy resins, polythiolenes, UV curable organic resins, polyurethanes, thermosetting acrylic polymers, alkyd resins, vinyl resins, etc., as well as one or more of these carriers. There are combinations that include. Polyesters include reaction products of aliphatic dicarboxylic acids (eg fumaric acid or maleic acid) and glycols (eg ethylene glycol, propylene glycol, neopentyl glycol, etc.), as well as reaction products and mixtures containing one or more of these. There is.

[0080] Epoxy resins that can be used as carriers include epoxy materials in the form of monomers, dimers, oligomers or polymers with one or more epoxy functional groups. For example, there are reaction products of bisphenol A and epichlorohydrin, reaction products of epichlorohydrin and phenol-formaldehyde resin, and the like. Other organic resins can be in the form of mixtures of polyolefins and polythiols, as shown in Kehr et al., U.S. Pat. Nos. 3,69395 and 3697402.

[0081] The term "thermoplastic acrylic polymer" as used herein includes a thermoplastic polymer obtained by polymerizing one or more acrylic acid ester monomers or methacrylic acid ester monomers. These monomers are represented by the following general formula VII.

[0082] CH₂= CWCOOR^f In equation (VII), W is a hydrogen or methyl group and R^fIs an alkyl group, preferably an alkyl group having about 1 to about 20 carbon atoms. R^fSome non-limiting examples of alkyl groups represented by are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, hexyl and the like. is there.

[0083] To give some non-limiting specific examples of the acrylate monomer represented by the formula VII, methyl acrylate, isopropyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, There are 2-ethylhexyl acrylate and so on. Some non-limiting specific examples of the methacrylic acid ester monomer represented by the formula VII include methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, isobutyl methacrylate, propyl methacrylate and the like, and these. There are reaction products and combinations containing one or more of the above.

[0084] The copolymers of the acrylic acid ester monomer and the methacrylic acid ester monomer described above are also included in the term thermoplastic acrylic polymer used in the present specification. Preferably, the thermoplastic acrylic polymer is a copolymer of poly (methyl methacrylate / methacrylic acid). The production of the thermoplastic acrylic polymer by polymerizing the acrylic acid ester monomer and the methacrylic acid ester monomer may be carried out by a known polymerization method. Thermoplastic acrylic polymer is typically about 0.300 cm³g^-1Less than, more typically about 0.250 cm³g^-1Less than, most typically about 0.200 cm³g^-1Has an intrinsic viscosity of less than.

[0085] In order to improve the adhesiveness of the reactive layer to the substrate, a primer may be used between them. Thermoplastic acrylic polymers useful as primers include acrylic homopolymers derived from a single type of acrylic acid ester monomer, methacrylic homopolymers derived from a single type of methacrylic acid ester monomer, and two or more different acrylic acid ester monomers. , Two or more different methacrylic acid ester monomers or copolymers derived from an acrylic acid ester monomer and a methacrylic acid ester monomer, and combinations containing one or more of these primers.

[0086] A mixture of two or more of the above-mentioned thermoplastic acrylic polymers, for example, two or more different acrylic homopolymers, two or more different acrylic copolymers, two or more different methacrylic homopolymers, two or more different Methacrylic copolymer, acrylic homopolymer and methacrylic homopolymer, acrylic copolymer and methacrylic copolymer, acrylic homopolymer and methacrylic copolymer, mixture of acrylic copolymer and methacrylic homopolymer, and reaction products thereof. Mixtures can also be used.

[0087] If appropriate, various coating techniques such as painting, dipping, spraying, spin coating, screen printing and the like can be used to deposit the reactive layer on the substrate. For example, the reactive layer may be with a relatively volatile solvent, preferably an organic solvent, that is substantially inert to the polycarbonate (ie, does not attack or adversely affect the polycarbonate) but is capable of dissolving carriers. Can be mixed. In general, the carrier concentration in the solvent is about 5% by weight or more, preferably about 10% by weight or more, and the upper limit of the polymer is about 25% by weight, preferably about 20% by weight or less. Examples of suitable organic solvents include ethylene glycol diacetate, butoxyethanol, methoxypropanol, lower alkanols and the like. Generally, the solvent concentration in the coating liquid is about 70% by weight or more, preferably about 75% by weight or more, and the upper limit range of the polymer is about 90% by weight, preferably about 85% by weight or less.

[0088] The reactive layer may optionally contain various additives such as matting agents, surfactants, thixotropes and the like, as well as reaction products and combinations containing one or more of these additives.

[0089] The thickness of the reactive layer depends on the type of reactive material used, the concentration of the reactive material in the reactive layer, and the desired absorption properties initially and after the desired period of the layer. When the reactive material is added to the coating formulation, the thickness of the reactive layer is about 1 μm, preferably about 2 μm, even more preferably about 3 μm. The upper limit of the thickness is about 15 μm or more, preferably about 10 μm or less, and more preferably about 6 μm or less. When the reactive material is added to the adhesive, the reactive layer is in the range of 30-80 μm, more preferably 40-60 μm.

Light intensity measured by an optical head detector, reflected from a metallized reflective layer for uncoated discs or limited reproduction discs in which the reactive layer is not absorbing the initial light I_initialIs the intensity of the laser beam incident on the optical disc I_OAnd formula I_initial/ I_O= R_initialThere is a relationship of. Reflectance factor R_initialConsiders the intrinsic reflectance of the reflective layer and the attenuation of light intensity due to absorption and scattering in all layers at time 0. Subsequent exposure of the reactive layer to oxygen reduces the amount of light that the dye absorbs and reflects off the optical head detector and returns. Absorbance A in the reactive layer can be calculated as follows using the Veil-Lambert law.

[0091] A = -log (I)_t/ I_{o o}) = εcl (Formula 4), I_iIs the incident light on the reactive layer, and ε is the molar extinction coefficient of the dye (about 54000 L / mole at 650 nm for methylene blue).^-1cm^-1), I is the thickness of the reactive layer, and c is the concentration of dye that changes over time. Therefore, the reflectance R can be approximated by the following equation with respect to a limited reproduction disc having a light absorption reactive layer that absorbs light in both paths passing through the light absorption layer.

R = I / I_O= R_inital10^(-2ecl)^____(Formula 5) Formula 5 can be used to calculate the dye concentration and reactive layer thickness required to obtain a particular reflectance. For example, if the reactive layer thickness is 3 μm, the dye is methylene blue and is present in the reactive layer at a concentration of 0.027 mole / L, and the reflectance of the disc without the light absorbing dye is 70%, the disc with the light absorbing dye The reflectance of is expected to be 10%.

[0093] Typically, the molded substrate is degassed before the reactive layer is placed on the substrate. In addition, the reactants used to form the reactive layer are typically retained in an inert environment. After the storage medium has been manufactured, the disc is usually kept in an inert environment until it is ready for use. Typically, the degassing can be carried out with an inert gas such as nitrogen, argon or helium.

[0094] There may be an adhesive layer to which any combination of the above layers can be adhered. The adhesive layer can form an oxygen permeable layer and does not substantially interfere with the transmission of light from the data reader through the medium (eg, substantially at the wavelength of light used by the device). Any material may be used as long as it is transparent and / or has a reflectance from the medium of about 50% or more, preferably about 65% or more, and more preferably about 75% or more). If appropriate, the adhesive layer may be a reactive layer, that is, the adhesive layer may contain an oxygen-sensitive dye. Possible adhesive materials include UV materials such as acrylates (eg, crosslinked acrylates), silicone hardcoats, and reaction products and combinations containing one or more of the materials described above. Other examples of UV materials are described in US Pat. Nos. 4179548 and 4491508. Examples of useful monoacrylate monomers include butyl acrylate, hexyl acrylate, and dodecyl acrylate. Examples of useful polyfunctional acrylate monomers include diacrylates, triacrylates, tetraacrylates, and combinations thereof.

[0095] The adhesive layer may contain only one of the polyfunctional acrylate monomers, or may contain a mixture (and its UV photoreaction product) containing one or more of the polyfunctional acrylate monomers. A preferred coating composition, although preferred, comprises a mixture of two polyfunctional monomers (and its UV photoreaction product), preferably a mixture of diacrylate and triacrylate (and its UV photoreaction product). In some cases, it contains monoacrylate. The adhesive coating may optionally contain a non-acrylic UV curable aliphatic unsaturated organic monomer in an amount of about 50% by weight or less of the uncured adhesive coating. Such unsaturated organic monomers include, for example, materials such as N-vinylpyrrolidone, styrene, and reaction products and combinations containing one or more of the above materials.

[0096] When the adhesive layer contains a mixture of acrylate monomers, the weight ratio of diacrylate to triacrylate is preferably in the range of about 10/90 to about 90/10. Examples of a mixture of diacrylate and triacrylate include a mixture of hexanediol diacrylate and pentaerythritol triacrylate, a mixture of hexanediol diacrylate and trimethylolpropane triacrylate, a mixture of diethylene glycol diacrylate and pentaerythritol triacrylate, and diethylene glycol di. Examples include a mixture of acrylate and trimethylolpropan triacrylate.

The adhesive layer may contain a photosensitizer (ie, an amount effective to achieve photocuring of the adhesive coating) of the photoinitiator. Generally, the amount is about 0.01% by weight (preferably about 0.1% by weight) to about 10% by weight (preferably about 5% by weight) based on the total weight of the adhesive coating. Possible photoinitiators include blends of ketone and hindered amine materials that form a suitable hard film upon exposure to UV light. The weight ratio of the ketone compound to the hindered amine compound is preferably about 80/20 to about 20/80. Usually about 50/50 or about 60/40 mixture is quite satisfactory.

Other possible ketone photoinitiators used in non-oxidizing atmospheres such as nitrogen include benzophenone and other acetophenone, benzyl, benzaldehyde and O-chlorobenzaldehyde, xanthone, thioxanthone, 2-chlorothioxanthone. , 9,10-Phenantrenquinone, 9,10-Anthraquinone, Methylbenzoin ether, Ethylbenzoin ether, Isopropylbenzoin ether, α, α-diethoxyacetophenone, α, α-dimethoxyacetophenone, 1-phenyl-1,2-propane There are diol-2-o-benzoyloxime, α, α-dimethoxy-α-phenylacetophenone, phosphine oxide and the like. In addition, reaction products and combinations containing one or more of the photoinitiators described above are also included.

Adhesive layers also include matting agents, surfactants, thixotropes, UV light stabilizers, UV absorbers, and / or stabilizers such as resorcinol monobenzoate and 2-methylresorcinol dibenzoate, as well as these. Combinations containing one or more and reaction products may be appropriately included. The stabilizer may be present in an amount of about 0.1% by weight (preferably about 3% by weight) to about 15% by weight based on the weight of the uncured UV layer.

[Examples] [0100] The present invention will be specifically described below with reference to examples so that those skilled in the art can appropriately carry out the present invention, but the examples do not limit the present invention.

【0101】<u style="single">Example 1</u> In a bottle, 60 g of Elvacite 2010 poly (methyl methacrylate) (manufactured by Ineos Acrylics) was added to 300 g of 1-methoxy-2-propanol and rolled to dissolve in a roller mill to dissolve PMMA 1-methoxy-2- A propanol solution was prepared. The solution was transferred to a flask and heated to about 80 ° C. with a stream of nitrogen slowly flowing over the surface of the solution. A cannula tube was used to transfer the degassing solution to a degassing bottle closed with a rubber diaphragm under nitrogen pressure.

[0102] 1.2 g of methylene blue trihydrate and 0.80 g of camphorsulfonic acid were mixed with 40 g of 1-methoxy-2-propanol in a 100 mL flask equipped with a rubber diaphragm to prepare a leucomethylene blue solution. Using syringe needles at both the nitrogen inlet and outlet, the stirred mixture was heated in a 90 ° C water bath, slowly passing a nitrogen stream through the flask. While hot, 4.2 mL of tin 2-ethylhexanoate (II) was added via syringe to reduce methylene blue to dark amber leucomethylene blue. 0.6 mL of the fluidity regulator BYK-301 (manufactured by BYK Chemie) was added to this solution. To prepare the PMMA / leucomethylene blue coating solution, the leucomethylene blue coating solution was sucked into a syringe, passed through a 0.2 μm syringe filter, and then injected into the PMMA solution.

【0103】<u style="single">Example 2</u> In this example, the production of a prior art disc using a sandwich configuration is illustrated. A solution was prepared in the same manner as in Example 1 except that the following amounts of raw materials were used.

[0104] [Table 1]<img file="JP4166754B2_D0010.tif" />Using a spin coater at 800 rpm for 60 seconds, a 0.6 mm metallized BPA-polycarbonate DVD first substrate was coated with a PMMA / leucomethylene blue base coat using the above solution. The average coating thickness was about 3 μm. One disc coated with PMMA / leucomethylene blue base coat was stored overnight in a nitrogen chamber, and then UV resin Daicure SD-640 was supplied in a thin ring shape to the middle part of the coated metallized DVD first substrate. A non-metallized BPA-polycarbonate second substrate was then placed on top of the first substrate disk with a ring of UV resin. The sandwich was rotated at 1000 rpm for 10 seconds to evenly disperse the UV adhesive. The sandwich was then passed under a flash xenon UV lamp for 25 seconds. The sandwich was stored in a nitrogen chamber for 48 hours or longer, then exposed to air and the dynamic characteristics of reflectance were measured.

【0106】<u style="single">Example 3</u> In this example, the production of the limited reproduction disc of the present invention is illustrated. Limited playback discs were manufactured as described in Example 2. However, instead of the prior art BPA-PC substrate, a non-metallized second substrate molded from BPA / DMBPC / DDDA terpolymer (molar ratio 49:49: 2) was used. The metallized first substrate was also molded from BPA / DMBPC / DDDA terpolymer. The synthesis of terpolycarbonate is described in US Pat. No. 6,395364.

[0107] The coated discs of Examples 2 and 3 were left at room temperature, during which the average% reflectance was measured. % With the decrease in reflectance, the color of the disc changed from substantially colorless to blue. Figure 1 shows the temporal dynamics of the reflectance of a limited-edition DVD manufactured in a sandwich configuration using a BPA-PC substrate (Example 2) and a BPA / DMBPC / DDDA terpolymer substrate (Example 3).

【0108】<u style="single">Example 4</u> As described in Example 2, a limited playback disc was manufactured. However, instead of the prior art BPA-PC substrate, a non-metallicized second substrate molded from DMBPC homopolymer was used. The metallized first substrate was molded from BPA / DMBPC / DDDA terpolymer.

【0109】<u style="single">Example 5</u> A 0.6 mm non-metallized BPA-polycarbonate DVD semi-disc was coated with PMMA / leucomethylene blue basecoat using the dye solution used in Example 2 using a spin coater at 800 rpm for 60 seconds. The average coating thickness was about 3 μm. One disc coated with PMMA / leucomethylene blue base coat was stored overnight in a nitrogen chamber, and then UV resin Daicure SD-640 was supplied in a thin ring shape to the middle part of the coated metallized DVD first substrate. Next, one of the discs coated with PMMA / leucomethylene blue base coat was placed on top of the top surface of the first substrate disc with a ring of UV resin. The sandwich was rotated at 1000 rpm for 10 seconds to evenly disperse the UV adhesive. The sandwich was then passed under a flash xenon UV lamp for 25 seconds. The sandwich was stored in a nitrogen chamber for at least 48 hours.

【0110】<u style="single">Example 6</u> As described in Example 5, a limited play disc was manufactured. However, instead of the BPA-PC substrate, a non-metallized second substrate molded from BPA / DMBPC / DDDA terpolymer was used. The metallized first substrate was molded from BPA-polycarbonate.

【0111】<u style="single">Example 7</u> As described in Example 5, a limited play disc was manufactured. However, instead of the BPA-PC substrate, a non-metallized second substrate molded from DMBPC homopolycarbonate was used. The metallized first substrate was molded from BPA-polycarbonate. The results of the reflectance dynamic characteristics and delayed dynamic characteristics for Examples 2 to 7 are shown in Table 1 and FIG.

[0112] [Table 2]<img file="JP4166754B2_D0011.tif" />As is clear from the data in Table 1 and FIG. 1, when a polycarbonate substrate having a lower oxygen permeability than BPA-PC is used, the oxidation rate of the reactive dye is reduced, and the playback time of the limited reproduction DVD is reduced. Is extended. The reflective layer is a good oxygen diffusion barrier, and on the time scale in question there is little or no oxygen permeating from the metallized substrate to the dye layer. Therefore, the rate of reflectance decay is largely controlled by the permeation of oxygen through the non-metallized substrate. Comparing Example 5, Example 6 and Example 7, when polycarbonate with a gradual decrease in oxygen permeability is used, the initiation of oxidation (here, the time until the reflectance drops to less than 45%) is shown in BPA-PC. It slows down from 9 hours to 32 hours for BPA / DMBPC / DDDA polycarbonate and even 94 hours for DMBPC-PC homopolymers. The oxygen permeability of these polycarbonates is 1.38, 0.36 and 0.10 Barrer, respectively (J. Applied Polym. Sci. 39, 2083-2096, 1990). The same effect can be seen by comparing the time required for the reflectance to reach 45% in Examples 2, 3 and 4. However, in these samples, the adhesive layer provides an additional oxygen diffusion barrier, which almost doubles the time to reach 45% reflectance. The samples of Example 2, Example 3 and Example 4 were produced with a reactive dye layer between the reflective layer and the adhesive layer, and the initial reflectance in Examples 3 and 4 was the thickness of the reflective layer. It was higher than the other samples due to the increase.) (1) Similar to Examples 5, 6 and 7, when the reactive dye layer is between the non-metallized substrate and the adhesive layer, or (2) the dye is between the adhesive layer and the metallized layer, but the adhesive layer. It is especially important to use a non-metallized substrate with a lower oxygen permeability than BPA-PC if it does not provide sufficient resistance to oxygen diffusion, or (3) the dye is in the adhesive layer. However, the oxygen permeability should not be slow enough to play a limited playback DVD beyond the target destruction time. By changing the composition of the copolymer in the non-metallized substrate, the diffusion lag time can be adjusted to achieve the target fracture time. For example, a BPA / DMBPC copolymer can be used to vary the lag time from 9 hours for BPA-PC to about 100 hours for DMBPC-PC homopolymers.

【0114】<u style="single">Example 8 ~ 15</u> As described in Example 5, a series of limited play discs was manufactured. However, instead of the BPA-PC substrate, a non-metallized second substrate molded from various DMBPC-polycarbonate and DMBPA-polycarbonate, polycarbonate copolymers and polycarbonate blends was used. The metallized first substrate was molded from BPA-PC. Further, a coating liquid was prepared in the same manner as in Example 1 except that the following amounts of raw materials were used.

[0115] [Table 3]<img file="JP4166754B2_D0012.tif" />Similar to Examples 2-7, these samples show that the diffusion lag time can be adjusted to achieve the target failure time by varying the composition of the copolymer in the non-metallized substrate. There is. Table 2 shows the time required to reach the start of reflectance attenuation (measured at a 10% decrease in reflectance) for Examples 8 to 15. The target destruction time measured in the time required to reach 10% reflectance is also shown in the table. FIG. 2 is a graph showing the dynamic characteristics of the reflectance with respect to Examples 8 to 15.

[0117] [Table 4]<img file="JP4166754B2_D0013.tif" /> 【0118】<u style="single">Example 16</u> Equations 2 to 5 were solved at the same time to predict the reduced reflectance of the limited reproduction DVD due to the oxidation of the leuco dye in the reactive layer. Initial concentration of leuco dye and effective rate coefficient k_effAs the parameters such as, the one that most closely matches the reflectance dynamic characteristics of Example 5 was used. Initial reflectance R₀Was assumed to be 65%. The boundary condition was selected as a simulation condition in which an infinitesimal thin reactive layer is placed between the non-metallized substrate and the adhesive layer. Under these environments, the oxygen concentration in the reactive layer when diffusing in the non-metallized substrate can be predicted using Equation 3. Oxygen diffusion coefficient in substrate material is 2 × 10^-8cm²1 × 10 from / s^-9cm²The time dependence of reflectance was calculated in a series of simulations varied up to / s. Oxygen solubility is 6.69 × 10 for a transmission range of 1.35 to 0.067 Barrer.^-3It was assumed to be constant at [cc] / ([cc] [cmHg]). The reflectance dynamic characteristics shown in FIG. 3 obtained from this series of calculation results exemplify that a range of fracture times can be designed for a limited reproduction DVD by using the composition of non-metallized substrates having different oxygen transmission rates. There is. In Fig. 3, the unit of diffusion coefficient (D) is cm.²It is / s, and the unit of transmittance (P) is Barrer.

[0119] Although the preferred embodiments have been exemplified and described above, various modifications and substitutions can be made without departing from the technical idea and technical scope of the present invention. Therefore, it should be understood that the present invention has been described solely for the purpose of illustration, and the examples and embodiments disclosed herein should not be construed as limiting the scope of claims.

BRIEF DESCRIPTION OF THE DRAWINGS [0120] FIG. 1 shows reflectance dynamic characteristics for a limited reproduction DVD in which the oxygen transmission rate of a non-metallized substrate is changed.

FIG. 2 shows reflectance dynamics for a limited playback DVD whose non-metallized substrate is made of various DMBPC-polycarbonate or DMBPA-polycarbonate.

FIG. 3 shows the expected reflectance dynamic characteristics of a series of limited-play DVDs in which the oxygen diffusion coefficient of a non-metallized substrate is changed.